JP2010151112A - Oxygen burning co2 recovery turbine system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance thermal efficiency and to simplify a system constitution in a CO<SB>2</SB>recovery type water vapor circulation cycle in which a fuel is oxygen-burned, a water vapor is condensed from a mixed gas comprising produced CO<SB>2</SB>and the water vapor, the CO2 of high concentration is directly recovered and condensed water is recycled/utilized. <P>SOLUTION: The fuel is burned by oxygen and outlet water vapor of a high pressure vapor turbine 1 in an oxygen combustion unit 2 to generate the mixed gas comprising the CO<SB>2</SB>and the water vapor of high temperature, and a heat exchange 4 is installed at an outlet of a low pressure gas turbine 3 in a back stream of the oxygen combustion unit 2. The water vapor of high pressure is generated, and a whole amount of the water vapor in the mixed gas is condensed by a condenser 6 installed in a back stream of the heat exchanger 4. Since the water vapor of high pressure enhances the thermal efficiency, motive power is recovered by the high pressure vapor turbine 1, is fed to the oxygen combustion unit 2, is re-heated by combustion of the fuel and is fed to the low pressure gas turbine 3 to perform recovery of the motive power. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

Detailed Description of the Invention

Industrial application fields

The present invention relates to an oxyfuel CO ₂ recovery turbine system. More specifically, the present invention drives a low-pressure gas turbine with a mixed gas composed of water vapor and CO ₂ produced by burning fossil fuel and biofuel, and heat of the combustion gas after driving the low-pressure gas turbine. It relates to a modified Rankine cycle oxyfuel combustion CO ₂ recovery turbine system that uses CO ₂ as a partial working fluid configured to drive a high pressure steam turbine connected to a low pressure gas turbine by steam generated in step 1.

The oxyfuel combustion CO ₂ recovery turbine system generates a mixed gas composed of water vapor not containing nitrogen and CO ₂ by oxyfuel combustion of the fuel, and easily cools and separates the water vapor in the mixed gas to achieve a high concentration. Development is expected as CO ₂ can be recovered. However, a highly efficient and highly feasible system similar to the system has not been developed.

Biofuel is carbon-neutral (because it is considered as a substance that fixes CO ₂ in the atmosphere, so CO ₂ generated by combustion is not counted), and is attracting attention as a power generation cycle without CO ₂ emissions. As this biofuel combustion turbine system, for example, a natural gas-fired gas turbine combined power generation shown in FIG. 6 has been conventionally considered.

Problems to be solved by the invention

However, the cycle of FIG. 6 does not capture the CO ₂ that is generated. If the generated CO _{2 is} to be recovered, a separate CO ₂ separation facility is required after the exhaust heat recovery boiler. However, this facility is a large-scale facility, which increases the equipment cost and requires a large amount of power. It becomes.

The present invention improves the feasibility of collecting and storing CO ₂ generated by fuel combustion by directly recovering high concentration CO ₂ with a relatively simple system configuration without requiring these incidental facilities. The purpose is to provide a complete cycle.

The system of the present invention can be driven by fossil fuels such as natural gas and light oil. However, when it is driven by biofuel, it collects CO ₂ generated from the carbon-neutral biofuel so that it can be recovered from this system. The amount of CO ₂ stored can be counted as a reduction amount, and theoretically, the CO ₂ concentration in the atmosphere can be reduced.

Means for solving the problem

In order to achieve such an object, the present invention generates a mixed gas composed of water vapor and CO ₂ by heat obtained by equivalent combustion of fuel and pure oxygen, and introduces the mixed gas into a low-pressure gas turbine to drive it. In the oxyfuel combustion CO ₂ recovery turbine system that condenses all the water vapor in the outlet gas mixture of the low-pressure gas turbine and discharges the water generated by the equivalent combustion of the pure oxygen and hydrogen out of the system and then supplies water again. An oxygen combustor is provided between the high-pressure steam turbine and the low-pressure gas turbine to equivalently combust fuel and pure oxygen to reheat the outlet steam of the high-pressure steam turbine, while the heat source is the outlet mixed gas of the low-pressure gas turbine. The feed water is heated by the exchanger to generate steam, and the entire amount of the generated steam is introduced into the high-pressure steam turbine, and the outlet steam of the high-pressure steam turbine is used as the upstream acid. And so as to drive this by introducing a low pressure gas turbine with reheating and introduced into the combustor.

