JP5023148B2 - Power supply facility for natural gas liquefaction plant, control device and control method thereof, and natural gas liquefaction plant - Google Patents

Description

  The present invention relates to a power supply facility for a natural gas liquefaction plant, a control device and control method therefor, and a natural gas liquefaction plant.

  The natural gas liquefaction plant purifies liquefied natural gas by cooling natural gas extracted from gas fields and oil fields with a refrigerant. Such plants are often located away from other industrial facilities, and power supply equipment for generating power (driving power, electric power) necessary for plant operation is often provided in the plant. As such a power supply facility for a natural gas liquefaction plant, for example, a gas turbine plant or a combined cycle plant is used.

  By the way, from the viewpoint of maintaining the quality and production efficiency of liquefied natural gas, it is desirable to operate the refrigerant compressor used for compressing the refrigerant in the natural gas liquefaction plant at a constant load. Therefore, it is required for the power supply equipment for the natural gas liquefaction plant to always supply the power required by the refrigerant compressor.

  As a technology of this kind, in a plant that directly drives the refrigerant compressor with the axial driving force of the gas turbine, when the power required by the refrigerant compressor exceeds the power generated by the gas turbine, the power obtained outside the gas turbine is insufficient. There is one configured to compensate for the minute (see JP-A-8-219571, etc.).

JP-A-8-219571

  However, when the above power supply equipment is used in an area where the atmospheric temperature changes due to a difference in season or day and night, the gas turbine output fluctuates due to a change in the intake air temperature, which may reduce the operation efficiency of the entire plant. In particular, there are many natural gas mining sites that have relatively high temperatures, such as regions with summer seasons, desert regions, and low-latitude regions, and the reduction in efficiency due to a decrease in gas turbine output becomes significant. Furthermore, in some cases, it may be impossible to supply necessary power to the plant even if the above technique is applied.

  An object of the present invention is to provide a power supply facility for a natural gas liquefaction plant, a control device and a control method thereof, and a natural gas liquefaction plant that can improve the plant operation efficiency when the atmospheric temperature changes.

In order to achieve the above object, the present invention provides a refrigerant compressor that compresses a refrigerant, a condenser that cools and condenses the refrigerant compressed by the refrigerant compressor, and a liquid receiver that receives the refrigerant condensed in the condenser. In a power supply facility for a natural gas liquefaction plant that supplies power to a natural gas liquefaction plant that includes a chiller and a cooler that expands the refrigerant from the receiver and cools other refrigerants, the fuel and intake air are burned A gas turbine driven by the combustion gas obtained in this way, a boiler that generates steam by exhaust gas from the gas turbine, a steam turbine driven by steam from the boiler, steam from the steam turbine, and cooling water a refrigerator for generating cold water by an intake cooler for cooling the intake air of the gas turbine by the cold water from the refrigerator, or the steam turbine A first flow rate adjusting means for adjusting a steam flow rate to the refrigerator, a second flow rate adjusting means for adjusting a cold water flow rate from the refrigerator to the intake air cooling device, and when entering the refrigerator A first temperature detector that detects the temperature of the cooling water, a second temperature detector that detects the temperature of the intake air as it exits the intake air cooling device, and a temperature setting for maintaining the temperature of the cold water generated by the refrigerator The opening degree of the first flow rate adjusting means is adjusted based on the detection value of the first temperature detector so that the steam flow rate from the steam turbine to the refrigerator approaches the target flow rate, and the output of the gas turbine Control for adjusting the opening of the second flow rate adjusting means based on the detection value of the second temperature detector so that the temperature of the intake air when coming out of the intake air cooling device approaches the target temperature set to hold the With the device For example, the refrigerant compressor, the driven by the gas turbine and power from at least one of the steam turbine, the condenser, and cools and condenses the refrigerant with cold water from the refrigerator.

  According to the present invention, even if the atmospheric temperature changes, a decrease in gas turbine output can be suppressed, so that the plant operation efficiency when the atmospheric temperature changes can be improved.

FIG. 1 is a schematic diagram of refrigerant precooling equipment and power supply equipment of a natural gas liquefaction plant according to a first embodiment of the present invention. FIG. 2 is a schematic diagram of the natural gas liquefaction plant according to the first embodiment of the present invention. FIG. 3 is a schematic diagram of the refrigerant precooling facility and the power supply facility of the natural gas liquefaction plant according to the second embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of the control device 30 in the natural gas liquefaction plant according to the second embodiment of the present invention. FIG. 5 is a comparative table of steam balances in a power supply facility and a comparative example of a natural gas liquefaction plant according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerant compressor 2 Motor 3 Condenser 4 Receivers 5-7 Cooler 11 1st refrigerant 20 Compressor 22 Gas turbine 24 Boiler 25 Steam turbine 28 Refrigerator 29 Intake air cooling device 30 Control device 32 Flow rate adjustment valve 34 Flow rate adjustment Valve 51 Air temperature detector 52 Intake air temperature detector 53 Steam flow rate detector 54 Cooling water temperature detector 62 Cold water temperature control unit 63 Intake air temperature control unit 100 Refrigerant precooling equipment 120 Gas-liquid separator 140 Main heat exchanger 160 Refrigerant precooling equipment 200 Power supply equipment

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

  FIG. 1 is a schematic diagram of refrigerant precooling equipment and power supply equipment of a natural gas liquefaction plant according to a first embodiment of the present invention.

  The natural gas liquefaction plant shown in this figure includes a refrigerant precooling facility 100 that cools a refrigerant used for liquefaction of natural gas, and a power supply facility 200 that supplies power (driving power and electric power) to facilities in the natural gas liquefaction plant. I have.

