An ammonia-hydrogen mixed natural gas combustion boiler test platform and a working method thereof

Abstract

The application discloses a kind of ammonia hydrogen mixed natural gas combustion boiler test platform and its working method, test platform includes natural gas storage tank, hydrogen storage tank, liquid ammonia storage tank and liquid ammonia heating system, natural gas storage tank is connected with the multiple-component gas burner installed on gas boiler, hydrogen storage tank is connected with the multiple-component gas burner installed on gas boiler and is equipped with hydrogen flow regulating valve on connecting pipeline, liquid ammonia storage tank is connected with ammonia water pump, and ammonia water pump outlet is connected with liquid ammonia heating system, liquid ammonia heating system can heat liquid ammonia into ammonia gas of preset temperature, and the outlet of liquid ammonia heating system is connected with multiple-component gas burner and is equipped with ammonia gas main flow regulating valve on connecting pipeline.The application can realize zero carbon emission, and the system structure is reasonable, with the characteristics that heat can be matched and utilized in stages, providing a kind of thought for the development of industrial boiler in future.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas combustion and testing, and particularly relates to an ammonia-hydrogen mixed natural gas combustion boiler test platform and a working method thereof. BACKGROUND

[0002] Replacing fossil fuels with non-carbon fuels is one of the effective ways of carbon emission reduction, and there are mainly two non-carbon fuels, hydrogen and ammonia. Hydrogen energy is a clean energy among fuel energies, and is valued and utilized by people, and can be obtained by electrolysis of renewable energy; but it is difficult to transport and store on a large scale due to its small density and low heat per unit volume. Ammonia is a good carrier of hydrogen energy, has a high liquefaction temperature, and has advantages such as low conversion hydrogen cost and sufficient supply.

[0003] Hydrogen has the characteristics of fast combustion speed, wide combustion limit, small specific heat value, and long quenching length; ammonia has the characteristics of slow combustion speed in air, instability, and difficulty in ignition; the liquefaction temperature includes safe pressurization, liquefaction, and combustion. Hydrogen and ammonia combustion has complementarity, and currently there is a preliminary test research on mixing ammonia with existing coal powder boilers, but there is no boiler for mixing hydrogen, ammonia and natural gas and other multi-gas fuel, so it is necessary to design a multi-gas fuel boiler combustion test platform to fully understand the combustion and heat exchange performance and pollutant emission concentration regularity of natural gas mixed with hydrogen and ammonia. SUMMARY

[0004] The purpose of the present application is to provide an ammonia-hydrogen mixed natural gas combustion boiler test platform and a working method thereof. Since ammonia and hydrogen are non-carbon fuels, the present application can achieve zero carbon emission, and the system structure is reasonable, has the characteristics of producing heat that can be matched and utilized in stages, and provides a thought for the development of future industrial boilers.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0006] An ammonia-hydrogen mixed natural gas combustion boiler test platform, comprising a natural gas storage tank, a hydrogen storage tank, a liquid ammonia storage tank and a liquid ammonia heating system, the natural gas storage tank is connected with a multi-component gas burner installed on a gas boiler, the hydrogen storage tank is connected with the multi-component gas burner installed on the gas boiler and a hydrogen flow regulating valve is arranged on the connecting pipeline, the liquid ammonia storage tank is connected with an ammonia water pump, the outlet of the ammonia water pump is connected with the liquid ammonia heating system, the liquid ammonia heating system can heat the liquid ammonia into ammonia gas at a preset temperature, and the outlet of the liquid ammonia heating system is connected with the multi-component gas burner and an ammonia gas main flow regulating valve is arranged on the connecting pipeline.

[0007] Preferably, a natural gas flow regulating valve is arranged at the outlet of the natural gas storage tank.

[0008] Preferably, the outlet of the ammonia water pump is provided with a liquid ammonia flow regulating valve.

[0009] Preferably, the liquid ammonia heating system comprises an ammonia gas-flue gas heat exchanger, a liquid ammonia-flue gas heat exchanger, a low-temperature ammonia gas buffer tank and a high-temperature ammonia gas buffer tank, the ammonia gas-flue gas heat exchanger is arranged in the flue of the gas boiler and located downstream of the economizer, the liquid ammonia-flue gas heat exchanger is arranged in the flue of the gas boiler and located downstream of the ammonia gas-flue gas heat exchanger; the outlet of the ammonia water pump is connected with the inlet of the liquid ammonia-flue gas heat exchanger, the outlet of the liquid ammonia-flue gas heat exchanger is connected with the inlet of the low-temperature ammonia gas buffer tank, the outlet of the low-temperature ammonia gas buffer tank is connected with the inlet of the ammonia gas-flue gas heat exchanger, the outlet of the ammonia gas-flue gas heat exchanger is connected with the inlet of the high-temperature ammonia gas buffer tank, the outlet of the high-temperature ammonia gas buffer tank is connected with the multi-component gas burner and provided with the ammonia gas main flow regulating valve, and the outlet of the low-temperature ammonia gas buffer tank is provided with a low-temperature ammonia gas branch flow regulating valve.

