Original Title: Lightning Protection Engineering Design and Construction Organization Plan (I) The lightning protection project needs to be implemented in an organized and step-by-step manner to ensure the quality and duration of the project. Today, Junhe Electronics takes a project as an example to share with you the template of lightning protection engineering design and construction organization scheme for reference only, as follows: I. Lightning protection design scheme 1. Project overview The project is located in XX Town, XX County, XX Province, which is surrounded by mountains on three sides. The project is located in the south of the XX fault zone. There are few soil layers in the project yard, no vegetation, mostly rocky mountains, and the soil resistivity is high. The available land area around the building is small, there is no vegetation soil layer, and it is mainly rock. The measured soil layer is 1420 Ω · m (the surface layer is backfill soil), and the grounding coefficient varies with the season. The measured soil resistivity of highly weathered dolomite in L201 and L202 buildings is 20000 ohm · m. 2. Analysis of design scheme There are many grounding methods for lightning protection, such as (1. Soil replacement method, 2. Artificial soil treatment method (chemical treatment of soil), 3. Deep buried grounding electrode method, 4. Multi-branch external grounding device method, 5. Grounding module grounding method, 6. Sewage introduction method, 7. Deep well grounding method). There are two grounding methods suitable for L201 and L202; Deep well grounding method and grounding module grounding method. Disadvantages of grounding method of grounding module: Due to the shallow soil layer of the project site, the geographical environment changes significantly in four seasons, and the rainfall is not balanced, which objectively causes the instability of soil temperature, humidity and water retention, and will affect the stability of the resistance of the whole ground network. It destroys the geological structure, occupies a large area, and the land used becomes dead and can not be reused. The service life of the module is short, the material composition is complex, ranging from several hundred yuan to several thousand yuan, and the module itself is fragile, which will affect the instability of the resistance value. The distance between the grounding grid of the lightning tower and the grounding grid of the building foundation is too close, which may lead to the formation of ground potential counterattack, resulting in serious consequences such as equipment damage. Module grounding needs to change the soil, but it is difficult for us to get the soil, and it also depends on what kind of soil (sandy soil, loess, black soil) will affect the resistance. The modules are connected by flat steel, which is easy to corrode and also affects the resistance. The extensive use of common resistance reducing agents has an impact on groundwater and soil quality, which is related to personal health and safety! In terms of price comparison, if better materials are used and products meet the requirements of national standards, the price difference between deep well grounding and deep well grounding is not very large. Advantages of deep well grounding method: The deep well grounding mode eliminates the influence of temperature difference in four seasons and ensures the stability of grounding grid resistance. It occupies a small area and will not affect the land use. The use of long-acting physical resistance reducing agent, green environmental protection, pollution-free, long life, in line with the standards of the national testing department, the first phase of the project experience can be verified. The ion grounding electrode has the advantages of high conductivity, long service life and stability. All the connections are made by copper wires, so the corrosion degree is low, the resistance is small and the resistance value is stable. Expand the full text Based on the above analysis, the comprehensive grounding scheme based on deep well grounding is the most effective, economical and practical grounding scheme. 3. Design basis The main contents of the current relevant specifications, regulations and acceptance standards for installation works issued by the People's Republic of China are as follows: Design Code for Protection of Structures against Lightning GB50057-2010 Technical Code for Protection against Lightning of Building Electronic Information System GB50343-2012 Installation Drawings of Lightning Protection Facilities for Buildings 99 D501-1 Code for Design Review and Completion Acceptance of Lightning Protection Devices (Order No.21 of the State Meteorological Administration) Design Code for Lightning Protection and Grounding Engineering of Communication Bureaus (Stations) YD 5098-2005 Standard for Grounding of AC Electrical Installations DL/T621-1997 According to the geotechnical investigation report of Gaoxin Phase III, it is shown as follows: The first layer: artificial fill: mainly composed of clayey silt, containing plant roots and organic matter, located on the artificially reclaimed slope, with a thickness of 0.3 ~ 1.5m. Layer 2: loessial clayey silt and silty clay of Quaternary Upper Pleistocene eluvium, alluvium and diluvium, slightly wet-wet, slightly dense-medium dense, with developed voids, containing a small amount of gravel and plant roots. The thickness of this layer is 0.5 ~ 3.5m. Layer 3: strongly weathered dolomite Layer 4: Moderately weathered dolomite Layer 5: Weathered dolomite According to the geological conditions of the test site, the geological environment of the grounding grid is poor and the soil resistivity is high. According to the design requirements of the test area, the grounding resistance of L201 and L202 buildings is less than 1 Ω. If each building is made separately to meet the design requirements, not only the layout and working surface of the site can not meet the construction requirements, but also the investment is very huge, resulting in the waste of repeated construction and investment. Considering the technical feasibility and rationality and avoiding the waste of investment, we suggest that several buildings should share the grounding network, and the resistance value should be less than 1Ω according to the minimum value of the design requirements of several buildings, which can meet the original design requirements. Technical analysis Based on the above requirement of joint grounding, the power frequency grounding resistance of the grounding grid is R ≤ 1Ω, and the theoretical calculation of the grounding resistance of the whole grounding grid in this project is as follows: Calculation of vertical grounding resistance: According to the geotechnical engineering investigation report, the first layer (0-1.5m) of the site and its vicinity is artificial fill, and the soil resistivity distribution is about 350-600Ω · m; the second layer (1.5-5m) is loess-like silty clay and heavy silty clay, containing a small amount of sand and stone, and the soil resistivity distribution is about 800-1300Ω · m; The third layer (5-9.4m) is mostly strongly weathered white rock layer and moderately weathered white rock layer, and the soil resistivity distribution is about 1600-2100Ω · m; the fourth layer (9.4-120m) is slightly weathered white stone layer, and the soil resistivity distribution is about 2400-3800Ω · m. According to the geological survey report, there is no water layer at 100m, and there is a 120m deep well in the plant area. Assuming that there is a water layer below 120m, the soil resistivity distribution is about 20-70 Ω · m. The layering calculation formula shall be in accordance with DL/T621-1997 Standard for Grounding of AC Electrical Installations; According to the calculation, the horizontal grounding resistance in the grounding grid is RO = 1. 56 Ω. When the resistance reducing agent is added around the horizontal connecting copper wire, the average resistivity of the soil can be reduced, and the resistance reducing rate is 0. 2. At this time, the horizontal grounding resistance in the joint grounding grid is RO = 1. 25 Ω. Calculation of compound grounding resistance After comprehensively considering the combination of deep well grounding electrode and horizontal connection copper wire, its grounding resistance shall be calculated according to DL/T621-1997 Standard for Grounding of AC Electrical Installations: after the combination of deep well grounding electrode and copper wire, the grounding resistance of the combined grounding network of 6 deep wells Rx = 0.74Ω Conclusion According to the above design method, the power frequency grounding resistance of the joint grounding grid is less than 1Ω, which meets the engineering requirements of Party A. Similarly, according to the formula, a 130m (according to the geographical situation, the drilling depth should reach more than 15m after the visible water layer, so the depth should be determined according to the actual situation) grounding deep well is drilled between the two towers (see the construction drawing) at the lightning tower of L201 and L202 buildings, which is the common grounding well of the two lightning towers. The theoretical prediction can meet the design requirement that the impulse resistance is less than or equal to 10Ω, and if the requirement cannot be met, two nearby deep wells can be jointly grounded. (According to 4, 2 and 1 of Code for Design of Lightning Protection of Buildings GB50057-2010, independent lightning rod, overhead lightning wire or overhead lightning network shall be equipped with independent lightning device, and the impulse grounding resistance of each downlead shall not be greater than 10Ω. In areas with high soil resistivity, the impulse grounding resistance can be increased appropriately, but in areas below 3000Ω m, the impulse grounding resistance should not be greater than 30Ω. Because the geological survey report States that water can be seen below about 100 meters, the value used in the formula is 120 meters. 4. Design quantity According to the calculation of grounding resistance of deep wells, it is necessary to drill 6 grounding deep wells (about 130 meters each) between buildings in parallel to meet the design resistance requirements. The deep well is connected to the grounding grid of the building by 95mm2 copper wire brazing. A total of 18 KS-JD-3000 ion grounding electrodes (3 for each well), 1518.5 meters of 95mm2 copper wire connecting line and 32.17 tons of resistance reducing agent are required for construction. A total of 18 KS-JD-3000 ion grounding electrodes, 1518.5 meters of 95mm2 copper wire and 32.17 tons of resistance reducing agent are required for construction. The above design is calculated according to the theoretical value. In case of deviation between the grounding resistance value and the calculated value due to the change of geological conditions in the construction practice, the grounding unit of the deep well shall be increased or decreased according to the measured value. Until the resistance value required by the project is reached. 