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Good Helper for Railway Coal Transportation in Northern China in Winter-Anti-freezing Dust Suppressant _ Wagon _ Carrying _ Water

Tue, 06 Sep 2022 07:42:44 +0200

Original Title: Good Helper for Railway Coal Transportation in Northern China in Winter-Anti-freezing Dust Suppressant Antifreezing dust suppressant is an antifreezing dust suppressant specially developed for railway coal transportation in northern China in winter. The dust suppressant well combines the dust suppression function and the anti-freezing function together, so that the dust suppressant not only has excellent moisture retention, bonding, film forming and crusting capabilities, but also has an effective anti-freezing function, thereby well solving the problems encountered in coal transportation by trains in northern areas in cold winter. The outstanding features of the antifreeze dust suppressant include: 1, that antifreeze dust suppressant organically combines dust suppression and antifreeze, so that the product has various effects of antifreezing,rotovap distillation, moisturizing, bon, forming a film, forming a shell and the like. And 2,cbd crystallization equipment, the antifreezing dust suppressant is an instant type, is easy to dissolve in water, does not agglomerate or pill in water, reduces the stirring time, saves electric energy, reduces the labor intensity of workers, winterization filtration ,wiped film evaporator, and is more convenient to use. 3. The dust suppression component of the antifreezing dust suppressant is modified plant fiber, which can form a high-viscosity network structure when sprayed on the surface of coal, and has good dust suppression effect. 4. The antifreezing dust suppressant can greatly reduce the freezing point and prevent the bulk water-containing materials and wagons from freezing. In severe cold seasons or severe cold areas, the bulk materials containing water transported by wagons, such as mined coal, will be frozen together with the wagons and cannot be unloaded. Before unloading, they must be thawed in the thawing room, which not only wastes a lot of time, but also consumes a lot of resources, reduces the efficiency of vehicles, increases transportation costs, and delays production. And 5, that dust suppressant is a powdery product, is more convenient and SAF to store and transport than a liquid dust suppressant, and is not affected by cold weather. Usage: 1. Preparation of the antifreezing dust suppressant solution: according to the local winter temperature, add the antifreezing dust suppressant into the water according to the proportion recommended by the sales engineer, and stir it while adding materials until it is completely dissolved, that is, prepare the dust suppresser solution. 2. Spraying amount of dust suppressant liquid: coal shall be sprayed on the surface of coal at the amount of 1.6 to 2 liters per square meter during railway transportation. If the coal has a high moisture content, the spray rate may be increased to 2.5 to 3.5 liters per square meter for frost protection. Return to Sohu , see more Responsible Editor: (function() { function getBrandHtml() { var brands = ,thin film distillation, html = ''; for(var i = 0; i < brands.length; i++) { var brand = brands; if(brands.length i+1) { html+= '

A pen-sized electric drill is a must for DIY people. Drill where you want to drill _ drill bit _ tool _ manual

