CN110375330A - A kind of classification oxygen supply combustion chamber and gas turbine classification oxygen supply combustion method - Google Patents

Abstract

The invention discloses a staged oxygen supply combustion chamber suitable for an oxygen-enriched combustion gas turbine and a staged combustion method. The staged oxygen supply combustor is divided into main combustion zone, secondary combustion zone and mixing zone. The front end of the main combustion zone is provided with a main nozzle for injecting fuel, primary oxygen and primary carbon dioxide. The front of the secondary combustion zone is provided with secondary nozzles for injecting secondary oxygen and secondary carbon dioxide. The blending area is provided with blending holes for introducing third-stage carbon dioxide. Under low load conditions, all fuel and oxygen are supplied to the main combustion area, so that the fuel is lean-burned in the main combustion area, reducing CO emissions; under high load conditions, the secondary oxygen supply in the secondary combustion area is increased, so that the fuel For rich combustion, reduce NOx emissions. The invention has the advantages of wide operating load adjustment range (high adjustable ratio), low CO and NOx emissions, and the like.

Description

A staged oxygen supply combustor and gas turbine staged oxygen supply combustion method

technical field

The invention relates to a graded oxygen supply combustion chamber suitable for an oxygen-enriched combustion gas turbine and a graded oxygen supply combustion method thereof, belonging to the technical field of power generation.

Background technique

Oxygen-enriched combustion gas turbines use carbon dioxide as the circulating working medium and oxygen as the oxidant to burn high-temperature gas to drive the turbine to rotate, drive the generator to generate electricity or drive other loads, and use oxygen and carbon dioxide instead of air to greatly reduce nitrogen oxide emissions and It is conducive to the capture of carbon dioxide emissions and is a highly efficient power device that can achieve ultra-low emissions. At the same time, due to the low critical temperature and pressure of carbon dioxide, it is easy to realize in engineering, so that its subcritical or supercritical fluid properties can be used to improve cycle performance. Therefore, this oxygen-enriched gas turbine using carbon dioxide as a working medium has attracted extensive attention from scientific research institutions and energy companies around the world. The gas turbine cycle using oxyfuel combustion technology mainly includes subcritical and supercritical carbon dioxide gas turbine cycles. Subcritical carbon dioxide gas turbines have low pressure (less than 3MPa), and are relatively easy to implement technically; while supercritical carbon dioxide gas turbines have the advantages of high power density and compact volume due to their high working pressure (30MPa), and high pressure is more conducive to Carbon dioxide carbon capture and storage to reduce greenhouse gas emissions.

Due to the rapid development of renewable energy, it is necessary to use thermal power for peak regulation, and the gas turbine is a device with better performance under variable conditions, so improving the low-load operation capacity of gas turbines and expanding the operating range under variable conditions is an important trend in the development of gas turbines . This is a challenge for oxy-combustion gas turbines that use carbon dioxide as the working fluid.

This is because in an oxygen-rich combustor, the flame temperature is not only related to the stoichiometric ratio (φ), but also related to the molar ratio (α) of oxygen to carbon dioxide. Since it takes a lot of energy to separate oxygen from air, it is necessary to save oxygen in order to improve the efficiency of power generation, and the stoichiometric ratio of fuel to oxygen in the entire combustion chamber should be close to 1. When the stoichiometric ratio is constant, as α increases, the flame temperature increases. On the contrary, the flame temperature decreases. At the same time, the high concentration of carbon dioxide in the combustion chamber will reduce the combustion temperature and combustion rate, resulting in easy flameout under low load conditions, insufficient combustion of fuel and oxygen, and high emissions of carbon monoxide and oxygen in combustion products. In addition, when the traditional oxygen-enriched combustor reduces the operating load of the gas turbine, the mass flow rate of fuel is reduced, and the mass flow rate of oxygen is correspondingly reduced when the stoichiometric ratio is guaranteed to be 1, thereby reducing the molar ratio of oxygen to carbon dioxide when the mass flow rate of carbon dioxide remains unchanged (α), which leads to a decrease in the outlet temperature of the combustor, resulting in higher carbon monoxide and oxygen emissions of the oxygen-enriched gas turbine during low-load operation, and a smaller range of operating conditions. Carbon monoxide and oxygen emissions not only reduce energy utilization efficiency, but also cause corrosion to the carbon dioxide delivery pipeline at the tail end of the gas turbine. Therefore, considering the application limitations of traditional combustors in oxyfuel combustion gas turbines, it is necessary to improve the combustor to improve the low-load operation capability of oxyfuel combustion gas turbines, broaden its variable operating range, and reduce carbon monoxide and oxygen emissions. Energy efficiency of the device.