Further, the oxyfuel CO ₂ recovery turbine system of the present invention uses the steam generated by using the outlet mixed gas of the low-pressure steam turbine as a heat source after passing through the heat exchanger, the steam of the oxygen combustor and the first low-pressure gas turbine. Introduced into the cooling passage in the first stage stationary blade, cools the inner wall surface of the oxycombustor and the first stage stationary blade, and superheats the steam by the heat of the mixed gas generated by combustion in the oxycombustor. I am doing so.

Action

The outlet steam of the high-pressure steam turbine is reheated by an oxycombustor that equivalently burns fuel and pure oxygen, raising the inlet mixed gas temperature to the low-pressure gas turbine and increasing the thermal efficiency. Moreover, the feed water is heated to steam by the heat of the mixed gas by a heat exchanger that uses the mixed gas at the outlet of the low-pressure gas turbine as a heat source. Therefore, the entire amount of water vapor required for the entire cycle can be evaporated. In addition, the turbine blades are cooled by the outlet steam of the high-pressure gas turbine to a temperature at which the blades of the low-temperature gas turbine can withstand the mixed gas of high-temperature steam and CO ₂ generated by the combustion of the fuel and the pure oxygen.

  In the case of the invention of claim 2, the steam generated by the mixed gas at the outlet of the low-pressure steam turbine is further heated by the superheater provided in the wall surface of the oxygen combustor and the first stage stationary blade of the low-pressure gas turbine. And the wall of the oxycombustor and the first stage stationary blade are cooled, so that the temperature of the steam at the inlet of the high-pressure steam turbine can be increased and the temperature of the mixed gas at the outlet of the oxycombustor can be increased. The thermal efficiency of is improved.

  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 the oxyfuel combustion CO ₂ recovery turbine system of the present invention. FIG. 2 shows a structural example of the oxyfuel CO ₂ recovery turbine of the present invention. In this hydrogen combustion turbine system, a high-pressure steam turbine 1 and a low-pressure gas turbine 3 that drive a generator 9 are installed on the same axis, and are rotated by passing steam and mixed gas through the turbines 1 and 3. To give a rotation.

  On the upstream side (turbine inlet side) of the low-pressure gas turbine 3, an oxycombustor 2 is provided in which fuel is equivalently burned with pure oxygen to reheat the outlet steam of the high-pressure steam turbine. In the case of the present embodiment, a heat exchanger 4 is provided on the downstream side (turbine outlet side) of the low-pressure gas turbine 2 by evaporating the feed water using the mixed gas output from the low-pressure gas turbine 3 as a heat source to make water vapor. . That is, the feed water is evaporated by the mixed gas at the outlet of the low-pressure gas turbine 3 heated to a high temperature by reheating the oxycombustor 2 to obtain water vapor. The steam generated by the heat exchanger 4 is directly introduced into the high-pressure steam turbine 1.

All the water vapor in the mixed gas after being used to evaporate the feed water in the heat exchanger 4 downstream of the low-pressure gas turbine 3 is condensed in the condenser 6 and the residual gas, CO _2, is recovered. Is done. The separated condensate is circulated again as the feed water after the water generated by the combustion of fuel and oxygen is discharged out of the system. The residual gas in the feed water is deaerated by the deaerator 8 by extracting a part of the water vapor at the outlet of the high-pressure steam turbine, degassed, and then supplied to the heat exchanger 4.

The oxyfuel CO ₂ recovery turbine system configured as described above operates as follows.

