CN214680967U - Nitrogen oxide waste gas resourceful treatment device - Google Patents
Nitrogen oxide waste gas resourceful treatment device Download PDFInfo
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- CN214680967U CN214680967U CN202120780005.6U CN202120780005U CN214680967U CN 214680967 U CN214680967 U CN 214680967U CN 202120780005 U CN202120780005 U CN 202120780005U CN 214680967 U CN214680967 U CN 214680967U
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Abstract
The utility model provides a nitrogen oxide waste gas resourceful treatment device, the device is including the oxidation reactor, one-level absorption tower and the second grade absorption tower that connect gradually, through establishingThe liquid returning pipe is arranged to change the primary absorption tower and the secondary absorption tower into an absorption whole, partial secondary absorption liquid can be intermittently introduced into the upper part of the primary absorption tower to be sprayed, the concentration of nitric acid in the primary absorption liquid is improved to more than 40 wt% to be recycled, corresponding fresh secondary absorption liquid only needs to be supplemented in the whole process, the emission of nitrogen oxides can be guaranteed to reach the standard, secondary pollution sources such as waste water and waste gas are not generated, and NO can be usedXThe nitric acid is converted into high-concentration nitric acid with the nitric acid concentration of more than 40 wt% for recycling, so that the resource treatment is realized, and the method has the advantages of compact structure, small equipment investment, low treatment cost and the like.
Description
Technical Field
The utility model belongs to the technical field of exhaust-gas treatment, especially, relate to a nitrogen oxide waste gas resourceful treatment device.
Background
Nitric acid is a strong inorganic monobasic acid with strong oxidizing property and strong corrosivity, is an important chemical raw material, and is often used as an oxidizing agent in industrial processes. However, nitric acid is reduced to form nitrogen oxides (mainly NO and NO)2Collectively called NOX) Yellow or brown smoke, commonly known as 'yellow dragon', is one of the important pollution sources causing atmospheric pollution. The nitrogen oxide waste gas not only causes acid rain and acid mist, but also can destroy the ozone layer to give natureThe environment and the production and the life of human beings bring serious harm. Therefore, the absorption and resource utilization of the nitrogen oxide waste gas are important components in environmental management and various nitric acid industrial production, and are not only required for realizing the economic sustainable development of China, but also required for the self health of human beings.
At present, the treatment method of nitrogen oxide waste gas mainly comprises a catalytic reduction method, a solvent absorption method, a solid adsorption method and a biological treatment method. Catalytic reduction processes include Selective Catalytic Reduction (SCR) and selective non-catalytic reduction (SNCR). The most used reducing agents in the catalytic reduction method are urea and ammonium sulfite, and the reducing agents can react NO under the action of certain temperature and catalystXReducing to harmless nitrogen and other nitrogen-free components. The solvent absorption method includes a direct solvent absorption method, and the used solvent includes water, dilute nitric acid, alkaline solution (alkaline liquid such as sodium hydroxide, sodium carbonate, ammonia water and the like) and the like. Solid adsorption method for NO by adsorbentXAdsorbing and fixing to prevent pollution caused by entering air, and commonly used adsorbents include molecular sieves, activated carbon, silica gel and the like. The essence of the biochemical treatment is to utilize the life activity of microbes to convert NOXTransformed into harmless inorganic substances and cytoplasm of microorganisms.
The method has great treatment difficulty for the nitrogen oxide waste gas generated in the noble metal purification process, because the waste gas generated by the operations of dissolving aqua regia, removing acid and converting sodium salt and the like in the noble metal purification process mainly contains high-concentration NO and a small amount of HCl and Cl2The fluctuation of nitrogen oxides is large in the continuous emission process of gas and nitrogen oxides, the problem of high concentration of the nitrogen oxides exists instantaneously, the gas and nitrogen oxides have strong pungent smell and high toxicity, the body health of operators is damaged, and the atmospheric environment is polluted. In addition, since the noble metal purification and recovery belong to liquid-solid reaction, and the generated nitrogen oxide waste gas contains moisture, the nitrogen oxide waste gas treatment method is preferably a solvent absorption method. The absorbent is selected from water, alkali liquor, ammonia water and the like, but the absorption efficiency of the nitrogen oxides is limited, and the emission reaching the standard cannot be realized, mainly because the waste gas is mainly NO and the oxidation degree of the nitrogen oxides is lower.
