CN213032227U - SCR flue gas denitration system for preparing ammonia by urea pyrolysis - Google Patents
SCR flue gas denitration system for preparing ammonia by urea pyrolysis Download PDFInfo
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- CN213032227U CN213032227U CN202021095892.5U CN202021095892U CN213032227U CN 213032227 U CN213032227 U CN 213032227U CN 202021095892 U CN202021095892 U CN 202021095892U CN 213032227 U CN213032227 U CN 213032227U
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Abstract
The utility model discloses an SCR flue gas denitration system for preparing ammonia by urea pyrolysis, which at least comprises a urea solution storage tank, a feed pump, a metering and distributing device, an atomizing spray gun, a pyrolysis furnace, an ammonia spraying grid, an SCR reactor, a denitration hot primary air duct, a primary air-steam heat exchanger and a primary air-steam heat exchanger steam side pipeline; the urea aqueous solution enters the pyrolysis furnace through the feeding pump, the metering and distributing device and the atomizing spray gun, and the denitration hot primary air enters the pyrolysis furnace through the denitration hot primary air duct after being heated to the temperature required by pyrolysis through the primary air-steam heat exchanger. The utility model discloses a hot air of denitration is heated to primary air-steam heat exchanger replacement electric heater, under the prerequisite of system safety, steady operation, has solved the high problem of urea pyrolysis power consumption, has expanded the degree of depth that the steam turbine backheat steam extraction utilized simultaneously, reaches the purpose that reduces the plant power rate, reduces the cold source loss of steam turbine to reduce the unit energy consumption.
Description
Technical Field
The utility model discloses be applied to the power generation field, especially, relate to an adopt SCR flue gas denitration system of urea pyrolysis system ammonia.
Background
Denitration of coal-fired thermal power plants is one of the key points of energy conservation and emission reduction tasks. Selective Catalytic Reduction (SCR) flue gas denitration is one of the most mature denitration technologies in the world at present, and is widely applied, the chemical reaction mechanism of the SCR flue gas denitration is relatively complex, but the main reaction is NH3Under the action of certain temperature and catalyst, NOx in the fume is selectively reduced into N2And H2O, and the like. At present, liquid ammonia or urea is generally used as a reducing agent for the SCR flue gas denitration process of the coal-fired power plant. The method for preparing ammonia by using liquid ammonia has the advantages of low investment, low operating cost and the like, but the storage and preparation system of the method needs to meet related specifications in the aspects of safety, fire protection, environmental protection and the like, and the daily operation and management of a power plant need to meet the requirements of secondary major hazard sources, such as poor management and easy occurrence of major accidents. The urea in the process of preparing ammonia from urea is a stable and nontoxic solid material, can be transported in bulk and stored for a long time, does not need special procedures in the aspects of transportation and storage, does not have adverse effects on personnel and surrounding residential areas during use, and is widely used due to high safety.
The technology for preparing ammonia from urea mainly adopts a technology for preparing ammonia from urea through pyrolysis, and has the technical key point that hot air is used as a heat source to rapidly decompose 40-55% urea aqueous solution at 400-650 ℃ to prepare ammonia. The hot air is primary air heated by an air preheater (air preheater), namely hot primary air, and the temperature of the hot primary air at the outlet of the conventional air preheater is about 300 ℃ and is far lower than that of air required by urea pyrolysis. In the conventional technology, a set of electric heating system is generally arranged in front of a pyrolysis furnace to increase the temperature of hot primary air, but the method generates larger power consumption, and the hot primary air passing through an air preheater carries smoke dust which can cause the blockage of an electric heater during operation to cause the fault. The urea pyrolysis system has the advantages of near-normal-pressure pyrolysis, low operation pressure and the disadvantages of high energy consumption, high operation cost and poor stability. Taking a certain 600MW unit as an example, the power of a hot primary wind electric heater for SCR flue gas denitration urea pyrolysis reaches 980 kW.
In view of the above insufficiency of the prior art, the utility model aims at providing a high, strong, energy-saving's of security urea pyrolysis system ammonia SCR flue gas denitration system.
Disclosure of Invention
The utility model provides a SCR flue gas denitration system for preparing ammonia by urea pyrolysis, which at least comprises a urea solution storage tank, a feeding pump, a metering and distributing device, an atomizing spray gun, a pyrolysis furnace, an ammonia spraying grid, an SCR reactor and a denitration hot primary air duct, and is characterized by also comprising a primary air-steam heat exchanger and a primary air-steam heat exchanger steam side pipeline, wherein the primary air-steam heat exchanger heats the denitration hot primary air; the urea solution with a certain concentration in the urea solution storage tank enters the pyrolysis furnace through the feeding pump, the metering and distributing device and the atomizing spray gun, the denitration hot primary air passes through the primary air-steam heat exchanger and is heated to the temperature required by pyrolysis, and then enters the pyrolysis furnace through the denitration hot primary air channel to provide heat for the pyrolysis of urea and obtain a product NH after the pyrolysis3To the SCR reactor.
Preferably, the primary air-steam heat exchanger comprises at least one heat exchanger.
Preferably, the steam source of the primary air-steam heat exchanger is high-temperature extraction steam of a steam turbine.
The utility model provides a pair of adopt SCR flue gas deNOx systems of urea pyrolysis system ammonia mainly has following advantage:
1. the utility model discloses utilize once wind-steam heat exchanger to replace electric heater to heat denitration heat once wind, satisfying under the safe, the steady operation's of deNOx systems prerequisite, can solve the high problem of urea pyrolysis power consumption, reduce the station service rate to reduce unit operation energy consumption.