[0010] Preferably, a communication pipeline is arranged between the outlet of the low-temperature ammonia gas buffer tank and the inlet of the high-temperature ammonia gas buffer tank, and the communication pipeline is provided with a low-temperature ammonia gas branch flow regulating valve.

[0011] Preferably, the multi-component gas burner comprises a first multi-component gas burner and a second multi-component gas burner arranged below the first multi-component gas burner, the outlet of the natural gas storage tank, the outlet of the hydrogen gas storage tank and the outlet of the liquid ammonia heating system are all divided into two paths and connected with the first multi-component gas burner and the second multi-component gas burner respectively.

[0012] Preferably, the gas injection ports in the multi-component gas burner are arranged as separate injection ports for each gas or common injection ports for all the gases.

[0013] The working method of the ammonia-hydrogen mixed natural gas combustion boiler test platform as described above comprises the following processes:

[0014] When the gas boiler is started in cold state or hot state, the natural gas storage tank supplies natural gas to the multi-component gas burner for combustion in the gas boiler, after the parameters of the gas boiler are stabilized, the ammonia gas main flow regulating valve and the liquid ammonia flow or / and the hydrogen flow regulating valve are adjusted to realize different mixing ratios of natural gas and ammonia gas or / and hydrogen gas, and the pollutant emission concentration of the flue gas in the tail of the gas boiler is analyzed.

[0015] Preferably, the liquid ammonia heating system includes an ammonia-flue gas heat exchanger, a liquid ammonia-flue gas heat exchanger, a low-temperature ammonia buffer tank, and a high-temperature ammonia buffer tank. The ammonia-flue gas heat exchanger is located in the flue of the gas-fired boiler and downstream of the economizer. The liquid ammonia-flue gas heat exchanger is also located in the flue of the gas-fired boiler and downstream of the ammonia-flue gas heat exchanger. The outlet of the ammonia pump is connected to the inlet of the liquid ammonia-flue gas heat exchanger. The outlet of the liquid ammonia-flue gas heat exchanger is connected to the inlet of the low-temperature ammonia buffer tank. The outlet of the low-temperature ammonia buffer tank is connected to the inlet of the ammonia-flue gas heat exchanger. The outlet of the ammonia-flue gas heat exchanger is connected to the inlet of the high-temperature ammonia buffer tank. The outlet of the high-temperature ammonia buffer tank is connected to a multi-component gas burner and equipped with the aforementioned ammonia main flow regulating valve. The outlet of the low-temperature ammonia buffer tank is equipped with a low-temperature ammonia main flow regulating valve. A connecting pipeline is provided between the outlet of the low-temperature ammonia buffer tank and the inlet of the high-temperature ammonia buffer tank, and a low-temperature ammonia branch flow regulating valve is provided on this connecting pipeline.

[0016] To measure the pollutant emission concentration of ammonia at different temperatures under a preset ammonia-hydrogen co-firing ratio, the flow ratio of low-temperature ammonia to high-temperature ammonia was adjusted by regulating the flow control valves of the main low-temperature ammonia line and the branch low-temperature ammonia line to achieve temperature changes. The pollutant emission concentration was analyzed by collecting flue gas from the flue of the gas-fired boiler.

[0017] Preferably, the flue gas collection point on the flue is located downstream of the liquid ammonia-flue gas heat exchanger, and a flue gas sampling hole is opened at the collection point in the flue.

