JP2013256925A - Method of controlling compressor, and compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of controlling a compressor, configured to suppress a variation of the pressure of gas supplied to a utilization process at a downstream side, and to provide the compressor.SOLUTION: A method of controlling a compressor includes the steps of: changing an opening degree of a discharge port 21 of a screw compressor 20 by being slid in the screw compressor 20 and changing a position of the slide; sliding a slide valve 22 for changing a compression capacity of the compressor 20 toward a prescribed target position; finding a difference between the target position and a position of the slide valve after the slide; and adjusting an opening degree of a spillback valve 13 according to the difference.

Description

  The present invention relates to a control method for a compression device provided with a screw compressor, and to a compression device provided with a screw compressor.

  Conventionally, a compression device described in Patent Document 1 is known. The compression device includes a screw compressor that compresses and discharges the gas flowing in from the inlet, a flow path adjustment valve, and a bypass flow path section that returns the gas discharged from the screw compressor to the inlet, A pressure gauge that measures the pressure (discharge pressure) of the gas discharged from the screw compressor, and a control unit that adjusts the discharge pressure of the screw compressor.

  The screw compressor has a slide valve, and the slide valve adjusts the compression capacity of the compressor by changing its opening degree. The control unit adjusts the opening of the flow rate adjusting valve and the opening of the slide valve based on the discharge pressure of the screw compressor (pressure of the discharged gas) measured by the pressure gauge, The pressure of the gas supplied to the use process connected to the downstream side by the compression device is controlled to a pressure (target pressure) required by the use process.

  Specifically, when the discharge pressure of the screw compressor becomes larger than the target pressure, the control unit increases the opening of the flow rate adjustment valve and returns it to the inlet side of the screw compressor by the bypass flow path unit. The discharge pressure of the screw compressor is lowered by increasing the flow rate of the generated gas. On the other hand, when the discharge pressure of the screw compressor becomes smaller than the target pressure, the control unit reduces the opening of the flow rate adjusting valve and returns the gas returned to the inlet side of the screw compressor by the bypass flow path unit. Increase the discharge pressure by reducing the flow rate of

  When the opening of the flow rate adjustment valve becomes larger than a predetermined range when reducing the discharge pressure, the control unit reduces the opening of the slide valve to reduce the compression capacity of the screw compressor. Is reduced to reduce the discharge flow rate of the gas from the screw compressor, thereby returning the opening degree of the flow rate adjusting valve to the predetermined range while lowering the discharge pressure. On the other hand, when the opening of the flow rate adjustment valve becomes smaller than a predetermined range when increasing the discharge pressure, the control unit increases the opening of the slide valve to reduce the compression capacity of the screw compressor. Is increased to increase the discharge flow rate of the gas from the screw compressor, thereby returning the opening of the flow rate adjustment valve to the predetermined range while increasing the discharge pressure.

Japanese Patent Publication No. 3-3078

  In the compression device, when the opening degree of the slide valve is adjusted, the gas discharge flow rate from the screw compressor may decrease (or increase) more than the target flow rate. In this case, like the compression device, after detecting a large decrease (or increase) in the discharge flow rate as a large decrease (or increase) in the discharge pressure with a pressure gauge, the opening degree of the flow rate adjustment valve is decreased or closed ( In the method in which the discharge pressure of the screw compressor is returned to the target pressure by increasing or fully opening the pressure, the pressure of the gas supplied from the compressor to the utilization process temporarily fluctuates greatly.

  Accordingly, in view of the above problems, the present invention provides a compression device equipped with a screw compressor, and a compression device control method and a compression device capable of suppressing pressure fluctuation of a gas supplied to a downstream use process. The issue is to provide.

  In order to solve the above-mentioned problems, the present invention has a screw compressor that compresses gas flowing into the inside from the inlet by a screw rotor and discharges the gas from the outlet, and a flow rate adjusting valve, and is discharged from the outlet. A method of controlling a compression device comprising a bypass flow path section for returning gas to the inlet, wherein a discharge process of gas from the screw compressor is connected to a downstream side of the compression device. A pressure adjusting step for adjusting the opening degree of the flow rate adjusting valve so as to be a target pressure that is a required pressure, and the opening degree is changed by sliding the inside of the screw compressor and changing the position thereof. A slide step of sliding a slide valve for changing a compression capacity of the compressor toward a predetermined target position; and a slide position after sliding in the target position and the slide step. It comprises a difference detection step of obtaining a difference between the position of the valve, and a variation suppressing step of adjusting the opening of the flow control valve in response to said difference. Then, when the opening degree of the flow rate adjustment valve deviates from a predetermined range in the pressure adjustment step, the slide step, the difference detection step, and the fluctuation suppression step are performed.