  The refrigerant precooling facility 100 includes a refrigerant compressor 1, a motor 2, a condenser 3, a liquid receiver 4, a first cooler 5, a second cooler 6, and a third cooler 7. A refrigerant (hereinafter referred to as a first refrigerant) 11 used for liquefaction of natural gas is cooled by another refrigerant (hereinafter referred to as a second refrigerant). In the present embodiment, a mixed refrigerant mainly containing methane, ethane, and propane is used as the first refrigerant 11, and propane is used as the second refrigerant.

  The refrigerant compressor 1 compresses the second refrigerant that cools the first refrigerant 11, and is driven by a motor 2 connected to a drive shaft. Although not particularly illustrated, the refrigerant compressor 1 according to the present embodiment includes three stages of a high pressure compressor, an intermediate pressure compressor, and a low pressure compressor. The high pressure compressor includes a cooler 5 and an intermediate pressure. The compressor is connected to the cooler 6, and the low-pressure compressor is connected to the cooler 7. The electric power of the motor 2 is supplied from the power supply facility 200.

  The condenser 3 is connected to the outlet of the refrigerant compressor 1 via a pipe 13 and has a pipe 14 through which cold water from a refrigerator 28 (described later) flows. The condenser 3 exchanges heat between the second refrigerant and the cold water compressed by the refrigerant compressor 1 via the pipe 14, thereby cooling and condensing the second refrigerant. Thereby, the 2nd refrigerant | coolant of this Embodiment is cooled to about 50 degreeC, for example.

  The liquid receiver 4 is connected to the outlet of the condenser 3 via the pipe 15 and receives the second refrigerant condensed by the condenser 3. A second refrigerant condensed and liquefied is stored in the liquid receiver 4.

  The first cooler 5 is connected to the outlet of the liquid receiver 4 through a pipe 16, and the second refrigerant that has been decompressed and expanded through an expansion valve (not shown) provided in the pipe 16 to reduce the temperature. Accept. The second cooler 6 is connected to the first cooler 5 via a pipe 17 and receives the second refrigerant further reduced in temperature via an expansion valve (not shown) provided in the pipe 17. . The third cooler 7 is connected to the second cooler 6 via a pipe 18 and receives the second refrigerant further reduced in temperature via an expansion valve (not shown) provided in the pipe 18. Yes.

  Inside the first cooler 5, the second cooler 6, and the third cooler 7, a pipe 19 through which the first refrigerant 11 flows is arranged. The second refrigerant received in the coolers 5, 6, 7 evaporates by taking heat from the first refrigerant 11 flowing through the pipe 19, thereby cooling the first refrigerant 11 in a stepwise manner. Thereby, the 1st refrigerant | coolant 11 of this Embodiment is cooled to about -30 degreeC, for example when it passes the 3rd cooler 7. FIG. The first cooler 5, the second cooler 6, and the third cooler 7 are connected to the high-pressure compressor, the medium-pressure compressor, and the low-pressure compressor of the refrigerant compressor 1, respectively. Intermediate cooling of the second refrigerant is also performed.

  The power supply facility 200 includes a compressor 20, a combustor 21, a gas turbine 22, a generator 23, a boiler 24, a steam turbine 25, a generator 26, a chimney 27, a refrigerator 28, an intake air A cooling device 29 is provided.

  The compressor 20 compresses the combustion air taken from the atmosphere.

  The combustor 21 generates combustion gas by combusting fuel supplied via the flow rate adjustment valve 31 and compressed air from the compressor 20, and is connected to the outlet of the compressor 20. The flow rate adjustment valve 31 is for adjusting the flow rate of fuel supplied to the combustor 21. As the fuel supplied to the combustor 21, it is preferable to use mined natural gas from the viewpoint of improving energy efficiency, plant operation efficiency, and the like.

  The gas turbine 22 is driven by the combustion gas from the combustor 21 and is connected to the outlet of the combustor 21. The gas turbine 22 drives the compressor 20 and the generator 23 and generates electric power by the generator 23. This power is supplied as power to equipment in the natural gas liquefaction plant.

  The boiler (exhaust heat recovery boiler) 24 generates steam by the exhaust gas of the gas turbine 22, and is provided on the downstream side in the exhaust gas flow direction. The chimney 27 exhausts the exhaust gas heat recovered by the boiler 24.

  The steam turbine 25 is driven by steam from the boiler 24 and is connected to the generator 26. The steam turbine 25 generates electric power by driving a generator 26. The electric power obtained by the generators 23 and 26 is supplied as power to equipment in the natural gas liquefaction plant.

  The refrigerator 28 generates cold water (for example, about −5 to 10 ° C.) with steam from the steam turbine 25 and cooling water. The refrigerator 28 is provided with a pipe 41 through which steam from the steam turbine 25 circulates, a pipe 42 through which cooling water circulates, and a pipe 43 through which water to be cooled (cold water) circulates.

  The pipe 41 is connected to a pipe 44 to which steam is supplied from the steam turbine 25. Starting from the connection with the pipe 44, one side of the pipe 41 is introduced into the refrigerator 28, and the other side is connected to a condenser (not shown) via the flow rate adjustment valve 32. Yes. The steam that has flowed into the condenser is condensed into water, which is reused as water supply for the boiler 24. The flow rate adjustment valve 32 is for adjusting the steam flow rate from the steam turbine 25 to the refrigerator 28. If the opening degree of the flow rate adjusting valve 32 is increased, the steam flow rate supplied to the refrigerator 28 is reduced. Conversely, if the opening degree is reduced, the steam flow rate is increased.

  The pipe 42 is provided with a pump 45, and cooling water for cooling the refrigerant in the refrigerator 28 is pumped by the pump 45. The pipe 43 is provided with a pump 46, and water (cold water) cooled by the refrigerator 28 is pumped by the pump 46.

  In addition, as a refrigerator used for this Embodiment, the thing using the heat | fever of the steam supplied from the steam turbine 25 and generating cold water should just be used. An example of this type of refrigerator is an absorption refrigerator. In the case of an absorption refrigerator that uses a mixed refrigerant of water and lithium bromide, the steam is used as a heat source when the mixed refrigerant is heated to separate water and lithium bromide.

