A method and device for resource treatment of nitrogen-containing waste gas

Abstract

The present invention relates to the technical field of resource recovery treatment of nitrogen-containing waste gas, and specifically discloses a resource recovery treatment method and equipment for nitrogen-containing waste gas, comprising the following steps: (a) preparing a dilute phosphoric acid solution; (b) primary absorption; (b1) inputting the dilute phosphoric acid solution into a first atomizer; (b2) conveying the nitrogen-containing waste gas to a first gas distributor; (b3) the dilute phosphoric acid solution and the nitrogen-containing waste gas undergo countercurrent contact reaction to generate a first mixed solution; (c) catalytic oxidation; (c1) filling a solid-phase catalyst into a fixed-bed reactor; (c2) conveying the treated waste gas to the fixed-bed reactor; (c3) passing oxygen into the fixed-bed reactor; (d) secondary absorption; (d1) conveying the remaining mixed waste gas and oxygen to a second gas distributor; (d2) inputting a potassium hydroxide solution into a second atomizer for reaction to generate a second mixed solution. The present invention has the characteristics of high resource utilization, high waste gas absorption rate and low treatment cost.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recovery treatment of nitrogen-containing waste gas, and in particular to a resource recovery treatment method and equipment for nitrogen-containing waste gas. Background Art

[0002] With the rapid development of industry in recent years, the scope and amount of use of organic nitrogen compounds and inorganic ammonium salts have increased significantly, and the scale of nitrogen-containing waste gas generation is also expanding. Chemical production processes generate a large amount of malodorous and irritating waste gas, such as ammonia, trimethylamine, formamide, nitrogen dioxide, and other typical inorganic ammonia, organic amines, and nitrogen oxides. Therefore, nitrogen-containing waste gas has become one of the main targets of pollution control.

[0003] At present, physical and chemical methods are often used to treat this type of waste gas, mainly including adsorption, absorption, thermal destruction and plasma methods. The adsorption method often uses activated carbon as the adsorption medium, but activated carbon has a good adsorption effect on non-polar compounds and poor adsorption performance for polar substances (such as methylamines). It has problems such as low adsorption capacity, short penetration time, frequent replacement cycles and high operating costs. The absorption method is not suitable for situations such as intermittent pollutant emissions and large changes in pollution loads. In addition, the waste liquid after absorption is prone to secondary pollution. The thermal destruction method has expensive operating costs, which few companies can afford, and there are also problems with equipment safety. Plasma technology is a relatively new treatment technology with large investment, low safety and high operating and maintenance costs.

[0004] Fertilizers come in a variety of types. Based on their effectiveness, they can be categorized as nitrogen fertilizers, potash fertilizers, phosphate fertilizers, and compound fertilizers. Industrial fertilizer production using chemical or biosynthetic technologies is associated with high energy consumption, significant pollution, and high waste emissions. Therefore, the search for safe, environmentally friendly, green, and economical fertilizer production processes is of great significance.

[0005] Publication No. "CN106348267A" discloses a method for producing diammonium phosphate from nitrogen-phosphorus wastewater. Specifically, the nitrogen-phosphorus wastewater generated in the production process of monoammonium phosphate is transported to a diammonium phosphate tail gas scrubber as a washing liquid to make up water, and to wash and absorb the tail gas of the diammonium phosphate device; the diammonium phosphate tail gas washing circulating liquid is then transported to the scrubber and mixed with concentrated phosphoric acid in proportion to absorb the dust- and ammonia-containing waste gas from the diammonium phosphate device trunk line; the concentrated phosphoric acid and the scrubber washing liquid are transported to a tubular reactor storage tank to mix and prepare the acid to achieve the specific gravity and neutralization degree required for the reaction of the diammonium phosphate tubular reactor; the appropriately proportioned mixed acid is transported to the tubular reactor to react with liquid ammonia to form a slurry that is quickly sprayed into the bed layer of a granulator for granulation; the method produces diammonium phosphate products by recycling the nitrogen-phosphorus wastewater generated in the production process of the monoammonium phosphate device, but there is still a problem of communicating the utilization rate of nitrogen and phosphorus elements in the wastewater. Summary of the Invention

[0006] In order to solve the above technical problems existing in the existing methods for treating nitrogen-containing waste gas, the present invention provides a method and equipment for resource-based treatment of nitrogen-containing waste gas, which has the characteristics of high resource utilization rate, high waste gas absorption rate and low treatment cost.

[0007] The first technical solution of the present invention is a method for recycling nitrogen-containing waste gas, comprising the following steps:

[0008] (a) preparing a dilute phosphoric acid solution;

[0009] The preparation of the dilute phosphoric acid solution comprises the following steps:

[0010] (a1) adding an appropriate amount of concentrated phosphoric acid solution into the first reaction kettle;

[0011] (a2) adding an appropriate amount of deionized water into the first storage tank;

[0012] (a3) starting the agitator in the first reactor, adding the deionized water in step (a2) into the first reactor to dilute the concentrated phosphoric acid solution to obtain a dilute phosphoric acid solution;

[0013] (b) primary absorption;

[0014] (b1) inputting the dilute phosphoric acid solution in step (a3) ​​into a first atomizer at the top of a first absorption tower, and spraying the dilute phosphoric acid solution downward from the first atomizer into atomization;

[0015] (b2) transporting the nitrogen-containing waste gas to a first gas distributor at the bottom of the first absorption tower, and dispersing the nitrogen-containing waste gas in the first absorption tower by the first gas distributor;

[0016] (b3) reacting the atomized dilute phosphoric acid solution in step (b1) with the nitrogen-containing waste gas dispersed in step (b2) in a countercurrent manner to generate a first mixed solution containing a certain concentration of ammonium phosphate;

[0017] (b4) feeding the first mixed solution in step (b3) into a second reactor and performing vacuum distillation to obtain ammonium phosphate solid and water;

[0018] (b5) returning the water in step (b4) to the first storage tank for reuse;

[0019] (b6) transporting the ammonium phosphate solid in step (b4) to a second storage tank;

[0020] (c) catalytic oxidation;

[0021] (c1) filling a solid-phase catalyst into a fixed-bed reactor;

[0022] (c2) transporting the waste gas treated in step (b3) to the fixed bed reactor in step (c1);

[0023] (c3) introducing oxygen into the fixed bed reactor in step (c1) to carry out a catalytic oxidation reaction with the waste gas in step (c2) in the fixed bed reactor;

[0024] (d) secondary absorption;

[0025] (d1) conveying the remaining waste gas and oxygen after mixing in step (c3) to the second gas distributor at the bottom of the second absorption tower;

[0026] (d2) adding an appropriate amount of potassium hydroxide solution to a third storage tank, and inputting the potassium hydroxide solution in the third storage tank into a second atomizer at the top of the second absorption tower, wherein the potassium hydroxide solution is sprayed downward from the second atomizer and atomized, and is in countercurrent contact with the mixed gas in step (d1) to react, thereby generating a second mixed solution containing a certain concentration of potassium nitrate;

[0027] (d3) feeding the second mixed solution into a third reactor and performing vacuum distillation to obtain potassium nitrate solid and water;

[0028] (d4) returning the water in step (d3) to the first storage tank for reuse;

[0029] (d5) transporting the potassium nitrate solid in step (d3) to a fourth storage tank.

[0030] The present invention comprises the following steps: firstly adding a concentrated phosphoric acid solution into a first reaction kettle, then diluting the concentrated phosphoric acid solution by adding deionized water, and accurately controlling the amount of deionized water added, thereby preparing a dilute phosphoric acid solution of required concentration; spraying the prepared dilute phosphoric acid solution from the top of a first absorption tower into the first absorption tower through a first atomizer; dispersing the nitrogen-containing waste gas to be treated from the bottom of the first absorption tower into the first absorption tower through a first gas distributor; the nitrogen-containing waste gas slowly rises from bottom to top, and the atomized dilute phosphoric acid solution slowly falls from top to bottom; the dilute phosphoric acid solution and the nitrogen-containing waste gas react in countercurrent contact; the dilute phosphoric acid solution absorbs the inorganic ammonia in the nitrogen-containing waste gas to generate an ammonium phosphate solution; and then After the ammonium phosphate solution is distilled under reduced pressure, ammonium phosphate solid and water are obtained, and the water is returned to the first storage tank for reuse. The ammonium phosphate solid provides a certain economic source for agricultural production as a compound fertilizer (nitrogen fertilizer + phosphate fertilizer), which not only further protects the environment, but also improves resource utilization and saves resources. The reaction rate of the whole process is relatively fast, and the dilute phosphoric acid solution has a high absorption efficiency for inorganic ammonia in nitrogen-containing waste gas, which lays a good foundation for subsequent treatment processes and technologies and ensures that the inorganic ammonia in the nitrogen-containing waste gas is fully absorbed. The present invention fills a solid-phase catalyst in a fixed-bed reactor, and then introduces oxygen into the fixed-bed reactor, and uses a catalytic oxidation method to catalyze the oxidation reaction of nitrogen monoxide in the waste gas into The nitrogen dioxide gas can be fully absorbed and processed by the subsequent alkali solution, and the addition of oxygen can also pressurize the entire reaction system, and can perform online pressure compensation for the gas consumed in the reaction, greatly improving the reaction efficiency of nitrogen monoxide. The present invention sprays the prepared potassium hydroxide solution from the top of the first absorption tower into the second absorption tower through the first atomizer, and disperses the nitrogen dioxide gas to be treated from the bottom of the second absorption tower into the second absorption tower through the second gas distributor. The nitrogen dioxide gas rises slowly from bottom to top, and the atomized potassium hydroxide solution falls slowly from top to bottom. The potassium hydroxide solution and the nitrogen dioxide gas are contacted and reacted in countercurrent, and the potassium hydroxide solution reacts with the nitrogen dioxide. After the gas absorption reaction, a potassium nitrate solution is generated, and the potassium nitrate solution is then subjected to reduced pressure distillation to obtain potassium nitrate solid and water. The water is returned to the first storage tank for reuse, and the potassium nitrate solid is used as a compound fertilizer (nitrogen fertilizer + potash fertilizer), which effectively saves the investment cost of subsequent treatment and further realizes the resource treatment of waste gas. The entire process of nitrogen dioxide gas introduction is accompanied by oxygen introduction. Oxygen can always oxidize the residual nitric oxide in the waste gas, making the waste gas treatment more sufficient. At the same time, oxygen replaces the waste gas to pressurize the reaction system, and can perform online pressure compensation for the waste gas consumed in the reaction, greatly improving the absorption efficiency of the waste gas, and can achieve complete absorption and zero emission of the waste gas.The present invention, through primary absorption, catalytic oxidation, and secondary absorption processes, absorbs nitrogen from waste gas, ultimately producing ammonium phosphate solids and potassium nitrate solids. These solids can be used as agricultural fertilizers. This treatment of nitrogen-containing waste gas not only eliminates the production of harmful secondary products but also produces waste materials and water needed for agriculture, achieving safe, environmentally friendly, green, and economical treatment of nitrogen-containing waste gas.

[0031] As an advantage, it also includes the steps of:

[0032] (e) Online monitoring;

[0033] (e1) adjusting the flow rate of deionized water in the first reactor online using a density meter to control the concentration of the dilute phosphoric acid solution;

[0034] (e2) adjusting the cooling water flow rate in the first temperature-controlled jacket outside the first reactor online by using a first thermometer to control the temperature in the first reactor to reach a certain set value;

[0035] (e3) adjusting the cooling water flow rate in the second temperature-controlled jacket outside the first absorption tower online by a second thermometer to control the temperature in the first absorption tower to reach a certain set value;

[0036] (e4) adjusting the cooling water flow rate in the fourth temperature-control jacket outside the second absorption tower online by a fourth thermometer to control the temperature in the second absorption tower to reach a certain set value;

[0037] (e5) online adjusting the cooling water flow rate in the third temperature control jacket outside the fixed bed reactor by a third thermometer to control the temperature in the fixed bed reactor to reach a certain set value;

[0038] (e6) connecting an ammonia gas detector to the first absorption tower in step (b), wherein the ammonia gas detector is interlocked with a third back-pressure valve for the dilute phosphate solution online, and adjusting the opening of the third back-pressure valve online to adjust the flow rate of the dilute phosphate solution;

[0039] (e7) A reduced nitrogen detector is connected to the fixed bed reactor in step (c), and the reduced nitrogen detector is online interlocked with the tenth oxygen back pressure valve, and the oxygen flow rate is adjusted by online adjusting the opening of the tenth back pressure valve;

[0040] (e8) A total nitrogen detector is connected to the second absorption tower in step (d), and the total nitrogen detector is online interlocked with the fourteenth back pressure valve of the potassium hydroxide solution and the thirteenth back pressure valve of the oxygen. The flow rate of the potassium hydroxide solution and the flow rate of the oxygen are adjusted by online adjusting the opening size of the fourteenth back pressure valve and the thirteenth back pressure valve.

[0041] The first back-pressure valve of the deionized water is interlocked online through the density meter to adjust the flow of the deionized water, so as to realize the precise control of the concentration of the concentrated phosphoric acid solution to be diluted into the dilute phosphoric acid solution; the second back-pressure valve of the cooling water is interlocked online through the first thermometer, and the opening size of the second back-pressure valve is adjusted online to adjust the flow of the cooling water, thereby online controlling the temperature in the first reactor, so that the concentrated phosphoric acid solution can be better diluted into the dilute phosphoric acid solution; the fifth back-pressure valve of the cooling water is interlocked online through the second thermometer, and the opening size of the fifth back-pressure valve is adjusted online to adjust the flow of the cooling water, thereby online controlling the temperature in the first absorption tower, so that the dilute phosphoric acid solution can better absorb the inorganic ammonia in the nitrogen-containing waste gas to generate an ammonium phosphate solution; the fifteenth back-pressure valve of the cooling water is interlocked online through the fourth thermometer Valve, by online adjusting the opening size of the fifteenth back-pressure valve, adjusting the cooling water flow, thereby online controlling the temperature in the second absorption tower, so that the potassium hydroxide solution can better absorb the nitrogen dioxide gas to generate potassium nitrate solution after reaction; through the third thermometer online interlocking the cooling water eleventh back-pressure valve, by online adjusting the opening size of the eleventh back-pressure valve, adjusting the cooling water flow, thereby online controlling the temperature in the fixed bed reactor, so that the nitrogen monoxide in the exhaust gas can be catalytically oxidized and converted into nitrogen dioxide gas more efficiently; through the ammonia detector online interlocking the third back-pressure valve of the dilute phosphoric acid solution, by online adjusting the opening size of the third back-pressure valve, adjusting the flow rate of the dilute phosphoric acid solution, so that the ammonia content detected by the ammonia detector in the first absorption tower is always at the set value, And ensure that the inorganic ammonia in the exhaust gas can be absorbed as completely as possible by the dilute phosphoric acid solution; through the online interlocking of the oxygen tenth back pressure valve by the reduced nitrogen detector, by adjusting the opening size of the tenth back pressure valve online, adjust the oxygen flow rate, so that the reduced nitrogen content detected by the reduced nitrogen detector in the fixed bed reactor is always at the set value, thereby ensuring that the reduced nitrogen in the exhaust gas can be oxidized into nitrogen dioxide as completely as possible by oxygen; through the online interlocking of the potassium hydroxide solution fourteenth back pressure valve and the oxygen thirteenth back pressure valve by the total nitrogen detector, by adjusting the opening size of the fourteenth back pressure valve online, adjust the flow rate of potassium hydroxide solution, so that the nitrogen dioxide in the second absorption tower can be reacted as completely as possible by the potassium hydroxide solution; by adjusting the opening size of the thirteenth back pressure valve online, adjust the oxygen The flow rate is adjusted so that the reduced nitrogen in the second absorption tower can be oxidized into nitrogen dioxide as completely as possible by oxygen. As a whole, the total nitrogen content in the second absorption tower detected by the total nitrogen detector is always at the set value, thereby ensuring that the nitrogen in the exhaust gas has been absorbed as completely as possible and that the gas finally discharged will not pollute the air. The temperature and nitrogen content in the exhaust gas involved in the mixing and reaction process of the exhaust gas are monitored in real time throughout the entire process, and the corresponding valve opening is interlocked. The cooling water valve is interlocked online through an online thermometer, and the valve opening is adjusted online to adjust the cooling water flow, thereby controlling the mixing and reaction temperature online, realizing precise temperature control during the gas mixing and reaction process, and laying a good foundation for efficient exhaust gas treatment.An online ammonia detector and a nitrogen oxide detector are used to measure the concentrations of inorganic ammonia and nitrogen oxides in the reactor in real time. The first and second absorption towers, fixed-bed reactors, dilute phosphoric acid solution, potassium hydroxide solution, and nitrogen-containing waste gas valves are interlocked online. By adjusting the valve openings online, the controllability of the reaction process is ensured. This successfully achieves high-efficiency, fully closed-loop waste gas treatment, ensuring that nitrogen-containing waste gas meets emission requirements. This effectively reduces costs and avoids harm to personnel caused by waste gas overflows due to intermittent sampling operations, resulting in significant practical value and economic benefits.

