1. Microwave heating principle Electronic vacuum components or semiconductor devices pass high-voltage direct current or 50Hz alternating current. The magnetron anode needs 7.2kV direct current. It is converted by three-phase mains through high-voltage transformer and high-voltage rectifier bridge. The frequency is between 300MHz and 300GHz. Electromagnetic waves. Microwave equipment is controlled by digital circuits, analog circuits, and programmable controllers. Polar molecules (such as water molecules) in the material are polarized under the action of microwaves, causing high-speed friction between the molecules to generate heat. After the material absorbs microwave energy, it is internally converted into heat energy, and the energy conversion process has little loss. The microwave penetration force is strong, and the material generates heat at the same time inside and outside after the microwave radiation, and the radiation stops after the radiation disappears. It has the advantages of uniform heating, high efficiency and fastness.
Second, the characteristics of microwave drying equipment The company has invested in six tunnel microwave dryers with an output of 30kW, which is used for the drying of nine Chinese medicines. The equipment is a WYH-30.2 microwave pill dryer produced by the Microwave Energy Application Research Institute of Chengdu Guoguang Electric Corporation. The equipment adopts YJ-1600 (output power 5kW, working frequency 2450-2470MHz) continuous wave magnetron as microwave generator, electrical control system is composed of digital, analog circuit and programmable controller, high power circulator, reflection The power absorption load and the electric three-pin adapter form a complete microwave output system. It has high output stability and programmable automatic output power regulation.
The equipment consists of 6 microwave sources and 3 cabinet sections. The microwave source consists of a magnetron and a microwave output system. The microwave generated by the magnetron is transmitted to the feeder at the top of the dry casing through the output system, and the feeder radiates the microwave evenly into the casing. The material is fed into the tunnel type radiation box through a conveyor belt and dried by microwave radiation. The microwave source power can be adjusted steplessly, and the conveyor speed can be continuously adjusted according to the moisture of different materials.
Advantages of Microwave Drying Technology Most traditional heating systems, such as hot air circulating furnaces, take a considerable amount of time to increase the furnace temperature. However, microwave dryers can adjust the microwave power to less than 1 s. The required value so that the material gets the right temperature. The traditional Chinese medicine pill using microwave drying is heated uniformly and fully dried, and a batch of nine doses is dried from the original 7h to about 5h. After drying, the pellet has good dispersibility, the pass rate reaches 100% (formerly 65%), and the sterilization effect is improved. The tunnel structure makes production into continuous production with continuous flow, high degree of automation and high production efficiency, and reduces labor intensity. It solves the drawbacks of large heating, drying equipment, high environmental temperature and environmental pollution.
Fourth, the device use precautions Microwave can only be absorbed by polar molecules, encountering metal objects will be reflected like visible light encountered in the mirror, and ordinary metal under the action of microwave surface vortex, and cause sparking. Therefore, stainless steel having a small surface resistance is often used as the microwave oven body. In order to avoid equipment damage caused by accidental ignition, it is clearly stated in the operating procedures for microwave drying equipment that metal objects in the furnace body must be removed before starting the machine. The material put into the conveyor belt can not exceed the carrying capacity of the conveyor belt, and the excessive material is easily dropped into the furnace cavity. When the water is evaporated, the material is burned due to overheating. When this happens, immediately turn off the microwave source, then open the oven door and extinguish the fire with a wet towel and thoroughly clean the residue.
Microwave is an invisible electromagnetic wave, and large doses of microwaves can cause harm to the human body. Although microwave drying equipment has adopted a variety of shielding measures, in the production process, the door screen shielding net and the outlet microwave suppressor will inevitably be damaged. The furnace body and the furnace door will be deformed after being heated for a long time, and the sealing degree is weakened. It will cause microwave leakage. The small microwave leak detector is equipped in the production team, which is an important guarantee for the safe operation of microwave equipment.
V. Maintenance and maintenance of equipment 1. Do a good job in cleaning and maintaining the furnace body. The powder that peels off the surface during the drying process of the pellet consumes a certain amount of microwave energy in the furnace body and reduces the microwave use efficiency. In order to ensure the safety of the equipment, it is necessary to improve the regular cleaning system in the furnace.
