CN108014617B - Method and device for treating concentrated nitrate tail gas through low-temperature ammonia reduction - Google Patents
Method and device for treating concentrated nitrate tail gas through low-temperature ammonia reduction Download PDFInfo
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- CN108014617B CN108014617B CN201711110055.8A CN201711110055A CN108014617B CN 108014617 B CN108014617 B CN 108014617B CN 201711110055 A CN201711110055 A CN 201711110055A CN 108014617 B CN108014617 B CN 108014617B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
- B01D53/1456—Removing acid components
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/76—Gas phase processes, e.g. by using aerosols
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2251/00—Reactants
- B01D2251/20—Reductants
- B01D2251/206—Ammonium compounds
- B01D2251/2062—Ammonia
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Abstract
The invention relates to a method and a device for treating concentrated nitric acid tail gas by low-temperature ammonia reduction, which comprises the following steps: A. waste gas of the concentrated nitrate system is pumped into the circulating tank through ejectors on the first-stage circulating tank and the second-stage circulating tank for cooling and absorption; B. and (4) conveying the waste gas of the circulating tank into a circulating absorption tower through a waste gas collecting tank, and cooling and absorbing magnesium tail water in the absorption tower. C. The absorbed and treated waste gas is heated by a heater and then enters an ammonia reducer to perform catalytic reduction reaction with ammonia on a catalyst, so that residual NOx in the waste gas is completely removed. D. The NOx content in the waste gas from the reducer completely meets the environmental protection requirement and can be directly discharged. The invention has the advantages that: the low-temperature absorption liquid is used for absorbing nitrogen oxides in the tail gas, on one hand, part of low-concentration dilute nitric acid is obtained through absorption, on the other hand, the reaction load of the ammonia reduction catalyst is reduced through absorption, the ammonia consumption of the reduction reaction is reduced, and the service cycle of the catalyst is prolonged. In addition, the heat released by the ammonia reduction reaction can be used for increasing the temperature of the exhaust gas entering the reducer, thereby reducing the consumption of steam and lowering the use cost.
Description
Technical Field
The invention belongs to the technical field of chemical industry, and relates to a method for treating NOx in concentrated nitric acid tail gas by using a low-temperature ammonia selective reduction catalyst to treat NO generated in the production process of concentrated nitric acidXAnd the exhaust gas realizes the purification and emission reduction of the exhaust gas.
Background
The waste gas of tower tail water circulation groove, rare magnesium groove in the thick nitre device of current is direct emission in the design, can't satisfy the environmental protection requirement at present.
1. The optimum conditions for nitrogen oxide absorption are high pressure and low temperature, but the site unorganized discharged waste gas is basically normal pressure, and the input cost is too high if pressurized absorption is realized.
Then, a low-temperature condition is created as far as possible to promote the absorption of the waste gas, so that the waste gas purification purpose is achieved, and when the concentration of the absorption liquid reaches about 20%, the low-concentration acid is recovered to be used by other posts (such as desalination, a sewage treatment system and system circulating liquid replacement).
2. A non-noble metal catalyst series ammonia selective reduction method for removing NOx catalyst ammonia selective catalytic reduction is adopted, and the reaction formula is as follows:
disclosure of Invention
The invention aims to solve the problem of large exhaust emission in the prior art, and provides a method and a device for treating concentrated nitrate tail gas by low-temperature ammonia reduction.
