WO2021134926A1 - 利用二氧化氯脱硫脱硝的方法 - Google Patents

利用二氧化氯脱硫脱硝的方法 Download PDF

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WO2021134926A1
WO2021134926A1 PCT/CN2020/080338 CN2020080338W WO2021134926A1 WO 2021134926 A1 WO2021134926 A1 WO 2021134926A1 CN 2020080338 W CN2020080338 W CN 2020080338W WO 2021134926 A1 WO2021134926 A1 WO 2021134926A1
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flue gas
chlorine dioxide
desulfurization
gas
denitrification
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PCT/CN2020/080338
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English (en)
French (fr)
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童裳慧
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童裳慧
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Priority to US17/628,798 priority Critical patent/US20220274057A1/en
Priority to JP2022503897A priority patent/JP2022541800A/ja
Publication of WO2021134926A1 publication Critical patent/WO2021134926A1/zh

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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
    • B01D53/60—Simultaneously removing sulfur oxides and nitrogen oxides
    • 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
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/108—Halogens or halogen compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/11—Air
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/40—Alkaline earth metal or magnesium compounds
    • B01D2251/404—Alkaline earth metal or magnesium compounds of calcium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/60—Inorganic bases or salts
    • B01D2251/602—Oxides
    • 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
    • B01D2257/00—Components to be removed
    • B01D2257/30—Sulfur compounds
    • B01D2257/302—Sulfur oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/40—Nitrogen compounds
    • B01D2257/404—Nitrogen oxides other than dinitrogen oxide
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/12—Methods and means for introducing reactants
    • B01D2259/122—Gaseous reactants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/12—Methods and means for introducing reactants
    • B01D2259/128—Solid reactants
    • 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
    • B01D53/75—Multi-step processes
    • 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
    • B01D53/76—Gas phase processes, e.g. by using aerosols
    • 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
    • B01D53/81—Solid phase processes
    • B01D53/83—Solid phase processes with moving reactants

Definitions

  • the invention relates to a method for desulfurization and denitration using chlorine dioxide.
  • Coal-fired flue gas contains a large amount of harmful gases such as sulfur dioxide and nitrogen oxides, which have caused indelible damage to the atmospheric environment, such as acid rain and photochemical smog.
  • harmful gases such as sulfur dioxide and nitrogen oxides
  • the effective removal of sulfur dioxide and nitrogen oxides in flue gas has always been the research focus of researchers, especially the removal of NO as the research difficulty.
  • Chlorine dioxide in gas-phase oxidants has attracted much attention due to its strong oxidizing properties, and has been widely used in denitrification projects in recent years. Chlorine dioxide gas is unstable in nature, easy to explode, and difficult to store and transport.
  • CN106621712A discloses a flue gas desulfurization and denitrification method.
  • an ozone generator is used to prepare ozone to oxidize NO in the flue gas to form high-valence nitrogen oxides, and then oxidize sulfur dioxide and high-valence nitrogen through an absorption liquid
  • the integrated removal of substances is carried out to achieve the purpose of flue gas purification.
  • ozone has high efficiency in oxidizing NO and its removal effect is obvious, the ozone generator is expensive, covers a large area, and the initial cost is relatively high.
  • CN104028103A discloses a method for simultaneously performing desulfurization and denitration by using liquid phase chlorine dioxide to catalyze and oxidize flue gas.
  • the chlorine dioxide aqueous solution is generated by the chlorine dioxide preparation device with a concentration of 0.0015 to 0.015 mol/L, sprayed in the absorption tower to oxidize the NO in the flue gas.
  • the tower volume and initial equipment investment are increased, which increases the difficulty of process implementation.
  • CN106975337A discloses an integrated process using chlorine dioxide gas phase oxidation desulfurization and denitration. Both the chlorine dioxide oxidation step and the desulfurization and denitration step occur in the absorption tower. After the flue gas is sprayed by the desulfurizer, the chlorine dioxide sprayed through the gasification spray pipe, NO is oxidized to high-valence nitrogen oxides, and then The denitrification agent on the upper layer of the board is removed by spraying. Chlorine dioxide can react with desulfurizer, which not only causes waste of chlorine dioxide and desulfurization absorbent, but also affects desulfurization efficiency.
  • an object of the present invention is to provide a method for desulfurization and denitration using in-situ synthesized chlorine dioxide.
  • the method has high desulfurization and denitration efficiency, simple process and low cost.
  • the present invention adopts the following technical solutions to achieve the above objectives.