Contents of the invention

The present invention aims to provide a staged oxygen supply combustion chamber and its operation method. By dividing the combustion chamber into a main combustion zone, a secondary combustion zone and a blending zone, and supplying oxygen in two stages through the main combustion zone and the secondary combustion zone, The carbon dioxide is supplied in three stages through the main combustion zone, the secondary combustion zone and the blending zone, which not only improves the low-load operation capacity of the gas turbine, reduces carbon monoxide and oxygen emissions, but also reduces NOx emissions under high loads through graded oxygen supply, thereby expanding oxygen-enriched combustion The range of operating conditions for gas turbines.

The present invention is realized through the following technical solutions:

A staged oxygen supply combustor, the staged oxygen supply combustor can be used for a fuel-rich gas turbine, the staged oxygen supply combustor is provided with at least one, and the staged oxygen supply combustor includes a combustor casing and a combustor casing The inner flame tube, the flame tube is a cylindrical structure with an arc-shaped contraction at one end, and the working medium gas channel is between the flame tube and the outer casing of the combustion chamber. According to the front and back direction of the airflow in and out, the inside of the flame tube is divided into main combustion zone, secondary combustion zone and mixing zone from front to back; the front end of the main combustion zone is provided with a main nozzle; the wall of the secondary combustion zone is provided with More than two secondary nozzles, the secondary nozzles include secondary oxygen nozzles and secondary carbon dioxide nozzles, the secondary carbon dioxide nozzles communicate with the working medium gas channel; the secondary nozzles are surrounded by the end near the main combustion zone The secondary combustion zone is arranged symmetrically or evenly; the wall of the mixing zone is provided with a number of mixing holes, and the mixing holes are evenly arranged around the mixing zone.

In the above technical solution, the main nozzle includes a fuel channel, a main oxygen channel and a main carbon dioxide channel, and the main carbon dioxide channel communicates with the working medium gas channel between the flame tube and the combustor jacket.

In the above technical solution, the combustion chamber further includes a swirler arranged at the front of the main nozzle and an ignition device arranged at the front of the main combustion zone.

A gas turbine includes a compressor arranged in sequence, the above-mentioned staged oxygen supply combustor, and a turbine, wherein at least one staged oxygen supply combustor is provided.

A gas turbine staged oxygen supply combustion method, which uses the gas turbine as described above, said method comprising:

According to the limit temperature of the main combustion zone of the staged oxygen supply combustor of the gas turbine, the maximum oxygen content of the main combustion zone is calculated;

After the carbon dioxide is compressed by the compressor, it is sent as a working medium into the working medium gas channel formed between the combustor casing and the flame tube, so that the carbon dioxide enters the main stage of the staged oxygen supply combustor through the main nozzle, the secondary carbon dioxide nozzle and the mixing hole respectively. The combustion zone, the secondary combustion zone and the mixing zone respectively form the first-level carbon dioxide, the second-level carbon dioxide and the third-level carbon dioxide injection;

Supply an appropriate amount of fuel into the main combustion zone through the main nozzle of the staged oxygen supply combustor of the gas turbine;

Set the stoichiometric ratio φ of the fuel to the total oxygen as 0.9≤φ≤1, and calculate the total oxygen flow according to the stoichiometric ratio, and compare the total oxygen flow with the maximum oxygen content of the main combustion zone;

When the total oxygen flow rate is less than or equal to the maximum oxygen content of the main combustion zone, oxygen is sprayed into the main combustion zone through the main nozzle; Lean-burn combustion of _{0.9≤φPZ≤1} is formed in the combustion zone to generate high-temperature gas; the high-temperature gas from the main combustion zone is mixed with secondary carbon dioxide fed through the secondary nozzle to form high-temperature flue gas;

When the total oxygen flow rate is greater than the maximum oxygen content of the main combustion zone, the oxygen enters the main combustion zone and the secondary combustion zone through the main nozzle and the secondary oxygen nozzle respectively, forming a primary oxygen supply and a secondary oxygen supply; and passing through the main nozzle The amount of primary oxygen entering the main combustion zone is the maximum amount of oxygen in the main combustion zone; the fuel, oxygen and carbon dioxide entering through the main nozzle are mixed and ignited, and the fuel and oxygen form a rich combustion in the main combustion zone to generate High-temperature gas: mix the high-temperature gas from the main combustion zone with the secondary oxygen and secondary carbon dioxide fed through the secondary nozzles in the secondary combustion zone and completely burn the incomplete combustion components in the high-temperature gas to generate high-temperature flue gas;

Inject tertiary carbon dioxide through the mixing hole, mix with the high-temperature flue gas from the secondary combustion zone to reduce the temperature of the high-temperature flue gas, and enter the turbine to do work; after the flue gas passes through the turbine to do work, the temperature is reduced and becomes exhaust gas, the main components of which are carbon dioxide and steam;

The exhaust gas is separated to obtain dry flue gas and condensed water with carbon dioxide as the main component, and part of the dry flue gas is used as recirculation gas. After mixing and adjustment, it is sent to the compressor for compression and boosting. The working gas channel formed between the barrels.

