CN112295385A - Tail gas purification and waste heat utilization method and device of hot blast stove for active carbon desorption - Google Patents

Tail gas purification and waste heat utilization method and device of hot blast stove for active carbon desorption Download PDF

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CN112295385A
CN112295385A CN201910692543.7A CN201910692543A CN112295385A CN 112295385 A CN112295385 A CN 112295385A CN 201910692543 A CN201910692543 A CN 201910692543A CN 112295385 A CN112295385 A CN 112295385A
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flue gas
gas pipeline
hot blast
blast stove
wastewater
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CN112295385B (en
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李勇
杨本涛
康建刚
魏进超
叶恒棣
刘昌齐
颜菲
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Hunan Zhongye Changtian Energy Conservation And Environmental Protection Technology Co ltd
Zhongye Changtian International Engineering Co Ltd
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Hunan Zhongye Changtian Energy Conservation And Environmental Protection Technology Co ltd
Zhongye Changtian International Engineering Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D47/00—Separating dispersed particles from gases, air or vapours by liquid as separating agent
    • B01D47/06—Spray cleaning
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00—Multistage treatment of water, waste water or sewage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2258/00—Sources of waste gases
    • B01D2258/02—Other waste gases
    • B01D2258/0283—Flue gases
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/10—Treatment of water, waste water, or sewage by heating by distillation or evaporation by direct contact with a particulate solid or with a fluid, as a heat transfer medium
    • C02F1/12—Spray evaporation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/16—Treatment of water, waste water, or sewage by heating by distillation or evaporation using waste heat from other processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5281—Installations for water purification using chemical agents
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment

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  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Organic Chemistry (AREA)
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  • Water Treatment By Sorption (AREA)

Abstract

A tail gas purification and waste heat utilization method of a hot blast stove for active carbon desorption comprises the following steps: 1) conveying the multi-pollutant flue gas to an adsorption tower through a raw flue gas pipeline; 2) the method comprises the following steps that hot blast stove tail gas generated during active carbon desorption enters a first flue gas pipeline, an atomizer and a dust remover are sequentially arranged on the first flue gas pipeline, waste water is atomized through the atomizer, the atomized waste water absorbs pollutants in the hot blast stove tail gas in the first flue gas pipeline, and the hot blast stove tail gas evaporates the waste water to form flue gas containing crystallized salt; dedusting the flue gas containing the crystallized salt to obtain crystallized salt and flue gas containing ammonia; 3) the first flue gas pipeline is merged to the original flue gas pipeline, the ammonia-containing flue gas in the first flue gas pipeline is mixed with the flue gas in the original flue gas pipeline and then enters the adsorption tower, and the mixture is adsorbed and purified by the active carbon in the adsorption tower and then is discharged. The invention carries out reasonable design aiming at the respective characteristics of the hot blast stove tail gas and the acidic washing wastewater, and realizes the high-efficiency utilization of the waste heat of the hot blast stove tail gas and the zero discharge of the wastewater.

Description

Tail gas purification and waste heat utilization method and device of hot blast stove for active carbon desorption
Technical Field
The invention relates to a method for purifying tail gas and utilizing waste heat, in particular to a method and a device for purifying the tail gas and utilizing the waste heat of a hot blast stove for desorbing active carbon, and belongs to the field of resource environment protection.
Background
The active carbon (active coke) in the flue gas desulfurization technology of the sintering and coking process of iron and steel enterprises needs to be heated to a certain temperature (about 430 ℃) in an analytical tower for analysis, and an acidic substance SO adsorbed by the active carbon is desorbed2And the released sulfur-rich gas can be directly used for preparing acid. In this process, the desorption column requires an external heat source.
In the prior art, hot blast stoves are generally used to use high-temperature flue gas (500 ℃) generated by burning blast furnace gas or coke oven gas as a heat source. After the high-temperature flue gas enters the desorption tower, the heating and regeneration of the activated carbon are realized through indirect heat exchange of the tubes. After the high-temperature flue gas passes through the desorption tower, the temperature can be reduced to about 280 ℃, namely the tail gas of the hot blast stove. Through detection, when the blast furnace gas or the coke oven gas is completely combusted, the tail gas of the hot blast furnace mainly consists of CO2、H2O、N2And a small amount of dust, and the dust is removed,when blast furnace gas or coke oven gas is not completely combusted, the tail gas of the hot blast furnace also contains a small amount of CH4Unsaturated hydrocarbons, CO, and the like.
Because the hot blast stove tail gas has certain temperature, and the active carbon flue gas purification system is comparatively sensitive to the temperature, therefore, hot blast stove tail gas is difficult to directly return the active carbon adsorption tower, and the present like engineering adopts chimney direct vent to handle, perhaps cools down the hot blast stove tail gas after, returns the active carbon adsorption tower and carries out purification treatment. According to the combination of the tail gas components of the hot blast stove, the tail gas pollutants of the hot blast stove are not effectively treated, the tail gas of the hot blast stove is not treated by the first method, and the particles in the tail gas of the hot blast stove can be only removed by the second method. And CO in the tail gas of the hot blast stove2Is a recognized greenhouse gas, CH4Unsaturated hydrocarbons, CO, etc. are precursors of haze and are therefore highly hazardous if not effectively handled.
In addition, a large amount of high-salinity wastewater, such as flue gas wet desulphurization and denitration wastewater, activated carbon desorption gas pickling and washing wastewater and the like, can be generated in steel smelting and other production processes, and the defects of high cost and long flow are caused by adopting the traditional step-by-step treatment technology. Aiming at wastewater treatment, the company develops a wastewater zero discharge technology through independent research and development. On this basis, considering that the hot blast stove tail gas generated during the active carbon analysis has higher temperature, and the hot blast stove tail gas is not effectively treated at present, and the problem of serious pollution exists in the treatment process, the application proposes that the hot blast stove tail gas generated during the active carbon analysis is used as the heat source to realize the zero discharge of washing wastewater, and the treatment of pollutants in the hot blast stove tail gas is realized simultaneously.
Disclosure of Invention
The invention provides a method and a device for tail gas purification and waste heat utilization of an air heating furnace for active carbon desorption, which take the heat waste caused by the tail gas emission of the air heating furnace and the environmental pollution into consideration, and take the heat requirement of evaporative crystallization of zero emission of waste water into consideration. The method adopts high temperature tail gas of hot blast stove as heat source for wastewater treatment, and pollutants such as CO in the tail gas after contact reaction of the tail gas of hot blast stove and wastewater2Can be under the high-temperature alkaline conditionLower is removed, CH4Unsaturated hydrocarbon, CO and the like can be subjected to catalytic oxidation reaction with metal precipitates under the high-temperature condition to be converted, so that the concentration of pollutants in the tail gas of the hot blast stove is greatly reduced, the energy recovery and utilization rate of the hot blast stove is improved, the pollutant emission of the hot blast stove is reduced, the waste gas amount is reduced, and zero emission of waste water is realized.
According to a first embodiment of the present invention, there is provided a method for purifying exhaust gas and utilizing waste heat of an air heating furnace for desorption of activated carbon, comprising:
a tail gas purification and waste heat utilization method of a hot blast stove for active carbon desorption comprises the following steps:
1) conveying multi-pollutant flue gas (such as sintering flue gas) to an adsorption tower through a raw flue gas pipeline;
2) when the activated carbon is analyzed, hot blast stove tail gas discharged from a heating section of an analysis tower enters a first flue gas pipeline, an atomizer and a dust remover are sequentially arranged on the first flue gas pipeline, wastewater is atomized through the atomizer, the atomized wastewater absorbs pollutants in the hot blast stove tail gas in the first flue gas pipeline, and the hot blast stove tail gas evaporates the wastewater to form flue gas containing crystallized salt; dedusting the flue gas containing the crystallized salt by a deduster to obtain crystallized salt and flue gas containing ammonia;
3) the tail end of the first flue gas pipeline is combined to the original flue gas pipeline, the ammonia-containing flue gas in the first flue gas pipeline is mixed with the flue gas in the original flue gas pipeline and then enters the adsorption tower, and the mixture is adsorbed and purified by the activated carbon in the adsorption tower and then is discharged.
In the invention, the wastewater in the step 2) is acidic washing wastewater. Preferably, the acidic washing wastewater is one or more of flue gas wet desulphurization and denitration wastewater, activated carbon SRG gas acid-making washing wastewater and membrane concentration wastewater.
Preferably, step 2) further comprises a wastewater treatment process before the wastewater atomization, specifically:
2a) acid filtration: performing acidic filtration on the wastewater through an acidic filtration device to obtain suspended matter precipitate and clear liquid;
2b) clear liquid flocculation: introducing the clear liquid obtained in the step 2a) into a flocculation precipitation device, and adding mixed alkali to flocculate and precipitate the clear liquid to obtain metal-containing sludge and salt-containing wastewater;
2c) adjusting alkali of wastewater: the salt-containing wastewater is mixed with alkali liquor and then enters an atomizer.
In the invention, in the step 1), a bypass flue gas pipeline is separated from the original flue gas pipeline. In the step 2), the bypass flue gas pipeline is combined to the first flue gas pipeline, and the connection position of the bypass flue gas pipeline and the first flue gas pipeline is positioned at the upstream of the atomizer. The bypass flue gas in the bypass flue gas pipeline is mixed with the tail gas of the hot blast stove in the first flue gas pipeline, and the waste water is atomized and then evaporated by using the mixed gas of the bypass flue gas in the first flue gas pipeline and the tail gas of the hot blast stove, and then enters the dust remover.
Preferably, the bypass flue gas pipeline is provided with a flow control valve for controlling the flow of flue gas entering the bypass flue gas pipeline from the raw flue gas pipeline.
