CN103961995B - A kind of coal-fired flue-gas alkali desulphurization produces the method for high-purity sodium sulfite and sodium sulphate - Google Patents
A kind of coal-fired flue-gas alkali desulphurization produces the method for high-purity sodium sulfite and sodium sulphate Download PDFInfo
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Abstract
Coal-fired flue-gas alkali desulphurization produces a method for high-purity sodium sulfite and sodium sulphate, adopts two-step desulfurization technique, and first order desulfurization be slightly take off, and sulfate is stayed in first order doctor solution and produces sodium sulphate, in flue gas, most of sulfur dioxide enters two-grade desulfurizing; Second level desulfurization is main de-, and flue gas can qualified discharge, and doctor solution directly can produce high-purity sodium sulfite by condensing crystallizing.Advantage of the present invention is: the method technique is simple, easy to implement, adopt two-step desulfurization technique, the sulfur dioxide of low-concentration flue gas is used as resource, thorough solution desulfurization secondary pollution also realizes zero-emission, utilize the high-purity sulphuric acid sodium of the sulphur dioxide production 95% in flue gas and 95% high-purity sodium sulfite product, wherein sodium sulfite proportion is 90-95%, change over the processing mode of pure consumption of natural resource, greatly alleviating enterprise's desulfurization burden even makes desulfurization become value-added production, has significant techno-economic effect.
Description
Technical field
The present invention relates to coal-fired flue gas desulfurization technology, particularly a kind of coal-fired flue-gas alkali desulphurization produces the method for high-purity sodium sulfite and sodium sulphate.
Background technology
Sulfur dioxide (SO2) emissions cause China's air environmental pollution and the increasing one of the main reasons of acid rain, since 1998, and China SO
2annual emissions exceedes the U.S., occupies first place in the world for years.And the coal-fired SO produced
2discharge capacity accounts for SO
2more than 90% of total emission volumn.
Coal-fired flue-gas is because of ature of coal difference, and sulfur dioxide concentration is generally 1000-3500ppm, and oxygen content is generally 3-8%, and discharging sulfur dioxide concentration after requiring desulfurization is 50ppm; Flue gas for such low-concentration sulfur dioxide forms, and domestic desulfurization industry disposal status is: 1) existing flue gas desulfurization technique is all remove sulfur dioxide in flue gas qualified discharge for target; 2) a large amount of calcium sulfate, calcium sulfite, sodium sulfite solution the like waste is accumulated after desulfurization, most calcium method by-product calcium sulfate is difficult to utilize, need to take a large amount of soil storage waste residue and cause secondary pollution, inadequate use to be also that expense is huge cause more burdens to enterprise, soda rule by-product sodium sulfite waste liquid, substantially be all by oxidation biochemical treatment, invest huge, operating cost is very high, reclaiming sodium sulfite can zero-emission, but sodium sulfite content generally only has about 60%, market does not have demand, suffers great loss; 3) the existing desulfurization wastewater technique of zero discharge such as sodium alkali, Dual alkali relating to use NaOH, be all adopt various new technology or equipment the wastewater treatment and renovation of existing sulfur removal technology, but still do not solve the use problem of byproduct or still belong to the technique of pure input cost.
Summary of the invention
The object of the invention is for above-mentioned existing problems, a kind of coal-fired flue-gas alkali desulphurization is provided to produce the method for high-purity sodium sulfite and sodium sulphate, the method technique is simple, easy to implement, adopt two-step desulfurization technique, the sulfur dioxide of low-concentration flue gas is used as resource, thoroughly solving desulfurization secondary pollution and while realizing zero-emission, utilize the sulphur dioxide production high-purity sodium sulfite product in flue gas, change over the processing mode of pure consumption of natural resource, greatly alleviating enterprise's desulfurization burden even makes desulfurization become value-added production, there is significant techno-economic effect.
