CN209213922U - An Efficiency Enhancement and Emission Reduction Device for Gas Turbines in IGCC Power Stations - Google Patents

Abstract

The utility model provides an efficiency-enhancing and emission-reducing device for gas turbines in IGCC power stations, including a sewage nitrogen collection device, wherein the sewage nitrogen collection device is installed on the sewage nitrogen pipeline of the gas turbine air separation device of the IGCC power station, and the sewage nitrogen collection device The outlet of the gas turbine in the IGCC power station is connected to the inlet of the compressor in the gas turbine of the IGCC power station; the polluted nitrogen gas discharged from the air separation unit is collected and cooled, and then passed into the combustion chamber to be mixed with the air and fuel passed into the combustion chamber for The oxygen content in the combustion chamber is reduced, thereby reducing the combustion temperature in the combustion chamber, so that the NOx emission of the gas turbine power generation system is greatly reduced.

Description

An Efficiency Enhancement and Emission Reduction Device for Gas Turbines in IGCC Power Stations

technical field

The utility model relates to the field of IGCC power stations, in particular to an efficiency-enhancing and emission-reducing device for a gas turbine of an IGCC power station.

Background technique

IGCC power station, that is, integrated coal gasification combined cycle power generation system, is an advanced power generation system that combines coal gasification technology and gas-steam combined cycle. It has high power generation efficiency and excellent environmental protection performance. It is an effective Development prospect of clean coal power generation technology. The IGCC power station is mainly composed of an air separation unit, a vaporizer, a synthesis gas purification unit, a gas turbine power generation system, a waste heat boiler and a steam turbine power generation system.

In the air separation unit, the air is compressed, cooled and rectified to obtain pure oxygen and nitrogen products. Pure oxygen is used for coal gasification, and pure nitrogen is used for transporting coal powder and purging pipelines. Dirty nitrogen equivalent to 1/4 of the air intake of the air separation unit. The composition of this part of dirty nitrogen is 96% (volume fraction) of N ₂ , 2% of O ₂ and 2% of Ar, the pressure is about 112Kpa (A), and it does not contain moisture at all, except for a small part for purging the air separation unit Outside the purification system, the rest are directly discharged to the atmosphere. The air separation unit evacuates excess nitrogen, which is a huge waste of energy.

The temperature of the atmosphere has a great influence on the power and efficiency of the gas turbine power generation system. Generally speaking, for every 10°C increase in the atmospheric temperature, the power of the gas turbine will decrease by 5%, and the efficiency will decrease by 0.1%.

For combustion devices, there are three main mechanisms of NOx generation, namely fuel-type NOx, rapid-type NOx and thermal-type NOx. The NOx emitted from the flue gas of the gas turbine system is mainly thermal NOx. When the local temperature in the combustion of the gas turbine is higher than 1800K, the thermal NOx generation rate increases exponentially, and the influence of the excess air coefficient on the thermal NOx is also very obvious. The thermal NOx generation is proportional to the square root of the oxygen concentration, that is, the oxygen The greater the concentration, the thermal NOx will increase accordingly. For some combustion equipment, in order to reduce the formation of thermal NOx, a common method is to circulate a part of the flue gas generated by combustion and introduce it into the combustion chamber at the same time as air and fuel. The principle is to reduce the oxygen content in the combustion chamber, thereby reducing the local high temperature.

It is known that reducing the inlet temperature of the gas turbine can increase the power generation of the gas turbine, and at the same time reducing the oxygen content of the air in the combustion chamber of the gas turbine can reduce the local high temperature, thereby reducing the NOx emission of the gas turbine.

Contents of the invention

The purpose of the utility model is to provide an efficiency-enhancing and emission-reducing device for gas turbines in IGCC power stations, which solves the problem of waste of energy caused by emptying the existing dirty nitrogen gas.

In order to achieve the above object, the technical scheme that the utility model adopts is:

The utility model provides an efficiency-enhancing and emission-reducing device for gas turbines in IGCC power stations, including a sewage nitrogen collection device, wherein the sewage nitrogen collection device is installed on the sewage nitrogen pipeline of the gas turbine air separation device of the IGCC power station, and the sewage nitrogen collection device The outlet of the gas turbine is connected to the inlet of the compressor in the gas turbine of the IGCC power station.

