JPS59218335A - Fuel feed controller of gas turbine - Google Patents

Abstract

PURPOSE:To enable fuel of gas turbine to be switched in a short time, by a method wherein a switch valve is controlled by means of a control valve opening instruction having a different value according to properties of two types of gas fuel, and the secondary pressure of a fuel control valve is balanced with a pressure in a burner. CONSTITUTION:Since the heating value of LNG is different form that of LPG, a minimum fuel instruction signal 16 is sent to gain converters 40 and 41, and thereafter, it is sent to each of fuel valve position control circuits 18-1 and 18-2 . The constant of the gain converter 42 takes the form of the characteristic ratio of each fuel, and during switching, the sum of input signals is equal to the out put signal of a low value preference circuit l7. The secondary side of a fuel control valve 15-2 is brought to a negative pressure as against a pressure in a burner 4 thanks to a spray effect. Thus, a differential pressure detector 45 detects a differential pressure between a secondary pressure and a discharge pressure, and generates bias until the difference enables feed of the fuel to a burner. This permits the one fuel system to be switched to the other in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gaseous fuel supply control device in a gas turbine power generation facility having one system of gaseous fuel.

[Technical background of the invention]

Conventionally, liquid fuels such as diesel oil and kerosene are often used as fuel for gas turbines, but with advances in energy resource transportation technology, liquefied natural gas (LNG) is now being used.
Gas turbines that burn exclusively with LNG or co-fire with LNG/liquid fuel are coming into use. Furthermore, in recent years, the proportion of gaseous fuels in the energy resource consumption ratio has increased, so there is a growing tendency to use only gaseous fuels, and the number of types of gaseous fuels has increased. The number of gas turbine installations using various types of gaseous fuels is increasing. In order to stabilize the power supply from the gas turbine, the system uses two types of gaseous fuel systems (for example, LNG and LPG), so that if an abnormality occurs in one fuel system, it can be easily switched to the other system in a short time. It is desired to realize a system that can Further, similar requirements exist when two systems of supply equipment for the same type of gaseous fuel are prepared and used alternately. The present invention seeks to meet this need.

The following is an example of a conventional fuel supply system and control device that has a column fuel supply facility, and is connected to a gas turbine l.
After the air 2 enters the compressor 3 and is pressurized, it is transferred to the combustor, where it burns the gaseous fuel 6 sent from the fuel line j, converts it into high-temperature gas 7, and then burns it in the gas turbine r. The exhaust gas is sent to the atmosphere, an exhaust gas recovery boiler (not shown), etc. as an exhaust gas generator. A compressor 3 and a generator 10 are directly connected on one axis to the gas turbine t, forming a power generation system.

The gas turbine control device 1/ is equipped with a startup control circuit l, a speed load control circuit 13, and a temperature control circuit /μ.

The output signals of these three control circuits selected by the low value priority circuit /7 are the minimum fuel command signal /A, which is sent to the fuel valve position control circuit /g. This control circuit 1 controls the fuel control valve/3.

The startup control circuit is used when starting the gas turbine, and is a circuit that sequentially generates the fuel valve opening request signal 20, 2/ necessary for the ignition signal, warm-up, and acceleration of the gas turbine. Therefore, closed loop control is not performed. The speed load control circuit 13 compares the rotational speed of the gas turbine with a speed setting signal force and performs closed-loop control to set the rotational speed to a predetermined rotational speed. After the output of the gas turbine generator, the speed setting signal force becomes the load setting signal. The temperature control circuit 1att detects the gas turbine exhaust temperature J and limits the fuel request signal so that the exhaust temperature does not exceed a set value Δ.

In the fuel valve position control circuit 7g, the fuel control valve IS is opened to a valve opening degree corresponding to the minimum fuel command signal lO. The valve position is
υ'' is returned to the position detector Δ, and position control is performed by this closed loop.

On the other hand, the fuel stop valve shuts off the fuel in the event of an emergency for the gas turbine, and also sets the fuel gas pressure 27 on the upstream side of the fuel control valve is to a value corresponding to the rotation speed n, improving the controllability of the fuel control valve. is being measured. To accomplish this, the fuel stop valve control circuit U calculates a valve opening command, the valve position is returned to the valve position detector 29, and position control is performed in a closed loop.

[Problems with background technology]

In the conventional single-fuel gas turbine control device as described above, control constants and the like are determined by the characteristics (particularly the calorific value) of the gaseous fuel. Therefore, when operating a gas turbine with a different gaseous fuel, it is necessary to change not only the control constants but also the hard components such as fuel stop valves, control valves, and combustion nozzles. Therefore, the downtime of the gas turbine is considerable.

