1. A system for reducing carbon emission by blending and burning ammonia gas is characterized by comprising an ammonia gas source, a gasification device (2), a hydrogen preparation device and a hearth;

an ammonia nozzle (8) and an ammonia-hydrogen mixed burner (7) are arranged above the over-fire air of the hearth;

the ammonia source is connected with the input end of the gasification device (2), the output end of the gasification device (2) is divided into three paths of outputs, the first path of output is connected with the input end of the hydrogen preparation device, the second path of output is connected with the output end of the hydrogen preparation device and the ammonia-hydrogen mixed burner (7), and the third path of output is connected with an ammonia nozzle on the hearth.

2. The system for reducing carbon emission by co-firing ammonia gas as claimed in claim 1, wherein the ammonia gas nozzle (8) is positioned above the ammonia-hydrogen mixing burner (7).

3. The system for reducing carbon emission by blending burned ammonia gas as claimed in claim 1, wherein the hydrogen production unit comprises a catalytic reforming unit (3) and a gas purification unit (4);

the input end of the catalytic reforming device (3) is connected with the first output of the gasification device (2), the output end of the catalytic reforming device (3) is connected with the input end of the gas purification device (4), and the output end of the gas purification device (4) is connected with the second output and then connected with the ammonia-hydrogen mixed burner (7).

4. The system for reducing carbon emission by blending burned ammonia gas as claimed in claim 3, wherein the output end of the gas purification device (4) is connected with a hydrogen storage tank, and the input end of the hydrogen storage tank is connected with the outlet of the second output.

5. The system for reducing carbon emission by co-firing ammonia gas as claimed in claim 1, wherein the ammonia gas source, the hydrogen gas production device, and the output lines of the second output and the third output of the gasification device are provided with detection devices, the detection device (4) is connected with the control unit (5), the detection device measures the temperature and the flow rate of the gas flowing through the lines, and the control unit (5) adjusts the flow rate of the gas according to the temperature and the flow rate.

6. The system for reducing carbon emission by blending burned ammonia gas as recited in claim 5, wherein the detection device (4) comprises a flow meter (9) and a temperature transmitter (10), the flow meter (9) and the temperature transmitter (10) are arranged on a pipeline;

the control unit (5) comprises a controller (11), a frequency converter (12) and an air pump, signal ends of the flowmeter (9) and the temperature transmitter (10) are connected with the controller (11), the controller (11) is connected with the air pump through the frequency converter (12), and the air pump is connected with a pipeline.

7. A method for controlling the system for reducing carbon emission by co-firing ammonia according to any one of claims 1 to 6,

the ammonia-hydrogen mixed gas enters the upper part of the over-fire air of the hearth through the ammonia-hydrogen mixed burner, the airflow rotation direction of the hydrogen-oxygen mixed gas is opposite to the over-fire air direction, and the size of the tangent circle is far smaller than that of the main burner;

the ammonia gas enters the upper part of the over-fire air of the hearth through the ammonia gas nozzle (8), the injection airflow direction of the ammonia gas is the same as the over-fire air, the tangential circle size is the same as the mixed gas layer of the ammonia and hydrogen, the ammonia gas is adopted, the NOx in the hearth is reduced by utilizing the SNCR principle, and the ammonia and hydrogen mixed gas is subjected to airflow racemization.

8. The method as claimed in claim 7, wherein the injection speed of the hydrogen ammonia-hydrogen gas is not lower than 100 m/s.

9. The method for controlling the system for reducing the carbon emission by co-firing the ammonia gas as claimed in claim 7, wherein the air amount fed into the main combustion zone of the furnace is 75% of the air amount required for the complete combustion of the pulverized coal.

10. The method for controlling the system for reducing carbon emission by co-firing the ammonia gas according to claim 7, wherein the flue gas conveyed by the hearth passes through an SCR (selective catalytic reduction) device of a tail flue to reduce NO in the flue gas again_xThe content of (a).

