JPH0472048B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water-injected gas turbine cycle, in which air or a gas mainly composed of air is compressed by a compressor, and part or all of the compressed air is heated using a heat recovery medium in advance. The air/steam mixture obtained by contacting the liquid phase water is used to recover heat from the turbine exhaust gas, and the cooled liquid phase water obtained by the contact operation is used as a heat recovery medium to perform intermediate cooling of the compressor and the above-mentioned It is characterized by being used only for cooling compressed air used in contact operations, and in a preferred embodiment, the cooling rate is 48% at a turbine input temperature of 1000°C.
It is a gas turbine cycle that can achieve thermal efficiency higher than (fuel natural gas, LHV standard).

The present inventor has proposed that in a gas turbine cycle in which heat recovery is performed from the Durbin exhaust air with an air/steam mixture obtained by contacting part or all of the compressed air with liquid water, the compressed air and the heated heat recovery medium are used as a heat recovery medium. A mixture of air/steam is obtained by contacting the liquid phase water obtained in the contact operation, and the cooled liquid phase water obtained in the contact operation is used as a heat recovery medium to cool the compressed air used in the contact operation and to recover heat from the turbine exhaust gas. We have discovered that large thermal efficiency can be achieved by using it for intermediate cooling of compressors as needed.
A patent application was filed earlier (Japanese Patent Application No. 199364-1983). The thermal efficiency according to this patent is 3-4% higher than that obtained with a combined gas turbine-steam turbine cycle under comparable operating conditions.

The patents have considered clean natural gas, liquefied natural gas, easily volatile liquid fuel, etc. that contain no or very low sulfur content as fuel.

Therefore, there was no need to consider low-temperature corrosion such as sulfuric acid corrosion caused by gas turbine exhaust gas, and the exhaust gas temperature was extremely low at around 80°C.

Subsequently, we continued to consider the configuration of the gas turbine cycle, taking into account the type and properties of the fuel, and found that the gas turbine blades and nozzles would not suffer from high-temperature corrosion, and that the sulfur oxides in the gas turbine exhaust gas would not exceed regulatory values. Due to this restriction, it was found that fuel can be put to practical use if the amount of sulfur contained in the fuel is approximately 0.8wt% or less. The acid dew point of the waste gas at this time is approximately 130, depending on the water vapor and oxygen content of the waste gas.
It is ℃.

Therefore, the low-temperature side heat recovery device and chimney for the gas turbine exhaust gas shown in the gas turbine cycle of the above-mentioned patent must take special consideration against acid corrosion, typified by sulfuric acid corrosion. Current technologies for heat exchangers include using expensive non-metallic materials such as corrosion-resistant metals and glass as tube materials, or lining inexpensive steel tubes with corrosion-resistant materials, but in any case, the burden of equipment costs is low. Inevitable.

Therefore, even in a cycle like the present invention, which does not add a low-temperature side heat recovery device for gas turbine exhaust gas and generates waste gas with a temperature higher than the acid dew point, the thermal efficiency does not decrease compared to the above patent.
It can be kept to around 1.5%. The thermal efficiency of this cycle is still 1.5% higher than that of the above-mentioned combined cycle, and is higher than that of the combined cycle in which the fuel contains sulfur and the waste gas has a temperature higher than the acid dew point as in the present invention.
More than 2.5% higher.

That is, the present invention uses a fuel containing sulfur as a fuel, and uses a compressor to compress air or a gas mainly composed of air, which is used as a combustion support gas, a working medium gas, etc., to produce some or all of the compressed air. In a gas turbine cycle, heat is recovered from turbine exhaust gas using an air/steam mixture obtained by contacting liquid phase water with air/steam. At the same time, the cooled liquid phase water obtained in the contact operation is used as a heat recovery medium only for cooling the compressed air used in the contact operation and for intermediate cooling of the compressor, and is subjected to the contact operation with the compressed air. , and a liquid phase that is subjected to the contact operation and the heat recovery operation, using as necessary a heat recovery medium of liquid phase water corresponding to the amount of liquid phase water that is evaporated in the contact operation and transferred into the compressed air as a mixture with air. This is a gas turbine cycle that is refueled underwater.