The technical scheme adopted by the invention is as follows:
1. a method for treating NOx in tail gas of a concentrated nitrate device by low-temperature ammonia selective reduction comprises the following steps:
a. waste gas of the rich-NOx system is pumped in from an air inlet of the primary circulating ejector, and the circulating absorption liquid injected by the circulating ejector enters the primary waste gas circulating tank to circularly absorb waste gas containing NOx;
b. the waste gas which is not absorbed in the first-stage waste gas circulation tank enters an air inlet of a second-stage circulation ejector through an emptying pipe, the absorption liquid sprayed by the circulation ejector enters the second-stage waste gas circulation tank to circularly absorb the waste gas, and the absorption liquid is circularly cooled through a cooler in the circulating absorption process;
c. the top of the secondary waste gas circulation tank is used for conveying unabsorbed tail gas to a waste gas collecting tank through an emptying pipe; waste gas of other equipment, such as storage tank emptying waste gas and tank car smoke waste gas, is also connected to a waste gas collecting tank through a pipeline;
d. the waste gas is sent to an absorption tower from an outlet of the waste gas collecting tank by an induced draft fan, the magnesium tail water is used for circulating absorption in the absorption tower, the absorption effect is promoted by adopting cooling water of a cooler for cooling, and the absorption liquid forms 1-5% of dilute nitric acid acidic water;
e. the waste gas from the absorption tower is heated to 180 deg.c in a heater and fed into an ammonia reducer, where ammonia gas is added to regulate the ammonia-nitrogen ratio NH3/NOxThe ratio is controlled to be 1.0-1.1, so that the nitrogen oxides in the waste gas are absorbed and decomposed, and the content of the nitrogen oxides in the decomposed gas is directly discharged at 100 PPm.
2. A tail gas treatment and reduction device of a concentrated nitrate device comprises the following devices:
a. the device comprises a primary waste gas circulation tank and a secondary waste gas circulation tank, wherein the top of each circulation tank is respectively provided with a primary circulation ejector, a secondary circulation ejector and a cooler, each circulation ejector is respectively connected with the bottom of the corresponding waste gas circulation tank to form a circulation jet air exhaust system, the air inlet end of the primary circulation ejector is connected with a waste gas outlet of a concentrated nitrate system, and the top of the primary waste gas circulation tank is provided with an emptying pipe connected to the air inlet end of the secondary circulation jet air ejector;
b. the top of the secondary waste gas circulation tank is provided with an emptying pipe connected to the waste gas collection tank, waste gas of other equipment is connected to the waste gas collection tank through the emptying pipe, and an outlet at the top of the waste gas collection tank is connected with an induced draft fan;
c. and the top of the absorption tower is provided with a vent pipe connected to a heater, and the heater is provided with a vent pipe connected to an ammonia reducer.
The invention has the advantages that:
the first half part of the project is a recovery section, low temperature is used for facilitating absorption reaction, and low-temperature absorption liquid is used for absorbing nitrogen oxides in tail gas, so that on one hand, part of low-concentration dilute nitric acid is obtained through absorption, on the other hand, the reaction load of the ammonia reduction catalyst is reduced through absorption, the ammonia consumption of the reduction reaction is reduced, and the service cycle of the catalyst is prolonged. In addition, the heat released by the ammonia reduction reaction can be used for increasing the temperature of the exhaust gas entering the reducer, thereby reducing the consumption of steam and lowering the use cost.
Description of the drawings:
FIG. 1 is a process flow diagram of the present invention.
Detailed description of the invention
The invention firstly provides a set of tail gas treatment and reduction device for a concentrated nitrate device, which comprises the following devices:
a. the device comprises a primary waste gas circulation tank and a secondary waste gas circulation tank, wherein the top of each circulation tank is respectively provided with a primary circulation ejector, a secondary circulation ejector and a cooler, each circulation ejector is respectively connected with the bottom of the corresponding waste gas circulation tank to form a circulation jet air exhaust system, the air inlet end of the primary circulation ejector is connected with a waste gas outlet of a concentrated nitrate system, and the top of the primary waste gas circulation tank is provided with an emptying pipe connected to the air inlet end of the secondary circulation jet air ejector;
b. the top of the secondary waste gas circulation tank is provided with an emptying pipe connected to the waste gas collection tank, waste gas of other equipment is connected to the waste gas collection tank through the emptying pipe, and an outlet at the top of the waste gas collection tank is connected with an induced draft fan;
c. and the top of the absorption tower is provided with a vent pipe connected to a heater, and the heater is provided with a vent pipe connected to an ammonia reducer.
