Compressor train for chemical plant and method of operating compressor train for chemical plant

Abstract

Provided is a compressor train for chemical plants, said compressor train comprising: a compression unit that is driven to compress a process gas of a chemical plant; a steam turbine that is rotated by steam generated in association with the treatment of the process gas of the chemical plant and drives the compression unit ; a motor that is capable of assisting the rotation of the steam turbine; and a frequency conversion unit that is connected to an electrical system and controls the rotation of the motor.

Description

[Technical Field]

[0001] The present disclosure relates to a compressor train for a chemical plant and a method of operating a compressor train for a chemical plant. This application claims priority to Japanese Patent Application No. 2021-155311, filed on September 24, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] For example, Patent Document 1 discloses a compressor system for ammonia production used in an ammonia plant, which is a chemical plant that produces ammonia. This compressor system for producing ammonia includes low-pressure and high-pressure compressors (hereinafter referred to as compression sections), and a driver (steam turbine) that drives the compression sections. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-154020 Summary of the Invention [Problem to be solved by the invention]

[0004] In a chemical plant such as an ammonia plant, when the rated rotation speed of the compression section is increased or when the amount of steam generated in the manufacturing process is reduced, the amount of steam introduced into the steam turbine may be insufficient for the amount of steam required for the rated rotation of the compression section.

[0005] In this case, the technology described in Patent Document 1 has difficulty in stabilizing the rotation speed of the compressor section, and there is a problem specific to chemical plants in that the pressure of the process gas compressed by the compressor section is unstable.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a compressor train for a chemical plant that can stabilize the pressure of process gas compressed by a compression section, and an operating method for a compressor train for a chemical plant. [Means for solving the problem]

[0007] In order to solve the above problems, a compressor train for a chemical plant according to the present disclosure includes a compression unit that is driven to compress process gas in the chemical plant, a steam turbine that is rotated by steam generated in the treatment of the process gas in the chemical plant to drive the compression unit, a motor that can assist the rotation of the steam turbine, and a frequency conversion unit that is connected to an electric power system and controls the rotation of the motor. The steam turbine includes a shaft seal device that seals a gap between a stator of the steam turbine and a rotor of the steam turbine, a vacuum pump that can reduce the pressure inside the steam turbine by being driven, and a control device that controls the operating status of the steam turbine, wherein the control device has: a vacuum pump drive unit that drives the vacuum pump to reduce the pressure inside the steam turbine when the flow of steam generated in the processing of the process gas into the steam turbine is stopped; a motor start unit that starts driving the motor to drive the steam turbine when the pressure inside the steam turbine is reduced and the flow of steam into the steam turbine is stopped; a motor drive unit that continues to drive the motor; and a steam switching unit that starts the flow of steam into the steam turbine when the amount of steam generated in the processing of the process gas becomes equal to or greater than a specified amount while the motor continues to drive. .

[0008] A method for operating a compressor train for a chemical plant according to the present disclosure includes: a compressor that compresses process gas in a chemical plant when driven; a steam turbine that drives the compressor when rotated by steam generated in the treatment of the process gas in the chemical plant; a motor that can assist the rotation of the steam turbine; a frequency converter that is connected to an electric power system and controls the rotation of the motor; a shaft seal device that seals a gap between a stator of the steam turbine and a rotor of the steam turbine; and a vacuum pump that can reduce the pressure inside the steam turbine when driven. A method for operating a compressor train for a chemical plant includes: a vacuum pumping process for reducing the pressure inside the steam turbine by driving the vacuum pump while the flow of steam generated in the treatment of the process gas into the steam turbine is stopped; a motor starting process for starting to drive the motor to start driving the steam turbine after the vacuum pumping process is completed while the flow of steam into the steam turbine is stopped; a motor driving process for continuing to drive the motor after the motor starting process is completed; and a first steam switching process for starting the flow of steam into the steam turbine when the amount of steam generated in the motor while it is continuing to drive becomes equal to or greater than a specified amount. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a compressor train for a chemical plant and an operating method of a compressor train for a chemical plant that can stabilize the pressure of process gas compressed by a compression section. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a compressor train for a chemical plant according to a first embodiment of the present disclosure. [Figure 2] FIG. 4 is a schematic diagram showing the configuration of a compressor train for a chemical plant according to a second embodiment of the present disclosure. [Figure 3] FIG. 10 is a schematic diagram showing the configuration of a compressor train for a chemical plant according to a third embodiment of the present disclosure. [Figure 4] FIG. 10 is a diagram showing a main part (system) of a configuration of a compressor train for a chemical plant according to a fourth embodiment of the present disclosure. [Figure 5] FIG. 10 is a diagram showing the configuration of a shaft sealing device according to a fourth embodiment of the present disclosure. [Figure 6] 10 is a flowchart illustrating a method for operating a compressor train for a chemical plant according to a fourth embodiment of the present disclosure. [Figure 7] FIG. 10 is a functional block diagram of a control device according to a fourth embodiment of the present disclosure. [Figure 8] 10 is a flowchart illustrating an operation of a control device according to a fourth embodiment of the present disclosure. [Figure 9] FIG. 1 is a hardware configuration diagram illustrating a configuration of a computer according to an embodiment of the present disclosure. [Figure 10] FIG. 10 is a schematic diagram showing the configuration of a compressor train for a chemical plant according to another embodiment of the present disclosure. [Figure 11] FIG. 10 is a schematic diagram showing the configuration of a compressor train for a chemical plant according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a compressor train for a chemical plant and an operating method of a compressor train for a chemical plant according to an embodiment of the present disclosure will be described with reference to the drawings.

[0012] [First embodiment] (Compressor train for chemical plants) A compressor train for a chemical plant compresses process gas generated in the chemical plant and supplies the compressed process gas to a reaction device installed in the chemical plant.

[0013] When the chemical plant is an ammonia plant, the reaction device can be, for example, an ammonia converter that produces ammonia through a chemical reaction at high temperature and pressure, and the process gas can be, for example, a gas containing hydrogen as a main component. The chemical plant in this embodiment is an ammonia plant that produces ammonia.

[0014] As shown in FIG. 1, the ammonia plant 100 includes a chemical plant compressor train 1, an ammonia converter 200, a gas inlet line 20a, a gas outlet line 20c, a first power purchase cable 61a, and a second power purchase cable 61b.

[0015] The compressor train 1 for a chemical plant includes a compression section 20, a steam turbine 30, a speed increaser 40, a motor 50, a frequency conversion section 60, a steam inlet line 201, and a steam outlet line 202.

[0016] (Compression section) The compression section 20 compresses the process gas P supplied from the outside and used in the ammonia plant 100 , and supplies the compressed process gas P to the ammonia converter 200 .

[0017] The compression section 20 includes a low-pressure compressor (LPC) 21, a high-pressure compressor (HPC) 22, and an intermediate line 20b.

[0018] The low-pressure stage compressor 21 is a rotary machine that increases the pressure of the process gas P supplied from the outside to a predetermined first pressure value. The low-pressure stage compressor 21 has a first casing 21a and a first rotor 21b.

[0019] The first casing 21a is a member that forms the outer shell of the low-pressure stage compressor 21. The first casing 21a is supported by a compressor support part (not shown) that is fixed to the ground, a stand, or the like, and allows the process gas P to circulate inside.

[0020] The first casing 21a has a casing body (not shown), an intake port (not shown) for drawing in the process gas P formed in the casing body, and an exhaust port (not shown) for discharging the process gas P formed in the casing body.

[0021] The first rotor 21b has a first rotating shaft 11 and a multi-stage impeller (not shown) fixed to the first rotating shaft 11 and forming a flow path for compressing the process gas P together with the inner surface of the casing body of the first casing 21a.

[0022] The first rotating shaft 11 is a drive shaft that is columnar and extends in an axial direction Da (left-right direction in FIG. 1) and is rotatable around an axis O that extends horizontally. Hereinafter, the direction in which the axis O extends will be referred to as the "axial direction Da." The first rotating shaft 11 is made of metal or the like. A casing body of the first casing 21a is fixed to the first rotating shaft 11 so as not to rotate, for example, via a bearing device, a sealing device, or the like.

[0023] The impellers are housed in the casing body of the first casing 21a. The impellers are arranged on the first rotary shaft 11 so as to be aligned in the axial direction Da, and rotate integrally with the first rotary shaft 11 around the axis O.

[0024] The following describes the flow of the process gas P introduced into the low-pressure stage compressor 21. A gas introduction line 20a, which is a pipe for introducing the process gas P before compression, is connected to the suction port of the first casing 21a of the low-pressure stage compressor, and the process gas P is introduced from a process gas treatment device (not shown) outside the compression section 20 in the ammonia plant 100 through this gas introduction line 20a.

[0025] The process gas P introduced into the first casing 21a through the suction port is sequentially compressed by the impeller of the first rotor 21b rotating at high speed inside the first casing 21a. The process gas P compressed to a first pressure value by the final-stage impeller is discharged to the outside of the low-pressure stage compressor 21 through the discharge port of the first casing 21a.

[0026] The high-pressure stage compressor 22 is a rotary machine that increases the pressure of the process gas P compressed by the low-pressure stage compressor 21 to a second pressure value that is higher than the first pressure value. The high-pressure stage compressor 22 and the low-pressure stage compressor 21 are connected by an intermediate line 20b, which is a pipe through which the process gas P flows.

[0027] That is, the process gas P compressed by the low-pressure stage compressor 21 is introduced into the high-pressure stage compressor 22 via the intermediate line 20b. The second pressure value in this embodiment is, for example, a pressure (atmospheric pressure) required for a chemical reaction in the ammonia converter 200.

[0028] The high-pressure stage compressor 22 is disposed on one side in the axial direction Da (the right side in FIG. 1) of the low-pressure stage compressor 21. The high-pressure stage compressor 22 has a second casing 22a and a second rotor 22b.

[0029] The second casing 22a is a member that forms the outer shell of the high-pressure stage compressor 22. The second casing 22a is supported by a compressor support part (not shown) that is fixed to the ground, a stand, or the like, and allows the process gas P to circulate inside.

[0030] The second casing 22a has a casing body (not shown), an intake port (not shown) for drawing in the process gas P formed in the casing body, and an exhaust port (not shown) for discharging the process gas P formed in the casing body.

[0031] The second rotor 22b has a second rotating shaft 12 and a multi-stage impeller (not shown) fixed to the second rotating shaft 12 and forming a flow path for compressing the process gas P together with the inner surface of the casing body of the second casing 22a.

[0032] The second rotating shaft 12 is a drive shaft that is columnar and extends in the axial direction Da and is rotatable around the axis O. The second rotating shaft 12 is made of metal or the like. A casing body of the second casing 22a is fixed to the second rotating shaft 12 so as not to rotate, for example, via a bearing device, a sealing device, or the like.

[0033] The impellers are housed in the casing body of the second casing 22a. The impellers are arranged on the second rotary shaft 12 so as to be aligned in the axial direction Da, and rotate integrally with the second rotary shaft 12 about the axis O.

[0034] Here, an end portion on one side in the axial direction Da of the first rotating shaft 11 of the first rotor 21b in the low-pressure stage compressor 21 and an end portion on the other side in the axial direction Da of the second rotating shaft 12 of the second rotor 22b in the high-pressure stage compressor 22 are integrally connected. Specifically, the first rotating shaft 11 and the second rotating shaft 12 are elastically connected by a flexible joint or the like (not shown).

[0035] The first rotating shaft 11 and the second rotating shaft 12 are connected so that their centers are aligned. That is, the center line of the first rotating shaft 11 and the center line of the second rotating shaft 12 are on the same straight line. That is, the first rotating shaft 11 and the second rotating shaft 12 share the axis O as their center line.

