阅读说明：本技术 一种pta焚烧锅炉灰渣溶液分盐结晶工艺 (PTA incineration boiler ash solution salt separation crystallization process ) 是由 武彦芳 王国清 曹吉林 李楼 胡晓静 郭瑞亚 李宁 吴浪 唐少康 于 2021-01-19 设计创作，主要内容包括：本发明涉及一种PTA焚烧锅炉灰渣溶液分盐结晶工艺,属于蒸发结晶技术领域,将带有余热的PTA焚烧锅炉灰渣溶解为碳酸钠和溴化钠的近饱和溶液,所述溶液采用金属烧结过滤器除去金属及其它不溶物,得到的滤液采用蒸发结晶法分离得到一水碳酸钠晶体,母液采用置换法除去碳酸钠后再用蒸发结晶法分离得到溴化钠晶体。本发明采用蒸发结晶法分离回收PTA锅炉灰渣中碳酸钠和溴化钠,工艺流程简单,操作条件简便、稳定,便于工业化；本发明回收得到的高纯度碳酸钠和溴化钠能够满足工业级产品的质量要求,可直接回收套用或作为副产品出售,既达到了处理废渣废水的目的,满足了当前环保形势的要求,且能够变废为宝,实现了盐的资源化,提高了工厂的效益。(The invention relates to a PTA incineration boiler ash solution salt separation crystallization process, belonging to the technical field of evaporative crystallization, wherein PTA incineration boiler ash with waste heat is dissolved into a nearly saturated solution of sodium carbonate and sodium bromide, metal and other insoluble substances are removed from the solution by a metal sintering filter, the obtained filtrate is separated by an evaporative crystallization method to obtain sodium carbonate monohydrate crystals, and mother liquor is separated by an evaporative crystallization method after removing sodium carbonate by a displacement method to obtain sodium bromide crystals. The method adopts an evaporative crystallization method to separate and recover sodium carbonate and sodium bromide in the PTA boiler ash, has simple process flow, simple, convenient and stable operation conditions, and is convenient for industrialization; the high-purity sodium carbonate and sodium bromide obtained by recycling can meet the quality requirement of industrial-grade products, can be directly recycled and reused or sold as byproducts, not only achieves the aim of treating waste residues and waste water, but also meets the requirement of the current environment-friendly situation, can change waste into valuable, realizes the recycling of salt, and improves the benefit of factories.)

1. A PTA incineration boiler ash solution salt separation crystallization process is characterized in that: dissolving the PTA incineration boiler ash residue with waste heat into a nearly saturated solution of sodium carbonate and sodium bromide, removing metals and other insoluble substances from the solution by using a metal sintering filter, separating the obtained filtrate by using an evaporative crystallization method to obtain sodium carbonate monohydrate crystals, removing the sodium carbonate from the separated mother liquor by using a displacement method, and then separating by using the evaporative crystallization method to obtain the sodium bromide crystals.

2. The process of claim 1, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the method comprises the following steps:

dissolving and filtering PTA incineration boiler ash: dissolving PTA incineration boiler ash with waste heat in an ash dissolving tank (1) by adding water to obtain a nearly saturated solution of sodium carbonate and sodium bromide, removing metals and other insoluble substances from the solution by adopting a metal sintering filter (2), discharging the obtained filter residue into a filter residue storage tank (3), and feeding the filtrate into a sodium carbonate crystallization raw material tank (4);

B. sodium carbonate evaporation crystallization: conveying the filtrate in a sodium carbonate crystallization raw material tank (4) to a sodium carbonate evaporation crystallization system by using a feeding pump for evaporation crystallization and separation, wherein the evaporation concentration temperature is 85-122 ℃, the filtrate is concentrated to a state that the solid content precipitated in a saturated solution is 10-30%, and then the solid-liquid separation is carried out at 85-122 ℃ to obtain sodium carbonate monohydrate crystals and mother liquor, the mother liquor returns to the sodium carbonate evaporation crystallization system, mother liquor I with a certain flow rate is discharged in the crystallization process, the flow rate of the mother liquor I is determined according to the content of sodium bromide in the raw material and the proportion of sodium bromide in the liquid phase at the concentration end point, and the mother liquor I is discharged into a sodium carbonate mother liquor reaction tank (7;

C. replacement of mother liquor I after sodium carbonate evaporation crystallization: adding 20-47% HBr solution into the mother liquor I by an HBr dosing device (8) to control the pH of the mother liquor I to be 7-8, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain high-purity sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying the sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the evaporation concentration temperature is 85-122 ℃, and when the concentration is carried out until the solid content precipitated in the saturated solution is 10-30%, carrying out solid-liquid separation at 85-122 ℃ to obtain sodium bromide crystals and a mother liquor II, and allowing the mother liquor II to enter the sodium bromide crystallization system for continuous evaporation crystallization.

