阅读说明：本技术 一种工业废盐熔融处理与精制的装置与方法 (Device and method for melting treatment and refining of industrial waste salt ) 是由 周海云 包健 吕良忠 鲍业闯 陈赛楠 王伟霞 杨振亚 李国平 赵笛 顾凰琳 于 2019-10-31 设计创作，主要内容包括：本发明公开了一种工业废盐熔融处理与精制的装置与方法,采用回转窑高温处理工业废盐,可高效去除盐中混杂的有机物,焚烧后废盐中仍存在一些不溶性碳质以及氮、磷、硫元素的无机盐,通过水溶过滤,去除盐水中的不溶性碳质,继而通过活性炭吸附去色,得到较纯净的饱和浓盐水；回转窑焚烧废气经洗涤冷却塔中的雾化器洗盐后送入二燃室焚烧,二燃室焚烧烟气进入主炉工艺处理达标后排放；与此同时,借助回收的余热锅炉蒸汽及洗涤塔出口烟气与饱和浓盐水进行间接换热,从而实现盐水蒸发结晶,制得精盐。本发明通过对主炉工艺中烟气废热回收利用,避免了能量浪费,获得了额外的能源效益；精制后所得废盐的氯化钠纯度可达97％以上。(The invention discloses a device and a method for melting treatment and refining of industrial waste salt, which adopt a rotary kiln to treat the industrial waste salt at high temperature, can efficiently remove organic matters mixed in the salt, still have some insoluble carbon and inorganic salts of nitrogen, phosphorus and sulfur elements in the waste salt after burning, remove the insoluble carbon in the brine through water-soluble filtration, and then remove color through activated carbon adsorption to obtain purer saturated strong brine; the rotary kiln incineration waste gas is subjected to salt washing by an atomizer in a washing cooling tower and then sent into a secondary combustion chamber for incineration, and the incineration flue gas in the secondary combustion chamber enters a main furnace for process treatment and is discharged after reaching the standard; meanwhile, indirect heat exchange is carried out between the recovered waste heat boiler steam and the outlet flue gas of the washing tower and the saturated strong brine, so that evaporation and crystallization of brine are realized, and refined salt is prepared. According to the invention, the waste heat of the flue gas in the main furnace process is recycled, so that energy waste is avoided, and additional energy benefits are obtained; the purity of the sodium chloride of the waste salt obtained after refining can reach more than 97 percent.)

1. A method for melting treatment and refining of industrial waste salt is characterized by comprising the following steps:

(1) feeding industrial waste salt to be treated into a rotary kiln for melting treatment at high temperature to remove organic matters, feeding the molten salt into a quenching tower for cooling crystallization, and separating to obtain crude salt;

(2) dissolving the crude salt obtained in the step (1) by using water, filtering insoluble carbon impurities, adsorbing and decoloring by using activated carbon, and removing calcium and magnesium impurities by using alkaline precipitation;

(3) and (3) exchanging heat of the high-concentration salt-containing solution obtained in the step (2) through the heat of the flue gas recovered from the quenching tower in the step (1), and evaporating and crystallizing to obtain refined salt.

2. The method for melting treatment and refining of industrial waste salt according to claim 1, wherein the molten waste gas generated by the quenching tower in the step (1) is subjected to salt washing by an atomizer of a washing and cooling tower and then sent to a secondary combustion chamber for incineration, and the incineration tail gas is sent to a flue gas main furnace process and is discharged after flue gas purification treatment and flue gas heat recovery.

3. The method for melting, treating and refining industrial waste salt according to claim 2, wherein the flue gas main furnace process comprises a waste heat boiler waste heat recovery system, a steam temperature and pressure reduction system, a cooling system, a dust removal system, a washing tower and an adsorption tower alkali washing process;

an SNCR denitration device is arranged in the waste heat recovery system of the waste heat boiler, after denitration flue gas sequentially enters a cooling system, a dedusting system and a washing tower, one part of flue gas is recovered and is used as a heat source for evaporative crystallization in the step (3), and the other part of flue gas and the flue gas after evaporative crystallization enter an adsorption tower for alkali washing, then enter a flue gas heater for heating, and finally are discharged through a chimney;

and (4) after high-temperature steam generated by the waste heat recovery system of the waste heat boiler passes through the steam temperature and pressure reduction system, taking one part of the high-temperature steam as a heat source for evaporation crystallization in the step (3), and taking the other part of the high-temperature steam as a heat source in the flue gas heater.