Tue, 06 Sep 2022 07:42:38 +0200

Original title: An electric drill the size of a pen is a must for DIY people. Where do you want to drill? Foreword In life, we always use a lot of tools, such as screwdrivers, wrenches, hammers, DIY people's tools are countless, but the traditional tools are relatively heavy, and storage is also more troublesome, it is better to try the following portable tools, not only powerful, more convenient to carry, storage, help you easily complete all kinds of repairs in life, DIY production. Electric drill is a kind of thing that is difficult to do without when it is needed. Compared with the traditional heavy impact electric drill, I recently received this WOWSTICK PLAY lithium mini electric drill pen, which is more suitable for simple maintenance and DIY production scenarios. It is compact, portable, safe and efficient, and more convenient to use. Appearance In addition to the body of the electric drill, it is equipped with two charging cables, eight different electric drills and multi-language instructions. It also has a white wavy support storage box, which is convenient for daily storage, and there is no need to worry about finding it. The electric drill pen is equipped with eight precision high-quality high-speed steel drill bits, which can be replaced by you. The thinnest is 0.8mm and the thickest is 2.2mm. It is easy to drill through plastic, wood, shell, circuit board and other materials. Expand the full text The electric drill pen is assembled and can be used normally. The body of the electric drill pen adopts an all-aluminum integrated polishing design, with a matte texture on the surface, which is full of texture and high appearance. With the new and original design of the pen cap, there is no need to worry about the insecurity caused by the exposed tool head. If you don't pull out the cap of the pen, you can't see that it's an electric drill tool at all, more like a beautiful pen. The body of the electric drill pen is printed with the English product name. Type-c charging mode can be used wirelessly at home and outdoors when fully charged, which is convenient and safe. Weighing less than 50g, it is as comfortable as holding a pen in the hand, Borehole Drill Bits , fitting the palm, and the frosted texture also enhances the holding stability. Experience This WOWSTICK PLAY lithium mini electric drill pen is not only beautiful, but also easy to operate, low noise and strong strength. After the electric drill cap is turned on, the electric drill can be turned on by pressing the switch on the pen body. The design of stopping immediately after releasing the hand is safe and reliable, and there is no pressure on the hand. When using the electric drill pen, it is as easy and simple as holding the pen, without the feeling of heavy burden, even if the electric drill is used for a long time, it is not tiring. Even girls can easily pick it up and use it at home to punch holes, string bracelets and so on, which will make you more efficient at work. Although the size is small, but the strength is not weak, the all-metal gearbox, the speed can reach 400r/min, effectively improve the efficiency of mini drilling. It can easily drill through the conventional thickness of sheet, plastic, aluminum, coins, circuit boards and other materials, but it should be noted that it is only applicable to thinner materials, do not drill too thick metal. Diamond Coin: Plastic Wood Usually like to tinker with all kinds of small handicraft works, you can use this electric drill pen to make. In terms of battery life, this electric drill pen has a built-in 280 mAh lithium battery, which can be used continuously for 2 hours after full charge. I used it for about an hour and a half after it was fully charged, and the electric drill pen was still charged. This kind of design without lithium battery greatly expands the use scenario, whether it is used indoors or outdoors, it can be carried with you, which is very convenient. Drill bit replacement is also very simple, do not need to borrow any auxiliary tools, just unscrew the Chuck and then directly remove the drill bit, and then replace the appropriate drill bit. Unscrew each part of the electric drill pen, select an electric drill, and then combine them together. Sum up Friends who like to make handicraft works are blessed to have eight precision high-quality high-speed steel drill bits, which can be replaced by you. They are not only beautiful, but also powerful. With them, drilling is actually very easy. Parents and children can also do handicraft together and enjoy parent-child time. Return to Sohu to see more Responsible Editor: (function() { function getBrandHtml() { var brands = ,mining drill bit, html = ''; for(var i = 0; i < brands.length; i++) { var brand = brands; if(brands.length i+1) { html+= '

Design and Construction Organization Plan of Lightning Protection Engineering (I) _ Grounding

Tue, 06 Sep 2022 07:42:21 +0200

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,dth rock bit, 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,rock drilling tools, 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 ,Mining Drilling Equipment, 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,mining dth bit, 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

Dry goods, the relationship between geometric angle of twist drill and sharpening accuracy _ vertex angle