[0036] The low-pressure stage compressor 21 and the high-pressure stage compressor 22 constitute a two-stage compression mechanism (multi-stage compressor).

[0037] The following describes the flow of the process gas P introduced into the high-pressure stage compressor 22. The process gas P introduced into the second casing 22a through the suction port of the second casing 22a is compressed by the second rotor 22b rotating at high speed inside the second casing 22a.

[0038] The process gas P compressed to the second pressure value by the final stage impeller is discharged to the outside of the high-pressure stage compressor 22 through the discharge port of the second casing 22a. A gas discharge line 20c, which is a pipe for discharging the compressed process gas P, is connected to the discharge port, and the process gas P is supplied to an ammonia converter 200 outside the compression unit 20 through this gas discharge line 20c.

[0039] The process gas P (H2) introduced into the ammonia converter 200 through the compression section 20 is used for a chemical reaction with nitrogen (N2) in the presence of a catalyst in the ammonia converter 200. Ammonia (NH3) is produced in the ammonia converter 200 by this chemical reaction.

[0040] The ammonia converter 200 is equipped with a boiler 200a as a heat exchanger that utilizes the heat generated by this chemical reaction to generate steam G. The steam G generated in the boiler 200a of the ammonia converter 200 is introduced into the steam turbine 30 as the working fluid of the steam turbine 30.

[0041] (Steam turbine) The steam turbine 30 (ST) is a rotary machine that drives the compression section 20 by utilizing steam G generated in association with the treatment of the process gas P in the ammonia plant 100. In the present embodiment, steam G generated in a boiler 200a of the ammonia converter 200 is introduced into the steam turbine 30 via a steam introduction line 201.

[0042] The steam turbine 30 is disposed on the other side in the axial direction Da (left side in FIG. 1) of the compression section 20. The steam turbine 30 has a turbine stator 30a and a turbine rotor 30b.

[0043] The turbine stator 30a has a turbine casing (not shown) through which steam G flows, and multiple stages of stator vanes (not shown) that extend inward from the inner surface of the turbine casing and straighten the flow of steam G as a working fluid.

[0044] The turbine casing is a component that forms the outer shell of the steam turbine 30. The turbine casing has a turbine casing body, a steam inlet portion formed in the turbine casing body for introducing steam G, and a steam outlet portion formed in the turbine casing body for discharging the steam G.

[0045] The turbine casing body is supported by a turbine support (not shown) fixed to the ground, a frame, or the like, and allows steam G to circulate inside. The stator vanes extend inward from the inner surface of the turbine casing body and regulate the flow of steam G as a working fluid inside the turbine casing body.

[0046] The turbine rotor 30b has a turbine rotating shaft 13 and multiple stages of moving blades that are fixed to the turbine rotating shaft 13 and rotate around the axis O together with the turbine rotating shaft 13 when steam G, which has been straightened by the stationary blades of the turbine stator 30a, collides with them.

[0047] The turbine rotating shaft 13 is a drive shaft that has a columnar shape extending in the axial direction Da and is rotatable around the axis O. The turbine rotating shaft 13 is made of metal or the like. A turbine casing body is fixed to the turbine rotating shaft 13 so that it cannot rotate, for example, via a bearing device, a sealing device, or the like.

[0048] The rotor blades are housed in the turbine casing body. The rotor blades are formed integrally with the turbine rotary shaft 13 and extend outward from the outer surface of the turbine rotary shaft 13. The rotor blades receive pressure from the steam G inside the turbine casing body as a rotational force that rotates the turbine rotary shaft 13.

[0049] The turbine rotor 30b, together with the inner surface of the turbine casing body in the turbine casing and the surfaces of the stator blades, forms a flow path for the steam G. The stator blades and moving blades are arranged alternately in the axial direction Da.

[0050] The flow of steam G introduced into the steam turbine 30 will be described below. The steam G introduced into the turbine casing body through the steam inlet connected to the steam introduction line 201 is rectified by the stator vanes and collides with the rotor blades in the subsequent stages, causing the rotor blades to rotate about the axis O. After colliding with the rotor blades, the steam G is rectified again by the stator vanes in the subsequent stages, and then collides with the rotor blades in the subsequent stages.

[0051] The steam G introduced into the turbine stator 30a continues to rotate the turbine rotor 30b by being rectified by the stator vanes and repeatedly colliding with the rotor blades. That is, the steam G introduced into the steam turbine 30 continues to rotate the turbine rotary shaft 13 of the turbine rotor 30b.

[0052] Here, an end portion on one side in the axial direction Da of the turbine rotating shaft 13 of the turbine rotor 30b and an end portion on the other side in the axial direction Da of the first rotating shaft 11 of the first rotor 21b are integrally connected. Specifically, the turbine rotating shaft 13 and the first rotating shaft 11 are elastically connected by a flexible joint or the like (not shown).

[0053] The turbine rotation shaft 13 and the first rotation shaft 11 are connected so that their centers are aligned. That is, the center line of the turbine rotation shaft 13 and the center line of the first rotation shaft 11 are on the same straight line. That is, the turbine rotation shaft 13 and the first rotation shaft 11 share the axis O as their center line.

[0054] Therefore, when the steam turbine 30 rotates the turbine rotary shaft 13, the first rotary shaft 11 and the second rotary shaft 12 in the compression section 20 rotate in accordance with this rotation. Therefore, the rotation of the steam turbine 30 drives the compression section 20.

[0055] In this embodiment, the turbine rotating shaft 13 in the steam turbine 30, the first rotating shaft 11 in the low-pressure stage compressor 21, and the second rotating shaft 12 in the high-pressure stage compressor 22 are integrated to form the rotating shaft 10, which is a single drive shaft extending in the axial direction Da. In other words, the rotating shaft 10 is rotatable around the axis O, with the axis O as the center.

[0056] After impinging on the rotor blades of the final stage, the steam G is discharged to the outside of the steam turbine 30 through a steam outlet in the turbine casing. A steam discharge line 202, which is a pipe for discharging the steam G, is connected to the steam outlet, and the steam G is discharged to the outside through this steam discharge line 202.

[0057] The steam G discharged outside the steam turbine 30 is introduced into a condenser (not shown) for removing dissolved gases such as oxygen contained in the steam G. The dissolved gases contained in the steam G introduced into the condenser are degassed by a degassing device.

[0058] (speed increaser) The step-up gear 40 (SG: Step-up Gear) is a gear device (gearbox) that connects the rotating shaft 10 and the motor 50 and is capable of increasing the rotation speed of the rotating shaft 10 to a speed higher than the rotation speed of the motor 50.

[0059] That is, the speed increaser 40 is interposed between the compression section 20 and the motor 50, and is capable of increasing the rotational speed of the first rotating shaft 11 and the second rotating shaft 12 in the compression section 20, and the turbine rotating shaft 13 in the steam turbine 30, to a speed higher than the rotational speed of the motor 50.

[0060] The speed increaser 40 in this embodiment has, for example, a gear coupling, which is a type of flexible shaft coupling, configured by a plurality of pinion gears arranged side by side in the axial direction Da.

[0061] The pinion gear of the gear coupling is fixed so as to cover from the outside the other end of the turbine rotating shaft 13 of the rotating shaft 10 in the axial direction Da, and part of the motor 50. The speed increaser 40 connects the rotating shaft 10 and the motor 50 at a predetermined gear ratio.

[0062] (Motor) The motor 50 (M: Motor) is a rotating machine serving as an electric motor that can assist in the rotation of the steam turbine 30. A voltage is applied to the motor 50 from the outside, and the motor 50 rotates at a rotation speed based on the magnitude of the applied voltage. The motor 50 has an output shaft 51 and a motor body 52 .

[0063] The output shaft 51 is a columnar member (motor shaft) that extends in the axial direction Da and is made of metal or the like and is rotatable around the axis O. One end of the output shaft 51 in the axial direction Da is connected to the speed increaser 40. Specifically, the one end of the output shaft 51 in the axial direction Da is fixed to a pinion gear of a gear coupling that the speed increaser 40 has.

[0064] Here, the output shaft 51 and the rotating shaft 10 are spaced apart from each other in the horizontal direction, and the center line of the rotating shaft 10 and the center line of the output shaft 51 are on the same straight line. In other words, the output shaft 51 and the rotating shaft 10 share an axis O as their center line.

[0065] The motor body 52 has, for example, a motor stator (not shown) as a stator, and a motor rotor (not shown) that is fixed integrally with the output shaft 51 and serves as a rotor.

[0066] The motor stator is electrically connected to a device external to the motor 50. When a current flows through a coil of the motor stator, an electromagnetic force is generated that rotates the motor rotor in the circumferential direction of the output shaft 51, with the axis O as the reference (center).

[0067] Therefore, when electric power is input from the outside to the motor stator of the motor body 52, the output shaft 51 rotates. When the output shaft 51 rotates, the speed increaser 40 connecting the output shaft 51 and the turbine rotating shaft 13 increases the rotation speed of the turbine rotating shaft 13 to a speed higher than the rotation speed of the motor 50. In other words, the motor 50 functions as an electric motor that can assist in the rotation of the turbine rotating shaft 13, which is rotated by the steam turbine 30.

[0068] (Frequency conversion section) The frequency conversion unit 60 (VFD: Variable Frequency Drive) is a device that is connected to an electric power system Gr external to the chemical plant compressor train 1 and controls the rotation of the motor 50. In this embodiment, the frequency conversion unit 60 is an inverter that is connected to the electric power system Gr and the motor 50, converts DC power supplied from the electric power system Gr into three-phase AC power, and inputs this AC power to the motor 50.

[0069] A first power purchase cable 61a and a second power purchase cable 61b are connected to the frequency conversion unit 60. The first power purchase cable 61a electrically connects the frequency conversion unit 60 and the motor stator of the motor 50. The second power purchase cable 61b electrically connects the frequency conversion unit 60 and the power grid Gr.

[0070] As a result, the DC power flowing through the electric power system Gr is input to the frequency conversion unit 60 through the second power purchase cable 61b. The DC power input to the frequency conversion unit 60 is converted to AC power, for example, by a power module or the like included in the frequency conversion unit 60, and then input to the motor 50 through the first power purchase cable 61a. Therefore, the motor 50 is driven by purchasing power from the electric power system Gr via the frequency conversion unit 60.

[0071] (Action and effect) The process gas P compressed by the compression unit 20 is supplied to an ammonia converter 200 in the ammonia plant 100, and the process gas P is used in a chemical reaction to produce ammonia. As the process gas P is treated (chemical reaction) inside the ammonia converter 200, steam G is generated in a boiler 200a provided in the ammonia converter 200, and the generated steam G is introduced into a steam turbine 30.

[0072] Here, for example, if the rate of chemical reaction inside ammonia converter 200 decreases, the amount of steam G generated inside boiler 200a within a certain period of time may decrease, that is, the amount of steam G introduced into steam turbine 30 that drives compression section 20 may decrease. Furthermore, if it is desired to increase the rated rotation speed (rated number of revolutions) of compression section 20, the amount of steam G introduced into steam turbine 30 that drives compression section 20 will become insufficient.

[0073] As described above, there are cases where the amount of steam G introduced into the steam turbine 30 is less than the amount of steam G required for the rated rotation of the compression section 20.

[0074] In the compressor train 1 for a chemical plant according to the above embodiment, the motor 50 can assist the rotation of the steam turbine 30 based on the rotation control of the frequency conversion section 60, and therefore, with the assistance of the motor 50, the rotation speed of the steam turbine 30 that drives the compression section 20 can be increased.