3. The process of salt-separating crystallization of PTA incineration boiler ash solution as claimed in claim 1 or 2, wherein: the PTA incineration boiler ash comprises the following components in percentage by weight: sodium carbonate: 75-94%, sodium bromide: 5-24% of metal and miscellaneous salt.

4. The process of claim 2, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the pH of the solution in the step A is 11-13, and the temperature of the feeding solution is 50-90 ℃.

5. The process of claim 2, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the sodium carbonate evaporative crystallization system comprises a sodium carbonate evaporative crystallizer (5) and a sodium carbonate centrifuge (6); the sodium bromide evaporative crystallization system comprises a sodium bromide evaporative crystallizer (9) and a sodium bromide centrifugal machine (10).

6. The process of claim 5, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the sodium carbonate evaporative crystallizer (5) comprises a sodium carbonate heating chamber and a sodium carbonate crystallizer; the sodium bromide evaporative crystallizer (9) comprises a sodium bromide heating chamber and a sodium bromide crystallizer.

7. The process of claim 6, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam.

8. The process of claim 6, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the sodium carbonate crystallizer is provided with a washing leg which can reversely wash crystals.

9. The process of claim 6, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the crystallizer is any one of a DP crystallizer, a DTB crystallizer, an OSlO crystallizer, a flash evaporation type crystallizer or the above crystallizer modification.

10. The process of claim 7, wherein the PTA incineration boiler ash solution is subjected to salt separation crystallization, and the process comprises the following steps: the secondary steam flashed in the sodium carbonate and sodium bromide evaporation crystallization process is singly used or shares a set of intercooling condensation system (11); the saturated steam exchanges heat with raw materials in a sodium carbonate heating chamber and a sodium bromide heating chamber shell pass, is mixed with condensate water of an indirect cooling condensing system (11), and then is sent to an ash dissolving tank (1) through a condensate water pump to dissolve PTA incineration boiler ash, and the other part of the condensate water is recycled.

Technical Field

The invention relates to a PTA incineration boiler ash solution salt separation crystallization process, and belongs to the technical field of evaporative crystallization.

Background

Purified Terephthalic Acid (PTA) is a main raw material for manufacturing polyester fibers, films and insulating paint, is mainly used for producing polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT) and the like, and can also be used as a dye intermediate. In recent years, the PTA yield in China is on a rapid growth trend year by year, but the waste residues and waste water brought along with the growth of the PTA yield bring huge pressure to the environment. As the main components in the incinerator ash are sodium carbonate and sodium bromide, reasonable energy recovery brings great economic value. Sodium carbonate is one of important chemical raw materials, and is widely applied to the fields of light industry and daily use chemicals, building materials, chemical industry, food industry, metallurgy, textile, petroleum, national defense, medicine and the like. Sodium bromide has important function in the photosensitive industry, the production of drug intermediates and the synthesis of dyes as brominating agents.

In chemical industry, a replacement method is often adopted, and hydrobromic acid is added into a mixed salt solution of sodium carbonate and sodium bromide to obtain single sodium bromide. When the content of sodium carbonate is high, a large amount of hydrobromic acid is consumed for converting the sodium carbonate into sodium bromide by adopting a displacement method, so that the economic cost is high, and the large-scale production is not facilitated. However, no prior art is available to completely separate the mixed salt of sodium carbonate and sodium bromide.

In view of the solubility characteristics of sodium carbonate and sodium bromide in the PTA incineration boiler ash, the salt separation crystallization is carried out by adopting an evaporative crystallization method, and the reasonable utilization of heat is realized by adding sufficient and reasonable design, so that the industrial-grade quality standard product can be produced with the minimum energy consumption.

Disclosure of Invention

The invention aims to provide a salt-separating crystallization process for a PTA incineration boiler ash solution, which can effectively recover sodium carbonate and sodium bromide in high-salt waste residues in the PTA industry at the lowest production cost.

In order to achieve the purpose, the invention adopts the technical scheme that:

a process for crystallizing the PTA incinerated boiler ash solution by separating its salt includes such steps as dissolving the PTA incinerated boiler ash with afterheat in a nearly saturated solution of sodium carbonate and sodium bromide, removing metal and other insoluble substances from said solution by sintered metal filter, separating the filtrate by evaporative crystallization to obtain sodium carbonate monohydrate crystal, removing sodium carbonate from the mother liquid by displacement method, and separating by evaporative crystallization to obtain sodium bromide crystal.

