The choice of drying equipment must be balanced with the supporting equipment, because the drying system consists of drying equipment and ancillary equipment. Whether the selection of ancillary equipment is appropriate is also a key link. Under normal circumstances, the drying system is mainly composed of ventilation equipment, heating equipment, main engine (drying equipment), gas-solid separation equipment, and feeding equipment. The rise in energy costs and regulations on pollution restrictions, working conditions and operational safety are directly related to the design and selection of industrial dryers. Some of the influences of these design factors (especially suspension dryer designs, such as spray, flash and fluidized bed dryers) have been fully discussed, and these must be taken into account during the selection phase of dryers of all types. factor. Sometimes, in the case of drying equipment that can be processed for different materials and different occasions, these factors must be taken into account at the design stage. For gases, the drying device can cause contamination due to the elimination of dust. In some places, even steam is not allowed. The general requirement is that the concentration of dust in the exhaust gas is less than 20~50mg/Nm3, and a high-efficiency dust collector must be installed. It is important to be suitable for drying coarse particles under certain conditions. On the other hand, the larger the particles, the longer the drying time. In the drying of the powder material, a cyclone, a bag filter or an electrostatic precipitator is usually used for dust accumulation and gas purification. In other forms, such as when drying a slurry, sheet, etc., the dust only occurs during convective drying of the material. In order to eliminate harmful gas pollution, people can resort to absorption, adsorption or incineration. * Dust removal equipment For gas, the drying device can cause pollution due to entrainment of dust. In some places, even steam is not allowed. Requires recommended system low cost, effective, easy to clean cyclone separator medium cost, high efficiency, high operating cost, bag filter, large amount of electrostatic precipitator product recovery, small particle size cyclone separator + wet dust collector, cyclone separator cyclone separator Widely used in convection drying systems, it is the main equipment for collecting products from gases. The cyclone separator has a simple structure and is easy to manufacture. As long as the design is reasonable and the manufacturing is proper, high separation efficiency can be obtained. For gases with high dust content, they can also be directly separated, and the pressure loss is relatively small. There are no moving parts, so they are durable. There are no other disadvantages other than the abrasive material causing wear or fine powder adhesion to the inner wall of the cyclone. Under normal circumstances, the cyclone separator can theoretically capture powders above 5 μm, and the separation efficiency can reach over 90%. However, in actual production operations, separation efficiency is often degraded due to poor manufacturing, improper installation or imperfect operation management. Generally only 50% to 80%, sometimes even lower. The cyclone separator, also called a centrifugal force separator, separates the fine powder from the gas by using the centrifugal force generated by the rotary motion of the fine powder gas stream. Strictly speaking, the movement of the airflow in the cyclone is quite complicated. Due to the agglomeration and dispersion of fine powder, the rebound effect of the wall on fine powder and the friction between particles, the separation mechanism is very complicated, and theoretical research has never stopped. After the fine gas-containing airflow enters the cyclone separator, it rotates along the inner wall and descends. As the radius of rotation decreases after reaching the conical portion, according to the law of conservation of momentum, the rotational speed gradually increases, and the particles in the airflow are subjected to greater centrifugal force. Since the separation speed by centrifugal force is several hundred times or even several thousand times larger than the sedimentation speed by gravity, the fine powder is separated from the swirling airflow and separated along the wall surface of the cyclone separator. When the airflow reaches the lower end of the conical portion, it begins to reverse, and gradually rises and rises in the center portion, and is discharged from the riser pipe after the Zui. The smaller the diameter of the cyclone separator, the larger the inlet velocity and the greater the number of rotations, the smaller the separation particle size. For the actual cyclone separator, due to the disturbance of the airflow and the friction of the wall surface, the uneven distribution of particles, the rebound effect of the particles and the wall surface, and the shape, the critical particle size of the separator