KR100941168B1 - Control system and control method of gas turbine - Google Patents

Abstract

When the gas turbine load falls, even if the power generation equipment employs low-calorie gas as fuel, the gas turbine 2 is a gas turbine control system that can easily suppress the increase in the rotation speed of the gas turbine. A fuel flow rate control valve 9 for regulating the flow rate of the fuel gas and a thermal gas supply for supplying the thermal gas to the fuel gas supply passage 3 disposed in the fuel gas supply passage 3 for supplying fuel gas; The apparatus 5 and the system control apparatus 10 are provided, and when this system control apparatus 10 detects the fall of load of the gas turbine 2, in order to reduce the heat input of the gas turbine 2, In addition to the opening degree control of the fuel flow rate control valve 9, it is comprised so that the thermal gas supply operation by the thermal gas supply apparatus 5 may be controlled.

Gas turbine, power generation equipment, rotation speed, load drop, control system, fuel gas supply passage, fuel flow control valve, heat input

Description

CONTROL SYSTEM AND CONTROL METHOD OF GAS TURBINE}

The present invention relates to a gas turbine control system and a control method, and more particularly, in a gas turbine power generation system, when a sudden load reduction such as load interruption occurs, The present invention relates to a gas turbine control system and a gas turbine control method capable of quickly controlling a heat input amount of a gas turbine in order to prevent an excess thereof.

In the field of steel making, for example, when pig iron is produced by the blast furnace method, the blast furnace gas (Blast Furnace Gas, referred to as BFG) is Occurs as a low calorie by-product gas. In recent years, in gas turbines, combustion of low-calorie by-product gas such as BFG is possible due to the improvement of technology, and the number of cases of generating electricity by using gas turbine fuel is increasing. On the other hand, in addition to the blast furnace method, new steelmaking processes such as the direct reduction iron method and the molten reduction iron method have been developed, and by-product gas is generated in such a new process. By-product gas generated in any steelmaking process is a so-called low-calorie gas, and its characteristics (gas composition and calorie) vary depending on the installation and operation. Even in the same facility, the characteristics of each raw material and the reaction process change from time to time and are not constant. It is expected to develop a combustion method that can be applied to the effective use of such by-product gas.

It is not limited to gas turbine power generation facilities that use low-calorie by-product gas (hereinafter referred to as "low-calorie gas") whose caloric value fluctuates. When a situation such as a sudden drop in the load occurs, it is necessary to control the gas turbine overspeed (overspeed rise of the rotational speed) and to maintain the required minimum output without tripping. For example, when the gas turbine is operating at rated load and the load is interrupted and released from the load due to any cause occurring in the transmission system or the gas turbine power generation equipment, the gas turbine momentarily enters the overspeed state. When the controller detects this, the opening degree of the flow control valve of the fuel supply system is rapidly reduced to suppress the overspeed of the gas turbine. The detection of the load interruption is executed according to the input such as the output signal of the generator and the rotational speed signal of the gas turbine.

And the flow control valve closes to the opening degree which the required minimum flow amount of fuel for maintaining the rated rotation speed in no load state is avoided, avoiding the combustion of the combustor. The opening degree control of such a flow control valve is performed, for example, by monitoring operation state amounts, such as gas turbine rotation speed, generator output, gas turbine exhaust temperature, air compressor inlet pressure, and outlet pressure. Control of such load interruption is disclosed in Japanese Patent Application Laid-Open No. 8-165934, Japanese Patent Application Laid-Open No. 2002-138856, and Japanese Patent Application Laid-Open No. 2002-227610.

In addition, depending on the gas turbine type, a means for opening and operating the gas turbine inlet blades during load drop is also used. Accordingly, by increasing the driving power of the compressor, the control effect of the rotating shaft is increased to increase the gas turbine. There is also a speed control.

However, in the gas turbine power generation equipment using the low calorie gas as fuel, operation control at the time of this load drop is not easy. Since the fuel gas is low-calorie, the supply amount to the gas turbine needs to be increased, so a large-diameter fuel gas supply pipe is used. As a result, the opening and closing stroke of the flow control valve also increases, which requires a long time for the valve closing. Therefore, it is difficult to rapidly reduce the heat input of the gas turbine at the same time as the occurrence of load interruption, and effective overspeed suppression of the gas turbine cannot be expected.

In addition, as described above, since the calorie fluctuates every moment, increasing the control gain of the flow control valve (increasing the response) makes the flow rate control sensitive to the disturbance of the calorie fluctuation. There is a possibility that the valve may cause henching. In order to avoid such a situation, control gain is set such that the responsiveness of the flow control valve is lowered. This further impedes the rapid closing operation of the flow control valve and becomes a factor of making it difficult to rapidly reduce the heat input of the gas turbine.