[0042] As an advantage, it also includes the steps of:

[0043] (f) discharge of waste gas;

[0044] By observing the reading of the total nitrogen detector in step (e8), determine whether the total nitrogen content in the exhaust gas meets the standard;

[0045] If the total nitrogen content in the exhaust gas is lower than the emission standard, the exhaust gas will be discharged into the atmosphere through the pipeline;

[0046] If the total nitrogen content in the waste gas is higher than the emission standard, the waste gas will continue to remain in the second absorption tower, and the online total nitrogen detector will be used to close the 16th back pressure valve for emptying, increase the opening of the 14th back pressure valve for potassium hydroxide solution and the 13th back pressure valve for oxygen, and continue to treat until the waste gas meets the standard and is discharged into the atmosphere. The total nitrogen detector is online interlocked with the 16th back pressure valve for emptying. Only when the total nitrogen content in the waste gas is lower than the emission standard can it be discharged into the atmosphere through the pipeline. If the total nitrogen content in the waste gas is higher than the emission standard, the nitrogen-containing gas compounds therein need to be reprocessed until they meet the standard before they can be discharged, thereby ensuring that the gas finally discharged will not pollute the air.

[0047] Preferably, the mass concentration of the concentrated phosphoric acid solution in step (a1) is 50% to 70%. More preferably, the mass concentration of the concentrated phosphoric acid solution in step (a1) is 55% to 65%. More preferably, the mass concentration of the concentrated phosphoric acid solution in step (a1) is 60%. The mass concentration limit of the concentrated phosphoric acid solution is adjusted based on the concentration of the dilute phosphoric acid solution required, which is in turn determined based on the content of inorganic ammonia in the nitrogen-containing waste gas to be treated, in order to absorb the inorganic ammonia in the nitrogen-containing waste gas as completely as possible into the ammonium phosphate solution.

[0048] Preferably, the temperature of the dilute phosphoric acid solution in step (a3) ​​is 20°C to 40°C. More preferably, the temperature of the dilute phosphoric acid solution in step (a3) ​​is 25°C to 35°C. More preferably, the temperature of the dilute phosphoric acid solution in step (a3) ​​is 30°C. The temperature limit here is to better dilute the concentrated phosphoric acid solution into a dilute phosphoric acid solution.

[0049] Preferably, the mass concentration of the dilute phosphoric acid solution in step (a3) ​​is 30% to 35%. More preferably, the mass concentration of the dilute phosphoric acid solution in step (a3) ​​is 32% to 34%. More preferably, the mass concentration of the dilute phosphoric acid solution in step (a3) ​​is 33%. The mass concentration of the dilute phosphoric acid solution is determined based on the content of inorganic ammonia in the nitrogen-containing waste gas to be treated, in order to absorb the inorganic ammonia in the nitrogen-containing waste gas as completely as possible into the ammonium phosphate solution.

[0050] Preferably, the flow rate of the dilute phosphoric acid solution in step (b1) is 60 mL / min to 80 mL / min. More preferably, the flow rate of the dilute phosphoric acid solution in step (b1) is 65 mL / min to 75 mL / min. More preferably, the flow rate of the dilute phosphoric acid solution in step (b1) is 70 mL / min. The limitation on the flow rate of the dilute phosphoric acid solution here is determined based on the content of inorganic ammonia in the nitrogen-containing waste gas to be treated, which can better ensure that the inorganic ammonia in the waste gas can be absorbed as completely as possible by the dilute phosphoric acid solution.

[0051] Preferably, the flow rate of the nitrogen-containing waste gas in step (b2) is 15 mL / min to 25 mL / min. More preferably, the flow rate of the nitrogen-containing waste gas in step (b2) is 18 mL / min to 22 mL / min. More preferably, the flow rate of the nitrogen-containing waste gas in step (b2) is 20 mL / min. The limit on the flow rate of the nitrogen-containing waste gas is determined based on the entire treatment system. Within this flow rate range, the nitrogen-containing waste gas can be completely treated while also ensuring a good treatment rate.

[0052] Preferably, the reaction time in step (b3) is 30 min to 90 min. More preferably, the reaction time in step (b3) is 40 min to 80 min. More preferably, the reaction time in step (b3) is 50 min to 70 min. More preferably, the reaction time in step (b3) is 55 min to 65 min. More preferably, the reaction time in step (b3) is 60 min. The reaction time limit here is to ensure that the inorganic ammonia in the nitrogen-containing waste gas is absorbed as completely as possible into the ammonium phosphate solution while taking into account timeliness.

[0053] Preferably, the reaction temperature in step (b3) is 30°C to 40°C. More preferably, the reaction temperature in step (b3) is 33°C to 38°C. More preferably, the reaction temperature in step (b3) is 35°C. Within this temperature range, inorganic ammonia in the nitrogen-containing waste gas can be more efficiently absorbed by the dilute phosphoric acid solution.

[0054] Preferably, the reaction pressure in step (b3) is 1 MPa to 4 MPa. More preferably, the reaction pressure in step (b3) is 1.5 MPa to 3.5 MPa. More preferably, the reaction pressure in step (b3) is 2 MPa to 3 MPa. More preferably, the reaction pressure in step (b3) is 2.2 MPa to 2.8 MPa. More preferably, the reaction pressure in step (b3) is 2.5 MPa. Within this reaction pressure range, the inorganic ammonia in the nitrogen-containing waste gas can be more efficiently absorbed by the dilute phosphoric acid solution; this enables the inorganic ammonia in the waste gas to come into more sufficient contact with the dilute phosphoric acid solution, thereby improving the absorption efficiency of the inorganic ammonia in the waste gas while ensuring the absorption effect.

[0055] Preferably, the solid-phase catalyst in step (c1) is a transition metal compound. The transition metal compound can more rapidly catalyze the reaction of the reduced nitrogen in the waste gas into nitrogen dioxide; under the action of the solid-phase catalyst, the nitrogen-containing waste gas and oxygen are catalytically oxidized, achieving the purpose of oxidizing nitrogen-containing compounds into nitrogen oxides. The operation is simple and easy to control, improving the oxidation treatment efficiency while reducing the treatment cost and energy consumption.

[0056] Preferably, the transition metal compound is at least one of Ce2O3, CeO2, Ce2(CO3)3, xCe2O3·(1 - x)CuO, Ce - Cu, Ce - Fe, Ce - Mn, Ce - Cr, MnO2, MnO, xMn2O3·(1 - x)CuO, xMnO·(1 - x)CuO, Mn3O4, Mn(OH)2, MnCO3, xFe2O3·(1 - x)MnO2, xFe2O3·(1 - x)CuO, Fe(OH)3, Fe2O3, Fe3O4, CuO, Cu(OH)2, CuMn2O4, Cr2O3, Cr(OH)3, xCr2O3·(1 - x)CuO, xCr2O3·(1 - x)MnO2, or CuCr2O4, where 0 < x < 1. The selection of transition metal compounds is relatively diverse, and choosing the specified compounds as catalysts can have a better catalytic effect on the reduced nitrogen in the waste gas.

[0057] Preferably, the particle size of the solid-phase catalyst in the step (c1) is 0.25 mm to 10 mm. More preferably, the particle size of the solid-phase catalyst in the step (c1) is 0.5 mm to 8 mm. More preferably, the particle size of the solid-phase catalyst in the step (c1) is 1 mm to 6 mm. More preferably, the particle size of the solid-phase catalyst in the step (c1) is 2 mm to 5 mm. More preferably, the particle size of the solid-phase catalyst in the step (c1) is 3 mm to 4 mm. More preferably, the particle size of the solid-phase catalyst in the step (c1) is 3.5 mm. The particle size of the solid-phase catalyst within the limited range can form a good porosity, thereby having a just catalytic effect on the reaction.

[0058] Preferably, the voidage of the fixed bed reactor after filling the solid-phase catalyst in step (c1) is 30% to 50%. More preferably, the voidage of the fixed bed reactor after filling the solid-phase catalyst in step (c1) is 35% to 45%. More preferably, the voidage of the fixed bed reactor after filling the solid-phase catalyst in step (c1) is 40%. A voidage within a defined range ensures good gas flow while also providing a good catalytic effect on the oxidation reaction of reduced nitrogen.

[0059] Preferably, a solid-phase catalyst support is provided within the fixed-bed reactor. The solid-phase catalyst support is selected from at least one of activated carbon, molecular sieve, or montmorillonite. The selected solid-phase catalyst support can effectively support the solid-phase catalyst, providing a relatively large release area between the solid-phase catalyst and the reaction gas, thereby achieving a better catalytic effect on the rapid degradation of nitrogen-containing waste gas by oxygen.

[0060] Preferably, the flow rate of the waste gas in step (c2) is 20 mL / min to 40 mL / min. More preferably, the flow rate of the waste gas in step (c2) is 25 mL / min to 35 mL / min. More preferably, the flow rate of the waste gas in step (c2) is 30 mL / min. The limit on the waste gas flow rate here is determined based on the content of reduced nitrogen in the nitrogen-containing waste gas to be treated, which can better ensure that the reduced nitrogen in the waste gas can be catalytically oxidized as completely as possible by oxygen.

[0061] Preferably, the flow rate of oxygen in the step (c3) is 30 mL / min to 60 mL / min. More preferably, the flow rate of oxygen in the step (c3) is 35 mL / min to 55 mL / min. More preferably, the flow rate of oxygen in the step (c3) is 40 mL / min to 50 mL / min. More preferably, the flow rate of oxygen in the step (c3) is 45 mL / min. The limitation on the oxygen flow rate here is determined based on the content of reduced nitrogen in the nitrogen-containing waste gas to be treated, which can better ensure that the reduced nitrogen in the waste gas is catalytically oxidized as completely as possible, and can also maintain the pressure in the fixed bed reactor at a good level.

[0062] Preferably, the reaction temperature in step (c3) is 210°C to 280°C. More preferably, the reaction temperature in step (c3) is 220°C to 270°C. More preferably, the reaction temperature in step (c3) is 230°C to 260°C. More preferably, the reaction temperature in step (c3) is 240°C to 250°C. More preferably, the reaction temperature in step (c3) is 245°C. Within this temperature range, the reduced nitrogen in the nitrogen-containing exhaust gas can be more efficiently catalytically oxidized to nitrogen dioxide by oxygen.

[0063] Preferably, the reaction pressure in step (c3) is 5 MPa to 8 MPa. More preferably, the reaction pressure in step (c3) is 5.5 MPa to 7.5 MPa. More preferably, the reaction pressure in step (c3) is 6 MPa to 7 MPa. More preferably, the reaction pressure in step (c3) is 6.5 MPa. Within this reaction pressure range, the reduced nitrogen in the nitrogen-containing exhaust gas can be more efficiently catalytically oxidized by oxygen; thereby enabling the reduced nitrogen monoxide in the exhaust gas to more fully contact with oxygen and the catalyst, thereby improving the catalytic oxidation efficiency of the reduced nitrogen monoxide in the exhaust gas while ensuring the absorption effect.

[0064] Preferably, the reaction time in step (c3) is 20 min to 60 min. More preferably, the reaction time in step (c3) is 25 min to 55 min. More preferably, the reaction time in step (c3) is 30 min to 50 min. More preferably, the reaction time in step (c3) is 35 min to 45 min. More preferably, the reaction time in step (c3) is 40 min. The limitation on the reaction time here is to ensure the most complete catalytic oxidation of the reduced nitrogen monoxide in the nitrogen-containing exhaust gas while taking into account timeliness.

[0065] Preferably, the oxygen flow rate in step (d1) is 40 mL / min to 50 mL / min. More preferably, the oxygen flow rate in step (d1) is 42 mL / min to 47 mL / min. More preferably, the oxygen flow rate in step (d1) is 45 mL / min. The limitation on the oxygen flow rate here is determined based on the content of reduced nitrogen in the nitrogen-containing waste gas to be treated, which can better ensure that the reduced nitrogen in the waste gas is catalytically oxidized as completely as possible and can also maintain the pressure in the second absorption tower at a good level.

[0066] Preferably, the waste gas flow rate in the step (d1) is 30 mL / min to 60 mL / min. More preferably, the waste gas flow rate in the step (d1) is 35 mL / min to 55 mL / min. More preferably, the waste gas flow rate in the step (d1) is 40 mL / min to 50 mL / min. More preferably, the waste gas flow rate in the step (d1) is 45 mL / min. The limitation on the waste gas flow rate here is determined based on the nitrogen dioxide to be treated and the residual reduced nitric oxide content, which can better ensure that the nitrogen dioxide in the waste gas is absorbed as completely as possible, and ensure that the residual reduced nitric oxide in the waste gas can also be oxidized to nitrogen dioxide by oxygen and then absorbed.

[0067] Preferably, the mass concentration of the potassium hydroxide solution in step (d2) is 13% to 18%. More preferably, the mass concentration of the potassium hydroxide solution in step (d2) is 15% to 17%. More preferably, the mass concentration of the potassium hydroxide solution in step (d2) is 16%. The mass concentration of the potassium hydroxide solution is determined based on the amount of nitrogen dioxide to be absorbed, in order to ensure that the nitrogen dioxide is absorbed as completely as possible into the potassium nitrate solution.

