CN109464899B - SNCR denitration system applied to small boiler - Google Patents
SNCR denitration system applied to small boiler Download PDFInfo
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- CN109464899B CN109464899B CN201811438213.7A CN201811438213A CN109464899B CN 109464899 B CN109464899 B CN 109464899B CN 201811438213 A CN201811438213 A CN 201811438213A CN 109464899 B CN109464899 B CN 109464899B
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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
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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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
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/77—Liquid phase processes
- B01D53/79—Injecting reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
Abstract
The invention relates to an SNCR (selective non-catalytic reduction) denitration system applied to a small boiler, which relates to the technical field of flue gas denitration, and the denitration efficiency is greatly reduced because a reducing agent sprayed into a boiler often cannot react with NOx under a proper temperature window due to large temperature fluctuation of a denitration reaction zone in the boiler. The scheme comprises a boiler, wherein an open fire area is arranged in the boiler; a reducing agent liquid inlet piece penetrates through the peripheral wall of the boiler, the open fire zone sequentially comprises an open fire front section and an open fire tail section along the flow direction of flue gas, and the reducing agent liquid inlet piece is connected with the open fire tail section; a liquid storage tank and a gas storage tank are arranged outside the boiler, urea solution is stored in the liquid storage tank, a reducing agent liquid inlet piece is connected with the liquid storage tank, and the reducing agent liquid inlet piece is connected with the gas storage tank. Through spouting the urea into the open flame tail section to improve denitration efficiency.
Description
Technical Field
The invention relates to the technical field of flue gas denitration, in particular to an SNCR (selective non catalytic reduction) denitration system applied to a small boiler.
Background
Selective non-catalytic reduction (SNCR) refers to the reduction of nitrogen oxides in flue gas to harmless nitrogen and water by spraying a reducing agent within a "temperature window" suitable for denitration reaction without the action of a catalyst. The technology generally adopts ammonia, urea or hydroammonia sprayed in a furnace as a reducing agent to reduce NOx, and the reducing agent only reacts with NOx in the flue gas and does not generally react with oxygen.
Wherein, since the process does not use a catalyst, the reducing agent must be added in a high temperature zone (suitable temperature window).
However, in the medium-and small-sized boilers, the temperature fluctuation in the interior thereof is relatively large, and the temperature fluctuation in the denitration reaction zone (the zone where the reducing agent is injected into the furnace) in the furnace is also relatively large. The reason is that: 1. the steam consumption of the small and medium-sized industrial boilers is determined by the operation load of the single plant in unit time period, and the operation load is always changed along with the change of the working time period; for example, it is possible that the plant needs to be flushed in the morning during this period, resulting in a large increase in the amount of steam required, and therefore the boiler continues to operate at a high load and its internal temperature will be high; by the afternoon or off-season, the steam demand decreases, the boiler starts to operate at a low load, and its internal temperature will be lower. 2. Large boilers are generally used for steam supply in a thermal power plant or an entire industrial park, and the load of each time period is relatively stable every day, which results in relatively stable temperature variation in the boiler.
The great temperature fluctuation of the denitration reaction zone in the furnace leads to that the reducing agent sprayed into the furnace can not react with NOx under a proper temperature window, thus greatly reducing the denitration efficiency.
Disclosure of Invention
The invention aims to provide an SNCR (selective non-catalytic reduction) denitration system applied to a small boiler, which improves the denitration efficiency by spraying urea into an open fire tail section.
The above object of the present invention is achieved by the following technical solutions:
an SNCR denitration system applied to a small boiler comprises a boiler, wherein an open fire area is arranged in the boiler; a reducing agent liquid inlet piece penetrates through the peripheral wall of the boiler, the open fire zone sequentially comprises an open fire front section and an open fire tail section along the flow direction of flue gas, and the reducing agent liquid inlet piece is connected with the open fire tail section; a liquid storage tank and a gas storage tank are arranged outside the boiler, urea solution is stored in the liquid storage tank, a reducing agent liquid inlet piece is connected with the liquid storage tank, and the reducing agent liquid inlet piece is connected with the gas storage tank.
