阅读说明：本技术 一种脱硫副产物制备脱硝剂ClO2的系统与方法 (Denitration agent ClO prepared from desulfurization byproducts2System and method ) 是由 张艳平 张凡 何学娟 黄家玉 王洪昌 张�浩 王相凤 王红梅 石应杰 王凡 田刚 于 2020-05-21 设计创作，主要内容包括：本发明公开了一种脱硫副产物制备脱硝剂二氧化氯的系统,包括脱硫塔(1)、浓缩池(2)、脱硫浆液储存罐(3)、氯酸钠溶液储存罐(4)、二氧化氯发生器(5)、二氧化氯吸收装置(6)、自动化控制装置(7)、副产物回收装置(8)及喷淋脱硝塔(9)。还公开了一种一种脱硫副产物制备脱硝剂二氧化氯的方法,该系统和方法既解决了氨法脱硫副产物(NH<Sub>4</Sub>)<Sub>2</Sub>SO<Sub>3</Sub>难以氧化和处理的问题,同时又提出了一种将氨法脱硫与氧化法脱硝有机结合的低成本、副产物可资源化的脱硝剂ClO<Sub>2</Sub>的制备方法。(The invention discloses a system for preparing denitrifying agent chlorine dioxide from desulfurization byproducts, which comprises a desulfurization tower (1), a concentration tank (2), a desulfurization slurry storage tank (3), a sodium chlorate solution storage tank (4), a chlorine dioxide generator (5), a chlorine dioxide absorption device (6), an automatic control device (7), a byproduct recovery device (8) and a spraying denitrification tower (9). Also discloses a method for preparing denitrifying agent chlorine dioxide by using the desulfurization by-products, and the system and the method not only solve the problem of ammonia desulfurization by-products (NH) 4 ) 2 SO 3 Difficult oxidation and treatment, and provides a denitrifier ClO which organically combines ammonia desulfurization and oxidation denitration and has low cost and recyclable by-products 2 The preparation method of (1).)

1. Denitration oxidant ClO prepared from desulfurization byproducts₂The system of (a), characterized by: comprises a desulfurizing tower (1), a concentration tank (2), a desulfurizing slurry storage tank (3), a sodium chlorate solution storage tank (4), a chlorine dioxide generator (5), a chlorine dioxide absorption device (6), an automatic control device (7), a byproduct recovery device (8) and a spraying and denitrifying tower (9);

the flue gas and the ammonia desulphurization stock solution are subjected to absorption reaction in a desulphurization tower (1), the absorbed desulphurization slurry is concentrated in a concentration tank (2), and the concentrated desulphurization slurry is stored in a desulphurization slurry storage tank (3);

the desulfurization slurry storage tank (3) and the sodium chlorate solution storage tank (4) are connected with the chlorine dioxide generator (5) through pipelines;

the automatic control device (7) comprises a regulating valve, a flow and temperature sensor and a pH sensor, wherein the acquisition end of the regulating valve is respectively arranged at the connecting pipeline of the chlorine dioxide generator (5) and the desulfurization slurry storage tank (3) and the connecting pipeline of the chlorine dioxide generator (5) and the sodium chlorate solution storage tank (4), and the acquisition ends of the flow and temperature sensor and the pH sensor are arranged in the chlorine dioxide generator (5);

the chlorine dioxide solution enters a spraying denitration tower (9) for oxidation spraying denitration; the byproduct ammonium sulfate in the chlorine dioxide generator (5) is recycled by a byproduct recycling device (8) to be used as a nitrogen fertilizer.

2. The method for preparing denitration oxidant ClO from desulfurization byproducts according to claim 2₂The system of (a), characterized by: the chlorine dioxide generator (5) is a negative pressure system, and the top of the chlorine dioxide generator is provided with a liquid-dividing flow meter.

3. A method for preparing denitrifying agent chlorine dioxide by using desulfurization by-product ammonium sulfite specifically comprises the following steps:

step 1, carrying out absorption reaction on the flue gas and an ammonia desulphurization stock solution in a desulphurization tower (1), concentrating the absorbed desulphurization slurry in a concentration tank (2), and storing the concentrated desulphurization slurry in a desulphurization slurry storage tank (3) for later use;

step 2, enabling the desulfurized slurry in the desulfurized slurry storage tank (3) and the sodium chlorate in the sodium chlorate solution storage tank (4) to enter a chlorine dioxide generator (5) through a pipeline;

step 3, heating the mixed solution in the chlorine dioxide generator (5), and controlling the reaction temperature to 10-20 ℃ through a temperature sensor of an automatic control device (7);

step 4, after the temperature of the mixed solution is stable, slowly adding the diluted sulfuric acid into the chlorine dioxide generator (5) through a liquid separating and flow metering device at the top of the chlorine dioxide generator (5) to enable ammonium sulfite and sodium chlorate to react under the acidic condition provided by the sulfuric acid;

step 5, ClO generated by the reaction in the chlorine dioxide generator (5)₂Entering a chlorine dioxide absorption device (6) under negative pressure to become chlorine dioxide solution; the chlorine dioxide generator (5) keeps a negative pressure state, and the pressure is-68 to-92 Kpa; the absorption liquid in the chlorine dioxide absorption device (6) is aqueous solution.

