JP2012180743A - Closed cycle gas turbine power generation plant for co2 recovery type gasification gas power generation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the combustibility and the combustion efficiency of a closed cycle gas turbine combustor.SOLUTION: The closed cycle gas turbine power generation plant for gasification gas includes: a gas turbine combustor which uses a gasification gas of heavy oil or coal as main fuel and which uses an oxidant mainly formed of oxygen for theoretical mixture ratio combustion; a gas turbine driven by the combustion gas; a generator connected to the gas turbine to output power; and a device which recycles a part of the exhaust gas discharged from the gas turbine as a gas turbine operating medium and collects a carbon dioxide when discharging the residual exhaust gas out of a system. A part of the recycled gas is supplied to a fuel supply system provided at a downstream side of a gasification furnace and at an upstream side of the combustor, and mixed with the gasification gas fuel before the gasification gas fuel is supplied to the gas turbine combustor. The temperature of the mixed gas is maintained at 400-900°C to decompose steam in the gas turbine combustion exhaust gas into hydrogen so as to raise the concentration of a hydrogen component in the gasification gas fuel, and thereafter, the gasification gas fuel is supplied to the gas turbine combustor.

Description

The present invention relates to a combustion acceleration technique in a gas turbine power plant for gasification gas in which a raw material such as heavy oil or coal is gasified and the generated gasification gas is combusted. More specifically, the present invention recycles a part of the gas turbine combustion exhaust gas after being discharged from the gas turbine as a diluent and collects CO ₂ while collecting carbon dioxide (CO ₂ ) from a part thereof. TECHNICAL FIELD The present invention relates to combustion promotion technology in a closed-cycle gas turbine power plant for type gasification gas power generation.

In recent years, development of coal gasification combined power generation (IGCC) technology has been promoted for the purpose of diversification of energy resources and high-efficiency power generation. On the other hand, in order to cope with global environmental problems, a power generation system combined with a CO ₂ recovery mechanism is also required.

Accordingly, in order to meet these demands, the present applicants of the present patent have previously proposed a CO ₂ recovery type IGCC system shown in FIG. 19 in which a closed cycle gas turbine and a CO ₂ recovery mechanism are combined with IGCC (Non-patent Document 1). ). In this system, CO ₂ -added O ₂ blown coal gasification gas fuel containing CO and H ₂ as main components is stoichiometrically burned in O ₂ , and the generated high-temperature combustion gas is converted into CO ₂ and H ₂ O. The gas turbine combustion exhaust gas as a main component is diluted with a gas turbine combustion exhaust gas and adjusted to a predetermined temperature to constitute a closed cycle gas turbine by exhaust gas circulation / O ₂ stoichiometric combustion. Here, a part of the gas turbine combustion exhaust gas recovers CO ₂ and is discharged out of the system, and the rest is recycled and supplied to the combustor as a diluent, and the combustion temperature rising to about 3000 ° C. is set to a predetermined temperature ( For example, in the case of a 1300 ° C. class gas turbine, the temperature is adjusted to 1350 ° C. at the first stage moving blade inlet of the expansion turbine. That is, in a closed cycle gas turbine that circulates gas turbine combustion exhaust gas, by realizing gas turbine combustion using combustion exhaust gas mainly composed of CO ₂ and H ₂ O as a working medium, a plant accompanying CO ₂ recovery is achieved. IGCC power generation that suppresses the decrease in thermal efficiency is realized.

Central Research Institute of Electric Power Industry Report M07003 (2007)

However, the closed cycle gas turbine for CO ₂ recovery type IGCC described in Non-Patent Document 1 is different from a normal LNG-fired gas turbine in which oxygen is excessively burned with a large amount of air, and thus is a stoichiometric combustion by O ₂ . The oxidation reaction is delayed, and there is a problem that it is difficult to complete combustion with a combustion gas residence time in a normal gas turbine.

In addition, the O ₂ stoichiometric combustion apparently exhibits a two-stage reaction phenomenon, and CO or H ₂ is regenerated by reduction of the CO ₂ and H ₂ O components in the diluent after the primary reaction (so-called, It causes reversibility of the reaction) and suppresses the oxidation reaction of the fuel.

Further, since the partial pressures of the CO ₂ and H ₂ O components are high and the oxidation reaction of CO and H ₂ in the gasified gas fuel is suppressed, the time until the reaction converges becomes long.

From this, the combustion reaction is suppressed as the CO component concentration in the fuel increases, and the O ₂ and CO component concentrations remaining in the combustion gas increase when compared with the same reaction time. That is, in the case of gasified gas fuel, there is a problem that combustibility is lowered mainly as the CO component concentration in the fuel is increased and combustion efficiency is lowered.

Further, in the closed cycle gas turbine combustion in which the combustion gas increases the CO ₂ concentration in the gas turbine combustion exhaust gas and dilutes the combustion gas with the gas turbine combustion exhaust gas mainly composed of CO ₂ and H ₂ O, CO and The oxidation reaction of the gasified gas fuel containing H ₂ as a main component is further suppressed, and the combustibility is lowered.

However, in order to advance the oxidation reaction, for example, when combustion is performed under a slight oxygen excess condition, although the combustion efficiency increases, surplus O ₂ remains in the combustion gas, and gasification raw material such as coal to the gasification furnace The use of the recycle gas turbine combustion exhaust gas as the carrier gas is restricted. In addition, there is a concern that when the fuel is burned under a fuel excess condition slightly higher than the stoichiometric ratio, the combustion efficiency rapidly decreases.

Furthermore, the gasification gas fuel is diluted with gas turbine combustion exhaust gas mainly composed of CO ₂ and H ₂ O burned stoichiometrically with O ₂ and adjusted to lower the temperature at the combustor outlet gas during rated operation. Therefore, the oxidation reaction of the gasified gas fuel mainly composed of CO and H ₂ is further suppressed, and a relatively short reaction time (for example, several times) like a gas turbine combustor that burns LNG. In the reaction time of 10 ms), O ₂ as an oxidant and CO as an unburned component remain in the gas turbine combustion exhaust gas at a high concentration, so that sufficient combustion efficiency cannot be obtained. There is a concern that the generation of soot due to the unburned component CO affects each device of the power plant.

From this, the stoichiometric combustion gas turbine combustor with O ₂ of gasified gas fuel mainly composed of CO and H ₂ suppresses the inhibition of the combustion reaction due to the circulation of the combustion exhaust gas, and is relatively short It is desired to develop a stable combustion technique in which the discharge amount of unburned components and residual O ₂ components is reduced in a reaction time of, for example, 100 ms or less, preferably several tens of ms. Furthermore, it is desired to develop a combustion technique that ensures combustibility and combustion stability in a closed cycle gas turbine combustor and maintains sufficient combustion efficiency.

The present invention responds to such a demand, and in a closed cycle gas turbine power plant that employs O ₂ stoichiometric combustion of gasified gas fuel under exhaust circulation, the combustion reaction in the gas turbine is promoted to achieve stable combustion. For the purpose. Specifically, the present invention relates to an unburned CO component or unburned CO generated in a combustion process of a closed cycle gas turbine combustor in a closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation. It aims at suppressing the soot produced | generated and improving the combustibility or combustion efficiency of a gas turbine combustor.

As a result of various studies and numerical analysis by the present inventors in order to achieve such an object, in the closed cycle gas turbine for CO ₂ recovery type IGCC, a small amount of O ₂ (for example, about 0.3 vol%) is contained in the recycled exhaust gas. although present, if 400 ° C. or higher 900 ° C. or less, towards reaction rate is H ₂ is generated by of H _{2 O} in the recycled exhaust gas than the oxidation is reduced is high, actively generate and H ₂ I came to know that.

The present invention is based on such knowledge, and the invention according to claim 1 is a facility for gasifying a raw material such as heavy oil or coal with an oxidizing agent, and a gasification gas generated by the gasification facility. And a gas turbine combustor that uses the gasified gas as a main fuel and burns in a stoichiometric ratio with an oxidant mainly composed of oxygen, a gas turbine driven by the combustion gas, A generator coupled to a gas turbine for outputting electric power, and CO ₂ when exhausting the remaining exhaust gas out of the system while recycling a part of the exhaust gas discharged from the gas turbine as a gas turbine working medium. in the closed-cycle gas turbine power plant for the gasification gas containing CO ₂ recovery device for recovering said at least a portion of the gas turbine combustion exhaust gas to be recycled To the fuel supply system downstream from the gasification furnace and upstream from the combustor, and mixed with the gasified gas fuel before being supplied to the gas turbine combustor, and at least 400 ° C. to 900 ° C. In the meantime, the temperature is maintained and water vapor in the gas turbine combustion exhaust gas is decomposed into hydrogen, and the hydrogen component concentration in the gasified gas fuel is increased before being supplied to the gas turbine combustor.

  Here, among the gas turbine combustion exhaust gas recycled to the gas turbine combustor, the amount supplied to the fuel supply system upstream of the gas turbine combustor increases the hydrogen component in the gasified gas fuel to increase the hydrogen component. In order to increase the concentration, a part of the concentration may be used, but preferably the entire amount is supplied.

  Further, the CO emission concentration or soot amount in the combustion gas discharged from the gas turbine combustor is monitored, and the CO emission concentration is adjusted by adjusting the supply position of the gas turbine combustion exhaust gas to the fuel supply system. It is preferable to control to a certain amount or less to suppress generation of soot.

  Further, by monitoring the CO component concentration or soot amount in the combustion gas discharged from the gas turbine combustor and adjusting the supply amount of the gas turbine combustion exhaust gas, the CO emission concentration is controlled to a certain amount or less. However, it is preferable to suppress the generation of soot.

  In addition, the gasified gas fuel supplied to the head of the gas turbine combustor, the gas turbine combustion exhaust gas or a mixed gas thereof is mixed in advance, or the head of the gas turbine combustor alone is steam or nitrogen. It is preferable to supply either one or both of them.

  Furthermore, by monitoring the CO component concentration or soot amount in the combustion gas discharged from the gas turbine combustor, and adjusting the supply amount of the gas mixed with either or both of water vapor and nitrogen, the CO emission It is preferable to control the concentration below a certain amount to suppress the generation of soot.

  Further, when the gas turbine combustion exhaust gas is mixed with the gasification gas fuel to generate hydrogen in the mixture before supplying the gasification gas fuel to the gas turbine combustor, the reaction temperature is appropriately controlled to at least It is important to maintain the temperature between 400 ° C and 900 ° C, preferably 600 ° C to 800 ° C. Therefore, in the present invention, as a heat source for properly controlling the reaction temperature for generating hydrogen in the mixed gas of the gas turbine combustion exhaust gas and the gasified gas fuel, the heat of the gasification furnace or the exhaust heat recovery boiler or heat The heat of the gas turbine combustion exhaust gas recovered by the exchanger is used.

  Furthermore, it is preferable to supply a part of the gas turbine combustion exhaust gas to be recycled to the gas turbine combustor between the head of the gas turbine combustor and the inlet of the first stage blade of the gas turbine.

