阅读说明：本技术 一种硫酸钠、氯化钠分盐方法 (Sodium sulfate and sodium chloride salt separation method ) 是由 顾逸 顾根生 徐建武 沈劲松 徐康明 章龙妹 刘晖 于 2021-01-14 设计创作，主要内容包括：本发明提供一种硫酸钠、氯化钠分盐方法,涉及盐类分离技术领域,包括如下步骤：S1、将含盐废水由进料泵先后输送至蒸馏水预热器和生蒸汽预热器,然后打入MVR强制循环部分；S2、进入液沫分离器经过旋流板除沫器液沫分离；S3、压缩后的蒸汽再打入蒸发室加热物料,然后出MVR蒸发结晶系统；S4、预热后的物料进入蒸发器后,和压缩后升高到108℃左右的二次蒸汽进行换热,本发明中通过蒸馏水预热器和生蒸汽预热器的设置,能够对含盐废水与蒸发结晶系统的蒸馏水和生蒸汽热至设定温度,液沫分离器的设置,能够对混合液体进行液沫分离,提高分盐的纯度,整个发明系统的操作可由计算机完成,具有原料适应性强、蒸发效率高、工艺环保绿色等优点。(The invention provides a method for separating salt from sodium sulfate and sodium chloride, which relates to the technical field of salt separation and comprises the following steps: s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater sequentially by a feed pump, and then pumping the salt-containing wastewater into an MVR forced circulation part; s2, entering a liquid foam separator for liquid foam separation through a cyclone plate foam remover; s3, pumping the compressed steam into an evaporation chamber to heat the material, and then discharging the material out of the MVR evaporation crystallization system; s4, after the preheated material enters an evaporator, the preheated material exchanges heat with secondary steam which is heated to about 108 ℃ after being compressed, through the arrangement of a distilled water preheater and a raw steam preheater, the salt-containing wastewater, the distilled water and the raw steam of an evaporative crystallization system can be heated to set temperatures, and through the arrangement of a liquid foam separator, liquid foam separation can be carried out on mixed liquid, so that the salt separation purity is improved.)

1. A sodium sulfate and sodium chloride salt separation method is characterized by comprising the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, feeding the 90 ℃ secondary steam from the top of the crystallization separator into a liquid foam separator, and feeding the steam into an MVR compression system after liquid foam separation of a cyclone plate demister;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate heat exchanger, and then discharging the steam out of the MVR evaporation crystallization system;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a thickener through a discharge pump, thickening the supersaturated concentrated solution, allowing the thickened supersaturated concentrated solution to enter a salt centrifuge, centrifuging to separate sodium sulfate salt, preheating the centrifugal mother solution, and returning the preheated centrifugal mother solution to the MVR evaporation crystallization system through a mother solution lifting pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

2. The method for separating the salt of sodium sulfate and sodium chloride according to claim 1, which is characterized in that: after the secondary vapor is compressed, the temperature may be raised to 108 c in said step s 2.

3. The method for separating the salt of sodium sulfate and sodium chloride according to claim 1, which is characterized in that: in the step s4, the heat balance of the MVR evaporative crystallization system is maintained by a compressor.

4. The method for separating the salt of sodium sulfate and sodium chloride according to claim 1, which is characterized in that: the temperature after heat exchange in the step S3 is 40-42 ℃.

5. The method for separating the salt of sodium sulfate and sodium chloride according to claim 1, which is characterized in that: the shell pass pressure of the evaporator is maintained by the opening of the automatic control regulating valve through the non-condensable gas.

6. The method for separating the salt of sodium sulfate and sodium chloride according to claim 1, which is characterized in that: the flash section is evacuated by a vacuum pump to maintain the system low pressure.

7. The method for separating the salt of sodium sulfate and sodium chloride according to claim 1, which is characterized in that: the evaporative crystallization system is controlled by a PLC, and all output and input signals and the operation of the system can be completed by a matched computer.

Technical Field

The invention relates to the technical field of salt separation, in particular to a salt separation method of sodium sulfate and sodium chloride.

Background

Sodium sulfate, inorganic compounds, white, odorless, bitter crystals or powders, and hygroscopic. The appearance is colorless, transparent, large crystal or granular small crystal. It is mainly used for making water glass, enamel, paper pulp, refrigerating mixture, detergent, drying agent, dye diluent, analytical chemical reagent, medicinal products, etc.

