Raw material gas liquefying device and method of controlling this raw material gas liquefying device

Patent metadata

Field	Value
Publication number	US-11808502-B2
Application number	US-201716465430-A
Country	US
Kind code	B2
Filing date	Dec 4, 2017
Priority date	Dec 8, 2016
Publication date	Nov 7, 2023
Grant date	Nov 7, 2023

Abstract

A raw material gas liquefying device includes a feed line which feeds a raw material gas, a refrigerant circulation line which circulates a refrigerant, the refrigerant circulation line including an expansion unit of a turbine type which expands the refrigerant to generate cryogenic energy, and an expansion unit entrance valve provided at an entrance side of the expansion unit, a heat exchanger which exchanges heat between the raw material gas and the refrigerant, a cooler which performs initial cooling of the raw material gas and the refrigerant by heat exchange with liquid nitrogen, and a controller which manipulates the opening rate of the expansion unit entrance value and performs a feedback control so that the rotation speed of the expansion unit reaches a predetermined target value, and outputs the opening rate command to the expansion unit entrance valve, at start-up and stop of the expansion unit.

First claim

The invention claimed is:

1. A raw material gas liquefying device comprising:
a feed line which feeds a raw material gas whose boiling temperature is lower than a boiling temperature of nitrogen;
a refrigerant circulation line which circulates a refrigerant for cooling the raw material gas, the refrigerant circulation line including an expansion unit of a turbine type which expands the refrigerant to generate cryogenic energy, and an expansion unit entrance valve provided at an entrance side of the expansion unit;
a heat exchanger which exchanges heat between the raw material gas and the refrigerant;
a cooler which performs initial cooling of the raw material gas and the refrigerant by heat exchange with liquid nitrogen;
an expansion unit rotation speed sensor which detects a rotation speed of the expansion unit; and
a controller configured to manipulate an opening rate of the expansion unit entrance valve, wherein:
before start-up of the expansion unit, the opening rate of the expansion unit entrance valve is manipulated so that the expansion unit entrance valve opened and a flow rate of the refrigerant flowing into the expansion unit is reaching a predetermined initial cooling flow rate, a flow of the refrigerant with the predetermined initial cooling flow rate through the expansion unit does not rotate the expansion unit, and
at the start-up and stop of the expansion unit, the opening rate of the expansion unit entrance valve is manipulated, by performing a feedback control, so that the rotation speed of the expansion unit reaches a predetermined target value.

2. The raw material gas liquefying device according to claim 1 ,
wherein at the start-up of the expansion unit,
the controller is configured to:
generate a first opening rate for the expansion unit entrance valve with reference to a predetermined valve opening rate schedule which increases the rotation speed of the expansion unit to a predetermined maximum rotation speed set value which is lower than a critical speed zone of the expansion unit;
generate a second opening rate for the expansion unit entrance valve by performing a feedback control so that the rotation speed of the expansion unit reaches the predetermined maximum rotation speed set value which is the target value; and
manipulate the opening rate of the expansion unit entrance valve to one of the first opening rate and the second opening rate which is smaller.

3. The raw material gas liquefying device according to claim 1 ,
wherein in a case where the rotation speed of the expansion unit is increased from a predetermined rotation speed which is outside a critical speed zone of the expansion unit, to a rated rotation speed of the expansion unit, at start-up of the expansion unit,
the controller is configured to decide the target value with reference to a predetermined rotation speed increase schedule which increases the rotation speed of the expansion unit while causing a temperature change of the heat exchanger which is associated with a change of the rotation speed of the expansion unit to be within a predetermined allowable range.

4. The raw material gas liquefying device according to claim 1 ,
wherein in a case where the rotation speed of the expansion unit is reduced from a rated rotation speed of the expansion unit to a predetermined rotation speed before stop of the expansion unit, which is outside a critical speed zone of the expansion unit, at stop of the expansion unit,
the controller is configured to decide the target value with reference to a predetermined rotation speed reduction schedule which reduces the rotation speed of the expansion unit while causing a temperature change of the heat exchanger which is associated with a change of the rotation speed of the expansion unit to be within a predetermined allowable range.