In the invention, in step 2), a flow distribution device is arranged on the first flue gas pipeline and at the upstream of the connection position of the bypass flue gas pipeline and the first flue gas pipeline, and the tail gas of the hot blast stove enters the second flue gas pipeline through the flow distribution device. And 3) combining the second flue gas pipeline to the original flue gas pipeline, mixing the hot blast stove tail gas in the second flue gas pipeline with the flue gas in the original flue gas pipeline, then entering the adsorption tower, and adsorbing and purifying the mixture by using activated carbon in the adsorption tower and then discharging the mixture.
Preferably, a flow meter is arranged on the first flue gas pipeline and at the upstream of the flow distribution device, and is used for detecting the total flow of the tail gas of the hot blast stove in the first flue gas pipeline.
Preferably, cold air is introduced into the second flue gas pipeline to adjust the temperature of the tail gas of the hot blast stove in the second flue gas pipeline.
Preferably, the second flue gas pipeline is provided with a heat exchanger, and the hot blast stove tail gas in the second flue gas pipeline is mixed with the flue gas in the original flue gas pipeline after the temperature of the hot blast stove tail gas is controlled or regulated by the heat exchanger.
In the invention, a medium inlet of the heat exchanger is connected with a gas outlet of a cooling section of the desorption tower, and a heat exchange medium of the heat exchanger is cold air discharged from the cooling section of the desorption tower. Preferably, the cold air discharged from the cooling section of the desorption tower is converted into hot air after heat exchange with the tail gas of the hot blast stove in the second flue gas pipeline, and the hot air is conveyed to the waste heat utilization system.
In the present invention, the step of treating wastewater further comprises: 2d) metal recovery: recycling the metal-containing sludge obtained in the step 2b) through a metal recycling device.
Preferably, step 2b) further comprises an oxidation step; the method specifically comprises the following steps: oxidizing the clear liquid obtained in the step 2a) by an oxidation device, then introducing the oxidized clear liquid into a flocculation precipitation device, adding mixed alkali, and performing a weak alkali flocculation precipitation process to flocculate and precipitate the clear liquid to obtain the metal-containing sludge and the salt-containing wastewater.
Preferably, the oxidation treatment employs one or more of chemical oxidation, electrochemical oxidation, ultraviolet catalytic oxidation, air oxidation or chemical oxidation.
In the invention, the acidic washing wastewater is obtained by washing acidic flue gas by a wet method. Preferably, the acid flue gas is SRG gas, and the SRG gas is: the multi-pollutant flue gas is adsorbed by the active carbon in the adsorption tower, and the active carbon adsorbed with the pollutants is obtained by analyzing the active carbon by the analysis tower.
In the present invention, the suspension in step 2a) is precipitated as carbon powder. Preferably, the carbon powder is used for synthesizing large-particle activated carbon and returns to the adsorption tower for recycling through a carbon powder recycling process.
In the present invention, the wet washing is carried out using an acidic solution (e.g., a 0.5-10% strength dilute hydrochloric acid or dilute sulfuric acid or dilute phosphoric acid solution, having a strength of, for example, 1 wt%, 4 wt%, 5 wt%, or 7 wt%).
Preferably, the pH value of the acidic solution is 0 to 7, preferably 1 to 6, and more preferably 2 to 5. Preferably, the acidic solution is dilute sulfuric acid or dilute hydrochloric acid. In the wet washing process, the volume flow ratio of the SRG gas to the acidic solution is 1: 10-100, preferably 1: 20-80, and more preferably 1: 30-60.
In the present invention, in step 2a), the acidic filtration is specifically: and removing the suspended matters by utilizing the self gravity settling effect or the filter interception effect of the suspended matters, wherein the concentration of the suspended matters in the clear liquid after the acidic filtration is 0-100 mg/L, preferably 1-80 mg/L, and more preferably 2-50 mg/L.
In the invention, the acidic washing wastewater comprises one or more of suspended matters, metal ions, ammonia nitrogen, fluorine and chlorine and organic pollutants. Preferably, the metal ions are one or more of iron, copper, lead, calcium, zinc, cadmium, cobalt, nickel and aluminum.
In the present invention, in step 2b), the flocculation precipitation is specifically: adding mixed alkali into the clear liquid, adjusting the pH value to be alkalescent, and flocculating and precipitating the clear liquid with weak alkali to obtain metal-containing sludge and salt-containing wastewater. Preferably, the pH of the serum is adjusted to 7-10, preferably 7.2-9, more preferably 7.5-8.5. Preferably, the mixed base is a mixture of a lyotropic hydroxide and a lyotropic carbonate, or a mixture of a lyotropic hydroxide and a lyotropic bicarbonate. More preferably, the mixed alkali is a mixture of one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide and one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.
In the invention, in step 2), the atomization specifically comprises: the mixture of the clear liquid and the alkali liquor is dispersed into small fog drops through an atomizer, and the particle size of the small fog drops is 10-100 microns, preferably 15-80 microns, and more preferably 20-50 microns. Preferably, the alkali liquor is one or more of soluble hydroxide, soluble carbonate and soluble bicarbonate, and is preferably sodium hydroxide. Preferably, the addition amount of the alkali liquor is 0 to 0.5 times, preferably 0.01 to 0.25 times, and more preferably 0.05 to 0.1 times of the amount of the clear liquor.
Preferably, the dust removal treatment in step 2) adopts dry dust removal, preferably electric dust removal, cloth bag dust removal or cyclone dust removal, and preferably cloth bag dust removal. After the dust removal treatment, the crystallized salt is discharged from a solid outlet of the dust remover.
In the invention, the multi-pollutant flue gas is SO2And one or more of NOx, dust, VOCs and heavy metals.
In the invention, the multi-pollutant flue gas is derived from complex gas containing sulfur dioxide generated in the steel, electric, colored, petrochemical, chemical or building material industries. Preferably, the volume content of sulfur dioxide in the multi-pollutant flue gas is 0.01-1%, preferably 0.03-0.8%, and more preferably 0.05-0.5%. The temperature of the multi-pollutant flue gas is 100-200 ℃, preferably 120-180 ℃, and more preferably 130-160 ℃.
According to a second embodiment of the present invention, there is provided an exhaust gas purification and residual heat utilization device for an activated carbon desorption hot blast stove, comprising:
a tail gas purification and waste heat utilization device of a hot blast stove for active carbon desorption or a device for the method comprises an adsorption tower, a desorption tower, an atomizer, a dust remover and the hot blast stove. The original flue gas pipeline is connected with a flue gas inlet of the adsorption tower. The active carbon outlet of the adsorption tower is connected to the desorption tower. The gas inlet of the heating section of the analysis tower is connected with the hot blast stove, and a first flue gas pipeline led out from the gas outlet of the heating section of the analysis tower is connected to the original flue gas pipeline. Be equipped with atomizer and dust remover on the first flue gas pipeline in proper order, the atomizer sets up the upper reaches at the dust remover.
Preferably, the apparatus further comprises a drying tower. The drying tower is arranged on the first flue gas pipeline, and the atomizer is positioned at the top in the drying tower.
In the invention, the device also comprises an acid filtering device and a flocculation and precipitation device. The wastewater is conveyed to an inlet of an acidic filtering device, and a liquid outlet of the acidic filtering device is connected to a flocculation precipitation device. The liquid outlet of the flocculation precipitation device is connected to the atomizer.
Preferably, the apparatus further comprises an oxidation apparatus. The liquid outlet of the acid filtration device is connected to the oxidation device. The outlet of the oxidation device is connected to the flocculation precipitation device.
Preferably, the apparatus further comprises a metal recovery device. The solid outlet of the flocculation precipitation device is connected to a metal recovery device.
In the invention, a bypass flue gas pipeline which is branched from the original flue gas pipeline is connected to the first flue gas pipeline, and the position where the bypass flue gas pipeline is connected with the first flue gas pipeline is positioned at the upstream of the atomizer. Preferably, the bypass flue gas pipeline is provided with a flow control valve.
Preferably, the apparatus further comprises a flow distribution device disposed on the first flue gas duct, the flow distribution device being located upstream of the location where the bypass flue gas duct connects to the first flue gas duct. And a second flue gas pipeline led out from the flow distribution device is connected to the original flue gas pipeline. Preferably, the first flue gas pipeline is further provided with a flow meter, and the flow meter is positioned at the upstream of the flow distribution device.
Preferably, the second flue gas pipeline is connected with an air pipeline.
Preferably, the second flue gas pipeline is provided with a heat exchanger. Preferably, the cooling section gas outlet of the desorption tower is connected to the medium inlet of the heat exchanger via a gas transfer conduit.
In the invention, the device also comprises an SRG gas acid making system. An SRG gas outlet of the desorption tower is connected to a gas inlet of an SRG gas acid making system through a pipeline, and a wastewater outlet of the SRG gas acid making system is connected to an inlet of the acid filtering device through a wastewater conveying pipeline.
Preferably, the solids outlet of the acidic filtration device is connected to the activated carbon inlet of the adsorption column.
Preferably, the atomizer is provided with an alkali liquor inlet. The gas outlet of the dust remover is connected to the gas inlet of the adsorption tower.
In the invention, a flow meter and a flow distribution device are arranged at the front end of the first flue gas pipeline, the flow meter is used for detecting the total flow of the tail gas of the hot blast stove, and the flow distribution device is used for controlling the flow of the tail gas of the hot blast stove for treating wastewater and the flow of the tail gas directly entering the adsorption tower. Meanwhile, the bypass flue gas pipeline is provided with a flow control valve for controlling the flow of the flue gas entering the bypass flue gas pipeline from the original flue gas pipeline. When the flow of the tail gas of the hot blast stove is enough to treat the wastewater, the tail gas of the hot blast stove is contacted with the wastewater through a first flue gas pipeline and dries the wastewater, and the ammonia-containing flue gas obtained after the wastewater is evaporated and crystallized returns to the adsorption tower for purification treatment. When the flow of the tail gas of the hot blast stove is insufficient to treat the wastewater, the invention introduces part of the flue gas from the original flue gas pipeline into the bypass flue gas pipeline, and the flue gas of the bypass flue gas pipeline is mixed with the tail gas of the hot blast stove to dry the wastewater. When the exhaust amount of the tail gas of the hot blast stove is large, one part of the tail gas of the hot blast stove is used for wastewater treatment, and the other part of the tail gas of the hot blast stove enters the adsorption tower for purification treatment after heat exchange (heat exchange through a heat exchanger or cold air charging heat exchange). Under the condition of no waste water, the tail gas of the hot blast stove enters the second flue gas pipeline, is subjected to heat exchange to reach a proper temperature and then enters the adsorption tower for purification treatment.