  The feed water supplied by the feed water pump 9 is supplied to the heat exchanger 4 using the steam discharged from the low-pressure gas turbine 3 as a heat source, and converted into steam using the heat of the outlet mixed gas of the low-pressure gas turbine 2. The steam generated in the heat exchanger 4 is introduced into the high-pressure steam turbine 1 to drive it.

  Next, the steam discharged from the high-pressure steam turbine 1 is introduced into the oxycombustor 2 and reheated. In this oxycombustor 2, fuel and pure oxygen are burned in an equivalent amount to obtain heat. Therefore, although the combustion heat becomes very high, it is diluted by the outlet steam of the high-pressure turbine 1 and lowered to, for example, about 1500 ° C.

  The water vapor discharged from the high-pressure steam turbine 1 is introduced into the oxycombustor 2 and reheated by the equivalent combustion of fuel and pure oxygen to be heated. The reheated mixed gas is introduced into the low-pressure gas turbine 3 to drive it. At this time, part of the steam at the outlet of the high-pressure steam turbine 1 is introduced into the low-pressure gas turbine 3 through the bypass passage 11 as cooling steam for the blades of the low-pressure gas turbine.

After the low-pressure gas turbine 3 is driven, the steam and CO ₂ mixed gas is introduced into the heat exchanger 4 and used as a heat source for evaporating the feed water, and then the water vapor in the mixed gas is completely condensed in the condenser 10. After that, CO ₂ which is a residual gas is recovered. Moisture generated by combustion in the oxycombustor 2 is discharged out of the system. A part of the outlet steam of the high-pressure turbine 1 is extracted and used as a heat source for the deaerator 8. The water vapor used in these deaerators 8 becomes water and is returned to the water supply diameter or condenser 10. The condensed water is deaerated in the deaerator 10, and is circulated and supplied by the water supply pump 9.

  As a result, a TS diagram as shown in FIG. 3 is obtained.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, as shown in FIGS. 4 and 5, as a system for improving the thermal efficiency by further increasing the temperature of the steam at the inlet of the high-pressure steam turbine 1, the wall of the oxycombustor 2 and the first stage of the low-pressure gas turbine are used. A cooling pipe is provided in the stationary blade, and the inside is superheated through steam generated by the heat exchanger 4, and the inner wall surface of the oxycombustor 2 and the first stage stationary blade are cooled. In this case, the temperature of the inlet steam to the high-pressure steam turbine 1 is higher than that of the first embodiment, so that the thermal efficiency is higher.

  In the present embodiment, both the wall surface of the oxycombustor 2 and the first stage stationary blade of the low-pressure turbine 3 are provided with a cooling structure using water vapor, but either one may be provided with a cooling structure.

The invention's effect

As is apparent from the above description, the oxyfuel combustion CO ₂ recovery turbine system of the present invention is a high-temperature mixed gas generated by the oxygen combustor 2 that performs equivalent combustion of the water vapor at the outlet of the high-pressure steam turbine 1, fuel and pure oxygen. Even if the low-pressure gas turbine 3 is driven, it has a sufficient amount of heat, so that the heat exchanger 4 can generate all the water vapor required for the entire cycle, and compresses a part of the steam. A machine is not required and the inlet steam temperature of the low-pressure gas turbine 3 can be increased to increase the thermal efficiency.

In addition, since it is cooled by steam discharged from the high-pressure steam turbine to a temperature at which the blades of the low-pressure gas turbine 3 can withstand the high-temperature mixed gas generated by the combustion of high-temperature fuel and pure oxygen, the oxyfuel combustion CO ₂ recovery turbine system Is easy to put into practical use.

  In the case of the invention of claim 2, the water vapor generated in the heat exchanger 4 is further heated up and supplied to the high-pressure steam turbine 2 by the superheater installed in the wall surface of the oxycombustor 2 and the low-pressure gas turbine 3. Therefore, the output of the high-pressure steam turbine is improved, and the heat efficiency can be increased accordingly.