In gas turbine power generation facilities using low calorie gas as fuel, a fuel compressor for compressing low calorie gas is provided in the fuel gas supply passage. This fuel compressor is often coaxially connected with the gas turbine. In this case, the moment of inertia of the entire rotor body of the generator heat constituted by the gas turbine, the fuel compressor and the generator is large. In addition, since the overspeed condition is caused by the load cutoff, rapid braking cannot be expected even if the flow control valve of the fuel supply line of the gas turbine is closed at the same time as the load cutoff, so that the rotation speed of the generator row including the gas turbine is increased. It is difficult to suppress it.

In commercial gas turbine power generation facilities, it is mandatory to confirm by the load breaking test that the speed governing device functions so that the gas turbine does not exceed 110% of the rated rotation speed during load operation in the event of load interruption. have. Operation is permitted after the function of the governor is confirmed. For this reason, in gas turbine power generation facilities using high calorie value and stable natural gas as fuel, various studies have been conducted in terms of device construction and control in order to suppress overspeed of the gas turbine at the time of load shedding so as not to exceed the specified range. By responding. Such studies have failed to effectively suppress the overspeed of the gas turbine when the load of the gas turbine power generation equipment, which is constantly low in calorie fluctuation, is used as fuel.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and when a load drop occurs such as load blocking in a gas turbine power generation facility, even if the facility uses low-calorie gas as fuel, the gas turbine can be easily installed. It is an object of the present invention to provide a gas turbine control system capable of suppressing an increase in rotational speed and to provide such a gas turbine control method.

Gas turbine control system of the present invention,

A gas turbine control system that suppresses an increase in the number of revolutions of a gas turbine when the load of the gas turbine drops sharply.

A fuel flow rate control valve arranged in a fuel gas supply passage for supplying fuel gas to the gas turbine, for controlling the flow rate of the fuel gas;

A thermal gas supply device for supplying thermal gas to the fuel gas supply passage;

With system control,

When the system controller detects a drop in load of the gas turbine, in order to reduce the heat input amount of the gas turbine, in addition to the opening degree control of the fuel flow rate control valve, to control the thermal gas supply operation by the thermal gas supply device. Consists of.

In this way, in order to reduce the heat input amount of the gas turbine when the gas turbine load falls, in addition to the control of the opening of the fuel flow control valve, a thermal gas is supplied to the fuel. Even if it exists, the increase of the rotation speed of a gas turbine can be suppressed effectively.

The system control unit closes the fuel flow control valve to an opening degree not exceeding a predetermined required minimum opening degree when the load of the operating gas turbine drops rapidly (for example, almost stepwise) to a predetermined value. In addition, the gas turbine may be controlled to supply the gas for heat reduction, which is necessary for the rotation speed of the gas turbine not to exceed a predetermined value.

In this way, by adding the heat-sensitive gas to the fuel, it is possible to reduce the amount of heat input while securing the minimum fuel flow rate necessary to prevent tripping of the gas turbine, thereby suppressing the increase in the rotation speed of the gas turbine and not exceeding the predetermined rotation speed. .

The system controller is configured to feedback control the amount of thermal gas supply from the thermal gas supply device so that the rotation speed of the gas turbine does not exceed a predetermined value by using the detected rotation speed of the gas turbine as a feed back input signal. Can be.

In the system controller, simulation of the thermal gas supply control and fuel flow control valve opening degree control performed along this model after the event of the process of rapidly decreasing the load of the operating gas turbine to a predetermined value is modeled. Remember the results,

The system controller may be configured to select and execute a preset control mode based on the simulation result when the load of the running gas turbine rapidly drops to a predetermined value.

The gas turbine control system further includes a hydrogen gas supply device for supplying hydrogen gas to the fuel gas supply passage, and a hydrogen concentration detection device for detecting hydrogen concentration in the fuel gas, wherein the system control device includes a hydrogen concentration. Can be configured to control the hydrogen gas supply operation by the hydrogen gas supply device based on the detection result.

Stable combustion in the combustor by avoiding misfire of the gas turbine by supplying the fuel gas with the required amount of hydrogen gas with high combustion speed and good ignition flame resistance, even if the gas turbine heat drops rapidly. Can be maintained. The purity of the hydrogen gas to be supplied is not particularly limited, but the higher the purity, the better the complex flame resistance, even in a small amount.

Gas turbine control method of the present invention,

As a gas turbine control method for suppressing the increase in the rotation speed of the gas turbine when the gas turbine load drops,

When detecting load drop of gas turbine,

Controlling the flow rate of the fuel gas by controlling the opening of the fuel flow control valve disposed in the fuel gas supply passage for supplying the fuel gas to the gas turbine;

Supplying a thermal gas to the fuel gas supply passage;

These steps are carried out to lower the heat input of the gas turbine.

