阅读说明：本技术 一种循环净化烟气中二氧化硫和氮氧化物的方法和装置 (Method and device for circularly purifying sulfur dioxide and nitrogen oxide in flue gas ) 是由 田森林 杨珊珊 李晨 赵群 宁平 李英杰 于 2021-09-15 设计创作，主要内容包括：一种循环净化烟气中二氧化硫和氮氧化物的方法和装置,所述方法以硫酸铵为烟气吸收介质在电解反应器内反应制取过硫酸铵溶液,进入吸收塔喷淋系统的过硫酸铵溶液经高温烟气活化用于氧化吸收烟气中的二氧化硫和氮氧化物,同时反应还原的硫酸铵可再次提取进入电解反应器,实现氧化剂的循环以及溶液中二氧化硫和氮氧化物的高效去除的目的。本发明装置简单、占地面积小、条件温和、运行成本低；在脱硫脱硝中不产生二次污染,环境友好,具有广泛的pH适应性；烟气中的N、S元素达到了资源的循环利用,具有较大的工业应用潜力。(A method and a device for circularly purifying sulfur dioxide and nitrogen oxide in flue gas are provided, the method takes ammonium sulfate as a flue gas absorption medium to react in an electrolytic reactor to prepare ammonium persulfate solution, the ammonium persulfate solution entering a spray system of an absorption tower is activated by high-temperature flue gas to be used for oxidizing and absorbing sulfur dioxide and nitrogen oxide in the flue gas, and the ammonium sulfate reduced by reaction can be extracted again to enter the electrolytic reactor, so that the purposes of circulation of an oxidant and efficient removal of the sulfur dioxide and the nitrogen oxide in the solution are realized. The device is simple, the occupied area is small, the condition is mild, and the operation cost is low; the method does not produce secondary pollution in desulfurization and denitrification, is environment-friendly and has wide pH adaptability; n, S element in the flue gas achieves the recycling of resources and has great industrial application potential.)

1. The utility model provides a device of sulfur dioxide and nitrogen oxide in circulation purification flue gas which characterized in that: comprises an electrolytic reactor (1), a circulating pump (2), an absorption tower (3) and an absorption liquid storage tank (4); the outlet of the electrolytic reactor (1) is communicated with a spraying atomization system of the absorption tower (3) through a pipeline, flue gas enters from the bottom of the absorption tower (3), the inlet of the absorption liquid storage tank (4) is communicated with the liquid outlet of the absorption tower (3), the outlet of the absorption liquid storage tank (4) is connected with the inlet of the electrolytic reactor (1) through a pipeline, and a circulating pump (2) is arranged on the pipeline.

2. The apparatus of claim 1, wherein: the electrolytic reactor (1) comprises a cathode chamber and an anode chamber, wherein the solution in the cathode chamber is ammonium sulfate and ammonium nitrate, and the solution in the anode chamber is ammonium persulfate.

3. The apparatus of claim 1, wherein: the flow rate in the circulating pump (2) is 1-30L/min.

4. The apparatus of claim 1, wherein: the spraying and atomizing system is a stainless steel vortex nozzle with the diameter of 2.3-10 cm, and the nozzle is in a fan-shaped form.

5. The apparatus of claim 1, wherein: the anode of the electrolytic reactor (1) is selected from one of pure platinum, titanium-based platinum plating and graphite electrode, and the cathode is selected from one of copper-based polypyrrole plating, titanium-based cobaltosic oxide plating, titanium-based platinum dioxide plating, copper-based bismuth plating and titanium dioxide plating electrode; the cathode chamber and the anode chamber of the electrolytic reactor (1) are separated by a diaphragm, and the diaphragm is one of a ceramic membrane, a perfluorosulfonic acid type cation exchange membrane and a quaternary ammonium type anion exchange membrane; the perfluorinated sulfonic acid type cation exchange membrane is an HDGN membrane, an HDCMI membrane, an HDNAF membrane or an HDJCM membrane; the quaternary ammonium type anion exchange membrane is an HDJAM membrane or an HDAMI membrane.

