JPS59176423A - Gas turbine plant system - Google Patents

Abstract

PURPOSE:To increase the effective power of a gas turbine wherein low calory gas is used as fuel by changing over fuel to supplementary fuel if gas is interrupted to be supplied for the gas turbine and making the suction side pressure of a fuel gas compressor negative so as to reduce the power of the compressor. CONSTITUTION:When supply of gas from a low calory gas supply source is interrupted, the rate at which gas flows into a combustor 3 is reduced by a fuel gas flow control valve 7 and fuel from a supplementary fuel supply installation 12a is increased, hence performing mixed fuel burning. At this time, power is consumed because a fuel gas compressor 6 makes cycling steps of suction and discharge. The suction pressure of the fuel gas compressor 6 is kept negative by a pressure control valve 13, whereby increasing the effective power of the plant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for a gas turbine plant that allows the plant to continue operating efficiently without stopping the plant when supply becomes unavailable.

FIG. 1 shows a conventional low-calorie gas-fired gas turbine plant, and its outline will be explained.

In FIG. 1, numeral 1 is an air compressor, 2 is a turbine,
3 is a combustor, 4 is a gear device, 5 is a load, 6 is a fuel gas compressor, 7 is a fuel gas flow control valve, 8 is a fuel gas tank, 9 is a cooler, 10 is a fuel gas supply main pipe, 11 1 is a power recovery turbine, and 12 is an auxiliary separation or co-combustion fuel supply facility, etc., and a low-calorie gas-fired gas turbine system has conventionally been configured with these. However, as an exception, the power recovery turbine 11 and the mixed combustion fuel supply equipment may not be provided.

The fuel gas supplied to the gas turbine is adjusted by bypassing the amount of fuel gas supplied to the gas turbine to the main pipe 10 using a control valve, depending on the load demand and the availability of the fuel gas supply source. It is something that exists.

In this case, bypassing the fuel gas compressor 6 to the main pipe 10 means that when the gas turbine is operated at a low load, the bypassed fuel gas is bypassed from the fuel gas compressor 6 to the main pipe 10.
This results in a waste of power for the gas turbine plant, which results in a decrease in thermal efficiency for the gas turbine plant. The power recovery turbine 11 is provided for the purpose of recovering this loss.

Some systems are equipped with a separate system for supplying high-calorie fuel, such as light oil, in addition to the auxiliary fuel or co-combustion fuel for low-calorie gas fuel. Here, the term "low calorie fuel" refers to, for example, blast furnace gas and other by-product gases having a fuel density of approximately 1000 KQa1/Nm3 or less.

For conventional systems not equipped with a power recovery turbine as described above, if the supply of gas fuel becomes impossible due to circumstances at the supply source, the flow of gas fuel to the gas turbine must be stopped. However, at this time, even if the amount of auxiliary fuel is increased, operation cannot be continued. The reason for this is that the working fluid of the gas turbine, the working fluid of the Kosaba gas turbine whose supply is stopped, decreases significantly, resulting in a decrease in output, but the power of the fuel gas compressor 6 hardly decreases. This is because effective output cannot be obtained. Therefore, in such a case, the plant will be forced to stop.

On the other hand, in the case where the power recovery turbine 11 is attached,
Although the above condition is improved, the equipment cost for this purpose increases. Additionally, devices equipped with the power recovery turbine 11 have the disadvantage that during steady operation, that is, when the amount of bypass from the control valve 7 is small, this device itself becomes a source of power loss. .

The present invention was devised in view of the above-mentioned drawbacks of conventional plants, and in a gas turbine that uses low-calorie gas as fuel, the gas turbine plant can be stopped even if the supply of fuel gas becomes impossible due to circumstances at the gas generation source. The purpose of this system is to ensure that operations continue efficiently without causing any damage, and if the supply of gas fuel becomes unavailable as described above, it is necessary for business establishments that have installed plants to carry out emergency operations. In many cases, the gas turbine plant can continue to operate without stopping at such times, which is of great benefit as a facility that can respond to emergencies.

The present invention is novel in the following points.

(f) If the gas turbine plant is to continue operating with the supply of gas fuel stopped, the fuel gas compressor 6 will not be consumed by the gas turbine, but will cycle between suction and discharge. However, all of this compression work becomes a loss, so in order to reduce this, a pressure control valve is installed on the suction side of the fuel gas compressor to make the gas suction pressure a negative pressure and reduce the power of the fuel gas compressor. To obtain effective output as a result.