[0018] The present invention has the following beneficial effects:

[0019] In this invention, an ammonia-hydrogen mixed natural gas combustion boiler test platform is used. When testing is required, different ratios of hydrogen, ammonia, and natural gas are injected into the furnace through a burner for combustion. The heat generated is used to heat the working fluid on the boiler's heating surfaces. The heated, high-temperature, high-pressure working fluid is used for power generation or external steam supply. By varying the ammonia-hydrogen blending ratio, key technologies for the clean and efficient combustion of hydrogen-rich fuels such as hydrogen and ammonia are mastered. These include the combustion characteristics and reaction mechanism of hydrogen, ammonia, and natural gas blended fuels; the dynamic combustion characteristics and pollutant generation characteristics of burners for hydrogen-rich blended fuels; and wide-load adjustment of blended fuel combustion. A two-stage ammonia heat exchanger allows liquid ammonia to be vaporized and heated, facilitating combustion. Simultaneously, an energy-saving device lowers the flue gas temperature to below the water dew point, fully utilizing the latent heat of vaporization of water vapor in the flue gas and improving the overall boiler efficiency. As can be seen from the above, this invention's ammonia-hydrogen mixed natural gas combustion boiler test platform can study the blending of hydrogen / ammonia. Furthermore, this system features a simple structure, extremely low emissions, and comprehensive utilization of combustion products, providing a new approach for the development of future industrial boilers. In this invention, almost all the heat input to the boiler is utilized, and only a small amount of low-temperature flue gas is emitted. While significantly reducing carbon dioxide emissions, it also achieves comprehensive utilization of the heat and mass of the flue gas, resulting in good social, economic and environmental benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the ammonia-hydrogen mixed natural gas combustion boiler test platform of the present invention.

[0021] Among them, 1 is a natural gas storage tank, 2 is a hydrogen storage tank, 3 is a liquid ammonia storage tank, 4-1 is a low-temperature ammonia buffer tank, 4-2 is a high-temperature ammonia buffer tank, 5 is a gas boiler, 5-1 is a multi-component gas burner, 5-2 is a water-cooled wall, 5-3 is a convective heat exchange surface, 5-4 is an economizer, 5-5 is an air preheater, 5-6 is an ammonia-flue gas heat exchanger, 6 is a liquid ammonia-flue gas heat exchanger, 7 is an ammonia main flow regulating valve, 7-1 is a liquid ammonia flow regulating valve, 7-2 is a low-temperature ammonia main flow regulating valve, 7-3 is a low-temperature ammonia branch flow regulating valve, 8 is a hydrogen flow regulating valve, 9 is a natural gas flow regulating valve, 10 is a flue gas sampling test hole, and 11 is an ammonia water pump. Detailed Implementation

[0022] Reference Figure 1The ammonia-hydrogen mixed natural gas combustion boiler test platform of the present invention includes a natural gas storage tank 1, a hydrogen storage tank 2, a liquid ammonia storage tank 3, a low-temperature ammonia buffer tank 4-1, a high-temperature ammonia buffer tank 4-2, a gas boiler 5, a multi-component gas burner 5-1, a water-cooled wall 5-2, a convection heat exchange surface 5-3, an economizer 5-4, an air preheater 5-5, an ammonia-flue gas heat exchanger 5-6, a liquid ammonia-flue gas heat exchanger 6, an ammonia main flow regulating valve 7, a liquid ammonia flow regulating valve 7-1, a low-temperature ammonia main flow regulating valve 7-2, a low-temperature ammonia branch flow regulating valve 7-3, a hydrogen flow regulating valve 8, a natural gas flow regulating valve 9, and a flue gas sampling and measuring hole 10.

[0023] Natural gas storage tank 1, hydrogen storage tank 2, and high-temperature ammonia buffer tank 4-2 are connected to a multi-component gas burner 5-1 via natural gas flow regulating valve 9, hydrogen flow regulating valve 8, and ammonia flow regulating valve 7, respectively. The multi-component gas burner 5-1 has various independent gas nozzles, allowing different fuels to enter the burner individually or simultaneously. Along the flue gas flow direction, the boiler is sequentially arranged with a water-cooled wall 5-2, a convective heat exchange surface 5-3, an economizer 5-4, an air preheater 5-5, an ammonia-flue gas heat exchanger 5-6, a liquid ammonia-flue gas heat exchanger 6, and a flue gas sampling port 10.

[0024] The ammonia heat exchanger includes an ammonia-flue gas heat exchanger 5-6 and a liquid ammonia-flue gas heat exchanger 6. When the system is not in operation for ammonia combustion, all flue gas bypasses the air preheater 5-5 and passes directly through the ammonia-flue gas heat exchanger 5-6. When the system is in operation for ammonia combustion, a portion of the flue gas flows through the air preheater 5-5, and another portion flows through the ammonia-flue gas heat exchanger 5-6. Subsequently, the two streams of low-temperature flue gas merge and flow together through the liquid ammonia-flue gas heat exchanger 6.