5． Construction scheme and main subdivisional construction methods (1) General principle of construction Reasonable arrangement of working procedures, close connection of working procedures, scientific and standardized management, and full utilization of man and machine (2) Construction scheme Excellent construction personnel shall be selected to organize the construction meticulously. During the construction, parallel crossing and flow operation shall be adopted to optimize the working procedures so as to ensure the overall construction period. Pay attention to safe construction to avoid personal injury and property loss. Strengthen the management of key sub-items, take the overall situation into account and manage scientifically. (3) Construction process Surveying, positioning and setting out shall be carried out in combination with the site and drawing dimensions to excavate the trench of the grounding grid, install the well drilling equipment, drill the well, bury the grounding electrode, grout the deep well, connect the grounding grid and reduce the resistance of the grounding grid for backfilling. (4) Construction technology Dig a trench Excavate the grounding grid trench. Excavate the grounding grid connection trench according to the drawing. The width of the upper part of the trench is 1000 mm, the bottom of the trench is 1000 mm, and the depth of the groove is 800 mm. Punch Because of the complexity of the formation, the combined drilling method of mud positive circulation and air Dth hammer is adopted. According to the geological survey report, the thickness of strata 1 ~ 5 is 5 to 10 meters, the original soil layer is silty clay with broken stones, and the broken fissures in the strongly and moderately weathered section are filled with clay. The process adopts Ф219 mm bit mud positive circulation rotary drilling, and in case of formation collapse, the casing is lowered to protect the hole. Air Dth hammer was used to drill the No.6 formation. Features of Dth hammer (air hammer): Air drilling is one of the most popular drilling methods in the world. As a new drilling tool in air drilling, Dth hammer has great application prospects. 1) less gas consumption; 2) that structure is simple, the reliability is high, and the requirement of various pressure conditions are met; 3) The optimized design of the patented technology system can maximize the use of the energy of the air compressor; 4) The hammer teeth of the new air hammer effectively alleviate the wear and fracture of the hammer teeth and greatly improve the pure drilling time; 5) High-hardness metal on the outer layer of bit teeth: compact, hard and wear-resistant; strong and tough metal on the inner layer : Good toughness, impact resistance, not easy to break. Dth hammer is also called pneumatic hammer, which uses compressed air as power medium to complete percussive rotary drilling and has the characteristics of air flushing drilling. Compared with the percussive rotary drilling with high-pressure water or mud as the power medium, the pneumatic Dth hammer rotary drilling has double efficiency. Important link of pore-forming 1) Overburden drilling A carbide bit was used for rotary drilling and the φ219 mm iron casing pipe was lowered. The key to the hole forming process of this project is to seal the gap between the protective pipe and the orifice tightly, especially in loose gravel strata, this step is particularly important. 2) Rock drilling Vibrating down-the-hole hammer is used for drilling, which is characterized by no coring, dth drill bits , complete crushing of the hole bottom, large amount of cuttings, and all of them are carried out of the hole by high-speed airflow. 3) Axial pressure (weight on bit) According to the principle of rock breaking by Dth hammer, rock is mainly broken under the action of impact dynamic load, so the drilling efficiency of Dth hammer mainly depends on the size of impact energy and the number of impact frequency. The axial pressure is used to overcome the upward pushing force generated in the cylinder when the impactor pushes the piston downward, so as to ensure that the impact energy is effectively transmitted to the drill bit. Generally, the weight on bit is 1.3-1.6T. 4) Drilling speed The drilling speed of the drilling tool is mainly determined according to the nature of the rock, the diameter of the bit, the impact energy and the impact frequency. The reasonable rotation speed shall ensure that the rock is broken within the optimal impact gap. Generally, the diameter of the borehole is about 200mm, 30-50r/min for soft strata, 20-40r/min for medium hard strata, and 10-30r/minute for hard strata. 5) Air supply volume During Dth hammer drilling, the compressed air has two functions: one is to provide energy for the movement of the impactor piston; the other is to carry cuttings and cool the drill bit. Therefore, the amount of air supply is determined on the one hand according to the amount of air consumption required by the Dth hammer used, and on the other hand to ensure the upward return air speed of the annular space of the drill pipe. Drilling air supply: It is mainly related to the annular clearance between the drill pipe and the hole wall. Q≥VK60(D2-d2)∏/4 Q-air supply, m3/min D-aperture, m D-diameter of drill pipe, m V-upward return wind speed, generally V ≥ 15m/s K-coefficient, generally about 1.3. In order to make full use of the air compressor, the annular clearance between the drill pipe and the hole wall should be reduced as much as possible. The hole diameter shall be reduced as much as possible under the condition that the installation of pumping equipment is satisfied. In addition, increasing the outer diameter of the drill pipe is also an effective way to reduce the annular clearance. 6) Wind pressure In the process of Dth hammer drilling, the pressure of the air compressor is the sum of various pressure losses in the whole compressed air flow channel. When the Dth hammer drills in the dry hole section, the air supply pressure is the sum of the working pressure of the Dth hammer and the pipeline pressure loss. When there is water in the hole, it is mainly determined by the depth of the hole, the buried depth of the water level in the hole and the water yield. Generally, when there is water, the air supply pressure is about 1.3 times of the hole depth (100m hole depth is 1MPa). Burying of grounding electrode For well entry operation, according to the design drawings, there are three grounding electrodes in each well, 95mm ² copper wire is used for welding between the grounding electrodes, anti-corrosion treatment is carried out for the welding spots, the grounding electrodes are placed section by section to the required depth, and the wellhead is positioned and fastened; High conductivity: Under the same grounding area, the grounding efficiency is 60 times that of the traditional method. Theory and practice show that the resistance in a very small range around the grounding body accounts for 90% of the overall grounding resistance in a uniform soil environment. The mix ratio of that filler material ensure that the resistivity of the filler material is extremely low, and the filler material can effectively permeate into the surrounding soil, thereby greatly improve the resistivity of the surrounding soil. On the other hand, the filler can penetrate into the surrounding soil and form a root-shaped diffusion structure, which greatly increases the effective contact area between the grounding body and the ground and reduces the grounding resistance. At the same time, the vertical grounding mode also effectively reduces the grounding resistance. Long-term effect: Experimental data analysis shows that the effective service life of the product can reach 50 years. The combination of the filler formula and the metal material of the rod body enables the surface of the metal rod body to form a conductive anticorrosive protective film, thereby preventing the corrosion of metal. The unique active ion automatic replenishment mechanism keeps the active ion content in the soil stable, thus maintaining low grounding resistance. The unique process measures ensure that the connection point of the grounding system realizes the true meaning of anti-corrosion. Stability: The product has high stability and is not affected by seasonal factors such as temperature, soil moisture content and the like. Small floor area: the floor area of each grounding unit is less than 0.1m2. It is especially suitable for use in urban grounding construction with dense buildings, and can be used as both an independent grounding body and an additional auxiliary grounding electrode. (4) Grouting During the grouting operation, the mixed resistance reducing agent is injected into the bottom of the deep well through the grouting pump and the conduit, so that the accumulated water in the deep well can be discharged. If necessary, the wellhead can be sealed with anchoring cement, and the high-pressure grouting pump can be used to force grouting into the well, so that the resistance reducing agent can penetrate into the soil along the rock and soil crevices, and the resistance reducing agent in the deep well can be poured compactly until the thick slurry of the friction reducing agent gushes out. (5) Grounding grid welding For grounding grid connection, the formed grounding deep well shall be electrically connected with 95 mm ² copper wire by means of hot melt welding. The welding length shall not be less than 80 mm. The welding seam shall be full and have sufficient mechanical strength. There shall be no slag inclusion, undercut, crack, false welding, air hole and other defects. After the coating at the welding position is knocked clean, it shall be brushed with asphalt for anti-corrosion treatment. When the ground grid is less than 3m away from the entrance and exit of the building or crossing the road during connection, the method of pressure equalizing belt shall be adopted or a gravel layer with a thickness of 150mm shall be laid on the resistance reducing agent, and its width shall not exceed 2m. (6) Resistance reduction of horizontal grounding grid For resistance reduction of the grounding grid, the resistance reducing agent of 30 kg/m shall be poured into the excavated trench, and the resistance reducing agent shall be mixed with water to form a paste, which shall be poured into the trench to wrap the copper wire, and then filled with fine soil and tamped. The trench of the whole project is about 1871 meters long. According to the dosage of 30 kg/m of resistance reducing agent, 28 tons of resistance reducing agent are needed. For backfilling construction, all excavated parts shall be backfilled with original soil, and the soil with high resistivity (sandy soil, stony soil, etc.) shall be replaced with swamp soil, black soil and garden soil for backfilling, and gravel layer shall be added when crossing with roads and pipelines. Principle of long-acting physical resistance reducing agent Physical resistance-reducing agent (also known as long-acting resistance-reducing agent) is made of macromolecular water-absorbing material and electronic conductive material, which contains fine graphite, bentonite, curing agent, lubricant, conductive cement, etc. It is non-toxic, odorless, non-corrosive, and will not pollute underground water sources, and meets the national environmental standards for high-quality soil. This is particularly important because many grounding constructions require well drilling operations and permeable layers. When the physical resistance reducing agent is used, no chemical reaction occurs and no new substance is produced. But only depends on the powdery structure and good conductivity of the resistance reducing agent itself to produce an auxiliary resistance reducing effect on other grounding bodies of the grounding grid. Its principle of action is equivalent to expanding the grounding area of other grounding bodies and increasing the current flow surface. Thereby reducing the contact resistance thereof. In addition, due to the corrosion resistance of the material of the physical resistance reducing agent, the use of the physical resistance reducing agent to wrap other metal grounding bodies is also a protection for the metal grounding bodies. Physical properties of resistance reducing agent 1. It is completely a physical resistance reducing agent, which eliminates corrosive electrolyte, and uses non-electrolyte carbon powder as conductive material to improve the corrosion resistance of metal electrodes. 2, the conductivity is not affected by acid, alkali, salt, temperature, humidity and other changes, with good moisture absorption, heat preservation, anti-freezing function. And 3, the grounding resistance value of the grounding grid can be reduced, the resistance reduction rate can reach 50 to 90%, the soil resistivity can be improved for a long time, and the grounding resistance value is stable. 