CN1391975A - Method for controlling flue gas contaiing SO2 with NaCl and producing high concentratino SO2 - Google Patents
Method for controlling flue gas contaiing SO2 with NaCl and producing high concentratino SO2 Download PDFInfo
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- CN1391975A CN1391975A CN 01113697 CN01113697A CN1391975A CN 1391975 A CN1391975 A CN 1391975A CN 01113697 CN01113697 CN 01113697 CN 01113697 A CN01113697 A CN 01113697A CN 1391975 A CN1391975 A CN 1391975A
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Abstract
The present invention belongs to environment protecting technology and relates to desulfurizing fume with low density SO2 gas. NaOH product in electrolyzing NaCl is used to absorb purified flue gas to produce sodium sulfite and sodium bisulphate; H2 and Cl2 produced in electrolyzing NaCl react to produce HCl; HCl reacts with sodium sulfite and sodium bisulphate to produce SO2 and HCl mixture and the mixture is washed to produce high concentration SO2; and HCl reacts with sodium sulfite and sodium bisulphate to produce NaCl as electrolyte material. Flue gas with sulfur may be treated to a SO2 content of 20-300 ppm with scarcely power consumption. Sulfuric radical prepared in absorption may be eliminated with BaCl2 to produce medical BaSO4.
Description
The invention belongs to the technical field of environmental protection, and particularly relates to a wet flue gas desulfurization method for treating flue gas containing sulfur dioxide and producing high-concentration sulfur dioxide by using sodium chloride.
The technologies related to the present invention mainly include:
CN1012854, a method for removing low-concentration sulfur dioxide in flue gas, which uses basic aluminum sulfate solution to absorbSulfur dioxide gas in flue gas. The process is carried out in SO2When the concentration is lower than 2350ppm, the economy is poor; in SO2When the concentration is more than 1%, the tail gas hardly meets the emission requirement. Meanwhile, the method produces a small amount of gypsum by-product with low sulfur value.
CN1165051, a high-efficiency flue gas desulfurization process, in which sodium hydroxide is used to absorb sulfur dioxide in gas to generate sodium bisulfite, and then calcium hydroxide is used to regenerate and regenerate sodium hydroxide for reuse. The method does not recover sulfur resources in the flue gas, generates a large amount of calcium sulfite, needs a huge slag yard or a landfill pool and causes secondary pollution. Because the absorbent sodium hydroxide is regenerated by calcium hydroxide, a large amount of Ca is introduced2+So that calcium formation is easy to occur in the absorption equipment, and the continuous and stable operation of the whole system is influenced.
CN1066225, furfural residue activated carbon and application thereof in eliminating and recycling sulfur dioxide in flue gas, and the activated carbon can eliminate the pollution of sulfur dioxide to the atmosphere. But the method recovers sulfur resources to produce the dilute sulfuric acid with low application value of about 30 percent. In addition, when the concentration of the sulfur dioxide exceeds 7000-8000 ppm, the concentration of the sulfur dioxide in the vented tail gas is increased, and the environmental protection requirement is difficult to achieve.
4. The sulfuric acid industry editorial department 1985 published the report on the investigation of the foreign sulfuric acid industry technology introduces the persulfuric acid oxidation method to remove and recover sulfur dioxide from flue gas, and the concentration of sulfur dioxide finally discharged into the atmosphere can be less than or equal to 50 ppm. But the method for recycling the sulfur resource also produces 30-40% dilute sulfuric acid with low application value.
5. In the low-concentration sulfur dioxide flue gas recovery process, a sodium-alkali method which is one of the most widely used methods in the industry at present has strong adaptability to the flue gas concentration, and the tail gas easily meets the environmental protection requirement. The products after absorbing the sulfur dioxide are sodium sulfite and sodium bisulfite, the product has unstable property and not wide application, if the sodium sulfite and the sodium bisulfite are decomposed by sulfuric acid to prepare high-concentration sulfur dioxide, a large amount of sodium sulfate solution is produced as a byproduct, and the application value of the product is not high; if the sulfur dioxide is prepared by heating and decomposing steam, the steam consumption is large and the economical efficiency is poor.
The above is the main technology related to the present invention, and it can be seen that there is no method which can simultaneously have the following characteristics: a. the method has strong adaptability to the concentration of sulfur dioxide in the flue gas, the tail gas can easily meet the environmental protection requirement, and no secondary pollution is generated. b. The sulfur resource in the flue gas can be fully recycled, and industrial raw material products with high value and wide application are produced. c. The process can be operated continuously and stably without factors such as scaling, blockage, short-period replacement of materials and equipment and the like. d. The desulfurization system has good economy or the whole system has better economy after the desulfurization system is arranged.
The invention aims to provide a wet flue gas desulfurization method which has the characteristics and utilizes sodium chloride to treat flue gas containing sulfur dioxide and produce high-concentration sulfur dioxide.
