WO2019130935A1

WO2019130935A1 - Motor cooling system

Info

Publication number: WO2019130935A1
Application number: PCT/JP2018/043382
Authority: WO
Inventors: 克年小林
Original assignee: 株式会社日立製作所
Priority date: 2017-12-25
Filing date: 2018-11-26
Publication date: 2019-07-04
Also published as: JP2019115177A

Abstract

This motor cooling system (S) comprises a compressor (C1) that raises the pressure of and transports a process gas (g) and comprises: a motor (m) that has a rotor (2) and a stator (3); and an impeller (1) that is driven by the motor (m) and raises the pressure of the process gas (g). The stator (3) is arranged inside a cylindrical motor frame (5). One or more first ventilation holes (9) are provided in the motor frame (5) upstream of the motor (m).

Description

Motor cooling system

The present invention relates to a motor cooling system.

In the upstream plant that produces natural gas, wells of several thousand meters in length are excavated to extract natural gas from natural gas fields several thousand meters underground.

At the beginning of operation of the production plant, natural gas is ejected from the ground through the wells by the self-injection pressure of high-pressure natural gas fields. Therefore, at the beginning of drilling a well, natural gas spouted from the well at high pressure is collected. However, when the production proceeds, the self-injection pressure is attenuated, which causes a problem that the production of natural gas is reduced.

Therefore, there is a method of installing a compressor near the gas field in the well and pumping the natural gas to the ground as time passes from the well drilling, in order to solve the natural gas production attenuation problem. By installing the compressor at a location closer to the natural gas field, the production efficiency is improved by pressurizing the natural gas with the compressor.

JP, 2017-85740, A

By the way, the well temperature which is several thousand meters underground is high in ambient temperature. Therefore, the motor for driving the compressor for mining is at a high temperature because it is installed inside a well near a natural gas field where the ambient temperature is high and narrow and airy.
Here, in order to reduce the cost required for well drilling, the inner diameter of the well is small. Therefore, there is not enough space for installing cooling accessories other than the compressor inside the well.

Thus, it is necessary to cool the motor using natural gas (process gas) of a natural gas field because sufficient space for installing the auxiliary equipment can not be secured.
Therefore, Patent Document 1 describes a system for blowing gas into the motor to cool the motor.

However, Patent Document 1 does not describe a structure that facilitates the gas being taken into the motor in order to take the gas into the motor.
The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a motor cooling system capable of effectively cooling a compressor for extracting a process gas.

In order to solve the above problems, a motor cooling system according to the present invention includes a motor having a rotor and a stator, and an impeller driven by the motor to boost the process gas, and boosts the process gas and transports the process gas. A compressor is provided, and the stator includes a cylindrical motor frame in which the stator is installed. The motor frame is provided with a plurality of or single first vent holes on the upstream side of the motor.

According to the present invention, it is possible to provide a motor cooling system capable of effectively cooling a compressor for extracting process gas.

The cross-sectional schematic diagram which shows the upstream plant which produces natural gas. BRIEF DESCRIPTION OF THE DRAWINGS The cross-sectional schematic diagram which shows the whole schematic structure of the gas pumping system which installed the compressor of embodiment which concerns on this invention. The expanded sectional view which shows the outline of the gas pumping system of a comparative example. The expanded sectional view which expanded the periphery of a motor. The perspective view of the motor frame in which the ventilation hole was installed. The expanded sectional view which expanded the small clearance periphery vicinity between the motor frame and casing of the compressor concerning Example 4 of this invention.

In an upstream plant that produces natural gas, in a compressor that does not use an external accessory for motor cooling, it is necessary to directly cool the heat generating part of the motor using process gas before purifying the natural gas.

Therefore, in the present invention, in a compressor which is a kind of rotary machine for conveying a pressurized process gas, a system for directly cooling a high temperature part of a motor of a drive source using the process gas is adopted. In order to improve the cooling performance of the motor, it is necessary to introduce as much process gas as possible into the high temperature part of the motor.

Therefore, in the present invention, part of the process gas is taken into the motor to directly cool the high temperature part of the motor.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an upstream plant that produces natural gas.
In the natural gas production plant, a well 21 having a depth of several thousand m or more, for example, 1000 m or more is excavated from the ground G so as to lead to the natural gas field 22. The well 21 has a depth on the order of several kilometers, and the depth reaches, for example, 1 to 2 km.

At the beginning of the operation of the natural gas production plant, the process gas g of the natural gas is ejected from the ground toward the ground through the well 21 by the self-injection pressure of the high pressure natural gas field 22 (arrow α1 in FIG. 1). Therefore, at the beginning of the drilling of the well 21, the process gas g to be purified into natural gas spouted at high pressure of the natural gas field 22 through the well 21 is sampled.
After that, when natural gas production progresses, the self-injection pressure decreases, so the production of process gas g decreases.

