What Is Mass Transfer?
The mass transfer process is the process of material transfer. Due to the difference in concentration, matter can be transferred within one phase or between phases. That is, from one phase to another. For example, in the process of gas production, the process of dissolving crude benzene in coke oven gas into the washing oil under the effect of concentration difference, the process of ammonia dissolving in water, and the process of water evaporation to air. Mass transfer process is an important process in the production of urban gas, chemical, metallurgy, medicine and light industry. It includes many unit operations such as absorption, adsorption, distillation, rectification, extraction and drying. [1]
- To sum up, the mass transfer process can be divided into two categories.
- One is a mass transfer process accompanied by a chemical reaction, usually performed in a reactor. For example, the quinone removal of hydrogen sulfide in coal gas, the pyrolysis of petroleum gas, the synthesis of ammonia, and the synthesis of polymers are all carried out in specific reactors, following different reaction mechanisms, and undergoing various treatments. Get the product you want.
- The other is the mass transfer process without chemical reaction, such as the absorption operation of crude benzene and naphthalene in the recovered gas; such as the separation of crude benzene, the processing of coal tar, the production of ethanol, and the distillation and processing of petroleum processing. Distillation operations; such as drying of products in the production of ceramics, dyes, urea, pharmaceuticals and food; such as the separation and purification of phenol-containing wastewater in gas and other industrial waste liquids, extraction of rare metals, and separation from fermentation broth Extraction operation by penicillin and the like. [2]
- As long as the imbalanced two are in contact with each other, mass transfer must occur. The driving force of the process is usually expressed by the degree of deviation of the actual concentration of one phase from its equilibrium concentration. As shown in the figure, if the state point is A (Y, X), the driving force represented by the difference in gas phase concentration is Y = Y-Y '; the driving force represented by the difference in liquid phase concentration is X = X-X '. [1]