Technical scheme of the present invention:
Coal-fired flue-gas alkali desulphurization produces a method for high-purity sodium sulfite and sodium sulphate, adopts two-step desulfurization technique, and first order desulfurization be slightly take off, and sulfate is stayed in first order doctor solution and produces sodium sulphate, in flue gas, most of sulfur dioxide enters two-grade desulfurizing; Second level desulfurization is main de-, and flue gas can qualified discharge, and doctor solution directly can produce high-purity sodium sulfite by condensing crystallizing, and step is as follows:
1) first order desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 20-50m/s, doctor solution is the sodium hydroxide solution of concentration 5-15wt%, and in alkali lye, add the oxygen-inhibiting agent that quality is the 0.1-5wt% of alkali lye quality, the amount ratio of doctor solution and coal-fired flue-gas is 1-8L/m3, desulfurization temperature is 90-130 DEG C, to doctor solution pH value be less than 2.0 or there is crystalline particle time, release doctor solution, the sodium hydroxide solution filtering rear concentration >=30wt% regulates PH to 6.0-7.0, be cooled to 10-20 DEG C, Crystallization Separation goes out sodium sulphate, mother liquor joins alkali and oxygen-inhibiting agent recovery is reused for first grade desulfurizing,
2) second level desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 20-50m/s, doctor solution is the sodium hydroxide solution of concentration 8-20wt% and in alkali lye, adds the 0.01-2wt% sodium thiosulfate that quality is alkali lye quality, sodium pyrosulfite, bisphenol-A, the oxygen-inhibiting agent of two or more arbitrary proportion mixing in hydroquinones and ascorbic acid, the amount ratio of doctor solution and coal-fired flue-gas is 10-28L/m3, desulfurization temperature is 40-70 DEG C, when being less than 6.0 to doctor solution pH value, release doctor solution, the sodium hydroxide solution filtering rear concentration >=30wt% regulates PH to ph10-11, through evaporation, Crystallization Separation obtains sodium sulfite, mother liquor is allocated neutralizer into and is reentered evaporator evaporation crystallization.
The oxygen-inhibiting agent of described first order desulfurization is sodium thiosulfate, sodium pyrosulfite, bisphenol-A, hydroquinones or ascorbic acid; The oxygen-inhibiting agent of described second level desulfurization is the mixture of the two or more arbitrary proportions in sodium thiosulfate, sodium pyrosulfite, bisphenol-A, hydroquinones and ascorbic acid.
Working mechanism of the present invention:
Desulfurization temperature in the desulfurization of this method step 1) first order, is different from the requirement of conventional desulfurization temperature, and higher temperature is conducive to hindering oxygen effect and the first order absorption reducing sulfur dioxide gas; The pH value of doctor solution, is different from the requirement of conventional desulfurization liquid PH, and lower pH value is conducive to first grade desulfurizing alkali lye and forms more sodium sulphate or niter cake, reduces the first order absorption of sulfur dioxide gas simultaneously.Step 2) require in the desulfurization of the second level to adopt two or more mixing oxygen-inhibiting agents, mainly two-grade desulfurizing liquid is longer for circulation timei, needs oxygen-inhibiting agent to maintain the long period.
Advantage of the present invention is: the method technique is simple, easy to implement, adopt two-step desulfurization technique, the sulfur dioxide of low-concentration flue gas is used as resource, thorough solution desulfurization secondary pollution also realizes zero-emission, utilize the high-purity sulphuric acid sodium of the sulphur dioxide production 95% in flue gas and 95% high-purity sodium sulfite product, wherein sodium sulfite proportion is 90-95%, change over the processing mode of pure consumption of natural resource, greatly alleviating enterprise's desulfurization burden even makes desulfurization become value-added production, has significant techno-economic effect.