Sodium chloride, which is white crystal in appearance, is mainly in seawater and is the main component of common salt. Is easily soluble in water and glycerol, and is slightly soluble in ethanol and liquid ammonia; insoluble in concentrated hydrochloric acid. Slightly deliquescent in air. Has good stability, is industrially used for manufacturing soda ash, caustic soda and other chemical products, and can be used for smelting ores and can be used for seasoning in life.

In the salt-containing wastewater, a large amount of sodium sulfate and sodium chloride are often contained, but in the prior art, the extraction and separation of two substances are often complex, the extraction efficiency and purity are low, the extraction cost is high, and the method is not suitable for large-batch extraction.

Disclosure of Invention

The invention aims to provide a method for separating sodium sulfate and sodium chloride to solve the technical problems.

In order to solve the technical problems, the invention adopts the following technical scheme: a method for separating sodium sulfate and sodium chloride from salt comprises the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, feeding the 90 ℃ secondary steam from the top of the crystallization separator into a liquid foam separator, and feeding the steam into an MVR compression system after liquid foam separation of a cyclone plate demister;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate heat exchanger, and then discharging the steam out of the MVR evaporation crystallization system;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a thickener through a discharge pump, thickening the supersaturated concentrated solution, allowing the thickened supersaturated concentrated solution to enter a salt centrifuge, centrifuging to separate sodium sulfate salt, preheating the centrifugal mother solution, and returning the preheated centrifugal mother solution to the MVR evaporation crystallization system through a mother solution lifting pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

Preferably, in the step s2, the temperature may be increased to 108 ℃ after the secondary steam is compressed.

Preferably, the heat balance of the MVR evaporative crystallization system is maintained by a compressor in the step s 4.

Preferably, the temperature after the heat exchange in the step S3 is 40-42 ℃.

Preferably, the shell-side pressure of the evaporator is maintained by the opening of the automatic control regulating valve through the non-condensable gas.

Preferably, the flash section is evacuated by a vacuum pump to maintain the system low pressure.

Preferably, the evaporative crystallization system is controlled by a PLC, and all output and input signals and operation of the system can be completed by a matched computer.

The invention has the beneficial effects that:

according to the invention, through the arrangement of the distilled water preheater and the raw steam preheater, the salt-containing wastewater and the distilled water and the raw steam of the evaporative crystallization system can be directly driven into the MVR forced circulation part after being heated to a set temperature, the liquid-foam separator can be used for carrying out liquid-foam separation on the mixed liquid, the purity of separated salt is improved, the heat exchange is carried out between the distilled water plate heat exchanger and the stock solution, so that the MVR evaporative crystallization system reaches the thermal balance, the thickener can be used for thickening the supersaturated concentrated solution, solid particles in the suspension are concentrated, the preheated material enters the evaporator and then carries out heat exchange evaporation with the steam with the temperature raised after compression, the whole system reaches the thermal balance, the whole invention is clear, the operation of the system can be completed by a matched computer, the adaptability of the raw material is strong, the equipment is not easy to scale, the evaporation end point concentration is reasonable, the evaporation efficiency is high, low cost, environment-friendly process and the like.

Detailed Description

The present invention will be further described with reference to specific embodiments for the purpose of facilitating an understanding of technical means, characteristics of creation, objectives and functions realized by the present invention, but the following embodiments are only preferred embodiments of the present invention, and are not intended to be exhaustive. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative efforts belong to the protection scope of the present invention.

Specific embodiments of the present invention are described below.

Example 1

A method for separating sodium sulfate and sodium chloride from salt comprises the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, feeding the 90 ℃ secondary steam from the top of the crystallization separator into a liquid foam separator, and feeding the steam into an MVR compression system after liquid foam separation of a cyclone plate demister;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate type heat exchanger, and discharging the steam out of an MVR evaporation crystallization system when the heat exchange temperature reaches 35 ℃;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a thickener through a discharge pump, thickening the supersaturated concentrated solution, allowing the thickened supersaturated concentrated solution to enter a salt centrifuge, centrifuging to separate sodium sulfate salt, preheating the centrifugal mother solution, and returning the preheated centrifugal mother solution to the MVR evaporation crystallization system through a mother solution lifting pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

Example 2

A method for separating sodium sulfate and sodium chloride from salt comprises the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, feeding the 90 ℃ secondary steam from the top of the crystallization separator into a liquid foam separator, and feeding the steam into an MVR compression system after liquid foam separation of a cyclone plate demister;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate type heat exchanger, and discharging the steam out of the MVR evaporation crystallization system when the heat exchange temperature reaches 40 ℃;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a thickener through a discharge pump, thickening the supersaturated concentrated solution, allowing the thickened supersaturated concentrated solution to enter a salt centrifuge, centrifuging to separate sodium sulfate salt, preheating the centrifugal mother solution, and returning the preheated centrifugal mother solution to the MVR evaporation crystallization system through a mother solution lifting pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

