Coal-fired power plant coupled with ammonia production and ammonia-doped combustion system

Abstract

A coal-fired power plant coupled ammonia production and ammonia-doped combustion system, comprising a plurality of groups of sequentially connected raw coal bunker, coal feeder and coal mill, the air inlet of the coal mill is connected with the air outlet of the boiler, and the discharge port of the coal mill is connected with the pulverized coal inlet of the boiler through a shut-off valve, characterized in that: the first and second raw coal bunkers are divided into two bins by a partition; the discharge ports at the lower ends of the two bins are connected with the coal feeder through electric gates; the shut-off valves on the discharge port pipelines of the first and second coal mills are two and are sequentially a first shut-off valve and a second shut-off valve, and a third shut-off valve is connected between the first and second shut-off valves to connect a discharge chute, the discharge ports of the two discharge chutes are connected with coal slurry tanks through low-pressure coal slurry pumps, the discharge ports at the lower ends of the two coal slurry tanks are connected with the inlets of the two sides of a coal gasification furnace through high-pressure coal slurry pumps, and the outlet at the upper end of the coal gasification furnace is connected with a liquid ammonia tank through a synthetic ammonia converter. The system has low investment cost, high combustion efficiency and can reduce carbon emissions of the unit.

Description

Technical Field

[0001] This utility model relates to the field of novel thermal power generation, and in particular to a coal-fired power plant coupled with ammonia production and combustion system. Background Technology

[0002] With the rapid development of installed capacity for new energy wind and solar power, the proportion of residential and tertiary sector electricity consumption in the overall power load is also growing rapidly. Both new energy power generation output and residential and tertiary sector electricity load exhibit strong intraday fluctuations, posing significant challenges to the flexible operation of the power system. Against the backdrop of achieving carbon peaking and carbon neutrality goals, the proposal of a new power system based on new energy sources places even higher demands on the flexibility and regulation of the power system.

[0003] Coal-fired power plant flexibility retrofitting, pumped hydro storage, gas-fired power generation, and energy storage devices are all effective means to improve the power system's regulation capacity. Pumped hydro storage is constrained by site resources, has a long construction period, and low energy efficiency. Gas-fired power is limited by gas source and gas price, and does not have the conditions for large-scale construction. The flexibility of thermal power plants is affected by factors such as main units, and the peak-shaving range is limited. Thermal power plant energy storage is constrained by technical and economic factors and does not yet have the conditions for large-scale commercial application.

[0004] High-frequency and deep peak shaving in thermal power units not only affects the lifespan of the equipment, but the timeliness of peak shaving is also gradually reaching the limits of thermal power units. Ammonia co-firing technology in boilers is not only one of the important technical routes for achieving low-carbon and clean development of thermal power, but it can also build a new interactive "ammonia-electricity" coupling mode on existing thermal power units, making the construction of new power systems an urgent problem to be solved.

[0005] Currently, ammonia production in China is generally carried out independently in chemical plants or energy bases, and then the produced ammonia is sent to thermal power plants to be mixed with coal for combustion. Ammonia production and boiler combustion are separate processes, which not only result in high costs, large land area, and complex systems, but also low boiler ammonia combustion efficiency, making it difficult to promote on a large scale. Utility Model Content

[0006] The technical problem to be solved by this utility model is to provide a coal-fired power plant coupled with ammonia production and combustion system that has low input cost, high combustion efficiency, and can reduce the carbon emissions of the unit.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A coal-fired power plant coupled with ammonia production and combustion system includes multiple sets of raw coal bunkers, coal feeders, and coal mills connected sequentially by pipelines. Each coal mill is connected to a demineralized water supply pipeline and a demineralized water return pipeline. The air inlets of the coal mills are connected to the air outlets of the boiler via air ducts and regulating valves. The discharge outlets of the coal mills are connected to the pulverized coal inlets of the boiler via pipelines and shut-off valves. The system is characterized by: The first and second raw coal silos are divided into two silos by internal partitions, which are used to store fuel coal and ammonia gasification coal respectively. The discharge ports at the lower end of the two silos are connected to the corresponding coal feeders through pipelines and electric gates, which are used to switch the raw materials of the two silos according to the operating status of the boiler. The first and second coal mills each have two shut-off valves on their discharge outlet pipelines, namely the first shut-off valve and the second shut-off valve. A discharge trough is connected between the first and second shut-off valves via a tee and a third shut-off valve, respectively. The discharge outlets at the lower ends of the two discharge troughs are connected to a coal slurry trough via pipelines and a low-pressure coal slurry pump, respectively. The discharge outlets at the lower ends of the two coal slurry troughs are connected to the feed inlets on both sides of a coal gasifier via pipelines and a high-pressure coal slurry pump, respectively. The outlet at the upper end of the coal gasifier is connected to a liquid ammonia tank via a synthetic ammonia conversion furnace. This is used to gasify the raw materials, liquefy them into ammonia through the synthetic ammonia conversion furnace, and then send them to the liquid ammonia tank for storage. The outlet of the liquid ammonia tank is connected to the liquid ammonia vaporizer via a liquid ammonia pump. The heat source inlet of the liquid ammonia vaporizer is connected to the hot primary air outlet of the boiler via a pipeline and a heat source shut-off valve. The ammonia outlet of the liquid ammonia vaporizer is connected to the ammonia burner inside the boiler via a gas supply pipeline.