When the gas turbine further includes a condenser, a separation valve, a mixing valve, and a carbon dioxide storage tank connected to the mixing valve, the method further includes:

Let the exhaust gas enter the condenser to recover waste heat, and enter the separation valve for steam-water separation, separate the gas with carbon dioxide as the main component and water to obtain dry flue gas; part of the separated dry flue gas is used as recirculation gas, enter the mixing valve, and After adjusting the flow rate through the carbon dioxide storage tank, it enters the compressor to compress and increase the pressure, and sends it as a working medium into the working medium gas channel formed between the combustor casing and the flame tube.

In the above technical scheme, the carbon dioxide enters the main combustion zone, the secondary combustion zone and the mixing zone of the staged oxygen supply combustor respectively through the main nozzle, the secondary carbon dioxide nozzle and the mixing hole, and the formed primary carbon dioxide, secondary carbon dioxide and The three-stage carbon dioxide injection ratio is (50-60):(5-20):(20-45).

In the above technical solution, the staged oxygen supply combustion method also includes a staged regulation method, and the staged regulation method includes:

The load of the gas turbine is gradually increased, so that the fuel supplied to the main combustion zone through the main nozzle of the staged oxygen supply combustion chamber is gradually increased;

According to the stoichiometric ratio φ of fuel and oxygen, the total oxygen flow rate is adjusted. When the total oxygen flow rate is less than or equal to the maximum oxygen content of the main combustion zone, the oxygen is adjusted to be injected into the main combustion zone through the main nozzle of the staged oxygen supply combustion chamber, so that The primary oxygen ratio is 100%; when the oxygen flow continues to increase and is greater than the maximum oxygen content of the main combustion zone, part of the oxygen exceeding the maximum oxygen content of the main combustion zone will be injected into the secondary combustion zone as secondary oxygen through the secondary oxygen nozzle .

In the above technical solution, the hierarchical adjustment method also includes:

The gas turbine load is gradually reduced, so that the fuel supplied to the main combustion zone through the main nozzle of the staged oxygen supply combustion chamber is gradually reduced;

According to the stoichiometric ratio φ of fuel and oxygen, the total oxygen flow rate is reduced. When the total oxygen flow rate is greater than the maximum oxygen intake in the main combustion zone, the total oxygen flow rate is reduced in sequence in the order of first reducing the secondary oxygen supply and then reducing the primary oxygen supply. Oxygen amount; when the total oxygen flow rate is less than or equal to the maximum oxygen content of the main combustion area, reduce the primary oxygen amount of the main combustion area.

The invention has the following advantages and beneficial effects: 1) Oxygen is fed in two stages, and the distribution ratio between the two stages is dynamically adjusted with the load, which widens the operating load range of the gas turbine; The combustion mode of the main combustion zone) is rich combustion at high load, and gradually transitions to equivalence ratio combustion as the load decreases, so that the main combustion zone maintains stable combustion at high load and reduces pollutant emissions as a whole, while at low Stable combustion can be maintained under load to avoid flameout and shutdown; 3) Carbon dioxide is fed in three stages, the second stage of carbon dioxide protects the second stage oxygen nozzle, and the third stage of carbon dioxide can effectively reduce the gas temperature of the combustion chamber.

Description of drawings

Fig. 1 is a schematic diagram of the oxy-fuel combustion gas turbine cycle system involved in the present invention.

Fig. 2 is a schematic diagram of a staged oxygen supply combustion chamber involved in the present invention.

Fig. 3 is a schematic diagram (A-A view) of the layout of the secondary nozzles of the staged oxygen supply combustor involved in the present invention.

Fig. 4 is a schematic diagram of adjusting operating parameters of the combustion chamber of the gas turbine involved in the present invention.

In the figure: 1-stage oxygen supply combustor; 2-turbine; 3-generator; 4-condenser; 5-separation valve; 6-mixing valve; 7-compressor; 8-air separator; 9-connecting shaft ; 11—flame cylinder; 12—main nozzle; 121—fuel passage; Mixing hole; 15-main combustion zone; 16-secondary combustion zone; 17-mixing zone; 18-diverter valve.

Detailed ways

The specific embodiment of the present invention and working process will be further described below in conjunction with accompanying drawing.

The orientation terms such as up, down, left, right, front and rear in this application document are established based on the positional relationship shown in the drawings. If the drawings are different, the corresponding positional relationship may also change accordingly, so this should not be understood as limiting the scope of protection.