By adopting the technical scheme, the suitable temperature for denitration of the reducing agent in the boiler is between 850 ℃ and 1100 ℃. During small boiler load changes, the temperature of the flue gas will continuously decrease as it flows along the boiler, and the decreasing speed tends to increase first and then decrease, i.e. the region where the temperature change is the smallest and the most constant is at the beginning of the flue gas (i.e. the open flame zone) and at the end of the boiler. And the temperature of the tail section of the boiler is greatly reduced to be lower than the SNCR denitration reaction temperature, so that the tail section of the boiler is not suitable for the denitration reaction of the reducing agent. The temperature of the open flame zone is generally changed between 900 ℃ and 1300 ℃ and is slightly higher than the proper reaction temperature of the reducing agent, so the open flame zone is most suitable to be used as the SNCR reaction zone of the small-sized boiler.
It is worth mentioning that when ammonia water is used as a reducing agent, the ammonia water is sprayed into the open flame region and is often burnt by open flame with oxygen in the temperature rising process, so that NH is generated3And is difficult to react with nitrogen oxides. When urea is used as a reducing agent, NH is generated as long as urea is sprayed to the tail section of the open fire3The amount of burning off will be greatly reduced, since urea will undergo a decomposition reaction to produce NH after being sprayed into the open flame tail section3And after decomposition is complete, NH3The urea is separated from the open fire tail section and moves to the area without open fire in the boiler, and the urea is heated in the open fire tail section in the decomposition process and can be approximately heated to denitrationWithin the reaction temperature range, the NH which is not burnt off and the temperature rise is completed3Just as it can react with nitrogen oxides.
Therefore, the denitration efficiency of the small boiler can be improved by spraying urea into the open flame tail section.
In addition, after more ammonia is reacted, the utilization rate of urea is improved, and ammonia escape is reduced.
The invention is further configured to: a plurality of circular pipes which are communicated end to end are arranged in the open fire tail section, the diameters of the circular pipes are gradually reduced, and the circular pipes are coaxially arranged; the circumferential wall of the ring pipe is communicated with a plurality of upward nozzles; the reducing agent liquid inlet pieces are tubular and are provided with a plurality of pipes, and each reducing agent liquid inlet piece is correspondingly communicated with one ring pipe; all the reducing agent liquid inlet pieces are communicated with the liquid storage tank, all the reducing agent liquid inlet pieces are communicated with the gas storage tank, and each reducing agent liquid inlet piece is provided with an opening and closing valve for controlling urea and gas to enter the boiler.
By adopting the technical scheme, in order to prevent the occurrence of local overheating caused by flame scouring on heating surfaces such as water-cooled walls and the like, namely, in order to ensure that each heating surface of the boiler is uniformly heated and distributed and prevent the heating surfaces from coking, the center of the flame needs to be maintained at the central axis of the whole open flame zone. Therefore, the temperature in the whole open flame tail section is characterized by high middle, low periphery, high lower end and low upper end, and the environment temperature of the most peripheral ring pipe is the lowest and the environment temperature of the most inner ring pipe is the highest in the plurality of ring pipes, that is, the ring pipe with larger diameter is higher.
And because the temperature variation range of the open fire tail section in the small-sized boiler is higher than the proper temperature of the denitration reaction, the problem that the temperature variation range of the open fire tail section is not matched with the proper temperature interval of the denitration reaction can be alleviated by the arrangement of the plurality of groups of ring pipes, and the specific operation principle is as follows:
when the small-sized boiler works under high load, namely the average temperature of the tail section of the open fire is higher than the proper temperature range of the denitration reaction, the ring pipe with the lowest environmental temperature starts to work and sprays urea solution so as to draw urine to the maximum extentThe temperature after the temperature rise and the proper temperature interval of the denitration reaction are set; when the small-sized boiler works at low load, namely the average temperature of the open fire tail section is adapted to the proper temperature interval of the denitration reaction, the ring pipe with the highest environmental temperature starts to work and urea solution is sprayed, so that the temperature rising efficiency of urea is ensured as much as possible on the premise that the temperature of the open fire tail section is adapted to the proper temperature interval of the denitration reaction, and NH decomposed from urea is prevented from being heated insufficiently and causing3Lower than the proper temperature interval for denitration reaction.
The invention is further configured to: the smaller the diameter of the loop, the lower the height.