5. The raw material gas liquefying device according to claim 1 ,
wherein the expansion unit includes a high-pressure expansion unit and a low-pressure expansion unit disposed downstream of the high-pressure expansion unit,
wherein the expansion unit entrance valve includes a high-pressure expansion unit entrance valve provided at an entrance side of the high-pressure expansion unit, and a low-pressure expansion unit entrance valve provided at an entrance side of a low-pressure expansion unit, and
wherein the controller is configured to control the rotation speed of the low-pressure expansion unit and the rotation speed of the high-pressure expansion unit so that the rotation speed of the high-pressure expansion unit reaches a predetermined rotation speed which is outside a critical speed zone of the high-pressure expansion unit after the rotation speed of the low-pressure expansion unit has reached a predetermined rotation speed which is outside a critical speed zone of the low-pressure expansion unit, and so that the rotation speed of the high-pressure expansion unit is increased from the predetermined rotation speed to a rated rotation speed of the high-pressure expansion unit, and the rotation speed of the low-pressure expansion unit is increased from the predetermined rotation speed to a rated rotation speed of the low-pressure expansion unit, after the rotation speed of the high-pressure expansion unit has reached the predetermined rotation speed and the rotation speed of the low-pressure expansion unit has reached the predetermined rotation speed.

6. A method of controlling a raw material gas liquefying device including:
a feed line which feeds a raw material gas whose boiling temperature is lower than a boiling temperature of nitrogen;
a refrigerant circulation line which circulates a refrigerant for cooling the raw material gas, the refrigerant circulation line including a turbine expansion unit which expands the refrigerant to generate cryogenic energy, and an expansion unit entrance valve provided at an entrance side of the expansion unit;
a heat exchanger which exchanges heat between the raw material gas and the refrigerant;
a cooler which performs initial cooling of the raw material gas and the refrigerant by heat exchange with liquid nitrogen; and
a controller which controls operations associated with the feed line and the refrigerant circulation line, the method comprising:
before start-up of the expansion unit, manipulating an opening rate of the expansion unit entrance valve so that the expansion unit entrance valve is opened and a flow rate of the refrigerant flowing into the expansion unit is reaching a predetermined initial cooling flow rate, a flow of the refrigerant with the predetermined initial cooling flow rate through the expansion unit does not rotate the expansion unit, and
at the start-up and stop of the expansion unit, manipulating the opening rate of the expansion unit entrance valve, by performing a feedback control, so that a rotation speed of the expansion unit reaches a predetermined target value.

7. The method of controlling the raw material gas liquefying device according to claim 6 ,
wherein at the start-up of the expansion unit,
a first opening rate for the expansion unit entrance valve is generated with reference to a predetermined valve opening rate schedule which increases the rotation speed of the expansion unit to a predetermined maximum rotation speed set value which is lower than a critical speed zone of the expansion unit,
a second opening rate for the expansion unit entrance valve is generated by performing the feedback control so that the rotation speed of the expansion unit reaches the predetermined maximum rotation speed set value which is the target value, and
the opening rate of the expansion unit entrance valve is manipulated to one of the first opening rate and the second opening rate whichever is smaller.

8. The method

Assignees

• Kawasaki Heavy Ind Ltd

Inventors

• Yamazoe Naotaka
• Sakamoto Tomohiro
• Miyazaki Hidetaka
• Kariya Daisuke
• Miwa Yasuo
• Saito Yuichi
• Kimura Yosuke

Classifications

• F25B9/06 Primary

  using expanders (F25B9/10 takes precedence) · CPC title

• F25J1/001 Primary

  Hydrogen · CPC title

• F25J1/005

  by expansion of a gaseous refrigerant stream with extraction of work · CPC title

• F25J1/0007

  Helium · CPC title

• F25J1/0052

  by vaporising a liquid refrigerant stream · CPC title