Overview of multi-layer flow-through belt dryer equipment
Multi layer flow-through belt dryers are commonly used in situations where the drying speed is low, the drying time is long, and the process operating conditions can be maintained constant throughout the entire drying process. Set up partitions between layers to organize the directional flow of drying medium, ensuring uniform drying of materials. Multi layer belt dryer takes up less space, has a simple structure, and is widely used for drying grain materials. Due to the need for multiple loading and unloading during operation, it is not suitable for dry, adhesive conveyor belts and materials that are not allowed to break.

Working principle of multi-layer flow-through belt dryer
The multi-layer flow-through belt dryer is equipped with feeding devices and discharge ports at both ends, and a dehumidification device is installed on the top of the equipment. One end of the feeding device is equipped with a blower and an air heater. The drying machine is equipped with multiple layers of drying mesh belts from top to bottom, and each layer of drying mesh belt is equipped with a transmission shaft at both ends. The transmission chains installed on both sides are fixedly connected to the mesh belt and operate by a sprocket transmission device. The external cold air is heated by the air supply fan through the heat exchanger and blown into the dryer, while the hot air penetrates the mesh belt and material layer from bottom to top. When reaching the upper mesh belt, the humid air is carried out through the exhaust duct by the dehumidification fan.

Structure diagram of multi-layer flow-through belt dryer equipment

Characteristics of multi-layer flow-through belt dryer equipment
The GWC multi-layer flow-through belt dryer is widely used in the dehydration and drying of sheet, strip, block, and granular materials in industries such as food, agricultural and sideline products, dehydrated vegetables, traditional Chinese medicine, aquatic products, local specialties, feed, and chemical raw materials.
(1) This series of dryers uses multi-layer mobile stainless steel mesh belts or vibrating plates to spread the processed materials. The hot air flow passes through the mesh belt and the material layer from bottom to top, with uniform and sufficient heat exchange, high production efficiency, and good product quality. It is equipped with a cooling layer and a rotating feeding device, and the discharge temperature is low, which is conducive to timely packaging.
(2) Adopting a lifting device with a homogenizer, the thickness is uniform, and the thickness of the material layer can be infinitely adjusted.
(3) The spreading area ranges from 25m2 to 120m2, with seven different sizes of machines that can meet the needs of various materials and different production scales.
(4) In the long-term production practice, Baide Drying adjusts the equipment structure based on the actual experience of customer production and use, continuously optimizes and updates the series of products, develops various structural forms, and has targeted designs and good usage effects for products with different properties. Based on the equipment structure, the series of products are now classified into standard models.
(5) Bottom air intake, multi-layer penetration, direct exhaust emissions.

Multi layer flow-through belt dryer with multiple optional configurations
(1) Conveyor belt
The most commonly used conveyor belt in China is made of stainless steel wire mesh, with a mesh size of 10-14 mesh, which needs to be determined based on the material particle size, material density, and material thickness. If a single-layer mesh appears thin, two layers of mesh can be stacked together for use. Underneath the wire mesh, there is a roller support, which is connected and fixed to the roller. Insert both ends of the roller into the hollow shaft of the conveyor chain and run together with the chain.
If the material is sticky, a non stick mesh can be attached to the stainless steel wire mesh.
Perforated steel plates are connected to form a conveyor belt. The thickness of the steel plate is 1mm to 1.5mm, and the perforation rate is determined by the rigidity of the perforated steel plate. There is information that the porosity is between 6% and 45%, which is too large. Based on practical experience, a steel plate thickness of 1.2mm and an opening rate of 12% to 18% are suitable. Can open a circular hole with a diameter of about 2mm; You can also punch long holes. The width of each perforated steel plate is equal to the pitch of the chain, and both ends of the perforated steel plate can be connected to the inner ear plate of the non-standard conveyor chain, so that the perforated steel plate can run together with the conveyor chain.
(2) Feeding device
If the thickness of the material layer on the conveyor belt is uneven, it will cause a short circuit or uneven pressure drop in the drying medium (hot air), resulting in the thin material layer being "over dried" and the thick material layer being insufficiently dried, affecting product quality. Therefore, the design of the feeding device is crucial.
Feeding funnel: This is the simplest feeding device, suitable for non sticky granular, block shaped and other solid materials with good flowability, such as fruits, pills and vegetables cut into small pieces or thin slices. The width of the funnel discharge port is equal to the effective drying width of the conveyor belt, and the discharge port is equipped with a gate to adjust the feeding amount.
Feeding funnel with flat blade mixing shaft inside: Add a flat blade mixing shaft to the above feeding funnel to prevent material from staying on the inclined wall of the funnel, suitable for granular materials with poor fluidity.
Replace the flat blades with uniformly toothed blades, suitable for fibrous materials such as wool, synthetic fibers, cellulose, etc. Due to the uniform tooth shaped blades, the fiber material can have a uniform thickness on the conveyor belt.
(3) Transmission device
The transmission device consists of a non-standard large pitch chain, sprocket, sprocket shaft, six pole motor (960r/min), frequency converter, two-stage cycloidal pinwheel reducer, and a set of gears or sprocket reducers.
Non standard large pitch chain: For wire mesh conveyor belts, the chain pitch is generally 76.2mm (3 inches) or 101.6mm (4 inches). The chain shaft is a hollow shaft that can pass through the roller shaft end of the supporting mesh belt; For punched plate conveyor belts, the chain pitch is 6-8 inches, which can increase the width and rigidity of the punched plate. There are ear plates on the inner side of the chain to fix the punched plate and lateral baffle plate. If the hot air temperature is below 200 ℃, the chain material is Q235A; If the temperature of the hot air is higher than 200 ℃, 16Mn should be considered as the material for the chain.
Chain wheel: The chain wheel should be made of 45 steel, and the teeth of the chain wheel should be locally quenched to increase wear resistance. The key slots on the chain wheels at both ends of the same chain wheel shaft must be in the same orientation. Suggest overlapping a pair of sprockets and spot welding them together before machining the keyway.
Chain wheel shaft: If the chain wheel shaft is long, carbon steel pipe can be used for the middle section; Two sections are made of solid shaft ends, plug welded or ring welded in steel pipes, and made of 45 grade steel. The two shaft ends must be kept concentric, and the key slots on the two shaft ends must be on the same busbar. This is in line with the requirements of the sprocket key slots, which can ensure that the chains on both sides do not have forward or backward displacement, and also ensure that the mesh belt conveyor and orifice plate conveyor do not tilt.
Six pole ordinary motor+frequency converter: For ordinary motors, the frequency can be reduced to 15Hz, which can make the motor output speed reach a minimum of 290r/min.
Double stage cycloidal pinwheel reducer: Its reduction ratio should be taken as 289-377, so that the minimum speed at the output end of the reducer is 1-0.77r/min.
A set of gears or sprockets for reduction: Its reduction ratio is 2.5-3, which can make the minimum linear speed of the conveyor belt 0.4-0.8m/min, ensuring the drying time required for materials that are not easily dried.

Technical parameter table of multi-layer flow-through belt dryer