4. The method for melting treatment and refining of industrial waste salt according to claim 1, wherein the rotary kiln in the step (1) is provided with a head burner and a tail burner, the head burner and the tail burner are respectively a kiln head multi-component burner and a kiln tail auxiliary burner, the two burners are supplied with heat through natural gas, and the salt-containing wastewater generated by the quenching tower is returned to the kiln head multi-component burner and enters the rotary kiln for incineration treatment.

5. The method for melting treatment and refining of industrial waste salt according to claim 3, wherein the wastewater generated in the process flow is collected by a water collecting tank and used as process water for the cooling and washing procedures of a quench tower, a washing cooling tower, a washing tower and an adsorption tower, a part of the washing water is recycled, and the rest wastewater is collected in a sewage tank and enters a wastewater treatment system.

6. The method for melting treatment and refining of industrial waste salt according to claim 1, wherein in the step (1), the melting treatment temperature of the rotary kiln is 950-1100 ℃, and the retention time of the industrial waste salt to be treated is 30-90 min.

7. The method for melting treatment and refining of industrial waste salt according to claim 2, wherein the incineration temperature of the secondary combustion chamber is 1100-1150 ℃, and the retention time of the waste gas is more than 2 s.

8. The method for melting treatment and refining of industrial waste salt according to claim 3, wherein the heat source for evaporative crystallization in the step (3) is derived from high-temperature steam generated by a waste heat boiler and outlet flue gas of a washing tower, the temperature is controlled to be 80-160 ℃, and indirect contact heat exchange is adopted between the heat source gas and the high-concentration salt-containing solution.

9. The method as claimed in claim 3, wherein the SNCR denitration device is operated at 850-1050 deg.C, and the flue gas duct is made of acid-resistant material.

10. A device for melting treatment and refining of industrial waste salt is characterized by comprising a rotary kiln, a quench tower, a washing cooling tower, a slag conveyor, a heat exchange evaporator, a waste heat boiler, a washing tower, an adsorption tower and a flue gas heater;

the rotary kiln is provided with a head burner and a tail burner, namely a kiln head multi-component burner and a kiln tail auxiliary burner; the discharge hole of the rotary kiln is connected with a quench tower; the waste gas outlet of the quenching tower is connected with a washing cooling tower, the liquid outlet is connected with a kiln head multi-component burner, the slag dragging machine is arranged in the quenching tower, crude salt generated by cooling crystallization in the quenching tower is separated out and is dissolved in water again, and refined salt is prepared by crystallization through a filter, an activated carbon adsorption decoloring device, an alkali precipitation impurity removal ion device and a heat exchange evaporator which are connected in sequence;

the rear end of the washing cooling tower is sequentially connected with a secondary combustion chamber and a waste heat boiler, the rear end of a flue gas outlet of the waste heat boiler is sequentially connected with a cooling system, a dust removal system and a washing tower, and an SNCR (selective non catalytic reduction) denitration device is arranged in the waste heat boiler; the washing tower flue gas outlet is respectively connected with the adsorption tower and the heat exchange evaporator; a steam outlet of the waste heat boiler is connected with a temperature and pressure reducing system; the flue gas outlet of the adsorption tower is connected into the flue gas heater, and the flue gas outlet of the flue gas heater is connected with the chimney; the steam outlet of the temperature and pressure reducing system is respectively connected with the heat exchange evaporator and the flue gas heater; the flue gas outlet of the heat exchange evaporator is connected with the adsorption tower;

liquid outlets in the washing cooling tower and the slag conveyor are connected with a water collecting tank, and the water collecting tank is respectively connected with the quenching tower and the sewage tank; and waste liquid outlets of the washing tower and the adsorption tower are connected to a sewage tank.

Technical Field

The invention relates to the technical field of industrial waste salt treatment, in particular to a device and a method for melting treatment and refining of industrial waste salt.

