JPH06288258A - Managing method of gas turbine fuel feeding temperature - Google Patents

Abstract

PURPOSE:To provide a managing method of the fuel feeding temperature in which the superheating temperature is made coincident to fuel that of a with the highest satulation temperature so as to prevent an superheating more than necessary, when fuels of different satulation temperatures are fed to an evaporator, in a gas turbine fuel feeding system having an evaporator and a superheater in order from the upstream side of the pipe system. CONSTITUTION:The temperature difference between the temperature between a superheater 2 and a combustor, and the temperature in an detected, and it is monitored whether the temperature difference is made less than a specific value or not, and a control is carried out to correspond that fluid drops are taken in to the combuster by reducing the fuel feeding temperature too much.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine fuel supply temperature control method, and more particularly to a gas turbine fuel supply system temperature control method when different types of fuel are used.

[0002]

2. Description of the Related Art FIG. 7 shows an example of a control system diagram of a fuel supply system of a conventional gas turbine. In the figure, reference numeral 1 is an evaporator, 2 is a superheater, 3 is a fuel gas control valve, 4 Indicate thermocouple thermometers.

Fuel is supplied from a fuel tank (not shown) to the evaporator 1
And is heated and vaporized there to be a gaseous fuel at a saturation temperature. This gaseous fuel is further superheated by the superheater 2 to become superheated fuel gas, passes through the fuel gas control valve 3 and enters the combustor, where it becomes combustion gas and is sent to the gas turbine.

In this normal system, in order to prevent liquid droplets from being brought into the combustor when the fuel supply temperature of the gas turbine becomes too low, the downstream side of the superheater 2 of the fuel supply system. A thermocouple thermometer 4 is provided to detect the temperature, and a protective interlock that trips the gas turbine due to a decrease in fuel supply temperature is provided.

[0005]

Generally, in a plant that handles a fuel gas having a high saturation temperature, in order to prevent droplets from being brought into the combustor when the temperature of the fuel supply to the gas turbine is lowered. A gas turbine trip protection interlock due to a drop in fuel supply temperature is provided.

However, according to the protection interlock for lowering the fuel supply temperature, in the case of a fuel containing a mixture of high saturation temperature and low saturation temperature, the temperature must be adjusted to the highest saturation temperature fuel. Instead, it will have to overheat more than necessary. This results in hindering the sizing of valves, nozzles, etc. in the design of the fuel supply system.

The present invention has been made in view of the above circumstances, and even when fuels having different saturation temperatures are supplied to the evaporator, the gas turbine fuel does not overheat the supplied fuel more than necessary. It is an object to provide a method for controlling the supply temperature.

[0008]

To solve the above problems, according to the present invention, temperature control in a gas turbine fuel supply system including an evaporator and a superheater in order from the upstream side of a pipe system is performed.
A gas turbine fuel supply temperature management method is provided, which is performed based on a temperature difference between a temperature detected between a superheater and a combustor and a temperature inside an evaporator.

[0009]

According to the above-mentioned means, the temperature condition of the gas turbine fuel supply system is relatively understood by detecting the temperature difference between the temperature between the superheater and the combustor and the temperature inside the evaporator. It That is, if the temperature difference between the two falls below a certain value, the downstream temperature of the superheater has decreased, and in the case of fuel with a high saturation temperature, it is approaching the saturation region and droplets are inside the combustor. It means that there is a concern to be brought in. Therefore, based on the detection of this temperature difference, it can be used for various management such as gas turbine trip and temperature control of the gas turbine fuel supply system.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a control system diagram showing an example of a gas turbine fuel supply system in which a method for controlling a gas turbine fuel supply temperature according to the present invention is implemented. In the figure, the same parts as those shown in FIG. 7 are designated by the same reference numerals.

According to FIG. 1, the fuel is sent from a fuel tank (not shown) to the evaporator 1 to be heated and vaporized into a gas fuel having a saturation temperature, and further superheated by the superheater 2 to the superheated fuel gas, and then the fuel. A combustor (not shown) passes through the gas control valve 3 and becomes combustion gas, which is sent to the gas turbine.