Background

In recent years, the world energy consumption is increasing, and the consumption of fossil fuels is accompanied by a series of environmental problems while bringing social and economic benefits. Therefore, the development of new fuels and combustion techniques thereof to replace fossil fuels has become urgent. The development and utilization of the high-efficiency low-pollution combustion technology can effectively solve the environmental problems of fossil energy shortage, greenhouse effect and the like, and has important significance for the sustainable development of society. Scholars at home and abroad propose various alternative fuels such as ethanol, dimethyl ether (DME), biodiesel, hydrogen and the like. Among them, hydrogen is generally favored due to its characteristics of no carbon emission, wide combustion limit, and the like. However, hydrogen is extremely low in energy per volume when transported relative to conventional fuels, and is 4 times less than gasoline when stored in liquid form at-235 ℃. In addition, hydrogen has a complex safety problem in storage, transportation and use due to its low ignition energy and high flame propagation speed. Ammonia is also considered a promising clean energy carrier and storage medium. Similar to hydrogen, ammonia may be obtained from fossil fuels, biomass, or other renewable resources. Compared with hydrogen, the cost of ammonia unit stored energy is lower, the volume energy density is higher, and the method is safer and more reliable. Therefore, the research on the efficient ammonia combustion technology can effectively relieve the energy crisis and provide a new direction for the development of the energy industry.

At present, a large number of existing thermal power generating units in China are difficult to survive under the large background of carbon peak reaching and carbon neutralization; meanwhile, the service life of the domestic unit is generally short, and the quitting of a power generation sequence can also bring about great waste of resources, so that the low-carbon fuel replacement of the existing unit has high application value. Because nitrogen-containing fuel can generate a large amount of nitrogen oxides in the combustion process, the combustion technology needs to be further developed.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a system and a method for reducing carbon emission by blending and burning ammonia gas, which reduce CO in a conventional coal-fired unit by blending and burning ammonia gas₂The discharge amount meets the requirement of replacing low-carbon fuel in the conventional coal-fired unit.

The invention is realized by the following technical scheme:

a system for reducing carbon emission by blending and burning ammonia gas comprises an ammonia gas source, a gasification device, a hydrogen preparation device and a hearth;

an ammonia nozzle and an ammonia-hydrogen mixed burner are arranged above the over-fire air of the hearth;

the ammonia source is connected with the input end of the gasification device, the output end of the gasification device is divided into three paths of outputs, the first path of output is connected with the input end of the hydrogen preparation device, the second path of output is connected with the output end of the hydrogen preparation device and the ammonia-hydrogen mixed burner, and the third path of output is connected with an ammonia nozzle on the hearth.

Preferably, the ammonia gas nozzle is positioned above the ammonia-hydrogen mixing burner.

Preferably, the hydrogen production unit comprises a catalytic reforming unit and a gas purification unit;

the input end of the catalytic reforming device is connected with the first output of the gasification device, the output end of the catalytic reforming device is connected with the input end of the gas purification device, and the output end of the gas purification device is connected with the second output and then connected with the ammonia-hydrogen mixed burner.

Preferably, the output end of the gas purification device is connected with a hydrogen storage tank, and the input end of the hydrogen storage tank is connected with the outlet of the second output.

Preferably, the ammonia source, the hydrogen preparation device, and the output pipelines of the second output and the third output of the gasification device are all provided with detection devices, the detection devices are connected with the control unit, the detection devices measure the temperature and the flow of the gas flowing through the pipelines, and the control unit adjusts the flow of the gas according to the temperature and the flow.

Preferably, the detection device comprises a flow meter and a temperature transmitter, and the flow meter and the temperature transmitter are arranged on the pipeline;

the control unit comprises a controller, a frequency converter and an air pump, signal ends of the flowmeter and the temperature transmitter are connected with the controller, the controller is connected with the air pump through the frequency converter, and the air pump is connected with the pipeline.

A control method of a system for reducing carbon emission by blending ammonia gas is characterized in that ammonia-hydrogen mixed gas enters the upper part of over-fire air of a hearth through an ammonia-hydrogen mixed burner, the airflow rotation direction of the hydrogen-oxygen mixed gas is opposite to the over-fire air direction, and the size of a tangent circle is far smaller than that of a main burner;

the ammonia gas enters the upper part of the over-fire air of the hearth through the ammonia gas nozzle, the injection airflow direction of the ammonia gas is the same as the over-fire air, the tangential circle size is the same as the ammonia-hydrogen mixed gas layer, the ammonia gas is adopted, the NOx in the hearth is reduced by utilizing the SNCR principle, and the ammonia-hydrogen mixed gas is subjected to air current racemization.