Background

China is a large industrial country, and with industrial development, the demand of industrial salt is greatly increased, so that a large amount of industrial byproduct salt is generated in related industries. The waste salt has wide source, and relates to the industrial industries of pesticide, pharmacy, printing and dyeing, fine chemical engineering and the like. In 2015, the production of waste salt in chemical industry in China is about 300 million tons, wherein 50 million tons of pesticides, 50 million tons of polycarbon, 20 million tons of coal chemical industry, 40 million tons of dye, 40 million tons of resin and 30 million tons of rubber are produced, and the production of waste salt in other chemical industries is about 70 million tons. The waste salt slag has high yield, contains various toxic substances, has serious harm to the environment, has complex components and high treatment and disposal cost, and cannot properly dispose industrial waste salt by adopting the traditional incineration and landfill disposal modes. Thus, disposal of waste salts has become one of the problematic environmental problems.

The industrial waste salt is mainly high-salt-content wastewater generated in the process stages of chemical reaction, salting-out, color fixation treatment and the like under the acid and alkali conditions, and is subjected to desalination process treatment such as salt concentration, evaporation and the like to obtain the wastewater containing NaCl and Na₂SO₄、KCl、Na₂SO₃And mixtures of one or more salts and organic contaminants. The industrial waste salt mainly contains sodium chloride, and can be roughly classified according to the types of substances containedThe method is divided into two types of single waste salt and mixed salt. The industrial waste salt generally contains organic pollutants, so that the industrial waste salt has strong pungent smell, and impurity elements such as heavy metal ions, heteroatoms and the like can be entrained in the industrial waste salt, and the industrial waste salt belongs to toxic and harmful substances.

The high-temperature melting method is adopted to treat the industrial waste salt, so that organic matters can be efficiently and thoroughly removed, and the method becomes a new method for treating the waste salt. The treatment and disposal of industrial waste salt face several key scientific and technical problems: firstly, the temperature of molten salt at the outlet of the rotary kiln is high, and the salt is volatile under the condition of high-temperature ventilation, so that the salt is cooled, crystallized and separated out in a subsequent treatment unit, and even blocks subsequent treatment equipment and pipelines; secondly, the existing engineering application mostly adopts a rotary kiln incineration technology of single-side natural gas heat supply, so that the temperature in the kiln body is reduced in a gradient manner along with the increase of the length of the kiln, and the high-temperature treatment effect of waste salt in the kiln is influenced; thirdly, the crystallized salt after high-temperature melting treatment still cannot meet the requirement of direct resource utilization, and still belongs to mixed salt, and oxidized carbon impurities, N, P, S elements and a small amount of heavy metal impurities may be wrapped in the crystallized salt, so that the molten waste salt needs to be deeply purified to meet the requirement of resource utilization, and the problem of the heavy resource utilization of industrial waste salt is solved. Fourthly, in the purification and refining process of salt, the traditional MVR evaporator is used for evaporating and crystallizing the salt water, so that the investment of large equipment cost is needed, and the energy recovery of the system is not considered.

Disclosure of Invention

The invention aims to solve the technical problem that the industrial waste salt is treated by adopting a rotary kiln incineration technology of natural gas heat supply at two ends aiming at the defects of the prior art, so that the phenomenon that the temperature in the rotary kiln body is reduced in a gradient manner due to the increase of the kiln length is avoided; then immediately carrying out quenching treatment on the molten salt through a quenching tower at the tail of the kiln, and avoiding the defect of scaling and blockage of the salt in equipment and pipelines in the traditional method; the waste gas waste heat generated in the process of utilizing the detoxified industrial waste salt is used for evaporating, crystallizing and refining high-concentration saturated salt water, so that the investment of an MVR evaporator is reduced; in addition, in the process flow, the quenching saline water is returned to the rotary kiln for incineration disposal, so that the pressure for treating the saline wastewater is reduced. In the main furnace process, the SNCR denitration process is arranged in the waste heat boiler, the high temperature of the flue gas at the outlet of the secondary combustion chamber is fully utilized to create a denitration reaction environment, and a heat source required by flue gas denitration is not required to be additionally provided.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a method for melting treatment and refining industrial waste salt comprises the following steps:

(1) feeding industrial waste salt to be treated into a rotary kiln for melting treatment at high temperature to remove organic matters, feeding the molten salt into a quenching tower for cooling crystallization, and separating to obtain crude salt;

(2) dissolving the crude salt obtained in the step (1) by using water, filtering insoluble carbon impurities, adsorbing by using activated carbon to remove color, and removing calcium and magnesium impurities by using alkali precipitation;

(3) and (3) exchanging heat of the high-concentration salt-containing solution obtained in the step (2) through the heat of the flue gas recovered from the quenching tower in the step (1), and evaporating and crystallizing to obtain refined salt.

And (3) further, washing salt by an atomizer of the washing cooling tower and then sending the molten waste gas generated by the quenching tower in the step (1) into a secondary combustion chamber for incineration, sending the incineration tail gas into a flue gas main furnace process, and discharging the incineration tail gas after flue gas purification treatment and flue gas heat recovery.

Specifically, the flue gas main furnace process comprises a waste heat boiler waste heat recovery system, a steam temperature and pressure reduction system, a cooling system, a dust removal system, a washing tower and an adsorption tower alkali washing process;

an SNCR denitration device is arranged in the waste heat recovery system of the waste heat boiler, after denitration flue gas sequentially enters a cooling system, a dedusting system and a washing tower, one part of flue gas is recovered and is used as a heat source for evaporative crystallization in the step (3), and the other part of flue gas and the flue gas after evaporative crystallization enter an adsorption tower for alkali washing, then enter a flue gas heater for heating, and finally are discharged through a chimney;

and (4) after high-temperature steam generated by the waste heat recovery system of the waste heat boiler passes through the steam temperature and pressure reduction system, taking one part of the high-temperature steam as a heat source for evaporation crystallization in the step (3), and taking the other part of the high-temperature steam as a heat source in the flue gas heater.

Further, the rotary kiln in the step (1) is provided with a head burner and a tail burner, namely a kiln head multi-component burner and a kiln tail auxiliary burner, wherein the two burners are supplied with heat through natural gas, and the salt-containing wastewater generated by the quenching tower is returned to the kiln head multi-component burner and enters rotation for incineration treatment; the kiln body of the rotary kiln is coated with high-temperature resistant anticorrosive materials.

Furthermore, the waste water generated in the process flow of the invention is collected by a water collecting tank and used as process water for the cooling and washing procedures of a quench tower, a washing and cooling tower, a washing tower and an adsorption tower, a part of the washing water is recycled, and the rest waste water is collected in a sewage tank and enters an urban waste water treatment system.

Preferably, in the step (1), the melting treatment temperature of the rotary kiln is 950-1100 ℃, and the retention time of the industrial waste salt to be treated is 30-90 min.

Preferably, the burning temperature of the second combustion chamber is 1100-1150 ℃, and the residence time of the waste gas is more than 2 s.

Preferably, the heat source for evaporative crystallization in the step (3) is derived from high-temperature steam generated by a waste heat boiler and outlet flue gas of a washing tower, the temperature is controlled to be 80-160 ℃, and indirect contact heat exchange is adopted between heat source gas and high-concentration salt-containing solution.

Preferably, the working temperature range of the SNCR denitration device is 850-1050 ℃, and the flue gas conveying pipeline is made of acid-resistant materials.

Further, the invention also provides a device for melting treatment and refining of the industrial waste salt, which comprises a rotary kiln, a quench tower, a washing cooling tower, a slag dragging machine, a heat exchange evaporator, a waste heat boiler, a washing tower, an adsorption tower and a flue gas heater;

the rotary kiln is provided with a head burner and a tail burner, namely a kiln head multi-component burner and a kiln tail auxiliary burner; the discharge hole of the rotary kiln is connected with a quench tower; the waste gas outlet of the quenching tower is connected with a washing cooling tower, the liquid outlet is connected with a kiln head multi-component burner, the slag dragging machine is arranged in the quenching tower, crude salt generated by cooling crystallization in the quenching tower is separated out and is dissolved in water again, and refined salt is prepared by crystallization through a filter, an activated carbon adsorption decoloring device, an alkali precipitation impurity removal ion device and a heat exchange evaporator which are connected in sequence;