  • the present invention provides a method for desulfurization and denitration using chlorine dioxide, which includes the following steps:
  • the chlorate is sodium chlorate; wherein the concentration of the sodium chlorate aqueous solution is 15-40 wt%, and the concentration of the sulfuric acid aqueous solution is 30-60 wt%.
  • the peroxide solution is 25 to 28 wt% hydrogen peroxide or 34 to 38 wt% hydrogen peroxide.
  • the molar ratio of chlorate, hydrogen peroxide and sulfuric acid added to the chlorine dioxide generator is 1:0.55-1:0.5-1;
  • the reaction temperature of the chlorine generator is 40-90°C.
  • the sulfur content of flue gas into the flue gas duct is 600 ⁇ 4000mg / Nm 3; nitrogen content 200 ⁇ 600mg / Nm 3; 5 oxygen ⁇ 23wt%; moisture content 5-12wt%.
  • the flow velocity of the flue gas in the flue gas pipe is 6-15m/s; the mixed gas and the flue gas are in contact in the flue gas pipe before entering the desulfurization and denitrification tower The time is 1 ⁇ 3s.
  • the dry powder of the alkaline absorbent is calcium oxide and/or calcium hydroxide; and the particle size of the dry powder of the alkaline absorbent is 150-350 mesh.
  • the flow rate of the oxidized flue gas in the desulfurization and denitrification tower is 1-7 m/s; the flue gas after oxidation and the dry powder of alkaline absorbent are in the desulfurization and denitrification tower
  • the contact time is 2-15s.
  • the molar ratio of calcium in the dry powder of the alkaline absorbent per unit time to sulfur in the flue gas per unit time is Ca/ S, which is 1.1 to 1.5.
  • the molar ratio of the calcium element contained in the dry powder of the alkaline absorbent per unit time to the nitrogen element contained in the flue gas per unit time is Ca /N, which is 0.5 to 1.5.
  • the desulfurization and denitration method of the present invention uses in-situ synthesized chlorine dioxide gas as an oxidant for desulfurization and denitration, and the desulfurization efficiency reaches more than 99%, and the denitration efficiency reaches more than 91%. Furthermore, the chlorine dioxide gas form is adopted, and the consumption of chlorine dioxide is reduced through a specific process method, and the cost is reduced.
  • the invention provides an integrated CFB flue gas desulfurization and denitrification process in which sodium chlorate prepares chlorine dioxide as an oxidant and is then combined with a calcium-based absorbent.
  • the reaction principle is as follows:
  • the method for flue gas desulfurization and denitration of the present invention includes the following steps: (1) a chlorine dioxide gas preparation step; (2) a flue gas oxidation step; and (3) a desulfurization and denitration step.
  • a chlorine dioxide gas preparation step for preparing chlorine dioxide gas.
  • a flue gas oxidation step for oxidation of flue gas.
  • a desulfurization and denitration step for desulfurization and denitration step.
  • the chlorate aqueous solution, the peroxide solution and the sulfuric acid aqueous solution are reacted in a chlorine dioxide generator to obtain chlorine dioxide gas.
  • Chlorine dioxide gas is mixed with air to obtain a mixed gas.
  • the percentage of chlorine dioxide gas in the mixed gas may be 4-10 vol%, preferably 5-8 vol%; more preferably 7-8 vol%.
  • the chlorine dioxide gas and air are mixed in the above-mentioned ratio to increase the conversion rate of nitric oxide on the basis of safe production.
  • the peroxide solution can be selected from hydrogen peroxide and the like.
  • the concentration of hydrogen peroxide in the hydrogen peroxide may be 25-28 wt%, preferably 26-28 wt%, more preferably 27-28 wt%.
  • the concentration of hydrogen peroxide in the hydrogen peroxide may also be 34-38 wt%, preferably 34.5-37 wt%, more preferably 35-36 wt%. Using peroxides in the above concentration range can control the reaction rate and improve the safety of chlorine dioxide gas production.
  • the chlorate salt may be selected from one of sodium chlorate, potassium chlorate and magnesium chlorate; preferably, the chlorate salt is selected from one of sodium chlorate or potassium chlorate; more preferably, the chlorate salt is sodium chlorate.
  • the molar ratio of sodium chlorate in the chlorate aqueous solution added to the chlorine dioxide generator, hydrogen peroxide in the hydrogen peroxide solution and sulfuric acid in the sulfuric acid aqueous solution is 1:0.55 to 1:0.5 to 1, preferably 1:0.6 to 1:0.6-1, more preferably 1:0.7-1:0.7-1.
