CN115920627A - Industrial furnace denitration system and method - Google Patents
Industrial furnace denitration system and method Download PDFInfo
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- CN115920627A CN115920627A CN202210605869.3A CN202210605869A CN115920627A CN 115920627 A CN115920627 A CN 115920627A CN 202210605869 A CN202210605869 A CN 202210605869A CN 115920627 A CN115920627 A CN 115920627A
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- 238000000034 method Methods 0.000 title claims abstract description 33
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims abstract description 181
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 94
- 239000003546 flue gas Substances 0.000 claims abstract description 94
- 229910021529 ammonia Inorganic materials 0.000 claims abstract description 60
- 238000002156 mixing Methods 0.000 claims abstract description 50
- 239000003054 catalyst Substances 0.000 claims abstract description 39
- 238000001704 evaporation Methods 0.000 claims abstract description 24
- 230000008020 evaporation Effects 0.000 claims abstract description 24
- 238000006243 chemical reaction Methods 0.000 claims abstract description 23
- 238000005259 measurement Methods 0.000 claims abstract description 15
- 238000005507 spraying Methods 0.000 claims abstract description 14
- 239000007789 gas Substances 0.000 claims abstract description 9
- 238000010438 heat treatment Methods 0.000 claims abstract description 9
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 55
- 239000003638 chemical reducing agent Substances 0.000 claims description 19
- 238000002347 injection Methods 0.000 claims description 12
- 239000007924 injection Substances 0.000 claims description 12
- 238000007865 diluting Methods 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 5
- 238000010531 catalytic reduction reaction Methods 0.000 claims description 5
- 239000001301 oxygen Substances 0.000 claims description 5
- 229910052760 oxygen Inorganic materials 0.000 claims description 5
- 239000002918 waste heat Substances 0.000 claims description 5
- 230000009471 action Effects 0.000 claims description 4
- 230000008016 vaporization Effects 0.000 claims description 4
- 238000009834 vaporization Methods 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 6
- 238000010790 dilution Methods 0.000 description 7
- 239000012895 dilution Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 6
- 239000005977 Ethylene Substances 0.000 description 6
- 230000007774 longterm Effects 0.000 description 5
- 238000005336 cracking Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000004880 explosion Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000006200 vaporizer Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 229910010413 TiO 2 Inorganic materials 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- WKXHZKXPFJNBIY-UHFFFAOYSA-N titanium tungsten vanadium Chemical group [Ti][W][V] WKXHZKXPFJNBIY-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention provides a denitration system and a denitration method for an industrial furnace, wherein the system comprises the industrial furnace, a measurement and control system, a liquid ammonia pump and a flowmeter; the industrial furnace comprises an industrial furnace, a flue, an ammonia spraying part, a denitration reaction section, a catalyst bed layer, a first convection tube bundle, a second convection tube bundle, a third convection tube bundle, an ammonia evaporation and pre-heating device, a first convection tube bundle, a denitration reaction section, a second convection tube bundle and a catalyst bed layer, wherein the first convection tube bundle, the denitration reaction section, the third convection tube bundle and the ammonia evaporation and pre-heating device are sequentially arranged in the flue of the industrial furnace from bottom to top; a mixing section pipeline is arranged outside the industrial furnace; the liquid ammonia pump is communicated with the inlet of the ammonia evaporation and pre-heater through a liquid ammonia pipeline by a flow meter, and the outlet of the ammonia evaporation and pre-heater is communicated with the inlet of the mixing section pipeline by a pipeline; a flue gas outlet of the industrial furnace is communicated with an inlet of a mixing section pipeline through a flue gas pipeline; the outlet of the mixing section pipeline is communicated with the ammonia spraying part; the measurement and control system is respectively electrically connected with the liquid ammonia pump and the flowmeter. The invention can reduce the occupied area of the whole system, save the equipment investment and the energy consumption in the whole operation period, and can realize the standard emission of tail gas.
Description
Technical Field
The invention relates to a denitration system and a denitration method for an industrial furnace, and belongs to the technical field of flue gas denitration.