Step 6, the chlorine dioxide solution enters a spraying denitration tower (9) to be oxidized and sprayed for denitration; meanwhile, the byproduct ammonium sulfate in the chlorine dioxide generator (5) is recycled by a byproduct recycling device (8) to be used as a nitrogen fertilizer.

4. A method for preparing denitrifying agent chlorine dioxide by using desulfurization by-product ammonium sulfite specifically comprises the following steps: in the step 2, the flow of the desulfurized slurry and the sodium chlorate is adjusted by an adjusting valve and a flowmeter.

5. A method for preparing denitrifying agent chlorine dioxide by using desulfurization by-product ammonium sulfite specifically comprises the following steps: in the step 5, controlling the pH value to be between 6 and 6.8 by a pH sensor of an automatic control device (7); wherein the acid is H with the concentration of 5-12mol/L₂SO₄Mixing the solution with H₂SO₄Is 1: 1.

Technical Field

The invention belongs to the field of industrial atmospheric pollution treatment, and particularly relates to a method for preparing denitration oxidant ClO by using ammonia desulphurization byproduct ammonium sulfite as a reducing agent₂The method of (1).

Background

Sulfur dioxide (SO)₂) And Nitrogen Oxides (NO)_x) Is the main atmospheric pollutant and the main factor influencing the atmospheric quality, and the SO in the air₂And NOx are also one of the important reasons for haze generation, SO that SO in flue gas is removed₂And NOx tolerance.

The ammonia desulphurization technology is a main desulphurization technology due to the advantages of high desulphurization speed, high efficiency, high economic value of desulphurization products and the like. The ammonia desulfurization is to absorb SO in flue gas by ammonia water₂Gas, acid-base neutralization reaction, i.e. ammonia and SO₂The reaction generates ammonium sulfite, which is high-efficiencyAnd a wet desulphurization mode with low energy consumption. The ammonia sulfite has unstable performance and can be decomposed into SO again₂Causing secondary pollution, and although ammonium sulfite can be directly used as a fertilizer, the effect is not good due to unstable property; because ammonium sulfite is not easy to be oxidized, the oxidation of ammonium sulfite into relatively stable ammonium sulfate is a key and important link to be solved for ammonia desulphurization.

The molecular formula of the chlorine dioxide is ClO₂Is a yellow green gas, is easy to dissolve in water, and is a safe and nontoxic green disinfectant recognized internationally. Simultaneous ClO₂It is also a strong oxidant, has strong oxidizing power, and can perform oxidation-reduction reaction with many organic and inorganic compounds. ClO₂The application field is wide, and the water treatment agent is commonly used for sterilizing and disinfecting water bodies such as tap water, hospital sewage, industrial circulating cooling water, swimming pool water, aquaculture water and the like, killing algae, removing peculiar smell and the like; also used for treating water bodies containing cyanogen, sulfur, sulfide, mercaptan, phenol, benzene and the like and printing and dyeing wastewater; because the catalyst has strong oxidizability and can be used for removing metal ions such as iron, manganese and the like in water, the ClO is currently used₂Has been successfully applied in the field of water treatment.

In recent years, ClO₂Research on wet denitration of industrial exhaust gas as an oxidizing agent has been widely reported, and the oxidizing agent is favored by broad researchers due to advantages such as high oxidation efficiency and strong flue gas temperature adaptability. Such as Zhejiang university for ClO₂Research on the removal of NO in the smoke by the solution is carried out. The experimental results show that: at a liquid-gas ratio of 20L/m³The reaction temperature is 20 ℃, the reaction pH is 4.0, and the NO mass concentration is 250mg/m³、ClO₂Under the condition of the mass concentration of 200mg/L, the NO oxidation rate reaches more than 92 percent. However, in the practical engineering application of waste gas denitration, ClO₂Denitration is limited in application due to problems of high preparation cost, difficulty in processing byproducts and the like.