The oxygen-enriched combustion gas turbine mentioned in the present invention refers to that the gas turbine operates under the oxygen-enriched combustion condition of burning an oxygen-containing gas higher than the oxygen content of air (20.947%). At this time, based on the stoichiometric ratio (φ) of fuel and oxygen, there are three combustion states, namely rich combustion (φ>1), equivalent combustion (φ=1) and lean combustion (φ<1). Equivalent combustion means that fuel and oxygen are burned according to the stoichiometric ratio of complete combustion. During actual operation, since fuel and oxygen are supplied dynamically, φ≈1 is regarded as equivalent combustion. The combustion state of the fuel relative to oxygen rich (Fuel rich) is rich combustion, conversely the combustion state of fuel relatively oxygen deficient (Fuel lean) is lean combustion.

As shown in Figure 1, the oxyfuel combustion gas turbine cycle system includes a staged oxygen supply combustor 1, a turbine 2 and a generator 3 connected in sequence, and the turbine 2 is also connected in sequence with a condenser 4 and a separation valve 5, the separation valve 5, the mixing valve 6 and the compressor 7 are connected in sequence, and the separated carbon dioxide is mixed and compressed and sent back to the staged oxygen supply combustor 1. The air separator 8 is connected with the staged oxygen supply combustion chamber 1, and separates the oxygen in the air from other gases such as nitrogen and carbon dioxide, and sends the oxygen into the staged oxygen supply combustion chamber 1. The connecting shaft 9 is respectively connected between the turbine 2 and the generator 3 and between the turbine 2 and the compressor 7, so as to realize the transmission between the turbine 2, the compressor 7 and the generator 3, and transfer the work of the turbine 2 to the generator 3 to generate electricity. At least one staged oxygen supply combustion chamber 1 is provided, and when more than two staged oxygen supply combustion chambers are provided, the multiple staged oxygen supply combustion chambers are arranged in an annular or cylindrical shape around the axis.

As shown in FIG. 2 , the staged oxygen supply combustor 1 includes a combustor casing and a flame tube 11 arranged in the combustor casing. The flame tube 11 is a cylindrical structure with an arc-shaped contraction at one end. There is a gas passage for the working medium between the flame tube 11 and the outer casing of the combustion chamber. For an oxygen-enriched combustion gas turbine, the working medium is carbon dioxide. According to the front-to-back direction of the incoming and outgoing airflow, the inside of the flame tube 11 is divided into a main combustion zone 15, a secondary combustion zone 16 and a mixing zone 17 from front to back.

The front end of the main combustion zone 15 is provided with a main nozzle 12 . The main nozzle 12 includes a fuel channel 121 , a main oxygen channel 122 and a main carbon dioxide channel, and the main carbon dioxide channel communicates with the working medium gas channel between the flame tube and the combustor jacket. Fuel is injected through the fuel channel 121 , primary oxygen is injected through the main oxygen channel 122 , and primary carbon dioxide is injected through the main carbon dioxide channel. The combustion chamber also includes a swirler 123 arranged at the front of the main nozzle 12 and an ignition device arranged at the front of the main combustion zone 15 . The swirler 123 is arranged at the front of the main nozzle with the fuel passage 121 as the central axis, and is used for swirling and mixing the primary oxygen and the primary carbon dioxide.

The wall surface of the secondary combustion zone 16 is provided with more than two secondary nozzles 13 . The secondary nozzle 13 includes a secondary oxygen nozzle 131 and a secondary carbon dioxide nozzle 132, and the secondary carbon dioxide nozzle 132 communicates with the working gas channel. One of the implementations is that the secondary oxygen nozzle 131 is arranged at the center, and the secondary carbon dioxide nozzle 132 is arranged around the secondary oxygen nozzle 131 in a concentric circle structure, so that the secondary carbon dioxide entrains the secondary oxygen injection, and is connected with the primary Incoming flames in the combustion zone produce cross-jet mixing. The end of the secondary nozzles 13 close to the primary combustion zone 15 is arranged symmetrically or uniformly around the secondary combustion zone 16 , as shown in FIG. 3 .

The wall surface of the mixing zone 17 is provided with several mixing holes 14, and the mixing holes 14 are evenly arranged around the mixing zone 17.

The oxygen injected into the main combustion zone 15 through the main nozzle 12 of the staged oxygen combustion chamber 1 is regarded as primary oxygen, and the oxygen injected into the secondary combustion zone 16 through the secondary oxygen nozzle 131 is regarded as secondary oxygen. Oxygen is obtained by separating air through an air separator 8 . The total oxygen supply is , the primary and secondary oxygen ratios are and in

During operation, firstly, the maximum oxygen intake in the main combustion zone 15 is calculated according to the limit temperature of the main combustion zone 15 of the staged oxygen supply combustor 1 of the gas turbine. The limit temperature of a gas turbine combustor is determined by its material. The temperature of the main combustion zone is directly related to the amount of fuel, oxygen and carbon dioxide. When the flow rate of carbon dioxide as the working medium is constant, the heat of combustion increases with the increase of the amount of fuel and oxygen in the main combustion zone. Due to the constant flow rate of carbon dioxide, the temperature in the main combustion zone continues to rise and reaches the main combustion zone. At this time, if the oxygen supply to the main combustion zone continues to increase, the temperature of the main combustion zone will inevitably exceed the limit temperature, resulting in erosion of the main nozzle and affecting the operation of the gas turbine. In order to avoid nozzle corrosion, the oxygen supply corresponding to the limit temperature is the maximum oxygen intake in the main combustion zone, which is also the critical point for the regulation of the staged oxygen supply combustion in the present invention.

