CN214891137U - Pulverized coal and ammonia mixed fuel preheating and decomposing combustion system - Google Patents

Pulverized coal and ammonia mixed fuel preheating and decomposing combustion system Download PDF

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Publication number
CN214891137U
CN214891137U CN202121160276.8U CN202121160276U CN214891137U CN 214891137 U CN214891137 U CN 214891137U CN 202121160276 U CN202121160276 U CN 202121160276U CN 214891137 U CN214891137 U CN 214891137U
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ammonia
pyrolysis
pulverized coal
communicated
boiler
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张向宇
陆续
王志超
张波
向小凤
徐宏杰
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Xian Thermal Power Research Institute Co Ltd
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Xian Thermal Power Research Institute Co Ltd
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Abstract

The utility model discloses a pulverized coal and ammonia mixed fuel pre-pyrolysis combustion system, which comprises a boiler, wherein each layer of combustor of the boiler is communicated with a pyrolysis furnace through a transition flue, after the pulverized coal is mixed with primary air, the pulverized coal is communicated with the inlet of each pyrolysis furnace in a multipath way, and secondary air is communicated with each pyrolysis furnace in a tangential way; an outlet of the liquid ammonia storage tank is communicated with a liquid ammonia inlet of the evaporator, ammonia at an ammonia outlet of the evaporator is communicated with an ammonia nozzle of each transition flue through a main ammonia pipeline in a multi-path ammonia branch pipeline, a main adjusting valve is arranged on the main ammonia pipeline, and an adjusting valve is arranged on each ammonia branch pipeline; the system of the utility model has the advantages of large-proportion mixed burning of ammonia and low nitrogen oxide emission.