6. A method for circularly purifying sulfur dioxide and nitrogen oxide in flue gas is characterized by comprising the following steps: firstly, reaction absorption liquid enters a cathode chamber of an electrolytic reactor, nitrate radicals and nitrite radicals are converted into ammonium radicals, then the ammonium radicals enter an anode chamber of the electrolytic reactor, sulfate radicals are converted into sulfate radicals at an anode, the solution containing ammonium persulfate and obtained by electrolysis is pumped into a spraying atomization system of an absorption tower by a circulating pump, meanwhile, high-temperature flue gas containing sulfur dioxide and nitrogen oxide is introduced from the bottom of the absorption tower, heat exchange is realized in the process, the ammonium persulfate is activated to generate active free radicals with strong oxidation, and the active free radicals are activated to be used for generating strong oxidationSO in flue gas₂And NO_XAnd (4) removing by oxidation, wherein the solution after reaction enters a pipeline from the bottom and is circularly pumped into the electrolytic reactor again, so that the circulation of the process is realized.

7. The method of claim 5, wherein: the concentration of ammonium persulfate generated by electrolysis in the electrolysis reactor is 0.005-1 mol/L.

8. The method of claim 5, wherein: the current density of the cathode and the anode of the electrolytic reactor is 0.5-10 mA/cm²And the electrolysis time is 0.5-8 h.

9. The method of claim 5, wherein: the pH value of the solution in the cathode chamber and the anode chamber of the electrolytic reactor is 2-5, the concentration of the ammonium sulfate solution in the cathode chamber is 0.5-3 mol/L, the concentration of the ammonium nitrate solution in the anode chamber is 0.0006-3 mol/L, and the concentration of the ammonium persulfate solution in the anode chamber is 0.005-1 mol/L.

Technical Field

The invention belongs to the field of flue gas purification, and particularly relates to a method and a device for circularly purifying sulfur dioxide and nitrogen oxide in flue gas.

Background

Very high concentrations of NOx and SO are produced during the combustion of fossil fuels₂Is the main pollutant of air and causes a series of serious environmental problems, such as photochemical smog, eutrophication and ozone depletion. Therefore, the control of the emission of sulfur dioxide and nitrogen oxides generated after combustion into the atmosphere is of great significance. The prior desulfurization methods comprise wet ammonia desulfurization, dry desulfurization, semi-dry desulfurization and flue gas circulating fluidized bed desulfurization; as for the denitration method, selective catalytic reduction and selective non-catalytic reduction, the most applied flue gas desulfurization and denitration technologies mainly comprise limestone/lime-gypsum flue gas desulfurization and ammonia selective catalytic reduction technologies which can respectively remove dioxide and nitrogen oxide, and because the main component of NOx is NO (about 90%), the NO solubility is low, unlike SO₂Thus, the removal is easy, and therefore, the simultaneous desulfurization and denitrification cannot be realized. At present, persulfate is used as an oxidizing agent to activate generated sulfate radicals (SO 4 ∙)^-) A novel advanced oxidation technology capable of realizing synchronous and efficient desulfurization and denitrification with hydroxyl free radical (. OH) is gradually attracting attention of researchers, persulfate is ionized in water to generate persulfate ions S₂O₈ ^2-The molecule of the oxidant contains peroxy O-O, and the oxidant is a strong oxidizing oxidant. But because the persulfate is relatively stable, the reaction rate is relatively slow at normal temperature, and the removal effect on nitrogen oxides and sulfur oxides is not obvious. In the presence of light, heat, ultrasonic waves, hydrogen peroxide, transition metal ions (Fe)²⁺Etc.) under the same conditions, S₂O₈ ^2-Can be activated and decomposed into SO₄∙^-. Therefore, the persulfate technology activated by the waste heat of the high-temperature flue gas is adopted, and the activated free radicals and a feasible method for synchronous desulfurization and denitrification are adopted. CN103691279A discloses 'a system and a method for desulfurizing and denitrating sodium persulfate by using flue gas waste heat through high-temperature activation', the method mainly uses flue gasThe waste heat activates persulfate in a high-temperature activation reactor, so that active free radicals are generated to remove sulfur dioxide and nitrogen oxide in the flue gas. However, the method cannot regenerate the absorbent, and the generated active free radicals have instantaneity. CN204058604U discloses a device for preparing ammonium persulfate from ammonia and urea solution flue gas purification absorption liquid, which is characterized in that the method comprises the steps of crystallizing and purifying ammonium sulfate and ammonium bisulfite which are byproducts of ammonia/urea solution, preparing ammonium persulfate through desulfurization and denitrification absorption in an electrolytic reactor, and introducing SO in flue gas₂And NO_XAnd (4) removing. The method does not activate ammonium persulfate to generate active free radicals with stronger oxidizing property, and does not convert nitrate to cause pollution of nitrate in water. CN105381699A discloses a method and a device for desulfurization and denitration by combining hydrogen peroxide oxidation and an amino wet method. The active free radical generated by the method is single, the hydroxyl free radical is stable without sulfate radical, and the regeneration of the absorbent can not be achieved. CN103691278386A discloses a system and a method for strengthening ammonium persulfate of ammonium persulfate based on acousto-optic coupling, in the method, flue gas in a boiler is dedusted and then enters a temperature regulator, the flue gas is subjected to temperature regulation and then enters an acousto-optic coupling reactor, and an ammonium persulfate solution releases sulfate radical (SO) free radicals under the action of ultrasonic waves and ultraviolet light₄∙^-) And simultaneously, the sulfur dioxide and the nitrogen oxide in the flue gas are oxidized and removed. The method does not regenerate the oxidant of the absorption liquid, and does not consider that nitrate radical and nitrite radical in water are converted into raw materials of the electrolyte. CN110585909A discloses a method for purifying flue gas by desulfurization and denitrification simultaneously, which comprises the steps of spraying flue gas at 50-90 ℃ with ammonia absorption liquid, aerating and oxidizing the obtained solution to obtain ammonium sulfate solution; and heating the obtained flue gas for heat exchange, and then adding a catalyst to convert the nitrogen oxides into nitrogen. The method has complex process and causes catalyst poisoning.

