JPH10317992A - Preventing device for load fluctuation at time of changeover of fuel of gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a gas turbine from dropping in load by fuel fluctuation caused at the time of changeover of the fuel of the gas turbine from gas to oil. SOLUTION: The oil from an oil fuel feed system 21 flows into manifolds 22-1 and 22-2 after the regulation by valves B1 and B2 and then into a combustor 30. The gas from a gas fuel feed system 31 flows into the combustion 30 after the control by a valve B3. A controller 1 is used for controlling the valve B3 to gradually reduce the gas flow rate to a predetermined value and for at the same time controlling the valves B1 and B2 to gradually increase the oil flow rate, so that the fuel is switched over from gas to oil. Although such a switchover includes a period where the oil flow rate shows no increase during the oil charge to the manifolds 22-1 and 22-2 in spite of a decrease in the gas flow rate, the controller 1 controls the valve B3 to hold the gas flow rate not lowering but constant during that period and thus compensate for such a fuel lack.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing load fluctuation at the time of gas turbine fuel switching and, more particularly, to preventing load fluctuation at the time of switching fuel from gas fuel to oil fuel.

[0002]

2. Description of the Related Art FIG. 4 is a fuel system diagram of a conventional gas turbine, in which gas fuel is supplied to a combustor 30 from a gas fuel supply system 31 through a valve (B3).
On the other hand, oil fuel is supplied from the oil fuel supply system 21 through the No. 1 valve (B1), and oil fuel is supplied from the No. 2 valve (B2) to the manifolds 22-1 and 22-2, respectively.
Fuel is distributed from each of the manifolds 22-1 and 22-2 to the combustor 30.

The valves (B1), (B2), and (B3) are controlled by the control device 10 as described later, and gradually reduce the gas fuel of the gas turbine that is operating on the gas fuel at the time of fuel switching. Then, the oil fuel is increased and finally switched to the oil fuel.

FIG. 5 is a diagram showing a flow rate control at the time of fuel switching performed by the conventional control device 10. In the figure, fuel switching is performed between times t _{0 and} t ₆ , and first the valve (B1) is switched. Is opened to supply oil fuel, and then the valve (B
Open 2) and supply oil fuel. At t ₀ , the NO. First valve (B1) is opened and held at t ₁ to a predetermined opening. t ₁ filling period of oil ~t between ₂ manifold 22-1, a period of t ₂ ~t ₃ decreases the amount gas, the period of increasing the oil, the t ₃ NO. 2
Open the valve (B2), a valve in t ₄ (B2)
Hold the opening of. t ₄ between the ~t ₅ the manifold 22
Filling period -2, duration of t ₅ ~t ₆ decreases the amount of gas,
A period for increasing the oil, fully mode changes in t ₆ from the gas fuel to the oil fuel.

[0005] The control device 10 refers to the load signal, and
Valve (B1) in accordance with the command value C of the oil flow rate indicated by the gas flow and the dotted line shown in, (B2), but controls the (B3), the actual oil flow rate D of the combustor 30 is between t ₀ ~t ₁ in reduces the gas flow rate as shown by P _1, no flow of oil to the combustor 30 is between the initial pipe filling. t _{1 to} t ₂ is a period during which the manifold 22-1 is filled with oil. During this period, load fluctuation is suppressed by keeping the fuel ratio constant, and the gas flow rate is constant and the oil flow rate command value C is constant. The actual oil flow rate D to the combustor 30 is zero because the manifold 22-1 is filled with oil.

During the period from t _{2 to} t ₃ , the filling of the manifold 22-1 is completed, the gas flow rate is reduced at a predetermined ratio, and the amount of oil is increased accordingly. At t ₃ to open the valve (B2), t
₄ , the gas flow rate is maintained at P ₂
As shown by, the oil command value C continues to decrease and the oil flows to the manifold 22-2 despite the increase command, so that after B1 is fully opened, the oil flow to the combustor 30 becomes constant. t ₄ is the filling period ~t ₅ in manifold 22-2, during which holds the fuel ratio signal constant, since suppressing the load fluctuation becomes gas flow rate, and the oil flow both constant.
filling of t ₅ ~t ₆ in the manifold 22-2 is completed,
Gas flow rate decreases, the oil flow rate is increased, the gas flow rate in t ₆ is completely mode changes to zero, and the fuel oil.