[0075] As a result, even if the amount of steam G introduced into the steam turbine 30 is insufficient for the amount of steam G required for the rated rotation of the compression section 20, the rotation speed of the compression section 20 can be increased, and as a result, the rotation speed of the compression section 20 can be made appropriate. Therefore, the pressure of the process gas P compressed by the compression section 20 can be stabilized.

[0076] Furthermore, because the motor 50 can assist the rotational speed of the steam turbine 30, an increase in the amount of steam G to be introduced into the steam turbine 30 can be suppressed when the rotational speed of the steam turbine 30 is increased. Therefore, the sizes of the steam turbine 30 and the compression section 20 can be reduced compared to the configuration of a compressor train 1 for a chemical plant that does not include the motor 50. In other words, the steam turbine 30 and the compression section 20 can be made compact.

[0077] Furthermore, since the motor 50 can assist the rotation of the steam turbine 30, the motor 50 can rotate the steam turbine 30 when the steam turbine 30 is started up (when operation begins). As a result, an auxiliary boiler or the like is not required to start up the steam turbine 30. This makes it possible to reduce the cost of manufacturing the compressor train 1 for a chemical plant. Furthermore, since an auxiliary boiler or the like is not required, the overall size of the compressor train 1 for a chemical plant can be made compact.

[0078] Furthermore, since the compressor train 1 for a chemical plant according to the above embodiment includes the speed-up gear 40 interposed between the compression section 20 and the motor 50, the motor 50 can more efficiently increase the rotational speed of the steam turbine 30. Furthermore, since the speed-up gear 40 rotates the steam turbine 30 and the compression section 20 faster than the motor 50, the steam turbine 30 and the compression section 20 can be made more compact compared to the configuration of the compressor train 1 for a chemical plant that does not include the speed-up gear 40.

[0079] [Second embodiment] A compressor train 1 for a chemical plant according to a second embodiment of the present disclosure will be described below with reference to Fig. 2. The compressor train 1 for a chemical plant described in the second embodiment has a partially different configuration from the compressor train 1 for a chemical plant according to the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0080] (Motor) The motor 50 (M / Gen: Motor / Generator) in this embodiment is an electric motor capable of assisting the rotation of the steam turbine 30, and also serves as a generator 70 capable of generating regenerative power in conjunction with the rotation of the steam turbine 30. Specifically, when the output shaft 51 of the motor 50 is rotated, the motor rotor of the motor main body 52 rotates about the axis O. As the motor rotor rotates, an induced electromotive force is generated in the coil of the motor stator as regenerative power.

[0081] When the amount of steam G introduced into the steam turbine 30 exceeds a predetermined threshold, the motor 50 does not function as an electric motor and switches to a generator 70. The predetermined threshold in this embodiment means, for example, an upper limit value in the range of the amount of steam introduced into the steam turbine 30 within a certain time required for the rated rotation of the compression section 20.

[0082] The predetermined threshold value is calculated, for example, based on the second pressure value of the process gas P in the compression section 20. In this embodiment, whether the amount of steam G introduced into the steam turbine 30 has exceeded the predetermined threshold value is determined, for example, by detecting the pressure of the process gas P that has passed through the compression section 20 using a pressure sensor or the like provided in the gas discharge line 20c, and based on the detection result.

[0083] (speed increaser) The step-up gear 40 (SG / RG: Step-up Gear / Reduction Gear) in this embodiment is a device that can increase the rotation speed of the rotating shaft 10 to a speed higher than the rotation speed of the motor 50, and also serves as a reducer 80 that can reduce the rotation speed of the motor 50 to a speed lower than the rotation speed of the rotating shaft 10. The step-up gear 40 switches to the reducer 80 when the motor 50 switches to the generator 70.

[0084] (Frequency conversion section) The frequency conversion unit 60 in this embodiment is an inverter that converts DC power supplied from the power grid Gr into AC power, and also serves as a converter that converts regenerative power, which is AC power generated in the coil of the motor stator in the motor 50, into DC power.

[0085] A first power selling cable 62a and a second power selling cable 62b are connected to the frequency conversion unit 60. The first power selling cable 62a electrically connects the frequency conversion unit 60 and the motor stator of the motor 50. The second power selling cable 62b electrically connects the frequency conversion unit 60 and the power grid Gr.

[0086] When the motor 50 switches to the generator 70, the frequency conversion unit 60 no longer receives power supply from the power grid Gr. For example, by switching the circuit, the frequency conversion unit 60 cuts off the flow of current from the power grid Gr through the second power purchase cable 61b. Meanwhile, regenerative power, which is AC power generated in the coil of the motor stator, is input to the frequency conversion unit 60 via the first power selling cable 62a.

[0087] As a result, the regenerative power, which is AC power input to the frequency conversion unit 60, is converted into DC power by a power module or the like included in the frequency conversion unit 60, and then input to the electric power grid Gr through the second power selling cable 62b. Therefore, the motor 50 serving as the generator 70 in this embodiment can sell the generated regenerative power to the electric power grid Gr via the frequency conversion unit 60.

[0088] (Action and effect) For example, if the rate of chemical reaction inside ammonia converter 200 increases, the amount of steam G generated inside boiler 200a in a certain period of time increases, that is, the amount of steam G introduced into steam turbine 30 that drives compression section 20 increases and may exceed a predetermined threshold. Also, if it is desired to reduce the rated rotation speed (rated number of revolutions) of compression section 20, the amount of steam G introduced into steam turbine 30 that drives compression section 20 may become excessive.

[0089] In the compressor train 1 for a chemical plant according to the above embodiment, when the amount of steam G generated exceeds a predetermined threshold, the motor 50 does not function as a motor, but becomes a generator 70 that is driven to rotate by the steam turbine 30 and can generate regenerative electricity.

[0090] This allows the regenerative power generated using the excess steam G to be sold to the power grid Gr. In other words, it is possible to partially offset the power purchased from the power grid Gr to drive the motor 50 as an auxiliary for the steam turbine 30. This makes it possible to achieve power saving in the compressor train 1 for a chemical plant and reduce the cost of operating the compressor train 1 for a chemical plant.

[0091] Furthermore, the force of the steam G excessively introduced into the steam turbine 30 can be utilized to rotate the motor 50. As a result, when the steam turbine 30 rotates the turbine rotary shaft 13, the weights of the motor 50 and the speed increaser 40 become resistance. Therefore, it is possible to prevent the rotation speed of the compression section 20 driven by the steam turbine 30 from becoming higher than the rated rotation speed.

[0092] [Third embodiment] A compressor train 1 for a chemical plant according to a third embodiment of the present disclosure will be described below with reference to Fig. 3. The compressor train 1 for a chemical plant described in the third embodiment has a configuration that is partially different from the compressor train 1 for a chemical plant according to the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0093] (Compression section) The first rotating shaft 11 in the low-pressure stage compressor 21 is connected to the speed increaser 400. The first rotating shaft 11 extends in the horizontal direction and is rotatable around a first axis O1 that is parallel to the axis O.

[0094] The second rotary shaft 12 in the high-pressure stage compressor 22 is connected to the speed increaser 400. The second rotary shaft 12 extends horizontally and is rotatable around a second axis O2 that is parallel to the axis O.

[0095] (Steam turbine) The turbine rotary shaft 13 in the steam turbine 30 is connected to the speed increaser 400. The turbine rotary shaft 13 extends in the horizontal direction and is rotatable around a turbine axis O3 that is parallel to the axis O.

[0096] In this embodiment, the first axis O1, the second axis O2, and the turbine axis O3 are different axes, and therefore the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 do not share the same axis as their center line.

[0097] (speed increaser) The speed increaser 400 in this embodiment is a gear device (gearbox) that connects the first rotating shaft 11 in the low-pressure stage compressor 21, the second rotating shaft 12 in the high-pressure stage compressor 22, the turbine rotating shaft 13 in the steam turbine 30, and the motor 50, and is capable of increasing the rotational speeds of these shafts to a speed higher than the rotational speed of the motor 50.

[0098] The speed increaser 400 has parallel gears that can increase the rotational speeds of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 to different speeds. The parallel gears in this embodiment can increase the rotational speeds of the turbine rotating shaft 13, the first rotating shaft 11, and the second rotating shaft 12 in this order so that they become higher than the rotational speed of the output shaft 51 of the motor 50.

[0099] The parallel gear is made up of multiple gears, and different gears in the parallel gear are capable of increasing the rotation speed of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13. In other words, the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 are connected to the speed increaser 400 at positions offset from one another.

[0100] The speed increaser 400 can be disconnected from the first rotating shaft 11 and the second rotating shaft 12, and can be connected only to the motor 50 and the turbine rotating shaft 13. This allows the motor 50 to assist only in driving the steam turbine 30, for example, when the steam turbine 30 starts operating (starting up).

[0101] (Motor) The output shaft 51 is a columnar member (motor shaft) that extends in the axial direction Da and is rotatable around the axis O. One end of the output shaft 51 in the axial direction Da is connected to the speed increaser 400.

[0102] Here, the first rotating shaft 11, the second rotating shaft 12, the turbine rotating shaft 13, and the output shaft 51 are spaced apart from one another in the horizontal direction, and the center line of the output shaft 51 and the center lines of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 are not aligned on the same straight line. In other words, the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 are eccentric with respect to the output shaft 51.

[0103] (Action and effect) In the compressor train 1 for a chemical plant according to the above embodiment, the parallel gears of the speed increaser 400 can increase the rotational speeds of the steam turbine 30, the low-pressure stage compressor 21, and the high-pressure stage compressor 22 to different speeds, so that the rotational speeds of each can be adjusted to the minimum required rotational speed.

[0104] This reduces the total amount of energy required to rotate these components compared to a configuration in which the speed-increasing gear 400 simultaneously increases the rotational speeds of the steam turbine 30, the low-pressure stage compressor 21, and the high-pressure stage compressor 22 on the same shaft. This makes it possible to improve the energy efficiency and save energy in the compressor train 1 for a chemical plant.

[0105] Moreover, in the compressor train 1 for a chemical plant according to the above embodiment, the steam turbine 30 has a turbine rotating shaft 13, the low-pressure stage compressor 21 has a first rotating shaft 11, and the high-pressure stage compressor 22 has a second rotating shaft 12. That is, the steam turbine 30, the low-pressure stage compressor 21, and the high-pressure stage compressor 22 each have a different drive shaft.

[0106] As a result, when one of these devices is disassembled for maintenance, the devices are not arranged coaxially, so that units or parts disassembled from one device do not interfere with the other devices, thereby improving the maintainability of the chemical plant compressor train 1.

[0107] [Fourth embodiment] A compressor train 1 for a chemical plant according to a fourth embodiment of the present disclosure and an operating method for the compressor train 1 for a chemical plant will be described below with reference to Figures 4 to 8. The compressor train 1 for a chemical plant described in the fourth embodiment has a partially different configuration from the compressor train 1 for a chemical plant according to the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0108] (Compressor train for chemical plants) As shown in FIG. 4, the compressor train 1 for a chemical plant in this embodiment includes a compression section 20 (not shown in its entirety), a steam turbine 30, a speed increaser 40, a motor 50, a frequency conversion section 60, a condenser 90, a condensate pump 95, a gland condenser 110, a vacuum pump 120, a vapor fan 125, a drain separator 130, a shaft seal device 140, a control device 150, a steam inlet line 201, a steam discharge line 202, a connection line 160, a drain line 170, a circulation line 180, a condensate recovery line 190, a first suction line 210, a second suction line 220, a leak steam line 230, a governing valve 240, a dump valve 250, a first on-off valve 260, a second on-off valve 270, and a flow rate sensor 290.