[0068] Preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 60 mL / min to 160 mL / min. More preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 70 mL / min to 150 mL / min. More preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 80 mL / min to 140 mL / min. More preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 90 mL / min to 130 mL / min. More preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 100 mL / min to 120 mL / min. More preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 105 mL / min to 115 mL / min. More preferably, the flow rate of the potassium hydroxide solution in the step (d2) is 110 mL / min. The flow rate of the potassium hydroxide solution is limited here based on the amount of nitrogen dioxide that needs to be absorbed, so that the nitrogen dioxide can be absorbed as completely as possible into potassium nitrate solution.

[0069] Preferably, the reaction temperature in step (d2) is 20° C. to 35° C. More preferably, the reaction temperature in step (d2) is 25° C. to 30° C. More preferably, the reaction temperature in step (d2) is 28° C. Within this temperature range, nitrogen dioxide can be more efficiently absorbed by the potassium hydroxide solution.

[0070] Preferably, the reaction pressure in step (d2) is 2.5 MPa to 5 MPa. More preferably, the reaction pressure in step (d2) is 3 MPa to 4.5 MPa. More preferably, the reaction pressure in step (d2) is 3.5 MPa to 4 MPa. More preferably, the reaction pressure in step (d2) is 3.8 MPa. Within this reaction pressure range, nitrogen dioxide can be more efficiently absorbed by the potassium hydroxide solution; the nitrogen dioxide can more fully contact the potassium hydroxide solution, thereby improving the absorption efficiency of nitrogen dioxide while ensuring the absorption effect.

[0071] Preferably, the reaction time in step (d2) is 30 to 45 minutes. More preferably, the reaction time in step (d2) is 35 to 40 minutes. More preferably, the reaction time in step (d2) is 38 minutes. The reaction time limit herein is to ensure that the nitrogen dioxide is absorbed as completely as possible into the potassium nitrate solution while taking into account timeliness.

[0072] Preferably, the emission standard in step (f) is that the mass concentration of total nitrogen in the exhaust gas does not exceed 5×10 -4 mg / L. The total nitrogen content in nitrogen-containing waste gas is controlled and discharged under this standard, which will not cause air pollution.

[0073] A second technical solution of the present invention is a resource recovery treatment device for nitrogen-containing waste gas, comprising a first storage tank, a drain outlet of the first storage tank being connected to a first reactor via a pipeline, a first temperature-control jacket being provided on an outer circumference of the first reactor, and a water inlet of the first temperature-control jacket being connected to a cooling water source;

[0074] The discharge port of the first reactor is connected to a first absorption tower via a pipeline. A first atomizer is provided at the top of the first absorption tower, and the first atomizer is connected to the discharge port of the first reactor via a pipeline. A first gas distributor is provided at the bottom of the first absorption tower, and the first gas distributor is connected to a nitrogen-containing waste gas source via a pipeline. A second temperature-control jacket is provided on the outer circumference of the first absorption tower, and a water inlet of the second temperature-control jacket is connected to a cooling water source.

[0075] The liquid outlet of the first absorption tower is connected to the second reactor through a pipeline, the water outlet of the second reactor is connected to the first storage tank through a pipeline, and the solid product outlet of the second reactor is connected to the second storage tank through a pipeline;

[0076] The exhaust port of the first absorption tower is connected to a fixed bed reactor via a pipeline, the air inlet of the fixed bed reactor is connected to an oxygen source via a pipeline, and the interior of the fixed bed reactor is filled with a solid-phase catalyst; a third temperature-control jacket is provided on the outer circumference of the fixed bed reactor, and the water inlet of the third temperature-control jacket is connected to a cooling water source via a pipeline;

[0077] The system further comprises a second absorption tower, wherein a second gas distributor is provided at the bottom of the second absorption tower, the second gas distributor is connected to the exhaust port of the fixed bed reactor via a pipeline, and the second gas distributor is connected to an oxygen source via a pipeline; a second atomizer is provided at the top of the second absorption tower, the second atomizer is connected to a third storage tank via a pipeline, the third storage tank is located outside the second absorption tower, and the third storage tank is filled with potassium hydroxide solution; the exhaust port of the second absorption tower is connected to the outside air via a pipeline; a fourth temperature control jacket is provided on the outer circumference of the second absorption tower, and the water inlet of the fourth temperature control jacket is connected to a cooling water source;

[0078] The drain port of the second absorption tower is connected to the third reactor through a pipeline, the drain port of the third reactor is connected to the first storage tank through a pipeline, and the drain port of the third reactor is connected to the fourth storage tank through a pipeline.

[0079] The present invention provides a first storage tank to store deionized water for accurately diluting a concentrated phosphoric acid solution, provides a first reactor to prepare a dilute phosphoric acid solution from the concentrated phosphoric acid solution, and provides a first temperature-controlling jacket on the outer circumference of the first reactor. Cooling water is used to accurately control the temperature of the dilute phosphoric acid solution during the preparation process, thereby quickly cooling down the heat during the dilution process and preventing the phosphoric acid solution from decomposing. The present invention provides a first absorption tower to achieve complete absorption of inorganic ammonia in nitrogen-containing waste gas by the dilute phosphoric acid solution. A first atomizer is provided at the top of the first absorption tower to atomize and spray the dilute phosphoric acid solution from the top of the first absorption tower into the first absorption tower, thereby enabling the dilute phosphoric acid solution to more fully contact and react with the inorganic ammonia in the nitrogen-containing waste gas. By arranging a first gas distributor at the bottom of the first absorption tower, the nitrogen-containing waste gas is well distributed in the first absorption tower, so that it can be fully countercurrently contacted and reacted with the falling dilute phosphate solution, so that the dilute phosphate solution absorbs the inorganic ammonia in the nitrogen-containing waste gas to generate an ammonium phosphate solution; by arranging a second temperature-controlled jacket on the outer peripheral surface of the first absorption tower, cooling water is used to accurately control the temperature during the entire countercurrent contact reaction process, thereby ensuring the full reaction and absorption of the inorganic ammonia; the present invention arranges a second reactor to receive the ammonium phosphate solution generated after the reaction, thereby further separating the ammonium phosphate solution into ammonium phosphate solid and water; a second storage tank is arranged to contain the separated ammonium phosphate solid; the water is returned to the first storage tank for reuse Ammonium phosphate solid as compound fertilizer provides a certain economic source for agricultural production, which not only further protects the environment, but also improves resource utilization and saves resources. The reaction rate of the whole process is relatively fast, and the absorption efficiency of the dilute phosphoric acid solution for the inorganic ammonia in the nitrogen-containing waste gas is relatively high, which lays a good foundation for the subsequent treatment process and technology, and ensures that the inorganic ammonia in the nitrogen-containing waste gas is fully absorbed; the present invention catalytically oxidizes the reduced nitrogen monoxide in the waste gas into nitrogen dioxide gas by setting a fixed bed reactor; the oxidation process of the reduced nitrogen monoxide is made faster by filling the interior of the fixed bed reactor with a solid-phase catalyst; the third temperature control jacket is set on the outer peripheral surface of the fixed bed reactor, and cooling water is used to accurately control the entire catalytic oxidation reaction process. The temperature during the process is increased, thereby allowing the reduced nitric oxide to be more fully converted into nitrogen dioxide gas; the addition of oxygen can also pressurize the entire reaction system, and can perform online pressure compensation for the gas consumed in the reaction, greatly improving the reaction efficiency of nitric oxide; the present invention provides a second absorption tower, on the one hand, to achieve the potassium hydroxide solution absorbing the reacted nitrogen dioxide to form a potassium nitrate solution, and on the other hand, to re-react the residual reduced nitric oxide; by providing a second gas distributor at the bottom of the second absorption tower, the mixed gas is well distributed in the second absorption tower, so that it can be fully countercurrently contacted and reacted by the falling potassium hydroxide solution, so that the potassium hydroxide solution absorbs the nitrogen dioxide in the mixed gas to form a potassium nitrate solution;A second atomizer is provided at the top of the second absorption tower to atomize and spray the potassium hydroxide solution from the top of the second absorption tower into the second absorption tower, so that the potassium hydroxide solution can more fully contact and react with the nitrogen dioxide in the mixed gas; a third storage tank is provided to store the potassium hydroxide solution; a fourth temperature-controlled jacket is provided on the outer peripheral surface of the second absorption tower, and cooling water is used to accurately control the temperature during the entire reaction process, so that the nitrogen dioxide can be more fully and completely absorbed into the potassium nitrate solution; oxygen is introduced together with the nitrogen dioxide gas during the entire process of introduction, and the oxygen can always absorb the residual nitrogen monoxide in the exhaust gas. Nitrogen is oxidized to more fully treat the waste gas. Simultaneously, oxygen replaces the waste gas to pressurize the reaction system, enabling online pressure compensation for the waste gas consumed in the reaction. This significantly improves waste gas absorption efficiency, achieving complete waste gas absorption and zero emissions. The present invention provides a third reactor to receive the potassium nitrate solution generated after the reaction, thereby further separating the potassium nitrate solution into potassium nitrate solid and water. A fourth storage tank is provided to store the separated potassium nitrate solid. The potassium nitrate solid serves as a compound fertilizer, effectively saving investment costs for subsequent treatment while further realizing resource-based waste gas treatment.

[0080] Preferably, a first delivery pump and a first back-pressure valve are provided in the pipeline between the first storage tank and the first reactor, with the first back-pressure valve being located closer to the first reactor than the first delivery pump. The first delivery pump can efficiently deliver deionized water from the first storage tank to the first reactor. The first back-pressure valve is interlocked with a density meter online and can intelligently switch on and off according to the specific concentration of the dilute phosphate solution, thereby accurately preparing the dilute phosphate solution of the desired concentration.

[0081] Preferably, the first reactor is connected to a density meter, which is interlocked with the first back pressure valve online. The density meter can monitor the concentration of the phosphoric acid solution in the first reactor in real time, so that the concentration of the final prepared dilute phosphoric acid solution is accurate.

[0082] Preferably, a second back-pressure valve is provided on the pipeline between the water inlet of the first temperature-control jacket and the cooling water source, and a first thermometer is connected to the first reactor, with the first thermometer and the second back-pressure valve being interlocked online. The first thermometer can monitor the reaction temperature in the first reactor in real time, and the opening of the second back-pressure valve can be adjusted in real time according to the specific temperature conditions. By controlling the flow rate of cooling water entering, the temperature in the first reactor is kept within an appropriate range.

[0083] Preferably, a second delivery pump and a third back-pressure valve are provided on the pipeline between the first reactor and the first absorption tower, wherein the third back-pressure valve is located closer to the first absorption tower than the second delivery pump. The second delivery pump can efficiently deliver the prepared dilute phosphoric acid solution to the first absorption tower, and the third back-pressure valve is correlated with the amount of nitrogen-containing waste gas entering the first absorption tower. The opening of the third back-pressure valve is adjusted in real time according to the amount of nitrogen-containing waste gas entering, so that the amount of dilute phosphoric acid solution entering can fully react and absorb the inorganic ammonia in the nitrogen-containing waste gas.

[0084] Preferably, a third delivery pump and a fourth back-pressure valve are provided in the pipeline between the nitrogen-containing waste gas source and the first gas distributor, with the fourth back-pressure valve being located closer to the first absorption tower than the third delivery pump. The third delivery pump can stably deliver the nitrogen-containing waste gas to the first gas distributor, and the fourth back-pressure valve is interlocked with the third back-pressure valve online to ensure that the amount of nitrogen-containing waste gas introduced is consistent with the amount of dilute phosphate solution, allowing the dilute phosphate solution to fully react and absorb the inorganic ammonia in the nitrogen-containing waste gas.

[0085] Preferably, the first absorption tower is connected to an ammonia detector. The ammonia detector can monitor the inorganic ammonia content in the first absorption tower in real time. The ammonia detector is online interlocked with the third back-pressure valve. When the ammonia detector indicates that the inorganic ammonia content is high, the opening of the fourth back-pressure valve is reduced and the opening of the third back-pressure valve is increased, allowing more dilute phosphoric acid solution to absorb the inorganic ammonia and control the inorganic ammonia content to be as close to zero as possible.

[0086] Preferably, a fifth back-pressure valve is provided on the pipeline between the water inlet of the second temperature-controlled jacket and the cooling water source, and a second thermometer is connected to the first absorption tower, and the second thermometer is online interlocked with the fourth back-pressure valve. The second thermometer can monitor the reaction temperature in the first absorption tower in real time, and the opening of the fifth back-pressure valve can be adjusted in real time according to the specific temperature conditions. By controlling the flow rate of cooling water entering, the temperature in the first absorption tower is controlled to be within an appropriate range.

[0087] Preferably, a fourth delivery pump and a sixth back-pressure valve are provided on the pipeline between the second reactor and the first absorption tower. The fourth delivery pump is closer to the first absorption tower than the sixth back-pressure valve. The sixth back-pressure valve, the fourth back-pressure valve, the ammonia gas detector, and the third back-pressure valve are interlocked online. The fourth delivery pump can effectively deliver the ammonium phosphate solution in the first absorption tower to the second reactor. The sixth back-pressure valve is interlocked online with the fourth back-pressure valve, the ammonia gas detector, and the third back-pressure valve. When the ammonium phosphate solution in the first absorption tower reaches a certain amount, it can be delivered to the second reactor in a timely manner.

[0088] Preferably, a fifth delivery pump and a seventh back-pressure valve are provided in the pipeline between the first storage tank and the drain outlet of the second reactor. The fifth delivery pump is located closer to the second reactor than the seventh back-pressure valve. The fifth delivery pump can steadily deliver water from the second reactor's vacuum distillation to the first storage tank, allowing the water to be recycled and reused. The seventh back-pressure valve can be flexibly opened and closed according to the amount of water in the second reactor, thereby ensuring stable operation of the entire vacuum distillation process in the second reactor.

[0089] Preferably, an eighth back-pressure valve and a sixth transfer pump are provided on the pipeline between the second storage tank and the solid product discharge port of the second reactor, with the eighth back-pressure valve being closer to the second reactor than the sixth transfer pump. The sixth transfer pump can efficiently deliver the solid ammonium phosphate product after vacuum distillation in the second reactor to the second storage tank, and the eighth back-pressure valve can be flexibly opened and closed according to the amount of solid ammonium phosphate product in the second reactor, thereby ensuring stable operation of the entire vacuum distillation process in the second reactor.

[0090] Preferably, a seventh delivery pump and a ninth back-pressure valve are provided in the pipeline between the fixed-bed reactor and the exhaust port of the first absorption tower. The ninth back-pressure valve is located closer to the fixed-bed reactor than the seventh delivery pump. The seventh delivery pump efficiently delivers the waste gas treated in the first absorption tower to the fixed-bed reactor for further reaction. The ninth back-pressure valve is interlocked with a reduced nitrogen detector online, and its opening is adjusted based on real-time data detected by the reduced nitrogen detector to ensure that the reduced nitrogen in the waste gas entering the fixed-bed reactor is completely oxidized.