Hereinafter, an example of a flow sheet of the present invention will be explained with reference to the accompanying drawings.

The drawing shows a contact exchange tower (hereinafter referred to as an exchange tower) 1 that brings compressed air and liquid water into contact, a heat recovery section, and a heat exchanger used for cooling the compressed air used in the contact operation (hereinafter referred to as a self-heat exchanger). ) 1, intercooler 1,
This is the case of the air compressor 2 and the turbine 1.

In the drawing, atmospheric air 3 taken into air compressor AC ₁ is adiabatically compressed and sent to intercooler IC via pipe 4.
It is cooled by liquid phase water 17 consisting of the liquid phase water in the pipe 24 from the exchange tower EXT and the make-up liquid phase water from the pressurized water introduction pipe 2.
It is adiabatically compressed again at AC ₂ and becomes compressed air 6. A part of the compressed air 6 is guided to the high-temperature side heat recovery unit R ₁ through a pipe 8 as required, and the remaining part enters the self-heat exchanger SR through a pipe 7 and is cooled, and then introduced through a pipe 9 to an exchange tower EXT. Liquid phase water heated as a heat recovery medium in the self-heat exchanger SR and intercooler IC, respectively, is introduced into the exchange tower EXT through pipes 19 and 18, where the compressed air and the liquid phase water are combined. is introduced into the high-temperature side heat recovery device R ₁ through a pipe 10 as a compressed air/steam mixture with an increased partial pressure of water vapor through countercurrent direct contact. In addition, the liquid phase water cooled by the contact operation is sent from the pipe 20 to the self-heat exchanger SR and the intercooler IC via the tubes 23 and 24, where the heat is recovered and becomes heated liquid phase water to the exchange tower.
Returned to EXT. The compressed air/steam mixture introduced into the high-temperature side heat recovery device R ₁ undergoes heat recovery together with the compressed air introduced directly from the air compressor AC ₂ from the air compressor AC 2 to the combustor 8 through the pipe 11 as needed.
Introduced to CC. The fuel 1 whose heat has been recovered in the heat recovery device R ₂ is introduced into the combustor CC through a pipe 21, and becomes combustion gas at a predetermined temperature and is introduced into the turbine ET through the pipe 12. The combustion gas expands adiabatically in the turbine ET, and is discharged from the pipe 13 that generates the driving force for the air compressors AC ₁ , AC ₂ and the load L, and a portion is sent to the fuel heat recovery device R ₂ from the pipe 22. The remainder is 1
4, the heat is recovered by the higher temperature side heat recovery device _R1 , and the heat is recovered by the pipe 15.
It is discharged outside the cycle as waste gas 16 through. In addition, air compressors AC ₁ , AC ₂ and turbine
Seal air introduced into the ET and cooling air introduced into the turbine ET are of course required separately due to the design of the machine. However, in the process of operation of the present invention, because low-temperature compressed air is obtained, the required amount of compressed air for turbine cooling can be reduced compared to conventional gas turbine cycles, and this effect results in further improvements in thermal efficiency. This contributes to improvement.

An example of the flow of the present invention has been shown above with reference to the drawings, but the present invention cools the compressed air used in the contact operation with liquid phase water obtained by contacting part or all of the compressed air with liquid phase water. This method only performs intermediate cooling of the compressor, and various changes can be made as long as this operation is used. For example, there are methods such as using fuel for intercooling and reheating cycles, and the relationship between compression ratio and thermal efficiency shows that even at high compression ratios, the rate of decrease in thermal efficiency is smaller than in conventional gas turbine cycles. It has a unique feature and has great benefits when used for high specific output or reheat cycle.