[0109] (Steam turbine) The steam turbine 30 has a turbine stator 30a (stator) and a turbine rotor 30b (rotor).

[0110] The turbine stator 30a has a turbine casing 301a through which steam G flows, and multiple stages of stator vanes 301b that extend inward from the inner surface of the turbine casing 301a and straighten the flow of steam G as a working fluid.

[0111] The turbine casing 301a forms the outer shell of the steam turbine 30. The turbine casing 301a has a turbine casing body, a steam inlet formed in the turbine casing body for introducing steam G, and a steam outlet formed in the turbine casing body for discharging the steam G. The stator vanes 301b extend inward from the inner surface of the turbine casing body. The stator vanes 301b straighten the flow of steam G as a working fluid inside the turbine casing body.

[0112] The turbine rotor 30b has a turbine rotating shaft 13 and multiple stages of moving blades 302a that are fixed to the turbine rotating shaft 13 and rotate around the axis O together with the turbine rotating shaft 13 when steam G that has been straightened by the stator blades 301b of the turbine stator 30a collides with them.

[0113] The rotor blades 302a are housed in the turbine casing body. The rotor blades 302a are formed integrally with the turbine rotary shaft 13 and extend outward from the outer surface of the turbine rotary shaft 13. The rotor blades 302a receive pressure from the steam G inside the turbine casing body as a rotational force that rotates the turbine rotary shaft 13.

[0114] The turbine rotor 30b, together with the inner surface of the turbine casing body in the turbine casing 301a and the surfaces of the stator blades 301b, forms a flow path for the steam G. The stator blades 301b and the rotor blades 302a are arranged alternately in the axial direction Da.

[0115] The flow of steam G introduced into the steam turbine 30 will be described below. The steam G introduced into the turbine casing body through a steam inlet connected to the steam introduction line 201 is rectified by the stator vanes 301b and collides with the rotor blades 302a in the subsequent stage, causing the rotor blades 302a to rotate around the axis O. After colliding with the rotor blades 302a, the steam G is rectified again by the stator vanes 301b in the subsequent stage, and then collides with the rotor blades 302a in the subsequent stage.

[0116] The steam G introduced into the turbine stator 30a continues to rotate the turbine rotor 30b by being rectified by the stator vanes 301b and repeatedly colliding with the rotor blades 302a. That is, the steam G introduced into the steam turbine 30 continues to rotate the turbine rotary shaft 13 of the turbine rotor 30b.

[0117] After colliding with the rotor blades 302a of the final stage, the steam G is discharged to the outside of the steam turbine 30 through a steam outlet portion in the turbine casing 301a. A steam discharge line 202, which is a pipe for discharging the steam G, is connected to the steam outlet portion, and the steam G is introduced into a condenser 90 arranged outside the steam turbine 30 through this steam discharge line 202.

[0118] (condenser) The condenser 90 is connected to the steam turbine 30, for example, by a steam discharge line 202. The condenser 90 cools and condenses the steam G discharged from a steam outlet of the turbine casing 301a through the steam discharge line 202. The condenser 90 is connected to a drainage line 170. The condenser 90 discharges water W accumulated inside to the outside of the condenser 90 through this drainage line 170.

[0119] The condenser 90 is also connected to a first suction line 210. The condenser 90 discharges air that flows in through gaps between equipment joints and the like from the first suction line 210 to the outside of the condenser 90. The condenser 90 is also connected to a circulation line 180. The circulation line 180 is also connected to a drainage line 170.

[0120] A connection line 160 is also connected to the condenser 90. The connection line 160 connects the steam introduction line 201 and the condenser 90. Therefore, the connection line 160 can guide the steam G flowing through the steam introduction line 201 toward the steam turbine 30 to the condenser 90. A dump valve 250 is also arranged on the connection line 160. The dump valve 250 adjusts its own opening by receiving a signal indicating its opening transmitted from the control device 150. The dump valve 250 reduces the pressure of the steam G flowing through the connection line 160 to a pressure that corresponds to its opening.

[0121] Furthermore, a governing valve 240 is disposed in the steam introduction line 201 at a position closer to the steam turbine 30 than the connection point with the connection line 160. The governing valve 240 adjusts its own opening degree by receiving a signal indicating the opening degree transmitted from the control device 150. Furthermore, a flow rate sensor 290 is disposed in the steam introduction line 201 at a position closer to the ammonia converter 200 than the connection point with the connection line 160. The flow rate sensor 290 detects the amount of steam G flowing through the steam introduction line 201. The flow rate sensor 290 transmits a signal indicating the detected amount of steam G to the control device 150.

[0122] (condensate pump) The condensate pump 95 is disposed in a drainage line 170. The condensate pump 95 circulates the water W condensed by the condenser 90 through the drainage line 170 to an external device (not shown), such as a boiler. A first on-off valve 260 is disposed in a portion of the drainage line 170 downstream of the condensate pump 95. A circulation line 180 that connects the drainage line 170 and the condenser 90 is also connected to the drainage line 170.

[0123] The first on-off valve 260 is disposed downstream of the connection point of the drain line 170 with the circulation line 180. A second on-off valve 270 is disposed in the circulation line 180. By adjusting the opening degrees of the first on-off valve 260 and the second on-off valve 270, the amount of water W flowing from the condenser 90 into the boiler and the amount of water W returned to the condenser 90 are adjusted.

[0124] (ground capacitor) The gland condenser 110 is connected to the steam turbine 30, for example, via a leak steam line 230. The gland condenser 110 degasses leak steam that has flowed out of the turbine stator 30a from a gap between the turbine stator 30a and the turbine rotor 30b of the steam turbine 30. The gland condenser 110 in this embodiment condenses leak steam (gland steam) that has leaked out from a gap between the turbine rotating shaft 13 of the turbine rotor 30b and openings formed at both ends of the turbine stator 30a in the axial direction Da of the casing body.

[0125] For this reason, the interior of the gland condenser 110 is in communication with the gap between the turbine rotating shaft 13 and the opening of the casing body through a leak steam line 230. The gland condenser 110 in this embodiment is, for example, a shell-and-tube type heat exchanger.

[0126] The gland condenser 110 is connected to the condenser 90 through a condensate recovery line 190. The gland condenser 110 supplies startup water W to the condenser 90 when the steam turbine 30 is started up. The gland condenser 110 supplies leak steam and water W obtained by degassing the condensed water W to the condenser 90 through the condensate recovery line 190 when the steam turbine 30 is in operation. In this way, the gland condenser 110 controls the liquid level in the condenser 90 when the steam turbine 30 is in operation.

[0127] (vacuum pump) The vacuum pump 120 is connected to the condenser 90 through a first suction line 210 .

[0128] When the vacuum pump 120 is driven, it sucks in air from inside the condenser 90. As a result, the vacuum pump 120 reduces the pressure inside the condenser 90 to a negative pressure. When the steam turbine 30 is not driven, when the vacuum pump 120 is driven, the air inside the condenser 90 is sucked in, and the air inside the steam turbine 30 is sucked into the condenser 90 through the steam discharge line 202. As a result, the pressure inside the steam turbine 30 decreases.

[0129] A drain separator 130 is disposed in the first suction line 210 downstream of the vacuum pump 120. The drain separator 130 further separates the air sucked by the vacuum pump 120 into gas and liquid. The liquid phase component and gas phase component separated by the drain separator 130 are each discharged to the outside of the compressor train 1 for a chemical plant, for example.

[0130] (Vapor Fan) The vapor fan 125 is disposed in a second suction line 220 connected to the gland condenser. The vapor fan 125 is electrically driven to remove air from the gland condenser 110 and maintain a slight negative pressure inside the gland condenser 110.

[0131] (Shaft seal device) The shaft seal device 140 seals the gap between the turbine stator 30a of the steam turbine 30 and the turbine rotor 30b of the steam turbine 30. In this embodiment, the shaft seal devices 140 are respectively disposed in the gap between the turbine rotating shaft 13 and openings formed at both ends of the casing body. In this way, the shaft seal devices 140 seal the gap between the openings and the outer peripheral surface of the turbine rotating shaft 13, thereby suppressing leakage of steam G from the casing body to the outside.

[0132] The shaft seal device 140 is connected to the gland condenser 110 through a leak steam line 230. The shaft seal device 140 in this embodiment is disposed in an atmospheric pressure environment facing the outside of the casing. As shown in Fig. 5, the shaft seal device 140 in this embodiment has a housing 141, a seal member 142, and a biasing member 143.

[0133] The housing 141 is fixed to the opening of the casing body within the opening. A groove 141a is formed in the housing 141, extending continuously in the circumferential direction around the axis O of the turbine rotary shaft 13. The groove 141a is composed of an accommodating recess 141b having a rectangular cross section and a communication portion 141c that connects the accommodating recess 141b with the space between the turbine rotary shaft 13 and the housing 141. The housing 141 holds the seal member 142 within the accommodating recess 141b so that the seal member 142 is movable in the radial direction of the turbine rotary shaft 13.

[0134] The seal member 142 is movable in its radial position relative to the outer circumferential surface of the turbine rotary shaft 13. The seal member 142 is also movable in the radial direction relative to the housing 141. In this embodiment, the seal member 142 is annular. The seal member 142 has a pressure-receiving portion 142a, a base portion 142b, a connecting portion 142c, and a seal body 142d.

[0135] The pressure-receiving portion 142a is accommodated in the accommodation recess 141b so as to be movable in the radial direction. The pressure-receiving portion 142a is connected to the seal body 142d via the base portion 142b and the connecting portion 142c. The pressure-receiving portion 142a moves the seal body 142d in the radial direction. The pressure-receiving portion 142a is formed so that its width in the axial direction Da is smaller than the width in the axial direction Da of the accommodation recess 141b and larger than the width in the axial direction Da of the connecting portion 142c.

[0136] The base portion 142b is disposed radially inward of the housing 141. The width dimension of the base portion 142b in the axial direction Da is larger than the width dimension of the communication portion 141c in the axial direction Da. In this embodiment, the width dimension of the base portion 142b in the axial direction Da is approximately the same as the width dimension of the housing 141 in the axial direction Da.

[0137] The connecting portion 142c connects the pressure receiving portion 142a and the base portion 142b to each other, and is movable in the radial direction within the communicating portion 141c of the groove 141a.

[0138] The seal body 142d seals the gap with the outer peripheral surface of the turbine rotary shaft 13. The seal body 142d is fixed to a radially inner portion of the base portion 142b. The inner peripheral surface of the seal body 142d is capable of coming into contact with the turbine rotary shaft 13. The seal body 142d includes a free-cutting material made of a material that is more machinable than the turbine rotary shaft 13. The seal body 142d in this embodiment is made of, for example, an abradable material. Note that the seal body 142d is not limited to an abradable material, and may include a free-cutting material. The seal body 142d may include, for example, a carbon material.

[0139] Furthermore, in this embodiment, a plurality of seal projections 131 are formed in a region of the outer peripheral surface of the turbine rotating shaft 13 that corresponds to the region where the shaft seal device 140 is disposed. The seal projections 131 are formed spaced apart in the axial direction Da on the outer peripheral surface of the turbine rotating shaft 13 facing the seal body 142d. The seal projections 131 are formed integrally with the turbine rotating shaft 13. The seal projections 131 protrude radially outward from the outer peripheral surface of the turbine rotating shaft 13. The seal body 142d exhibits sealing properties by sliding against the seal projections 131 that rotate while being scraped.