Background
Currently, the emission requirements of various industries on atmospheric pollutants are more and more strict. Among them, the control of nitrogen oxides is the focus of the control of atmospheric pollutants. The selective catalytic reduction method (SCR denitration) is the most widely applied flue gas denitration technology internationally at present. The technology mainly adopts ammonia (NH) 3 ) As reducing agent, the reducing agent ammonia (NH) 3 ) With NO preferentially under the action of catalyst X Reduction reaction is carried out to generate nitrogen and water (2 NO) which have NO influence on the atmosphere 2 +4NH 3 +O 2 →3N 2 +6H 2 O；4NO+4NH 3 +O 2 →4N 2 +6H 2 O). The method has the advantages of no by-product, high removal efficiency, reliable operation and the like.
At present, the SCR denitration system in various industrial furnaces mostly adopts an independent denitration module. In the system, a vaporizer and a mixer of reducing agent liquid ammonia are arranged in a separate space outside the industrial furnace, wherein the vaporizer of reducing agent liquid ammonia needs to provide steam and the like outside as a heat source to provide heat for vaporizing liquid ammonia; the mixer is arranged near the carburetor, and fresh air is provided by a separate fan to be mixed and diluted with the reducing agent ammonia, and when the fresh air is used for mixing and diluting the reducing agent ammonia, the dilution ratio needs to avoid the explosion limit of the ammonia. The dilution air is mixed with the reducing agent ammonia and then sent to the pipeline of the ammonia injection part, and heat tracing is needed to avoid ammonia liquefaction in the pipeline. In addition, an ammonia injection grid in the denitration module, a catalyst bed layer is arranged in one module, a full-air flue is arranged between the two modules, ammonia is uniformly mixed with flue gas through the ammonia injection grid after being injected for a certain distance, and then the ammonia passes through the catalyst bed layer to remove nitrogen oxides, so that the environmental protection requirement is met.
However, the SCR denitration systems in various industrial furnaces currently have the following disadvantages:
1) The occupied area is large, and the conveying pipeline is long;
2) The required amount of dilution air is large, and a vaporizer, heat tracing, cold air and the like can cause part of extra energy consumption;
3) After the ammonia is sprayed in by the ammonia spraying part, the ammonia needs to be uniformly mixed after a long distance, the space is vacant, so that the space waste is caused, and the material quantity and the investment are increased; and
4) The built industrial furnace can not meet the arrangement requirement, and the engineering quantity is large during the environmental protection reconstruction.
Therefore, it has become an urgent technical problem to be solved in the art to provide a novel denitration system and method for an industrial furnace.
Disclosure of Invention
In order to solve the above disadvantages and shortcomings, an object of the present invention is to provide a denitration system for an industrial furnace.
The invention also aims to provide a denitration method for the industrial furnace.
In order to achieve the above object, in one aspect, the present invention provides an industrial furnace denitration system, wherein the industrial furnace denitration system comprises: the system comprises an industrial furnace, a measurement and control system, a liquid ammonia pump and a flowmeter; the industrial furnace comprises an industrial furnace, a flue, an ammonia spraying part, a first convection tube bundle, a denitration reaction section, a third convection tube bundle, an ammonia evaporation and pre-heating device, a catalyst bed layer and a catalyst bed layer, wherein the first convection tube bundle, the denitration reaction section, the third convection tube bundle and the ammonia evaporation and pre-heating device are sequentially arranged in the flue of the industrial furnace from bottom to top; a mixing section pipeline is arranged outside the industrial furnace;
the liquid ammonia pump is communicated with the inlet of the ammonia evaporation and pre-heater through a liquid ammonia pipeline via a flow meter, and the outlet of the ammonia evaporation and pre-heater is communicated with the inlet of the mixing section pipeline through a pipeline; a flue gas outlet of the industrial furnace is communicated with an inlet of the mixing section pipeline through a flue gas pipeline; the outlet of the mixing section pipeline is communicated with the ammonia spraying part;
and the measurement and control system is electrically connected with the liquid ammonia pump and the flowmeter respectively.
In the flue of the industrial furnace, the first convection bank and the second convection bank are respectively arranged in front of and behind (or below and above) the ammonia spraying part, and the second convection bank and the third convection bank are respectively arranged in front of and behind (or below and above) the catalyst bed layer, so that the optimal mixing effect is achieved, and the space for arranging other mixing parts can be saved.
As a specific embodiment of the denitration system of the industrial furnace, the system further comprises an induced draft fan, and a flue gas outlet of the industrial furnace is communicated with an inlet of the mixing section pipeline through a flue gas pipeline via the induced draft fan.