The solvent absorption method has the advantages of simple process, less investment, easily obtained raw materials and the like, can convert the nitrogen oxide into nitric acid for recycling, and is widely applied to enterprises. For example, CN205832945U discloses a device for recovering nitrogen oxide waste gas to prepare dilute nitric acid, which comprises an air purifier, an air pressurizing device, an oxidation tower for oxidizing low-valence nitrogen oxide into high-valence nitrogen oxide, a first absorption tower for absorbing nitrogen oxide with water as an absorbent to generate dilute nitric acid, and a second absorption tower for absorbing sodium hydroxide solution as an absorbent, wherein the air purifier is connected with the lower part of the oxidation tower through a pipeline, the nitrogen oxide waste gas is connected with the lower part of the oxidation tower through a pump, the upper part of the oxidation tower is connected with the lower part of the first absorption tower through a pipeline, the upper part of the first absorption tower is connected with the lower part of the second absorption tower through a pipeline, and the upper part of the second absorption tower is connected with an exhaust pipe. The device has compact structure, easy operation, advantage that absorption efficiency is high, and nitrogen oxide waste gas can reach national emission standard through handling, but, first absorption tower uses water as the absorbent, and the dilute nitric acid concentration as the product is lower, and the second absorption tower uses sodium hydroxide solution as the absorbent, can produce the salt waste water that contains sodium nitrate and sodium nitrite, causes secondary pollution.
CN1864812A discloses an industrial process Nitrogen Oxide (NO)X) The waste gas treatment and resource utilization method comprises a pressurization absorption working section and a decompression concentration increasing working section; the pressurized absorption section adopts single tower or multi-tower series absorption: will contain NOXThe waste gas and the air are mixed in proportion, and then enter from the bottom of the first tower after being pressurized for multistage series absorption, the purified gas is discharged from the top of the tail tower, and the low-concentration nitric acid generated after absorption and reaction is discharged from the bottom of the first tower and enters a pressure reduction and concentration section; the pressure reduction and concentration section adopts a concentration tower to bleach and dehydrate, low-concentration nitric acid enters from the top of the concentration tower or the middle part of the concentration tower, and NO-containing nitric acid is extracted from a vacuum system at the top of the concentration towerXThe gas enters the absorption section again after being pressurized, and the water or the dilute acid evaporated by the thickening tower is added from the top end of the tail tower of the absorption section and is used as an absorbent to be in countercurrent contact with the gas entering the tower and transfer mass. The method can ensure NO contentXEnvironmental protection of exhaust gas to discharge NOXAll are carried outRecycling, generating 55-65% of high-concentration nitric acid for industrial recycling, and ensuring that secondary pollution sources such as wastewater and waste gas are not generated in the whole process. However, the method not only needs to pressurize the nitrogen oxide waste gas to an absolute pressure of 2.5-5 atm, but also needs to obtain high-concentration nitric acid through a pressure reduction and concentration working section, and has the defects of complex operation, high equipment cost and the like.
CN205115054U discloses an utilize equipment of nitrogen oxide water absorption preparation dilute nitric acid, including oxidation reaction kettle, condenser, buffer tank, one-level nitre cigarette absorption tower, second grade nitre cigarette absorption tower, tertiary nitre cigarette absorption tower and the level four nitre cigarette absorption tower that connects gradually, level four nitre cigarette absorption tower reverse access deionized water and air suction jar, simultaneously, level four nitre cigarette absorption tower forward connect nitrogen oxide waste gas centrifuge and alkali absorption tower, the alkali absorption tower is connected with sodium thiosulfate-lye tank. The equipment adopts supplementary air and deionized water to oxidize nitric oxide and nitrogen dioxide in the nitrogen oxide, the reaction generates nitric acid, the four-stage reverse countercurrent absorption is arranged to increase the gas-liquid contact area, the nitric acid with the concentration of 40% can be obtained, and the absorption efficiency is further improved by arranging the nitrogen oxide waste gas centrifugal machine and the alkali absorption tower, so that the treatment efficiency of the nitrogen oxide is not lower than 99.5%. However, the equipment has the defects that the absorption tower is more, the equipment investment is increased, and secondary wastewater is generated by the alkali absorption tower.