[0007]

As described above, when the fuel of a conventional gas turbine is switched from gas fuel to oil fuel, the gas fuel is gradually reduced and the oil fuel is gradually increased. Finally, the gas fuel is set to zero and switched to the oil fuel. At this time, while the oil fuel is being filled into the manifolds 22-1 and 22-2, the actual oil flow rate entering the combustor 30 does not reach the set value, and the load is reduced. In the current control, the fuel ratio is kept constant without changing because it causes fluctuation. This state will be described with reference to FIG. 5. Between t ₁ and t ₂ , the valve (B 1) has a predetermined opening degree and the oil fuel is supplied to the manifold 2.
A period which is filled to 2-1, between the the fuel ratio is constant, also kept constant at Similarly t ₃ ~t _4, thereby suppressing variation of the load.

During the oil filling period of the manifold described above, the gas flow rate is reduced as indicated by P _{1 from} t _{0 to} t ₁ , and the command value C of the oil flow rate is increased by Q _1. And the oil flow does not increase as indicated by Q ₁ ′.
Also, t ₃ ~t ₄ In the same manner as the gas flow rate decreases as shown by P _2, the oil flow rate despite increased command as indicated by Q _2, the oil flow rate is not changed as indicated by Q ' Not increase. Therefore, only gas fuel decreases during these
The oil flow does not change. For this reason, the amount of fuel supplied to the combustor 30 decreases with respect to the load, which causes a load change.

Accordingly, the present invention corrects in the gas fuel supply system the amount corresponding to the fuel that is not injected into the combustor during the period of filling the manifold with oil fuel when switching the fuel of the gas turbine from gas fuel to oil fuel. A first object of the present invention is to provide an apparatus for preventing load fluctuation at the time of fuel switching of a gas turbine, which can suppress a load reduction caused by fuel fluctuation in this period.
It was done as an issue.

Further, as a second problem, the above-mentioned load fluctuation preventing device can be applied to a fuel supply system of a gas turbine having an oil fuel supply system for starting and operating a load in the oil fuel supply system. Is to do.

[0011]

The present invention provides the following (1) and (2) in order to solve the first and second problems.
Means are provided.

(1) A fuel supply system and a gas fuel supply system are provided. The gas fuel supply system is connected to a combustor via a flow control valve, and the oil fuel supply system is connected to a combustor via a flow control valve and a manifold. A gas turbine load change prevention device for controlling the flow rate control valve to switch from gas fuel to oil fuel by gradually decreasing gas fuel and gradually increasing oil fuel under the control of a control device; The gas fuel supply is performed such that the flow rate control valve of the oil fuel supply system is opened and the flow rate of the gas fuel is kept constant without decreasing the flow rate of the gas fuel for a predetermined time from when the filling of the oil fuel into the manifold is started. A load fluctuation prevention device at the time of gas turbine fuel switching, characterized by controlling a flow control valve of a system.

(2) In the above (1), the oil fuel supply system has a flow path for supplying the oil fuel at the time of starting and a flow path for supplying the oil fuel at the time of the load operation. A load fluctuation preventing device at the time of gas turbine fuel switching, comprising a valve and a manifold.

In (1) of the present invention, the flow rate control valves of the oil fuel supply system and the gas fuel supply system are controlled by the control device, and the gas fuel is gradually supplied according to the actual load based on a predetermined command value. At the same time, the oil fuel is gradually increased, and the fuel is switched from the gas fuel to the oil fuel. At the time of this switching, when the flow rate control valve of the oil fuel supply system is opened and the filling of the oil fuel into the manifold is started, the gas flow rate was conventionally reduced, but during this period, the oil fuel is stored in the manifold. Since the filling is started, the actual oil flow rate is zero. Accordingly, during this period, the oil fuel does not increase despite the decrease in the gas fuel, and the fuel becomes insufficient for the load.

In (1) of the present invention, the control device controls the flow control valve of the gas fuel supply system during this period,
The gas fuel is kept constant without reducing the gas flow rate, and the shortage of the fuel is corrected by suppressing the gas flow rate so as not to decrease. As a result, it is possible to suppress a decrease in load due to fuel fluctuations during this period.

In (2) of the present invention, the oil fuel supply system is composed of two systems. First, the control device opens the flow control valve on the startup side to increase the oil flow while decreasing the gas flow. After a predetermined time, the flow control valve on the load operation side is opened and the same control is performed to switch from gas fuel to oil fuel. In this case as well, the control device opens the flow control valve on the start-up side to start filling the manifold with oil fuel, as in (1), and opens the flow control valve on the load operation side to fill the manifold with oil. At the start of fuel filling, the flow rate control valves of the gas fuel supply system are controlled so that the flow rates are kept constant without decreasing the gas flow rate for a predetermined time.