The invention provides a method for treating tail gas NOx of a concentrated nitrate device by low-temperature ammonia selective reduction, which comprises the following steps:
1. waste gas (the temperature is 40-50 ℃, the normal pressure) of a concentrated nitrate system is pumped in from an air inlet of a primary circulating ejector, the waste gas containing NOx is circularly absorbed along with circulating absorption liquid sprayed by the circulating ejector, the absorption liquid in a circulating groove is dilute nitric acid acidic water with the concentration of 1-5%, the acidic water is circulated in the absorbing groove by a circulating pump, and the temperature is 30-40 ℃;
2. the waste gas which is not absorbed in the first-stage waste gas circulation tank enters an air inlet of a second-stage circulation ejector through an emptying pipe, the absorption liquid sprayed by the circulation ejector enters the second-stage waste gas circulation tank to circularly absorb the waste gas, and the absorption liquid is circularly cooled by a cooler in the circulating absorption process (the temperature is 10-15 ℃, and the pressure is slightly negative);
3. the top of the secondary waste gas circulation tank is used for conveying unabsorbed tail gas to a waste gas collecting tank through an emptying pipe; waste gas of other equipment, such as storage tank emptying waste gas and tank car smog waste gas, is also connected to a waste gas collecting tank through a pipeline (the temperature in the collecting tank is about 30 ℃, and the micro negative pressure is realized);
4. the waste gas is sent to an absorption tower from an outlet of the waste gas collecting tank by an induced draft fan (with the flow rate of 2000-;
5. the waste gas from the absorption tower (mainly the nitrogen oxide gas which is not absorbed by the absorption liquid) enters a heater, is heated to 180 ℃ and is sent into an ammonia reducer for reduction in ammoniaAdding ammonia gas into the reactor, and adjusting the appropriate ammonia-nitrogen ratio (NH)3/NOxThe ratio is controlled to be 1.0-1.1), the nitrogen oxide in the waste gas is absorbed and decomposed, the decomposed gas (the content of the nitrogen oxide in the tail gas after the decomposition reaction is about 100 PPm) is directly discharged, and the water generated by the reduction reaction is gaseous (the reaction is an exothermic reaction, the temperature is 270 ℃ and 300 ℃), so that the concentration of the nitrogen oxide in water does not exist.
Claims (2)
1. A method for treating concentrated nitric acid tail gas by low-temperature ammonia reduction comprises the following steps:
a. waste gas of the rich-NOx system is pumped in from an air inlet of the primary circulating ejector, and the circulating absorption liquid injected by the circulating ejector enters the primary waste gas circulating tank to circularly absorb waste gas containing NOx;
b. the waste gas which is not absorbed in the first-stage waste gas circulation tank enters an air inlet of a second-stage circulation ejector through an emptying pipe, the absorption liquid sprayed by the circulation ejector enters the second-stage waste gas circulation tank to circularly absorb the waste gas, and the absorption liquid is circularly cooled through a cooler in the circulating absorption process;
c. the top of the secondary waste gas circulation tank is used for conveying unabsorbed tail gas to a waste gas collecting tank through an emptying pipe; the storage tank is also connected with an exhaust gas collecting tank through a pipeline;
d. the waste gas is sent to an absorption tower from an outlet of the waste gas collecting tank by an induced draft fan, the magnesium tail water is used for circulating absorption in the absorption tower, the absorption effect is promoted by adopting cooling water of a cooler for cooling, and the absorption liquid forms 1-5% of dilute nitric acid acidic water;
e. the waste gas from the absorption tower is heated to 180 deg.c in a heater and fed into an ammonia reducer, where ammonia gas is added to regulate the ammonia-nitrogen ratio NH3the/NOx ratio is controlled to be 1.0-1.1, so that the nitrogen oxides in the waste gas are absorbed and decomposed, and the content of the nitrogen oxides in the decomposed gas is directly discharged at 100 PPm.
