JP2000054856A - External heating type gas turbine power generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external heating type gas turbine power system in which the number of heat exchangers can be decreased, heat can be efficiently recovered by a simple device structure and efficient power generation can be performed. SOLUTION: In this external heating type as turbine power system in which an external heater 2 heating compressed air 4 from a gas turbine compressor 5 by a refuse batch throwing gasification combustion type incinerator 1 is arranged in an open cycle gas turbine, exhaust gas 9 such that gas turbine exhaust gas 8 is mixed with incinerator exhaust gas 3 is used as the heat source of the external heater 2, a steam boiler 12 that exhaust gas by which the external heater 2 is heated is used as a heat source is arranged on the rear stream side of the external heater 2, and a whole or a part of amount of steam from the steam boiler 12 is mixed with gas turbine compressed air 4 and heated in the external heater 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an externally heated gas turbine power generation system, and more particularly to an externally heated micro gas turbine power generation system for exchanging heat between high-temperature combustion gas and air in a small incinerator.

[0002]

2. Description of the Related Art The purpose of an externally heated gas turbine is to reduce the amount of fuel used in an internal combustor by heating the compression outlet air with the combustion exhaust gas of a solid fuel such as coal or wood. As an implementation example of an externally heated gas turbine,
The combustion gas of the pulverized coal burner at 1200 ° C
It has been demonstrated that air can be heated to 0 ° C. to operate a 500 kW gas turbine. This project is
A subsidiary project of the US Department of Energy, which aims to increase the efficiency of existing coal-fired boiler / steam turbine systems of 100,000 kW or less. The external heater for the gas turbine in this project uses a ceramic shell-and-tube heat exchanger.

The exhaust gas of an externally heated gas turbine is generally used as combustion air for solid fuel combustion, and serves as preheated air for a combustion furnace. After the flue gas of the combustion furnace is subjected to heat exchange in a steam boiler, an exhaust gas treatment device is installed for removing soot, sulfur oxides, nitrogen oxides, and the like.
On the other hand, a small gas turbine generator has been developed for a hybrid vehicle that uses both electricity and fuel, and has an output of 50%.
Commercialization of a gas turbine generator of about kW is possible. Such a small-sized gas turbine is called a micro gas turbine, and is expected to be a cogeneration prime mover with a remarkably small number of parts, one-tenth or less of a gas engine and a low maintenance cost, as compared with a gas engine. Since the micro gas turbine has a pressure ratio of about 4 and a turbine inlet temperature of 1000 ° C., if an inexpensive external heater can be obtained, biomass such as wood chips can be effectively used as a heat source.

A small gasification combustion type incinerator which is separated so that vinyl chloride which causes dioxin is not mixed is supplied with secondary air to the fuel gas generated in the gasification chamber, and the combustion gas temperature is set to 800 ° C. Can hold more than smoke,
It is a small incinerator that generates very little soot and dioxin, and is equipped with an external fuel burner such as kerosene to keep the exhaust gas temperature high even when the incinerator starts and stops. Conventionally, in the incinerator having a refuse incineration capacity of less than 200 kg / h, hot water is generally recovered, and there is no method of inexpensively converting it into electric power. Small incinerators employ a batch type in which refuse is injected at once, and boiler / steam turbine types used in large continuous incinerators are not implemented in terms of power generation efficiency and availability. Did not.

[0005] In a small incinerator, a batch system in which refuse is supplied at once is generally used, and the amount of gas from a gasification chamber is not constant from start to stop. The secondary combustion chamber of the small gasification combustion type incinerator is charged with secondary air and clean fuel such as kerosene, complete combustion, and has a combustion temperature of 800 ° C.
As described above, the exhaust gas amount fluctuates from the start to the stop. On the other hand, when the gas turbine generator is a single-shaft gas turbine in which a compressor, a turbine, and a generator are on the same shaft, the amount of exhaust gas from the gas turbine is almost constant, which requires a gasification combustion type incinerator. Does not match air volume. That is, it is difficult to use gas turbine exhaust gas as combustion air of a batch type incinerator in which refuse is injected at once. Exhaust gas from large gas turbines is recovered by steam using an exhaust heat recovery boiler and combined power generation is performed by a steam turbine generator to increase the amount of power generation. However, from the viewpoint of economy, the gas turbine output is less than 10,000 kW. Then
Few examples have been implemented.

A regenerator that heats compressor outlet air using exhaust gas from a gas turbine as an external heating source can reduce the amount of air heating by the gas turbine internal combustor and reduce the amount of external fuel used. When a regenerator is used, the compressed air temperature is heated by the regenerator, so the inlet air temperature to the external heater also increases, and if the outlet air temperature does not change, the heat exchange capacity of the external heater decreases. I do.
The outlet temperature of the external heater is determined by the allowable temperature of the heat exchange material. In the case of a metal tube, the air temperature is preferably 750 ° C. or less. The heat exchanger required for the combination of a gas turbine and a small incinerator is a gas turbine regenerator used for heating compressed air, an external heater for the incinerator exhaust gas, and a gas turbine exhaust gas for recovering the remaining exhaust heat with hot water. A total of four types of hot water heat exchangers and incinerator exhaust gas hot water heat exchangers are required. The reason why the hot water heat exchanger is used is that the gas turbine exhaust gas temperature by the regenerator is 50 ° C to 1 ° C lower than the compressor outlet air temperature.
This is because the temperature is about 300 ° C. which is about 00 ° C. higher than the exhaust gas temperature level of a gas engine or a diesel engine, the exhaust gas outlet temperature does not decrease in steam recovery, and the amount of exhaust heat recovery is smaller than that in hot water recovery.