Disclosure of Invention

The invention provides a method and a device for circularly purifying sulfur dioxide and nitrogen oxide in flue gas, aiming at realizing the purpose of strengthening removal of sulfur dioxide and nitrogen oxide in the flue gas.

The technical scheme adopted by the invention is as follows:

a method for circularly purifying sulfur dioxide and nitrogen oxide in flue gas by using amino absorption liquid comprises the following steps: firstly, reaction absorption liquid enters a cathode chamber of an electrolytic reactor to convert nitrate radical and nitrite radical into NH₄ ⁺Then enters the anode chamber of the electrolytic reactor to convert sulfate radicals into S at the anode₂O₈ ^2-The solution containing ammonium persulfate obtained by electrolysis is pumped into the spraying atomization system of the absorption tower by using a circulating pump, and the high-temperature flue gas containing sulfur dioxide and nitrogen oxide is introduced from the bottom of the absorption tower, SO that heat exchange is realized in the process, the ammonium persulfate is activated to generate active free radicals with stronger oxidation, and SO in the flue gas is simultaneously used₂And NO_XAnd (4) removing by oxidation, wherein the solution after reaction enters a pipeline from the bottom and is circularly pumped into the electrolytic reactor again, so that the circulation of the process is realized. After multiple cycles, the high-concentration ammonium sulfate is further evaporated and crystallized to obtain the ammonium sulfate byproduct.

Preferably, the concentration of ammonium persulfate generated by electrolysis in the electrolysis reactor is 0.005-1 mol/L.

Preferably, the current density of the cathode and the anode of the electrolytic reactor is 0.5-10 mA/cm²And the electrolysis time is 0.5-8 h.

Preferably, the pH of the solution in the cathode chamber and the anode chamber of the electrolytic reactor is 2-5, the concentration of the ammonium sulfate solution in the cathode chamber is 0.5-3 mol/L, the concentration of the ammonium nitrate solution in the anode chamber is 0.0006-3 mol/L, and the concentration of the ammonium persulfate solution in the anode chamber is 0.005-1 mol/L. .

Preferably, the raw material liquid for electrolyzing the ammonium persulfate in the electrolysis reactor contains 1-3 mol/L ammonium sulfate.

Preferably, the current density of the cathode and the anode in the electrolytic reactor is 0.5-10 mA/cm²The electrolysis time is 2-8 h, and the pH value of the anode chamber is 2-5.

Preferably, the reduction reaction is carried out at the cathode of the electrolytic reactor to convert the nitric acid and nitrite ions into NH₄ ⁺The anode is oxidized to convert sulfate radical into S₂O₈ ^2-And finally, enabling the electrolysis product ammonium persulfate to flow into a spraying atomization system of the absorption tower by using a circulating pump.

A device for circularly purifying sulfur dioxide and nitrogen oxide in flue gas comprises an electrolytic reactor, a circulating pump, an absorption tower and an absorption liquid storage tank; the outlet of the electrolytic reactor is communicated with a spraying and atomizing system of the absorption tower through a pipeline, the flue gas enters from the bottom of the absorption tower, the inlet of the absorption liquid storage tank is communicated with the liquid outlet of the absorption tower, the outlet of the absorption liquid storage tank is connected with the inlet of the electrolytic reactor through a pipeline, and the pipeline is provided with a circulating pump.