[0025] The liquid ammonia inlet of the liquid ammonia-flue gas heat exchanger 6 is connected to the liquid ammonia storage tank 3 via the liquid ammonia flow regulating valve 7-1 and the ammonia water pump 11. The ammonia water pump 11 provides power for the flow of ammonia water and ammonia. If the ammonia water pump 11 is a frequency converter pump or a flow control pump, the liquid ammonia flow regulating valve 7-1 may not be used. The outlet of the low-temperature ammonia buffer tank 4-1 is connected to the inlet of the low-temperature ammonia buffer tank 4-1. During operation, the liquid ammonia is heated and vaporized by the low-temperature flue gas flowing through the liquid ammonia-flue gas heat exchanger 6, and the resulting low-temperature ammonia gas enters the low-temperature ammonia buffer tank 4-1. The low-temperature ammonia inlet of the ammonia-flue gas heat exchanger 5-6 is connected to the low-temperature ammonia buffer tank 4-1 via the low-temperature ammonia main flow regulating valve 7-2. The outlet is connected to the inlet of the high-temperature ammonia buffer tank 4-2. During operation, the low-temperature ammonia is heated by the high-temperature flue gas flowing through the ammonia-flue gas heat exchanger 5-6 and then enters the high-temperature ammonia buffer tank 4-2. There is also a branch pipeline between the low-temperature ammonia buffer tank 4-1 and the high-temperature ammonia buffer tank 4-2. A low-temperature ammonia branch flow regulating valve 7-3 is installed on the pipeline to regulate the temperature of the ammonia entering the high-temperature ammonia buffer tank 4-2 during operation.

[0026] Natural gas is used as the ignition and combustion stabilization fuel, while ammonia and hydrogen are used as co-fired fuels. The flue gas enters the furnace through the burner. After heat exchange through the water-cooled wall, convection heat exchange surface, economizer, air preheater and ammonia heat exchanger, the flue gas is discharged from the boiler. The flue gas temperature and pollutant emissions in the flue gas are measured through flue gas sampling holes 10.

[0027] When the boiler is started up in a cold or hot state, the natural gas storage tank 1 supplies natural gas to the multi-component gas burner 5-1 for combustion in the gas-fired boiler 5. The resulting high-temperature flue gas is used to heat the working fluid on the heating surface of the natural gas boiler. The heated high-temperature and high-pressure working fluid is used for power generation or external gas supply. After the parameters of the gas-fired boiler 5 stabilize, in order to measure the pollutant emission concentration of the tail flue gas of the gas-fired boiler 5 under different blending ratios of ammonia and / or hydrogen, different blending ratios can be achieved by adjusting the main flow regulating valve 7 and the liquid ammonia flow regulating valve 7-1 and / or the hydrogen flow regulating valve 8. Then, the flue gas is collected through the flue gas sampling port 10 for pollutant emission concentration analysis. In order to measure the pollutant emission concentration of ammonia at different temperatures in the boiler tail flue gas under a certain ammonia-hydrogen blending ratio, the flow ratio of low-temperature ammonia to high-temperature ammonia can be adjusted by adjusting the main flow regulating valve 7-2 and the branch flow regulating valve 7-3 to achieve temperature changes. Then, the flue gas is collected through the flue gas sampling port 10 for pollutant emission concentration analysis. Ultimately, the study aims to understand the impact of natural gas blending with hydrogen / ammonia, the blending of natural gas with hydrogen and ammonia, and ammonia temperature on combustion characteristics and pollutant emission concentrations. The flue gas, after heat exchange in the furnace of the gas-fired boiler, first passes through the furnace, convection heat exchange surface, economizer, air preheater, and ammonia heat exchanger. The ultra-low temperature flue gas passing through the ammonia heat exchanger, with a temperature below the water dew point, then passes through a dehydration device before being discharged, reducing emissions.

[0028] This invention enables systematic research on the co-firing of natural gas with hydrogen / ammonia, featuring a simple structure, extremely low pollutant emissions, and comprehensive and efficient utilization of combustion products. In this invention, almost all the heat input to the boiler is utilized, with only a small amount of low-temperature flue gas emitted. This significantly reduces carbon dioxide emissions while simultaneously achieving comprehensive heat and mass recovery and utilization of the flue gas, resulting in excellent social, economic, and environmental benefits.