According to the invention, the waste water is treated by using the tail gas of the hot blast stove, the waste water is subjected to alkali regulation treatment, the waste water is alkaline, pollutants such as dust, sulfur dioxide, fluoride, chloride and the like in the tail gas of the hot blast stove can be well absorbed, the pollutants in the tail gas are removed by treating the tail gas of the hot blast stove by using the waste water, the subsequent treatment and utilization are convenient, the damage of the dust to equipment such as a fan and the like is avoided, and meanwhile, the corrosion of the equipment by corrosive pollutants such as sulfur dioxide, fluoride, chloride and the.
In addition, the heat of the hot blast stove tail gas is used for evaporating the salt-containing wastewater, so that the salt in the wastewater is recycled, and the crystallized salt is obtained; the evaporated flue gas is changed into low-temperature flue gas, and the low-temperature flue gas is conveyed back to the original flue gas pipeline and is combined for purification treatment. In addition, the dust in the hot blast stove tail gas is utilized and used as a 'nucleus' in the evaporation and crystallization process of the salt-containing wastewater, so that the formation and the growth of crystallized salt are facilitated.
The technical principle of the process is as follows:
1) regulating and controlling tail gas of the high-temperature hot blast stove: because the crystallization recovery is usually bag-type dust removal, and the flue gas is returned to an active carbon flue gas purification system after spray drying, the two devices require that the flue gas temperature is not too high (less than 150 ℃). Under normal conditions, after being mixed with the flue gas introduced into the bypass flue gas pipeline from the original flue gas pipeline, the tail gas of the hot blast stove is contacted with the waste water to generate a cooling process, so that the temperature of the mixed flue gas is maintained at about 130 ℃. And under special circumstances, when no waste water is added, the flue gas of the hot blast stove is mixed with the flue gas of the bypass flue gas pipeline, obvious temperature drop can not occur, and the flue gas directly enters the two devices, so that the risk of overtemperature of the devices exists. Or when the exhaust amount of the tail gas of the hot blast stove is large, one part of the tail gas of the hot blast stove is used for treating wastewater, and the other part of the tail gas of the hot blast stove directly enters the adsorption tower through the second flue gas pipeline, so that the risk of overtemperature of the device also exists. Therefore, the flow meter and the flow distribution device are arranged at the front end of the first flue gas pipeline, and the flow required for the tail gas of the hot blast stove to enter the second flue gas pipeline and treat the waste water is determined and adjusted by detecting the flow of the waste water and combining the flow detection and the temperature characteristic analysis of the tail gas of the hot blast stove. When the abnormal conditions appear, when not having waste water to enter promptly, the hot-blast furnace flue gas gets into the heat exchanger, takes place heat exchange and then gets into the adsorption tower with the cold wind that the analytic tower produced (or the hot-blast furnace flue gas is handled through adding cold wind and then is carried to the adsorption tower), becomes hot-blast behind the cold wind heat transfer of analytic tower cooling zone, can carry to subsequent waste heat utilization device.
2) Acid precipitation/acid filtration: the nature that the suspended matter is easy to settle is utilized, and the suspended matter is filtered in the acidity by the gravity action and the acidic filter under the acidic condition. Carbon powder blockage is prevented by acidic filtration; the sulphur colloid is prevented from dissolving to form sodium thiosulphate and is decomposed on drying.
3) Flocculation and weak base precipitation: adjusting the wastewater to be alkalescent by adopting mixed alkali, wherein the pH value is less than or equal to 10; the metal cation will react with OH-、CO3 2-Or HCO3 -And the like, to form insoluble substances. And the precipitate is settled by adding a flocculating agent, so that the metal cations in the wastewater are removed, and the hardness of the wastewater is reduced. Heavy metals are precipitated to prevent the heavy metals from entering into crystallized salt, so that hazardous waste reduction is realized; meanwhile, the flocculation precipitation process adopts mixed alkali, so that a weak alkali environment is ensured, and ammonia volatilization and formation of a metal ammonia nitrogen complex are avoided.
4) Wastewater atomization and alkali adjustment: because the small liquid drops are easy to evaporate and dry, an air compressor is adopted to pressurize the waste water, and a high-speed centrifuge can also be adopted to atomize the waste water, the atomized particles are 10-100 mu m in particle size and then contact with hot waste gas, and because the particle size is small, the specific surface area is large, the mass transfer rate is high, the smoke heat can be quickly absorbed, the drying crystallization is realized, and the waste water drying rate is improved. The waste water is contacted with the hot waste gas in a way of arranging a separate drying tower or directly contacting in a flue of the hot waste gas. In addition, since the acidic washing wastewater generally contains a large amount of fluorine and chlorine, and the multi-pollutant flue gas (such as sintering flue gas) is weakly acidic, the wastewater needs to be adjusted to be alkaline in order to prevent hydrogen fluoride, hydrogen chloride and the like from being generated in the evaporation process of the wastewater. In addition, the wastewater is adjusted to be alkaline, so that the hardness of the wastewater is reduced, heavy metals are removed, the scaling of subsequent equipment is avoided, and the enrichment of heavy metal precipitates is realized.
5) Purifying flue gas pollutants of a hot blast stove: as the waste water needs to be adjusted to be alkaline before drying, the main pollutant CO in the flue gas of the hot blast stove2、SO2Will react with the alkali liquor and be removed. And the dust in the flue gas of the hot blast stove can be recovered through subsequent crystallization and is captured and removed by a dust remover. Furthermore, when the stove is not burning completely, CH in the flue gas4Unsaturated hydrocarbon, CO and the like can be converted by catalytic oxidation reaction with the metal precipitate under the high-temperature condition. The direct discharge of pollutants is avoided, and the environmental pollution is avoided.
6) And (3) crystal recovery: after the solution is evaporated, the solid mainly comprises sulfate, chloride and fluoride salt, is conventional inorganic salt, and can be recovered and removed by adopting a dust removal material with the filter diameter of less than 1 mu m. Commonly used dust removal materials include cloth bags, ceramics, metal membranes, and the like. After the suspended matters in the wastewater are removed by acidic filtration, the wastewater is changed into small-particle acidic fog drops by an atomizer, and the acidic fog drops are in contact with atomized alkali liquor quickly and have neutralization reaction to form alkaline liquid drops due to small particle size, large specific surface area and high mass transfer rate, and the dry crystallization is realized by quickly absorbing the heat of the flue gas. Because the heavy metal is removed by the weak base flocculation precipitation, the dried crystallized salt does not contain the heavy metal, the harmfulness of the crystallized salt is reduced, and the harmless treatment of fluorine and chlorine is realized.
7) Carbon powder recycling: a large amount of activated carbon powder is generated in the processes of activated carbon adsorption and desorption due to chemical loss and mechanical loss, a part of the carbon powder is separated after being screened with the desorbed activated carbon, and a part of the carbon powder enters the wastewater with the desorbed gas. Based on the particle size analysis and the surface hydrophobic characteristic of the carbon powder, the method filters the carbon powder in the wastewater under the acidic condition by reasonably designing the filtering condition, and mixes the carbon powder with the carbon powder under the sieve after drying, so that the carbon powder is granulated, combusted and buried, the resource utilization of the carbon powder is realized, and the operation cost is reduced.
8) Ammonia nitrogen clean recovery: after ammonia enters flue gas, part of ammonia and SO2The binding becomes ammonium sulfite and a portion reacts with NOx in an SCR reaction to form nitrogen. Because the ammonium sulfite is unstable, the generated ammonium sulfite is easily decomposed into ammonia gas and SO in the high-temperature regeneration process of the active carbon2. Since ammonia is very soluble in water, almost all ammonia enters the washing wastewater. According to the invention, heavy metals are precipitated by mixed alkali in weak alkali (7-9), so that ammonia gas escape and a metal ammonia nitrogen stable complex formed during heavy metal precipitation by high alkali can be effectively avoided, and clean recovery or treatment of ammonia nitrogen is realized.
In the invention, after wet washing, the generated acidic washing wastewater comprises carbon powder in a suspended state and a wastewater solution containing metal ions; the part of the acidic washing wastewater is subjected to acidic filtration to separate suspended matters (such as carbon powder) in the wastewater to obtain carbon powder, and the part of the carbon powder can be recycled through a carbon powder recycling process, for example, a re-granulation process is adopted to obtain large-particle activated carbon, and then the large-particle activated carbon is recycled to an adsorption tower. The wastewater after the suspended matter is separated contains metal ions (or metal salts) which are clear liquid; and (3) subjecting the clear liquid to a flocculation precipitation process, adding mixed alkali into the clear liquid to enable most heavy metal ions in the clear liquid to form precipitates, introducing the precipitates into the metal-containing sludge, and then recovering metals from the metal-containing sludge to obtain a pure metal recovered material which can be sold or used for other purposes. The salt-containing wastewater obtained after the flocculation and precipitation process is characterized in that an alkali solution is added into the salt-containing wastewater, after atomization, heat emitted by a flue gas conveying pipeline is used for drying, metal ions which are not precipitated in the flocculation and precipitation process are crystallized in the salt-containing wastewater after drying, and chloride ions, fluoride ions, sulfate ions and the like in the wastewater are dried by adding the alkali solution into the salt-containing wastewater to form a clear solution and heat emitted by an alkali solution mixture through the flue gas conveying pipeline, and water is volatilized to form crystallized salt. The volatile matter is pollution-free matter. The crystalline salt can be sold or used for other purposes, resulting in economic value. The crystal salt is sulfate, chloride or fluoride.