  • the reaction temperature of the chlorine dioxide generator is 50 to 90°C, preferably 60 to 80°C, and more preferably 70 to 80°C.
  • the chlorine dioxide gas produced by the chlorine dioxide generator and the added air are mixed in the chlorine dioxide generator to form a mixed gas, and the mixed gas is output through the induced draft fan.
  • the mixed gas and the flue gas are contacted in the flue gas pipeline before entering the desulfurization and denitrification tower to obtain the oxidized flue gas.
  • the molar ratio of chlorine dioxide in the mixed gas passing into the flue gas duct to the nitrogen monoxide contained in the flue gas per unit time can be 1 to 1.8, preferably 1.1 to 1.6, and more preferably 1.2 to 1.5. Using the above molar ratio can increase the oxidation rate of nitric oxide on the basis of saving the amount of chlorine dioxide.
  • the chlorine dioxide gas produced by the chlorine dioxide generator and the added air are mixed in the chlorine dioxide generator to form a mixed gas, and the mixed gas is output through the induced draft fan and then input to the flue gas pipeline It is in contact with the flue gas in the flue gas pipe.
  • the molar ratio of chlorine dioxide in the mixed gas passing into the flue gas pipeline to the nitrogen monoxide contained in the flue gas per unit time is 1.2-1.5.
  • Sulfur content of flue gas into the flue gas duct may be 600 ⁇ 4000mg / Nm 3, preferably 1000 ⁇ 3000mg / Nm 3, more preferably 1500 ⁇ 2500mg / Nm 3.
  • the nitrogen content of the flue gas entering the flue gas duct (the nitrogen content is the nitric oxide content) can be 200-600 mg/Nm 3 , preferably 200-400 mg/Nm 3 , more preferably 220-250 mg/Nm 3 .
  • the oxygen content of the flue gas entering the flue gas duct may be 5 to 23 wt%, preferably 10 to 20 wt%, and more preferably 15 to 20 wt%.
  • the moisture content of the flue gas entering the flue gas duct may be 5-12% by weight, preferably 8-12% by weight, more preferably 10-12% by weight.
  • flue gas sulfur content, nitrogen content, oxygen content and moisture content can help improve the desulfurization and denitrification effect of flue gas.
  • the flow velocity of the flue gas in the flue gas duct may be 6-15 m/s, preferably 8-15 m/s, more preferably 10-12 m/s.
  • the contact time between the mixed gas and the flue gas in the flue gas pipeline before entering the desulfurization and denitrification tower can be 1 to 3 seconds.
  • the dust content of the flue gas may be 80-200 mg/Nm 3 , preferably 100-150 mg/Nm 3 , more preferably 120-150 mg/Nm 3 .
  • the flue gas is subjected to pre-dust removal treatment before passing into the flue gas pipe, so that the pre-dust flue gas is passed into the flue gas pipe.
  • the invention uses an electrostatic precipitator to pre-clean the flue gas.
  • the oxidized flue gas is passed into the desulfurization and denitration tower and mixed with the sprayed alkaline absorbent dry powder, and water is sprayed into the desulfurization and denitration tower to obtain desulfurization and denitration flue gas.
  • the dry powder of the alkaline absorbent is calcium oxide and/or calcium hydroxide.
  • the dry powder of the alkaline absorbent is calcium oxide and/or calcium hydroxide. More preferably, the dry powder of the alkaline absorbent is hydroxide. calcium.
  • the purity of calcium oxide may be 80 to 99 wt%, preferably 80 to 95 wt%, and more preferably 80 to 90 wt%.
  • the purity of calcium hydroxide may be 80 to 99 wt%, preferably 80 to 95 wt%, and more preferably 80 to 90 wt%.
  • the particle size of the dry powder of the alkaline absorbent may be 150-350 mesh, preferably 200-350 mesh, more preferably 200-300 mesh. Adopting the alkaline absorbent in the above particle size range for dry absorption can improve the desulfurization and denitrification effect.
  • the flow rate of the flue gas in the desulfurization and denitration tower after oxidation may be 1-7 m/s, preferably 2-5 m/s, more preferably 3-4 m/s.
  • the time for the oxidized flue gas to contact the dry powder of the alkaline absorbent in the desulfurization and denitration tower can be 2-15s, preferably 3-12s, more preferably 5-10s.
  • the molar ratio of the calcium element contained in the dry powder of the alkaline absorbent per unit time to the sulfur element contained in the flue gas per unit time is Ca/S, which can be 1.1-1.5, preferably 1.2-1.5, more Preferably it is 1.2-1.3.