2. A device for realizing a method for treating concentrated nitric acid tail gas by low-temperature ammonia reduction comprises the following devices:
the device comprises a first-stage waste gas circulating tank and a second-stage waste gas circulating tank, wherein the top of each circulating tank is respectively provided with a first-stage circulating ejector, a second-stage circulating ejector and a cooler, each circulating ejector is respectively connected with the bottom of the corresponding waste gas circulating tank to form a circulating injection air exhaust system, the air inlet end of the first-stage circulating ejector is connected with a waste gas outlet of a saltpeter system, and the top of the first-stage waste gas circulating tank is provided with an emptying pipe connected to the air inlet end of the second-stage circulating injection;
b, a waste gas collecting tank, wherein an emptying pipe is arranged at the top of the secondary waste gas circulating tank and connected to the waste gas collecting tank, the storage tank empties the waste gas, the tank car smoke waste gas is connected to the waste gas collecting tank through the emptying pipe, and an outlet at the top of the waste gas collecting tank is connected with an induced draft fan;
and c, a waste gas absorption tower, wherein the outlet of the induced draft fan is connected to the bottom of the absorption tower, the absorption tower is provided with a circulating pump and a cooler, the top of the absorption tower is provided with a vent pipe connected to a heater, and the heater is provided with a vent pipe connected to an ammonia reducer.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711110055.8A CN108014617B (en) | 2017-11-12 | 2017-11-12 | Method and device for treating concentrated nitrate tail gas through low-temperature ammonia reduction |
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| CN201711110055.8A CN108014617B (en) | 2017-11-12 | 2017-11-12 | Method and device for treating concentrated nitrate tail gas through low-temperature ammonia reduction |
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| CN108014617A CN108014617A (en) | 2018-05-11 |
| CN108014617B true CN108014617B (en) | 2020-10-09 |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1425487A (en) * | 2003-01-28 | 2003-06-25 | 南化集团研究院 | Method for single stage circulation absorbing nitrogen oxide intail gas by dilute nitric acid |
| CN102233234A (en) * | 2011-06-24 | 2011-11-09 | 北京中兵北方环境科技发展有限责任公司 | Device and method for purifying waste gas containing high-concentration nitrogen oxide (NOx) |
| CN103537178A (en) * | 2013-09-26 | 2014-01-29 | 浙江优创材料科技股份有限公司 | Treatment system and method of nitric oxide in nitrotoluene nitric acid oxidation tail gas |
| CN103920384A (en) * | 2014-04-25 | 2014-07-16 | 兰州大学 | Equipment for absorbing high-concentration nitric oxides by adopting normal-pressure process |
| CN104190225A (en) * | 2014-09-27 | 2014-12-10 | 安徽金禾实业股份有限公司 | Recovery and purifying method and device of nitric acid tail gas |
-
2017
- 2017-11-12 CN CN201711110055.8A patent/CN108014617B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1425487A (en) * | 2003-01-28 | 2003-06-25 | 南化集团研究院 | Method for single stage circulation absorbing nitrogen oxide intail gas by dilute nitric acid |
| CN102233234A (en) * | 2011-06-24 | 2011-11-09 | 北京中兵北方环境科技发展有限责任公司 | Device and method for purifying waste gas containing high-concentration nitrogen oxide (NOx) |
| CN103537178A (en) * | 2013-09-26 | 2014-01-29 | 浙江优创材料科技股份有限公司 | Treatment system and method of nitric oxide in nitrotoluene nitric acid oxidation tail gas |
| CN103920384A (en) * | 2014-04-25 | 2014-07-16 | 兰州大学 | Equipment for absorbing high-concentration nitric oxides by adopting normal-pressure process |
| CN104190225A (en) * | 2014-09-27 | 2014-12-10 | 安徽金禾实业股份有限公司 | Recovery and purifying method and device of nitric acid tail gas |
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