Preferably, a circulating heat exchange system for reducing the intake air temperature of the compressor is provided between the dirty nitrogen collection device and the compressor.

Preferably, the circulating heat exchange system includes a cooling tower, the air inlet of the cooling tower is connected to the outlet of the dirty nitrogen collection device, and the outlet of the cooled dirty nitrogen in the cooling tower is connected to the inlet of the compressor.

Preferably, the circulating heat exchange system further includes a water pump, and the water outlet of the water pump is connected to the water inlet provided at the upper end of the cooling tower.

Preferably, the air inlet of the cooling tower is arranged at the bottom.

Preferably, a heat exchange system for air is also provided between the intake pipes of the compressor.

Preferably, the heat exchange system is a heat exchanger.

Preferably, the device for collecting dirty nitrogen is a fan.

Compared with the prior art, the beneficial effects of the utility model are:

The utility model provides an efficiency-enhancing and emission-reducing device for gas turbines in IGCC power stations. After collecting the polluted nitrogen gas discharged from the air separation unit and cooling it down, it passes into the combustion chamber, and the air and gas passed into the combustion chamber The fuel is mixed to reduce the oxygen content in the combustion chamber, thereby reducing the local maximum temperature in the combustion chamber, while the average temperature remains basically unchanged, so that the NOx emissions of the gas turbine power generation system are greatly reduced.

Furthermore, through the circulation of cooling water between the water pump and the heat exchanger, the temperature of the inlet air of the compressor is reduced, thereby improving the power generation efficiency of the gas turbine power generation system.

Description of drawings

Fig. 1 is the structural representation of the utility model synergistic emission reduction device;

Figure 2 is the relationship between the reinjection rate of contaminated nitrogen and the NOx emission of the gas turbine;

Among them, 1. Dirty nitrogen pipeline 2. Fan 3. Intake pipeline 4. Heat exchanger 5. Water pump 6. Cooling tower 7. Compressor 8. Turbine 9. Waste gas pipeline 10. Fuel 11. Combustion chamber.

Detailed ways

The utility model is described in further detail below in conjunction with accompanying drawing and specific embodiment.

As shown in Figure 1, the utility model provides an efficiency-enhancing and emission-reducing device for gas turbines in IGCC power plants, including a blower fan 2 installed on a sewage nitrogen pipeline 1, and the outlet of the blower fan 2 is sequentially connected with a heat exchange cycle system, air compressor 7, combustor 11, turbine 8 and generator 12, wherein the cycle heat exchange system includes heat exchanger 4, water pump 5 and cooling tower 6, the outlet of fan 2 and the air inlet at the bottom of cooling tower 6 connected, the water outlet of the water pump 5 is connected to the water inlet on the upper end of the cooling tower 6, and the dirty nitrogen is mixed with the water droplets sprayed in the cooling tower 6 from bottom to top in the water cooling tower 6, thereby reducing the water and nitrogen in the cooling tower. The temperature of the dirty nitrogen; the water inlet of the water pump 2 is connected with the water outlet of the heat exchanger 4, and the water inlet of the heat exchanger 4 is connected with the water outlet of the cooling tower 6.

At the same time, the air outlet of the cooling tower 6 is connected to the air inlet of the compressor 7; the gas turbine air enters the heat exchanger 4 for cooling, and the cooled gas turbine air is mixed with the cooled dirty nitrogen gas into the compressor 7.

The device will firstly use the dirty nitrogen pipeline and fan 2 to collect the dirty nitrogen discharged from the air separation unit. The dirty nitrogen mainly comes from the sum of the dirty nitrogen discharged from the purification system of the air separation unit and the emptied dirty nitrogen.

The collected polluted nitrogen is sent to the bottom of the cooling tower 6, and is mixed with the water droplets sprayed in the cooling tower 6 from bottom to top. Because the dirty nitrogen gas is extremely dry and the water content is zero, part of the water droplets will evaporate and absorb a lot of heat during the contact with the water droplets, which will reduce the temperature of the water droplets and the dirty nitrogen gas; according to the experience of the water cooling tower of the air separation unit, it can be The water temperature dropped from 30°C to about 15°C.

The intake pipe 3 of the gas turbine system is connected to the heat exchanger 4, and the temperature of the air decreases after exchanging heat with the heat exchanger 4, that is, the intake air temperature of the gas turbine system is reduced. The relationship between the intake air temperature and the power generation and efficiency of the gas turbine is shown in Table 1.