  • the molar ratio of the calcium element contained in the dry powder of the alkaline absorbent per unit time to the nitrogen element contained in the flue gas per unit time is Ca/N, which can be 0.5-1.5, preferably 0.5-1.0, more Preferably it is 0.6-0.8. Adopting the above-mentioned Ca/N molar ratio improves the denitration efficiency on the basis of cost saving.
  • the temperature of the flue gas after oxidation at the inlet of the desulfurization and denitration tower may be 110-200°C, preferably 110-180°C, more preferably 120-150°C.
  • the desulfurization and denitration flue gas is dedusted by the bag filter on the top of the desulfurization and denitration tower, the purified flue gas is discharged from the chimney, and the obtained solid ash is transported to the ash storage tank or sprayed into the desulfurization and denitrification
  • the inside of the tower is reused as the dry powder of the alkaline absorbent.
  • a metering pump is used to transport the sodium chlorate aqueous solution, hydrogen peroxide and sulfuric acid aqueous solution to the chlorine dioxide generator for reaction to obtain chlorine dioxide gas, which is mixed with the air introduced into the chlorine dioxide generator to obtain the mixed gas, and passes through the induced draft fan Input into the flue gas pipe.
  • the flue gas is dedusted by the electrostatic precipitator and then passed into the flue gas pipeline; the mixed gas input by the induced draft fan is contacted in the flue gas pipeline to oxidize the nitric oxide in the flue gas to obtain nitrogen oxides, and to obtain the oxidized flue gas.
  • the oxidized flue gas is passed into the desulfurization and denitrification tower, mixed with the dry calcium hydroxide powder sprayed into the desulfurization and denitrification tower, and then water is sprayed into the desulfurization and denitrification tower to remove nitrogen oxides and sulfur dioxide in the oxidized flue gas , Obtain desulfurization and denitration flue gas.