  The present invention is also a compression device capable of supplying compressed gas to a utilization process connected downstream, wherein the gas flowing into the interior from the inlet is compressed by a screw rotor and discharged from the outlet. A compressor, a bypass flow passage section that returns a gas discharged from the discharge port to the inflow port, and a pressure for measuring a discharge pressure that is a pressure of the gas discharged from the discharge port; A measurement unit; and a control unit that controls the pressure of the gas supplied to the utilization process. The screw compressor has a slide valve that slides inside the screw compressor and changes its position by changing its position, and also changes the compression capacity of the compressor. A pressure adjusting unit that adjusts an opening of the flow rate adjusting valve based on a measurement result by the pressure measuring unit, and a slide valve so that the discharge pressure becomes a target pressure that is a pressure required by the use process. A slide valve control unit that slides toward a predetermined target position, a difference detection unit that obtains a difference between the position of the slide valve after sliding by the slide valve control unit and the target position, and the difference detection unit. A fluctuation suppression control unit that adjusts the opening degree of the flow rate adjustment valve according to the difference, and the opening degree of the flow rate adjustment valve is adjusted in advance by the adjustment by the pressure adjustment unit. When out of the order was given range, the slide valve control unit, the difference detecting section, and the fluctuation suppressing unit, to operate the.

  According to these inventions, the discharge pressure is controlled using the slide valve when the discharge pressure is out of the predetermined range by the flow rate adjusting valve, so that the hunting (the delay operation of the flow rate adjusting valve is delayed). This can prevent the discharge pressure from undulating up and down.

  Moreover, even when the slide valve is slid from the target position, the difference between the target position and the actual slide valve position is obtained, and the opening of the flow rate adjustment valve is adjusted according to this difference. The fluctuation range of the discharge pressure (discharge flow rate) of the screw compressor due to the deviation of the slide valve from the target position can be effectively suppressed. That is, by detecting the deviation of the slide valve from the target position and adjusting the opening of the flow rate adjusting valve so as to suppress fluctuations in the discharge pressure (or discharge flow rate) of the screw compressor caused by this deviation, Before the discharge pressure (discharge flow rate) fluctuates significantly, it is returned to the target discharge pressure (pressure required by the use process, etc.). Compared to the case where the opening of the flow rate adjustment valve is adjusted so that this pressure (flow rate) fluctuation is detected and the pressure (flow rate) fluctuation is suppressed, the fluctuation range of the discharge pressure (discharge flow rate) is effectively suppressed. Can do.

  The utilization process connected to the downstream side of the compression device may be, for example, a gas turbine.

  Further, in the control method of the compression device, when the opening degree of the flow rate adjustment valve is out of a predetermined range and the opening degree of the slide valve is 80% or more and less than 100% in the pressure adjustment step. The slide process, the difference process, and the fluctuation suppressing process may be performed.

  When the opening degree of the slide valve is 80% or more and less than 100%, the variation in the discharge flow rate (discharge pressure) of the screw compressor accompanying the change in the opening degree of the slide valve is large. By performing the slide process, the differential process, and the fluctuation suppressing process when the percentage is greater than or equal to 100% and less than 100%, fluctuations in the discharge pressure (discharge flow rate) of the screw compressor are more effectively suppressed.

  Specifically, in the sliding step, after the slide valve is slid in the closing direction, when the discharge pressure is less than the target pressure and the discharge pressure decreases, the discharge pressure decreases with time. In order to continue away from the target pressure (see FIG. 3A), in such a case, the difference detection step and the fluctuation suppression step are performed, and thereby the discharge pressure (discharge flow rate) resulting from the difference is reduced. Suppresses the drop in discharge pressure (discharge flow rate) by suppressing a large drop.

  On the other hand, in the sliding step, after the slide valve is slid in the opening direction, when the discharge pressure is higher than the target pressure and the discharge pressure is increased, the discharge pressure continues to increase with time and the target In such a case, the difference detection step and the fluctuation suppression step are performed in order to further increase the discharge pressure (discharge flow rate) due to the difference, because the pressure is further away from the pressure (see FIG. 3B). Suppresses the range of increase in discharge pressure (discharge flow rate).

  From the above, the range of fluctuation in the discharge pressure (discharge flow rate) of the screw compressor is effectively suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the control method and compression apparatus of a compression apparatus which can suppress the pressure fluctuation of the gas supplied to a downstream utilization process can be provided.

It is a figure which shows the whole structure of the compression apparatus which concerns on this embodiment in the state connected to the utilization process. It is a functional block diagram of the control part of the said compression apparatus. It is a figure for demonstrating the fluctuation | variation of discharge pressure. It is a figure for demonstrating the relationship between the judgment start position and target position in a slide valve control part and a fluctuation | variation suppression control part in the case of sliding a slide valve. It is a figure which shows the flowchart of pressure control when the discharge pressure of a screw compressor becomes larger than target pressure in the said compression apparatus. It is a figure which shows the flowchart of pressure control when the discharge pressure of a screw compressor becomes smaller than target pressure in the said compression apparatus. It is a figure which shows the relationship between the opening degree of a slide valve, and the discharge flow volume of a screw compressor. (A) is a figure which shows an example of the change of the opening degree of the slide valve and spillback valve with progress of time in the said compression device, (B) is a slide valve shown by FIG. It is a figure which shows the change of the discharge pressure when the opening degree adjustment of a spillback valve is performed. (A) is a figure which shows an example of the change of the opening degree of the slide valve and spillback valve with progress of time in the conventional compressor, (B) is a slide valve shown by FIG. 9 (A). It is a figure which shows the change of the discharge pressure when the opening degree adjustment of a spillback valve is performed.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram illustrating an overall configuration of a compression apparatus according to the present embodiment in a state connected to a use process, and FIG. 2 is a functional block diagram of a control unit of the compression apparatus.

