JP2003074372A - Gas turbine facility using a closed system of fuel and combustion gas using underground coal seam - Google Patents

Abstract

(57) [Problem] To provide a gas turbine system, in particular, a gas turbine power generation system for recovering almost all of carbon dioxide gas generated by using coal seam gas so as not to be released into the atmosphere. SOLUTION: Oxygen-combustion gas turbine 1 is driven by burning methane gas with oxygen separated from air by oxygen production device 3 to remove carbon dioxide discharged from the turbine together with air components after oxygen is separated. By injecting carbon dioxide into the underground coal seam 7 to fix carbon dioxide in the coal seam, and recovering the coal seam gas to the ground by the gas pushing action of the injected gas and supplying it as fuel for the gas turbine, Suppresses atmospheric emissions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine facility closed by injecting generated carbon dioxide together with nitrogen and burning methane gas recovered from an underground coal seam with oxygen.

[0002]

2. Description of the Related Art Since industrial activities have become remarkably active, it has been strongly feared that artificially released carbon dioxide causes global environmental damage. Particularly, the amount of carbon dioxide emitted from a power generation facility using fossil fuel is large, and it is required to suppress the release of this carbon dioxide gas into the atmosphere.

Research is being carried out in various places to meet the demand for suppressing the release of carbon dioxide into the atmosphere, and the New Energy Industrial Technology Development Organization (NEDO) is aiming to reduce the carbon dioxide emissions of power generation facilities and to improve power generation efficiency. Closed type gas turbine power generation systems are being studied. The gas turbine power generation system studied here is a coaxial combination of a steam turbine and a closed cycle gas turbine equipped with a methane oxycombustor.
In the methane oxycombustor, the steam discharged from the high-pressure steam turbine is heated together and used as a driving gas in the high-temperature gas turbine, and then a part of the steam is extracted and supplied to the steam low-pressure turbine.

Most of the carbon dioxide gas generated in the methane oxy-fuel combustor circulates in the gas turbine, but the part accompanying the steam drawn to the low-pressure steam turbine is separated by the steam turbine condenser and compressed by the compressor. Recycle and fix by appropriate method and collect. As described above, by closing the gas turbine system, it is possible to facilitate the recovery of carbon dioxide, but advanced technology is required for its realization and it is currently under development. Although the method of recovering carbon dioxide used in this new system has not been clarified, it is a promising method to recover carbon dioxide emitted from thermal power plants without releasing it into the atmosphere and making it into greenhouse gases. As such, for example, a method of liquefying and storing on the seabed, a method of press-fitting into an underground aquifer, etc. are known. In particular, the method of storing on the seabed is expected to have a large capacity, but when considering a long-term span of tens or hundreds of years,
It should be noted that liquid carbon dioxide gas will be released back to the atmosphere.

On the other hand, although various energy sources have been developed in response to an increase in energy demand, coal bed gas contained in a coal bed is receiving attention. Coal beds are distributed all over the world,
The reserves of coal are enormous. A large amount of coal bed gas containing methane as a main component exists in the coal bed. However, conventionally, in order to prevent the danger of coal bed gas during coal mining, before coal mining, the gas is sufficiently degassed, and during coal mining, air is sent to the tunnel to ventilate and release it to the atmosphere, or it is used as fuel in the plant Was there. Coal bed gas is present in a large amount in a state of being adsorbed on coal regardless of the quality of coal, but it is known that coal layer gas is released by exposing it to the atmosphere or by injecting a fluid into the coal bed. Therefore, it is conceivable to collect and use methane gas for coal layers that cannot be mined or coal layers that have become unprofitable due to poor profitability. Furthermore, the coal bed is underground and adsorbs and fixes carbon dioxide gas, and thus has the potential of becoming a promising disposal site.

[0006]

Therefore, a problem to be solved by the present invention is to use a coal bed gas as a fuel to recover almost all of the carbon dioxide gas generated and prevent it from being released into the atmosphere. In particular, it is to provide a gas turbine power generation system. It is also necessary to supply a system designed to recover as much coal bed gas as fuel from the coal bed as much as possible.

