WO2009096028A1

WO2009096028A1 - Motive power supply system for plant, method for operating the same, and method for modifying the same

Info

Publication number: WO2009096028A1
Application number: PCT/JP2008/051573
Authority: WO
Inventors: Yukinori Katagiri; Kouichi Chino; Yasuo Fukushima; Mutsumi Horitsugi
Original assignee: Hitachi, Ltd.
Priority date: 2008-01-31
Filing date: 2008-01-31
Publication date: 2009-08-06
Also published as: JPWO2009096028A1; JP4910042B2

Abstract

A motive power supply system for a plant includes a gas turbine machine (20), an exhaust heat recovery boiler (3) to generate vapor with exhaust gas from the gas turbine machine, a vapor turbine machine (25) which is driven with vapor from the exhaust heat recovery boiler, a bleed piping (64) to supply vapor bled from the vapor turbine machine to a water manufacturing machine (30), a bleed air flow rate regulating valve (9) provided on the bleed piping, and a controller (110) to set up a flow rate (GblsD) of vapor bled from the vapor turbine machine in accordance with an output command deviation (ΔMW0) such that a total output (MW) of the gas turbine machine and the vapor turbine machine comes close to an output command value (MWD) when the output command value (MWD) from a plant which is changed with daily variation in ambient temperature drops below rated output values (MWD0) of the gas turbine machine and the vapor turbine machine. Such a configuration assures operation of the gas turbine machine in the vicinity of its rated output even in the event of drop in ambient temperature, thereby allowing to improve efficiency of the motive power supply system for a plant.

Description

Power supply system for plant, its operation method and remodeling method

The present invention relates to a power supply system for a plant that supplies power to a plant, and an operation method and a modification method thereof.

Among various plants, due to the characteristics of the products of the plant, etc., continuous and stable with respect to a system (plant power supply system) that supplies power (electric power, driving force, etc.) to the plant. Some require power. Further, in such a plant, the gas turbine equipment driven by the combustion gas, the exhaust heat recovery boiler that generates steam from the exhaust gas from the gas turbine equipment, and the steam from the exhaust heat recovery boiler are driven. Some of them use a combined cycle facility combined with a steam turbine facility as a power supply system to improve energy efficiency.

An example of this type of plant is a natural gas liquefaction plant that purifies and liquefies natural gas extracted from a gas field. In this plant, continuous and stable power supply is indispensable in order to maintain the quality of natural gas and maximize the production volume. Also, in natural gas liquefaction plants, the necessary power is supplied within the plant by using a combined cycle facility in order to cope with constraints such as the location of the well being located in an area away from other industrial facilities. There is something.

By the way, combined cycle equipment has the characteristic that the power generation output fluctuates due to daytime and nighttime or annual atmospheric temperature fluctuations. In particular, there is a problem in that the gas turbine output is relatively decreased during warm weather such as daytime or summer, because the atmospheric temperature relatively increases as compared with other times and seasons. In order to deal with this problem, a method has been proposed in which water is sprayed on the gas turbine intake air during warm weather to increase the gas turbine output (see JP 2003-206750 A).

JP 2003-206750 A

However, on the other hand, when it is cold at night or in winter, the air temperature is relatively decreased compared to other times and seasons, so the gas turbine output is relatively increased and generated in the exhaust heat recovery boiler. Steam is surplus. When surplus steam is generated in this way, the amount of steam supplied to the steam turbine equipment and the output of the steam turbine become surplus, and the steam utilization efficiency decreases.

In this regard, in a natural gas liquefaction plant, the cooling performance of a heat exchanger or the like used for cooling natural gas or refrigerant (natural gas cooling refrigerant (mixed medium, propane, etc.)) is relatively improved during cold weather. Therefore, the required power of the compressor that pressurizes and compresses the refrigerant is reduced, and the power required by the plant tends to be reduced. This characteristic is opposite to the characteristic of the combined cycle facility in which the output increases in cold weather, and the efficiency decrease due to surplus steam during cold weather becomes even more remarkable.

For such a problem, there is a method of suppressing the generation of steam by reducing the gas turbine output, but when the gas turbine equipment is operated at an intermediate load, the energy efficiency is reduced compared to the case of operating near the rating, There are economic disadvantages from the viewpoint of fuel use.

An object of the present invention is to provide a power supply system for a plant that can suppress a decrease in efficiency when the atmospheric temperature is lowered while supplying continuous and stable power to the plant.

In order to achieve the above object, the present invention provides a gas turbine facility driven by combustion gas obtained by burning fuel and intake air, an exhaust heat recovery boiler that generates steam from exhaust gas from the gas turbine facility, Steam turbine equipment driven by steam from the exhaust heat recovery boiler, extraction piping for supplying steam extracted from the steam turbine facility to the steam utilization facility, extraction flow rate control valve provided in the extraction piping, air When the output command value (MWD) from the plant that changes with the daily change in temperature is lower than the rated output value (MWD0) of the gas turbine equipment and the steam turbine equipment, the total output of the gas turbine equipment and the steam turbine equipment ( MW) is based on a deviation (ΔMW) between the rated output value (MWD0) and the output command value (MWD) so that the output command value (MWD) approaches. And a control device for determining a steam flow rate (GblsD) extracted from the steam turbine equipment via the extraction piping and setting the extraction flow rate control valve at an opening degree (CVbls) determined based on the steam flow rate (GblsD). With.