FIG. 2 is a schematic cross-sectional view showing an overall schematic configuration of a gas pumping system S provided with a compressor C according to an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view schematically showing a gas pumping system of a comparative example to which the present invention is applied.

The expanded sectional view which expanded the periphery of the motor m of gas pumping system S of embodiment which concerns on FIG. 4 at this invention is shown.
Here, since the gas pump system S10 of the comparative example of FIG. 3 and the gas pump system S according to the embodiment of the present invention shown in FIG. 4 to FIG. Indicated and not repeated.

Therefore, in the comparative example, as shown in FIG. 3, the compressor C of the gas pumping system S10 is installed inside the well 21 near the natural gas field 22 (see FIG. 2).
The casing 6 is provided inside the well 21 (see FIG. 2), and the compressor C of the gas pumping system S10 is provided inside the casing 6. The ambient temperature of the compressor C in this case reaches a high temperature state of 100 to 200.degree.

The gas pumping system S10 of the comparative example includes the impeller 1 of the compressor C, the rotor 2 fixed to the shaft 2j, the motor stator 3, and the casing 6 in which the suction passage 4 is formed.

The rotor 2 and the motor stator 3 constitute a motor m. Although the rotor 2 has a magnet, it is omitted in FIG. 3 and FIG. 4 and FIG.
The impeller 1 is fixed to one side of a shaft 2 j to which the rotor 2 is fixed. The motor stator 3 is fixed to the inside of a circular tubular or cylindrical motor frame 5.

Thus, the rotor 2 and the motor stator 3 are covered by the motor frame 5. A bearing 2 j 1 is provided between one side of the shaft 2 j to which the rotor 2 near the impeller 1 is fixed and the motor frame 5. A bearing 2 j 2 is provided between the other side of the shaft 2 j and the motor frame 5.

By driving the motor m, the rotor 2 is rotated, and the impeller 1 fixed to the shaft 2 j of the rotor 2 is rotationally driven.
The compressor C sucks the process gas g from the upstream suction flow path 4 close to the natural gas field 22 (see FIG. 2) by the rotation of the impeller 1. Then, the impeller 1 of the compressor C pressurizes the sucked process gas g by its rotation, and spouts and pumps it downstream of the well 21 (see FIG. 3).

At this time, as shown in FIG. 3, the process gas g flows into the interior of the casing 6 from the suction flow path 4, flows through the gap 12 between the motor frame 5 and the casing 6, and flows into the impeller 1. The pressure is increased by the rotation of the impeller 1.
In this case, since the motor m is driven by the magnetic force, the energy of the motor m causes the periphery between the rotor 2 and the motor stator 3 in the motor m to have a high temperature. For example, the periphery between the rotor 2 and the motor stator 3 has a high temperature of about 400 to 500.degree.

Therefore, in order to cool the high temperature part of the motor m using the process gas g, as shown in FIG. 4 of the embodiment, a part of the process gas g1 of the process gas g is used as a gap between the rotor 2 and the motor stator 3 Flow through the air gap 7.
The following embodiments shown in FIGS. 4 to 6 disclose a configuration in which the process gas g1 flows in the air gap 7 which is a gap between the rotor 2 and the motor stator 3.

Example 1
FIG. 4 shows the structure of the compressor C1 of Example 1 according to the embodiment of the present invention. The perspective view of the motor frame 5 in which the vent holes 9 and 10 of the gas pumping system S of embodiment were installed in FIG. 5 is shown.
A part of the process gas g1 of the process gas g flowing in from the suction flow path 4 is flowed into the air gap 7 between the rotor 2 and the motor stator 3 in the motor m.

Therefore, in the first embodiment, in order to take in part of the process gas g1 of the process gas g into the motor m, a plurality of ventilating holes 9 are circumferentially provided on the upstream side of the circular or tubular motor frame 5. It has been installed.

As shown in FIG. 5, a plurality of ventilation holes 9 are provided on one side of the motor frame 5. FIG. 5 shows the case where four rectangular ventilation holes 9 are formed on one side of the motor frame 5. However, the shape and / or the number of the vent holes 9 are not limited as long as the process gas g1 can flow through the air gap 7 in the gap between the rotor 2 and the motor stator 3.

According to this structure, as shown in FIG. 4, the process gas g is branched from the main process gas g0 and a part of the process gas g1 passing through the vent holes 9 on the upstream side. Then, a part of the branched process gas g1 can be flowed into the air gap 7 in the motor m. Thereby, the periphery between the rotor 2 and the motor stator 3 can be cooled. Therefore, the life of the motor m can be extended, and the reliability of the compressor C1 can be improved.

