阅读说明：本技术 一种降低合成气燃气轮机NOx排放的系统 (System for reducing NOx emission of synthesis gas turbine ) 是由 王波 肖云汉 张哲巅 张士杰 赵丽凤 于 2020-04-03 设计创作，主要内容包括：本发明公开了一种降低合成气燃气轮机NOx排放的系统,空分单元通过管路经加热加湿器后与燃气轮机压气机的进气管线连通,将加热加湿后的氮气以低压状态(接近常压)通入压气机的进气管线并与其中的进口空气以适当比例进行掺混,还可进一步将煤制气脱碳单元产生的二氧化碳通过管路经加热加湿器以低压状态(接近常压)通入所述压气机的进气管线中并与其中的空气进行掺混,将混合气体送入燃气轮机压气机,降低进入燃气轮机压气机的空气氧浓度,从而降低进入燃气轮机燃烧室的空气氧浓度,实现降低合成气燃气轮机NOx排放的目的。(The invention discloses a system for reducing NOx emission of a synthetic gas turbine, wherein an air separation unit is communicated with an air inlet pipeline of a gas turbine compressor through a pipeline after passing through a heating humidifier, nitrogen after heating and humidifying is introduced into the air inlet pipeline of the gas turbine compressor in a low-pressure state (close to normal pressure) and is mixed with inlet air in the air inlet pipeline in a proper proportion, carbon dioxide generated by a coal gas decarburization unit can be further introduced into the air inlet pipeline of the gas turbine compressor in a low-pressure state (close to normal pressure) through the pipeline after passing through the heating humidifier and is mixed with the air in the air inlet pipeline, mixed gas is sent into the gas turbine compressor, and the oxygen concentration of the air entering the gas turbine compressor is reduced, so that the oxygen concentration of the air entering a combustion chamber of the gas turbine is reduced, and the aim of reducing the NOx emission of.)

1. A system for reducing NOx emission of a synthesis gas turbine, which at least comprises an air separation unit, a gas turbine and a heating humidifier, wherein the gas turbine adopts synthesis gas fuel and at least comprises a compressor, a combustion chamber and a turbine, an air inlet pipeline of the compressor is communicated with the atmosphere, an exhaust pipeline of the compressor is communicated with the combustion chamber, high-pressure gas generated by the compressor and the synthesis gas fuel are mixed and combusted in the combustion chamber to generate high-temperature gas, and the high-temperature gas is introduced into and drives the turbine,

and nitrogen generated by the air separation unit passes through the heating humidifier through a pipeline and is communicated with an air inlet pipeline of the air compressor, the nitrogen is heated and humidified and then is introduced into the air inlet pipeline of the air compressor in a low-pressure state (close to normal pressure), and inlet air of the air compressor and the heated and humidified low-pressure nitrogen are mixed in the air inlet pipeline of the air compressor and then are introduced into the air compressor.

2. The system for reducing NOx emissions of a syngas gas turbine engine as set forth in the preceding claim, wherein said air separation unit is a low pressure air separation plant.

3. The system of claim, further comprising a coal decarbonization unit, wherein carbon dioxide produced by the coal decarbonization unit is passed through the heating humidifier and introduced into the compressor inlet line, wherein the carbon dioxide and nitrogen are blended in the nitrogen heating humidifier, heated and humidified, and further blended with air at a low pressure (near atmospheric pressure) in the compressor inlet line.

4. The system for reducing NOx emissions of a syngas gas turbine as set forth in the preceding claim, wherein a waste heat utilization device is disposed downstream of said turbine, flue gas discharged from said turbine is passed into said waste heat utilization device, a water preheater is disposed at the tail of said waste heat utilization device, hot water produced by said water preheater is passed into said heating humidifier and heats and humidifies nitrogen and/or carbon dioxide therein.

5. The system for reducing NOx emissions of a syngas gas turbine according to claim 4, wherein said waste heat utilization device is preferably a waste heat boiler, said water preheater is preferably located at the rear of said waste heat boiler, the water introduced into said water preheater is heated by the heat of the flue gas at the rear of said waste heat boiler, and the hot water generated by said water preheater is introduced into said heating humidifier.

6. The system for reducing NOx emissions from a syngas gas turbine as set forth in claim 5, wherein said exhaust heat boiler is further configured with a turbine, and wherein high temperature steam generated by said exhaust heat boiler is channeled to and drives said turbine to produce work.

