CN112403225A - Method for reducing nitrogen oxides of caustic soda flake device - Google Patents

Method for reducing nitrogen oxides of caustic soda flake device Download PDF

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Publication number
CN112403225A
CN112403225A CN202011215091.2A CN202011215091A CN112403225A CN 112403225 A CN112403225 A CN 112403225A CN 202011215091 A CN202011215091 A CN 202011215091A CN 112403225 A CN112403225 A CN 112403225A
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nitrogen oxides
caustic soda
hno
flake
alkali liquor
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于育新
蔡银萍
王盟
李腾飞
潘慧
张海艳
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Binzhou Polytechnic
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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
    • B01D53/75—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
    • B01D53/46—Removing components of defined structure
    • B01D53/54—Nitrogen compounds
    • B01D53/56—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
    • 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
    • B01D53/86—Catalytic processes
    • B01D53/8621—Removing nitrogen compounds
    • B01D53/8625—Nitrogen oxides
    • B01D53/8628—Processes characterised by a specific catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2251/00—Reactants
    • B01D2251/10—Oxidants
    • B01D2251/102—Oxygen
    • 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
    • B01D2255/00—Catalysts
    • B01D2255/50—Zeolites
    • B01D2255/504—ZSM 5 zeolites
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)

Abstract

The invention belongs to the technical field of nitrogen oxide treatment, and particularly relates to a method for reducing nitrogen oxides in a caustic soda flake device, which comprises the following steps: s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction; s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower; s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor. By using high-silicon Na-ZSM-5 molecular sieve as catalyst, the inherent O in waste gas is used2As an oxidant, to catalytically oxidize NO in the exhaust gas to readily soluble NO2The alkali liquor cooling water generated in the production process of flake caustic soda is reused, so that the problem of the cooling water evaporation of the alkali liquor is solved, and the nitrogen oxide NO in the waste gas is reducedxThe content of (a).

Description

Method for reducing nitrogen oxides of caustic soda flake device
Technical Field
The invention belongs to the field of nitrogen oxide treatment, and particularly relates to a method for reducing nitrogen oxides in a caustic soda flake device.
Background
NOxThe treatment method of waste gas mainly includes dry method and wet method, the dry method includes catalytic reduction method, catalytic decomposition method, adsorption method, etc., the wet method includes alkali absorption, reduction absorption, oxidation absorption and complex absorption, etc., compared with the dry method, the wet method has the advantages of simple process equipment, low operation cost, various absorbent types, strong adaptability, etc.
Existing Nitrogen Oxides (NO)x) In the process of absorption, industrial NO is containedxThe mole fraction of NO in the exhaust gas is NOxMore than 90 percent of the total amount, the mole fraction of water vapor and oxygen can reach 20 percent, NO is difficult to dissolve in alkali liquor, and NO is causedxThe removal rate is low, and therefore partial oxidation of NO to NO is necessary first2To effectively convert NOxThe content of (c) is reduced.
Therefore, the method for reducing the nitrogen oxides in the caustic soda flake device is provided.
Disclosure of Invention
The invention aims to solve the problems and provides a method for reducing nitrogen oxides in a caustic soda flake device.
In order to achieve the purpose, the invention adopts the following technical scheme: a method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at the temperature of 100-.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
the method for reducing the nitrogen oxide in the caustic soda flake deviceIn the method, in the S3, the content of alkali liquor is opposite to NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
Compared with the prior art, the invention has the advantages that: by using high-silicon Na-ZSM-5 molecular sieve as catalyst, the inherent O in waste gas is used2As an oxidant, to catalytically oxidize NO in the exhaust gas to readily soluble NO2The alkali liquor cooling water generated in the production process of flake caustic soda is reused, so that the problem of the cooling water evaporation of the alkali liquor is solved, and the nitrogen oxide NO in the waste gas is reducedxThe content of (a).
Detailed Description
The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.
Example 1
A method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at 100 ℃ for 2h, roasting at 480 ℃ for 3h, tabletting, crushing and sieving to obtain the granular molecular sieve catalyst with the particle size of 0.60mm, and using the granular molecular sieve catalyst in subsequent processes for later use.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
in the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the content of lye is NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
Example 2
A method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at 105 ℃ for 2h, then roasting at 485 ℃ for 3h, tabletting, crushing and sieving to obtain the granular molecular sieve catalyst with the particle size of 0.65mm, and using the granular molecular sieve catalyst in subsequent processes for later use.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2As an oxidizing agent, with a high content ofThe silicon Na-ZSM-5 molecular sieve is used as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
in the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the content of lye is NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
Example 3
A method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) After forming waste gas with a certain oxidation degree, introducingIn a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at 110 ℃ for 2h, roasting at 490 ℃ for 3h, tabletting, crushing and sieving to obtain the granular molecular sieve catalyst with the particle size of 0.70mm, and using the granular molecular sieve catalyst in subsequent processes for later use.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
in the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the content of lye is NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
Example 4
A method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at 115 ℃ for 2h, then roasting at 495 ℃ for 3h, tabletting, crushing and sieving to obtain the granular molecular sieve catalyst with the particle size of 0.75mm, and using the granular molecular sieve catalyst in subsequent processes for later use.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Is/are as followsThe component (A) comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
in the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the content of lye is NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
Example 5
A method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at 120 ℃ for 2h, roasting at 500 ℃ for 3h, tabletting, crushing and sieving to obtain the granular molecular sieve catalyst with the particle size of 0.8mm, and using the granular molecular sieve catalyst in subsequent processes for later use.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
in the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the content of lye is NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
Example 6
A method for reducing nitrogen oxides in a caustic soda flake plant, the method comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
In the above method for reducing nitrogen oxides in a caustic soda flake plant, in S1, the catalyst is prepared by:
selecting Na-ZSM-5(n(SiO2)/n(Al2O3) 300) molecular sieve, drying the molecular sieve raw powder at 125 ℃ for 2h, then roasting at 505 ℃ for 3h, tabletting, crushing and sieving to obtain the granular molecular sieve catalyst with the particle size of 0.85mm, and using the granular molecular sieve catalyst in subsequent processes for later use.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S1, Nitrogen Oxides (NO) generated during heating of combustion furnacex) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
In the above method for reducing nitrogen oxides in caustic soda flake plant, in S2, O in the exhaust gas is used2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
In the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the component of the lye cooling water is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
in the above method for reducing nitrogen oxides in flake caustic soda device, in S3, the content of lye is NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, the result is thatOH in lye-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
In the invention, the inherent O in the waste gas is used by adopting high-silicon Na-ZSM-5 molecular sieve as a catalyst2As an oxidant, to catalytically oxidize NO in the exhaust gas to readily soluble NO2The alkali liquor cooling water generated in the production process of flake caustic soda is reused, so that the problem of the cooling water evaporation of the alkali liquor is solved, and the nitrogen oxide NO in the waste gas is reducedxThe content of (a).
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (6)