2. Regularly check the microwave transmission system. The microwave transmission system is a channel for transmitting microwaves from the generator to the furnace body. The outlet of the microwave energy feeder is covered by a plastic plate, and the plastic plate is deformed after being heated for a long time, which affects the sealing between the furnace body and the plastic plate. Part of the water vapor enters the microwave transmission system from the feeder, and condenses in the transmission system to adhere to the inner surface of the excitation chamber, the electric three-pin adapter, the high-power circulator, and the waveguide, and the microwave is partially condensed when passing through the transmission system. The water is absorbed, causing losses to reduce the output power. Moisture easily oxidizes the surface of the microwave transmission device made of oxygen-free copper to produce patina, which makes the surface of the device rough. The microwave encounters a rough surface and is easy to fire. In severe cases, the transmitting antenna of the magnetron is burned, resulting in magnetic Control is scrapped.
3. Check the cooling system regularly. The heat generated by the operation of the microwave component and the reflected microwave of the high power circulator are absorbed by the cooling system. Appropriate cooling water pressure and flow rate are important guarantees for the normal operation of the equipment. Regularly check the water pressure, flush the scale inside the cooling pipe, ensure the cooling water pressure loss protection device is effective and the cooling water is stable and smooth. The cooling system connects the devices that need to be cooled by rubber hoses, and is arranged vertically and horizontally in the microwave source. The microwave source is covered with various circuit boards, high-voltage transformers, rectifying components and electrical components. As long as the cooling pipe is slightly leaked, the electrical circuit will be short-circuited. Causing an accident. Before the equipment is powered on, first turn on the cooling system, check the system sealing, and confirm that the power can be started. The fittings with cooling must be hydrostatically tested before use to confirm that they are leak-free.
4. Regularly check the shielding performance of the equipment. The microwave dryer is equipped with a suppressor at the entrance and exit. The furnace door observation window is provided with a copper mesh, and the door frame is installed with a purlin seal. These shielding measures can effectively eliminate microwave leakage under normal conditions. However, microwave is an invisible electromagnetic wave. People can't sense the existence of microwave by sensory organs. Only by means of instrument detection can we understand the intensity and source of microwave. Regular screening of microwave equipment is an important measure to ensure safe use. Without affecting the operation of the equipment, a shielding net is added around the equipment to provide effective protection to the operator before the microwave leaks and is not discovered.
Article link: China Chemical Instrument Network / Tech_news/detail/52782
Second, the characteristics of microwave drying equipment The company has invested in six tunnel microwave dryers with an output of 30kW, which is used for the drying of nine Chinese medicines. The equipment is a WYH-30.2 microwave pill dryer produced by the Microwave Energy Application Research Institute of Chengdu Guoguang Electric Corporation. The equipment adopts YJ-1600 (output power 5kW, working frequency 2450-2470MHz) continuous wave magnetron as microwave generator, electrical control system is composed of digital, analog circuit and programmable controller, high power circulator, reflection The power absorption load and the electric three-pin adapter form a complete microwave output system. It has high output stability and programmable automatic output power regulation.
The equipment consists of 6 microwave sources and 3 cabinet sections. The microwave source consists of a magnetron and a microwave output system. The microwave generated by the magnetron is transmitted to the feeder at the top of the dry casing through the output system, and the feeder radiates the microwave evenly into the casing. The material is fed into the tunnel type radiation box through a conveyor belt and dried by microwave radiation. The microwave source power can be adjusted steplessly, and the conveyor speed can be continuously adjusted according to the moisture of different materials.
Advantages of Microwave Drying Technology Most traditional heating systems, such as hot air circulating furnaces, take a considerable amount of time to increase the furnace temperature. However, microwave dryers can adjust the microwave power to less than 1 s. The required value so that the material gets the right temperature. The traditional Chinese medicine pill using microwave drying is heated uniformly and fully dried, and a batch of nine doses is dried from the original 7h to about 5h. After drying, the pellet has good dispersibility, the pass rate reaches 100% (formerly 65%), and the sterilization effect is improved. The tunnel structure makes production into continuous production with continuous flow, high degree of automation and high production efficiency, and reduces labor intensity. It solves the drawbacks of large heating, drying equipment, high environmental temperature and environmental pollution.