After being compressed by the compressor 7, the carbon dioxide is sent as a working medium into the working medium gas channel formed between the combustor casing and the flame tube 11, so that the carbon dioxide enters the graded supply through the main nozzle 12, the secondary carbon dioxide nozzle 132 and the mixing hole 14 respectively. The main combustion zone 15, the secondary combustion zone 16 and the mixing zone 17 of the oxygen combustion chamber 1 respectively form a primary carbon dioxide, a secondary carbon dioxide and a tertiary carbon dioxide injection. Wherein, the ratio of primary carbon dioxide y ₁ , secondary carbon dioxide y ₂ and tertiary carbon dioxide y ₃ is (50-60):(5-20):(20-45).

An appropriate amount of fuel corresponding to the load is all fed into the main combustion zone 15 through the main nozzle 12 of the staged oxygen supply combustor 1 of the gas turbine.

The stoichiometric ratio φ of fuel to total oxygen is set to 0.9≤φ≤1, since oxygen is obtained through air separation and the cost is relatively high, the selection of φ should be as close as possible to equivalent combustion while ensuring sufficient combustion. The total oxygen flow rate is calculated according to the stoichiometric ratio of the amount of fuel to the amount of oxygen, that is In the formula, k is the fuel coefficient for the conversion of mass flow rate and stoichiometric equivalent. Compare the total oxygen flow with the maximum oxygen content of the main combustion zone 15.

When the total oxygen flow rate is less than or equal to the maximum amount of oxygen in the main combustion zone 15, oxygen is sprayed into the main combustion zone 15 through the main nozzle 12; the fuel, oxygen and carbon dioxide entering through the main nozzle 12 are mixed and the fuel is ignited, and the fuel and oxygen are mixed. In the main combustion zone 15 , a lean-burn combustion of 0.9≤φ _PZ ≤1 is formed to generate relatively fully combusted high-temperature gas. Mix the high-temperature gas from the main combustion zone 15 with the secondary carbon dioxide fed through the secondary nozzle 13, and continue to burn completely in the secondary combustion zone 16 by increasing the residence time of the gas to generate high-temperature flue gas.

When the total oxygen flow rate is greater than the maximum oxygen content of the main combustion zone 15, the oxygen enters the main combustion zone 15 and the secondary combustion zone 16 through the main nozzle 12 and the secondary oxygen nozzle 132 respectively to form primary oxygen and secondary oxygen. At this time, the amount of primary oxygen entering the main combustion zone 15 through the main nozzle 12 is the maximum amount of oxygen in the main combustion zone. The fuel, oxygen and carbon dioxide entering through the main nozzle 12 are mixed and ignited, and the fuel and oxygen form rich combustion in the main combustion zone 15 to generate high-temperature gas. The high-temperature gas advances toward the turbine 2 and enters the secondary combustion zone 16 . The high-temperature gas from the main combustion zone 15 is mixed with the secondary oxygen and carbon dioxide fed through the secondary nozzle 13, so that the incomplete combustion components (such as CO) in the high-temperature gas are completely combusted with O ₂ to generate high-temperature flue gas . At the same time, the injection of the secondary carbon dioxide forms a low-temperature protection for the secondary nozzle 13 to avoid corrosion caused by high combustion temperatures.

Carbon dioxide is injected through the mixing hole 14, mixed with the high-temperature flue gas from the secondary combustion zone 16 to lower the temperature of the high-temperature flue gas, enters the turbine 2 to do work, and drives the generator 3 to generate electricity. After the flue gas passes through the turbine 2, the temperature is lowered to become exhaust gas, and the main components of the exhaust gas are carbon dioxide and water vapor.

The exhaust gas is separated through the separation valve 5 to obtain dry flue gas and condensed water with carbon dioxide as the main component, part of the dry flue gas is used as recirculation gas, and the rest of the dry flue gas enters the carbon capture device. The recirculated gas enters the regulating valve 6, is mixed and regulated by increasing/decreasing the flow rate of carbon dioxide through the carbon dioxide storage tank, and then sent to the compressor 7 for compression and boosting, as a working medium, it is sent to the working medium gas channel formed between the combustor jacket and the flame tube 11 .