According to the closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to the first aspect of the present invention, at least a part of the gas turbine combustion exhaust gas to be recycled is located downstream from the gasification furnace and gas turbine combustion. Is supplied to the fuel supply system upstream of the gas generator, mixed with the gasified gas fuel before being supplied to the gas turbine combustor, and maintained at a temperature of at least 400 ° C. to 900 ° C. in the gas turbine combustion exhaust gas. The steam is decomposed into hydrogen and the hydrogen component concentration in the gasified gas fuel is increased before being supplied to the gas turbine combustor, which increases the combustion speed and greatly contributes to combustion stability. . Normally, according to the closed cycle gas turbine for CO ₂ recovery type gasification gas power generation, since the stoichiometric combustion is performed, the oxidation reaction of the fuel is lowered and the stability of the combustion reaction is deteriorated. However, according to the present invention, since the hydrogen component concentration in the gasified gas fuel before being supplied to the gas turbine combustor is increased, the combustibility of the gasified gas fuel is improved, Since the oxidation reaction rate is increased and the oxidation reaction of the fuel is completed quickly, the stability of the combustion reaction is increased and the combustion efficiency can be further increased. This suppresses soot generated due to unburned CO components or unburned CO, compared with the conventional closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation, and the combustibility of the gas turbine combustor. Or combustion efficiency can be improved.

In addition, before supplying gasified gas fuel to a gas turbine combustor having a complicated flow and reaction process, it is possible to increase the hydrogen concentration of the fuel to improve combustibility, and Since it is possible to appropriately control the composition of the diluent or the ratio with water vapor, it becomes easier to more efficiently improve the combustibility of the closed cycle gas turbine for CO ₂ recovery type IGCC.

  According to the second aspect of the present invention, the total amount of gas turbine combustion exhaust gas recycled to the gas turbine combustor is mixed with the gasified gas fuel before being supplied to the gas turbine combustor. The hydrogen content concentration of the gas is increased most, and the combustibility of the gasified gas fuel can be improved. And, by supplying gasified gas fuel with good combustibility, the combustion speed in the primary combustion zone is increased and the combustibility is surely improved, and soot generated due to unburned CO components or unburned CO is suppressed. At the same time, the combustion efficiency can be improved.

According to the third aspect of the present invention, the CO emission concentration or the soot amount in the combustion gas discharged from the gas turbine combustor is monitored to be downstream from the gasification furnace and upstream from the gas turbine combustor. Since the supply position of the gas turbine combustion exhaust gas mixed with the gasification gas fuel is adjusted on the side, the amount of H ₂ generated in the gasification gas fuel is made appropriate, and the CO emission concentration is kept below a certain amount Control and suppress the generation of soot.

  According to the invention of claim 4, the CO emission is monitored by adjusting the supply amount of the gas turbine combustion exhaust gas by monitoring the CO component concentration or soot amount in the combustion gas discharged from the gas turbine combustor. The concentration is controlled to a certain level or less to suppress soot generation, so that the combustion efficiency and combustion stability of the gas turbine are ensured and the combustion efficiency is improved over the entire operating range of the gasification power plant. be able to.

According to the invention described in claim 5, the gas turbine combustor is previously mixed with the gasified gas fuel, the gas turbine combustion exhaust gas or the mixed gas supplied to the head of the gas turbine combustor, or the gas turbine combustor. Since only one or both of water vapor and nitrogen are mixed and supplied to the head, even if it is a gasified gas fuel that is difficult to burn completely by stoichiometric combustion with O ₂ , the H ₂ component in the fuel Since the concentration can be further increased before the combustion reaction or during the combustion reaction process, the combustibility of the gasified gas fuel can be further improved and the combustion reaction can be further promoted. Thereby, combustibility can be raised, unburned CO component can be decreased, and combustion efficiency can be improved. In addition, since the concentration of the CO ₂ component in the diluent is relatively lowered, there is an effect of promoting the oxidation of the CO component in the fuel. Here, the effect of increasing the H ₂ component concentration by supplying steam, nitrogen or a mixed gas thereof is the gas turbine combustion exhaust gas that is directly supplied to the head of the gas turbine combustor so as to be supplied upstream of the combustor. Is the same, but gasification gas fuel is added to the gas turbine combustor before the gas turbine combustor is mixed with either or both of water vapor and nitrogen to increase the H ₂ component concentration. It is preferable because control of gas fuel can be ensured. The mixing of either or both of water vapor and nitrogen into the gasified gas fuel can maintain the combustibility by increasing the H ₂ component concentration even when the recirculation amount of the gas turbine combustion exhaust gas decreases.

  According to the invention of claim 6, the CO component concentration or the soot amount in the combustion gas discharged from the gas turbine combustor is monitored, and either or both of water vapor and nitrogen supplied to the gas turbine combustion exhaust gas By adjusting the supply amount of CO, the CO emission concentration can be controlled below a certain amount, so that the combustion efficiency can be increased and the generation of soot due to CO can be suppressed.

  According to the seventh aspect of the present invention, as a heat source for appropriately controlling the reaction temperature for generating hydrogen in the mixed gas of the gas turbine combustion exhaust gas and the gasified gas fuel, the heat or exhaust heat recovery of the gasifier is performed. Since the heat of the gas turbine combustion exhaust gas recovered by the boiler or heat exchanger is used, not only is there no need to obtain an external heat source, but the exhaust heat can be used effectively, minimizing reduction in plant thermal efficiency. It becomes possible to.

  According to the invention described in claim 8, since a part of the gas turbine combustion exhaust gas to be recycled is supplied downstream from the intermediate position of the gas turbine combustor, the combustion adjusted to the rated temperature at the first stage blade inlet of the gas turbine. While supplying gas, the combustion temperature in the primary combustion region at the head of the gas turbine combustor where the combustion is most active can be controlled to a temperature higher than the rated temperature, for example, a temperature range of 1500 to 1900 ° C. Combined with the effect of increasing the combustion stability by increasing the hydrogen component concentration in the gasified gas fuel before being supplied to the combustor by mixing the gas turbine combustion exhaust gas and increasing the combustion speed, When the oxidation reaction rate of the fuel is high, the reversibility of the oxidation reaction of the fuel can be reduced to promote the oxidation reaction / combustion reaction. Baked properties can be maintained.

1 is a schematic layout diagram showing a first embodiment of a CO ₂ recovery gasification power plant according to the present invention. It is a graph which shows the analysis result regarding the influence of the composition of a diluent on the time-dependent change of the hydrogen component in a fuel at the time of supplying gasification gas fuel, an oxidizing agent, and a diluent to a gas turbine combustor. It is a graph which shows the analysis result regarding the influence of the composition of a diluent on the combustion exhaust gas characteristic and combustion efficiency in a gas turbine combustor exit part. Is a graph showing the analysis results on the effect of diluent in H _{2 O} component concentration on Combustion exhaust gas characteristics and fuel efficiency in a gas turbine combustor outlet. It is a graph which shows the analysis result (when the ratio of dilution amount / fuel = 2) about the influence of the reaction temperature on the amount of hydrogen produced in the gas mixture of gasification gas fuel and exhaust gas. It is a graph which shows the analysis result (when the ratio of dilution amount / fuel = 4) regarding the influence of the reaction temperature on the amount of hydrogen generated in the gas mixture of gasified gas fuel and exhaust gas. It is a graph which shows the analysis result (when the ratio of dilution amount / fuel = 3) regarding the influence of the reaction temperature on the amount of hydrogen generated in the gas mixture of gasified gas fuel and exhaust gas. It is a graph which shows the analysis result (in the case of the ratio of dilution amount / fuel = 5) regarding the influence of the reaction temperature on the amount of hydrogen produced in the gas mixture of gasified gas fuel and exhaust gas. Analysis results on the influence of the diluent amount and reaction temperature on the hydrogen amount when the diluent is supplied to the gasification gas fuel upstream from the gas turbine combustor (dilution amount / fuel ratio = 2-5) ). It is a graph which shows the analysis result regarding the influence of the molar ratio of a diluent / fuel on the combustion exhaust gas characteristic and combustion efficiency in a gas turbine combustor exit part. It is a graph which shows the result of having analyzed the relationship between the dilution rate for every combustion reaction time, and combustion efficiency. The second embodiment of the CO ₂ recovery gasification plant according to the present invention is a schematic arrangement diagram showing. It is a schematic arrangement diagram showing a third embodiment of a CO ₂ recovery gasification plant according to the present invention. It is a schematic layout diagram showing a fourth embodiment of a CO ₂ recovery gasification plant according to the present invention. It is a schematic layout diagram showing a fifth embodiment of a CO ₂ recovery gasification plant according to the present invention. A sixth embodiment of the CO ₂ recovery gasification plant according to the present invention is a schematic arrangement diagram showing. It is a graph which shows the result of having analyzed the relationship between the combustion time of a primary combustion area | region, the composition of combustion gas, and combustion efficiency. It is a graph which shows the analysis result regarding the influence of the molar ratio of the diluent / fuel supplied to a primary combustion area | region on the time-dependent change of the combustible component in combustion gas. It is a schematic arrangement diagram showing a conventional CO ₂ recovering IGCC system.

  Hereinafter, the configuration of the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of a closed cycle gas turbine power plant for CO ₂ recovery gasification gas power generation according to the present invention. This power plant includes a facility for gasifying a raw material such as heavy oil or coal with an oxidizing agent, a gasification furnace 2, and a gas purification facility 3 for purifying the gasification gas CG1 generated in the gasification furnace 2, A gas turbine combustor 5 that burns in a stoichiometric ratio with an oxidant (hereinafter also simply referred to as O ₂ ) that uses gasified gas as the main fuel and oxygen as a main component, a gas turbine 6 that is driven by the combustion gas, and a gas a generator 9 which is coupled to a turbine 6 to output the power, CO ₂ when discharging the remaining exhaust gases out of the system while recycling a portion of the exhaust gas discharged from the gas turbine 6 as the gas turbine working medium CO ₂ recovery device 12 for recovering CO ₂ -added O ₂ blown coal gasification gas fuel is stoichiometrically combusted in O ₂ , and part of the gas turbine combustion exhaust gas recovers CO ₂ outside the system Exhaust to the rest A closed loop is formed which is recycled and supplied to the combustor 5 to adjust the combustion temperature and introduce the combustion gas into the turbine 6. That is, in the closed cycle gas turbine for CO ₂ recovery type IGCC of the present invention, by realizing gas turbine combustion using combustion exhaust gas mainly composed of CO ₂ and H ₂ O as a working medium, it is accompanied by CO ₂ recovery. IGCC power generation that suppresses the decrease in plant thermal efficiency is realized. In the figure, reference numeral 1 denotes an oxygen production apparatus for generating oxygen AO2 required by the gasification furnace 2 and the gas turbine combustor 5 from air, and 4 denotes gasification gas fuel from the gasification furnace 2 to the gas turbine combustor 5. Fuel supply system for supply, 7 is an exhaust heat recovery boiler, 8 is a compressor for boosting a gas turbine combustion exhaust gas to be recycled (also simply referred to as recycled exhaust gas), 9 is a generator, 10 is a steam turbine, 11 is Condenser, 13 chimney, 14 gas turbine axle, C is gasification raw material such as coal, CG1 is gas after gasification, CG2 is gasification gas fuel after gas purification, CD is gas turbine combustion exhaust gas Recovered CO ₂ , FG is gas turbine combustor exhaust gas, FW is condensate / feed water, G is gas after turbine exhaust, HG is recycled exhaust gas after compression, HG1 is gas turbine combustor via fuel supply system 4 5 recycling waste Exhaust gas supply line for supplying, HG3 is water vapor exhaust gas supply line of the gasification raw material transport for recycling exhaust gases to the gasifier, ST is the working medium of the steam turbine plant.