the rear end of the washing cooling tower is sequentially connected with a secondary combustion chamber and a waste heat boiler, the rear end of a flue gas outlet of the waste heat boiler is sequentially connected with a cooling system, a dust removal system and a washing tower, and an SNCR (selective non catalytic reduction) denitration device is arranged in the waste heat boiler; the washing tower flue gas outlet is respectively connected with the adsorption tower and the heat exchange evaporator; a steam outlet of the waste heat boiler is connected with a temperature and pressure reducing system; the flue gas outlet of the adsorption tower is connected into the flue gas heater, and the flue gas outlet of the flue gas heater is connected with the chimney; the steam outlet of the temperature and pressure reducing system is respectively connected with the heat exchange evaporator and the flue gas heater; the flue gas outlet of the heat exchange evaporator is connected with the adsorption tower;

liquid outlets in the washing cooling tower and the slag conveyor are connected with a water collecting tank, and the water collecting tank is respectively connected with the quenching tower and the sewage tank; and waste liquid outlets of the washing tower and the adsorption tower are connected to a sewage tank.

Furthermore, the kiln head and the kiln tail of the rotary kiln, the smoke outlet of the quench tower, the secondary combustion chamber, the smoke and steam outlet of the waste heat boiler, the SNCR denitration device, the air outlet of the cooling system, the air inlet of the dust removal system, the air inlet and the air outlet of the washing tower, the smoke heater and the brine heat exchange evaporation process are all provided with temperature control systems, automatic control is realized by programming, and the corresponding temperature control systems and automatic control programs are selected and installed by technicians in the field as required to achieve the purpose of automatically controlling the temperature, and do not serve as creative contribution of the invention.

Has the advantages that:

according to the invention, the industrial waste salt is treated at high temperature by adopting the rotary kiln, organic matters mixed in the salt can be removed efficiently, some insoluble carbon and inorganic salt forms of nitrogen, phosphorus and sulfur still exist in the waste salt after incineration, the insoluble carbon in the brine is removed through water-soluble filtration, and then the activated carbon is used for adsorption and decolorization to obtain pure saturated strong brine; the rotary kiln incineration waste gas is subjected to salt washing by an atomizer in a washing cooling tower and then sent into a secondary combustion chamber for incineration, and the incineration flue gas in the secondary combustion chamber enters a main furnace for process treatment and is discharged after reaching the standard; meanwhile, indirect heat exchange is carried out between the recovered waste heat boiler steam and the outlet flue gas of the washing tower and the saturated strong brine, so that evaporation and crystallization of brine are realized, and refined salt is prepared.

The invention has the advantages that the end two burners, namely the kiln head multi-component burner and the kiln tail auxiliary burner, are arranged in the rotary kiln, so that the temperature in the kiln is uniform, the phenomenon that the temperature in the kiln body is reduced in a gradient manner due to the increase of the length of the rotary kiln is avoided, the temperature environment for high-temperature treatment of the industrial waste salt is further strengthened, and the removal effect and the incineration efficiency of organic matters in the industrial waste salt are improved; the inner wall of the rotary kiln body is coated with high-temperature-resistant anticorrosive materials, so that the service life of the rotary kiln is prolonged. In addition, the rotary kiln molten salt is treated by a quenching tower at the tail of the kiln, so that the defect of scaling and blocking of the salt in equipment and pipelines in the traditional method is overcome.