Detailed description of the invention
Embodiment 1:
Coal-fired flue-gas alkali desulphurization produces a method for high-purity sodium sulfite and sodium sulphate, and step is as follows:
1) first order desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 30m/s, doctor solution is the sodium hydroxide solution of concentration 5wt%, and in alkali lye, add the sodium thiosulfate that quality is the 2wt% of alkali lye quality, the amount ratio of doctor solution and coal-fired flue-gas is 3L/m3, desulfurization temperature is 95 DEG C, when being 1.8 to doctor solution pH value, release doctor solution, the sodium hydroxide solution filtering rear 32wt% regulates PH to 6.5, enter evaporator evaporation, be evaporated to when crystallization occurs and transferred to cooler, be cooled to 20 DEG C, crystallization centrifuge is separated, sodium sulphate is obtained after oven dry, detecting sodium sulphate content is 95.5%, mother liquor joins alkali and oxygen-inhibiting agent recovery is reused for first grade desulfurizing,
2) second level desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 30m/s, doctor solution is the sodium hydroxide solution of concentration 15wt% and in alkali lye, adds the oxygen-inhibiting agent that quality is alkali lye quality 0.5%, sodium thiosulfate and the hydroquinones mixture of oxygen-inhibiting agent to be mass ratio be 1:0.1, , the amount ratio of doctor solution and coal-fired flue-gas is 15L/m3, desulfurization temperature is 60 DEG C, when being 5.8 to doctor solution pH value, release doctor solution, filter the sodium hydroxide solution adjustment PH to ph10.5 that rear concentration is 32wt%, neutralizer through multiple-effect evaporation to occurring mass crystallization, crystallization centrifugation obtains sodium sulfite, after drying, sodium sulfite content is 95.3%, mother liquor is allocated neutralizer into and is reentered evaporator evaporation crystallization.
Embodiment 2:
Coal-fired flue-gas alkali desulphurization produces a method for high-purity sodium sulfite and sodium sulphate, and step is as follows:
1) first order desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 30m/s, doctor solution is the sodium hydroxide solution of concentration 8wt%, and in alkali lye, add the bis-phenol a that quality is the 1wt% of alkali lye quality, the amount ratio of doctor solution and coal-fired flue-gas is 3L/m3, desulfurization temperature is 95 DEG C, when being 2.0 to doctor solution pH value, release doctor solution, the sodium hydroxide solution filtering rear 32wt% regulates PH to 6.8, enter evaporator evaporation, be evaporated to when crystallization occurs and transferred to cooler, be cooled to 20 DEG C, crystallization centrifuge is separated, sodium sulphate is obtained after oven dry, detecting sodium sulphate content is 96.3%, mother liquor joins alkali and oxygen-inhibiting agent recovery is reused for first grade desulfurizing,
2) second level desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 30m/s, doctor solution is the sodium hydroxide solution of concentration 13wt% and in alkali lye, adds the oxygen-inhibiting agent that quality is alkali lye quality 0.3%, sodium thiosulfate and the bis-phenol a mixture of oxygen-inhibiting agent to be mass ratio be 1:0.2, the amount ratio of doctor solution and coal-fired flue-gas is 15L/m3, desulfurization temperature is 60 DEG C, when being 5.6 to doctor solution pH value, release doctor solution, filter the sodium hydroxide solution adjustment PH to ph10.5 that rear concentration is 32wt%, neutralizer through multiple-effect evaporation to occurring mass crystallization, crystallization centrifugation obtains sodium sulfite, after drying, sodium sulfite content is 95.1%, mother liquor is allocated neutralizer into and is reentered evaporator evaporation crystallization.
Embodiment 3:
Coal-fired flue-gas alkali desulphurization produces a method for high-purity sodium sulfite and sodium sulphate, and step is as follows:
1) first order desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 30m/s, doctor solution is the sodium hydroxide solution of concentration 10wt%, and in alkali lye, add the hydroquinones that quality is the 1.2wt% of alkali lye quality, the amount ratio of doctor solution and coal-fired flue-gas is 3L/m3, desulfurization temperature is 95 DEG C, when being 2.0 to doctor solution pH value, release doctor solution, the sodium hydroxide solution filtering rear 32wt% regulates PH to 6.9, enter evaporator evaporation, be evaporated to when crystallization occurs and transferred to cooler, be cooled to 20 DEG C, crystallization centrifuge is separated, sodium sulphate is obtained after oven dry, detecting sodium sulphate content is 95.8%, mother liquor joins alkali and oxygen-inhibiting agent recovery is reused for first grade desulfurizing,
2) second level desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 30m/s, doctor solution is the sodium hydroxide solution of concentration 14wt% and in alkali lye, adds the oxygen-inhibiting agent that quality is alkali lye quality 0.2%, the ascorbic acid of oxygen-inhibiting agent to be mass ratio be 1::5:1, sodium thiosulfate and hydroquinones mixture, the amount ratio of doctor solution and coal-fired flue-gas is 15L/m3, desulfurization temperature is 50 DEG C, when being 5.5 to doctor solution pH value, release doctor solution, filter the sodium hydroxide solution adjustment PH to ph10.5 that rear concentration is 32wt%, neutralizer through multiple-effect evaporation to occurring mass crystallization, crystallization centrifugation obtains sodium sulfite, after drying, sodium sulfite content is 96.1%, mother liquor is allocated neutralizer into and is reentered evaporator evaporation crystallization.