  In the gasification furnace 2, the gas A gas is supplied to the gas turbine combustor 5 by deoxidizing and desulfurizing the coal C by oxygen oxidation of the coal C by supplying oxygen AO 2, and degassing and desulfurization by the gas purification device 3. Generate CG2. When the load of the gasification furnace 2 rises and a gasification gas CG2 having a certain quality is produced, it is supplied to the gas turbine combustor 5. In the gas turbine 6, the operation is started by switching the gasified gas fuel CG2 to the starting fuel, and the plant load is increased, and the operation is mainly performed under rated conditions.

Further, the hot exhaust gas G from the gas turbine 6 transfers heat to the feed water FW by the exhaust heat recovery boiler 7, guides the generated steam ST to the steam turbine 10, drives it, and generates electricity by the generator 9. To do. Most of the exhaust gas G that has passed through the exhaust heat recovery boiler 7 is compressed by the compressor 8, and a part of the high-pressure exhaust gas HG is supplied to the gasifier 2 as gasification raw material transport gas via the exhaust gas supply line HG3. Most of the gas is supplied as primary recycled exhaust gas through the exhaust gas supply line HG1. As shown in FIG. 1, the entire amount of the recycled exhaust gas is mixed with the gasified gas fuel of the fuel supply system 4 upstream of the gas turbine combustor 5 and then supplied to the head of the gas turbine combustor 5. In some cases, as shown in FIG. 12, a part of the recycle exhaust gas is mixed with the gasified gas fuel in the fuel supply system 4 upstream of the gas turbine combustor 5 and the remaining recycle exhaust gas is mixed if necessary. the amount is supplied as a secondary recycling exhaust gas until the inlet of the first stage moving blade of the gas turbine downstream than the head of the gas turbine combustor through the following gas supply line HG2 by by O ₂ in the gasification gas fuel The stoichiometric combustion gas may be diluted and adjusted to a predetermined temperature. Further, if necessary, a part of the recycle exhaust gas recycled to the gas turbine combustor 5 is supplied to the fuel supply system 4 upstream of the gas turbine combustor and mixed with the gasified gas fuel. While supplying to the head, a part of the recycled exhaust gas may be directly supplied to the gas turbine combustor 5. A part of the combustion exhaust gas is exhausted from the chimney 13 after CO ₂ is recovered by the CO ₂ recovery facility 12. Exhaust gas G that has passed through the exhaust heat recovery boiler 7 is introduced into the compressor 8 and recycled by adjusting the opening of an exhaust gas damper (not shown), and the compressor side And part of the gas turbine combustion exhaust gas that is introduced to the CO ₂ recovery side and exhausted outside the system. In addition, the recycled exhaust gas HG compressed through the compressor 8 is supplied to the fuel supply system 4 upstream of the gas turbine combustor 5 by adjusting the opening of a flow control valve (not shown). The gas is divided and supplied to a supply line HG1 and an exhaust gas supply line HG3 for conveying the gasification raw material to the gasification furnace. Of course, as shown in FIG. 12 or FIG. 13, as a diluent, the secondary exhaust gas supply line HG2 is used as a diluent between the head of the gas turbine combustor and the inlet of the first stage blade of the gas turbine. When supplying secondary recycle exhaust gas, and also when supplying recycle exhaust gas directly to the gas turbine combustor 5 via the exhaust gas supply line HG1 'as necessary, the distribution ratio is appropriately adjusted by adjusting the opening of the flow control valve. Will be distributed. By the way, the flow control valve generally measures the flow rate by the differential pressure.In addition, the flow control valve, the flow measurement unit, the drive air source for control (air compressor such as a reciprocating type), etc. It is configured.

  Examples of the gasification raw material C include, but are not limited to, coal, petroleum, biomass, waste, and the like. Examples of the gasifying agent AO2 include, but are not limited to, oxygen, air, oxygen-enriched air, and the like.

Here, the stoichiometric combustion gas turbine combustor 5 with O ₂ of gasified gas fuel mainly composed of CO and H ₂ suppresses the inhibition of the combustion reaction due to the circulation of the gas turbine combustion exhaust gas, and is several tens of ms. Stable combustion with reduced emissions of unburned components and remaining O ₂ components is required in a reaction time of ˜100 ms. Further, in a closed cycle gas turbine, it is not always necessary to maintain high combustion efficiency (η> 99.5%), unlike a normal LNG-fired cycle gas turbine. In the CO ₂ recovery type IGCC power generation system, it is important that each component allows the composition of the gas turbine combustion exhaust gas and performs stable operation by adjusting the fuel, oxidant, and diluent. However, if the combustion efficiency is reduced, soot may be generated due to the CO component in the combustion gas, which may hinder the operation of the closed cycle gas turbine. Therefore, in the gas turbine combustor 5, it is most important to maintain stable combustion while suppressing generation of soot and the like.

Therefore, the closed cycle gas turbine power plant for CO ₂ recovery IGCC according to the present invention is at least a part of gas turbine combustion exhaust gas (referred to as recycle exhaust gas or diluent in this specification) to be recycled by the gas turbine combustor 5. Is supplied to the fuel supply system 4 downstream of the gasification furnace 2 and upstream of the gas turbine combustor 5 and mixed with the gasified gas fuel before being supplied to the gas turbine combustor 5, and at least 400 ° C. The temperature is maintained between ˜900 ° C., the water vapor in the gas turbine combustion exhaust gas is decomposed into hydrogen, and the hydrogen component concentration in the gasified gas fuel is increased before being supplied to the gas turbine combustor 5. Yes. Further, in the present embodiment, the recycled exhaust gas is divided and part thereof is in the head of the gas turbine combustor 5, that is, the primary fuel region, and the remaining part is downstream of the head of the gas turbine combustor and the first stage moving blade of the gas turbine. Between the inlet and the combustor outlet. In some cases, the amount of the recycle exhaust gas supplied to the head of the gas turbine combustor is controlled so that the combustion temperature at the head of the gas turbine combustor is in the range of 1500 to 1900 ° C.

  Here, among the gas turbine combustion exhaust gas recycled to the gas turbine combustor 5, the amount supplied to the fuel supply system 4 on the upstream side of the gas turbine combustor 5 is not particularly limited. In order to increase the hydrogen component concentration in the gasified gas fuel and increase the concentration of the hydrogen component to increase the combustion reaction rate and improve the combustibility, it is preferable to supply the entire amount, though it may be a part. In addition to the gas turbine combustion exhaust gas recycled to the combustor, the gas turbine combustion exhaust gas exhausted outside the system is used as an exhaust gas for conveying gasification raw materials such as coal to the gasification furnace. About 10% is used. The recycled exhaust gas for conveying the gasification raw material becomes a part of the gasifying agent.

  The total amount of recycled exhaust gas HG is determined by the rated operating conditions (such as the combustion gas combustor outlet temperature) and the calorific value of the gasified gas fuel used. For example, when a gasified gas fuel having the composition shown in Table 1 is used, the combustion temperature becomes 3087 ° C., and therefore when the combustion gas combustor outlet temperature (rated combustion temperature) is set to 1350 ° C., 1 mol of fuel is used. 5 mol of gas turbine combustion exhaust gas is circulated and supplied to the combustor. When the rated combustion temperature is 1300 ° C., 5.4 mol of gas turbine combustion exhaust gas is circulated and supplied to the combustor with respect to 1 mol of fuel.

  Recycle exhaust gas is preferably supplied to the fuel supply system 4 upstream of the gas turbine combustor 5 in terms of increasing combustibility by increasing the hydrogen component concentration in the gasified gas fuel. In order to achieve both the improvement of combustion stability and combustion efficiency by controlling the combustion temperature in the gas turbine combustor 5, the recycled exhaust gas supplied to the gas turbine combustor 5 is combusted at the head of the combustor. Divided into the amount required to adjust the combustion temperature to 1500-1900 ° C where the reaction is active and the amount required to lower the combustor outlet temperature of the combustion gas to the rated temperature. Supply. That is, the recycle exhaust gas is mixed with the gasified gas fuel of the fuel supply system 4 or directly supplied to the primary combustion region of the head of the gas turbine combustor 5 and the subsequent secondary combustion. Divided into secondary recycle exhaust gas supplied to the region, and possibly tertiary recycle exhaust gas for diluting the combustion gas. At this time, it is preferable that the secondary recycle exhaust gas is supplied downstream from the intermediate position of the gas turbine combustor. The tertiary recycle exhaust gas may be supplied to the first stage stationary blade inlet of the expansion turbine and mixed sufficiently. That is, the tertiary exhaust gas can be used for cooling the blades of the expansion turbine.

That is, it is preferable that at least a part of the recycled exhaust gas is mixed with gasified gas fuel upstream of the gas turbine combustor 5 and maintained in a certain temperature range. For example, as shown in FIG. 1 and FIGS. 12 to 16, a part of the recycled exhaust gas is converted into gasified gas fuel upstream of the gas turbine combustor 5 through an exhaust gas supply line HG 1 connected to the fuel supply system 4. After mixing in advance, the gas turbine combustor 5 may be supplied to the head. In particular, as in the embodiment of FIGS. 1 and 16, the gasified gas fuel before being supplied to the gas turbine combustor 5 on the downstream side of the gasification furnace 2 and on the upstream side of the gas turbine combustor 5. The gas mixture of the exhaust gas and the recycle exhaust gas is maintained at a temperature of at least 400 ° C. to 900 ° C., preferably 600 to 800 ° C. to decompose the water vapor in the recycle exhaust gas into hydrogen, and the hydrogen component in the gasification gas fuel It is preferable to supply the gas turbine combustor 5 after increasing the concentration. In this case, since the hydrogen concentration in the gasified gas fuel is increased, the combustion reaction rate is increased and the combustibility is improved. In the fuel supply system 4 on the upstream side of the gas turbine combustor 5, the increase in the hydrogen concentration in the gasified gas fuel caused by mixing the recycle exhaust gas into the gasified gas fuel occurs in a reduced state in which there is almost no oxygen. This is a reaction phenomenon. It is important that this reaction is maintained at a temperature range of at least 400 ° C. to 900 ° C., preferably a more appropriate reaction temperature, for example, 600 to 800 ° C. for a certain period of time. Even if a small amount of O ₂ (for example, about 0.3 vol%) is present, the reaction rate at which H ₂ is generated is higher than that of oxidation, and H ₂ is generated. Therefore, in the present embodiment, as a heat source for appropriately controlling the reaction temperature for generating hydrogen in the mixed gas of the recycle exhaust gas and the gasification gas, the heat of the gasification furnace or the exhaust heat recovery boiler or FIG. 16 is shown. The heat of the recycled exhaust gas recovered by such a heat exchanger 16 is used. Means for adjusting the distribution ratio between when supplying to the fuel supply system 4 upstream of the gas turbine combustor 5 via the exhaust gas supply line HG1 and when supplying directly to the gas turbine combustor 5 via the exhaust gas supply line HG1 ' For example, the flow rate of exhaust gas to be circulated is measured with a differential pressure type flow meter, etc., and a flow rate adjustment valve is provided to adjust the flow rate, and an automatic adjustment device is provided to automatically adjust the flow rate. Based on the measured value, the flow rate adjustment valve is driven by the compressed air supplied from the driving air source and adjusted. In the figure, reference numeral HG1 ′ denotes an exhaust gas supply line that directly supplies the recycled exhaust gas to the gas turbine combustor 5 as required, and HG2 denotes the first stage operation of the gas turbine downstream from the head of the gas turbine combustor 5. This is an exhaust gas supply line that supplies recycled exhaust gas as needed up to the blade inlet.