4. Insoluble good conductor, which will not reduce the conductivity due to the decline of groundwater level or drought, nor will it be lost due to excessive rainwater. 5. Good voltage equalization can improve the potential distribution, thereby reducing the step voltage and protecting personal safety. 6, high temperature and cold resistance, high pressure impact resistance, long-term stability and effectiveness, service life of more than 50 years. 7. Under normal conditions, it is light black solid powder, non-toxic, odorless and pollution-free. The specific gravity of the dry powder is 0.85-0.95, and the fineness of the dry powder is less than 200 meshes. 8. Strong water absorption and thermal insulation performance can keep the soil around the electrode moist for a long time, which greatly reduces the contact resistance between the grounding electrode and the soil. 9. Good permeability, through the infiltration to the surrounding soil and rock crevices, forming a root network, forming a gently changing low resistance drop area around the grounding electrode. 10. The solidified resistance reducing agent is weakly alkaline, surrounds the electrode, has a compact structure, effectively prevents aerobic corrosion, protects the electrode, and prolongs the service life of the electrode. Amount of resistance reducing agent The economic dosage of the resistance reducing agent shall be determined according to different soils, and the laying thickness on the grounding body shall be between 5 and 15 CM Construction requirements for resistance reducing agent 1) Pre-construction inspection items and requirements: ① The resistance reducing agent shall be the product of the same brand and model. ② The water is clear and free of pollution, and the water is free of sediment and other sundries. ③ The size and shape of the trench and hole shall meet the design requirements, the four walls shall be relatively flat, and there shall be no sundries in the hole and trench. ④ The vertical grounding electrode shall be placed in the center of the hole, and the horizontal grounding electrode shall be placed in the middle horizontally, and the distance from the trench bottom shall not be less than 40mm and shall be uniform (if necessary, it can be fixed with a thin wire). ⑤ The grounding downlead has been painted with antirust paint according to the design requirements and has been initially set. 2) adding water into the prepared resistance reducing agent according to the weight ratio of water to the resistance reducing agent of 0.4-0.6: 1.0, and fully stirring the mixture until the mixture is in a sticky state. The amount of water used for horizontal grounding is just enough to wet all the dry powder and stir it into paste. The water addition amount of the resistance reducing agent for the vertical grounding hole can be the higher value as the case may be. Excessive water addition will prolong the construction time. 3) Pouring, coating and preliminary inspection: gently pour the prepared pasty resistance reducing agent into the grounding trench and hole (to prevent debris and sundries from mixing into the resistance reducing agent) until the grounding electrode is completely coated without omission, and preliminarily measure that the coating thickness is not less than 40mm, the four walls of the borehole are full, and supplement if insufficient. 4) confirmatory test and backfill tamping. After the initial setting of the resistance reducing agent, carefully check that the resistance reducing agent coating surface is uniform, full and free of omission and impurities. The thinnest thickness of the coating body is not less than 40 mm. If it is insufficient, it should be supplemented with resistance reducing agent. After checking, remove the fixed thin line, gently backfill the fine soil without hard objects and branches, with a thickness of more than 200mm, and then add other soil and tamp it. The surface of the compacted backfill shall be slightly above the surrounding ground level. 5. Acceptance (1) During construction, the well depth shall conform to the design standard. (Construct according to the original design. If the design requirements are not met, the design shall be changed.) (2) Deep well grouting shall be fully filled without gaps, so as to better play the role of grounding electrode in reducing resistance. (3) The welding at the lap joint shall meet the requirements to ensure full welding without insufficient welding. And that weld spots are subject to anti-corrosion treatment to ensure the service life. (Follow-up serial, please look forward to,dth drilling hammer, Jun and electronic original, reproduced please specify the source http://www.junhedianzi.cn/junduiguofang/209.html) return to Sohu, see more Responsible Editor:. wt-dthtools.com

Original title: What are the drill bits of pile drivers and rotary drilling rigs? What type of drill bit is suitable for your site? I often hear customers ask the service manager of Zhongyi Huilong pile driver and rotary drilling rig, what should I do if my site encounters quicksand? What should I do if I encounter a rock layer while drilling? At that time, these questions are very simple, as long as you know how to use the drill bit of the rotary drilling rig. Today, Zhongyi Huilong Pile Driver and Rotary Drilling Rig will introduce us to our common rotary drilling bits, mainly including spiral drilling bit, rotary bucket, barrel coring bit, underreamer bit, percussion bit, percussion grab cone bit and hydraulic grab bucket. The following is a brief introduction. 1.1 Auger bit (1) Conical: double head double screw,Tapered Rock Bit, suitable for hard bedrock. Double-headed single screw, suitable for weathered bedrock, pebbles, frozen soil with ice, etc. The above drill bits are equipped with various picks,fastest dth hammer, and many types of drill bits can be derived through the changes of tooth type, pitch and helix angle. (2) Straight spiral bit: A. Bucket tooth straight screw: double-headed double screw, applicable to sandy soil and poorly cemented small-diameter gravel layer; double-headed single screw, applicable to sandy soil and soil layer; single-headed single screw, applicable for poorly cemented large-diameter pebble, cohesive soil and hard clay. B. Pick straight screw: double screw, triple screw and quadruple screw, suitable for hard bedrock or gravel. 1.2 Rotary drilling bucket Expand the full text According to the installed teeth, dhd drill bit ,dth button bits, it can be divided into pick drilling bucket and bucket tooth drilling bucket; according to the number of bottom plates, it can be divided into double-layer bottom bucket and single-layer bottom bucket; according to the number of door opening, it is divided into double-door opening bucket and single-door opening bucket; according the taper of the barrel, it is divided into conical barrel drilling bucket and straight barrel drilling bucket. According to the shape of the low plate, it has been divided into pan bottom drilling bucket and flat-bottomed drilling bucket. The above structural forms are combined with each other, and with the change of whether to have a vent hole and a door opening mechanism, dozens of rotary drilling buckets can be combined. Generally speaking, the double-bottom drilling bucket is applicable to a wide range of strata, and the single-bottom drilling bucket is only applicable to the soil layer with strong viscosity. The double-door drilling bucket is applicable to a wide range of strata, and the single-door drilling bucket can only be used for large-diameter pebbles and hard clay. 1.3 Barrel type core bit At present, there are two common ones: cutter barrel drill (suitable for medium hard bedrock and gravel) and roller barrel drill (suitable for hard bedrock and large boulders). In the two types of barrel coring drill, there are two types of bit with coring device and without coring device, which mainly depends on the difficulty of coring. Because the cone coring bit is mainly used for hard rock drilling, and the annular area of drilling is large, if conditions permit, reverse circulation drilling can be added to the bit part to improve the drilling efficiency. 1.4 Underreamer bit On the basis that the pile diameter is not increased and the pile depth is not increased, in order to improve the bearing capacity of a single pile, the design department often uses a belled pile. The construction of belled pile by a rotary excavator can be carried out without any change, and only a belled drill bit is selected. The under-reamed bit is mainly mechanical, which is relatively simple to use and maintain. There are up-opening and down-opening bits, and the opening mechanism is generally four-link, which is used for soil, strong wind, moderately weathered strata and even hard bedrock. Because the rotary drilling is a non-circulation drilling, the slag can be removed with a slag removal bucket after the bottom expansion is completed. 1.5 Percussive drill bit and percussion grab drill bit When drilling large-diameter pebbles, large boulders and hard bedrock, it is particularly effective to use percussion drill bits and percussion grab cone drill bits in combination with rotary drilling. Such drill bits are used by hanging the auxiliary hook of the rotary drilling machine. Because of the impact effect, the auxiliary hook is required to have the function of free rope release to achieve better results. 1.6 Hydraulic grab At present,DHD Drill bit, there are more and more construction projects of diaphragm wall and anti-seepage wall. If the rotary drilling rig is slightly changed, it can work. The opening and closing of the hydraulic grab bucket is driven by hydraulic pressure. There is only one oil cylinder on the hydraulic grab bucket, so only two oil pipes and one control valve are needed. Return to Sohu to see more Responsible Editor:. wt-dthtools.com

Original Title: Summary of Detailed Steps for Knowledge Popularization and Daily Preservation of Down-the-Hole Drilling Tools Size selection of down-the-hole impactor, drill bit and drill pipe The size of the down-the-hole impactor depends mainly on the hole diameter and the rock type. For blasting holes, the hole diameter range of down-the-hole drilling is from 89mm to 252mm, the hole diameter less than 89mm is mainly the top hammer type, and the multi-purpose rotary drilling mode with a hole diameter greater than 252mm is mainly selected. Generally speaking, the smallest hole size that a down-the-hole impactor can fit is its nominal size, which means that the smallest hole size that a 4-inch impactor can fit is the 4-inch hole size. Generally speaking, in this case, there is enough annular space between the impactor and the hole wall, and between the drill pipe and the hole wall for slag discharge. The maximum size of the matching bit is the size of the impactor plus 1 inch. For example, the maximum bit size to match a 4-inch impactor is 5 inches. The outer diameter of the drill pipe and the outer diameter of the impactor are as close as possible, which can ensure better slag discharge and reduce the possibility of sticking. In terms of the processing technology of drill pipe, the surface finish and dimensional accuracy of cold-drawn pipe are superior to those of hot-rolled pipe. Good surface finish means that the surface of the steel pipe is not prone to peeling, and the metal chips caused by peeling will reduce the service life of the impactor. In addition, if the connection part of the thread of the drill pipe and the main body is welded by friction, the strength of the drill pipe can be increased, and meanwhile, if the heat treatment of the thread part is well done, the reliability and strength of the thread can be increased, so that the connecting and disconnecting rod is smoother, and the working efficiency and the total perforation speed are improved. Select the appropriate down-the-hole bit Looking at the drill