Preferably, the injection speed of the gas flow of the hydroammoniating gas is not lower than 100 m/s.

Preferably, the air feeding amount of the main combustion zone of the hearth is 75% of the air amount required by the complete combustion of the pulverized coal.

Preferably, the flue gas conveyed by the hearth passes through an SCR (selective catalytic reduction) device of the tail flue to reduce NO in the flue gas again_xThe content of (a).

Compared with the prior art, the invention has the following beneficial technical effects:

the invention provides a system for reducing carbon emission by blending and burning ammonia gas, wherein liquid ammonia gas passes throughThe gasification device is divided into three paths, wherein one path of the gasification device utilizes ammonia to prepare hydrogen, the prepared hydrogen and the ammonia of the other path of the gasification device are mixed into ammonia-hydrogen mixed fuel, the ammonia-hydrogen mixed fuel is input to the upper part of over-fire air of the hearth through an ammonia-hydrogen mixed burner to carry out combustion heat release, NOx generation can be reduced under the condition of low oxygen, the ammonia output by the third path of the gasification device enters the hearth through an ammonia nozzle, NOx in the hearth is reduced by utilizing the SNCR principle, smoke can reach the atmospheric emission standard after the ammonia is mixed and burned, the combustion characteristic of the ammonia is improved by doping the hydrogen, the hydrogen is doped by utilizing a direct current mode, the investment cost is reduced, the application risk is reduced, the ammonia is doped into an existing coal-fired unit to replace fire coal with the same heat value, non-carbon fuel is utilized to replace carbon-containing fuel, thereby CO is reduced₂Meanwhile, the resources of the thermal power generating unit in service are fully utilized, and the current situation of existence of the thermal power generating unit is improved.

The ammonia-hydrogen mixed gas enters the upper part of the over-fire air of the hearth, the airflow rotation direction of the hydrogen-oxygen mixed gas is opposite to the over-fire air direction, and the size of the tangent circle is far smaller than that of the tangent circle of the main burner. The ammonia gas enters the upper part of the over-fire air of the hearth, the injection airflow direction of the ammonia gas is the same as the over-fire air, the tangential circle size is the same as the hydrogen-ammonia mixed gas layer, the ammonia-hydrogen fuel airflow is despun while the NOx is reduced by adopting the SNCR principle, and finally the NOx content in the flue gas is reduced through the treatment of SCR, so that the flue gas can reach the atmospheric emission standard after the ammonia gas is doped.

Drawings

FIG. 1 is a block diagram of a pre-device in a system for reducing carbon emission by blending ammonia gas according to the present invention;

FIG. 2 is a schematic diagram of a furnace burner of the system for reducing carbon emission by blending ammonia gas according to the present invention;

fig. 3 is a schematic diagram of a sensor and control unit of the present invention.

In the figure: the device comprises a liquid ammonia storage tank 1, a gasification device 2, a catalytic reforming device 3, a gas purification device 4, a flow signal transmission unit 5, a control unit 6, an ammonia-hydrogen mixed burner 7, an ammonia nozzle 8, a flowmeter 9, a temperature transmitter 10, a controller 11, a frequency converter 12, an air pump 13 and a temperature measuring point 14.

Detailed Description

The present invention will now be described in further detail with reference to the attached drawings, which are illustrative, but not limiting, of the present invention.

Referring to fig. 1-3, a system for reducing carbon emission by blending ammonia gas comprises an ammonia gas source, a gasification device 2, a hydrogen preparation device and a hearth.

The ammonia source is connected with the input end of the gasification device 2, the output end of the gasification device 2 is divided into three paths of outputs, the first path of output is connected with the input end of the hydrogen preparation device, the second path of output and the output end of the hydrogen preparation device are connected with the ammonia-hydrogen mixed burner 7 on the hearth, and the third path of output is connected with the ammonia nozzle on the hearth.

The ammonia-hydrogen mixed burner 7 is arranged above the over-fire air of the hearth, and the ammonia nozzle 8 is positioned above the ammonia-hydrogen mixed burner 7.