  The recycle exhaust gas supplied to the head of the gas turbine combustor 5 may be a constant supply amount determined by the calorific value of the gasified gas fuel that varies depending on the fuel composition, gasification system, etc., but more preferably gas By monitoring the CO component concentration or soot amount in the combustion gas discharged from the turbine combustor 5 and adjusting the supply amount of the recycle exhaust gas, or to the gasified gas fuel before being supplied to the gas turbine combustor 5 By adjusting the distribution ratio between the amount of the recycled exhaust gas to be supplied and the amount of the recycled exhaust gas directly supplied to the head of the gas turbine combustor 5, or downstream of the gasification furnace 2 and the gas turbine combustor 5. By adjusting the supply position of the recycle exhaust gas mixed with the gasified gas fuel on the upstream side, the CO emission concentration is reduced below a certain level. Controls on, may be suppress the formation of soot. Further, it is preferable to monitor the fuel calorific value of the gasification gas fuel and adjust the amount of the recycle exhaust gas so that the temperature of the combustion gas at the combustor outlet becomes the rated temperature when the calorific value changes. . In the present invention, the purpose is to ensure the combustion stability in the gas turbine combustor 5 or to improve the combustibility. Therefore, it is not the CO monitoring at the smoke outlet, but the unburned component in the gas turbine combustor outlet gas. Monitors CO and soot.

In addition, the gasified gas fuel supplied to the head of the gas turbine combustor, the gas turbine combustion exhaust gas or a mixed gas thereof is mixed in advance, or the head of the gas turbine combustor alone is steam or nitrogen. It is preferable to supply a gas obtained by mixing one or both of the above. Even in this case, the combustion reaction can be promoted by generating a hydrogen component in the combustion gas during the combustion reaction process in the gas turbine combustor. In addition, since the concentration of the CO ₂ component in the diluent is relatively lowered, there is an effect of promoting the oxidation of the CO component in the fuel. Here, by monitoring the CO component concentration or the amount of soot in the combustion gas discharged from the gas turbine combustor, and adjusting the supply amount of either or both of water vapor and nitrogen supplied to the recycle exhaust gas, The CO emission concentration may be automatically controlled below a certain amount. In addition, even if water vapor or N ₂ is mixed in the secondary recycle exhaust gas or the tertiary recycle exhaust gas, there is no particular problem, but the combustion promoting effect is very small and the expected effect cannot be increased.

(Hydrogen generation in the combustion process)
The effects of various gas turbine state quantities on the basic combustion reaction characteristics of gasified gas fuel / O ₂ stoichiometric combustion by exhaust gas circulation will be clarified by numerical analysis of reaction kinetics considering the reaction process. First, the hydrogen generation situation in the combustion process of the gas turbine combustor will be described by showing the reaction kinetic numerical analysis result considering the reaction process.

Figure 2 examines the hydrogen generation and decomposition processes in the combustion process when gasified gas fuel, oxidant, and diluent (recycled exhaust gas) are all supplied from the head of the combustor by numerical analysis based on reaction kinetics. It is a result. For the numerical analysis, the elementary reaction scheme proposed by Millar and Bowman was used (literature name: Miller, JA, and Bowman, CT, 1989, “Mechanism and modeling of nitrogen chemistry in combustion,” Prog. Energy Combust. Sci. , Vol.15, pp.287-338.). The elementary reaction scheme of this document consists of 248 elementary reactions, and the chemical species considered are 51 components. Although various elementary reaction schemes have been proposed, the inventors of the present application have confirmed that in the reaction analysis of NH ₃ and NO in the gasification gas, the results agree with the experimental results under certain conditions ( Literature name: Hasegawa, T. et al., “Study of Ammonia Removal from Coal Gasified Fuel,” Combustion and Flame, Vol. 114, pp.246-258, 1998.).

  For thermodynamic data, JANAF thermodynamic property values were used, and unknown physical property values were derived from the relationship between Gibbs standard formation energy and chemical equilibrium constants. That is, 51 differential equations for obtaining the concentration of each chemical species with respect to the reaction time can be created from a chemical reaction system including 51 chemical species. The concentration of each chemical species after an arbitrary reaction time was determined by solving the equation 51 nonlinear differential equation system using the Gear method. Also, in the reaction process, all chemical species are assumed to be uniformly mixed, diffusion and mixing processes are not considered, and the reaction proceeds at a constant temperature. The numerical solution method is not limited to the Gear method, and other numerical solution methods such as the Runge-Kutta method may be used.

The numerical analysis is based on the temperature conditions shown in Table 1 (combustion reaction temperature 3087 ° C. under stoichiometric conditions calculated from gasified gas fuel and oxidizer, gas temperature 1350 ° C. at the outlet of the combustor including diluent), pressure conditions (3 MPa), and the combustion process in the gas turbine combustor of the gas mixed with the total amount of gasified gas fuel, oxidant and diluent (recycled exhaust gas) is calculated. FIG. 2 describes the difference in the composition of the diluent with respect to the hydrogen component of the 51 chemical species components constituting the elementary reaction. Under the standard conditions shown in Table 1 (described as “3 types” in FIG. 2), the H ₂ O concentration in the diluent is about 27%, and in FIG. 2, the majority of the diluent is H ₂ O or N _2. Are comparing.

As shown in FIG. 2, in the case of a gas (“3 types” in FIG. 2) in which the gasified gas fuel having the composition shown in Table 1 is mixed with the total amount of the oxidizer and diluent, the hydrogen oxidation reaction takes place in the reaction time Starting from 10 ⁻⁵ seconds, the hydrogen component does not change significantly until the reaction time 10 ⁻⁵ seconds to 10 ⁻³ seconds. After that, after the reaction time 10 ⁻³ seconds, the oxidation of hydrogen to H ₂ O It can be seen that the reaction proceeds and shows a two-stage reaction phenomenon that converges to an equilibrium concentration within a reaction time of a few seconds. The composition of the diluent is significantly affected between the primary reaction and the secondary reaction, that is, with a reaction time of 10 ⁻⁵ seconds to 10 ⁻³ seconds. By setting the diluent to H ₂ O or N ₂ , You can see that it is generated. In other words, assuming a gasified gas fuel with the composition shown in Table 1, the amount of recycled exhaust gas (D / F = 3) to be diluted to adjust to the primary combustion temperature in the range of 1700 ° C. (D / F = 3) When supplying steam or N ₂ to the combustor head when supplying to the section, it is apparent that H ₂ regeneration occurs at a reaction time of 10 ⁻⁴ seconds as shown in FIG. FIG. 3 shows the O ₂ , CO, and hydrogen component concentrations remaining in the combustion gas together with the combustion efficiency when the residence time of the combustion gas in the gas turbine combustor is about 20 ms.

When the diluent is an H ₂ O component, it can be seen that the CO component remaining in the combustion gas is reduced and the combustion efficiency is increased by 10 points. When N ₂ is used as the diluent, the residual amount of the hydrogen component is small and the combustion efficiency is further increased. Furthermore, as shown in FIG. 3, as a result of a trial calculation for the case where the diluent is CO ₂ , the oxidation of CO is greatly suppressed, and the combustion efficiency is reduced by 50 points or more. That is, increase of the CO ₂ component concentration in the diluent is significantly delay the time until the reaction is converged. As a result, in the tens of ms that is an example of the combustion reaction time in the gas turbine, the concentration of the O ₂ component and the unburned CO component remaining in the combustion exhaust gas increases, and the combustion efficiency decreases. This is because the gasification gas fuel is prevented from being oxidized by mixing the combustion exhaust gas. That is, as the H ₂ component concentration in the gasified gas fuel increases and the CO component concentration relatively decreases, the combustion reaction is promoted and the combustion efficiency tends to be improved.

Further, even when a part of the recycled exhaust gas is directly supplied to the head of the gas turbine combustor and the rest is supplied downstream from the intermediate position of the combustor, as illustrated in FIG. It has been found that flammability is improved by increasing H ₂ over time. In FIG. 18, when the total amount of the recycle exhaust gas is supplied to the head of the combustor (broken line, combustion temperature 1350 ° C.), it is divided and supplied to the combustor head (1700 ° C.) and the intermediate position (1350 ° C.). An example of the reaction phenomenon in the case (solid line) is shown, and the change over time of the H ₂ concentration when the recycled exhaust gas is supplied when shown by a circle in the figure is enlarged and shown by a dotted line A. Here, the reason why the H ₂ concentration is once lowered is that the whole is simply converted to 1 mol. From the dotted line A, it can be seen that H ₂ increases in about 0.1 ms. This is one of the effects of increasing H ₂ when the recycled exhaust gas is supplied to the gas turbine combustor.

From the results of the numerical analysis, CO in the _2-recovery IGCC for closed cycle gas turbine, CO ₂ gas in the diluent inhibits effect is greater to the oxidation reaction of CO in the fuel as an exhaust circulating gas, combustion efficiency It turns out that it reduces. In order to suppress the inhibition of the oxidation reaction of CO, it is most effective to increase the N ₂ component in the diluent, and the plant produces a large amount of N ₂ with an oxygen production device. It is possible to take advantage of this. In this case, there is a concern that thermal NOx is generated in the combustion process, and NOx increases due to exhaust gas circulation. In addition, when the working medium contains a large amount of N ₂ , an adverse effect such as the need for incidental equipment for CO ₂ recovery occurs. On the other hand, if raising of H _{2 O} component in the diluent is not limited thereto. That is, water vapor can be separated from CO ₂ relatively easily by condensing. Accordingly, it is shown for effect to promote combustion of the H _{2 O} concentration in the diluent, the result of investigation by the reaction numerical analysis in FIG. The horizontal axis is adjusted by increasing the H ₂ O component concentration in the diluent from 0% to 37% and decreasing the CO ₂ component concentration in the diluent. The reaction time is about 20 ms as in FIG. As the concentration of the H ₂ O component in the diluent increases, the concentration of the hydrogen component remaining in the combustion gas slightly increases, but the unburned CO component is greatly suppressed, and the combustion efficiency is greatly improved. found. In particular, by generating hydrogen component in the combustion process, also by CO ₂ component concentration decreases, which promotes the combustion reaction, the oxidation reaction of the fuel it is clear that the combustion time to converge is shortened It was.

Therefore, even if the recycle exhaust gas is supplied to the head / primary combustion region of the gas turbine combustor of the closed cycle gas turbine for CO ₂ recovery type IGCC, the amount of gasified gas fuel in the gas turbine combustor due to O ₂ It does not hinder the stoichiometric combustion reaction, but rather, it generates hydrogen in the combustion process in the gas turbine combustor to promote the combustion reaction and improve the combustion efficiency, thereby forming a closed loop for gasification gas. It is clear that it contributes to the establishment of a gas turbine. Moreover, no special equipment is attached to the plant system for supplying the working medium, which is a problem in the closed cycle gas turbine. Therefore, it is possible to minimize the increase in power generation cost. In addition, since the diluent is actively supplied to the combustion region of the gas turbine combustor, the O ₂ component remaining in the diluent can be actively involved in the gas turbine combustion, and the O ₂ in the diluent can be actively involved. _It also has the effect of reducing the concentration of _two components. In addition, since this system uses stoichiometric combustion of gasified gas fuel with O ₂ , the amount of oxidant supplied to the combustor is reduced, and power in the oxygen production plant is reduced. By reducing the concentration of O ₂ remaining in the combustion gas, the recycled exhaust gas can be used for transportation to a coal gasifier.