Description

Pulverized coal and ammonia mixed fuel preheating and decomposing combustion system
Technical Field
The utility model relates to a mix ammonia fuel power generation technology specifically is a buggy and ammonia mixed fuel preheat and separate combustion system.
Background
At present, the carbon dioxide emission of coal-fired power generation in China is about 540 g/kilowatt hour, and the reduction of the carbon dioxide emission of coal-fired boilers of thermal power plants still has great potential. In order to reduce the carbon emission, the thermal power plant needs to change the traditional coal-fired power generation mode with high carbon emission, and the coal and carbon reduction is realized by burning carbon-free fuels, such as biomass, hydrogen, ammonia and other alternative fuels, at the front end.
Ammonia has fuel properties with energy density comparable to fossil fuels, and direct combustion of ammonia can reduce energy losses in the cracking to hydrogen. On the other hand, ammonia is a renewable clean carbon-free fuel, greenhouse gas emission is avoided in the combustion process, and under the large background of carbon peak and carbon neutralization, the development and utilization of an efficient low-pollution combustion technology of ammonia can become one of effective ways for solving the problem of fossil energy substitution and realizing reduction of carbon emission of thermal power units.
The laminar flame speed of ammonia is low, and the ammonia is difficult to independently and stably combust, and the blending of ammonia and hydrocarbon fuel is a main means for improving the combustion rate of ammonia. Research shows that the boiler efficiency is reduced due to the fact that the ammonia mixing proportion is improved, for a coal-fired boiler, the existing ammonia mixing proportion is difficult to break through 10%, and a new combustion technology needs to be developed to achieve ammonia mixing in a larger proportion.
The fuel nitrogen content in ammonia is too high, and high unburned ammonia and nitrogen oxides generally exist in tail gas, so how to reduce the emission of nitrogen oxides while ensuring stable combustion is a main bottleneck restricting the utilization of ammonia fuel.
Disclosure of Invention
To the problem that exists among the prior art, the utility model provides a system of coal powder and ammonia co-combustion electricity generation that ammonia, low nitrogen oxide discharged is mixed to big proportion.
The utility model discloses a realize through following technical scheme:
a pulverized coal and ammonia mixed fuel preheating and decomposing combustion system comprises a boiler 8, wherein each layer of combustor of the boiler 8 is communicated with a pyrolysis furnace through a transition flue, pulverized coal 1 and primary air 2 are mixed and then communicated with the inlet of each pyrolysis furnace in a multipath manner, and secondary air 3 is communicated with each pyrolysis furnace in a tangential direction; 9 exports of liquid ammonia storage tank communicate 10 liquid ammonia entry of evaporimeter, and the ammonia 11 of the ammonia export of evaporimeter 10 divides the ammonia branch road to communicate the ammonia spout of every transition flue after passing through the ammonia main line, is provided with total governing valve 12 on the ammonia main line, sets up the governing valve on every way ammonia branch road.
When the boiler 8 operates with variable load, the pyrolysis furnaces with corresponding quantity are started and stopped according to the load.
The number of the pyrolysis furnaces is 2-4.
The working method of the pulverized coal and ammonia mixed fuel preheating and decomposing combustion system comprises the following steps:
1) mixing the pulverized coal 1 and primary air 2, and respectively feeding the pulverized coal and the primary air into a first pyrolysis furnace in multiple paths; the secondary air 3 is tangentially fed into the first pyrolysis furnace to provide oxygen for combustion supporting and simultaneously carries pulverized coal to rotate and advance along the wall; in a first pyrolysis furnace, coal powder 1 is subjected to pyrolysis reaction to generate pyrolysis gas, and the main components of the generated pyrolysis gas are carbon monoxide, methane and hydrogen;
2) after liquid ammonia in the liquid ammonia storage tank 9 enters the evaporator 10, the liquid ammonia is gasified into ammonia gas 11 through heat absorption; the ammonia 11 is sprayed into the transition flue of the corresponding layer through the corresponding ammonia nozzle, and in the transition flue, the ammonia 11 is mixed with the pyrolysis gas and reduces the nitrogen oxide in the pyrolysis gas;
3) pyrolysis gas and ammonia gas 11 enter the boiler 8 through each layer of transition flue of the boiler 8 to be combusted, the pyrolysis gas generates carbon dioxide and water after being combusted, the ammonia gas 11 generates nitrogen and water after being combusted, and heat released by combustion reaction is used for generating power by the boiler;
4) when 8 variable load operation of boiler, open according to the load and stop corresponding quantity's pyrolysis oven, specifically do: increasing the number of the pyrolysis furnaces in operation at high load, and reducing the number of the pyrolysis furnaces in operation at low load; when each pyrolysis furnace is started, opening a corresponding ammonia nozzle and a corresponding regulating valve; when the pyrolysis furnace is shut down, closing the corresponding ammonia nozzle and the corresponding regulating valve; the mixing proportion of ammonia gas and pulverized coal is adjusted through the main adjusting valve 12, the flow of ammonia in each layer of combustor is finely adjusted through each layer of adjusting valve, and the stable combustion of low nitrogen oxides of ammonia is realized.
Compared with the prior art, the utility model discloses following profitable technological effect has:
the flame speed of the coal gasification gas is not lower than that of natural gas, the fuel cost is also lower than that of natural gas, the source is more stable than that of natural gas, the influence of market price floating is small, and the cost of ammonia fuel power generation can be reduced by adopting the coal gasification gas mixed with ammonia for combustion.
The main components of the coal gasification gas are hydrogen and carbon monoxide, the flame speed of the hydrogen and the carbon monoxide can be improved simultaneously by adding ammonia into the carbon monoxide, and the flame speed can be improved to the maximum degree by using the hydrogen as the blending fuel of the ammonia, so that the flame stability of ammonia combustion is improved, and the blending proportion of the ammonia is improved. Meanwhile, ammonia is a carbon-free fuel, and the carbon emission in the coal-fired power generation process can be reduced by high-proportion blending of ammonia gas in the coal-fired boiler.
In a high-temperature strong-reducibility flue gas environment, the sprayed ammonia generates a chain reaction to generate OH and H free radicals, and the reaction of the ammonia and the nitrogen oxides can be promoted, so that the concentration of the nitrogen oxides in the coal gasification gas is reduced. When the coal gasification gas and the ammonia are mixed to be combusted, the carbon monoxide and the oxygen are combined more quickly, so that the reaction of the ammonia and the excessive oxygen can be inhibited, and the emission of nitrogen oxides in the ammonia combustion process is reduced.
The utility model discloses in arrange a pyrolysis oven in every layer of combustor department of boiler, the thermal power of every pyrolysis oven equals, can reduce the volume and the manufacturing cost of pyrolysis oven. The pyrolysis furnace adopts a cyclone gasification mode, so that the retention time of coal powder in the furnace can be prolonged, and the proportion of combustible components in gasified gas can be improved. The tail part of each pyrolysis furnace is provided with an independent ammonia nozzle and an independent regulating valve, the start and stop of the pyrolysis furnace are flexibly adjusted according to the load change of the unit, and the mixing proportion of ammonia and coal powder is adjusted, so that the variable load response speed of the unit is increased.
Drawings
Fig. 1 is a schematic view of the pulverized coal and ammonia mixed fuel preheating and decomposing combustion system of the present invention.
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings and specific examples, which are given by way of illustration and not of limitation.
Utility model
As shown in fig. 1, the system for pre-pyrolysis combustion of pulverized coal and ammonia mixed fuel in the embodiment includes a boiler 8, two layers of burners of the boiler 8 are respectively communicated with a first pyrolysis furnace 4 and a second pyrolysis furnace 5 through a first layer transition flue 6 and a second layer transition flue 7, pulverized coal 1 is mixed with primary air 2 and then communicated with inlets of the first pyrolysis furnace 4 and the second pyrolysis furnace 5 in two ways, and secondary air 3 is communicated with the first pyrolysis furnace 4 and the second pyrolysis furnace 5 tangentially; an outlet of the liquid ammonia storage tank 9 is communicated with a liquid ammonia inlet of the evaporator 10, ammonia 11 at an ammonia outlet of the evaporator 10 passes through an ammonia main pipeline and then is divided into two paths of ammonia branches to be respectively communicated with ammonia nozzles of the first layer transition flue 6 and the second layer transition flue 7, a main adjusting valve 12 is arranged on the ammonia main pipeline, and a first layer adjusting valve 13 and a second layer adjusting valve 15 are respectively arranged on the two paths of ammonia branches.
The working method of the pulverized coal and ammonia mixed fuel preheating and decomposing combustion system in the embodiment is as follows:
1) the pulverized coal 1 and the primary air 2 are mixed and then are respectively sent into a first pyrolysis furnace 4 and a second pyrolysis furnace 5. The secondary air 3 is tangentially sent into the first pyrolysis furnace 4 and the second pyrolysis furnace 5, provides oxygen for combustion supporting, and simultaneously carries pulverized coal to rotate and advance along the wall. The first layer pyrolysis furnace 4 is connected with a first layer combustor of a boiler 8 through a first layer transition flue 6, the second layer pyrolysis furnace 5 is connected with a second layer combustor of the boiler 8 through a second layer transition flue 7, and the number of the pyrolysis furnaces is 2-4.
2) In the pyrolysis furnace, coal powder 1 is subjected to pyrolysis reaction to generate pyrolysis gas, and the reaction equation is as follows: 2CHxOy+(1-y)O2→2CO+xH2,3C+2O2→2CO+CO2,CO2+ C → 2CO, the main components of the generated pyrolysis gas are carbon monoxide, methane and hydrogen.
3) Liquid ammonia is stored in a liquid ammonia storage tank 9, and the liquid ammonia storage tank 9 is connected with a vaporizer 10.After entering the evaporator 10, the liquid ammonia is gasified into ammonia gas 11 by heat absorption. The ammonia gas 11 is sprayed into the first layer transition flue 6 through the first layer ammonia nozzle 14, is sprayed into the second layer transition flue 7 through the second layer ammonia nozzle 16, is mixed with the pyrolysis gas and reduces the nitrogen oxide in the pyrolysis gas, and the reaction equation is NOx+NH3→N2+H2And O. The pyrolysis gas and the ammonia gas 11 enter the boiler 8 through the transition flue to be combusted, the pyrolysis gas generates carbon dioxide and water after being combusted, and the reaction equation is CO + O2→CO2,H2+O2→H2And O. The ammonia gas 11 is combusted to produce nitrogen and water, and the reaction equation is O2+NH3→NO+H2O,O2+NO→NO2,NO+NO2+NH3→N2+H2And O. The heat released by the combustion reaction is used for generating power by a boiler.
4) When 8 variable load operation of boiler, open according to the load and stop corresponding quantity's pyrolysis oven, specifically do: the number of pyrolysis furnaces put into operation is increased at high load, and the number of pyrolysis furnaces put into operation is decreased at low load. When each pyrolysis furnace is started, opening a corresponding ammonia nozzle and a corresponding regulating valve; and when the pyrolysis furnace is shut down, closing the corresponding ammonia nozzle and the corresponding regulating valve. The mixing proportion of ammonia gas and pulverized coal is adjusted through the main adjusting valve 12, and the flow of ammonia in each layer of combustor is finely adjusted through the first layer adjusting valve 13 and the second layer adjusting valve 15, so that the stable combustion of low nitrogen oxides of ammonia is realized.