To sum up, at present, the urgent need is to develop a nitrogen oxide waste gas resourceful treatment device, which not only can ensure the discharge to reach the standard of nitrogen oxide, does not produce secondary pollution sources such as waste water and waste gas, but also can remove NO from the waste water and waste gasXThe nitric acid is converted into high-concentration nitric acid for recycling, so that the resource treatment is realized, and the method has the advantages of compact structure, low equipment investment, low treatment cost and the like.
SUMMERY OF THE UTILITY MODEL
To the deficiency that prior art exists, the utility model aims to provide a nitrogen oxide waste gas resourceful treatment device, the device returns liquid through setting up including oxidation reactor, one-level absorption tower and the second grade absorption tower that connects graduallyThe pipe becomes one absorption whole with one-level absorption tower and second grade absorption tower, can intermittently import partial second grade absorption liquid the upper portion of one-level absorption tower sprays, improves nitric acid concentration in the one-level absorption liquid to more than 40 wt% recycle, and corresponding fresh second grade absorption liquid only needs to be replenished in the whole journey, not only can guarantee the discharge to reach standard of nitrogen oxide, does not produce secondary pollution sources such as waste water waste gas, can also be with NOXThe nitric acid is converted into high-concentration nitric acid with the nitric acid concentration of more than 40 wt% for recycling, so that the resource treatment is realized, and the method has the advantages of compact structure, small equipment investment, low treatment cost and the like.
To achieve the purpose, the utility model adopts the following technical proposal:
an object of the utility model is to provide a nitrogen oxide waste gas resourceful treatment device, including oxidation reactor, one-level absorption tower and second grade absorption tower open at oxidation reactor's middle part has nitrogen oxide waste gas entry and oxidant entry, oxidation reactor's top with the lower part of one-level absorption tower is connected through one-level intake pipe, the top of one-level absorption tower with the lower part of second grade absorption tower is connected through the second grade intake pipe, the bottom of one-level absorption tower with the upper portion of one-level absorption tower is connected through one-level absorption liquid pipeline, set up the one-level circulating pump on the one-level absorption liquid pipeline, the bottom of second grade absorption tower with the upper portion of second grade absorption tower is connected through the second grade absorption liquid pipeline, set up the second grade circulating pump on the second grade absorption liquid pipeline;
the primary absorption liquid pipeline corresponding to the outlet of the primary circulating pump and the secondary absorption liquid pipeline corresponding to the outlet of the secondary circulating pump are connected through a liquid return pipe, and the primary absorption liquid pipeline corresponding to the position between the outlet of the primary circulating pump and the liquid return pipe is connected with a nitric acid solution storage tank through a liquid discharge pipe; and a first liquid supplementing pipe is arranged at the upper part of the secondary absorption tower, and a first exhaust pipe is arranged at the top of the secondary absorption tower.
The device regards water as one-level absorption liquid, regards hydrogen peroxide solution as second grade absorption liquid, and wherein, the main reaction of nitrogen oxide and water includes:
2NO2＝N2O4
NO+NO2＝N2O3
N2O4+H2O＝HNO2+HNO3
N2O3+H2O＝2HNO2
3HNO2＝HNO3+H2O+2NO
3NO2+H2O＝2HNO3+NO
the main reactions of nitrogen oxides with hydrogen peroxide include:
2NO+3H2O2＝2HNO3+2H2O
NO+H2O2＝NO2+H2O
HNO2+H2O2＝HNO3+H2O
because the first-stage absorption tower takes water as the first-stage absorption liquid, although the cost is low, partial nitrogen oxides can be converted into nitric acid, NO in a reaction product cannot be completely converted into nitric acid, and HNO exists in the absorption liquid2Different from HNO3Can be in liquid phase as H+And NO3 -Is stably present in the form of, HNO2Is subjected to H+Influence of (2) only by HNO2The molecular exists in a molecular form, the solubility of the molecular exists very low, and NO is easily decomposed, so that NO still exists in gas discharged from the top of the primary absorption tower, and HNO in absorption liquid2Need to be further converted into HNO3. Compared with the prior art, the secondary absorption tower takes the hydrogen peroxide solution as the secondary absorption liquid, the nitrogen oxide can not only react with water, but also react with the hydrogen peroxide, so that the gas exhausted from the top of the secondary absorption tower basically does not contain the nitrogen oxide, and only HNO exists in the secondary absorption liquid3And H2O2Two solutes, with NO, NO2And HNO2Etc. further reactThere is still good nitrogen oxide absorption capacity.