As a specific embodiment of the above denitration system for the industrial furnace, the system further comprises a backflow baffle, wherein a flue gas outlet of the industrial furnace is communicated with an inlet of the mixing section pipeline through a flue gas pipeline via a draught fan and the backflow baffle;
the measurement and control system is electrically connected with the backflow baffle plate and used for measuring the flow of the backflow flue gas.
The backflow baffle arranged on the flue gas pipeline is used for controlling the amount of backflow flue gas so as to dilute ammonia gas in a proper proportion.
As a specific embodiment of the above-mentioned denitration system for an industrial furnace, the system further includes a chimney, and the flue gas outlet of the industrial furnace is communicated with the inlet of the chimney through a flue gas pipeline.
As a specific embodiment of the denitration system of the industrial furnace, the denitration system further comprises a chimney, and a flue gas outlet of the industrial furnace is communicated with an inlet of the chimney through a flue gas pipeline via an induced draft fan.
As a specific embodiment of the above-mentioned denitration system for industrial furnaces, in the denitration reaction section, a blending member is further disposed between the second convection tube bundle and the catalyst bed layer.
The mixing component is used for further mixing and distributing the mixed flue gas before entering the catalyst bed layer so as to enable the reducing agent and the flue gas to be mixed more uniformly. In addition, the structure and the like of the mixing component are not particularly required, and the mixing component can be designed into various single structural forms according to the detailed structure in the industrial furnace, and can also be designed into various combined structural forms. For example, in some embodiments of the present invention, the blending component may be one or a combination of a folded plate type, a spiral type, a blade type, and the like.
In an embodiment of the denitration system of an industrial furnace, the ammonia evaporation and preheater is located at the tail of the flue of the industrial furnace.
In an embodiment of the denitration system of the industrial furnace, the ammonia injection component is an ammonia injection grid.
As a specific embodiment of the above-mentioned denitration system for an industrial furnace, the measurement and control system includes a nitrogen oxide content measuring instrument, an oxygen content measuring instrument, a flow measuring instrument, and the like, and can calculate and control the liquid ammonia pump to inject a certain amount of liquid ammonia reducing agent as required in real time.
The nitrogen oxide content measuring instrument and the oxygen content measuring instrument in the measurement and control system are further respectively arranged in front of (or below or above) the catalyst bed layer in the denitration reaction section so as to be used for measuring the nitrogen oxide content and the oxygen content before and after the catalytic reduction reaction.
On the other hand, the invention also provides an industrial furnace denitration method, wherein the industrial furnace denitration method is realized by using the industrial furnace denitration system, and the industrial furnace denitration system comprises the following steps:
(1) The waste heat of the tail flue gas of the industrial furnace is utilized to vaporize and preheat the liquid ammonia reducing agent in an ammonia evaporation and preheater;
(2) Mixing and diluting the ammonia gas preheated in the step (1) and tail flue gas refluxed by the industrial furnace in a mixing section pipeline to obtain mixed gas;
(3) And enabling the mixed gas to enter a denitration reaction section through an ammonia spraying part and uniformly mix with flue gas generated by an industrial furnace to obtain mixed flue gas, enabling the mixed flue gas to pass through a catalyst bed layer, and enabling nitrogen oxides in the mixed flue gas and ammonia gas to perform catalytic reduction reaction under the action of a catalyst to remove the nitrogen oxides and enable the treated flue gas to reach the standard and be discharged.
As a specific embodiment of the denitration method for the industrial furnace, in the step (1), the temperature of the tail flue gas of the industrial furnace is 100-190 ℃.
As a specific embodiment of the above denitration method for an industrial furnace according to the present invention, in the step (1), the ammonia gas obtained after vaporization is preheated to 70-180 ℃.
As a specific embodiment of the denitration method for the industrial furnace, in the step (2), the volume ratio of the tail flue gas refluxed by the industrial furnace to the ammonia gas preheated in the step (1) is 10.
As a specific embodiment of the above denitration method for the industrial furnace, in the step (3), the mixed gas enters the denitration reaction section through the ammonia spraying component and is mixed with the flue gas generated by the industrial furnace, and then the mixed flue gas continuously passes through the second convection bank, the mixing component and other mixing components upwards in the flue, so that the ammonia gas and the flue gas are mixed more uniformly.