[0007]

DISCLOSURE OF THE INVENTION In view of the above prior art, the present invention reduces the number of heat exchangers, efficiently recovers heat with a simple apparatus configuration, and efficiently generates power. It is an object of the present invention to provide an externally heated gas turbine power generation system using exhaust gas from a coal incinerator.

[0008]

According to the present invention, there is provided an external heater for heating compressed air from a gas turbine compressor using exhaust gas from a refuse lump-type gasification combustion type incinerator. In an externally heated gas turbine power generation system provided in an open cycle gas turbine, an exhaust gas obtained by mixing a gas turbine exhaust gas with an incinerator exhaust gas is used as a heat source of the external heater. Further, in the gas turbine power generation system of the present invention, on the downstream side of the external heater, a steam boiler that uses exhaust gas heated by the external heater as a heat source is provided, and all or a part of the steam from the steam boiler is provided. It can be mixed with gas turbine compressed air and heated in the external heater.

[0009]

Next, the present invention will be described in detail.
The present invention mixes gas turbine exhaust gas with incinerator exhaust gas and performs air heating and steam heat recovery with the mixed exhaust gas. Small-scale gasification combustion type incinerators separate and introduce refuse that does not generate hydrogen chloride, so gas treatment for removing hydrogen chloride is unnecessary. Since dust removal is performed in the cyclone at the incinerator outlet, the exhaust gas is discharged at a high temperature. The exhaust gas temperature of the incinerator ranges from 800 ° C. to 1200 ° C. The exhaust gas temperature is kept constant by controlling the amount of external fuel such as kerosene from the start to the end of combustion.

The exhaust gas temperature of a micro gas turbine is 70
When the gas turbine exhaust gas amount and the incinerator exhaust gas amount are approximately the same, the exhaust gas temperature after mixing is 750 ° C.
To 950 ° C. In the regenerator, the amount of exhaust gas and the amount of compressed air are almost the same, but since the amount of mixed exhaust gas is twice the amount of compressed air, the exhaust gas outlet temperature of the external heater is higher than the exhaust gas outlet temperature of the regenerator. When the temperature of the mixed exhaust gas is 950 ° C., the temperature of the exhaust gas at the inlet of the exhaust heat recovery heat exchanger installed on the downstream side of the external heater rises to 675 ° C., which is a temperature at which economical steam recovery is possible.

When the steam of the steam recovery boiler on the downstream side of the external heater is mixed with the compressed air and guided to the external heater, the specific heat of the steam is larger than that of the air. Be larger. When the mixed gas of air and steam is heated to 1000 ° C. by the gas turbine internal combustor, the output of the gas turbine is higher than that of air alone. Although it has been practiced to inject steam into the gas turbine combustor chamber to increase the gas turbine output, the micro gas turbine has a rotation speed of 100,000 rpm or more and the combustor chamber is very small, so the steam is It is difficult to attach a nozzle for injection.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. However, this embodiment is one example, and the present invention is not limited thereto. Embodiment 1 FIG. 1 shows a schematic configuration diagram of a gas turbine power generation system according to the present invention. In FIG. 1, 1 is a lump-type gasification combustion incinerator, 2 is a high-temperature heater, and 3 is combustion exhaust gas from the incinerator. 4 is air for a gas turbine, 5 is a compressor,
6 is a generator and 7 is a turbine. The compressor 5, the gas turbine 7, and the generator 6 are connected to the same shaft and have a speed of 1.5 t / h.
Air 4 is compressed by a compressor 5 at a pressure of 0.4 MPa · ab.
s, compression heated to 230 ° C. Incinerator exhaust gas 3
Is an exhaust gas amount of 1.4 t / h and an exhaust gas temperature of 1200 ° C. The heat input of the separated waste is 521 kWth. The compressed air is mixed with steam 14 generated from a steam boiler 12 on the downstream side of the high-temperature heater 2 via a steam injection valve 15, and is guided to the high-temperature heater 2 as a mixed gas of air and steam, and is supplied to a gas turbine. The mixture is heated to 750 ° C. by the exhaust gas 9 obtained by mixing the exhaust gas 8 and the incinerator exhaust gas 3. A bypass damper 16 is provided between the high-temperature heater 2 and the incinerator 1, and enables the operation of the incinerator after the gas turbine is started first and starts power generation independently.

