In the fine chemical synthesis process, the extraction and washing (including water washing and alkali washing) processes are essential links. Their main purpose is to remove solvents and by-product salts from the reaction solution. However, at present, these two processes still rely on traditional kettle stirring and standing separation, which have problems such as low separation efficiency and long standing time, which seriously affect the efficiency of subsequent processing units. This results in a low degree of automation, long process cycles, large wastewater output, and high direct costs in the production of prepared compounds, which limits the improvement of manufacturing levels.
In order to meet the needs of continuous production in modern factories, Zhengzhou Tiei Extraction has launched the CWL-M series of new centrifugal extractors based on the extraction and separation characteristics of nitrification reactions and synthesis reactions. CWL-M series centrifugal extraction technology realizes contact mass transfer and phase separation of liquid-liquid phases by using centrifugal force field. It has the characteristics of compact structure, large processing capacity, stable operation, low power consumption, and convenient cleaning and maintenance.
In the centrifugal extractor, the mixing-mass transfer process occurs in the gap between the fixed outer cylinder and the high-speed rotating inner cylinder, while the stratification of the extraction phase and the raffinate phase is completed in the high-speed rotating inner cylinder, and the separation is achieved through the control weir system. The two processes of mixing, mass transfer and separation and clarification are completed in the same equipment. Since the advent of the centrifugal extractor, it has developed rapidly and has been widely used in chemical industry, pharmaceuticals, metallurgy, wastewater treatment, petrochemical industry and other fields in many countries.
According to the summary of practical experience, compared with traditional extraction towers, mixing settlers and other equipment, centrifugal extraction technology has obvious advantages in terms of volume efficiency, storage flow, mass transfer efficiency and residence time:
- In terms of volumetric efficiency, the centrifugal extractor has the highest volumetric efficiency, which can usually reach 30 to 50 times that of the mixing settlers.
- In terms of storage flow, due to the strong phase separation ability of the centrifugal extractor, its volume is much smaller than the mixing settlers and the extraction tower under the same output demand.
- In terms of mass transfer efficiency, the stage efficiency of centrifugal extractors is very high, generally reaching more than 99%. In contrast, the extraction tower is prone to axial backmixing, resulting in lower mass transfer efficiency.
- In terms of residence time, the residence time of the centrifugal extractor is the shortest among the three types of equipment, and is generally controlled between a few seconds to tens of seconds.
Therefore, applying centrifugal extraction technology to extraction and washing in the chemical synthesis reaction process can not only transform the original intermittent operation into the continuous process, but also greatly improve the separation efficiency. This is of great significance for promoting the advanced development of chemical machinery.
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