According to the present invention, since the gas turbine equipment can be operated near the rating even when the atmospheric temperature decreases, the efficiency of the power supply system for the plant can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the natural gas liquefaction plant provided with the power supply system for plants which concerns on the 1st Embodiment of this invention. The schematic diagram of the power supply system for plants concerning a 1st embodiment of the present invention. The circuit diagram of the combined cycle auxiliary control part 101 of the power supply system for plants which concerns on the 1st Embodiment of this invention. The figure which shows an example of the plant operation characteristic when not performing the optimal operation which concerns on the 1st Embodiment of this invention. The figure which shows an example of the plant operation characteristic at the time of implementing the optimal operation which concerns on the 1st Embodiment of this invention. The schematic diagram of the power supply system for plants concerning a 2nd embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbine 2 Compressor 3 Waste heat recovery boiler 5 Turbine 6 Intake spraying device 7 Temperature measuring device 8 Water quantity adjustment valve 9 Extraction flow rate adjustment valve 10 1st refrigerant compressor 11 2nd refrigerant compressor 20 Gas turbine equipment 23 Flow rate adjustment valve 25 Steam turbine equipment 30 Water production device 31 Water tank 60 First refrigeration cycle system 61 Second refrigeration cycle system 63 Spray water piping 64 Extraction piping 100 Combined cycle control unit 101 Combined cycle auxiliary control unit 102 Plant control unit 110 Controller GblsD Steam flow rate CVbls Opening command GwacD Water volume CVwac Opening command MWD Output command value MWD0 Rated output value ΔMW0 Output command value deviation MW Output

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, a natural gas liquefaction plant equipped with a plant power supply system according to a first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is a schematic view of a natural gas liquefaction plant provided with a plant power supply system according to a first embodiment of the present invention.

The natural gas liquefaction plant is a facility for producing liquefied natural gas (LNG) 48 by refining and liquefying natural gas extracted from a gas field. The natural gas liquefaction plant (hereinafter referred to as appropriate plant) shown in this figure mainly includes a main heat exchanger 40, a gas-liquid separator 41 (separator), a first refrigeration cycle system (mixed refrigerant refrigeration cycle system) 60, A second refrigeration cycle system (propane refrigeration cycle system) 61 is provided.

The main heat exchanger 40 cools and liquefies natural gas (source gas 49) from which impurities have been separated by a natural gas refining facility (not shown) with the first refrigerant from the first refrigeration cycle system 60. .

In the main heat exchanger 40, a natural gas introduction pipe 62 from a natural gas purification facility is introduced. The natural gas introduction pipe 62 circulates the source gas 49 and passes through the main heat exchanger 40 and extends to the outside of the main heat exchanger 40. The main heat exchanger 40 is connected to a gas-liquid separator 41 into which the first refrigerant cooled by the first refrigeration cycle system 60 is introduced. The liquid phase portion and the gas phase portion of the first refrigerant separated by the gas-liquid separator 41 are separately led to the main heat exchanger 40 and used for cooling the raw material gas 49. The raw material gas 49 supplied from the natural gas refining facility is cooled by the first refrigerant when passing through the main heat exchanger 40, and then further cooled to pass through the expansion valve 65 to liquefy natural gas 48. It becomes.

The first refrigeration cycle system (mixed refrigerant refrigeration cycle system) 60 compresses and cools the first refrigerant to be supplied to the main heat exchanger 40. The working fluid (first refrigerant) of the first refrigeration cycle system 60 in the present embodiment is a mixed refrigerant (MCR) mainly composed of methane, ethane, and propane. The first refrigeration cycle system 60 cools the first refrigerant compressed by the low-pressure refrigerant compressor 10a and the low-pressure refrigerant compressor 10a that compresses the first refrigerant used for cooling the natural gas in the main heat exchanger 40. An intermediate cooler 47a, a high-pressure refrigerant compressor 10b that compresses the first refrigerant cooled by the intermediate cooler 47a, a post-cooler 47b that cools the first refrigerant compressed by the high-pressure refrigerant compressor 10b, and a plant And an electric motor 16 that drives the low-pressure refrigerant compressor 10a and the high-pressure refrigerant compressor 10b with electric power supplied from a power supply system 80 (described later) via a power system 18 (see FIG. 2). The inlet of the low-pressure refrigerant compressor 10a is connected to the main heat exchanger 40. The outlet of the post-cooler 47b is connected to the gas-liquid separator 41 after passing through the cooler group (the first cooler 43, the second cooler 44, and the third cooler 45) of the second refrigeration cycle system 61. ing. Hereinafter, the low-pressure refrigerant compressor 10a and the high-pressure refrigerant compressor 10b are collectively referred to as the first refrigerant compressor 10 and the gas-liquid separator 41 is cooled through the cooler group of the second refrigeration cycle system 61. The first refrigerant is subjected to gas-liquid separation, and is connected to the outlet of the third cooler 45. The gas-liquid separator 41 supplies the separated liquid phase portion and gas phase portion of the first refrigerant to the main heat exchanger 40 separately.

The second refrigeration cycle system (propane refrigeration cycle system) 61 compresses and cools the second refrigerant for cooling the first refrigerant, and cools the first refrigerant from the first refrigeration cycle system 60 with the second refrigerant. Is. The second refrigeration cycle system 61 includes a refrigerant compressor (second refrigerant compressor) 11, an electric motor 17, a condenser 46, a liquid receiver 42, a first cooler 43, a second cooler 44, and A third cooler 45 is provided. Note that the working fluid (second refrigerant) of the second refrigeration cycle system 61 in the present embodiment is propane.