7. The system for reducing NOx emissions from a syngas gas turbine as set forth in any one of claims 4-6, wherein hot water introduced into said heated humidifier heats and humidifies nitrogen and/or carbon dioxide therein in a direct contact manner or a non-contact manner.

8. The system for reducing NOx emissions from a syngas gas turbine as set forth in any one of claims 4-7, wherein hot water produced by said water preheater is passed into said heating humidifier in a temperature and flow adjustable manner.

9. The system for reducing NOx emissions from a syngas gas turbine as set forth in any one of claims 4-8, wherein cold water discharged from said heating humidifier is passed into a water make-up line of said water preheater.

Technical Field

The invention relates to the technical field of gas turbines, in particular to a system for reducing NOx emission of a synthetic gas turbine.

Background

The gas turbine is a new generation power device utilizing clean energy, can efficiently and cleanly convert gas fuels such as natural gas, hydrogen, synthetic gas, purge gas and the like or liquid fuels such as fuel oil and the like into electric power, and is a large-scale heat power conversion device with the highest efficiency at present.

When the gas turbine is used for burning the synthetic gas fuel rich in hydrogen (the fuel comprises gasification fuel gas of carbon-containing fuel such as coal, biomass and the like, purge gas in the chemical synthesis process, coke oven gas and the like, and the main combustible components comprise CO and H₂) In order to prevent backfire, the traditional premixed low NOx combustion technology is difficult to adopt, and currently, a diffusion combustion mode is mainly adopted. The diffusion combustion mode has high adiabatic flame temperature, which causes high NOx emission of the gas turbine, and in order to reduce the NOx emission of the gas turbine, a method of fuel dilution or a method of injecting a diluent into a combustion chamber is generally adopted, wherein the diluent is generally steam or nitrogen. For example, in the American Tampa IGCC power station, when the gas turbine is used for burning coal to prepare synthesis gas, the method of compressing nitrogen produced by high-pressure deep cooling air by a compressor and then completely injecting the compressed nitrogen into a combustion chamber of the gas turbine is adopted to reduce the emission of NOx; the United states Wabash River IGCC power station adopts a method of injecting water vapor into a gas turbine to reduce NOx emission; the Dutch Buggenium IGCC power station reduces the emission of NOx by adopting a method of further compressing nitrogen produced by high-pressure cryogenic air and injecting fuel; the method that the fuel is humidified by hot water, the nitrogen produced by high-pressure air is further compressed and then injected into the fuel in the Spanish Puertollano IGCC power station reduces the NOx emission. The Tianjin 250MW IGCC power station in Huaneng in China adopts a method of injecting steam into fuel to reduce the emission of NOx. The Fujian refining synthesis gas combustion engine in China reduces the NOx emission by adopting a method of diluting fuel after compressing nitrogen of low-pressure air separation.

The methods of fuel dilution or diluent injection into the combustion chamber have significant effects on reducing NOx emissions, but their disadvantages are also significant. First, in order to inject a diluent (nitrogen or steam) into the fuel (syngas) or combustion chamber of a gas turbine, the diluent is required to have a higher pressure. Such as nitrogen or carbon dioxide, require the addition of a compressor and the high-grade heat required to produce high-pressure steam in order to consume large amounts of compression work, such as steam, which reduces the overall efficiency of the system and consumes large amounts of high-quality demineralized water.

Another disadvantage of fuel dilution or injection of large amounts of diluent directly into the combustion chamber is the through-flow difficulties that result in the gas turbine. At present, most of gas turbines burning synthetic gas are reformed based on a gas turbine taking natural gas or oil as fuel, and after the gas turbines burn low-heat-value fuel gas, the heat value of the fuel is very low due to the dilution of the synthetic gas, and is generally only 4-5MJ/Nm³And even lower, the fuel flow rate and thus the gas flow rate into the gas turbine is significantly increased. On one hand, the back pressure of the gas compressor of the gas turbine can be obviously increased, so that the working point of the gas compressor approaches to or even exceeds a surge line, and the gas compressor can stall; on the other hand, the output power of the combustion engine is obviously increased, and the shafting strength is not enough. The problem mentioned above is the through-flow problem of medium and low calorific value syngas gas turbines. In order to solve the through-flow problem, gas turbine manufacturers adopt various methods, such as the reduction of the flow rate of the gas compressor by the top cutting of the blades of the gas compressor, the reduction of the temperature of the outlet of a combustion chamber, the air extraction and air separation of the outlet of the gas compressor, the formation of integrated air separation and the like. In addition to the technical difficulties to be solved, these methods either increase the investment significantly, reduce the efficiency significantly, or increase the complexity of the system operation control significantly.

