CN-121974514-A - Comprehensive treatment and recycling system for sodium carbonate production waste liquid

CN121974514ACN 121974514 ACN121974514 ACN 121974514ACN-121974514-A

Abstract

The invention discloses a comprehensive treatment and recycling system of sodium carbonate production waste liquid, which relates to the technical field of water treatment and waste liquid resource utilization and comprises the steps of pretreating the waste liquid to obtain salt-containing liquid, obtaining deliquescence characteristic data through a relative humidity step test, and constructing a risk index by combining sensitive hetero ion concentration; regulating mother liquor release ratio according to risk index to inhibit impurity enrichment, correcting in-phase seed crystal dosage to make directional hydration crystallization, acclimating the separated wet crystal under the condition of specific humidity, judging qualification according to temperature rise distribution and hot spot area, re-dissolving unqualified product, and reusing condensed water to production system. The invention can effectively inhibit local deliquescence and crusting risks caused by impurity ion enrichment in closed cycle, and improve the quality of waste liquid recycling products and the running stability of a system.

Inventors

ZHAO XIANGHAI
FU GUANGHUI

Assignees

江苏德邦兴华化工科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260128

Claims (8)

1. A comprehensive treatment and recycling system for sodium carbonate production waste liquid is characterized by comprising: the waste liquid pretreatment module is used for pretreating the waste liquid of soda production to obtain salt-containing liquid; The risk index module is used for carrying out relative humidity step test on the salt-containing liquid and the calcium chloride solid to obtain deliquescence starting relative humidity, deliquescence ending relative humidity and maximum temperature rise, and calculating a risk index by combining with the predetermined sensitive hetero ion concentration; the mother liquor regulating and controlling module is used for calculating the mother liquor release proportion according to the risk index, taking the mother liquor with corresponding flow as release flow and removing, and enabling the residual mother liquor to enter a circulation loop; The crystallization control module is used for evaporating and concentrating the mother solution entering the circulation loop, adding in-phase seed crystals into the crystallizer for directional hydration crystallization, and separating to obtain wet crystals after crystallization, wherein the adding amount of the seed crystals is corrected according to the risk index; The humidity domestication module is used for sending wet crystals into the domestication bin, adjusting the relative humidity of the domestication bin and judging whether the product is qualified or not according to the temperature rise distribution and the hot spot area occupation ratio in the domestication process; And the recycling module is used for recycling condensed water generated by evaporation and concentration to the production system and returning the product judged as unqualified to the evaporation and crystallization.
2. The comprehensive treatment and recycling system for waste liquid from soda ash production according to claim 1, wherein the pretreatment of the waste liquid from soda ash production for removing suspended matters to obtain salt-containing liquid meeting the limit value requirement comprises: Introducing the sodium carbonate production waste liquid into a homogenizing tank for homogenizing treatment, and performing clarification and solid-liquid separation of filtration to obtain filtered salt-containing liquid; and when the suspension concentration of the filtered salt-containing liquid is not higher than the preset suspension limit value, obtaining the salt-containing liquid.
3. The comprehensive treatment and recycling system for soda ash production waste liquid according to claim 1, wherein the relative humidity step test is performed on the salt-containing liquid and the calcium chloride solid, comprising: In the relative humidity step test process, the relative humidity is changed at a fixed speed and the temperature is measured, so that the minimum relative humidity meeting the preset temperature rise threshold is used as the deliquescence starting relative humidity, the relative humidity corresponding to the deliquescence wet spot expansion and stabilization is used as the deliquescence ending relative humidity, and the maximum temperature rise in the whole process is obtained.
4. The comprehensive treatment and recycling system for soda ash production waste liquid according to claim 3, wherein the calculation of risk index comprises: a sensitive impurity ion set is predetermined, and an allowable temperature rise upper limit and an allowable window width lower limit are obtained; Taking the ratio of the maximum temperature rise to the allowable temperature rise upper limit as a first ratio; Taking the difference value between the ending humidity and the starting humidity as the window width; taking the ratio of the lower limit of the allowable window width to the window width as a second ratio; summing the ratio of the concentration of each sensitive hetero ion in the sensitive hetero ion set to the corresponding reference concentration to obtain an enrichment item; And obtaining a risk index according to the product of the enrichment item and the first ratio and the second ratio.
5. The comprehensive treatment and recycling system for soda ash production waste liquid according to claim 1, wherein the calculation of the mother liquor release ratio according to the risk index comprises: Acquiring a basic release proportion and an upper limit of the release proportion; when the risk index does not exceed a preset reference value, taking the basic release proportion as a mother liquor release proportion; When the risk index exceeds a preset reference value, increasing the basic release proportion to obtain a mother liquor release proportion, wherein the increase is in direct proportion to the part of the risk index exceeding the preset reference value, and the mother liquor release proportion does not exceed the upper limit of the release proportion; and obtaining a release flow according to the product of the circulating mother liquor flow rate and the mother liquor release proportion in the mother liquor circulating loop.
6. The comprehensive treatment and recycling system for sodium carbonate production waste liquid according to claim 5, wherein the release flow is classified according to salinity and sensitive hetero-ion enrichment degree of the release flow, and the release flow is respectively guided to a salt using link or an outgoing disposal link.
7. The comprehensive treatment and recycling system for soda ash production waste liquid according to claim 1, characterized in that the method comprises the steps of: Obtaining a basic seed crystal mass ratio; When the risk index exceeds a preset reference value, increasing the basic seed crystal mass ratio to obtain a corrected seed crystal mass ratio, wherein the increment is in direct proportion to the part of the risk index exceeding the preset reference value; Obtaining the seed crystal adding amount according to the product of the corrected seed crystal mass ratio and the target crystal production mass; and (5) adding in-phase seed crystals into the crystallizer based on the seed crystal adding amount to carry out directional hydration crystallization.
8. The comprehensive treatment and recycling system for soda ash production waste liquid according to claim 1, wherein the relative humidity of the domestication bin is adjusted, and whether the product is qualified is judged according to the temperature rise distribution in the domestication process, comprising: Calculating an arithmetic average value of the deliquescence starting relative humidity and the deliquescence ending relative humidity, and setting the relative humidity of the domestication bin as the arithmetic average value; And when the temperature rise distribution and the hot spot area occupation ratio in the domestication process meet set conditions, judging that the product is qualified, wherein the set conditions are that the maximum temperature rise in the domestication bin is not higher than the allowable self-heating temperature rise upper limit and the proportion of the area occupation total area of the temperature rise in the domestication bin exceeding the temperature rise threshold value is not higher than the allowable hot spot area occupation ratio upper limit.