The refrigerant compressor 11 compresses the second refrigerant and is driven by an electric motor 17 connected to a drive shaft. The refrigerant compressor 11 has a high pressure stage portion connected to the first cooler 43, an intermediate pressure stage portion connected to the second cooler 44, and a low pressure stage portion connected to the third cooler 45. The second refrigerant (gas) supplied from the

coolers

43, 44, 45 to the refrigerant compressor 11 via this connection path cools the second refrigerant in the refrigerant compressor 11. Electric power of the electric motor 17 is supplied from a power supply system 80 via an electric power system 18 (see FIG. 2).

The condenser 46 is connected to the outlet of the refrigerant compressor 11 and cools and condenses the second refrigerant compressed by the refrigerant compressor 11.

The liquid receiver 42 is connected to the outlet of the condenser 46 and receives the second refrigerant condensed by the condenser 46. A second refrigerant condensed and liquefied is stored in the liquid receiver 42.

The first cooler 43 is connected to the outlet of the liquid receiver 42, and receives the second refrigerant that has been expanded under reduced pressure and reduced in temperature via an expansion valve. The second cooler 44 is connected to the first cooler 43, and receives the second refrigerant further reduced in temperature via the expansion valve. The third cooler 45 is connected to the second cooler 44, and receives the second refrigerant whose temperature has been further reduced via the expansion valve.

Inside the first cooler 43, the second cooler 44, and the third cooler 45, a pipe through which the first refrigerant (mixed refrigerant) flows is arranged. The second refrigerant (propane) received in the

coolers

43, 44, and 45 takes heat from the first refrigerant and evaporates, thereby cooling the first refrigerant stepwise. As a result, the mixed refrigerant (first refrigerant) is cooled to about −35 ° C., for example, when it passes through the third cooler 45 and supplied to the gas-liquid separator 41.

In the above plant, in order to keep the quality of the natural gas constant, it is necessary to minimize the temperature fluctuation of the refrigerant (first refrigerant and second refrigerant) used for cooling the natural gas. The temperature of a 1st refrigerant | coolant and a 2nd refrigerant | coolant is determined by the heat exchange amount of the condenser 46, the intermediate | middle cooler 47a, and the postcooler 47b. During warm days such as daytime and summer when the atmospheric temperature is relatively high, the blower air volume and cooling water volume of these

heat exchangers

46, 47a, 47b are increased, and the temperature and pressure of the refrigerant are controlled to be constant. Along with this, the power required by the entire plant or the first refrigerant compressor 10 and the second refrigerant compressor 11 (output command value MWD described later) also changes.

Next, a power supply system for a plant according to the first embodiment of the present invention will be described.

FIG. 2 is a schematic diagram of a power supply system for a plant according to the first embodiment of the present invention.

The plant power supply system (power supply system) 80 shown in this figure includes a gas turbine facility 20, an intake spray device 6, a water amount adjustment valve 8, a water tank 31, an exhaust heat recovery boiler 3, and a steam turbine facility. 25, a condenser 35, a water production device 30, a power system 18, and a control device 110.

The gas turbine facility 20 includes a turbine 1, a compressor 2, and a combustor (not shown). The intake air and fuel compressed by the compressor 2 are burned by the combustor to generate combustion gas. The turbine 1 is rotationally driven by the combustion gas. A generator 14 is connected to the turbine 1 and supplies power to the plant via the power system 18. The power system 18 supplies the power generated by the power supply system to the plant, and the main power supply destination is the motor 16 that drives the first refrigerant compressor and the second refrigerant compressor 11. There is a motor 17 to perform.

An intake spray device 6 and a temperature measuring device 7 are provided on the upstream side of the compressor 2.

The intake spray device 6 sprays water on the intake air of the gas turbine equipment 20, and is connected to the water tank 31 via the spray water pipe 63. The spray water pipe 63 is provided with a water amount adjustment valve 8 that adjusts the amount of water supplied to the intake spray device 6 according to the atmospheric temperature, and a water transfer pump 32 that pumps up water in the water tank 31. The opening degree of the water amount adjustment valve 8 in the present embodiment is adjusted by an opening degree command (CVwac) output from a combined cycle auxiliary control unit 101 (described later). In addition, as water used for intake spraying, pure water is preferable in order to suppress corrosion and the like of piping.

The temperature measuring device 7 measures the atmospheric temperature, and outputs the measured atmospheric temperature Ta to the combined cycle auxiliary control unit 101.

The water tank 31 stores water supplied to the intake spray device 6. Pure water is supplied from the water production apparatus 30 to the water tank 31 of the present embodiment. In addition to the water production apparatus 30, the condenser 35 and other supply sources may be used as the pure water supply source.

The exhaust heat recovery boiler 3 heats the water supplied from the condenser 35 via the makeup water pump 34 with the exhaust gas from the gas turbine facility 20 to generate steam. The exhaust heat recovery boiler 3 is provided on the downstream side in the direction in which the exhaust gas from the gas turbine equipment 20 flows. Most of the steam generated in the exhaust heat recovery boiler 3 is supplied to the steam turbine equipment 25 via the flow rate control valve 23, and the rest is discharged to the outside via the chimney 4.

The steam turbine facility 25 has a turbine 5 driven by steam from the exhaust heat recovery boiler 3. A generator 15 is connected to the turbine 5, and the steam turbine facility 25 supplies power to the plant via the power system 18. The steam turbine facility 25 is attached with an extraction pipe 64 for extracting a part of the steam flowing through the steam turbine facility 25. Note that the extraction pipe 64 of the present embodiment is connected to a so-called intermediate stage portion between the first stage and the last stage of the turbine 5.