One of the key issues in syngas gas turbines is how to reduce the NOx emissions of the syngas gas turbine at a small cost.

Disclosure of Invention

In view of the above disadvantages and shortcomings of the prior art, the present invention provides a system for reducing NOx emission of a syngas gas turbine from the perspective of system integration, wherein nitrogen generated by an air separation unit and/or carbon dioxide separated during decarbonization of syngas are heated and humidified, and then mixed with air sucked by a gas compressor at an inlet of the gas turbine compressor, and then fed into the gas turbine compressor, so as to reduce the oxygen concentration of the air entering the gas turbine compressor, thereby reducing the oxygen concentration of the air entering a combustion chamber of the gas turbine, further changing the adiabatic flame temperature of combustion, achieving the purpose of reducing NOx emission of the gas turbine, and not significantly affecting the through flow of the syngas gas turbine.

The technical solution adopted by the invention to solve the technical problem is as follows:

a system for reducing NOx emission of a synthesis gas turbine, which at least comprises an air separation unit, a gas turbine and a heating humidifier, wherein the gas turbine adopts synthesis gas fuel and at least comprises a compressor, a combustion chamber and a turbine, an air inlet pipeline of the compressor is communicated with the atmosphere, an exhaust pipeline of the compressor is communicated with the combustion chamber, high-pressure gas generated by the compressor and the synthesis gas fuel are mixed and combusted in the combustion chamber to generate high-temperature gas, and the high-temperature gas is introduced into and drives the turbine,

and nitrogen generated by the air separation unit passes through the heating humidifier through a pipeline and is communicated with an air inlet pipeline of the air compressor so as to be introduced into the air inlet pipeline of the air compressor in a low-pressure state (close to normal pressure) after being heated and humidified, and inlet air of the air compressor and the low-pressure nitrogen after being heated and humidified are mixed in the air inlet pipeline of the air compressor and then are introduced into the air compressor.

Preferably, the air separation unit is a low pressure air separation plant.

Preferably, the system further comprises a coal gas decarbonization unit, carbon dioxide generated by the coal gas decarbonization unit passes through the heating humidifier through a pipeline and then is introduced into the air inlet pipeline of the compressor, and after the carbon dioxide and nitrogen are mixed in the heating humidifier and heated and humidified, the carbon dioxide and the nitrogen are further mixed with air in the air inlet pipeline of the compressor in a low-pressure state (close to normal pressure).

Preferably, a waste heat utilization device is arranged at the downstream of the turbine, the flue gas discharged by the turbine is introduced into the waste heat utilization device, a water preheater is arranged at the tail part of the waste heat utilization device, and hot water generated by the water preheater is introduced into the heating humidifier and heats and humidifies nitrogen and/or carbon dioxide in the heating humidifier. Namely, the water introduced into the water preheater is heated by the low-grade heat at the tail part of the waste heat utilization device.

Further, the waste heat utilization device is preferably a waste heat boiler, the water preheater is preferably arranged at the tail of the waste heat boiler, water introduced into the water preheater is heated by heat of flue gas at the tail of the waste heat boiler, and hot water generated by the water preheater is introduced into the heating humidifier.

Furthermore, the waste heat boiler is also provided with a steam turbine in a matching way, and high-temperature steam generated by the waste heat boiler is introduced into and drives the steam turbine to do work.

Further, the hot water introduced into the heating humidifier heats and humidifies the nitrogen and/or the carbon dioxide in the heating humidifier in a direct contact mode or a non-contact mode.

Further, hot water generated by the water preheater is introduced into the heating humidifier in a manner of adjusting the temperature and the flow rate. The inlet temperature of the gas compressor of the gas turbine is adjusted to a certain degree, and for some gas turbines, the partial load efficiency of the unit can be improved.

Furthermore, cold water discharged by the heating humidifier is introduced into a water supplementing pipeline of the water preheater.