  A cold water header 35 for sending the cold water generated by the refrigerator 28 to a plurality of supply destinations is provided on the downstream side of the refrigerator 28 in the pipe 43. A pipe 14 introduced into the condenser 3 and a pipe 48 introduced into the intake air cooling device 29 are connected to the cold water header 35.

  The pipe 14 is provided with a flow rate adjusting valve 33 for adjusting the flow rate of cold water from the refrigerator 28 to the condenser 3, and the pipe 48 is used for adjusting the flow rate of cold water from the refrigerator 28 to the intake air cooling device 29. A flow rate adjustment valve 34 is provided.

  The intake air cooling device 29 cools combustion air (intake air) introduced into the compressor 20, and is provided on the upstream side of the compressor 20. A pipe 48 is disposed inside the intake air cooling device 29, and the intake air of the gas turbine 22 is cooled by cold water flowing through the pipe 48.

  In the natural gas liquefaction plant configured as described above, the steam generated in the boiler 25 of the power supply facility 200 is introduced into the refrigerator 28 via the pipe 41 after driving the steam turbine 25. While the refrigerator 28 uses this steam as a heat source, the cooling water introduced through the pipe 42 is used for cooling the refrigerant, and the water supplied through the pipe 43 is cooled to generate cold water. The cold water generated by the refrigerator 28 is supplied to the intake air cooling device 29 and the condenser 3 via the cold water header 35.

  The cold water supplied to the intake air cooling device 29 reduces the intake air temperature of the compressor 20. As a result, the load on the compressor 20 decreases, so that the turbine output can be increased without increasing the fuel flow rate. The cold water supplied to the condenser 3 cools and condenses the second refrigerant. Thereby, since the second refrigerant can be cooled more effectively than the case where the refrigerant affected by the atmospheric temperature change such as outside air or seawater is used, the first refrigerant used for liquefaction of natural gas is efficiently cooled. be able to.

  In addition, as a 2nd refrigerant | coolant of the refrigerant | coolant precooling equipment 100, the propane shown above is preferable. This is because propane has a relatively high saturation temperature and is easily condensed by being cooled to cold water (for example, −5 to 10 ° C.) in the condenser 3, so that it is suitable as a refrigerant for a cycle combined with the refrigerator 28. is there. In addition to propane, the second refrigerant can be replaced with propylene, a mixed refrigerant containing propane, methane, and ethane as main components.

  FIG. 2 is a schematic view of the natural gas liquefaction plant according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part as the previous figure, and description of the part is abbreviate | omitted (it is assumed that the subsequent figure is the same).

  The natural gas liquefaction plant shown in this figure includes the refrigerant precooling equipment 100 shown in FIG. 1, a gas-liquid separator 120 that separates the first refrigerant 11 cooled by the refrigerant precooling equipment 100 into a gas phase and a liquid phase, A main heat exchanger 140 that cools and liquefies natural gas using the first refrigerant 11, and a refrigerant precooling facility 160 that cools the first refrigerant 11 stored in the main heat exchanger 140 by exchanging heat with natural gas. It has.

  The gas-liquid separator 120 is connected to the outlet of the refrigerant precooling facility 100 (that is, the outlet of the third cooler 7 (see FIG. 1)) via the pipe 19. The gas-liquid separator 120 is connected to a pipe 141 through which the liquid phase of the first refrigerant 11 flows and a pipe 142 through which the gas phase flows.

  After being introduced into the main heat exchanger 140, the pipe 141 is once taken out of the main heat exchanger 140, and then introduced into the main heat exchanger 140 again and connected to the nozzle 143. . The pipe 141 has a heat transfer path 144 provided inside the main heat exchanger 140 and an expansion valve 145 provided outside the main heat exchanger 140. Similarly, the pipe 142 is once taken out of the main heat exchanger 140 and then connected to the nozzle 146 in the main heat exchanger 140. The pipe 142 has heat transfer paths 147 and 148 provided inside the main heat exchanger 140 and an expansion valve 149 provided outside the main heat exchanger 140.

  The piping 150 circulates the natural gas to be liquefied, and extends to the outside of the main heat exchanger 140 after passing through the inside of the main heat exchanger 140. The pipe 150 has heat transfer paths 151 and 152 provided inside the main heat exchanger 140 and an expansion valve 153 provided outside the main heat exchanger 140.

  The refrigerant precooling facility 160 cools the first refrigerant 11 used for liquefaction of natural gas, and includes compressors 162 and 163 driven by a motor 161 and a cooler 164 that cools the compressed first refrigerant 11. , 165. The motor 161 drives the compressors 162 and 163 with electric power supplied from the power supply facility 200. The compressor 162 is connected to the main heat exchanger 120 via a pipe 166.

  Next, the natural gas liquefaction process in the natural gas liquefaction plant configured as described above will be described.

  The first refrigerant 11 cooled to a predetermined temperature (for example, about −35 ° C.) by the second refrigerant in the refrigerant precooling facility 100 is supplied to the gas-liquid separator 120 via the pipe 19, and the gas phase component and liquid Separated into phase components.

  The liquid phase component of the first refrigerant 11 in the gas-liquid separator 120 is introduced into the main heat exchanger 140 via the pipe 141, and passes through the heat transfer path 144 while the refrigerant in the main heat exchanger 140 ( It is further cooled by the cooled first refrigerant 11). The first refrigerant 11 that has passed through the heat transfer path 144 is adiabatically expanded by the expansion valve 145, cooled to a predetermined temperature (for example, about −120 ° C.), and dispersed as a refrigerant in the main heat exchanger 140 through the nozzle 143. Is done.

  On the other hand, the gas phase component of the first refrigerant 11 in the gas-liquid separator 120 is introduced into the main heat exchanger 140 through the pipe 142 and cooled while passing through the heat transfer paths 147 and 148. The first refrigerant 11 that has passed through the heat transfer paths 147 and 148 is cooled to a predetermined temperature (for example, about −170 ° C.) by the expansion valve 149, and is dispersed as a refrigerant in the main heat exchanger 140 through the nozzle 146. .