[0091] Preferably, an eighth delivery pump and a tenth back-pressure valve are provided in the pipeline between the oxygen source and the air inlet of the fixed-bed reactor. The tenth back-pressure valve is located closer to the fixed-bed reactor than the eighth delivery pump. The eighth delivery pump can stably deliver oxygen to the fixed-bed reactor, thereby completely oxidizing the reduced nitrogen within the fixed-bed reactor. The tenth back-pressure valve is online-interlocked with the ninth back-pressure valve and the reduced nitrogen detector, allowing flexible adjustment based on the reaction conditions and air pressure within the fixed-bed reactor, ensuring that the reduced nitrogen in the exhaust gas from the fixed-bed reactor is completely oxidized under stable air pressure.

[0092] Preferably, an eleventh back-pressure valve is provided on the pipeline between the cooling water source and the third temperature-control jacket, and a third thermometer is connected to the fixed-bed reactor, wherein the third thermometer is online interlocked with the eleventh back-pressure valve. The third thermometer can monitor the reaction temperature within the fixed-bed reactor in real time, and the opening of the eleventh back-pressure valve can be adjusted in real time according to specific temperature conditions. By controlling the flow rate of cooling water entering the fixed-bed reactor, the temperature within the fixed-bed reactor is controlled to remain within an appropriate range.

[0093] Preferably, the fixed-bed reactor is connected to a reduced nitrogen detector, which can monitor the reduced nitrogen content in the fixed-bed reactor in real time to ensure that the reduced nitrogen in the fixed-bed reactor is completely oxidized to nitrogen dioxide.

[0094] Preferably, a twelfth backpressure valve and a ninth delivery pump are provided on the pipeline between the fixed-bed reactor exhaust port and the second gas distributor, with the ninth delivery pump being located closer to the fixed-bed reactor than the twelfth backpressure valve. The ninth delivery pump can steadily deliver nitrogen dioxide from the fixed-bed reactor to the second gas distributor. The twelfth backpressure valve is interlocked with a reduced nitrogen detector and a total nitrogen detector, respectively, online. Flexible adjustment of the opening ensures complete absorption of nitrogen dioxide entering the second gas distributor.

[0095] Preferably, a thirteenth back-pressure valve and a tenth delivery pump are provided on the pipeline between the oxygen source and the second gas distributor, with the thirteenth back-pressure valve being closer to the second gas distributor than the tenth delivery pump. The tenth delivery pump can stably deliver oxygen to the second gas distributor, thereby further thoroughly oxidizing the residual reduced nitrogen entering the second absorption tower. The thirteenth back-pressure valve is interlocked online with the twelfth back-pressure valve, the fourteenth back-pressure valve, and the total nitrogen detector, respectively, and flexibly adjusted according to the reaction conditions and air pressure in the second absorption tower, ensuring that the reduced nitrogen in the second absorption tower is thoroughly oxidized under stable air pressure, while the nitrogen dioxide is completely reacted and absorbed by the potassium hydroxide solution.

[0096] Preferably, an eleventh delivery pump and a fourteenth back-pressure valve are provided on the pipeline between the third storage tank and the second atomizer, with the fourteenth back-pressure valve being closer to the second absorption tower than the eleventh delivery pump. The eleventh delivery pump can stably deliver potassium hydroxide solution to the second atomizer, and the fourteenth back-pressure valve is online interlocked with the twelfth back-pressure valve and the total nitrogen detector, and the amount of potassium hydroxide solution added is controlled by adjusting the opening size to ensure that nitrogen dioxide in the second absorption tower is completely reacted and absorbed by the potassium hydroxide solution.

[0097] Preferably, a twelfth delivery pump and a sixteenth back-pressure valve are provided on the pipeline between the outside air and the exhaust port of the second absorption tower, wherein the twelfth delivery pump is closer to the second absorption tower than the sixteenth back-pressure valve. The twelfth delivery pump can stably discharge the treated gas that meets the standards into the outside air, and the sixteenth back-pressure valve is online interlocked with the total nitrogen detector. The gas in the second absorption tower can only be discharged when the total nitrogen content is lower than the set value.

[0098] Preferably, a fifteenth back-pressure valve is provided on the pipeline between the cooling water source and the fourth temperature-control jacket, and a fourth thermometer is connected to the second absorption tower. The fourth thermometer is interlocked with the fifteenth back-pressure valve. The fourth thermometer can monitor the reaction temperature in the second absorption tower in real time, and the opening of the fifteenth back-pressure valve is adjusted in real time according to the specific temperature conditions. By controlling the flow rate of cooling water entering the second absorption tower, the temperature in the second absorption tower is kept within an appropriate range.

[0099] Preferably, the second absorption tower is connected to a total nitrogen detector, and the total nitrogen detector, the thirteenth back pressure valve, the fourteenth back pressure valve, the sixteenth back pressure valve, the twelfth back pressure valve, the reduced nitrogen detector, the ninth back pressure valve, and the tenth back pressure valve are interlocked online. The total nitrogen detector can monitor the total nitrogen content in the second absorption tower in real time. Only when the total nitrogen content reaches a first set value is it allowed to be discharged to the air. Otherwise, treatment needs to continue until the discharge standard is met.

[0100] Preferably, a thirteenth delivery pump and a seventeenth back-pressure valve are provided on the pipeline between the third reactor and the discharge port of the second absorption tower, wherein the seventeenth back-pressure valve is closer to the second absorption tower than the thirteenth delivery pump. The third delivery pump can effectively deliver the potassium nitrate solution in the second absorption tower to the third reactor, and the seventeenth back-pressure valve is opened by adjusting the opening according to the amount of potassium nitrate solution in the second absorption tower. When the potassium nitrate solution in the second absorption tower reaches a certain amount, it can be promptly delivered to the third reactor.

[0101] Preferably, a fifteenth delivery pump and a nineteenth back-pressure valve are provided in the pipeline between the first storage tank and the drain outlet of the third reactor. The fifteenth delivery pump is closer to the third reactor than the nineteenth back-pressure valve. The fifteenth delivery pump can stably deliver water after vacuum distillation in the third reactor to the first storage tank, allowing the water to be recycled and reused. The nineteenth back-pressure valve can be flexibly opened and closed according to the amount of water in the third reactor, thereby ensuring stable operation of the entire vacuum distillation process in the third reactor.

[0102] Preferably, an eighteenth back-pressure valve and a fourteenth delivery pump are provided on the pipeline between the fourth storage tank and the liquid discharge port of the third reactor, with the eighteenth back-pressure valve being closer to the third reactor than the fourteenth delivery pump. The fourteenth delivery pump can effectively deliver the solid potassium nitrate product after vacuum distillation in the third reactor to the fourth storage tank, and the eighteenth back-pressure valve can be flexibly opened and closed according to the amount of the solid potassium nitrate product in the third reactor, thereby ensuring stable operation of the entire vacuum distillation process in the third reactor.

[0103] Preferably, the first absorption tower and the second absorption tower are both provided with trays, and both are three-stage absorption towers, wherein the diameter of the three-stage absorption tower is 1000 mm to 1200 mm, and the height of the three-stage absorption tower is 4000 mm to 4200 mm. The three-stage absorption tower has a better absorption effect and can ensure the completeness of the entire absorption process.

[0104] Preferably, the first gas distributor includes an air inlet pipe, one end of which passes through the first absorption tower and is connected to an air inlet cross pipe, and the outer peripheral surface of the air inlet cross pipe is symmetrically connected to two groups of air inlet branches, and the tops of the two groups of air inlet branches are connected to multiple air nozzles; the first gas distributor also includes a primary diversion component and a secondary diversion component, the primary diversion component is located on the upper side of the air nozzle, and the secondary diversion component is located on the upper side of the primary diversion component. The gas can be evenly sprayed into the first absorption tower through multiple air nozzles, so that the dilute phosphoric acid solution sprayed down by atomization can fully contact and react to the greatest extent, thereby improving the efficiency of the reaction; the primary diversion component and the secondary diversion component can better divert the gas, increase the area of ​​gas uniform distribution, and ensure the efficiency of the reaction.

[0105] Preferably, the primary flow splitter assembly includes multiple inverted conical first flow splitters, the number of which is equal to the number of air nozzles. The multiple first flow splitters are located directly above the multiple air nozzles, and adjacent first flow splitters are connected by first connecting rods. A first fixing ring is connected to the inner sidewall of the first absorption tower, and the first flow splitters adjacent to the first fixing ring are connected to the first fixing ring by a first connecting rod. This can further split the gas and maximize the efficiency of the reaction.

[0106] Preferably, the secondary diversion assembly includes a plurality of liquid storage boxes, the number of the plurality of liquid storage boxes is equal to the number of the plurality of first diverters, the plurality of liquid storage boxes are respectively located directly above the plurality of first diverters, a leakage hole is provided at the bottom of the liquid storage box, a plurality of second diverters are connected in a ring shape to the top of the liquid storage box via a support rod, two adjacent liquid storage boxes are connected via a second connecting rod, a second fixed ring is slidably connected to the inner wall of the first absorption tower, and the liquid storage box close to the second fixed ring is connected to the second fixed ring via a second connecting rod. When the atomizing nozzle is corroded and damaged, the atomization effect deteriorates. At this time, due to the smaller distribution area, the liquid storage box can receive more dilute phosphate solution in the same time. When the receiving speed is greater than the leakage speed of the leakage hole, the solution in the liquid storage box will increase, thereby generating a greater pulling force on the pull rod. When the pulling force applied to the tension sensor is greater than the set value, it indicates that the atomizing nozzle has been seriously damaged.

[0107] Preferably, the distance between the bottom ends of the plurality of second diverters on the liquid storage box and the axis of the liquid storage box is greater than the top surface radius of the first diverter located directly below the liquid storage box.

[0108] Preferably, the first atomizer includes a plurality of liquid supply pipes equidistantly arranged at the top of the first absorption tower, one end of the liquid supply pipe passes through the first absorption tower and is rotatably connected to a liquid supply transverse pipe, the liquid supply pipe is communicated with the liquid supply transverse pipe, two groups of liquid supply branches are symmetrically provided on the outer circumference of the liquid supply transverse pipe, the top and bottom of the two groups of liquid supply branches are connected to a plurality of atomizing nozzles, and the atomizing nozzles are provided with solenoid valves; it also includes a drive motor and a turntable, the turntable is located inside the first absorption tower and connected to the end of the liquid supply transverse pipe, the second drive motor is located outside the first absorption tower and connected to the turntable; it also includes an atomization state detection component. The dilute phosphoric acid solution can be evenly atomized and sprayed through multiple atomizing nozzles, ensuring that the dilute phosphoric acid solution can fully contact and react with the nitrogen-containing waste gas, thereby improving the sufficiency and speed of the reaction; the driving motor can drive the liquid delivery horizontal pipe to rotate 180 degrees, so that the new atomizing nozzle on the upper side replaces the damaged atomizing nozzle on the lower side to perform atomizing spraying work, thereby extending the replacement and maintenance cycle of the atomizing nozzle while ensuring the smooth progress of the reaction, effectively improving the practicality and reliability of the device.

[0109] Preferably, the atomization state detection component includes a plurality of sealed boxes connected in a ring shape to the inner wall of the first absorption tower, wherein a tension sensor is provided in the sealed box, and a straight rod is provided on the tension sensor, the bottom end of the straight rod passes through the bottom wall of the sealed box and is connected to a connecting plate, a pull rod is provided on the connecting plate, and the bottom end of the pull rod is connected to the second fixed ring, and the tension sensor is connected to the drive motor via a wired or wireless method. The tension sensor is connected to the second fixed ring through the pull rod, so that the weight of the entire secondary shunt assembly can be monitored. When the amount of dilute phosphate solution in the liquid storage box increases, the tension value applied to the tension sensor will increase, thereby being able to monitor the quality of the atomization effect of the atomizing nozzle and determine whether a new atomizing nozzle needs to be replaced to ensure the smooth progress of the reaction.

[0110] The present invention has the following beneficial effects:

[0111] (1) A concentrated phosphoric acid solution is first added to a first reaction kettle, and then the concentrated phosphoric acid solution is diluted by adding deionized water, and the amount of deionized water added is precisely controlled to prepare a dilute phosphoric acid solution of required concentration; the prepared dilute phosphoric acid solution is atomized and sprayed from the top of the first absorption tower into the first absorption tower through a first atomizer, and the nitrogen-containing waste gas to be treated is dispersed in the first absorption tower from the bottom of the first absorption tower through a first gas distributor, the nitrogen-containing waste gas slowly rises from bottom to top, and the atomized dilute phosphoric acid solution slowly falls from top to bottom, and the dilute phosphoric acid solution and the nitrogen-containing waste gas are in countercurrent contact and reaction. The dilute phosphoric acid solution absorbs the inorganic ammonia in the nitrogen-containing waste gas to generate an ammonium phosphate solution, which is then subjected to reduced-pressure distillation to obtain ammonium phosphate solid and water. The water is returned to the first storage tank for reuse. The ammonium phosphate solid serves as a compound fertilizer (nitrogen fertilizer + phosphorus fertilizer) and provides a certain economic source for agricultural production, which not only further protects the environment, but also improves resource utilization and saves resources. The reaction rate of the whole process is relatively fast, and the dilute phosphoric acid solution has a high absorption efficiency for the inorganic ammonia in the nitrogen-containing waste gas, which lays a good foundation for subsequent treatment processes and technologies and ensures that the inorganic ammonia in the nitrogen-containing waste gas is fully absorbed.

[0112] (2) By filling a fixed-bed reactor with a solid-phase catalyst and then introducing oxygen into the fixed-bed reactor, the nitrogen monoxide in the exhaust gas is catalytically oxidized to form nitrogen dioxide gas, which can be fully absorbed and treated by the subsequent alkaline solution. The addition of oxygen can also pressurize the entire reaction system and perform online pressure compensation for the gas consumed in the reaction, greatly improving the reaction efficiency of nitrogen monoxide;

[0113] (3) The prepared potassium hydroxide solution is sprayed from the top of the first absorption tower into the second absorption tower through the second atomizer, and the nitrogen dioxide gas to be treated is dispersed into the second absorption tower from the bottom of the second absorption tower through the second gas distributor. The nitrogen dioxide gas slowly rises from bottom to top, and the atomized potassium hydroxide solution slowly falls from top to bottom. The potassium hydroxide solution and the nitrogen dioxide gas react in countercurrent. The potassium hydroxide solution absorbs the nitrogen dioxide gas to generate potassium nitrate solution, and then the potassium nitrate solution is distilled under reduced pressure to obtain potassium nitrate solid and water, and the water is refluxed. The solid potassium nitrate is then recycled into the first storage tank for reuse, and used as a compound fertilizer (nitrogen fertilizer + potash fertilizer), effectively saving the investment cost of subsequent treatment while further realizing the resource-based treatment of waste gas. Oxygen is introduced throughout the entire nitrogen dioxide gas introduction process, and oxygen can always oxidize the residual nitric oxide in the waste gas, making the waste gas treatment more complete. At the same time, oxygen replaces the waste gas to pressurize the reaction system, and can perform online pressure compensation for the waste gas consumed in the reaction, greatly improving the waste gas absorption efficiency and achieving complete absorption of the waste gas and zero emission.