[0008] A further improvement of this utility model is that: the demineralized water supply pipelines corresponding to the first and second coal mills are respectively connected to the gasification water pipelines via tee connections, and a gasification water shut-off valve is provided on the gasification water pipelines. The other end of the gasification water pipelines is respectively connected to the gasification water inlets of the first and second coal mills.

[0009] A further improvement of this utility model is that a pressure reducing valve and a check valve are sequentially installed on the gas supply pipeline to adjust the ammonia pressure output by the liquid ammonia vaporizer.

[0010] A further improvement of this utility model is that the exhaust port of the liquid ammonia vaporizer is connected to the gas supply pipeline through a pipeline, so that the ammonia gas can be mixed with the cooled hot primary air and then sent into the ammonia burner for combustion.

[0011] A further improvement of this utility model is that a coal feeding gate is provided on the pipeline between the coal feeder and the coal mill to control the coal feeding of the coal mill.

[0012] The beneficial effects of this utility model are as follows: 1. Utilize existing coal bunkers, coal feeders, and coal mills in thermal power units to reduce investment in ammonia production equipment.

[0013] 2. Ammonia is produced when the thermal power unit is running at low load, and the electrical energy is stored in the fuel ammonia to meet the peak shaving needs of the thermal power unit at low load. The unit load can be reduced to zero load, so that the boiler can be shut down without stopping the machine. At high load, the stored fuel ammonia is converted into ammonia gas through a liquid ammonia gasifier and introduced into the ammonia burner in the boiler to replace part of the fuel coal, thereby reducing the carbon emissions of the thermal power unit.

[0014] 3. Liquid ammonia is vaporized and utilized as the boiler's primary hot air. The primary hot air serves as both a heat source and oxygen supply for combustion. Fuel premixing improves the combustion efficiency of ammonia. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the system structure of this utility model.

[0016] In the diagram: 1A (first raw coal bunker), 1B (second raw coal bunker), 1C (third raw coal bunker), 2 (electric gate), 3 (pipeline), 4 (coal feeder), 5 (coal feed gate), 6 (first shut-off valve), 7 (gasification water shut-off valve), 8 (gasification water pipeline), 9 (demineralized water supply pipeline), 10 (demineralized water return pipeline), 11 (water-side shut-off valve), 12A (first coal mill), 12B (second coal mill), 12C (third coal mill), 13 (regulating valve), 14 (heat source shut-off valve). Valve 14, air duct 15, low-pressure coal slurry pump 16, coal slurry tank 17, high-pressure coal slurry pump 18, coal gasification furnace 19, third shut-off valve 20, second shut-off valve 21, discharge chute 22, synthetic ammonia conversion furnace 23, liquid ammonia tank 24, fourth shut-off valve 25, liquid ammonia shut-off valve 26, liquid ammonia pump 27, liquid ammonia gasifier 28, pressure reducing valve 29, check valve 30, gas supply pipeline 31, ammonia burner 32, boiler 33. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to embodiments: like Figure 1 As shown, this utility model relates to a coal-fired power plant coupled with ammonia production and combustion system, which includes multiple raw coal bunkers, coal feeders 4 and coal mills connected in sequence by pipelines. Each coal mill is connected to a demineralized water supply pipeline 9 and a demineralized water return pipeline 10. The air inlet of the coal mill is connected to the air outlet of the boiler through an air duct 15 and a regulating valve 13. The discharge outlet of the coal mill is connected to the pulverized coal inlet of the boiler through a pipeline and a shut-off valve.

[0018] This embodiment takes three sets of raw coal bunkers, coal feeder 4 and coal mill as an example. The raw coal bunkers are the first raw coal bunker 1A, the second raw coal bunker 1B and the third raw coal bunker 1C. The coal mills are the first coal mill 12A, the second coal mill 12B and the third coal mill 12C. Each coal mill has four discharge ports.

[0019] The first and second raw coal bunkers are divided into two equal-sized silos by internal partitions, which are used to store fuel coal and ammonia gasification coal respectively. The discharge ports at the lower end of the two silos are connected to the corresponding coal feeders 4 through pipelines 3 and electric gates 2, respectively, to switch the raw materials of the two silos according to the operating status of the boiler.