The ammonia-hydrogen mixed burner 7 and the ammonia nozzle 8 are arranged on the upper layer of the over-fire air of the hearth, after the ammonia gas output by the first path of the gasification device 2 enters the hydrogen preparation device to be made into hydrogen gas, the hydrogen gas is mixed with the ammonia gas output by the second path of the gasification device 2 and then enters the ammonia-hydrogen mixed burner 7, the ammonia-hydrogen mixed fuel is combusted to release heat, the ammonia gas output by the third path of the gasification device 2 enters the hearth through the ammonia nozzle, and the content of nitrogen oxides at the outlet of the hearth is reduced through the reburning reduction action under the reducing atmosphere.

And the ammonia source, the hydrogen preparation device, and the second output and the third output of the gasification device are respectively provided with a detection device, and the detection device 4 is connected with the control unit 5.

The detection device 4 comprises a flowmeter 9 and a temperature transmitter 10, the flowmeter 9 and the temperature transmitter 10 are arranged on a pipeline, a temperature measuring point 14 is arranged on the pipeline, and the flowmeter 9 and the temperature transmitter 10 are used for measuring the flow and the temperature of the gas flowing through the corresponding pipeline.

The control unit 5 comprises a controller 11, a frequency converter 12 and an air pump, signal ends of the flowmeter 9 and the temperature transmitter 10 are connected with the controller 11, the controller 11 is connected with the air pump through the frequency converter 12, the air pump is connected with a pipeline, and the flow of air in the pipeline is controlled through the air pump.

The ammonia gas source is liquid ammonia storage tank 1, and the hydrogen preparation facilities includes catalytic reforming device 3 and gas purification device 4, and catalytic reforming device 3's input passes through gasification equipment 2's output connection all the way, and catalytic reforming device 3's output is connected with gas purification device 4's input, and the hydrogen storage tank is connected to gas purification device 4's output, and the input of hydrogen storage tank is connected with ammonia-hydrogen mixed combustion ware 7 after the exit linkage of second way output.

The detection device on the output pipeline of the hydrogen preparation device is positioned on the pipeline of the output end of the hydrogen storage tank.

The following is a detailed description of the control method of the system for reducing carbon emission by blending ammonia gas provided by the present invention.

The ammonia-hydrogen mixed gas enters the upper part of the over-fire air of the hearth through the ammonia-hydrogen mixed burner, the temperature of the position is not higher than 1300 ℃, the airflow rotating direction of the hydrogen-oxygen mixed gas is opposite to the over-fire air direction, the size of a tangent circle is far smaller than that of a main burner, and the airflow injection speed of the hydrogen-oxygen mixed gas is not lower than 100 m/s.

The ammonia gas enters the upper part of the over-fire air of the hearth through the ammonia gas nozzle 8, the temperature of the position is about 1000 ℃, the injection airflow direction of the ammonia gas is the same as the over-fire air, the tangential circle size is the same as the mixed gas layer of the hydrogen and the ammonia, and the ammonia fuel airflow racemization is realized while the NOx is reduced by adopting the SNCR principle.

The air amount fed into the main combustion zone of the hearth is 75% of the air amount required by the complete combustion of the pulverized coal, and the excess air coefficient of the whole hearth is about 1.12.

According to the system for reducing carbon emission by blending combustion of ammonia, provided by the invention, hydrogen-oxygen mixed gas is input into a hearth under the condition that the airflow injection speed is not lower than 100m/s, ammonia-hydrogen mixed fuel is ignited by entrainment of high-temperature flue gas, and NOx generation can be reduced under the condition of low oxygen in the flue gas while heat release is realized by combustion of residual oxygen in the flue gas. At the same time, ammonia is introduced into the upper region, and the formation of NOx is further reduced by utilizing the SNCR principle. In addition, the SCR device through the tail flue can further reduce smokeThe NOx content of the gas. Through the mode, the temperature of a combustion area is controlled, and the treatment of flue gas internal circulation, ammonia SNCR reduction and SCR are added, the ammonia SNCR is combined with the SCR mode to reduce NOx, the content of NOx in flue gas is reduced, the flue gas can reach the atmospheric emission standard after the ammonia is doped and burned, the combustion characteristic of the ammonia is improved by doping the hydrogen, the hydrogen is doped in a direct current mode, the investment cost is reduced, the application risk is reduced, the ammonia is doped into an active coal-fired unit to replace fire coal with the same heat value, and non-carbon fuel is used for replacing carbon-containing fuel, so that CO is reduced₂Meanwhile, the resources of the thermal power generating unit in service are fully utilized, and the current situation of existence of the thermal power generating unit is improved.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.