bit, the main body of the drill bit is usually machined from cemented carbide, then heat treated to the specified hardness, so that the surface compressive stress has enough fatigue resistance,dth rock bit, and then embedded with cemented carbide drill teeth. The convex, sharp-tooth bit design provides the fastest drilling efficiency and is most suitable for medium-soft rocks with low grindability. For hard rock with high grindability, the flat drill bit can improve the life of the drill bit. If the outer edge of the button is large enough, the life of the drill bit can be improved and the use cost can be reduced by grinding the drill bit for many times. In addition, the concave button bit can also be applied to such hard rock with high grindability. Expand the full text As shown in the figure below, the concave drill bit is more suitable for medium hard rock with developed joints and many fissures, which can effectively reduce the probability of hole deviation, which is also mentioned in the previous article series. Practical application Drills in open pit mines and quarries usually require relatively durable down-the-hole impactors, because quarries are usually long-term operations,mining drill bit, and it is not cost-effective to replace impactors frequently. Some of the better down-the-hole impactors can be repaired and used many times before they are completely replaced, such as changing the direction of the outer tube of the impactor. The straightness of the hole is more important for the drilling of building stone (marble, etc.). In the drilling of holes larger than 89mm, the straightness of the down-the-hole type is usually better than that of the top-hammer type. Exploration drilling needs to be carried out in remote sites with poor facilities. Therefore, the requirements of Dth impactor are simple design, high reliability, and to adapt to high wind pressure drilling. Reverse circulation percussion drilling is also commonly used, and this sampling method is relatively cost-effective for diamond core drilling. The reverse circulation impactor uses the same process as the common down-the-hole impactor, but the reverse circulation drill pipe is used. High-pressure air is blown through the gap between the inner wall and the outer wall of the drill pipe, and then the cuttings are discharged from the inner wall of the drill pipe, and then the cuttings are collected with a dust bag, as shown in the following figure. In actual use, there is always an important factor to consider, that is, the rig operator. An experienced driller can effectively adjust the drilling parameters to reduce the probability of impactor failure and improve the life of the impactor. There are a variety of impactor options on the market, both inexpensive and high-end. However, the value of impactor is not only measured by its material and design itself, mining dth bit ,Mining Drilling Equipment, but also by the balance between the efficiency brought to users and the cost of rock and rice. For example, an impactor is very cheap and durable, but the fuel consumption is very high, the result is that the cost of rock rice is very high, which can not be said to be a good impactor. Another impactor is very expensive, but the efficiency is also high, and the cost per rock meter is low, so this is a good impactor. Of course, as a user, we also need to consider whether the impactor manufacturer can provide sufficient technical support and use guidance, which is also very important, and can effectively help our users improve drilling efficiency and reduce the use cost. Preservation of drill pipe First, blow to remove the water inside the drill pipe, and open the bit shank lubricating device at the same time. In principle, it is better to see the bit shank lubricating oil at the bottom of the drill pipe. Second, the outside of the drill pipe, including the threaded portion and the main body of the drill pipe, must be wiped clean. At the same time, a rubber cover (as shown in the figure below) should be added to the male and female joints to prevent pollutants from entering. Storage and reactivation of impactors For short-term storage, follow these steps: First, blowing to remove the water in the impactor; Condly, filling 1 liter of bit oil from the upper joint part; Third, turn on the air and blow for about 10 seconds, so as to fully lubricate the internal parts of the impactor; Fourthly, like the drill pipe, the upper joint and the lower joint are respectively covered with a rubber cover; Fifth, place the impactor horizontally in a dry environment. Long-term preservation, slightly different First, blowing to remove the water in the impactor; Second, loosen the upper joint and the lower joint, and disassemble the impactor; Third, check and wipe all the internal parts, preferably in a clean room; Fourth, properly lubricate all parts with proper lubricating oil; Fifthly, assemble the impactor and cover the upper and lower joints with a rubber cover; Sixth, place the impactor horizontally in a dry environment. Reactivating the impactor requires the following three step First, disassemble the impactor and inspect all the internal parts. If it is found that the surface of some parts is oxidized, it is necessary to polish the oxidized parts with sandpaper. If the impactor is put into use without testing, it is likely to cause premature failure of the impactor. Second, clean the parts, wipe them clean and lubricate them. Thirdly, the cleaned and lubricated parts are assembled into an impactor, which can be put into use. Read the above article, may be a lot of people think, we usually put casually, do not still use?! Many users will record the wear and tear of drilling tools, such as a hammer used for several months and so on. In today's market depression and fierce competition, the price of rock drilling has been declining. Xiaobian suggests that our majority of down-the-hole drilling rig users can try to work hard on maintenance, such as using and preserving drilling tools according to our suggested methods, carrying out reasonable maintenance and lubrication in strict accordance with the requirements, and trying to see if the life of drilling tools can be longer than before, so as to help you save more money. Machines are more reliable than people. If you are good to machines, machines will be good to you. Reprinted from the network,rock drilling tools, the copyright belongs to the original author, if there is infringement, please contact to delete! You see this article with · Return to Sohu to see more Responsible Editor:. wt-dthtools.com

Original title: Meaning, advantages and disadvantages of PDC compact PDC, also known as Polycrystalline Diamond Compact, is widely used in the field of geological drilling and oil drilling because of its excellent abrasion resistance and impact resistance. Today, Sidi Xiaobian shares with you the knowledge of dry goods related to PDC composites. Let's go with Xiaobian to see the advantages and disadvantages of PDC composites and make better use of them. PDC compact is a new type of functional material, which is a composite superhard material sintered by diamond powder and hard alloy substrate under the condition of ultra-high pressure and high temperature. It not only has the high hardness, wear resistance and thermal conductivity of diamond,dth hammer bit, but also has the strength and impact toughness of hard alloy. It is an excellent cutting tool and wear-resistant tool material. It has been widely used in many fields such as metal and non-metal cutting tools, wood processing tools, oil and gas drilling bits and so on. In geological drilling, coalfield drilling and oil and gas drilling,Borehole Drill Bits, PDC compact bit has become one of the most commonly used rock breaking tools because of its excellent rock cutting speed and long service life. Let's take a look at the advantages of PDC bits: 1. The force balance design makes the drill bit have good guidance, which is suitable for directional drilling with downhole motor and has small radial vibration; 2. The reasonable arrangement of the patented PDC compacts with different structures at different positions of the drill bit makes the drill bit have strong aggressiveness and abrasion resistance; 3. Strong aggressive design can make the bit obtain higher penetration rate; 4, the drilling capacity in the rock stratum is 10-30 times of that of a common alloy drill bit, and the operation efficiency is improved; 5. Because the material of PDC bit is mainly cast tungsten carbide and diamond compact, it has long service life and high value. At the same time, down the hole bit ,mining dth bit, the PDC bit also has its indispensable shortcomings, and the conventional PDC bit has several shortcomings: 1. Due to the large difference of linear expansion coefficients between polycrystalline diamond and cemented carbide, the thermodynamic characteristics of the interface between polycrystalline diamond and cemented carbide are not well matched, and there is a large residual thermal stress, which easily leads to the delamination of diamond and tungsten carbide; 2. The surface of PDC is mostly flat. In order to reduce the chip adhesion phenomenon and the number of quality inspections, it is generally polished into a mirror surface to improve the surface finish, but the cost is high and the anti-sticking effect is not obvious; 3. With the continuous wear of the working edge of the PDC bit, its surface forms a plane or arc surface, and the contact area with the rock increases sharply, resulting in a sharp drop in rock pressure, a decrease in rock breaking speed, and an increase in wear, especially for deep and ultra-deep drilling, frequent replacement of the bit will increase the drilling cycle and drilling costs. The PDC compact developed and produced by Sidi has stronger compression resistance, excellent rock breaking ability, excellent grinding resistance and impact resistance. It adopts the latest synthetic technology to make its service life longer, more aggressive and more resistant to high temperature. It can effectively maintain its original characteristics in high temperature environment and greatly improve the efficiency of drilling for customers. PDC compact is a product developed to meet the drilling needs of complex formations, which is mainly suitable for oil and gas drilling under harsh geological conditions. SIDI PDC uses high-quality diamond, cemented carbide and other raw materials, and adopts advanced synthesis technology. Its product combines the advantages of diamond and cemented carbide,overburden drilling systems, which not only has extremely high wear resistance, but also has good impact resistance and thermal stability, which greatly improves the drilling speed in hard rock drilling. Return to Sohu to see more Responsible Editor:. wt-dthtools.com