When the load on the running gas turbine drops rapidly (for example, almost stepwise) to a predetermined value,

In the fuel flow rate adjusting step, the fuel flow rate control valve is closed to an opening degree not lower than a predetermined required minimum opening degree, thereby reducing the fuel flow rate,

In the thermal gas supply process, the thermal gas necessary for the rotation speed of the gas turbine not to exceed a predetermined value may be supplied to the fuel gas supply passage.

The minimum required opening degree is a valve opening degree for securing a fuel flow rate necessary for maintaining stable combustion of the gas turbine.

According to the present invention, when a sudden drop in load such as load interruption occurs in the gas turbine power generation equipment, it is possible to suppress the increase in the gas turbine rotation speed rapidly and effectively.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram schematically showing an example of a gas turbine power generation facility including an embodiment of a gas turbine control system of the present invention.

Figure 2a is a graph showing the load change when the load cut off of the gas turbine,

Figure 2b is a graph showing the change in the opening degree of the fuel flow control valve to be controlled in response to the load cutoff,

Figure 2c is a graph showing the gas turbine heat input change according to the change in the opening of the fuel flow control valve,

Figure 2d is a graph showing the change in the gas turbine heat input amount according to the change in the opening degree of the fuel flow control valve and the supply of the thermal gas,

Figure 2e is a graph showing a change in the number of revolutions of the gas turbine generated due to the gas turbine heat input change.

3 is a schematic diagram schematically showing another example of the gas turbine power generation equipment including the embodiment of the gas turbine control system of the present invention.

DETAILED DESCRIPTION Embodiments of a gas turbine control system and a gas turbine control method of the present invention will be described with reference to the accompanying drawings.

1 is a schematic diagram showing a gas turbine power generation facility 1 including an embodiment of a gas turbine control system of the present invention. This gas turbine power generation equipment 1 (hereinafter also referred to simply as power generation equipment 1) is, for example, a low calorie by-product gas (low calorie gas) in which the calorie value generated from a gas generating source S such as a direct reduction iron plant fluctuates constantly. Fuel gas supply pipe (3) for supplying gas as fuel to the gas turbine (2), fuel compressor (4) for compressing low-calorie gas, and thermal reduction for supplying thermal gas to the fuel gas supply pipe (3). A gas supply device 5, a hydrogen gas supply device 6 for supplying hydrogen gas to the fuel gas supply pipe 3, and a mixer 7 for mixing the supplied thermal gas and hydrogen gas with low calorie gas, respectively. ). The mixer 7 may be arrange | positioned, respectively for the thermal gas mixing and hydrogen gas mixing. Further, a device such as a buffer tank for suppressing the calorie fluctuation of low calorie gas may be provided on the fuel gas supply pipe 3 as necessary.

In such a power generation facility 1, since the heat-sensitive gas and hydrogen gas supply sources 15 and 19 of higher pressure than the low-calorie gas supplied as fuel gas are provided, the heat-sensitive gas supply apparatus 5 and hydrogen gas are provided. The supply device 6 and the mixer 7 are provided on the downstream side of the fuel compressor 4 in the fuel gas supply pipe 3. The fuel compressor 4 may be configured to be coaxially connected to the gas turbine 2 so as to be driven by the gas turbine 2, or may be arranged separately from the gas turbine 2 and driven by a separately installed motor. It may be configured as possible.

In addition, in the normal operation of the gas turbine power generation equipment 1, a system controller 10 for controlling the operation of the gas turbine is provided when a sudden drop of the load such as load interruption occurs. A fuel flow rate control valve (hereinafter simply referred to as a control valve) 9 is provided upstream of the gas turbine combustor 8 in the fuel gas supply pipe 3. Reference numeral 11 denotes an air compressor and reference numeral 12 denotes a generator. On the upstream side of the mixer 7 in the fuel gas supply pipe 3, a hydrogen concentration meter 13 for measuring the hydrogen concentration in the fuel gas and a fuel flow meter 14 for measuring the flow rate of the low calorie gas are provided. The higher the purity of the hydrogen gas, the better the ignition flame resistance in a small amount, but in practice, the hydrogen gas to be supplied does not have to be pure hydrogen. Here, the low calorie gas is defined as a gas whose calorific value is about 12 MJ / Nm ³ or less.

The heat-sensitive gas supply device 5 is a heat-sensitive gas for low-calorie gas for the purpose of rapidly lowering the heat input of the gas turbine 2 when a sudden drop in load such as load blocking occurs in the gas turbine power generation equipment 1. It is installed to mix. The thermal gas supply device 5 includes a thermal gas supply source 15, a thermal gas supply pipe 16 connected to the mixer 7 from the thermal gas supply source 15, and a thermal gas supply pipe ( It has the heat-sensitive gas flowmeter 17 and the flow control valve 18 provided in 16). The pressure of the thermal gas at the stage of entering the mixer 7 is higher than the pressure of the low calorie gas so that the required amount can be supplied quickly. For this purpose, a boosting device, a pressure storage container, or the like may be provided as necessary. The control of the heat-sensitive gas supply device 5 that supplies the heat-sensitive gas at the time of the load drop is performed by the system controller 10 while controlling the fuel flow rate control valve 9 in the closing direction. This point is mentioned later.