By adopting the method, after the multi-pollutant smoke is treated by the activated carbon, the activated carbon can be completely recycled. The sulfides in the contaminants are recovered as sulfur-containing by-products. Most of the metal ions can be recovered by the flocculation precipitation step and the metal recovery step, and the remaining chloride ions, fluoride ions, sulfate ions, and the like are converted into crystal salts. Therefore, the synergistic treatment of the multi-pollutant flue gas is really realized, the zero discharge of waste water is realized, the secondary pollution is not generated, and metal ions (or heavy metal ions) in the multi-pollutant flue gas are recovered. Changing waste into valuable, recycling, saving cost, recycling resources and protecting environment.
In the invention, the SRG gas refers to the enriched flue gas discharged after being analyzed by the desorption tower. The SRG gas (or SRG flue gas) has high temperature, high dust content and SO2High content, high water content, complex smoke impurity components and the like. In the art, SRG gas is also referred to simply as sulfur-rich gas; used for being conveyed to an acid making system for making acid.
According to the waste water amount to be treated, the amount of the tail gas of the hot blast stove and the flue gas in the bypass flue gas pipeline entering the drying tower is accurately controlled, so that the tail gas of the hot blast stove and the flue gas in the bypass flue gas pipeline can just treat the part of waste water. If the introduced flue gas into the drying tower is too little, the wastewater treatment is incomplete, and the significance of the invention is lost; if the flue gas that introduces the drying tower is too much, will make the flue gas in the bypass flue gas pipeline surplus, handle waste water and need not surplus flue gas, because the flue gas through the drying tower all needs to be handled through the dust remover, consequently, the flue gas that introduces the drying tower is too much will increase the work load of removing dust, and is also stricter to the requirement of dust remover, has increased the input cost. According to the invention, the amount of the flue gas introduced into the drying tower is accurately controlled, so that the part of the flue gas can just treat the wastewater to be treated, and the extra workload of dust removal is not increased.
In the invention, the heat quantity required by the wastewater treatment is calculated according to the wastewater quantity to be treated, the temperature of the wastewater, the temperature of the tail gas of the hot blast stove and the temperature required by the wastewater evaporation (the set temperature according to the process experience). The heat required by the wastewater treatment is provided by the tail gas of the hot blast stove, and the amount of the tail gas of the hot blast stove entering the drying tower can be accurately calculated according to the temperature of the tail gas of the hot blast stove; therefore, the flue gas volume entering the drying tower can just completely treat the wastewater through adjustment and control, and the surplus condition can not exist, so that the load of dust removal treatment can not be additionally increased. And if the tail gas of the hot blast stove is excessive, the excessive tail gas of the hot blast stove passes through a second flue gas pipeline, is subjected to temperature regulation and is then conveyed to the original flue gas pipeline. If the tail gas of the hot blast stove is not enough to treat the wastewater, the high-temperature flue gas with corresponding amount is supplemented through a bypass flue gas pipeline and is conveyed to a drying tower for treating the wastewater. In addition, through accurate control, the temperature of the flue gas entering the adsorption tower can be controlled within a temperature range suitable for activated carbon adsorption treatment.
In the invention, the tail gas of the hot blast stove refers to the part of gas discharged outside in the circulating gas of the heating sections of the hot blast stove and the desorption tower. And the gas heated by the hot blast stove is used as a heating medium for the heating section of the desorption tower, and the high-temperature heating medium is discharged from the heating medium outlet of the heating section after being conveyed to the heating section of the desorption tower for heat exchange and is conveyed back to the hot blast stove. However, in order to ensure the combustion efficiency in the hot blast stove, the oxygen content in the hot blast stove must be ensured, and a part of the medium after being conveyed back to the heat exchange of the hot blast stove needs to be discharged outside, and then new air is supplemented to the hot blast stove to ensure the oxygen content in the hot blast stove, so as to further ensure the combustion efficiency of the fuel in the hot blast stove. The part of flue gas discharged outside the hot blast stove is also generated by combustion of the hot blast stove, and the part of tail gas discharged outside the hot blast stove contains CO2、SO2And the pollutants are directly discharged to pollute the air; meanwhile, the tail gas of the hot blast stove has a high temperature of more than 200 ℃, and can not be directly conveyed to a raw flue gas pipeline to be treated by an activated carbon adsorption tower.
Generally, the volume of the tail gas of the hot blast stove is about 10% of the volume of the circulating gas of the heating section of the hot blast stove and the desorption tower. The invention fully utilizes the alkaline condition of the waste water to absorb pollutants in the tail gas of the hot blast stove; meanwhile, the high-temperature condition of the tail gas of the hot blast stove is utilized for evaporating the wastewater and recovering the crystallized salt, thereby achieving the purpose of treating the wastewater. In addition, the dust in the tail gas of the hot blast stove is utilized, and plays a role of 'nucleus' in the evaporation and crystallization process, so that the formation and the growth of crystals are facilitated; the treated tail gas of the hot blast stove can be conveyed to an activated carbon adsorption tower for subsequent purification treatment by utilizing the cooling effect of the wastewater. The technical scheme of the invention realizes the cooperative treatment of the tail gas and the wastewater of the hot blast stove.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention carries out reasonable design aiming at the respective characteristics of the hot blast stove tail gas and the acidic washing wastewater, and realizes the high-efficiency utilization of the waste heat of the hot blast stove tail gas and the zero discharge of the wastewater;
2. the tail gas of the hot blast stove of the desorption tower is subjected to waste heat utilization, the flue gas temperature is greatly reduced, the hot waste gas quantity is greatly reduced, and according to a gas state equation (pV ═ nRT), the total quantity of the waste gas discharged by sintering is effectively reduced, and the construction cost and the operation cost of a later dust removal, desulfurization and denitrification purification section are effectively reduced;
3. when the tail gas of the hot blast stove is contacted with the wastewater, pollutants such as dust, carbon dioxide and the like in the tail gas of the hot blast stove can react with substances in the wastewater to be cooperatively removed, for example, the carbon dioxide can be absorbed by alkali liquor, and the dust can be removed by cloth bag dust removal used in the method, so that the concentration of the pollutants in the flue gas can be reduced, and the environmental pollution is avoided;
4. the high-temperature flue gas of the hot blast stove is used as one of heat sources for wastewater treatment, and compared with the method that only the bypass medium-temperature hot waste gas separated from the original flue gas pipeline is used as the heat source, the method has the advantages of low investment of evaporation equipment, small occupied area, high heat utilization rate and reliable operation;
5. after the tail gas of the hot blast stove is introduced into the waste water treatment, the temperature of the bypass flue gas separated from the original flue gas pipeline can be effectively raised, so that the removal rate of sulfur dioxide and nitrogen oxide in the bypass flue gas can be increased in the waste water spraying process, and the load of a subsequent activated carbon flue gas purification system can be effectively reduced;
6. the method of the invention treats the acidic washing wastewater, and prevents carbon powder from being blocked by acidic filtration; preventing the sulfur colloid from dissolving to form sodium thiosulfate and decomposing during drying;
7. the acid filtered clear liquid is subjected to a flocculation precipitation process, so that heavy metals form heavy metal precipitates, the heavy metals are prevented from entering crystallized salt, and hazardous waste reduction is realized; meanwhile, mixed alkali is adopted in the flocculation precipitation process, so that a weak alkali environment is ensured, and ammonia volatilization and formation of a metal ammonia nitrogen complex are avoided;
8. the ammonia-containing wastewater in the flocculation precipitation process passes through an atomizer and is dried by using the waste heat of the flue gas in a flue; high-alkali atomization is adopted, which is beneficial to recycling ammonia gas; alkaline drying to prevent formation of high viscosity ammonium bisulfate and other by-products;
9. according to the invention, heavy metals are precipitated by mixed alkali in weak alkali (7-9), so that ammonia gas escape and a metal ammonia nitrogen stable complex formed during heavy metal precipitation by high alkali can be effectively avoided, and clean recovery or treatment of ammonia nitrogen is realized.
In the present application, desorption and desorption are the same concept. The hot blast stove off-gas and the hot blast stove flue gas are the same concept. "upstream" is set according to the direction of flue gas flow in the duct. The "top" is set according to the height direction of the apparatus or device.
Drawings
FIG. 1 is a process flow diagram of a method for purifying tail gas and utilizing waste heat of a hot blast stove for desorption of activated carbon according to the present invention;
FIG. 2 is a schematic structural diagram of a tail gas purification and waste heat utilization device of a hot blast stove for active carbon desorption according to the present invention;
FIG. 3 is a schematic structural diagram of a second device for tail gas purification and waste heat utilization of a hot blast stove for active carbon desorption according to the present invention;
FIG. 4 is a schematic structural diagram of the device for utilizing waste heat of tail gas of the hot blast stove and realizing zero discharge of waste water;
FIG. 5 is a schematic structural diagram of a second device for utilizing waste heat of tail gas and realizing zero discharge of waste water in the hot blast stove.
Reference numerals:
1: an adsorption tower; 2: a resolution tower; 201: a heating section; 202: a cooling section; 3: an atomizer; 4: a dust remover; 5: an acidic filtration unit; 6: a flocculation precipitation device; 7: a flow control valve; 8: a flow distribution device; 9: a flow meter; 10: a heat exchanger; 11: a metal recovery device; 12: an oxidation unit; 13: a hot blast stove; 14: an SRG gas acid making system; 15: a drying tower;
l0: an original flue gas pipeline; l1: a first flue gas duct; l2: a bypass flue gas duct; l3: a second flue gas duct; l4: an air duct; l5: a waste water conveying pipeline.
