Classification by Bed Type
FBD can be classified according to bed type: vibrating and static.
Vibrating Fluid Bed Dryer
The vfbd dryer is a very successful improved fluidized bed dryer and is increasingly becoming the main type of drying equipment. By applying a specific required vibration source to a common fluid bed dryer. According to its excitation method, it can be classified into electric motor, electromagnetic induction, crankshaft or eccentric, pneumatic and hydraulic .
Advantages of vibrating fluidized bed dryer
- The object is heated evenly, the heat exchange is sufficient, and the drying strength is high.
- Balanced operation, easy maintenance and and long service life.
- The fluidization is uniform, and cooling and humidifying products can be obtained.
- Good adjustability, adaptability to surface width, material layer thickness, moving speed in the machine, and full amplitude change can achieve stepless adjustment.
- It has little damage to the surface of the material and can be used for drying fragile materials, and the work effect will not be affected when the material particles are irregular.
- The fully enclosed structure is used to effectively prevent the cross infection between the material and the outside air.
Disantages of vibrating fluidized bed dryer
- Generally not suitable for materials that are easy to stick to the wall and agglomerate;
- The vibro fluid bed dryer is not suitable for the fluidization operation of materials with large differences in density;
- There are certain requirements for the particle size of the material, and the general particle diameter is 30 μm ~ 6 mm.
- Due to the need for auxiliary equipment such as fans, heaters, separators or dust collectors, the equipment is relatively heavy and occupies a large area;
- The thermal efficiency of the vibrating fluidized bed dryer is generally 40% to 60%. From the perspective of energy saving, the thermal efficiency needs to be improved.
Static Fluid Bed Dryer
Static fluid bed dryer utilizes gas or liquid to pass through the granular solid layer to keep the solid particles in a suspended motion state, and conduct gas-solid phase reaction or liquid-solid phase reaction. When used in gas-solid reaction systems, it is also called boiling fluidized bed.
Any equipment in which the fluid passes through the bed layer formed by the immobile solid material is called a fixed bed reactor. Among them, gas-solid-phase catalytic reactors, which use gaseous reaction materials to react through a bed composed of solid catalysts, are the most widely used in chemical production.
Advantages of static fluid bed dryer
- The chemical reaction speed is faster, and the required catalyst dosage and reactor volume are smaller when the same production capacity is achieved.
- The gas residence time can be strictly controlled and the temperature distribution can be adjusted, which is beneficial to improve the conversion rate and selectivity of the chemical reaction.
- The catalyst is not easy to wear and can be used continuously for a long time.
- Suitable for operation under high temperature and high pressure conditions.
Disadvantages of static fluid bed dryer
- Heat transfer in the static FBD dryer is poor.
- The regeneration and replacement of the catalyst are inconvenient, and the production must be stopped for replacement.
- Fine particle catalysts cannot be used.
Classification by Production Method
Fluidized bed dryers can be classified into three categories according to production methods: continuous, semi-continuous and batch.
Semi-continuous Fluidized Bed Dryer
Semi-continuous fluidized bed dryers have several drying chambers that work in parallel, and it combines the features of continuous FBD and batch FBD.
Since it will generate a lot of waste in the process of running, there will be a high volume of material remains in the semi-continuous fluid bed dryer chambers.
Based on this significant limitation, we usually choose between continuous FBD and batch FBD.
Batch Fluid Bed Dryer
Batch fluidized bed dryers usually come in a vertical shape, so it usually called vertical fluid bed dryer.
Hot gas is supplied from the bottom of batch fluid bed dryer through the perforated plate to fluidize and dry the powder materials. Feeding, drying, and discharging processes are repeated in a batch process.
Main Features of batch fluid bed dryers
- Reaches low moisture content with a relatively low drying temperature.
- Uniform drying is possible by controlling the residence time.
- Batch fluid bed dryer is suitable especially for the material which requires drying in the decreasing-rate drying zone.
- Minimized damage to the powder. Suitable for granules or crystallized materials.
- Easy operation by automatic controlling system of feeding, drying, and discharging processes.
- All of the powder materials are easily discharged.
Fluid Bed Dryer Operation Tips
- Before use, confirm that the voltage of the power supply meets the requirements, and confirm that there is no foreign matter in each fan.
- Turn on the heating valve of the induced draft fan, blower and steam pipe, the system generates hot air, preheats the drying system, and observes whether there is air leakage at each connection. If there is an air leak, tighten it in time. After reaching the preheating requirements (the temperature of the hot air inlet is about 130°C), adjust the valves of each air inlet so that the drying system is in the state of air volume and temperature during normal operation.
- Turn on the vibration motor and observe whether the vibration of the lower box and the bed is stable. If any unevenness is found, the vibration motor should be turned off immediately to find out the reason.
- When feeding begins, the feeding status should be observed at any time. When feeding, the material should enter the feeding port of the vibrating fluidized bed dryer evenly and quantitatively.
- Observe whether the product discharge from the discharge port of the fluid bed dryer machine is uniform, and regularly check the moisture content and output of the product.
- Open the air closer at the discharge port of the cyclone dust collector regularly.
- When the drying system stops working, the feeding should be stopped first. When the discharge port of the dryer no longer discharges the material, the power supply of the vibration motor can be cut off to make the vibration fluidized bed dryer stop working. Then close the valve of the steam pipe, no longer generate hot air (refer to its corresponding instructions when using other heat sources), and let the drying system cool down gradually. After a while, the power to the blower and other motors is turned off, at which point the entire drying system stops working.
- The user should gradually accumulate experience in the process of use, find out the best working parameters of the fluidized bed dryer, and make the whole set of drying equipment reach the best working condition.
Fluid Bed Dryer In Pharmaceutical Industry
In the pharma industry, the drying step in many pharmaceutical production lines is often a bottleneck because the process is affected by many parameters and it is difficult to determine the time required to dry the material.
Fluid bed drying machine is widely used in the pharmaceutical industry due to their good mixing between the solid and hot gas phase inside and strong heat and mass transfer.
Fluid Bed Dryer In Food Industry
Due to the particularity of food materials, its drying method and drying conditions are also different from those of ordinary materials. It is not only necessary to remove moisture from dry food materials, but also to ensure that the nutritional elements of the food are not destroyed, or are destroyed as little as possible. At the same time, a series of factors such as color and taste after processing need to be considered in food processing.
Ordinary drying equipment is difficult to meet the above strict technical index requirements. In order to solve these problems, various fluidized bed dryers have emerged: pulsation-assisted fluidized bed, adsorption fluidized bed, centrifugal fluidized bed and heat pump fluidized bed.
Fluid Bed Dryer In Chemical Industry
The molecular structure of many materials in the chemical industry contains free water, which makes its molecules unstable. In case of heat, free water often overflows, and moisture absorption is easy to agglomerate. Therefore, the dehydrated chemical raw materials need to be dried to remove excess water.
For example, the drying of zinc sulfate has always been a difficulty. ZnSO4·7H2O is a stable hydrate in equilibrium with water in the range of 0-39℃, and when the temperature is 39-60℃, it will be converted to ZnSO4·6H2O, and when the temperature is 60-100℃, it will be ZnSO4 ·H2O.
When using a vibrating fluidized bed dryer to replace the air flow dryer that was often used in the past to dry zinc sulfate, the product quality and corporate profits were significantly improved.
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Griffin Machinery, an experienced and reliable partner.
If you are also looking for a gentle, yet effective way to dry your product, please contact us for advice. Our team is ready to help you find the right solution for your project.
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