Tue, 06 Sep 2022 07:42:05 +0200

Original title: Dry goods, the relationship between geometric angle of twist drill and sharpening accuracy Source: Mechanical Professor Geometric angle of twist drill: 1. Vertex angle 2 Φ It is the angle between the projections of the two main cutting edges in the midplane. The smaller the vertex angle is, the longer the main cutting edge is, the load on the unit cutting edge is reduced, and the axial force is reduced, which is beneficial to the axial stability of the drill. And the tool tip angle at the excircle is increased, thereby being beneficial to heat dissipation and improving the durability of the tool. However, the decrease of the vertex angle will weaken the strength of the drill point, increase the chip deformation, and lead to an increase in torque. A standard twist drill has a vertex angle of about 118 °. HSS high speed steel drill: the top angle is generally 118 degrees, sometimes more than 130 degrees; HM carbide drill: the top angle is generally 140 degrees; straight flute drill is often 130 degrees, and three-edged drill is generally 150 degrees. 2. Front angle The angle between the rake face and the base plane in an orthogonal plane. The relationship between the rake angle of any selected point on the main cutting edge and the helix angle, cutting edge angle and cutting edge inclination angle of the point is tan = tan/sin + tancos (2-3). As the helix angle gradually decreases from the outer diameter to the drill center,dth drilling hammer, the cutting edge inclination angle also gradually decreases (negative value increases). When the cutting edge angle is constant, the rake angle decreases from + 30 ° to -30 °. The cutting condition near the center of the drill bit is very poor. 3. Rear angle The clearance angle at any point on the cutting edge is the angle between the cutting plane and the flank at that point. The relief angle of the drill is not measured in the main profile, but in the assumed working plane (feed profile). In the drilling process, it is this relief angle that actually plays a role, and it is also convenient to measure. The clearance angle of the drill bit is obtained by sharpening. During sharpening,Tapered Rock Bit, the outer edge of the drill bit shall be sharpened to a smaller angle (about 8 ° ~ 10 °), and the area near the drill center shall be sharpened to a larger angle (about 20 ° ~ 30 °). The reason for sharpening in this way is that the relief angle can be adapted to the change of the rake angle of the main cutting edge, so that the wedge angle of each point is roughly equal, thus achieving the relative balance of sharpness, strength and durability, making up for the influence caused by the reduction of the actual working relief angle of each point on the cutting edge due to the axial feed movement of the drill bit, and improving the working conditions of the chisel edge. 4. Main deflection angle and end edge inclination angle The main cutting angle of a selected point on the main cutting edge of a twist drill is the angle between the projection of the main cutting edge on the base plane of the point and the drilling feed direction. Due to the different base planes of each point on the main cutting edge of the twist drill, the main deflection angle of each point also changes accordingly. After the twist drill is ground to a vertex angle of 2Φ, the main cutting angle of each point is determined, dhd drill bit ,dth hammer bit, and the relationship between them is tan = tanΦcos (2-2). The end face cutting edge inclination angle of the selected point is the included angle between the projection of the main cutting edge in the end face and the base surface of the point. Expand the full text Because the absolute value of the edge inclination angle of each point on the cutting edge gradually increases from the outer edge to the drill center, the main deflection angle of each point on the cutting edge is also large at the outer edge and small at the drill center. 5. Angle of chisel edge The chisel edge is a section of cutting edge perpendicular to the axis on the end face of the twist drill, and the angle of the cutting edge includes a chisel edge bevel angle, a chiset edge rake angle, and a chiset edge relief angle. 1) Chisel edge bevel The angle between the chisel edge and the main cutting edge in the end plane. It is naturally formed when sharpening the drill bit. The standard twist drill with normal top angle and back angle sharpening. The larger the back angle, the smaller the angle. Decreasing the angle increases the chisel edge length. 2) Chisel edge rake angle Since the base plane of the chisel edge is located within the tool solid, the chisel edge rake angle is negative. 3) Chisel edge relief angle. For standard twist drills, =- (54 ° ~ 60 °), = 30 ° ~ 36 °. Therefore, during drilling, the metal at the chisel edge is severely squeezed and deformed, and the axial force is very large. Experiments show that about 50% of the axial force is generated by the chisel edge when machining with a standard twist drill. For larger diameter twist drills, it is generally necessary to grind the chisel edge to reduce the axial force. First of all, "less grinding" is "no grinding". Grinding in a hurry when you get the drill bit must be blind grinding. Only by placing the blade in a good position before sharpening can we lay a solid foundation for the next step of "sharpening", which is very important. Four pithy formulas are used here to guide the sharpening process, and the effect is better. Pithy formula 1: "The cutting edge is placed flat against the wheel surface." This is the first step of the relative position of the drill bit and the grinding wheel, and there are often students who lean on the grinding wheel to start sharpening before the cutting edge is flat. This is definitely not good for grinding. The "cutting edge" here is the main cutting edge, and "flat" means that the main cutting edge of the part to be sharpened is in a horizontal position. "Face" means the surface of a grinding wheel. " "Lean on" means to get closer slowly. At this time, the drill bit cannot contact the grinding wheel. Pithy formula 2: "The drill shaft slants out the sharp angle." This refers to the positional relationship between the drill axis and the surface of the grinding wheel. The point angle is the half of the point angle 118 ° ± 2O, which is about 60 °. This position is very important because it directly affects the point angle, the shape of the main cutting edge and the bevel angle of the chisel edge. Students should be reminded to memorize the angle of 60 ° in a commonly used set square of 30 °, 60 ° and 90 °, which is easy for students to master. Pithy formula 1 and pithy formula 2 both refer to the relative position of the drill bit before sharpening. The two should be considered as a whole. Do not neglect to set the bevel angle in order to level the cutting edge, or neglect to level the cutting edge in order to set the oblique axis. These mistakes are often made in actual use. The drill bit is now in the correct position and ready to contact the grinding wheel. Pithy formula 3: "Grind the back from the blade to the back." This refers to the slow sharpening from the cutting edge of the drill bit along the entire back. This facilitates heat dissipation and sharpening. On the basis of stabilizing and consolidating the first and second pithy formulas, the drill bit can gently contact the grinding wheel at this time for a small amount of sharpening. When sharpening, observe the uniformity of sparks, adjust the pressure in time, and pay attention to the cooling of the drill bit. When you start sharpening again after cooling, you should continue to set the position of the first and second pithy formulas, which is often difficult to grasp at the beginning of learning, and often change the correctness of its position involuntarily. Pithy formula 4: "Swing up and down and don't warp your tail." This action is also very important in the process of drill sharpening. Some students often change "swinging up and down" into "rotating up and down" when sharpening,fastest dth hammer, which destroys the other main edge of the drill. At the same time, the tail of the drill bit should not be higher than the horizontal center line of the grinding wheel, otherwise the cutting edge will be blunt and can not be cut. Return to Sohu to see more Responsible Editor:. wt-dthtools.com

