JPS6140432A - Fuel control device in gas turbine - Google Patents

Abstract

PURPOSE:To restrain variations in output power of a turbine caused by variations in fuel heating value, by detecting the heating value of fuel to compensate a fuel control signal. CONSTITUTION:A gas concentration detector 16 is provided in a fuel sstem for a burner. If a gas in a mine shaft is used as a fuel, the concentration of the gas which is proportional to the heating value of fuel, is detected to compensate a fuel control signal set in accordance with a design fuel heating value with the use of a divider 14. With this arrangement, even if the heating value varies, it is possible to prevent the output power of a turbine from varying.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a control device for a gas turbine, and particularly to a fuel control device when using fuel whose calorific value fluctuates.

[Background of the invention]

Figure 2 shows an example of the equipment configuration of a gas turbine power plant.
Air compressed by the compressor 1 is heated by the combustor 2 and becomes a high-temperature gas. The thermal energy possessed by this gas is converted into work by the turbine 3, and 9! The electric machine 4 is driven to generate electric power. 9! The generated power is transmitted to the grid 6 via the circuit breaker 5.

The fuel regulating valve 7 controls the amount of fuel flowing into the combustor based on the output signal of the fuel control device 8.

FIG. 3 shows a block diagram of the fuel control device. The fuel control system for a gas turbine is broadly divided into a startup control system 9, a speed/load control system IO1, an acceleration control system 11, and a temperature control system 12.

The startup control system 9 controls the fuel flow rate according to a startup program determined when starting the gas turbine, and starts the gas turbine up to the rated speed.

The speed/load control system controls speed and load after the gas turbine reaches rated speed.

The acceleration control system 11 controls the turbine acceleration at startup.

Control so that the specified value does not occur.

The temperature control system 12 is provided to manage the life of the high temperature section of the gas turbine, and controls the temperature change rate so that it does not exceed a predetermined value at startup, and controls the combustion temperature to a predetermined value during load operation. Control so that the value is not exceeded.

The signal selection gate 13 selects an optimal signal from the control signals according to the operating state of the turbine.

As an example that describes the above-mentioned control system in detail, see US Pat.
There is No. 20133.

In the fuel control device having such a configuration, the fuel control icon controls the fuel flow rate, and selection of the fuel regulating valve and setting of the control system are performed based on the calorific value of the fuel.

However, for example, when underground gas from a coal mine is used as fuel, the concentration of the fuel gas, that is, the calorific value, changes significantly. Since the regulating valve and control system are set with only one calorific value, changes in gas concentration cause load fluctuations. In other words, as shown in Figure 4, fuel! ! l! Since the I valve controls the fuel flow rate F, a difference in gas concentration causes a difference in turbine heat input, and the load changes. That is, QH indicates the turbine heat input when the gas temperature is high, and QL indicates the turbine heat input when the gas concentration is low.

[Object of the Invention] An object of the present invention is to provide a gas turbine fuel control device that does not cause a load change even if the calorific value of the fuel changes.

[Summary of the invention]

The key point of the present invention is to detect the calorific value of fuel and correct the fuel control signal.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG.

The heat input to the turbine is: Turbine heat input = Fuel flow rate x Fuel calorific value... (1) Here, the fuel flow rate required to take a certain load is:
Select a fuel adjustment valve that can flow a fuel flow rate that can handle the rated load when the 1 calorific value is the lowest, and the fuel control signal is the calorific value at the design point and the change in the calorific value set by the fuel flow rate. You can fix it with.

In the case of underground gas from a coal mine, the calorific value is proportional to the gas concentration, so it is sufficient to calculate the gas concentration [16].

In FIG. 1, the divider 14 corrects the fuel control signal set by the design calorific value by dividing it by the fuel calorific value fi (gas concentration), as shown in equation (2).

The fuel adjustment valve 7 is controlled by the servo valve driver 15 using this corrected signal.

〔Effect of the invention〕

According to the present invention, it is possible to prevent a change in turbine output due to a change in calorific value.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is an overall configuration diagram of a gas turbine power plant, Fig. 3 is a block diagram of a gas turbine fuel control table, and Fig. 4 is a diagram showing gas turbine concentration and turbine FIG. 3 is an explanatory diagram showing the relationship of heat input. 7... Fuel adjustment valve, 14... Divider, 15... Servo valve driver, 16... Gas concentration detector.

Claims (1)

[Claims] 1. A gas turbine fuel control device characterized in that a means for detecting the calorific value of fuel is provided in the fuel system, and a fuel control signal is continuously corrected based on the calorific value.