As the thermal gas, inert gas such as waste nitrogen, helium (He) or carbon dioxide, air, combustion exhaust gas, or the like can be used. Since the air can be used by inhaling inexhaustible atmosphere and the combustion exhaust gas is generated in the gas turbine 2, for example, the air can be recovered and used, so that the operating cost is very low. When using a gas containing oxygen such as air and combustion exhaust gas, the thermal gas is mixed with a low calorie gas, and then operation control is performed while monitoring the oxygen concentration so that the mixed gas (fuel gas) does not enter the flammable limit. .

The waste nitrogen contains a large amount of N ₂ , while not a flammable gas. Waste nitrogen is generated as a by-product from oxygen production plants used in various steelmaking processes, and nitrogen released from dissipation and nitrogen discharged from nitrogen produced in nitrogen production plants added to oxygen production plants. Nitrogen in trace amounts. Any nitrogen is waste nitrogen and is usually released to the atmosphere. Such waste nitrogen has a gas composition of about 95 to 98% of nitrogen gas and about 2 to 5% of oxygen, and is a safe thermal gas in view of the flammable limit of low calorie gas. By recovering these large amounts of waste nitrogen and using it as a thermal gas, the operating cost becomes very low.

If the gas is lower calorie than fuel gas, it can be used as a thermal gas. For example, when coke oven gas (COG) and converter gas (LDG) are used as fuel gas, the blast furnace is lower than those. It is also possible to employ gas BFG as the thermal gas. However, it is preferable to use waste nitrogen or the like having a very low flammable component content rate because the thermal effect is much greater. In addition to the gas described above, it is also possible to employ water vapor as the thermal gas.

In the normal operation of the power plant 1, the system controller 10 may output, for example, the output value of the generator 12, the rotation speed of the gas turbine 2, the inlet pressure of the air compressor 11, the gas. Using the exhaust temperature of the turbine 2 as an input signal, the opening degree of the fuel flow rate control valve 9 is controlled to perform gas turbine heat input according to the fluctuation.

Moreover, the calorie value of the low calorie gas which is a fuel fluctuates as mentioned above. In order to maintain a stable heat input of the gas turbine against such calorie fluctuations, the system controller 10 controls the opening of the fuel flow control valve 9 according to an appropriate feedforward control or feedback control. There is a case. However, if the fuel flow rate control valve 9 is opened and closed in response to a change in calorie value and a change in generator output, the control gain is greatly increased because the fuel flow rate control valve 9 may cause a handle in response to a small calorie change. You can't. That is, when using a low calorie gas, the response of the fuel flow volume control valve 9 cannot be made high, but the control gain is set small normally. In addition, the fuel flow rate control valve 9 also needs to be enlarged because the fuel gas supply pipe 3 for supplying the low calorie gas has a large pipe diameter.

For this reason, even when it is desired to reduce the gas turbine heat input momentarily during load interruption or the like, a rapid opening / closing operation of the fuel flow rate control valve 9 cannot be expected. In this power generation facility 1, therefore, the system controller 10 effectively controls the heat input amount of the gas turbine 2 by mixing the thermal gas with the fuel gas in addition to the opening / closing operation of the fuel flow rate control valve 9.

In addition, in order to reduce the heat input amount of the gas turbine, the valve opening degree must be made very small in the case of responding only by narrowing the fuel flow control valve 9 as in the prior art. In this case, a back fire or the like may occur in the combustor due to insufficient fuel flow rate, and combustion may become unstable. However, in the power generation facility 1, the heat input amount control is also performed by the heat-sensitive gas as described above, so that the fuel flow rate control valve 9 can be made open to secure the required minimum flow rate for stable combustion. As a result of the narrowing of the fuel flow control valve 9 and the synergistic effect of the thermal gas mixture, the gas turbine heat input is stably and quickly shifted from the rated load operation state to the rated no load operation state without tripping the gas turbine. You can.

The fuel flow rate control valve 9 is closed while accommodating the supply of the thermal gas, but the closing operation is stopped when the required minimum opening degree is reached. In this case, of course, if the heat input amount is required, the supply of the heat-sensitive gas can be continued within the range not lower than the misfire limit.

Referring to FIG. 2, the control of the fuel flow rate control valve 9, the control of the thermal gas supply device 5, and the change in the gas turbine rotational speed by the load breaking of the power generation facility 1 described above will be described. do.