The specific implementation method of the invention is as follows:
1. and (5) an absorption step. The method comprises the following steps of purifying and cooling low-concentration sulfur dioxide gas such as flue gas generated by combustion of sulfur-containing fuel, sulfuric acid production tail gas and smelting flue gas, removing dust, sulfur trioxide and acid mist in the low-concentration sulfur dioxide gas, then enabling the low-concentration sulfur dioxide gas to enter an absorption tower of an absorption process, absorbing the low-concentration sulfur dioxide gas by using 10-35% of sodium hydroxide solution at the temperature of 30-85 ℃, enabling the sulfur dioxide content in the absorbed flue gas to be less than or equal to 20-300 ppm, and enabling. The sodium hydroxide in the absorbent reacts with the sulfur dioxide as follows:
the side reactions that occur in the absorption solution are:
the volume ratio of liquid to gas in the tower is 1-10 l/m3And the gas operation speed in the absorption tower is 0.6-2 m/s.
2. And (5) a decomposition process. The mixed solution of sodium sulfite and sodium bisulfite generated in the absorption procedure reacts with hydrogen chloride gas at the temperature of 120-180 ℃ as follows:
the gas phase after the reaction contains sulfur dioxide, hydrogen chloride, water vapor and hydrogen, wherein a small amount of hydrogen chloride has influence on the deep processing of the sulfur dioxide gas and the extension products taking the sulfur dioxide gas as raw materials and must be removed. In the invention, a 25-38% sodium bisulfite solution is used for washing, and the following reaction occurs during washing:
the washed gas is treated with hydrochloric acid mist and salt solution in a fiber demister to finally prepare sulfur dioxide gas with chlorine content less than or equal to 1.2mg/L and concentration more than or equal to 97 percent, and the sulfur dioxide gas can be directly used as a raw material for preparing liquid sulfur dioxide or producing sulfuric acid.
3. And (5) a purification process. The solution generated in the decomposition process contains a large amount of sodium chloride, sulfur dioxide and a small amount of Ca2+、Mg2+And SO4 2-Ions are removed and the pH is adjusted to meet the requirements of electrolysis in the subsequent step. Adding the solution from the upper part of a desorption tower, introducing clean air from the bottom of the desorption tower, wherein the liquid-gas ratio is 1-100 l/m3The content of sulfur dioxide in the solution after desorption is less than or equal to 0.1g/L, and the wet gas containing sulfur dioxide after desorption is sent to an inlet of an absorption tower in an absorption process. Adding sodium hydroxide solution into the solution which has absorbed sulfur dioxide, and removing Mg in the solution2+The following reactions mainly occur:
The solution after primary purification contains 24 percent of sodium chloride and SO4 2-≤5g/L，SO2≤0.1g/L，Mg2++Ca2+≤0.1mg/L。
The solution after the secondary purification contains 24 percent of sodium chloride and SO4 2-≤5g/L，SO2≤0.1g/L，Mg2++Ca2+Not more than 20 mug/L, not more than 0.1ppm of solid suspended matter, Ba2+≤1ppm。
4. And (5) an electrolysis process. Electrolyzing the purified sodium chloride solution by adopting a diaphragm method or an ion exchange membrane method, wherein the following reactions occur in an electrolytic cell:
5. And a hydrogen chloride step. The hydrogen and chlorine generated in the electrolysis process are used for reacting in a reaction furnace according to the ratio of 1.05-1.1 of hydrogen to chlorine as follows:
FIG. 1 is a schematic process flow diagram of the present invention. The specific process is illustrated as follows:
the method comprises the following steps of purifying and cooling low-concentration sulfur dioxide gas such as flue gas generated by combustion of sulfur-containing fuel, sulfuric acid production tail gas and smelting flue gas, sending the low-concentration sulfur dioxide gas into an absorption tower 1 through a fan 2, firstly conveying 10-35% of sodium hydroxide solution through a pump 5 for absorption, then circularly absorbing the low-concentration sulfur dioxide gas by using an absorption liquid through a pump 3, and discharging the low-concentration sulfur dioxide gas after reaching the standard, wherein the sulfur dioxide content in the flue gas is less than or equal to 20. And (3) the sodium sulfite and the sodium bisulfite generated after absorption enter a circulating tank 4, redundant liquid in the circulating tank 4 overflows to a hydrogen chloride purification tower 9, then flows into a circulating tank 11, is conveyed to a decomposition tower 10 through a pump 12, and reacts with hydrogen chloride gas with the temperature of 120-180 ℃ and the hydrogen content of 1-2%. The surplus liquid in the circulating tank 11 overflows to a desorption tower 13, the wet gas containing sulfur dioxide after desorption enters an inlet of a fan 2, the solution after desorption enters a liquid collecting tank 16, then overflows to a purifying tank 14 from the liquid collecting tank 16, and the bottom flow of the purifying tank 14 is used for preparing barium sulfate. If the diaphragm method is adopted for electrolysis, clear liquid is conveyed to the electrolytic bath 6 by the pump 15; if the ion exchange membrane electrolysis is adopted, the clear liquid needs to be purified for the second time and then sent to the electrolytic cell 6. The sodium hydroxide solution produced in the electrolytic cell 6 is conveyed by the pump 5 to the absorption column 1, in which a small portion is removed to produce sodium hypochlorite. Hydrogen and chlorine generated in the electrolytic cell 6 react in the reaction furnace 7 according to the ratio of 1.05-1.1 to generate hydrogen chloride, and the hydrogen chloride passes through the heat exchanger 8 and then enters the decomposition tower 10. And the redundant chlorine gas of the synthesized hydrogen chloride is used for preparing the sodium hypochlorite during electrolysis. The purification tank 14 is continuously replenished with sodium chloride solution consumed in the process.
