CN114641618B

CN114641618B - Integrated motor-compressor unit with a cooling circuit configured to reduce cooling fluid pressure and a pressure relief system

Info

Publication number: CN114641618B
Application number: CN201980100679.2A
Authority: CN
Inventors: B·笛福; S·吉尔曼; T·阿尔班; G·纳沃罗基
Original assignee: Thermodyn Sas
Current assignee: Thermodyn Sas
Priority date: 2019-09-23
Filing date: 2019-09-23
Publication date: 2024-02-23
Anticipated expiration: 2039-09-23
Also published as: CA3151299A1; JP7391196B2; US20220372994A1; BR112022005399A2; CN114641618A; EP4034768A1; WO2021058995A1; JP2022548391A

Abstract

The invention provides an integrated motor-compressor unit (10) comprising a motor (12) and a compressor (14) coupled to the motor (12) via a rotatable shaft (16) and mounted in a single common housing (18) configured to circulate a cooling fluid in a cooling circuit (27), wherein the integrated motor-compressor unit (10) comprises a pressure relief system (30) configured to relieve pressure of the motor (12).

Description

Integrated motor-compressor unit with a cooling circuit configured to reduce cooling fluid pressure and a pressure relief system

Background

The field of the invention relates to an integrated motor-compressor unit for processing a working fluid, and more particularly to an integrated motor-compressor with a cooling system.

Generally, a motor-compressor unit includes a centrifugal compressor and a motor integrated in a common housing.

Centrifugal compressors having multiple compression stages typically include multiple impellers supported by a drive shaft coupled to a rotor driven by a motor or turbine to produce a compressed process gas stream.

The shaft used to directly drive such centrifugal compressors needs to rotate at a relatively high speed to generate heat. In addition, operating the motor-compressor at high speed increases windage friction losses generated by components operating in pressurized gas.

If such heat is inappropriately dissipated, it may negatively impact the performance of the motor and damage the electrical insulation of the stator. The increased temperature may also adversely affect the rotor bearing system of both the compressor and the motor, resulting in bearing damage and/or failure.

In order to regulate heat and cool such integrated motor-compressor units, it is known to use a cooling circuit, which may be an open loop cooling circuit or a quasi-closed loop cooling circuit, wherein gas is drawn from the process stream at some point in the compression process. The gas is then circulated through the motor and bearings to absorb heat.

For example, only a small amount of process gas is fed from the process stream into the cooling loop. The cooling gas may be driven by a pressure differential between the cooling gas source and the location to which the gas is allowed to flow.

Alternatively, it is known to use a blower located before the cooling circuit to circulate the cooling gas in the cooling circuit and thereby improve the fan compression efficiency. However, this solution increases the windage losses significantly, more when the machine is operating at high pressure.

Reference may be made to US 9,200,643-B2, which describes a system for cooling a motor-compressor with a closed-loop cooling circuit. However, the motor is sealed from the gas being processed by the compressor by a dry gas seal or carbon ring to avoid contamination, thereby increasing maintenance on the seal.

Summary of The Invention

One benefit provided by the embodiments of the integrated motor-compressor unit described herein is reduced windage losses.

In practice, the high speed motor, coupling head and bearings are immersed in the process gas, and the windbreak losses can be high, especially for compressors with high suction pressure.

Accordingly, a pressure relief system for an integrated motor-compressor unit is presented having a motor and a compressor coupled to the motor. The pressure relief system is configured to relieve pressure of the motor.

There is further proposed an integrated motor-compressor unit configured to process a working fluid (such as gas, for example), and comprising a motor and a compressor coupled to said motor via a rotatable shaft and mounted in a single common housing, a cooling fluid circulating through the entire housing in a cooling circuit.

Disclosure of Invention

The integrated motor-compressor unit includes a pressure relief system configured to relieve pressure of the motor.

Thus, the depressurization system is configured to reduce the pressure of the cooling fluid circulating in the cooling circuit.

Such reduced pressure systems create a significant pressure drop of at least 10 bar. Therefore, the efficiency of the motor is significantly increased.

According to one embodiment, the depressurization system includes an expansion device (e.g., before the cooling circuit) and an auxiliary compressor (e.g., after the cooling circuit) configured to recover suction pressure.

For example, the expansion device may be a cooling expansion valve configured to receive working fluid via a main compressor suction inlet of the compressor and to transfer the expanded cooling fluid to the cooling circuit, and the auxiliary compressor may be configured to receive the cooling fluid and compress the cooling fluid after the motor and/or bearings have been significantly cooled.