[0007]

In order to solve the above problems, the gas turbine equipment of the present invention drives an oxyfuel gas turbine by burning coal bed gas recovered from a coal bed with oxygen separated from air. Then, the discharged carbon dioxide is pressed into the underground coal bed together with the air containing nitrogen as the main component after separating oxygen to fix the carbon dioxide in the coal bed, and the coal is pressed by the function of the injected gas. It is characterized by suppressing the release of carbon dioxide to the atmosphere by collecting the layered methane to the ground and supplying it as fuel for the gas turbine.

Further, the gas turbine equipment of the present invention comprises an oxygen production apparatus for extracting oxygen from air, a gas turbine provided with a methane oxycombustor for supplying oxygen extracted by the oxygen production apparatus to burn methane, An exhaust gas condenser that separates carbon dioxide from the combustion gas of the gas turbine, a gas compressor that pressurizes the carbon dioxide separated by the exhaust gas condenser and the nitrogen gas generated by the oxygen generator, and a pressure pipe and coal that feed the gas to the underground coal bed. It is characterized by having a recovery pipe for recovering methane from the layer. Then, the pressurized gas produced by the gas compressor is pressed into the coal bed from the pressure feed pipe and the methane gas pushed out is collected from the collection pipe, and the collected methane gas is supplied to the oxycombustor to suppress the external emission of exhaust gas. To do.

It is known that the underground coal bed has an adsorbing ability and is fixed in the coal bed when carbon dioxide gas is injected. On the other hand, regardless of the quality of the coal, the coal bed contains a large amount of coal bed gas containing methane as a main component, and when carbon dioxide gas is injected into the coal bed, it flows in the bed, so it is located at an appropriate position. A recovery pipe can be installed to collect methane gas on the ground. This recovered methane is used as fuel for the gas turbine.

If gas containing oxygen gas is injected under pressure, methane will burn underground, which is dangerous, and combustible components in the recovered gas will decrease, making it unusable as fuel. Therefore, when carbon dioxide is used as a pressurizing gas, it is necessary to add a non-combustible gas if the amount of gas is insufficient, but if oxygen is removed and non-combustible gas such as nitrogen is added, the combustion will be increased. I don't have to worry. Moreover, when coal bed gas is collected by injecting carbon dioxide gas, it can be collected over a long period of time, but the total amount of collection is not large enough. On the other hand, it is possible to recover by pressing nitrogen gas, but in this case, a large amount of coal bed gas is released in the initial stage, but it is not released immediately and a sufficient amount cannot be recovered.

However, if the proportion of nitrogen gas is increased initially and the proportion of carbon dioxide gas is gradually increased over time, a relatively large amount of coal bed gas can be obtained from a relatively initial state. It was found that the production amount did not decrease so much over time, and the final total recovery amount was, for example, about 5 times as large as that in the case of carbon dioxide gas alone. Therefore, when oxygen is separated from the carbon dioxide gas generated from the gas turbine equipment and air with increased nitrogen content is mixed and injected into the underground coal seam, the composition ratio of nitrogen gas is increased at the beginning of operation. Then, it is preferable to secure the recovery amount of the coal bed gas by decreasing the ratio of nitrogen gas with time.

In the gas turbine equipment of the present invention, methane gas recovered from the underground coal bed is used as a fuel, oxygen separated from the air is burned in the combustor as a combustion improver, and carbon dioxide generated in the combustor is separated from the air. It was pressed into the underground coal bed together with the nitrogen gas and fixed in the coal bed.
Therefore, almost all of the generated carbon dioxide gas can be fixed in the ground so as not to be released into the atmosphere. Moreover, since the air and carbon dioxide gas after extracting oxygen are used to recover the coal-bed methane, there is no waste.

The gas turbine equipment of the present invention may be one in which the rotating shaft of the gas turbine is connected to a generator. In addition, a waste heat recovery boiler may be provided in the combustion gas discharge pipe of the gas turbine, a steam turbine generator may be provided, and steam produced by the waste heat recovery boiler may be supplied to the steam turbine generator to generate electricity. Good. These power generation facilities with generators connected to gas turbines and steam turbines can fix almost all of the carbon dioxide generated by the combustion of fuel in the underground coal seam. It does not release carbon dioxide to the atmosphere and cause environmental pollution or global warming.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to examples. FIG. 1 is a block diagram showing an embodiment of a gas turbine facility of the present invention, FIG. 2 is a graph for explaining a change over time in the amount of coal bed gas recovery with injection gas as a parameter, and FIG.
[Fig. 4] is a material balance diagram of a plant to which this embodiment is applied. The gas turbine equipment shown in FIG. 1 comprises a gas turbine equipment 1, a steam turbine equipment 2, an oxygen production equipment 3, and a carbon dioxide gas / coal bed gas treatment equipment.