[0140] The biasing member 143 biases the pressure-receiving portion 142a radially inward. A plurality of biasing members 143 are arranged inside the accommodating recess 141b while connected to the pressure-receiving portion 142a. The biasing members 143 are elastic members such as disc springs or leaf springs. The biasing members 143 press the pressure-receiving portion 142a radially inward and contract by receiving a force radially outward from the pressure-receiving portion 142a.

[0141] In this shaft seal device 140, the pressure-receiving portion 142a is pressed radially inward by the biasing force of the biasing member 143. As a result, the seal body 142d approaches the outer peripheral surface of the turbine rotary shaft 13, and the seal body 142d comes into sliding contact with the seal protrusion 131. This causes the shaft seal device 140 to seal the gap between the opening of the casing body and the turbine rotary shaft 13, preventing air from entering the inside of the casing body from the outside. In other words, when the steam turbine 30 is driven, the pressure-receiving portion 142a is pressed radially inward by the biasing force of the biasing member 143, sealing the gap between the turbine rotary shaft 13 and the opening of the casing body.

[0142] (Control device) The control device 150 controls the operating status of the steam turbine 30. As shown in Fig. 6 , the control device 150 in this embodiment includes a steam switching unit 151, a vacuum pump control unit 152, a motor control unit 153, a steam flow rate detection unit 154, a steam flow rate determination unit 155, and a memory unit 156.

[0143] (Steam switching section) The steam switching unit 151 controls the opening degree of the governing valve 240 disposed in the steam introduction line 201 and the opening degree of the dump valve 250 disposed in the connection line 160. The steam switching unit 151 has a governing valve operation unit 151a and a dump valve operation unit 151b.

[0144] Governing valve operation unit 151a controls the opening degree of governing valve 240 by transmitting a signal indicating the opening degree to governing valve 240. Dump valve operation unit 151b controls the opening degree of dump valve 250 by transmitting a signal indicating the opening degree to dump valve 250.

[0145] (Vacuum pump control unit) The vacuum pump control unit 152 drives the vacuum pump 120. Specifically, the vacuum pump control unit 152 drives the vacuum pump 120 by transmitting a signal indicating a drive instruction to the vacuum pump 120.

[0146] (Motor control unit) The motor control unit 153 controls the driving of the motor 50 during operation of the steam turbine 30, including starting and stopping of the steam turbine 30. The motor control unit 153 has a motor starting unit 153a, a motor driving unit 153b, and a motor deceleration unit 153c.

[0147] The motor starting unit 153a starts driving the motor 50 when a signal indicating a start instruction is input. Specifically, when a signal indicating a start instruction is input to the control device 150 via an input interface or the like by an operator of the compressor train 1 for a chemical plant, the motor starting unit 153a starts driving the motor 50 by sending a signal indicating the start instruction to the frequency conversion unit 60. When the frequency conversion unit 60 receives the signal sent from the motor starting unit 153a, it inputs a predetermined amount of AC power to the motor 50 via the first power purchase cable 61a. This causes the motor 50 to start driving. That is, when an AC voltage is applied to the motor main body 52 of the motor 50, the output shaft 51 of the motor 50 starts rotating around the axis O.

[0148] When the motor starting unit 153a starts driving the motor 50, the motor driving unit 153b continues to drive the motor 50. Specifically, the motor driving unit 153b continues to drive the motor 50 by transmitting a signal indicating a predetermined rotation speed to the frequency conversion unit 60. When the frequency conversion unit 60 receives the signal transmitted from the motor driving unit 153b, it inputs AC power of a magnitude corresponding to the rotation speed indicated by the received signal to the motor 50 via the first power purchasing cable 61a. As a result, the motor 50 continues to rotate at the rotation speed corresponding to the signal. Note that the rotation speed indicated by the signal transmitted from the motor driving unit 153b to the frequency conversion unit 60 is stored in advance in, for example, the storage unit 156. The rotation speed in this embodiment includes, for example, the rated rotation speed of the motor 50.

[0149] The motor speed reducer 153c decelerates the motor 50 when, for example, a signal indicating a stop instruction is input while the motor driver 153b maintains the drive of the motor 50. Specifically, when a signal indicating a stop instruction is input to the control device 150 via an input interface or the like by an operator of the chemical plant compressor train 1, the motor speed reducer 153c decelerates the motor 50 by transmitting a signal indicating deceleration to the frequency converter 60. In this embodiment, when the frequency converter 60 receives the signal transmitted from the motor speed reducer 153c, it stops the input of AC power to the motor 50 via the first power purchase cable 61a. As a result, the motor 50 gradually decelerates (the rotation speed decreases).

[0150] (Steam flow rate detector) The steam flow rate detection unit 154 detects the amount of steam G flowing through the steam introduction line 201. Specifically, the steam flow rate detection unit 154 detects the amount of steam G by receiving a signal indicating the detection result transmitted from a flow rate sensor 290 arranged in the steam introduction line 201. The steam flow rate detection unit 154 sends a signal indicating the detected amount of steam G to the steam flow rate determination unit 155.

[0151] (Steam flow rate determination unit) The steam flow rate determination unit 155 determines whether or not the amount of steam G flowing through the steam introduction line 201 is equal to or greater than a specified amount. Specifically, the amount of steam G received from the steam flow rate detection unit 154 is compared with a predetermined specified amount stored in advance in the storage unit 156, thereby determining whether or not the amount of steam G flowing through the steam introduction line 201 is equal to or greater than the specified amount.

[0152] That is, if the amount of steam G received from the steam flow rate detection unit 154 is less than the specified amount, the steam flow rate determination unit 155 determines that "the amount of steam is less than the specified amount." On the other hand, if the amount of steam G received from the steam flow rate detection unit 154 is equal to or greater than the specified amount, the steam flow rate determination unit 155 determines that "the amount of steam is equal to or greater than the specified amount." The steam flow rate determination unit 155 sends a signal indicating the determination result to the steam switching unit 151.

[0153] The specified amount in this embodiment means, for example, the lower limit (minimum cooling steam flow) of the range of amounts of steam G at which the temperature inside the steam turbine 30 does not rise excessively when steam G flows into the steam turbine 30 and the steam turbine 30 is driven while the pressure inside the steam turbine 30 is reduced by the vacuum pump 120. This specified amount is a value smaller than the rated steam amount flowing into the steam turbine 30 during rated operation of the steam turbine 30. The specified amount is stored in advance in the memory unit 156, for example.

[0154] Here, when the above-described steam switching unit 151 receives a determination result from the steam flow rate determination unit 155, it switches the open / closed states of the governing valve 240 and the dump valve 250 based on this determination result. Specifically, when the determination result indicates that "the amount of steam is less than a specified amount," the steam switching unit 151 closes the governing valve 240 and opens the dump valve 250. On the other hand, when the determination result indicates that "the amount of steam is equal to or greater than a specified amount," the steam switching unit 151 opens the governing valve 240 and closes the dump valve 250.

[0155] At this time, the steam switching unit 151 gradually changes the opening degrees of the governing valve 240 and the dump valve 250. That is, the steam switching unit 151 gradually increases or decreases the opening degrees of the governing valve 240 and the dump valve 250. The steam switching unit 151 in this embodiment switches the open / closed states of the governing valve 240 and the dump valve 250, for example, by linearly increasing or decreasing the opening degrees of the governing valve 240 and the dump valve 250.

[0156] (Method of operating a compressor train for a chemical plant) Next, a method for operating the compressor train 1 for a chemical plant will be described with reference to Fig. 7. The method for operating the compressor train 1 for a chemical plant in this embodiment executes a vacuum drawing step S1, a motor starting step S2, a motor driving step S3, a first steam flow rate determination step S4, a first steam switching step S5, a turbine operating step S6, a motor deceleration step S7, a second steam flow rate determination step S8, and a second steam switching step S9.

[0157] (Vacuum drawing process) In the evacuation step S1, the vacuum pump 120 is driven while the steam turbine 30 is not operating, thereby reducing the pressure inside the steam turbine 30. That is, the inside of the steam turbine 30 is evacuated. At this time, the inside of the steam turbine 30 is evacuated while the flow of steam G generated by the treatment of the process gas P into the steam turbine 30 is stopped. That is, the inside of the steam turbine 30 is evacuated while the governing valve 240 is closed and the dump valve 250 is open. Therefore, the inside of the steam turbine 30 is evacuated while the governing valve 240 is closed and the flow of steam G and air from the outside into the steam turbine 30 is prevented.

[0158] (Motor starting process) The motor starting process S2 is a process that is executed after the evacuation process S1 is completed. In the motor starting process S2, AC power is input from the frequency conversion unit 60 to the motor 50, thereby starting the motor 50. Therefore, in the motor starting process S2, the motor 50 starts to start, and the steam turbine 30 starts to operate. At this time, the motor 50 starts to operate in a state where the flow of steam G generated by the treatment of the process gas P into the steam turbine 30 is stopped.

[0159] (Motor drive process) The motor driving step S3 is a step that is executed after the motor starting step S2 is completed. In the motor driving step S3, AC power is continuously input from the frequency conversion unit 60 to the motor 50, thereby continuously driving the motor 50. Therefore, in the motor driving step S3, the driving of the motor 50 is maintained, and the steam turbine 30 is continuously driven.

[0160] (First steam flow rate determination step) In the first steam flow rate determination step S4, the amount of steam G generated by driving the motor 50 is compared with a specified amount while the motor 50 continues to drive. In the first steam flow rate determination step S4, the amount of steam G flowing through the steam inlet line 201 is detected, and it is determined whether the amount of steam G flowing through the steam inlet line 201 is equal to or greater than the specified amount.

[0161] (First steam switching process) The first steam switching process S5 is a process executed after the first steam flow rate determination process S4. In the first steam switching process S5, the flow of steam G into the steam turbine 30 is started based on the result determined in the first steam flow rate determination process S4. In the first steam switching process S5, the flow of steam G into the steam turbine 30 is started when the amount of steam G generated in association with the driving of the motor 50 becomes equal to or greater than a specified amount. That is, in the first steam switching process S5, the governing valve 240 is switched to an open state, and the dump valve 250 is simultaneously switched to a closed state. At this time, the opening degrees of the governing valve 240 and the dump valve 250 are gradually changed, thereby switching the open / closed states of the governing valve 240 and the dump valve 250.

[0162] (Turbine operating process) The turbine operation step S6 is a step executed after the first steam switching step S5. In the turbine operation step S6, AC power is continuously input from the frequency conversion unit 60 to the motor 50, thereby continuously driving the motor 50. Therefore, in the turbine operation step S6, the driving of the motor 50 is maintained, thereby continuously driving the steam turbine 30. In the turbine operation step S6 in this embodiment, for example, the motor 50 is continuously driven at a rated rotation speed (rated operation).

[0163] (Motor deceleration process) In the motor deceleration step S7, the rotation of the motor 50 is decelerated. In the motor deceleration step S7, the rotation of the motor 50 is decelerated when, for example, an operator of the compressor train 1 for a chemical plant or the like issues an instruction to stop the steam turbine 30. In the motor deceleration step S7 in this embodiment, the rotation of the motor 50 is decelerated and the driving of the motor 50 is stopped by not inputting AC power from the frequency conversion unit 60 to the motor 50.

[0164] (Second steam flow rate determination step) In the second steam flow rate determination step S8, when the rotation of the motor 50 is decelerated, the amount of steam G generated by driving the motor 50 is compared with a specified amount. In the second steam flow rate determination step S8, the amount of steam G flowing through the steam inlet line 201 is detected, and it is determined whether the amount of steam G flowing through the steam inlet line 201 is less than the specified amount.

