CN112755750A - Method for reducing sodium sulfate generation in boiler dual-alkali desulfurization process - Google Patents

Method for reducing sodium sulfate generation in boiler dual-alkali desulfurization process Download PDF

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Publication number
CN112755750A
CN112755750A CN202110051646.2A CN202110051646A CN112755750A CN 112755750 A CN112755750 A CN 112755750A CN 202110051646 A CN202110051646 A CN 202110051646A CN 112755750 A CN112755750 A CN 112755750A
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sodium sulfate
alkali
reduced
eluent
double
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CN202110051646.2A
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霍晓光
霍成斌
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Tonghua Jinshan Yinshan Environmental Protection Equipment Manufacturing Co ltd
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Tonghua Jinshan Yinshan Environmental Protection Equipment Manufacturing 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
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
    • 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
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/504—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/30—Alkali metal compounds
    • B01D2251/304—Alkali metal compounds of sodium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/60—Inorganic bases or salts
    • B01D2251/604—Hydroxides
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Treating Waste Gases (AREA)

Abstract

The invention relates to the field of boiler flue gas treatment, in particular to a method for reducing the generation of sodium sulfate in the process of boiler dual-alkali desulfurization. Adapted for SO2The reaction with the basic substance or in the alkaline solution. A cooling device is arranged on a double-alkali water tank of a desulfurization elution tower body, and the sprayed eluent enters the cooling device and then enters the double-alkali water tank, so that the temperature of the eluent in the double-alkali water tank is kept between 25 and 35 ℃, the oxidation activity of oxygen is reduced, and the generation of sodium sulfate is reduced. By lowering the temperature of the eluent, the generation of sodium sulfate can be reduced. The temperature of the eluent is kept between 25 ℃ and 35 ℃, the oxidation activity of oxygen is reduced to the minimum, the sodium sulfate is greatly reduced, the discharge of the eluent is reduced, the use amount of sodium hydroxide and the oxygen inhibitor is saved, and the desulfurization cost is reduced.