The extraction pipe 64 is connected to the water production facility (steam utilization facility) 30 and supplies the steam extracted from the steam turbine facility 25 to the water production facility 30. The extraction pipe 64 is provided with an extraction flow rate adjusting valve 9 that adjusts the extraction flow rate of steam from the turbine 5 in accordance with the atmospheric temperature. The opening degree of the extraction flow rate adjusting valve 9 in the present embodiment is adjusted by an opening degree command (CVbls) output from a combined cycle auxiliary control unit 101 (described later).

The water production device 30 produces pure water from seawater, river water, etc. using steam from the extraction pipe 64. Seawater or river water, which is a raw material of pure water, is supplied to the water production apparatus 30 by a water intake pump 33. In the present embodiment, seawater or river water pumped up by the intake pump 33 is also supplied to the condenser 35, and is used for condensing steam from the steam turbine equipment 25 by the condenser 35. The pure water produced by the water production apparatus 30 is supplied to the water tank 31 and the condenser 35 and used as intake spray or steam.

The control device 110 controls the entire plant, and includes a plant control unit 102, a combined cycle control unit (hereinafter referred to as CC control unit) 100, and a combined cycle auxiliary control unit (hereinafter referred to as CC auxiliary control unit) 101. is doing.

The plant control unit 102 includes a CC control unit 100 and a CC auxiliary control unit that output a total output (output command value MWD) required by the entire plant and a signal SW that instructs the power supply system to execute the optimum control according to the present invention. 101 is connected to the CC control unit 100 and the CC auxiliary control unit 101. The output command value MWD changes with the daily change of the atmospheric temperature Ta, as shown in FIGS.

The signal SW indicates the start of the optimum operation of the plant based on the atmospheric temperature change according to the present invention after the combined cycle facility including the gas turbine facility 20, the steam turbine facility 25, and the exhaust heat recovery boiler 3 reaches the rated operation state. Or it is a control signal for instruct | indicating cancellation to each control part 100,101. Note that the timing for outputting the signal SW may be determined automatically by calculation in the control circuit of the plant control unit 102, or may be determined manually by an operator operating the control device 110.

The CC control unit 100 is connected to the fuel flow control valve 22. When the CC control unit 100 receives a signal to start control by the signal SW from the plant control unit 102, the CC control unit 100 calculates the opening degree of the fuel flow control valve 22 based on the output command value MWD, and holds the calculated opening degree. The degree command CVfuel is output to the fuel flow control valve 22. The opening degree command CVfuel determines the amount of fuel supplied to the combustor of the gas turbine equipment 20, and thereby the output of the gas turbine equipment 20 and the turbine rotational speed, and the amount of steam generated in the exhaust heat recovery boiler 3 (that is, The amount of steam supplied to the steam turbine equipment 25) is controlled.

The CC auxiliary control unit 101 is connected to the temperature measuring device 7, the water amount adjustment valve 8, and the extraction flow rate adjustment valve 9. When the CC auxiliary control unit 101 receives a signal to start control by the signal SW from the plant control unit 102, the CC auxiliary control unit 101 sums the actual outputs of the gas turbine facility 20 and the steam turbine facility 25 (that is, the actual total output of the power supply system ( Hereinafter, based on the output command value MWD and the atmospheric temperature Ta so that the output MW)) approaches the output command value (MWD), the amount of spray water (GwacD) supplied to the intake spray device 6 and the extraction from the steam turbine equipment 25 The steam flow rate (GblsD) to be adjusted is adjusted.

In the above description, only one gas turbine facility 20 is shown, but a plurality of gas turbine facilities may be connected to the power system 18 according to the power required by the plant. When multiple gas turbine facilities are installed and power is supplied from each gas turbine facility to the plant via the power system 18, the output of any of the multiple gas turbine facilities decreases due to failure or inspection. In this case, the necessary power can be supplemented by the output from other gas turbine equipment. Thereby, compared with the case where gas turbine equipment and a refrigerant compressor are connected directly, the reliability of a power supply system can be improved. In this case, a combined cycle system may be constructed by appropriately providing steam turbine equipment that cooperates with a plurality of gas turbine equipment.

Next, an example of the control circuit of the CC auxiliary control unit 101 will be described with reference to FIG.

FIG. 3 is a circuit diagram of the CC auxiliary control unit 101 of the power supply system according to the first embodiment of the present invention.

The CC auxiliary control unit 101 shown in this figure supplies a subtraction unit 50 that calculates an output command value deviation ΔMW0 (described later), a maximum selection unit 51 that selects the maximum value of the output command value deviation ΔMW0, and an intake spray device 6. A water amount control unit 52 for calculating the amount of water to be calculated, a valve opening degree control unit 53 for adjusting the opening amount of the water amount control valve 8, a minimum selection unit 54 for selecting the minimum value of the output command value deviation ΔMW0, and steam turbine equipment 25, a steam flow rate control unit 55 for calculating the steam flow rate to be extracted from the air flow rate 25 and a valve opening degree control unit 56 for adjusting the opening degree of the extraction flow rate control valve 9 are provided.

The rated output value MWD0 that is the sum of the rated outputs of the gas turbine facility 20 and the steam turbine facility 25 (that is, the combined cycle facility) and the output command value MWD are input to the subtracting unit 50. The subtracting unit 50 subtracts the rated output value MWD0 from the output command value MWD, and calculates a deviation (output command value deviation) ΔMW0 between the output command value MWD and the rated output value MWD0. The output command deviation value ΔMW0 calculated by the subtraction unit 50 is output to the maximum selection unit 51 and the minimum selection unit 54.