For this reason, the device returns the liquid pipe through setting up and becomes an absorption whole with one-level absorption tower and second grade absorption tower, can intermittently be leading-in with partial second grade absorption liquid the upper portion of one-level absorption tower sprays, improves nitric acid concentration in the one-level absorption liquid and carries out recycle to more than 40 wt%, and whole journey only need supply corresponding fresh second grade absorption liquid, not only can guarantee nitrogen oxide's discharge to reach standard, does not produce secondary pollution sources such as waste water waste gas, can also be with NOXThe nitric acid is converted into high-concentration nitric acid with the nitric acid concentration of more than 40 wt% for recycling, so that the resource treatment is realized, and the method has the advantages of compact structure, small equipment investment, low treatment cost and the like.
As the utility model discloses preferred technical scheme, the top of second grade absorption tower with the lower part of tertiary absorption tower is passed through first blast pipe is connected, the bottom of tertiary absorption tower with the upper portion of tertiary absorption tower is connected through tertiary absorption liquid pipeline sets up tertiary circulating pump on the road the upper portion of tertiary absorption tower sets up second moisturizing pipe the top of second grade absorption tower sets up the second blast pipe.
It is worth to say that the device of the utility model is further provided with a three-stage absorption tower, which can fully ensure that the treated gas meets the emission standard; however, practice proves that the gas entering the three-stage absorption tower basically does not contain nitrogen oxides, so that whether the three-stage absorption tower is put into use or not can be judged according to the treatment effect of the first two-stage absorption tower.
As the utility model discloses preferred technical scheme, the second fluid infusion pipe sets up the export of tertiary circulating pump corresponds on the tertiary absorption liquid pipeline, help improving the mixed degree between the tertiary absorption liquid of new replenishment and the tertiary absorption liquid of endless, and then guarantee that the top of the tower sprays the even unanimity of concentration of liquid in the tertiary absorption tower.
As the preferred technical scheme of the utility model the export of tertiary circulating pump corresponds tertiary absorption liquid pipeline sets up tertiary cooler.
As the utility model discloses preferred technical scheme the export of one-level circulating pump corresponds one-level absorption liquid pipeline sets up the one-level cooler.
As the utility model discloses preferred technical scheme the export of second grade circulating pump corresponds second grade absorption liquid pipeline sets up the second grade cooler.
As the utility model discloses preferred technical scheme, first fluid infusion pipe sets up the export of second grade circulating pump corresponds on the second grade absorption liquid pipeline, help improving the mixed degree between new supplementary second grade absorption liquid and the endless second grade absorption liquid, and then guarantee that the concentration of second grade absorption tower inner tower top spray liquid is even unanimous.
As the utility model discloses preferred technical scheme set up booster fan in the one-level intake pipe.
As the preferable technical proposal of the utility model, a cooling coil is arranged outside the oxidation reactor.
As the utility model discloses preferred technical scheme oxidant entry sets up the oxidant intake pipe set up the air supplement fan in the oxidant intake pipe.
It is worth explaining, the preferred packed tower of one-level absorption tower, second grade absorption tower, tertiary absorption tower among the device, packed tower pressure reduces, simple structure, operating flexibility is big, is applicable to corrosive materials, can effectively increase the reverse area of contact of nitrogen oxide waste gas and absorption liquid, is favorable to improving the absorption capacity of absorption liquid to nitrogen oxide.
It is worth explaining, one-level circulating pump, second grade circulating pump, tertiary circulating pump among the device are used for circulating absorption liquid at different levels to tower upper portion from the bottom of the tower and spray.
It is worth explaining, one-level cooler, second grade cooler, tertiary cooler in the device are used for cooling the absorption liquid at all levels, because nitrogen oxide's absorption reaction belongs to exothermic reaction, can improve the absorptive capacity through the temperature that reduces the absorption liquid at all levels.