  The compression apparatus 10 of the present embodiment compresses the supplied gas and supplies a gas having a predetermined pressure (target pressure) to the utilization process 100 connected to the downstream side of the compression apparatus 10. For example, a gas turbine is connected to the compression apparatus 10 of the present embodiment as the utilization process 100. Then, the compressor 10 supplies a gas having a pressure (target pressure) required by the gas turbine 100.

  The compression device 10 includes a screw compressor 20, a bypass flow path unit 11, a pressure sensor (pressure measurement unit) 14, and a control unit 30.

  The screw compressor 20 includes a rotor chamber 21, a screw rotor (not shown), a rotor driving unit (not shown), a slide valve 22, and a slide valve driving unit 23. The screw compressor 20 of the present embodiment is supplied with gas through the inflow pipe 15 and supplies the gas compressed to a predetermined pressure to the gas turbine 100 through the discharge pipe 16.

  The rotor chamber 21 has an inlet 21a through which gas flows and an outlet 21b through which the gas is discharged, and a screw rotor is disposed therein. The inflow pipe 15 is connected to the inflow port 21a, and the discharge pipe 16 is connected to the discharge port 21b.

  The screw rotor (not shown) is rotationally driven by a rotor driving unit (not shown) while being arranged in the rotor chamber 21, thereby compressing the gas flowing into the rotor chamber 21 from the inlet 21 a and discharging the outlet 21 b. Discharge from.

  The slide valve 22 is provided in the rotor chamber 21 and changes the opening of the discharge port 21b and changes the compression capacity of the screw compressor 20 by sliding and changing its position.

  The slide valve drive unit 23 includes a drive unit 24 that slides the slide valve 22 and a position detector 25 that detects the position of the slide valve 22. The drive unit 24 is connected to the control unit 30 and slides (moves) the slide valve 22 in accordance with an instruction signal from the control unit 30. The drive unit 24 has, for example, a hydraulic cylinder, and slides the slide valve 22 with the hydraulic cylinder. The position detector 25 is connected to the control unit 30 and outputs a position signal corresponding to the detected position of the slide valve 22 to the control unit 30. This position detector 25 is attached to a hydraulic cylinder.

  The bypass flow path unit 11 includes a bypass pipe 12 and a spillback valve (flow rate adjustment valve) 13 and returns the gas discharged from the discharge port 21b to the inflow port 21a.

  The bypass pipe 12 has one end 12a connected to the inflow pipe 15 and the other end 12b connected to the discharge pipe 16, and the gas flowing through the discharge pipe 16 (the gas after being compressed by the screw compressor 20). ) Is formed to return a part of the gas to the inflow pipe 15.

  The spillback valve 13 is provided in the bypass pipe 12 and adjusts the flow rate of the gas flowing through the bypass pipe 12 by changing its opening degree. The spillback valve 13 is connected to the control unit 30 and changes its opening according to an opening signal from the control unit 30.

  The pressure sensor 14 measures the pressure (discharge pressure) of the gas discharged from the screw compressor 20 and outputs a pressure signal corresponding to the measurement result to the control unit 30. The pressure sensor 14 of the present embodiment is provided at a site downstream of the discharge port 21b and upstream of the site of the discharge pipe 16 where the other end 12b of the bypass pipe 12 is connected. The discharge pressure in this embodiment may be, for example, the gas pressure at the position of the discharge port 21b.

  The control unit 30 performs overall control of the compression apparatus 10 and includes, for example, a microcomputer including a microprocessor and a memory. And the control part 30 is for suppressing the pressure fluctuation of the gas supplied to the utilization process (this embodiment gas turbine) 100 connected to the downstream of the compression apparatus 10 stored in the memory etc., for example. By executing the pressure fluctuation suppression program, functionally, a pressure adjustment unit 32, a slide valve control unit 34, a difference detection unit 36, and a fluctuation suppression control unit 38 are provided.

  The pressure adjusting unit 32 adjusts the opening degree of the spillback valve 13 so that the discharge pressure of the screw compressor 20 becomes a set target pressure. The target pressure in the present embodiment is a pressure necessary for the gas turbine (utilization process connected to the downstream side of the compressor 10) 100.

  Specifically, the pressure adjusting unit 32 adjusts the discharge pressure by outputting an opening degree signal to the spillback valve 13 based on the pressure signal from the pressure sensor 14. Specifically, the pressure adjustment unit 32 reduces the opening of the spillback valve 13 when the discharge pressure measured by the pressure sensor 14 is lower than the target pressure. As a result, the flow rate of the gas returned from the discharge pipe 16 (discharge port 21b side) of the screw compressor 20 to the inflow pipe 15 (inflow port 21a side) through the bypass pipe 12 is reduced, and the flow rate of the gas flowing through the discharge pipe 16 is reduced. As a result, the pressure increases. On the other hand, the pressure adjustment unit 32 increases the opening of the spillback valve 13 when the discharge pressure measured by the pressure sensor 14 is higher than the target pressure. As a result, the flow rate of the gas returned from the discharge pipe 16 (discharge port 21b side) of the screw compressor 20 to the inflow pipe 15 (inflow port 21a side) through the bypass pipe 12 is increased, and the flow rate of the gas flowing through the discharge pipe 16 is increased. As a result, the pressure drops.

