JP7391196B2 - an integrated motor-compressor unit having a cooling circuit and a pressure reduction system configured to reduce the pressure of the cooling fluid; - Google Patents

Description

The field of the invention relates to integrated motor-compressor units for processing working fluids, and more particularly to integrated motor-compressors with cooling systems.

Typically, a motor-compressor unit includes a centrifugal compressor and a motor integrated into a common housing.

Centrifugal compressors with multiple compression stages generally employ multiple impellers supported by a drive shaft coupled to a rotor driven by a motor or turbine to produce a flow of compressed process gas. Be prepared.

The shafts used to directly drive such centrifugal compressors must rotate at relatively high speeds, thereby generating heat. Additionally, operating the motor compressor at high speeds increases wind friction losses due to components operating on pressurized gas.

If this heat is not properly dissipated, it can adversely affect the performance of the motor and damage the electrical insulation of the stator. Increased temperatures can also adversely affect the rotor bearing systems of both the compressor and motor, resulting in damage and/or failure.

To regulate heat and cool such integrated motor-compressor units, use a cooling circuit, which may be an open-loop cooling circuit or a semi-closed-loop cooling circuit, in which gas is withdrawn from the process stream at some point in the compression process. It is known to do. Process gases are then circulated through the motor and bearings to absorb heat.

For example, only a small amount of process gas is supplied from the process stream to the cooling circuit. The cooling gas may be driven by a pressure difference between the source of the cooling gas and the point through which the gas can flow.

Alternatively, it is known to use a blower placed before the cooling loop to circulate the cooling gas within the cooling circuit and thus improve the fan compression efficiency. However, such a solution significantly increases windage when the machine operates at high pressure.

Reference may be made to US Pat. No. 9,200,643 (B2), which describes a system for cooling motor compression in a closed loop cooling circuit. However, the motor is sealed from the compressor process gas by a dry gas seal or carbon ring to avoid contamination, which increases seal maintenance.
Brief description of the invention

One advantage provided by the integrated motor compressor unit embodiments described herein is reduced windage.

In fact, windage losses can be high when high speed motors, couplings, and bearings are immersed in process gas, especially in compressors with high suction pressures.

Accordingly, an integrated motor-compressor unit pressure reduction system having a motor and a compressor coupled to the motor has been proposed. The pressure reduction system is configured to reduce the pressure of the motor.

Furthermore, an integrated unit configured to process a working fluid, e.g. a gas, comprising a motor and a compressor coupled to the motor via a rotatable shaft and mounted in a single common housing. A motor-compressor unit is proposed in which cooling fluid is circulated throughout the housing in a cooling circuit.

The integrated motor compressor unit includes a pressure reduction system configured to reduce the pressure of the motor.

Accordingly, the pressure reduction system is configured to reduce the pressure of the cooling fluid circulating within the cooling circuit.

Such reduced pressure systems generate significant pressure drops of at least 10 bar. Therefore, the efficiency of the motor increases significantly.

According to one embodiment, the pressure reduction system comprises an expansion device, e.g. before the cooling circuit, and an auxiliary compressor, e.g. after the cooling circuit, configured to restore suction pressure.

The expansion device may be, for example, a refrigeration expansion valve configured to receive the working fluid through the main compressor inlet of the compressor and send the expanded refrigeration fluid to the refrigeration circuit, and the auxiliary compressor It may be configured to receive cooling fluid and compress the cooling fluid, particularly after cooling the motor and/or bearings.

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

The inflation wheel may be mounted at various suitable locations as further described and claimed herein.

In one embodiment of operation of an integrated motor-compressor unit, the motor rotates a shaft, thereby driving the compressor. The process gas to be compressed is introduced through a main compressor suction inlet located within the housing. The compressor then compresses the process gas through successive stages of the impeller, thereby producing a compressed process gas. The compressed process gas then exits the compressor through a process outlet located within the housing.