Through adopting above-mentioned technical scheme, the temperature in the whole open flame tail section can be high in the middle of being, low all around, and the lower extreme is high, the upper end is low, then through making a plurality of ring canal exist highly look into, especially let the ring canal that originally is located the ambient temperature lower be in more eminence, promptly, enlarged the temperature difference between a plurality of ring canals to the change in the bigger temperature range of adaptation boiler.
The invention is further configured to: the gas outlet of the boiler is communicated with a flue, the flue is connected with a gas return pipe which is used for conveying part of the flue gas which passes through the economizer and the air preheater back to the open fire tail section, the gas return pipe is provided with a circulating gas pump, one end of the gas return pipe, which is close to the boiler, is communicated with a cooling spray gun, the cooling spray gun penetrates into the boiler, and a control valve which is used for controlling the flue gas to enter the boiler is arranged on the cooling spray gun.
By adopting the technical scheme, the return pipe can transmit part of low-temperature flue gas which passes through the economizer and the air preheater back to the open fire tail section so as to reduce the temperature of the open fire tail section. The operation is mainly used for drawing a temperature interval between the temperature after the temperature rise of the urea and the proper temperature interval of the denitration reaction to a greater extent when the small-sized boiler works at a high load.
The invention is further configured to: and one end of the cooling spray gun communicated with the open flame tail section is positioned above the annular pipe at the outermost ring.
By adopting the technical scheme, the cooling spray gun mainly aims at the ring pipe with the lowest environment temperature, and the ring pipe with the lowest environment temperature is most directly and effectively reduced, so that the mode of drawing the temperature after urea temperature rise decomposition and the proper temperature interval of denitration reaction can be realized.
The invention is further configured to: the gas outlet of the boiler is communicated with a flue, the flue is connected with a gas return pipe for transmitting part of the flue gas passing through the economizer and the air preheater back to the open fire tail section, the gas return pipe is provided with a circulating gas pump, one end of the gas return pipe close to the boiler is communicated with a cooling spray gun, and the cooling spray gun penetrates into the boiler; a water tank is arranged outside the boiler, a water delivery pipe is communicated between one end of the cooling spray gun outside the boiler and the water tank, and a water delivery pump is arranged on the water delivery pipe; and a control valve for controlling water and flue gas to enter the boiler is arranged on the cooling spray gun.
By adopting the technical scheme, the cooling spray gun sprays external cold water into the open flame tail section to carry out proper cooling. The operation is mainly used for drawing a temperature interval between the temperature after the temperature rise of the urea and the proper temperature interval of the denitration reaction to a greater extent when the small-sized boiler works at a high load.
The invention is further configured to: a water tank is arranged outside the boiler, a cooling spray gun penetrates through the circumferential wall of the boiler, a water delivery pipe is communicated between one end of the cooling spray gun, which is positioned outside the boiler, and the water tank, and a water delivery pump is arranged on the water delivery pipe; the cooling spray gun is provided with a control valve for controlling water to enter the boiler.
By adopting the technical scheme, the cooling spray gun sprays low-temperature flue gas and external cold water into the open flame tail section so as to properly cool. The operation is mainly used for drawing a temperature interval between the temperature after the temperature rise of the urea and the proper temperature interval of the denitration reaction to a greater extent when the small-sized boiler works at a high load.
And in the process of spraying cold water and low-temperature flue gas into the open fire tail section, the flue gas can be mixed into the cold water to atomize the water sprayed into the open fire tail section, so that the heat exchange efficiency of the cold water in the open fire tail section is improved.
The invention is further configured to: the periphery of the spray head is wrapped by a protective sleeve.
By adopting the technical scheme, the protective sleeve can be made of high-temperature-resistant, corrosion-resistant and wear-resistant alloy materials and is used for protecting the spray head in the boiler and prolonging the service life of the spray head.
In conclusion, the beneficial technical effects of the invention are as follows:
1. in the scheme, the urea is sprayed into the open fire tail section, so that the denitration efficiency is improved;
2. in the scheme, the temperature after urea temperature rise and decomposition and the proper temperature interval of denitration reaction are drawn as close as possible, so that the denitration efficiency is improved, namely a plurality of circular pipes at different environmental temperatures are arranged, and the proper circular pipes are operated according to the load condition of small filtration.