  • the above method is applied to the 90m 2 sintering machine desulfurization and denitration project, and the operating parameters are shown in Table 1.
  • the desulfurization and denitrification flue gas is dedusted by the bag filter at the top of the desulfurization and denitration tower, and the purified flue gas parameters obtained are shown in Table 2.
  • Example 4 In this comparative example, except for the operating parameters in Table 3, the remaining operating parameters are the same as in Example 1.
  • the purified flue gas parameters obtained in this comparative example are shown in Table 4.

Abstract

一种利用二氧化氯脱硫脱硝的方法，包括如下步骤：（1）将氯酸盐水溶液、过氧化物溶液和硫酸水溶液混合加入二氧化氯发生器中反应，获得二氧化氯气体；将二氧化氯气体与空气混合获得混合气体；其中，二氧化氯气体占混合气体的4～10vol％；（2）将混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触，获得氧化后烟气；其中，单位时间内通入烟气管道的混合气体中的二氧化氯与烟气中含有的一氧化氮的摩尔比为1～1.8；（3）将氧化后烟气通入脱硫脱硝塔内与喷入的碱性吸收剂干粉混合，且向脱硫脱硝塔内喷淋水，获得脱硫脱硝烟气。

Description

利用二氧化氯脱硫脱硝的方法 技术领域
本发明涉及一种利用二氧化氯脱硫脱硝的方法。
背景技术
燃煤烟气中含有大量的二氧化硫和氮氧化物等有害气体，对大气环境造成了不可磨灭的损伤，例如酸雨、光化学烟雾等。烟气中二氧化硫和氮氧化物的有效脱除一直以来都是研究者们的研究重点，尤其以NO的脱除为研究难点。
在烟气脱硝时，需要将烟气中NO先氧化成高价氮氧化物，该氧化过程需要氧化剂的参与。气相氧化剂中的二氧化氯因其强氧化性备受关注，在近几年的脱硝工程中多有应用。二氧化氯气体性质不稳定，容易发生爆炸，难以储存和运输。
CN106621712A公开了一种烟气脱硫脱硝方法，通过添加强氧化系统，利用臭氧发生器制备臭氧对烟气中的NO进行氧化形成高价态的氮氧化物，然后经吸收液对二氧化硫和高价态氮氧化物进行一体化脱除，达到烟气净化目的。虽然臭氧氧化NO效率高，脱除效果明显，但臭氧发生器价格昂贵，占地面积大，前期成本投入较高。
CN104028103A公开了一种利用液相二氧化氯催化氧化烟气同时进行脱硫脱硝的方法。二氧化氯水溶液由二氧化氯制备装置生成，浓度为0.0015～0.015mol/L，在吸收塔内进行喷淋，用以氧化烟气中的NO。但是，由于二氧化氯的浓度低，喷淋量较大，增大了塔体积及前期设备投资，增大了工艺实施的难度。
CN106975337A公开了一种利用二氧化氯气相氧化脱硫脱硝一体化的工艺。二氧化氯氧化步骤和脱硫脱硝步骤均在吸收塔内发生，烟 气经脱硫剂喷淋后，经过气化喷雾管喷出的二氧化氯，NO被氧化为高价态氮氧化物，然后在隔板上层的脱硝剂喷淋作用下被脱除。二氧化氯与脱硫剂可反应，不仅造成二氧化氯和脱硫吸收剂的浪费，还影响脱硫效率。
由此，研发一种能够利用二氧化氯进行低能耗、高效率的脱硫脱硝工艺，是十分必要的。
发明内容
有鉴于此，本发明的一个目的在于提供一种利用原位合成的二氧化氯脱硫脱硝的方法。该方法脱硫脱硝效率高，工艺简单、成本低。
本发明采用如下技术方案实现上述目的。
本发明提供一种利用二氧化氯脱硫脱硝的方法，包括如下步骤：
(1)将氯酸盐水溶液、过氧化物溶液和硫酸水溶液混合加入二氧化氯发生器中反应，获得二氧化氯气体；将二氧化氯气体与空气混合获得混合气体；其中，二氧化氯气体占混合气体的4～10vol％；
(2)将混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触，获得氧化后烟气；其中，单位时间内通入烟气管道的混合气体中的二氧化氯与烟气中含有的一氧化氮的摩尔比为1～1.8；
(3)将氧化后烟气通入脱硫脱硝塔内与喷入的碱性吸收剂干粉混合，且向脱硫脱硝塔内喷淋水，获得脱硫脱硝烟气。