According to another embodiment, the expansion device is an expansion wheel.

The expansion wheel may be mounted in a variety of suitable positions as further described and claimed herein.

In an embodiment operating the integrated motor-compressor unit, the motor rotates the shaft and thereby drives the compressor in rotation. The process gas to be compressed is introduced via a main compressor suction inlet provided in the housing. The compressor then compresses the process gas through successive impeller stages, thereby producing a compressed process gas. The compressed process gas then exits the compressor via a process discharge outlet disposed in the housing.

Drawings

Other objects, features and advantages of embodiments of the present invention will become apparent upon reading the following description, given by way of non-limiting example only, and with reference to the accompanying drawings in which:

fig. 1 very schematically shows an integrated motor-compressor unit according to a first embodiment of the invention;

fig. 2 very schematically shows an integrated motor-compressor unit according to a second embodiment of the invention;

fig. 3 very schematically shows an integrated motor-compressor unit according to a third embodiment of the invention; and is also provided with

Fig. 4 very schematically shows an integrated motor-compressor unit according to a fourth embodiment of the invention.

Detailed Description

The figures very schematically illustrate an integrated motor-compressor unit 10 configured to process a working fluid, such as a gas. The integrated motor-compressor unit 10 comprises a motor 12 and a compressor 14 coupled to said motor 12 via a rotatable shaft 16 and mounted in a single common housing 18 configured to circulate a cooling fluid in a cooling circuit 27.

The integrated motor-compressor unit 10 further includes a pressure relief system 30 configured to relieve the pressure of the motor 12 and thereby reduce the pressure of the cooling circulated in the cooling circuit.

Such a reduced pressure system 30 creates a significant pressure drop of at least 10 bar. Thus, the efficiency of the motor 12 increases significantly due to such pressure drops.

The shaft extends substantially the entire length of the housing 18 and includes a motor section 17 coupled to the motor 12 and a driven section 19 coupled to the compressor 14. The motor section 17 and the driven section 19 of the rotatable shaft 16 are connected via a coupling 20 (e.g. such as a flexible or rigid coupling).

As shown, the motor section 17 and the driven section 19 are supported at each end by one or more radial bearings 22, respectively. By way of non-limiting example, four sets of radial bearings 22 are shown. The bearing 22 may be directly or indirectly supported by the housing 18.

The electric machine 12 may be an electric motor, such as a permanent magnet motor, having permanent magnets mounted on a rotor (not shown in the figures) and a stator (not shown in the figures). Alternatively, other types of motors may be used, such as, for example, … … such as synchronous motors, induction motors, brushed dc motors, etc

The compressor 14 may be a multi-stage centrifugal compressor having one or more compressor stage impellers (not shown).

To cool or otherwise regulate the temperature of the motor 12 and bearings 22, a cooling gas is circulated throughout the housing 18 in a cooling circuit 27 having a cooling conductance 28 and a heat conductance 29.

The depressurization system 30 includes an expansion device 32 before the cooling circuit 27 and an auxiliary compressor 34 after the cooling circuit 27 configured to recover suction pressure.

A first embodiment of a pressure relief system 30 is shown in fig. 1. In this embodiment, the expansion device 32 is a cooled expansion valve that receives the process gas via the primary compressor suction inlet 24 and transfers the expanded cooled process gas to the cooling circuit 27. The auxiliary compressor 34 receives the cooling fluid after having cooled the bearing 22 and the motor 12 and compresses it before delivery to the main compressor suction inlet 24.

The embodiment of fig. 2, in which like elements have like numerals, differs from the embodiment of fig. 1 in the construction of the expansion device 32. In this embodiment, the expansion device 32 is an expansion wheel mounted on the end of the motor shaft. Alternatively, the expansion wheel may be mounted on the compressor shaft end, between bearings or on a dedicated turbo-expander. In this embodiment, the auxiliary compressor 34 is mounted on the compressor shaft end. Alternatively, the auxiliary compressor 34 may be mounted on the motor shaft end, between bearings, on a dedicated turbo-expander, or on a dedicated compressor.

The embodiment of fig. 3, in which like elements have like numerals, differs from the embodiment of fig. 1 in the construction of the expansion device 32. In this embodiment, expansion is created by leakage from the active compressor 14 compressed by the auxiliary compressor 34. In other words, the calibration gas leak on the compressor end 14 is used to generate the cooling flow. In this embodiment, and as a non-limiting example, the auxiliary compressor 34 is mounted on the motor shaft end.