Claims (2)
1. a coal-fired flue-gas alkali desulphurization produces the method for high-purity sodium sulfite and sodium sulphate, it is characterized in that: adopt two-step desulfurization technique, first order desulfurization is thick de-, and sulfate is stayed in first order doctor solution and produces sodium sulphate, in flue gas, most of sulfur dioxide enters second level desulfurization; Second level desulfurization is main de-, flue gas qualified discharge, and the direct condensing crystallizing of doctor solution produces high-purity sodium sulfite, and step is as follows:
1) first order desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 20-50m/s, doctor solution is the sodium hydroxide solution of concentration 5-15wt%, and in sodium hydroxide solution, adding the oxygen-inhibiting agent that quality is the 0.1-5wt% of sodium hydroxide solution quality, the amount ratio of doctor solution and coal-fired flue-gas is 1-8L/m
3desulfurization temperature is 90-130 DEG C, to doctor solution pH value be less than 2.0 or there is crystalline particle time, release doctor solution, the sodium hydroxide solution filtering rear concentration>=30wt% regulates pH to 6.0-7.0, be cooled to 10-20 DEG C, Crystallization Separation goes out sodium sulphate, and mother liquor joins alkali and oxygen-inhibiting agent recovery is reused for first order desulfurization;
2) second level desulfurization
In desulfurizing tower, bottom passes into coal-fired flue-gas, top spray doctor solution, coal-fired flue-gas flow velocity is 20-50m/s, doctor solution is the sodium hydroxide solution of concentration 8-20wt% and in sodium hydroxide solution, adds the oxygen-inhibiting agent that in 0.01-2wt% sodium thiosulfate, sodium pyrosulfite, bisphenol-A, hydroquinones and the ascorbic acid that quality is sodium hydroxide solution quality, two or more arbitrary proportion mixes, and the amount ratio of doctor solution and coal-fired flue-gas is 10-28L/m
3, desulfurization temperature is 40-70 DEG C, when being less than 6.0 to doctor solution pH value, release doctor solution, the sodium hydroxide solution filtering rear concentration>=30wt% regulates pH to pH10-11, and obtain sodium sulfite through evaporation, Crystallization Separation, mother liquor is allocated neutralizer into and reentered evaporator evaporation crystallization.
2. coal-fired flue-gas alkali desulphurization produces the method for high-purity sodium sulfite and sodium sulphate according to claim 1, it is characterized in that: the oxygen-inhibiting agent of described first order desulfurization is sodium thiosulfate, sodium pyrosulfite, bisphenol-A, hydroquinones or ascorbic acid; The oxygen-inhibiting agent of described second level desulfurization is the mixture of the two or more arbitrary proportions in sodium thiosulfate, sodium pyrosulfite, bisphenol-A, hydroquinones and ascorbic acid.
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| BE1030584B1 (en) * | 2022-06-02 | 2024-01-08 | Univ Tianjin Technology | METHOD FOR PRODUCING HIGH PURITY SODIUM SULFITE AND SODIUM SULFATE FROM BURNED COAL GAS BY ALKALINE DESULFURIZATION |
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| CN106390704A (en) * | 2016-06-21 | 2017-02-15 | 太仓市顺邦防腐设备有限公司 | A system for treating sulfur containing flue gas by utilizing sodium sulfite |
| CN110124497B (en) * | 2019-05-27 | 2022-02-18 | 广东佳德环保科技有限公司 | Desulfurization and denitrification absorbent and application thereof |
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