The technical scheme of the invention is further improved as follows: the method comprises the following steps:

A. dissolving and filtering PTA incineration boiler ash: dissolving the PTA incineration boiler ash with waste heat in an ash dissolving tank by adding water to obtain a nearly saturated solution of sodium carbonate and sodium bromide, removing metals and other insoluble substances from the solution by adopting a metal sintering filter, discharging the obtained filter residue into a filter residue storage tank, and feeding the filtrate into a sodium carbonate crystallization raw material tank;

B. sodium carbonate evaporation crystallization: conveying the filtrate in a sodium carbonate crystallization raw material tank to a sodium carbonate evaporation crystallization system by using a feeding pump for evaporation crystallization and separation, wherein the evaporation concentration temperature is 85-122 ℃, the filtrate is concentrated until the solid content precipitated in a saturated solution is 10-30%, and then the solid-liquid separation is carried out at 85-122 ℃ to obtain sodium carbonate monohydrate crystals and mother liquor, the mother liquor returns to the sodium carbonate evaporation crystallization system, mother liquor I with a certain flow rate is discharged in the crystallization process, the flow rate of the mother liquor I is determined according to the content of sodium bromide in the raw material and the proportion of sodium bromide in a liquid phase at the concentration end point, and the sodium carbonate in the mother liquor I is discharged into a mother liquor reaction tank;

C. replacement of mother liquor I after sodium carbonate evaporation crystallization: adding 20-47% HBr solution into the mother liquor I by an HBr dosing device to control the pH of the mother liquor I to be 7-8, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain high-purity sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying the sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the evaporation concentration temperature is 85-122 ℃, and when the concentration is carried out until the solid content precipitated in the saturated solution is 10-30%, carrying out solid-liquid separation at 85-122 ℃ to obtain sodium bromide crystals and a mother liquor II, and allowing the mother liquor II to enter the sodium bromide crystallization system for continuous evaporation crystallization.

The technical scheme of the invention is further improved as follows: the PTA incineration boiler ash comprises the following components in percentage by weight: sodium carbonate: 75-94%, sodium bromide: 5-24% of metal and miscellaneous salt.

The technical scheme of the invention is further improved as follows: the pH of the solution in the step A is 11-13, and the temperature of the feeding solution is 50-90 ℃.

The technical scheme of the invention is further improved as follows: the sodium carbonate evaporative crystallization system comprises a sodium carbonate evaporative crystallizer and a sodium carbonate centrifuge; the sodium bromide evaporative crystallization system comprises a sodium bromide evaporative crystallizer and a sodium bromide centrifugal machine.

The technical scheme of the invention is further improved as follows: the sodium carbonate evaporative crystallizer comprises a sodium carbonate heating chamber and a sodium carbonate crystallizer; the sodium bromide evaporation crystallizer comprises a sodium bromide heating chamber and a sodium bromide crystallizer.

The technical scheme of the invention is further improved as follows: the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam.

The technical scheme of the invention is further improved as follows: the sodium carbonate crystallizer is provided with a washing leg which can reversely wash crystals.

The technical scheme of the invention is further improved as follows: the crystallizer is any one of a DP crystallizer, a DTB crystallizer, an OSlO crystallizer, a flash evaporation type crystallizer or the above crystallizer modification.

The technical scheme of the invention is further improved as follows: the secondary steam of the flash evaporation in the sodium carbonate and sodium bromide evaporation crystallization process is singly used or shares a set of intercooling condensation system; the saturated steam exchanges heat with the raw materials in the shell pass of the sodium carbonate heating chamber and the sodium bromide heating chamber, is mixed with the condensed water of the indirect cooling condensation system, then is sent to the ash residue dissolving tank through a part of the condensed water pump to dissolve the PTA incineration boiler ash residue, and the other part of the condensed water is recycled.

Due to the adoption of the technical scheme, the invention has the following technical effects:

the invention adopts the evaporative crystallization method to separate and recover sodium carbonate and sodium bromide in the PTA boiler ash, has simple process flow and simple, convenient and stable operation conditions, and is convenient for realizing industrial production. The high-purity sodium carbonate and sodium bromide obtained by recycling by the method can meet the quality requirement of industrial-grade products, can be directly recycled and reused or sold as byproducts, not only achieves the aim of treating waste residues and waste water, meets the requirement of the current environment-friendly situation, but also can change waste into valuable, realizes the resource utilization of salt and improves the benefit of factories.

