Overview of Closed Cycle Centrifugal spray Dryer
The closed cycle centrifugal spray dryer is a closed circulation loop formed by the system, and the heat carrier can be recycled. For the drying of volatile organic solvents, toxic or hazardous materials that can cause harm to people and the environment after release, the organic solvents or products contained in the liquid are easily oxidized, flammable, and explosive materials. In general, materials that require this process cannot come into contact with oxygen, so most heat carriers use inert gases (such as nitrogen, carbon dioxide, etc.); This method is also known as inert gas drying. The exhaust gas discharged from the dryer, after gas-solid separation, also needs to go through a condenser to recover solvents or remove moisture, and then enter the dryer for recycling after being heated by a heater. Through the heat carrier and closed cycle, we can effectively avoid the danger of high temperature when drying materials, prevent contact with oxygen during spray drying, and recover more than 90% of dust.

The closed cycle spray dryer has been mature and applied to the closed cycle spray drying process for the suspension made of ethanol, acetone, cyclohexane, toluene and other organic solvents, and the products with inert gas (or nitrogen) as the drying medium. The entire process is oxidation free, the medium is recyclable, and the inert gas (or nitrogen) can be recycled. The closed cycle system designed for organic solvent recovery has extremely high requirements for explosion-proof control, high system self-control performance, and strict GMP requirements. It is commonly used for spray drying of precision ceramics, pharmaceuticals, battery materials, hard alloy (Wc. Fe) powder.

PID Diagram of Closed Cycle Centrifugal spray Dryer

Working principle of closed cycle centrifugal spray dryer
The explosion-proof closed cycle centrifugal spray dryer system consists of the main engine of the centrifugal spray dryer, heater with air filter, blower, moisture separator, large and small cooling towers, spray tower, exhaust fan, primary cyclone separator, secondary cyclone separator, pump, oxygen detector, pipeline and control valve.
Working principle: Firstly, heated nitrogen gas is filled into the drying tower, and the dried liquid material is transported to the centrifugal nozzle through an infusion pump. The liquid material is atomized into small droplets by a high-speed rotating centrifugal atomizer, and the droplets undergo sufficient heat exchange with the hot nitrogen gas in the drying tower. The liquid part of the material is instantly evaporated, and the solid part forms a powder material that settles at the bottom of the tower. Finally, the dried powder material is discharged from the bottom of the tower. Among them, the evaporated organic solvent gas is subjected to dust removal treatment by devices such as cyclone separators and spray towers under the action of a fan, and then the saturated organic solvent gas after dust removal is condensed into liquid and discharged from the condenser. During this process, the inert gas used as a drying medium is continuously heated and reused as a drying carrier within the system.
The explosion-proof closed cycle centrifugal spray drying system works in a closed environment. The drying medium is inert gas such as nitrogen. The drying tower is operated under positive pressure. If the internal pressure drops, the pressure transmitter can automatically control the amount of nitrogen entering to ensure the system pressure balance. Due to the use of nitrogen as a circulating carrier, it has a protective effect on dry materials. Nitrogen and other circulating carriers play a role in carrying, removing, and circulating moisture, and their carrier media can be reused. However, conventional conventional centrifugal spray drying achieves the purpose of moisture removal through continuous air supply and exhaust, and its tower is controlled by negative pressure operation, which is also the obvious difference between explosion-proof closed centrifugal spray drying system and conventional centrifugal spray drying system. Therefore, the explosion-proof closed cycle centrifugal spray drying system is particularly suitable for drying organic solvent materials, toxic gas materials and materials prone to oxidation in the drying process.

Three dimensional drawing of closed cycle centrifugal spray dryer

New technical theory of closed cycle centrifugal spray dryer:
1. The closed circulation system was applied to the explosion-proof centrifugal spray dryer, and was the first to be applied in industrial production;
2. The application of pressure differential automatic transmission and online oxygen detection technology makes the system safer and product quality more guaranteed;
3. The application of intelligent automatic control technology has upgraded the traditional centrifugal spray drying equipment;
4. Innovative mechanical seal leak free technology has effectively solved the leakage problem of such systems.

Advantages of closed cycle centrifugal spray dryer
1. The closed cycle centrifugal spray dryer uses nitrogen as the conduction and heat transfer medium and nitrogen as the carrier to achieve closed cycle in a closed state, effectively achieving the safety of drying liquid materials containing organic solvents, and protecting the oxidation resistance of easily oxidized wet materials in the drying process.
2. This unit adopts a new spray drying technology, so as to achieve the high solid content that traditional centrifugal spray drying can not compare with, and has the viscous and thick liquid material nitrogen power atomization, so as to improve the production capacity and reduce energy consumption by more than 70%, achieving a significant energy saving and high-yield production effect.
3. This unit adopts online monitoring and self diagnostic control functions to ensure safe production of liquid materials containing organic solvents during drying. The intelligent control system has a high degree of automation.
4. This unit realizes the recycling and utilization of materials containing organic solvents in the drying production process, and on the basis of solving the difficulties in drying and heavy pollution caused by exhaust gas emissions in related industries, achieves the practical effect of energy conservation and emission reduction through solvent recycling and utilization.