When a load break occurs, the gas turbine is momentarily removed from the load, but it cannot be instantaneously reduced for the heat input supplied to maintain rated operation until then. The excess heat input generates an acceleration torque to accelerate the gas turbine and increase the rotation speed. Even in such a case, the amount of heat input should be drastically reduced so that the speed of the gas turbine does not exceed the maximum allowable speed (Rmax.).

2A shows the load change of the gas turbine 2 at the time of load shedding. The horizontal axis represents time, the vertical axis represents gas turbine load (%), 100% rated load operation is executed until load interruption, and 0% after load interruption.

FIG. 2B shows the change of the opening degree of the fuel flow rate control valve 9 when the load of the gas turbine 2 is cut off. The horizontal axis represents time to correspond to FIG. 2A described above. Although the vertical axis | shaft shows the opening degree (%) of a control valve, you may identify with the fuel flow volume. Until the load is interrupted, the rated opening degree (100%) (ODrat.) Of the control valve (9), that is, the rated heat input (HIrat.) (Fig. 2C) of the gas turbine 2 as described later is enabled. The operation is carried out at the fuel flow rate (rated fuel flow rate) Qrat. After the load is blocked, the control valve 9 is opened up to an introduction direction (called the minimum opening required) (ODmin.) Where the fuel flow rate is the required minimum flow rate (Qmin.) For maintaining the no-load rated rotational speed of the gas turbine. The required minimum flow rate Qmin. Is a fuel set in order to ensure the fuel gas flow rate in the range in which the so-called backfire does not occur in the combustor 8, and to secure the required minimum heat input amount HImin. Which does not reach the misfire limit described later. Flow rate.

The dashed-dotted line curve B1 in FIG. 2B is a valve closing curve necessary for reducing the gas turbine heat input so that when the load break occurs, the gas turbine speed does not exceed the allowable maximum value Rmax. (FIG. 2E). This is a fuel flow reduction curve. This is called an abnormal curve (BI). On the other hand, the curve B2 shown by the solid line is the actual valve closing curve of the control valve 9 in the present embodiment. This indicates that rapid closing is not possible because the aperture of the control valve 9 is set to a large size and the control gain is set small as described above.

2C and 2D show a change in heat input amount per unit time of the gas turbine during load interruption. FIG. 2C shows the reduction in the heat input amount by the closing operation of the control valve 9 only, and FIG. 2D shows the reduction in the heat input amount due to the closing operation of the control valve 9 and the supply of the thermal gas. The horizontal axis represents time to correspond to FIG. 2B described above. The vertical axis represents the amount of heat input per unit time of the gas turbine 2. The load is operated at the rated heat input (HIrat.) Set in the gas turbine (2), and after the load is blocked, it is operated at the heat input in a range that does not fall to the misfire limit of the gas turbine.

The dashed-dotted line curve C1 in FIG. 2C shows a state in which the heat input amount of the gas turbine is reduced when the valve is closed along the ideal closed curve B1 (FIG. 2B). This is a reduction curve of the gas turbine heat input amount necessary for the gas turbine rotational speed not to exceed the allowable maximum value Rmax. (Fig. 2E) when the load interruption occurs. This is called an abnormal curve C1. On the other hand, the curve C2 shown by the solid line is a reduction curve of the actual amount of heat input due to the closing of the control valve 9 in which rapid valve closing is impossible.

Since the dashed-dotted line curve D2 in FIG. 2D shows that it is the same as the deceleration curve C2 of the actual heat input amount in FIG. 2C mentioned above, description is abbreviate | omitted. On the other hand, the curve D1, which is a solid line, closes the control valve 9 along the actual valve closing curve B2 in FIG. 2B and supplies the gas for thermal reduction to the fuel gas from the thermal gas supply device 5. This is a curve when the heat input amount of the turbine 2 is rapidly lowered. This is a curve showing an example of the control in the present embodiment.

Looking at the curve D1, in comparison with the heat input amount lowering curve D2 only by the closing of the control valve 9, the lower value of the heat input amount is lowered as well as the lowering rate is large (undershooting from d1 to d2). have). This occurs when the control gain of the heat-sensitive gas supply, which should match the ideal heat input reduction curve C1 in FIG. 2C, is set. This undershoot improves the effect of suppressing the rise of the gas turbine speed. In this case, of course, the required minimum heat input amount (fire limit HImin.) Set in order to prevent misfire of the gas turbine 2 is set to be lower. It can be seen from the above that the hatching portion surrounded by the curve C1 and the curve C2 is a heat input amount that can be reduced by the supply of the thermal gas.