Fourth, the device use precautions Microwave can only be absorbed by polar molecules, encountering metal objects will be reflected like visible light encountered in the mirror, and ordinary metal under the action of microwave surface vortex, and cause sparking. Therefore, stainless steel having a small surface resistance is often used as the microwave oven body. In order to avoid equipment damage caused by accidental ignition, it is clearly stated in the operating procedures for microwave drying equipment that metal objects in the furnace body must be removed before starting the machine. The material put into the conveyor belt can not exceed the carrying capacity of the conveyor belt, and the excessive material is easily dropped into the furnace cavity. When the water is evaporated, the material is burned due to overheating. When this happens, immediately turn off the microwave source, then open the oven door and extinguish the fire with a wet towel and thoroughly clean the residue.
Microwave is an invisible electromagnetic wave, and large doses of microwaves can cause harm to the human body. Although microwave drying equipment has adopted a variety of shielding measures, in the production process, the door screen shielding net and the outlet microwave suppressor will inevitably be damaged. The furnace body and the furnace door will be deformed after being heated for a long time, and the sealing degree is weakened. It will cause microwave leakage. The small microwave leak detector is equipped in the production team, which is an important guarantee for the safe operation of microwave equipment.
V. Maintenance and maintenance of equipment 1. Do a good job in cleaning and maintaining the furnace body. The powder that peels off the surface during the drying process of the pellet consumes a certain amount of microwave energy in the furnace body and reduces the microwave use efficiency. In order to ensure the safety of the equipment, it is necessary to improve the regular cleaning system in the furnace.
2. Regularly check the microwave transmission system. The microwave transmission system is a channel for transmitting microwaves from the generator to the furnace body. The outlet of the microwave energy feeder is covered by a plastic plate, and the plastic plate is deformed after being heated for a long time, which affects the sealing between the furnace body and the plastic plate. Part of the water vapor enters the microwave transmission system from the feeder, and condenses in the transmission system to adhere to the inner surface of the excitation chamber, the electric three-pin adapter, the high-power circulator, and the waveguide, and the microwave is partially condensed when passing through the transmission system. The water is absorbed, causing losses to reduce the output power. Moisture easily oxidizes the surface of the microwave transmission device made of oxygen-free copper to produce patina, which makes the surface of the device rough. The microwave encounters a rough surface and is easy to fire. In severe cases, the transmitting antenna of the magnetron is burned, resulting in magnetic Control is scrapped.
3. Check the cooling system regularly. The heat generated by the operation of the microwave component and the reflected microwave of the high power circulator are absorbed by the cooling system. Appropriate cooling water pressure and flow rate are important guarantees for the normal operation of the equipment. Regularly check the water pressure, flush the scale inside the cooling pipe, ensure the cooling water pressure loss protection device is effective and the cooling water is stable and smooth. The cooling system connects the devices that need to be cooled by rubber hoses, and is arranged vertically and horizontally in the microwave source. The microwave source is covered with various circuit boards, high-voltage transformers, rectifying components and electrical components. As long as the cooling pipe is slightly leaked, the electrical circuit will be short-circuited. Causing an accident. Before the equipment is powered on, first turn on the cooling system, check the system sealing, and confirm that the power can be started. The fittings with cooling must be hydrostatically tested before use to confirm that they are leak-free.
4. Regularly check the shielding performance of the equipment. The microwave dryer is equipped with a suppressor at the entrance and exit. The furnace door observation window is provided with a copper mesh, and the door frame is installed with a purlin seal. These shielding measures can effectively eliminate microwave leakage under normal conditions. However, microwave is an invisible electromagnetic wave. People can't sense the existence of microwave by sensory organs. Only by means of instrument detection can we understand the intensity and source of microwave. Regular screening of microwave equipment is an important measure to ensure safe use. Without affecting the operation of the equipment, a shielding net is added around the equipment to provide effective protection to the operator before the microwave leaks and is not discovered.
Article link: China Chemical Instrument Network / Tech_news/detail/52782
Double Convex Cylindrical Lens
Cylinder Lenses are offered in both plano-concave and plano-convex configurations, they are typically used to focus incoming light to a line, or to change the aspect ratio of an image. Cylinder Lenses are available with positive or negative focal lengths, they are used for the optics, lasers, medical science, electronics, tele-communication and others.
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