[0114] (4) Through the overall process of primary absorption, catalytic oxidation and secondary absorption, the nitrogen in the waste gas can be absorbed, thereby finally generating ammonium phosphate solid and potassium nitrate solid, wherein the ammonium phosphate solid and potassium nitrate solid can be used as agricultural fertilizers. In this way, the treatment of nitrogen-containing waste gas will not only avoid the occurrence of harmful secondary products, but also obtain the waste and water required for agriculture, thereby achieving safe, environmentally friendly, green and economical treatment of nitrogen-containing waste gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0115] Figure 1 It is a schematic diagram of the process module of the present invention;

[0116] Figure 2 It is a structural schematic diagram of the first absorption tower in the present invention;

[0117] Figure 3 yes Figure 2 A magnified schematic diagram of point A in the middle;

[0118] Figure 4 yes Figure 2 A magnified schematic diagram of point B in the middle;

[0119] Figure 5 It is a structural diagram of the liquid delivery horizontal pipe in the present invention;

[0120] Figure 6 It is a structural diagram of the second diverter in the present invention;

[0121] Figure 7 It is a structural schematic diagram of the first diverter in the present invention;

[0122] Figure 8 It is a structural diagram of the air intake cross pipe in the present invention.

[0123] The marks in the accompanying drawings are: 100-first absorption tower, 101-first atomizer, 1011-liquid feeding pipe, 1012-liquid feeding transverse pipe, 1013-liquid feeding branch pipe, 1014-atomizing nozzle, 1015-driving motor, 1016-turntable, 1017-atomization state detection assembly, 10171-sealing box, 10172-tension sensor, 10173-straight rod, 10174-connecting plate, 10175-pull rod, 102-first body distributor, 1021-inlet pipe, 1022-inlet transverse pipe, 1023-inlet branch pipe, 1024-jet nozzle, 1025-first level diversion assembly, 10251-first diverter, 10252-first Connecting rod, 10253-first fixed ring, 1026-secondary diversion assembly, 10261-liquid storage box, 10262-leakage hole, 10263-support rod, 10264-second diverter, 10265-second connecting rod, 10266-second fixed ring, 103-second temperature control jacket, 104-third delivery pump, 105-fourth back pressure valve, 106-ammonia detector, 107-fifth back pressure valve, 108-second thermometer, 109-fourth delivery pump, 110-sixth back pressure valve, 111-seventh delivery pump, 112-ninth back pressure valve, 200-first storage tank, 300-first reactor, 301-first temperature control jacket, 302-first Delivery pump, 303-first back pressure valve, 304-density meter, 305-second back pressure valve, 306-first thermometer, 307-second delivery pump, 308-third back pressure valve, 400-second reactor, 401-fifth delivery pump, 402-seventh back pressure valve, 403-eighth back pressure valve, 404-sixth delivery pump, 500-second storage tank, 600-fixed bed reactor, 601-solid phase catalyst, 602-third temperature control jacket, 603-eighth delivery pump, 604-tenth back pressure valve, 605-eleventh back pressure valve, 606-third thermometer, 607-reduced nitrogen detector, 700-second absorption tower, 701-second gas distributor, 70 2-second atomizer, 703-fourth temperature control jacket, 704-twelfth back pressure valve, 705-ninth delivery pump, 706-thirteenth back pressure valve, 707-tenth delivery pump, 708-eleventh delivery pump, 709-fourteenth back pressure valve, 710-twelfth delivery pump, 711-sixteenth back pressure valve, 712-fifteenth back pressure valve, 713-fourth thermometer, 714-total nitrogen detector, 715-thirteenth delivery pump, 716-seventeenth back pressure valve, 800-third storage tank, 900-third reactor, 901-fifteenth delivery pump, 902-nineteenth back pressure valve, 903-eighteenth back pressure valve, 904-fourteenth delivery pump, 1000-fourth storage tank. DETAILED DESCRIPTION

[0124] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0125] A method for recycling nitrogen-containing waste gas comprises the following steps:

[0126] (a) preparing a dilute phosphoric acid solution;

[0127] The preparation of the dilute phosphoric acid solution comprises the following steps:

[0128] (a1) adding an appropriate amount of concentrated phosphoric acid solution to the first reaction kettle; the mass concentration of the concentrated phosphoric acid solution in step (a1) is 50% to 70%; the concentration of the concentrated phosphoric acid solution is adjusted according to the concentration of the dilute phosphoric acid solution;

[0129] (a2) adding an appropriate amount of deionized water into the first storage tank;

[0130] (a3) starting the agitator in the first reaction kettle, adding the deionized water obtained in step (a2) to the first reaction kettle to dilute the concentrated phosphoric acid solution to obtain a dilute phosphoric acid solution; the temperature of the dilute phosphoric acid solution in step (a3) ​​is 20° C. to 40° C.; and the mass concentration of the dilute phosphoric acid solution in step (a3) ​​is 30% to 35%;

[0131] (b) primary absorption;

[0132] (b1) inputting the dilute phosphoric acid solution in step (a3) ​​into the first atomizer at the top of the first absorption tower, and spraying the dilute phosphoric acid solution downward from the first atomizer into atomization; the flow rate of the dilute phosphoric acid solution in step (b1) is 60 mL / min to 80 mL / min;

[0133] (b2) transporting the nitrogen-containing waste gas to a first gas distributor at the bottom of the first absorption tower, and dispersing the nitrogen-containing waste gas in the first absorption tower by the first gas distributor; the flow rate of the nitrogen-containing waste gas in step (b2) is 15 mL / min to 25 mL / min;

[0134] (b3) contacting the atomized dilute phosphoric acid solution in step (b1) with the nitrogen-containing waste gas dispersed in step (b2) in a countercurrent manner to generate a first mixed solution containing a certain concentration of ammonium phosphate; the reaction time in step (b3) is 30 minutes to 90 minutes; the reaction temperature in step (b3) is 30° C. to 40° C.; and the reaction pressure in step (b3) is 1 MPa to 4 MPa; so that the nitrogen in the waste gas can more fully contact with the dilute phosphoric acid solution, thereby improving the absorption efficiency of the nitrogen in the waste gas while ensuring the absorption effect;

[0135] (b4) feeding the first mixed solution in step (b3) into a second reactor and performing vacuum distillation to obtain ammonium phosphate solid and water;

[0136] (b5) Recycle the water in step (b4) back to the first storage tank for reuse;

[0137] (b6) Transport the ammonium phosphate solid in step (b4) to the second storage tank;

[0138] (c) Catalytic oxidation;

[0139] (c1) Fill the solid-phase catalyst into the fixed-bed reactor; the solid-phase catalyst in step (c1) is a transition metal compound; the transition metal compound is at least one of Ce2O3, CeO2, Ce2(CO3)3, xCe2O3·(1 - x)CuO, Ce-Cu, Ce-Fe, Ce-Mn, Ce-Cr, MnO2, MnO, xMn2O3·(1 - x)CuO, xMnO·(1 - x)CuO, Mn(OH)2, MnCO3, xFe2O3·(1 - x)MnO2, xFe2O3·(1 - x)CuO, Fe(OH)3, Fe2O3, Fe3O4, CuO, Cu(OH)2, CuMn2O4, Cr2O3, Cr(OH)3, xCr2O3·(1 - x)CuO, xCr2O3·(1 - x)MnO2 or CuCr2O4, where 0 < x < 1; the particle size of the solid-phase catalyst in step (c1) is 0.25 mm to 10 mm; the void fraction of the fixed-bed reactor after filling the solid-phase catalyst in step (c1) is 30% to 50%. Under the action of the solid-phase catalyst, the organic nitrogen-containing waste gas and oxygen are catalytically oxidized, achieving the purpose of oxidizing the organic nitrogen-containing compound into nitrogen oxides. The operation is simple and easy to control. While improving the oxidation treatment efficiency, it also reduces the treatment cost and energy consumption; a solid-phase catalyst carrier is provided in the fixed-bed reactor, and the solid-phase catalyst carrier is selected from at least one of activated carbon, molecular sieve or montmorillonite; it has a good catalytic effect on the rapid degradation of organic nitrogen-containing waste gas by oxygen;

[0140] (c2) Transport the waste gas treated in step (b3) to the fixed-bed reactor in step (c1); the flow rate of the waste gas in step (c2) is 20 mL / min to 40 mL / min;

[0141] (c3) Introduce oxygen into the fixed-bed reactor in step (c1) to carry out a catalytic oxidation reaction with the waste gas in step (c2) in the fixed-bed reactor; the flow rate of oxygen in step (c3) is 30 mL / min to 60 mL / min; the reaction temperature in step (c3) is 210°C to 280°C; the reaction pressure in step (c3) is 5 MPa to 8 MPa; the reaction time in step (c3) is 20 min to 60 min;

[0142] (d) Secondary absorption;

[0143] (d1) transporting the remaining waste gas and oxygen after mixing in step (c3) to the second gas distributor at the bottom of the second absorption tower; the oxygen flow rate in step (d1) is 40 mL / min to 50 mL / min; the waste gas flow rate in step (d1) is 30 mL / min to 60 mL / min;

[0144] (d2) adding an appropriate amount of potassium hydroxide solution to a third storage tank, and inputting the potassium hydroxide solution in the third storage tank into the second atomizer at the top of the second absorption tower, the potassium hydroxide solution is sprayed downward from the second atomizer and atomized, and reacts with the mixed gas in countercurrent contact in step (d1) to generate a second mixed solution containing a certain concentration of potassium nitrate; the mass concentration of the potassium hydroxide solution in step (d2) is 13% to 18%; the flow rate of the potassium hydroxide solution in step (d2) is 60 mL / min to 160 mL / min; the reaction temperature in step (d2) is 20° C. to 35° C.; the reaction pressure in step (d2) is 2.5 MPa to 5 MPa; the reaction time in step (d2) is 30 min to 45 min;

[0145] (d3) feeding the second mixed solution into a third reactor and performing vacuum distillation to obtain potassium nitrate solid and water;

[0146] (d4) returning the water in step (d3) to the first storage tank for reuse;

[0147] (d5) transporting the potassium nitrate solid in step (d3) to a fourth storage tank;

[0148] (e) Online monitoring;

[0149] (e1) adjusting the flow rate of deionized water in the first reactor online using a density meter to control the concentration of the dilute phosphoric acid solution;

[0150] (e2) adjusting the cooling water flow rate in the first temperature-controlled jacket outside the first reactor online by using a first thermometer to control the temperature in the first reactor to reach a certain set value;

[0151] (e3) adjusting the cooling water flow rate in the second temperature-controlled jacket outside the first absorption tower online by a second thermometer to control the temperature in the first absorption tower to reach a certain set value;

[0152] (e4) adjusting the cooling water flow rate in the fourth temperature-control jacket outside the second absorption tower online by a fourth thermometer to control the temperature in the second absorption tower to reach a certain set value;

[0153] (e5) online adjusting the cooling water flow rate in the third temperature control jacket outside the fixed bed reactor by a third thermometer to control the temperature in the fixed bed reactor to reach a certain set value;

[0154] (e6) connecting an ammonia gas detector to the first absorption tower in step (b), interlocking the ammonia gas detector with a third back-pressure valve for the dilute phosphate solution online, and adjusting the opening of the third back-pressure valve online to adjust the flow rate of the dilute phosphate solution;

[0155] (e7) A reduced nitrogen detector is connected to the fixed bed reactor in step (c), and the reduced nitrogen detector is interlocked with the tenth oxygen back pressure valve online, and the oxygen flow rate is adjusted by adjusting the opening of the tenth back pressure valve online;

[0156] (e8) A total nitrogen detector is connected to the second absorption tower in step (d), and the total nitrogen detector is online interlocked with the fourteenth back pressure valve of the potassium hydroxide solution and the thirteenth back pressure valve of the oxygen. The flow rate of the potassium hydroxide solution and the flow rate of the oxygen are adjusted by online adjusting the opening size of the fourteenth back pressure valve and the thirteenth back pressure valve;

[0157] (f) discharge of waste gas;

[0158] By observing the reading of the total nitrogen detector in step (e8), determine whether the total nitrogen content in the exhaust gas meets the standard;

[0159] If the total nitrogen content in the exhaust gas is lower than the emission standard, the exhaust gas will be discharged into the atmosphere through the pipeline;

[0160] If the total nitrogen content in the waste gas is higher than the emission standard, the waste gas will continue to remain in the second absorption tower, the sixteenth back pressure valve for exhaust will be closed through the online total nitrogen detector, the opening of the fourteenth back pressure valve for potassium hydroxide solution and the thirteenth back pressure valve for oxygen will be increased, and the treatment will continue until the waste gas meets the standard and is discharged into the atmosphere; the emission standard in step (f) is that the mass concentration of total nitrogen in the waste gas does not exceed 5×10 -4 mg / L.

[0161] like Figure 1 The illustrated apparatus for recycling nitrogen-containing waste gas comprises a first storage tank 200, the drain outlet of the first storage tank being connected to a first reactor 300 via a pipeline. A first temperature-control jacket 301 is sheathed on the outer circumference of the first reactor, and the water inlet of the first temperature-control jacket is connected to a cooling water source.

[0162] The discharge port of the first reactor is connected to the Figure 2 The first absorption tower 100 shown in the figure has a first atomizer 101 provided at the top thereof, which is connected to the liquid discharge port of the first reactor via a pipeline; a first gas distributor 102 provided at the bottom thereof, which is connected to the nitrogen-containing waste gas source via a pipeline; a second temperature-control jacket 103 is provided on the outer circumference of the first absorption tower, and the water inlet of the second temperature-control jacket is connected to the cooling water source;

[0163] The liquid outlet of the first absorption tower is connected to the second reactor 400 via a pipeline, the water outlet of the second reactor is connected to the first storage tank via a pipeline, and the solid product outlet of the second reactor is connected to the second storage tank 500 via a pipeline;

[0164] The exhaust port of the first absorption tower is connected to a fixed bed reactor 600 via a pipeline, the air inlet of the fixed bed reactor is connected to an oxygen source via a pipeline, and the interior of the fixed bed reactor is filled with a solid-phase catalyst 601; a third temperature-control jacket 602 is sheathed on the outer circumference of the fixed bed reactor, and the water inlet of the third temperature-control jacket is connected to a cooling water source via a pipeline;

[0165] The system further includes a second absorption tower 700, wherein a second gas distributor 701 is provided at the bottom of the second absorption tower, the second gas distributor is connected to the exhaust port of the fixed bed reactor via a pipeline, and the second gas distributor is connected to the oxygen source via a pipeline; a second atomizer 702 is provided at the top of the second absorption tower, and the second atomizer is connected to a third storage tank 800 via a pipeline. The third storage tank is located outside the second absorption tower and is filled with potassium hydroxide solution; the exhaust port of the second absorption tower is connected to the outside air via a pipeline; a fourth temperature control jacket 703 is provided on the outer circumference of the second absorption tower, and the water inlet of the fourth temperature control jacket is connected to the cooling water source;

[0166] The drain port of the second absorption tower is connected to the third reactor 900 through a pipeline, the drain port of the third reactor is connected to the first storage tank through a pipeline, and the drain port of the third reactor is connected to the fourth storage tank 1000 through a pipeline.