The gas turbine system 1 comprises a compressor 11, a methane oxygen combustor 12, a gas turbine 13 and a gas turbine generator 14. The compressor 11, the gas turbine 13, and the gas turbine generator 14 are coaxially connected to each other, and the turbine 13
The power of rotation is used to generate electricity and distribute it to customers. In the methane oxycombustor 12, the coal bed gas containing oxygen gas and methane as main components is directly sprayed and burned, and the combustion gas is guided to and driven by the gas turbine 13. The exhaust gas from the turbine 13 contains a large amount of carbon dioxide and water generated by the combustion of coal layer gas.

An exhaust gas condenser 15 is provided in the exhaust pipe of the gas turbine 13, the exhaust gas is guided to the exhaust gas condenser 15 to collect condensed water, and the carbon dioxide gas and the dilution gas which are not condensed are returned to the compressor 11. . At this time, excess gas that is not circulated and used in the gas turbine device 1 is sent to the gas compression module 4 as recovered gas. The recovered gas is obtained by removing water from the exhaust gas and contains the same amount of carbon dioxide as newly generated in the gas turbine.

Further, a waste heat recovery boiler 21 is provided in the exhaust pipe of the gas turbine, and steam is generated by the heat of the recovered exhaust gas to generate electricity by the steam turbine device 2 and supply it to customers. The waste heat recovery boiler 21 is the water supply pump 2
The water supplied in 8 is heated by the exhaust gas and sent to the steam turbine generator 22. A generator 23 is attached to the steam turbine 22. The steam whose pressure has been reduced in the steam turbine 22 becomes water in the condenser 24, passes through the condensate pump 25, the feed water heater 26, and the deaerator 27, and is supplied to the waste heat recovery boiler 21 by the feed water pump 28. The water becomes high temperature steam again and drives the steam turbine 22 to produce electricity by the generator 23 and distribute it to consumers.

The gas turbine equipment is equipped with an oxygen production device 3
Is attached. The oxygen production device 3 is a device that separates oxygen from air, and cools air, for example, to separate oxygen from the difference in boiling points. The oxygen produced by the oxygen producing apparatus 3 is sent to the methane oxygen combustor 12, and the air component containing nitrogen as a main component after extracting the oxygen is sent to the gas compression module 4.

The carbon dioxide gas / coal bed gas treatment facility is
It consists of a gas compression module 4, a pressure feed pipe 5, and a recovery pipe 6. The gas compression module 4 pressurizes air components other than oxygen and carbon dioxide together and sends them to the pressure feeding pipe 5 that reaches the underground coal layer 7, and from the opening formed at the position of the coal layer 7 of the pressure feeding pipe 5 to the coal layer 7. Press into 7.

A coal bed 7 is provided at a position appropriately separated from the pressure pipe 5.
There is provided a recovery pipe 6 reaching Coal bed 7 in recovery pipe 6
An opening is provided at a position corresponding to. The coal layer 7 contains a large amount of coal layer gas containing methane as a main component, and the coal layer gas flowing into the recovery pipe 6 can be recovered on the ground. When the pressure of the coal bed gas is insufficient, the force of the suction device provided on the ground may be used to collect the gas to the ground.

When a gas containing carbon dioxide and nitrogen is pressed into the coal bed 7, the coal bed gas is pushed by the so-called gas pushing action and gathers in the direction of the recovery pipe 6 where the pressure becomes lower than the surroundings. Therefore, by providing the recovery pipe 6 at an appropriate position and injecting the recovered gas or the like under pressure, the coal bed gas containing methane as a main component can be efficiently recovered on the ground. This coal layer gas is supplied to the methane oxyfuel combustor 12 and used as fuel for the gas turbine.