Drilling technology Daquan, this must be collected! _ Drill

Tue, 06 Sep 2022 07:41:52 +0200

Original Title: Drilling Technology Encyclopedia, This Must Be Collected! Drill, as the most common tool in hole processing, is widely used in mechanical manufacturing, especially in the processing of holes in cooling devices, tubesheets of power generation equipment and steam generators. I. Characteristics of drilling Drills usually have two main cutting edges, and when machining, the drill cuts while rotating. The rake angle of the drill is getting larger and larger from the central axis to the outer edge, the cutting speed of the drill is getting higher and higher when it is closer to the outer circle, and the cutting speed decreases to the center, and the cutting speed of the rotary center is zero. The chisel edge of the drill is located near the central axis of rotation. The chisel edge has a large secondary rake angle, no chip space and low cutting speed, so it will produce a large axial resistance. If the chisel edge is ground to Type A or Type C in DIN1414 and the cutting edge near the central axis has a positive rake angle, the cutting resistance can be reduced and the cutting performance can be significantly improved. According to the shape, material, structure and function of the workpiece, the drill bit can be divided into many types, such as high-speed steel drill bit (twist drill, group drill, flat drill), solid carbide drill bit, indexable shallow hole drill, deep hole drill, trepanning drill and interchangeable head drill bit. 2. Chip breaking and chip removal The cutting of the drill is carried out in a narrow hole, and the chips must be discharged through the drill edge groove, so the chip shape has a great influence on the cutting performance of the drill. Common chip shapes include flaky chips, tubular chips, acicular chips, conical spiral chips, ribbon chips, fan-shaped chips and powdery chips. Key Chip Control in Drilling When the chip shape is not appropriate, the following problems will arise: ① Fine chips block the cutting edge groove, affecting the drilling accuracy, reducing the life of the drill bit, and even breaking the drill bit (such as powdery chips, fan-shaped chips,dth button bits, etc.); ② Long chips entangle the drill bit, which hinders the operation, causing the drill bit to break or preventing the cutting fluid from entering the hole (such as spiral chips, ribbon chips, etc.). How to solve the problem of improper chip shape: ① The chip breaking and chip removal effects can be improved by increasing the feed rate, intermittent feed, grinding the chisel edge, installing the chip breaker and other methods respectively or in combination, so as to eliminate the problems caused by chips. ② Professional chip-breaking drill can be used for drilling. For example, the addition of a designed chip breaker in the groove of the drill breaks the chips into more easily removed chips. The debris is smoothly discharged along the groove, and the phenomenon of blockage in the groove does not occur. Therefore, the new chip-breaking drill obtains a much smoother cutting effect than the traditional drill. At the same time, the short scrap iron makes the coolant flow to the drill tip more easily,down the hole bit, which further improves the heat dissipation effect and cutting performance in the processing process. Moreover, because the new chip-breaking edge penetrates the whole groove of the drill bit, it can still maintain its shape and function after many times of grinding. In addition to the above functional improvements, it is worth mentioning that the design strengthens the rigidity of the drill body and significantly increases the number of holes drilled before a single grinding. III. Drilling accuracy The accuracy of the hole is mainly composed of the hole size, position accuracy, coaxiality, roundness, surface roughness and hole burr. Factors affecting the accuracy of the hole to be machined during drilling: Expand the full text ① Bit clamping accuracy and cutting conditions, such as tool holder, cutting speed, feed rate, cutting fluid, etc.; ② Drill size and shape, such as drill length, blade shape, drill core shape, etc.; ③ Workpiece shape, such as orifice side shape, orifice shape, thickness, clamping state, etc. Reaming Reaming is caused by the oscillation of the drill during machining. The swing of the tool holder has a great influence on the hole diameter and the positioning accuracy of the hole, so when the tool holder is worn seriously, it should be replaced with a new one in time. When drilling a small hole, DHD Drill bit ,overburden drilling systems, it is difficult to measure and adjust the swing, so it is better to use a drill with a thick shank and a small edge diameter with a good coaxiality between the blade and the shank. When the regrinding drill is used for machining, the reason for the decrease of hole accuracy is mostly due to the asymmetry of the back shape. Controlling the height difference of the cutting edge can effectively restrain the amount of hole expansion. Roundness of the hole Because of the vibration of the drill bit, the drilled hole shape is easy to be polygonal, and the lines like rifling appear on the hole wall. Common polygonal holes are mostly triangular or pentagonal. The reason for the triangular hole is that the drill bit has two rotary centers during drilling, and they vibrate at the frequency of exchanging once every 600. The main reason for the vibration is that the cutting resistance is unbalanced. When the drill bit rotates for one turn, the resistance is unbalanced during the second turn of cutting due to the poor roundness of the processed hole. The last vibration is repeated again, but the vibration phase has a certain deviation. Cause rifling pattern to appear on that walls of the hole. When the drilling depth reaches a certain degree, the friction between the drill edge and the hole wall increases, the vibration decreases, the rifling disappears, and the roundness becomes better. The orifice of this pass is funnel-shaped when viewed in longitudinal section. For the same reason, pentagonal and heptagonal holes may also appear in cutting. In order to eliminate this phenomenon, in addition to controlling the factors such as Chuck vibration, cutting edge height difference, back and edge shape asymmetry, measures such as improving drill rigidity, increasing feed per revolution, reducing clearance angle and grinding chisel edge should be taken. Drill holes on sloped and curved surfaces When the cutting surface or penetration surface of the drill is inclined, curved or stepped, the positioning accuracy is poor, and the tool life is reduced due to the radial single-sided cutting surface of the drill. To improve the positioning accuracy, the following measures can be taken: 1. Drill the center hole first ； 2. Milling hole seat with end mill ； 3. And that selection cut-in property is good Drill bit with good rigidity; 4. Reduce the feed speed 。 Treatment of burrs During drilling, burrs will appear at the entrance and exit of the hole, especially when machining materials with high toughness and thin plates. The reason is that when the drill bit is about to drill through, the material to be processed is plastically deformed. At this time, the triangular part that should be cut by the cutting edge of the drill bit near the outer edge is deformed and bent outward under the action of axial cutting force, and further curled under the action of the chamfer of the outer edge of the drill bit and the edge surface of the cutting edge, forming curling or burrs. IV. Processing conditions of drilling In the catalogue of general drill product sample book, there is a Reference Table of Basic Cutting Parameters arranged by processing materials. Users can refer to the cutting parameters provided to select the cutting conditions for drilling. Whether the selection of cutting conditions is appropriate or not should be judged comprehensively through trial cutting according to the factors such as machining accuracy, machining efficiency and drill life. 1. Drill life and machining efficiency On the premise of meeting the technical requirements of the machined workpiece, whether the drill bit is used properly or not should be measured comprehensively according to the service life and machining efficiency of the drill bit. Cutting path can be selected as the evaluation index of drill life, and feed speed can be selected as the evaluation index of machining efficiency. For high speed steel drill bit, the service life of the drill bit is greatly affected by the rotary speed, and is less affected by the feed per revolution, so the machining efficiency can be improved by increasing the feed per revolution, and the longer service life of the drill bit can be ensured. However, it should be noted that if the feed per revolution is too large, the chip will be thickened, resulting in difficulty in chip breaking. Therefore, the range of feed per revolution that can successfully break the chip must be determined through trial cutting. For cemented carbide drill, the cutting edge has a large chamfer in the negative rake angle direction, and the optional range of feed per revolution is smaller than that of high-speed steel drill. If the feed per revolution exceeds this range during machining, the service life of the drill will be reduced. Because the heat resistance of cemented carbide drill is higher than that of high-speed steel drill, the rotary speed has little effect on the life of the drill, so the method of increasing the rotary speed can be used to improve the processing efficiency of cemented carbide drill and ensure the life of the drill. 