(Supply of recycled exhaust gas upstream of the combustor)
The combustion reaction of fuel is composed of many elementary reactions, and the flow in the gas turbine combustor is complicated and very fast, and it is difficult to control each elementary reaction involved in the oxidation reaction of fuel in detail. . Therefore, the recycle exhaust gas supplied to the head of the combustor is mixed with the gasified gas fuel before supplying the gasified gas fuel to the gas turbine combustor, as shown in FIG. 1 and FIGS. To a gas turbine combustor as a mixed gas. More preferably, the gasified gas fuel before being supplied to the gas turbine combustor and the recycled exhaust gas are mixed and maintained in a temperature range in which an increase in the hydrogen component concentration due to the reduction reaction is established. In other words, hydrogen is generated due to water vapor to increase the hydrogen concentration, and then supplied.

  FIG. 5 shows the result of analyzing the change in the hydrogen component concentration in the gasified gas fuel with respect to the reaction temperature when the gasified gas fuel and the diluent (recycled exhaust gas) for exhaust circulation are mixed. The mixing amount of the diluent is a two-fold molar amount of the gasified gas fuel. When the reaction temperature is 400 ° C. or lower, the hydrogen component concentration in the mixed gas hardly changes, and the hydrogen concentration in the gasification gas fuel increases by about 10% when the reaction is in the temperature range of 600 to 800 ° C. It can be seen that when the reaction temperature is further increased, hydrogen in the gasified gas fuel has been decomposed. In addition, an analysis conducted separately has shown that increasing the hydrogen component in the gasified gas fuel speeds up the combustion reaction and improves the combustion efficiency.

  FIG. 6 shows an analysis result when the amount of the diluent mixed with the gasified gas fuel is increased to a 4-fold molar amount of the gasified gas fuel. In this case, it is understood that the hydrogen component concentration in the gasified gas fuel is increased by setting the reaction temperature to 600 ° C. to 800 ° C. More preferably, by setting the reaction temperature to 600 ° C., the hydrogen component concentration in the gasified gas fuel can be increased by about 20%.

Further, FIG. 7 and FIG. 8 show the results of numerical analysis of the influence of the reaction temperature on the increase rate of H ₂ under a constant dilution rate (diluent / fuel). From this result, it was found that the reaction temperature at which H ₂ increases varies depending on the amount of recycled exhaust gas, that is, the dilution rate. In the case of the dilution rate (diluent / fuel) 3, as shown in FIG. 7, the ratio of H ₂ slightly decreases from 200 ° C. to 400 ° C. However, when the temperature exceeds 400 ° C., H ₂ tends to increase. % Peak reached. And while decreasing slightly from 600 degreeC to 800 degreeC, when it exceeded 800 degreeC, it became a rapid decreasing tendency, and it fell until it divided to 80% at 1000 degreeC. In the case of the dilution rate (diluent / fuel) 5, as shown in FIG. 8, the ratio of H ₂ slightly decreases from 200 ° C. to 300 ° C., but the ratio of H ₂ increases very slightly from 300 ° C. to 400 ° C. It showed a tendency to start, with a clear increasing trend of H ₂ above 400 ° C, reaching a peak above 120% at 600 ° C. And although it showed a tendency of slightly over 10% from 600 ° C to 800 ° C, it still maintained an increase of 10%, and when it exceeded 800 ° C, it showed a sharp decline, reaching 75% at 1000 ° C. Declined.

That is, in the fuel supply system upstream of the gas turbine combustor, the increase in the hydrogen concentration in the gasified gas fuel caused by mixing the recycle exhaust gas into the gasified gas fuel is a reduced state that occurs in a state where there is almost no oxygen. This is a reaction phenomenon. Therefore, temperature conditions are important when supplying hydrogen components by supplying recycled exhaust gas or a mixture of water vapor or N ₂ to exhaust gas into gasified gas fuel. Since the reaction rate and production rate of H ₂ O, H _2, and OH involved in hydrogen production are not sufficiently increased (exponentially), hydrogen is not generated no matter how much time is spent. On the other hand, if it is between 400 degreeC and 900 degreeC, hydrogen can be produced | generated by a reductive reaction. However, when it exceeds 800 ° C., it is oxidized by a small amount of O ₂ (0.3 vol%) remaining in the recycled exhaust gas, and the reduction of the hydrogen component in the fuel starts. Therefore, the gas mixture of the gasification gas fuel and the recycle exhaust gas in the fuel supply system downstream of the gasification furnace and upstream of the combustor should be maintained in a temperature range of at least 400 ° C to 900 ° C. However, it is preferably 600 to 800 ° C, more preferably about 600 ° C. When the temperature is in the range of 600 ° C. to 800 ° C., the reaction is exponentially activated to generate hydrogen, and hydrogen generation is most active in the vicinity of about 600 ° C. This increasing H ₂ component is generated by reducing H ₂ O (27.2 vol% in Table 1) in the recycled exhaust gas. And although there is slight O ₂ (for example, about 0.3 vol%) in the recycle exhaust gas, if it is 850 ° C. or less, the reaction rate at which H ₂ is generated is higher than oxidation, and FIG. as shown, actively generate H _2.

Further, FIG. 9 shows the result of numerical analysis of the influence of the amount of the diluent on the increasing rate of the H ₂ concentration in the fuel. From this result, the ratio of H ₂ is less than 100% up to 400 ° C. regardless of the dilution rate, but it shows a tendency to increase rapidly as the reaction temperature rises. Reaches a peak at a rate (only at a dilution rate of 2 reaches a peak at 800 ° C.), increases to about 110% regardless of the dilution rate at 800 ° C., and the rate of increase in H ₂ decreases rapidly after exceeding 800 ° C. It showed a tendency, and at 1000 ° C., the ratio of H ₂ was less than 80%, and it was found that an increase in H ₂ due to mixing of recycled exhaust gas was observed in the reaction temperature range of 600 ° C. to 800 ° C. Also in this result, a significant correlation was obtained between the dilution rate and the H ₂ increase rate in the vicinity of the reaction temperature of 600 ° C. where the largest increase in H ₂ is expected. Then, most the H ₂ compares the percentage increase of H ₂ per dilution at the reaction temperature 600 ° C. to increase, the increase or decrease in the amount of increase in increase and decrease of dilution ratio and H ₂ are proportional, increase in H ₂ When the dilution rate is 5, that is, when the entire amount of the combustion exhaust gas to be recycled is mixed with the gasified gas fuel, the amount of increase in H ₂ decreases as the dilution rate decreases. The increase amount of ₂ was small when the dilution rate was the smallest. In addition, since the optimum reaction temperature for generating H ₂ varies slightly depending on the gasification gas fuel composition and diluent composition, it is appropriate to adjust the temperature around 600 ° C. in actual operation. .

Here, the fuel supply system between the more recycled exhaust gas, preferably the total amount of the recycled exhaust gas supplied to the head of the gas turbine combustor 5, upstream from the combustor 5 and downstream from the gasifier 2. 4 and previously mixed with the gasified gas fuel increases the hydrogen concentration in the gasified gas fuel to increase the combustibility and promote the combustion reaction in the gas turbine combustor 5 as well as the combustion stability. It can be understood from FIG. As a result, unburned CO components generated in the combustion process of the gas turbine combustor or soot generated due to unburned CO can be suppressed, and the combustibility or combustion efficiency of the gas turbine combustor can be improved. . In addition, before supplying gasified gas fuel to a gas turbine combustor having a complicated flow and reaction process, it is possible to increase the hydrogen concentration of the fuel to improve combustibility, and Since it is possible to appropriately control the composition of the diluent or the ratio with water vapor, it becomes easier to more efficiently improve the combustibility of the closed cycle gas turbine for CO ₂ recovery type IGCC. Here, as is clear from FIG. 9, the dilution between about 2 and 4 with the combustion temperature at the head of the gas turbine combustor at 1500 to 1900 ° C. when the gasified gas fuel having the composition shown in Table 1 is used. At the rate (D / F), the increase in H ₂ concentration in the fuel is 1.08 to 1.17 times, and at the dilution rate 3, the increase in H ₂ concentration in the fuel is 1.12 times. This amount of increase in H ₂ concentration is not so high that the combustion temperature is significantly increased. On the other hand, when H ₂ having a high combustion speed is increased by about 10%, the gas turbine having a high fuel injection speed improves the combustion stability. Even a slight addition of about 10% has a great effect on combustion stability. In addition, as will be described later, when the amount of primary recycle exhaust gas supplied to the head of the gas turbine combustor is adjusted to 1500 to 1900 ° C. at the combustion temperature at the head of the gas turbine combustor, a fast reaction rate is maintained. However, by suppressing the reversibility of the reaction, the combustion efficiency can be maximized.

Further, in the closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation of the present invention, the temperature suitable for the reduction reaction for raising the hydrogen component in the gasification gas fuel on the upstream side of the combustor is shown in FIG. As shown in FIG. 6, FIG. 7, and FIG. 8, the gas turbine is affected by the amount of diluent mixed, but is generally in the range of 600 ° C. to 800 ° C. The heat of the gas turbine combustion exhaust gas exhausted from the gas, the heat of the gasifier, etc. can be used.

(Relationship between combustion reaction temperature and combustion efficiency)
Furthermore, the elementary reactions involved in the combustion reaction in the gas turbine combustor are affected by the composition of the gasified gas fuel, the composition of the diluent circulating in the recycle exhaust gas, and the reaction temperature. Change. That is, in order to promote the combustion reaction, it is important to set the combustion reaction region of the gas turbine combustor to an appropriate reaction temperature according to the reaction gas composition.

FIG. 10 shows the combustion of residual O ₂ , CO, and hydrogen component concentrations in the recycle exhaust gas when the ratio of the amount of the recycle exhaust gas to the gasified gas fuel, that is, the dilution rate (D / F) is changed under the same fuel composition. It is shown with efficiency. The reaction time is about 20 ms. The combustion temperature during the O ₂ stoichiometric combustion of gasified gas fuel is about 3100 ° C. when the diluent / fuel ratio is zero, that is, when no recycle exhaust gas is mixed, and this increases the diluent / fuel ratio. Accordingly, the combustion temperature decreases, and when the diluent / fuel ratio = 5, the combustion temperature corresponds to about 1350 ° C. From the analysis results shown in FIG. 10, when the diluent / fuel ratio is 3, the concentrations of O ₂ component, unburned CO and hydrogen component remaining in the combustion gas are the lowest and the combustion efficiency is the highest value. This is the result of the most accelerated fuel oxidation reaction according to the reaction gas composition and combustion reaction temperature when the diluent / fuel ratio is 3, which is important for improving the combustibility in a reaction time of about 20 ms. Index. That is, in this reaction time, the amount of diluent supplied to the combustion region of the gas turbine combustor is three times that of the gasified gas fuel, and the remaining diluent is supplied to the downstream side of the gas turbine combustor. Can be maintained high. Further, FIG. 11 shows the result of numerical analysis of the influence of the combustion time on the dilution rate (D / F) and the combustion efficiency. From this analysis result, if the combustion temperature at the head of the gas turbine combustor is between 1500 ° C. and 1900 ° C. (D / F≈2.5 to 4), as shown in FIG. 11, the existing LNG gas It has been found that high combustion efficiency can be obtained in a range from a combustion time using a turbine combustor (about 20 ms) to 100 ms or less. Here, in order to lengthen the combustion time, it can be easily adjusted by increasing the diameter of the combustion cylinder or increasing the length of the combustion cylinder.

