Original title: The knowledge of spray drying tower is here, working principle, operating procedures, fault repair! Source: Chemical 707 Main function: the material in solution state can be sprayed into the spray drying tower, and the material is discharged in solid powder state after drying. The pressure and flow of the feed liquid pump and the size of the spray hole can be adjusted according to the process requirements to obtain the required spherical particles in a certain proportion. Most of them are used in the drying of biological pesticides, medicines and food microorganisms. Action principle: After being filtered and heated, the air enters the air distributor at the top of the dryer, and the hot air enters the drying chamber uniformly in a spiral shape. The feed liquid is atomized into extremely fine atomized liquid droplets by a high-speed centrifugal atomizer or a high-pressure atomizer at the top of the tower body, and can be dried into a finished product in an extremely short time after being contacted with air in parallel flow. The finished product is continuously output from the bottom of the drying tower and the cyclone separator, the micro-dust material is collected by the pulse bag collector, and the waste gas is emptied by the fan. Characteristics of spray drying tower 1, that dry speed is high, and the drying proces only needs a few seconds; 2, suitable for drying heat-sensitive materials; 3, wide range of use: according to the characteristics of materials, can be used for hot air drying, centrifugal granulation and cold air granulation, most of the products with very different characteristics can be produced by this machine; 4. Because the drying process is completed instantaneously, the particles of the finished product can basically maintain the approximate spherical shape of the droplets, and the product has good dispersibility, fluidity and solubility; And 5, that production proces is simplified, and the operation control is convenient. Spray drying is usually used for solutions with a solid content of less than 60%. After drying, there is no need for crushing and screening, which reduces the production process and simplifies the production process. The particle size, bulk density and moisture of the product can be adjusted by changing the operating conditions within a certain range, and the control and management are very convenient; 6. In order to prevent the materials from being contaminated and prolong the service life of the equipment, all parts in contact with the materials can be made of stainless steel. Main types of spray drying tower 1 Centrifugal spray Expand the full text High speed centrifugal spray drying is the most widely used process in the liquid process forming and drying industry. It is most suitable for producing powdery and granular solid products from solution, emulsion, suspension and pasty liquid raw materials. Therefore, when the particle size distribution, residual moisture content, bulk density and particle shape of the finished product must meet the accuracy standards, spray drying is a very ideal process. Performance characteristics: 1) the drying speed is high, the surface area of the material liquid is greatly increased after atomization, 95% -98% of water can be evaporated instantaneously in the hot air flow, the drying time is only a few seconds, and the method is particularly suitable for drying heat-sensitive materials. 2) the product has good uniformity, fluidity and solubility, high purity and good quality. And 3) that production proces is simplified, and the operation control is convenient. Liquid with moisture content of 40-60% (up to 90% for special materials) can be dried into powder products at one time, which is convenient for control and management. Adapt Material: Chemical industry: sodium fluoride (potassium fluoride), basic dyes and pigments, dye intermediates, compound fertilizers, formaldehyde, silicic acid, catalysts, sulfuric acid, amino acids, white carbon black, etc. Plastic resin: AB, ABS emulsion, urea-formaldehyde resin, phenolic resin, urea-formaldehyde resin, polyethylene, polyvinyl chloride, etc. Food industry: rich fat milk powder, milk protein, cocoa milk powder,thin film distillation, milk replacer, hunting blood powder, egg white (yellow), etc. Foods and plants: oats, chicken juice, coffee, instant tea, spice meat, protein, soy, peanut protein, hydrolysate, etc. Sugars: corn steep liquor, corn starch, glucose, pectin, maltose, potassium sorbate, etc. Ceramics: alumina, ceramic tile material, magnesium oxide, talcum powder,wiped film distillation, etc. 2 Pressure spray How it works: The working process of this unit is that the feed liquid is input under high pressure through the diaphragm pump, spraying foggy droplets, and then falling with the hot air, most of the powder is collected by the bottom discharge port of the tower, the waste gas and its tiny powder are separated by the cyclone separator, the waste gas is discharged by the exhaust fan, the powder is collected by the pollination cylinder at the lower end of the cyclone separator, and the outlet of the fan can also be equipped with a secondary dust removal device. The recovery rate is above 96-98%. Performance characteristics: 1) the drying speed is high, the surface area of the material liquid is greatly increased after atomization, 95% -98% of water can be evaporated instantaneously in the hot air flow, the drying time is only more than ten seconds to tens of seconds, and the method is particularly suitable for drying heat-sensitive materials. 