In the main furnace process, waste heat recovery is carried out on the incineration flue gas of the secondary combustion chamber through a waste heat boiler, so that additional heat source value is created; the SNCR denitration process is arranged in the waste heat boiler, the high temperature of the flue gas at the outlet of the secondary combustion chamber is fully utilized to create a denitration reaction environment, and a heat source required by flue gas denitration does not need to be additionally provided; meanwhile, the waste heat of the flue gas at the outlet of the washing tower in the process flow and the recycled boiler steam are fully utilized to evaporate and crystallize the salt water, so that the heat waste is avoided, the equipment investment of using an MVR evaporator in the traditional evaporation process is reduced, and the industrial waste salt treatment cost is greatly reduced; meanwhile, the process water generated in the process flow is recycled, the requirement on clean water is reduced, and the generated high-salt-content wastewater is partially returned to the rotary kiln for incineration, so that the pressure of subsequent sewage treatment is reduced. The purity of the sodium chloride of the waste salt obtained after refining in the invention can reach more than 97 percent, and the waste salt can be used as subsequent sodium chloride industrial salt to realize resource utilization. In addition, a temperature control system and an automatic control system are arranged in the process, so that the safety production is guaranteed, and the processing efficiency is improved.

Drawings

The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic view of the apparatus and process of the present invention.

Detailed Description

The invention will be better understood from the following examples.

The structures, proportions, and dimensions shown in the drawings and described in the specification are for understanding and reading the present disclosure, and are not intended to limit the scope of the present disclosure, which is defined in the claims, and are not essential to the skilled in the art. In addition, the terms "upper", "lower", "front", "rear" and "middle" used in the present specification are for clarity of description, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the relative positions may be changed or adjusted without substantial technical changes.

The melting treatment and refining of industrial waste salt are carried out by adopting a device shown in figure 1, wherein the device comprises a rotary kiln, a quench tower, a washing cooling tower, a slag conveyor, a heat exchange evaporator, a waste heat boiler, a washing tower, an adsorption tower and a flue gas heater;

the rotary kiln is provided with a head burner and a tail burner, namely a kiln head multi-component burner and a kiln tail auxiliary burner; the discharge hole of the rotary kiln is connected with a quench tower; the waste gas outlet of the quenching tower is connected with a washing cooling tower, the liquid outlet is connected with a kiln head multi-component burner, the slag dragging machine is arranged in the quenching tower, crude salt generated by cooling crystallization in the quenching tower is separated out and is dissolved in water again, and refined salt is prepared by crystallization through a filter, an activated carbon adsorption decoloring device, an alkali precipitation impurity removal ion device and a heat exchange evaporator which are connected in sequence;

the rear end of the washing cooling tower is sequentially connected with a secondary combustion chamber and a waste heat boiler, the rear end of a flue gas outlet of the waste heat boiler is sequentially connected with a cooling system, a dust removal system and a washing tower, and an SNCR (selective non catalytic reduction) denitration device is arranged in the waste heat boiler; the washing tower flue gas outlet is respectively connected with the adsorption tower and the heat exchange evaporator; a steam outlet of the waste heat boiler is connected with a temperature and pressure reducing system; the flue gas outlet of the adsorption tower is connected into the flue gas heater, and the flue gas outlet of the flue gas heater is connected with the chimney; the steam outlet of the temperature and pressure reducing system is respectively connected with the heat exchange evaporator and the flue gas heater; the flue gas outlet of the heat exchange evaporator is connected with the adsorption tower;

liquid outlets in the washing cooling tower and the slag conveyor are connected with a water collecting tank, and the water collecting tank is respectively connected with the quenching tower and the sewage tank; and waste liquid outlets of the washing tower and the adsorption tower are connected to a sewage tank.

The melting treatment and refining process of the industrial waste salt comprises the following specific steps: industrial waste salt is sent into a rotary kiln, heat sources are provided through natural gas burners at two ends of the head and the tail of the rotary kiln to heat the waste salt to a molten state, then the molten salt enters a quench tower to be rapidly cooled and crystallized, and then the waste salt is separated and collected through a slag conveyor. The crude salt collected after incineration is redissolved in water, insoluble carbon impurities in the water are filtered, then color is removed through activated carbon adsorption, calcium and magnesium impurities are removed through alkaline precipitation, and finally, the saturated strong brine is evaporated and crystallized through the recovered smoke heat to prepare refined salt. In the process, the incineration waste gas discharged from the quench tower is subjected to salt washing by an atomizer in a washing cooling tower and then sent into a secondary combustion chamber for incineration, the incineration temperature of the secondary combustion chamber is controlled to be 1100-1150 ℃, the retention time of the waste gas is more than 2s, and the incineration tail gas of the secondary combustion chamber is sent into a flue gas main furnace process and is discharged after flue gas purification treatment and waste heat recovery.