Drawings
Fig. 1 is a schematic diagram of a first embodiment of the present invention.
Fig. 2 is a schematic diagram of a second embodiment of the present invention.
Fig. 3 is a schematic diagram of a third embodiment of the present invention.
In the figure, 1, a boiler; 11. a coal economizer; 12. an air preheater; 13. a flue; 2. an open flame zone; 21. open fire front section; 22. an open fire tail section; 23. a ring pipe; 24. a spray head; 25. a reducing agent inlet part; 26. opening and closing a valve; 3. a water tank; 4. a liquid storage tank; 41. a liquid outlet pump; 42. a mother liquid outlet pipe; 43. a liquid outlet branch pipe; 5. a gas storage tank; 51. discharging the air pump; 52. an air outlet main pipe; 53. an air outlet branch pipe; 6. cooling the spray gun; 61. a control valve; 62. an air return pipe; 63. a circulating air pump; 64. a water delivery pipe; 65. a water delivery pump.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
In a first embodiment, referring to fig. 1, an SNCR denitration system applied to a small boiler disclosed by the present invention includes a boiler 1, an open flame region 2 is arranged in the boiler 1, the open flame region 2 is a place where an open flame can be seen in the boiler 1, and the open flame region 2 sequentially includes an open flame front section 21 and an open flame rear section 22 along a flue gas flowing direction.
Wherein the suitable temperature for denitration of the reducing agent in the boiler 1 is between 850 ℃ and 1100 ℃. During the load change of the small boiler 1, the temperature of the flue gas will continuously decrease as the flue gas flows along the boiler 1, and the decreasing speed tends to increase first and then decrease, that is, the area with the smallest temperature change and the most constant is at the beginning of the flue gas (i.e. the open flame area 2) and the end section of the boiler 1. And the temperature of the tail section of the boiler 1 is greatly reduced to be below the SNCR denitration reaction temperature, so that the tail section of the boiler 1 is not suitable for the denitration reaction of the reducing agent. The temperature of the open flame zone 2 is generally changed between 900 ℃ and 1300 ℃ and is slightly higher than the proper reaction temperature of the reducing agent, so that the open flame zone 2 is most suitable to be used as the SNCR reaction zone of the small-sized boiler 1.
It is worth mentioning that when ammonia water is used as the reducing agent, the ammonia water sprayed into the open flame region 2 is often burnt by open flame with oxygen in the temperature rising process, resulting in NH3And is difficult to react with nitrogen oxides. When urea is used as a reducing agent, NH is generated as long as urea is sprayed to the open flame tail section 223The amount of burning off will be greatly reduced since urea will undergo a decomposition reaction to produce NH after being sprayed into the open flame tail section 223And after decomposition is complete, NH3The urea is separated from the open flame tail section 22 and moves to the area without open flame in the boiler 1, and the temperature of the urea is increased in the open flame tail section 22 in the decomposition process and can be approximately increased to the denitration reaction temperature range, and the NH which is heated and is not burnt is completed at the moment3Just as it can react with nitrogen oxides.
Therefore, the denitration efficiency of the small boiler 1 can be improved by injecting urea into the open flame tail section 22.
The open fire tail section 22 is internally provided with three circular pipes 23 which are communicated end to end, the diameters of the three circular pipes 23 are gradually reduced, and the plurality of circular pipes 23 are coaxially arranged, wherein the height of the circular pipe 23 with the smaller diameter is lower, namely, the circular pipe 23 with the smaller diameter is closer to the open fire front end. All communicate with a plurality of shower nozzle 24 that sets up on every ring canal 23 perisporium, shower nozzle 24 periphery parcel has protective case (not shown in the figure), and protective case can select high temperature resistant, corrosion-resistant, stand wear and tear alloy material to make for the shower nozzle 24 of protection in boiler 1, prolongs its life-span.