Description

Method for reducing sodium sulfate generation in boiler dual-alkali desulfurization process
Technical Field
The invention relates to the field of boiler flue gas treatment, in particular to a method for reducing the generation of sodium sulfate in the process of boiler dual-alkali desulfurization. Is suitable for the pollution treatment technology (wet flue gas desulfurization technology) for removing SO2 by adopting a double-alkali method, namely sodium hydroxide and calcium hydroxide.
Background
In the prior art, the flue gas desulfurization technology is a boiler flue gas purification technology. SO in flue gas2Substantially acidic, and can be removed from flue gases by the sodium hydroxide-based double-alkali process
SO removal of boiler waste gas2The limestone method and the double-alkali method are commonly used, the method is mature, and the good removal rate can reach about 90 percent. Limestone processes, because of their relatively low cost, are used relatively much, especially in large boilers operated continuously, which are essentially limestone desulfurization. However, the double alkali method is more suitable for medium and small boilers, particularly for batch operation boilers.
The two-base process is derived from the desulfurization technology of the U.S. general automobile company. Most of domestic desulfurization towers adopting two-to-four-layer nozzles to spray double-alkali eluent to form two-to-four-layer water curtains, boiler waste gas rises upwards from the bottom of the desulfurization tower, and the waste gas passes through the spraying water curtains to complete elution. In practice, the light is far from sufficient by spray elution, and under the impact of the waste gas with the speed of at least two to three meters per second or even higher, a spray water curtain can be curled up and deformed, which cannot be intact, and a part of the waste gas can not contact with the water curtain. The method is one of the reasons that the conventional desulfurizing tower cannot realize zero emission of SO 2.
In the process of desulfurization and elution by the double alkali method, the production of sodium sulfate can not be controlled, the cost is high, and otherwise, the cost is greatly reduced. The main raw material sodium hydroxide in the double-alkali eluent reacts with SO2 to generate sodium sulfite, calcium hydroxide is added, most of the sodium sulfite is regenerated into sodium hydroxide, and a few sodium sulfite is oxidized into sodium sulfate by oxygen. Sodium in sodium sulfate is derived from sodium hydroxide, and the more sodium sulfate is produced, the more sodium hydroxide is lost. Wu' an scholars "practical technical design for wet flue gas desulfurization in Industrial boiler" page 99 points out: "in order to prevent natural oxidation of Na2SO3, the oxygen-resisting agent p-phenylenediamine and hydroquinone can be added into the absorption liquid". The wuan scholars teach that when the two-base method is followed by addition of an oxygen-blocking agent, the oxidation will also produce 5% sodium sulfate per hour. That is, the sodium hydroxide charged in 20 hours was completely oxidized. Thus, what we say is that the "double base process can recycle sodium hydroxide" is greatly discounted. The solution proposed by wu' an scholars is to discharge 5% of the dibasic solution every hour, and simultaneously supplement an equal amount of new dibasic solution, always keeping the proportion of sodium sulfate below 5%. Sodium sulfate in discharged double alkali liquor only accounts for 5 percent, while sodium hydroxide accounts for most of the discharged double alkali liquor, and the discharged double alkali liquor is the main reason of sodium hydroxide loss. The book of flue gas desulfurization and denitration technology by Xiaojie is also pointed out: when the concentration of Na2SO4 reaches 5%, a part of mother liquor must be discharged, and a part of fresh lye must be replenished. The rest of textbooks avoid saying how to solve the problem of sodium sulfate. This problem is not solved, and the dual alkali desulfurization is not acceptable in terms of cost. Not only sodium sulfate generates and loses sodium hydroxide 'money burning', but also the discharged double alkali liquor loses sodium hydroxide 'money burning'. Especially, the extra-discharge double alkali liquor is the most serious in 'money burning'.
The eluent continuously elutes the smoke gas at 100-200 ℃, and the temperature of the eluent can reach as high as 80-90 ℃. The higher the temperature of the eluent is, the higher the oxidation activity of oxygen in the eluent is, the more sodium sulfate is generated by oxidation, the more sodium sulfate needs to be discharged, and the elution cost is increased.
In addition, sodium hydroxide and sulfur dioxide produce sodium sulfite, and calcium hydroxide is added to change into calcium sulfite. Calcium sulfite is unstable, and if calcium sulfite is removed by precipitation, the discharged sodium sulfite can be subjected to calcium-sulfur separation under certain conditions, so that secondary pollution is caused. Therefore, in the traditional desulfurization process, a double-alkali water tank is arranged below a desulfurization tower, air is sent to the double-alkali water tank by an oxidation fan while desulfurization is carried out, and calcium sulfite in double alkali liquid is oxidized into calcium sulfate. The disadvantage of this process is that the larger the air supply, the more oxygen, and the more sodium sulfite in the brackish water is oxidized to sodium sulfate.
Disclosure of Invention
The invention aims to provide a method for reducing the generation of sodium sulfate in the process of boiler dual-alkali desulfurization, which can reduce the desulfurization cost.
The technical solution of the invention is as follows: a method for reducing the generation of sodium sulfate in the process of boiler dual-alkali desulfurization is characterized in that a cooling device is arranged on a dual-alkali water tank of a desulfurization elution tower body, and the sprayed eluent enters the cooling device and then enters the dual-alkali water tank, so that the temperature of the eluent in the dual-alkali water tank is kept between 25 and 35 ℃, the oxidation activity of oxygen is reduced, and the generation of sodium sulfate is reduced.