The embodiment of fig. 4 (wherein like elements have like numerals) differs from the embodiment of fig. 1 in the structure of compression system 30. In this embodiment, the depressurization system 30 includes a blower device 36 mounted upstream of the compressor 14 and configured to circulate a cooling fluid in the closed loop cooling circuit 27. The depressurization system 30 further includes a depressurization auxiliary compressor 34 configured to compensate for primary compressor gas leakage. The depressurization system 30 also includes a cooler 38 that is installed on the cooling circuit 27 after the blower device 36.

The pressure-reducing auxiliary compressor 34 may be a low-pressure compressor or a dedicated device.

In an embodiment that operates the integrated motor-compressor unit 10, the motor 12 rotates the shaft 16 and thereby drives the compressor 14 in rotation. The process gas to be compressed is introduced via a main compressor suction inlet 24 provided in the housing 18. The compressor 14 then compresses the process gas through successive impeller stages, thereby producing compressed process gas. The compressed process gas 14 then exits the compressor via a process discharge outlet 26 provided in the housing 18.

Thanks to the decompression system of the invention, windage losses are reduced in an integrated motor-compressor unit, in particular in compressors with high suction pressure.

Claims

1. A decompression system (30) for an integrated motor-compressor unit (10) having a motor (12) and a compressor (14) coupled to the motor (12), wherein the decompression system (30) is configured to decompress the motor (12), the system comprising an expansion device (32) and an auxiliary compressor (34) configured to recover suction pressure, the system being characterized in that the expansion device (32) is a cooling expansion valve configured to receive working fluid via a main compressor suction inlet (24) of the compressor (14) and to transmit expanded cooling fluid to a cooling circuit (27) of the integrated motor-compressor unit (10), and wherein the auxiliary compressor (34) is configured to receive the cooling fluid and compress the cooling fluid after the motor (12) has been significantly cooled.

2. The pressure relief system (30) of claim 1, wherein the expansion device (32) is an expansion wheel.

3. The reduced pressure system (30) of claim 2, wherein the reduced pressure system (30) further comprises a cooler.

4. The reduced pressure system (30) of claim 1, wherein the reduced pressure system (30) further comprises a blower device (36).

5. The depressurization system (30) as set forth in claim 4 wherein said depressurization system (30) further comprises a depressurization auxiliary compressor (34) configured to compensate for compressor gas leakage.

6. An integrated motor-compressor unit (10) having a motor (12) and a compressor (14) coupled to the motor (12) via a rotatable shaft (16) and mounted in a single common housing (18) configured to circulate a cooling circuit (27), wherein the integrated motor-compressor unit (10) comprises: a decompression system (30) configured to decompress a pressure of the electric machine (12), the system comprising an expansion device (32) and an auxiliary compressor (34) configured to recover suction pressure, the system characterized in that the expansion device (32) is a cooling expansion valve configured to receive working fluid via a main compressor suction inlet (24) of the compressor (14) and to transfer expanded cooling fluid to a cooling circuit (27) of the integrated motor-compressor unit (10), and wherein the auxiliary compressor (34) is configured to receive the cooling fluid and compress the cooling fluid after the electric machine (12) has been significantly cooled.

7. The integrated motor-compressor unit (10) of claim 6, wherein the expansion device (32) is an expansion wheel.

8. The integrated motor-compressor unit (10) of claim 7, wherein the expansion wheel (32) is mounted on a motor shaft end and the auxiliary compressor (34) is mounted on a compressor shaft end.

9. The integrated motor-compressor unit (10) of claim 6, wherein expansion of the working fluid is formed by an active compressor (14) leak compressed by the auxiliary compressor (34).

10. The integrated motor-compressor unit (10) of claim 9, wherein the pressure relief system (30) further comprises a cooler mounted on the cooling circuit (27).

11. The integrated motor-compressor unit (10) of claim 6, wherein the depressurization system (30) includes a blower device (36) mounted upstream (14) of the compressor and configured to circulate the cooling fluid in a closed loop cooling circuit (27).

12. The integrated motor-compressor unit (10) of claim 11, wherein the depressurization system (30) further comprises a depressurization auxiliary compressor (34) configured to compensate for compressor gas leakage.

13. The integrated motor-compressor unit (10) according to claim 11 or 12, wherein the depressurization system (30) further comprises a cooler (38) mounted on the cooling circuit (27) after or before the blower device (36).

14. The integrated motor-compressor unit (10) according to any one of claims 6 to 13, wherein the rotatable shaft (16) is supported at each end by at least one bearing (22).