Solve the problem of low heat transfer：
Due to the high temperature drying of some products in the chemical, pharmaceutical, food and other industries, the product will be denatured, the organism loses its activity, etc., the operating conditions during the drying operation must be changed, so that the temperature rise of the material is not high and the water is removed, so vacuum drying is used. In some petrochemical drying operations, because the volatile medium is organic vapor, the danger of mixing with air and burning and explosion, in order to ensure safety, is not air into the drying system and vacuum drying.
Most of the drying techniques currently used are batch drying, such as vacuum kneading dryers, double cone dryers, vacuum ovens, and the like. The problems are small processing volume, low drying efficiency, high energy consumption, high labor intensity, poor working conditions and poor working environment. When the material to be dried is in the form of a paste, the viscosity of the material may change with the change of the moisture content in the drying process, and an undesired phenomenon such as sticking and winding may occur in a certain moisture content stage. The power is increased, the heat transfer efficiency is lowered, and the drying operation is smoothly performed. For liquid drying due to sticking walls, low heat transfer efficiency, etc., it is almost impossible to use current vacuum drying equipment. Vacuum drying is currently not possible for continuous operation, and in particular, an important reason is the problem of sealing the inlet and outlet at the time of continuous feeding and continuous discharging.
Despite the above difficulties, the benefits of vacuum drying are very obvious. The company is currently conducting research on the technical scheme of continuous vacuum drying equipment, in order to develop a continuous vacuum drying device with satisfactory results and mature technology.
1. Successfully developed a hot-shaft agitating continuous vacuum drying device to solve the problem that the material needs low-temperature vacuum drying and a large amount of treatment, and also solves the safety problem that the volatilized medium is organic steam and the treatment amount is large;
2. Two horizontal parallel hollow shafts are arranged in the drying machine cylinder, and W-shaped partitions are arranged below the two horizontal parallel hollow shafts; 2-3 sets of bag filters are arranged at one end of the barrel body, and the other end is provided with a connection at the top of the barrel body a hopper of the rotary lock valve, a discharge port is arranged on both sides of the cylinder body, and a dry material buffer tank is connected under each discharge port; an automatic control valve is respectively arranged at each inlet and outlet of the buffer tank;
3. The cylinder of the dryer is a closed circular cylinder, and two outlets are arranged on the side, and the two outlets are arranged on the same side or on opposite sides;
4. The outer wall of each hollow shaft is provided with a plurality of hollow fan-shaped blades, each of which is connected with the hollow shaft, and the heat source disposed in the hollow shaft is steam, molten salt or heat-conducting oil;
5. Overall, through the combination of the feeding system, the discharging system, the vacuum dedusting system and the main body of the dryer, and the automatic control system, it becomes a continuous vacuum drying device, which realizes continuous vacuum drying of materials and treatment. Large amount of purpose;
6. During operation, the hot shaft is heated and dried by agitation, the material is added into the drying cylinder, the heat source steam or heat transfer oil is introduced into the hollow shaft, and the fan-shaped hollow blades on the hollow shaft are introduced into the hollow shaft, and the hot wall and the drying cylinder are inside. The material is in full contact with heat transfer. The vaporized medium in the material is heated and the vaporized phase changes to steam. Under different vacuum conditions, the vaporization phase transition temperature is different. Different vacuum conditions can be determined according to the specific material. With the rotation of the hollow shaft and the fan shape The stirring action of the blade, the material in the drying cylinder continuously moves, so that the heat exchange surfaces of the hollow shaft and the fan-shaped blade and the material are continuously updated, thereby improving the heat exchange efficiency between the hollow shaft and the fan-shaped blade and the material, thereby improving the drying barrel The rate of vaporization phase change of the volatile medium in the material in the body. The continuous drying of the materials added in the drying cylinder is realized;
7. The vacuum state of the drying process is maintained, and continuous vacuum drying is realized, that is, the materials to be dried are continuously added to the dryer, and the dry materials in the dryer are continuously discharged, and the volatile medium in the dryer is continuously heated and vaporized. The phase changes to steam and the vacuum source of the process system is continuously pumped out. The purpose is achieved by realizing the dynamic sealing of the feed port of the material to be dried, the dynamic sealing of the discharge port of the dry material, and the extraction of the vapor of the volatilized medium;
8. Dynamic sealing process of the feed port of the dry material: a hopper with a rotary lock valve is installed above the cylinder of the dryer, and the dry material is installed in the hopper, and is continuously added to the dryer through the rotary lock valve. The dry material in the hopper has a certain sealing effect on the outside air, and the rotary lock valve also seals the outside air. The sealing form of the feed port is a rotary lock valve and a material double composite seal. Continuous feeding, insulation air entering the dryer from the inlet;
9. The dynamic sealing process of the dry material discharge port: two dry material discharge ports are opened on the side of the dryer cylinder, which can be opened on the left and right sides of the dryer cylinder, or can be opened in the dryer cylinder On the same side, the left side buffer tank and the right side buffer tank are respectively connected under the left and right two dry material discharge ports. The left side of the buffer tank is equipped with a left inlet valve, the lower side is equipped with a left outlet valve, the right side of the buffer tank is equipped with a right inlet valve, and the lower side is equipped with a right outlet valve; four automatic control valves are executed by an automatic control system A certain logical relationship, after the left inlet valve and the right outlet valve are closed, the left outlet valve and the right inlet valve are opened, at this time, the left buffer tank is discharged, and the right buffer tank is fed. After the right inlet valve and the left outlet valve are closed, the right outlet valve and the left inlet valve are opened, at which time the right buffer tank is discharged, and the left buffer tank is fed; in any state, the dryer The two discharge ports of the dry material have a discharge state, and the continuous discharge of the dry material is realized. In any state, the two discharge openings of the dryer are separated from the outside air. The continuous discharge of the dryer is realized, and the vacuum state in the dryer is maintained;
10. Continuous discharge process of volatile medium vapor: During the drying process of the dryer, the volatile medium contained in the material continuously generates steam and is entrained with a certain amount of dust. In order to maintain the vacuum state in the dryer, the volatile medium vapor must be processed by the process. The vacuum source is continuously drawn out of the dryer, and the dust entrained in the volatilized medium vapor should be filtered and dusted during vacuuming; two bag filters are installed in the upper part of the dryer cylinder, and the dust entrained by the volatilized medium vapor is The bag filter is filtered and dusted. The two bag filters can automatically switch off the dust on the filter bag by automatic control, and the filtered dust falls into the dryer. The two bag filters can be switched out and cleaned by automatic control, and the vacuum system is kept open at any time to maintain the vacuum state in the dryer;
11. The research and development results of this project solve the dynamic sealing problem of the inlet and outlet of the dryer and the dust removal problem of continuous vacuuming, so that the drying process of the dryer material is always kept under a certain vacuum condition, and continuous vacuum drying is realized. the goal of. It is mainly used for continuous vacuum drying of water-containing powder materials and paste materials. For the drying of liquid materials, the pumping feeding method is also applicable.