The invention is a near zero emission treatment method, secondary water generated in the treatment process can be continuously used for dissolving ash, and the cyclic utilization of water resources is realized. In the treatment process, salts in the mother liquor are continuously enriched and separated out, so that the maximum recovery of the salts is realized.

The method fully utilizes the solubility characteristics of sodium carbonate and sodium bromide, when filtrate enters a sodium carbonate evaporation crystallization process, the filtrate firstly enters a crystallization area of sodium carbonate monohydrate, and the crystallization of the sodium carbonate monohydrate is ensured by controlling the evaporation crystallization temperature and the evaporation end point concentration, while the sodium bromide does not reach a saturated state, so that the high-purity sodium carbonate monohydrate is obtained; adding hydrogen bromide to convert the residual sodium carbonate in the mother liquor into sodium bromide, and then carrying out evaporative crystallization on the sodium bromide by controlling the evaporative crystallization temperature and the evaporative end point concentration to obtain the high-purity sodium bromide.

The selection of the filtering equipment of the invention is based on the impurity components in the ash, and the ash contains metals such as Fe, Cr, Ni, Co, Mn and the like, is an important component of the catalyst for synthesizing PTA, and has higher recovery value, so the metal in the ash solution is intercepted by adopting a metal sintering filter for recovery treatment, and the production cost is reduced.

The invention selects the crystallizer which can be used for forced crystallization, can depend on forced flow generated by external power, has the circulating speed of 1.5-3m/s, is beneficial to preventing scaling in the process and is easy to process solution with higher concentration. The crystallizer is provided with a vertical washing leg, so that the crystals can be reversely washed, the separated crystals are ensured to contain less impurities, and the industrial quality standard is reached.

Drawings

FIG. 1 is a schematic process flow diagram of the present invention;

the device comprises an ash dissolving tank 1, an ash dissolving tank 2, a metal sintering filter 3, a filter residue storage tank 4, a sodium carbonate crystallization raw material tank 5, a sodium carbonate evaporative crystallizer 6, a sodium carbonate centrifuge 7, a sodium carbonate mother liquor reaction tank 8, an HBr dosing device 9, a sodium bromide evaporative crystallizer 10, a sodium bromide centrifuge 11 and an indirect condensing system.

Detailed Description

The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, which are illustrative of only some embodiments of the invention and are not limiting of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A PTA incineration boiler ash solution salt separation crystallization process is disclosed, wherein the PTA incineration boiler ash comprises the following components in percentage by weight: sodium carbonate: 75-94%, sodium bromide: 5-24% and the balance of metal and miscellaneous salts, as shown in figure 1, comprising the following steps:

A. dissolving and filtering PTA incineration boiler ash: dissolving PTA incineration boiler ash with waste heat in an ash dissolving tank 1 by adding desalted water to obtain a nearly saturated solution of sodium carbonate and sodium bromide, wherein the pH value of the solution is 11-13, the temperature is 50-90 ℃, a metal sintering filter 2 is adopted to remove metal and other insoluble substances, the obtained filter residue is discharged into a filter residue storage tank 3, and the filtrate enters a sodium carbonate crystallization raw material tank 4;

B. sodium carbonate evaporation crystallization: conveying the filtrate in a sodium carbonate crystallization raw material tank 4 to a sodium carbonate evaporation crystallization system by using a feeding pump for evaporation crystallization and separation, wherein the sodium carbonate evaporation crystallization system comprises a sodium carbonate evaporation crystallizer 5 and a sodium carbonate centrifuge 6, the sodium carbonate evaporation crystallizer 5 comprises a sodium carbonate heating chamber and a sodium carbonate crystallizer, circulation between the sodium carbonate heating chamber and the sodium carbonate crystallizer is realized by an axial flow pump, the evaporation concentration temperature is 85-122 ℃, the sodium carbonate evaporation crystallizer is concentrated until the content of precipitated solid in saturated solution is 10-30%, the sodium carbonate evaporation crystallizer enters the sodium carbonate centrifuge 6 through a discharging pump for solid-liquid separation at 85-122 ℃ to obtain sodium carbonate monohydrate crystals and mother liquor, the sodium carbonate monohydrate crystallizer is provided with an elutriation leg capable of reversely washing the crystals, and the high-purity sodium carbonate monohydrate crystals obtained by centrifugation are returned to PTA production or sold as byproducts, the centrifugal mother liquor returns to the sodium carbonate crystallization evaporator 5; in the crystallization process, the flow of discharged mother liquor I is determined according to the content of NaBr in the raw materials and the proportion of NaBr in a liquid phase at the concentration end point, so that the purity of sodium carbonate crystallization is improved, and the mother liquor I enters a sodium carbonate mother liquor reaction tank 7.