FIG. 2E shows the rotation speed change of the gas turbine under the heat input control shown in FIGS. 2C and 2D. The horizontal axis represents time to correspond to Figs. 2C and 2D described above. The vertical axis represents the ratio of the number of revolutions in which the gas turbine speed is 100% at the rated speed (Rrat.) At the rated load operation.

Curve E2 in the figure shows a case where the gas turbine speed after load breaking is not effectively suppressed and exceeds the allowable maximum speed (value of 110% of the rated speed) (Rmax.). This is because when the control valve 9 cannot close rapidly due to the aperture or gain setting as described with reference to curve B2 of FIG. 2B, the gas turbine heat input amount is not appropriately reduced (the curve of FIG. 2C). C2 and curve D2) of FIG. 2D. On the other hand, curve E1 shows the case where the heat input to the gas turbine 2 is rapidly lowered along the curve D1 by combining the supply of the thermal gas shown in FIG. have. In this case, the gas turbine speed does not exceed the allowable maximum speed (Rmax.).

As shown in Figs. 2A to 2E, when the load of the gas turbine 2 decreases stepwise from the point A1 of 100% to the point A2 of 0% in Fig. 2A by load interruption, in this embodiment, The system control device 10 of the system is configured to close the control valve 9 to the required minimum opening degree (ODmin.) So as to suppress the sudden increase in the rotational speed of the gas turbine 2 (curve B2 in FIG. 2B). The thermal gas is supplied from the gas supply device 5 to the fuel gas. In doing so, the heat input of the gas turbine 2 decreases rapidly (curve D1 in FIG. 2D). As a result, the gas turbine whose speed has started to rise rapidly out of the load is prevented from exceeding the allowable maximum speed Rmax. Due to the braking effect of the heat input amount being reduced, and the rated speed Rrat. Decelerate to near) (curve E1 in FIG. 2E).

As a means for the system controller 10 to detect that the load of the gas turbine 2 has dropped, for example, a method known as a conventionally known power load unbalanced detection can be used. Of course, it is not limited to this method. If possible, the load drop may be detected from the rotation speed signal of the gas turbine, the exit pressure signal of the fuel compressor, the breaking signal from the load breaker, and the like.

When the system controller 10 controls the closing operation of the control valve 9 and the operation of the thermal gas supply device 5 after detecting the load drop, the rated rotation speed (Rrad.) Is set as a target value. In addition, the actual gas turbine rotation speed can be controlled by feeding back. In addition, other gas turbine operating state quantities may be fed back and controlled. In addition, it is also possible to simulate the thermal gas supply control and the closing control of the control valve modeled after the load drop from the rated load operation of the gas turbine. The control device 10 presets data of the opening degree of the control valve at the time of the load drop and the supply amount of the heat-sensitive gas corresponding to the opening degree, the timing of the supply, and the like obtained from the simulation result. . And during actual load drop, preset data can be selected and executed. In addition, the actual data (including data at the time of load interruption) obtained through the actual operation operation may be replaced with some or all of the simulation data. That is, the preset data of the simulation result may be corrected by the actual operation data and used.

As described above, the system controller 10 stores a program for performing the arithmetic processing necessary for the control and preset data, and includes a RAM for temporarily storing data and numerical values, etc. during operation, and calculation according to the program. CPU oil for processing is provided.

The system controller 10 controls all operations of the gas turbine operation as described above. That is, the system control apparatus 10 includes a start (including start preparation, purging, ignition, synchronous injection, cold start, warm start), rated load operation, Each mode of operation such as partial load operation, stop, cool down, and load interruption are stored. Modes other than the load interruption are omitted here. In particular, in the load interruption mode, the gas turbine control system realizes a rapid reduction in heat input by mixing the gas for heat in the fuel gas in addition to the operation control of the fuel flow rate control valve 9 and other control targets.

When the load interruption occurs and the operation mode of the system controller 10 becomes the load interruption mode, the required supply flow rate and supply time of the thermal gas from the system controller 10 to the thermal gas supply device 5 are reduced. Is directed. The required supply flow rate and supply time are stored as preset data. At this time, for example, the opening / closing operation of the flow control valve 18 may be controlled so that the target supply flow rate is obtained by using the measurement result of the thermal gas flow meter 17 as a feedback signal. In consideration of the need to supply a predetermined amount of the thermal gas for a short time, the diameter of the thermal gas supply pipe 16 and the flow control valve 18 may be reduced, and the number of installation water and the number of installation may be increased.