Here, in considering the influence of the recycle exhaust gas in the combustor on the combustion reaction, the combustion temperature controlled by the primary recycle exhaust gas supplied to the head of the gas turbine combustor is 1500 to 1900 ° C. It is preferably 1600 ° C. to 1800 ° C., more preferably about 1650 ° C. to 1800 ° C., further preferably 1700 ° C. to less than 1800 ° C., and most preferably around 1700 ° C. However, the combustion temperature at the combustor head has a slight range depending on the variation of the composition of the gasified gas fuel, the operating conditions, and the like, and it is appropriate in actual operation to be 1700 ° C to 1800 ° C. . Therefore, the amount of the primary recycle exhaust gas supplied to the head of the gas turbine combustor is not uniform, but is determined by the calorific value of the gasified gas fuel. For example, when the calorific value of gasified gas fuel is low, the amount of recycle exhaust gas that makes the combustion temperature at the combustor head 1700-1800 ° C. is less than 3 times the mole. Generally, the calorific value of gasified gas fuel varies depending on the gasification system, gasification raw material, and the like. For example, in the case of the oxygen-blown gasified gas fuel shown in Table 1 (fuel calorific value: about 2750 kcal / m ³ N), 3 times mole of recycled exhaust gas of the gasified gas fuel is recycled to the head of the gas turbine combustor, that is, the combustion If it supplies to the area | region where reaction is active, the primary combustion area | region which makes combustion temperature a 1700 degreeC range can be formed. In addition, in the case of oxygen-blown gasified gas fuel by coal slurry conveyance, the calorific value is around 2000 kcal / m ³ N. In this case, the supply amount of the recycle exhaust gas is about 1700 ° C. at double moles. The combustion gas temperature can be adjusted.

When the reaction temperature in the head of the gas turbine combustor, that is, the primary combustion region is controlled in the range of 1500 ° C. to 1900 ° C., the combustion phenomenon in the combustor is often dominated by the reaction temperature, and the oxidation reaction rate However, the reversibility of the fuel oxidation reaction decreases and the oxidation reaction proceeds. As a result, unburned CO components or soot generated due to unburned CO is suppressed, and the combustibility or combustion efficiency of the gas turbine combustor is improved. In particular, in the vicinity of 1700 ° C. to 1800 ° C., the reversibility of the oxidation reaction of the fuel is maintained low, and an appropriate reaction rate is obtained and the oxidation reaction proceeds. Therefore, the combustion efficiency can be maintained as high as 92%. Even if the temperature is higher or lower than the temperature range of 1700 ° C. to 1800 ° C., the oxidation amount decreases. This is a condition where the amount of oxidation reaches a maximum value, and is not determined only by the oxidation rate as in a conventional LNG-fired gas turbine. However, if the flammability is to be improved most in a combustion reaction time of several tens of ms, the amount of oxidation and the oxidation rate are balanced. That is, as the combustion temperature decreases, the oxidation rate decreases and unburned components begin to increase. Therefore, when the temperature drops significantly below 1700 ° C., for example, below 1500 ° C., the reaction rate rapidly decreases until the reaction is completed. It takes time. On the other hand, at a temperature exceeding 1900 ° C., the reaction rate increases, but the reversibility increases and a high reaction amount cannot be obtained. Therefore, in the temperature range of 1900 ° C. or more and less than 1500 ° C., the combustion efficiency decreases, and the CO component and O ₂ concentration, which are unburned components remaining in the exhaust gas, increase. For example, in the oxygen-blown gasified gas fuel shown in Table 1, when the dilution rate is set to 2, the combustion temperature becomes too high at 1980 ° C. (FIG. 10), the reaction rate increases, but the reversibility increases and the combustion efficiency is Decrease to 84%. On the other hand, when the dilution ratio is 4 or more, the combustion temperature becomes too low (less than 1500 ° C.) (FIG. 10), but the reversibility decreases, but the reaction rate decreases conversely, and the combustion efficiency decreases to 88%. The CO component and O ₂ concentration, which are unburned components remaining in the exhaust gas, increased. Incidentally, since a part of the gas turbine combustion exhaust gas is exhausted from the chimney after CO ₂ is recovered, the fuel cost increases and the unit price of power generation increases when the CO concentration increases. In addition, if the residual O ₂ component concentration in the exhaust gas increases, the exhaust gas cannot be used for coal transportation, so it must not be established as a system or the external power must be used to reduce the O ₂ concentration. The unit price of power generation increases. Furthermore, the power of the oxygen production apparatus increases to produce more oxygen.

As described above, if the combustion temperature at the head of the gas turbine combustor is between 1500 and 1900 ° C., the reversibility can be lowered while the combustion reaction rate is high. In particular, when the temperature is in the range of 1700 ° C., it is possible to easily reduce the reversibility and increase the irreversibility when the oxidation reaction rate is high. The temperature at the 1700 ° C. range is a value that maximizes the combustion efficiency. Combustion at the head of the gas turbine combustor deteriorates in combustibility because the reaction rate decreases as the temperature decreases. And if the primary recycle exhaust gas with the combustion temperature of 1500-1900 ° C. at the head of the gas turbine combustor can be supplied to the head of the combustor, it is directly from the burner of the gas turbine combustor. Even when supplying to the head of the combustor after being pre-mixed with the gasified gas fuel downstream from the gasifier and upstream from the combustor, The primary combustion region of the closed cycle gas turbine combustor can also be distributed and supplied to the gasified gas fuel supply system downstream of the combustor and to the head of the gas turbine combustor. It is generated due to unburned CO components or unburned CO generated in the combustion process because the reversibility of the oxidation reaction of the fuel in the reactor decreases and the oxidation reaction proceeds. By suppressing soot, it can be achieved to improve the combustion or the combustion efficiency of the gas turbine combustor. Moreover, all or a part of the recycle exhaust gas required for lowering the combustion temperature at the head of the gas turbine combustor between 1500 and 1900 ° C. is gasified gas upstream of the gas turbine combustor 5. In the case where the fuel is mixed in advance and maintained in the temperature range of 400 ° C. to 900 ° C. and then supplied to the combustor head, combustion is combined with the effect that H ₂ having a high combustion rate is increased by about 10% Efficiency can be further increased. In other words, even if the addition is only about 10%, combustion stability is improved by suppressing the reversibility of the reaction while maintaining a high reaction rate while improving the combustion stability in a gas turbine combustor with a high fuel injection speed. Increases the effect on sex. As described above, the combustion temperature at the head of the gas turbine combustor is adjusted between 1500 to 1900 ° C., which is effective in improving combustion efficiency and combustibility and suppressing soot.

(Influence on flammability by mixing water vapor or nitrogen)
When either or both of water vapor and N ₂ are mixed in order to increase the hydrogen concentration of the gasified gas fuel, the gasified gas fuel or the gas turbine combustor is directly in the combustion region or upstream of the combustion region. It is desirable to mix with the recycle exhaust gas supplied to the head and supply it to the combustion region. In the range from the combustion region of the gas turbine combustor to the first stage blade inlet of the expansion turbine downstream, the direct combustion promotion effect due to the mixing of water vapor or nitrogen is very small or cannot be expected. FIG. 2 shows the analysis results at a reaction temperature of 1350 ° C. (combustor outlet gas temperature). When steam or N ₂ is supplied at a reaction temperature of 1350 ° C., H ₂ is regenerated (reaction time 10 ⁻⁴ seconds), but when 20 ms (reaction time 20 × 10 ⁻³ seconds) elapses at the combustor outlet, H ₂ It is clear that the combustion promotion effect by the regeneration of can not be expected. However, if H ₂ is generated in a time period of 10 ⁻⁴ seconds, the oxidation of CO proceeds, and at the same time, H ₂ increases and combustion in the combustor can be promoted to further improve the combustion efficiency. That is, even if steam or N ₂ is supplied from a portion having a low participation in the combustion reaction, for example, a position sufficiently away from the primary combustion region to the inlet of the first stage blade of the expansion turbine, the combustion promoting effect I can not expect to raise. Therefore, in the embodiment of FIG. 14, water vapor (or N ₂ ) is mixed into the recycled exhaust gas upstream of the compressor 8, so that the embodiment is not limited to the recycled exhaust gas supplied to the head of the gas turbine combustor. Steam or N ₂ is also mixed in the recycle exhaust gas as a diluent for adjusting the temperature of the combustion gas supplied downstream from the primary combustion region in the combustor. Just because it can't be expected to improve gender, it doesn't induce system problems. The supply of gas that mixes either or both of water vapor and N ₂ does not have to be mixed with the recycle exhaust gas or supplied to the combustion zone together with the recycle exhaust gas, but alone, upstream of the gas turbine combustor. The combustion promotion effect by the increase in the hydrogen concentration due to the regeneration of H ₂ can also be obtained by mixing with the gasification gas fuel in this fuel supply system or directly supplying it to the combustion zone. Therefore, when the recirculation amount of the gas turbine combustion exhaust gas decreases or the combustion efficiency deteriorates, the hydrogen component can be increased and the combustibility can be improved by flowing the water vapor.

As shown in FIG. 14, if water vapor is supplied to the recycle exhaust gas upstream of the combustor, H ₂ O is relatively increased and the amount of H ₂ reduced and generated in the fuel is further increased. In addition, when N ₂ is supplied instead of water vapor or in combination with water vapor, the oxidation reaction of CO and H ₂ proceeds. Of these two components, H ₂ occurs when the oxidation reaction is faster. Then, the time the oxidation of CO becomes significant, so that _{the H 2} is generated from _{H 2} O.

Here, in the case of supply of steam, in the case of this embodiment in which a combined cycle incorporating a steam turbine is used, a large amount of steam higher than the pressure in the combustor is generated. There is no technical problem in mixing with the recycle exhaust gas supplied to the head of the car. In addition, as a supply source of water vapor, the water separated from the recycle exhaust gas discharged outside the system for CO ₂ recovery can be recovered as heat by using a heat exchanger and used as steam. It is also possible to compress condensed water generated when a part of the gas is exhausted after removing CO ₂ and to inject it into the recycled exhaust gas after pressure increase. The pressure of the N ₂ by-produced in the O ₂ during manufacturing, for example, about 5 atm. Therefore, it is conceivable that a compressor for boosting the pressure is separately provided or mixed with the exhaust gas before the exhaust gas compressor. In addition, in IGCC, there is a system in which a compressor for N ₂ is separately prepared and the pressure is increased to about 30 atm and used for coal transportation, and this N ₂ may be branched and used.

Here, in the plant shown in FIG. 14, the supply of the gas obtained by mixing one or both of water vapor and N ₂ is premixed with the recycle exhaust gas, supplied to the combustion zone together with the recycle exhaust gas, or Independently, it is previously mixed with gasified gas fuel upstream of the combustor or directly supplied to the combustion zone. However, the CO component concentration or soot amount in the combustion gas discharged from the gas turbine combustor is monitored and the steam or nitrogen supplied to the recycle exhaust gas to be mixed with the gasified gas fuel before being supplied to the gas turbine combustor. By adjusting the amount of either or both and the amount of either or both of water vapor and / or nitrogen supplied to the recycle exhaust gas that is supplied directly to the combustor head, the CO emission concentration is controlled below a certain amount. You may make it comprise as follows. For example, in the plant shown in FIG. 15, the CO concentration, which is an unburned component in the gas turbine combustion exhaust gas discharged from the gas turbine by the measuring device / monitoring device 15, is measured or monitored, and feedback is performed based on the measurement result. The supply position or supply amount of the gas obtained by mixing one or both of water vapor and N ₂ injected into the gasified gas fuel can be switched by the controlled control device 4a. At this time, in the plant shown in FIG.
Since the supply position or amount of the recycle exhaust gas to the gasification gas fuel in the fuel supply system is feedback controlled so that the CO concentration in the combustion gas is below a certain amount, steam or N ₂ is supplied together with the recycle exhaust gas according to the instruction of the control device 4a. A gas obtained by mixing one or both of these may be injected into the gasified gas fuel and mixed. Even in this case, the selection of the supply position of the gas mixed with one or both of water vapor and nitrogen is not limited to switching the mixing device 4b for supplying the gas in the fuel supply system, Changing the position to which the gas is supplied by changing each device 4b is also included. Of course, the supply of the gas obtained by mixing one or both of water vapor and N ₂ may be independently supplied from the mixing device 4b instead of the recycled exhaust gas.

