Equipment and method for preparing anhydrous sodium sulfate

Abstract

The invention discloses equipment for preparing anhydrous sodium sulfate. The equipment is characterized by comprising a closed cycle membrane concentration system, a salting out system, a conveying pump and a normal temperature crystallization system which are sequentially connected; the closed cycle membrane concentration system is used for conducting concentration on inlet liquor containing sodium sulfate and discharging concentrated liquor containing supersaturated sodium sulfate, the salting out system is used for changing a sodium chloride-sodium sulfate-water ternary system in the concentrated liquor into an unstable system, the conveying pump is used for conveying the concentrated liquor discharged by the salting out system to the normal temperature crystallization system, and the normal temperature crystallization system is used for conducting normal temperature crystallization and centrifugation on the concentrated liquor conveyed by the conveying pump so as to obtain the anhydrous sodium sulfate. The invention further provides a method for preparing the anhydrous sodium sulfate. According to the method, the evaporation process is omitted, crystallization is conducted at a normal temperature, anhydrous sodium sulphate is obtained, phase change of water does not occur in the whole process, energy consumption is low in the production process, product quality is good, and the high-grade anhydrous sodium sulphate can be obtained.

Description

technical field [0001] The invention relates to equipment and a method for preparing anhydrous sodium sulfate, and is particularly suitable for the field of desulfating salt water after electrolysis in the chlor-alkali industry. Background technique [0002] The technology of preparing anhydrous sodium sulfate (being Yuanmingfen) all is to adopt the technology of crystallization evaporation at present, yet because the heat of vaporization of water is relatively large, the energy consumption of sodium sulfate adopts evaporation crystallization is relatively high. In addition, the equipment investment is relatively large, and in a high-concentration sodium chloride system, high-temperature heating requires higher requirements for the processing materials of the equipment used, a large initial investment of equipment, and a long period of cost recovery. Especially for the removal of sodium sulfate in high-concentration brine, the industry is more complicated. After concentratin...

AI Technical Summary

Problems solved by technology

[0002] At present, the process of preparing anhydrous sodium sulfate (ie, sodium sulfate) is to adopt the process of crystallization and evaporation. However, due to the relatively large heat of vaporization of water, the energy consumption of sodium sulfate by evaporation and crystallization is relatively high.

In addition, the equipment investment is also relatively large, and in a high-concentration sodium chloride system, high-temperature heating requires higher requirements for the processing materials of the equipment used, a large initial investment of equipment, and a long period of cost recovery

Especially for the removal of sodium sulfate in high-concentration brine, the industry is more complicated. After concentrating with membrane, the concentration of sodium sulfate is concentrated to 40-65g / l, and then the thenardite is precipitated by freezing method, but the precipitated thenardite has 10 crystal water If the temperature is higher than 33°C, thenardite will be dissolved by its own crystal water and become a solution, which is not easy to transport and store, especially in summer. This problem is more prominent. Since thenardite contains 10 crystal water, its use is relatively limited. Therefore, if you want to make a product, you must remove the crystallization water of Glauber’s salt through evaporation to make anhydrous sodium sulfate before you can sell it. However, the energy consumption and investment of these processes in the current market are relatively large.

Images