2) All products are spherical particles with uniform particle size, good fluidity, good solubility, high product purity and good quality. 3) the application range is wide, according to the characteristics of materials, hot air can be used for drying, cold air can also be used for granulation, and the adaptability to materials is strong. And 4) that operation is simple and stable, the control is convenient, and the automatic operation is easy to realize. Adapt Material: Spray Dried Granules: Chemicals: catalysts, resins, synthetic washing powder, oils and fats, ammonium sulfate, dyes, dye intermediates, white carbon black, graphite, ammonium phosphate, etc. Food: amino acids and analogs, flavoring, protein, starch, dairy products, coffee extract, fish meal, meat extract, etc. Pharmaceutical: TCM drug, agricultural chemicals, antibiotics, nutsche filter dryer ,50l rotovap, medicinal granules, etc. Ceramics: magnesium oxide, porcelain clay, various metal oxides, dolomite, etc. Spray granulation: all kinds of fertilizer, aluminum oxide, ceramic powder, pharmaceutical, heavy metal, super hard steel, fertilizer, granular washing powder, TCM drug. Spray cooling granulation: amino fatty acid, paraffin, glyceryl ester, tallow, etc. It is often used in spray crystallization, spray concentration and spray reaction. 3 Traditional Chinese medicine spray The machine is fully enclosed, all parts are made of stainless steel, equipped with three-level purification device, the filtered air reaches the requirements of 100000. The cylinder and the top are equipped with a cold wall device to make the wall temperature less than 80 ℃, and the drying tower is equipped with an air brush sweeping device. The traditional Chinese medicine extract powder dried by the machine does not have the phenomenon of coking and deterioration, greatly increases the powder collection rate (more than 95%), and does not have the phenomena of medicine mixing and wall sticking. How it works: The invention relates to a high-speed centrifugal spraying device for traditional Chinese medicine extract, which is an application of centrifugal spray drying technology in the drying of specific materials, and is also a drying device which uses a high-speed centrifugal atomizer to disperse the materials into mist and fully contact with a hot air space to complete instantaneous drying and form a powdery finished product. Performance characteristics: 1) The tower body is provided with a cold air jacket; 2) The tower body is equipped with an automatic rapping device; 3) The tower body and pipeline are equipped with quick-opening cleaning holes and blowdown holes; 4) It can be equipped with automatic control constant temperature feeding tank; 5) Attached accessories of manual high-pressure washing tower can be provided; 6) The part in contact with materials shall be made of stainless steel (or made of stainless steel). 7) Two-stage cyclone dedusting device, or primary cyclone deduster and wet deduster are used for material collection; 8) Automatic control and continuous device for air inlet temperature; 9) Air sweeping device can be equipped. 4 Airflow spray How it works: Air or water vapor is mainly sprayed from a nozzle at a high speed, and the material liquid is separated into fine droplets by friction, so that the droplets are completely contacted with hot air to form heat exchange, and the whole process takes less than half a minute. It has a good effect on viscous materials, which is incomparable with other spray dryers. And that operation is convenient. Product application: Main applications are chemical industry: latex, dyes, resins, etc.; food industry: maltose Dextrin, starch, etc.; Dairy industry It is also often used in the building materials industry. Operating procedures for spray drying tower The operating procedure of the spray drying system is to clarify the technical characteristics of the equipment, check and confirm the production operation, stop the operation and clean the system. The specific procedures are as follows: 1 Clarify the technical characteristics of the equipment (spray drying tower) Liquid treatment capacity: 270-400 kg/H; evaporation water: 170-250 kg/H; finished product output: 100-150 kg/H, inlet air temperature ≥ 185-240 ℃, outlet air temperature ≤ 95 ℃ 2 Check