Detailed Description
According to a first embodiment of the present invention, there is provided a method for purifying exhaust gas and utilizing waste heat of an air heating furnace for desorption of activated carbon, comprising:
a tail gas purification and waste heat utilization method of a hot blast stove for active carbon desorption comprises the following steps:
1) the multi-pollutant flue gas is conveyed to the adsorption tower 1 through an original flue gas pipeline L0;
2) when the activated carbon is analyzed, tail gas of the hot blast stove discharged from a heating section 201 of an analysis tower 2 enters a first flue gas pipeline L1, an atomizer 3 and a dust remover 4 are sequentially arranged on the first flue gas pipeline L1, wastewater is atomized through the atomizer 3, the atomized wastewater absorbs pollutants in the tail gas of the hot blast stove in the first flue gas pipeline L1, and the tail gas of the hot blast stove evaporates the wastewater to form flue gas containing crystalline salt; the flue gas containing the crystallized salt is subjected to dust removal treatment by a dust remover 4 to obtain crystallized salt and flue gas containing ammonia;
3) the tail end of the first flue gas pipeline L1 is merged to the original flue gas pipeline L0, the flue gas containing ammonia in the first flue gas pipeline L1 is mixed with the flue gas in the original flue gas pipeline L0 and then enters the adsorption tower 1, and the flue gas is adsorbed and purified by the activated carbon in the adsorption tower 1 and then is discharged.
In the invention, the wastewater in the step 2) is acidic washing wastewater. Preferably, the acidic washing wastewater is one or more of flue gas wet desulphurization and denitration wastewater, activated carbon SRG gas acid-making washing wastewater and membrane concentration wastewater.
Preferably, step 2) further comprises a wastewater treatment process before the wastewater atomization, specifically:
2a) acid filtration: performing acidic filtration on the wastewater through an acidic filtration device 5 to obtain suspended substance precipitate and clear liquid;
2b) clear liquid flocculation: introducing the clear liquid obtained in the step 2a) into a flocculation precipitation device 6, adding mixed alkali to flocculate and precipitate the clear liquid, and obtaining metal-containing sludge and salt-containing wastewater;
2c) adjusting alkali of wastewater: the salt-containing wastewater is mixed with the alkali liquor and then enters the atomizer 3.
In the invention, in step 1), the raw flue gas pipeline L0 is divided into a bypass flue gas pipeline L2. In step 2), the bypass flue gas duct L2 merges into the first flue gas duct L1, and the connection point of the bypass flue gas duct L2 to the first flue gas duct L1 is located upstream of the atomizer 3. The bypass flue gas in the bypass flue gas pipeline L2 is mixed with the tail gas of the hot blast stove in the first flue gas pipeline L1, and the atomized waste water is evaporated by using the mixed gas of the bypass flue gas in the first flue gas pipeline L1 and the tail gas of the hot blast stove and then enters the dust remover 4.
Preferably, the bypass flue gas pipeline L2 is provided with a flow control valve 7 for controlling the flow of flue gas entering the bypass flue gas pipeline L2 from the raw flue gas pipeline L0.
In the invention, in step 2), a flow distribution device 8 is arranged on the first flue gas pipeline L1 and upstream of the connection position of the bypass flue gas pipeline L2 and the first flue gas pipeline L1, and the hot blast stove tail gas also enters the second flue gas pipeline L3 through the flow distribution device 8. In the step 3), the second flue gas pipeline L3 is merged into the original flue gas pipeline L0, and the hot blast stove tail gas in the second flue gas pipeline L3 is mixed with the flue gas in the original flue gas pipeline L0, enters the adsorption tower 1, and is adsorbed and purified by the activated carbon in the adsorption tower 1 and then is discharged.
Preferably, a flow meter 9 is disposed on the first flue gas pipe L1 and upstream of the flow distribution device 8, and is used for detecting the total flow of the exhaust gas of the hot blast stove in the first flue gas pipe L1.
Preferably, cold air is introduced into the second flue gas duct L3 to adjust the temperature of the hot blast stove tail gas in the second flue gas duct L3.
Preferably, the heat exchanger 10 is arranged on the second flue gas pipeline L3, and the tail gas of the hot blast stove in the second flue gas pipeline L3 is mixed with the flue gas in the original flue gas pipeline L0 after the temperature of the tail gas is controlled or regulated by the heat exchanger 10.
In the present invention, the medium inlet of the heat exchanger 10 is connected to the gas outlet of the cooling section 202 of the desorption tower 2, and the heat exchange medium of the heat exchanger 10 is the cold air discharged from the cooling section 202 of the desorption tower 2. Preferably, the cold air discharged from the cooling stage 202 of the desorption tower 2 is heat-exchanged with the hot blast furnace off gas in the second flue gas duct L3 to be changed into hot air, and is sent to the waste heat utilization system.
In the present invention, the step of treating wastewater further comprises: 2d) metal recovery: the metal-containing sludge obtained in step 2b) is recycled by means of a metal recycling device 11.
Preferably, step 2b) further comprises an oxidation step; the method specifically comprises the following steps: oxidizing the clear liquid obtained in the step 2a) by an oxidation device 12, then introducing the oxidized clear liquid into a flocculation precipitation device 6, adding mixed alkali, and performing a weak alkali flocculation precipitation process to flocculate and precipitate the clear liquid to obtain the metal-containing sludge and the salt-containing wastewater.
Preferably, the oxidation treatment employs one or more of chemical oxidation, electrochemical oxidation, ultraviolet catalytic oxidation, air oxidation or chemical oxidation.
In the invention, the acidic washing wastewater is obtained by washing acidic flue gas by a wet method. Preferably, the acid flue gas is SRG gas, and the SRG gas is: the multi-pollutant flue gas is adsorbed by the active carbon in the adsorption tower 1, and the active carbon adsorbed with the pollutants is resolved by the resolving tower 2 to obtain the multi-pollutant flue gas.
In the present invention, the suspension in step 2a) is precipitated as carbon powder. Preferably, the carbon powder is used for synthesizing large-particle activated carbon and is returned to the adsorption tower 1 for recycling through the carbon powder recycling process.
In the present invention, the wet scrubbing is carried out using an acidic solution (e.g., a 0.5-10% strength dilute hydrochloric acid or dilute sulfuric acid or dilute phosphoric acid solution; the strength is, for example, 1 wt%, 4 wt%, 5 wt%, or 7 wt%).
Preferably, the pH value of the acidic solution is 0 to 7, preferably 1 to 6, and more preferably 2 to 5. Preferably, the acidic solution is dilute sulfuric acid or dilute hydrochloric acid. In the wet washing process, the volume flow ratio of the SRG gas to the acidic solution is 1: 10-100, preferably 1: 20-80, and more preferably 1: 30-60.
In the present invention, in step 2a), the acidic filtration is specifically: and removing the suspended matters by utilizing the self gravity settling effect or the filter interception effect of the suspended matters, wherein the concentration of the suspended matters in the clear liquid after the acidic filtration is 0-100 mg/L, preferably 1-80 mg/L, and more preferably 2-50 mg/L.
In the invention, the acidic washing wastewater comprises one or more of suspended matters, metal ions, ammonia nitrogen, fluorine and chlorine and organic pollutants. Preferably, the metal ions are one or more of iron, copper, lead, calcium, zinc, cadmium, cobalt, nickel and aluminum.
In the present invention, in step 2b), the flocculation precipitation is specifically: adding mixed alkali into the clear liquid, adjusting the pH value to be alkalescent, and flocculating and precipitating the clear liquid with weak alkali to obtain metal-containing sludge and salt-containing wastewater. Preferably, the pH of the serum is adjusted to 7-10, preferably 7.2-9, more preferably 7.5-8.5. Preferably, the mixed base is a mixture of a lyotropic hydroxide and a lyotropic carbonate, or a mixture of a lyotropic hydroxide and a lyotropic bicarbonate. More preferably, the mixed alkali is a mixture of one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide and one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.
In the invention, in step 2), the atomization specifically comprises: the mixture of the clear liquid and the alkali liquor is dispersed into small fog drops through an atomizer 3, and the particle size of the small fog drops is 10-100 microns, preferably 15-80 microns, and more preferably 20-50 microns. Preferably, the alkali liquor is one or more of soluble hydroxide, soluble carbonate and soluble bicarbonate, and is preferably sodium hydroxide. Preferably, the addition amount of the alkali liquor is 0 to 0.5 times, preferably 0.01 to 0.25 times, and more preferably 0.05 to 0.1 times of the amount of the clear liquor.
Preferably, the dust removal treatment in step 2) adopts dry dust removal, preferably electric dust removal, cloth bag dust removal or cyclone dust removal, and preferably cloth bag dust removal. After the dust removal treatment, the crystallized salt is discharged from the solid outlet of the dust remover 4.
In the invention, the multi-pollutant flue gas is SO2And one or more of NOx, dust, VOCs and heavy metals.
In the invention, the multi-pollutant flue gas is derived from complex gas containing sulfur dioxide generated in the steel, electric, colored, petrochemical, chemical or building material industries. Preferably, the volume content of sulfur dioxide in the multi-pollutant flue gas is 0.01-1%, preferably 0.03-0.8%, and more preferably 0.05-0.5%. The temperature of the multi-pollutant flue gas is 100-200 ℃, preferably 120-180 ℃, and more preferably 130-160 ℃.
According to a second embodiment of the present invention, there is provided an exhaust gas purification and residual heat utilization device for an activated carbon desorption hot blast stove, comprising:
a tail gas purification and waste heat utilization device of a hot blast stove for active carbon desorption or a device for the method comprises an adsorption tower 1, a desorption tower 2, an atomizer 3, a dust remover 4 and a hot blast stove 13. The original flue gas pipeline L0 is connected with the flue gas inlet of the adsorption tower 1. The active carbon outlet of the adsorption tower 1 is connected to the desorption tower 2. The gas inlet of the heating section 201 of the analysis tower 2 is connected with the hot blast stove 13, and the first flue gas pipeline L1 led out from the gas outlet of the heating section 201 of the analysis tower 2 is connected with the original flue gas pipeline L0. The first flue gas pipeline L1 is sequentially provided with an atomizer 3 and a dust remover 4, and the atomizer 3 is arranged at the upstream of the dust remover 4.
