CN203525568U - Device for preparing ammonia through urea pyrolysis - Google Patents

Device for preparing ammonia through urea pyrolysis Download PDF

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Publication number
CN203525568U
CN203525568U CN201320693102.7U CN201320693102U CN203525568U CN 203525568 U CN203525568 U CN 203525568U CN 201320693102 U CN201320693102 U CN 201320693102U CN 203525568 U CN203525568 U CN 203525568U
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Prior art keywords
flue
gas bypass
urea
spray gun
gas
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CN201320693102.7U
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李金晶
郭玥
赵振宁
张清峰
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State Grid Corp of China SGCC
North China Electric Power Research Institute Co Ltd
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State Grid Corp of China SGCC
North China Electric Power Research Institute Co Ltd
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Abstract

The utility model provides a device for preparing ammonia through urea pyrolysis. The device comprises a flue (4) and one or more spray guns (52) capable of spraying a urea solution into the flue (4), or comprises the flue (4) and one or more flue gas by-paths (6), wherein the two ends of each flue gas by-path are communicated with the flue (4); one or more spray guns (52) capable of spraying a urea solution into the flue gas by-paths (4) are arranged on the flue gas by-paths (6). The device for preparing ammonia through urea pyrolysis can be used for well controlling the concentration of ammonia gas in flue gas; in addition, the device for preparing ammonia through urea pyrolysis is simple in structure and convenient to maintain.