[0167] A first delivery pump 302 and a first back-pressure valve 303 are provided on the pipeline between the first storage tank and the first reactor. The first back-pressure valve is closer to the first reactor than the first delivery pump. A density meter 304 is connected to the first reactor, and the density meter is interlocked with the first back-pressure valve online. A second back-pressure valve 305 is provided on the pipeline between the water inlet of the first temperature-controlled jacket and the cooling water source. A first thermometer 306 is connected to the first reactor, and the first thermometer is interlocked with the second back-pressure valve online. A second delivery pump 307 and a third back-pressure valve 308 are provided on the pipeline between the first reactor and the first absorption tower. The third back-pressure valve is closer to the first absorption tower than the second delivery pump. A third delivery pump 104 is provided on the pipeline between the nitrogen-containing waste gas source and the first gas distributor. and a fourth back-pressure valve 105, which is closer to the first absorption tower than the third delivery pump; an ammonia detector 106 is connected to the first absorption tower; a fifth back-pressure valve 107 is provided on the pipeline between the water inlet of the second temperature-controlled jacket and the cooling water source, a second thermometer 108 is connected to the first absorption tower, and the second thermometer is interlocked online with the fourth back-pressure valve; a fourth delivery pump 109 and a sixth back-pressure valve 110 are provided on the pipeline between the second reactor and the first absorption tower, and the fourth delivery pump is closer to the first absorption tower than the sixth back-pressure valve, and the sixth back-pressure valve, the fourth back-pressure valve, the ammonia detector and the third back-pressure valve are interlocked online; a fifth delivery pump 401 and a seventh back-pressure valve 402 are provided on the pipeline between the first storage tank and the drain outlet of the second reactor, The fifth delivery pump is closer to the second reactor than the seventh back pressure valve; an eighth back pressure valve 403 and a sixth delivery pump 404 are provided on the pipeline between the second storage tank and the solid product discharge port of the second reactor, and the eighth back pressure valve is closer to the second reactor than the sixth delivery pump; a seventh delivery pump 111 and a ninth back pressure valve 112 are provided on the pipeline between the fixed bed reactor and the exhaust port of the first absorption tower, and the ninth back pressure valve is closer to the fixed bed reactor than the seventh delivery pump; an eighth delivery pump 603 and a tenth back pressure valve 604 are provided on the pipeline between the oxygen source and the air inlet of the fixed bed reactor, and the tenth back pressure valve is closer to the fixed bed reactor than the eighth delivery pump; an eleventh back pressure valve 605 is provided on the pipeline between the cooling water source and the third temperature control jacket, The reactor is connected to a third thermometer 606, which is interlocked online with the eleventh back-pressure valve; the fixed-bed reactor is connected to a reduced nitrogen detector 607; a twelfth back-pressure valve 704 and a ninth delivery pump 705 are provided on the pipeline between the exhaust port of the fixed-bed reactor and the second gas distributor, and the ninth delivery pump is closer to the fixed-bed reactor than the twelfth back-pressure valve; a thirteenth back-pressure valve 706 and a tenth delivery pump 707 are provided on the pipeline between the oxygen source and the second gas distributor, and the thirteenth back-pressure valve is closer to the second gas distributor than the tenth delivery pump; an eleventh delivery pump 708 and a fourteenth back-pressure valve 709 are provided on the pipeline between the third storage tank and the second atomizer, and the fourteenth back-pressure valve is closer to the second absorption tower than the eleventh delivery pump;A twelfth delivery pump 710 and a sixteenth back pressure valve 711 are provided on the pipeline between the outside air and the exhaust port of the second absorption tower. The twelfth delivery pump is closer to the second absorption tower than the sixteenth back pressure valve; a fifteenth back pressure valve 712 is provided on the pipeline between the cooling water source and the fourth temperature control jacket, and a fourth thermometer 713 is connected to the second absorption tower, and the fourth thermometer is interlocked with the fifteenth back pressure valve online; a total nitrogen detector 714 is connected to the second absorption tower, and the total nitrogen detector, the thirteenth back pressure valve, the fourteenth back pressure valve, the sixteenth back pressure valve, the twelfth back pressure valve, the reduced nitrogen detector, the ninth back pressure valve and the tenth back pressure valve are connected to the second absorption tower. The valves are interlocked online. A thirteenth delivery pump 715 and a seventeenth back-pressure valve 716 are installed in the pipeline between the third reactor and the second absorber outlet. The seventeenth back-pressure valve is closer to the second absorber than the thirteenth delivery pump. A fifteenth delivery pump 901 and a nineteenth back-pressure valve 902 are installed in the pipeline between the first storage tank and the third reactor outlet. The fifteenth delivery pump is closer to the third reactor than the nineteenth back-pressure valve. An eighteenth back-pressure valve 903 and a fourteenth delivery pump 904 are installed in the pipeline between the fourth storage tank and the third reactor outlet. The eighteenth back-pressure valve is closer to the third reactor than the fourteenth delivery pump.

[0168] The first gas distributor includes an air inlet pipe 1021, one end of which passes through the first absorption tower and is connected to an air inlet cross pipe 1022. Two groups of air inlet branches 1023 are symmetrically connected on the outer circumference of the air inlet cross pipe. The tops of the two groups of air inlet branches are connected to multiple Figure 8 The first gas distributor also includes the following: Figure 4 The primary flow diversion assembly 1025 and the secondary flow diversion assembly 1026 are shown, the primary flow diversion assembly is located on the upper side of the air nozzle, and the secondary flow diversion assembly is located on the upper side of the primary flow diversion assembly; the primary flow diversion assembly includes a plurality of inverted cone-shaped Figure 7 The first diverter 10251 shown in the figure has the same number as the number of the air nozzles, and the multiple first diverters are respectively located directly above the multiple air nozzles, and the adjacent first diverters are connected by a first connecting rod 10252; a first fixed ring 10253 is connected to the inner wall of the first absorption tower, and the first diverter close to the first fixed ring is connected to the first fixed ring through the first connecting rod; the secondary diversion assembly includes a plurality of liquid storage boxes 10261, and the number of the multiple liquid storage boxes is equal to the number of the multiple first diverters. The multiple liquid storage boxes are respectively located directly above the multiple first diverters, and a leakage hole 10262 is provided at the bottom of the liquid storage box. The top of the liquid storage box is connected to a plurality of liquid storage boxes in a ring shape through a support rod 10263. Figure 6The second flow divider 10264 shown has two adjacent liquid storage boxes connected by a second connecting rod 10265. A second fixing ring 10266 is slidably connected to the inner wall of the first absorption tower. The liquid storage box closest to the second fixing ring is connected to the second fixing ring via the second connecting rod. The distance between the bottom end of the multiple second flow dividers on the liquid storage box and the liquid storage box axis is greater than the radius of the top surface of the first flow divider located directly below the liquid storage box. The second gas distributor has the same structure as the first gas distributor.

[0169] The first atomizer 101 includes a plurality of liquid feeding pipes 1011 equidistantly arranged at the top of the first absorption tower. One end of the liquid feeding pipe passes through the first absorption tower and is rotatably connected to the first absorption tower. Figure 5 The liquid feeding transverse pipe 1012 shown is connected to the liquid feeding transverse pipe, and two groups of liquid feeding branches 1013 are symmetrically provided on the outer circumference of the liquid feeding transverse pipe. The top and bottom of the two groups of liquid feeding branches are connected to multiple atomizing nozzles 1014, and the atomizing nozzles are provided with solenoid valves; it also includes a drive motor 1015 and a turntable 1016, the turntable is located inside the first absorption tower and connected to the end of the liquid feeding transverse pipe, and the second drive motor is located outside the first absorption tower and connected to the turntable; it also includes Figure 3 The atomization state detection assembly 1017 shown includes a plurality of sealed boxes 10171 connected in a ring shape to the inner wall of the first absorption tower. A tension sensor 10172 is installed in each sealed box. The tension sensor is provided with a straight rod 10173. The bottom end of the straight rod passes through the bottom wall of the sealed box and is connected to a connecting plate 10174. A pull rod 10175 is provided on the connecting plate. The bottom end of the pull rod is connected to the second fixing ring. The tension sensor is connected to the drive motor via a wired or wireless connection. The second atomizer has the same structure as the first atomizer.

[0170] The working principle of the present invention is:

[0171] After power is turned on, the gas is sprayed upward into the first absorption tower 100 and the second absorption tower 700 through the air intake pipe 1021, the air intake cross pipe 1022, the air intake branch pipe 1023 and the air nozzle 1024. The gas is then sprayed from the air nozzle to the first diverter 10251 directly above it and is initially dispersed. The initially dispersed gas then continues to flow upward and collides with multiple second diverters 10264 and is dispersed here. At this time, the gas is fully and evenly distributed inside the first absorption tower and the second absorption tower.

[0172] At the same time, the solution is atomized and sprayed into the first absorption tower and the second absorption tower through the liquid delivery pipe 1011, the liquid delivery horizontal pipe 1012, the liquid delivery branch pipe 1013 and the atomizing nozzle 1014 until it reacts with the thoroughly dispersed and evenly distributed gas to generate a mixed liquid.

[0173] As the working time of the atomizing nozzle 1014 increases, it will be corroded by the solution and damaged. At this time, the atomizing effect of the atomizing nozzle becomes worse, making it difficult for the corresponding dilute phosphoric acid solution and sodium hydroxide solution to be evenly atomized and distributed inside the first absorption tower 100 and the second absorption tower 700. In this way, the solution sprayed downward is more concentrated, resulting in an increase in the solution falling into the liquid storage box 10261 in the same time. When the speed of the solution entering the liquid storage box is greater than the speed of the solution discharged from the leakage hole 10262, the solution in the liquid storage box will continue to increase, thereby causing the pull rod 1017 to 5 and the tension sensor 10172 are subjected to an increase. When the tension reaches a set value, the drive motor 1015 is started to drive the liquid delivery transverse pipe 1012 to rotate 180 degrees through the turntable 1016 and the liquid delivery pipe 1011, so that the new atomizing nozzle originally located on the upper side is put into operation, and the damaged atomizing nozzle is rotated to the upper side and the solenoid valve thereon is closed to stop working. In this way, the replacement and maintenance cycle of the atomizing nozzle can be extended without affecting the atomizing spraying effect, thereby effectively improving the practicality and reliability of the first atomizer and the second atomizer.

[0174] Example 1:

[0175] A method for recycling nitrogen-containing waste gas comprises the following steps:

[0176] (a) preparing a dilute phosphoric acid solution;

[0177] The preparation of the dilute phosphoric acid solution comprises the following steps:

[0178] (a1) adding an appropriate amount of 50% phosphoric acid concentrated solution into the first reaction kettle;

[0179] (a2) adding an appropriate amount of deionized water into the first storage tank;

[0180] (a3) starting the agitator in the first reactor, adding the deionized water prepared in step (a2) to the first reactor, and diluting the concentrated phosphoric acid solution at 20° C. to obtain a dilute phosphoric acid solution having a mass concentration of 30%;

[0181] (b) primary absorption;

[0182] (b1) the dilute phosphoric acid solution in step (a3) ​​is input into the first atomizer at the top of the first absorption tower at a flow rate of 60 mL / min, and the dilute phosphoric acid solution is sprayed downward from the first atomizer into atomization;

[0183] (b2) delivering the nitrogen-containing waste gas to a first gas distributor at the bottom of the first absorption tower at a flow rate of 15 mL / min, and the nitrogen-containing waste gas is dispersed in the first absorption tower by the first gas distributor;

[0184] (b3) The atomized dilute phosphoric acid solution in step (b1) and the dispersed nitrogen-containing waste gas in step (b2) are in countercurrent contact reaction at a temperature of 30°C and a pressure of 1 MPa for 30 minutes to generate a first mixed solution containing a certain concentration of ammonium phosphate salt;

[0185] (b4) The first mixed solution in step (b3) is fed into a second reaction kettle, and after vacuum distillation, ammonium phosphate salt solid and water are obtained;

[0186] (b5) The water in step (b4) is refluxed to the first storage tank for reuse;

[0187] (b6) The ammonium phosphate salt solid in step (b4) is transported to a second storage tank;

[0188] (c) Catalytic oxidation;

[0189] (c1) The solid-phase catalyst is filled into a fixed-bed reactor; the solid-phase catalyst in step (c1) is a transition metal compound; the transition metal compound is at least one of Ce2O3, CeO2, Ce2(CO3)3, xCe2O3·(1 - x)CuO, Ce-Cu, Ce-Fe, Ce-Mn, Ce-Cr, MnO2, MnO, xMn2O3·(1 - x)CuO, xMnO·(1 - x)CuO, Mn3O4, Mn(OH)2, MnCO3, xFe2O3·(1 - x)MnO2, xFe2O3·(1 - x)CuO, Fe(OH)3, Fe2O3, Fe3O4, CuO, Cu(OH)2, CuMn2O4, Cr2O3, Cr(OH)3, xCr2O3·(1 - x)CuO, xCr2O3·(1 - x)MnO2 or CuCr2O4, where 0 < x < 1; the particle size of the solid-phase catalyst in step (c1) is 0.25 mm; the porosity of the fixed-bed reactor after filling the solid-phase catalyst in step (c1) is 30%. Under the action of the solid-phase catalyst, the organic nitrogen-containing waste gas and oxygen are catalytically oxidized, achieving the purpose of oxidizing organic nitrogen compounds into nitrogen oxides. The operation is simple and easy to control. While improving the oxidation treatment efficiency, it also reduces the treatment cost and energy consumption; a solid-phase catalyst carrier is provided in the fixed-bed reactor, and the solid-phase catalyst carrier is selected from at least one of activated carbon, molecular sieve or montmorillonite; it has a good catalytic effect on the rapid degradation of organic nitrogen-containing waste gas by oxygen;

[0190] (c2) The waste gas treated in step (b3) is transported to the fixed-bed reactor in step (c1) at a flow rate of 20 mL / min;

[0191] (c3) introducing oxygen into the fixed bed reactor in step (c1) at a flow rate of 30 mL / min, and carrying out a catalytic oxidation reaction with the exhaust gas in step (c2) in the fixed bed reactor at a temperature of 210° C. and a pressure of 5 MPa for 20 min;

[0192] (d) secondary absorption;

[0193] (d1) delivering the remaining waste gas after mixing in step (c3) at a flow rate of 30 mL / min and oxygen at a flow rate of 40 mL / min to a second gas distributor at the bottom of the second absorption tower;

[0194] (d2) adding an appropriate amount of a potassium hydroxide solution having a mass concentration of 13% to a third storage tank, and inputting the potassium hydroxide solution in the third storage tank into a second atomizer at the top of the second absorption tower at a flow rate of 60 mL / min, spraying the potassium hydroxide solution downward from the second atomizer and atomizing the potassium hydroxide solution, and reacting with the mixed gas in step (d1) at a temperature of 20° C. and a pressure of 2.5 MPa in countercurrent contact for 30 min to generate a second mixed solution containing a certain concentration of potassium nitrate;

[0195] (d3) feeding the second mixed solution into a third reactor and performing vacuum distillation to obtain potassium nitrate solid and water;

[0196] (d4) returning the water in step (d3) to the first storage tank for reuse;

[0197] (d5) transporting the potassium nitrate solid in step (d3) to a fourth storage tank;

[0198] (e) Online monitoring;

[0199] (e1) adjusting the flow rate of deionized water in the first reactor online using a density meter to control the concentration of the dilute phosphoric acid solution;

[0200] (e2) adjusting the cooling water flow rate in the first temperature-controlled jacket outside the first reactor online by using a first thermometer to control the temperature in the first reactor to reach a certain set value;