In summer, when the atmospheric temperature is relatively high, such as 30°C, the heat exchanger can reduce the gas turbine inlet temperature to about 15°C. According to Table 1, the power of the gas turbine will increase by 6%, and the efficiency will increase 0.8%;

In winter, since the atmospheric temperature is relatively low and water is easy to freeze, the water in the water circulation heat exchange device composed of cooling tower 6, water pump 5 and heat exchanger 4 can be drained, that is, in winter, the circulation exchange system is disabled. Thermal device:

Table 1

After the polluted nitrogen passes through the cooling tower 6 for heat exchange, its own temperature also decreases to a certain extent, and then the air in the gas turbine inlet pipe 3 is mixed. The main purpose of the mixing is to reduce the NOx emission in the combustion chamber.

It is known that the NOx emitted from the flue gas of the gas turbine system mainly comes from the combustion chamber, and the formation mechanism of NOx is mainly thermal NOx. The known thermodynamic mechanism involves the following two chain reactions:

O+N ₂ →NO+N N.1

N+O ₂ →NO+O N.2

The activation energy of reaction N.1 is quite large (319050kJ/kmol), that is, this reaction has a strong relationship with temperature. As an empirical estimate, thermal mechanisms are generally insignificant at temperatures below 1800K, but the rate of thermal NOx formation increases exponentially above 1800K in combustion localized temperatures.

The fuel used by the gas turbine in the IGCC power station is hydrogen-rich syngas fuel10, and the combustion method basically adopts the diffusion combustion method. Mixing dirty nitrogen and air into the combustion chamber 11 and syngas 10 for combustion reduces the _O2 content in the air, thereby reducing the local high temperature in the combustion chamber 11 and reducing the NOx emissions in the exhaust gas 9 of the combustion engine; The high-temperature flue gas generated in the chamber 11 drives the turbine 8 to do work and drives the generator 12 .

As shown in Figure 2, it is the relationship between the reinjection rate of polluted nitrogen gas and the NOx emission of the combustion engine, where the reinjection rate of polluted nitrogen gas is the percentage of the volume of polluted nitrogen gas and the volume of air. Can reduce NOx emissions by about 10%. According to the operating data of an IGCC power plant, the air intake volume of a 170MW gas turbine at full load is about 522kg/s, and the nitrogen pollution volume of the air separation unit is about 28.5kg/s. Then, when the gas turbine is running at full load, according to calculations, the local high temperature of the combustion chamber can be reduced by about 50°C, and the emission of NOx can be reduced by about 10mg/ ^m3 ; at the same time, the intake temperature of the compressor 7 can be reduced by about 15°C. ℃, according to Table 1, ideally, the power generation can be increased by about 10MW. Therefore, the device can not only improve the efficiency and power generation of the gas turbine system of the IGCC power station, but also reduce its NOx emissions.

Claims (8)

1. a kind of synergy emission reduction device for the power station IGCC combustion engine, which is characterized in that including dirty nitrogen collection device, wherein Dirty nitrogen collection device is mounted on the power station IGCC combustion engine air separation unit dirt nitrogen pipeline (1), the outlet of dirty nitrogen collection device It is connect with compressor (7) import in the combustion engine of the power station IGCC.

2. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 1, it is characterised in that, dirty nitrogen It is provided between collection device and compressor (7) for reducing the circulating heat exchange system of compressor (7) inlet temperature.

3. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 1, it is characterised in that, circulating picture-changing Hot systems include cooling tower (6), and the air inlet of the cooling tower (6) is connect with the outlet of dirty nitrogen collection device, cooling tower (6) Dirty nitrogen gas outlet after middle cooling is connect with compressor (7) import.

4. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 3, it is characterised in that, circulating picture-changing Hot systems further include water pump (5), and water inlet of the water outlet of the water pump (5) with setting in cooling tower (6) upper end is connect.

5. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 4, it is characterised in that, cooling tower (6) air inlet is arranged in bottom.

6. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 1, which is characterized in that compressor (7) heat-exchange system for cooling air is additionally provided in admission line (3).

7. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 6, which is characterized in that heat exchange system System is heat exchanger (4).

8. a kind of synergy emission reduction device for the power station IGCC combustion engine according to claim 1, which is characterized in that dirty nitrogen Collection device be blower (2).