Claims (4)

1. A pulverized coal and ammonia mixed fuel preheating and pyrolysis combustion system is characterized by comprising a boiler (8), wherein each layer of combustor of the boiler (8) is communicated with a pyrolysis furnace through a transition flue, pulverized coal (1) is mixed with primary air (2) and then communicated with an inlet of each pyrolysis furnace in a multipath manner, and secondary air (3) is communicated with each pyrolysis furnace in a tangential manner; an outlet of the liquid ammonia storage tank (9) is communicated with a liquid ammonia inlet of the evaporator (10), ammonia (11) at an ammonia outlet of the evaporator (10) is communicated with an ammonia nozzle of each transition flue through a main ammonia pipeline by a plurality of paths of ammonia branches, a main adjusting valve (12) is arranged on the main ammonia pipeline, and an adjusting valve is arranged on each path of ammonia branch.
2. The pre-pyrolysis combustion system of pulverized coal and ammonia mixed fuel according to claim 1, characterized in that when the boiler (8) is operated with variable load, a corresponding number of pyrolysis furnaces are started and stopped according to the load.
3. The pre-pyrolysis combustion system for pulverized coal and ammonia mixed fuel as claimed in claim 1, wherein the number of the pyrolysis furnaces is 2-4.
4. The pulverized coal and ammonia mixed fuel pre-pyrolysis combustion system according to claim 1, wherein pulverized coal pyrolysis gas and ammonia gas are mixed and then fed into a boiler (8) for combustion, and the released heat is used for boiler power generation.
CN202121160276.8U 2021-05-27 2021-05-27 Pulverized coal and ammonia mixed fuel preheating and decomposing combustion system Active CN214891137U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113154369A (en) * 2021-05-27 2021-07-23 西安热工研究院有限公司 Pulverized coal and ammonia mixed fuel preheating and decomposing combustion system and method

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113154369A (en) * 2021-05-27 2021-07-23 西安热工研究院有限公司 Pulverized coal and ammonia mixed fuel preheating and decomposing combustion system and method

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