CIO₂The properties are more active, and the transportation and the storage are not easy, and a field preparation mode is usually adopted. ClO₂The preparation method is various and is divided into a chemical method and an electrolytic method, the current main method is the chemical method, and the ClO is mainly prepared by adding a reducing agent into sodium chlorate under the acidic condition₂。

The common process is to use SO₂R as a reducing agent₁Process R with hydrochloric acid (HCl) as reducing agent₂Method, R with salt (NaCl) as reducing agent₅Method, with methanol (CH)₃OH) as reducing agent₈Process, and with hydrogen peroxide (H)₂O₂) R as a reducing agent₁₁The method is carried out. The chemical reaction is as follows:

R₁the method comprises the following steps: NaClO₃+SO₂→ClO₂+NaSO₄

R₂The method comprises the following steps: NaClO₃+2HCl→ClO₂+1/2Cl₂+H₂O+NaCl

R₅The method comprises the following steps: NaClO₃+NaCl+H₂SO₄→ClO₂+0.5Cl₂+Na₂SO₄+H₂O

R₈The method comprises the following steps: NaClO₃+CH₃OH+H₂SO₄→ClO₂+Na₃H(SO₄)₂+CH₃COOH+H₂O

R₁₁The method comprises the following steps: 2NaClO₃+H₂O₂+H₂SO₄→O₂+2C1O₂+2H₂O+Na₂SO₄

The method can be applied to the engineering production of chlorine dioxide and achieves a good effect, but is difficult to be applied to the actual waste gas denitration engineering.

Wherein R is₁Due to the by-product SO₂Too many problems have the disadvantage that R₂The main disadvantage of the process is the by-product Cl₂High yield, R₅By-product of the process Na₂SO₄The recovery of (acid mirabilite) is difficult, which causes secondary pollution. R₈And R₁₁The method is limited in its application due to its high cost.

Therefore, in order to develop the denitration technology for oxidizing the flue gas by using the chlorine dioxide solution, an economical and applicable reducing agent needs to be found to solve the problems of high preparation cost and difficulty in treating byproducts.

Disclosure of Invention

The invention aims to solve the problem of ClO in flue gas denitration engineering application₂High preparation cost and difficult treatment of byproducts.

The technical scheme of the invention is to provide a method for preparing denitration oxidant ClO by using desulfurization byproducts₂The system of (a), characterized by: the device comprises a desulfurization tower, a concentration tank, a desulfurization slurry storage tank, a sodium chlorate solution storage tank, a chlorine dioxide generator, a chlorine dioxide absorption device, an automatic control device, a byproduct recovery device and a spraying denitration tower;

the flue gas and the ammonia desulphurization stock solution are subjected to absorption reaction in a desulphurization tower, and the absorbed desulphurization slurry is concentrated in a concentration tank and then stored in a desulphurization slurry storage tank;

the desulfurization slurry storage tank and the sodium chlorate solution storage tank are both connected with the chlorine dioxide generator through pipelines;

the automatic control device comprises a regulating valve, a flow and temperature sensor and a pH sensor, wherein the acquisition end of the regulating valve is respectively arranged at the connecting pipeline of the chlorine dioxide generator and the desulfurization slurry storage tank and the connecting pipeline of the chlorine dioxide generator and the sodium chlorate solution storage tank, and the acquisition ends of the flow and temperature sensor and the pH sensor are arranged in the chlorine dioxide generator;

the chlorine dioxide solution enters a spraying denitration tower to be oxidized and sprayed for denitration; the byproduct ammonium sulfate in the chlorine dioxide generator is recycled by a byproduct recycling device to be used as a nitrogen fertilizer.

Further, the chlorine dioxide generator is a negative pressure system, and the top of the chlorine dioxide generator is provided with a liquid dividing flow meter.

The invention also provides a method for preparing the denitrifying agent chlorine dioxide by using the desulfurization byproduct ammonium sulfite, which comprises the following steps:

step 1, carrying out absorption reaction on the flue gas and an ammonia desulphurization stock solution in a desulphurization tower, concentrating the absorbed desulphurization slurry in a concentration tank, and storing the concentrated desulphurization slurry in a desulphurization slurry storage tank for later use;

step 2, enabling the desulfurized slurry in the desulfurized slurry storage tank and the sodium chlorate in the sodium chlorate solution storage tank to enter a chlorine dioxide generator through a pipeline;

step 3, heating the mixed solution in the chlorine dioxide generator, and controlling the reaction temperature to 10-20 ℃ through a temperature sensor of an automatic control device;

step 4, after the temperature of the mixed liquid is stable, slowly adding the diluted sulfuric acid into a chlorine dioxide generator through a liquid separating flow meter at the top of the chlorine dioxide generator, and reacting ammonium sulfite and sodium chlorate under an acidic condition provided by the sulfuric acid;

step 5, ClO generated by the reaction in the chlorine dioxide generator₂Entering a chlorine dioxide absorption device under negative pressure to become chlorine dioxide solution; the chlorine dioxide generator is kept in a negative pressure state, and the pressure is-68 to-92 Kpa; the absorption liquid in the chlorine dioxide absorption device is aqueous solution.