and confirm the equipment Check whether the production water, electricity and steam are normal; check whether the voltage and current instrument signals are normal. Check the oil level of the intermediate tank agitator and add lubricating oil in time; if the agitating paddle falls off, tighten it in time; start the agitator and observe if the rotation is normal and if there is noise. Whether the pipe connections are installed with sealing materials and then connected to ensure that unheated air does not enter the drying chamber. Before startup and operation, the drying chamber, material pipeline, intermediate tank, material receiving barrel and other devices and parts in contact with materials shall be cleaned to meet the hygienic requirements of product quality. (Wash the tank and high-pressure pipe with 90 ℃ hot water before startup) Add lubricating oil to each lubricating point of the equipment as required. Check whether the transmission equipment operates flexibly and whether the steering is correct by inching. Close the observation window tightly, install the receiving barrel, and check whether the sealing conditions of all pipeline joints and valves are in good condition. Whether the process parameters and operating procedures are clear. Completely drain the steam condensate in the sub-cylinder and pipeline, and slowly open the steam valve. 3 Production operation 1) First start the blower, start the exhaust fan, start the electric heating compensation, open the atomizer to maintain the negative pressure of 100-200 Pa, drain the steam condensate in the sub-drum cylinder and steam pipe, slowly open the steam valve, preheat the drying tower for about 0.5-1 hour (start the material pump to feed after all the condensate in the air duct and tower is turned into steam and discharged). 2) After feeding, maintain the normal negative pressure at 50-150 Pa, adjust the feeding amount, control the tower temperature at 75-90 ℃ and the moisture at less than 5%; pay attention to the material level in the material tank at any time during drying. 3) Finished product packaging: after the seasoning (powder) product spray-dried and cooled to room temperature passes the standard inspection, it is bagged and weighed according to the quality requirements, and after the inspection certificate is put in, it is sealed and sealed for warehousing (the warehouse is required to maintain good ventilation effect and dryness). 4 Stop operation 1) After each batch of materials is dried, turn on the hot water switch of the intermediate tank to clean the atomizer, atomizing tray, material pipe, pump, etc. 2) The shutdown sequence is to shut down the steam feed pump, electric heater and atomizer (adjust the outlet air temperature to make the feeding speed between 15 and 20, reduce the inlet air temperature to 150 ℃, shut down the atomizer), close the air supply mechanism of the rapping and drying exhaust fan (reduce the inlet air temperature to 110 ℃), and turn off the power supply. 5 Cleaning system 1) In order to ensure the cleanliness of the drying tower body and its pipes and all parts in contact with the finished products, it is necessary to obtain first-class products and regular cleaning equipment. 2) When the product is replaced, or the equipment has been stopped for more than 24 hours without cleaning, it should be thoroughly cleaned. Dry cleaning: clean with brush, broom and vacuum cleaner. Wet cleaning: cleaning with hot water at 60-80 ℃. Acid washing: prepare nitric acid (HNO3) into 1-2% solution, heat to 95 ℃ for washing, and then wash with water. Alkali washing: prepare sodium hydroxide (NaOH) into 0.5-1% solution, heat to 60-80 ° C for washing, and then wash with water. 3) After wet cleaning and chemical washing, the equipment and components shall be installed and sterilized at high temperature for 15-30 minutes. 4) When cleaning the equipment, pay attention not to use chlorine and its compounds. 5) The air filter shall be cleaned according to the ambient conditions, that is, the dust content in the air. Generally, the air filter with high dust content shall be cleaned once every 3-6 weeks, and the air filter with low dust content shall be cleaned once every 6-8 weeks. Common fault repair method Wall sticking phenomenon (1) The feeding amount is too large to fully evaporate; (2) Insufficient heating of the drying chamber before the start of spraying; (3) At the beginning of spraying, the feeding flow is adjusted too large; (4) The feed liquid added is unstable. Repair method: Properly reduce the feeding amount; Properly increase the inlet and outlet temperature of the hot air; At the beginning of spraying, the flow should be small, gradually increased, and adjusted to the appropriate time; Check whether the pipeline is blocked, and adjust the solid content of the material to ensure the fluidity of the feed liquid. High moisture content Generally, the exhaust temperature is too low. Properly reduce the feed rate to increase the exhaust temperature. Low purity (1) Poor air filtration; (2) mix that accumulated pow into a finished product; (3) that purity of the raw material is not high; (4) Incomplete cleaning of equipment. Repair method: Check whether the filter material in the air filter is laid evenly and whether the filter has been used for a long time. If so, replace it immediately; Check the coke powder at the hot air inlet to overcome the vortex; Filter the feed liquid before spraying; clean the equipment again 。 