is not so accurate, and it will be mixed in the separated materials. Part of the fine particles. The pressure drop of the cyclone is also an important performance indicator, generally proportional to the square of the gas inlet velocity. The separation efficiency of the cyclone separator is an important technical indicator, and the particles in the fine powder gas are usually composed of particles of different sizes. In the separation technique, the dispersion degree is usually used to reflect the particle size distribution, and the dispersion degree is the mass percentage of various particle fractions in the fine powder. Practice has shown that the separation efficiency is not only related to the structure and operating conditions of the separator, but also varies with the particle size distribution. Under the same operating conditions, the same equipment has different particle size distributions and different overall efficiencies. Therefore, in the separation technique, the particle size distribution is used to determine the separation efficiency of the separator, which is the classification efficiency. It shows the separation efficiency of the separator for a certain grade of powder. When the treatment gas volume is large, the size of a cyclone separator is too large, and the efficiency is declining. Several small-diameter cyclones can be used in parallel to form a cyclone separator group. Reducing the diameter of the cyclone will increase the centrifugal force and particle settling velocity, thus also increasing the efficiency of dust removal. Second, the bag filter dust collector bag filter (bag filter or bag filter) is often used as a gas-solid separation device after the separation of powdery products from the dry exhaust gas, is a line of defense after the interception of the powder in the tail gas. The bag filter is characterized by high collection efficiency. It can be said that in many gas-solid separation devices, its collection efficiency is beyond the reach of other equipment, especially when capturing particles below 20μm, the efficiency is 99. %the above. The bag filter is mainly composed of a filter bag, a bag holder and a casing, and the casing is composed of a box body and a clean air chamber, and the bag is installed on the partition plate between the box body and the clean air chamber. After the dust-containing gas enters the tank, the powder is inerted, diffused, adhered, and electrostatically attached to the surface of the filter cloth. The pores of the cleaning gas passing through the filter cloth are discharged from the clean air chamber, and the dust on the filter cloth is blown back or vibrated. The action breaks into the filter cloth and breaks into the hopper. (1) The working parameters of the bag filter are based on the working principle of the bag filter. The working resistance increases with the increase of the adhesion of the dust on the filter cloth within a certain range. The change of the resistance will cause the fluctuation of the ventilation of the system. The efficiency has a great influence. The working resistance is mainly composed of structural resistance, the resistance of the cleaning filter cloth and the resistance of the dust layer attached to the filter cloth. The resistance of the equipment is mainly determined by the latter two resistances. It is worth noting that the dry exhaust gas is a high dust and high humidity gas, paying special attention to the working temperature of the bag filter. The general operating temperature is higher than the dew point temperature by 10 to 20 ° C. Otherwise, once the condensation is formed, the dust adheres to the filter cloth a lot, and the resistance suddenly increases. In severe cases, the system may not work. (2) As mentioned in the filter cloth, the important factor determining the efficiency of the collection is the filter cloth. In a certain sense, it plays a decisive role. The correct selection of the filter cloth is the key to improve the collection efficiency. When selecting the filter cloth, it should be satisfied. the following conditions: ①the captured powder can be attached on the filter cloth forming the filter layer; ② select cloth gap should be larger than the diameter of the particles; ③ the powder adhering to the filter cloth to be easily peeled off; ④ acid-base pair the gas should have a certain chemical stability; ⑤ easily washed and difficult to shrink; ⑥ long-term treatment at a temperature of the medium is not damaged. (III) Structure of Bag Dust Collector At present, there are two types of bag dust collectors, such as electromagnetic pulse backflushing dust collector and mechanical rotary backflushing dust collector. The outer casing of the electromagnetic pulse backflushing dust collector is mostly square, and the cloth bag is divided into several rows, and the number of each row is equal. There is a back-blowing air pipe above the bag, and the back-blowing time is controlled by a solenoid valve, and each row of bags