The method for recycling the nitrogen oxide waste gas by adopting the device comprises the following contents:
introducing nitrogen oxide waste gas and air with the volume ratio of 1 (3-5) into an oxidation reactor for oxidation reaction, controlling the temperature of the oxidation reaction to be less than 30 ℃, and controlling the oxidation degree of the nitrogen oxide in the gas of the oxidation reactor to be 70-80%;
introducing the gas of the oxidation reactor into a primary absorption tower, absorbing with water as primary absorption liquid, controlling the retention time of the waste gas of the primary absorption tower at 10-25s, the temperature of the spray liquid at the top of the tower at 15-20 ℃, and the spray density at 12-15m3/(m2·h)；
Introducing the gas in the first-stage absorption tower into a second-stage absorption tower, absorbing by using a hydrogen peroxide solution with the concentration of 5-27.5 wt% as a second-stage absorption liquid, controlling the retention time of the waste gas in the second-stage absorption tower to be 10-25s, controlling the temperature of the spray liquid at the top of the tower to be 30-40 ℃, and controlling the spray density to be 12-15m3/(m2·h)；
Introducing the gas in the second-stage absorption tower into a third-stage absorption tower, absorbing by using a urea solution with the concentration of 15-30 wt% as a third-stage absorption liquid, controlling the retention time of the waste gas in the third-stage absorption tower to be 10-25s, controlling the temperature of the spray liquid at the top of the tower to be 30-40 ℃, and controlling the spray density to be 12-15m3/(m2·h)；
After the circulation is established, 1-15m of nitric acid is discharged through a liquid discharge pipe when the concentration of nitric acid in the primary absorption liquid is more than or equal to 40wt percent3The primary absorption liquid is led into a nitric acid solution storage tank, and 1-15m is led into the nitric acid solution storage tank through a liquid return pipe3The secondary absorption liquid is guided into the upper part of the primary absorption tower for spraying, and 1-15m of the secondary absorption tower is supplemented by a first liquid supplementing pipe3The hydrogen peroxide solution of (1).
It is worth to be noted that, in the method for the resource treatment of the nitrogen oxide waste gas, the concentration of the nitric acid in the primary absorption liquid discharged for the first time does not reach the standard, and the circulation is gradually established after a part of the secondary absorption liquid is introduced into the upper part of the primary absorption tower through the return pipe for spraying for the first time.
It is worth explaining, the device is based on absorbing holistic one-level absorption tower and second grade absorption tower as one to water is as the one-level absorption liquid, regard as the second grade absorption liquid with hydrogen peroxide solution, and is leading-in with partial second grade absorption liquid through intermittent type nature the upper portion of one-level absorption tower sprays, improves the nitric acid concentration in the one-level absorption liquid and carries out recycle to more than 40 wt%, and whole journey only need supply corresponding fresh second grade absorption liquid, compares in traditional nitrogen oxide exhaust-gas treatment method, the utility model discloses the waste gas and the intermittent type operating mode that more are fit for high concentration nitrogen oxide have the operation stably, convenient operation, elasticity is big, do not produce secondary pollutant and guarantee the advantage of discharge up to standard.
It is worth to be noted that in the method for recycling the nitrogen oxide waste gas, only HNO exists in the secondary absorption liquid by ensuring that a certain hydrogen peroxide concentration is maintained in the secondary absorption liquid3And H2O2Two solutes, with NO, NO2And HNO2And the like, and still has good nitrogen oxide absorption capacity.
It is worth to be noted that in the method for resource treatment of nitrogen oxide waste gas, urea solution is selected as the third-stage absorption liquid for absorption, and the method mainly comprises the following reactions:
4CO(NH2)2+6NO2＝4CO2+7N2+8H2o (main reaction)
2CO(NH2)2+6NO＝2CO2+5N2+4H2O
Because the urea and the nitrogen oxide generate carbon dioxide, nitrogen and water, the waste liquid after absorption has no salt byproducts, the treatment cost is low, the absorption rate is high, no secondary pollution is caused, and after the three-stage absorption liquid circulates for a period of time, the fresh urea solution is supplemented through the second liquid supplementing pipe.