2. Reasonable use of cutting fluid The cutting of drill is carried out in the hole with narrow space, so the type of cutting fluid and the way of injection have a great influence on the life of drill and the machining accuracy of the hole. Cutting fluid can be divided into two categories: water-soluble and water-insoluble. The water-insoluble cutting fluid has good lubricity, wettability and adhesion resistance, and also has anti-rust effect. Water-soluble cutting fluid has good cooling property, no smoke and no flammability. For the sake of environmental protection, the amount of water-soluble cutting fluid is large in recent years. However, if the dilution ratio of the water-soluble cutting fluid is improper or the cutting fluid deteriorates, the service life of the tool will be greatly shortened, so attention must be paid in use. Whether it is water-soluble or non-water-soluble cutting fluid, the cutting fluid must fully reach the cutting point in use, and the flow, pressure, nozzle number and cooling mode (internal cooling or external cooling) of the cutting fluid must be strictly controlled. V. Re-sharpening of drill bit Bit regrinding discrimination The criteria for re-sharpening of drill bits are: 1. Cutting edge Wear loss of chisel edge and edge land; 2. Dimensional accuracy and surface roughness of the hole to be machined ； 3. The color of the swarf , shape; 4. Cutting resistance (Indirect values of spindle current, noise, vibration, etc.); 5. Processing quantity, etc 。 In actual use, accurate and convenient criteria should be determined from the above indicators according to the specific situation. When the wear loss is used as the criterion, the best regrinding period with the best economy should be found out. Because the main grinding parts are the back of the head and the chisel edge, if the wear of the drill bit is too large, the grinding time is too long, the grinding amount is too large, and the number of times of regrinding is reduced (the total service life of the tool = the service life of the tool after regrinding × the number of times of regrinding), which will shorten the total service life; When the dimensional accuracy of the hole to be machined is used as the criterion, the column gauge or limit gauge shall be used to check the cutting expansion and non-straightness of the hole. Once the control value is exceeded, it shall be re-sharpened immediately. When the cutting resistance is used as the criterion, it can be stopped automatically immediately when the set limit value (such as spindle current) is exceeded; When the limit management of processing quantity is adopted, the above discrimination contents shall be integrated and the discrimination criteria shall be set. Method for sharpening drill bit When re-sharpening the drill, it is better to use a special machine tool for drill sharpening or a universal tool grinder, which is very important to ensure the service life and machining accuracy of the drill. If the original drill type is in good processing condition, it can be reground according to the original drill type; if the original drill is defective,mining dth bit, the rear shape can be properly improved and the chisel edge can be grinded according to the use purpose. Attention shall be paid to the following points during sharpening: 1. Prevent overheating ? Avoid reducing the hardness of the drill bit; 2. Damages on the drill bit shall be (Especially the damage on the edge surface of the blade) is completely removed; 3. The drill pattern shall be symmetrical ； 4. Be careful not to damage the cutting edge during sharpening. , and remove the burrs after sharpening; 5. For cemented carbide drill bits ? The sharpening shape has a great influence on the performance of the drill. The drill shape when leaving the factory is the best drill shape obtained through scientific design and repeated tests. Therefore, the original edge shape should be maintained when re-sharpening. This article is from Momo's WeChat public account . You can get the tutorial after paying attention to it. Return to Sohu to see more Responsible Editor:. wt-dthtools.com