can be back-blowed in turn, so that the powder adhered outside the bag is detached from the bag in time. The outer casing of the mechanical rotary backflush is round. In order to improve the separation efficiency, it is often designed as a volute-like inlet. The large particles fall into the hopper along the wall of the cylinder under the action of centrifugal force, and the small particles are dispersed in the space of the filter chamber, so that the filter bag is retained and adhered to the outside of the filter cloth. The clean air chamber is provided with a swing arm, and the high-pressure clean air is introduced to periodically blow back into the bag, so that the dust adhering to the filter cloth falls off. Both types of dust collectors have their own advantages and disadvantages. The pulse dust collector can automatically control the backflushing cycle and the backflushing time, but the backflushing amount is small. If the filter bag is long, the backflushing effect at the end is not good. The mechanical rotary backflushing volume is large, and the backflushing effect is good, but it has a certain influence on the system, causing the system pressure to fluctuate. Since the air is introduced at room temperature, there is a tendency to dew condensation of the air in the filter bag during operation, and care should be taken during operation. Third, the air filter Some materials dry, such as food, medicine and biological products, require high air sanitation conditions for drying, to filter the air entering the system. The filter is usually placed at the front end of the system, and the air passing through the filter can enter the heating system. The material of the filter is generally oil-immersed filter layer, and the filter layer is formed of stainless steel wire to form a pile (also can be steel wool, copper velvet, nylon fiber, medium-porous foam), sprayed with light stator oil, or vacuum pump oil. A filter layer having a monomer thickness of about 5 to 12 cm each of about 50 × 50 cm is prepared, and other materials may be used. One or more layers may be stacked together as a filter layer according to requirements, and both sides of the filter layer are clamped and fixed by a steel mesh and then mounted on the filter casing. Fourth, the venturi dust collector Venturi dust collector (Wen's dust collector) is a kind of wet dust collector. The Venturi Dust Collector (Wen's Dust Collector) captures the dust particles in the gas and separates them into gas-liquid separation to achieve dust removal. Venturi dust collectors can be divided into central spray, peripheral radial spray, liquid membrane introduction, and airflow energy introduction according to the liquid introduction method. The dust collection and gas-liquid separation in the gas are all completed by one device, which can have satisfactory effects. The Venturi dust collector mainly consists of a shrink tube, a throat diameter, a diffusion section, a cyclone, a fluid guide, a baffle, and a separation chamber. The dust-laden gas enters the dust collector from below, and the velocity reaches a large value at the throat. The trapping water is tangentially entered into the swirl chamber by the action of the pump, and a loop is formed at the throat to communicate with the swirl chamber. The water rotates in the swirl chamber and has a pressure that forms a rotating liquid film after entering the throat through the loop. The liquid film is rapidly atomized by the impact of high-speed airflow, and the atomized droplets increase the contact area with the gas after atomization. Due to the speed difference between the two, the dust in the gas is trapped by the mist and separated from the gas. The gas entrains the droplets upwards and moves from the vertical motion to the rotary motion after the guide vanes. The centrifugal force generated causes the droplets to be adhered to the water film and separated from the gas after being deflected toward the wall, thereby enhancing the trapping effect. The upper diffusion section lowers the gas velocity and acts as a sedimentation, thereby reducing the amount of entrainment of the droplets, and the purified gas is discharged from the top. 5. There are one or two orifice plates in the tank type water film dust collector, and there are nozzles above each board. The dust-containing gas enters the dust collector from the air inlet. When the baffle suddenly forms a 180° turn, the airflow generates a large centrifugal force. The dust moves to the outside of the airflow and is adsorbed after contact with the water surface. Form a * level separation. When it reaches the bottom of the orifice plate, it contacts the water droplets falling down the orifice plate, and some of the dust is adsorbed by the water droplets. The water droplets sprayed from the nozzle fall into the orifice plate and are subjected to the ascending airflow passing under the orifice plate, and a foam layer of 60 to 80 mm is produced on the orifice plate. When the airflow passes through the orifice, the area of ​​contact between the dust and the water is large, and the collection rate is high. The airflow passing through the orifice plate necessarily entrains some of the droplets, and when it rises to the gap of the deflector of the centrifugal demister, the airflow changes from a linear motion to a spiral motion. The strong rotating motion causes the entrained mist to drip onto the wall to form a water film and flow back into the water tank along the wall, and the purified gas is discharged from the air outlet. 