The maximum selection unit 51 compares the output command deviation value ΔMW0 with a numerical value 0 (zero), and when the output command deviation value ΔMW0 is positive (that is, the output command value MWD exceeds the rated output value MWD0, the demand (MWD) On the other hand, when the output (MWD0) is insufficient), the maximum value ΔMWH of the deviation value ΔMW0 is output to the water amount control unit 52.

In addition to the maximum deviation value ΔMWH, the atmospheric temperature Ta is input from the temperature measuring device 7 to the water amount control unit 52. The water amount control unit 52 calculates the water amount GwacD from the deviation maximum value ΔMWH by proportional-integral calculation so that the actual output MW of the power supply system approaches the output command value MWD. At this time, the water amount control unit 52 corrects the value of the water amount GwacD according to the atmospheric temperature Ta. Thus, when the correction | amendment according to atmospheric temperature Ta is added to the water quantity GwacD, the motive power fall of the compressor 2 by an air temperature fluctuation | variation can be suppressed. The water amount GwacD calculated by the water amount control unit 52 is output to the valve opening degree control unit 53.

In addition to the water amount GwacD, a signal SW from the plant control unit 102 is input to the valve opening degree control unit 53. The valve opening degree control unit 53 determines the opening degree of the water amount adjustment valve 8 based on the water amount GwacD, and calculates an opening degree command CVwac that holds the calculated opening degree. The opening degree command CVwac calculated by the valve opening degree control unit 53 is output to the water amount adjustment valve 8.

In addition, when the gas turbine equipment 20, the steam turbine equipment 25, and the exhaust heat recovery boiler 3 are not operated at rated values, or when the signal SW does not command the plant optimum operation, an opening degree command CVwac that outputs 0 is output. Then, the intake spray is stopped.

When the intake air spray is applied to the compressor 2 as described above, an increase in the air temperature inside the compressor 2 is suppressed, so that the power of the compressor 2 can be reduced and the output of the gas turbine equipment 20 can be increased. Thereby, even when the atmospheric temperature rises and the output (MWD0) is insufficient with respect to the demand (MWD), the actual output MW can be brought close to the output command value MWD. In this embodiment, when the pure water is sufficiently atomized by the intake spray device 6 and completely evaporated inside the compressor 2, the increase in output is estimated to be approximately 10%. The overall output adjustment range is expected to be about 6% of the rated output value MWD0. Therefore, it is preferable to determine the rated output value MWD0 of the power supply system in consideration of this output adjustment range.

On the other hand, the minimum selection unit 54 compares the output command deviation value ΔMW0 with the numerical value 0 (zero), and when the output command deviation value ΔMW0 is negative (that is, the output command value MWD falls below the rated output value MWD0, the demand (MWD) ) (When the output (MWD0) becomes excessive), the minimum value (absolute value maximum value in a negative number) ΔMWL of the deviation value ΔMW0 is output to the steam flow rate controller 55.

In addition to the minimum deviation value ΔMWL, the atmospheric temperature Ta is input from the temperature measuring device 7 to the steam flow rate control unit 55. The steam flow rate control unit 55 calculates the extraction flow rate GblsD from the minimum deviation value ΔMWL by proportional integration so that the actual output MW of the power supply system approaches the output command value MWD. At this time, the steam flow rate control unit 55 corrects the value of the extraction flow rate GblsD according to the atmospheric temperature Ta. Thus, when the correction | amendment according to atmospheric temperature Ta is added to extraction flow GblsD, the output excess of the steam turbine equipment 25 by temperature fluctuation can be suppressed. The extraction flow rate GblsD calculated by the steam flow rate control unit 55 is output to the valve opening degree control unit 56.

In addition to the extraction flow rate GblsD, a signal SW from the plant control unit 102 is input to the valve opening degree control unit 56. The valve opening degree control unit 56 determines the opening degree of the extraction flow rate adjusting valve 9 based on the extraction flow rate GblsD, and calculates an opening degree command CVbls that holds the calculated opening degree. The opening degree command CVbls calculated by the valve opening degree control unit 56 is output to the extraction flow rate adjusting valve 9.

In addition, when the gas turbine equipment 20, the steam turbine equipment 25, and the exhaust heat recovery boiler 3 are not operated at the rated value, or when the signal SW does not command the plant optimum operation, the opening degree command CVbls that outputs the opening degree 0 is output. Then, steam extraction is stopped.

When steam is extracted from the steam turbine equipment 25 as described above, the output of the steam turbine equipment 25 can be reduced, and pure water can be produced by the water production apparatus 30 using surplus steam. As a result, even when the atmospheric temperature decreases and the output (MWD0) becomes excessive with respect to the demand (MWD), the actual output MW is brought close to the output command value MWD without reducing the output of the gas turbine equipment 20. Can do.

In the above description, only the case where the output command value deviation ΔMW0 calculated by the subtracting unit 50 is positive or negative has been described. However, when the output command value deviation ΔMW0 is zero, the signal SW does not command the optimum plant operation. In the same manner as described above, an opening degree command for opening degree 0 is output to each of the control valves 8 and 9. Further, even when the output command value deviation ΔMW0 does not become zero, a threshold value for regarding the output command value deviation ΔMW0 as zero is determined in advance, and if the output command value deviation ΔMW0 falls within the threshold value, the control valves 8 and 9 You may control to output the opening degree command which becomes the opening degree 0.

Next, effects of the first embodiment of the present invention will be described with reference to FIGS.

FIG. 4 is a diagram showing an example of plant operation characteristics when the optimum operation is not performed. In FIG. 4, the upper diagram is a diagram showing the daily change of the atmospheric temperature Ta, and the lower diagram is a diagram showing the daily change of the output command value MWD and the output MW of the power supply system at that time. In the lower diagram, it is assumed that the fuel flow rate supplied to the gas turbine equipment of the power supply system and the steam flow rate supplied to the steam turbine equipment are constant.