[Purpose of the invention]

An object of the present invention is to provide a fuel supply control device for a gas turbine that allows switching between fuel systems to be performed easily and in a short period of time.

[Summary of the invention]

The fuel supply control device of the present invention includes a circuit that generates a fuel switching signal in response to a saturation signal of a position control circuit of a fuel stop valve in each system, and a signal that continuously changes with time based on this fuel switching signal. A switching function generator that generates a switching function generator, a circuit that generates fuel control valve opening commands with different values depending on the characteristics of the different types of gaseous fuel, and a circuit that generates fuel control valve opening commands with different values depending on the characteristics of the different types of gaseous fuel, and balances the fuel control valve secondary pressure with the combustor internal pressure at the time of switching. and a circuit for generating a bias for controlling the switching function generator, and determining an operation signal for the fuel control valve of each system based on the output signal of the switching function generator, the fuel control valve opening command, and the bias. It is something.

[Embodiments of the invention]

Figure 2 shows a gas turbine power generation facility with a λ system gas fuel supply system.
It is possible to switch PG.

Components similar to those in FIG. 1 are designated with the same reference numerals or -11-2. In Figure 2, fuel is supplied to the LNG system j-/ and the LPG system! - It is made from two systems of λ, and a gaseous fuel stop valve is installed in each line! -/, g-co, gaseous fuel control valve/! ;-1°1s-x are provided, through which fuel is delivered to the combustor≠ by separate nozzles. When operating with one fuel line, the fuel stop valve and fuel control valve of the other line are in a fully closed state. In addition, since LNG and LPG have different calorific values per unit weight, the size of the fuel stop valve, valve lift, and combustion nozzle diameter must be different for both systems, and the constants of the control device must also be different. .

FIG. 3 shows a control device used to control the power generation equipment shown in FIG. 2.

The activation control circuit 12 is configured such that a valve opening request signal for LNGXLPGλ type fuel can be set using a setting device /9.20X2/, and for example, a potentiometer 30 driven by an electric motor is driven by a fuel switching signal 3t. , LNG side, L
It is possible to change the setting value on the PG side.

Since the calorific value of LNG and LPG is different, the minimum fuel command signal /6 is determined by the gain converter 410. tiic (each having constants α and β) are sent to the LNG fuel valve position control circuit 1tr-/ and the LPG valve position control circuit 1tr-2. More specifically, the output signal of the gain converter OG is multiplied by the output of the fuel switching function generator 3 by the multiplier 3/, and the output signal is passed through the adder 3 to I,
The signal is sent to the NG fuel valve position control circuit 1t-7, and is also sent to the adder 33 via the gain converter 'A2.

The constant of the gain converter Hiro2 is a value β/ determined by the ratio of the characteristics of LNG fuel (especially calorific value) and the characteristics of LPG fuel.
It is α. The three fuel switching function generators generate three fuel switching signals.
It receives q and continuously generates analog signals from KO to l over time, and there is no manual input to the valve position control circuits lza-1 and lg-2 before, during and after switching. The sum of the signals is equal to the output signal of the low value priority circuit 17.

For example, considering the case of LNG operation, the W force signal from the three fuel switching function generators is! Therefore, the input signal to the LPG valve position control circuit/za-2 is O. Also, during switching, the output signal of the function generator 32 is set to 0. ≠, If the output signal of the low value priority circuit 17 is a 100% signal, the human input signal to the LNG valve position control circuit /g-/ is ll-0αchi, 9, LPG valve position control circuit 1tr-, The human signal to z becomes AOlchi.

At the start of fuel switching, for example, when switching from LNG to fiLPG, λ of the fuel control valve is-λ of the LNG fuel line
The next line t-2 has a negative pressure with respect to the internal pressure of the combustor due to the atomizing effect. Therefore, in order to send LPG fuel to the combustor at the time of switching, it is necessary to use a certain amount of LPG fuel.
It is necessary to open the fuel control valve/3. This is LP
The same applies when switching to G fuel and LNG fuel. However, in the circuit described so far, it is possible to use fiLPG instead of LNG fuel.
When switching to fuel is started, the amount of change in fuel opening until the pressure A-1 on the next side of the gas fuel control valve becomes higher than the internal pressure of the combustor has no effect on the load. Therefore, when switching, L
Even if the NG fuel control valve 15-/ is throttled and the LPG fuel control valve is-,2 opens accordingly, there is no load increase, so
Overall, this results in a load reduction.