6. The box type scrubber box washer is a horizontal packing layer scrubber. The packing layer is composed of a multi-layer net. The thickness depends on the process conditions, and generally consists of two to three such packing layers. There is a spray pipe above the packing layer to make the mesh layer wet. When the dust-containing gas passes through the packing layer, the gas-liquid contact surface area is increased, and the collected dust flows back to the water tank together with the water, and the trapping water can be recycled. To ensure that the filler is completely rinsed with water, there is generally an angle of inclination. The amount of water used in such a scrubber is relatively small, generally 0.15 to 0.5 L/m3, and the resistance of the device varies depending on the thickness of the filler layer. When the concentration of the dust-containing gas at the inlet is 10 to 12 g/m3, the dust efficiency of capturing the particle size of 2 μm can reach 90%. Second, the heat source is inseparable from the heat source, but because the material to be dried is more complicated, it has different requirements for the heat source and the heat exchange equipment. Once the material to be dried is determined, the choice of the heat source is based. The type of heat source of the dryer and the form of the heat exchange equipment largely determine the operating cost and production cost of the equipment, so the technical and economic indicators of the equipment depend not only on the rational design and normal operation of the drying equipment itself, but also to a large extent. It is also closely related to the selected heat source and the way of utilization. First, the choice of heat source Dry heat source Commonly used fuels are solid fuels, liquid fuels, gaseous fuels, heat carriers and electrical energy. Specifically, there are mainly various combustion products (coal, natural gas, liquefied petroleum gas, combustible chemical gas) and air combustion products, water vapor, hot water, electric energy, exhaust gas with a certain amount of heat, waste liquid, waste oil residue and the like. If the hot air for drying requires indirect heat exchange, the heat exchange medium also has heat transfer oil (such as raw oil). The heat source selection should be considered in the following aspects: 1 Meet the requirements of product quality. The heating temperature and the cleanliness of the heat source have a great influence on the product quality; 2 Meet the environmental protection requirements. Some burning heat sources will produce odor or smoke during the combustion process, and will cause pollution after being discharged to the atmosphere. Such heat sources should be used with caution, and if necessary, environmental treatment is also required; 3 Economical and easy to obtain. The heat source to be used should be suitable for local conditions, considering the cost of various heat sources, and easy to obtain; 4 safe and reliable. This is more important for direct-fired heat sources. Some of the materials to be flammable are flammable, explosive or oxidizable. For the treatment of such materials, the heat source for indirect heat exchange is used. For direct combustion, special flame retardant or explosion-proof measures are required. 5 Easy to operate. The selected heat source is as easy to operate and automatic as possible to ensure stable product quality. Second, the type of heat source (a) steam steam is a clean, safe and inexpensive heat source, mainly used in indirect heat exchange equipment. After the heat transfer device conducts heat transfer, the sensible heat is released and discharged into condensed water. When the steam pressure is high, the temperature of the air exchanged is high, and the drying process conditions determine the required pressure and amount of steam. If the plant has steam of 0.6 to 0.8 MPa, the drying medium (air, nitrogen or other gas) can be heated to 150-160 ° C through a heat exchanger. Theoretically, the temperature of the drying medium leaving the heat exchanger is approximately 5 to 7 ° C below the steam temperature. (2) Hot water If the temperature of the hot water reaches 90 to 130 ° C, it can be considered to have a certain use value. It can be mainly used to operate some dry materials with lower temperature, such as drying with solvent or as an auxiliary heat source for preheating. The heat transfer can bring the drying medium to a temperature of 50-90 °C. (3) Electrical energy is mainly used in small dryers or where high control standards are required. The electrical energy is converted into heat by an electric heating tube to heat the drying medium. Electrical energy is a high-grade energy source without any pollution problems. It can be used as a heat source alone or as a secondary heating device together with other heat exchange equipment. However, when using the electric heater, pay attention to the outlet temperature of the hot air. Do not exceed 350 °C. Otherwise, the electric heating tube may be burnt out, and the junction of the electric wire is also easily blown. In addition, the fan must be turned off when the outlet temperature of the electric heater is reduced to below 100 °C during shutdown to avoid burning the device. (4) Coal coal is a relatively cheap fuel. The flue gas produced by coal combustion can be heated by heat exchange method, or it can be directly dried by flue gas after dust removal. However, materials or fine chemical products that require strict impurity content generally do not adopt direct coal combustion. Coal flue gas can reach very high temperatures and can be used to reduce energy consumption in the drying of certain building materials. (5) Fuel oil can be directly burned to produce flue gas and indirect heat exchange. The fuel burner should use a special burner, and different fuels should be equipped with different burners. In general, the burner structure for low-viscosity fuel is simpler and less expensive. The viscosity of the fuel burner structure is more complicated and more expensive. (6) Combustible gas, natural gas, liquefied gas and other combustible chemical gases can be used as drying heat sources. These gases have a relatively high calorific value. Their main advantage is that the products of combustion can be directly used as drying medium. It can reach very high temperatures (usually up to 300-800 ° C). When the gas is burned, it is usually necessary to disperse the gas by a special burner to make it burn more completely. Regarding the form of the burner, most of the low pressure burners of various structures are used in the chemical and pharmaceutical industries. Although the high-pressure burner has a high burning speed and a high temperature, it requires a high wind pressure, is noisy during use, and is prone to tempering. Most of the combustible gas contains a certain amount of sulfur. For the case where the dried material is not allowed to contact sulfur, the combustible gas can be desulfurized before combustion. In industrial production, iron oxide, zinc oxide and activated carbon can reduce the sulfur content in the gas to less than 1 ppm. For some natural gas with high sulfur content, it can be desulfurized with activated carbon and then treated with zinc oxide. This purification method combining physical adsorption and chemical reaction adsorption has been proved to be effective by industrial practice. (7) Heat transfer oil Organic high temperature heat carrier plus combustion furnace heat exchange is a common heat exchange equipment for drying. This heat exchanger called heat transfer oil furnace has advantages that other industrial furnaces cannot match. When the production process requires high temperature heating at 180-250 ° C, if steam heat exchange is used, the saturated steam pressure needs 4 Mpa, and the working temperature can only reach 250 ° C. However, the use of a heat transfer oil furnace, the saturated steam pressure can reach 280 °C when less than 0.7MPa, so the heat transfer oil furnace heat transfer has the characteristics of low pressure and high temperature. The heat transfer medium that transfers heat from the heater to the dryer in an indirect manner is called a heat carrier. The industrial heat carrier can be divided into two types: an organic heat carrier and an inorganic heat carrier. The organic heat carrier is commonly called a heat transfer oil. As early as 1931, the American Daosheng Chemical Company researched and created a heat carrier, named "Daosheng Oil." Daosheng oil is usually a mixture of biphenyl and diphenyl ether, such as 26.5% biphenyl and 73.5% diphenyl ether. This group of Daosheng oil has high temperature and good thermal stability. However, due to its high freezing point, it must be operated under pressure above 250 °C, and it has strong permeability at high temperature, has special unpleasant odor and toxicity, and pollutes the environment. Therefore, new high-temperature heat carriers are being developed at home and abroad to replace Daosheng. oil. At present, there are many manufacturers of heat transfer oil in China. The selection is not difficult, but generally only heat transfer oil below 300 °C is available. The research on China's heat carrier started late, and research work began in the late 1970s, but progress has been rapid. Some products have caught up with the level of similar foreign products. Domestic organic heat-conducting bodies can be divided into two categories