Introduction
In recent years, the production scale and sales growth of fine chemicals in China have been very large, and fine chemical equipment and technology have also been developed and promoted to a certain extent. Conventional Efficient Fluid Bed Dryers can no longer come close to meeting the increasingly high safety and environmental protection requirements of the chemical industry, and a number of problems have gradually come to light in production. These problems are no longer applicable to the production processes of flammable and explosive chemical products, as shown in the following points:
(1) The equipment's explosion-proof performance is poor; only simple explosion-proof measures are taken, which cannot ensure the safety of operators and the plant, leaving hidden risks in production;
(2) Filter bag installation and removal is inconvenient. Although a wire-rope structure is used to mount and remove the bags, the connection between the bag and the upper cylinder still requires manually fastening the bottom edge of the bag to the flange of the upper cylinder with a rope, which is inconvenient to operate;
(3) The fluidization plate of the fluid bed mostly uses a vertically perforated plate or a mat-type mesh plate, so during fluidization the material is prone to uneven fluidization or dead corners, and the drying uniformity of chemical products cannot be guaranteed;
(4) The fluidization plate and the main drying unit are mostly fixed with bolts, which makes disassembly inconvenient and easily leads to incomplete discharge and product residue.
In response to the above problems, based on the rich experience accumulated over many years in the production and commissioning of dedicated equipment for fine chemical post-treatment production lines, and combined with the characteristics of similar foreign equipment, Jiangsu Longxin developed a new type of automatic discharge Efficient Fluid Bed Dryer and brought it to market. This equipment provides granulating, coating and drying functions as well as explosion-proof performance, and is now widely used in fine chemical industries such as pesticide technical materials, rubber additives and new materials.
Automatic Discharge Efficient Fluid Bed Dryer — Working Principle
The automatic discharge Efficient Fluid Bed Dryer is dedicated equipment for powder drying in the fine chemical industry. In a closed vessel, wet material enters the main drying unit through the feed inlet on the equipment. The supply fan delivers filtered air, which is heated by the heater to the temperature required by the drying process and then enters the fluid bed to carry out heat and mass transfer (drying) of the material added through the height-difference feed inlet. After charging is complete, drying continues until the material reaches the required final moisture content. During drying, the hot, humid gas carries a small amount of fine powder through the dust collector, where all fine powder above 2 μm undergoes gas-solid separation. Once drying is complete, a flap (tilting plate) mechanism discharges the material on the hot-air distribution plate into the lower cylinder, from where it is conveyed by a vacuum pump or pneumatic conveying system into a closed vessel for storage and packaging (both feeding and discharging take place in a closed environment, with no dust in the workshop).
Automatic Feeding and Discharging Efficient Fluid Bed Dryer — Equipment Structure
The automatic discharge Efficient Fluid Bed Dryer consists of an air filter, air heater, drying bed, separation chamber, filter chamber, exhaust duct, induced draft fan, chimney, control system and so on.
(1) Main unit: the main unit consists of the bottom air inlet chamber, the drying bed, the separation chamber and the filter chamber.
(2) Air filter: filtered by primary and medium-efficiency air filters, ensuring the cleanliness of the inlet air to Class 300,000.
(3) Air heater: uses stainless steel tubes wound with aluminium fins, which increases the heat transfer coefficient of the heat exchanger while ensuring that no rust or foreign matter falls off.
(4) Exhaust system: composed of an exhaust duct, induced draft fan and silencer. The induced draft fan is installed separately (isolated) from the main unit, with noise ≤80 dB, and the air volume can be controlled by variable-frequency speed regulation to adjust the fluidization state continuously. The machine is therefore suitable for a wide range of feed quantities and also adapts well to the air volume requirements of different material conditions.
(5) Stirring mechanism: an internal rake-tooth stirring mechanism built into the material trolley assists fluidization and prevents channelling and dead-bed conditions during drying, keeping the fluidized state stable and the moisture content of the dried material uniform.
Automatic Feeding and Discharging Efficient Fluid Bed Dryer — Performance Features
(1) PLC + touch screen operation; convenient and stable, with strict interlock functions that prevent human error in operation.
(2) Dust cleaning is by pulse bag cleaning, with continuous off-line cleaning and dust removal during operation. The cleaning effect is far superior to on-line pulse cleaning and cylinder bag-shaking cleaning, and it prevents material dead-bed during drying.
(3) Equipped with top-withdrawal rigid-cage filter bags, which ensure bag area and cleaning effect while reducing the poor working conditions workers face when removing and washing the bags. The bags can be easily removed from the equipment without anyone having to climb inside the cylinder.
(4) The equipment feeds material automatically under negative pressure through its own induced draft fan, reducing manual operations and easing the labour intensity of workers.
(5) Through the automatic discharge device, the equipment achieves automatic, enclosed discharge, reducing cross-contamination of materials and reducing workers' labour intensity.
(6) The equipment incorporates a stirring structure that prevents material bridging and dead-bed, giving better material fluidization and drying results.
(7) The equipment adopts a closed circular structure with no dead corners; cleaning is convenient and quick, with no cross-contamination. The whole unit is easy to operate, easy to disassemble and easy to clean, and meets "GMP" requirements.
(8) When docked with a pneumatic conveying system, it can achieve unattended, fully automatic continuous operation (optional).
(9) A drainage device is provided at the bottom of the main unit, which can quickly drain away the accumulated water when the machine is being cleaned.
Automatic Feeding and Discharging Efficient Fluid Bed Dryer — Flow Chart 1: Open systems
Automatic Feeding and Discharging Efficient Fluid Bed Dryer — Flow Chart 2: Close cycle systems