Step 6, allowing the chlorine dioxide solution to enter a spray denitration tower for oxidation spray denitration; meanwhile, the byproduct ammonium sulfate in the chlorine dioxide generator is recycled by a byproduct recycling device to be used as a nitrogen fertilizer.

Further, in step 2, the flow of the desulfurized slurry and the sodium chlorate is adjusted by an adjusting valve and a flow meter.

Further, in the step 5, controlling the pH value to be between 6 and 6.8 by a pH sensor of an automatic control device; wherein the acid is H with the concentration of 5-12mol/L₂SO₄Mixing the solution with H₂SO₄Is 1: 1.

The invention has the advantages that:

(1) by-product (NH) of flue gas ammonia desulphurization link in equipment₄)₂SO₃As reducing agents, in H₂SO₄Provided with NaClO under acidic conditions₃Reaction for preparing ClO₂Further used for flue gas denitration, and solves the problem of ammonia desulphurization by-product (NH)₄)₂SO₃The oxidation problem of the desulfurization catalyst realizes high-value recycling of desulfurization byproducts;

(2) the method prepares ClO₂Low cost compared with methanol (CH3OH) and H₂O₂Methods, etc., which reduce the complicated processes for the special preparation of reducing agents, and direct extractionThe by-product of ammonia desulphurization is used as the raw material, so that the preparation cost is saved;

(3) reaction by-product (NH)₄)₂SO₄Can be used as chemical fertilizer, the byproduct mirabilite is directly crystallized and separated out in the form of neutral mirabilite, and can be recycled or sold as a commodity, thereby solving the problem of ClO₂The problem that byproducts are difficult to treat in the preparation process is solved, and the green and economic ClO is provided for wet denitration₂A preparation method.

(4) The interdependence of desulfurization and denitrification links is realized, so that the disposal of respective byproducts and secondary pollution are reduced, and the desulfurization and denitrification operation cost of enterprises is reduced.

(5) The invention adopts desulfurization by-product ammonium sulfite ((NH) on the basis of comprehensively considering the desulfurization and denitrification method of flue gas, products and by-products₄)₂SO₃) Preparation of denitration oxidant ClO for reducing agent₂And further used for flue gas denitration. Namely, the problem of treating the by-product of ammonia desulphurization is solved, and the denitration agent CIO is greatly reduced₂The preparation cost is low, and the reaction product ammonium sulfate is used as a main chemical basic raw material and can be used as a nitrogen fertilizer. The method reduces the oxidation link of the ammonium sulfite serving as the byproduct of ammonia desulphurization, improves the comprehensive utilization efficiency of the desulphurization byproduct resources, and provides green and economic ClO for wet denitration₂The preparation method of the oxidant saves the preparation of CIO₂The preparation or purchase cost of the required reducing agent can greatly reduce the desulfurization and denitrification environment-friendly operation cost of enterprises.

Drawings

FIG. 1 is a schematic view of the process of the present invention.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to fig. 1.

As shown in FIG. 1, this example provides a method for preparing a denitration oxidizer ClO from a desulfurization byproduct₂The system comprises a desulfurizing tower 1, a concentration tank 2, a desulfurized slurry storage tank 3, a sodium chlorate solution storage tank 4, a chlorine dioxide generator 5, a chlorine dioxide absorption device 6, an automatic control device 7, a byproduct recovery device 8 and a spraying and denitrifying tower 9;

wherein, the flue gas and the ammonia desulphurization stock solution are subjected to absorption reaction in a desulphurization tower 1, the absorbed desulphurization slurry is concentrated in a concentration tank 2, and the concentrated desulphurization slurry is stored in a desulphurization slurry storage tank 3;

the desulfurization slurry storage tank 3 is connected with the chlorine dioxide generator 5 through a pipeline, the sodium chlorate solution storage tank 4 is connected with the chlorine dioxide generator 5 through a pipeline, and a flow meter and an adjusting valve are respectively arranged in the middle of the storage tank;

the chlorine dioxide generator 5 is a negative pressure system, and the top of the chlorine dioxide generator is provided with a liquid separation flow meter;

the automatic control device 7 comprises a regulating valve, a flow and temperature sensor and a pH sensor, wherein the acquisition end of the regulating valve is respectively arranged at the connecting pipeline of the chlorine dioxide generator 5 and the desulfurization slurry storage tank 3 and the connecting pipeline of the chlorine dioxide generator 5 and the sodium chlorate solution storage tank 4, and the acquisition ends of the flow and temperature sensor and the pH sensor are arranged in the chlorine dioxide generator 5.