[0201] (e3) adjusting the cooling water flow rate in the second temperature-controlled jacket outside the first absorption tower online by a second thermometer to control the temperature in the first absorption tower to reach a certain set value;

[0202] (e4) adjusting the cooling water flow rate in the fourth temperature-control jacket outside the second absorption tower online by a fourth thermometer to control the temperature in the second absorption tower to reach a certain set value;

[0203] (e5) online adjusting the cooling water flow rate in the third temperature control jacket outside the fixed bed reactor by a third thermometer to control the temperature in the fixed bed reactor to reach a certain set value;

[0204] (e6) connecting an ammonia gas detector to the first absorption tower in step (b), interlocking the ammonia gas detector with a third back-pressure valve for the dilute phosphate solution online, and adjusting the opening of the third back-pressure valve online to adjust the flow rate of the dilute phosphate solution;

[0205] (e7) A reduced nitrogen detector is connected to the fixed bed reactor in step (c), and the reduced nitrogen detector is interlocked with the tenth oxygen back pressure valve online, and the oxygen flow rate is adjusted by adjusting the opening of the tenth back pressure valve online;

[0206] (e8) A total nitrogen detector is connected to the second absorption tower in step (d), and the total nitrogen detector is online interlocked with the fourteenth back pressure valve of the potassium hydroxide solution and the thirteenth back pressure valve of the oxygen. The flow rate of the potassium hydroxide solution and the flow rate of the oxygen are adjusted by online adjusting the opening size of the fourteenth back pressure valve and the thirteenth back pressure valve;

[0207] (f) discharge of waste gas;

[0208] By observing the reading of the total nitrogen detector in step (e8), determine whether the total nitrogen content in the exhaust gas meets the standard;

[0209] If the total nitrogen content in the exhaust gas is lower than the emission standard, the exhaust gas will be discharged into the atmosphere through the pipeline;

[0210] If the total nitrogen content in the waste gas is higher than the emission standard, the waste gas will continue to remain in the second absorption tower, the sixteenth back pressure valve for exhaust will be closed through the online total nitrogen detector, the opening of the fourteenth back pressure valve for potassium hydroxide solution and the thirteenth back pressure valve for oxygen will be increased, and the treatment will continue until the waste gas meets the standard and is discharged into the atmosphere; the emission standard in step (f) is that the mass concentration of total nitrogen in the waste gas does not exceed 5×10 -4 mg / L.

[0211] Example 2:

[0212] A method for recycling nitrogen-containing waste gas comprises the following steps:

[0213] (a) preparing a dilute phosphoric acid solution;

[0214] The preparation of the dilute phosphoric acid solution comprises the following steps:

[0215] (a1) adding an appropriate amount of 70% phosphoric acid concentrated solution into the first reaction kettle;

[0216] (a2) adding an appropriate amount of deionized water into the first storage tank;

[0217] (a3) starting the agitator in the first reaction kettle, adding the deionized water obtained in step (a2) to the first reaction kettle, and diluting the concentrated phosphoric acid solution at a temperature of 40° C. to obtain a dilute phosphoric acid solution having a mass concentration of 35%;

[0218] (b) primary absorption;

[0219] (b1) the dilute phosphoric acid solution in step (a3) ​​is input into the first atomizer at the top of the first absorption tower at a flow rate of 80 mL / min, and the dilute phosphoric acid solution is sprayed downward from the first atomizer into atomization;

[0220] (b2) delivering the nitrogen-containing waste gas to a first gas distributor at the bottom of the first absorption tower at a flow rate of 25 mL / min, and the nitrogen-containing waste gas is dispersed in the first absorption tower by the first gas distributor;

[0221] (b3) subjecting the atomized dilute phosphoric acid solution of step (b1) to countercurrent contact reaction with the nitrogen-containing waste gas dispersed in step (b2) at a temperature of 40° C. and a pressure of 4 MPa for 90 minutes to generate a first mixed solution containing a certain concentration of ammonium phosphate;

[0222] (b4) feeding the first mixed solution in step (b3) into a second reactor and performing vacuum distillation to obtain ammonium phosphate solid and water;

[0223] (b5) returning the water in step (b4) to the first storage tank for reuse;

[0224] (b6) transporting the ammonium phosphate solid in step (b4) to a second storage tank;

[0225] (c) catalytic oxidation;

[0226] (c1) Fill the solid-phase catalyst into a fixed-bed reactor; the solid-phase catalyst in step (c1) is a transition metal compound; the transition metal compound is at least one of Ce2O3, CeO2, Ce2(CO3)3, xCe2O3·(1 - x)CuO, Ce-Cu, Ce-Fe, Ce-Mn, Ce-Cr, MnO2, MnO, xMn2O3·(1 - x)CuO, xMnO·(1 - x)CuO, Mn3O4, Mn(OH)2, MnCO3, xFe2O3·(1 - x)MnO2, xFe2O3·(1 - x)CuO, Fe(OH)3, Fe2O3, Fe3O4, CuO, Cu(OH)2, CuMn2O4, Cr2O3, Cr(OH)3, xCr2O3·(1 - x)CuO, xCr2O3·(1 - x)MnO2 or CuCr2O4, where 0 < x < 1; the particle size of the solid-phase catalyst in step (c1) is 10 mm; the porosity of the fixed-bed reactor after filling the solid-phase catalyst in step (c1) is 50%. Under the action of the solid-phase catalyst, catalytic oxidation of the organic nitrogen-containing waste gas and oxygen is carried out, achieving the purpose of oxidizing the organic nitrogen-containing compound into nitrogen oxides. The operation is simple and easy to control. While improving the oxidation treatment efficiency, it also reduces the treatment cost and energy consumption; a solid-phase catalyst carrier is provided in the fixed-bed reactor, and the solid-phase catalyst carrier is selected from at least one of activated carbon, molecular sieve or montmorillonite; it has a good catalytic effect on the rapid degradation of organic nitrogen-containing waste gas by oxygen;

[0227] (c2) Feed the waste gas treated in step (b3) into the fixed-bed reactor in step (c1) at a flow rate of 40 mL / min;

[0228] (c3) Feed oxygen into the fixed-bed reactor in step (c1) at a flow rate of 60 mL / min, and carry out a catalytic oxidation reaction for 60 min in the fixed-bed reactor with the waste gas in step (c2) at a temperature of 280 °C and a pressure of 8 MPa;

[0229] (d) Secondary absorption;

[0230] (d1) Feed the remaining waste gas after mixing in step (c3) into the second gas distributor at the bottom of the second absorption tower at a flow rate of 60 mL / min, and feed oxygen into it at a flow rate of 50 mL / min;

[0231] (d2) adding an appropriate amount of 18% potassium hydroxide solution to a third storage tank, and inputting the potassium hydroxide solution in the third storage tank into a second atomizer at the top of the second absorption tower at a flow rate of 160 mL / min, spraying the potassium hydroxide solution downward from the second atomizer and atomizing the potassium hydroxide solution, and reacting with the mixed gas in step (d1) at a temperature of 35° C. and a pressure of 5 MPa in countercurrent contact for 45 minutes to generate a second mixed solution containing a certain concentration of potassium nitrate;

[0232] (d3) feeding the second mixed solution into a third reactor and performing vacuum distillation to obtain potassium nitrate solid and water;

[0233] (d4) returning the water in step (d3) to the first storage tank for reuse;

[0234] (d5) transporting the potassium nitrate solid in step (d3) to a fourth storage tank;

[0235] (e) Online monitoring;

[0236] (e1) adjusting the flow rate of deionized water in the first reactor online using a density meter to control the concentration of the dilute phosphoric acid solution;

[0237] (e2) adjusting the cooling water flow rate in the first temperature-controlled jacket outside the first reactor online by using a first thermometer to control the temperature in the first reactor to reach a certain set value;

[0238] (e3) adjusting the cooling water flow rate in the second temperature-controlled jacket outside the first absorption tower online by a second thermometer to control the temperature in the first absorption tower to reach a certain set value;

[0239] (e4) adjusting the cooling water flow rate in the fourth temperature-control jacket outside the second absorption tower online by a fourth thermometer to control the temperature in the second absorption tower to reach a certain set value;

[0240] (e5) online adjusting the cooling water flow rate in the third temperature control jacket outside the fixed bed reactor by a third thermometer to control the temperature in the fixed bed reactor to reach a certain set value;

[0241] (e6) connecting an ammonia gas detector to the first absorption tower in step (b), interlocking the ammonia gas detector with a third back-pressure valve for the dilute phosphate solution online, and adjusting the opening of the third back-pressure valve online to adjust the flow rate of the dilute phosphate solution;

[0242] (e7) A reduced nitrogen detector is connected to the fixed bed reactor in step (c), and the reduced nitrogen detector is interlocked with the tenth oxygen back pressure valve online, and the oxygen flow rate is adjusted by adjusting the opening of the tenth back pressure valve online;

[0243] (e8) A total nitrogen detector is connected to the second absorption tower in step (d), and the total nitrogen detector is online interlocked with the fourteenth back pressure valve of the potassium hydroxide solution and the thirteenth back pressure valve of the oxygen. The flow rate of the potassium hydroxide solution and the flow rate of the oxygen are adjusted by online adjusting the opening size of the fourteenth back pressure valve and the thirteenth back pressure valve;

[0244] (f) discharge of waste gas;

[0245] By observing the reading of the total nitrogen detector in step (e8), determine whether the total nitrogen content in the exhaust gas meets the standard;

[0246] If the total nitrogen content in the exhaust gas is lower than the emission standard, the exhaust gas will be discharged into the atmosphere through the pipeline;

[0247] If the total nitrogen content in the waste gas is higher than the emission standard, the waste gas will continue to remain in the second absorption tower, the sixteenth back pressure valve for exhaust will be closed through the online total nitrogen detector, the opening of the fourteenth back pressure valve for potassium hydroxide solution and the thirteenth back pressure valve for oxygen will be increased, and the treatment will continue until the waste gas meets the standard and is discharged into the atmosphere; the emission standard in step (f) is that the mass concentration of total nitrogen in the waste gas does not exceed 5×10 -4 mg / L.

[0248] Example 3:

[0249] A method for recycling nitrogen-containing waste gas comprises the following steps:

[0250] (a) preparing a dilute phosphoric acid solution;

[0251] The preparation of the dilute phosphoric acid solution comprises the following steps:

[0252] (a1) adding an appropriate amount of 60% phosphoric acid concentrated solution into the first reaction kettle;

[0253] (a2) adding an appropriate amount of deionized water into the first storage tank;

[0254] (a3) starting the agitator in the first reactor, adding the deionized water prepared in step (a2) to the first reactor, and diluting the concentrated phosphoric acid solution at a temperature of 30° C. to obtain a dilute phosphoric acid solution having a mass concentration of 32.5%;

[0255] (b) primary absorption;

[0256] (b1) the dilute phosphoric acid solution in step (a3) ​​is input into the first atomizer at the top of the first absorption tower at a flow rate of 70 mL / min, and the dilute phosphoric acid solution is sprayed downward from the first atomizer into atomization;

[0257] (b2) delivering the nitrogen-containing waste gas to a first gas distributor at the bottom of the first absorption tower at a flow rate of 20 mL / min, and the nitrogen-containing waste gas is dispersed in the first absorption tower by the first gas distributor;

[0258] (b3) The atomized dilute phosphoric acid solution in step (b1) and the nitrogen-containing waste gas dispersed in step (b2) are in countercurrent contact reaction at a temperature of 35 °C and a pressure of 2.5 MPa for 60 min to generate a first mixed solution containing ammonium phosphate salt with a certain concentration.

[0259] (b4) The first mixed solution in step (b3) is fed into a second reactor, and after vacuum distillation, ammonium phosphate salt solid and water are obtained.

[0260] (b5) The water in step (b4) is refluxed to the first storage tank for reuse.

[0261] (b6) The ammonium phosphate salt solid in step (b4) is transported to a second storage tank.

[0262] (c) Catalytic oxidation;

[0263] (c1) The solid-phase catalyst is filled into a fixed-bed reactor; the solid-phase catalyst in step (c1) is a transition metal compound; the transition metal compound is at least one of Ce2O3, CeO2, Ce2(CO3)3, xCe2O3·(1 - x)CuO, Ce-Cu, Ce-Fe, Ce-Mn, Ce-Cr, MnO2, MnO, xMn2O3·(1 - x)CuO, xMnO·(1 - x)CuO, Mn3O4, Mn(OH)2, MnCO3, xFe2O3·(1 - x)MnO2, xFe2O3·(1 - x)CuO, Fe(OH)3, Fe2O3, Fe3O4, CuO, Cu(OH)2, CuMn2O4, Cr2O3, Cr(OH)3, xCr2O3·(1 - x)CuO, xCr2O3·(1 - x)MnO2 or CuCr2O4, where 0 < x < 1; the particle size of the solid-phase catalyst in step (c1) is 3 mm; the porosity of the fixed-bed reactor after filling the solid-phase catalyst in step (c1) is 40%. Under the action of the solid-phase catalyst, the organic nitrogen-containing waste gas and oxygen are catalytically oxidized, achieving the purpose of oxidizing the organic nitrogen-containing compound into nitrogen oxides. The operation is simple and easy to control. While improving the oxidation treatment efficiency, it also reduces the treatment cost and energy consumption; a solid-phase catalyst carrier is provided in the fixed-bed reactor, and the solid-phase catalyst carrier is selected from at least one of activated carbon, molecular sieve or montmorillonite; it has a good catalytic effect on the rapid degradation of organic nitrogen-containing waste gas by oxygen;

[0264] (c2) The waste gas treated in step (b3) is transported to the fixed-bed reactor in step (c1) at a flow rate of 30 mL / min.