Preferably, the flow rate of the circulating pump is 1-30L/min.

Preferably, the liquid inlet of the absorption column is in communication with the anode of the electrolysis cell.

Preferably, the electrolytic reactor comprises a cathode chamber and an anode chamber, wherein the cathode chamber solution is ammonium sulfate and ammonium nitrate, and the anode chamber solution is ammonium persulfate.

Preferably, the spraying and atomizing system is a stainless steel vortex nozzle with the diameter of 2.3-10 cm, and the nozzle is in a fan-shaped form.

Preferably, the anode of the electrolytic reactor is selected from one of pure platinum, titanium-based platinum and graphite electrodes, and the cathode is selected from one of copper-based polypyrrole-plated, titanium-based cobaltosic oxide-plated, titanium-based platinum dioxide-plated, copper-based bismuth-plated and titanium dioxide-plated electrodes.

Preferably, the cathode chamber and the anode chamber of the electrolytic reactor are separated by a diaphragm, and the diaphragm is one of a ceramic membrane, a perfluorosulfonic acid type cation exchange membrane and a quaternary ammonium type anion exchange membrane.

Preferably, the perfluorosulfonic acid type cation exchange membrane is an HDGN membrane, HDCMI membrane, HDNAF membrane or HDJCM membrane.

Preferably, the quaternary ammonium anion exchange membrane is an HDJAM membrane or an HDAMI membrane.

The principle is as follows: after the electrolyzed ammonium persulfate solution is subjected to flue gas desulfurization and denitration, the reaction product is a solution containing ammonium sulfate and ammonium nitrate, and the solution containing ammonium sulfate and ammonium nitrate is subjected to electrolysisAnd electrolyzing in the decomposition reactor to prepare ammonium persulfate solution. Oxidizing SO in flue gas by using ammonium persulfate as oxidant₂And NO_XNO in the flue gas is converted into a compound which is easier to dissolve and absorb, so that the aim of synchronously desulfurizing and denitrifying the flue gas based on an ammonia method is fulfilled. In addition, considering that the flue gas contains a large amount of high-temperature waste heat, in order to fully utilize the heat energy of the flue gas, the ammonium persulfate can be activated in the process of carrying out gas-liquid mass transfer by spraying in the absorption tower.

During the treatment process of the method, the partial chemical reactions involved are as follows:

the principle for preparing ammonium persulfate by electrolyzing ammonium sulfate and ammonium nitrate is as follows:

the electrolytic process has an ion reaction formula:

cathode:

anode:

persulfate activation reaction formula:

based on the amino absorption liquid NO removal reaction formula:

based on amino-group-absorbing liquids SO₂Removing the reaction formula:

based on amino-group-absorbing liquids SO₂The removal of NO in the presence of:

the invention has the following beneficial effects:

1) the raw materials of the ammonium persulfate produced by electrolysis in the electrolysis reactor are derived from the desulfurization and denitrification reaction product. In addition, SO in the flue gas is converted into SO by sulfate radicals generated by activating ammonium persulfate₂And NO_XAfter removal, it is itself reduced to ammonium sulfate, the same as the desulfurization by-product of the invention; meanwhile, nitrate radical and nitrite radical generated in the solution are converted into NH at cathode in the electrolytic bath₄ ⁺Conversion of sulphate to S at the anode₂O₈ ^2-Therefore, the method does not produce secondary pollution in the desulfurization and denitrification and is environment-friendly.

2) The method has good treatment effect on sulfur dioxide and nitrogen oxide in industrial flue gas, and byproducts of ammonium sulfate and ammonium nitrate can be used as electrolytic raw material liquid and also can be used as chemical fertilizer, so that N, S element in the flue gas is recycled, and economic cycle is realized.

3) The waste heat in the flue gas is fully utilized during persulfate activation, no additional substance or energy is needed for activation, the feasibility is high, the cost is low, and the industrial application potential is large.

Drawings

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

In the figure: 1-an electrolytic reactor, 2-a circulating pump, 3-an absorption tower and 4-an absorption liquid storage tank.

Fig. 2 is a schematic diagram of the reactions that mainly occur at the anode and cathode of the membrane electrode.

Detailed Description

The invention is described in more detail below with reference to the figures and the examples, but the scope of the invention is not limited to the description.