Example (b):
the method is used for treating the flue gas containing 3000ppm of secondary development sulfur oxide generated by the coal-fired boiler, and the gas quantity is 60 ten thousand Nm3H, the gas is sent into the absorption tower by a fan 2 after being purified and cooled1, firstly, a 35% sodium hydroxide solution is delivered by a pump 5 for 9m3The absorption is carried out in the per hour, and then the absorption liquid is utilized to circularly absorb by the pump 3, the circulating amount is 600m3And h, the sulfur dioxide content in the absorbed flue gas is less than or equal to 150ppm, and the flue gas is discharged after reaching the standard. And the sodium sulfite and the sodium bisulfite generated after absorption enter a circulating tank 4, redundant liquid in the circulating tank 4 overflows to a hydrogen chloride purifying tower 9, then flows into a circulating tank 11, and reacts with hydrogen chloride gas with the temperature of 120-180 ℃ and the hydrogen content of 1-2% by a decomposition tower 10 conveyed by a pump 12. The surplus liquid in the circulating tank 11 overflows to a desorption tower 13, the wet gas containing sulfur dioxide after desorption enters an inlet of a fan2, the solution after desorption enters a liquid collecting tank 16, then overflows to a purifying tank 14 from the liquid collecting tank 16, and the bottom flow of the purifying tank 14 is used for preparing barium sulfate. The ion exchange membrane electrolysis is adopted, the clear liquid is purified for the second time and then is sent to the electrolytic cell 6, and the power consumption of the electrolytic sodium chloride is about 2200KW for each ton of sulfur dioxide produced. The sodium hydroxide solution produced in the electrolytic cell 6, with a concentration of 35%, is conveyed by the pump 5 to the absorption column 1, in which a small portion is removed to make sodium hypochlorite. Hydrogen and chlorine generated in the electrolytic cell 6 react in a reaction furnace 7 according to the proportion of 1.05-1.1 to generate hydrogen chloride, the hydrogen chloride passes through a heat exchanger 8 and then enters a decomposition tower 10, and 4886kg/h of sulfur dioxide with the concentration of more than 97% is discharged from a washing tower 9.
The invention is suitable for low-concentration sulfur dioxide gas such as flue gas generated by combustion of sulfur-containing fuel, tail gas generated by sulfuric acid production, smelting flue gas and the like, the sulfur dioxide content in the gas can be treated by 500ppm to 5 percent, the adaptability to the concentration of the sulfur dioxide in the flue gas is strong, the tail gas easily meets the environmental protection requirement, and no secondary pollution is generated; the sulfur resource in the flue gas can be fully recycled, and industrial raw material products with high value and wide application are produced; the process can continuously and stably run without factors such as scaling, blockage, short-period material and equipment replacement and the like; the desulfurization system has good economy or the whole system has better economy after being provided with the desulfurization system.