When the gas turbine load changes, no matter the load increases or the load decreases, the essence is to ensure the oxygen supply of the main combustion zone first, that is, the primary oxygen first increases and then decreases.

When the gas turbine load gradually increases, the fuel supplied to the main combustion zone 15 through the main nozzle 12 of the staged oxygen supply combustor 1 gradually increases. Adjust the total oxygen flow rate according to the stoichiometric ratio φ of fuel and oxygen. When the total oxygen flow rate is less than or equal to the maximum oxygen content of the main combustion zone, the oxygen is adjusted to be injected into the main combustion zone through the main nozzle 12 of the staged oxygen supply combustion chamber 1. 15. Make the primary oxygen ratio 100%; when the oxygen flow continues to increase and is greater than the maximum oxygen content of the main combustion zone, part of the oxygen exceeding the maximum oxygen content of the main combustion zone is injected into the secondary combustion zone through the secondary oxygen nozzle 132 16.

And when the gas turbine load gradually decreases, the fuel supplied to the main combustion zone 15 through the main nozzle 12 of the staged oxygen supply combustor 1 is gradually reduced. At this time, the total oxygen flow rate is still adjusted according to the stoichiometric ratio φ of the fuel and the oxygen amount, and the total oxygen amount is successively reduced in the order of first reducing the second-level oxygen and then reducing the first-level oxygen. The specific reduction method is: when the total oxygen flow rate is greater than the maximum oxygen content of the main combustion zone, only the secondary oxygen volume is reduced, and the primary oxygen volume remains unchanged; when the total oxygen flow rate is reduced to less than or equal to the maximum oxygen content of the main combustion area When the amount is increased, stop the secondary oxygen, only supply oxygen to the main combustion zone, and gradually reduce the amount of primary oxygen.

Under normal operating conditions, that is, when the gas turbine is operating at a load greater than 30%, the CO2 flow rate is usually constant. When the load decreases to a certain level (usually below 30%, especially close to shutdown), since the required working fluid has been greatly reduced, it is necessary to gradually reduce the flow rate of carbon dioxide until shutdown. At this time, the excess carbon dioxide can be recovered by using the carbon dioxide storage tank through the regulating valve 6; or the excess carbon dioxide can be discharged by using the separation valve 5 for carbon collection.

Correspondingly, during the start-up process of the gas turbine, the carbon dioxide flow rate also needs to be gradually increased, and after reaching a certain load (usually 30%), the carbon dioxide flow rate remains unchanged.

Fig. 4 is one embodiment of applying the staged oxygen supply combustion method of the present invention, and shows the change of the load control range of the staged combustion gas turbine relative to the operating load range of the traditional gas turbine. As shown in the figure, the range of about 30% to 70% of the gas turbine load is the range where the main combustion zone maintains a near-equivalent combustion state of φ _PZ ≈ 1 and the temperature increases with the increase of load. At this time, the fuel and oxygen in the staged combustion chamber are all supplied through the main nozzle of the main combustion zone, and the carbon dioxide is supplied in three _stages . The amount of fuel, total oxygen and primary oxygen increase synchronously. φ, at this stage, the fuel in the main combustion zone maintains a near-equivalent combustion state of φ _PZ ≈ 1. Both the secondary combustion zone and the mixing zone serve as cooling zones for further mixing of high-temperature gas and working fluid. Since the working fluid is supplied in three stages, the carbon dioxide in the main combustion area is greatly reduced, which is equivalent to maintaining sufficient oxygen supply in a small area (main combustion area), so that the high-temperature flame of the fuel can be maintained and the combustion is sufficient, making the low-load state It avoids the high concentration of CO or even the shutdown due to the difficulty in maintaining the temperature of the fuel flame due to the excessive flow of the working fluid and the insufficient local oxygen supply. This is the problem that is difficult to overcome in the low-load state of the rich-burn gas turbine with the traditional combustor. Therefore, the staged oxygen supply combustion method greatly expands the low-load operating range of the rich-burn gas turbine.

When the load further increases, the amount of fuel continues to increase, and at this time the oxygen supply of the main combustion zone no longer increases (therefore, the φ _PZ of the main combustion zone shows a gradual increase trend), but by increasing the secondary oxygen, the fuel is first in the main combustion zone. The combustion zone performs rich combustion to generate incompletely combusted high-temperature gas. The high-temperature gas enters the secondary combustion zone for further combustion, which not only prevents the main combustion zone from exceeding the limit temperature, but also ensures the full combustion of the fuel, and also makes NOx under high load Emissions are greatly reduced. This is due to the fact that oxygen is separated from the air, so a small amount of nitrogen will inevitably be contained in the oxygen, resulting in the formation of NOx during the combustion process. Combustion greatly reduces the formation of NOx. Therefore, the staged combustion method not only widens the low-load operation range of the gas turbine, but also reduces the NOx emission of the gas turbine during high-load operation.