A thermocouple thermometer 4 is mounted between the downstream side of the superheater 2 and the upstream side of the fuel gas control valve 3, and a thermocouple thermometer 5 is also mounted in the evaporator 1. ing.

The measured values of the thermocouple thermometers 4 and 5 are input to the converter 6 and converted into a temperature difference signal. Converter 6
The output of is sent to a protective interlock that trips the gas turbine when the temperature difference falls below a certain value.

In this way, by detecting the temperature difference between the temperature between the superheater 2 and the combustor and the temperature inside the evaporator, the state of the fuel supply temperature, that is, the temperature difference between the two is kept below a certain value. If so, it means that the downstream temperature of the superheater 2 has decreased, and the droplets may be brought into the combustor because the fuel is approaching the saturation region depending on the type of fuel (those having a high saturation temperature). It can be understood that there is a certain situation.

Therefore, even if the mixing type of the fuel supplied to the evaporator 1 changes, if a trip set value of + α value is given (changed) for each type, droplets will be brought into the combustor. Is gone.

That is, in the past, the temperature control of the fuel supply system was controlled only by the absolute temperature of the gas on the downstream side of the superheater 2, whereas in the present invention, the gas temperature of the evaporator 1 changes depending on the type of fuel. Even so, the natural law that is the boiling point temperature of the fuel is inevitably used, and the gas temperature for preventing the gas from returning to the liquid again is managed by the gas temperature T ₁ (boiling point) + α of the evaporator 1. , The temperature difference T ₁ -T with the temperature T ₂ on the downstream side of the superheater 2.
_It is monitored whether ₂ becomes equal to or less than α, and the gas turbine is tripped when T ₂ −T ₁ ≧ α.

When the temperature difference between the temperature between the superheater 2 and the combustor and the temperature inside the evaporator 1 becomes a certain value or less, an alarm is issued before the trip to notify the operator. You may

If the temperature difference decreases below a certain value, a runback (load reduction) operation may be automatically performed to reduce the load until the specified temperature difference is reached. At this time, if the specified temperature difference is not reached, automatic stop is performed.

Further, when the temperature difference decreases below a certain value, the amount of steam input to the gas turbine (NOx reducing steam or output increasing steam) may be automatically increased and the amount of fuel input may be decreased. it can.

FIG. 2 is a control system diagram showing a second embodiment of a gas turbine fuel supply temperature control method according to the present invention. In the figure, the same parts as those shown in FIG. It is attached.

According to FIG. 2, the output of the converter 6 is
Is supplied to the steam or hot water adjusting means 7 of the steam or hot water supply system which is the heat source of the thermocouple thermometers 4, 5
If the difference in temperature measured by
The steam or hot water adjusting means 7 is controlled so as to increase the degree of superheat at 1, and the steam amount or hot water amount is increased.

FIG. 3 is a control system diagram showing a third embodiment of a gas turbine fuel supply temperature control method according to the present invention. In the figure, the same parts as those shown in FIG. It is attached.

According to FIG. 3, the output of the converter 6 is the superheater 2
Is supplied to the electric heat amount adjusting means 8 for adjusting the heat source temperature of the heat source. If the difference between the temperatures measured by the thermocouple thermometers 4 and 5 becomes small, the degree of superheat in the superheater 2 is increased. The quantity adjusting means 8 is controlled to increase the amount of electric heat.

FIG. 4 is a control system diagram showing a fourth embodiment of a gas turbine fuel supply temperature control method according to the present invention. In the figure, the same parts as those shown in FIG. It is attached.

According to FIG. 4, the output of the converter 6 is connected to the fuel switching controller 9, and its output is parallel to the fuel switching valve 10 provided on the downstream side of the fuel gas control valve 3 and this fuel supply system. The fuel is supplied to the fuel switching valve 11 of the installed backup fuel system, and if the difference between the temperatures measured by the thermocouple thermometers 4 and 5 becomes small, the backup fuel (liquid fuel such as heavy oil or gaseous fuel) is supplied. Switch to. At this time, as the temperature difference decreases, an alarm is issued and the backup fuel is automatically switched at the same time, or an alarm is issued to prompt the operator to switch to the backup fuel.