The particles are too fine The solid content is too low or the feed rate is too small. Increase the solid content of the feed liquid, increase the feed rate, and increase the inlet air temperature. The phenomenon of powder loss The separation effect of the cyclone separator is poor. Repair method: (1) Check whether the cyclone separator is deformed due to knocking and collision; (2) improving the air tightness of the inlet and outlet of the cyclone separator; (3) Check whether the inner wall and discharge port are blocked by material accumulation. The rotating speed of the spray head is low The centrifugal spray head component has failed. Check the internal parts of the spray head. Low evaporation (1) the air volume of the whole system is reduced; (2) The inlet temperature of hot air is low; (3) The equipment has air leakage, and cold air enters the drying chamber. Repair method: (1) Check whether the rotating speed of the centrifuge is normal; (2) Check whether the position of centrifuge regulating valve is correct; (3) Check whether the air filter and air heater pipes are blocked; (4) Check whether the grid voltage is normal; (5) Check whether the electric heater works normally; (6) Check whether the connection of each component of the equipment is sealed. Nozzle vibration Cause of failure: (1) Improper cleaning and maintenance of the nozzle causes residual substances in the spray disc or bending and deformation of the main shaft; (2) The dynamic balance of centrifugal disc is not good. Repair method: (1) Check whether there are residual substances in the spray tray, and clean them in time if any; (2) If the spindle is found to be abnormal, replace it; (3) Readjust or replace the dynamic balance of the centrifugal disc. Operation precautions 1. First turn on the centrifugal fan, then turn on the heater, and check whether there is air leakage. If it is normal, it can be preheated. Because the hot air preheating determines the evaporation capacity of the drying equipment, the inlet air temperature should be increased as much as possible without affecting the quality of the dried materials. 2. During preheating, the atomizer is placed at the top of the drying chamber, and the drying chamber and the discharge port of the cyclone separator must be sealed to prevent cold air from entering the drying chamber and reducing the preheating efficiency. 3. When the inlet temperature of the drying chamber reaches the set temperature, start the centrifugal nozzle. When the spray head reaches the maximum speed, start the feed pump, add water and spray for 10 minutes, and then replace it with feed liquid. The feed amount should be from small to large, otherwise it will stick to the wall until the appropriate requirements are adjusted. The concentration of the feed liquid should be prepared according to the drying properties of the material to ensure that the finished product has good fluidity after drying. 4. The temperature and humidity of the dried finished product depend on the exhaust air temperature. During the operation, it is extremely important to keep the exhaust air temperature as a constant, which depends on the feeding amount. If the feeding amount is stable, the outlet temperature is relatively stable. If the solid content and flow rate of the feed liquid change, the outlet temperature will also change. 5. If the product temperature is too high, the feeding amount can be reduced to increase the outlet temperature, and vice versa if the product temperature is too low. For heat-sensitive materials with low product temperature, the feeding amount can be increased to reduce the exhaust temperature, but the product temperature will be increased accordingly. And 6, collecting the dried finished product. The pollinator at the lower part of the cyclone separator should be replaced before it is full. When replacing the pollinator, the butterfly valve on it must be closed first. 7. If the dried finished product is hygroscopic, the cyclone separator and its pipeline and the pollinator shall be wrapped with thermal insulation materials, so as to avoid moisture regain and moisture absorption of the dried finished product. Pay attention to our energy-saving internal reference public micro-signal: jnnc01 We insist on original depth or selected every article, welcome to pay attention and share. 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