根据本发明所述的方法，优选地，步骤(1)中，氯酸盐为氯酸钠；其中，氯酸钠水溶液的浓度为15～40wt％，硫酸水溶液的浓度为30～60wt％。
根据本发明所述的方法，优选地，步骤(1)中，过氧化物溶液为25～28wt％的双氧水或者34～38wt％的双氧水。
根据本发明所述的方法，优选地，步骤(1)中，加入二氧化氯 发生器中的氯酸盐、过氧化氢和硫酸的摩尔比为1:0.55～1:0.5～1；二氧化氯发生器的反应温度为40～90℃。
根据本发明所述的方法，优选地，步骤(2)中，进入烟气管道中的烟气含硫量为600～4000mg/Nm 3；含氮量200～600mg/Nm 3；含氧量5～23wt％；含湿量5～12wt％。
根据本发明所述的方法，优选地，步骤(2)中，烟气在烟气管道内的流速为6～15m/s；混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触的时间为1～3s。
根据本发明所述的方法，优选地，步骤(3)中，碱性吸收剂干粉为氧化钙和/或氢氧化钙；且碱性吸收剂干粉的粒径为150～350目。
根据本发明所述的方法，优选地，步骤(3)中，氧化后烟气在脱硫脱硝塔内的流速为1～7m/s；氧化后烟气与碱性吸收剂干粉在脱硫脱硝塔内接触的时间为2～15s。
根据本发明所述的方法，优选地，步骤(3)中，单位时间内通入的碱性吸收剂干粉所含钙元素与单位时间内通入的烟气所含硫元素的摩尔比Ca/S，其为1.1～1.5。
根据本发明所述的方法，优选地，步骤(3)中，单位时间内通入的碱性吸收剂干粉所含钙元素与单位时间内通入的烟气所含氮元素的摩尔比为Ca/N，其为0.5～1.5。
本发明的脱硫脱硝方法采用原位合成的二氧化氯气体作为氧化剂进行脱硫脱硝，脱硫效率达到99％以上，脱硝效率达到91％以上。进一步地，采用二氧化氯气体形态，通过特定的工艺方法，减少二氧化氯的消耗量，降低了成本。
具体实施方式
下面结合具体实施例对本发明作进一步的说明，但本发明的保护范围并不限于此。
本发明提供一种氯酸钠制备二氧化氯作为氧化剂、然后与钙系吸收剂相结合的CFB法烟气脱硫脱硝一体化工艺。反应原理如下：
(1)二氧化氯气体的制备
2NaClO 3+H 2O 2+H 2SO 4→2ClO 2+Na 2SO 4+H 2O+O 2(主)
(2)一氧化氮的氧化
2ClO 2+5NO+H 2O→2HCl+5NO 2(主)
2ClO 2+4NO→Cl 2+4NO 2(副)
2NO 2+H 2O→HNO 2+HNO 3(副)
5HNO 2+2ClO 2+H 2O→5HNO 3+2HCl(副)
(3)烟气脱硝
NO+NO 2+Ca(OH) 2→Ca(NO 2) 2+H 2O(主)
Ca(NO 2) 2+O 2→Ca(NO 3) 2(主)
HNO 2+HNO 3+1/2O 2+Ca(OH) 2→Ca(NO 3) 2+2H 2O(副)
4ClO 2+2Ca(OH) 2→Ca(ClO 2) 2+Ca(ClO 3) 2+2H 2O(副)
2Cl 2+2Ca(OH) 2→CaCl 2+Ca(ClO) 2+2H 2O(副)
(4)烟气脱硫
SO 2+H 2O→H 2SO 3(主)
3H 2SO 3+2Ca(OH) 2→Ca(HSO 3) 2+CaSO 3+4H 2O(主)
Ca(HSO 3) 2+2CaSO 3+2O 2+Ca(OH) 2→4CaSO 4+2H 2O(主)
本发明的烟气脱硫脱硝的方法包括如下步骤：(1)二氧化氯气体的制备步骤；(2)烟气的氧化步骤；和(3)脱硫脱硝步骤。下面进行详细描述。
＜二氧化氯气体的制备步骤＞
将氯酸盐水溶液、过氧化物溶液和硫酸水溶液在二氧化氯发生器中反应，获得二氧化氯气体。将二氧化氯气体与空气混合获得混合气体。在本发明中，二氧化氯气体占混合气体的百分比可以为4～10vol％，优选为5～8vol％；更优选为7～8vol％。将二氧化氯气体与空气按上述配比混合，在安全生产的基础上提高一氧化氮的转化率。
过氧化物溶液可以选自双氧水等。根据本发明的一个实施方式，双氧水中过氧化氢的浓度可以为25～28wt％，优选为26～28wt％，更优选为27～28wt％。根据本发明的另一个实施方式，双氧水中过氧化氢的浓度还可以为34～38wt％，优选为34.5～37wt％，更优选为35～36wt％。采用上述浓度范围的过氧化物，可以控制反应速率，提高生产二氧化氯气体的安全性。
氯酸盐可以选自氯酸钠、氯酸钾和氯酸镁中的一种；优选地，氯酸盐选自氯酸钠或者氯酸钾中的一种；更优选地，氯酸盐为氯酸钠。加入二氧化氯发生器中的氯酸盐水溶液中的氯酸钠、双氧水中的过氧化氢和硫酸水溶液中的硫酸的摩尔比为1:0.55～1:0.5～1，优选为1:0.6～1:0.6～1，更优选为1:0.7～1:0.7～1。此外，二氧化氯发生器的反应温度为50～90℃，优选为60～80℃，更优选为70～80℃。采用上述摩尔比和反应温度范围，可以控制二氧化氯生成速率，提高生成的安全系数；进一步地，提高生成的二氧化氯气体的纯度。