Next, the hydrogen gas supply device 6 will be described. Since hydrogen gas has a high combustion speed and good ignition flame resistance, it contributes to maintaining stable combustion even when the heat input amount of the gas turbine is greatly reduced. Therefore, the hydrogen gas supply device 6 is provided to maintain the flame in the combustor 8 of the gas turbine 2 by mixing hydrogen gas in the fuel gas. Therefore, this hydrogen gas supply device 6 is useful for preventing gas turbine misfire due to a decrease in heat input during a load drop. The hydrogen gas supply device 6 includes a hydrogen gas supply source 19, a hydrogen gas supply pipe 20 connected to the mixer 7 from the hydrogen gas supply source 19, and hydrogen gas provided in the hydrogen gas supply pipe 20. It has a flowmeter 21 and a flow control valve 22. When using high purity hydrogen gas instead of pure hydrogen as hydrogen gas, a hydrogen concentration meter (not shown) is provided in the hydrogen gas supply pipe 20.

The system controller 10 controls the hydrogen gas supply as follows when the calorie value and the flow rate of the fuel gas supplied to the gas turbine 2 are rapidly lowered when the gas turbine load falls sharply. That is, as a result of the detection of the hydrogen concentration meter 13 of the fuel gas supply pipe 3 so as to maintain the hydrogen gas required content rate of the fuel gas in the combustor 8 predetermined for flame holding, mixing of the thermal gas with respect to low calorie gas is carried out. The required amount of hydrogen gas is calculated from the ratio, the flow rate of the fuel gas detected by the fuel flow meter 14, and the like. Then, the opening and closing operation of the flow control valve 22 is controlled while monitoring the hydrogen gas flow meter 21. The supplied hydrogen gas is mixed with the low calorie gas by the mixer 7.

3 shows another gas turbine power plant 31. In this power generation facility 31, since the relatively low pressure thermal gas supply source 15 and the hydrogen gas supply source 19 are provided, the thermal gas supply device 5, the hydrogen gas supply device 6, and the mixer 7 are provided. ) Is provided upstream of the fuel compressor 4 in the fuel gas supply pipe 3. Since other configurations are the same as those of the power generation equipment 1 shown in FIG. 1, the same reference numerals are given to the same components and the description thereof is omitted. In this gas turbine power generation facility 31, the system control device 10 performs the same control as in the power generation facility 1 of FIG.

In the embodiment described above, by-product gas generated by the direct reduction iron production method is illustrated as the low calorie gas to be used, but the present invention is not limited thereto. Examples of low-calorie gas include blast furnace gas (BFG), converter gas (LDG), coal bed gas contained in the coal layer (coal mine gas, referred to as CMG), by-product gas generated by the fusion reduction steelmaking method, and GTL (Gas-to). -Tail gas generated in liquid process, by-product gas generated by oil refining process from oil sand, gas generated by pyrolyzing garbage, general waste including kitchen waste The landfill includes low calorie gas such as by-product gas generated by chemical reaction of combustible methane gas (Landfill gas) generated during fermentation and decomposition, and other similar raw materials. Of course, the gas includes not only the gas but also a gas obtained by mixing a plurality of different gases. In addition, the present invention is not limited to low-calorie gas, and can be applied to a facility for supplying a gas such as a calorie value fluctuating as fuel for a gas turbine.

Depending on the characteristics of the fuel gas, especially when the calorie fluctuation is significant, a calorie fluctuation suppressor using a buffer tank and a control mechanism that suppresses the calorie fluctuation may be provided to increase the control effect at the time of breaking the load. .

The gas turbine control system described above exemplifies that the gas gas for the gas turbine is a low calorie gas. However, the gas turbine control system is not limited thereto, and the gas turbine control system may be a high calorie gas as the fuel. In the case of using high-calorie gas as fuel, gas turbine heat input control by the fuel flow control valve is generally easy even when the gas turbine load drops. When using high-calorie gases such as natural gas, hydrocarbon gas such as propane or butane, and mixed gas of COG, COG and other by-product gas, the size of the fuel gas piping and fuel flow control valve Can be made smaller than that for low-calorie gas. As a result, the valve closing stroke is shortened to enable a quick response. In addition, when the gas properties including the calorie value are stabilized, it is not necessary to set the control gain of the fuel flow rate control valve small. In addition, since there is no need to provide a fuel compressor, there is no increase in the moment of inertia of the rotating body. As a result, the fuel flow control valve can be rapidly closed to the required minimum opening degree even when the load drops. However, even when high calorie gas is used, the moment of inertia increases due to the addition of several mechanisms to the gas turbine after operation, and the control gain may need to be reset. Even in such a case, if a thermal gas supply device is installed, it is possible to easily and reliably compensate for the load shedding operation without the need to change or modify the fuel flow control valve by utilizing the gas turbine heat input. It becomes possible.

Based on the foregoing, various modifications and embodiments will be apparent to those skilled in the art. Therefore, it should be understood that the above description is described with reference to the drawings, and the above description is for the purpose of explaining the present invention to those skilled in the art. Regarding the contents of the configuration and function described above, various modifications and changes can be made without departing from the spirit of the present invention, and they should be understood as belonging to the scope of the present invention.

