Method and device for recycling waste clear liquid produced in process for producing sodium carbonate by ammonia-soda process

Abstract

The invention relates to the technical field of soda production, in particular to a method and a device for recycling waste clear liquid produced in a process for producing sodium carbonate by an ammonia-soda process. The method for recycling the waste clear liquid comprises the following steps of: leading the waste clear liquid into a waste liquid tank; starting a compression device to ensure that negative pressure is formed in the waste liquid tank, and recycling according to a gas and liquid heat exchange principle to obtain distilled water; when water is evaporated to ensure the concentration of sodium chloride in the waste clear liquid is increased until sodium chloride precipitate is separated out, performing liquid-solid separation to obtain sodium chloride; and continuously pressurizing to compress the waste clear liquid to ensure that the concentration of calcium chloride in the waste clear liquid is increased until calcium chloride precipitate is separated out, performing solid-liquid separation to obtain calcium chloride. By the method, the chemical pollution of the waste clear liquid produced in the process for producing the sodium carbonate by the ammonia-soda process is eliminated, distillation waste liquid can be reformed into a chemical product with certain economic value, the negative pressure and pressurization principles are skillfully used, sodium chloride and calcium chloride in the waste clear liquid can be recycled, and distilled water can be extracted; and the method has the advantages of simplicity, low production cost, and high economic benefit.

Description

technical field [0001] The invention relates to the technical field of soda production, in particular to a recycling method and device for waste clear liquid produced by ammonia soda method to produce soda ash. Background technique [0002] The soda ash industry is one of the basic sectors of the chemical industry, known as the mother of industry, and occupies a very important position in the national economy. Soda ash production processes mainly include ammonia-soda process, combined soda process and trona production process. From a global perspective, the chemical synthesis soda process that is widely used and has a large production scale is the ammonia-soda process. Its process is mature and reliable, and its product quality is excellent. Moreover, the process does not need a supporting synthetic ammonia device, and has the advantages of short process route, normal temperature and pressure production, convenient process control, safe and reliable operation, etc. The output...

AI Technical Summary

Problems solved by technology

So far, the utilization rate of distillation waste liquid and waste residue is low, and it is generally treated by the method of external discharge. The waste dumping site is large, which not only wastes chemical substances, but also pollutes the environment. With the increase of environmental protection pressure, waste liquid treatment has been Seriously restricted the development of ammonia-soda soda ash industrial enterprises, especially the development of inland ammonia-soda enterprises

[0004] At present, the method of producing calcium chloride by using ammonia-alkali waste liquid is mainly based on shell and tube evaporator or membrane evaporator, and some even use open Containers or steamers are directly evaporated, and some use a large area of ​​land to re-dry the waste liquid. The tube-and-tube evaporator has a small heat transfer area and requires relatively high-pressure steam. The steam pressure used is generally above 0.6MPa. The process is relatively complicated, the floor area is large, the thermal efficiency and production efficiency are low, and the energy waste is serious. At the same time, the heating chamber of the evaporator is easy to foul. Therefore, it is often necessary to add spare equipment or add barium chloride to prevent scaling in the heating chamber of the evaporator. High production cost, difficult to guarantee product quality

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