FIG. 5 is a control system diagram showing a fifth embodiment of the gas turbine fuel supply temperature control method according to the present invention. In the figure, the same parts as those shown in FIG. It is attached.

According to FIG. 5, the output of the converter 6 is connected to the fuel switching controller 12, and its output is supplied to the fuel switching valves 13 and 14 installed on the upstream side of the evaporator 1. When the difference between the temperatures measured by the thermocouple thermometers 4 and 5 becomes small, the fuel is automatically switched so that the fuel having a low saturation temperature is supplied to the evaporator 1. At this time, the fuel switching controller 12 may be replaced by an alarm means, and the operator may switch the fuel by the alarm.

FIG. 6 is a control system diagram showing a sixth embodiment of a gas turbine fuel supply temperature control method according to the present invention. In the figure, the same parts as those shown in FIG. It is attached.

According to FIG. 6, the output of the converter 6 is connected to the steam or electric heat quantity adjusting means, and the heat quantity of the steam pipe or the electric heating coil 16 provided around the combustion supply pipe on the downstream side of the superheater 2 is shown. It is controlled. That is, when the difference between the temperatures measured by the thermocouple thermometers 4 and 5 is reduced, the steam or electrothermal amount adjusting means 15 is controlled to increase the amount of pipe steam trace of the steam pipe or the electric heating coil 16 or the amount of pipe electric heater. I will let you.

[0030]

As described above, according to the present invention, the fuel supply temperature is controlled based on the detection of the temperature difference between the temperature between the superheater and the combustor and the temperature inside the evaporator, that is, the relative value. Therefore, even if there are several kinds of fuel supplied to the evaporator, it is possible to give a trip set value of + α for each of the fuels, and heat the fuel more than necessary and supply it as in the conventional case. There is no need to do so, and sizing of valves and nozzles that hindered the design of the fuel supply system can now be performed accurately, which greatly contributes to improving the reliability of gas turbines and reducing equipment costs. .

[Brief description of drawings]

FIG. 1 is a fuel control system diagram showing an embodiment of a method for managing a gas turbine fuel supply temperature according to the present invention.

FIG. 2 is a fuel control system diagram showing a second embodiment of the method for managing the gas turbine fuel supply temperature according to the present invention.

FIG. 3 is a fuel control system diagram showing a third embodiment of a gas turbine fuel supply temperature management method according to the present invention.

FIG. 4 is a fuel control system diagram showing a fourth embodiment of the method for managing the gas turbine fuel supply temperature according to the present invention.

FIG. 5 is a fuel control system diagram showing a fifth embodiment of the gas turbine fuel supply temperature management method according to the present invention.

FIG. 6 is a fuel control system diagram showing a sixth embodiment of the method for managing the gas turbine fuel supply temperature according to the present invention.

FIG. 7 is a fuel control system diagram showing an embodiment of a conventional gas turbine fuel supply temperature management method.

[Explanation of symbols]

 1 Evaporator 2 Superheater 3 Fuel Gas Control Valve 4,5 Thermocouple Thermometer 6 Converter 7 Steam or Hot Water Adjusting Means 8 Electric Heat Quantity Adjusting Means 9 Fuel Changeover Controller 10, 11 Fuel Changeover Valve 12 Fuel Changeover Controller 13, 14 Fuel Switching valve 15 Steam or electric heat amount adjusting means 16 Steam pipe or electric heating coil

Claims (1)

[Claims] Claim: What is claimed is: 1. Management of temperature in a gas turbine fuel supply system comprising an evaporator and a superheater in order from the upstream side of the pipe system, by controlling the temperature detected between the superheater and the combustor and the temperature in the evaporator. A method for managing a gas turbine fuel supply temperature, which is performed based on a temperature difference.