Claims (2)
1. Method for treating flue gas containing sulfur dioxide and producing high-concentration sulfur dioxide by using sodium chloride, and method for producing high-concentration sulfur dioxide by using sodium chloride① the gas is purified and cooled to remove dust, sulfur trioxide and acid mist, then absorbed by 10-35% sodium hydroxide solution generated by sodium chloride electrolysis at 30-85 ℃ to generate a mixed solution of 32-38.5% sodium sulfite and sodium bisulfite, ② hydrogen and chlorine generated by sodium chloride electrolysis are combusted to generate hydrogen chloride, the hydrogen chloride gas is cooled to 120-180 ℃ and then reacts with the mixed solution of ① generated sodium sulfite and sodium bisulfite violently to generate high-concentration sulfur dioxide gas containing a small amount of hydrogen chloride and water vapor at 45-85 ℃, and the high-concentration sulfur dioxide gas is washed by 25-38% sodium bisulfite solution to ensure that the chlorine content is less than or equal to 1.2mg/Nm3Removing acid mist by a mist removing device to ensure that the content of the acid mist is less than or equal to 30mg/Nm3Then dried by 93-98% concentrated sulfuric acid to ensure that the water content is less than or equal to 0.1g/Nm3③ step ②, the solution of hydrogen chloride after reacting with the mixed solution of sodium sulfite and sodium bisulfite contains large amount of sodium chloride and dissolves large amount of sulfur dioxide, clean air is used to desorb the solution to make the content of sulfur dioxide in the solution less than 0.1g/L, the desorbed gas containing sulfur dioxide is returned to the purified flue gas in step ① for reabsorption, the sodium chloride solution after desorbing sulfur dioxide is purified to remove Ca2 +、Mg2 +And SO4 2-After the ion treatment, sodium hydroxide, which is an absorbent for sulfur dioxide gas in step ①, chlorine gas and hydrogen gas, which are raw materials for synthesizing hydrogen chloride in step ②, are produced by electrolysis using a diaphragm method or an ion exchange membrane method.
2. The method for treating sulfur dioxide-containing flue gas and producing high-concentration sulfur dioxide by using sodium chloride as claimed in claim 1, wherein barium chloride is used to remove SO in procedure ③4 2-Ions are generated to generate barium sulfate,separating, washing, dehydrating and drying to obtain the medical barium sulfate.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 01113697 CN1225303C (en) | 2001-06-18 | 2001-06-18 | Method for controlling flue gas contaiing SO2 with NaCl and producing high concentratino SO2 |
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| CN 01113697 CN1225303C (en) | 2001-06-18 | 2001-06-18 | Method for controlling flue gas contaiing SO2 with NaCl and producing high concentratino SO2 |
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| CN1225303C CN1225303C (en) | 2005-11-02 |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100361731C (en) * | 2003-12-14 | 2008-01-16 | 徐宝安 | Equipment of desulfurizing fume by alkalifying method, through dissolved in cold water and electrolysis of removing hard water |
| CN101318633B (en) * | 2008-06-12 | 2010-08-18 | 江苏中兴化工设备有限公司 | Method for producing sulphuric acid with SO2 containing coal-fired boiler flue gas |
| CN104998534A (en) * | 2015-06-26 | 2015-10-28 | 潜江海为化学科技有限公司 | Recovery method for sulfonyl chloride chlorination reaction tail gas |
| CN105903327A (en) * | 2016-06-14 | 2016-08-31 | 赵劲松 | Device achieving dedusting, desulfuration and denitration by means of acid and alkali potential water |
| CN109020839A (en) * | 2018-10-29 | 2018-12-18 | 吴江 | A kind of ammonolysis ethylenehydrinsulfonic acid sodium prepares taurine utilization process |
| CN110102169A (en) * | 2019-06-12 | 2019-08-09 | 禄丰天宝磷化工有限公司 | Exhaust treatment system in a kind of sulfuric acid preparation process |
| CN113941227A (en) * | 2021-11-26 | 2022-01-18 | 西安西热水务环保有限公司 | Method and system for selectively removing HCl in flue gas |
-
2001
- 2001-06-18 CN CN 01113697 patent/CN1225303C/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100361731C (en) * | 2003-12-14 | 2008-01-16 | 徐宝安 | Equipment of desulfurizing fume by alkalifying method, through dissolved in cold water and electrolysis of removing hard water |
| CN101318633B (en) * | 2008-06-12 | 2010-08-18 | 江苏中兴化工设备有限公司 | Method for producing sulphuric acid with SO2 containing coal-fired boiler flue gas |
| CN104998534A (en) * | 2015-06-26 | 2015-10-28 | 潜江海为化学科技有限公司 | Recovery method for sulfonyl chloride chlorination reaction tail gas |
| CN105903327A (en) * | 2016-06-14 | 2016-08-31 | 赵劲松 | Device achieving dedusting, desulfuration and denitration by means of acid and alkali potential water |
| CN109020839A (en) * | 2018-10-29 | 2018-12-18 | 吴江 | A kind of ammonolysis ethylenehydrinsulfonic acid sodium prepares taurine utilization process |
| CN109020839B (en) * | 2018-10-29 | 2021-06-29 | 吴江 | Recycling process for preparing taurine by ammonolysis of hydroxyethanesulfonic acid sodium |
| CN110102169A (en) * | 2019-06-12 | 2019-08-09 | 禄丰天宝磷化工有限公司 | Exhaust treatment system in a kind of sulfuric acid preparation process |
| CN113941227A (en) * | 2021-11-26 | 2022-01-18 | 西安西热水务环保有限公司 | Method and system for selectively removing HCl in flue gas |
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