The invention relates to an air separation oxygen production process in the process industries of integrated coal gasification combined cycle power generation or coal chemical raw materials based on large-scale pressurized coal gasification and the like. For the synthesis gas turbine applied to the coal chemical industry, the carbon dioxide generated by the carbon dioxide separation unit and the nitrogen can be further mixed and then heated and humidified together, and then the mixture is sent to the inlet of the compressor of the gas turbine, so that the oxygen concentration of the air entering the gas turbine is further reduced.

The invention discloses a system for reducing NOx emission of a synthesis gas turbine, which has the working principle that: the invention changes the temperature of the adiabatic flame of combustion by reducing the oxygen concentration of the air in the combustion chamber, and can effectively reduce the NOx emission of the combustion chamber.

Although the prior scheme for reducing NOx by diluting fuel of a synthesis gas turbine can achieve better technical effect of reducing NOx, the technical scheme of the invention has simpler system and does not bring about the through-flow problem of the gas turbine, and compared with the method for injecting steam/nitrogen into fuel or a combustion chamber of the gas turbine in the technical background, the method has the advantages that:

(1) the invention mixes low-pressure (near normal pressure) nitrogen and/or carbon dioxide and water vapor into the inlet of the gas compressor of the gas turbine, and the nitrogen/carbon dioxide does not need to be compressed, thereby saving equipment and energy consumption. If nitrogen and/or carbon dioxide are used to dilute the fuel, a multistage centrifugal compressor is typically provided to pressurize the diluent gas above the fuel pressure. For example, nitrogen fuel dilution is adopted, and in order to reduce system energy consumption, an air separation oxygen generation device of the nitrogen fuel dilution system generally needs to be operated at high pressure so as to increase the pressure of produced gas. The invention only needs low-pressure nitrogen and/or carbon dioxide (close to normal pressure), and waste nitrogen generated by the low-pressure air separation oxygen generation device and/or carbon dioxide generated in the process of decarbonization of synthesis gas are introduced into the inlet of the combustion engine to be mixed with air by heating the humidifier to improve the water vapor content.

(2) The invention has little influence on the through flow of the synthesis gas turbine. The gas turbine through-flow problems are exacerbated by either fuel dilution or diluent injection into the combustor, and provisions have to be taken to mitigate through-flow. In the invention, nitrogen and/or carbon dioxide and steam are mixed with air at the inlet of the compressor of the gas turbine, so that the oxygen concentration of the air at the inlet of the compressor can be reduced, but the total flow of the compressor is not changed greatly, and the influence on the gas flow at the inlet of the turbine is not large.

(3) The invention can reduce the NOx emission of the gas turbine and can not cause obvious influence on the through flow of the synthetic gas combustion engine.

(4) The invention heats and humidifies by nitrogen and/or carbon dioxide to form mixed gas of nitrogen and/or carbon dioxide and water vapor, the nitrogen and/or carbon dioxide directly contacts with hot water for heat and mass transfer, and the evaporation of the hot water only needs to consume the low-temperature waste heat (usually lower than 80 ℃) of the system.

(5) Although the heating and humidification of nitrogen and/or carbon dioxide improves the water vapor content of the inlet gas of the gas turbine compressor and reduces the oxygen concentration, the inlet temperature of the gas turbine compressor can be improved to a certain extent, and the output power and the thermal efficiency of the gas turbine are further reduced (compared with the condition that the inlet is not heated, the efficiency is reduced), so whether the NOx reduction system is adopted or not needs to be selected according to actual requirements.

(6) The invention can adjust the inlet temperature of the compressor of the gas turbine to a certain extent by adjusting the hot water flow and temperature of the heating humidifier of the nitrogen and/or the carbon dioxide, and can improve the partial load efficiency of the unit for some gas turbines.

Drawings

Fig. 1 is a schematic diagram of a system for reducing NOx emission of a syngas gas turbine according to the present invention applied to a gas turbine power generation and syngas cogeneration system based on coal gasification, wherein a coal gasification unit 1, a coal gas purification and desulfurization unit 2, a coal gas shift unit 3, a coal gas decarbonization unit 4, a compressor 5, a combustion chamber 6, a turbine 7, a waste heat boiler 8, a steam turbine 9, a generator 10, a cryogenic air separation unit 11, a heating humidifier 12, and a water preheater 13 are provided.

Detailed Description

In order to make the implementation objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in the embodiments of the present invention. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, but not all embodiments of the invention. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. The structure and technical scheme of the present invention are further described in detail with reference to the accompanying drawings, and an embodiment of the present invention is provided.