Three reducing agent liquid inlet pieces 25 are arranged on the circumferential wall of the boiler 1 in a penetrating manner, the reducing agent liquid inlet pieces 25 are tubular, each reducing agent liquid inlet piece 25 is correspondingly communicated with one ring pipe 23, and each reducing agent liquid inlet piece 25 is provided with a mounting holeThere is an on-off valve 26. A liquid storage tank 4 and a gas storage tank 5 are arranged outside the boiler 1, the liquid storage tank 4 is used for storing urea solution, and the gas storage tank 5 is used for storing high-pressure gas. A liquid outlet main pipe 42 is connected to the liquid storage tank 4, a liquid outlet pump 41 is mounted on the liquid outlet main pipe 42, the liquid outlet pump 41 is a metering pump, three liquid outlet branch pipes 43 are connected to the liquid outlet main pipe 42, and the three liquid outlet branch pipes 43 are respectively communicated with a reducing agent liquid inlet part 25; the gas storage tank 5 is connected with a gas outlet main pipe 52, the gas outlet main pipe 52 is provided with a gas outlet pump 51, the gas outlet pump 51 is a metering pump, the gas outlet main pipe 52 is connected with three gas outlet branch pipes 53, and the three gas outlet branch pipes 53 are respectively communicated with a reducing agent inlet part 25. The valve 26 can cut off or open the urea and the gas into the boiler 1, and the high-pressure gas mixed with the urea solution can atomize the urea solution sprayed from the nozzle 24, thereby increasing NH after urea decomposition3The contact area with nitrogen oxides.
It should be noted that, in order to prevent the occurrence of local overheating caused by flame scouring on the heating surfaces such as water-cooled walls, that is, in order to make the heating surfaces of the boiler 1 uniformly heated and to prevent the heating surfaces from coking, the flame center needs to be maintained at the central axis of the whole open flame zone 2. Therefore, the temperature in the whole open flame tail section 22 is characterized by high middle, low periphery, high lower end and low upper end, and the environment temperature of the outermost and uppermost ring pipes 23 is the lowest among the plurality of ring pipes 23, and the environment temperature of the innermost and lowermost ring pipes 23 is the highest, that is, the ring pipe 23 with the larger diameter is the higher.
And because the temperature variation range of the open fire tail section 22 in the small-sized boiler 1 is higher than the proper temperature of the denitration reaction, the problem that the temperature variation range of the open fire tail section 22 is not matched with the proper temperature interval of the denitration reaction can be alleviated by the arrangement of the plurality of groups of ring pipes 23, and the specific operation principle is as follows:
when the small-sized boiler 1 works under high load, namely the average temperature of the open fire tail section 22 is higher than the proper temperature interval of the denitration reaction, the ring pipe 23 with the lowest environmental temperature starts to work and urea solution is sprayed, so that the temperature after the urea is heated and the proper temperature interval of the denitration reaction are drawn to the maximum extent; at the low part of a small boiler 1The load work is that when the average temperature of the open fire tail section 22 is adapted to the proper temperature interval of the denitration reaction, the loop 23 with the highest environmental temperature starts to work and urea solution is sprayed, so that on the premise that the temperature of the open fire tail section 22 is adapted to the proper temperature interval of the denitration reaction, the temperature rise efficiency of urea is ensured as much as possible, and the NH decomposed from urea is prevented from being insufficiently raised, which results in insufficient temperature rise of urea3Lower than the proper temperature interval for denitration reaction.
An air outlet of the boiler 1 is communicated with a flue 13, the flue 13 is connected with an air return pipe 62, the air return pipe 62 is provided with a circulating air pump 63, one end of the air return pipe 62, which is close to the boiler 1, is communicated with a cooling spray gun 6, the cooling spray gun 6 penetrates into the boiler 1, and the cooling spray gun 6 is provided with a control valve 61. The return pipe 62 may transmit part of the low temperature flue gas that has passed through the economizer 11 and the air preheater 12 back to the open flame tail section 22 for reducing the temperature of the open flame tail section 22. The operation is mainly used for drawing a temperature range between the temperature after the urea temperature rise and the proper temperature range of the denitration reaction to a greater extent when the small-sized boiler 1 works under a high load.
Moreover, one end of the cooling spray gun 6 communicated with the open flame tail section 22 is positioned above the annular pipe 23 at the outermost ring, so that the cooling spray gun 6 mainly aims at the annular pipe 23 at the lowest environmental temperature, and because the annular pipe 23 at the lowest environmental temperature is most directly and effectively reduced, the temperature after the urea is heated and decomposed and the proper temperature range of the denitration reaction can be drawn.