Although the basic flow of the gas turbine cycle of the present invention and an example of its application have been shown above, from the point of view of operating conditions, heat and mass (water) transfer through direct contact between compressed air and liquid water is more efficient. As for the range that can be advantageously used, first of all, the amount of compressed air used in the contact operation is usually preferably used in full from the perspective of heat recovery rate, but the amount of compressed air used in the contact operation is preferably used in the contact operation used in self-heat exchangers, intercooling, etc. The flow is diverted to the high-temperature side heat recovery device as appropriate based on the desired amount of cooled liquid phase water, the practical conditions of the contact operation, the size of the equipment used, etc. Also, the amount of water that is evaporated by contact with compressed air and transferred into the compressed air as a mixture of compressed air/steam is selected in accordance with the implementation.

This suitable operating range naturally changes depending on the use of fuel for intercooling, the use of a reheat cycle, or the conditions at the turbine inlet. For example, in the flow sheet shown in Figure 1,
Under the turbine inlet conditions of 6at pressure and 1000℃ temperature, the amount of water transferred into the compressed air as a compressed air/steam mixture is per 1 kgmol of total intake air.
It ranges from 0.06 to 0.12 Kgmol, preferably from 0.07 to 0.11 Kgmol. In addition, in a compressor, the pressure distribution before and after stages when performing intercooling should be determined from the viewpoint of increasing the compression power reduction effect due to intercooling.

Below, a study example will be shown to more specifically explain the effects of the present invention.

Study example () Conditions (a) Efficiency Compressor adiabatic efficiency η _C =0.89 Turbine adiabatic efficiency η _T =0.91 Mechanical efficiency η _n =0.99 Generator efficiency η _G =0.985 Combustion efficiency η _B =0.999 (b) Air intake condition temperature Temperature 15℃ Pressure 1.033at Humidity 60% Flow rate Dry Air 1Kgmol/s H ₂ O 0.0101Kgmol/s (c) Fuel type Natural gas Temperature 15℃ Higher calorific value (0℃) 245200Kcal/Kgmol Lower calorific value (0℃) 221600Kcal/Kgmol (d) Total pressure loss rate 0.149 (e) Make-up water temperature 15℃ Flow rate 0.091Kgmol/s (f) Turbine inlet condition pressure 6at Temperature 1000℃ (g) Heat exchanger minimum temperature Differential high temperature side heat recovery device R ₁ 30℃ Fuel preheater R ₂ 30℃ Intercooler IC 20℃ Self-heat exchanger SR 20℃ (h) Others Compression power of fuel, make-up water and exchange tower bottom water is ignored. , 0.3% of the generating end output was considered as the in-house power. In addition, the required amount of turbine cooling air was set taking into consideration that low-temperature compressed air can be obtained in this cycle.

() Results (a) Waste gas temperature 138.5℃ Flow rate 1.11Kgmol/s (b) Compressor AC ₂ outlet temperature 150℃ (c) Sending end output 8090KW (d) Sending end thermal efficiency 48.6%

[Brief explanation of the drawing]

The drawing is a flow sheet showing an example of the present invention. 2 is a pressurized water introduction pipe, 3 is atmospheric air, 6 is compressed air, 7, 8, 9, 10, 18, 19, 20, 2
3 and 24 are tubes, R ₁ is a high temperature side heat recovery device, R ₂ is a heat recovery device, IC is an intercooler, SR is a self-heat exchanger,
EXT is an exchange tower, AC ₁ and AC ₂ are air compressors, CC is a combustor, ET is a turbine, and L is a load.

Claims (1)

[Claims] 1. Liquid phase water is added to part or all of the compressed air obtained by using fuel containing sulfur as fuel and compressing air or air-based gas used as combustion support gas, working medium gas, etc. using a compressor. In a gas turbine cycle in which heat recovery from the turbine exhaust is performed using an air/steam mixture obtained through contact,
Compressed air and heated liquid water used as a heat recovery medium are contacted to obtain an air/steam mixture, and the cooled liquid water obtained in the contacting operation is used as a heat recovery medium in the contacting operation. It is used only for cooling compressed air and intermediate cooling of the compressor, and is subjected to a contact operation with the compressed air, and as necessary, the amount of liquid phase water that evaporates during the contact operation and transfers into the compressed air as a mixture with air. A gas turbine cycle in which liquid phase water is used as a heat recovery medium and is supplied to the contact operation and the heat recovery operation.