Bias circuit! -/, case-1 is to correct this, and the differential pressure detector 'As -/, 'A3- detects the fuel control valve secondary pressure and the compressor discharge pressure, and this differential pressure A bias is generated to open the fuel control valve to a value that allows fuel to be delivered to the combustor.

In the case of LPG fuel switching, the bias circuit is activated by the switching command signal 37, and when the differential pressure reaches a predetermined value, the bias is fixed, and switching is then started.

At the time of completion of switching, the bias circuit of the LNG bias circuit is no longer fixed in bias, and the output signal of the bias circuit stop becomes zero. Switching from LPG to LNG is performed in a similar manner.

Figure 1 shows the fuel control valve /! when switching from LNG to LPG. ;-/,! ! −1 and bias circuit rod−/
, shows the change in the output signal of case-j, and time A.
is the start of switching, and time B is the end of switching.

The fuel switching signal 31A is generated based on a manual switching command signal 33' by an operator or an automatic switching command signal 37. The automatic switching command signal 37 causes the fuel control valve 1 to switch when an abnormality occurs in the fuel system in use and the fuel pressure decreases.
．． If the pressure 27 on the upstream side of 3 does not satisfy the specified value, the fuel stop valve 26 is fully opened, and the fuel stop valve position control circuit 2
1: is saturated and is therefore generated when this is detected by the voltage comparator 36.

When the fuel switching based on the fuel switching signal 3ψ is completed, a fully closed bias signal 3g is sent to each of the fuel stop valve position control circuits u1 and fuel control valve position control circuits l of the unused fuel systems.
, 39 are in contact, and the fuel stop valve 1 and the fuel control valve 3, which are applied through the valve, are kept fully open, completely shutting off the unused fuel system. Furthermore, at the start of switching, the above-mentioned contact does not operate, and therefore the fully closed bias signal is released.However, since the manual signal of the unused side fuel control valve position control circuit is zero, the fully closed state is maintained. It will be done. On the other hand, the unused side fuel stop valve 13 starts operating to control the fuel pressure on the upstream side of the fuel control valve roller because the fully closed bias signal is released. This is illustrated in Figure 5.

The figure shows switching from LNG to LPG.
The horizontal axis is the time axis, and when the switching start command is issued at time A, the fully closed bias signal 3 of each position control circuit/g-21, 11-λ of the fuel stop valve and control valve of the LPG fuel system is issued.
9-2.3g-1 is canceled.

At time B when the switching from the LNG fuel system to the LPG fuel system is completed, a fully closed bias signal 39-/, 3g-7 is applied.

〔Effect of the invention〕

As described above, according to the present invention, in a fuel supply facility configured with λ fuel systems, the fuel systems can be switched manually or automatically (that is, without causing load fluctuations) and quickly. can be done.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional gas turbine fuel supply system and its control device, Fig. 2 is a diagram showing a fuel supply system consisting of one system, and Fig. 3 is a diagram showing an embodiment of the control device according to the present invention. The block diagram, FIGS. 1 and 5 are time charts showing changes in the respective signals and states at the time of fuel system switching. 3...Compressor, G...Combustor, ♂...Gas turbine, ll...Gas turbine flail '0i4
1 device, lS... fuel control valve, 7g... fuel control valve position 1tiIJ control circuit, easy... fuel stop valve, d.
... Fuel stop valve position control circuit, 3/... Multiplier, 3... Fuel switching function generator, Di... Fuel switching signal,
36... comparator, 3. g, 39... Valve fully closed bias signal. Applicant's agent Kiyoshi Inomata

Claims (1)

[Scope of Claims] (1) In a fuel supply control device for a gas turbine power generation facility that has two gaseous fuel supply systems and each system is provided with a fuel stop valve and a fuel control valve, a fuel stop valve for each system is provided. a circuit that generates a fuel switching signal in response to the saturation signal of the position control circuit; a fuel switching function generator that generates a signal that continuously changes over time based on the fuel switching signal; A starting control circuit that generates a fuel control valve opening command with a different value depending on the characteristics, and a fuel lI'4i
ff! An operation signal for the fuel control valve of each system is determined based on a bias for balancing the I control valve secondary side pressure with the combustor internal pressure, the output signal of the switching function generator, and the fuel control valve opening command. A gas turbine fuel supply control device comprising λ fuel control valve position control circuits. (2. In the device according to claim 7, the fuel control valve opening command is given to one of the fuel control valve position control circuits via a gain converter having a first constant α, and , is applied to the other fuel control valve position control circuit via a gain converter having a second constant β different from the first constant. (3) Claim 1: 2. The device according to claim 1, wherein the human power of at least one fuel control valve position control circuit is determined based on the product of the fuel control valve opening command and the output of the switching function generator.