  Further, when the opening degree of the spillback valve 13 after the change is out of a predetermined range (GAP width), the pressure adjusting unit 32 outputs a signal to the slide valve control unit 34. In the present embodiment, the GAP width (predetermined range) is a range in which the opening degree of the spillback valve 13 is 85% or more and 95% or less. The GAP width is not limited to a range in which the opening degree of the spillback valve 13 is 85% or more and 95% or less, and is appropriately changed according to the specification of the compression device 10 or the like.

  When the opening degree of the spillback valve 13 deviates from the GAP width (that is, when a signal from the pressure adjustment unit 32 is received), the slide valve control unit 34 slides the slide valve 22 to remove from the screw compressor 20. Adjust the gas discharge flow rate.

  Specifically, when the opening degree of the spillback valve 13 exceeds the upper limit of the GAP width (95% in this embodiment), the slide valve control unit 34 instructs the slide valve drive unit 23 (specifically, the drive unit 24). A signal is output, and the slide valve 22 is slid (moved) to the unload side (the direction in which the discharge port 21b is closed or the opening degree is reduced) to reduce the compression capacity of the screw compressor 20, and thereby the screw The discharge flow rate of the compressor 20 is decreased. At this time, the slide valve control unit 34 sets a target position on the unload side, and slides the slide valve 22 toward the target position. In addition, the width | variety (distance) which slides the slide valve 22 at this time may be called an unloading width | variety below.

  The target position when sliding the slide valve 22 to the unload side is a predetermined opening degree (in this embodiment, from the opening degree of the slide valve 22 when the opening degree of the spillback valve 13 exceeds the upper limit of the GAP width). It is a position that is reduced by a predetermined opening degree within a range of 1% or more and 3% or less. Note that the distance (unload width) from the position before movement (sliding) to the target position (unload width) is not limited to 1% or more and 3% or less, and is appropriately set according to the specifications of the compression device 10 or the like.

  On the other hand, when the opening of the spillback valve 13 falls below the lower limit of the GAP width (85% in this embodiment), the slide valve control unit 34 sends an instruction signal to the slide valve drive unit 23 (specifically, the drive unit 24). The slide valve 22 is slid (moved) to the load side (the direction in which the discharge port 21b is opened or the opening degree is increased) to increase the compression capacity of the screw compressor 20, and thus the screw compressor 20 Increase the discharge flow rate. At this time, the slide valve control unit 34 slides the slide valve 22 toward the target position on the load side. In addition, the width | variety (distance) which slides the slide valve 22 at this time may be called a load width | variety below.

  The target position for sliding the slide valve 22 to the load side is a predetermined opening (1 in this embodiment) from the opening of the slide valve 22 when the opening of the spillback valve 13 falls below the upper limit of the GAP width. %) And a position that increases by a predetermined opening within a range of 3% or less. Note that the distance (load width) from the position before movement (sliding) to the target position is not limited to 1% or more and 3% or less, and is appropriately set according to the specifications of the compression device 10 or the like.

  When sliding the slide valve 22 as described above, the slide valve control unit 34 slides the slide valve 22 while appropriately checking the position of the slide valve 22 based on the position signal from the position detector 25. Specifically, the slide valve control unit 34 further outputs an instruction signal to the slide valve drive unit 23 when the slide valve 22 has not reached the target position when the slide valve 22 is slid. Then, the slide valve 22 is slid to the target position side. By repeating this, the slide valve control unit 34 reaches or exceeds the target position of the slide valve 22 (below the target position when sliding to the unload side / when sliding to the load side. Slide the slide valve 22 until it exceeds the target position. The cause of the slide valve 22 exceeding the target position is due to a mechanical error of the slide valve drive unit 23.

  The difference detector 36 obtains the difference between the position of the slide valve 22 after the slide and the target position based on the position signal from the position detector 25 and the target position set by the slide valve controller 34. Specifically, when the slide valve 22 slides to the unload side, the difference detection unit 36 determines that the slide valve 22 is less than the target position (the opening is smaller than the target position). The difference between the position and the target position is obtained. Further, when the slide valve 22 slides to the load side, the difference detection unit 36 determines the position of the slide valve 22 and the target when the slide valve 22 exceeds the target position (the opening is larger than the target position). Find the difference from the position.

  The fluctuation suppression control unit 38 determines the opening degree of the spillback valve 13 in preference to the pressure adjustment unit 32 when it is determined that the discharge pressure is separated from the target pressure after the slide valve 22 is slid by the slide valve control unit 34. On the other hand, when it is determined that the discharge pressure does not deviate from the target pressure after the slide valve 22 is slid by the slide valve control unit 34, the opening degree of the spillback valve 13 is not adjusted. The fluctuation suppression control unit 38 adjusts the opening degree of the spillback valve 13 according to the difference obtained by the difference detection unit 36. When the difference is detected (obtained) when the slide valve 22 is slid to the load side, the fluctuation suppression control unit 38 of the present embodiment reduces the opening of the spillback valve 13 by 3%, and the slide valve 22. When the difference is detected (obtained) when the valve is slid to the unload side, the opening of the spillback valve 13 is increased by 3%. The opening width of the spillback valve 13 that is changed by the fluctuation suppression control unit 38 is not limited to 3% (a constant value). The fluctuation suppression control unit 38 may adjust the opening of the spillback valve 13 so as to correspond to the change in the discharge flow rate (discharge pressure) of the screw compressor 20 due to the difference.