二氧化氯发生器产生的二氧化氯气体与加入的空气在二氧化氯发生器中混合形成混合气体，通过引风机输出混合气体。
＜烟气的氧化步骤＞
将混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触，获得氧化后烟气。在本发明中，单位时间内通入烟气管道的混合气体中的二氧化氯与烟气中含有的一氧化氮的摩尔比可以为1～1.8，优选为1.1～1.6，更优选为1.2～1.5。采用上述摩尔比，可以在节约二氧化氯用量的基础上，提高一氧化氮的氧化率。
根据本发明的一个具体实施方式，二氧化氯发生器产生的二氧化氯气体与加入的空气在二氧化氯发生器中混合形成混合气体，该混合气体经引风机输出，然后输入至烟气管道中，且与输入烟气管道中的烟气进行接触。单位时间内通入烟气管道的混合气体中的二氧化氯与烟气中含有的一氧化氮的摩尔比为1.2～1.5。
进入烟气管道中的烟气含硫量(含硫量为二氧化硫含量)可以为600～4000mg/Nm 3，优选为1000～3000mg/Nm 3，更优选为1500～2500mg/Nm 3。进入烟气管道中的烟气含氮量(含氮量为一氧化氮含量)可以为200～600mg/Nm 3，优选为200～400mg/Nm 3，更优选为220～250mg/Nm 3。进入烟气管道中的烟气含氧量可以为5～23wt％，优选为10～20wt％，更优选为15～20wt％。进入烟气管道中的烟气含湿量可以为5～12wt％，优选为8～12wt％，更优选为10～12wt％。采用上述烟气含硫量、含氮量、含氧量和含湿量，可以协助提高烟气的脱硫脱硝效果。
烟气在烟气管道内的流速可以为6～15m/s，优选为8～15m/s，更优选为10～12m/s。此外，混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触的时间可以为1～3s。通过将烟气的流速控制在上述范围内，既保证烟气中一氧化氮的氧化率，又能保证处理速率。
烟气的含尘量可以为80～200mg/Nm 3，优选为100～150mg/Nm 3， 更优选为120～150mg/Nm 3。根据本发明的一个具体实施方式，烟气在通入烟气管道前进行预除尘处理，获得预除尘烟气通入烟气管道中。本发明采用静电除尘器对烟气进行预除尘处理。
＜脱硫脱硝步骤＞
在脱硫脱硝步骤中，将氧化后烟气通入脱硫脱硝塔内与喷入的碱性吸收剂干粉混合，且向脱硫脱硝塔内喷淋水，获得脱硫脱硝烟气。
在本发明中，碱性吸收剂干粉为氧化钙和/或氢氧化钙，优选地，碱性吸收剂干粉为氧化钙和/或氢氧化钙，更优选地，碱性吸收剂干粉为氢氧化钙。在本发明中，氧化钙的纯度可以为80～99wt％，优选为80～95wt％，更优选为80～90wt％。氢氧化钙的纯度可以为80～99wt％，优选为80～95wt％，更优选为80～90wt％。在本发明中，碱性吸收剂干粉的粒径可以为150～350目，优选为200～350目，更优选为200～300目。采用上述粒径范围的碱性吸收剂进行干法吸收，可以提高脱硫脱硝效果。
氧化后烟气在脱硫脱硝塔内的流速可以为1～7m/s，优选为2～5m/s，更优选为3～4m/s。氧化后烟气与碱性吸收剂干粉在脱硫脱硝塔内接触的时间可以为2～15s，优选为3～12s，更优选为5～10s。
单位时间内通入的碱性吸收剂干粉所含钙元素与单位时间内通入的烟气所含硫元素的摩尔比为Ca/S，其可以为1.1～1.5，优选为1.2～1.5，更优选为1.2～1.3。采用上述Ca/S摩尔比，在节约成本的基础上，提高脱硫效率。
单位时间内通入的碱性吸收剂干粉所含钙元素与单位时间内通入的烟气所含氮元素的摩尔比为Ca/N，其可以为0.5～1.5，优选为0.5～1.0，更优选为0.6～0.8。采用上述Ca/N摩尔比，在节约成本的基础上，提高脱硝效率。
氧化后烟气在脱硫脱硝塔入口处的温度可以为110～200℃，优选为110～180℃，更优选为120～150℃。
根据本发明的一个具体实施方式，脱硫脱硝烟气经过脱硫脱硝塔顶的布袋除尘器除尘，获得的净化后烟气从烟囱排放，获得的固体灰渣输送至灰渣储罐或者喷入脱硫脱硝塔内作为碱性吸收剂干粉重复利用。
实施例1
采用计量泵将氯酸钠水溶液、双氧水和硫酸水溶液输送至二氧化氯发生器中进行反应，获得二氧化氯气体，与通入二氧化氯发生器中的空气混合获得混合气体，并通过引风机输入至烟气管道中。
将烟气经过静电除尘器除尘后通入烟气管道中；与引风机输入的混合气体在烟气管道内接触，将烟气中的一氧化氮氧化获得氮氧化物，获得氧化后烟气。
将氧化后烟气通入脱硫脱硝塔内，与喷入脱硫脱硝塔中的氢氧化钙干粉的混合，再向脱硫脱硝塔内喷淋水，以脱除氧化烟气中的氮氧化物和二氧化硫，获得脱硫脱硝烟气。