Description

Urea pyrolysis ammonia-preparing device
Technical field
The utility model relates to environmental protecting device technical field, specifically a kind of urea pyrolysis ammonia-preparing device.
Background technology
SCR(selective catalytic reduction) denitrating technique needs ammonia as reducing agent, and general ammonia has three kinds of forms: liquefied ammonia, urea, ammoniacal liquor.What use was more at present is liquefied ammonia, and SCR denitration technology also all adopts this technique mostly.Because liquefied ammonia belongs to high-risk product, its storage and transportation be very inconvenience all, Qie Dui power plant and surrounding enviroment all form larger potential safety hazard, and therefore some power plant in the comparatively concentrated or close urban district of some populations mainly adopt urea ammonia processed to improve the security of denitrification apparatus.Urea preparing ammonia, has two kinds of methods: pyrolysis and hydrolysis conventionally.Hydrolyze method is decomposed urea with the form of the aqueous solution, pyrolysismethod is that the urea liquid after direct Fast Heating atomization decomposes.The urea under high pressure pyrolysis temperature of (2.0MPa) is 160-240 ℃, and the pyrolysis temperature under normal pressure is 350-460 ℃.
In order to save the energy, those skilled in the art has invented again the method for utilizing fume afterheat heating urea: contact heating method.Contact heating method be adopt heat exchanger by the thermal energy transfer of flue gas to urea liquid, between flue gas and urea liquid, only have energy exchange and do not have mass exchange, the advantage of the method is that urea liquid can not stain by flue dust, urea spray gun operational reliability is high, but the heat exchange efficiency of contact heating is lower.
For the ease of understanding, the related technical name of this paper is made an explanation:
SCR(selective catalytic reduction) denitration: selective catalytic reduction denitration, at boiler back end ductwork, spray into liquefied ammonia or ammoniacal liquor, under 280-420 ℃ and catalyst action, the reaction that nitrogen oxides in effluent is removed by NH3 reduction.
Current-sharing grid: be arranged in the flase floor before SCR reaction zone, make flue gas uniform-flow cross the catalyst in reaction zone, to improve denitration reaction efficiency.
Economizer: be arranged in the heating surface in boiler back end ductwork, for preheating the feedwater that is about to enter boiler water wall.
Negative pressure: gas pressure is lower than the state of atmospheric pressure.
Utility model content
In order to solve the lower technical problem of heat exchange efficiency of contact heating.The utility model provides a kind of urea pyrolysis ammonia-preparing device, this urea pyrolysis ammonia-preparing device comprises that flue and at least one can be to spraying the spray gun of urea liquid in this flue or by gas bypass being set and spray gun being set in gas bypass, thereby can well control the concentration of ammonia in flue gas gas, in addition, this urea pyrolysis ammonia-preparing device simple in structure, easy to maintenance.
The utility model for the technical scheme that solves its technical problem and adopt is: a kind of urea pyrolysis ammonia-preparing device, comprises that flue and at least one can be to the spray guns that sprays urea liquid in this flue.
In flue, be provided with economizer, spray gun is arranged on the flue that is positioned at economizer entrance, and spray gun is connected with assignment of traffic and metering device, and spray gun is also connected with the pipeline for injecting compressed air in spray gun, and pipeline is provided with air door.
A urea pyrolysis ammonia-preparing device, comprises flue and at least one gas bypass, and the two ends of gas bypass are all communicated with flue, and gas bypass is provided with at least one can be to the spray gun that sprays urea liquid in this gas bypass.
In flue, be provided with economizer and current-sharing grid, one end of gas bypass is communicated with the flue that is positioned at economizer entrance, and the other end of this gas bypass is communicated with the flue that is positioned at current-sharing grid entrance.
Air pressure in one end of gas bypass is greater than the air pressure in the other end of this gas bypass.
Gas bypass is provided with for regulating the gas baffle of flue gas flow in gas bypass.
Spray gun is connected with the pipeline for injecting compressed air in spray gun, and pipeline is provided with air door.
Spray gun is connected with assignment of traffic and metering device.
Gas bypass is provided with for monitoring the flow sensor of flue gas flow in this gas bypass.
Gas bypass is provided with for monitoring the temperature sensor of urea pyrolysis temperature in this gas bypass.
The beneficial effects of the utility model are:
1, utilize fume afterheat before the economizer pyrolysis institute calorific requirement of supplying urea, without external heat source;
2, adopt mixed heating method, the efficiency of heating surface is high, and system bulk is little;
3, utilize the flue gas differential pressure of economizer front and back as the driving force of heating system, do not need to increase the equipment such as blower fan, the energy consumption of denitrating system is little;
4, simple in structure, easy to maintenance.
Accompanying drawing explanation
Below in conjunction with accompanying drawing, urea pyrolysis ammonia-preparing device described in the utility model is described in further detail.
Fig. 1 is the structural representation of urea pyrolysis ammonia-preparing device in embodiment 1.
Fig. 2 is the structural representation of urea pyrolysis ammonia-preparing device in embodiment 2.
1. economizers wherein, 2. current-sharing grid, 3. denitrating catalyst, 4. flue, 51. assignment of traffic and metering device, 52. spray guns, 53. air doors, 54. pipelines, 6. gas bypass, 61. gas baffles, 62. flow sensors, 63. temperature sensors.
The specific embodiment
Embodiment 1
Below in conjunction with accompanying drawing, urea pyrolysis ammonia-preparing device described in the utility model is described in further detail.A urea pyrolysis ammonia-preparing device, comprises that flue 4 and at least one can be to the spray guns 52 of the interior injection urea liquid of this flue 4, as shown in Figure 1.
