CN210473607U - Full-load SCR denitration system of coal-fired boiler - Google Patents

Full-load SCR denitration system of coal-fired boiler Download PDF

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Publication number
CN210473607U
CN210473607U CN201920742864.9U CN201920742864U CN210473607U CN 210473607 U CN210473607 U CN 210473607U CN 201920742864 U CN201920742864 U CN 201920742864U CN 210473607 U CN210473607 U CN 210473607U
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air
heater
coal
door
fired boiler
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刘岗
任建兴
陈宏礼
郝红亮
程海松
侯国
黄玉妹
沈洪洪
张莉
陈春彦
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Shanghai University of Electric Power
University of Shanghai for Science and Technology
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Shanghai University of Electric Power
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Abstract

The utility model relates to a coal fired boiler full load SCR deNOx systems, including denitration reactor, air preheater, the air preheater includes flue gas duct and air duct, the flue export of denitration reactor passes through the flue gas duct and the electrostatic precipitator device of air preheater are connected, the input and the forced draught blower of air duct of air preheater are connected, and the output is connected with the secondary bellows, and this system still includes the air heater, the input of air heater is connected with the output that closes on the pressure cylinder extraction opening of generating set steam turbine and air duct of air preheater respectively, the output of air heater with the flue access connection of denitration reactor. Compared with the prior art, the utility model discloses not only can guarantee that coal fired boiler satisfies full load, full period steady operation more than minimum technical output, NOx discharges in the flue gas and reaches the emission requirement that the country formulated, can also realize the operation of the real full load denitration of the back of being incorporated into the power networks.