Claims

1. An ammonia-hydrogen mixed natural gas combustion boiler test platform, characterized by, The system comprises a natural gas tank (1), a hydrogen tank (2), an ammonia tank (3), and an ammonia heating system, the natural gas tank (1) is connected with a multi-component gas burner (5-1) installed on a gas boiler (5), the hydrogen tank (2) is connected with the multi-component gas burner (5-1) installed on the gas boiler (5) and a hydrogen flow regulating valve (8) is arranged on the connecting pipeline, the ammonia tank (3) is connected with an ammonia water pump (11), the outlet of the ammonia water pump (11) is connected with the ammonia heating system, the ammonia heating system can heat the liquid ammonia into ammonia gas with a preset temperature, the outlet of the ammonia heating system is connected with the multi-component gas burner (5-1) and an ammonia main flow regulating valve (7) is arranged on the connecting pipeline. The ammonia heating system comprises an ammonia gas-flue gas heat exchanger (5-6), an ammonia-liquid heat exchanger (6), a low-temperature ammonia buffer tank (4-1), and a high-temperature ammonia buffer tank (4-2), the ammonia gas-flue gas heat exchanger (5-6) is arranged in the flue of the gas boiler and located downstream of an economizer (5-4), the ammonia-liquid heat exchanger (6) is arranged in the flue of the gas boiler and located downstream of the ammonia gas-flue gas heat exchanger (5-6), the outlet of the ammonia water pump (11) is connected with the inlet of the ammonia-liquid heat exchanger (6), the outlet of the ammonia-liquid heat exchanger (6) is connected with the inlet of the low-temperature ammonia buffer tank (4-1), the outlet of the low-temperature ammonia buffer tank (4-1) is connected with the inlet of the ammonia gas-flue gas heat exchanger (5-6), the outlet of the ammonia gas-flue gas heat exchanger (5-6) is connected with the inlet of the high-temperature ammonia buffer tank (4-2), the outlet of the high-temperature ammonia buffer tank (4-2) is connected with the multi-component gas burner (5-1) and the ammonia main flow regulating valve (7) is arranged on the connecting pipeline, the outlet of the low-temperature ammonia buffer tank (4-1) is provided with a low-temperature ammonia main flow regulating valve (7-2). A communication pipeline is arranged between the outlet of the low-temperature ammonia buffer tank (4-1) and the inlet of the high-temperature ammonia buffer tank (4-2), and a low-temperature ammonia branch flow regulating valve (7-3) is arranged on the communication pipeline. The multi-component gas burner (5-1) comprises a first multi-component gas burner and a second multi-component gas burner arranged below the first multi-component gas burner, the outlet of the natural gas tank (1), the outlet of the hydrogen tank (2), and the outlet of the ammonia heating system are all divided into two paths and connected with the first multi-component gas burner and the second multi-component gas burner respectively.

2. The ammonia-hydrogen mixed natural gas combustion boiler test platform according to claim 1, characterized in that, The outlet of the natural gas tank (1) is provided with a natural gas flow regulating valve (9).

3. The ammonia-hydrogen mixed natural gas combustion boiler test platform according to claim 1, characterized in that, The outlet of the ammonia water pump (11) is provided with an ammonia flow regulating valve (7-1).

4. The ammonia-hydrogen mixed natural gas combustion boiler test platform according to claim 1, characterized in that, The gas injection ports in the multi-component gas burner (5-1) are arranged as individual injection ports for each gas or a common injection port for all the gases.

5. The method of operating an ammonia-hydrogen mixed natural gas combustion boiler test platform according to any one of claims 1-4, characterized in that, The system comprises the following processes: When the gas boiler (5) is started in cold or hot state, the natural gas storage tank (1) supplies natural gas to the multi-component gas burner (5-1) and burns in the gas boiler (5). After the parameters of the gas boiler (5) are stable, in order to measure the pollutant emission concentration of the tail flue gas of the gas boiler (5) under different blending ratios of ammonia and / or hydrogen, the ammonia main flow regulating valve (7) and the liquid ammonia flow or / and the hydrogen flow regulating valve (8) are adjusted to realize different blending ratios of natural gas and ammonia or / and hydrogen, and the pollutant emission concentration of the flue gas collected from the flue of the gas boiler (5) is analyzed. In order to measure the pollutant emission concentration of the tail flue gas of the boiler under different temperatures of ammonia at a preset ammonia-hydrogen blending ratio, the flow ratio of low-temperature ammonia and high-temperature ammonia is adjusted by adjusting the low-temperature ammonia main flow regulating valve (7-2) and the low-temperature ammonia branch flow regulating valve (7-3) to realize the change of temperature, and the pollutant emission concentration is analyzed by collecting the flue gas from the flue of the gas boiler (5).

6. The method of operating an ammonia-hydrogen mixed natural gas combustion boiler test platform of claim 5, wherein, The collection point of the flue gas on the flue is located downstream of the liquid ammonia-flue gas heat exchanger (6), and the flue is provided with a flue gas sampling measuring hole (10) at the collection point.

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