US-12624702-B2 - Compressor train of chemical plants and method of operating compressor train of chemical plants

US12624702B2US 12624702 B2US12624702 B2US 12624702B2US-12624702-B2

Abstract

A compressor train of chemical plants includes: a compression unit which is driven to compress a process gas of the chemical plants; a steam turbine which is rotated by steam generated in accordance with the processing of the process gas of the chemical plants to drive the compression unit; a motor which is able to assist the rotation of the steam turbine; and a frequency conversion unit which is connected to an electric power system and controls the rotation of the motor.

Inventors

Satoru Yoshida
Daisuke Kiuchi
Yuta Miwada
Tomoaki Nogami

Assignees

MITSUBISHI HEAVY INDUSTRIES COMPRESSOR CORPORATION

Dates

Publication Date: 20260512
Application Date: 20220810
Priority Date: 20210924

Claims (6)

1 . A compressor train of a chemical plant comprising: a compression unit which is driven to compress a process gas of the chemical plant; a steam turbine which is rotated by steam generated in accordance with processing of the process gas of the chemical plant to drive the compression unit; a motor which is able to assist a rotation of the steam turbine; a frequency conversion unit which is connected to an electric power system and controls a rotation of the motor; a shaft seal device which seals a gap between a stator of the steam turbine and a rotor of the steam turbine; a vacuum pump which is driven to be able to reduce pressure inside the steam turbine; and a control device which controls an operating status of the steam turbine, wherein the control device includes a vacuum pump driving unit which reduces the pressure inside the steam turbine by driving the vacuum pump while an inflow of the steam generated in accordance with the processing of the process gas into the steam turbine is stopped, a motor starting section which starts to drive the steam turbine by starting to drive the motor while the pressure inside the steam turbine is reduced and the inflow of the steam into the steam turbine is stopped, a motor driving section which continues to drive the motor, and a steam switching unit which starts the inflow of the steam into the steam turbine when an amount of the steam generated in accordance with a driving of the motor becomes a specified amount or more while the motor continues to drive.
2 . The compressor train according to claim 1 , wherein the motor also serves as a generator that is able to generate regenerative power in accordance with the rotation of the steam turbine when the amount of the steam generated exceeds a predetermined threshold value, and the frequency conversion unit is able to transmit the regenerative power to the electric power system.
3 . The compressor train according to claim 1 , wherein the control device further includes a motor decelerating section which decelerates the rotation of the motor, and the steam switching unit stops the inflow of the steam into the steam turbine when the rotation of the motor is decelerated and the amount of the steam becomes smaller than the specified amount.
4 . The compressor train according to claim 1 , further comprising: a steam introduction line which is able to guide the steam generated in accordance with the processing of the process gas of the chemical plant to the steam turbine; a steam discharge line which is able to guide the steam discharged from the steam turbine to a condenser; a connection line which is able to guide the steam flowing through the steam introduction line to the condenser; a governing valve which is disposed at a position closer to the steam turbine than a connection point between the connection line and the steam introduction line in the steam introduction line and is able to adjust the amount of the steam flowing through the steam introduction line; and a dump valve which is disposed in the connection line and is able to adjust the amount of the steam flowing through the connection line, wherein the steam switching unit starts or stops the inflow of the steam into the steam turbine by switching the governing valve and the dump valve.
5 . A method of operating a compressor train of a chemical plant comprising: a compression unit which is driven to compress a process gas of the chemical plant; a steam turbine which is rotated by steam generated in accordance with processing of the process gas of the chemical plant to drive the compression unit; a motor which is able to assist a rotation of the steam turbine; a frequency conversion unit which is connected to an electric power system and controls a rotation of the motor; a shaft seal device which seals a gap between a stator of the steam turbine and a rotor of the steam turbine; and a vacuum pump which is driven to be able to reduce pressure inside the steam turbine, the method comprising: an evacuation step of reducing the pressure inside the steam turbine by driving the vacuum pump while an inflow of the steam generated in accordance with the processing of the process gas into the steam turbine is stopped; a motor starting step of starting to drive the steam turbine by starting to drive the motor while the inflow of the steam into the steam turbine is stopped after the evacuation step is completed; a motor driving step of continuing to drive the motor after the motor starting step is completed; and a first steam switching step of starting the inflow of the steam into the steam turbine when an amount of the steam generated in accordance with the driving of the motor becomes a specified amount or more while the motor continues to drive.
6 . The method according to claim 5 , further comprising: a motor decelerating step of decelerating the rotation of the motor; and a second steam switching step of stopping the inflow of the steam into the steam turbine when the rotation of the motor is decelerated and the steam amount becomes smaller than the specified amount.