according to the production raw materials. One type is based on petroleum products. This type is called heat-conducting oil. Because the specific heat of oil is large, the appropriate fraction can be selected and the resources are compared. Adequate, generally selected from naphthenic or aromatic mixed materials, added anti-oxidation heat-resistant additives. The other type is made by using organic materials as raw materials. Third, the air heat exchanger (a) heat pipe heat exchanger heat pipe heat exchanger is a kind of heat exchange device that uses the working material enclosed in the pipe to repeatedly carry out physical phase change or chemical reaction to transfer heat. Heat pipe technology is a new technology. Since the advent of the heat pipe in 1964, it has only been more than 30 years old. Because of its many advantages in recovering waste heat and preheating air, heat pipe technology has developed rapidly, with many types and functions. According to the working principle of the heat pipe, according to the working mode of the working fluid, it can be divided into a physical heat pipe and a chemical heat pipe. The physical heat pipe transfers heat by physical phase change (fluidization, condensation) of the working fluid. Chemical heat pipes use the combination of working substances to transfer heat. In the spray drying system, the use of a heat exchanger to indirectly heat the air has achieved good economic benefits. The working fluid of the heat pipe can be selected according to the needs of different liquids, but each working fluid has its proper operating temperature range. (2) Coal-fired hot blast stoves Coal-fired hot air furnaces mostly heat air by indirect heat exchange. In the indirect heat exchange process, there are generally two cases. One case is that there is a ventilation pipe in the furnace, a cold air pipe layer, and a flue gas gas shell layer. The heat generated by the combustion of the coal radiates to the outer wall of the tube, and the heat is transmitted to the inner tube through the wall of the tube, and then heated by the cold air of the inner tube. The inlet of the furnace is cold air, and after heating, the hot air that is heated to a certain temperature is cleaned from the other port. The other is a coal-fired heat-conducting oil furnace. The heat-conducting oil is heated and then flows to another heat exchanger (such as a fin heat exchanger) to exchange heat with cold air. The characteristic of indirect heat exchange is that the obtained hot gas has high cleanliness, and the air has no humidity change during the heat exchange process, and the moisture content of the cold air is still maintained. The structure of the coal-fired hot air furnace is relatively simple, and there are many ways to add coal. Different heating methods are adopted according to the process requirements or the heat exchange amount. Due to the direct radiation of the flame and the heat exchange tube, there is a chemical substance with strong corrosiveness such as sulfur in the gas, which has certain requirements on the material of the tube. The hot air furnace has a high temperature furnace and a low temperature furnace. When the outlet hot air temperature is required to be above 300 ° C, the heat exchange tube should be made of a material resistant to high temperature and corrosion. In addition, the running path of the air inside the pipe should also avoid the local high temperature of the heat exchange tube as much as possible, otherwise it will affect the service life. The flue gas of the hot air furnace conducts heat transfer and radiation heat transfer to the cold air in the pipe layer through the pipe wall. The cold air runs in the furnace for four strokes, and three strokes exchange heat with the high temperature flue gas, of which two The stroke can be exchanged with the high-temperature gas on both sides at the same time, so the heat exchange efficiency is high and the discharge temperature of the flue gas is very low. (III) Steam heat exchanger The steam heat exchanger is an indirect heat exchange device and is composed of a plurality of heat dissipation tubes. In the heat exchange, a set of work can be used as needed, or multiple sets can be used in series. The tube is made of copper or steel. In order to increase the heat transfer effect, the tube is wrapped around the fins, and the fins have good contact with the tube. When steam is used as the heat medium, steam is passed through the tube, and air is taken between the outer fins of the tube. Due to the different materials of the fin heat exchanger and the winding form of the fins, there are many specifications and have been serialized. The heat exchanger is suitable for both steam and hot water systems, as a heat exchanger for heating air, mainly for drying systems and air conditioning systems. If steam is used as the heat medium, the working pressure of steam is 0.03~0.8MPa, which is mainly composed of three rows of staggered spiral finned tubes flowing