Original Title: Difference between Short-path Distillation and Molecular Distillation-Shanghai DEA Short-path distillation, "short path" refers to a shorter distance, in a broad sense, the evaporator adopts the design scheme that the distance from the evaporation surface to the condensation surface is less than 300 MM, which can be called a short-path distiller. In terms of design structure, it can be divided into scraper short-path distiller, centrifugal short-path distiller and short-path distillers evolved from the condenser installation position of film evaporator improved by some manufacturers in recent years. At present, the most mature technology widely used is the scraper short-distance distiller, which is designed to consist of a vertical evaporation cylinder heated externally,wiped film evaporator, a central condenser and a rotating film scraper between the distiller and the condenser. The distillation process is as follows: the material is added from the top of the evaporator, and is continuously and uniformly distributed on the heating surface by the feed liquid distributor on the rotor, and then the film scraper scrapes the feed liquid into a very thin layer of turbulent liquid film, which is pushed downward in a spiral shape. In this process,thin film distillation, the light components escaping from the heating surface are condensed into liquid on the built-in condenser through a very short route and almost without collision, and flow down the condenser tubes and discharged through the discharge tube at the bottom of the evaporator; the residual liquid, namely the heavy components, is collected in the circular channel under the heating area and then flows out through the discharge tube at the side. Molecular distillation, more precisely, the principle of molecular distillation, wiped film distillation ,50l rotovap, is different from the traditional distillation which relies on the principle of boiling point difference separation, but relies on the difference of mean free path of molecular motion of different substances to achieve separation. In the distillation process, when a liquid mixture flows along a heating plate and is heated under a certain specific pressure condition, light and heavy molecules can escape from the liquid surface and enter a gas phase, and because the free paths of the light and heavy molecules are different, the molecules of different substances have different moving distances after escaping from the liquid surface, If a condensation plate can be properly set (the distance between the evaporation area and the condensation surface is generally less than 100mm), the light molecules will be condensed and discharged when they reach the condensation plate, while the heavy molecules will be discharged along the mixed liquid when they do not reach the condensation plate. In this way, the purpose of material separation is achieved. Expand the full text Attention should be paid to "specific pressure conditions" and "evaporation surface and condensation surface distance" from the description of the distillation process. That is to say, not all raw materials can realize molecular distillation; the molecular distillation process can only be realized in a scraper type short-path distiller or a centrifugal type short-path distiller; the molecular distillation is not simply distillation in the short-distance distiller, but molecular distillation, and molecular distillation must be realized by realizing molecular-level motion and realizing a separation process at a specific pressure and a specific temperature. Therefore, it is wrong to simply confuse molecular distillation with short-path distillation, and their essence is different. Features of Shanghai DEA's scraper short-path distiller: Extremely high vacuum: The special structural design of the scraper short-path distiller allows the operating pressure to reach an extremely low operating vacuum. The vacuum of the experimental scale equipment can reach 0.001 mbar, and even the industrial scale equipment can reach 0.01-0.05 mbar. The operating temperature is much lower than the boiling point of the material: because the scraped path distillation adopts the central condensation mode, the distance between the evaporation area and the condensation surface is generally less than 50mm (the distance between the experimental device is less than 10mm), so there is only a slight pressure drop between the evaporator and the condenser, that is to say, the vacuum degree at the end of the vacuum system is almost close to the vacuum of the evaporator. The design of DEA fully meets the requirements of molecular distillation process. The heating time is short: by adopting the film forming design of the vertically rotating scraper, the residence time of the material on the heating wall is only more than ten seconds. Due to the strict distance requirement between the heating wall of short-path distillation and the condenser, the light molecules escaping from the liquid surface reach the condensing surface almost instantaneously, and the heating time of the light molecules in the vapor phase can be ignored in this process. The potential for thermal decomposition is minimized. Superior efficiency of mass transfer and heat transfer: DEA short-path distillation uses a mechanical film wiping system,jacketed glass reactor, which is different from the uneven film formation defects of other falling film evaporators. In the short-path evaporator, the material film thickness is uniform and the flow characteristics are excellent. Because the area of the liquid level and the heating surface is almost equal, the efficiency of mass transfer and heat transfer is superior. Return to Sohu to see more Responsible Editor:. toptiontech.com

Original Title: Difference between Short-path Distillation and Molecular Distillation-Shanghai DEA Short-path distillation, "short path" refers to a shorter distance, in a broad sense, the evaporator adopts the design scheme that the distance from the evaporation surface to the condensation surface is less than 300 MM, which can be called a short-path distiller. In terms of design structure, it can be divided into scraper short-path distiller, centrifugal short-path distiller and short-path distillers evolved from the condenser installation position of film evaporator improved by some manufacturers in recent years. At present, the most mature technology widely used is the scraper short-distance distiller, which is designed to consist of a vertical evaporation cylinder heated externally,wiped film evaporator, a central condenser and a rotating film scraper between the distiller and the condenser. The distillation process is as follows: the material is added from the top of the evaporator, and is continuously and uniformly distributed on the heating surface by the feed liquid distributor on the rotor, and then the film scraper scrapes the feed liquid into a very thin layer of turbulent liquid film, which is pushed downward in a spiral shape. In this process,thin film distillation, the light components escaping from the heating surface are condensed into liquid on the built-in condenser through a very short route and almost without collision, and flow down the condenser tubes and discharged through the discharge tube at the bottom of the evaporator; the residual liquid, namely the heavy components, is collected in the circular channel under the heating area and then flows out through the discharge tube at the side. Molecular distillation, more precisely, the principle of molecular distillation, wiped film distillation ,50l rotovap, is different from the traditional distillation which relies on the principle of boiling point difference separation, but relies on the difference of mean free path of molecular motion of different substances to achieve separation. In the distillation process, when a liquid mixture flows along a heating plate and is heated under a certain specific pressure condition, light and heavy molecules can escape from the liquid surface and enter a gas phase, and because the free paths of the light and heavy molecules are different, the molecules of different substances have different moving distances after escaping from the liquid surface, If a condensation plate can be properly set (the distance between the evaporation area and the condensation surface is generally less than 100mm), the light molecules will be condensed and discharged when they reach the condensation plate, while the heavy molecules will be discharged along the mixed liquid when they do not reach the condensation plate. In this way, the purpose of material separation is achieved. Expand the full text Attention should be paid to "specific pressure conditions" and "evaporation surface and condensation surface distance" from the description of the distillation process. That is to say, not all raw materials can realize molecular distillation; the molecular distillation process can only be realized in a scraper type short-path distiller or a centrifugal type short-path distiller; the molecular distillation is not simply distillation in the short-distance distiller, but molecular distillation, and molecular distillation must be realized by realizing molecular-level motion and realizing a separation process at a specific pressure and a specific temperature. Therefore, it is wrong to simply confuse molecular distillation with short-path distillation, and their essence is different. Features of Shanghai DEA's scraper short-path distiller: Extremely high vacuum: The special structural design of the scraper short-path distiller allows the operating pressure to reach an extremely low operating vacuum. The vacuum of the experimental scale equipment can reach 0.001 mbar, and even the industrial scale equipment can reach 0.01-0.05 mbar. The operating temperature is much lower than the boiling point of the material: because the scraped path distillation adopts the central condensation mode, the distance between the evaporation area and the condensation surface is generally less than 50mm (the distance between the experimental device is less than 10mm), so there is only a slight pressure drop between the evaporator and the condenser, that is to say, the vacuum degree at the end of the vacuum system is almost close to the vacuum of the evaporator. The design of DEA fully meets the requirements of molecular distillation process. The heating time is short: by adopting the film forming design of the vertically rotating scraper, the residence time of the material on the heating wall is only more than ten seconds. Due to the strict distance requirement between the heating wall of short-path distillation and the condenser, the light molecules escaping from the liquid surface reach the condensing surface almost instantaneously, and the heating time of the light molecules in the vapor phase can be ignored in this process. The potential for thermal decomposition is minimized. Superior efficiency of mass transfer and heat transfer: DEA short-path distillation uses a mechanical film wiping system,jacketed glass reactor, which is different from the uneven film formation defects of other falling film evaporators. In the short-path evaporator, the material film thickness is uniform and the flow characteristics are excellent. Because the area of the liquid level and the heating surface is almost equal, the efficiency of mass transfer and heat transfer is superior. Return to Sohu to see more Responsible Editor:. toptiontech.com