In the main furnace process, the flue gas at the outlet of the secondary combustion chamber is exhausted into the atmosphere after sequentially passing through a waste heat boiler, an SNCR denitration process, a cooling system, a dust removal system, a washing tower, an adsorption tower and the like. The SNCR denitration process is arranged in the waste heat boiler, the working temperature range of SNCR denitration is controlled to be 850-1050 ℃, a denitration reaction environment is created by fully utilizing the high temperature of the flue gas at the outlet of the secondary combustion chamber, and a heat source required by flue gas denitration is not required to be additionally provided; the byproduct steam collected by the waste heat recovery system of the waste heat boiler is wide in application approach, the process is used for flue gas heating on one hand, and is applied to evaporative crystallization of salt water together with outlet flue gas of a washing tower on the other hand, and the rest can be used for thermal units such as a melting kettle, atomized steam and the like and is used for other purposes.

In addition, water (called process water) generated in the process flow is mainly used for cooling and washing sections of a quench tower, a washing cooling tower, a washing tower and an adsorption tower, a part of washing water treated in the sections is recycled, and the rest waste water is collected in a sewage tank and enters a municipal sewage treatment pipe network for treatment.

The method of the invention is used for carrying out rotary kiln high-temperature melting treatment and refining on waste salt of a pesticide enterprise, and evaluating the benefit of the invention by engineering actual condition and salt production detection and analysis and assisting with certain engineering prediction.

The engineering live steps are as follows:

firstly, waste salt incineration: sending industrial waste salt into a rotary kiln, heating the waste salt to a molten state by using a heat source provided by natural gas combustion, controlling the temperature of the rotary kiln to be 980 ℃, keeping the retention time of the waste salt to be 45min, rapidly cooling and crystallizing the molten salt after incineration treatment by a quenching tower, and separating and collecting the molten salt by a slag conveyor.

Waste salt refining: re-dissolving the crude salt collected after incineration in water, filtering out insoluble carbon impurities, then removing color through activated carbon adsorption, removing calcium and magnesium impurities through alkaline precipitation, and finally evaporating and crystallizing saturated strong brine through the recovered flue gas heat to prepare refined salt; wherein the flue gas temperature for the evaporative crystallization is 90 ℃.

Thirdly, flue gas incineration: washing salt from the waste gas discharged from the quench tower by an atomizer in a washing cooling tower, feeding the waste gas into a secondary combustion chamber for incineration, controlling the incineration temperature of the secondary combustion chamber to be 1120 ℃, keeping the retention time of the waste gas to be 3s, feeding the incineration tail gas of the secondary combustion chamber into a flue gas main furnace process, and discharging the waste gas after flue gas purification treatment and waste heat recovery; wherein the SNCR denitration working temperature is 900 ℃.

The results of examining the TOC and sodium chloride purity of the raw and refined salts are shown in table 1. Wherein the TOC of the salt is as follows: weighing 1g of salt, dissolving in 100 ml of water, ultrasonically dissolving (the original salt needs to be continuously diluted by a certain multiple), and detecting by using a multi N/C2100 s TOC tester of Germany Jena. And the purity of the sodium chloride is obtained by converting the concentration of chloride ions detected by ion chromatography.

According to detection data, the purity of sodium chloride in the refined waste salt can reach 97.60%, the removal rate of organic matters in the waste salt is as high as 99.66%, and the treatment effect is good.

In addition, according to the power estimation of MVR equipment, the power consumption is nearly 3000 KW.h every day according to eight hours a day, the evaporation crystallization of saturated saline water is realized through waste heat recycling, the energy is obviously saved, the treatment cost is reduced, and the method has positive significance in engineering production.

TABLE 1 TOC and purity comparison of raw and refined salts

The invention provides a device and a method for melting and refining industrial waste salt, and a method and a way for implementing the technical scheme are many, the above description is only a preferred embodiment of the invention, and it should be noted that, for a person skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the invention, and the improvements and decorations should be regarded as the protection scope of the invention. All the components not specified in the present embodiment can be realized by the prior art.