Technical basics
A fluidized bed is created when gas flows upward through a layer of powdery material. The weight of the powder articles is compensated through the upward flow of the gases. The powder thus caused to be suspended then behaves similarly to a liquid. The large advantage of this homogeneous mix of powdery products with preheated gases is that a very uniform matter and heat transport occurs; this also ensures extremely uniform temperature distribution.
Batches or continuous?
The many years of experience of thermal cleaning gave birth to the idea to use fluidized bed technology also to perform chemical reactions at high temperatures. Based on the scalable gas distribution plate SCHWING dimensions the systems according to the respective requirement profile. State-of-the-art measuring and control technology of the SCHWING fluidized bed reactors ensures precise process control and reproducibility of the thermo-chemical processes where temperatures up to 1100 °C or process pressures up to 15 bar as well as the use of aggressive media are possible.
If required, periodically cleaned hot gas filters for the cleaning of the waste gas and recycling of the solids are integrated in the fluidized bed of the reactors. The fluidized bed systems can be operated both discontinuously and continuously.
Batch operation for top uniformity
Cold or preheated gas or a fluid-gas mixture flows into the bottom chamber of the fluidized bed reactor. The pressure and flow parameters determined in the lab are transferred to the exchangeable fluid-gas distribution plate. The fluidized bed reactor can be heated either electrically or via an external combustion chamber divided into several heating zones. A so-called freeboard is located above the fluidized bed functioning as a sedimentation zone for heavier particles. The reaction gas is cleaned of very fine particles through hot gas candle filters. The candle filters are equipped with a blow back system and are cleaned sequentially. The solids thus remain in the reactor until drained through the product drainage valve integrated in the bottom.
If purging of particulate matter is required, the filtration unit can be placed outside the reactor. Alternatively, separation via cyclone is possible. Cooling and heat transfer systems which can be integrated are available for strongly exothermal reactions.
Continuous operation for maximum economy
SCHWING also offers multistage fluidized bed reactors for continuous chemical reactions. These multistage reactors can be designed for calcining or drying powders or granulates with up to 150 theoretical mixing stages.
Based on a special flow and dwell concept the multistage systems achieve such a product uniformity as could so far only be realized through batch operation. At the same time, the economic advantages of continuous processes can be fully utilized at the large technical scale. The system is especially suitable for products where the quality depends very much on the treatment time.
You want to learn more?
Please call +49 2845 930-115, send us an e-mail or contact one of our experts with any question you may have.