For the tube of the high-temperature heater, heat-resistant steel having a material allowable temperature of 1000 ° C. or less and a chromium content of about 25% is used. Since the heater outlet temperature is set as low as 750 ° C., the heat transfer area can be reduced, and an inexpensive metal tube can be used instead of expensive ceramics. In addition, since it is a combustion gas of separated garbage that does not contain vinyl chloride, there is no danger of high temperature corrosion of metal tubes due to hydrogen chloride. The inlet temperature of the gas turbine is 1000 ° C. of the uncooled metal turbine, and the mixed gas 9
750 ° C., an external fuel 11 (kerosene or the like) is charged into the internal combustor 10 and heated to 1000 ° C.
To drive the compressor 5 and the generator 6.

Assuming that the power generation output of the simple open cycle gas turbine without the high temperature heater 2 is 45 kW and the power generation efficiency is 12%, the required heat input of the gas turbine is 375 kWth. In the externally heated gas turbine according to the present embodiment, the temperature is 230 ° C. to 7 ° C.
Since it is externally heated to 50 ° C., the internal combustor 10
Fuel consumption is reduced by 66% and heat input of external fuel is reduced by 13%.
2 kWth. When the steam injection rate is 0.3 t / h, the total flow rate of the air 11 and the steam entering the internal combustor 10 is 1.8 t / h, which is 20% of 1.5 t / h of the air alone.
Will increase. The turbine output is 135 kW when the air alone is used, and if the flow rate is increased to 20% increase to 162 kW, the required power of the compressor is 90 kW and the same, and the power generation output is 72 kW compared to 45 kW without steam injection. And the power generation output increases by about 60%. By mixing with the steam, the heat input of the external fuel increases to 187 kW.

If the ratio of the heat input 187 kWth of the external fuel excluding the heat input to the external heater and the power generation 72 kW is defined as the external fuel power generation efficiency, the power generation efficiency is 38.5%. Since the power generation efficiency of large state-of-the-art simple open cycle gas turbines, diesel engines, and fuel cells is about 40%, the micro gas turbine has been used to effectively utilize the unused energy of waste. Assuming that the pressure of the steam generated by the steam boiler 12 is 0.9 MPa · abs in which the steam can be used as a heat source of the double effect absorption refrigerator 17, the coefficient of performance of the refrigerator becomes 1.2, and the hot water single effect absorption refrigerator is used. Coefficient of performance of 0.
The chilled water output 18 is increased by 50% or more as compared with 7. In gas turbine cogeneration, heat is often used for air conditioning, electricity demand fluctuates yearly, heat demand is less than summer cooling demand in the interim period, and waste heat recovered steam is surplus In some cases, however, the present invention makes it possible to replace the surplus steam with a power generation output.

[0016]

According to the present invention, the following effects can be obtained. 1) The number of heat exchangers can be reduced and inexpensive waste cogeneration can be achieved. 2) Since the exhaust gas temperature is higher than that of a gas turbine with a regenerator, steam can be recovered, and the heat source of the double effect absorption refrigerator having a high coefficient of performance can be obtained. 3) When steam demand is low, gas turbine output can be increased by about 40% by mixing excess steam with compressor outlet air and directing it to a hot air heater. 4) The waste heat of the lump-type gasification combustion incinerator can be converted into electric power and steam at low cost, and the use of external fuel such as kerosene for the internal combustor for the gas turbine can be reduced. The ratio between the power generation output and the external fuel calorific value becomes 50% or more, which is equal to or higher than the fossil fuel use efficiency of the gas turbine combined power generation or the diesel power generation, and the use amount of the fossil fuel can be suppressed as waste heat recovery of the small incinerator.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a gas turbine power generation system of the present invention.

[Explanation of symbols]

1: lump input type gasification combustion incinerator, 2: high temperature air heater, 3: incinerator exhaust gas, 4: air for gas turbine,
5: compressor, 6: generator, 7: gas turbine, 8: gas turbine exhaust gas, 9: mixed exhaust gas, 10: internal combustor,
11: external fuel, 12: waste heat recovery boiler, 13: boiler feedwater, 14: steam, 15: steam injection valve, 16: switching damper, 17: double effect absorption refrigerator, 18: cold water,

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masayuki Nishimura 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Toshimitsu Kobayashi 11-1 Haneda Asahi-cho, Ota-ku, Tokyo EBARA CORPORATION

Claims (2)

[Claims] 1. An externally heated gas turbine power generation system comprising: an open cycle gas turbine having an external heater for heating compressed air from a gas turbine compressor using exhaust gas from a refuse lump-type gasification combustion incinerator; An externally heated gas turbine power generation system, wherein an exhaust gas obtained by mixing a gas turbine exhaust gas with the incinerator exhaust gas is used as a heat source of the external heater. 2. A steam boiler using a flue gas heated by the external heater as a heat source is provided on a downstream side of the external heater.
The externally heated gas turbine power generation system according to claim 1, wherein the whole or a part of the steam from the steam boiler is mixed with gas turbine compressed air and heated in the external heater.