Compared with the prior art, the beneficial effects of the utility model are that:
the device comprises an oxidation reactor, a first-stage absorption tower and a second-stage absorption tower which are connected in sequence, and the device passes throughThe arrangement of the liquid return pipe enables the first-stage absorption tower and the second-stage absorption tower to be an absorption whole body, partial second-stage absorption liquid can be intermittently introduced into the upper portion of the first-stage absorption tower to be sprayed, the concentration of nitric acid in the first-stage absorption liquid is increased to more than 40 wt% to be recycled, corresponding fresh second-stage absorption liquid only needs to be supplemented in the whole process, the emission of nitrogen oxides reaching the standard can be guaranteed, secondary pollution sources such as waste water and waste gas are not generated, and NO can be usedXThe nitric acid is converted into high-concentration nitric acid with the nitric acid concentration of more than 40 wt% for recycling, so that the resource treatment is realized, and the method has the advantages of compact structure, small equipment investment, low treatment cost and the like.
Drawings
FIG. 1 is a schematic view of a nitrogen oxide waste gas recycling device according to embodiment 1 of the present invention;
in the figure: 1-an oxidation reactor; 2-air supply fan; 3-a booster fan; 4-a first-stage absorption tower; 5-first-stage circulating pump; 6-first stage cooler; 7-a secondary absorption tower; 8-a two-stage circulating pump; 9-a secondary cooler; 10-a tertiary absorption tower; 11-three-stage circulating pump; 12-a tertiary cooler; 13-nitric acid solution storage tank; 14-liquid return pipe.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments with reference to the accompanying drawings.
Example 1
The embodiment provides a recycling treatment device for nitrogen oxide waste gas, as shown in fig. 1, comprising an oxidation reactor 1, a primary absorption tower 4 and a secondary absorption tower 7, the middle part of the oxidation reactor 1 is provided with a nitrogen oxide waste gas inlet and an oxidant inlet, the top of the oxidation reactor 1 is connected with the lower part of the primary absorption tower 4 through a primary gas inlet pipe, the top of the first-stage absorption tower 4 is connected with the lower part of the second-stage absorption tower 7 through a second-stage air inlet pipe, the bottom of the primary absorption tower 4 is connected with the upper part of the primary absorption tower 4 through a primary absorption liquid pipeline, a primary circulating pump 5 is arranged on the primary absorption liquid pipeline, the bottom of the secondary absorption tower 7 is connected with the upper part of the secondary absorption tower 7 through a secondary absorption liquid pipeline, and a secondary circulating pump 8 is arranged on the secondary absorption liquid pipeline;
the primary absorption liquid pipeline corresponding to the outlet of the primary circulating pump 5 and the secondary absorption liquid pipeline corresponding to the outlet of the secondary circulating pump 8 are connected through a liquid return pipe 14, and the primary absorption liquid pipeline corresponding to the position between the outlet of the primary circulating pump 5 and the liquid return pipe 14 is connected with a nitric acid solution storage tank 13 through a liquid discharge pipe; a first liquid supplementing pipe is arranged at the upper part of the secondary absorption tower 7, and a first exhaust pipe is arranged at the top of the secondary absorption tower 7;
the device also comprises a third-stage absorption tower 10, wherein the top of the second-stage absorption tower 7 is connected with the lower part of the third-stage absorption tower 10 through the first exhaust pipe, the bottom of the third-stage absorption tower 10 is connected with the upper part of the third-stage absorption tower 10 through a third-stage absorption liquid pipeline, a third-stage circulating pump 11 is arranged on the third-stage absorption liquid pipeline, a second liquid supplementing pipe is arranged on the upper part of the third-stage absorption tower 10, and a second exhaust pipe is arranged at the top of the second-stage absorption tower 7; the second liquid supplementing pipe is arranged on the third-stage absorption liquid pipeline corresponding to the outlet of the third-stage circulating pump 11; a third cooler 12 is arranged on the third-stage absorption liquid pipeline corresponding to the outlet of the third-stage circulating pump 11;
a primary cooler 6 is arranged on the primary absorption liquid pipeline corresponding to the outlet of the primary circulating pump 5; a secondary cooler 9 is arranged on the secondary absorption liquid pipeline corresponding to the outlet of the secondary circulating pump 8; the first liquid supplementing pipe is arranged on the secondary absorption liquid pipeline corresponding to the outlet of the secondary circulating pump 8; a booster fan 3 is arranged on the primary air inlet pipe; a cooling coil is arranged outside the oxidation reactor 1; an oxidant inlet pipe is arranged at the oxidant inlet, and an air supplementing fan 2 is arranged on the oxidant inlet pipe;
the first-stage absorption tower 4, the second-stage absorption tower 7 and the third-stage absorption tower 10 are all packed towers, plastic pall rings are selected as packing, and the size of each absorption tower is phi 900 multiplied by 6500mm, phi 900 multiplied by 6500mm and phi 900 multiplied by 5000mm in sequence.