Difference between Short-path Distillation and Molecular Distillation-Shanghai DEA

Tue, 06 Sep 2022 07:41:30 +0200

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, 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, 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 ,cbd centrifugal extractor, 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,50l rotovap, 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

Working principle of wiped film molecular distillation unit _ condensation

Tue, 06 Sep 2022 07:41:17 +0200

Original Title: Working Principle of Wiped Film Molecular Distillation Unit AYAN-B60 molecular distillation is a special liquid-liquid separation technology. It is different from the traditional distillation which relies on the separation principle of boiling point difference,jacketed glass reactor, but relies on the difference of mean free path of molecular motion of different substances to achieve separation. When the liquid mixture flows along the heating plate and is heated,wiped film distillation, the light and heavy molecules will escape from the liquid surface and enter the gas phase. Because the free paths of the light and heavy molecules are different, the moving distances of the molecules of different substances after escaping from the liquid surface are different. If a condensing plate is properly arranged, wiped film evaporator ,hemp extraction centrifuge, the light molecules will be condensed and discharged when they reach the condensing plate, while the heavy molecules will be discharged along the mixed liquid when they do not reach the condensing plate. In this way, the purpose of material separation is achieved. The pressure difference between the boiling film and the condensation surface is the driving force for the flow of the vapor, which is caused by a small pressure drop. Operating at 1 mbar requires a very short distance between the boiling surface and the condensing surface, and distillers based on this principle are called short-path distillers. The short-path distiller (molecular distillation) has an internal condenser on the opposite side of the heating surface and reduces the operating pressure to 0.001 mbar. Short-path distiller is a thermal separation process working under the pressure of 1 ~ 0.001 mbar. Its low boiling temperature is very suitable for heat-sensitive and high-boiling substances. It consists of a cylindrical cylinder with a heating jacket, a rotor and a built-in condenser, and a film scraper and an anti-splashing device are precisely installed on the fixing frame of the rotor. The built-in condenser is located in the center of the evaporator,decarboxylation after extraction, and the rotor rotates between the cylindrical cylinder and the condenser. The short-path distiller consists of an externally heated vertical cylinder, a condenser located at its center, and a film scraper rotating between the distiller and the condenser. Return to Sohu to see more Responsible Editor:. toptiontech.com