The gas turbine control system of the present invention easily realizes a reduction in heat input of a portion that cannot be achieved only by the narrowing of the fuel flow control valve by mixing the gas for heat with the fuel gas. Such a gas turbine control system can be applied to a gas turbine power generation facility without requiring a large design change.

Claims (9)

A gas turbine control system that suppresses an increase in the rotation speed of a gas turbine by reducing the amount of heat input to the gas turbine at the time of the load drop of the gas turbine, A fuel flow rate control valve arranged in a fuel gas supply passage for supplying fuel gas to the gas turbine, for controlling the flow rate of the fuel gas; A thermal gas supply device for supplying a thermal gas to the fuel gas supply passage; With system control, When the system controller detects a load drop of the gas turbine, the opening degree of the fuel flow control valve is not lower than the required minimum opening degree so that the detected rotation speed of the gas turbine does not exceed a predetermined value. And a gas turbine control system configured to control the thermal gas supply operation by the thermal gas supply device in parallel with the opening degree control decreasing in a range. delete 2. The heat supply gas supply amount according to claim 1, wherein the system controller sets the detected rotation speed of the gas turbine as a feedback input signal so that the rotation speed of the gas turbine does not exceed a predetermined value. Gas turbine control system, characterized in that for controlling the feedback. 2. The system control apparatus according to claim 1, wherein an event of a process of rapidly decreasing the load of the operating gas turbine to a predetermined value is modeled in the system control apparatus, and the thermal gas supply control and the fuel flow rate are performed according to the model. The simulation result of the opening degree control of the control valve is stored, And the system control unit is configured to select and execute a preset control mode based on the simulation result when the load of the running gas turbine rapidly drops to a predetermined value. . 2. The apparatus of claim 1, further comprising a hydrogen gas supply device for supplying hydrogen gas to the fuel gas supply passage, and a hydrogen concentration detection device for detecting hydrogen concentration in the fuel gas, And the system controller is configured to control the hydrogen gas supply operation by the hydrogen gas supply device based on the detection result of the hydrogen concentration. As a control method of a gas turbine for suppressing the increase in the rotation speed of the gas turbine by reducing the amount of heat input to the gas turbine at the time of the load drop of the gas turbine, When detecting that the load of the gas turbine during operation has dropped rapidly to a predetermined value, The opening degree of the fuel flow control valve disposed in the fuel gas supply passage for supplying fuel gas to the gas turbine so that the detected rotation speed of the gas turbine does not exceed a predetermined value, does not exceed the predetermined minimum opening degree required. And controlling the supply amount of the thermal gas to the fuel gas supply passage in parallel with adjusting the flow rate of the fuel gas by controlling. delete A gas turbine control system that suppresses an increase in the number of revolutions of a gas turbine when the load of the gas turbine drops sharply. A fuel flow rate control valve arranged in a fuel gas supply passage for supplying fuel gas to the gas turbine, for controlling the flow rate of the fuel gas; A thermal gas supply device for supplying a thermal gas to the fuel gas supply passage; With system control, When the system controller detects a load drop of the gas turbine, in order to reduce the amount of heat input to the gas turbine, in addition to the opening degree control of the fuel flow rate control valve, the heat supply gas is supplied by the thermal gas supply device. Configured to control operation, In addition, when the load of the gas turbine during operation rapidly decreases to a predetermined value, the fuel flow control valve is closed to an opening degree not lower than a predetermined required minimum opening degree, and the rotation speed of the gas turbine exceeds a predetermined value. It is configured to supply the thermal gas required from the thermal gas supply device, so as not to In the system control apparatus, an event of a process of rapidly decreasing the load of a running gas turbine to a predetermined value is modeled, and a thermal gas supply control and opening degree control of the fuel flow control valve performed according to the model. The simulation results of And the system control unit is configured to select and execute a preset control mode based on the simulation result when the load of the running gas turbine rapidly drops to a predetermined value. . A gas turbine control system that suppresses an increase in the number of revolutions of a gas turbine when the load of the gas turbine drops sharply. A fuel flow rate control valve arranged in a fuel gas supply passage for supplying fuel gas to the gas turbine, for controlling the flow rate of the fuel gas; A thermal gas supply device for supplying a thermal gas to the fuel gas supply passage; With system control, When the system controller detects a load drop of the gas turbine, in order to reduce the amount of heat input to the gas turbine, in addition to the opening degree control of the fuel flow rate control valve, the heat supply gas is supplied by the thermal gas supply device. Configured to control operation, And a hydrogen gas supply device for supplying hydrogen gas to the fuel gas supply passage, and a hydrogen concentration detection device for detecting hydrogen concentration in the fuel gas. And the system controller is configured to control the hydrogen gas supply operation by the hydrogen gas supply device based on the detection result of the hydrogen concentration.

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