Description

Full-load SCR denitration system of coal-fired boiler
Technical Field
The utility model relates to a waste gas purification and energy environmental protection field among the coal fired power generation especially relate to a coal fired boiler full load SCR deNOx systems.
Background
The energy structure mainly based on coal in China can not be changed for a long time, so that the control of NOx emission in the combustion flue gas of a coal-fired boiler is an important work for treating atmospheric environmental pollution in China. By NH3The NOx Selective Catalytic Reduction (SCR) technology which is a reducing agent is the most widely and effectively coal-fired boiler flue gas denitration technology which is applied in the coal-fired power generation industry in recent years.
The Selective Catalytic Reduction (SCR) technology has the advantages that flue gas has a certain temperature range according to different requirements of adopted catalysts, NOx is Selectively Catalytically Reduced (SCR) in the temperature range, the emission concentration of NOx in coal-fired flue gas is reduced, the temperature requirement can be met during the high-load running period of an actual coal-fired boiler, but the flue gas temperature often cannot reach the working temperature required by the Selective Catalytic Reduction (SCR) technology when the boiler is started, stopped and runs at low load, so that an SCR denitration device cannot have the working temperature required by the Selective Catalytic Reduction (SCR) technology, and the SCR denitration device cannot have the working temperatureEffectively remove NOx in the boiler flue gas. And environmental protection department letter (Ring letter [2015 ]]Number 143) explicitly states: the thermal power plant must reach the standard for emission under any operating load, so that the emission concentration of NOx cannot reach the national emission standard of 50mg/m3The thermal power generating unit is required to realize the full-load SCR denitration operation of the coal-fired boiler through technical transformation.
The catalyst of the conventional coal-fired power plant is applicable to a temperature of 300-420 ℃, if the catalyst is operated below the lowest ammonia injection temperature for a long time, the catalyst loses activity rapidly, and meanwhile, after ammonium sulfate salt is precipitated on the surface of the catalyst, dust in flue gas can be adhered to the surface of the catalyst at the same time to cause the blocking phenomenon of the catalyst, and the activity of the catalyst cannot be completely recovered by heating, so that the catalyst is operated below the lowest ammonia injection temperature for a long time, the influence on the chemical life of the catalyst is large, particularly the coal-fired power plant with high dust content, and therefore, the whole temperature of the flue gas in a denitration reaction area must be improved in low-load stages such as startup and shutdown.
Therefore, how to effectively solve the problem of commissioning of the SCR denitration device under the conditions of starting of the generator set and low-load operation becomes a key problem in the field of flue gas denitration of the current coal-fired boiler.
In the prior art, for example, patent CN 201510701175. X- "full-load low NOx device of economizer sectional boiler and transformation method" is to arrange the economizers in sections to meet the requirement of low-load denitration operation of coal-fired boiler, but this method has a large transformation amount for the active coal-fired generator set, and because the problem of over-temperature of the full-load operation unit must be considered, the detection range under low load is limited, and the denitration operation of the SCR denitration device system at the unit start-up stage cannot be realized.
In the prior art, for example, patent CN 204962817U- "SCR flue gas denitration system operated under full load condition", a post-combustion device is arranged on a denitration flue between a boiler economizer and an SCR flue gas denitration reactor, and the flue gas temperature during the period from boiler ignition to non-steady combustion load under the minimum steady combustion load condition is increased by the post-combustion device, so that full load flue gas denitration under any load of the boiler from ignition to 100% BMCR working condition is realized. However, this method requires additional fuel consumption to raise the temperature of the boiler flue gas, and thus has the problem of high unit operation cost.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a coal fired boiler full load SCR deNOx systems just in order to overcome the SCR denitrification facility that above-mentioned prior art exists the defect that the system can not drop into normal operating when the unit opens machine and low-load operation.
The purpose of the utility model can be realized through the following technical scheme:
the utility model provides a coal fired boiler full load SCR deNOx systems, includes denitration reactor, air preheater, the air preheater includes flue gas duct and air duct, the flue outlet of denitration reactor passes through the flue gas duct of air preheater is connected with electrostatic precipitator device, the input and the forced draught blower of air duct of air preheater are connected, and the output is connected with the secondary bellows, and this system still includes the air heater, the input of air heater is connected with the pressure cylinder extraction opening that closes on the generating set steam turbine and the output of air duct of air preheater respectively, the output of air heater with the flue access connection of denitration reactor.
Preferably, a first adjusting door assembly is arranged on a connecting pipeline between the input end of the air heater and the suction opening of the pressure cylinder close to the steam turbine of the generator set.
Preferably, the first adjusting door assembly comprises a manual door in front of the steam supply electric door of the air heater, a steam supply adjusting door of the air heater and a manual door behind the steam supply adjusting door of the air heater, which are sequentially arranged from the air suction opening of the pressure cylinder to the input end direction of the air heater.
Preferably, a second adjusting door assembly is arranged on a connecting pipeline between the input end of the air heater and the output end of the air channel of the air preheater.
Preferably, the second adjusting door assembly comprises a hot secondary air to warm air device door adjusting front manual door, a hot secondary air to warm air device door adjusting, a hot secondary air to warm air device electric door and a hot secondary air to warm air device electric door rear manual door which are sequentially arranged from the output end of the air channel of the air preheater to the input end direction of the warm air device.
Preferably, the air heater is also connected with a steam trap.
Preferably, one end of the steam trap connected with the air heater is provided with a front manual door of the steam trap, and the other end of the steam trap is provided with a rear manual door of the steam trap.
Preferably, an air inlet filter screen of the air heater is arranged at the input end of the air heater connected with the output end of the air channel of the air preheater.
Preferably, the denitration reactor is connected with a boiler body started by coal-fired oil-free ignition.
Preferably, a flue gas adjusting baffle is arranged at the joint of the boiler body and the denitration reactor.
Compared with the prior art, the utility model has the advantages of it is following:
1. utilize and close to generating set extraction steam and realize self coal fired boiler full load denitration operation, according to boiler operation demand promptly, from closing on generating set extraction part high temperature steam, heat the required hot overgrate air of boiler, hot air temperature control after will heating is above 330 ℃, directly spout SCR denitrification facility catalyst entry, under the effect of hot overgrate air, improve the whole temperature level of SCR denitrification facility catalyst, not only can guarantee coal fired boiler and satisfy full load more than the minimum technological output, the stable operation of full period, NOx discharges and reaches the emission requirement that the country made in the flue gas, can also realize the full load denitration operation in the real meaning after being incorporated into the power networks (more than 0MW, even after the ignition).