The invention has the advantages that: 1. by lowering the temperature of the eluent, the generation of sodium sulfate can be reduced. The temperature of the eluent is kept between 25 ℃ and 35 ℃, the oxidation activity of oxygen is reduced to the minimum, the sodium sulfate is greatly reduced, the discharge of the eluent is reduced, the use amount of sodium hydroxide and the oxygen inhibitor is saved, and the desulfurization cost is reduced. 2. The method is characterized in that an oxidation fan is not used for conveying oxygen into the double-alkali water solution in the double-alkali water pool, and the oxidation process of the calcium sulfite is carried out in the concentrated solution after the concentration of the cyclone.
Embodiments of the present invention are described in further detail below.
Detailed Description
A method for reducing the generation of sodium sulfate in the process of boiler dual-alkali desulfurization is characterized in that a cooling device is arranged on a dual-alkali water tank of a desulfurization elution tower body, and the sprayed eluent enters the cooling device and then enters the dual-alkali water tank, so that the temperature of the eluent in the dual-alkali water tank is kept between 25 and 35 ℃, the oxidation activity of oxygen is reduced, and the generation of sodium sulfate is reduced.
According to the detection result, after the temperature of the eluent is reduced to 25-35 ℃, the generated sodium sulfate is less than the former 40 percent. By combining the application, barium sulfate and other barium-containing substances are adopted to precipitate and remove the sodium sulfate, double loss of discharged double alkali liquor is avoided, the loss of sodium hydroxide is reduced by more than 80% through calculation of the input amount, and the problem of money burning of the sodium sulfate is solved well. The double alkali desulfurization is considered to be high in cost, and the main point is that the material of the double alkali method is sodium hydroxide, the material of the limestone method is limestone, and the price of the two materials is greatly different. However, the sodium hydroxide used in the dual alkali process of the present invention is also very different in "amount" from the limestone used in the limestone process. The dual-alkali desulfurization cost of the invention is lower than that of the traditional limestone method, and the dual-alkali desulfurization is more convenient to popularize.
Experimental example 1
The application adopts an ion chromatograph to detect the sodium sulfate of different temperatures of the eluent. According to the detection result (the national center for electrochemical and spectral research analysis and test report sheet, report number GP-20-0325): running at 80 deg.C for 2 hr to obtain 3.3174% sodium sulfate solution (A sample) with sodium sulfate content of 33.174 mg/ml; running at 70 deg.C for 2 hr to obtain sodium sulfate 26.258mg/ml (B sample, 2.6258%;) in the double alkali solution, and running at 60 deg.C for 2 hr to obtain sodium sulfate 22.725mg/ml (C sample, 2.2725%); running at 50 deg.C for 2 hr, and sodium sulfate content of 18.451mg/ml (D sample) is 1.8451%; run at 40 ℃ for 2 hours with a sodium sulfate content of 16.176mg/ml (E sample), 1.6176%; run at 30 ℃ for 2 hours with a sodium sulfate content of 15.116 mg/ml (F sample), 1.5116%.
At the same time, the oxygen transmission into the double-alkali eluent is reduced to the maximum extent. In the elution process, sodium hydroxide and SO2The reaction generates sodium sulfite, calcium sulfite is generated by adding calcium hydroxide, the calcium sulfite is unstable, calcium and sulfur are separated under certain conditions, secondary pollution occurs, and the calcium sulfite is required to be oxidized into calcium sulfate to be discharged. In the traditional limestone method and double alkali method desulfurization designs, an oxidation fan or an aerator is designed in an elution tank at the lower part of a desulfurization tower, air is fed in 24 hours a day, calcium sulfate is generated by oxidation, and for the double alkali method, the more sodium sulfate is generated by oxidation. The Baixin project does not supply air to the elution pool, but separates the eluent into supernatant and concentrated solution in the cyclone, the supernatant returns to the elution pool, and aeration is carried out in the concentrated solution tank to oxidize the calcium sulfite in the supernatant into calcium sulfate. By the design, the concentrated solution is only about one tenth of the double-alkali water solution, and the sodium sulfite is one tenth of the double-alkali pool, so that the generation of sodium sulfate can be greatly reduced.
Mineral fine powder natural barium sulfate can also be added into the double-alkali liquid pool, and the liquid-solid ratio of the sodium sulfate to the barium sulfate is 1.3: 1, the sodium sulfate is used for precipitating the sodium sulfate, and finally the sodium sulfate and the calcium sulfate generated by desulfurization are concentrated, dehydrated and removed together, so that the storage amount of the sodium sulfate in the alkali liquor is reduced, and the double alkali liquor obtained after dehydration is continuously recycled without being discharged.
The sodium sulfate is removed by adopting a precipitation method, the sodium sulfate in the alkali liquor is removed in time, the accumulation is avoided, the existence of the sodium sulfate is reduced, the double alkali liquor is not discharged, and the most main loss of the sodium hydroxide caused by the discharged double alkali liquor is recovered. According to the invention, 2 yuan more than one kilogram of mineral fine powder natural barium sulfate (the price is cheaper than barium chloride and barium sulfate) is added into a double-alkali liquid pool, the mineral fine powder natural barium sulfate and calcium sulfate generated by desulfurization are concentrated, dehydrated and removed, and the double-alkali liquid obtained after dehydration is continuously recycled without discharge.
If an oxygen inhibitor for effectively inhibiting the generation of sodium sulfate is developed, sodium hydroxide can really become 'recycled after regeneration', the only cost of the double-alkali desulphurization is the oxygen inhibitor, and the limestone method can completely exit the history stage.
Experimental example 2
The results of field detection of smoke dust of a boiler (which is in work with the applicant) in the general public communications pharmaceutical industry by Jilin province metallurgy research institute are as follows (sampling point boiler outlet): smoke dust 3.13mg/m3Sulfur dioxide less than 3mg/m3Nitrogen oxides less than 3mg/m3Oxygen content of 19.6 percent and flue gas flow of 9416m3H is used as the reference value. All reach the standard.
The foregoing description is only exemplary of the invention and is not intended to limit the spirit of the invention.