The following description will be made of an application of the system for reducing NOx emissions of a syngas gas turbine according to the present invention, taking a gas turbine power generation and syngas cogeneration system based on coal gasification as an example. As shown in fig. 1, the system comprises a coal gasification unit 1, a coal gas purification and desulfurization unit 2, a coal gas conversion unit 3, a coal gas decarbonization unit 4, a compressor 5, a combustion chamber 6, a turbine 7, a waste heat boiler 8, a steam turbine 9, a generator 10, a cryogenic air separation unit 11, a heating humidifier 12, a water preheater 13 and other components and necessary pipelines. The environmental air is separated into oxygen and nitrogen by a cryogenic air separation unit 11, the oxygen is sent to a coal gasification unit 1 to be used as an oxidant for gasification, coal is gasified to generate crude synthesis gas, the crude synthesis gas passes through a coal gas purification and desulfurization unit 2 to remove solid particles and sulfides (H) in the crude synthesis gas₂S and COS), chlorides, ammonia, etc. into clean coal gas. One part of the coal gas is sent into a combustion chamber 6 of a gas turbine to be used as fuel gas, the other part of the coal gas is converted into carbon dioxide and hydrogen through water vapor of carbon monoxide in the coal gas by a coal gas conversion unit 3, and the carbon dioxide in the gas is separated by a coal gas decarbonization unit 4 to form synthesis gas with the hydrogen-carbon ratio meeting the downstream requirement. A compressor 5 of the gas turbine sucks air from the environment, before the ambient air enters the compressor 5, waste nitrogen returned from a deep cooling air separation unit 11 is mixed with carbon dioxide gas separated from a coal gas decarburization unit 4, the mixed nitrogen/carbon dioxide mixed gas enters from the bottom of a heating humidifier 12, and is in direct countercurrent contact with a large amount of hot water sprayed from the top in the heating humidifier 12, the nitrogen/carbon dioxide mixed gas is humidified and heated at the same time, and the nitrogen/carbon dioxide/water vapor mixed gas is mixed with the air and then enters the gas turbine compressor 5. In the heated humidifier 12, during the downward flow of the top-injected hot water, part of the water evaporates into the nitrogen/carbon dioxide gas, the temperature of the hot water decreases, and the heated humidifierThe cold water discharged from the bottom of the waste heat boiler 12 is sent to a water preheater 13 arranged at the tail of the waste heat boiler 8, and the cold water exchanges heat with the flue gas at the tail of the waste heat boiler to be heated and become hot water again, and then the hot water is sent to the top of the heating humidifier 12. In the heating humidifier 12, the amount of water reduced due to evaporation is supplemented by the replenishment water, thereby achieving water balance.

The mixed gas of nitrogen/carbon dioxide/steam is compressed by the compressor 5 and then sent into the combustion chamber 6, and after being combusted with the synthesis gas in the combustion chamber, the mixed gas becomes high-temperature and high-pressure gas to push the turbine 7 to do work, and the output work of the turbine 7 drives the generator 10 to generate electricity. The flue gas that turbine 7 discharged passes through exhaust-heat boiler 8 recovery heat and produces steam, promotes turbine 9 and does work. A water preheater 13 is provided at the rear of the exhaust-heat boiler 8 to heat water for heating the humidifier 12.

The above presents a simplified flow of a syngas turbine NOx emission reduction system using the present invention, applied to a coal gasification based gas turbine power generation and syngas co-production system. The core of the invention is that after the waste nitrogen and/or carbon dioxide which is useless in the system is heated and humidified by the waste heat which is useless in the system, the waste nitrogen and/or carbon dioxide is mixed with air at the inlet of the compressor of the gas turbine, so that the aim of reducing the NOx emission of the synthesis gas turbine is fulfilled. In practical application, nitrogen or carbon dioxide or a combination of the nitrogen and the carbon dioxide can be adopted to dilute inlet air of the compressor after heating and humidifying according to the requirements of different grades of combustion engines. The heating humidifier 12 of the present invention may be a packed tower or a hollow tower or other devices capable of heating and humidifying gas by using hot water energy.

The object of the present invention is fully effectively achieved by the above embodiments. Those skilled in the art will appreciate that the present invention includes, but is not limited to, what is described in the accompanying drawings and the foregoing detailed description. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications within the spirit and scope of the appended claims.