The difference between a closed-loop spray dryer and a regular spray dryer
As an efficient, fast and energy-saving milling process, spray drying technology has been widely used in pharmaceutical, food, chemical and other fields. Among the types of spray dryers, closed-loop spray dryers and ordinary spray dryers are the two most common, and they have significant differences in use and performance.
First, the working principle.
The working principle of ordinary spray dryer is to atomize the material solution into tiny droplets through the nozzle, and then evaporate and dry it in hot air. The dried product is collected in powder form.
The closed-loop spray dryer is a more advanced drying technology, which works by atomizing the material solution into tiny droplets through a nozzle and evaporating and drying in a closed drying chamber. The exhaust gas generated during the drying process is purified by the dust collector and discharged, and the dried product is also collected in powder form.
Second, structural characteristics.
The structure of ordinary spray dryer is relatively simple, mainly composed of nozzle, hot air inlet, drying chamber, discharge outlet and other parts. Due to the limitations of its structure and working principle, ordinary spray dryers can only carry out open-circuit drying, that is, the exhaust gas generated during the drying process is directly discharged.
The structure of the closed-loop spray dryer is more complex, and in addition to the partial structure of an ordinary spray dryer, it is also equipped with additional structures such as exhaust gas treatment system and sealing device. The existence of these structures enables the closed-loop spray dryer to carry out closed cycle work, and the exhaust gas can be reused after treatment, which improves energy utilization and environmental performance.
3. Scope of application.
Due to its simple structure, convenient operation and low cost, ordinary spray dryers are widely used in some occasions with low requirements for drying. For example: drying of chemical products, drying of feed before pelleting, etc.
Due to its high energy utilization rate and environmental performance, closed-loop spray dryer is widely used in some occasions with high requirements for product quality and environmental protection. For example: drying of pharmaceutical products, drying of food additives, etc. In addition, because the closed-loop spray dryer can carry out closed cycle work, the equipment can also play a protective role for some volatile or air-sensitive materials.
Fourth, the advantages and disadvantages are compared.
The advantages of ordinary spray dryers are simple structure, convenient operation, and low cost. However, due to the characteristics of its open circuit work, it is easy to be affected by the external environment, such as air humidity, temperature, etc., resulting in unstable product quality. In addition, due to the direct exhaust gas discharge, the energy utilization rate of ordinary spray dryers is low, which does not meet environmental protection requirements.
The advantages of closed-loop spray dryer are high energy utilization, good environmental performance, and stable product quality. At the same time, because it can carry out closed cycle work, it can also play a protective role for some special materials. However, due to its complex structure and high cost, it is not suitable for some occasions with low cost requirements.
To sum up, closed-loop spray dryers and ordinary spray dryers have their own advantages and disadvantages, and the specific choice of which equipment needs to be considered according to actual needs. In today's pursuit of product quality and environmental protection requirements, closed-loop spray dryer as an advanced milling process will be more widely used.