2. The utility model discloses regard the steam turbine extraction as the wind-steam heat exchanger heat source, greatly expanded the degree of depth that backheat extraction utilized, reduce the steam turbine cold source loss simultaneously, improve unit heat economy nature.
The conception, the specific structure and the technical effects of the present invention will be further described with reference to the accompanying drawings, so as to fully understand the objects, the features and the effects of the present invention.
Drawings
Fig. 1 is a system diagram of an embodiment of the present invention.
The labels in the figure are:
1: a boiler; 2: an ammonia injection grid; 3: an SCR reactor; 4: a denitration primary hot air duct; 5: primary air-steam heat exchanger; 6: a primary air-steam heat exchanger steam side pipeline; 7: a pyrolysis furnace; 8: a urea solution storage tank; 9: a feed pump; 10: a metering and dispensing device; 11: an atomizing spray gun.
Detailed Description
Example 1.
As shown in fig. 1, the embodiment of the SCR flue gas denitration system using urea pyrolysis for ammonia production of the present invention includes a boiler 1, an ammonia injection grid 2, an SCR reactor 3, a primary denitration hot air duct 4, a primary air-steam heat exchanger 5, a primary air-steam heat exchanger steam side duct 6, a pyrolysis furnace 7, a urea solution storage tank 8, a feed pump 9, a metering and distributing device 10, and an atomizing spray gun 11. Urea aqueous solution with certain concentration in a urea solution storage tank 8 enters a pyrolysis furnace 7 through a feeding pump 9, a metering and distributing device 10 and an atomizing spray gun 11; the denitration hot primary air is heated to the temperature required by pyrolysis through the primary air-steam heat exchanger 6, then enters the pyrolysis furnace 7 through the denitration hot primary air duct 4 to provide heat for the pyrolysis of urea and obtain a product NH after the pyrolysis3To the SCR reactor 3. The number of the primary air-steam heat exchangers is one, the steam source is the first-stage extraction steam after the hot re-steam, the temperature is high, and the denitration hot primary air meets the temperature required by urea pyrolysis after being heated by the primary air-steam heat exchangers, so that the hot primary air electric heater completely replaces the urea pyrolysis under the full-load working condition.
The utility model discloses a wind-steam heat exchanger not only can satisfy denitration system safety, steady operation for traditional electric heater, still can solve the high problem of urea pyrolysis power consumption, and the heat source adopts the steam turbine to take out steam simultaneously, has expanded greatlyThe depth of the regenerative steam extraction utilization achieves the purposes of saving station power consumption and reducing the loss of a cold source, thereby reducing the energy consumption of unit operation. Taking a certain 600MW unit as an example, the annual average operating power of the primary hot wind electric heater for SCR flue gas denitration urea pyrolysis reaches 980kW, and the annual power consumption of the primary hot wind electric heater is up to 6.37 multiplied by 10 calculated according to 6500 hours of annual denitration operation6kW & h, calculated as the price of power on the internet is 0.4 yuan/(kW & h), and the annual power consumption cost reaches about 254 ten thousand yuan. And the steam extraction heating is adopted, only 660 tons of standard coal are consumed, and the energy consumption is only 49.5 ten thousand yuan calculated by 750 yuan per ton. Therefore, the SCR flue gas denitration system adopting the urea pyrolysis method for preparing ammonia has obvious electricity-saving and energy-saving effects.
It should be noted that the above detailed description describes specific embodiments of the present invention. According to the number and the connection mode of the heat exchangers, different heat sources of the heat exchangers and other system connection modes with various arrangement combinations, it can be understood that the invention aims to provide a method and a system for heating denitration primary air by steam. Many modifications and variations will be apparent to those of ordinary skill in the art in light of the above teachings without undue experimentation. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning or limited experiments based on the existing methods according to the concept of the present invention should be within the scope of protection defined by the claims.
Claims (3)
1. An SCR flue gas denitration system for preparing ammonia by urea pyrolysis at least comprises a urea solution storage tank, a feeding pump, a metering and distributing device, an atomizing spray gun, a pyrolysis furnace, an ammonia spraying grid, an SCR reactor and a denitration hot primary air duct, and is characterized by also comprising a primary air-steam heat exchanger and a primary air-steam heat exchanger steam side pipeline, wherein the primary air-steam heat exchanger heats the denitration hot primary air; the urea solution with a certain concentration in the urea solution storage tank enters the pyrolysis furnace through the feeding pump, the metering and distributing device and the atomizing spray gun, and the denitration hot primary air passes through the primary air-steam heat exchanger and is heated to the temperature required by pyrolysis and then passes through the pyrolysis furnaceA denitration hot primary air duct which enters the pyrolysis furnace and provides heat for the pyrolysis of urea and the product NH after the pyrolysis3To the SCR reactor.
2. The SCR flue gas denitration system for ammonia production by urea pyrolysis according to claim 1, wherein the primary air-steam heat exchanger comprises at least one heat exchanger.
3. The SCR flue gas denitration system for producing ammonia by urea pyrolysis according to claim 1, wherein a steam source of the primary air-steam heat exchanger is high-temperature extracted steam of a steam turbine.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113713610A (en) * | 2021-09-14 | 2021-11-30 | 南京中电环保科技有限公司 | Efficient energy-saving denitration modification method suitable for coal-fired power plant |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113713610A (en) * | 2021-09-14 | 2021-11-30 | 南京中电环保科技有限公司 | Efficient energy-saving denitration modification method suitable for coal-fired power plant |
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