The utility model is the technique of urea pyrolysis ammonia processed under normal pressure.The pyrolysis temperature of urea under normal pressure is 350-460 ℃, and when boiler normally moves, in back-end ductwork, economizer inlet flue gas temperature is just in time in this temperature range.Therefore, can utilize the boiler economizer inlet flue gas required heat of solution pyrolysis of supplying urea.Urea liquid is directly sprayed in high-temperature flue gas (as shown by arrow A), can efficiently utilize the waste heat of flue gas that urea liquid (as shown by arrow B) is heated rapidly to applicable decomposition temperature.Due to oxygen concentration in flue gas lower (approximately 3%), can effectively evade the risk that ammonia and oxygen mix are blasted.
In flue 4, be provided with economizer 1, spray gun 52 is arranged on the flue 4 that is positioned at economizer 1 entrance, spray gun 52 is connected with assignment of traffic and metering device 51, and spray gun 52 is also connected with for the pipeline 54 to spray gun 52 interior injecting compressed airs, and pipeline 54 is provided with air door 53.
Under the operating mode of stopping transport at spray gun 52, pass into continuously compressed air (as shown by arrow C) and can guarantee that spray gun is not stopped up by flue dust.Because flue gas moves in negative pressure, if being in operation, stops up by spray gun, can directly spray gun be extracted and dredges and safeguard from exhaust gases passes, and needn't worry that high-temperature flue gas ejection hurts sb.'s feelings.Urea liquid by assignment of traffic and metering device 51 after, adopt the mode of multi-point injection directly to spray into economizer gas approach by spray gun 52, before entering current-sharing grid 2, evenly mix the rear decomposition reaction that heated up rapidly with high-temperature flue gas and generate ammonia, under denitrating catalyst 3 effects, nitrogen oxides in effluent is removed by NH3 reduction.When spray gun is stopped transport, compressed air valve 53 is opened, and in spray gun, passes into continuously compressed air, prevents that spray gun from being stopped up by flue dust.
Embodiment 2
A urea pyrolysis ammonia-preparing device, comprises flue 4 and at least one gas bypass 6, and the two ends of gas bypass 6 are all communicated with flue 4, and gas bypass 6 is provided with at least one can be to the spray gun 52 of the interior injection urea liquid of this gas bypass 6, as shown in Figure 2.
In embodiment 1, directly in flue 4, spray urea liquid, in flue 4, the flow of flue gas is uncontrollable, may occur that gas residence time is less than urea liquid pyrolytic reaction required time, reduces urea decomposition rate, affects the economy of denitrating system operation.Increased after gas bypass 6, spray gun 52 is to the interior ejection urea liquid of gas bypass 6, as arrow B in Fig. 2 represents urea liquid, the time of staying of the pyrolytic reaction of this urea liquid in gas bypass 6 can be regulated by the flue gas flow in this gas bypass 6, to guarantee the abundant pyrolysis of urea.
Gas bypass 6 along continuous straight runs settings, gas bypass 6 is along the width setting of burner hearth.In flue 4, be provided with economizer 1 and current-sharing grid 2, one end of gas bypass 6 is communicated with the flue 4 that is positioned at economizer 1 entrance, and the other end of this gas bypass 6 is communicated with the flue 4 that is positioned at current-sharing grid 2 entrances.Because the both sides of economizer 1 exist pressure reduction, so the air pressure in one end of gas bypass 6 is greater than the air pressure in the other end of this gas bypass 6, as shown in Figure 2, the air pressure in the left end of gas bypass 6 is greater than the air pressure in the right-hand member of this gas bypass 6.Flue gas can be automatically flows and without additional air-blast device in gas bypass 6 like this.
Gas bypass 6 is provided with for regulating the gas baffle 61 of gas bypass 6 interior flue gas flows.Spray gun 52 is connected with for the pipeline 54 to spray gun 52 interior injecting compressed airs, pipeline 54 is provided with air door 53, under spray gun stoppage in transit operating mode, pass into continuously compressed air (as shown by arrow C), can guarantee that spray gun is not stopped up by flue dust, because flue gas moves in negative pressure, if spray gun is in operation, stop up, can directly spray gun be extracted and dredges and safeguard from exhaust gases passes, and needn't worry that high-temperature flue gas ejection hurts sb.'s feelings.
Spray gun 52 is connected with assignment of traffic and metering device 51, and the effect of assignment of traffic and metering device 51 mainly contains two: 1, distribute the flow of the urea liquid in each spray gun, flue gas is mixed with urea liquid; 2, the flow of metering urea liquid, controls reference data is provided for operation, and facilitate managerial personnel to calculate denitrating system economy.Gas bypass 6 is provided with for monitoring the flow sensor 62 of these gas bypass 6 interior flue gas flows.Gas bypass 6 is provided with for monitoring the temperature sensor 63 of the interior urea pyrolysis temperature of this gas bypass 6.According to the monitoring of flow sensor 62 and temperature sensor 63, by gas baffle 61, controlled the flow of gas bypass 6 interior flue gases, thereby control the time of staying of urea pyrolysis reaction.
During work, the ammonia that the interior pyrolytic reaction of gas bypass 6 generates and the flue gas shown in arrow A on the right side of flue 4 after even mixing through current-sharing grid 2, the nitrogen oxide under the effect of denitrating catalyst 3 in flue gas is reduced and removes.
The above; be only specific embodiment of the utility model, can not limit the scope that utility model is implemented with it, so the displacement of its equivalent assemblies; or the equivalent variations of doing according to the utility model scope of patent protection and modification, all should still belong to the category that this patent is contained.