In the invention, the catalyst used in the catalyst bed layer is a conventional denitration catalyst used in the field, and can be reasonably selected according to the actual field operation condition, so long as the ammonia gas and the nitrogen oxide in the flue gas can react under the catalysis of the catalyst to remove the nitrogen oxide in the flue gas. For example, in some embodiments of the present invention, the catalyst may be a plate catalyst, a honeycomb catalyst, a corrugated plate catalyst, a particle catalyst, or the like, wherein the effective component of the catalyst is TiO 2 、V 2 O 5 And WO 3 And the like.
The industrial furnace denitration system and the industrial furnace denitration method provided by the invention have the following beneficial technical effects:
1) The waste heat of the flue gas at the tail part of the industrial furnace is adopted to gasify the liquid ammonia and preheat the ammonia gas to the temperature close to that of the flue gas at the tail part, and the operation can save energy.
2) The reducing agent, namely ammonia gas, is diluted by adopting the flue gas at the tail of the industrial furnace, so that the explosion risk of ammonia-air mixture is avoided, the ammonia gas is safer than the ammonia gas diluted by adopting air, and the application range of the dilution ratio is wider; in addition, the temperature of the tail flue gas of the industrial furnace is generally 100-190 ℃, and compared with the method for diluting ammonia gas by adopting fresh air, the method for diluting ammonia gas by adopting the tail flue gas of the industrial furnace is more energy-saving in long-term operation; in addition, the tail flue gas of the industrial furnace is adopted to dilute the ammonia gas, so that two independently arranged dilution fans can be avoided, and the investment and the occupied area can be reduced; and finally, tail flue gas of the industrial furnace is adopted to dilute the ammonia gas, the tail flue gas with higher temperature can prevent the mixture from being liquefied in a mixing section pipeline, and the mixing section pipeline does not need to be subjected to heat tracing, so that the investment is saved, and the energy consumption for long-term operation is further saved.
3) And a second convection tube bundle is arranged in the denitration reaction section and between the ammonia spraying part and the catalyst bed layer, so that the mixed flue gas before entering the catalyst bed layer can be further mixed and distributed, the reducing agent and the flue gas in the mixed flue gas are more uniformly mixed, the inner space of the denitration reaction section can be fully utilized by the design, and the equipment investment is saved.
In conclusion, compared with the SCR denitration systems in various industrial furnaces at present, the denitration system of the industrial furnace is designed in an integrated manner, so that the occupied area of the whole system can be reduced, the equipment investment is saved, the energy consumption in the whole operation period is saved, the tail gas can be discharged up to the standard, and the problem of difficult arrangement of the environmental protection modification project of the industrial furnace is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a denitration system of an industrial furnace provided in embodiment 1 of the present invention.
The main reference numbers illustrate:
1. an industrial furnace;
21. a first convective bank;
22. a second convective bank of tubes;
23. a third convection bank;
3. an ammonia injection grid;
4. a catalyst bed layer;
5. a mixing section pipeline;
6. a flue gas duct;
7. a reflux baffle;
8. ammonia evaporation and pre-heater;
9. a liquid ammonia line;
10. a measurement and control system;
11. a liquid ammonia pump;
12. a denitration reaction section;
13. a chimney;
14. a flow meter;
15. an induced draft fan;
16. a blending component.
Detailed Description
It should be noted that the term "comprises/comprising" and any variations thereof in the description and claims of this invention and the above-described drawings is intended to cover non-exclusive inclusions, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In the present invention, the terms "upper", "lower", "inner", "outer", "center", "front", and "rear" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings. These terms are used primarily to better describe the invention and its embodiments and are not intended to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation.
Moreover, some of the above terms may be used in other meanings besides orientation or positional relationship, for example, the term "upper" may also be used in some cases to indicate a certain attaching or connecting relationship. The specific meanings of these terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
Furthermore, the terms "disposed" and "connected" should be interpreted broadly. For example, "connected" may be a fixed connection, a detachable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.
The "ranges" disclosed herein are given as lower and upper limits. There may be one or more lower limits, and one or more upper limits, respectively. The given range is defined by the selection of a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges defined in this manner are combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, ranges of 60-120 and 80-110 are listed for particular parameters, with the understanding that ranges of 60-110 and 80-120 are also contemplated. Further, if the minimum range values listed are 1 and 2 and the maximum range values listed are 3,4 and 5, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.