As shown in the upper diagram of FIG. 4, when the atmospheric temperature Ta changes, the output command value MWD required by the plant rises in the daytime (10 to 22:00) and increases at night (0 (10:00 to 20:00 to 24:00). On the other hand, the total MW of the actual output of the gas turbine facility and the steam turbine facility (that is, the actual output of the combined cycle facility) tends to decrease in the daytime and increase in the night as opposed to the atmospheric temperature change.

In particular, in the natural gas liquefaction plant as in the present embodiment, a heat exchanger or the like (for example, an intercooler 47a, a post-cooler) used for cooling natural gas or the first and second refrigerants during cold weather (for example, at night). 47b, because the cooling performance of the condenser 46) is relatively improved, the required power of the

refrigerant compressors

10 and 11 for heating and compressing the first and second refrigerants is reduced, and the output command value MWD tends to be reduced. . This characteristic is opposite to the characteristic of the combined cycle facility in which the output increases in cold weather, and the efficiency decrease due to surplus steam during cold weather becomes even more remarkable. For example, in the example shown in FIG. 4, a deviation of ΔMW occurs at the maximum in the power supply and demand due to the daily change in the atmospheric temperature Ta.

One way to reduce this deviation in power supply and demand ΔMW is to perform partial load operation of the combined cycle facility, but this reduces the power generation efficiency compared to operating the combined cycle facility near the rating. And the fuel utilization rate as the whole plant will also fall.

In response to such a problem, the power supply system according to the present embodiment has an extraction pipe 64 that supplies steam extracted from the steam turbine facility 25 to the water production apparatus 30, an extraction flow rate control valve 9, and an output from the plant. When the command value MWD is lower than the rated output value MWD0 of the gas turbine equipment 20 and the steam turbine equipment 25, the rated output value MWD0 is set so that the total output MW of the gas turbine equipment 20 and the steam turbine equipment 25 approaches the output command value MWD. A control device 110 is provided that determines a steam flow rate GblsD to be extracted from the steam turbine equipment 25 based on the deviation ΔMW of the output command value MWD, and holds the extraction flow rate adjustment valve 9 at the opening degree CVbls determined based on the steam flow rate GblsD. ing.

In the power supply system configured as described above, when it is determined that the atmospheric temperature decreases and the output command value MWD (demand power) falls below the rated output value MWD0 (supply power) (that is, the output command deviation value ΔMW0 is When negative, the CC auxiliary control unit 101 of the control device 110 first calculates the extraction flow rate GblsD from the output command deviation value ΔMW0 and the atmospheric temperature Ta, and based on the calculated extraction flow rate GblsD, the opening degree command CVbls. Is calculated. Next, the CC auxiliary control unit 101 outputs the calculated opening degree command CVbls to the extraction flow rate adjustment valve 9, and the opening degree of the extraction flow rate adjustment valve 9 so that the output MW follows the change in the output command value MWD. Adjust.

When the steam extraction flow rate from the steam turbine equipment 25 is adjusted so that the output MW follows the change in the output command value MWD in this way, the output of the steam turbine equipment 25 is reduced according to the change in the output command value MWD. Therefore, the output MW can be brought close to the output command value MWD while the gas turbine facility 20 is operated near the rating. Further, in the present embodiment, the steam extracted from the steam turbine facility 25 is supplied to the water production device 30 to produce pure water required by the intake spray device 6 when the temperature rises. The generated steam can be used effectively. In other words, according to the present embodiment, the output MW can follow the change in the output command value MWD while operating the gas turbine facility 20 near the rating even when the atmospheric temperature is lowered. Efficiency can be improved.

Here, a specific example of the above effect will be described with reference to FIG.

FIG. 5 is a diagram showing an example of plant operation characteristics when the optimum operation is performed. In FIG. 5, the upper diagram shows the daily change of the output MW when the atmospheric temperature Ta changes as shown in the upper diagram of FIG. 4, and the lower diagram shows the water amount adjustment valve 8 and the bleed flow rate at that time. It is a figure which shows the opening degree (%) of the control valve.

In the example shown in FIG. 5, it is assumed that the plant optimum operation is always performed by the signal SW. Further, “output command value MWD <rated output value MWD0 (ie, output command deviation value ΔMW0 <0)” is established between 0-10 o'clock and 22-24 o'clock, and “output command value MWD> rated rating between 10-22 o'clock”. Assume that the rated output value MWD0 of the power supply system is set so that the output value MWD0 (that is, the output command deviation value ΔMW0> 0) is established.

In this case, the output command deviation value ΔMW0 is negative between midnight and morning (0-10 o'clock, 22-24 o'clock) when the atmospheric temperature Ta is relatively low, so the output of the steam turbine equipment 25 is reduced. Thus, control is performed to bring the output MW closer to the output command value MWD. In particular, in this example, control is performed to keep the output MW constant from 0 to 8 o'clock, and the opening degree of the extraction flow rate adjusting valve 9 is held at α. Thus, when the opening degree of the extraction flow rate adjusting valve 9 is adjusted in accordance with the change in the output command value MWD, the output of the steam turbine equipment 25 can be reduced from the rating by ΔMWbld (see the upper part of FIG. 5). The output MW can be brought close to the output command value MWD while operating the facility 20 near the rating.