[0165] (Second steam switching process) The second steam switching step S9 is a step executed after the second steam flow rate determination step S8. In the second steam switching step S9, the flow of steam G into the steam turbine 30 is stopped based on the result of determination in the second steam flow rate determination step S8. In the second steam switching step S9, the flow of steam G into the steam turbine 30 is stopped when the amount of steam G generated in association with the driving of the motor 50 becomes less than a specified amount. That is, in the second steam switching step S9, the governing valve 240 is switched to a closed state, and the dump valve 250 is simultaneously switched to an open state. At this time, the opening degrees of the governing valve 240 and the dump valve 250 are gradually changed, thereby switching the open / closed states of the governing valve 240 and the dump valve 250.

[0166] In the second steam switching step S9, the pressure inside the steam turbine 30 is reduced by switching the open / closed states of the governing valve 240 and the dump valve 250 and then driving the vacuum pump 120 again.

[0167] By executing the above-described steps (S1 to S9), the compressor train 1 for a chemical plant is operated.

[0168] (Control device operation) Next, the operation of the control device 150 will be described with reference to FIG. First, in the evacuation step S1, the steam switching unit 151 of the control device 150 operates the governing valve 240 and the dump valve 250 to set the open / closed states of the governing valve 240 and the dump valve 250 (step S10). Specifically, the steam switching unit 151 sets the governing valve 240 to a closed state and the dump valve 250 to an open state.

[0169] Next, in the evacuation step S1, the vacuum pump driving unit of the control device 150 drives the vacuum pump 120 (step S11). Specifically, the vacuum pump driving unit drives the vacuum pump 120 by transmitting a signal indicating a driving instruction to the vacuum pump 120.

[0170] Next, in a motor starting step S2, the motor starting unit 153a in the control device 150 starts starting the motor 50 (step S12). Specifically, the motor starting unit 153a starts driving the motor 50 by transmitting a signal indicating a start instruction to the frequency conversion unit 60.

[0171] Next, in a motor driving step S3, the motor driving unit 153b in the control device 150 continues driving the motor 50 (step S13). Specifically, the motor driving unit 153b continues driving the motor 50 by transmitting a signal indicating a predetermined number of rotations to the frequency conversion unit 60. That is, the driving of the motor 50 is maintained by the motor driving unit 153b.

[0172] Next, in a first steam flow rate detection step S4, the steam flow rate detection unit 154 of the control device 150 detects the amount of steam G flowing through the steam introduction line 201 (step S14). Specifically, the steam flow rate detection unit 154 detects the amount of steam G flowing through the steam introduction line 201 by receiving a signal transmitted from the flow rate sensor 290.

[0173] Next, in a first steam flow rate detection step S4, the steam flow rate determination unit 155 of the control device 150 determines whether the amount of steam G is equal to or greater than a specified amount based on the amount of steam G detected by the steam flow rate detection unit 154 (step S15). If the steam flow rate determination unit 155 determines that "the amount of steam is less than the specified amount" (step S15: NO), the process returns to, for example, step S14.

[0174] On the other hand, if steam flow rate determination unit 155 determines that "the amount of steam is equal to or greater than the specified amount" (step S15: YES), in the first steam switching step S5, steam switching unit 151 operates governing valve 240 and dump valve 250 to switch the open / closed states of governing valve 240 and dump valve 250 (step S16). Specifically, steam switching unit 151 opens governing valve 240 and closes dump valve 250 at the same time.

[0175] Next, in a turbine operation step S6, the motor drive unit 153b maintains the driving of the motor 50 (step S17). Specifically, the motor drive unit 153b continues to drive the motor 50 by sending a signal indicating a predetermined rotation speed to the frequency conversion unit 60. At this time, the motor drive unit 153b sends a signal indicating the rated rotation speed to the frequency conversion unit 60 so that the steam turbine 30 is driven at the rated rotation speed by the driving of the motor 50. Therefore, the motor drive unit 153b operates the steam turbine 30 at the rated speed.

[0176] Next, in a motor deceleration step S7, when a signal indicating an instruction to stop the steam turbine 30 is input by an operator of the chemical plant compressor train 1 or the like, the motor deceleration unit 153c of the control device 150 decelerates the motor 50 (step S18). Specifically, the motor deceleration unit 153c decelerates the motor 50 by transmitting a signal indicating deceleration to the frequency conversion unit 60.

[0177] Next, in a second steam flow rate determination step S8, when the motor 50 is decelerated, the steam flow rate detection unit 154 detects the amount of steam G flowing through the steam introduction line 201 (step S19). Specifically, the steam flow rate detection unit 154 detects the amount of steam G flowing through the steam introduction line 201 by receiving a signal transmitted from the flow rate sensor 290.

[0178] Next, in a second steam flow rate determination step S8, the steam flow rate determination unit 155 determines whether the amount of steam G is less than a specified amount (step S20) based on the amount of steam G detected by the steam flow rate detection unit 154. If the steam flow rate determination unit 155 determines that "the amount of steam is equal to or greater than the specified amount" (step S20: NO), the process returns to, for example, step S18.

[0179] On the other hand, if the steam flow rate determination unit 155 determines that "the amount of steam is less than the specified amount" (step S20: YES), in the second steam switching step S9, the steam switching unit 151 operates the governing valve 240 and the dump valve 250 to switch the open / closed states of the governing valve 240 and the dump valve 250 (step S21). Specifically, the steam switching unit 151 closes the governing valve 240 and simultaneously opens the dump valve 250.

[0180] The above-described processing from step S10 to step S20 is repeatedly executed during operation of the ammonia plant.

[0181] (Action and effect) According to the above configuration, the pressure inside the steam turbine 30 can be reduced by the vacuum pump 120 while the gap between the turbine rotor 30b and the turbine stator 30a of the steam turbine 30 is sealed by the shaft seal device 140. That is, the inside of the steam turbine 30 can be evacuated. Therefore, for example, the steam turbine 30 can be started to be driven by the motor 50 while the pressure inside the steam turbine 30 is reduced. As a result, for example, the load on the motor 50 when the steam turbine 30 starts to be driven can be reduced.

[0182] Furthermore, according to the above, the steam turbine 30 can be driven with the internal pressure of the steam turbine 30 reduced until the amount of steam G generated in the treatment of the process gas P reaches or exceeds a specified amount. That is, the steam turbine 30, the interior of which has been evacuated, can be driven until the amount of steam G reaches or exceeds a specified amount. Therefore, for example, an increase in the internal temperature of the steam turbine 30 can be suppressed when the steam turbine 30 starts to operate. As a result, for example, damage to components of the steam turbine 30 inside the steam turbine 30 can be suppressed. Furthermore, an increase in the load on the motor 50 can be suppressed when the steam turbine 30 starts to operate. Therefore, the power required for operation of the compressor train 1 for a chemical plant can be reduced.

[0183] Furthermore, according to the above, when the amount of steam G generated in the treatment of the process gas P falls below a specified amount, the flow of steam G into the steam turbine 30 can be stopped. After the flow of steam G into the steam turbine 30 is stopped, the vacuum pump 120 is driven, thereby reducing the pressure inside the steam turbine 30. That is, when the flow of steam G into the steam turbine 30 is stopped, the inside of the steam turbine 30 can be evacuated. Therefore, for example, an increase in the temperature inside the steam turbine 30 can be suppressed when the operation of the steam turbine 30 is stopped. Furthermore, an increase in the load on the motor 50 can be suppressed when the operation of the steam turbine 30 is stopped.

[0184] Moreover, in the above embodiment, the inflow state of steam G to the steam turbine 30 can be switched by the governing valve 240 arranged in the steam inlet line 201 and the dump valve 250 arranged in the connection line 160. This makes it possible to achieve the above-mentioned effects with a more specific configuration. Moreover, in the above embodiment, when the governing valve 240 is closed and the dump valve 250 is opened, the steam G flowing through the steam inlet line 201 is introduced into the condenser 90 in a depressurized state. Therefore, for example, it is not necessary to provide a separate device in the ammonia plant 100 for receiving the steam G flowing through the steam inlet line 201. As a result, it is possible to prevent the ammonia plant 100 from becoming large in size.

[0185] [Other embodiments] Although the embodiments of the present disclosure have been described above in detail with reference to the drawings, the specific configurations are not limited to those of the embodiments, and additions, omissions, substitutions, and other modifications of the configurations are possible within the scope of the gist of the present disclosure. Furthermore, the present disclosure is not limited to the embodiments, but is limited only by the claims.

[0186] FIG. 9 is a hardware configuration diagram showing the configuration of a computer 1100 according to this embodiment. The computer 1100 includes a processor 1110 , a main memory 1120 , storage 1130 , and an interface 1140 .

[0187] The above-described control device 150 is implemented in a computer 1100. The operations of the above-described processing units are stored in the form of a program in storage 1130. The processor 1110 reads the program from storage 1130, loads it into main memory 1120, and executes the above-described processing in accordance with the program. The processor 1110 also allocates a storage area in main memory 1120 corresponding to the above-described storage unit 156 in accordance with the program.

[0188] The program may be for realizing part of the functions to be performed by the computer 1100. For example, the program may be for performing the functions by combining with another program already stored in the storage 1130 or by combining with another program installed in another device.

[0189] Furthermore, the computer 1100 may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions implemented by the processor 1110 may be implemented by the integrated circuit.

[0190] Examples of storage 1130 include a magnetic disk, a magneto-optical disk, a semiconductor memory, etc. Storage 1130 may be an internal medium directly connected to the bus of computer 1100, or an external medium connected to computer 1100 via interface 1140 or a communication line.

[0191] Furthermore, when this program is distributed to the computer 1100 via a communication line, the computer 1100 that receives the program may load the program into the main memory 1120 and execute the above processing. In the above embodiment, the storage 1130 is a non-transitory tangible storage medium.

[0192] The program may also be a program for realizing part of the above-described functions. Furthermore, the program may be a so-called differential file (differential program) that realizes the above-described functions in combination with another program already stored in storage 1130.

[0193] 10, the configuration described in the second embodiment and the configuration described in the third embodiment may be combined, which also provides the same effects as the above embodiments.

[0194] In addition, in the first and second embodiments, a configuration has been described in which the center line of the rotating shaft 10 and the center line of the output shaft 51 are on the same straight line (on the axis O), but this does not necessarily mean that they are completely on the same straight line, and also includes cases in which they are slightly misaligned.

[0195] In the first and second embodiments, the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 share the axis O as their center line, but the present invention is not limited to this configuration. The center lines of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 may not only be completely aligned as the axis O, but may also be slightly misaligned or tilted.

[0196] In the first and second embodiments, the center line of the rotary shaft 10 and the center line of the output shaft 51 do not have to be on the same straight line. That is, the output shaft 51 may be configured to be eccentric with respect to the rotary shaft 10.

[0197] Furthermore, the high-pressure stage compressor 22 in the first and second embodiments may be disposed between the low-pressure stage compressor 21 and the steam turbine 30. That is, the high-pressure stage compressor 22 may be disposed on the rotating shaft 10 on the other side in the axial direction Da of the low-pressure stage compressor 21 and on the one side in the axial direction Da of the steam turbine 30.

[0198] Furthermore, the steam turbine 30 in the first and second embodiments may be disposed on one side of the compression section 20 in the axial direction Da.

[0199] Furthermore, the steam turbine 30 in the first and second embodiments may be disposed between the low-pressure stage compressor 21 and the high-pressure stage compressor 22 of the compression section 20. In this case, the low-pressure stage compressor 21 may be disposed on one side of the high-pressure stage compressor 22 in the axial direction Da, or may be disposed on the other side of the high-pressure stage compressor 22 in the axial direction Da.