As described above, by adjusting the supply amount of the recycle exhaust gas, water vapor or nitrogen supplied to the gasified gas fuel, it becomes possible to appropriately control the amount of hydrogen components generated in the gasified gas fuel. It is possible to further improve the combustibility of the gasified gas fuel / O ₂ stoichiometric fuel closed cycle gas turbine by circulation.

(Supply position of recycled exhaust gas in the fuel supply system)
Since the reduction reaction by the supply of the recycle exhaust gas to the gasified gas fuel in the fuel supply system upstream of the gas turbine combustor is a slow reaction, it takes time. Further, the reduction reaction exhibits a unique phenomenon only in a narrow temperature range. That is, unlike the oxidation reaction (combustion phenomenon) of fuel, the reduction reaction exhibits a unique phenomenon by maintaining it at a specific reaction temperature for a long time. Therefore, by monitoring the CO concentration in the exhaust gas at the combustor outlet, expansion turbine outlet, or exhaust heat recovery boiler outlet, the combustibility and stability etc. in the combustor are evaluated, and recycled exhaust gas is obtained so that the optimum combustibility is obtained. It is more preferable to control the reduction reaction time by selecting the supply position in the fuel supply system.

  For example, as in the plant shown in FIG. 15, the measuring device / monitoring device 15 that measures or monitors the CO concentration that is an unburned component in the gas turbine combustion exhaust gas discharged from the gas turbine, and the measurement or monitoring. A control device 4a for switching the position or amount of supplying the recycle exhaust gas by feedback control in the fuel supply system between the gasification furnace and the gas turbine combustor so that the CO concentration in the combustion gas becomes a certain amount or less depending on the result; A plurality of mixing devices 4b such as nozzles or ejectors for injecting and mixing recycled exhaust gas into gasified gas fuel according to instructions from the control device 4a, and recycling by the control device 4a according to detection values from the measuring / monitoring device 15 Select the mixing device 4b that supplies exhaust gas, or feedback control the amount to be injected It is preferable to. Here, the selection of the supply position of the recycle exhaust gas is not only performed when the mixing device 4b for supplying the recycle exhaust gas is switched in the fuel supply system, but also mainly by changing the supply amount of the recycle exhaust gas for each mixing device 4b. It also includes changing the position where the recycle exhaust gas is supplied. In the present embodiment, the recycled exhaust gas may be supplied in a state where one or both of water vapor and nitrogen are mixed in some cases.

  Next, a description will be given of injection mixing of recycled exhaust gas, water vapor or nitrogen, and measurement of CO concentration in the recycled exhaust gas and adjustment of the injection amount position by monitoring for the purpose of generating a hydrogen component in the gasified gas fuel.

Recycled exhaust gas wants to obtain as high combustion efficiency as possible and reduce unburned CO and residual O ₂ . In order to use a part of the exhaust gas as a recycle exhaust gas for conveying a gasification raw material such as coal to the gasification furnace 2, it is better that the residual O ₂ concentration is small. Further, since a part of the exhaust gas is exhausted from the chimney 13, the remaining unburned components lower the plant thermal efficiency. Furthermore, when the concentration of O ₂ remaining in the exhaust gas increases, the power of the oxygen production apparatus 1 increases, leading to a decrease in plant thermal efficiency. Therefore, the CO concentration which is an unburned component in the recycle exhaust gas is measured and monitored, and the information is transmitted to the control device 4a, and the recycle exhaust gas (or water vapor or nitrogen) supply position or The mixing device 4b is adjusted so as to control the supply amount. CO concentration in the exhaust gas is in a proportional relationship between the residual O ₂ concentration, thus the residual O ₂ concentration can be reduced.

  The mixing device 4b for the recycle exhaust gas (or water vapor or nitrogen) to the gasified gas fuel adjusts the reaction temperature and the reaction time by arbitrarily setting from the outlet of the gasifier 2 to the inlet of the gas turbine combustor 5. It becomes possible. In an actual power plant, the reaction time and reaction temperature for producing hydrogen mainly depend on the mixing device 4b of the recycle exhaust gas (or steam or nitrogen). For example, the reaction temperature at which a hydrogen component is generated in the mixed gas is 600 ° C. to 800 ° C., but more preferable conditions in this range are limited by facilities. That is, in the process from the outlet of the gasifier 2 to the inlet of the gas turbine combustor 5, the gasified gas fuel CG1 repeats exhaust heat recovery from the power plant and reaches the 600 ° C. range at the combustor inlet. In other words, in an actual power plant, by adjusting the mixing device 4b, the supply position of the primary recycle exhaust gas (or steam or nitrogen) supplied to the fuel supply system upstream of the gas turbine combustor via the exhaust gas supply line HG1 is adjusted. It is possible to adjust the reaction temperature by switching.

In this way, by measuring and monitoring the CO concentration in the recycle exhaust gas and setting the recycle exhaust gas, water vapor or nitrogen mixing device 4b so as to reduce the CO concentration, there is a concern about deterioration of combustibility. It is possible to adopt an exhaust circulation closed cycle gas turbine in a gasification power plant, reducing CO ₂ exhausted from the power plant without greatly depending on CO ₂ separation and fixation technology and without impairing the thermal efficiency of the plant. can do.

In the gas turbine combustor, gasified gas fuel and recycled exhaust gas as a diluent are mixed in advance and supplied to the gas turbine combustor, so that O ₂ in the diluent is actively involved in gas turbine combustion. Thus, a synergistic effect of reducing the concentration of O ₂ remaining in the recycle exhaust gas and facilitating use of the recycle exhaust gas for coal transportation or the like can be obtained.

  Furthermore, the CO component concentration or soot amount in the combustion gas is constant with respect to the CO concentration measuring device 15 and the plurality of mixing devices 4b that can supply the additive gas from outside the fuel supply system into the gasified gas fuel. By using the control device 4a that performs feedback control as described above, the supply amount of the recycled exhaust gas itself is adjusted, or the amount of the recycled exhaust gas supplied to the gasification gas before being supplied to the gas turbine combustor and the recycling It is also possible to control the CO emission concentration below a certain amount by adjusting the distribution ratio with the amount of exhaust gas supplied directly to the combustor head.

(Effect of secondary recycling exhaust gas supply position on combustion efficiency)
Further, in the closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to the present invention, the recycle supplied to the combustor in order to maintain both the rated operation temperature and the combustion temperature for increasing the combustion efficiency. The amount of exhaust gas required to adjust the combustion temperature to 1500-1900 ° C where the combustion reaction is active at the head of the combustor, and necessary to lower the combustor outlet temperature of the combustion gas to the rated temperature It is preferable to divide and supply the amount. Here, of the amount of diluent (recycled exhaust gas) required to adjust the combustion gas temperature or the combustor outlet temperature to the rated temperature, the amount of recycled exhaust gas (referred to as primary recycled exhaust gas) supplied to the primary combustion region The remaining diluent (referred to as secondary recycle exhaust gas) excluding the amount is mainly intended to adjust the temperature of the combustion gas, and is sufficient from the part that is not involved in the combustion reaction, such as the primary combustion region of the combustor. It is preferable that the gas is supplied from a position having a gap to the inlet of the first stage blade of the expansion turbine. In addition, secondary cycle exhaust gas (may be further divided into secondary or tertiary in some cases) is limited to a certain amount supplied to the combustor head when the amount of recycled exhaust gas fluctuates. Therefore, it naturally varies. For example, when the circulation amount of exhaust gas increases, the amount supplied to the downstream side increases, and when it decreases, it decreases.

  FIG. 17 shows the result of numerical analysis performed on the influence on the combustion efficiency when the position for supplying the secondary exhaust gas is changed. In this numerical analysis, the combustion time in the entire combustor is 20 ms, and “total mixing” is the case where the entire amount of combustion exhaust gas to be recycled from the burner is supplied (in this case, 5 times the mole of the supplied fuel). is there. “1 ms” means that the primary exhaust gas supplied from the combustor burner is supplied to the combustor head, that is, the primary combustion region, in order to suppress the combustion temperature in the primary combustion region to about 1700 ° C. When 2 mol of secondary exhaust gas is supplied at a position 1 ms downstream from the burner end, that is, at a position where the fluid injected from the burner flows when 1 ms has passed, that is, the reaction time in the primary combustion region is 1 ms. I mean. The same applies to “3 ms” to “19 ms”.

  As a result, compared with the case where the entire amount of the recycled exhaust gas is directly supplied from the burner, the primary recycled exhaust gas and the remaining secondary or tertiary recycling in such an amount that the combustion temperature at the head of the gas turbine combustor is 1500-1900 ° C. Combustion efficiency was improved only by dividing the exhaust gas and supplying it downstream of the burner outlet at least 1 ms after the combustion time. Further, it has been found that it is preferable to supply the secondary exhaust gas 3 ms or more downstream from the gasified gas fuel or the primary exhaust gas injected from the head of the burner. It has been found that the combustion efficiency is most improved in the case of 19 ms downstream of the combustor. That is, in the case of “total amount mixing”, the combustion efficiency η = 75%, but when the exhaust gas was divided into at least two parts and the secondary exhaust gas was injected 19 ms downstream, the combustion efficiency increased to about 93%. Here, the combustion efficiency is improved as the supply position is moved to the downstream side of the burner outlet. In particular, the combustion efficiency is rapidly improved to 10 ms on the downstream side of 1 ms. Combustion efficiency was ensured. However, after 10 ms, the effect of improving the combustion efficiency began to decline more than before, and almost saturated. Here, in the combustor in which the combustion time in the entire combustor is 20 ms, the supply position of 10 ms is around the middle of the combustor. Therefore, it is preferable that the position where the secondary exhaust gas is supplied is downstream of the middle of the combustor. That is, as the position where the secondary exhaust gas or further tertiary exhaust gas is supplied further downstream from the primary combustion region, the time during which the combustion reaction temperature (1700 ° C.) in the primary combustion region is maintained is longer. Is estimated to advance. Here, considering only the combustion temperature at the head of the combustor, as shown in FIG. 17, in the case of total mixing for supplying the total amount of recycled exhaust gas necessary as a diluent to the head of the gas turbine combustor 5, The combustion efficiency is extremely bad at 75%. However, the total mixing in this case is a case where the total amount of the combustion exhaust gas to be recycled, the oxidant and the gasified gas fuel are directly supplied to the head of the gas turbine combustor, and the upstream of the gas turbine combustor 5 is mixed. This is different from the case where the entire amount of the recycle exhaust gas necessary as a diluent is supplied to the fuel supply system 4 and mixed with the gasified gas fuel in advance. In other words, the exhaust gas to be recycled is supplied to the fuel supply system 4 in advance and mixed with the gasified gas fuel and maintained in the temperature range of 400 ° C. to 900 ° C., thereby oxidizing the hydrogen component concentration by 10 to 20%. The effect of increasing the reaction speed, increasing the stability of the combustion reaction and increasing the combustion efficiency is not reflected in the numerical analysis of FIG.