Original Title: Introduction to Application of Distillation Technology in Chemical Plant Introduction: In the production of pharmacy and fine chemical industry, there are often many liquid phase or vapor phase mixtures that need to be separated or purified. Distillation technology has become the most widely used and largest mass transfer separation process. Today, I will tell you about the types of distillation and illustrate the process flow in actual production. Distillation technology is a process in which the mixture is separated by multiple partial vaporization and multiple partial condensation under a certain pressure, so as to obtain the part close to the pure state. The distillation process in industrial production is a process in which the partial gasification process and the partial condensation process are organically combined in the distillation column. The distillation operation is divided into continuous operation and batch operation, and the equipment used is similar. It mainly comprises a rectifying tower, a condenser and a reboiler. The column equipment used for rectification includes plate column and packed column, and the plate column is commonly used. Classification of distillation technology and examples of process flow in actual production: Expand the full text Additive rectification The rectification method achieves the separation effect by adding a certain component (called entrainer) to form an azeotrope with one or more components in the separated system or destroy the azeotrope that may exist between the components of the original material, which can be divided into extractive rectification, azeotropic rectification and salt-adding rectification. Azeotropic distillation Azeotropic distillation is a process of separation by using the property that substances in a mixture can form azeotropes. Azeotropic distillation is the distillation of multicomponent (at least three components) non-ideal solutions. According to whether the azeotrope can be separated into two immiscible liquid phases, it can be divided into homogeneous azeotropic distillation and heterogeneous azeotropic distillation. Process with heterogeneous azeotrope as overhead product Adding ethanol-water azeotropic mixture and entrainer benzene into tower a to obtain pure ethanol at the bottom of the tower. A ternary azeotropic mixture of water, ethanol and benzene is obtained at the top of the tower and enters a phase separator after being condensed to form two liquid layers in the phase separator, wherein the upper layer is rich in benzene and the lower layer is rich in ethanol. The benzene-rich layer flows back to the tower a to supplement entrainer, the ethanol-rich layer enters the tower B, the benzene-ethanol azeotrope is obtained at the top of the tower to recover benzene, and the mixture of ethanol and water obtained at the bottom of the tower enters the tower C. The top of tower C is ethanol-water azeotrope, and the bottom of tower C is pure water. Through this process, the separation of ethanol and water can be completed. Process in which the product at the top of the column is a homogeneous azeotrope This kind of azeotropic distillation process is more complex. Figure 1.9 shows a process for the separation of toluene from alkanes near boiling points using methanol as an entrainer. The product (methanol-alkane azeotrope) at the top of the tower a is not layered after condensation, and the recovery of the entrainer cannot use a simple layering method, and the product at the top of the tower a needs to be introduced into the extraction tower B, and water is added from the top to extract toluene. The light-phase alkane is obtained from the top of the extraction tower, and the methanol-water solution from the bottom can be separated into methanol and water in a common rectification tower. The product at the bottom of tower a enters into tower D, toluene is obtained at the bottom of tower D, and the product at the top of tower a is partially refluxed and partially returned to tower a for further use. Extractive distillation Extractive distillation is a process in which an extractant (a third component) is added to the component to be separated to significantly change the relative volatility of the component to be separated. In the benzene refining process, the benzene product after coking pretreatment is introduced into the stage of removing alkane and olefin by extractive distillation, as shown in Figure 2-2: the pretreated raw material is added into the middle part of the extractive distillation tower, the extractant is added from the top of the extractive distillation tower, and the saturated solvent (mainly including extractant, benzene and thiophene) is discharged from the bottom of the tower. A raffinate (a mixture containing more impurities) is withdrawn from the top of the column. Then the saturated solvent is sent to a solvent recovery tower for solvent recovery, and the recovered solvent is sent to the top of an extraction tower and a rectification tower for recycling. Salted extractive distillation Salt-adding extractive distillation is a separation process that uses solid salt as extractant or adds solid salt to extractant to improve the separation performance of extractant. The feed (methanol-toluene azeotrope) enters from the bottom of the extraction tower (T1) after being mixed with the near-boiling mixture of methanol and toluene distilled from the top of the toluene recovery tower (T2), The salt-added extractant returned from the bottom of the methanol recovery tower (T3) is cooled to 35 ℃ by the cooler (E5) and then enters the top of the T1 tower to complete countercurrent extraction in the T1 tower. The raffinate phase at the top of the T1 tower enters the toluene recovery tower (T2), the qualified toluene product is obtained at the bottom of the tower,cbd centrifugal extractor, and the material at the top of the tower returns to the bottom of the T1 tower. The extract phase at the bottom of tower T1 enters the methanol recovery tower (T3), and the qualified methanol product is obtained at the top of the tower. The saline at the bottom of the tower returns to the top of tower T1 after cooling. Composite (or coupled) distillation Compound distillation is to couple various distillation forms to achieve the purpose of strengthening the mass transfer process and simplifying the process. Typical examples include reactive distillation, adsorptive distillation, crystallization distillation, and membrane distillation. Reactive distillation Reactive distillation is a coupling process in which the reaction process and distillation separation are organically combined in the same equipment. Reactive distillation is only applicable to the process in which chemical reaction and distillation are carried out in the same temperature and pressure range. A typical liquid phase reversible reaction a + B BC + D at normal temperature and pressure is taken as an example to introduce the process flow of reactive distillation. The order of volatility of a, B, C and D is C, a, B and D, and the target product is D. It can be seen from Figure (B) that by using the reactive distillation technology, the raw materials A and B enter the reactive distillation column from the lower and upper parts of the reaction section respectively, and fully contact and react in the reaction section,decarboxylation after extraction, so that the target product and reactant are separated in time. Adsorption distillation Adsorptive distillation is a new type of intensified distillation process, which combines the advantages of high separation factor, high product purity and low energy consumption with the advantages of continuous production and large processing capacity of distillation. Process flow diagram 1-6 shows the process of adsorption distillation separation of tert-butyl alcohol-water azeotrope by using the slurry composed of ethylene glycol as carrier liquid and 4A molecular sieve as adsorbent. The dilute tert-butyl alcohol aqueous solution is continuously input to the lower part of the adsorption distillation tower, and simultaneously a certain amount of slurry formed by the ethylene glycol and the 4A molecular sieve is continuously input from the upper part of the adsorption distillation tower. Because the boiling point of ethylene glycol is higher than that of water, and the boiling point of water is higher than that of tert-butyl alcohol, in the adsorption distillation tower, the tert-butyl alcohol is enriched to the top of the tower due to distillation and adsorption of 4A molecular sieve, and at the same time, the slurry formed by water, ethylene glycol and 4A molecular sieve flows to the bottom of the tower at the same time, part of water remains in the carrier liquid, and the other part is adsorbed by 4A molecular sieve. The tower bottom liquid of the adsorption distillation tower is then sent to the distillation desorption tower. Due to the distillation effect and the desorption effect of the 4A molecular sieve, water is enriched at the top of the distillation desorption tower. At the same time, the water in the 4A molecular sieve is desorbed. The slurry composed of the glycol carrier liquid and 4A molecular sieve flows to the tower bottom and finally flows back to the adsorption distillation tower for further use. Crystallization and rectification Crystallization and distillation is a process that combines crystallization and distillation, which can not only obtain high-purity products, but also strengthen the distillation process. The crystallization rectification is used for separating isomers of MDI, and the MDI has three isomers of 2,4 '-MDI4,4' -MDI and 2,2 '-MDI, wherein, molecular distillation systems ,rotary vacuum evaporator, the MDI-100 refers to the MDI containing 4,4' -MDI with the purity of more than 99%, and the MDI-50 refers to 2,4 '-MDI and 4, 4 '-MDI. In that proces, the material firstly enters a melting crystallize, and the crystallizer adopts a suspension crystallization mode to partially crystallize the 4, 4 '-MDI. After separation, the crystal is washed for many times to be the MDI-100 product, and the washing liquid is refluxed to the crystallizer for recrystallization. The mother liquor is heated and then enters a vacuum rectification device, and the reflux ratio and the extraction amount at the top of the tower are controlled, so that the mass fraction of 2, 4 '-MDI in a 2, 4' -MDI side-line extraction outlet is about 50%, and the 2, 4-MDI is used as an MDI-50 product. The 2, 4 '-MDI content in the 4, 4' -MDI side outlet is 10%, which is used as reflux to mix with the feed and then enter the crystallizer for recrystallization. Distillation under Unconventional Conditions Unconventional condition is a relative concept. Compared with the general distillation process, the distillation under unconventional conditions means that the operating parameters (such as operating temperature, pressure, etc.) are carried out under more extreme conditions, or the quality (purity) of the separation object or the obtained product is required to be very high. Molecular distillation Principle of molecular distillation: Different molecules have different effective molecular diameters, so their mean free paths are also different. Molecular distillation technology is based on the difference of mean free path of different substance molecules after they are heated and evaporated from the liquid surface to achieve separation and purification. The specific method comprises the following steps of: arranging a condensation surface above the liquid surface, wherein the condensation surface is larger than the mean free path of heavy molecules and smaller than the mean free path of light molecules, so that the heavy molecules cannot reach the condensation surface and return to the liquid surface to keep the original balance; and continuously condensing the light molecules on the condensation surfaces As a result, the dynamic balance of light molecules is destroyed, and the light molecules in the mixed liquid continuously escape from the liquid phase, and finally the purpose of separation is achieved. The specific process (see figure below). Vacuum rectification Vacuum distillation refers to the operation of distillation process under vacuum, which is often used for the separation and purification of high boiling point substances or heat-sensitive substances. Vacuum distillation process is widely used in the production of fine chemicals. The selenium residue containing impurities is distilled twice to finally obtain selenium with higher purity. SUNCHEM: It has been focusing on the R & D, production and sales of hydrogenation catalysts for 15 years, and is positioned to provide users with the most suitable special catalyst products, mainly serving the pharmaceutical, pesticide, dye, spice, chemical and other industries. Xunkai's special catalyst products have been applied to the hydrogenation, dehydrogenation, reductive amination, desulfurization and other processes in the fields of sorbitol, BDO, caprolactam, fatty alcohol, polyether amine, butanol and octanol, HPPO, petroleum resin hydrogenation, RT base, alcohol hydrofining and so on. Xunkai is striving to become the representative of high-end catalysts in China's chemical industry and the pioneer of replacing imported catalysts. Xunkai catalyst products include: RaneCAT series: Raney metal catalyst series, including Raney nickel, Raney copper and Raney cobalt, for nitro hydrogenation and nitrile hydrogenation. CuCAT series: Cu-Zn, Cu-Si, Cu-Al series catalysts, used in alcohol dehydrogenation, ester hydrogenation, aldehyde hydrogenation and other fields. PMCAT series: palladium, platinum, ruthenium supported on activated carbon or alumina catalysts, used in hydrogenation, dechlorination, deep desulfurization, fuel cell desulfurization and other fields. SNCAT series: powder supported nickel catalyst, fixed bed supported nickel catalyst, used in C5 resin hydrogenation, C9 resin hydrogenation, DCPD resin hydrogenation, rosin and its resin,wiped film evaporator, PAO polyalphaolefin, oil hydrogenation and so on. The latest chemical consulting, please click to follow me! Information source of this article | Environmental Protection Chemical Platform Please contact us if there is any violation or infringement. 