1. A method for reducing nitrogen oxides in a caustic soda flake plant, comprising the steps of:
s1, Nitrogen Oxides (NO) generated in the heating process of the combustion furnacex) Collected into a fixed bed reactor through a pipeline in a centralized way and used for preparing a catalyst required by the reaction;
s2 Nitric Oxide (NO) after passing through fixed bed reactorx) Introducing the waste gas with a certain oxidation degree into a bubbling absorption tower;
s3, discharging the alkali liquor cooling water generated in the production process of flake caustic into a bubbling absorption tower to finish the treatment of Nitrogen Oxide (NO)x) Absorbing and reducing with alkali liquor.
2. The method for reducing nitrogen oxides in a caustic soda flake plant according to claim 1, wherein in the step S1, the catalyst is prepared by:
Na-ZSM-5(n (SiO) is selected2)/n(Al2O3) 300) is divided intoAnd (2) sieving, namely drying the molecular sieve raw powder at the temperature of 100-.
3. The method for reducing nitrogen oxides in caustic soda flake plant as claimed in claim 1, wherein Nitrogen Oxides (NO) generated during heating of combustion furnace in S1x) Comprises NO and N2O、NO2、N2O3、N2O4Etc. wherein NO, NO2Etc. are all present in gaseous form in the normal state, and dinitrogen pentoxide (N)2O5) In a solid form in a normal state.
4. The method for reducing nitrogen oxides in caustic soda flake plant as claimed in claim 1, wherein in S2, O in exhaust gas is used as O2Takes high-silicon Na-ZSM-5 molecular sieve as an oxidant and takes high-silicon Na-ZSM-5 molecular sieve as a catalyst to catalyze and oxidize NO into easily soluble NO2And then introducing the waste gas after catalytic oxidation into a bubbling absorption tower.
5. The method for reducing nitrogen oxides in caustic soda flake plant as claimed in claim 1, wherein in S3, the component of the cooling water of the caustic soda is mainly Na2CO3And NaOH, wherein the NaOH absorbs NOxThe overall reaction formula of (a) is:
2NaOH+2NO2→NaNO3+NaNO2+H2O，
2NaOH+NO2+NO→2NaNO2+H2O
Na2CO3absorption of NOxThe overall reaction formula of (a) is:
Na2CO3+2NO2→NaNO2+NaNO2+CO2，
Na2CO2+NO2+NO→2NaNO2+CO2。
6. according toThe method for reducing nitrogen oxides in caustic soda flake device as claimed in claim 1, wherein in S3, the content of lye is relative to NOxThe effect of the removal rate of (a) is: when the mass fraction of NaOH is controlled to be more than 1 percent, the removal rate is controlled to be 60 to 65 percent, and the mass fraction of NaOH is controlled to be less than 1 percent, OH in the alkali liquor is caused-The content of HNO generated by the reaction in the solution is compared with that of HNO generated by the reaction in the solution2And HNO3In such a small amount that a large amount of HNO is present in the solution2And HNO3Resulting in a downward linear removal rate with OH-Increased content of, consumed HNO2And HNO3Is also increased so that NO isxThe removal rate of (a) is increased.
CN202011215091.2A 2020-11-04 2020-11-04 Method for reducing nitrogen oxides of caustic soda flake device Withdrawn CN112403225A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114471112A (en) * 2021-12-24 2022-05-13 安徽环境科技集团股份有限公司 Process and device for purifying waste gas containing nitrogen oxides

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114471112A (en) * 2021-12-24 2022-05-13 安徽环境科技集团股份有限公司 Process and device for purifying waste gas containing nitrogen oxides

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