In short, the present invention forms staged oxygen supply combustion through staged supply of oxygen (oxidant) and staged supply of carbon dioxide (working fluid), flexibly adjusts the distribution ratio of oxygen in each combustion zone of the combustion chamber, improves the combustion stability of the main combustion zone, and Through the low temperature protection function of the working fluid, the problem of high temperature damage is avoided. When the combustion chamber is running at low load, increase the oxygen distribution ratio of the main combustion zone (thereby increasing the α _PZ of the main combustion zone) to increase the flame temperature of the main combustion zone, avoiding the increase of carbon monoxide and oxygen emissions and flameout due to low flame temperature And other problems, thereby broadening the range of operating conditions of the combustion chamber. When the combustion chamber is in a high-load condition, reduce the oxygen distribution ratio of the main combustion area to prevent the flame temperature in the main combustion area from exceeding the limit temperature that the material can withstand, and avoid the flame tube and nozzle melting and tempering caused by excessive flame temperature And other issues.

The staged oxygen-supply combustion method described above is applicable to conventional oxygen-enriched combustion gas turbines, and also applicable to subcritical and supercritical oxygen-enriched combustion gas turbines.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A staged oxygen supply combustor, the staged oxygen supply combustor (1) can be used for a fuel-rich gas turbine, and the staged oxygen supply combustor (1) is provided with at least one, and the staged oxygen supply combustor (1) ) comprises a combustion chamber casing and a flame cylinder (11) arranged in the combustion chamber casing, the flame cylinder (11) is a cylindrical structure with an arc-shaped contraction at one end, the flame cylinder (11) and the combustion chamber There is a working medium gas channel between the outer jackets, and it is characterized in that, according to the direction of the air flow in and out, the flame tube (11) is divided into the main combustion zone (15), the secondary combustion zone (16) and the Blending zone (17); the front end of the main combustion zone (15) is provided with a main nozzle (12); the wall surface of the secondary combustion zone (16) is provided with more than two secondary nozzles (13), and the secondary nozzles (13) comprising a secondary oxygen nozzle (131) and a secondary carbon dioxide nozzle (132), the secondary carbon dioxide nozzle (132) is communicated with the working medium gas channel; the secondary nozzle (13) is close to the main combustion zone (15) One end surrounds the secondary combustion zone (16) symmetrically or uniformly; the wall of the blending zone (17) is provided with some blending holes (14), and the blending holes (14) surround the blending zone ( 17) Arrange evenly. 2. The staged oxygen supply combustion chamber according to claim 1, characterized in that, the main nozzle (12) comprises a fuel passage (121), a main oxygen passage (122) and a main carbon dioxide passage, and the main carbon dioxide passage is connected with The working medium gas channel between the flame tube and the outer casing of the combustion chamber is in communication. 3. The staged oxygen supply combustion chamber according to claim 2, characterized in that, the combustion chamber also comprises a swirler (123) arranged at the front portion of the main nozzle (12) and arranged at the main combustion zone ( 15) The ignition device at the front end. 4. A gas turbine, characterized in that it comprises a compressor (7) connected in sequence, a staged oxygen supply combustor (1) as claimed in any one of claims 1-3, and a turbine (2), Wherein the staged oxygen supply combustion chamber (1) is provided with at least one. 5. A gas turbine staged oxygen supply combustion method, which uses the gas turbine as claimed in claim 4, is characterized in that, said method comprises: According to the limit temperature of the main combustion zone (15) of the staged oxygen supply combustor (1) of the gas turbine, the maximum oxygen intake of the main combustion zone (15) is calculated; The carbon dioxide is compressed by the compressor (7) and sent as a working medium into the working medium gas channel formed between the combustor casing and the flame tube (11), so that the carbon dioxide passes through the main nozzle (12) and the secondary carbon dioxide nozzle (132) respectively. and the mixing hole (14) enter the main combustion zone (15), the secondary combustion zone (16) and the mixing zone (17) of the staged oxygen supply combustor (1), respectively forming a first-level carbon dioxide, a second-level carbon dioxide and a third-level Injection of carbon dioxide; An appropriate amount of fuel is supplied to the main combustion zone (15) through the main nozzle (12) of the staged oxygen supply combustor (1) of the gas turbine; The stoichiometric ratio φ of the fuel and the total oxygen amount is set as 0.9≤φ≤1, and the total oxygen flow is calculated according to the stoichiometric ratio, and the total oxygen flow is compared with the maximum oxygen content of the main combustion zone (15); When the total oxygen flow is less than or equal to the maximum amount of oxygen in the main combustion zone (15), oxygen is injected into the main combustion zone (15) through the main nozzle (12); the fuel, oxygen and carbon dioxide entering through the main nozzle (12) are Mix and ignite the fuel, and