Equipment Overview

The closed-loop circulating vibration fluidized bed dryer is a new type of drying (cooling) equipment developed by our factory based on absorbing advanced foreign technology and integrating more than ten years of drying experience. It has been widely used in various industries. The vibrating fluidized bed not only has excellent drying function, but also can complete processes such as material granulation, cooling, spraying a small amount of liquid, screening, and transportation according to process requirements.

The closed-loop circulating vibrating fluidized bed dryer is an improved type of hot air convection dryer. During operation, the excitation force provided by a vibration motor or other means causes the material to jump forward on the air distribution plate, while also coming into contact with the hot air sent in from below the distribution plate for heat and mass transfer. The lower box provides a stable air chamber with a certain pressure for the bed layer. Adjust the induced draft fan to maintain a slight negative pressure on the upper part of the bed material in the upper box, maintain a good dry environment, and prevent dust leakage. The air distribution board supports the material and evenly distributes the hot air.

Measures to address the risk of explosion in a closed-loop vibrating fluidized bed dryer

To solve or reduce the safety risks of closed-loop drying machines for organic solvent pesticide raw materials during the drying process, analyze the explosive elements, select inert gases and high flash point solvents to avoid the formation of explosive gases, and use metal conductive materials for devices and materials to eliminate static electricity; Take measures such as explosion-proof boards and automatic control to reduce the harm of explosions to people.

(1) Organic solvent selection

Water is preferred as the medium for crystallization and rinsing of pesticide raw materials. If water cannot be used as the medium for raw materials, solvents with high flash points, high gas explosion limits, and narrow explosion limits should be selected to avoid mixing gases that can easily reach explosive concentrations during the drying process, and to increase the minimum ignition energy to reduce the risk of explosion.

(2) Using inert gas nitrogen protection

When choosing flammable and explosive liquids as solvents, inert gas nitrogen should be used as the drying medium to effectively prevent explosions. The safety and reliability of nitrogen gas, while avoiding the oxidation and deterioration of easily oxidizable raw materials during the drying process, improve the quality of the product.

(3) Exhaust gas treatment equipment and dust removal bags

The material of the closed-loop dryer is high-quality stainless steel, and the air ducts, condensers, fans, etc. are made of conductive materials such as galvanized steel pipes or stainless steel. The dust removal bag body of the drying fluidized bed is mostly made of fibers, which are prone to static electricity. By adding conductive anti-static fibers during fiber weaving, static electricity can be evenly and quickly dissipated, and static electricity will not accumulate, thereby eliminating the generation of sparks.

(4) Explosion proof motor, electrical

Explosion proof motors are selected for the induced draft fan and hopper mixing motor, and explosion-proof measures are taken for the on-site control instruments. The explosion-proof level meets the requirements for explosion prevention of explosive gases and dust. The electrical control cabinet and device shall be isolated and comply with the distance regulations related to the explosion-proof zone.

(5) Explosion proof film

Explosion proof plates are installed on the main equipment of the organic solvent raw material dryer, which effectively dissipate the energy generated in the event of an explosion and prevent damage to the equipment system. The area of its explosion-proof board should be calculated based on factors such as the drying medium of the dried material, the characteristics of the organic solvent, and the drying temperature. For organic solvent drying, the occurrence of gas explosions and dust explosions should also be considered.

(6) Anti static grounding

During the drying process of organic solvent raw materials, static electricity exists, and it is crucial to quickly and uniformly discharge the generated static electricity. Special copper braided flange jumper wires should be selected between pipelines and equipment flanges. The grounding wires of the air ducts should be evenly spaced, and the equipment should have reliable equipotential grounding and be interconnected with each other.

(7) Automation and Interlocking Control

With the development of automation technology, closed-loop drying machines can be operated using automated programs from feeding to drying finished products, recording, alarming, controlling, adjusting, and automating indicators such as drying medium temperature, drying time, and drying air volume to reduce the number of on-site personnel and effectively protect the safety of operators. By setting temperature, pressure, and online gas detection concentration alarms, safety risks can be detected early; Setting up interlocks for cutting off and stopping the heating medium can promptly address safety hazards and prevent the escalation of accidents.

Performance characteristics of closed-loop circulating vibrating fluidized bed dryer

1. Due to the application of vibration, the minimum fluidization gas velocity can be reduced, which can significantly reduce the air demand and thus reduce dust entrainment. The supporting heat source, fan, cyclone separator, etc. can also be correspondingly reduced in size, and the cost of the complete equipment will be significantly reduced, resulting in significant energy-saving effects.

2. It is convenient to adjust the vibration parameters to change the residence time of materials in the dryer. The piston flow operation reduces the requirements for material particle size uniformity and regularity, making it easy to obtain uniform dry products.

3. Vibration helps to disperse materials. If appropriate vibration parameters are selected, materials that are prone to agglomeration or generate channeling in ordinary fluidized beds may be fluidized and dried smoothly.

4. Due to the absence of intense material return, the airflow velocity is lower compared to ordinary fluidized beds, resulting in less damage to material particles. For materials that require no damage to crystal form or surface brightness during the drying process.

5. Due to the application of vibration, noise will be generated. At the same time, some parts of the equipment have a shorter lifespan than other types of dryers.

Process flowchart of closed-loop circulating vibrating fluidized bed dryer