[0200] In the first and second embodiments, the first rotating shaft 11 and the second rotating shaft 12, and the first rotating shaft 11 and the turbine rotating shaft 13 are connected by joints, but the present invention is not limited to this configuration. For example, they may be connected together by welding or fastening with bolts or the like.

[0201] In addition, in the first and second embodiments, the rotating shaft 10 is formed by the turbine rotating shaft 13 in the steam turbine 30, the first rotating shaft 11 in the low-pressure stage compressor 21, and the second rotating shaft 12 in the high-pressure stage compressor 22, but is not limited to this configuration.

[0202] As an example of the above, instead of a configuration in which the steam turbine 30, the low-pressure stage compressor 21, and the high-pressure stage compressor 22 have their respective drive shafts (first rotating shaft 11, second rotating shaft 12, and turbine rotating shaft 13), the chemical plant compressor train 1 may be configured to have one rotating shaft, and the steam turbine 30, the low-pressure stage compressor 21, and the high-pressure stage compressor 22 may use this rotating shaft as a common drive shaft. This eliminates the need to use members for connecting the drive shafts, for example.

[0203] Furthermore, the compressor train 1 for a chemical plant in the first and second embodiments may further include a speed increaser that connects the turbine rotating shaft 13 and the low-pressure stage compressor 21 and is capable of increasing the rotation speed of the first rotating shaft 11 to a speed higher than the rotation speed of the turbine rotating shaft 13.

[0204] Furthermore, the compressor train 1 for a chemical plant in the first and second embodiments may be provided with a speed increaser instead of the speed increaser 40, which connects the turbine rotating shaft 13 and the low-pressure stage compressor 21 and is capable of increasing the rotation speed of the first rotating shaft 11 to a speed higher than the rotation speed of the turbine rotating shaft 13.

[0205] In addition, in the second embodiment, the determination of whether the amount of steam G introduced into the steam turbine 30 exceeds a predetermined threshold value may be based on the measurement results obtained by measuring the flow rate and flow velocity of the steam G introduced into the steam turbine 30 using a flow meter, flow velocity meter, etc. installed in the steam introduction line 201.

[0206] In addition, in the second embodiment, the determination of whether the amount of steam G introduced into the steam turbine 30 exceeds a predetermined threshold value may be based on the detection result of detecting the temperature of the process gas P that has passed through the compression section 20 using a temperature sensor or the like installed in the gas discharge line 20c.

[0207] Furthermore, the first axis O1, the second axis O2, and the turbine axis O3 in the third embodiment are not limited to being parallel to the axis O. The first axis O1, the second axis O2, the turbine axis O3, and the axis O may be skewed relative to one another.

[0208] Furthermore, the speed-increasing gear 400 in the third embodiment can be disconnected from the first rotating shaft 11 and the second rotating shaft 12, leaving only the motor 50 and the turbine rotating shaft 13 connected, but is not limited to this configuration. For example, the speed-increasing gear 400 may temporarily disconnect from the output shaft 51 of the motor 50, leaving only the turbine rotating shaft 13, the first rotating shaft 11, and the second rotating shaft 12 connected to each other. The speed-increasing gear 400 may be able to switch these connection modes as appropriate.

[0209] Furthermore, the parallel gears of the speed increaser 400 in the third embodiment can increase the rotational speed of the turbine rotating shaft 13, the first rotating shaft 11, and the second rotating shaft 12 in this order so that the rotational speed becomes higher than the rotational speed of the output shaft 51 of the motor 50, but this order is not limited to this. The parallel gears may also be able to increase the rotational speed of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 in this order so that the rotational speed becomes higher than the rotational speed of the output shaft 51 of the motor 50, for example. The parallel gears of the speed increaser 400 may be able to appropriately switch the order of the rotational speed magnitude of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13.

[0210] Furthermore, although the parallel gears of the speed increaser 400 in the third embodiment can increase the rotational speeds of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 to different speeds, the present invention is not limited to this configuration. The parallel gears may be capable of increasing the rotational speeds of two of the first rotating shaft 11, the second rotating shaft 12, and the turbine rotating shaft 13 to the same rotational speed, or may be capable of increasing the rotational speeds of all of them to the same rotational speed.

[0211] Furthermore, the axis O, the first axis O1, the second axis O2, and the turbine axis O3 in the above embodiments are not limited to a configuration in which they extend horizontally, and may extend at a slight inclination relative to the horizontal.

[0212] Moreover, the compression section 20 in the above embodiment may further include an intercooler or the like that is provided in the intermediate line 20b and that cools the process gas P compressed by the low-pressure stage compressor 21.

[0213] Furthermore, although the compression section 20 in the above embodiment has a low-pressure stage compressor 21 and a high-pressure stage compressor 22, this configuration is not limited to this, and the compression section 20 may be configured by a single compressor. Furthermore, the compression section 20 may be configured by two or more compressors (multi-stage compressor).

[0214] Furthermore, the motor 50 and the generator 70 in the above embodiment may be independent devices rather than being the same device. In this case, it is sufficient that the motor body 52 is fixed integrally to the output shaft 51 and the generator 70 is provided on the output shaft 51 of the motor 50.

[0215] Furthermore, the steam flow rate determination unit 155 of the control device 150 described in the fourth embodiment may further determine that "the amount of steam is excessive" when the amount of steam G flowing through the steam inlet line 201 is equal to or greater than a predetermined upper limit amount. This upper limit amount is set, for example, to a value greater than the rated steam amount flowing into the steam turbine 30 during rated operation of the steam turbine 30 (prescribed amount<rated steam amount<upper limit amount). The upper limit amount may be stored in advance in the storage unit 156 of the control device 150, for example.

[0216] When the steam flow rate determination unit 155 determines that "the amount of steam is excessive," the steam switching unit 151 may operate the governing valve 240 and the dump valve 250 so that the amount of steam G flowing into the steam turbine 30 is less than the upper limit amount. Specifically, the steam switching unit 151 may reduce the opening degree of the governing valve 240 and increase the opening degree of the dump valve 250, so that the amount of steam G flowing into the steam turbine 30 is less than the upper limit amount.

[0217] 11, the compressor train 1 for a chemical plant described in the fourth embodiment may further include a spray line 300, a spray nozzle 310, a spray pump 320, and a temperature sensor 330. The configurations of the spray line 300, the spray nozzle 310, and the temperature sensor 330 will be described below.

[0218] The spray line 300 is a pipe through which water W flows. One end of the spray line 300 is connected to equipment external to the steam turbine 30, and the other end of the spray line 300 is disposed, for example, inside the casing body of the steam turbine 30 on one side in the axial direction Da of the last stage rotor blade 302a.

[0219] An example of the external device to which one end of the spray line 300 is connected is the condenser 90. Therefore, in this case, water W stored in the condenser 90 flows through the spray line 300 toward the inside of the steam turbine 30.

[0220] The spray nozzle 310 is integrally connected to the other end of the spray line 300. By being connected to the spray line 300, the spray nozzle 310 can spray water W inside the casing main body.

[0221] The spray pump 320 is disposed in the spray line 300. The spray pump 320 is driven by receiving a signal indicating a drive instruction from the control device 150, and directs water W from an external device (condenser 90) into the spray line 300 toward the inside of the steam turbine 30.

[0222] The temperature sensor 330 is disposed inside the casing body of the steam turbine 30. The temperature sensor 330 detects the temperature inside the casing body. The temperature sensor 330 transmits a signal indicating the detected temperature to the control device 150.

[0223] In this case, the control device 150 may further include, for example, a temperature detection unit (not shown) that can detect the internal temperature of the steam turbine 30 by receiving a signal transmitted from the temperature sensor 330, a temperature determination unit (not shown) that determines the internal temperature of the steam turbine 30 by comparing the temperature detected by the temperature detection unit with a predetermined temperature threshold, and a spray pump drive unit (not shown) that drives the spray pump 320 based on the determination result of the temperature determination unit.

[0224] The temperature detection unit sends a signal indicating the temperature detected by the temperature sensor 330 to the temperature determination unit. The temperature determination unit determines that "the temperature inside the steam turbine is abnormal" when the detection result (the temperature inside the steam turbine 30) received from the temperature detection unit indicates a temperature equal to or higher than the temperature threshold. On the other hand, the temperature determination unit determines that "the temperature inside the steam turbine is not abnormal" when the detection result received from the temperature detection unit indicates a temperature lower than the temperature threshold. The temperature determination unit transmits a signal indicating the determination result to the spray pump drive unit.

[0225] If the determination result of the temperature determination unit indicates that "the temperature inside the steam turbine is abnormal," the spray pump driving unit transmits a signal instructing the spray pump to be driven to the spray pump 320. On the other hand, if the determination result of the temperature determination unit indicates that "the temperature inside the steam turbine is not abnormal," the spray pump driving unit transmits a signal instructing the spray pump to be stopped to the spray pump 320.

[0226] 11, it is possible to prevent the temperature inside the steam turbine 30 (inside the casing body) from rising above the temperature threshold value while the steam turbine 30 is in operation. Therefore, for example, it is possible to further prevent damage to components of the steam turbine 30 inside the steam turbine 30.

[0227] Furthermore, the vacuum pump 120 described in the fourth embodiment may directly suck air from inside the steam turbine 30 without going through the condenser 90 .

[0228] Furthermore, in each of the above embodiments, the configuration of the compressor train 1 for a chemical plant that operates in the ammonia plant 100 has been described, but the configuration is not limited to this, and the compressor train 1 for a chemical plant may operate in a chemical plant such as an LNG plant or an ethylene plant.

[0229] Furthermore, the configurations of the compressor train 1 for a chemical plant described in each of the above embodiments do not have to be independent configurations, and the compressor train 1 for a chemical plant may be configured by appropriately combining the components described in each embodiment.

[0230] [Note] The compressor train for a chemical plant and the operating method of the compressor train for a chemical plant described in each embodiment can be understood, for example, as follows.

[0231] (1) A compressor train 1 for a chemical plant according to a first embodiment includes a compression section 20 that compresses process gas P of the chemical plant when driven, a steam turbine 30 that drives the compression section 20 when rotated by steam G generated in the processing of the process gas P of the chemical plant, a motor 50 that can assist the rotation of the steam turbine 30, and a frequency conversion section 60 that is connected to a power system Gr and controls the rotation of the motor 50.

[0232] This makes it possible to increase the rotation speed of the compression section 20 even when the amount of steam introduced into the steam turbine 30 is insufficient for the amount of steam required for the rated rotation of the compression section 20. Furthermore, when the rotation speed of the steam turbine 30 is increased, an increase in the amount of steam introduced into the steam turbine 30 can be suppressed.

[0233] (2) A second aspect of the compressor train 1 for a chemical plant is the compressor train 1 for a chemical plant of (1), wherein the motor 50 also serves as a generator 70 capable of generating regenerative power in conjunction with the rotation of the steam turbine 30 when the amount of steam G generated exceeds a predetermined threshold, and the frequency conversion unit 60 may be capable of transmitting the regenerative power to the power system Gr.

[0234] This allows the regenerative power generated using the excess steam G to be sold to the power grid Gr. In other words, the power purchased from the power grid Gr to drive the motor 50 as an auxiliary for the steam turbine 30 can be partially offset.