  Further, the natural gas flowing in the pipe 150 passes through the main heat exchanger 140, and the predetermined temperature (for example, −150) in the heat transfer paths 151 and 152 by the first refrigerant 11 dispersed as described above when passing through the main heat exchanger 140. It is cooled to about ° C. Thereafter, the natural gas guided to the outside of the main heat exchanger 140 is further cooled by passing through the expansion valve 153, and becomes a liquefied natural gas having a predetermined temperature (for example, −162 ° C.). Although not particularly shown, an upstream side of the pipe 150 is provided with equipment for performing an acid gas removal process, a water removal process, and the like, and the natural gas that has undergone these pretreatment processes is provided in the pipe 150. Has been led.

  The first refrigerant 11 used for cooling the natural gas is stored in the main heat exchanger 140 and introduced into the refrigerant precooling facility 160 via the pipe 166. Thus, the first refrigerant 11 guided to the refrigerant precooling facility 160 is appropriately compressed and cooled by the compressors 162 and 163 and the coolers 164 and 165 to be in a predetermined state (for example, 40 ° C., 5 MPa), The refrigerant is introduced into the refrigerant precooling facility 100 through the pipe 19.

  Next, the effect of this embodiment will be described.

  Unlike the natural gas liquefaction plant according to the present embodiment described above, a power supply facility without the intake air cooling device 29 or a condenser using a refrigerant affected by changes in the atmospheric temperature such as outside air or seawater is precooled with the refrigerant. In the plant equipped with the equipment, when the atmospheric temperature rises, the temperature of the gas turbine intake and the condenser refrigerant also rises, so that the gas turbine output and the condenser cooling capacity are lowered. Therefore, when a plant having such a configuration is used in a season or region where the atmospheric temperature is relatively high, the operation efficiency of the plant may be reduced.

  On the other hand, the natural gas liquefaction plant of the present embodiment includes a refrigerator 28 that generates cold water using steam discharged from the power supply facility 200. According to the present embodiment configured as described above, the cold water generated by the refrigerator 28 can be supplied to the intake air cooling device 29 and the condenser 3. Since the cold water supplied to the intake air cooling device 29 lowers the intake air temperature of the gas turbine 22, the load on the compressor 20 is reduced, and the turbine output can be increased without increasing the fuel flow rate. Moreover, since the cold water supplied to the condenser 3 suppresses a decrease in the cooling capacity of the condenser 3 when the atmospheric temperature changes, it is possible to efficiently cool the first refrigerant used for natural gas liquefaction. it can.

  Thus, according to this Embodiment, since the fall of the gas turbine output and the cooling capacity of a condenser can be suppressed, the plant operation efficiency when atmospheric temperature rises can be improved. Moreover, according to this Embodiment, since cold water can be generated using the steam heat released to the atmosphere, the thermal efficiency of the plant can also be improved.

  Next, a second embodiment of the present invention will be described. The feature of this embodiment is that a control device 30 for controlling the intake air temperature of the gas turbine 22 and the cold water temperature of the refrigerator 28 is provided.

  FIG. 3 is a schematic diagram of refrigerant precooling equipment and power supply equipment of a natural gas liquefaction plant according to a second embodiment of the present invention.

  The power supply facility 200A shown in this figure includes the above-described power in that it includes an atmospheric temperature detector 51, an intake air temperature detector 52, a steam flow rate detector 53, a cooling water temperature detector 54, and a control device 30. Different from the supply facility 200.

  The atmospheric temperature detector 51 detects the temperature of intake air (that is, the temperature of the atmosphere) when entering the intake air cooling device 29, and is provided on the upstream side of the intake air cooling device 29. The detection value (atmospheric temperature Ta) of the atmospheric temperature detector 51 is output to the control device 30. The intake air temperature detector 52 detects the temperature of the intake air as it exits the intake air cooling device 29, and is provided downstream of the intake air cooling device 29 and upstream of the compressor 20. The detection value (intake air temperature Tao) of the intake air temperature detector 52 is output to the control device 30. The steam flow rate detector 53 detects the flow rate of the steam entering the refrigerator 28, and is provided on the pipe 41 on the refrigerator 28 side from the connection portion with the pipe 44. The detection value (steam flow rate Gsi) of the steam flow detector 53 is output to the control device 30. The cooling water temperature detector 54 detects the temperature of the cooling water when entering the refrigerator 28, and is provided upstream of the refrigerator 28 in the pipe 42. The detection value (cooling water temperature Tw) of the cooling water temperature detector 54 is output to the control device 30.

FIG. 4 is a block diagram showing the configuration of the control device 30.
In this figure, the control device 30 includes a gas turbine control unit 61, a cold water temperature control unit 62, and an intake air temperature control unit 63, and an atmospheric temperature detector 51, an intake air temperature detector 52, and a steam flow rate detector 53. The coolant temperature detector 54, the flow rate adjustment valve 31, the flow rate adjustment valve 32, and the flow rate adjustment valve 34 are connected. The detection values (Ta, Tao, Gsi, Tw) are input from the detectors 51, 52, 53, 54 to the control unit 30. The opening degree commands (Cv1, Cv2, Cv3) are output as operation signals from the control unit 30 to the flow rate adjusting valves 31, 32, 34, respectively. In addition, a power generation output command MWD for the power supply facility 200 is input to the control unit 30. This power generation output command MWD is determined based on the total amount of power required by the entire natural gas liquefaction plant, and is output from, for example, a plant control device (not shown) that controls the entire plant.

  The gas turbine control unit 61 is a part in charge of control when the gas turbine 22 is started and stopped or during load operation based on the power generation output command MWD, and includes a target fuel flow rate setting unit 64 and a flow rate adjustment valve control unit 65. Yes.