along the air, and the finned tubes are wound with 15×0.5mm with φ21×2mm seamless steel tubes. The wrinkled steel strip is formed in a spiral shape. According to practical experience, when the steam temperature is between 130 and 160 ° C, the evaporation chamber needs about 2.0 to 2.5 m 2 of heat exchange area per evaporation of steam, and the steam consumption is about 1.8 to 2.5 kg. At this time, the temperature of the output hot air is about 6 to 10 ° C lower than the heater inlet steam temperature. Steam heat exchanger connection method: Steam heat exchangers are generally connected in groups, and the installation positions are mainly vertical series and horizontal series. The vertical series connection is that the windward side of the heat exchanger is parallel to the horizontal plane, the vertical horizontal plane of the air passes through the heat exchanger, and the horizontal series is the air parallel plane passing through the heat exchanger, and the heat exchanger group and the group are connected by bolts, which is convenient for maintenance. Horizontal installation is recommended. According to the method of steam entering the heater, it can be divided into three methods: series, parallel, and series-series. These methods have different heat exchange effects. The series connection method is that the steam passes through the heat exchanger one by one, and the energy can be fully utilized, and the condensed water discharge temperature is very low. However, it is necessary to increase the heat exchange area, the system temperature rises slowly, and sometimes it takes several hours to reach the specified temperature. Parallel is steam passing through each group of heat exchangers at the same time, and simultaneously discharged, so that the steam heat exchanger maintains a large temperature difference with the air. The heat transfer rate is high and the heating rate is fast, but the discharge temperature of the condensed water is high and the energy utilization rate is low. Combining the above two methods, it is more reasonable to adopt the parallel connection method. The steam first passes through several sets of heat exchangers in parallel, and passes through the low temperature steam of the heat exchanger and then passes through the latter groups in series, which overcomes the shortcomings of the first two methods. After testing, if three sets of heat exchangers are used, the intake method is parallel to the first two groups, and then connected in series with the latter group. (4) Electric heater The electric heater is a heating device that converts electrical energy into heat energy and radiates heat to the air. The electric heater is composed of a plurality of tubular electric heating elements. The tubular electric heating element is formed by placing a resistance wire in a metal tube and closely filling the void portion with crystalline magnesium oxide powder having good heat resistance, thermal conductivity and insulation, and then being processed by other processes. The utility model has the advantages of simple structure, high mechanical strength, high thermal efficiency, safety and reliability, simple installation and easy realization of temperature control automation. It is used to heat no relative humidity of more than 95%, no explosive, no corrosive gas. The working voltage should not be greater than 1.1 times the rated value, and the heated air temperature should not exceed 300 °C. It can be used independently or as a second-stage heating device, often combined with a steam heat exchanger. If the hot air inlet temperature of the dryer requires 200 ° C, the general steam heat exchange is difficult to meet the requirements. At this time, the cold air can be heated to a temperature through the steam heat exchanger and then enter the electric heater to continue to heat up to reach the required temperature. The electric heating operation is convenient and easy to realize automation, but the electricity is high-grade energy, and the operation cost is high, and it is not suitable for use in a material drying system with low added value. The above discussion is to provide some considerations for the selection of the dryer during the selection of the drying unit. It is not possible to select a dryer that is ideal in all aspects. However, by reading this article during the design or application of the dryer, you will definitely improve your design, selection and use.
Indications
Prophylaxis and treatment of worminfections in calves, cattle, goats and sheep like Fasciola, Hypoderma and Oestrus spp.
Contra indications
Administration to lactating animals.
Side effects
Overdoses can cause colic, coughing, excessive salivation, excitation, hyperpnoea, lachrymation, spasms, sweating and vomiting.
Swine: Ascaris suum, Hyostrongylus rubidus, Metastrongylus elongatus, Oesophagostomum spp. and Trichuris suis.
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Hebei Kexing Pharmaceutical Co., Ltd. , https://www.kexingpharma.com