What is a jacketed glass reactor? Double or triple glass reactor? _ Interlayer _ Experiment _ High and Low Temperature

Tue, 06 Sep 2022 07:41:01 +0200

Originally published as What is a jacketed glass reactor? Double or triple glass reactor? Glass reactor is a commonly used biochemical instrument, which is widely used in modern fine chemicals, biopharmaceuticals, scientific research experiments and other industries. It can do concentration, distillation, reflux, separation, purification reactions and other processes under the conditions of constant speed, constant force and constant temperature. It is an ideal instrument and equipment for teaching, experiment, pilot test and production. Glass reactors can generally be divided into two categories, one is the double glass reactor, and the other is the single glass reactor. Among them,molecular distillation systems, the double-layer glass reactor is a commonly used equipment in the laboratory, which is widely used in medicine, biopharmaceuticals and other fields. To put it simply, a double-glazed reaction kettle is a single reaction kettle based on multiple functions. And after years of improvement, the reaction kettle is based on a single multifunctional glass reactor,nutsche filter dryer, so that the requirements of convenient high and low temperature control, rapid temperature rise, cooling in the experimental process, a modern laboratory, chemistry, pharmacy and the like are met. The sandwich section can be controlled for condensation or heating by different temperature requirements. The double-layer glass reactor has standard components including a stirring motor, a speed regulator, a condenser, a continuous titration funnel, a vacuum plug, a vacuum suction head,rotary vacuum evaporator, a thermometer shell, a reaction kettle and a two-meter heat-conducting silicone rubber tube. Under the condition of constant temperature, the stirring reaction can be carried out under normal pressure and negative pressure according to the use requirements. Reflux and distillation of the reaction solution can also be carried out. Therefore, it can be used in biopharmaceuticals, fine chemical plants and the synthesis of new materials. The kettle body of the double-layer glass reaction kettle is divided into two layers, and the middle part of the outer layer and the inner layer is called an interlayer. The inner layer is used to place the reaction solvent for stirring reaction. What is the function of the interlayer? According to introduction Glass reactor can not only complete high temperature experiments, but also complete low temperature reactions. However, the single-layer glass reactor has its own heating device, while the double-layer glass reactor does not, so the interlayer plays a very important role. The heating of the double-layer glass reaction kettle is completely completed through the interlayer. Specifically, the double-layer kettle is connected to the circulating oil bath, and the interlayer is filled with heat transfer oil. The power supply is plugged in to heat the materials. The same is true for the low-temperature reaction, as long as the solvent in the interlayer is replaced by ethanol. The interlayer can uniformly heat the materials, and the stirring reaction process of the materials can be conveniently and directly observed. Therefore, the role of the interlayer of the double-glass reactor can not be underestimated, which is also the reason why the double-glass reactor is becoming more and more popular. Some glass reactor manufacturers said that many customers would ask if the jacketed glass reactor was the same as the double-layer glass reactor? For this problem, the industry said that, in fact, if only from the structural point of view, jacketed glass reaction kettle and double-layer glass reaction kettle are composed of kettle body, kettle cover, jacket, transmission equipment, shaft seal equipment, agitator and support components, stirring methods are also paddle type, anchor type, turbine type and so on. Both of them are made of GG17 high borosilicate glass, which has good chemical and physical properties, relatively constant speed and safe and stable continuous work. However, the reaction solvent is placed in the inner layer of the double-layer glass reaction kettle for stirring reaction,thin film distillation, and the interlayer can be used for constant-temperature heating or cooling reaction through a cold and heat source; while the glass interlayer interface of the jacketed glass reaction kettle can be used for heating reaction through hot oil circulation, and low-temperature reaction can be carried out through refrigeration. Therefore, there are still some differences between the two. Return to Sohu to see more Responsible Editor:. toptiontech.com