Example 3

A method for separating sodium sulfate and sodium chloride from salt comprises the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, feeding the 90 ℃ secondary steam from the top of the crystallization separator into a liquid foam separator, and feeding the steam into an MVR compression system after liquid foam separation of a cyclone plate demister;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate type heat exchanger, and discharging the steam out of the MVR evaporation crystallization system when the heat exchange temperature reaches 45 ℃;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a thickener through a discharge pump, thickening the supersaturated concentrated solution, allowing the thickened supersaturated concentrated solution to enter a salt centrifuge, centrifuging to separate sodium sulfate salt, preheating the centrifugal mother solution, and returning the preheated centrifugal mother solution to the MVR evaporation crystallization system through a mother solution lifting pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

Example 4

A method for separating sodium sulfate and sodium chloride from salt comprises the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, directly feeding 90 ℃ secondary steam from the top of the crystallization separator into an MVR compression system;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate type heat exchanger, and discharging the steam out of the MVR evaporation crystallization system when the heat exchange temperature reaches 40 ℃;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a thickener through a discharge pump, thickening the supersaturated concentrated solution, allowing the thickened supersaturated concentrated solution to enter a salt centrifuge, centrifuging to separate sodium sulfate salt, preheating the centrifugal mother solution, and returning the preheated centrifugal mother solution to the MVR evaporation crystallization system through a mother solution lifting pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

Example 5

A method for separating sodium sulfate and sodium chloride from salt comprises the following steps:

s1, conveying the salt-containing wastewater to a distilled water preheater and a raw steam preheater by a feed pump, preheating the salt-containing wastewater, the distilled water and the raw steam of the evaporative crystallization system to a set temperature, directly pumping the salt-containing wastewater into an MVR forced circulation part, and continuing evaporative crystallization;

s2, feeding the 90 ℃ secondary steam from the top of the crystallization separator into a liquid foam separator, and feeding the steam into an MVR compression system after liquid foam separation of a cyclone plate demister;

s3, pumping the compressed steam into an evaporation chamber to heat materials, condensing the steam with the temperature of 100 ℃ into water and discharging the water by a distilled water pump in the process of heating the materials, exchanging heat with the stock solution through a distilled water plate type heat exchanger, and discharging the steam out of the MVR evaporation crystallization system when the heat exchange temperature reaches 40 ℃;

s4, after entering the evaporator, the preheated material exchanges heat with compressed secondary steam which is raised to about 108 ℃, the MVR evaporative crystallization system reaches thermal balance, and at the moment, only a small amount of external fresh steam is needed for heating;

s5, conveying the supersaturated concentrated solution evaporated by the forced circulation evaporator to a salt centrifuge through a discharge pump for centrifugal separation to obtain sodium sulfate salt, and preheating the centrifugal mother solution and returning the preheated centrifugal mother solution to the MVR evaporative crystallization system through a mother solution lift pump;

s6, pumping the MVR part of centrifugal mother liquor to a rear-end low-temperature part of forced circulation system by a mother liquor pump, and carrying out flash evaporation to crystallize sodium chloride;

s7, pumping part of mother liquor after flash evaporation crystallization into a front-end pipeline mixer, mixing the mother liquor with the raw materials, preheating the mixture to an evaporation temperature, and pumping the mixture into an MVR system to continue evaporation crystallization;

s8, after the preheated material enters the evaporator, the preheated material and the compressed steam with the increased temperature are subjected to heat exchange evaporation, and the whole system achieves heat balance.

Example analysis:

in the implementation of 1-3, the temperature after heat exchange in the step S3 is changed to 35 ℃, 40 ℃ and 45 ℃, and other processes are the same;

example 4 compared with example 2, in step s2 in example 2, the liquid foam is separated by the second steam passing through the liquid foam separator and the cyclone plate demister, while in example 4, the second steam directly enters the MVR compression system, and other processes and data are the same;

example 5 in comparison with example 2, in step s5 in example 2, the saturated concentrated solution was sent to a thickener for thickening, while in example 5, the saturated concentrated solution was directly sent to a salt centrifuge for centrifugation.

Experimental analysis:

the quality and purity of the sodium sulfate and sodium chloride separated in examples 1-5 were respectively determined, and the higher the quality, the higher the purity, the better the method.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.