The coal bed gas recovery rate changes depending on the composition of the gas to be injected. FIG. 2 is a graph conceptually illustrating how the amount of coal bed gas recovered changes depending on the composition, taking the horizontal axis as time. When only carbon dioxide gas is used, the recovery amount of coal gas gradually increases and eventually becomes almost constant recovery amount, and this state is maintained for a long time. On the other hand, when only nitrogen gas is used, the amount of recovery increases rapidly at first, but then the amount of recovery rapidly decreases.

However, when a gas in which nitrogen gas and carbon dioxide gas are appropriately mixed is used, not only the total amount of coal bed gas that can be recovered remarkably increases, but also the composition ratio of nitrogen gas and carbon dioxide gas is temporally changed. Control, and increase the ratio of nitrogen gas first and gradually decrease the ratio to reach a certain amount of recovery relatively early and increase the amount of recovery, and the total amount of recovery is only carbon dioxide gas. It has been found that it is about five times as large as that in the above case. Therefore, also in the gas turbine equipment of the present embodiment, it is preferable to provide a composition adjusting means for the press-fitted gas so that the component ratio of nitrogen gas and carbon dioxide gas can be optimally changed over time.

It should be noted that if a gas containing oxygen gas is injected under pressure, methane burns underground and is dangerous, and the combustible components in the recovered gas decrease, making it unusable as fuel. Therefore, when carbon dioxide is used as the pressurizing gas, it is necessary to add an incombustible gas if the amount of gas is insufficient, but as in the present embodiment, it is preferable to use air in which an incombustible gas such as nitrogen is left after removing oxygen. If so, there is no concern that coal bed gas will burn underground.

Further, since the underground coal seam 7 has an adsorption capacity, the carbon dioxide gas injected is fixed in the coal seam without returning to the ground. Therefore, when the gas turbine equipment of this embodiment is used, carbon dioxide It does not need to be released into the atmosphere. In addition, the method of burning methane with oxygen is preferable because it does not contain NOX in the exhaust gas, unlike the case of burning with air containing nitrogen, and thus the degree of pollution of the environment is small.
It should be noted that the coal bed gas is not necessarily generated in a large amount in a good quality coal bed, and can be recovered even in a low quality coal bed such as a deteriorated coal bed or peat that has already been commercially mined, so that the gas turbine equipment of the present invention Can also be used as a means of regenerating and utilizing the coal field.

Next, an example of material balance when the present invention is applied to a power plant having a nominal output of 7 MW is shown in FIG.
Shown in. The target power generation facility is 16.69 × 10 ⁶ kc
It is equipped with a gas turbine power generator having an output of 5670 kW at an air temperature of 15 ° C and a steam turbine power generator having a capacity of 2300 kW using air having a flow rate of 21.5 kg / sec using natural gas of al / hr as a fuel. . The total output is 7980 kW.

When coal bed gas in which methane gas accounts for 100% is used, the coal bed gas is 1950 m ³ /
hr need. Oxygen gas must be supplied at least 3900 m ³ / hr in order to completely burn this coal bed gas. In addition, the gas turbine power generator is
Although it is operating in a supercharged state by supplying air containing twice as much oxygen gas, since the efficiency can be improved by using pure oxygen, in FIG. A value that does not consider loss is used. The amount of water generated by combustion is 3136 kg / hr, and the flow rate of steam for driving the steam turbine is 1 from the heat balance.
It is calculated as 1300 kg / hr.

The power required to separate oxygen from air is 0.33 kW per m ³ of oxygen, so 3900
It consumes 1288 kW to produce m ³ / hr of oxygen. In addition to this, the power consumed in the facility is about 4
Since it is estimated to be 00 kW, the electric power that can be supplied to the outside can be calculated as 5490 kW. The nitrogen gas produced at the same time is 15600 m ³ / hr, and the required air is 27
It will be 870 m ³ / hr. The carbon dioxide gas generated by combustion will be 1950 m ³ / hr, and if the operating rate is assumed to be 80%, it will reach 7273 T a year, but this amount will be fixed in the coal bed.