  The target fuel flow rate setting unit 64 is a part that determines a target output of the gas turbine 22 that satisfies the request of the power generation output command MWD and sets a fuel flow rate (target fuel flow rate) required to achieve the target output. The flow rate adjusting valve control unit 65 is a part that adjusts the opening degree of the flow rate adjusting valve 31 so that the fuel flow rate supplied to the combustor 21 approaches the target fuel flow rate. Is output.

  The chilled water temperature control unit 62 is responsible for controlling the temperature of the chilled water generated by the refrigerator 28 and includes a target steam flow rate setting unit 66 and a flow rate adjustment valve control unit 67.

  The target steam flow rate setting unit 66 is a part for setting a steam flow rate (target steam flow rate GsiD) to be supplied from the steam turbine 25 to the refrigerator 28 in order to maintain the temperature of the cold water generated by the refrigerator 28. A target steam flow rate GsiD is set based on the coolant temperature Tw input from the temperature detector 54. The flow rate adjusting valve control unit 67 is a part that adjusts the opening degree of the flow rate adjusting valve 32 so that the steam flow rate Gsi from the steam turbine 25 to the refrigerator 28 approaches the target steam flow rate GsiD. Command Cv2 is output.

  Generally, in a refrigerator, the response of the cold water temperature to a change in the temperature and flow rate of the heat source and the cooling water is slow, and there are some industrial large machines whose time constant exceeds one hour. Therefore, in the present embodiment, the temperature control of the cold water is performed in advance by adjusting the flow rate of the steam supplied to the refrigerator 28 based on the temperature change of the cooling water. Thereby, even when the cooling water temperature changes due to the atmospheric temperature change, the temperature change of the cold water at the outlet of the refrigerator 28 can be suppressed, so that the intake air cooling device 29 and the condenser 3 have a stable temperature. Cold water can be supplied.

  Here, an example of control performed by the cold water temperature control unit 62 will be described.

  The above equation (1) is for calculating the target steam flow rate GsiD, and consists of a function f1 and a function f2. The function f1 calculates a base value of the steam flow rate to be supplied to the refrigerator 28 based on the power generation output command MWD, and the function f2 is a steam based on the temperature Tw of the cooling water supplied to the refrigerator 28. The flow rate is corrected. The target steam flow rate setting unit 66 obtains the target steam flow rate GsiD from the power generation output command MWD and the cooling water temperature Tw using the formula (1).

  The above equation (2) is for calculating the opening degree command Cv2 from the target steam flow rate GsiD, and is corrected by feedback control so that the steam flow rate Gsi supplied to the refrigerator 28 matches the target steam flow rate GsiD. ing. In the equation (2), TTw is an integration time constant. The flow rate adjusting valve control unit 67 calculates the opening degree command Cv2 from the target steam flow rate GsiD and the steam flow rate Gsi obtained by the target steam flow rate setting unit 66 by using the equation (2), and sends the operation signal to the flow rate adjusting valve 32. Output. As a result, the flow rate adjustment valve 32 is adjusted to an opening degree corresponding to the opening degree command Cv2, so that the temperature of the cold water coming out of the refrigerator 28 can be maintained even if the cooling water temperature changes with the atmospheric temperature change. it can.

  In the above example, based on the control for setting the target steam flow rate GsiD based on the power generation output command MWD and the cooling water temperature Tw, the detection value of the steam flow rate detector 53 (steam flow rate Gsi), and the target steam flow rate GsiD. By performing control to adjust the opening degree of the flow rate adjustment valve 32, chilled water temperature control suitable for the operation state of the plant is performed. However, from the viewpoint of keeping the cold water temperature constant, it is sufficient to set the target steam flow rate GsiD based on the cooling water temperature Tw and to control the opening degree of the flow rate adjusting valve 32 based on the target steam flow rate GsiD. That is, if the control is simplified in this manner, the steam flow rate detector 53 can be omitted, and the configuration of the plant can be simplified.

  The intake air temperature control unit 63 is in charge of intake air temperature control when leaving the intake air cooling device 29, and includes a target intake air temperature setting unit 68, a target cold water flow rate setting unit 69, and a flow rate adjustment valve control unit 70. Yes.

  The target intake air temperature setting unit 68 is a part that sets an intake air temperature (target intake air temperature TaoD) suitable for the power generation output required for the gas turbine 22, and sets the target intake air temperature TaoD based on the power generation output command MWD. Yes. The target chilled water flow rate setting unit 69 is a part for setting a chilled water flow rate (target chilled water flow rate GwD) to be supplied from the refrigerator 28 to the intake air cooling device 29 in order to suppress the output fluctuation of the gas turbine 22 due to the atmospheric temperature change. The target cold water flow rate GwD is set so that the intake air temperature Tao input from the intake air temperature detector 52 approaches the target intake air temperature TaoD. The flow rate adjustment valve control unit 70 is a part that adjusts the flow rate adjustment valve 34 so that the cold water flow rate to the intake air cooling device 29 approaches the target cold water flow rate GwD, and outputs an opening degree command Cv3 to the flow rate adjustment valve 34. .

  Here, an example of control performed by the intake air temperature control unit 63 will be described.

  The above equation (3) includes a function f3 for calculating the target intake air temperature TaoD based on the power generation output command MWD. The target intake air temperature setting unit 68 obtains the target intake air temperature TaoD from the power generation output command MWD using Expression (3).

  The above equation (4) is for calculating the target cold water flow rate GwD from the target intake air temperature TaoD, and is composed of a function f4, a function f5, and a feedback function. The function f4 calculates the base value of the chilled water flow rate to be supplied to the intake air cooling device 29 based on the power generation output command MWD, and the function f5 corrects the chilled water flow rate based on the atmospheric temperature Ta. . The feedback function adds correction by feedback control to the cold water flow rate so that the intake air temperature Tao matches the target intake air temperature TaoD. Note that TTa in equation (4) is an integration time constant. The target chilled water flow rate setting unit 69 obtains the target chilled water flow rate GwD from the power generation output command MWD, the atmospheric temperature Ta, the intake air temperature Tao, and the target intake air temperature TaoD using the equation (4).