[0265] (c3) introducing oxygen into the fixed bed reactor in step (c1) at a flow rate of 45 mL / min, and carrying out a catalytic oxidation reaction with the exhaust gas in step (c2) in the fixed bed reactor at a temperature of 245° C. and a pressure of 6.5 MPa for 40 min;

[0266] (d) secondary absorption;

[0267] (d1) delivering the remaining waste gas after mixing in step (c3) at a flow rate of 45 mL / min and oxygen at a flow rate of 45 mL / min to a second gas distributor at the bottom of the second absorption tower;

[0268] (d2) adding an appropriate amount of a potassium hydroxide solution having a mass concentration of 15.5% to a third storage tank, and inputting the potassium hydroxide solution in the third storage tank into a second atomizer at the top of the second absorption tower at a flow rate of 110 mL / min, wherein the potassium hydroxide solution is sprayed downward from the second atomizer and atomized, and is in countercurrent contact with the mixed gas in step (d1) at a temperature of 27.5° C. and a pressure of 3.75 MPa to react for 37.5 min to generate a second mixed solution containing a certain concentration of potassium nitrate;

[0269] (d3) feeding the second mixed solution into a third reactor and performing vacuum distillation to obtain potassium nitrate solid and water;

[0270] (d4) returning the water in step (d3) to the first storage tank for reuse;

[0271] (d5) transporting the potassium nitrate solid in step (d3) to a fourth storage tank;

[0272] (e) Online monitoring;

[0273] (e1) adjusting the flow rate of deionized water in the first reactor online using a density meter to control the concentration of the dilute phosphoric acid solution;

[0274] (e2) adjusting the cooling water flow rate in the first temperature-controlled jacket outside the first reactor online by using a first thermometer to control the temperature in the first reactor to reach a certain set value;

[0275] (e3) adjusting the cooling water flow rate in the second temperature-controlled jacket outside the first absorption tower online by a second thermometer to control the temperature in the first absorption tower to reach a certain set value;

[0276] (e4) adjusting the cooling water flow rate in the fourth temperature-control jacket outside the second absorption tower online by a fourth thermometer to control the temperature in the second absorption tower to reach a certain set value;

[0277] (e5) online adjusting the cooling water flow rate in the third temperature control jacket outside the fixed bed reactor by a third thermometer to control the temperature in the fixed bed reactor to reach a certain set value;

[0278] (e6) connecting an ammonia gas detector to the first absorption tower in step (b), interlocking the ammonia gas detector with a third back-pressure valve for the dilute phosphate solution online, and adjusting the opening of the third back-pressure valve online to adjust the flow rate of the dilute phosphate solution;

[0279] (e7) A reduced nitrogen detector is connected to the fixed bed reactor in step (c), and the reduced nitrogen detector is interlocked with the tenth oxygen back pressure valve online, and the oxygen flow rate is adjusted by adjusting the opening of the tenth back pressure valve online;

[0280] (e8) A total nitrogen detector is connected to the second absorption tower in step (d), and the total nitrogen detector is online interlocked with the fourteenth back pressure valve of the potassium hydroxide solution and the thirteenth back pressure valve of the oxygen. The flow rate of the potassium hydroxide solution and the flow rate of the oxygen are adjusted by online adjusting the opening size of the fourteenth back pressure valve and the thirteenth back pressure valve;

[0281] (f) discharge of waste gas;

[0282] By observing the reading of the total nitrogen detector in step (e8), determine whether the total nitrogen content in the exhaust gas meets the standard;

[0283] If the total nitrogen content in the exhaust gas is lower than the emission standard, the exhaust gas will be discharged into the atmosphere through the pipeline;

[0284] If the total nitrogen content in the waste gas is higher than the emission standard, the waste gas will continue to remain in the second absorption tower, the sixteenth back pressure valve for exhaust will be closed through the online total nitrogen detector, the opening of the fourteenth back pressure valve for potassium hydroxide solution and the thirteenth back pressure valve for oxygen will be increased, and the treatment will continue until the waste gas meets the standard and is discharged into the atmosphere; the emission standard in step (f) is that the mass concentration of total nitrogen in the waste gas does not exceed 5×10 -4 mg / L.

[0285] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A method for recycling nitrogen-containing waste gas, characterized by: The following steps are included: (a) Prepare a dilute phosphoric acid solution; The preparation of the dilute phosphoric acid solution comprises the following steps: (a1) adding an appropriate amount of concentrated phosphoric acid solution into the first reaction kettle; (a2) adding an appropriate amount of deionized water into the first storage tank; (a3) starting the agitator in the first reactor and adding the deionized water prepared in step (a2) into the first reactor to dilute the concentrated phosphoric acid solution to obtain a dilute phosphoric acid solution; (b) first-order absorption; (b1) feeding the dilute phosphoric acid solution in step (a3) ​​into the first atomizer at the top of the first absorption tower, and spraying the dilute phosphoric acid solution downward from the first atomizer into atomization; (b2) transporting the nitrogen-containing waste gas to a first gas distributor at the bottom of the first absorption tower, and dispersing the nitrogen-containing waste gas in the first absorption tower by the first gas distributor; (b3) reacting the atomized dilute phosphoric acid solution in step (b1) with the nitrogen-containing waste gas dispersed in step (b2) in a countercurrent manner to generate a first mixed solution containing a certain concentration of ammonium phosphate; (b4) feeding the first mixed solution in step (b3) into a second reaction kettle and performing vacuum distillation to obtain ammonium phosphate solid and water; (b5) returning the water in step (b4) to the first storage tank for reuse; (b6) transferring the ammonium phosphate solid in step (b4) to a second storage tank; (c) catalytic oxidation; (c1) filling a solid-phase catalyst into a fixed-bed reactor; (c2) conveying the waste gas treated in step (b3) to the fixed bed reactor in step (c1); (c3) introducing oxygen into the fixed bed reactor in step (c1) to carry out a catalytic oxidation reaction with the waste gas in step (c2) in the fixed bed reactor; (d) secondary absorption; (d1) conveying the remaining waste gas and oxygen after mixing in step (c3) to the second gas distributor at the bottom of the second absorption tower; (d2) adding an appropriate amount of potassium hydroxide solution to a third storage tank, and inputting the potassium hydroxide solution in the third storage tank into a second atomizer at the top of the second absorption tower, wherein the potassium hydroxide solution is sprayed downward from the second atomizer and atomized, and reacts with the mixed gas in a countercurrent manner in step (d1) to generate a second mixed solution containing a certain concentration of potassium nitrate; (d3) feeding the second mixed liquid into a third reaction kettle and performing vacuum distillation to obtain potassium nitrate solid and water; (d4) returning the water in step (d3) to the first storage tank for reuse; (d5) transporting the potassium nitrate solid in step (d3) to a fourth storage tank.

2. The method for recycling nitrogen-containing waste gas according to claim 1, wherein: Also includes the steps, (e) Online monitoring; (e1) adjusting the flow rate of deionized water in the first reactor online using a density meter to control the concentration of the dilute phosphoric acid solution; (e2) regulating the flow rate of cooling water in the first temperature-control jacket outside the first reactor online by means of a first thermometer to control the temperature in the first reactor to reach a certain set value; (e3) regulating the cooling water flow rate in the second temperature-controlled jacket outside the first absorption tower online by a second thermometer to control the temperature in the first absorption tower to reach a certain set value; (e4) regulating the cooling water flow rate in the fourth temperature-control jacket outside the second absorption tower online by a fourth thermometer to control the temperature in the second absorption tower to reach a certain set value; (e5) online adjusting the cooling water flow rate in the third temperature-control jacket outside the fixed-bed reactor by a third thermometer to control the temperature in the fixed-bed reactor to reach a certain set value; (e6) connecting an ammonia gas detector to the first absorption tower in step (b), wherein the ammonia gas detector is interlocked with a third back-pressure valve for the dilute phosphate solution online, and adjusting the opening of the third back-pressure valve online to adjust the flow rate of the dilute phosphate solution; (e7) A reduced nitrogen detector is connected to the fixed bed reactor in step (c), and the reduced nitrogen detector is interlocked with the tenth oxygen back pressure valve online, and the oxygen flow rate is adjusted by adjusting the opening of the tenth back pressure valve online; (e8) A total nitrogen detector is connected to the second absorption tower in step (d), and the total nitrogen detector is online interlocked with the fourteenth back pressure valve of the potassium hydroxide solution and the thirteenth back pressure valve of the oxygen. By adjusting the opening size of the fourteenth back pressure valve and the thirteenth back pressure valve online, the flow rate of the potassium hydroxide solution and the flow rate of the oxygen are adjusted.

3. The method for recycling nitrogen-containing waste gas according to claim 2, wherein: Also includes the steps, (f) discharge of waste gases; By observing the reading of the total nitrogen detector in step (e8), determine whether the total nitrogen content in the exhaust gas meets the standard; If the total nitrogen content in the exhaust gas is lower than the emission standard, the exhaust gas will be discharged into the atmosphere through the pipeline; If the total nitrogen content in the waste gas is higher than the emission standard, the waste gas will continue to remain in the second absorption tower, and the sixteenth back pressure valve for emptying will be closed through the online total nitrogen detector, and the opening of the fourteenth back pressure valve for potassium hydroxide solution and the thirteenth back pressure valve for oxygen will be increased, and the treatment will continue until the waste gas meets the standard and is discharged into the atmosphere.

4. The method for recycling nitrogen-containing waste gas according to claim 1, wherein: The mass concentration of the concentrated phosphoric acid solution in step (a1) is 50% to 70%; the temperature of the dilute phosphoric acid solution in step (a3) ​​is 20°C to 40°C; the mass concentration of the dilute phosphoric acid solution in step (a3) ​​is 30% to 35%; the flow rate of the dilute phosphoric acid solution in step (b1) is 60 mL / min to 80 mL / min; the flow rate of the nitrogen-containing waste gas in step (b2) is 15 mL / min to 25 mL / min; the reaction time in step (b3) is 30 min to 90 min; the reaction temperature in step (b3) is 30°C to 40°C; and the reaction pressure in step (b3) is 1 MPa to 4 MPa.

5. The method for recycling nitrogen-containing waste gas according to claim 1, wherein: The solid-phase catalyst in the step (c1) is a transition metal compound; the transition metal compound is at least one of Ce2O3, CeO2, Ce2(CO3)3, xCe2O3∙(1-x)CuO, Ce-Cu, Ce-Fe, Ce-Mn, Ce-Cr, MnO2, MnO, xMn2O3∙(1-x)CuO, xMnO∙(1-x)CuO, Mn3O4, Mn(OH)2, MnCO3, xFe2O3∙(1-x)MnO2, xFe2O3 ∙(1-x)CuO, Fe(OH)3, Fe2O3, Fe3O4, CuO, Cu(OH)2, CuMn2O4, Cr2O3, Cr(OH)3, xCr2O3∙(1-x)CuO, xCr2O3∙(1-x)MnO2 or CuCr2O4, where 0 < x < 1; the particle size of the solid-phase catalyst in the step (c1) is 0.25 mm to 10 mm; the void fraction of the fixed-bed reactor after filling with the solid-phase catalyst in the step (c1) is 30% to 50%; a solid-phase catalyst carrier is provided in the fixed-bed reactor, and the solid-phase catalyst carrier is selected from at least one of activated carbon, molecular sieve or montmorillonite.

6. The method for recycling nitrogen-containing waste gas according to claim 1, characterized in that: The flow rate of the waste gas in the step (c2) is 20 mL / min to 40 mL / min; the flow rate of oxygen in the step (c3) is 30 mL / min to 60 mL / min; the reaction temperature in the step (c3) is 210 °C to 280 °C; the reaction pressure in the step (c3) is 5 MPa to 8 MPa; the reaction time in the step (c3) is 20 min to 60 min.

7. The method for recycling nitrogen-containing waste gas according to claim 1, characterized in that: The flow rate of oxygen in the step (d1) is 40 mL / min to 50 mL / min; the flow rate of the waste gas in the step (d1) is 30 mL / min to 60 mL / min; the mass concentration of the potassium hydroxide solution in the step (d2) is 13% to 18%; the flow rate of the potassium hydroxide solution in the step (d2) is 60 mL / min to 160 mL / min; the reaction temperature in the step (d2) is 20 °C to 35 °C; the reaction pressure in the step (d2) is 2.5 MPa to 5 MPa; the reaction time in the step (d2) is 30 min to 45 min.

8. A resource processing equipment for nitrogen-containing waste gas, characterized by: It includes a first storage tank (200), the drain outlet of the first storage tank is connected to a first reaction kettle (300) through a pipeline, a first temperature control jacket (301) is sleeved on the outer peripheral surface of the first reaction kettle, and the water inlet of the first temperature control jacket is connected to a cooling water source; The liquid discharge port of the first reactor is connected to a first absorption tower (100) via a pipeline. A first atomizer (101) is provided at the top of the first absorption tower, and the first atomizer is connected to the liquid discharge port of the first reactor via a pipeline. A first gas distributor (102) is provided at the bottom of the first absorption tower, and the first gas distributor is connected to a nitrogen-containing waste gas source via a pipeline. A second temperature-control jacket (103) is provided on the outer peripheral surface of the first absorption tower, and a water inlet of the second temperature-control jacket is connected to a cooling water source. The liquid outlet of the first absorption tower is connected to the second reactor (400) via a pipeline, the water outlet of the second reactor is connected to the first storage tank via a pipeline, and the solid product outlet of the second reactor is connected to the second storage tank (500) via a pipeline; The exhaust port of the first absorption tower is connected to a fixed bed reactor (600) via a pipeline, the air inlet of the fixed bed reactor is connected to an oxygen source via a pipeline, and the interior of the fixed bed reactor is filled with a solid-phase catalyst (601); a third temperature-control jacket (602) is provided on the outer circumference of the fixed bed reactor, and the water inlet of the third temperature-control jacket is connected to a cooling water source via a pipeline; The invention also includes a second absorption tower (700), wherein a second gas distributor (701) is provided at the bottom of the second absorption tower, the second gas distributor is connected to the exhaust port of the fixed bed reactor via a pipeline, and the second gas distributor is connected to the oxygen source via a pipeline; a second atomizer (702) is provided at the top of the second absorption tower, the second atomizer is connected to a third storage tank (800) via a pipeline, the third storage tank is located outside the second absorption tower, and the third storage tank contains potassium hydroxide solution; the exhaust port of the second absorption tower is connected to the outside air via a pipeline; a fourth temperature control jacket (703) is provided on the outer peripheral surface of the second absorption tower, and the water inlet of the fourth temperature control jacket is connected to the cooling water source; The liquid discharge port of the second absorption tower is connected to the third reactor (900) via a pipeline, the water discharge port of the third reactor is connected to the first storage tank via a pipeline, and the liquid discharge port of the third reactor is connected to the fourth storage tank (1000) via a pipeline.

9. The resource recovery treatment equipment for nitrogen-containing waste gas according to claim 8, characterized in that: The first gas distributor includes an air inlet pipe (1021), one end of which passes through the first absorption tower and is connected to an air inlet cross pipe (1022), two groups of air inlet branch pipes (1023) are symmetrically connected on the outer peripheral surface of the air inlet cross pipe, and the tops of the two groups of air inlet branch pipes are both connected to multiple air nozzles (1024); the first gas distributor also includes a first-level diversion component (1025) and a second-level diversion component (1026), the first-level diversion component is located on the upper side of the air nozzle, and the second-level diversion component is located on the upper side of the first-level diversion component.

10. The resource recovery treatment equipment for nitrogen-containing waste gas according to claim 9, characterized in that: The first-stage flow splitter assembly comprises a plurality of inverted conical first flow splitters (10251), the number of the first flow splitters being equal to the number of the air nozzles, the plurality of the first flow splitters being respectively located directly above the plurality of air nozzles, and adjacent first flow splitters being connected via a first connecting rod (10252); a first fixing ring (10253) being connected to the inner side wall of the first absorption tower, and the first flow splitters close to the first fixing ring being connected to the first fixing ring via a first connecting rod; The secondary diversion assembly includes a plurality of liquid storage boxes (10261), the number of the plurality of liquid storage boxes is equal to the number of the plurality of first diverters, the plurality of liquid storage boxes are respectively located directly above the plurality of first diverters, a leakage hole (10262) is provided at the bottom of the liquid storage box, a plurality of second diverters (10264) are connected in a ring shape at the top of the liquid storage box via a support rod (10263), two adjacent liquid storage boxes are connected via a second connecting rod (10265), a second fixed ring (10266) is slidably connected to the inner side wall of the first absorption tower, and the liquid storage box close to the second fixed ring is connected to the second fixed ring via a second connecting rod.

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