It should be noted that the use of gas mixed with nitrogen gas and carbon dioxide gas will increase the methane production amount about 5 times. Therefore, in order to obtain 1950 m ³ / hr of coal bed gas, for example, the Hokkaido Sorachi Branch Office It can be presumed that the number of methane recovery wells in the Akabira Coal Mine could be increased to 6 to solve this problem. This system does not release carbon dioxide gas into the atmosphere because the total amount of carbon dioxide gas generated in the facility is pressed into the coal bed together with nitrogen gas and fixed, and coal bed gas recovered from the coal bed by gas injection. After all, power generation of about 5,500 kW can be supplied to the outside. The power generation efficiency is 28.2%, and the power supply capacity is 38.4 × 10 ⁶ kWh per year.

[0030]

EFFECTS OF THE INVENTION When power is generated by the gas turbine equipment of the present invention, carbon dioxide generated in the gas turbine is used for pumping coal bed gas by pumping it to the underground coal bed and fixing it in the coal bed. , It is possible to prevent carbon dioxide gas from being released into the atmosphere and causing environmental damage. Further, since the methane gas recovered from the underground coal seam can be used as the fuel for the gas turbine, the fuel production and the exhaust gas treatment can be constructed as a closed system.

[Brief description of drawings]

FIG. 1 is a block diagram of a gas turbine facility according to an embodiment of the present invention.

FIG. 2 is a graph illustrating a change over time in the amount of coal bed gas recovered.

FIG. 3 is a drawing showing an example of a material balance of a plant to which this embodiment is applied.

[Explanation of symbols]

1 gas turbine equipment 11 compressor 12 Methane oxygen combustor 13 gas turbine 14 gas turbine generator 15 Exhaust gas condenser 2 Steam turbine equipment 21 Exhaust heat recovery boiler 22 Steam turbine 23 Steam turbine generator 24 condenser 25 Condensate pump 26 Water heater 27 Deaerator 28 Water pump 3 oxygen production equipment 4 Gas compression module 5 pressure pipe 6 collection tubes 7 coal bed

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Paul Sims             Australia 2113 Sydney, North Rye             De Julius Avenue (no street number)             Riverside Corporate Parkco             Monwells of science en             De Industrial Research

Claims (5)

[Claims] 1. An oxyfuel gas turbine is driven by a combustion gas obtained by burning methane gas recovered from a coal bed with oxygen separated from air, and carbon dioxide discharged from the gas turbine is separated from oxygen. Carbon dioxide is injected into the coal bed together with air containing nitrogen as a main component to fix the carbon dioxide in the coal bed, and by promoting the recovery of methane gas from the coal bed and supplying the gas turbine with carbon dioxide, Gas turbine equipment characterized by a closed system that suppresses atmospheric release of air. 2. An oxygen combustion type gas turbine equipped with an oxygen production apparatus for extracting oxygen from air, and a methane oxycombustor for supplying oxygen extracted by the oxygen production apparatus to burn methane, and a gas turbine of the gas turbine. An exhaust gas condenser for separating carbon dioxide from a combustion gas, a gas compressor for pressurizing the carbon dioxide separated by the exhaust gas condenser and nitrogen gas generated in the oxygen generator, a pressure pipe and a coal bed for feeding gas to an underground coal bed A recovery pipe for recovering methane from the gas compressor is used to recover the methane gas extruded by pressurizing the pressurized gas produced by the gas compressor from the pressure-feeding pipe into the coal bed, and recovering the recovered methane gas from the oxygen combustion. A gas turbine facility characterized by suppressing the release of carbon dioxide gas to the outside atmosphere by supplying it to the reactor. 3. The gas turbine equipment according to claim 1, wherein the rotating shaft of the gas turbine is connected to a generator to produce electricity. 4. A waste heat recovery boiler is further provided in a combustion gas discharge pipe of the gas turbine, a steam turbine generator is provided, and steam produced by the waste heat recovery boiler is supplied to the steam turbine generator. The gas turbine equipment according to claim 3, which generates electric power. 5. The amount of coal bed gas recovered is increased by increasing the nitrogen gas component at the start of the operation of the composition of the gas fed into the coal bed and increasing the carbon dioxide gas component over time. The gas turbine equipment according to any one of claims 1 to 4.