Preferably, the apparatus further comprises a drying tower 15. The drying tower 15 is disposed on the first flue gas duct L1, and the atomizer 3 is located at the top inside the drying tower 15.
In the invention, the device also comprises an acid filtering device 5 and a flocculation precipitation device 6. The wastewater is conveyed to the inlet of the acidic filtering device 5, and the liquid outlet of the acidic filtering device 5 is connected to the flocculation precipitation device 6. The liquid outlet of the flocculation and precipitation device 6 is connected to the atomizer 3.
Preferably, the apparatus further comprises an oxidation device 12. The liquid outlet of the acid filter unit 5 is connected to the oxidation unit 12. The outlet of the oxidation device 12 is connected to the flocculation and sedimentation device 6.
Preferably, the apparatus further comprises a metal recovery device 11. The solids outlet of the flocculation and precipitation unit 6 is connected to a metal recovery unit 11.
In the present invention, a bypass flue gas duct L2 branched from the raw flue gas duct L0 is connected to the first flue gas duct L1, and the position where the bypass flue gas duct L2 is connected to the first flue gas duct L1 is located upstream of the atomizer 3. Preferably, the bypass flue gas pipeline L2 is provided with a flow control valve 7.
Preferably, the apparatus further comprises a flow distribution device 8 disposed on the first flue gas duct L1, the flow distribution device 8 being located upstream of the point at which the bypass flue gas duct L2 connects to the first flue gas duct L1. The second flue gas duct L3 leading from the flow distributing device 8 is connected to the original flue gas duct L0. Preferably, the first flue gas pipeline L1 is further provided with a flow meter 9, and the flow meter 9 is located upstream of the flow distribution device 8.
Preferably, an air duct L4 is connected to the second flue gas duct L3.
Preferably, the second flue gas pipeline L3 is provided with a heat exchanger 10. Preferably, the gas outlet of the cooling section 202 of the desorption column 2 is connected to the medium inlet of the heat exchanger 10 via a gas transfer conduit.
In the present invention, the apparatus also includes an SRG gas acid making system 14. The SRG gas outlet of the desorption tower 2 is connected to the gas inlet of the SRG gas acid making system 14 through a pipeline, and the wastewater outlet of the SRG gas acid making system 14 is connected to the inlet of the acid filtering device 5 through a wastewater conveying pipeline L5.
Preferably, the solids outlet of the acidic filtration device 5 is connected to the activated carbon inlet of the adsorption column 1.
Preferably, the atomizer 3 is provided with an alkali liquor inlet. The gas outlet of the dust separator 4 is connected to the gas inlet of the adsorption tower 1.
Example 1
As shown in fig. 2, the device for purifying tail gas and utilizing waste heat of the hot blast stove for desorbing active carbon comprises an adsorption tower 1, an analytical tower 2, an atomizer 3, a dust remover 4 and a hot blast stove 13. The original flue gas pipeline L0 is connected with the flue gas inlet of the adsorption tower 1. The active carbon outlet of the adsorption tower 1 is connected to the desorption tower 2. The gas inlet of the heating section 201 of the analysis tower 2 is connected with the hot blast stove 13, and the first flue gas pipeline L1 led out from the gas outlet of the heating section 201 of the analysis tower 2 is connected with the original flue gas pipeline L0. The first flue gas pipeline L1 is sequentially provided with an atomizer 3 and a dust remover 4, and the atomizer 3 is arranged at the upstream of the dust remover 4. An alkali liquor inlet is arranged on the atomizer 3. The gas outlet of the dust separator 4 is connected to the gas inlet of the adsorption tower 1.
A bypass flue gas duct L2 branching off from the raw flue gas duct L0 is connected to the first flue gas duct L1, and the position where the bypass flue gas duct L2 is connected to the first flue gas duct L1 is upstream of the atomizer 3. The bypass flue gas pipeline L2 is provided with a flow control valve 7.
The apparatus further comprises a flow distribution device 8 disposed on the first flue gas duct L1, the flow distribution device 8 being located upstream of the point at which the bypass flue gas duct L2 connects to the first flue gas duct L1. The second flue gas duct L3 leading from the flow distributing device 8 is connected to the original flue gas duct L0. The first flue gas pipeline L1 is also provided with a flow meter 9, and the flow meter 9 is located upstream of the flow distribution device 8.
The second flue gas duct L3 is provided with a heat exchanger 10. The gas outlet of the cooling section 202 of the desorption column 2 is connected to the medium inlet of the heat exchanger 10 via a gas transfer conduit.
Example 2
Example 1 is repeated except that the apparatus further comprises a drying tower 15. The drying tower 15 is disposed on the first flue gas duct L1, and the atomizer 3 is located at the top inside the drying tower 15.
Example 3
As shown in fig. 3, the embodiment 2 is repeated, except that an air duct L4 is connected to the second flue gas duct L3, i.e., the heat exchanger 10 on the second flue gas duct L3 is replaced with an air duct L4.
Example 4
Example 2 was repeated, as shown in fig. 4, except that the apparatus further comprised an acid filtration apparatus 5, an oxidation apparatus 12, a flocculation and precipitation apparatus 6 and a metal recovery apparatus 11. The waste water is fed to the inlet of the acid filter unit 5 and the liquid outlet of the acid filter unit 5 is connected to the oxidation unit 12. The outlet of the oxidation device 12 is connected to the flocculation and sedimentation device 6. The liquid outlet of the flocculation and precipitation device 6 is connected to the atomizer 3. The solids outlet of the flocculation and precipitation unit 6 is connected to a metal recovery unit 11. The solid outlet of the acidic filtering device 5 is connected to the activated carbon inlet of the adsorption tower 1.
Example 5
Example 4 is repeated, as shown in fig. 5, except that the apparatus further includes an SRG gas acid making system 14. The SRG gas outlet of the desorption tower 2 is connected to the gas inlet of the SRG gas acid making system 14 through a pipeline, and the wastewater outlet of the SRG gas acid making system 14 is connected to the inlet of the acid filtering device 5 through a wastewater conveying pipeline L5.
Example 6
As shown in fig. 1, a method for purifying tail gas and utilizing waste heat of a hot blast stove for desorption of activated carbon comprises the following steps:
1) the multi-pollutant flue gas is conveyed to the adsorption tower 1 through a raw flue gas pipeline L0.
2) When the activated carbon is analyzed, tail gas of the hot blast stove discharged from a heating section 201 of an analysis tower 2 enters a first flue gas pipeline L1, an atomizer 3 and a dust remover 4 are sequentially arranged on the first flue gas pipeline L1, wastewater is atomized through the atomizer 3, the atomized wastewater absorbs pollutants in the tail gas of the hot blast stove in the first flue gas pipeline L1, and the tail gas of the hot blast stove evaporates the wastewater to form flue gas containing crystalline salt; and (4) dedusting the flue gas containing the crystallized salt by a deduster 4 to obtain the crystallized salt and the flue gas containing ammonia.
Wherein: the wastewater in the step 2) is acidic washing wastewater. The acid washing wastewater is the acid washing wastewater produced by the SRG gas of the active carbon. In the step 2), a wastewater treatment process is further included before the wastewater atomization, and the process specifically comprises the following steps:
2a) acid filtration: carrying out acidic filtration on the acidic washing wastewater through an acidic filtration device 5, and removing suspended matters by utilizing the self gravity settling action or the filter interception action of the suspended matters; obtaining suspended matter precipitate and clear liquid;
2b) clear liquid flocculation: introducing the clear liquid obtained in step 2a) into a flocculation precipitation device 6, adding sodium hydroxide and sodium carbonate, and adjusting the pH value to 8; flocculating and precipitating the clear liquid to obtain metal-containing sludge and salt-containing wastewater;
2c) adjusting alkali of wastewater: the salt-containing wastewater is mixed with sodium hydroxide and then enters the atomizer 3.
3) The tail end of the first flue gas pipeline L1 is merged to the original flue gas pipeline L0, the flue gas containing ammonia in the first flue gas pipeline L1 is mixed with the flue gas in the original flue gas pipeline L0 and then enters the adsorption tower 1, and the flue gas is adsorbed and purified by the activated carbon in the adsorption tower 1 and then is discharged.
In this example, the concentration of the suspension in the supernatant after acidic filtration was 1 mg/L. And removing heavy metal ions in the clear liquid after the acid filtration through flocculation and precipitation, wherein the metal ions enter the metal-containing sludge. The salt-containing wastewater is evaporated by using the tail gas of the hot blast stove in the first flue gas pipeline L1 to obtain crystallized salt, so that zero discharge of the wastewater is realized; meanwhile, pollutants in the hot blast stove tail gas are removed in a synergistic manner, so that the waste heat of the hot blast stove tail gas is efficiently utilized, and the zero emission of waste gas is realized.
Example 7
Example 6 was repeated except that in step 1), the raw flue gas line L0 branches off the bypass flue gas line L2. In step 2), the bypass flue gas duct L2 merges into the first flue gas duct L1, and the connection point of the bypass flue gas duct L2 to the first flue gas duct L1 is located upstream of the atomizer 3. The bypass flue gas in the bypass flue gas pipeline L2 is mixed with the tail gas of the hot blast stove in the first flue gas pipeline L1, and the atomized waste water is evaporated by using the mixed gas of the bypass flue gas in the first flue gas pipeline L1 and the tail gas of the hot blast stove and then enters the dust remover 4. The bypass flue gas pipeline L2 is provided with a flow control valve 7 for controlling the flow of flue gas entering the bypass flue gas pipeline L2 from the raw flue gas pipeline L0.
In this embodiment, when the amount of the tail gas of the hot blast stove is not enough to treat the wastewater, a part of the flue gas is introduced from the raw flue gas pipeline L0 to enter the bypass flue gas pipeline L2, and the flue gas entering the bypass flue gas pipeline L2 is mixed with the tail gas of the hot blast stove in the first flue gas pipeline L1 to evaporate the wastewater together.