In the present invention, unless otherwise stated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0 to 5" indicates that all real numbers between "0 to 5" have been listed throughout this disclosure, and "0 to 5" is only a shorthand representation of the combination of these numbers.
In the present invention, all the embodiments and preferred embodiments mentioned in the present invention may be combined with each other to form a new technical solution, if not specifically stated.
In the present invention, all the technical features mentioned in the present invention and preferred features may be combined with each other to form a new technical solution, if not specifically stated.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. The following described embodiments are some, but not all embodiments of the present invention, and are merely illustrative of the present invention and should not be construed as limiting the scope of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are conventional products which are not indicated by manufacturers and are commercially available.
Example 1
The embodiment provides a denitration system of an industrial furnace, the structural schematic diagram of which is shown in fig. 1, and as can be seen from fig. 1, the system comprises:
the system comprises an industrial furnace 1, a measurement and control system 10, a liquid ammonia pump 11, a chimney 13, a flow meter 14 and an induced draft fan 15; the industrial furnace comprises an industrial furnace 1, a flue, an ammonia evaporation and pre-heating device 8, a first convection tube bundle 21, a denitration reaction section 12, a third convection tube bundle 23 and an ammonia evaporation and pre-heating device 8, wherein the first convection tube bundle 21, the denitration reaction section 12, the third convection tube bundle 23 and the ammonia evaporation and pre-heating device 8 are sequentially arranged in the flue of the industrial furnace 1 from bottom to top, an ammonia injection grid 3, a second convection tube bundle 22, a mixing component 16 and a catalyst bed layer 4 are sequentially arranged in the denitration reaction section 12 from bottom to top, and the mixing component 16 is of a folded plate type structure; a mixing section pipeline 5 is arranged outside the industrial furnace 1;
the liquid ammonia pump 11 is communicated with the inlet of the ammonia evaporation and pre-heater 8 through a liquid ammonia pipeline 9 and a flow meter 14, and the outlet of the ammonia evaporation and pre-heater 8 is communicated with the inlet of the mixing section pipeline 5 through a pipeline; a flue gas outlet of the industrial furnace 1 is communicated with an inlet of the mixing section pipeline 5 through a flue gas pipeline 6 sequentially by an induced draft fan 15 and a reflux baffle 7; the outlet of the mixing section pipeline 5 is communicated with the ammonia injection grid 3;
the flue gas outlet of the industrial furnace 1 is communicated with the inlet of the chimney 13 through a flue gas pipeline 6 and an induced draft fan 15;
the measurement and control system 10 is respectively electrically connected with the backflow baffle 7, the liquid ammonia pump 11 and the flowmeter 14, and the measurement and control system 10 comprises a nitrogen oxide content measuring instrument, an oxygen content measuring instrument, a flow measuring instrument and the like.
Example 2
The embodiment provides an industrial furnace denitration method, which is realized by using the industrial furnace denitration system provided in embodiment 1, wherein the method comprises the following specific steps:
(1) A liquid ammonia pump is used for conveying a liquid ammonia reducing agent into an ammonia evaporation and preheater, and waste heat of tail flue gas (the temperature is about 100 ℃) of an industrial furnace is used for vaporizing the liquid ammonia reducing agent in the ammonia evaporation and preheater and preheating the liquid ammonia reducing agent to about 100 ℃;
(2) Mixing and diluting tail flue gas refluxed by the industrial furnace and ammonia gas preheated in the step (1) in a mixing section pipeline according to the volume ratio of the tail flue gas to the ammonia gas to be about 200;
(3) Enabling the mixed gas to enter a denitration reaction section through an ammonia spraying part and to be mixed with flue gas generated by an industrial furnace, then enabling the mixed flue gas to continuously upwards pass through mixing parts such as a second convection tube bundle and a mixing part in a flue so as to enable ammonia gas and the flue gas to be mixed more uniformly and obtain uniformly mixed flue gas, enabling the uniformly mixed flue gas to pass through a catalyst bed layer, and enabling nitrogen oxides in the mixed flue gas to be subjected to catalytic reduction reaction with the ammonia gas under the action of a catalyst so as to remove the nitrogen oxides and enable the treated flue gas to reach the standard and be discharged;
wherein the catalyst is a vanadium-tungsten-titanium system honeycomb catalyst, and the effective component of the catalyst is TiO 2 、V 2 O 5 And WO 3 。
The denitration system and method of the industrial furnace provided by the embodiment 1 and the embodiment 2 of the invention are applied to a certain ethylene plant in Lanzhou, namely, an ethylene cracking furnace is additionally arranged in the ethylene plant, and the ethylene cracking furnace is equivalent to the industrial furnace in the invention.