[0020] The discharge pipes of the first and second coal mills have two shut-off valves, namely the first shut-off valve 6 and the second shut-off valve 21. The first and second shut-off valves are connected to a discharge chute 22 via a tee, a pipeline, and a third shut-off valve 20. The first and second coal mills each correspond to a discharge chute 22. The discharge ports at the lower ends of the two discharge chute 22 are connected to a coal slurry tank 17 via pipelines and a low-pressure coal slurry pump 16. The discharge ports at the lower ends of the two coal slurry tanks 17 are connected to the inlets on both sides of a coal gasifier 19 via pipelines and a high-pressure coal slurry pump 18. The outlet at the upper end of the coal gasifier 19 is connected to a synthetic ammonia converter 23 via a pipeline. The liquid outlet of the synthetic ammonia converter 23 is connected to a liquid ammonia tank 24 via a pipeline. The raw materials are gasified and then liquefied by the synthetic ammonia converter 23 before being sent to the liquid ammonia tank 24 for storage.

[0021] The outlet of the liquid ammonia tank 24 is connected to the liquid ammonia vaporizer 28 via a pipeline, a liquid ammonia shut-off valve 26, and a liquid ammonia pump 27. The heat source inlet of the liquid ammonia vaporizer 28 is connected to the hot primary air outlet of the boiler 33 via a pipeline and a heat source shut-off valve 14. The ammonia outlet of the liquid ammonia vaporizer 28 is connected to the ammonia burner 32 inside the boiler 33 via a gas supply pipeline 31. A pressure reducing valve 29 and a check valve 30 are sequentially installed on the gas supply pipeline 31 to adjust the ammonia pressure output by the liquid ammonia vaporizer 28. The exhaust port of the liquid ammonia vaporizer 28 is connected to the end of the gas supply pipeline 31 near the boiler 33 via a pipeline and a tee to facilitate the mixing of ammonia with the cooled hot primary air before it is sent to the ammonia burner 32 for combustion.

[0022] Water-side shut-off valves 11 are respectively installed on the demineralized water supply pipeline 9 and the demineralized water return pipeline 10. The demineralized water supply pipeline 9 corresponding to the first and second coal mills is connected to the gasification water pipeline 8 through a tee. A gasification water shut-off valve 7 is installed on the gasification water pipeline 8. The other end of the gasification water pipeline 8 is connected to the gasification water inlet of the corresponding first and second coal mills.

[0023] The discharge ports of the third raw coal bunker 1C are connected to the corresponding coal feeders 4 via pipelines and electric gate valves 2. A coal feed gate valve 5 is installed on the pipeline between the coal feeder 4 and the corresponding coal mill to control the coal feed of the coal mill. A shut-off valve 25 is installed on the discharge port pipeline of the third coal mill 12C, and is the fourth shut-off valve 25, used to control the pulverized coal fed into the boiler 33.

[0024] The coal feeding gate 5, the first shut-off valve 6, the gasification water shut-off valve 7, the water-side shut-off valve 11, the second shut-off valve 21, the third shut-off valve 20, the regulating valve 13, the heat source shut-off valve 14, the liquid ammonia shut-off valve 26, and the pressure reducing valve 29 are all electric valves.

[0025] During operation, the two silos in the first and second raw coal bunkers store fuel coal and ammonia gasification coal respectively, and each first shut-off valve 6 is controlled to be in the normally open state; the specific working principle is as follows: When boiler 33 is running at low load, the electric gate 2 of the corresponding fuel coal silo is closed, and the electric gate 2 for controlling the ammonia gasification coal and the coal feeding gate 5 are opened. The gasified coal is fed into the corresponding coal mill after passing through the electric gate 2, the coal feeder 4, and the coal feeding gate. Each second shut-off valve 21 is closed, each third shut-off valve 20 is opened, the water-side shut-off valve 11 is closed, the gasification water shut-off valve 7 is opened, and the regulating valve 13 of the corresponding first and second coal mills is controlled to adjust the air volume fed into the coal mill. The ammonia raw material formed in the coal mill is sent into the corresponding discharge trough 22, pressurized by the low-pressure coal slurry pump 16 and sent into the coal slurry tank 17. Then, the high-pressure coal slurry pump 18 pressurizes it again to the gasification pressure and sends it into the gasifier 19. After the raw material is gasified, it is sent into the synthetic ammonia conversion furnace 23 to produce ammonia. After liquefaction, it enters the liquid ammonia tank 24 for storage.