(Reduction reaction heat source upstream of the combustor)
As a heat source for appropriately controlling the reaction temperature for generating hydrogen in the mixed gas of recycled exhaust gas and gasified gas fuel upstream of the gas turbine combustor, new equipment may be installed separately. It is preferable to use the heat of the plant, for example, the heat of the gasification furnace or the heat of the recycled exhaust gas recovered by the exhaust heat recovery boiler or the heat exchanger. There are more heat sources in a CO ₂ recovery gasification gas power plant. For example, the recycled exhaust gas has a temperature of about 770 ° C., and as shown in FIG. 5 or FIG. 6, it is required for the reaction for generating hydrogen in the mixture of gasified gas fuel and recycled exhaust gas, water vapor or nitrogen. The reaction temperature of 600 ° C. to 800 ° C. can be appropriately controlled. If a higher reaction temperature is required, the gasification gas fuel CG1 or gasification furnace 2 before gas purification can be used as the heat source, and the gasification gas fuel and the recycle exhaust gas, water vapor or nitrogen are used as the recycle exhaust gas. Higher reaction temperatures can be obtained by heat exchange with G. Conversely, when it is important to adjust to a lower temperature and a narrower temperature range, the exhaust gas line of the gas turbine 6 can be used as a heat source so that the temperature can be adjusted to a predetermined temperature.

For example, as shown in FIG. 16, in order to circulate the gas turbine combustion exhaust gas and supply it to the gas turbine, it is necessary to lower the temperature of the exhaust gas once and then pressurize it with the compressor 8. By obtaining a heat source with the provided heat exchanger 16 or obtaining a heat source in the exhaust heat recovery boiler 7, it is possible to adjust to an arbitrary temperature below the combustion exhaust gas temperature. As a result, there is no need to obtain a heat source required for the reaction for generating hydrogen outside, and no internal power is required, and the hydrogen component is increased in the gasified gas fuel, and the gasified gas fuel by exhaust circulation is used. The combustion stability of the O ₂ stoichiometric combustion is improved, the unburned CO component remaining in the recycled exhaust gas is reduced, and the O ₂ component is also reduced. The gasification furnace 2 includes a gasification furnace section (1800 ° C. to 1100 ° C.) and a heat recovery section (the temperature of the gasification gas fuel is reduced to 400 ° C.), and uses these heat sources. Thus, it is possible to appropriately control the temperature of the mixed gas of gasified gas fuel and recycled exhaust gas and / or water vapor or nitrogen to a reaction temperature of 600 ° C. to 800 ° C. required for the reaction for generating hydrogen.

(Adjustment of recycled exhaust gas supply)
Further, in the closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation, it is conceivable that the properties of the gasification gas fuel will fluctuate temporarily and the amount of heat generated by the fuel will change drastically. Therefore, although not shown in the figure, the fuel calorific value of the gasified gas fuel is monitored, and when the calorific value changes, the combustion temperature changes accordingly, so that the combustor outlet temperature is set to the rated temperature. Since the amount of the recycle exhaust gas required for this also varies, it is desirable to adjust these appropriately. In this case, when the entire amount of the recycled exhaust gas is supplied to the fuel supply system 4 upstream of the gas turbine combustor 5, the amount is changed. Further, when the combustion temperature of the combustor head is adjusted to fall within the range of 1500 ° C. to 1900 ° C., preferably within the range of 1700 ° C. to 1800 ° C., the recycle exhaust gas supplied to the primary combustion region of the combustor head It is preferable to adjust the combustor outlet temperature to the rated temperature by adjusting the distribution ratio between the amount of the secondary and tertiary recycled exhaust gas supplied downstream from the combustor head.

  For example, the fuel supply system between the gasification furnace 2 or the gasification furnace 2 and the gas turbine combustor 5 is equipped with a device for measuring the calorific value of the gasification gas fuel, and the calorific value of the gasification gas fuel is monitored. It is preferable to adjust the amount of the recycle exhaust gas supplied to the combustor head according to the change in the calorific value. However, if the calorific value of the gasified gas fuel does not fluctuate significantly, the combustor outlet temperature of the combustion gas can be kept within a predetermined temperature range without adjusting the total amount of recycled exhaust gas.

Here, the monitoring of the calorific value of the fuel can easily calculate the calorific value using a known calorific value measuring method or apparatus, for example, a gas chromatography method or a calorimeter, or can instantaneously measure the calorific value of the gas. In the case of the gas chromatography method, the calorific value can be calculated by measuring the concentrations of CO, H ₂ , CH ₄ , CO ₂ , H ₂ O, and N ₂ in the gasified gas fuel. Here, the component analysis by gas chromatography is accurate, but the analysis takes about 5 minutes. On the other hand, calorimeters can measure the calorific value of gas instantaneously, although the analysis accuracy is reduced. Therefore, it is preferable to confirm that the calorific value of the gasified gas fuel does not vary greatly by using a component analysis by gas chromatography and a calorimeter together.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the CO ₂ recovery type gasification power plant of this embodiment, it is driven by the exhaust heat recovery boiler that generates steam using the heat of the high-temperature exhaust gas discharged from the gas turbine, and the steam generated here. Although it is configured as a gasification combined power plant including a steam turbine and a generator coupled to the steam turbine to output electric power, it is not particularly limited to this, and CO ₂ adopting only a closed cycle gas turbine. You may comprise as a collection-type gasification power plant.

Further, when N ₂ is mixed instead of steam, thermal NOx may be generated, so a denitration device or a non-catalytic denitration system may be required, but it is more flammable than when steam is mixed. It is effective in terms of improving Furthermore, in the present embodiment, the case where either water vapor or N ₂ is mixed with the recycled exhaust gas to be recycled has been described, but the present invention is not particularly limited thereto, and a mixed gas of water vapor and N ₂ is mixed with the recycled exhaust gas. You may let them.

Further, as shown in FIG. 14, the supply of water vapor or N _{2 to} the gasified gas fuel is merely an example of mixing the water vapor AD with the recycle exhaust gas recycled before the compressor 8. Depending on the situation, the gas may be supplied between the gas purification device 3 and the gas turbine combustor 5 or, in some cases, at the outlet of the gasification furnace 2, or the exhaust gas supplied to the combustor 5 immediately before the combustor 5. You may make it supply to.

1 Oxygen production equipment
2 Gasifier
3 Gas purification equipment for gasification gas
4 Recycle exhaust gas (diluent), steam or nitrogen injection and mixing position to gasified gas fuel
4a Equipment for controlling the supply position of recycled exhaust gas (diluent), water vapor or nitrogen
4b Recycle exhaust gas (diluent), water vapor or nitrogen supply position
5 Gas turbine combustor
6 Gas turbine
7 Waste heat recovery boiler
8 Exhaust gas compressor
9 Generator
10 Steam turbine
11 Condenser
12 CO ₂ recovery equipment
13 Chimney
14 Gas turbine axle
15 Measuring and monitoring device for CO emission concentration in exhaust gas
15a Signal for adjusting the position of circulating exhaust gas supply to gasified gas fuel
16 Heat exchanger
Supply of water vapor or nitrogen to adjust AD combustor outlet gas temperature
AO2 Oxygen-based oxidizer
C Gasification raw materials such as coal
CG1 Gas after gasification
CG2 Gasified gas fuel after gas purification
CG3 Gasified gas fuel after reforming, in which gasified gas fuel and recycled exhaust gas, water vapor or nitrogen are mixed to increase the concentration of hydrogen components in the fuel
CO ₂ recovered from CD gas turbine combustion exhaust gas
FG gas turbine combustor exhaust gas
FW Condensate / Water supply
G Gas after expansion turbine exhaust
Recycled exhaust gas after HG compressor
HG1 Exhaust gas supply line that supplies recycled exhaust gas to the gas turbine combustor via the fuel supply system
Exhaust gas supply line that directly supplies recycled exhaust gas to the head of the HG1 'gas turbine combustor
HG2 An exhaust gas supply line that supplies recycled exhaust gas from the head of the gas turbine combustor to the inlet of the first stage blade of the gas turbine.
HG3 Exhaust gas supply line for transporting gasified raw materials to gasifier
Steam, the working medium of ST steam turbine plant

Claims (8)

A facility for gasifying a raw material such as heavy oil or coal with an oxidant, and a gas purification facility for purifying a gasification gas generated in the gasification facility, wherein the gasification gas is a main fuel, oxygen is A gas turbine combustor that performs stoichiometric combustion with an oxidizer as a main component, a gas turbine that is driven by combustion gas, a generator that is coupled to the gas turbine and outputs electric power, and discharged from the gas turbine In a closed cycle gas turbine power plant for gasification gas including a CO ₂ recovery device that recovers CO ₂ when exhausting part of the exhaust gas as a gas turbine working medium and discharging the remaining exhaust gas outside the system , At least a part of the gas turbine combustion exhaust gas to be recycled is disposed downstream of the gasification furnace and upstream of the combustor. Supplying the gasified gas fuel before being supplied to the gas turbine combustor, maintaining a temperature of 400 ° C. to 900 ° C. to decompose water vapor in the gas turbine combustion exhaust gas into hydrogen, A closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation, characterized in that the hydrogen component concentration in the gasification gas fuel is increased and then supplied to the gas turbine combustor. _{2. The} closed cycle gas turbine power generation for CO ₂ recovery type gasification gas power generation according to claim 1, wherein the total amount of the gas turbine combustion exhaust gas recycled to the gas turbine combustor is supplied to the fuel supply system. plant. By monitoring the CO emission concentration or soot amount in the combustion gas discharged from the gas turbine combustor and adjusting the supply position of the gas turbine combustion exhaust gas to the fuel supply system, the CO emission concentration is kept constant. The closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to claim 1 or 2, wherein the production is controlled to be less than or equal to the amount to suppress the generation of soot. By monitoring the CO component concentration or soot amount in the combustion gas exhausted from the gas turbine combustor and adjusting the supply amount of the gas turbine combustion exhaust gas, the CO exhaust concentration is controlled to a certain amount or less. The closed-cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to any one of claims 1 to 3, wherein generation of soot is suppressed. The gasified gas fuel supplied to the head of the gas turbine combustor or the gas turbine combustion exhaust gas or a mixed gas thereof is mixed in advance, or the head of the gas turbine combustor alone is either steam or The closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to any one of claims 1 to 4, wherein either one or both of nitrogen are mixed and supplied. By monitoring the CO component concentration or soot amount in the combustion gas discharged from the gas turbine combustor and adjusting the supply amount of the gas in which one or both of the water vapor and nitrogen are mixed, the CO emission concentration was controlled at a constant amount or less, soot CO ₂ recovery gasification gas power for closed cycle gas turbine power plant according to claim 5, wherein suppressing the formation of. As a heat source for appropriately controlling the reaction temperature for generating hydrogen in the mixed gas of the gas turbine combustion exhaust gas and the gasification gas, it is recovered by the heat of the gasification furnace or the exhaust heat recovery boiler or heat exchanger. The closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to any one of claims 1 to 6, wherein heat of the gas turbine combustion exhaust gas is utilized. 2. A part of the gas turbine combustion exhaust gas to be recycled is supplied downstream from a head of the gas turbine combustor to an inlet of a first stage blade of the gas turbine. The closed cycle gas turbine power plant for CO ₂ recovery type gasification gas power generation according to any one of 3 to 7.

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