Wherein, the flue gas volume of the ethylene cracking furnace is 126717kg/hr, and the main components of the flue gas comprise: 2v% of 2 、72v％N 2 、18v％H 2 O and 8v% CO 2 And the temperature of the flue gas outlet is 120 ℃. The nitrogen oxide content is 120mg/Nm in long-term operation 3 Under some short-term operation conditions, the content of nitrogen oxides can reach 280mg/Nm 3 。
Wherein, the flow rate of the returned tail flue gas is 600-800kg/hr, the injection amount of the reducing agent ammonia is about 3-4kg/hr, and the injection amount can be dynamically adjusted according to the actual detection condition.
In the application process, after denitration, the concentration of nitrogen oxides in all working conditions is less than 40mg/Nm 3 Therefore, the scheme provided by the invention can obviously reduce the concentration of the nitrogen oxide in the smoke.
In addition, compared with the actual operation data of the conventional ethylene cracking furnace in the field, the system and the method provided by the invention do not need to adopt electric tracing to heat and preserve the temperature of the pipeline at the mixing section, and do not need to adopt air (the annual average temperature in Lanzhou city is 11.4 ℃) to dilute ammonia gas. By only two improvements, 30100KWh can be saved, 16999kg of fuel gas can be saved, and about 47 tons of carbon dioxide can be reduced.
The industrial furnace denitration system and the industrial furnace denitration method provided by the embodiment of the invention have the following beneficial technical effects:
1) The waste heat of the flue gas at the tail part of the industrial furnace is adopted to gasify the liquid ammonia and preheat the ammonia gas to the temperature close to that of the flue gas at the tail part, and the operation can save energy.
2) The reducing agent, namely ammonia gas, is diluted by adopting the flue gas at the tail of the industrial furnace, so that the explosion risk of ammonia-air mixture is avoided, the ammonia-air mixture is safer than the ammonia-air mixture diluted by adopting air, and the application range of the dilution ratio is wider; in addition, the temperature of the tail flue gas of the industrial furnace is generally 100-190 ℃, and compared with the method for diluting ammonia gas by adopting fresh air, the method for diluting ammonia gas by adopting the tail flue gas of the industrial furnace is more energy-saving in long-term operation; in addition, the tail flue gas of the industrial furnace is adopted to dilute the ammonia gas, so that two independently arranged dilution fans can be avoided, and the investment and the occupied area can be reduced; and finally, tail flue gas of the industrial furnace is adopted to dilute the ammonia gas, the tail flue gas with higher temperature can prevent the mixture from liquefying in a mixing section pipeline, and heat tracing of the mixing section pipeline is not needed, so that the investment is saved, and the energy consumption for long-term operation is further saved.
3) And a second convection tube bundle is arranged in the denitration reaction section and between the ammonia spraying part and the catalyst bed layer, so that the mixed flue gas before entering the catalyst bed layer can be further mixed and distributed, the reducing agent and the flue gas in the mixed flue gas are more uniformly mixed, the inner space of the denitration reaction section can be fully utilized by the design, and the equipment investment is saved.
In conclusion, compared with the SCR denitration systems in various industrial furnaces at present, the industrial furnace denitration system is designed in an integrated manner, so that the occupied area of the whole system can be reduced, the equipment investment is saved, the energy consumption in the whole operation period is saved, the tail gas can reach the standard and the problem of difficult arrangement of the industrial furnace environmental protection modification project is solved.
The above description is only exemplary of the invention and should not be taken as limiting the scope of the invention, so that the invention is intended to cover all modifications and equivalents of the embodiments described herein. In addition, the technical features and the technical inventions of the present invention, the technical features and the technical inventions, and the technical inventions can be freely combined and used.