Other objects, features and advantages of embodiments of the invention will become apparent from the following description, taken by way of non-limiting example only and with reference to the accompanying drawings, in which: FIG.
1 is a highly schematic representation of an integrated motor-compressor unit according to a first embodiment of the invention; FIG. FIG. 3 is a highly schematic representation of an integrated motor-compressor unit according to a second embodiment of the invention; FIG. 3 very schematically represents an integrated motor-compressor unit according to a third embodiment of the invention; FIG. 4 very schematically represents an integrated motor-compressor unit according to a fourth embodiment of the invention;

The figure shows very schematically an integrated motor-compressor unit 10 configured to process a working fluid, such as a gas. The integrated motor-compressor unit 10 is mounted to a motor 12 and a single common housing 18 coupled to the motor 12 via a rotatable shaft 16 and configured to circulate cooling fluid within a cooling circuit 27. and a compressor 14.

The integrated motor-compressor unit 10 further comprises a pressure reduction system 30 configured to reduce the pressure of the motor 12 and thus reduce the pressure of the refrigeration circulating within the refrigeration circuit.

Such a reduced pressure system 30 produces a significant pressure drop of at least 10 bar. Therefore, the efficiency of motor 12 is significantly increased by such a pressure drop.

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 driven section 19 of the rotatable shaft 16 are connected via a coupling 20, for example a flexible or rigid coupling.

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

Motor 12 may be an electric motor, such as a permanent magnet motor having permanent magnets mounted on a rotor (not shown) and a stator (not shown). Alternatively, other types of electric motors may be used, such as synchronous motors, induction motors, brushed DC motors, etc.

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

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

The reduced pressure system 30 comprises an expansion device 32 before the cooling circuit 27 and an auxiliary compressor 34 after the cooling circuit 27 configured to restore suction pressure.

A first embodiment of a reduced pressure system 30 is shown in FIG. In this embodiment, expansion device 32 is a refrigeration expansion valve that receives process gas via main compressor suction inlet 24 and delivers expanded, cooled process gas to refrigeration circuit 27 . Auxiliary compressor 34 receives the cooling fluid after cooling bearings 22 and motor 12 and compresses it before passing it to main compressor suction inlet 24.

The embodiment of FIG. 2 differs from the embodiment of FIG. 1 by the structure of the inflation device 32, although like elements have the same reference numerals. In this embodiment, inflation device 32 is an inflation wheel attached to the end of the motor shaft. Alternatively, the expansion wheel may be mounted at the end of the compressor shaft, between bearings, or on a dedicated turboexpander. In this embodiment, the auxiliary compressor 34 is attached to the end of the compressor shaft. Alternatively, the auxiliary compressor 34 may be mounted at the end of the motor shaft, between bearings, on a dedicated turboexpander, or on a dedicated compressor.

The embodiment of FIG. 3 differs from the embodiment of FIG. 1 by the structure of the inflation device 32, although like elements have the same reference numbers. In this embodiment, expansion is created by spontaneous compressor 14 leakage compressed by auxiliary compressor 34. In other words, a calibrated gas leak on the compressor end 14 is used to generate the cooling flow. In this embodiment, by way of non-limiting example, the auxiliary compressor 34 is attached to the end of the motor shaft.

The embodiment of FIG. 4 differs from the embodiment of FIG. 1 by the structure of the reduced pressure system 30, although like elements have the same reference numerals. In this embodiment, the reduced pressure system 30 includes a blowing device 36 mounted upstream of the compressor 14 and configured to circulate cooling fluid within the closed loop cooling circuit 27 . The vacuum system 30 further includes a vacuum auxiliary compressor 34 configured to compensate for main compressor gas leaks. The reduced pressure system 30 also includes a cooler 38 attached to the cooling circuit 27 after the blower device 36 .

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

In one embodiment of operation of integrated motor-compressor unit 10, motor 12 rotates shaft 16, thereby driving compressor 14. The process gas to be compressed is introduced via a main compressor inlet 24 provided in the housing 18 . Compressor 14 then compresses the process gas through successive stages of the impeller, thereby producing a compressed process gas. The compressed process gas then exits the compressor 14 via a process outlet 26 provided in the housing 18 .

The reduced pressure system of the present invention reduces windage losses within an integrated motor-compressor unit, especially in compressors with high suction pressures.