By the way, the power supply system of the present embodiment includes an intake spray device 6 that sprays water on the intake air of the gas turbine equipment 20, a water tank 31 that stores water supplied to the intake spray device 6, and a water tank 31. Spray water pipe 63 that connects to the intake spray device 6, a water amount adjustment valve 8 provided in the spray water pipe 63, a temperature measuring device 7 that measures the atmospheric temperature, and an output command value MWD from the plant is the gas turbine equipment 20 and the rated output value MWD0 of the steam turbine equipment 25, the deviation ΔMW between the rated output value MWD0 and the output command value MWD so that the total output MW of the gas turbine equipment 20 and the steam turbine equipment 25 approaches the output command value MWD. And based on the atmospheric temperature Ta from the temperature measuring device 7, the water amount GwacD supplied from the water tank 31 to the intake spray device 6 is determined, and the water amount Gwa is determined. Further comprising a control device 110 for holding the water amount adjusting valve 8 to an opening CVwac determined based on D.

In the power supply system configured as described above, when it is determined that the atmospheric temperature rises and the output command value MWD (demand power) exceeds the rated output value MWD0 (supply power) (that is, the output command deviation value ΔMW0 is When positive, the CC auxiliary control unit 101 of the control device 110 determines the amount of water GwacD supplied to the intake spray device 6 based on the deviation ΔMW of the output command value MWD and the atmospheric temperature Ta. Then, the CC auxiliary control unit 101 outputs the opening degree command CVwac determined based on the water amount GwacD to the water amount adjustment valve 8, and opens the water amount adjustment valve 8 so that the output MW follows the change in the output command value MWD. Adjust the degree.

When the intake spray amount to the inlet of the compressor 2 is adjusted so that the output MW follows the change in the output command value MWD in this way, the driving force of the compressor 2 can be reduced according to the change in the output command value MWD. Therefore, the output of the gas turbine equipment 20 can be increased from the rating according to the change in the output command value MWD. Thereby, even if atmospheric temperature rises, since output MW can be made to follow change of output command value MWD, the efficiency of the power supply system for plants can further be improved.

With respect to the above control, in the example shown in FIG. 5, the water amount adjustment valve 8 is held at the opening degree β at 12 to 20:00 when the atmospheric temperature rises, and the intake spray is performed on the inlet of the compressor 2. As a result, the output of the combined cycle facility increases by ΔMWwac, so that the output MW can be made to follow the output command value MWD required by the plant even when the atmospheric temperature increases.

In the example of FIG. 5, control is performed to keep the output MW constant at 0-8 o'clock and 12-20 o'clock, but the deviation between the output command value MWD and the output MW approaches zero over the entire time period. Thus, the output MW may be controlled. In this case, the efficiency of the power supply system can be further improved.

As described above, according to the present embodiment, even if the output command value MWD required by the plant fluctuates up and down due to the daily change of the atmospheric temperature Ta, the output MW while operating the gas turbine equipment 20 near the rating. Therefore, the power generation efficiency of the combined cycle facility and the fuel utilization rate of the entire plant can be made constant, and the efficient operation of the entire plant becomes possible.

Next, a plant power supply system according to a second embodiment of the present invention will be described.

FIG. 6 is a schematic diagram of a plant power supply system according to a second embodiment of the present invention. The same parts as those in the previous figure are denoted by the same reference numerals and description thereof is omitted.

The power supply system of the present embodiment is different from that of the first embodiment in that the drive shaft of the first refrigerant compressor 10A is connected to the turbine 1, and the second refrigerant compressor 11A is connected to the turbine 5. The drive shaft is connected. With this configuration, the power supply system shown in FIG. 6 directly drives the first refrigerant compressor 10 with the power obtained by the gas turbine equipment 20, and the second refrigerant compressor 11 with the power obtained by the steam turbine equipment 25. Is driving directly.

Conventionally, when the rotating shafts of the

turbines

1 and 5 are directly connected to the drive shafts of the

refrigerant compressors

10 and 11 as described above, when the required power of each of the

refrigerant compressors

10 and 11 changes individually, It was difficult to make the output of the combined cycle equipment follow changes.

However, according to the present embodiment configured as described above, the opening degree command CVwac to the water amount adjusting valve 8 can be calculated from the deviation of the output of the gas turbine equipment 20 and the necessary power of the first refrigerant compressor 10. The opening degree command CVbls to the extraction flow rate adjusting valve 9 can be calculated from the deviation of the output of the steam turbine equipment 25 and the necessary power of the second refrigerant compressor 11. Therefore, according to the present embodiment, the outputs of the gas turbine facility 20 and the steam turbine facility 25 can be individually controlled by controlling the opening degree commands CVwac and CVbls. Thereby, it can respond flexibly also when the required motive power of the 1st refrigerant | coolant compressor 10 and the 2nd refrigerant | coolant compressor 11 changes separately.

In the above description, the configuration in which the first refrigerant compressor 10 is driven by the gas turbine equipment 20 and the second refrigerant compressor 11 is driven by the steam turbine equipment 25 has been taken up. The second refrigerant compressor 11 may be driven by 20 and the first refrigerant compressor 10 may be driven by the steam turbine equipment 25.

Further, a generator (not shown) is added to the rotating shaft of the gas turbine equipment 20 or the rotating shaft of the steam turbine 25 shown in FIG. 6, and the first refrigerant compressor 10 or the second refrigerant compressor 11 becomes redundant. Electric power may be generated with a different driving force. If the generator is added in this way, the surplus output that is not used for driving the

refrigerant compressors

10 and 11 can be supplied as electric power to other equipment in the plant, so that the output generated by the combined cycle equipment can be used. Efficiency can be further improved.