  Specifically, when the slide valve 22 is slid to the unload side, the fluctuation suppression control unit 38 causes the discharge pressure measured by the pressure sensor 14 to fall below the target pressure after the slide valve 22 slides, and the discharge pressure. Is lowered, the opening degree signal is output to the spillback valve 13 to reduce the opening degree.

  As described above, when the discharge pressure is lower than the target pressure and the discharge pressure is lowered after the slide valve 22 is slid to the unload side, as time passes, as shown in FIG. It can be predicted that the discharge pressure continues to decrease and moves away from the target pressure. For this reason, the compression device 10 (variation suppression control unit 38) of the present embodiment spills back before the discharge pressure significantly decreases in such a case (when the discharge pressure is less than the target pressure and the discharge pressure is reduced). By reducing the opening of the valve 13 and increasing the flow rate of the gas flowing through the discharge pipe 16, the discharge pressure (discharge flow rate) due to the difference is prevented from greatly decreasing and the discharge pressure drop is reduced. Increase pressure to target pressure. The determination as to whether or not the discharge pressure in the fluctuation suppression control unit 38 is decreasing is made based on, for example, whether or not the change or rate of change of the discharge pressure with the passage of time is negative. That is, the fluctuation suppression control unit 38 determines that the discharge pressure has decreased when the change or rate of change of the discharge pressure is negative.

  The fluctuation suppression control unit 38 of the present embodiment reduces the opening of the spillback valve 13 by 3% when the discharge pressure measured by the pressure sensor 14 is lower than the target pressure and the discharge pressure decreases after the slide valve 22 slides. . In addition, the change width | variety of this opening degree is not limited. The change width of the opening is appropriately set based on the discharge pressure and the position of the slide valve 22.

  On the other hand, when the slide valve 22 is slid to the load side, the fluctuation suppression control unit 38 spills when the discharge pressure measured by the pressure sensor 14 exceeds the target pressure and the discharge pressure increases after the slide valve 22 slides. An opening signal is output to the back valve 13 to increase the opening.

  In this way, after the slide valve 22 is slid to the load side, when the discharge pressure is higher than the target pressure and the discharge pressure is increased, the discharge is performed as time passes as shown in FIG. It can be predicted that the pressure will continue to rise and move away from the target pressure. For this reason, the compressor 10 (variation suppression control unit 38) of the present embodiment spills back before the discharge pressure rises greatly in such a case (when the discharge pressure is higher than the target pressure and the discharge pressure is increased). By increasing the opening degree of the valve 13 and decreasing the flow rate of the gas flowing through the discharge pipe 16, the discharge pressure is largely increased by suppressing a large increase in the discharge pressure due to the difference, and the discharge pressure is set to the target pressure. To lower. The determination as to whether or not the discharge pressure in the fluctuation suppression control unit 38 is increasing is made, for example, based on whether or not the change or rate of change of the discharge pressure over time is positive. That is, the fluctuation suppression control unit 38 determines that the discharge pressure is increasing when the change or rate of change of the discharge pressure is positive.

  The fluctuation suppression control unit 38 of the present embodiment increases the opening of the spillback valve 13 by 3% when the discharge pressure measured by the pressure sensor 14 exceeds the target pressure and the discharge pressure increases after the slide valve 22 slides. . In addition, the change width | variety of this opening degree is not limited. The change width of the opening is appropriately set based on the discharge pressure and the position of the slide valve 22.

  Determination of whether or not the slide valve 22 has exceeded the target position in the slide valve control unit 34, and determination of whether or not the discharge pressure in the fluctuation suppression control unit 38 is lower than the target pressure and the change rate of the discharge pressure is negative The determination (or whether or not the discharge pressure exceeds the target pressure and the rate of change of the discharge pressure is positive) cannot be determined in time when the slide valve 22 starts after reaching the target position. For this reason, the slide valve control unit 34 and the fluctuation suppression control unit 38 are configured so that the slide valve 22 is located at a position before the target position (in this embodiment, a position 0.6% before the opening: FIG. 4 (A) and FIG. 4 (B) (see determination start position), the above determinations (including measurement of discharge pressure and detection of slide valve position necessary for the above determination) are started. The position at which this determination is started (determination start position) is not limited to a position that is 0.6% before the target position in the slide direction. In the present embodiment, since the load width or unload width of the slide valve 22 is 1% or more and 3% or less, the distance from the target position to the determination start position is 0.5% or more in terms of the opening degree of the slide valve 22. Further, it is preferably 1.5% or less, but is not limited to this, and may be appropriately changed depending on the specifications of the compression device 10 or the like.

  Hereinafter, the pressure control of the gas when the compressed apparatus 10 supplies the compressed gas to the gas turbine 100 connected to the downstream side thereof will be described. First, the discharge pressure of the screw compressor 20 is higher than the target pressure. Will be described based on the flowchart shown in FIG.