C. Replacement of mother liquor I after sodium carbonate evaporation crystallization: adding 20-47% HBr solution into the mother liquor I by an HBr dosing device 8, controlling the pH value to be 7-8, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain high-purity sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying a sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the sodium bromide evaporation crystallization system comprises a sodium bromide evaporation crystallizer 9 and a sodium bromide centrifugal machine 10, the sodium bromide evaporation crystallizer 9 comprises a sodium bromide heating chamber and a sodium bromide crystallizer, circulation between the sodium bromide heating chamber and the sodium bromide crystallizer is realized through an axial flow pump, the evaporation concentration temperature is 85-122 ℃, the sodium bromide evaporation crystallization system enters the sodium bromide centrifugal machine 10 through a discharge pump when the evaporation concentration temperature is 85-122 ℃ until the solid content separated out from a saturated solution is 10-30%, the sodium bromide evaporation crystallization system performs solid-liquid separation at 85-122 ℃ to obtain sodium bromide crystals and mother liquor, and the mother liquor enters the sodium bromide crystallization system for continuous evaporation crystallization.

The crystallizer is any one of a DP crystallizer, a DTB crystallizer, an OSlO crystallizer, a flash evaporation type crystallizer or the modification of the above crystallizer, can be used for a crystallizer used for forced crystallization, can depend on forced flow generated by external power, has the circulating speed of 1.5-3m/s, is beneficial to preventing scaling in the process, and is easy to treat solution with higher concentration degree.

As shown in fig. 1, the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam, and the saturated steam exchanges heat with the raw materials in the shell pass of the heating chamber; and the secondary steam flashed by the sodium carbonate crystallizer and the sodium bromide crystallizer enters an indirect cooling condensation system 11. After the saturated steam condensate water and the secondary steam condensate water are mixed, one part of the mixed condensate water is sent to the ash dissolving tank 1 through the condensate water pump to dissolve PTA incineration boiler ash, and the other part of the condensate water is recycled.

The temperature of circulating water used by the indirect condensing system 11 is 25-30 ℃, and circulating water backwater is directly discharged through a circulating water backwater pipeline after the circulating water enters the indirect condensing system 11 for heat exchange.

Example 1

A PTA incineration boiler ash solution salt separation crystallization process is disclosed, wherein the mass of the PTA incineration boiler ash is 1360Kg/h, and the weight percentages of the components are as follows: sodium carbonate: 94%, sodium bromide: 5 percent, and the balance of metal and miscellaneous salt, as shown in figure 1, comprises the following steps:

A. dissolving and filtering PTA incineration boiler ash: dissolving PTA incineration boiler ash with waste heat in an ash dissolving tank 1 by adding desalted water to obtain a solution containing 27.07% of sodium carbonate and 1.44% of sodium bromide, wherein the pH value of the solution is about 12, the temperature is 50 ℃, removing metals and other insoluble substances by using a metal sintering filter 2, discharging obtained filter residue into a filter residue storage tank 3, and feeding filtrate into a sodium carbonate crystallization raw material tank 4;

B. sodium carbonate evaporation crystallization: the filtrate in the sodium carbonate crystallization raw material tank 4 is conveyed to a sodium carbonate evaporation crystallization system by a feeding pump for evaporation crystallization and separation, the sodium carbonate evaporative crystallization system comprises a sodium carbonate evaporative crystallizer 5 and a sodium carbonate centrifuge 6, wherein the sodium carbonate evaporative crystallizer 5 comprises a sodium carbonate heating chamber and a sodium carbonate crystallizer, realizing circulation between a sodium carbonate heating chamber and a sodium carbonate crystallizer by an axial flow pump, wherein the evaporation concentration temperature is 85 ℃, when the concentration is carried out until the content of precipitated solids in saturated solution is 30 percent, the concentrated solution enters a sodium carbonate centrifuge 6 through a discharge pump for solid-liquid separation to obtain sodium carbonate monohydrate crystals and mother liquor, the sodium carbonate crystallizer is provided with an elutriation leg which can reversely wash crystals, 1510kg/h of high-purity sodium carbonate monohydrate crystals obtained by centrifugation are returned to PTA production for use or sold as a byproduct, and the centrifugal mother liquor is returned to the sodium carbonate evaporative crystallizer 5; discharging about 128Kg/h of mother liquor I in the crystallization process to improve the purity of sodium carbonate crystals, wherein the mother liquor I enters a sodium carbonate mother liquor reaction tank 7.