The implementation principle of the embodiment is as follows: the urea is sprayed into the open flame tail section 22, so that the denitration efficiency is improved; meanwhile, the temperature after urea temperature rise decomposition and the proper temperature interval of denitration reaction are drawn as close as possible through the following two modes, so that the denitration efficiency is improved. Firstly, a plurality of circular pipes 23 at different environmental temperatures are arranged, and the proper circular pipes 23 are operated according to the load condition of the small-scale filtration; secondly, the low-temperature flue gas is sprayed into the open flame tail section 22 through the cooling spray gun 6 so as to carry out proper temperature reduction.
Second embodiment, referring to fig. 2, the only difference from the first embodiment is that there are no air return pipe 62 and no air circulation pump 63, and there are provided a water tank 3, a water pipe 64 and a water pump 65.
The water tank 3 is arranged outside the boiler 1, the water delivery pipe 64 is communicated with the cooling spray gun 6 and is positioned between one end outside the boiler 1 and the water tank 3, and the water delivery pump 65 is arranged on the water delivery pipe 64.
The implementation principle of the embodiment is as follows: the urea is sprayed into the open flame tail section 22, so that the denitration efficiency is improved; meanwhile, the temperature after urea temperature rise decomposition and the proper temperature interval of denitration reaction are drawn as close as possible through the following two modes, so that the denitration efficiency is improved. Firstly, a plurality of circular pipes 23 at different environmental temperatures are arranged, and the proper circular pipes 23 are operated according to the load condition of the small-scale filtration; secondly, the cooling spray gun 6 sprays external cold water into the open fire tail section 22 to perform proper temperature reduction.
Third embodiment, referring to fig. 3, the only difference from the first embodiment is that a water tank 3, a water pipe 64 and a water pump 65 are additionally provided.
The water tank 3 is arranged outside the boiler 1, the water delivery pipe 64 is communicated with the cooling spray gun 6 and is positioned between one end outside the boiler 1 and the water tank 3, and the water delivery pump 65 is arranged on the water delivery pipe 64.
The implementation principle of the embodiment is as follows: the urea is sprayed into the open flame tail section 22, so that the denitration efficiency is improved; meanwhile, the temperature after urea temperature rise decomposition and the proper temperature interval of denitration reaction are drawn as close as possible through the following two modes, so that the denitration efficiency is improved. Firstly, a plurality of circular pipes 23 at different environmental temperatures are arranged, and the proper circular pipes 23 are operated according to the load condition of the small-scale filtration; secondly, the cooling spray gun 6 sprays low-temperature flue gas and external cold water into the open fire tail section 22 to perform proper temperature reduction.
In the process that the cold water and the low-temperature flue gas are sprayed into the open fire tail section 22, the flue gas can be mixed into the cold water to atomize the water sprayed into the open fire tail section 22, and therefore the heat exchange efficiency of the cold water in the open fire tail section 22 is improved.
The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.
Claims (6)
1. An SNCR denitration system applied to a small boiler comprises a boiler (1), wherein an open fire area (2) is arranged in the boiler (1); the method is characterized in that: a reducing agent liquid inlet piece (25) penetrates through the peripheral wall of the boiler (1), the open fire area (2) sequentially comprises an open fire front section (21) and an open fire tail section (22) along the flowing direction of flue gas, and the reducing agent liquid inlet piece (25) is connected with the open fire tail section (22); a liquid storage tank (4) and a gas storage tank (5) are arranged outside the boiler (1), urea solution is stored in the liquid storage tank (4), a reducing agent liquid inlet piece (25) is connected with the liquid storage tank (4), and the reducing agent liquid inlet piece (25) is connected with the gas storage tank (5);
a plurality of circular pipes (23) which are communicated end to end are arranged in the open fire tail section (22), the diameters of the circular pipes (23) are gradually reduced, and the circular pipes (23) are coaxially arranged; the circumferential wall of the ring pipe (23) is communicated with a plurality of upward nozzles (24); the reducing agent liquid inlet pieces (25) are tubular and are provided with a plurality of pipes, and each reducing agent liquid inlet piece (25) is correspondingly communicated with one ring pipe (23); all the reducing agent liquid inlet pieces (25) are communicated with the liquid storage tank (4), all the reducing agent liquid inlet pieces (25) are communicated with the gas storage tank (5), and each reducing agent liquid inlet piece (25) is provided with an on-off valve (26) for controlling urea and gas to enter the boiler (1); the smaller the diameter of the loop (23) is, the lower the height is.