Claims (15)

A pressure reduction system (30) for an integrated motor-compressor unit (10) having a motor (12) and a compressor (14) coupled to the motor (12), the system comprising:
a cooling circuit (27) configured to circulate a working fluid for cooling the integrated motor compressor unit (10);
an expansion device (32) connected to the cooling circuit (27);
an auxiliary compressor (34) connected to the cooling circuit (27),
The expansion device (32) receives the working fluid via the main compressor suction inlet (24) of the compressor (14), expands and cools the working fluid, and sends it to the cooling circuit (27). A cooling expansion valve or expansion wheel configured to
The auxiliary compressor (34) compresses the working fluid from the cooling circuit (27) after cooling the motor (12) and generates a suction pressure for sending it to the main compressor suction inlet (24). A reduced pressure system (30), characterized in that it is configured to recover. The reduced pressure system (30) according to claim 1, further comprising a cooler connected to the cooling circuit (27). A reduced pressure system (30) according to any one of claims 1 or 2,
a motor (12);
a compressor (14) coupled to the motor (12) via a rotatable shaft (16);
a single common housing (18) housing the motor (12), the compressor (14) and the rotatable shaft (16);
has
a working fluid circulates within a cooling circuit (27) arranged through said single common housing (18);
Integrated motor compressor unit (10). The expansion device (32) is an expansion wheel, the expansion wheel (32) is attached to the motor shaft end of the rotatable shaft (16), and the auxiliary compressor (34) is connected to the rotatable shaft (16). An integrated motor-compressor unit (10) according to claim 3, wherein the integrated motor-compressor unit (10) is mounted on a compressor shaft end of a compressor. An integrated motor-compressor unit (10) according to claim 3 or 4, wherein each end of the rotatable shaft (16) is supported by at least one bearing (22). A system (30) for an integrated motor-compressor unit (10) having a motor (12) and a compressor (14) coupled to the motor (12), the system comprising:
a cooling circuit (27) configured to circulate a working fluid for cooling the integrated motor compressor unit (10);
an auxiliary compressor (34) connected to the cooling circuit (27),
the cooling circuit (27) is configured to receive expanded working fluid leaked from the compressor (14) to cool the integrated motor-compressor unit (10);
The auxiliary compressor (34) compresses the working fluid after cooling the motor (12) from the cooling circuit (27) and supplies it to the main compressor suction inlet (24) of the compressor (14 ). A system (30) configured to restore suction pressure for delivery. The system (30) of claim 6, further comprising a cooler attached to the cooling circuit (27). A system (30) according to any one of claims 6 or 7,
a motor (12);
a compressor (14) coupled to the motor (12) via a rotatable shaft (16);
a single common housing (18) housing the motor (12), the compressor (14) and the rotatable shaft (16);
has
An integrated motor-compressor unit (10) in which working fluid circulates in a cooling circuit (27) arranged through said single common housing (18). An integrated motor-compressor unit (10) according to claim 8, wherein an auxiliary compressor (34) is attached to the motor shaft end of the rotatable shaft (16). An integrated motor-compressor unit (10) according to claim 8 or 9, wherein each end of the rotatable shaft (16) is supported by at least one bearing (22). A system (30) for an integrated motor-compressor unit (10) having a motor (12) and a compressor (14) coupled to the motor (12), the system comprising:
a closed loop cooling circuit (27) configured to circulate a working fluid for cooling the integrated motor compressor unit (10);
a blowing device (36) connected to the closed loop cooling circuit (27) and mounted upstream of the compressor (14);
an auxiliary compressor (34) connected to the closed loop cooling circuit (27),
The auxiliary compressor (34) compresses the working fluid after cooling the motor (12) from the closed loop cooling circuit (27) to the main compressor suction inlet (24) of the compressor (14 ). A system (30) configured to restore suction pressure to the system. 12. The system (30) of claim 11, further comprising a cooler (38) attached to the closed loop cooling circuit (27) upstream or downstream of the blowing device (36). A system (30) according to claim 11 or 12;
a motor (12);
a compressor (14) coupled to the motor (12) via a rotatable shaft (16);
a single common housing (18) housing the motor (12), the compressor (14) and the rotatable shaft (16);
has
An integrated motor-compressor unit (10) in which working fluid circulates in a closed-loop cooling circuit (27) arranged through said single common housing (18). An integrated motor-compressor unit (10) according to claim 13, wherein a blowing device (36) is attached to the compressor shaft end of the rotatable shaft (16). An integrated motor-compressor unit (10) according to claim 13 or 14, wherein each end of the rotatable shaft (16) is supported by at least one bearing (22).