C. Replacement of mother liquor I after sodium carbonate evaporation crystallization: adding 10Kg/h of HBr solution with the content of 20% into the mother liquor I by an HBr dosing device 8, controlling the pH value to be about 7.5, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain 138Kg/h of sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying a sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the sodium bromide evaporation crystallization system comprises a sodium bromide evaporation crystallizer 9 and a sodium bromide centrifugal machine 10, the sodium bromide evaporation crystallizer 9 comprises a sodium bromide heating chamber and a sodium bromide crystallizer, circulation between the sodium bromide heating chamber and the sodium bromide crystallizer is realized through an axial flow pump, the evaporation concentration temperature is about 85 ℃, when the concentration is about 25% of the precipitated solid content in the saturated solution, the concentrated solution enters the sodium bromide centrifugal machine 10 through a discharge pump for solid-liquid separation, a sodium bromide crystal of about 70kg/h and a mother solution II are obtained, and the mother solution II enters the sodium bromide evaporation crystallizer 9 for continuous evaporation crystallization.

As shown in fig. 1, the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam, and the saturated steam exchanges heat with the raw materials in the shell pass of the heating chamber; and the secondary steam flashed by the sodium carbonate crystallizer and the sodium bromide crystallizer enters an indirect cooling condensation system 11. After the saturated steam condensate water and the secondary steam condensate water are mixed, one part of the mixed condensate water is sent to the ash dissolving tank 1 through the condensate water pump to dissolve PTA incineration boiler ash, and the other part of the condensate water is recycled.

Example 2

A process for salt separation and crystallization of PTA incineration boiler ash solution is disclosed, wherein the mass of the PTA incineration boiler ash is about 1240Kg/h, and the weight percentages of the components are as follows: sodium carbonate: 88%, sodium bromide: 11 percent, and the balance of metal and miscellaneous salts, as shown in figure 1, comprises the following steps:

A. dissolving and filtering PTA incineration boiler ash: dissolving the PTA incineration boiler ash with waste heat in an ash dissolving tank 1 by adding desalted water to obtain a solution containing about 25.20% of sodium carbonate and about 3.20% of sodium bromide, wherein the pH value of the solution is about 12, the temperature is about 60 ℃, removing metals and other insoluble substances by using a metal sintering filter 2, discharging the obtained filter residue into a filter residue storage tank 3, and feeding the filtrate into a sodium carbonate crystallization raw material tank 4;

B. sodium carbonate evaporation crystallization: conveying the filtrate in a sodium carbonate crystallization raw material tank 4 to a sodium carbonate evaporation crystallization system by using a feeding pump for evaporation crystallization and separation, wherein the sodium carbonate evaporation crystallization system comprises a sodium carbonate evaporation crystallizer 5 and a sodium carbonate centrifuge 6, the evaporation concentration temperature is about 95 ℃, circulation between a sodium carbonate heating chamber and the sodium carbonate crystallizer is realized by using an axial flow pump, when the concentration is carried out until the content of separated solids in saturated solution is about 20%, the concentrated solution enters a sodium carbonate centrifuge 7 through a discharging pump for solid-liquid separation to obtain sodium carbonate monohydrate crystals and a mother solution, the sodium carbonate crystallizer is provided with an elutriation leg capable of carrying out reverse washing on the crystals, the high-purity sodium carbonate monohydrate crystals obtained by centrifugation are returned to PTA production or sold as a byproduct, and the centrifugal mother solution is returned to the sodium carbonate evaporation crystallizer 5; and discharging 263Kg/h of mother liquor I during the crystallization process to improve the purity of sodium carbonate crystals, wherein the mother liquor I enters a sodium carbonate mother liquor reaction tank 7.

C. Replacement of mother liquor I after sodium carbonate evaporation crystallization: adding 9.3Kg/h of 47% HBr solution into the mother liquor I by an HBr dosing device 8, controlling the pH value to be about 7.5, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain about 283Kg/h of sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying a sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the sodium bromide evaporation crystallization system comprises a sodium bromide evaporation crystallizer 9 and a sodium bromide centrifugal machine 10, the evaporation concentration temperature is 95 ℃, circulation between a sodium bromide heating chamber and the sodium bromide crystallizer is realized through an axial flow pump, when the concentration is carried out until the content of precipitated solids in a saturated solution is about 25%, a concentrated solution enters a sodium bromide centrifugal machine 12 through a discharge pump for solid-liquid separation, so that about 145Kg/h of sodium bromide crystals and a mother solution are obtained, and the mother solution enters the sodium bromide evaporation crystallizer 9 for continuous evaporation crystallization.