2. The SNCR denitration system applied to a small boiler according to claim 1, characterized in that: boiler (1) gas outlet intercommunication has flue (13), even goes out on flue (13) to be used for transmitting back to return gas return pipe (62) of naked light tail section (22) with the part flue gas that has passed through economizer (11) and air preheater (12), be equipped with circulating air pump (63) on return pipe (62), return pipe (62) are close to boiler (1) one end intercommunication and have cooling spray gun (6), in cooling spray gun (6) worn into boiler (1), install on cooling spray gun (6) and be used for controlling the flue gas and advance to control valve (61) in boiler (1).
3. The SNCR denitration system applied to a small boiler according to claim 2, characterized in that: one end of the cooling spray gun (6) communicated with the open fire tail section (22) is positioned above the annular pipe (23) at the outermost ring.
4. The SNCR denitration system applied to a small boiler according to claim 1, characterized in that: the air outlet of the boiler (1) is communicated with a flue (13), the flue (13) is connected with an air return pipe (62) which is used for conveying part of flue gas passing through the economizer (11) and the air preheater (12) back to the open fire tail section (22), the air return pipe (62) is provided with a circulating air pump (63), one end of the air return pipe (62) close to the boiler (1) is communicated with a cooling spray gun (6), and the cooling spray gun (6) penetrates into the boiler (1); a water tank (3) is arranged outside the boiler (1), a water pipe (64) is communicated between one end of the cooling spray gun (6) positioned outside the boiler (1) and the water tank (3), and a water delivery pump (65) is arranged on the water pipe (64); the cooling spray gun (6) is provided with a control valve (61) for controlling water and flue gas to enter the boiler (1).
5. The SNCR denitration system applied to a small boiler according to claim 1, characterized in that: a water tank (3) is arranged outside the boiler (1), a cooling spray gun (6) penetrates through the peripheral wall of the boiler (1), a water conveying pipe (64) is communicated between one end, located outside the boiler (1), of the cooling spray gun (6) and the water tank (3), and a water conveying pump (65) is arranged on the water conveying pipe (64); the cooling spray gun (6) is provided with a control valve (61) for controlling water to enter the boiler (1).
6. The SNCR denitration system applied to a small boiler according to claim 1, characterized in that: the periphery of the spray head (24) is wrapped with a protective sleeve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811438213.7A CN109464899B (en) | 2018-11-27 | 2018-11-27 | SNCR denitration system applied to small boiler |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811438213.7A CN109464899B (en) | 2018-11-27 | 2018-11-27 | SNCR denitration system applied to small boiler |
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| CN109464899A CN109464899A (en) | 2019-03-15 |
| CN109464899B true CN109464899B (en) | 2021-12-21 |
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| CN201811438213.7A Active CN109464899B (en) | 2018-11-27 | 2018-11-27 | SNCR denitration system applied to small boiler |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002029219A1 (en) * | 2000-10-04 | 2002-04-11 | Robert Bosch Gmbh | Device for producing a reducing agent/exhaust gas mixture and exhaust gas purification system |
| CN108126491A (en) * | 2018-01-24 | 2018-06-08 | 江苏德义通环保科技有限公司 | A kind of efficient NOx control method and device of biomass boiler |
| CN108151006A (en) * | 2017-12-28 | 2018-06-12 | 中国计量大学 | A kind of SNCR and flue gas recirculation for chain furnace couples denitrating system |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002029219A1 (en) * | 2000-10-04 | 2002-04-11 | Robert Bosch Gmbh | Device for producing a reducing agent/exhaust gas mixture and exhaust gas purification system |
| CN108151006A (en) * | 2017-12-28 | 2018-06-12 | 中国计量大学 | A kind of SNCR and flue gas recirculation for chain furnace couples denitrating system |
| CN108126491A (en) * | 2018-01-24 | 2018-06-08 | 江苏德义通环保科技有限公司 | A kind of efficient NOx control method and device of biomass boiler |
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