  The pressure adjusting unit 32 increases the opening of the spillback valve 13 and increases the flow rate of the gas returning from the discharge pipe 16 to the inflow pipe 15. At this time, when the pressure adjustment unit 32 determines that the opening of the spillback valve 13 exceeds the upper limit of the GAP width (step S1: Yes), the pressure adjustment unit 32 outputs a signal to the slide valve control unit 34. If the opening of the spillback valve 13 is within the GPA range (step S1: No), the pressure adjusting unit 32 adjusts the opening of the spillback valve 13 based on the measurement result of the pressure sensor 14. The determination whether the opening degree exceeds the upper limit of the GAP width is repeated.

  Subsequently, the slide valve control unit 34 sets a target position on the unload side, and slides the slide valve 22 toward the target position (that is, slides the slide valve 22 to the unload side). When the slide valve control unit 34 determines that the slide valve 22 has reached or falls below the target position (step S2: Yes), the difference detection unit 36 obtains a difference between the target position and the position of the slide valve 22. When the difference is detected (step S3: Yes), the fluctuation suppression control unit 38 compares the discharge pressure with the target pressure, and determines that the discharge pressure is lower than the target pressure (step S4: Yes), the discharge pressure. Find the rate of change. If the change rate of the discharge pressure is negative (less than 0) (step S5: Yes), the fluctuation suppression control unit 38 reduces the opening of the spillback valve 13 by 3% (step S6). Thereby, in the said compression apparatus 10, before the big fall (fall much larger than the fall of the target pressure) of the discharge pressure (discharge flow rate) of the screw compressor 20 resulting from the slide valve 22 being less than a target position arises. Further, by reducing the opening degree of the spillback valve 13 and increasing the flow rate of the gas flowing through the discharge pipe 16, it is possible to suppress the large decrease in the discharge pressure and suppress the width of the decrease in the discharge pressure.

  If the slide valve control unit 34 determines in step S2 that the slide valve 22 has not reached the target position (step S2: No), the slide valve control unit 34 performs the determination in step S2 again after a predetermined time, This determination is repeated until the slide valve 22 reaches the target position or falls below the target position. Further, when it is determined in step S4 that the discharge pressure is equal to or higher than the target value (step S4: No), and when it is determined in step S5 that the change rate of the discharge pressure is 0 or higher (step S5: No). Return to step S1. Further, step S4 and step S5 may be performed in the reverse order or may be performed in parallel.

  Next, the case where the discharge pressure of the screw compressor 20 becomes smaller than the target pressure will be described based on the flowchart shown in FIG.

  The pressure adjusting unit 32 reduces the opening of the spillback valve 13 to reduce the flow rate of the gas returning from the discharge pipe 16 to the inflow pipe 15. At this time, if the pressure adjustment unit 32 determines that the opening degree of the spillback valve 13 is below the lower limit of the GAP width (step S11: Yes), the pressure adjustment unit 32 outputs a signal to the slide valve control unit 34. If the opening of the spillback valve 13 is within the GPA range (step S11: No), the pressure adjusting unit 32 adjusts the opening of the spillback valve 13 based on the measurement result of the pressure sensor 14. The determination as to whether the opening is below the lower limit of the GAP width is repeated.

  Subsequently, the slide valve control unit 34 sets a target position on the load side, and slides the slide valve 22 toward the target position (that is, slides the slide valve 22 to the load side). When the slide valve control unit 34 determines that the slide valve 22 has reached or exceeded the target position (step S12: Yes), the difference detection unit obtains a difference between the target position and the position of the slide valve 22. When the difference is detected (step S13: Yes), the fluctuation suppression control unit 38 compares the discharge pressure with the target pressure, and determines that the discharge pressure exceeds the target pressure (step S14: Yes), the discharge pressure. Find the rate of change. If the change rate of the discharge pressure is positive (greater than 0) (step S15: Yes), the fluctuation suppression control unit 38 increases the opening degree of the spillback valve 13 by 3% (step S16). As a result, in the compression device 10, before a large increase in the discharge pressure (discharge flow rate) of the screw compressor 20 due to the slide valve 22 exceeding the target position (an increase greater than the target pressure increase) occurs. Further, by increasing the opening degree of the spillback valve 13 and decreasing the flow rate of the gas flowing through the discharge pipe 16, the increase in the large discharge pressure can be suppressed and the increase in the discharge pressure can be suppressed.

  When the slide valve control unit 34 determines in step S12 that the slide valve 22 has not reached the target position (step S12: No), the slide valve control unit 34 performs the determination in step S12 again after a predetermined time, This determination is repeated until the slide valve 22 reaches the target position or exceeds the target position. Further, when it is determined in step S14 that the discharge pressure is equal to or less than the target value (step S14: No), and when it is determined in step S15 that the change rate of the discharge pressure is 0 or less (step S15: No). Return to step S11. Further, step S14 and step S15 may be performed in reverse order, or may be performed in parallel.

  According to the compressor 10 described above, even if the slide valve 22 is displaced from the target position when the slide valve 22 is slid, the difference between the target position and the actual position of the slide valve 22 is obtained and the spillback valve 13 corresponding to this difference is obtained. Therefore, the pressure fluctuation range of the discharge pressure of the screw compressor 20 due to the deviation of the slide valve 22 from the target position can be effectively suppressed.