Claims (1)

1. A method for reducing the generation of sodium sulfate in the process of boiler dual-alkali desulfurization is characterized in that a cooling device is arranged on a dual-alkali water tank of a desulfurization elution tower body, and the sprayed eluent enters the cooling device and then enters the dual-alkali water tank, so that the temperature of the eluent in the dual-alkali water tank is kept between 25 and 35 ℃, the oxidation activity of oxygen is reduced, and the generation of sodium sulfate is reduced.
CN202110051646.2A 2020-12-21 2021-01-15 Method for reducing sodium sulfate generation in boiler dual-alkali desulfurization process Pending CN112755750A (en)

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CN202011514971 2020-12-21

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07284632A (en) * 1994-04-19 1995-10-31 Mitsubishi Heavy Ind Ltd Method for removing low-concentration sulfur dioxide and device therefor
JPH10230129A (en) * 1997-02-21 1998-09-02 Chiyoda Corp Flue gas desulfurization method and flue gas desulfurizing device
CN1712113A (en) * 2005-06-03 2005-12-28 吴金泉 Smoke desulfidation from amino bialkali method
EP2353701A1 (en) * 2010-01-27 2011-08-10 Hitachi Power Europe GmbH Waste gas cleaner with cooling tower
WO2012147466A1 (en) * 2011-04-28 2012-11-01 川崎重工業株式会社 Wet desulfurization apparatus and method for operating said wet desulfurization apparatus
CN106669326A (en) * 2017-01-20 2017-05-17 东南大学 Wet desulfurization synergized fine particle and SO3 acid mist removing method and device
CN208553732U (en) * 2018-07-10 2019-03-01 中瑞工程设计院有限公司 A kind of white system of Novel tobacco qi exhaustion that flue gas is directly cooling
CN209317434U (en) * 2018-07-24 2019-08-30 福建龙净环保股份有限公司 A kind of circulating treating system of wet desulphurization slurry
CN211487169U (en) * 2019-12-13 2020-09-15 济南裕兴化工有限责任公司 Sodium-alkali method desulphurization device

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07284632A (en) * 1994-04-19 1995-10-31 Mitsubishi Heavy Ind Ltd Method for removing low-concentration sulfur dioxide and device therefor
JPH10230129A (en) * 1997-02-21 1998-09-02 Chiyoda Corp Flue gas desulfurization method and flue gas desulfurizing device
CN1712113A (en) * 2005-06-03 2005-12-28 吴金泉 Smoke desulfidation from amino bialkali method
EP2353701A1 (en) * 2010-01-27 2011-08-10 Hitachi Power Europe GmbH Waste gas cleaner with cooling tower
WO2012147466A1 (en) * 2011-04-28 2012-11-01 川崎重工業株式会社 Wet desulfurization apparatus and method for operating said wet desulfurization apparatus
CN106669326A (en) * 2017-01-20 2017-05-17 东南大学 Wet desulfurization synergized fine particle and SO3 acid mist removing method and device
CN208553732U (en) * 2018-07-10 2019-03-01 中瑞工程设计院有限公司 A kind of white system of Novel tobacco qi exhaustion that flue gas is directly cooling
CN209317434U (en) * 2018-07-24 2019-08-30 福建龙净环保股份有限公司 A kind of circulating treating system of wet desulphurization slurry
CN211487169U (en) * 2019-12-13 2020-09-15 济南裕兴化工有限责任公司 Sodium-alkali method desulphurization device

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