Claims (13)
1. An industrial furnace denitration system, characterized in that, industrial furnace denitration system includes: the system comprises an industrial furnace, a measurement and control system, a liquid ammonia pump and a flowmeter; the industrial furnace comprises an industrial furnace, a flue, an ammonia spraying part, a denitration reaction section, a catalyst bed layer, a first convection tube bundle, a second convection tube bundle, a third convection tube bundle, an ammonia evaporation and pre-heating device, a first convection tube bundle, a denitration reaction section, a second convection tube bundle and a catalyst bed layer, wherein the first convection tube bundle, the denitration reaction section, the third convection tube bundle and the ammonia evaporation and pre-heating device are sequentially arranged in the flue of the industrial furnace from bottom to top; a mixing section pipeline is arranged outside the industrial furnace;
the liquid ammonia pump is communicated with the inlet of the ammonia evaporation and preheater through a liquid ammonia pipeline via a flow meter, and the outlet of the ammonia evaporation and preheater is communicated with the inlet of the mixing section pipeline through a pipeline; the flue gas outlet of the industrial furnace is communicated with the inlet of the mixing section pipeline through a flue gas pipeline; the outlet of the mixing section pipeline is communicated with the ammonia spraying part;
and the measurement and control system is electrically connected with the liquid ammonia pump and the flowmeter respectively.
2. The industrial furnace denitration system of claim 1, further comprising an induced draft fan, wherein a flue gas outlet of the industrial furnace is communicated with an inlet of the mixing section pipeline through a flue gas pipeline via the induced draft fan.
3. The denitration system of the industrial furnace according to claim 2, further comprising a backflow baffle, wherein a flue gas outlet of the industrial furnace is communicated with an inlet of the mixing section pipeline through a flue gas pipeline via a draught fan and the backflow baffle;
the measurement and control system is electrically connected with the backflow baffle.
4. The denitration system of the industrial furnace according to claim 1, further comprising a chimney, wherein the flue gas outlet of the industrial furnace is communicated with the inlet of the chimney through a flue gas pipeline.
5. The denitration system of the industrial furnace according to claim 2, further comprising a chimney, wherein the flue gas outlet of the industrial furnace is communicated with the inlet of the chimney through a flue gas pipeline via an induced draft fan.
6. The industrial furnace denitration system of claim 1, wherein a blending member is further disposed between the second convection tube bundle and the catalyst bed in the denitration reaction section.
7. The denitration system of an industrial furnace according to any one of claims 1 to 6, wherein the ammonia evaporation and preheater is located at the tail of a flue of the industrial furnace.
8. The denitration system of the industrial furnace according to any one of claims 1 to 6, wherein the ammonia injection member is an ammonia injection grid.
9. The industrial furnace denitration system of any one of claims 1 to 6, wherein the measurement and control system comprises a nitrogen oxide content measuring instrument, an oxygen content measuring instrument and a flow measuring instrument.
10. An industrial furnace denitration method, which is implemented by using the industrial furnace denitration system according to any one of claims 1 to 9, comprising:
(1) The waste heat of the tail flue gas of the industrial furnace is utilized to vaporize and preheat the liquid ammonia reducing agent in an ammonia evaporation and preheater;
(2) Mixing and diluting the ammonia gas preheated in the step (1) and tail flue gas refluxed by the industrial furnace in a mixing section pipeline to obtain mixed gas;
(3) And enabling the mixed gas to enter a denitration reaction section through an ammonia spraying part and uniformly mixing with flue gas generated by an industrial furnace to obtain mixed flue gas, and enabling the mixed flue gas to pass through a catalyst bed layer, so that nitric oxide in the mixed flue gas and ammonia gas are subjected to catalytic reduction reaction under the action of a catalyst to remove the nitric oxide and enable the treated flue gas to reach the standard and be discharged.
11. The denitration method for the industrial furnace according to claim 10, wherein in the step (1), the temperature of the tail flue gas of the industrial furnace is 100-190 ℃.
12. The denitration method for the industrial furnace according to claim 10 or 11, wherein in the step (1), the ammonia gas obtained after the vaporization is preheated to 70-180 ℃.
13. The denitration method for the industrial furnace according to claim 10 or 11, wherein in the step (2), the volume ratio of tail flue gas returned by the industrial furnace to ammonia gas preheated in the step (1) is 10.
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