Application example 1
The application example provides a method for recycling nitrogen oxide waste gas by adopting the device in the embodiment 1, the to-be-treated nitrogen oxide waste gas is the waste gas of high-concentration nitrogen oxide generated in the purification and recovery process of a noble metal platinum mesh catalyst, and the maximum flow is 150m3H, containing NO, HCl and Cl2Air, water vapor, etc., wherein NOXThe content is 8333mg/m3(NO is more than 95%), HCl content is 500mg/m3，Cl2The content is 300mg/m3The nitrogen oxide off-gas is pumped into the oxidation reactor 1 by a vacuum pump, the method comprising:
nitrogen oxide waste gas and air with the volume ratio of 1:4 are fed into an oxidation reactor 1 for oxidation reaction, the temperature of the oxidation reaction is controlled to be less than 30 ℃, the retention time of the oxidation waste gas is 120s, and the effective volume of the oxidation reactor 1 is calculated to be 25m3The oxidation degree of nitrogen oxides in the gas of the oxidation reactor 1 is 75%;
the gas in the oxidation reactor 1 enters a primary absorption tower 4, water is used as primary absorption liquid for absorption, the retention time of the waste gas in the primary absorption tower 4 is controlled to be 20s, the temperature of the spray liquid at the top of the tower is controlled to be 20 ℃, and the spray density is controlled to be 15m3/(m2·h)；
The gas in the primary absorption tower 4 enters a secondary absorption tower 7, hydrogen peroxide solution with the initial concentration of 27.5 wt% is used as secondary absorption liquid for absorption, the retention time of the waste gas in the secondary absorption tower 7 is controlled to be 20s, the temperature of the spray liquid at the top of the tower is controlled to be 40 ℃, and the spray density is 15m3/(m2·h)；
The gas in the secondary absorption tower 7 enters a tertiary absorption tower 10, urea solution with the initial concentration of 25 wt% is used as tertiary absorption liquid for absorption, the retention time of waste gas in the tertiary absorption tower 10 is controlled to be 15s, the temperature of spray liquid at the top of the tower is controlled to be 40 ℃, and the spray density is 15m3/(m2·h)；
After the circulation is established, 5m of nitric acid is discharged through a liquid discharge pipe when the concentration of nitric acid in the primary absorption liquid is more than or equal to 40wt percent3The primary absorption liquid is led into a nitric acid solution storage tank 13 and passes through a return liquidPipe 14 ground 5m3The second absorption liquid is introduced into the upper part of the first absorption tower 4 to be sprayed, and 5m of the second absorption tower 7 is supplemented by a first liquid supplementing pipe3A volume of hydrogen peroxide solution.
NO in gas discharged from the second exhaust pipe of the three-stage absorption towerXThe content is 119mg/m3The HCl content is 52mg/m3，Cl2The content is 30mg/m3All meet the emission standard.
In conclusion, utilize nitrogen oxide waste gas resourceful treatment method that the device went on, based on as the holistic one-level absorption tower of an absorption and second grade absorption tower, regard as one-level absorption liquid with hydrogen peroxide solution as second grade absorption liquid, import into partial second grade absorption liquid through intermittent type nature the upper portion of one-level absorption tower sprays, improves nitric acid concentration in the one-level absorption liquid to more than 40 wt% and carries out recycle, whole journey only need supply corresponding fresh second grade absorption liquid, compare in traditional nitrogen oxide waste gas treatment method, the utility model discloses the waste gas that more is fit for high concentration nitrogen oxide and intermittent type operation operating mode have the advantage that the operation is stable, convenient operation, elasticity are big, do not produce secondary pollutant and guarantee discharge to reach standard; and the urea solution is selected as the tertiary absorption liquid for absorption, and because the urea and the nitrogen oxides generate carbon dioxide, nitrogen and water, the absorbed waste liquid has no salt byproducts, the treatment cost is low, the absorption rate is high, and no secondary pollution is caused.