[0026] When boiler 33 is running at high load, the electric gate 2 of the corresponding ammonia gasification coal silo is closed, and the electric gate 2 and the coal feeding gate 5 of the fuel coal control are opened. The fuel coal is fed into the corresponding coal mill after passing through the electric gate 2, the coal feeder 4, and the coal feeding gate 5. Each second shut-off valve 21 is opened, each third shut-off valve 20 is closed, the water-side shut-off valve 11 is opened, the gasification water shut-off valve 7 is closed, and the regulating valve 13 of the corresponding first and second coal mills is controlled to adjust the air volume fed into the coal mill, thereby controlling the outlet coal powder temperature. The fuel coal is ground into coal powder in the coal mill and sent to the boiler furnace through the discharge port pipeline. Meanwhile, the liquid ammonia produced during low-load operation is vaporized by the liquid ammonia vaporizer 28 and then sent to the ammonia burner 32 in the boiler 33 for combustion. That is, the liquid ammonia shut-off valve 26 is opened, and the liquid ammonia is pressurized by the liquid ammonia pump 27 and sent into the liquid ammonia vaporizer 28. The heat source for vaporization is taken from the hot primary air of the boiler. The heat source shut-off valve 14 is opened, and the vaporized ammonia gas is mixed with the cooled hot primary air after passing through the pressure reducing valve 29 and the check valve 30 and then sent into the boiler ammonia burner 32 for combustion.

[0027] The third raw coal bunker, which is not divided into separate compartments, is configured in the conventional manner. The fourth shut-off valve 25 is normally open, and the water-side shut-off valve 11 of the corresponding third raw coal bunker 1C is normally open. When the boiler 33 is running at high load, the electric gate and the coal feeding gate are opened. The fuel coal is fed into the coal mill after passing through the electric gate, the coal feeder 4, and the coal feeding gate. The regulating valve C19 of the corresponding third coal mill is controlled to regulate the air volume fed into the third coal mill 12C, thereby controlling the outlet coal powder temperature. At low load, the output of the coal mill is adjusted according to the unit load to meet the boiler load requirements.

[0028] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A coal-fired power plant coupled with ammonia production and combustion system, comprising multiple sets of raw coal bunkers, coal feeders, and coal mills connected sequentially by pipelines, wherein each coal mill is connected to a demineralized water supply pipeline and a demineralized water return pipeline, the air inlet of the coal mill is connected to the air outlet of the boiler via an air duct and a regulating valve, and the discharge outlet of the coal mill is connected to the pulverized coal inlet of the boiler via a pipeline and a shut-off valve, characterized in that: The first and second raw coal silos are divided into two silos by internal partitions, which are used to store fuel coal and ammonia gasification coal respectively. The discharge ports at the lower end of the two silos are connected to the corresponding coal feeders through pipelines and electric gates, which are used to switch the raw materials of the two silos according to the operating status of the boiler. The first and second coal mills each have two shut-off valves on their discharge outlet pipelines, namely the first shut-off valve and the second shut-off valve. A discharge trough is connected between the first and second shut-off valves via a tee and a third shut-off valve, respectively. The discharge outlets at the lower ends of the two discharge troughs are connected to a coal slurry trough via pipelines and a low-pressure coal slurry pump, respectively. The discharge outlets at the lower ends of the two coal slurry troughs are connected to the feed inlets on both sides of a coal gasifier via pipelines and a high-pressure coal slurry pump, respectively. The outlet at the upper end of the coal gasifier is connected to a liquid ammonia tank via a synthetic ammonia conversion furnace. This is used to gasify the raw materials, liquefy them into ammonia through the synthetic ammonia conversion furnace, and then send them to the liquid ammonia tank for storage. The outlet of the liquid ammonia tank is connected to the liquid ammonia vaporizer via a liquid ammonia pump. The heat source inlet of the liquid ammonia vaporizer is connected to the hot primary air outlet of the boiler via a pipeline and a heat source shut-off valve. The ammonia outlet of the liquid ammonia vaporizer is connected to the ammonia burner inside the boiler via a gas supply pipeline.

2. The coal-fired power plant coupled with ammonia production and combustion system according to claim 1, characterized in that: The demineralized water supply pipelines corresponding to the first and second coal mills are respectively connected to the gasification water pipelines via tee connections. A gasification water shut-off valve is installed on the gasification water pipeline, and the other end of the gasification water pipeline is respectively connected to the gasification water inlet of the first and second coal mills.

3. The coal-fired power plant coupled with ammonia production and combustion system according to claim 1, characterized in that: A pressure reducing valve and a check valve are installed in sequence on the gas supply line to adjust the ammonia pressure output by the liquid ammonia vaporizer.

4. The coal-fired power plant coupled with ammonia production and combustion system according to claim 3, characterized in that: The exhaust port of the liquid ammonia vaporizer is connected to the gas supply pipeline through a pipeline so that the ammonia gas can be mixed with the cooled hot primary air and then sent to the ammonia burner for combustion.

5. The coal-fired power plant coupled with ammonia production and combustion system according to any one of claims 1-4, characterized in that: A coal feed gate is installed on the pipeline between the coal feeder and the coal mill to control the coal feed to the coal mill.

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