[0235] (3) The compressor train 1 for a chemical plant according to the third aspect may be the compressor train 1 for a chemical plant according to (1) or (2), and may further include an axial seal device 140 that seals the gap between the stator (turbine stator 30a) of the steam turbine 30 and the rotor (turbine rotor 30b) of the steam turbine 30, and a vacuum pump 120 that can reduce the pressure inside the steam turbine 30 when driven.

[0236] This allows the pressure inside the steam turbine 30 to be reduced while the steam turbine 30 is sealed by the shaft seal device 140. That is, the inside of the steam turbine 30 can be evacuated. Therefore, for example, the steam turbine 30 can start to be driven by the motor 50 while the pressure inside the steam turbine 30 is reduced. As a result, for example, the load on the motor 50 when the steam turbine 30 starts to be driven can be reduced.

[0237] (4) A compressor train 1 for a chemical plant according to a fourth aspect is the compressor train 1 for a chemical plant of (3), further comprising a control device 150 for controlling the operating status of the steam turbine 30. The control device 150 may include: a vacuum pump drive unit that drives the vacuum pump 120 to reduce the pressure inside the steam turbine 30 when the flow of the steam G generated by the treatment of the process gas P into the steam turbine 30 is stopped; a motor start unit 153a that starts driving the motor 50 when the pressure inside the steam turbine 30 is reduced and the flow of the steam G into the steam turbine 30 is stopped, thereby starting to drive the steam turbine 30; a motor drive unit 153b that continues to drive the motor 50; and a steam switching unit 151 that starts the flow of the steam G into the steam turbine 30 when the amount of the steam G generated by the drive of the motor 50 becomes equal to or greater than a specified amount when the motor 50 continues to drive.

[0238] This allows the steam turbine 30 to be driven with the pressure inside the steam turbine 30 reduced until the amount of steam G generated reaches or exceeds a specified amount. Therefore, for example, it is possible to suppress an increase in the temperature inside the steam turbine 30 when the steam turbine 30 starts to be driven. Also, it is possible to suppress an increase in the load on the motor 50 when the steam turbine 30 starts to be driven.

[0239] (5) A fifth aspect of the compressor train 1 for a chemical plant is the compressor train 1 for a chemical plant of (4), wherein the control device 150 further has a motor deceleration unit 153c that decelerates the rotation of the motor 50, and the steam switching unit 151 may stop the flow of the steam G into the steam turbine 30 when the rotation of the motor 50 is decelerated and the amount of the steam G becomes less than the specified amount.

[0240] As a result, when the amount of generated steam G falls below a specified amount, the flow of steam G into the steam turbine 30 can be stopped. Therefore, for example, it is possible to suppress an increase in the temperature inside the steam turbine 30 when the operation of the steam turbine 30 is stopped. Also, it is possible to suppress an increase in the load on the motor 50 when the operation of the steam turbine 30 is stopped.

[0241] (6) A compressor train 1 for a chemical plant according to a sixth aspect is the compressor train 1 for a chemical plant according to (4) or (5), and includes a steam inlet line 201 capable of guiding the steam G generated in association with the treatment of the process gas P in the chemical plant to the steam turbine 30, a steam discharge line 202 capable of guiding the steam G discharged from the steam turbine 30 to the condenser 90, a connection line 160 capable of guiding the steam G flowing through the steam inlet line 201 to the condenser 90, and The steam turbine 30 may further include a governing valve 240 arranged on the line 201 closer to the steam turbine 30 than the connection point with the connection line 160, and capable of adjusting the amount of steam G flowing through the steam inlet line 201, and a dump valve 250 arranged on the connection line 160, and capable of adjusting the amount of steam G flowing through the connection line 160, and the steam switching unit 151 may start or stop the flow of steam G into the steam turbine 30 by switching between the governing valve 240 and the dump valve 250.

[0242] This makes it possible to realize the above-mentioned effect with a more specific configuration. Furthermore, when governing valve 240 is closed and dump valve 250 is opened, steam G flowing through steam inlet line 201 is introduced into condenser 90. Therefore, there is no need to provide a separate device in the chemical plant (ammonia plant 100) for receiving steam G flowing through steam inlet line 201. This makes it possible to prevent the chemical plant from becoming larger.

[0243] (7) A seventh aspect of the present invention relates to an operating method for a compressor train 1 for a chemical plant, which is the operating method for a compressor train 1 for a chemical plant of (3), and includes the following steps: a vacuum pumping step S1 in which the vacuum pump 120 is driven to reduce the pressure inside the steam turbine 30 while the flow of the steam G generated by the treatment of the process gas P into the steam turbine 30 is stopped; a motor starting step S2 in which the motor 50 is started to be driven to start driving the steam turbine 30 while the flow of the steam G into the steam turbine 30 is stopped after the vacuum pumping step S1 is completed; a motor driving step S3 in which the motor 50 is continued to be driven after the motor starting step S2 is completed; and a first steam switching step S5 in which the flow of the steam G into the steam turbine 30 is started when the amount of the steam G generated by the driving of the motor 50 becomes equal to or greater than a specified amount while the motor 50 is continuing to be driven.

[0244] (8) The operating method of a compressor train 1 for a chemical plant according to the eighth aspect is the operating method of a compressor train 1 for a chemical plant according to (7), and may further include a motor deceleration step S7 for decelerating the rotation of the motor 50, and a second steam switching step S9 for stopping the flow of the steam G into the steam turbine 30 when the rotation of the motor 50 is decelerated and the amount of the steam G becomes less than the specified amount. [Industrial Applicability]

[0245] According to the present disclosure, it is possible to provide a compressor train for a chemical plant and an operating method of a compressor train for a chemical plant that can stabilize the pressure of process gas compressed by a compression section. [Explanation of symbols]

[0246] 1...Compressor train for chemical plant 10...Rotating shaft 11...First rotating shaft 12...Second rotating shaft 13...Turbine rotating shaft 20...Compression section 20a...Gas introduction line 20b...Intermediate line 20c...Gas discharge line 21...Low pressure stage compressor 22...High pressure stage compressor 30...Steam turbine 30a...Turbine stator 30b...Turbine rotor 40, 400...Speed-up gear 50...Motor 51...Output shaft 52...Motor body 60...Frequency conversion section 61a...First power purchase cable 61b...Second power purchase cable 62a...First power sales cable 62b...Second power sales cable 70...Generator 80,800...Reduction gear 90...Condenser 95...Condensate pump 100...Ammonia plant 110...Gland condenser 120...Vacuum pump 125...Vapor fan 130...Drain separator 131...Seal protrusion 140...Shaft seal device 141...Housing 141a...Groove 141b...Accommodation recess 141c...Communicating portion 142...Seal member 142a...Pressure receiving portion 142b...Base portion 142c...Coupling portion 142d...Seal body 143...Biasing member 150...Control device 151...Steam switching portion 151a...Governing valve operating portion 151b...Dump valve operating portion 152...Vacuum pump control portion 153...Motor control portion 153a...Motor starting portion 153b...Motor driving portion 153c...Motor reduction portion 154...Steam flow rate detection portion 155...Steam flow rate determination unit 156...Memory unit 160...Connection line 170...Drainage line 180...Circulation line 190...Condensate recovery line 200...Ammonia converter 200a...Boiler 201...Steam inlet line 202...Steam exhaust line 210...First suction line 220...Second suction line 230...Leak steam line 240...Governing valve 250...Dump valve 260...First on-off valve 270...Second on-off valve 290...Flow rate sensor 300...Spray line 310...Spray nozzle 320...Spray pump 330...Temperature sensor 301a...Turbine casing 301b...Stator vane 302a...Moving blade 1100...Computer 1110...Processor 1120...Main memory 1130...Storage 1140...Interface Da...Axial direction G...Steam Gr...Power system O...Axis O1...First axis O2...Second axis O3...Turbine axis P...Process gas S1...Vacuum drawing process S2...Motor starting process S3...Motor driving process S4...First steam flow rate determination process S5...First steam switching process S6...Turbine operating process S7...Motor deceleration process S8...Second steam flow rate determination process S9...Second steam switching process W...Water

Claims

1. a compression unit that is driven to compress process gas of the chemical plant; a steam turbine that is rotated by steam generated in the process gas treatment of the chemical plant to drive the compression section; a motor capable of assisting the rotation of the steam turbine; a frequency conversion unit connected to a power grid to control the rotation of the motor; a shaft seal device that seals a gap between a stator of the steam turbine and a rotor of the steam turbine; a vacuum pump that can reduce the pressure inside the steam turbine when driven; a control device for controlling an operating condition of the steam turbine, The control device a vacuum pump driving unit that drives the vacuum pump while the flow of the steam generated by the treatment of the process gas into the steam turbine is stopped, thereby reducing the pressure inside the steam turbine; a motor starting unit that starts driving the motor to start driving the steam turbine in a state where the pressure inside the steam turbine has decreased and the flow of the steam into the steam turbine has been stopped; a motor driving unit that continues to drive the motor; a steam switching unit that starts the flow of the steam into the steam turbine when an amount of the steam generated by the driving of the motor reaches or exceeds a specified amount while the motor continues to drive; A compressor train for a chemical plant having:

2. the motor also functions as a generator capable of generating regenerative power in association with rotation of the steam turbine when an amount of steam generated exceeds a predetermined threshold; The compressor train for a chemical plant according to claim 1 , wherein the frequency conversion unit is capable of transmitting the regenerated power to the power grid.

3. the control device further includes a motor speed reducer that reduces the rotation speed of the motor, 3. The compressor train for a chemical plant according to claim 1, wherein the steam switching unit stops the flow of the steam into the steam turbine when the rotation of the motor is decelerated and the amount of the steam becomes less than the specified amount.

4. a steam introduction line capable of introducing the steam generated in association with the treatment of the process gas in the chemical plant to the steam turbine; a steam discharge line capable of guiding steam discharged from the steam turbine to a condenser; a connection line capable of guiding the steam flowing through the steam introduction line to the condenser; a governing valve that is arranged on the steam turbine side of a connection point between the steam inlet line and the connection line and that is capable of adjusting the amount of steam flowing through the steam inlet line; a dump valve disposed in the connecting line and capable of adjusting the amount of steam flowing through the connecting line; Further provided with 3. The compressor train for a chemical plant according to claim 1, wherein the steam switching unit starts or stops the flow of the steam into the steam turbine by switching the governing valve and the dump valve.

5. A compression unit that compresses process gas in a chemical plant when driven; a steam turbine that is rotated by steam generated in the process gas treatment of the chemical plant to drive the compression section; a motor capable of assisting the rotation of the steam turbine; a frequency conversion unit connected to a power grid to control the rotation of the motor; a shaft seal device that seals a gap between a stator of the steam turbine and a rotor of the steam turbine; a vacuum pump that is driven to reduce a pressure inside the steam turbine, the method comprising: a vacuum pumping step of driving the vacuum pump to reduce the pressure inside the steam turbine while stopping the flow of the steam generated by the treatment of the process gas into the steam turbine; a motor starting process for starting to drive the steam turbine by starting to drive the motor while the flow of the steam into the steam turbine is stopped after the evacuation process is completed; a motor driving step of continuing to drive the motor after the motor starting step is completed; a first steam switching step of starting a flow of the steam into the steam turbine when an amount of the steam generated in association with the driving of the motor becomes equal to or greater than a specified amount while the motor continues to be driven; A method for operating a compressor train for a chemical plant that performs the above.

6. a motor deceleration step of decelerating the rotation of the motor; a second steam switching step of stopping the flow of the steam into the steam turbine when the rotation speed of the motor is decelerated and the amount of the steam becomes less than the specified amount; 6. The method of operating a compressor train for a chemical plant according to claim 5, further comprising:

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