(b) The power recovery turbine 11 connected to the fuel gas compressor 6 that has been used in the past is effective during the above-mentioned circulation operation, but the power recovery effect is low because there is little freedom in design. However, in contrast, creating a negative pressure on the suction side of the gas fuel compressor can optionally reduce power consumption and increase effective output.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

In FIG. 2, numerals 1 to 10 indicate the same parts as in FIG. 1 of the conventional example, numeral 12a is auxiliary, co-combustion and single-combustion fuel supply equipment, 13 is a fuel gas compressor suction pressure control valve, 14 is indicates steam injection equipment.

In a gas turbine plant consisting of a gas turbine, i.e., an air compressor], a load 5 (generator, blower, etc.) axially coupled to a turbine 2 and a combustor 3, and a fuel gas compressor 6, the fuel gas 8 to combustor 3
The flow rate is bypass-controlled by the control valve 7,
It is returned to the supply main pipe 10 via the cooler 9. It is equipped with auxiliary fuel supply equipment that has the capacity to co-combust auxiliary fuel (high calorie fuel, such as light oil, etc.) for combustion of low-calorie gas, and to burn it exclusively when gas fuel is not available. A suction pressure regulating valve 13 is provided on the suction side of the fuel gas compressor 6.

In the above configuration, when the gas turbine is operated with low-calorie gas fuel, if the low-calorie gas generation and supply device runs out of gas, the fuel gas flow rate control valve 7 controls the fuel gas flow rate to the combustor 3. The fuel from the auxiliary fuel supply equipment 12 is increased and the ratio of auxiliary fuel is increased while co-combustion is being carried out, and the fuel gas is shut off.

is closed to shift to auxiliary fuel exclusive combustion operation without stopping the gas turbine viverant.

At this time, the fuel gas compressor 6 is operated by the gas turbine; gas fuel is not being supplied, but the fuel gas compressor 6 is circulating from suction to discharge, and power is being consumed.

Therefore, in order to increase the efficiency of the plant, the suction pressure of the combustible gas compressor 6 is guided to negative pressure through the pressure control valve 13 in order to reduce the power of the waste gas compressor 6. With the above structure and action that increases the
The present invention has the following effects.

a) Even if the supply of low-calorie fuel gas, which is the main fuel, runs out, the gas turbine plant can continue to operate using auxiliary fuel without stopping the plant. Can increase power.

(a) Compared to increasing the effective output in the above cases using a conventional power recovery turbine, this can be done using a pressure control valve, so the cost is low. 7°, which increases maintenance and reliability.

(1) Whereas the effectiveness of a power recovery turbine decreases if it deviates from its optimal design point, it has a wide degree of freedom in application because it only adjusts the suction pressure of the fuel gas compressor.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a conventional low-calorie gas-fired gas turbine plant, and Fig. 2 is a gas turbine of the present invention. FIG. 7 is a system diagram of the seven stems of the implant. 1. Air compressor, 2. Turbine, 3. Combustor, 4
・・Gearing device, 5・・Load, 6・・Fuel gas compressor, 7
・・Fuel gas flow rate control valve, 8 ・・Fuel gas shutoff valve, 9
・・Cooler, 10・・Fuel gas supply main pipe, 12a・・Auxiliary and mixed combustion and independent combustion fuel supply equipment, 13・・
Fuel gas compressor suction pressure control valve, 14...Steam injection equipment. 1 Continuation of Figure 7, page 1 ■Applicant Nippon Steel Corporation 2-6-3 Otemachi, Chiyoda-ku, Tokyo

Claims (1)

[Claims] In a plant where the fuel gas compressor of a gas turbine that uses low-calorie gas as fuel is connected to the gas turbine by a shaft, when fuel gas is generated or the fuel gas supply from the supply source is stopped, the main fuel can be removed without stopping the plant. A fuel switching facility is installed to switch from low-calorie gas to auxiliary fuel, and the pressure on the gas suction side of the fuel gas compressor in the plant is set to negative pressure.
A gas turbine plant system characterized by reducing compressor power and recovering it as effective output to increase plant output.