2. After a part of high-temperature pure hot air is mixed with the original hot flue gas in the tail flue, the content of NOx in the flue gas in unit volume is reduced, the actual ammonia spraying amount in unit time is also reduced, the NOx removal is facilitated, and the ammonia escape is reduced, and the prevention and control of Ammonium Bisulfate (ABS) accumulation of the air preheater under low load are facilitated.
3. Because the unit started by coal-fired oil-free ignition is adopted, the boiler is ignited for at least more than 3 hours before grid connection, the inlet flue gas temperature of a denitration catalyst reaction area has higher temperature, less hot air needs to be supplemented, and the temperature condition of denitration operation can be met.
4. By adjusting the flue gas adjusting baffle, the heat absorption of the working medium in the economizer pipe to the flue gas in the tail flue is reduced as much as possible, so that the original flue gas temperature of the catalyst reaction area is further increased.
5. The electric adjusting door is arranged on the steam inlet pipeline of the air heater, so that the temperature of on-line hot air compensation can be adjusted, and the accurate control of the air temperature can be realized.
6. A manual stop gate and an electric stop gate are arranged on a steam inlet pipeline of the air heater, so that the system pipeline is conveniently isolated, and equipment is conveniently overhauled when a unit operates.
7. When the unit is started or stopped, the air feeder has large margin, which is beneficial to hot air supplement in the denitration catalyst reaction area.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention;
fig. 2 is a schematic structural diagram of the system in the embodiment.
The figure is marked with: 1. the system comprises a heater steam supply electric door, a heater steam supply adjusting door rear manual door, a steam trap front manual door, a steam trap, a 7 steam trap rear manual door, a 8 steam trap bypass door, a 9 steam trap air inlet filter screen, a 10 steam blower outlet flow meter, a 11 steam blower outlet electric door, a 12 boiler body, a 13 steam secondary air to heater electric door rear manual door, a 14 steam secondary air to heater electric door, a 15 steam secondary air to heater electric door, a 16 steam secondary air to heater air adjusting door, a 17 steam trap reactor, a 18 air preheater, a 19 steam blower, a 20, an electrostatic dust removal device, a 21, a secondary air box, a 22 air heater.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.
Examples
The denitration system of coal fired boiler full load SCR is proposed to the unable operation problem of SCR denitrification facility when coal fired unit starts or low-load operation, reduces nitrogen oxide and discharges in this application. Under the normal condition, because the installed quantity of the coal-fired generating sets is generally configured with more than two sets, when more than one set operates, and the other set operates at the stage of starting or stopping, the system heats the hot secondary air of the set which is started or stopped by utilizing the high-temperature steam extraction of the operating set, and the further heated high-temperature secondary air is uniformly sprayed into a catalyst reaction area through reasonable flow field optimization and can directly improve the temperature field of the catalyst reaction area after being mixed with the original hot flue gas in the tail flue.
As shown in fig. 1, the present system includes a denitration reactor 17, an air preheater 18, and a heater 22. The air preheater 18 comprises a flue gas channel and an air channel, the flue gas channel of the air preheater 18 is connected with the electrostatic dust removal device 20, the input end of the air channel of the air preheater 18 is connected with the blower 19, and the output end of the air channel is connected with the secondary air box 21. The input end of the air heater 22 is respectively connected with the extraction opening of the pressure cylinder close to the turbine of the generator set (hereinafter referred to as the temporary machine) and the output end of the air channel of the air preheater 18, and the output end of the air heater 22 is connected with the flue inlet of the denitration reactor 17.
After the air supplied by the blower 19 is heated by the air preheater 18, most of the air is fed into the secondary air box 21 and is introduced into the hearth for combustion supporting, and the other small part of the air is heated and heated by the air heater 22 of a heat source provided by high-temperature steam extraction provided by the machine, so that the air is used as hot air supplement of a denitration reaction area, and after the hot air supplement and tail flue gas are uniformly mixed, the temperature of the flue gas is raised to be more than 290 ℃, so that the temperature of the flue gas reaches the temperature of denitration catalytic reaction.
A first adjusting door assembly is arranged on a connecting pipeline between the input end of the air heater 22 and the suction opening of the pressure cylinder close to the air heater. The first adjusting door assembly comprises a front manual door 1 of the steam supply electric door of the air heater, a steam supply electric door 2 of the air heater, a steam supply adjusting door 3 of the air heater and a rear manual door 4 of the steam supply adjusting door of the air heater, which are sequentially arranged from the suction opening of the pressure cylinder to the input end direction of the air heater 22.
A second regulating door assembly is provided on the connecting line between the inlet of the air heater 22 and the outlet of the air passage of the air preheater 18. The second adjusting door assembly comprises a hot secondary air to heater air adjusting front manual door 16, a hot secondary air to heater air adjusting door 15, a hot secondary air to heater air electric door 14 and a hot secondary air to heater air electric door rear manual door 13 which are sequentially arranged from the output end of the air channel of the air preheater 18 to the input end direction of the air heater 22. An air inlet filter screen 9 of the air heater is arranged at an input port of the air heater 22 connected with the output end of the air channel of the air preheater 18.
The heater 22 is also connected to the steam trap 6. One end of the steam trap 6 connected with the air heater 22 is provided with a front manual door 5 of the steam trap, and the other end of the steam trap 6 is provided with a rear manual door 7 of the steam trap. The front steam trap manual door 5, the steam trap 6 and the rear steam trap manual door 7 form a steam trap bypass door 8.
A blower outlet flowmeter 10 and a blower outlet electric door 11 are provided on a pipeline between the blower 19 and the air preheater 18.
The denitration reactor 17 is connected with a boiler body 12 started by coal-fired oil-free ignition. The flue gas adjusting baffle is arranged at the joint of the boiler body 12 and the denitration reactor 17, so that the heat absorption of the working medium in the economizer pipe to the flue gas in the tail flue can be reduced as much as possible, and the original flue gas temperature of the catalyst reaction area is further improved.
As shown in fig. 2, in the system of the present embodiment, a full-load denitration system of a boiler is implemented by using 5 stages of post-extraction steam of a temporary intermediate pressure cylinder.
Because the temperature of the third pump after the 5-stage intermediate pressure cylinder is high, the system selects the temperature of the third pump, and the working parameters of the system are shown in the table 1. In the embodiment, the steam extraction temperature under the THA working condition (heat rate acceptance working condition) is 456.5 ℃, the temperature reaches about 520 ℃ after the medium-pressure 5-stage operation in the actual operation, the temperature change of the unit is small during the load change period, the enthalpy drop of the steam in the unit operation is mainly reflected in the change of the pressure, the steam grade is high, and the heat exchange effect is good.
The three-pumping steam pressure is about 1.924MPa under the THA working condition (heat consumption rate acceptance working condition), and about 2.056MPa under the VWO (valve full-open working condition), so that the pressure is low, the arrangement of the field pipelines of the system is convenient, and the investment is saved.
TABLE 1 operating parameters of the system
Because the boiler is ignited for about 3 hours before grid connection, the flue gas temperature at the denitration inlet reaches more than 250 ℃, the denitration operation condition can be met only by increasing the flue gas temperature by 40 ℃, so that less hot air needs to be supplemented, and the denitration operation condition can be met.