  The above equation (5) is composed of a function f6 for calculating the opening degree command Cv3 from the target cold water flow rate GwD. The flow rate adjustment valve control unit 70 calculates the opening degree command Cv3 from the target cold water flow rate GwD obtained by the target cold water flow rate setting unit 69 using the formula (5), and outputs the opening degree command Cv3 to the flow rate adjustment valve 34 as an operation signal. As a result, the flow rate adjustment valve 34 is adjusted to an opening corresponding to Cv3, so that the intake temperature of the gas turbine 22 can be maintained at the target intake air temperature TaoD even if the atmospheric temperature changes.

  In the above example, the control for calculating the target intake air temperature TaoD based on the power generation output command MWD and the control for calculating the target cold water flow rate GwD based on the power generation output command MWD, the atmospheric temperature Ta, and the target intake air temperature TaoD. By doing so, intake air temperature control suitable for the operation state of the plant is performed. However, from the viewpoint of maintaining the intake air temperature at the target intake air temperature TaoD, the target cold water flow rate GwD is set based on the target intake air temperature TaoD and the intake air temperature Tao, and the opening degree of the flow rate adjusting valve 34 is set based on the target cold water flow rate GwD. Control is sufficient. That is, if the control is simplified in this way, the atmospheric temperature detector 51 can be omitted, and the configuration of the plant can be simplified.

  In addition, the power supply facility 200A for the natural gas liquefaction plant according to the present embodiment is the same as that of the first embodiment, the gas-liquid separator 120, the main heat exchanger 140, and the refrigerant precooling facility 160. A natural gas liquefaction plant can be configured by cooperating with the above.

  In the natural gas liquefaction plant configured as described above, when the atmospheric temperature Ta rises due to changes in the season or day and night, the cooling water temperature Tw also rises, and the temperature of the cold water in the refrigerator 28 begins to drop. At this time, the control device 30 operates as follows in order to suppress a decrease in the cold water temperature.

  The target steam flow rate setting unit 66 in the chilled water temperature control unit 62 is supplied to the refrigerator 28 based on the cooling water temperature Tw input from the cooling water temperature detector 54 in order to maintain the temperature of the chilled water of the refrigerator 28. A target steam flow rate GsiD to be set is set, and this is output to the flow rate adjustment valve control unit 67. The flow rate adjustment valve control unit 67 to which the target steam flow rate GsiD is input calculates an opening degree command Cv2 from the target steam flow rate GsiD and adjusts the flow rate so that the steam flow rate to the refrigerator 28 approaches the target steam flow rate GsiD. An operation signal is output to the valve 32. The flow rate adjusting valve 32 that has received the opening degree command Cv2 from the flow rate adjusting valve control unit 67 is held at the specified opening degree, so that steam having a flow rate similar to the target steam flow rate GsiD is supplied to the refrigerator 28. Thereby, the control apparatus 30 can hold | maintain the cold water temperature from the refrigerator 28 even if atmospheric temperature Ta (cooling water temperature Tw) changes.

  The cold water generated by the refrigerator 28 is supplied to the condenser 3 and the intake air cooling device 29 in the refrigerant precooling facility 100 via the cold water header 35 while maintaining a constant temperature. Since the temperature of the cold water supplied to the condenser 3 is maintained by the control device 30 as described above even when the atmospheric temperature Ta changes, the condenser 3 condenses the second refrigerant while maintaining a constant condensation performance. You can continue.

  On the other hand, when the atmospheric temperature Ta changes as described above, the intake temperature of the gas turbine 22 increases, the load on the compressor 20 increases, and the turbine output begins to decrease. In order to suppress this, the control device 30 operates as follows.

  The target intake air temperature setting unit 68 in the intake air temperature control unit 63 sets the target intake air temperature TaoD based on the power generation output command MWD, and outputs this to the target cold water flow rate setting unit 69. The target chilled water flow rate setting unit 69 to which the target intake air temperature TaoD has been input, performs intake air cooling based on the intake air temperature Tao input from the intake air temperature detector 52 in order to maintain the intake air temperature of the gas turbine 22 at the target intake air temperature TaoD. A target cold water flow rate GwD to be supplied to the device 29 is set, and this is output to the flow rate adjustment valve control unit 70. The flow rate adjusting valve control unit 70 to which the target cold water flow rate GwD has been input calculates an opening degree command Cv3 from the target cold water flow rate GwD in order to bring the cold water flow rate to the intake air cooling device 29 closer to the target cold water flow rate GwD. An operation signal is output to the regulating valve 34. The flow rate adjustment valve 34 that has received the opening degree command Cv3 from the flow rate adjustment valve control unit 70 is held at the designated opening degree, so that chilled water having a flow rate approximately equal to the target chilled water flow rate GwD is supplied to the intake air cooling device 29. . At this time, since the cold water temperature is held by the cold water temperature control unit 62 as described above, the intake air temperature can be easily adjusted only by adjusting the flow rate of the cold water to the intake air cooling device 29. As described above, the control device 30 can maintain the intake air temperature Tao of the gas turbine 22 at the target intake air temperature TaoD even if the atmospheric temperature Ta (cooling water temperature Tw) changes.

Next, the effect of this embodiment will be described.
Generally, natural gas liquefaction plants are operated using a medium such as water or air that is affected by changes in the atmospheric temperature as refrigerant in a condenser or intake air of a gas turbine. Depending on the situation, the operating state of the equipment in the plant may fluctuate (for example, when the atmospheric temperature rises, the load on the compressor increases and the turbine output decreases, and air is used as the refrigerant for the condenser. In this case, the cooling performance of the condenser will be reduced). On the other hand, considering the quality and productivity of liquefied natural gas, which is a product of the plant, it is preferable to operate the equipment in the plant at a constant state at all times. There is a need for improved efficiency.