Example 1

The flue gas generated by a certain thermal power plant is circularly purified, wherein SO₂、NO_XRespectively at a concentration of 2635 mg/m³、383 mg/m³And the temperature of the flue gas entering the absorption tower is 85 ℃. The cathode chamber and the anode chamber of the electrolytic reactor take a perfluorinated sulfonic acid cation exchange membrane as a diaphragm to containUsing 1mol/L ammonium sulfate solution as anolyte, maintaining the pH of the anolyte at 2-3, selecting a titanium-based platinum-plated electrode as a cathode, selecting a titanium-based cobaltosic oxide-plated electrode as an anode, and controlling the current density of the cathode and the anode to be 8 mA/cm²The electrolysis time is 3.0 h, and the gas-to-liquid ratio of the flue gas desulfurization and denitrification liquid is 25L/m³The result of the system of the small-sized system for removing sulfur and nitrogen in the purified flue gas is that SO in the flue gas₂And NO_XAnd the removal efficiency can reach 99.8 percent and 51.6 percent respectively.

Example 2

Circularly purifying the sulfur dioxide and the nitrogen oxide in the flue gas generated by a certain coke-oven plant, wherein SO₂、NO_XRespectively at a concentration of 800 mg/m³、600 mg/m³And the temperature of the flue gas entering the absorption tower is 70 ℃. The cathode chamber and the anode chamber of the electrolytic reaction chamber use a perfluorinated sulfonic acid cation exchange membrane as a diaphragm, a solution containing 2 mol/L ammonium sulfate as an anolyte, the pH of the anolyte is maintained to be 2-3, a titanium-based platinum-plated electrode is used as a cathode, a titanium-based cobaltosic oxide-plated electrode is used as an anode, and the current densities of the cathode and the anode are both 10 mA/cm²The electrolysis time is 4.0 h, and the gas-liquid ratio of the flue gas denitration liquid is 25L/m³The result of the system of the small-sized system for removing sulfur and nitrogen in the purified flue gas is that SO in the flue gas₂And NO_XAnd the removal efficiency can reach 98.5 percent and 78.3 percent respectively.

Example 3

Circularly purifying the sulfur dioxide and the nitrogen oxide in the flue gas generated by a certain steel plant, wherein SO₂、NO_XRespectively at a concentration of 2457 mg/m³、300mg/m³The temperature of the flue gas entering the absorption tower is 85 ℃. The cathode chamber and the anode chamber of the electrolytic reactor use a perfluorinated sulfonic acid cation exchange membrane as a diaphragm, a solution containing 3 mol/L ammonium sulfate as an anolyte, the pH of the anolyte is maintained to be 2-3, a titanium-based platinum-plated electrode is used as a cathode, a titanium-based cobaltosic oxide-plated electrode is used as an anode, and the current densities of the cathode and the anode are both 10 mA/cm²The electrolysis time is 4.0 h, and the gas-liquid ratio of the flue gas denitration liquid is 25L/m³The result of the system of the small-sized system for removing sulfur and nitrogen in the purified flue gas is that SO in the flue gas₂And NO_XAnd the removal efficiency can reach 98.8 percent and 78.8 percent respectively.

Example 4

A method for circularly purifying sulfur dioxide and nitrogen oxides in flue gas by a circular electrolysis/advanced oxidation-ammonia process comprises the following steps: firstly, inputting high-temperature flue gas containing sulfur dioxide and nitric oxide to the bottom of an absorption tower; the solution containing ammonium persulfate obtained by electrolysis of the electrolysis reactor flows into a spraying and atomizing system of the absorption tower by using a cooling water circulating pump, the sprayed and atomized ammonium persulfate solution can be in gas-liquid contact in the absorption tower, so that indirect heat exchange is realized, and the ammonium persulfate is activated to generate active free radicals with strong oxidation; solution containing active free radicals as flue gas absorption liquid and SO in flue gas₂And NO_XContact reaction to remove SO in flue gas₂And NO_XRemoval by oxidation, SO₂And NO_XIs converted into SO with higher solubility₃ ^2-、SO₄ ^2-、NO₂、NO₂ ^-、NO₃ ^-And (3) plasma products are generated, and the absorption liquid simultaneously contains ammonium sulfate and ammonium nitrate solution, and the solution flows into the absorption liquid storage tank to be used as a raw material liquid for electrolyzing the absorption liquid in the electrolytic reactor to produce ammonium persulfate.

While the present invention has been described in detail with reference to the specific embodiments thereof, the present invention is not limited to the embodiments described above, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.