Claims (10)

1. The full-load SCR denitration system of the coal-fired boiler comprises a denitration reactor (17) and an air preheater (18), wherein the air preheater (18) comprises a flue gas channel and an air channel, a flue gas outlet of the denitration reactor (17) is connected with an electrostatic dust removal device (20) through the flue gas channel of the air preheater (18), the input end of the air channel of the air preheater (18) is connected with a blower (19), and the output end of the air channel of the air preheater (18) is connected with a secondary air box (21).
2. The coal-fired boiler full load SCR deNOx system of claim 1, wherein, the connecting pipeline between the input end of the air heater (22) and the pressure cylinder extraction opening adjacent to the generating set steam turbine is provided with a first adjusting door assembly.
3. The coal-fired boiler full-load SCR denitration system according to claim 2, wherein the first adjusting door assembly comprises a front manual door (1) of the steam supply electric door of the air heater, a steam supply electric door (2) of the air heater, a steam supply adjusting door (3) of the air heater and a rear manual door (4) of the steam supply adjusting door of the air heater, which are sequentially arranged from a suction opening of the pressure cylinder to the input end direction of the air heater (22).
4. The coal-fired boiler full load SCR denitration system according to claim 1, wherein a second adjusting door assembly is provided on a connection pipeline between an input end of the air heater (22) and an output end of an air passage of the air preheater (18).
5. The coal-fired boiler full load SCR denitration system according to claim 4, wherein the second adjusting door assembly comprises a hot overair to heater damper front manual door (13), a hot overair to heater damper door (14), a hot overair to heater damper electric door (15) and a hot overair to heater damper rear manual door (16) which are sequentially arranged from the output end of the air channel of the air preheater (18) to the input end of the heater (22).
6. The coal-fired boiler full load SCR denitration system according to claim 1, wherein the air heater (22) is further connected with a steam trap (6).
7. The coal-fired boiler full-load SCR denitration system according to claim 6, wherein one end of the steam trap (6) connected with the air heater (22) is provided with a manual door (5) in front of the steam trap, and the other end of the steam trap (6) is provided with a manual door (7) behind the steam trap.
8. The full-load SCR denitration system of a coal-fired boiler according to claim 1, wherein an inlet end of the air heater (22) connected with an outlet end of an air channel of the air preheater (18) is provided with an air inlet filter screen (9) of the air heater.
9. The full-load SCR denitration system of a coal-fired boiler according to claim 1, wherein the denitration reactor (17) is connected with a boiler body (12) which is started by oil-free ignition of coal.
10. The coal-fired boiler full load SCR deNOx systems of claim 9, wherein the junction of denitration reactor (17) in boiler body (12) is equipped with flue gas damper.
CN201920742864.9U 2019-05-22 2019-05-22 Full-load SCR denitration system of coal-fired boiler Active CN210473607U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112432197A (en) * 2020-11-20 2021-03-02 胜利国电(东营)热电有限公司 SCR inlet flue gas temperature reheating device and method based on boiler secondary air

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112432197A (en) * 2020-11-20 2021-03-02 胜利国电(东营)热电有限公司 SCR inlet flue gas temperature reheating device and method based on boiler secondary air

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