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Original Title: [Dry Goods] Structures and Working Principles of 22 Kinds of Evaporation and Crystallization Equipment, Illustrated Central-circulation tubular evaporator The heating chamber of the central circulation tube evaporator is composed of a vertical heating tube bundle (boiling tube bundle). In the center of the tube bundle, there is a tube with a larger diameter, called the central circulation tube, whose cross-sectional area is generally 40-100% of the total cross-sectional area of the heating tube bundle. When the heating medium is introduced between the tubes for heating, the heated area of the liquid per unit volume in the heating tube is larger than that in the central circulating tube, so that the relative density of the liquid in the heating tube is small, thereby causing a density difference between the liquid in the central circulating tube and that of the heating tube, and the density difference causes the solution to flow in a natural circulation manner of descending from the central circulation tube and then ascending from the heating pipe. The circulation speed of the solution depends on the density difference produced by the solution and the length of the tube. The greater the density difference, the longer the tube, and the greater the circulation speed of the solution. However, due to the limitation of the total height, the length of the heating tube of this type of evaporator is generally 1 ~ 2 m, the diameter is 25 ~ 75 mm, and the length-diameter ratio is 20 ~ 40. Performance characteristics: The central circulation tube evaporator has the advantages of compact structure, convenient manufacture and reliable operation, so it is widely used in industry and is called "standard evaporator". But in fact, due to the limitation of structure, its circulation speed is relatively low (generally below 0.5m/s); and because the solution circulates continuously in the heating tube, its concentration is always close to the concentration of the finished solution, so the boiling point of the solution is high and the effective temperature difference is reduced. In addition, the cleaning and maintenance of the equipment is not convenient enough. Externally heated evaporator The structural feature of the externally heated evaporator is that the heating chamber is separated from the separation chamber, which not only facilitates cleaning and replacement, but also reduces the total height of the evaporator. Because the heating pipe is long (the ratio of the pipe length to the pipe diameter is 50-100), and the solution in the circulating pipe is not heated, the circulating speed of the solution is high, which can reach 1.5m/s. Rising film evaporator The heating chamber of the rising film evaporator is composed of one or several vertical long tubes. The diameter of the heating tube is usually 25 ~ 50mm, and the ratio of the tube length to the tube diameter is 100 ~ 150. After being preheated, the raw material liquid enters from the bottom of the evaporator, and the heated steam is condensed outside the tube. When the solution is heated and boiled, it vaporizes rapidly, and the generated secondary steam rises at a high speed in the tube, driving the liquid to flow upward along the inner wall of the tube in a film shape, and the rising liquid film continues to evaporate due to heating. Therefore, the solution is gradually concentrated in the process of rising from the bottom to the top of the evaporator, and the concentrated solution enters the separation chamber and is discharged from the bottom of the separator after being separated from the secondary steam. The secondary steam velocity at the outlet of the heating tube under normal pressure shall not be less than 10 m/s, generally 20 ~ 50 m/s, and sometimes 100 ~ 160 m/s or higher during decompression operation. Performance characteristics: Expand the full text The climbing film evaporator is suitable for the solution with large evaporation capacity (i.e. dilute solution), heat sensitivity and easy foaming, but not suitable for the solution with high viscosity,jacketed glass reactor, crystal precipitation or easy scaling. Horizontal evaporator It is basically similar to the structure of the horizontal shell and tube condenser. According to the way of liquid supply, it can be divided into shell and tube evaporator and dry evaporator. Horizontal shell and tube evaporators are widely used in closed saline circulation systems. Performance characteristics: Compact structure, good contact between liquid and heat transfer surface, high heat transfer coefficient. However, it needs to be filled with a large amount of refrigerant, and the liquid column will have a certain impact on the evaporation temperature. And when the concentration of the saline is reduced or the brine pump is shut down for some reason, the saline may be frozen in the pipe. If the refrigerant is Freon, it is difficult for the lubricating oil dissolved in the Freon to return to the compressor. In addition, it is necessary to stop working during cleaning. Vertical tube type cold water tank evaporator Spiral tube evaporator The common point of vertical tube and spiral tube evaporators is that the refrigerant evaporates in the tubes, and the whole evaporator tube group is immersed in the box (or pool, tank) filled with secondary refrigerant. In order to ensure that the secondary refrigerant circulates in the box at a certain speed, a longitudinal partition is welded in the box and a spiral stirrer is installed. The coolant flow rate is generally 0.3 ~ 0.7 m/s to enhance heat transfer. Performance characteristics: Vertical tube and spiral tube evaporators can only be used in open cycle systems, so the secondary refrigerant must be non-volatile substances, such as saline and water. If saline is used,hemp extraction centrifuge, the evaporator tubes are easily oxidized, and the saline is easy to absorb moisture and reduce the concentration. These two evaporators can directly observe the flow of secondary refrigerant and are widely used in saline refrigeration system with ammonia as refrigerant. Cooling tube bank A cooling calandria is an evaporator used to cool the air. It is widely used in low temperature cold storage. The refrigerant flows and evaporates in the cooling tube, and the cooled air outside the tube as the heat transfer medium makes natural convection. Performance characteristics: The biggest advantage of the cooling calandria is that it is simple in structure, easy to make, and causes less dry loss to the non-packaged food stored in the warehouse. However, the heat transfer coefficient of the calandria is low, and the defrosting operation is difficult, which is not conducive to the realization of automation. For the ammonia direct cooling system, the seamless steel tube is welded, and the smooth tube or wound finned tube is used; for the Freon system, the wound or set finned copper tube is mostly used. Coil type calandria Coil type jacking pipe gravity liquid supply or ammonia pump liquid supply can be used; single-row and double-row coil type wall calandria can be used for an ammonia pump liquid supply system and a gravity liquid supply system of a bottom-in and top-out type, and a single coil type calandria can also be used for an ammonia pump top in and bottom out liquid supply system and a thermal expansion valve liquid supply system. Performance characteristics: The coiled calandria has the advantages of simple structure, easy manufacture, small liquid storage and strong applicability. Its main disadvantage is that the steam produced in the lower section of the calandria can not be drawn out in time and can only be discharged after passing through the full length of the calandria, so the heat transfer coefficient is small and the vapor-liquid two-phase flow resistance is large. Air cooler (air cooler) Air cooler is a complete set of equipment composed of axial flow fan and cooling calandria. It relies on the fan to force the air in the warehouse to flow through the cooling pipes in the box for heat exchange, so as to cool the air and achieve the purpose of reducing the temperature of the warehouse. The air cooler can be divided into dry type, wet type and dry-wet mixed type according to the way of cooling air. Among them, the refrigerant or secondary refrigerant flows in the calandria and passes through the tube wall to cool the air outside the tube, which is called dry air cooler; the sprayed secondary refrigerant liquid directly exchanges heat with the air, which is called wet air cooler; the mixed air cooler has a secondary refrigerant spraying device in addition to cooling the calandria. Dry air coolers commonly used in cold storage can be divided into ceiling type and floor type according to their installation positions. They are all composed of air cooling pipes, ventilators and defrosting devices, and the cooling pipes in the air cooler are all sheet-type. Large dry air coolers are often floor-mounted. External circulation type evaporation equipment The evaporator is characterized in that the heating pipe is lengthened and the heating chamber is arranged outside the evaporator, so that the total length of the evaporator can be reduced, and meanwhile, the circulating pipe is not heated by steam, so that the natural circulation speed of the solution is higher. Basket evaporator It is an improvement of the central circulation tube evaporator. The heating chamber is like a hanging basket, which is hung at the lower part of the evaporator shell and can be taken out from the top for easy cleaning and replacement. The heat medium enters that heat chamber through the central steam pipe, cbd crystallization equipment ,rotovap distillation, and there is an annular channel between the outer wall of the heating cham and the inner wall of the evaporator shell, which acts like a central circulating pipe. During operation, the solution descends along the annulus and ascends along the heating tube, forming a natural circulation. Generally, the cross-sectional area of the annular gap is about 100-150% of the total area of the heating tube, so the solution circulation rate is relatively high (about 1-1.5m/s). Since the boiling liquid is in contact with the evaporator shell at a lower temperature, there is less heat loss. Performance characteristics: The basket-type evaporator is suitable for evaporating the solution which is easy to scale or has crystal precipitation. Its disadvantage is that the structure is complex and the amount of equipment materials required for unit heat transfer surface is large. Levin evaporator The structure of the Levin evaporator is characterized in that a boiling chamber is additionally arranged at the upper part of the heating chamber. In this way, the solution in the heating chamber can be vaporized only when it rises to the boiling chamber due to the action of this additional liquid column. A longitudinal partition is installed above the boiling chamber to prevent bubbles from growing. In addition, since the circulation pipe is not heated, the driving force for the circulation of the solution is large. The height of the circulating pipe is generally 7 ~ 8 m, and its cross-sectional area is about 200 ~ 350% of the total cross-sectional area of the heating pipe. Therefore, the flow resistance in the circulating