Turbo compressor and turbo chiller using same

Patent metadata

Field	Value
Publication number	US-10858951-B2
Application number	US-201414784821-A
Country	US
Kind code	B2
Filing date	Apr 9, 2014
Priority date	May 30, 2013
Publication date	Dec 8, 2020
Grant date	Dec 8, 2020

Abstract

The purpose of the present invention is to provide: a turbo compressor which is provided with an open impeller and has the minimal gap between the shroud and the impeller such that efficiency is improved and the safe operating region is enlarged; and a turbo chiller using the same. The turbo compressor is provided with an open impeller with a shroud provided on the side of a casing, and the rotary shaft is supported by a radial magnetic bearing and a magnetic thrust bearing. The turbo compressor is provided with a control unit that comprises: a load calculating means that calculates the axial thrust load generated by the pressure distribution of the compressor; and an axial support position control means that controls a gap between the impeller and the shroud to be a target gap by varying, on the basis of the axial thrust load, the axial support position of the rotary shaft due to the magnetic thrust bearing.

First claim

The invention claimed is:

1. A turbo compressor comprising:
an open impeller with a shroud provided on a casing side;
a rotary shaft which is supported by a radial magnetic bearing and a thrust magnetic bearing; and
a controller configured to
calculate an axial direction thrust load generated by a pressure distribution of the compressor on the basis of a front surface side thrust load and a rear surface side thrust load of the impeller, and
control a gap between the impeller and the shroud to at least two different target gaps including a minimum gap S 1 and a gap S 2 which is greater than the gap S 1 by changing an axial direction support position of the rotary shaft by controlling current values distributed and supplied to the thrust magnetic bearing on the basis of the axial direction thrust load,

wherein the controller, when an operation condition in which the axial direction thrust load is rapidly changed is detected, is configured to correct and control the axial direction support position of the rotary shaft determined by the thrust magnetic bearing from a position where the gap between the impeller and the shroud becomes the minimum target gap S 1 to a position where the gap between the impeller and the shroud becomes the second target gap S 2 that is greater than the minimum target gap S 1 to prevent the impeller from making contact with the shroud due to a position change of the rotary shaft in association with the rapid change in the axial direction thrust load.

2. The turbo compressor according to claim 1 ,
wherein the controller is further configured to correct the axial direction support position of the rotary shaft, by calculating the axial direction thrust load by detecting a change in a load and/or a change in a cooling water temperature, or on the basis of a correlation function set in advance.

3. The turbo compressor according to claim 1 ,
wherein one or more sensors include a second gap sensor which is provided at an outer diameter position of the impeller in addition to a gap sensor which is provided near the rotary shaft and/or the thrust magnetic bearing to detect the axial direction support position of the rotary shaft, and
said controller is further configured to correct the axial direction support position of the rotary shaft by using detection signals of the second gap sensor.

4. The turbo compressor according to claim 1 ,
wherein the controller is further configured to correct the axial direction support position of the rotary shaft by using a change in a control amount of an opening of an inlet vane of the compressor and/or a change in a rotation frequency control amount of the impeller.

5. The turbo compressor according to claim 1 ,
wherein one or more sensors include a second gap sensor which is provided at an outer diameter position of the impeller in addition to a gap sensor which is provided near the rotary shaft and/or the thrust magnetic bearing to detect the axial direction support position of the rotary shaft, and
said controller is further configured to correct the axial direction support position of the rotary shaft by using detection signals of the second gap sensor.

6. The turbo compressor according to claim 1 ,
wherein one or more sensors include a second gap sensor which is provided at an outer diameter position of the impeller in addition to a gap sensor which is provided near the rotary shaft and/or the thrust magnetic bearing to detect the axial direction support position of the rotary shaft, and
said controller is further configured to correct the axial direction support position of the rotary shaft by using detection signals of the second gap sensor.

7. The turbo compressor according to claim 1 ,
wherein the controller is further configured to correct the axial direction support position of the rotary shaft, by calculating the axial direction thrust load by detecting a change in a load and/or a change in a cooling water temperature, or on the basis of a correlation function set in advance.

8. The turbo compressor according to claim 1 ,
wherein the controller is further configured to correct the axial direction support position of the rotary shaft by using a change in a control amount of an opening of an inlet vane of the compressor and/or a change in a rotation frequency control amount of the impeller.

9. The turbo compressor according to claim 8 ,
wherein one or more sensors include a second gap sensor which is provided at an outer diameter position of the impeller in addition to a gap sensor which is provided near the rotary shaft and/or the thrust magnetic bearing to detect the axial direction support position of the rotary shaft, and
said controller is further configured to correct the axial direction support position of the rotary shaft by using detection signals of the second gap sensor.

10. The turbo compressor according to claim 1 ,
wherein the controller, when one or more sensors to detect an axial direction position of the rotary shaft is installed at a position distant from a compression section, detects a temperature of a desired part including the rotary shaft, the radial magnetic bearing that support the rotary shaft, and the casing, by means of temperature sensors provided in a motor room of the casing, calculates a change amount of the gap between the impeller and the shroud from an axial length change amount of the rotary shaft due to thermal expansion and an axial direction change amount of the casing which sets a relative positional relationship between the shroud and the impeller, and on the basis of this, corrects the axial direction support position.

11. The turbo compressor according to claim 1 , wherein an operation condition in which the axial thrust load is rapidly changed is any one of the following:
(A) a start-up or a stop of the compressor,
(B) an occurrence of surging,
(C) a change in load,
(D) a change in cooling water temperature,
(E) a rapid change in rotation frequency, and
(F) an abnormal stop of a chiller.

12. A turbo chiller comprising:
a turbo compressor;
a condenser;
a throttle device; and
an evaporator,
wherein the turbo compressor in the turbo chiller is the turbo compressor according to claim 1 .

13. A turbo chiller comprising:
a turbo compressor;
a condenser;
a throttle device; and
an evaporator,
wherein the turbo compressor in the turbo chiller is the turbo compressor according to claim 2 .

14. A turbo chiller comprising:
a turbo compressor;
a condenser;
a throttle device; and
an evaporator,
wherein the turbo compressor in the turbo chiller is the turbo compressor according to claim 4 .

Assignees

• Mitsubishi Heavy Ind Thermal Systems Ltd

Inventors

• Hasegawa Yasushi
• Ueda Kenji
• Yokoyama Akimasa

Classifications

• F04D29/058 Primary

  magnetic; electromagnetic · CPC title

• F04D29/048

  magnetic; electromagnetic · CPC title

• F25B1/053

  of turbine type · CPC title

• F04D29/051

  Axial thrust balancing · CPC title

• F04D17/12

  Multi-stage pumps · CPC title