In (2) of the present invention, the shortage of fuel is controlled so that the flow rate of gaseous fuel does not decrease as described above. At the start of the opening operation of the flow control valve on the load operation side, control is performed so as to suppress a decrease in the gas flow rate, so that a decrease in the load at the time of fuel switching can be prevented as in (1).

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a fuel system diagram of a load fluctuation prevention device at the time of gas turbine fuel switching according to one embodiment of the present invention. In the figure, a characteristic part of the present invention resides in the control device 1, and the fuel system is the same as the conventional one. The valves (B1), (B2), and (B3) are controlled by a control pattern shown in FIG. This is to correct a shortage of fuel caused by the oil fuel filling period of the manifolds 22-1 and 22-2, thereby preventing the load from decreasing.
Hereinafter, features of the present invention will be described in detail.

FIG. 2 shows a pattern of controlling the gas flow rate of the load fluctuation prevention device at the time of fuel switching of the gas turbine according to one embodiment of the present invention.
Indicates a conventional one. In the figure, time t _0-
In t _1, has been conventionally reduced gas flow, the gas flow rate in the present invention is constant.

The period from t _{0 to} t _{1 is} a period from when the No. 1 valve (B1) of the oil fuel supply system is opened until a predetermined opening degree is maintained, as described in the conventional example. value despite increasing command as indicated by Q ₁ in FIG. 5, the actual oil flow has become zero so starts filling the manifold 22-1 as indicated by Q ₁ '. Therefore, the fuel for the combustor 30 is insufficient correspondingly.
₀ between ~t ₁ was constant as A shown to t ₂ without reducing the gas flow rate, and supplement this partial gas fuel,
This is to prevent the load from decreasing.

Further, at t ₃ , the valve (B 2) of the oil fuel supply system is opened, and at t ₄ , the opening degree is maintained at a predetermined degree. Conventionally, the gas flow rate was reduced during this period. Then, it is controlled to be constant.

Although the command value of the oil flow during the period from t _{3 to} t ₄ is an increase command as shown by Q ₂ in FIG. 5, the actual oil flow is the manifold 22-2 as shown by Q ₂ ′. It is constant since the filling is started. Thus the fuel to the combustor 30 will be insufficient by that amount, where the period of t ₃ ~t ₄ in the present invention was constant until t ₅ as A shown without reducing the gas flow rate, the amount It supplements with gaseous fuel to prevent a decrease in load.

FIG. 3 is a block diagram of the inside of the control device 1 in the embodiment described above. In the figure, reference numeral 10 denotes a fuel ratio setting signal, which sets each fuel ratio setting signal of a gas flow rate and an oil flow rate. 11 is an actual load signal of the gas turbine combustor. Reference numeral 12-1 denotes a multiplier for obtaining a flow rate command of a gas to be controlled by multiplying an actual load signal 11 by a gas flow rate in the fuel ratio setting signal 10.

[0024] 13-1 is a correction with setting circuit, intended to provide a set obtained by adding a gas amount to be corrected between t ₀ ~t ₁ and t ₃ ~t ₄ shown in FIG. 2, the correction amount and its timing Is set in advance. Reference numeral 14 is a setting circuit, the period of the gas flow rate of motion of up to t ₀ ~t ₆ shown in FIG. 5 which is set in advance, i.e. such that the motion of B shown in FIG. 2, the oil flow rate during this period Output the control command value. Reference numeral 15 denotes a valve drive signal generation circuit that outputs a signal for controlling the No. 3 valve (B3) based on the corrected gas flow rate. The valve drive signal generation circuit 15 changes the valve No. 3 (B3) to the gas flow rate shown in FIG. Control. A switch 16 selects the output of the correction setting circuit 13-1 only when switching from oil fuel to gas fuel.

A multiplier 12-2 multiplies the oil flow amount of the fuel ratio setting signal 10 by the actual load signal 11 to obtain an oil flow to be controlled. 13-2 is a setting circuit,
The control command value of the oil flow rate during this period is output so that the oil flow rate during the period from t ₀ to t ₃ shown in FIG. 5 is set in advance. Reference numeral 18 denotes a valve drive signal generation circuit, which is a No. 1 valve (B1) based on the control command value.
To control the supply of oil fuel.

[0026] is likewise 13-3 also setting circuit, so that the t ₃ when shown in Fig. 5 which is set in advance with an oil flow rate of movement of the period until t ₆ outputs a control command value of the oil flow rate during this period I do. Reference numeral 19 denotes a valve drive signal generation circuit, which is a high pressure side No. 2 (B
2) to control the supply of oil fuel.