By the way, in each said embodiment, although the system (propane pre-cooling MCR system) using a mixed refrigerant and propane as a refrigerant which cools natural gas was taken up and explained, various methods are proposed for a natural gas liquefaction system. This is just one way of cooling natural gas. The power supply system of the present invention can be applied to any system as long as it is a natural gas liquefaction plant that drives a large compressor, and does not depend on the cooling / liquefaction system exemplified above.

In each of the above-described embodiments, the supply destination of the steam extracted from the steam turbine facility 25 is the water production apparatus 30, but one end of the extraction pipe 64 is connected to a steam utilization facility such as a heat pump or district heating / cooling, and extraction The steam thus used may be used as a heat source for other equipment.

Furthermore, in the above description, the power supply system of the natural gas liquefaction plant has been described as an example, but besides this, the power supply consistent with the power demand of the plant is always required due to the nature of the plant, and the The present invention can be applied to any plant that requires stable power.

Claims

Gas turbine equipment driven by combustion gas obtained by burning fuel and intake air,
An exhaust heat recovery boiler that generates steam from the exhaust gas from the gas turbine facility;
Steam turbine equipment driven by steam from the exhaust heat recovery boiler;
An extraction pipe for supplying steam extracted from the steam turbine facility to the steam utilization facility;
An extraction flow control valve provided in the extraction pipe;
When the output command value from the plant that changes with the daily change of the atmospheric temperature is lower than the rated output value of the gas turbine equipment and the steam turbine equipment, the total output of the gas turbine equipment and the steam turbine equipment becomes the output command value. A steam flow to be extracted from the steam turbine equipment via the extraction piping is determined based on a deviation between the rated output value and the output command value so as to approach, and the extraction is determined at an opening determined based on the steam flow. A power supply system for a plant, comprising: a control device that sets a flow control valve.
The power supply system for a plant according to claim 1,
An intake air spray device for spraying water into the intake air of the gas turbine equipment;
A water tank storing water to be supplied to the intake spray device;
Spray water piping connecting the water tank and the intake spray device;
A water amount adjusting valve provided in the spray water pipe;
A temperature measuring device for measuring the atmospheric temperature,
The control device further includes a sum of the gas turbine equipment and the steam turbine equipment when an output command value from the plant that changes with a daily change in atmospheric temperature exceeds a rated output value of the gas turbine equipment and the steam turbine equipment. Supplied from the water tank to the intake spray device via the spray water pipe based on the deviation between the rated output value and the output command value and the atmospheric temperature from the temperature measuring device so that the output approaches the output command value A power supply system for a plant, wherein the amount of water to be determined is determined, and the water amount adjustment valve is set to an opening determined based on the amount of water.
The power supply system for a plant according to claim 2,
The plant power supply system, wherein the steam utilization facility is a water production apparatus for producing water to be supplied to the water tank.
The power supply system for a plant according to claim 1,
A power supply system for a plant, wherein a generator for supplying electric power to the plant is connected to the gas turbine facility and the steam turbine facility.
The power supply system for a plant according to claim 1,
A power supply system for a plant, wherein a rotation drive device of the plant is connected to the gas turbine facility and the steam turbine facility.
The power supply system for a plant according to claim 5,
A power supply system for a plant, wherein a generator for supplying electric power to the plant is connected to at least one of the gas turbine facility and the steam turbine facility.
In the power supply system for plants in any one of Claim 1 to 6,
The plant power supply system, wherein the plant is a natural gas liquefaction plant.
Gas turbine equipment driven by combustion gas obtained by burning fuel and intake air, an exhaust heat recovery boiler that generates steam from exhaust gas from the gas turbine equipment, and driven by steam from the exhaust heat recovery boiler In a method for operating a power supply system for a plant comprising a steam turbine facility,
When the output command value from the plant that changes with the daily change of the atmospheric temperature is lower than the rated output value of the gas turbine equipment and the steam turbine equipment, the total output of the gas turbine equipment and the steam turbine equipment becomes the output command value. The steam flow to be extracted from the steam turbine equipment is determined based on the deviation between the rated output value and the output command value so as to approach,
A method for operating a power supply system for a plant, comprising: adjusting a flow rate of steam supplied from the steam turbine facility to a steam utilization facility based on the determined steam flow rate.
The operation method of the power supply system for a plant according to claim 8,
Further, when the output command value from the plant that changes with the daily change of the atmospheric temperature exceeds the rated output value of the gas turbine equipment and the steam turbine equipment, the total output of the gas turbine equipment and the steam turbine equipment is the output command value. To determine the amount of water sprayed to the intake of the gas turbine equipment based on the deviation between the rated output value and the output command value and the atmospheric temperature,
A method for operating a power supply system for a plant, wherein the amount of water sprayed on the intake air of the gas turbine equipment is adjusted based on the determined amount of water.
Gas turbine equipment driven by combustion gas obtained by burning fuel and intake air, exhaust heat recovery boiler that generates steam from exhaust gas from the gas turbine equipment, and steam driven from the exhaust heat recovery boiler For power supply systems for plants with steam turbine equipment,
An extraction pipe for supplying steam extracted from the steam turbine facility to the steam utilization facility;
An extraction flow control valve provided in the extraction pipe;
When the output command value from the plant that changes with the daily change of the atmospheric temperature is lower than the rated output value of the gas turbine equipment and the steam turbine equipment, the total output of the gas turbine equipment and the steam turbine equipment becomes the output command value. A steam flow to be extracted from the steam turbine equipment via the extraction piping is determined based on a deviation between the rated output value and the output command value so as to approach, and the extraction is determined at an opening determined based on the steam flow. A remodeling method for a power supply system for a plant, wherein a control device for setting a flow control valve is additionally provided.