The chlorine dioxide solution enters a spraying denitration tower 9 for oxidation spraying denitration; the by-product ammonium sulfate in the chlorine dioxide generator 5 is recovered by the by-product recovering apparatus 8 to be used as a nitrogen fertilizer.

The embodiment also provides a method for preparing denitrifying agent chlorine dioxide by using a desulfurization byproduct ammonium sulfite, which specifically comprises the following steps:

step 1, carrying out absorption reaction on the flue gas and an ammonia desulphurization stock solution in a desulphurization tower 1, concentrating the absorbed desulphurization slurry in a concentration tank 2, and storing the concentrated desulphurization slurry in a desulphurization slurry storage tank 3 for later use;

and 2, enabling the desulfurization slurry in the desulfurization slurry storage tank 3 and the sodium chlorate in the sodium chlorate solution storage tank 4 to enter a chlorine dioxide generator 5 through a pipeline, wherein the flow rates are adjusted through an adjusting valve and a flow meter.

Step 3, heating the mixed solution in the chlorine dioxide generator 5, and controlling the optimal reaction temperature to 10-20 ℃ by a temperature sensor of the automatic control device 7;

in the step, the temperature is not suitable to be too high so as to prevent the reaction from being too violent or the generated chlorine dioxide gas from escaping in a large amount;

and 4, after the temperature of the mixed solution is stable, slowly adding the diluted sulfuric acid into the chlorine dioxide generator 5 through a liquid separating flow meter at the top of the chlorine dioxide generator 5, and reacting ammonium sulfite and sodium chlorate under an acidic condition provided by the sulfuric acid.

The pH is controlled between 6 and 6.8 by a pH sensor of the automatic control device 7.

In the step, the acid is H with the concentration of 5-12mol/L₂SO₄Mixing the solution with H₂SO₄Is 1: 1.

Step 5, ClO generated by the reaction in the chlorine dioxide generator 5₂Entering a chlorine dioxide absorption device 6 under negative pressure to become chlorine dioxide solution;

in the step, the chlorine dioxide generator 5 is kept in a negative pressure state, and the pressure is-68 to-92 Kpa; the absorption liquid in the chlorine dioxide absorption device 6 is aqueous solution.

Step 6, the chlorine dioxide solution enters a spraying denitration tower 9 for oxidation spraying denitration; meanwhile, the byproduct ammonium sulfate in the chlorine dioxide generator 5 is recycled by a byproduct recycling device 8 to be used as a nitrogen fertilizer.

In this implementation, desulfurization by-products are utilized as reducing agents with NaClO₃Reaction for preparing ClO₂Adding H₂SO₄The reaction principle is as follows:

liquid ammonia is firstly mixed with water to generate ammonia water, and the ammonia water is mixed with SO in flue gas in a desulfurizing tower₂Combining to generate ammonium hydrogen sulfite, and continuously reacting the ammonium hydrogen sulfite solution with NH₃The ammonium sulfite is generated by reaction, ammonia is continuously introduced, and SO is continuously absorbed₂Circularly reciprocating, when the solution reaches a certain concentration, transferring the concentrated solution into a neutralization tank, introducing ammonia for neutralization, and after the reaction is completed, concentrating and filtering to form ammonium sulfite slurry

NH₃+H₂O→NH₃·H₂O (1)

NH₃·H₂O+SO₂→NH₄HSO₃(2)

NH₄HSO₃+NH₃→(NH4)₂SO₃(3)

The desulfurization byproduct ammonium sulfite slurry reacts with sodium chlorate solution in a chlorine dioxide generator under the acidic condition provided by sulfuric acid to prepare chlorine dioxide, and the reaction formula is as follows:

2NaClO₃+(NH₄)₂SO₃+H₂SO₄＝Na₂SO₄+2ClO₂+H₂O+(NH₄)₂SO₄(4)

while the principles of the invention have been described in detail in connection with the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing embodiments are merely illustrative of exemplary implementations of the invention and are not limiting of the scope of the invention. The details of the embodiments are not to be interpreted as limiting the scope of the invention, and any obvious changes, such as equivalent alterations, simple substitutions and the like, based on the technical solution of the invention, can be interpreted without departing from the spirit and scope of the invention.