make the fuel and oxygen form a lean combustion of _{0.9≤φPZ≤1} in the main combustion zone (15), generating high-temperature gas; make the high-temperature gas from the main combustion zone (15) pass through the secondary nozzle (13) The secondary carbon dioxide introduced is mixed to form high-temperature flue gas; When the total oxygen flow rate is greater than the maximum amount of oxygen in the main combustion zone (15), oxygen is made to enter the main combustion zone (15) and the secondary combustion zone (16) through the main nozzle (12) and the secondary oxygen nozzle (132) respectively, Form one-level oxygen supply and secondary oxygen supply; And the one-level oxygen amount that enters main combustion zone (15) by main nozzle (12) is the maximum oxygen content of main combustion zone; Make the fuel that enters by main nozzle (12), Oxygen and carbon dioxide mix and ignite the fuel, and make the fuel and oxygen form rich combustion in the main combustion zone (15) to generate high-temperature gas; make the high-temperature gas from the main combustion zone (15) pass through the secondary nozzle (13) The input secondary oxygen and secondary carbon dioxide are mixed in the secondary combustion zone (16) and the incomplete combustion components in the high-temperature gas are completely combusted to generate high-temperature flue gas; Inject tertiary carbon dioxide through the mixing hole (14), mix with the high-temperature flue gas from the secondary combustion zone (16) to reduce the temperature of the high-temperature flue gas, and enter the turbine (2) to do work; the temperature of the flue gas after passing through the turbine (2) to do work Reduced to waste gas, the main components of which are carbon dioxide and water vapor; Separate the exhaust gas to obtain dry flue gas and condensed water with carbon dioxide as the main component, and use part of the dry flue gas as recirculation gas, after mixing and adjusting, send it to the compressor (7) for compression and boosting, and send it to the combustion chamber as a working medium The working medium gas channel formed between the jacket and the flame cylinder (11). 6. gas turbine staged oxygen supply combustion method according to claim 5, is characterized in that, described gas turbine also comprises condenser (4), separating valve (5) and mixing valve (6) and with described mixing valve (6) ) connected carbon dioxide storage tanks, the method also includes: Let the exhaust gas enter the condenser (4) to recover waste heat, and enter the separation valve (5) for steam-water separation, and separate the gas with carbon dioxide as the main component from water to obtain dry flue gas; a part of the separated dry flue gas is used as recirculation gas , enters the mixing valve (6), and enters the compressor (7) to compress and raise the pressure after adjusting the flow rate through the carbon dioxide storage tank, and sends it as a working medium into the working medium gas channel formed between the combustor jacket and the flame tube (11). 7. The gas turbine staged oxygen supply combustion method according to claim 5 or 6, characterized in that, the carbon dioxide enters the staged supply through the main nozzle (12), the secondary carbon dioxide nozzle (132) and the mixing hole (14) respectively. The primary combustion zone (15), the secondary combustion zone (16) and the mixing zone (17) of the oxygen combustion chamber (1), the formation of primary carbon dioxide, secondary carbon dioxide and tertiary carbon dioxide injection ratio is (50-60) :(5～20):(20～45). 8. The gas turbine staged oxygen supply combustion method according to claim 5 or 6, characterized in that, the staged oxygen supply combustion method also includes a staged adjustment method, and the staged adjustment method includes: The load of the gas turbine is gradually increased, so that the fuel supplied to the main combustion zone (15) by the main nozzle (12) of the staged oxygen supply combustion chamber (1) is gradually increased; According to the stoichiometric ratio φ of fuel and oxygen, increase the total oxygen flow rate. When the total oxygen flow rate is less than or equal to the maximum oxygen content of the main combustion zone, the oxygen is adjusted to be sprayed through the main nozzle (12) of the staged oxygen supply combustion chamber (1). Enter the main combustion zone (15), so that the primary oxygen ratio is 100%; when the oxygen flow continues to increase and is greater than the maximum oxygen content of the main combustion zone, part of the oxygen exceeding the maximum oxygen content of the main combustion zone will pass through as secondary oxygen Secondary oxygen nozzles (132) inject into the secondary combustion zone (16). 9. The gas turbine staged oxygen supply combustion method according to claim 8, characterized in that, the staged adjustment method further comprises: The gas turbine load is gradually reduced, so that the fuel supplied to the main combustion zone (15) by the main nozzle (12) of the staged oxygen supply combustion chamber (1) is gradually reduced; According to the stoichiometric ratio φ of fuel and oxygen, the total oxygen flow rate is reduced. When the total oxygen flow rate is greater than the maximum oxygen intake in the main combustion zone, the total oxygen flow rate is reduced in sequence in the order of first reducing the secondary oxygen supply and then reducing the primary oxygen supply. Oxygen amount; when the total oxygen flow rate is less than or equal to the maximum oxygen content of the main combustion area, reduce the primary oxygen amount of the main combustion area.