As shown in fig. 1, the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam, and the saturated steam exchanges heat with the raw materials in the shell pass of the heating chamber; and the secondary steam flashed by the sodium carbonate crystallizer and the sodium bromide crystallizer enters an indirect cooling condensation system 11. After the saturated steam condensate water and the secondary steam condensate water are mixed, one part of the mixed condensate water is sent to the ash dissolving tank 1 through the condensate water pump to dissolve PTA incineration boiler ash, and the other part of the condensate water is recycled.

Example 3

A salt-separating crystallization process of PTA (pure terephthalic acid) incineration boiler ash solution is disclosed, wherein the mass of the PTA incineration boiler ash is about 1348Kg/h, and the weight percentages of the components are as follows: sodium carbonate: 81%, sodium bromide: 18 percent, and the balance of metal and miscellaneous salts, as shown in figure 1, comprises the following steps:

A. dissolving and filtering PTA incineration boiler ash: dissolving PTA incineration boiler ash with waste heat in an ash dissolving tank 1 by adding desalted water to obtain a solution containing 23.20% of sodium carbonate and 5.23% of sodium bromide, wherein the pH value of the solution is about 12, the temperature is 70 ℃, removing metals and other insoluble substances by using a metal sintering filter 2, discharging obtained filter residue into a filter residue storage tank 3, and feeding filtrate into a sodium carbonate crystallization raw material tank 4;

B. sodium carbonate evaporation crystallization: conveying the filtrate in a sodium carbonate crystallization raw material tank 4 to a sodium carbonate evaporation crystallization system by using a feeding pump for evaporation crystallization and separation, wherein the sodium carbonate evaporation crystallization system comprises a sodium carbonate evaporation crystallizer 5 and a sodium carbonate centrifuge 6, the evaporation concentration temperature is about 95 ℃, circulation between a sodium carbonate heating chamber and the sodium carbonate crystallizer is realized by an axial flow pump, solid is separated out after concentration until the saturated solution is concentrated, when the content is 30%, the concentrated solution enters the sodium carbonate centrifuge 6 through a discharging pump for solid-liquid separation to obtain sodium carbonate monohydrate crystals and a mother solution, the sodium carbonate crystallizer is provided with an elutriation leg capable of reversely washing the crystals, the high-purity sodium carbonate monohydrate crystals obtained by centrifugation are about 1281kg/h and return to PTA production for use or sold as a byproduct, and the centrifugal mother solution returns to the sodium carbonate evaporation crystallizer 5; about 470Kg/h of mother liquor I is discharged in the crystallization process to improve the purity of sodium carbonate crystals, and the mother liquor I enters a sodium carbonate mother liquor reaction tank 7.

C. Replacement of mother liquor I after sodium carbonate evaporation crystallization: adding about 15Kg/h of 47% HBr solution into the mother liquor I by an HBr dosing device 8, controlling the pH value to be about 7.5, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain about 485Kg/h of sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying a sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the sodium bromide evaporation crystallization system comprises a sodium bromide evaporation crystallizer 9 and a sodium bromide centrifugal machine 10, the evaporation concentration temperature is about 95 ℃, circulation between a sodium bromide heating chamber and the sodium bromide crystallizer is realized through an axial flow pump, when the concentration is carried out until the content of precipitated solids in a saturated solution is 25%, a concentrated solution enters the sodium bromide centrifugal machine 10 through a discharge pump for solid-liquid separation, sodium bromide crystals of about 257kg/h and a mother solution are obtained, and the mother solution enters the sodium bromide evaporation crystallizer 9 for continuous evaporation crystallization.

As shown in fig. 1, the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam, and the saturated steam exchanges heat with the raw materials in the shell pass of the heating chamber; and the secondary steam flashed by the sodium carbonate crystallizer and the sodium bromide crystallizer enters an indirect cooling condensation system 11. After the saturated steam condensate water and the secondary steam condensate water are mixed, one part of the mixed condensate water is sent to the ash dissolving tank 1 through the condensate water pump to dissolve PTA incineration boiler ash, and the other part of the condensate water is recycled.