As described above, when the fuel of the gas turbine is switched, the control device 1 controls the fuel ratio setting signal 10.
Oil fuel based on the actual load signal 11
Control the valve (B1) to increase gradually, then
The valve (B2) is controlled to increase, and accordingly, the gas flow rate is gradually reduced by controlling the No. 3 valve (B3), and the fuel is switched from gas to oil fuel.

In the above switching process, although the gas flow rate is reduced, the manifold 22-
The oil flow rate does not increase during the filling of the oil at 1,22-2, and as a result, the fuel to the combustor 30 becomes insufficient by this amount, and the load decreases. Therefore, in the embodiment of the present invention, the gas flow rate of the gas fuel supply system is controlled by the valve (B3) by the control device 1. The method is shown in FIG. The value is corrected.

According to the above-described embodiment, when the fuel of the gas turbine is switched from gas to oil fuel, the gas flow rate is reduced while filling the manifold with oil.
The oil flow did not change, and the load decreased during this time.
A correction circuit 13-1 and a switch 16 are provided in the control device 1,
Since the change in the gas flow rate is kept constant while the oil flow rate does not change, and the fuel is corrected based on the gas flow rate, load fluctuation during fuel switching is suppressed, and stable switching is performed.

[0030]

According to the present invention, (1) has an oil fuel supply system and a gas fuel supply system. The gas fuel supply system has a flow control valve, and the oil fuel supply system has a flow control valve and a manifold. The two flow rate control valves are controlled by a control device to gradually reduce gas fuel and gradually increase oil fuel to switch from gas fuel to oil fuel, thereby preventing load fluctuation of a gas turbine. An apparatus, wherein the control device keeps the flow rate constant without decreasing the flow rate of gas fuel for a predetermined time from the time when the flow rate control valve of the oil fuel supply system is opened to start filling the manifold with oil fuel. It is characterized in that the flow rate control valve of the gas fuel supply system is controlled so as to maintain the flow rate. With such a configuration, a decrease in load at the time of switching from gas fuel to oil fuel is suppressed, and fuel switching of the gas turbine can be performed stably.

According to a second aspect of the present invention, in the first aspect of the present invention, the oil fuel supply system includes a flow path for supplying the oil fuel at the time of starting and a flow path for supplying the oil fuel during the load operation. Has,
Each is characterized by having a flow control valve and a manifold. With such a configuration, even when the oil fuel supply system has two systems, that is, a start-up side and a load operation side, it is possible to prevent the load from being reduced at the time of fuel switching as in the case of (1).

[Brief description of the drawings]

FIG. 1 is a fuel control system diagram of a load fluctuation prevention device at the time of gas turbine fuel switching according to an embodiment of the present invention.

FIG. 2 is a diagram showing a gas flow rate of the load fluctuation prevention device at the time of gas turbine fuel switching and a conventional gas flow rate according to one embodiment of the present invention.

FIG. 3 is a block diagram of the inside of a control device of the load fluctuation prevention device at the time of gas turbine fuel switching according to one embodiment of the present invention.

FIG. 4 is a fuel control system diagram at the time of conventional gas turbine fuel switching.

FIG. 5 is a diagram showing a gas flow rate and an oil flow rate at the time of conventional gas turbine fuel switching.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 control device 10 fuel ratio setting signal 11 load signal 12-1, 12-2 multiplier 13-1, 13-2, 13-3 setting circuit 14 setting circuit 15, 18, 19 valve drive signal generation circuit 21 oil fuel supply System 22-1, 22-2, 32 Manifold 30 Combustor 31 Gas fuel supply system

Claims (2)

[Claims] An oil fuel supply system and a gas fuel supply system are connected to a combustor via a flow control valve, and the oil fuel supply system is connected to a combustor via a flow control valve and a manifold. A gas turbine load change prevention device for controlling the flow rate control valve to switch from gas fuel to oil fuel by gradually decreasing gas fuel and gradually increasing oil fuel under the control of a control device; The gas fuel supply is performed such that the flow rate control valve of the oil fuel supply system is opened and the flow rate of the gas fuel is kept constant without decreasing the flow rate of the gas fuel for a predetermined time from when the filling of the oil fuel into the manifold is started. A load fluctuation prevention device at the time of gas turbine fuel switching, characterized by controlling a flow control valve of a system. 2. The oil fuel supply system has a flow path for supplying oil fuel during startup and a flow path for supplying oil fuel during load operation, and has a flow control valve and a manifold, respectively. 2. The load fluctuation prevention device according to claim 1, wherein the gas turbine fuel is switched.