  Here, in addition to the configuration of the first embodiment, the natural gas liquefaction plant of the present embodiment includes a control device 30 that controls the intake air temperature of the gas turbine 22 and the cold water temperature of the refrigerator 28. . According to the natural gas liquefaction plant thus configured, even when the atmospheric temperature fluctuates and the cooling water temperature of the refrigerator 28 rises, the cold water temperature is maintained by adjusting the flow rate of steam supplied to the refrigerator 28. can do. Thereby, since the cooling performance of the condenser 3 can be maintained, the second refrigerant can be continuously cooled in a constant state. Further, according to the present embodiment, even when the atmospheric temperature fluctuates and the intake air temperature rises, the intake air temperature can be maintained by adjusting the flow rate of the cold water supplied to the intake air cooling device 29. As a result, an increase in the load of the compressor 20 is suppressed and the output of the gas turbine 22 can be maintained, so that constant power can be continuously supplied to the refrigerant compressor 28.

  Thus, according to the present embodiment, the output of the gas turbine 22 and the cooling performance of the condenser 3 can be maintained even when the atmospheric temperature changes, so the gas turbine 22 and the refrigerant precooling facility 100 are designed. Operation can be continued near the optimum value (performance planned point) set in step 1. As a result, even if the atmospheric temperature changes, the optimum plant operation can be performed, so that the plant operation efficiency can be improved.

Next, the effect of this embodiment will be described in detail from the viewpoint of the thermal efficiency of the plant.
FIG. 5 is a comparative table of steam balances in a power supply facility of a natural gas liquefaction plant according to a second embodiment of the present invention and a comparative example thereof.

  In this figure, “Ta” is the atmospheric temperature, “Gas turbine output” is the output of the gas turbine in the power supply facility, “Steam generation amount” is the steam generation amount in the boiler in the power supply facility, and “Tw” is the refrigerator. The cooling water temperature, “steam consumption” indicates the steam consumption in the refrigerator in the power equipment, and “steam balance” indicates the steam balance obtained by subtracting the steam consumption from the steam generation amount. The upper part of each case shows data when the atmospheric temperature is in a standard state (Ta = 15 ° C.), and the lower part shows data when the atmospheric temperature rises (Ta = 40 ° C.). In addition, the numerical values of “gas turbine output”, “steam generation amount”, and “steam consumption amount” are shown as change rates when the standard state (Ta = 15 ° C.) is used as a reference.

  Case 1 is a steam balance when the refrigerator 28, the intake air cooling device 29, and the control device 30 are omitted from the power supply facility 200A of the present embodiment, and cold water is not manufactured by the refrigerator 28. In this case, when the atmospheric temperature Ta rises from 15 ° C. (standard state) to 40 ° C., the output of the gas turbine is reduced by 21% due to an increase in the power of the compressor 20 due to the intake air temperature rise, and the amount of steam generated is 14% accordingly Decrease.

  Case 2 is a steam balance when the intake air cooling device 29 and the control device 30 are omitted from the power supply facility 200A of the present embodiment. In the power supply facility of this case, cold water is produced by the refrigerator 28 using the exhaust heat of the gas turbine 22 and is supplied to the condenser 3 of the refrigerant precooling facility 100. In this case, when the atmospheric temperature Ta rises to 40 ° C., the amount of generated steam is reduced by 14% as in the case 1. Further, as the atmospheric temperature Ta rises, the cooling water temperature Tw also rises to 36 ° C., so the steam consumption for producing cold water by the refrigerator 28 increases by 15%. Therefore, the steam balance of the entire plant results in 29% shortage compared to the standard state.

  Case 3 is a steam balance in the power supply facility 200A of the present embodiment. The power supply facility in this case controls the intake air cooling device 29 and the refrigerator 28 using the control device 30 as described above. In this case, when the atmospheric temperature rises, the intake air cooling device 29 is used to control the inlet air temperature (intake air temperature) of the compressor 20 so that it falls within a range of 1 ° C. above and below the standard state (ie, 14 to 16 ° C.). Suppose that In this case, the gas turbine output can be reduced by 1%, and the steam generation amount can be reduced by 3%. Further, since the cooling water temperature Tw rises, the steam consumption for producing the cold water by the refrigerator 28 increases by 15% as in the case 2, but the gas turbine 22 can be operated near the standard state. The steam balance can be kept at 18%.

  By the way, in the power supply equipment of the case 2 described above, when the steam balance is insufficient as the atmospheric temperature rises, the steam introduced from the pipe 41 to the condenser is throttled through the flow rate adjustment valve 32, so that the refrigerator It leads to 28 and eliminates the shortage of steam. For this reason, it is necessary to generate steam in consideration of the amount of steam required when the atmospheric temperature rises from the standard state so that the cold water temperature does not decrease even if the atmospheric temperature rises. However, in the standard state, the amount of steam is excessive, leading to a decrease in the thermal efficiency of the plant.

  In contrast, in the present embodiment, since the intake temperature of the gas turbine 22 can be held by the control device 30, the steam balance when the atmospheric temperature rises can be improved as described above. Thereby, since the surplus steam amount in the standard state can be reduced, the thermal efficiency of the plant can be improved.

  Further, when power is supplied to the refrigerant precooling facility 100 via the motor 2 as in the power supply facilities 200 and 200A in the above embodiments, the gas turbine 22 and the like are directly connected to the drive target. Compared with, it is possible to perform flexible power supply in accordance with the demand for equipment in the plant. Therefore, the power supply facilities 200 and 200A according to the present embodiment can be easily added to the existing plant. The motor 2 may be omitted, and the drive shafts of the refrigerant compressor 1, the compressor 20, and the gas turbine 22 may be shared, and the refrigerant compressor 1 may be directly driven using the gas turbine 22. . If the gas turbine 22 and its driving target are directly connected in this way, the driving target such as the refrigerant compressor 1 can be driven with higher efficiency than in the case of using a motor.