  As a result, in the case of the invention of claim 2, a TS diagram as shown in FIG. 6 is obtained.

It is a cycle configuration diagram showing an embodiment of the oxyfuel combustion CO ₂ recovery turbine system of the present invention. FIG. ₂ is a structural conceptual diagram of an oxyfuel CO ₂ recovery turbine according to the embodiment of FIG. 1. FIG. _{2 is} a TS diagram of the oxyfuel CO ₂ recovery turbine system according to the embodiment of FIG. 1. It is a cycle configuration diagram showing another embodiment of the oxyfuel combustion CO ₂ recovery turbine system of the present invention. FIG. 3 is a structural conceptual diagram of an oxyfuel CO ₂ recovery turbine according to the embodiment of FIG. 2. FIG. 3 is a TS diagram of the oxyfuel CO ₂ recovery turbine system according to the embodiment of FIG. 2. 1 shows an oxyfuel CO ₂ recovery turbine system of the present invention and an embodiment for storing the recovered CO ₂ in an underground aquifer. From a conventional gas turbine exhaust gases of a combined cycle system, showing an embodiment for recovering CO ₂ using CO ₂ recovery apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High pressure steam turbine 2 Oxygen combustor 3 Low pressure gas turbine 4 Heat exchanger 5 Steam drum 6 Condenser 7 Deaerator 8 Feed water pump 9 Generator 10 Turbine blade cooling steam flow path 11 Superheater (combustor inner wall)
12 Superheater (turbine first stage stationary blade)
13 Turbine axle 14 Thrust bearing 15 Journal bearing 16 CO ₂ compressor 17 Motor 18 Underground aquifer 19 Air compressor 20 Combustor 21 Gas turbine 22 Waste heat recovery boiler 23 Steam turbine 24 CO ₂ absorber 25 Reboiler 26 Absorbed liquid regeneration Tower

Claims (2)

Equivalent combustion of fossil fuels such as natural gas and light oil and fuels (hereinafter referred to as biofuels) produced from biomass such as ethanol, fatty acid esters and glycerin and pure oxygen to generate a mixed gas consisting of water vapor and CO ₂ The gas is introduced into a low-pressure gas turbine and driven, and after the temperature is lowered by a heat exchanger provided at the outlet of the low-pressure gas turbine, cooling is performed with seawater or the like, thereby recovering all the water vapor in the mixed gas. Oxygen combustion CO ₂ recovery that separates the water and collects high-concentration CO ₂ as the remaining gas, and supplies water again excluding water generated by the equivalent combustion of the fossil fuel, biofuel, and pure oxygen In the turbine system, a high pressure steam turbine and a low pressure gas turbine are provided, and fuel and pure oxygen are equivalently burned between the high pressure steam turbine and the low pressure gas turbine. An oxygen combustor that reheats the outlet steam of the high-pressure steam turbine, while generating the steam by heating the feed water with a heat exchanger provided at the outlet of the low-pressure turbine using the outlet steam of the low-pressure gas turbine as a heat source, The total amount of the generated steam is introduced into the high-pressure steam turbine, and the outlet steam of the high-pressure steam turbine is introduced into the oxycombustor and reheated and introduced into the low-pressure gas turbine to drive it. An oxyfuel combustion CO ₂ recovery turbine system that uses outlet steam as a heat source of the heat exchanger on the downstream side. Steam that has passed through the heat exchanger and is evaporated using the outlet steam of the low-pressure gas turbine as a heat source is introduced, and a mixed gas composed of steam and CO ₂ heated by the combustion heat of the fuel in the upstream oxygen combustor A superheater that superheats as a heat source is installed inside the wall of the oxycombustor and the first stage stationary blades of the low pressure gas turbine, and at the same time, the wall of the oxycombustor and the first stage stationary blades of the low pressure gas turbine are cooled. The oxyfuel CO ₂ recovery turbine system according to claim 1.

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