Closed loop horizontal boiling dryer

Principle of Closed Loop Horizontal Boiling Drying Machine

The horizontal closed-loop boiling dryer is a closed-loop drying circulation system. At the beginning, start the fan, open the nitrogen valve, and input inert gas (usually nitrogen) to replace the existing air in the system. When the oxygen content in the system reaches the predetermined target, close the valve. From then on, nitrogen in the system serves as a medium for heat and mass transfer, completing the drying of wet materials. After the organic solvents contained in the wet material are vaporized, they enter the condenser together with nitrogen gas to condense the solvents into liquid and flow into the storage tank. Nitrogen gas, due to its low boiling point, cannot liquefy and enters the next cycle driven by the fan. The drying device in the closed-loop boiling dryer system can choose cylindrical boiling dryer (also known as high-efficiency boiling dryer), box type boiling dryer, vibrating fluidized bed dryer, or even air flow dryer according to the material state and requirements. As these dryers are fluidized state drying, the drying rate is high and the drying time of the material is short.

Characteristics of Closed Loop Horizontal Boiling Drying Machine

1. The system is fully enclosed and has almost no oxygen (content self-control). As mentioned above, the system of the closed-loop boiling dryer operates in a fully enclosed state, with neither outward nor inward leakage. To achieve this, it is necessary to ensure that all parts of the system, whether it is pipeline interfaces or the inlet and outlet of the box; Whether in the positive or negative pressure zone, whether it is a static or dynamic part, it must be strictly sealed. The oxygen content in the system does not exceed the process requirements, ensuring the safety of explosion and flame prevention, and providing reliable assurance for oxygen sensitive materials.

2. Zero emissions. If the system operates continuously, there is basically no exhaust emission.

3. Solvent recovery. If the system can operate continuously, the solvent recovery rate will be very high (up to over 98%), and its economic significance is self-evident.

4. High degree of automation. Our company has set up automatic control and over limit alarm devices for three parameters including temperature, oxygen content, and system pressure in the system, using PLC control, which is easy to operate, safe, and reliable.

Advantages of Closed Loop Horizontal Boiling Drying Machine

1. Security

The equipment is a fully sealed structure, and nitrogen is filled inside the equipment. When drying anaerobic materials or materials containing flammable and explosive solvents, there is no oxygen in the gas, making it unable to burn or oxidize. This can effectively prevent the equipment from catching fire or exploding during production, making it safer than ordinary equipment.

The equipment host uses a bag pulse dust removal system with high dust removal efficiency. The dust does not adhere to the filter cartridge and is easy to disassemble and clean. The equipment discharges materials from the lower part of the host, which can be pumped to the material storage device by vacuum discharge, reducing the workload of workers and improving efficiency. The operation workshop is completely dust-free, with a good workshop environment, high degree of automation, and easy disassembly and cleaning.

After being dried by this equipment, the hot and humid gases containing solvents enter the condenser to condense the solvents in the gas (with a solvent recovery rate of over 95%), which can both recover the solvents and condense the dehumidified dry gas. The recovered solvent can be recycled again, which can save costs and will not cause pollution to the environment due to exhaust emissions.

When the equipment is working, the internal air pressure required is low, only a slight positive pressure is needed, so the power of the fan equipped with the equipment is reduced. This is because during positive pressure, the hot air blows upwards from the lower part of the material mesh plate, and the penetration of the wind is strong. Although the boiling height of the material is not high, the contact between the hot air and the material is more complete, and the drying rate is faster. After the fan power of the equipment is reduced, the noise of the equipment becomes smaller, and energy is also saved.

The hot and humid gas inside the equipment undergoes condensation dehumidification, resulting in lower humidity and stronger drying ability, making it more suitable for moisture absorbing materials that are sensitive to temperature environments.

For materials with finer particles: Due to low air pressure, the escape rate of the material is small, and it can be fully recovered in the secondary dust removal process.

The equipment is in a fluidized state during the drying process, where the material comes into large-scale gas-solid contact with hot air, resulting in high drying intensity and efficiency. With the increase of equipment size and fan air volume, the efficiency of the equipment can still be guaranteed, unlike static vacuum drying systems, where the drying efficiency decreases with the increase of equipment size. The material during the drying process of the equipment is fluidized, which avoids other adverse situations such as local material overheating and deterioration caused by direct contact between the heating surface of the material and the material in the vacuum drying system.

Process flow diagram of closed-loop horizontal boiling dryer