Example 8
Example 7 is repeated, except that in step 2), a flow distribution device 8 is arranged on the first flue gas pipeline L1 and upstream of the connection position of the bypass flue gas pipeline L2 and the first flue gas pipeline L1, and the tail gas of the hot blast stove enters the second flue gas pipeline L3 through the flow distribution device 8. In the step 3), the second flue gas pipeline L3 is merged into the original flue gas pipeline L0, and the hot blast stove tail gas in the second flue gas pipeline L3 is mixed with the flue gas in the original flue gas pipeline L0, enters the adsorption tower 1, and is adsorbed and purified by the activated carbon in the adsorption tower 1 and then is discharged. Wherein, a flowmeter 9 is arranged on the first flue gas pipeline L1 and at the upstream of the flow distribution device 8, and is used for detecting the total flow of the hot blast furnace tail gas. And meanwhile, cold air is introduced into the second flue gas pipeline L3 to adjust the temperature of the tail gas of the hot blast stove in the second flue gas pipeline L3.
In this embodiment, flow detection and the operating condition analysis to hot-blast furnace tail gas according to flowmeter 9, when the flow of hot-blast furnace tail gas is great, partly hot-blast furnace tail gas gets into drying tower 15 through first flue gas pipeline L1 and carries out the evaporation treatment to waste water, perhaps this part hot-blast furnace tail gas and the flue gas that gets into bypass flue gas pipeline L2 mix the back and carry out the evaporation treatment to waste water in the lump, another part hot-blast furnace tail gas gets into second flue gas pipeline L3, and get into adsorption tower 1 after with the cold air heat transfer, the direct outer polluted environment that arranges of hot-blast furnace tail gas has been avoided. The flow rate of the hot blast stove tail gas for treating wastewater and the flow rate of the hot blast stove tail gas entering the adsorption tower 1 through the second flue gas pipeline L3 are controlled by the flow rate distribution device 8. When abnormal working conditions occur and no wastewater enters, the tail gas of the hot blast stove can completely enter the second flue gas pipeline L3, and enters the adsorption tower 1 for purification treatment after heat exchange with cold air.
Example 9
Example 8 is repeated except that the heat exchanger 10 is arranged on the second flue gas pipeline L3, and the tail gas of the hot blast stove in the second flue gas pipeline L3 is mixed with the flue gas in the original flue gas pipeline L0 after the temperature of the tail gas is controlled or regulated by the heat exchanger 10. I.e. no cold air is introduced into the second flue gas duct L3. The medium inlet of the heat exchanger 10 is connected with the gas outlet of the cooling section 202 of the desorption tower 2, and the heat exchange medium of the heat exchanger 10 is cold air discharged from the cooling section 202 of the desorption tower 2. The cold air discharged from the cooling section 202 of the desorption tower 2 exchanges heat with the tail gas of the hot blast stove in the second flue gas pipeline L3 to be changed into hot air, and the hot air is conveyed to the waste heat utilization system.
In this embodiment, the tail gas of the hot blast stove entering the second flue gas duct L3 enters the adsorption tower 1 after exchanging heat with the cold air discharged from the cooling section 202 of the desorption tower 2, and is then purified. The cold wind that desorption tower 2 cooling section 202 was discharged carries out the heat exchange with the interior hot-blast furnace tail gas of second flue gas pipeline L3 and becomes hot-blast, is carried to the waste heat utilization system, compares in embodiment 8, and this embodiment is more abundant to the waste heat utilization of hot-blast furnace tail gas, and the cold wind of desorption tower 2 cooling section 202 has reduced the production of waste gas as heat transfer medium simultaneously, has also avoided the direct outward pollution that leads to the fact to the environment of cold wind.
Example 10
Example 9 was repeated except that step 2b) also included an oxidation step; the method specifically comprises the following steps: oxidizing the clear liquid obtained in the step 2a) by an oxidation device 12 through electrochemical oxidation, then introducing the oxidized clear liquid into a flocculation precipitation device 6, adding mixed alkali, and performing a weak alkali flocculation precipitation process to flocculate and precipitate the clear liquid to obtain the metal-containing sludge and the salt-containing wastewater. The method further comprises the following steps: 2d) metal recovery: the metal-containing sludge obtained in step 2b) is recycled by means of a metal recycling device 11.
In the embodiment, the clear liquid after the acid filtration is subjected to an oxidation process to remove COD in the clear liquid, so that organic matter components in the clear liquid are greatly reduced; then removing heavy metal ions in the waste water by flocculation precipitation. The metal-containing sludge is subjected to a metal recovery process to enrich and recover metals, so that economic value is directly generated.
Example 11
Example 10 is repeated, and the acidic washing wastewater is obtained by wet washing acidic flue gas. Wherein, the acid flue gas is SRG gas. The multi-pollutant flue gas is adsorbed by an adsorption tower 1, activated carbon is arranged in the adsorption tower 1, and the activated carbon adsorbed with pollutants is analyzed by an analysis tower 2 to obtain SRG gas. The suspended matter is precipitated as carbon powder in step 2 a). The carbon powder is used for synthesizing large-particle activated carbon and returns to the adsorption tower 1 for recycling through a carbon powder recycling process (re-granulation). The SRG gas comprises suspended matters, metal ions, ammonia nitrogen, fluorine and chlorine and organic pollutants. The metal ions include iron, copper, lead, calcium, zinc, cadmium, cobalt, nickel and aluminum.
In the wet washing process, the volume flow ratio of the SRG gas to the acidic solution is 1: 45. In step 2a), the concentration of the suspension in the supernatant after acidic filtration was 1.8 mg/L. Through a flocculation precipitation process, the content of heavy metal ions in the salt-containing wastewater is 6.7 mg/L.
The high-sulfur gas generated in the SRG gas treatment process is subjected to a sulfur recycling process to recover sulfuric acid. The salt-containing wastewater after the flocculation precipitation process is changed into crystal salt through the processes of adding alkali, atomizing, drying, dedusting and the like, and the crystal salt can be directly sold, so that economic benefits are generated; and screening the activated carbon after thermal regeneration to obtain large-particle activated carbon and small-particle activated carbon. The embodiment completely realizes the advantages of the synergistic treatment of multi-pollutant flue gas and the effective control of secondary pollution. The method can well treat secondary pollutants, utilize waste heat, change waste into valuable, recycle waste water, realize zero discharge of waste water, save cost, recover resources and protect environment.
Detecting CO in hot blast stove tail gas at discharge position of desorption tower2、SO2Then detecting CO in the flue gas after passing through a drying tower and a dust remover2、SO2The contents of (a) are recorded as follows:
Figure BDA0002148318120000181

Claims (19)

1. a tail gas purification and waste heat utilization method of a hot blast stove for active carbon desorption comprises the following steps:
1) the multi-pollutant flue gas is conveyed to the adsorption tower (1) through an original flue gas pipeline (L0);
2) when the activated carbon is analyzed, hot blast stove tail gas discharged from a heating section (201) of an analysis tower (2) enters a first flue gas pipeline (L1), an atomizer (3) and a dust remover (4) are sequentially arranged on the first flue gas pipeline (L1), the wastewater is atomized through the atomizer (3), the atomized wastewater absorbs pollutants in the hot blast stove tail gas in the first flue gas pipeline (L1), and the hot blast stove tail gas evaporates the wastewater to form flue gas containing crystallized salt; the flue gas containing the crystallized salt is subjected to dust removal treatment by a dust remover (4) to obtain crystallized salt and flue gas containing ammonia;
3) the tail end of the first flue gas pipeline (L1) is merged to the original flue gas pipeline (L0), the flue gas containing ammonia in the first flue gas pipeline (L1) and the flue gas in the original flue gas pipeline (L0) are mixed and then enter the adsorption tower (1), and the flue gas is adsorbed and purified by the activated carbon in the adsorption tower (1) and then is discharged.
2. The method of claim 1, wherein: the wastewater in the step 2) is acidic washing wastewater; preferably, the acidic washing wastewater is one or more of flue gas wet desulphurization and denitration wastewater, activated carbon SRG gas acid-making washing wastewater and membrane concentration wastewater; and/or
In the step 2), a wastewater treatment process is further included before the wastewater atomization, and the process specifically comprises the following steps:
2a) acid filtration: performing acidic filtration on the wastewater through an acidic filtration device (5) to obtain suspended substance precipitate and clear liquid;
2b) clear liquid flocculation: introducing the clear liquid obtained in the step 2a) into a flocculation precipitation device (6), and adding mixed alkali to flocculate and precipitate the clear liquid to obtain metal-containing sludge and salt-containing wastewater;
2c) adjusting alkali of wastewater: the salt-containing wastewater is mixed with the alkali liquor and then enters an atomizer (3).
3. The method according to claim 1 or 2, characterized in that: in the step 1), the original flue gas pipeline (L0) is divided into a bypass flue gas pipeline (L2); in step 2), the bypass flue gas duct (L2) merges into the first flue gas duct (L1), and the connection position of the bypass flue gas duct (L2) and the first flue gas duct (L1) is located upstream of the atomizer (3); the bypass flue gas in the bypass flue gas pipeline (L2) is mixed with the tail gas of the hot blast stove in the first flue gas pipeline (L1), and the atomized waste water is evaporated by using the mixed gas of the bypass flue gas in the first flue gas pipeline (L1) and the tail gas of the hot blast stove and then enters the dust remover (4);
preferably, the bypass flue gas duct (L2) is provided with a flow control valve (7) for controlling the flow of flue gas entering the bypass flue gas duct (L2) from the raw flue gas duct (L0).