将上述方法应用于90m 2烧结机脱硫脱硝项目中，各运行参数见表1。脱硫脱硝烟气通过脱硫脱硝塔顶的布袋除尘器进行除尘，获得的净化烟气参数见表2。
表1
参数 数值 单位
烟气管道入口处的烟气流量(工况) 575824 m 3/h
烟气管道入口处的烟气流量(标况) 400000 Nm 3/h
脱硫脱硝塔入口处的氧化后烟气的温度 120 ℃
烟气中SO 2的含量 2300 mg/Nm 3
烟气中NO的含量 230 mg/Nm 3
烟气含湿量 10 ％
烟气含氧量 18 ％
烟气含尘量 120 mg/Nm 3
烟气在烟气管道内的流速 12 m/s
氧化后烟气在脱硫脱硝塔内的流速 3.8 m/s
氯酸钠水溶液 30 wt％
双氧水 27.5 wt％
硫酸水溶液 60 wt％
氯酸钠:过氧化氢:硫酸的摩尔比 1:0.7:0.7 -
二氧化氯发生器反应温度 45 ℃
二氧化氯占混合气体的体积分数 8 vol％
烟气管道内ClO 2/NO的摩尔比 1.3 -
Ca/S摩尔比 1.3 -
Ca/N摩尔比 0.6 -
氢氧化钙干粉的纯度 90 wt％
氢氧化钙干粉的粒径 200～300 目
氢氧化钙干粉的用量 1688 kg/h
表2
项目 数量 单位
脱硫效率 99.8 ％
脱硝效率 95.2 ％
对比例1
在本对比例中，除了表3中的运行参数，其余运行参数均与实施例1相同。本对比例获得的净化烟气参数见表4。
表3
参数 数值 单位
ClO 2/NO摩尔比 0.7  
表4
项目 数量 单位
脱硫效率 99.2 ％
脱硝效率 89.6 ％
对比例2
在本对比例中，除了表5中的运行参数，其余运行参数均与实施例1相同。本对比例获得的净化烟气参数见表6。
表5
参数 数值 单位
ClO 2/NO摩尔比 2  
表6
项目 数量 单位
排烟温度 40 ℃
脱硫效率 99.5 ％
脱硝效率 93.6 ％
本发明并不限于上述实施方式，在不背离本发明的实质内容的情况下，本领域技术人员可以想到的任何变形、改进、替换均落入本发明的范围。

Claims (10)

  1. 一种利用二氧化氯脱硫脱硝的方法，其特征在于，包括如下步骤：
    (1)将氯酸盐水溶液、过氧化物溶液和硫酸水溶液混合加入二氧化氯发生器中反应，获得二氧化氯气体；将二氧化氯气体与空气混合获得混合气体；其中，二氧化氯气体占混合气体的4～10vol％；
    (2)将混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触，获得氧化后烟气；其中，单位时间内通入烟气管道的混合气体中的二氧化氯与烟气中含有的一氧化氮的摩尔比为1～1.8；
    (3)将氧化后烟气通入脱硫脱硝塔内与喷入的碱性吸收剂干粉混合，且向脱硫脱硝塔内喷淋水，获得脱硫脱硝烟气。
  2. 根据权利要求1所述的方法，其特征在于，步骤(1)中，氯酸盐为氯酸钠；其中，氯酸钠水溶液的浓度为15～40wt％，硫酸水溶液的浓度为30～60wt％。
  3. 根据权利要求2所述的方法，其特征在于，步骤(1)中，过氧化物溶液为25～28wt％的双氧水或者34～38wt％的双氧水。
  4. 根据权利要求3所述的方法，其特征在于，步骤(1)中，加入二氧化氯发生器中的氯酸盐水溶液中的氯酸钠、双氧水中的过氧化氢和硫酸水溶液中的硫酸的摩尔比为1:0.55～1:0.5～1；二氧化氯发生器的反应温度为40～90℃。
  5. 根据权利要求1所述的方法，其特征在于，步骤(2)中，进入烟气管道中的烟气含硫量为600～4000mg/Nm 3；含氮量为200～600mg/Nm 3；含氧量5～23wt％；含湿量5～12wt％。
  6. 根据权利要求1所述的方法，其特征在于，步骤(2)中，烟气在烟气管道内的流速为6～15m/s；混合气体与烟气在进入脱硫脱硝塔之前的烟气管道内接触的时间为1～3s。
  7. 根据权利要求1所述的方法，其特征在于，步骤(3)中，碱性吸收剂干粉为氧化钙和/或氢氧化钙；且碱性吸收剂干粉的粒径为150～350目。
  8. 根据权利要求1所述的方法，其特征在于，步骤(3)中，氧化后烟气在脱硫脱硝塔内的流速为1～7m/s；氧化后烟气与碱性吸收剂干粉在脱硫脱硝塔内接触的时间为2～15s。
  9. 根据权利要求7所述的方法，其特征在于，步骤(3)中，单位时间内通入的碱性吸收剂干粉所含钙元素与单位时间内通入的烟气所含硫元素的摩尔比为Ca/S，其为1.1～1.5。
  10. 根据权利要求9所述的方法，其特征在于，步骤(3)中，单位时间内通入的碱性吸收剂干粉所含钙元素与单位时间内通入的烟气所含氮元素的摩尔比为Ca/N，其为0.5～1.5。
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