Example 4

A process for crystallizing PTA incineration boiler ash solution through salt separation, wherein the mass of the PTA incineration boiler ash is about 1360Kg/h, and the weight percentages of the components are as follows: sodium carbonate: 75%, sodium bromide: 24 percent, and the balance of metal and miscellaneous salts, as shown in figure 1, comprises the following steps:

A. dissolving and filtering PTA incineration boiler ash: dissolving the PTA incineration boiler ash with waste heat in an ash dissolving tank 1 by adding desalted water to obtain a solution containing 21.52% of sodium carbonate and 6.85% of sodium bromide, wherein the pH value of the solution is about 12, the temperature is about 90 ℃, removing metal and other insoluble substances by using a metal sintering filter 2, discharging the obtained filter residue into a filter residue storage tank 3, and feeding the filtrate into a sodium carbonate crystallization raw material tank 4;

B. sodium carbonate evaporation crystallization: conveying the filtrate in a sodium carbonate crystallization raw material tank 4 to a sodium carbonate evaporation crystallization system by using a feeding pump for evaporation crystallization and separation, wherein the sodium carbonate evaporation crystallization system comprises a sodium carbonate evaporation crystallizer 5 and a sodium carbonate centrifuge 6, the evaporation concentration temperature is about 110 ℃, circulation between a sodium carbonate heating chamber and the sodium carbonate crystallizer is realized by an axial flow pump, the sodium carbonate evaporation crystallization system is concentrated to a saturated solution to separate out solids, when the content is about 25%, the concentrated solution enters the sodium carbonate centrifuge 6 through a discharge pump for solid-liquid separation to obtain sodium carbonate monohydrate crystals and a mother liquor, the sodium carbonate crystallizer is provided with an elutriation leg capable of reversely washing the crystals, the high-purity sodium carbonate monohydrate crystals obtained by centrifugation are about 1186kg/h and return to PTA production or are sold as byproducts, and the centrifugal mother liquor returns to the sodium carbonate evaporation crystallizer 5; about 637Kg/h of mother liquor I is discharged during the crystallization process to improve the purity of sodium carbonate crystals, and the mother liquor I enters a sodium carbonate mother liquor reaction tank 7.

C. Replacement of mother liquor I after sodium carbonate evaporation crystallization: adding about 49Kg/h of HBr solution with the content of 20% into the mother liquor I by an HBr dosing device 8, controlling the pH value to be about 7.5, and converting the residual sodium carbonate in the mother liquor I into sodium bromide to obtain about 686Kg/h of sodium bromide solution;

D. sodium bromide evaporative crystallization: conveying a sodium bromide solution to a sodium bromide evaporation crystallization system for evaporation crystallization and separation, wherein the sodium bromide evaporation crystallization system comprises a sodium bromide evaporation crystallizer 9 and a sodium bromide centrifugal machine 10, the evaporation concentration temperature is 110 ℃, circulation between a sodium bromide heating chamber and the sodium bromide crystallizer is realized through an axial flow pump, when the concentration is carried out until the content of precipitated solids in a saturated solution is 30%, a concentrated solution enters the sodium bromide centrifugal machine 10 through a discharge pump for solid-liquid separation, so that a sodium bromide crystal of about 351kg/h and a mother solution are obtained, and the mother solution enters the sodium bromide evaporation crystallizer 9 for continuous evaporation crystallization.

As shown in fig. 1, the heat sources of the sodium carbonate heating chamber and the sodium bromide heating chamber are saturated steam, and the saturated steam exchanges heat with the raw materials in the shell pass of the heating chamber; and the secondary steam flashed by the sodium carbonate crystallizer and the sodium bromide crystallizer enters an indirect cooling condensation system 11. After the saturated steam condensate water and the secondary steam condensate water are mixed, one part of the mixed condensate water is sent to the ash dissolving tank 1 through the condensate water pump to dissolve PTA incineration boiler ash, and the other part of the condensate water is recycled.

The sodium carbonate crystal and the sodium bromide crystal which are prepared by separation by the process are dried and then are subjected to performance detection, and the detection results are respectively shown in tables 1 and 2.

TABLE 1 detection of sodium carbonate product Properties

Note: the sodium carbonate is obtained by converting sodium carbonate monohydrate into sodium carbonate in percentage by mass.

TABLE 2 sodium bromide product Performance test

The data show that the sodium carbonate product and the sodium bromide product obtained by the method respectively meet the performance requirements of industrial sodium carbonate and industrial sodium bromide, and can be directly sold as industrial products.