  In the second embodiment described above, only the case where the intake air temperature and the cold water temperature are controlled by the control device 30 has been described. However, it is of course possible to use a control method equivalent to the above. For example, an operation panel for displaying the current intake air temperature Tao and the coolant temperature Tw is separately provided, and the operator can adjust the opening degree of the flow rate adjusting valves 32, 34 and the like as appropriate while watching these temperatures. You may do it.

Claims (8)

A refrigerant compressor for compressing the refrigerant;
A condenser that cools and condenses the refrigerant compressed by the refrigerant compressor;
A liquid receiver for receiving the refrigerant condensed in the condenser;
In a power supply facility for a natural gas liquefaction plant that supplies power to a natural gas liquefaction plant comprising a cooler that expands the refrigerant from the receiver and cools other refrigerants,
A gas turbine driven by combustion gas obtained by burning fuel and intake air;
A boiler that generates steam from the exhaust gas from the gas turbine;
A steam turbine driven by steam from this boiler;
A refrigerator that generates cold water by steam from the steam turbine and cooling water;
An intake air cooling device that cools the intake air of the gas turbine with cold water from the refrigerator;
First flow rate adjusting means for adjusting a steam flow rate from the steam turbine to the refrigerator;
Second flow rate adjusting means for adjusting the flow rate of cold water from the refrigerator to the intake air cooling device;
A first temperature detector for detecting a temperature of cooling water when entering the refrigerator;
A second temperature detector for detecting the temperature of the intake air as it exits the intake air cooling device;
The first flow rate based on the detection value of the first temperature detector so that the steam flow rate from the steam turbine to the refrigerator approaches a target flow rate set to hold the temperature of the cold water generated by the refrigerator. While adjusting the opening degree of the adjusting means, the detected value of the second temperature detector is adjusted so that the temperature of the intake air when coming out of the intake air cooling device approaches the target temperature set for maintaining the output of the gas turbine. A control device for adjusting the opening of the second flow rate adjusting means based on ,
The refrigerant compressor is driven by power from at least one of the gas turbine and the steam turbine,
The power supply equipment for a natural gas liquefaction plant , wherein the condenser cools and condenses the refrigerant with cold water from the refrigerator . In the power supply equipment for a natural gas liquefaction plant according to claim 1 ,
The target temperature is set based on the output of the gas turbine, the power supply equipment for a natural gas liquefaction plant. In the power supply equipment for a natural gas liquefaction plant according to claim 1 or 2 ,
A third temperature detector for detecting the temperature of the intake air when entering the intake air cooling device;
The control device is configured to control the second temperature detector based on the detection value of the second temperature detector and the detection value of the third temperature detector so that the temperature of the intake air as it exits the intake air cooling device approaches the target temperature. A power supply facility for a natural gas liquefaction plant, wherein the opening degree of the flow rate adjusting means is adjusted. In the power supply equipment for a natural gas liquefaction plant according to claim 1 or 2 ,
A flow rate detector for detecting the flow rate of steam entering the refrigerator;
The control device adjusts the first flow rate based on a detection value of the first temperature detector and a detection value of the flow rate detector so that a steam flow rate from the steam turbine to the refrigerator approaches the target flow rate. A power supply facility for a natural gas liquefaction plant, wherein the opening degree of the means is adjusted. In the power supply equipment for a natural gas liquefaction plant according to claim 1,
The refrigerant compressor has a motor,
A power supply facility for a natural gas liquefaction plant, wherein the gas turbine supplies power to the refrigerant compressor via the motor. In the power supply equipment for a natural gas liquefaction plant according to claim 1,
The power supply equipment for a natural gas liquefaction plant, wherein the gas turbine is directly connected to the refrigerant compressor. In the power supply equipment for a natural gas liquefaction plant according to claim 1,
The power supply facility for a natural gas liquefaction plant, wherein the refrigerant is any one of propane, propylene, or a mixed refrigerant containing methane, propane, and ethane. A refrigerant compressor that compresses the refrigerant, a condenser that cools and condenses the refrigerant compressed by the refrigerant compressor, a liquid receiver that receives the refrigerant condensed by the condenser, and a refrigerant that is expanded from the liquid receiver To power a natural gas liquefaction plant with a cooler that cools other refrigerants,
A gas turbine that is driven by combustion gas obtained by burning fuel and intake air and supplies power to the natural gas liquefaction plant, a boiler that generates steam by exhaust gas from the gas turbine, and a steam that is driven by steam from the boiler A steam turbine that supplies power to the natural gas liquefaction plant, an intake air cooling device that cools intake air of the gas turbine, and cold water that is supplied to the intake air cooling device and the condenser is obtained by using steam and cooling water from the steam turbine. A refrigerator to be generated, a first flow rate adjusting means for adjusting a steam flow rate from the steam turbine to the refrigerator, and a second flow rate adjustment for adjusting a cold water flow rate from the refrigerator to the intake air cooling device Means, a first temperature detector for detecting the temperature of the cooling water as it enters the refrigerator, and an intake air as it exits the intake air cooling device. A control apparatus for motive power supply equipment and a second temperature detector for detecting the temperature of,
Based on the detection value of the first temperature detector, the steam flow rate from the steam turbine to the refrigerator approaches a target flow rate set to hold the temperature of the cold water generated by the refrigerator. A chilled water temperature control unit for adjusting the opening degree of the flow rate adjusting means;
Based on the detection value of the second temperature detector, the second flow rate adjusting means is arranged so that the temperature of the intake air as it exits the intake air cooling device approaches the target temperature set to maintain the output of the gas turbine. A control device for a power supply facility for a natural gas liquefaction plant, comprising: an intake air temperature control unit that adjusts an opening.

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