Description

TECHNICAL FIELD The present disclosure relates to a compressor train of chemical plants and a method of operating a compressor train of chemical plants. Priority is claimed on Japanese Patent Application No. 2021-155311, filed Sep. 24, 2021, the content of which is incorporated herein by reference. BACKGROUND ART For example, Patent Document 1 discloses an ammonia production compressor system used in an ammonia plant as a chemical plant that produces ammonia. This ammonia production compressor system includes low-pressure side and high-pressure side compressors (hereinafter, referred to as compression units), and a drive machine (steam turbine) that drives the compression units. CITATION LIST Patent Document Patent Document 1 Japanese Unexamined Patent Application, First Publication No. 2000-154020 SUMMARY OF INVENTION Technical Problem Incidentally, in chemical plants such as ammonia plants, when the rated rotational speed in the compression unit is increased or when the amount of steam generated in the manufacturing process is decreased, the amount of steam introduced into the steam turbine may be insufficient compared to the amount of steam required for the rated rotation of the compression unit. In this case, in the technique described in Patent Document 1, there is a problem unique to chemical plants in that the rotational speed of the compression unit is not easily stabilized and the pressure of the process gas compressed by the compression unit is unstable. The present disclosure has been made to solve the above-described problems and an object of the present disclosure is to provide a compressor train of chemical plants capable of stabilizing the pressure of a process gas compressed by a compression unit and a method of operating the compressor train of chemical plants. Solution to Problem In order to achieve the aforementioned objects, a compressor train of chemical plants according to the present disclosure includes: a compression unit which is driven to compress a process gas of the chemical plants; a steam turbine which is rotated by steam generated in accordance with the processing of the process gas of the chemical plants to drive the compression unit; a motor which is able to assist a rotation of the steam turbine; and a frequency conversion unit which is connected to an electric power system and controls a rotation of the motor. A method of operating a compressor train of chemical plants according to the present disclosure is a method of operating a compressor train of chemical plants including a compression unit which is driven to compress a process gas of the chemical plants, a steam turbine which is rotated by steam generated in accordance with the processing of the process gas of the chemical plants to drive the compression unit, a motor which is able to assist the rotation of the steam turbine, a frequency conversion unit which is connected to an electric power system and controls the rotation of the motor, a shaft seal device which seals a gap between a stator of the steam turbine and a rotor of the steam turbine, and a vacuum pump which is driven to be able to reduce the pressure inside the steam turbine, the method including: an evacuation step of reducing the pressure inside the steam turbine by driving the vacuum pump while the inflow of the steam generated in accordance with the processing of the process gas into the steam turbine is stopped; a motor starting step of starting to drive the steam turbine by starting to drive the motor while the inflow of the steam into the steam turbine is stopped after the evacuation step is completed; a motor driving step of continuing to drive the motor after the motor starting step is completed; and a first steam switching step of starting the inflow of the steam into the steam turbine when amount of the steam generated in accordance with the driving of the motor becomes a specified amount or more while the motor continues to drive. Advantageous Effects of Invention According to the present disclosure, it is possible to provide the compressor train of chemical plants capable of stabilizing the pressure of the process gas compressed by the compression unit and the method of operating the compressor train of chemical plants. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a configuration of a compressor train of chemical plants according to a first embodiment of the present disclosure. FIG. 2 is a schematic view showing a configuration of a compressor train for a chemical plant according to a second embodiment of the present disclosure. FIG. 3 is a schematic view showing a configuration of a compressor train for a chemical plant according to a third embodiment of the present disclosure. FIG. 4 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. FIG. 5 is a diagram showing a configuration of a shaft seal device according