  That is, the opening degree of the spillback valve 13 is adjusted so as to detect the deviation of the slide valve 22 from the target position and suppress the fluctuation of the discharge pressure (discharge flow rate) of the screw compressor 20 caused by this deviation. Is returned to the original discharge pressure (target pressure) before the discharge pressure fluctuates greatly, so that after the large fluctuation of the discharge pressure is detected as in the prior art, the flow rate adjustment valve is configured to suppress the pressure fluctuation. As compared with the case where the opening degree of is adjusted, the fluctuation range of the discharge pressure can be effectively suppressed.

  For this reason, by using the compression device 10 of the present embodiment as the supply source of the compressed gas of the load device such as the gas turbine 100, the load device (utilization process) can be operated stably and with maximum efficiency.

  Further, in the compression device 10 of the present embodiment, normally, the discharge pressure of the screw compressor 20 is controlled by the spillback valve 13 (when the opening of the spillback valve 13 is within the GAP width), and in this control, the spill is controlled. When the opening degree of the back valve 13 deviates from the GAP width, the discharge pressure control using the slide valve 22 is also performed. For this reason, in the said compression apparatus 10, the frequency of the opening degree adjustment of the slide valve 22 can be suppressed. Thus, since the screw compressor 20 is provided so that the compression capacity can be changed, generally, the wear of the slide valve 22 that is difficult to perform maintenance such as replacement compared to the spillback valve 13 provided in the bypass pipe 12 is reduced. The frequency of maintenance of the slide valve 22 can be suppressed.

  In addition, the control method and compression apparatus of the compression apparatus of this invention are not limited to the said embodiment, Of course, it can add various changes within the range which does not deviate from the summary of this invention.

  In the compression device 10 of the above embodiment, since the discharge pressure and the flow rate of the gas flowing through the discharge pipe 16 are in a proportional relationship, the pressure sensor 14 measures the change in the discharge flow rate of the screw compressor 20 as a pressure change. The slide valve 22 and the spillback valve 13 are controlled based on the above, but the present invention is not limited to this configuration. The compression device is provided with a flow rate sensor instead of the pressure sensor 14, and the flow rate of the gas discharged from the screw compressor 20 is directly measured, and the slide valve 22 and the spillback valve 13 are controlled based on this flow rate. May be.

  In the compression device 10 of the above-described embodiment, the opening degree of the slide valve is adjusted when the opening degree of the spillback valve deviates from the GAP width regardless of the opening degree of the slide valve, but is not limited to this configuration. For example, the compression device adjusts the opening of the slide valve 22 and adjusts the position of the slide valve when the opening of the spillback valve 13 deviates from the GAP width and the opening of the slide valve 22 is 80% or more and less than 100%. The opening degree of the spillback valve 13 may be adjusted according to the difference between the target position and the target position.

  This is because, as shown in FIG. 7, the relationship between the opening of the slide valve 22 and the discharge flow rate of the screw compressor 20 is not proportional, and the change in the discharge flow rate increases as the opening of the slide valve 22 increases. By adjusting the opening of the slide valve 22 and adjusting the opening of the spillback valve 13 according to the difference in the region where the change in the discharge flow rate is large, the pressure fluctuation range of the discharge pressure is effectively reduced. Can be suppressed.

  Specifically, when the opening adjustment of the slide valve 22 is performed in a region where the change in the discharge flow rate is small (a region where the opening of the slide valve 22 is small (for example, around the left side Δx in the graph of FIG. 7)) The opening control of the spillback valve 13 corresponding to the difference is not performed as in the compressor 10 of the embodiment, and the change ΔL1 is detected after the change ΔL1 in the discharge pressure (discharge flow rate) occurs as in the conventional compressor. Even if the spillback valve 13 is controlled, since the change ΔL1 in the discharge pressure is small, the pressure fluctuation range of the gas supplied to the utilization process 100 is small. On the other hand, when the opening adjustment of the slide valve 22 is performed in a region where the change in the discharge flow rate is large (a region where the opening of the slide valve 22 is large (for example, around the right side Δx in the graph of FIG. 7)) Since the opening degree control of the spillback valve 13 according to the difference is not performed as in the compressor 10 of the above embodiment, the change ΔL2 occurs after a change ΔL2 in the discharge pressure (discharge flow rate) occurs as in the conventional compressor. Is detected and the spillback valve 13 is controlled, the change ΔL2 in the discharge pressure is large, and therefore the width of the pressure fluctuation of the gas supplied to the utilization process 100 becomes large. For this reason, when the opening degree of the slide valve 22 is in the range of 80% or more and less than 100% (that is, in a region where the change in the discharge flow rate accompanying the change in the opening degree of the slide valve 22 is large), By controlling the spillback valve 13 according to the difference together with the adjustment, it is possible to suitably suppress the width of the pressure fluctuation of the gas supplied to the utilization process 100. The slide valve 22 may adjust the opening degree of the inlet 21 a of the rotor chamber 21.