Claims (10)

1. a urea pyrolysis ammonia-preparing device, is characterized in that, described urea pyrolysis ammonia-preparing device comprises that flue (4) and at least one can be to the spray guns (52) that sprays urea liquid in this flue (4).
2. urea pyrolysis ammonia-preparing device according to claim 1, it is characterized in that: in flue (4), be provided with economizer (1), spray gun (52) is arranged on the flue (4) that is positioned at economizer (1) entrance, spray gun (52) is connected with assignment of traffic and metering device (51), spray gun (52) is also connected with for the pipeline (54) to the interior injecting compressed air of spray gun (52), and pipeline (54) is provided with air door (53).
3. a urea pyrolysis ammonia-preparing device, it is characterized in that, described urea pyrolysis ammonia-preparing device comprises flue (4) and at least one gas bypass (6), the two ends of gas bypass (6) are all communicated with flue (4), and gas bypass (6) is provided with at least one can be to the spray gun (52) of injection urea liquid in this gas bypass (6).
4. urea pyrolysis ammonia-preparing device according to claim 3, it is characterized in that: in flue (4), be provided with economizer (1) and current-sharing grid (2), one end of gas bypass (6) is communicated with the flue (4) that is positioned at economizer (1) entrance, and the other end of this gas bypass (6) is communicated with the flue (4) that is positioned at current-sharing grid (2) entrance.
5. urea pyrolysis ammonia-preparing device according to claim 3, is characterized in that: the air pressure in one end of gas bypass (6) is greater than the air pressure in the other end of this gas bypass (6).
6. urea pyrolysis ammonia-preparing device according to claim 3, is characterized in that: gas bypass (6) is provided with for regulating the gas baffle (61) of the interior flue gas flow of gas bypass (6).
7. urea pyrolysis ammonia-preparing device according to claim 3, is characterized in that: spray gun (52) is connected with for the pipeline (54) to the interior injecting compressed air of spray gun (52), and pipeline (54) is provided with air door (53).
8. urea pyrolysis ammonia-preparing device according to claim 3, is characterized in that: spray gun (52) is connected with assignment of traffic and metering device (51).
9. urea pyrolysis ammonia-preparing device according to claim 3, is characterized in that: gas bypass (6) is provided with for monitoring the flow sensor (62) of the interior flue gas flow of this gas bypass (6).
10. urea pyrolysis ammonia-preparing device according to claim 3, is characterized in that: gas bypass (6) is provided with for monitoring the temperature sensor (63) of the interior urea pyrolysis temperature of this gas bypass (6).
CN201320693102.7U 2013-11-05 2013-11-05 Device for preparing ammonia through urea pyrolysis Active CN203525568U (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103551034A (en) * 2013-11-05 2014-02-05 国家电网公司 Urea-pyrolysis ammonia preparation device
CN104587830A (en) * 2015-01-09 2015-05-06 西安西热锅炉环保工程有限公司 Urea solution intra-flue direct injection pyrolysis device and method with SCR (Selective Catalytic Reduction) system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103551034A (en) * 2013-11-05 2014-02-05 国家电网公司 Urea-pyrolysis ammonia preparation device
CN104587830A (en) * 2015-01-09 2015-05-06 西安西热锅炉环保工程有限公司 Urea solution intra-flue direct injection pyrolysis device and method with SCR (Selective Catalytic Reduction) system

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