pipe is small, and the circulating speed can be as high as 2 to 3 m/s. Performance characteristics: The advantages of Levin evaporator are high circulation speed and good heat transfer effect. Because the solution does not boil in the heating tube, it can avoid the precipitation of crystals in the heating tube, so it is suitable for the treatment of solutions with crystal precipitation or easy scaling. Its disadvantage is that the equipment is huge and the required plant is high. In addition, since the static pressure of the liquid layer is large, the pressure of the heating steam is required to be high. Forced circulation evaporator The above evaporators are all natural circulation evaporators, that is, the circulation of the solution is caused by the density difference between the heating tube and the circulating tube. The circulation speed is generally low, so it is not suitable to deal with the solution with high viscosity, easy scaling and a large number of precipitated crystals. For the evaporation of such solutions, a forced circulation type evaporator may be used. This kind of evaporator uses external power (circulating pump) to make the solution circulate at a high speed in a certain direction. The circulation speed can be controlled by adjusting the flow of the pump. Generally, the circulation speed is above 2.5m/s. Performance characteristics: This kind of evaporator has the advantages of large heat transfer coefficient and good adaptability to materials with high viscosity or easy crystallization and scaling, but its power consumption is large. Falling film evaporator The difference between the falling-film evaporator and the rising-film evaporator is that the feed liquid is added from the top of the heating tube. Under the action of its own gravity, the solution flows downward along the inner wall of the tube in a film shape and is evaporated and concentrated. The vapor-liquid mixture enters the separation chamber from the bottom of the heating tube. After gas-liquid separation, the finished liquid is discharged from the bottom of the separator. In order to make the solution form a uniform film on the wall, the top of each heating tube needs to be equipped with a liquid film distributor. There are many types of film distributor, three of which are commonly used. A cylinder with a spiral groove is used as the draft tube, and the liquid flows down along the groove and is distributed on the inner wall of the whole tube. The lower part of the draft tube is a cone, and the bottom of the cone is concave downward to prevent the liquid flowing down along the cone slope from gathering in the center. The liquid descends along the inner wall of the heating tube in a film shape through the tooth gap. Performance characteristics: The falling film evaporator can evaporate the solution with higher concentration, and is also suitable for the material with higher viscosity. However, it is not suitable for the solution which is easy to crystallize or scale. In addition, because the liquid film is not easy to distribute evenly in the tube, its heat transfer coefficient is smaller than that of the climbing film evaporator. Scraper film evaporator The scraper film evaporator uses the scraper action of the rotating scraper to distribute the liquid on the wall of the heating tube. Its outstanding advantage is that it has strong adaptability to materials, such as materials with high viscosity, heat sensitivity, easy crystallization and scaling. A heating steam jacket is arranged outside the shell of the scraper film evaporator, and a rotatable stirring scraper is arranged inside the shell of the scraper film evaporator, wherein the rotating scraper can be fixed or movable. The gap between the former and the inner wall of the shell is 0.75 ~ 1.5 mm, and the gap between the latter and the wall of the shell varies with the number of revolutions of the stirring shaft. After the feed liquid is added from the upper part of the evaporator along the tangential direction, the solution forms a downward spiral film on the inner wall of the shell under the drive of gravity and the rotary scraper, and is continuously evaporated and concentrated in the descending process to obtain the finished liquid at the bottom. In some cases, the solution may be evaporated to dryness to obtain a solid product directly from the bottom. Performance characteristics: The disadvantages of this kind of evaporator are complex structure, large power consumption, small heat transfer area, generally 3 ~ 4 m2, the maximum is not more than 20 m2, so its processing capacity is small. MVR falling film evaporator The material stock solution is added from the upper tube box of the heat exchanger, the material is distributed into each heat exchange tube through the liquid distributor, a uniform liquid film is formed along the inner wall of the heat exchange tube, the liquid film in the tube is heated by the heating steam of the shell side in the downward flow process, and the liquid film is boiled and evaporated while flowing downward. And that material at the bottom end of the heat exchange tube become concentrated solution and secondary steam. The concentrated solution falls into the lower channel box, and the secondary steam enters the gas-liquid separator. In the gas-liquid separator, liquid droplets entrained in the vapor are removed, and the pure vapor is transferred from the separator to the compressor. The compressor compresses the secondary steam and delivers it as heating steam to the shell side of the heat exchanger for the heat source of the evaporator. And that continuous evaporation proces is realized. Performance characteristics: 1. High heat exchange efficiency 2. Small floor area And 3, the retention time of the materials is short, and the materials are not easy to deteriorate. 4. It is suitable for materials with higher viscosity. Scope of application: The falling-film evaporator is suitable for the pre-concentration process of MVR evaporation and crystallization, and can evaporate materials with high viscosity, especially heat-sensitive materials, but it is not suitable for the treatment of materials with crystallization. MVR forced circulation evaporator The forced circulation evaporator consists of an evaporation separator, a heat exchanger and a forced circulation pump. The material in the heat exchange tube of the heat exchanger is heated by the steam outside the heat exchange tube to raise the temperature. Under the action of the circulating pump, the material rises into the evaporation separator, and the material is evaporated in the evaporation separator due to the decrease of the static pressure of the material. And secondary steam generate by evaporation overflows from that material, the material is concentrate to generate supersaturation so as to enable crystals to grow, the supersaturated material enters the for circulating pump and enters the heat exchanger under the action of the circulating pump, and the material is circulated in this way to be continuously evaporated and concentrated or concentrated and crystallized. The crystal slurry is output from the circulating pipeline by a discharge pump. The secondary steam in the evaporation separator is delivered to the compressor after being purified by the separation and defoaming device at the upper part of the evaporation separator, and the compressor compresses the secondary steam and delivers the secondary steam to the shell side of the heat exchanger to be used as the heating steam of the evaporator, so as to realize the continuous evaporation of heat energy circulation. Performance characteristics: 1. Low heat transfer coefficient ； 2. The heat exchange surface is not easy to form scale or crystallization 。 Scope of application: It is suitable for the evaporation concentration or evaporation crystallization process of high-viscosity materials which are easy to scale and produce crystallization. MVR Evaporation OSLO Crystallizer OSLO evaporative crystallizer consists of OSLO evaporator, heat exchanger and forced circulation pump. The material in the heat exchange tube of the heat exchanger is heated by the steam outside the heat exchange tube to raise the temperature. Under the action of the circulating pump, the material rises to the OSLO evaporative crystallizer, and the material is evaporated in the OSLO evaporative crystallizer due to the decrease of the static pressure of the material. The secondary steam generated by evaporation overflows from the material, and the material is concentrated to generate supersaturation. The supersaturated solution descends in the central tube of the OSLO evaporation crystallizer and fully contacts with the small crystals in the solution to further grow the crystals. The larger crystals are elutriated by the elutriation column, and the large crystals are precipitated below the elutriation column and transported to the thickener by the crystal slurry pump. Smaller crystals continue to grow in the OSLO crystallizer. The clarified liquid is delivered to the heat exchanger by the forced circulation pump for further heating, and the material is continuously evaporated and concentrated or concentrated and crystallized in this way. The secondary steam in the OSLO evaporation crystallizer is delivered to the compressor after being purified by the separation and defoaming device at the upper part of the separator. The compressor compresses the secondary steam and delivers it to the shell side of the heat exchanger to be used as the heating steam of the evaporator. And that heat energy circulation continuous evaporation is realize. Main features: 1, that crystal granularity is large and uniform; 2. Large equipment volume and high cost Scope of application: It is suitable for the production of materials requiring large crystal size. MVR evaporation DTB crystallizer DTB type crystallizer is a typical crystallizer with internal circulation of crystal slurry. Because the crystallizer is provided with the inner draft tube, the circulating channel is formed, so that the crystal slurry has a good mixing condition, the supersaturation degree can be quickly eliminated in the evaporative crystallization, and the supersaturation degree of the solution can be kept at a lower level. It is especially suitable for products with steep solubility curve. The DTB type crystallizer has good performance and high production strength, can produce larger crystal grains, and is not easy to scab in the crystallizer. It has become one of the main forms of continuous crystallizer. Performance characteristics: High production strength, large crystal particles and stable performance. Scope of application: It is suitable for the production of materials with large crystal size and high production intensity. Vertical crystallization box The vertical crystallization box is usually used for the products with small output and short crystallization period Horizontal crystallization box Horizontal crystallization box is often used for those with large output and long cycle. (1) the volume is large, and the power consumed by the crystal suspension stirring is small; (2) materials with higher crystallization speed can be operated in series for continuous crystallization. The best control for continuous operation is to make the solution start to generate crystal nuclei at the inlet, and generate enough crystal nuclei soon after entering the equipment. These crystal nuclei are suspended in the solution and grow into crystals as the solution moves slowly in the tank. And finally discharging from the other end of the crystallization tank. Vacuum crystal boiling pot It is suitable for products with fast crystallization speed,thin film distillation, easy natural crystallization and large crystal requirement, and can control the evaporation speed and feeding speed of the solution with simple structure. Source: Water, Gas and Solid Environmental Protection Technology Collection Return to Sohu to see more Responsible Editor:. toptiontech.com