Here, in order to confirm the effect of the compression device of the above embodiment, the pressure fluctuation of the gas supplied to the utilization process was examined by simulation assuming the following compression devices A1 and A2.
A1: Compressor of the above embodiment A2: The configuration other than the control unit is the same as the compressor of the above embodiment, and after the opening of the slide valve is adjusted, the discharge pressure of the screw compressor varies. The compression device (conventional compression device) in which the fluctuation is detected and control is performed to adjust the opening of the spillback valve based on the detected fluctuation.

  The results are shown in FIGS. 8 (A) to 9 (B). FIG. 8A is a diagram showing changes in the opening degree of the slide valve and the spillback valve with the passage of time in the compression device A1, and FIG. 8B is a diagram showing the change in the compression device A1. It is a figure which shows the change of the discharge pressure when the opening degree adjustment of the slide valve and spillback valve shown by FIG. 8 (A) is performed. FIG. 9A is a diagram showing changes in the opening degree of the slide valve and the spillback valve with the passage of time in the compression device A2, and FIG. 9B is a diagram in the compression device A2. It is a figure which shows the change of the discharge pressure when the opening degree adjustment of the slide valve and spillback valve shown by FIG. 9 (A) is performed.

  From this result, in the compression device A1, the pressure fluctuation range (0.019 MPaG in FIG. 8B) after the slide valve is slid to the unload side is the slide in the compression device A2. It was confirmed that the pressure fluctuation range of the discharge pressure after sliding the valve to the unload side (0.042 MPaG in FIG. 9B) was smaller.

  Moreover, in said compression apparatus A1, after the slide valve is slid to the unload side, the change width of the opening degree of the spillback valve is that after the slide valve in the above-mentioned compression apparatus A2 is slid to the unload side. It was also confirmed that it was smaller than the change width of the spillback valve opening.

DESCRIPTION OF SYMBOLS 10 Compressor 11 Bypass flow path part 12 Bypass pipe 13 Spillback valve (flow rate adjustment valve)
14 Pressure sensor (pressure measuring part)
20 Screw compressor 21 Rotor chamber 21a Inlet 21b Discharge port 22 Slide valve 25 Position detector 30 Control unit 32 Pressure adjustment unit 34 Slide valve control unit 36 Difference detection unit 38 Fluctuation suppression control unit 100 Gas turbine (utilization process)

Claims (6)

A screw compressor that compresses the gas flowing into the inside from the inlet by a screw rotor and discharges it from the outlet, and a bypass flow path section that has a flow rate adjusting valve and returns the gas discharged from the outlet to the inlet A method of controlling a compression device comprising:
A pressure adjustment step of adjusting the opening of the flow rate adjustment valve so that the gas discharge pressure from the screw compressor becomes a target pressure that is a pressure required by a use process connected downstream of the compression device; ,
A slide step of sliding the slide valve for changing the compression capacity of the compressor while changing the opening by sliding in the screw compressor and changing the position thereof, aiming at a predetermined target position;
A difference detecting step for obtaining a difference between the target position and the position of the slide valve after sliding in the sliding step;
And a fluctuation suppressing step of adjusting the opening of the flow rate adjusting valve according to the difference,
A control method for a compression device, wherein the slide step, the difference detection step, and the fluctuation suppression step are performed when the opening of the flow rate adjustment valve is out of a predetermined range in the pressure adjustment step.   In the pressure adjustment step, when the opening of the flow rate adjustment valve is out of a predetermined range and the opening of the slide valve is 80% or more and less than 100%, the sliding step, the difference step, and The method for controlling a compression device according to claim 1, wherein the fluctuation suppressing step is performed.   2. The difference detection step and the fluctuation suppression step are performed when the discharge pressure is less than the target pressure and the discharge pressure is lowered after the slide valve is slid in the closing direction in the slide step. 3. A method for controlling a compression device according to 2.   In the slide step, after the slide valve is slid in the opening direction, the difference detection step and the fluctuation suppression step are performed when the discharge pressure is larger than the target pressure and the discharge pressure is increased. The control method of the compression apparatus of any one of 3. A compression device capable of supplying compressed gas to a utilization process connected downstream,
A screw compressor that compresses the gas flowing into the inside from the inflow port with a screw rotor and discharges the gas from the discharge port;
A bypass flow path portion having a flow rate adjustment valve and returning the gas discharged from the discharge port to the inflow port;
A pressure measuring unit for measuring a discharge pressure which is a pressure of a gas discharged from the discharge port;
A control unit for controlling the pressure of the gas supplied to the utilization process,
The screw compressor has a slide valve that slides inside the screw compressor and changes its position by changing its position and changes the compression capacity of the compressor,
The controller is
A pressure adjusting unit that adjusts the opening of the flow rate adjusting valve based on a measurement result by the pressure measuring unit so that the discharge pressure becomes a target pressure that is a pressure required by the use process;
A slide valve control unit that slides the slide valve toward a predetermined target position;
A difference detection unit for obtaining a difference between the position of the slide valve after sliding by the slide valve control unit and the target position;
A fluctuation suppression control unit that adjusts the opening of the flow rate adjustment valve according to the difference obtained by the difference detection unit;
A compression device that operates the slide valve control unit, the difference detection unit, and the fluctuation suppression unit when the opening of the flow rate adjustment valve deviates from a predetermined range by adjustment by the pressure adjustment unit. . The compression apparatus according to claim 5, wherein the utilization process connected to the downstream side is a gas turbine.

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