The applicant states that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and those skilled in the art should understand that any changes or substitutions easily conceivable by those skilled in the art within the technical scope of the present invention are within the protection scope and the disclosure scope of the present invention.
Claims (10)
1. A nitrogen oxide waste gas resource treatment device is characterized by comprising an oxidation reactor, a primary absorption tower and a secondary absorption tower, wherein a nitrogen oxide waste gas inlet and an oxidant inlet are formed in the middle of the oxidation reactor, the top of the oxidation reactor is connected with the lower part of the primary absorption tower through a primary gas inlet pipe, the top of the primary absorption tower is connected with the lower part of the secondary absorption tower through a secondary gas inlet pipe, the bottom of the primary absorption tower is connected with the upper part of the primary absorption tower through a primary absorption liquid pipeline, a primary circulating pump is arranged on the primary absorption liquid pipeline, the bottom of the secondary absorption tower is connected with the upper part of the secondary absorption tower through a secondary absorption liquid pipeline, and a secondary circulating pump is arranged on the secondary absorption liquid pipeline;
the primary absorption liquid pipeline corresponding to the outlet of the primary circulating pump and the secondary absorption liquid pipeline corresponding to the outlet of the secondary circulating pump are connected through a liquid return pipe, and the primary absorption liquid pipeline corresponding to the position between the outlet of the primary circulating pump and the liquid return pipe is connected with a nitric acid solution storage tank through a liquid discharge pipe; and a first liquid supplementing pipe is arranged at the upper part of the secondary absorption tower, and a first exhaust pipe is arranged at the top of the secondary absorption tower.
2. The apparatus for recycling a nitrogen oxide exhaust gas according to claim 1, further comprising a third absorption tower, wherein the top of the second absorption tower is connected to the lower part of the third absorption tower through the first exhaust pipe, the bottom of the third absorption tower is connected to the upper part of the third absorption tower through a third absorption liquid pipe, a third circulation pump is provided on the third absorption liquid pipe, a second solution pipe is provided on the upper part of the third absorption tower, and a second exhaust pipe is provided on the top of the second absorption tower.
3. The apparatus for recycling a nitrogen oxide exhaust gas according to claim 2, wherein the second fluid replacement pipe is provided on the tertiary absorption liquid pipeline corresponding to the outlet of the tertiary circulation pump.
4. The apparatus for recycling a nitrogen oxide off-gas as recited in claim 2, wherein a tertiary cooler is provided in the tertiary absorption liquid line corresponding to the outlet of the tertiary circulation pump.
5. The apparatus for recycling a nitrogen oxide off-gas as recited in claim 1, wherein a primary cooler is provided in said primary absorption liquid line corresponding to an outlet of said primary circulation pump.
6. The apparatus for recycling a nitrogen oxide off-gas as recited in claim 1, wherein a secondary cooler is provided in the secondary absorption liquid line corresponding to an outlet of the secondary circulation pump.
7. The apparatus for recycling a nitrogen oxide exhaust gas according to claim 1, wherein the first fluid replacement pipe is provided on the secondary absorption liquid line corresponding to an outlet of the secondary circulation pump.
8. The apparatus for recycling a nitrogen oxide exhaust gas according to claim 1, wherein a booster fan is provided in the primary intake pipe.
9. The apparatus for resourcefully treating a nitrogen oxide exhaust gas according to claim 1, wherein a cooling coil is provided outside the oxidation reactor.
10. The apparatus for resourceful treatment of nitrogen oxide exhaust gas according to claim 1, wherein an oxidant inlet pipe is provided at the oxidant inlet, and an air supply fan is provided at the oxidant inlet pipe.
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| CN202120780005.6U CN214680967U (en) | 2021-04-16 | 2021-04-16 | Nitrogen oxide waste gas resourceful treatment device |
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