Description

Comprehensive treatment and recycling system for sodium carbonate production waste liquid Technical Field The invention relates to the technical field of water treatment and waste liquid resource utilization, in particular to a comprehensive treatment and recycling system for waste liquid in soda production. Background In the process of producing sodium carbonate, the distillation washing mother liquor of the processes of an ammonia-alkali combined alkali method and the like can generate high-salinity waste liquid in the circulating link, and the waste liquid contains sodium chloride salt calcium salt and various soluble impurity ions, has the characteristics of high conductivity and high ionic strength and is easy to scale, and is difficult to directly discharge after reaching the standard. In order to realize emission reduction and recycling utilization, the industry generally adopts a treatment route for recycling salt condensate water through solid-liquid separation, evaporation, concentration and crystallization, and uses calcium chloride as a byproduct recycling product, but in actual operation, the recycled calcium chloride solid is easy to generate local deliquescence wet spots, the wet spot area is accompanied by local temperature rise, the subsequent layered caking of an outer hard shell and an inner pulverization layer is formed when humidity changes, the caking is distributed in random plaque, meanwhile, the problems of the reduction of the circulation stability of a recycled water salinity rebound system and the like are also solved, and the quality conveyability of the calcium chloride product and the long-term operation of a waste liquid treatment recycling closed loop are seriously influenced. The prior art focuses on reducing the average salt content of the waste liquid to control evaporation multiple, or adopts conventional anti-scaling anti-moisture absorption measures, so that the core problem can not be solved pertinently, on one hand, the closed cycle can lead to gradual enrichment of trace impurity ions, so that the property of the mother liquid drifts along with the operation time, and the hydration phase path and micro-area of a crystallization product are not uniform, on the other hand, the conventional control scheme is mostly designed based on average water quality or average humidity, so that the key instability root cause of impurity ion accumulation and micro-area non-uniformity can not be identified, and the risk assessment index capable of being used in a closed loop is also lacking, and can lead to sudden caking and blocking of calcium chloride solid under the conventional storage and transportation conditions, fluctuation of granularity and fluidity of the product, and the rebound of salinity of reuse water are aggravated, and the operation stability of the whole waste liquid treatment and recycling system is further reduced. Disclosure of Invention The invention aims to solve the problems that in the comprehensive treatment and recycling process of sodium carbonate production waste liquid in the prior art, calcium chloride solid is easy to generate local deliquescence, temperature rise and caking, closed cycle causes sensitive hetero ion enrichment and mother liquor property drift, and hydration phase paths and micro-areas of a crystallization product are non-uniform, so that fluctuation of product quality and conveyability, rebound of recycle water salinity and insufficient system recycling stability are caused, and provides a comprehensive treatment and recycling system of sodium carbonate production waste liquid. In order to solve the problems existing in the prior art, the invention adopts the following technical scheme: a comprehensive treatment and recycling system for sodium carbonate production waste liquid comprises: the waste liquid pretreatment module is used for pretreating the waste liquid of soda production to obtain salt-containing liquid; The risk index module is used for carrying out relative humidity step test on the salt-containing liquid and the calcium chloride solid to obtain deliquescence starting relative humidity, deliquescence ending relative humidity and maximum temperature rise, and calculating a risk index by combining with the predetermined sensitive hetero ion concentration; the mother liquor regulating and controlling module is used for calculating the mother liquor release proportion according to the risk index, taking the mother liquor with corresponding flow as release flow and removing, and enabling the residual mother liquor to enter a circulation loop; The crystallization control module is used for evaporating and concentrating the mother solution entering the circulation loop, adding in-phase seed crystals into the crystallizer for directional hydration crystallization, and separating to obtain wet crystals after crystallization, wherein the adding amount of the seed crystals is corrected according to the risk index; The humidity dom