4. The method of claim 3, wherein: in the step 2), a flow distribution device (8) is arranged on the first flue gas pipeline (L1) and at the upstream of the connection position of the bypass flue gas pipeline (L2) and the first flue gas pipeline (L1), and the tail gas of the hot blast stove enters the second flue gas pipeline (L3) through the flow distribution device (8); in the step 3), the second flue gas pipeline (L3) is merged into the original flue gas pipeline (L0), the tail gas of the hot blast stove in the second flue gas pipeline (L3) is mixed with the flue gas in the original flue gas pipeline (L0) and then enters the adsorption tower (1), and the tail gas is adsorbed and purified by the active carbon in the adsorption tower (1) and then is discharged;
preferably, a flow meter (9) is arranged on the first flue gas pipeline (L1) and positioned at the upstream of the flow distribution device (8) and is used for detecting the total flow of the tail gas of the hot blast stove in the first flue gas pipeline (L1).
5. The method of claim 4, wherein: introducing cold air into the second flue gas pipeline (L3) to adjust the temperature of the tail gas of the hot blast stove in the second flue gas pipeline (L3); and/or
The second flue gas pipeline (L3) is provided with a heat exchanger (10), and the hot blast stove tail gas in the second flue gas pipeline (L3) is mixed with the flue gas in the original flue gas pipeline (L0) after the temperature of the hot blast stove tail gas is controlled or regulated by the heat exchanger (10).
6. The method of claim 5, wherein: a medium inlet of the heat exchanger (10) is connected with a gas outlet of a cooling section (202) of the desorption tower (2), and a heat exchange medium of the heat exchanger (10) is cold air discharged from the cooling section (202) of the desorption tower (2); preferably, the cold air discharged from the cooling section (202) of the desorption tower (2) is converted into hot air after heat exchange with the hot blast furnace tail gas in the second flue gas duct (L3), and is conveyed to the waste heat utilization system.
7. The method according to any one of claims 2-6, wherein: the wastewater treatment process further comprises: 2d) metal recovery: recycling the metal-containing sludge obtained in the step 2b) through a metal recycling device (11); and/or
The step 2b) also comprises an oxidation process; the method specifically comprises the following steps: oxidizing the clear liquid obtained in the step 2a) through an oxidation device (12), then introducing the oxidized clear liquid into a flocculation precipitation device (6), adding mixed alkali, and performing a weak alkali flocculation precipitation process to flocculate and precipitate the clear liquid to obtain metal-containing sludge and salt-containing wastewater;
preferably, the oxidation treatment employs one or more of chemical oxidation, electrochemical oxidation, ultraviolet catalytic oxidation, air oxidation or chemical oxidation.
8. The method according to any one of claims 2-7, wherein: the acid washing wastewater is obtained by washing acid flue gas by a wet method; preferably, the acid flue gas is SRG gas, and the SRG gas is: the multi-pollutant flue gas is subjected to adsorption treatment through active carbon in an adsorption tower (1), and the active carbon adsorbed with pollutants is obtained by analyzing through an analyzing tower (2); and/or
Precipitating the suspended matters in the step 2a) into carbon powder; preferably, the carbon powder is used for synthesizing large-particle activated carbon and is returned to the adsorption tower (1) for recycling through the carbon powder recycling process.
9. The method of claim 8, wherein: the solution adopted by the wet washing is an acid solution; preferably, the pH value of the acidic solution is 0-7, preferably 1-6, and more preferably 2-5; preferably, the acidic solution is dilute sulfuric acid or dilute hydrochloric acid; in the wet washing process, the volume flow ratio of the SRG gas to the acidic solution is 1: 10-100, preferably 1: 20-80, and more preferably 1: 30-60.
10. The method according to any one of claims 2-9, wherein: in step 2a), the acidic filtration is specifically: removing the suspended matters by utilizing the self gravity settling effect or the filter interception effect of the suspended matters, wherein the concentration of the suspended matters in the clear liquid after the acid filtration is 0-100 mg/L, preferably 1-80 mg/L, and more preferably 2-50 mg/L; and/or
The acidic washing wastewater comprises one or more of suspended matters, metal ions, ammonia nitrogen, fluorine and chlorine and organic pollutants; preferably, the metal ions are one or more of iron, copper, lead, calcium, zinc, cadmium, cobalt, nickel and aluminum.
11. The method according to any one of claims 2-10, wherein: in the step 2b), the flocculation precipitation specifically comprises the following steps: adding mixed alkali into the clear liquid, and adjusting the pH value to be alkalescent so as to flocculate and precipitate the weak alkali in the clear liquid and obtain metal-containing sludge and salt-containing wastewater; preferably, the pH of the serum is adjusted to 7-10, preferably 7.2-9, more preferably 7.5-8.5; preferably, the mixed alkali is a mixture of soluble hydroxide and soluble carbonate, or a mixture of soluble hydroxide and soluble bicarbonate; more preferably, the mixed alkali is a mixture of one or more of sodium hydroxide, potassium hydroxide and lithium hydroxide and one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate.
12. The method according to any one of claims 2-11, wherein: in the step 2), the atomization specifically comprises: dispersing the mixture of the clear liquid and the alkali liquor into small fog drops through an atomizer (3), wherein the particle size of the small fog drops is 10-100 microns, preferably 15-80 microns, and more preferably 20-50 microns; preferably, the alkali liquor is one or more of soluble hydroxide, soluble carbonate and soluble bicarbonate, and is preferably sodium hydroxide; preferably, the addition amount of the alkali liquor is 0-0.5 times, preferably 0.01-0.25 times, and more preferably 0.05-0.1 times of the amount of the clear liquor; and/or
The dust removal treatment in the step 2) adopts dry dust removal, preferably electric dust removal, cloth bag dust removal or cyclone dust removal, and preferably cloth bag dust removal; after the dust removal treatment, the crystallized salt is discharged from a solid outlet of the dust remover (4).
13. The method according to any one of claims 1-12, wherein: the multi-pollutant flue gas is SO2Mixed flue gas consisting of one or more of NOx, dust, VOCs and heavy metals; and/or
The multi-pollutant flue gas is derived from a complex gas containing sulfur dioxide generated in the steel, electric power, colored, petrochemical, chemical or building material industries; preferably, the volume content of sulfur dioxide in the multi-pollutant flue gas is 0.01-1%, preferably 0.03-0.8%, and more preferably 0.05-0.5%; the temperature of the multi-pollutant flue gas is 100-200 ℃, preferably 120-180 ℃, and more preferably 130-160 ℃.
14. A tail gas purification and waste heat utilization device of a hot blast stove for active carbon desorption or a device for the method of any one of claims 1 to 13, which comprises an adsorption tower (1), a desorption tower (2), an atomizer (3), a dust remover (4) and the hot blast stove (13); the original flue gas pipeline (L0) is connected with a flue gas inlet of the adsorption tower (1); an active carbon outlet of the adsorption tower (1) is connected to the desorption tower (2); a gas inlet of a heating section (201) of the analysis tower (2) is connected with the hot blast stove (13), and a first flue gas pipeline (L1) led out from a gas outlet of the heating section (201) of the analysis tower (2) is connected to an original flue gas pipeline (L0); an atomizer (3) and a dust remover (4) are sequentially arranged on the first flue gas pipeline (L1), and the atomizer (3) is arranged at the upstream of the dust remover (4);
preferably, the apparatus further comprises a drying tower (15); the drying tower (15) is arranged on the first flue gas pipeline (L1), and the atomizer (3) is positioned at the top in the drying tower (15).
15. The apparatus of claim 14, wherein: the device also comprises an acid filtering device (5) and a flocculation precipitation device (6); the wastewater is conveyed to an inlet of an acidic filtering device (5), and a liquid outlet of the acidic filtering device (5) is connected to a flocculation precipitation device (6); the liquid outlet of the flocculation precipitation device (6) is connected to the atomizer (3);
preferably, the apparatus further comprises an oxidation device (12); the liquid outlet of the acid filtering device (5) is connected to the oxidation device (12); the outlet of the oxidation device (12) is connected to the flocculation precipitation device (6); and/or
The device also comprises a metal recovery device (11); the solid outlet of the flocculation precipitation device (6) is connected to the metal recovery device (11).
16. The apparatus of claim 14 or 15, wherein: a bypass flue gas pipeline (L2) branched from the raw flue gas pipeline (L0) is connected to the first flue gas pipeline (L1), and the position where the bypass flue gas pipeline (L2) is connected with the first flue gas pipeline (L1) is positioned at the upstream of the atomizer (3); preferably, a flow control valve (7) is arranged on the bypass flue gas pipeline (L2); and/or
The apparatus further comprises a flow distribution device (8) arranged on the first flue gas duct (L1), the flow distribution device (8) being located upstream of the location where the bypass flue gas duct (L2) connects to the first flue gas duct (L1); a second flue gas pipeline (L3) led out from the flow distribution device (8) is connected to the original flue gas pipeline (L0); preferably, the first flue gas pipeline (L1) is also provided with a flow meter (9), and the flow meter (9) is positioned at the upstream of the flow distribution device (8).
17. The apparatus of claim 16, wherein: an air pipeline (L4) is connected to the second flue gas pipeline (L3); and/or
A heat exchanger (10) is arranged on the second flue gas pipeline (L3); preferably, the gas outlet of the cooling section (202) of the desorption column (2) is connected to the medium inlet of the heat exchanger (10) via a gas transfer conduit.
18. The apparatus according to any one of claims 15-17, wherein: the apparatus also includes an SRG gas acid making system (14); an SRG gas outlet of the desorption tower (2) is connected to a gas inlet of an SRG gas acid making system (14) through a pipeline, and a waste water outlet of the SRG gas acid making system (14) is connected to an inlet of the acid filtering device (5) through a waste water conveying pipeline (L5).
19. The apparatus according to any one of claims 15-18, wherein: a solid outlet of the acidic filtering device (5) is connected to an activated carbon inlet of the adsorption tower (1); and/or
An alkali liquor inlet is arranged on the atomizer (3); the gas outlet of the dust remover (4) is connected to the gas inlet of the adsorption tower (1).
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