In addition, although the case where the ventilation hole 9 was installed in multiple numbers was demonstrated in Example 1, you may install the ventilation hole 9 singularly. However, a plurality of vent holes 9 is more desirable than in the case of a single vent hole, since the process gas g1 can be taken in different directions and / or in large amounts inside the motor m.

Example 2
The gap 12 between the motor frame 5 and the casing 6 shown in FIG. 3 is, for example, about 5 to 10 mm.
Here, as shown in FIG. 3, since the air gap 7 is a very narrow gap, for example, about 3 mm, even if the vent hole 9 is installed in the motor frame 5, a portion of the process gas g1 of the process gas g is a motor Even inside the frame 5, the air usually bounces off the air gap 7 and flows into the gap 12 of about 5 to 10 mm between the motor frame 5 and the casing 6. Therefore, even if there are vent holes 9, the process gas g does not branch at the vent holes 9, and part of the process gas g1 does not flow in the air gap 7.

Therefore, in Example 2, as shown in FIG. 4, since the process gas g is taken into the motor m, the gap 12 between the motor frame 5 and the casing 6 through which the main process gas g0 flows is shown in FIG. Compared with this, a narrow gap 12i is formed, and a pressure loss becomes high. FIG. 4 shows the structure of a compressor C2 according to a second embodiment of the present invention.

In the second embodiment, as shown in FIG. 4, the casing 6 is formed in a step shape having a convex portion 6t projecting inward. The convex portion 6 t is formed in an annular shape projecting inward from the cylindrical casing 6.

Thereby, a narrow gap channel 12i is formed between the annular convex 6t of the motor frame 5 and the casing 6. Since the gap channel 12i is narrow and the pressure loss is high, the main flow process gas g0 is less likely to flow through the gap channel 12i between the motor frame 5 and the casing 6.

Therefore, the process gas g1 flows into the air gap 7 inside the motor m.
In the second embodiment, the casing 6 is illustrated to have a step shape with the projecting portion 6t projecting inward. However, without providing the projecting portion 6t projecting inward to the casing 6, the motor frame 5 is not provided. The projection may be provided with an outwardly projecting protrusion.

Alternatively, the casing 6 may be provided with a projection projecting inward, and the motor frame 5 may be provided with a projection projecting outward. If the gap channel 12i is narrowed, the configuration of the convex portion is not limited and can be selected arbitrarily.

Example 3
As shown in FIG. 3, a bearing 2j1 is provided between the other side of the motor frame 5 and the side of the impeller 1 of the shaft 2j to which the rotor 2 is fixed. Therefore, in the conventional structure, part of the process gas g1 passing through the air gap 7 shown in FIG. 4 can not flow. Therefore, part of the process gas g1 flowing into the air gap 7 needs to be merged with the main process gas g0 again.

Therefore, in the third embodiment shown in FIG. 4, the vent holes on the downstream side of the motor frame 5 in order to rejoin part of the process gas g1 flowing through the air gap 7 with the main process gas g0 branched from the process gas g. Install 10 That is, as shown in FIG. 5, a plurality of ventilating holes 10 are installed in the circumferential direction on the other side of the circular tubular motor frame 5. In FIG. 5, the case where four rectangular ventilation holes 10 are installed in the circumferential direction on the other side of the circular tubular motor frame 5 is shown. The shape and / or the number of the vent holes 10 are not limited as long as the process gas g1 discharged from the air gap 7 between the rotor 2 and the motor stator 3 can be discharged to the outside of the motor frame 5.

As a result, part of the process gas g1 having flowed into the air gap 7 joins the mainstream process gas g0 through the vent holes 10 (see FIG. 5) even when the bearing 2j1 is on the downstream side.

According to this configuration, the process gas g is branched into the main flow process gas g0 and a part of the process gas g1 passing through the vent holes 9 through the vent holes 9. Then, a part of the branched process gas g1 flows into the air gap 7 between the rotor 2 and the motor stator 3. Thereafter, the process gas g1 can be smoothly joined to the mainstream process gas g0 through the vent holes 10 on the downstream side of the motor frame 5.

Therefore, the rotor 2 and the motor stator 3 around the air gap 7 can be cooled smoothly by the process gas g1.
In addition, although the case where multiple ventilation holes 10 were installed was demonstrated in Example 3, you may install the ventilation hole 10 single. However, it is more desirable that the process gas g1 inside the motor m can be discharged to the outside in different directions and / or in a large amount than in the case where the vent hole 10 is a single one.

Example 4
The structure of the compressor C4 concerning Example 4 of this invention is shown in FIG. 6, and the expanded sectional view which expanded the narrow clearance gap 12a periphery between the motor frame 5 and the casing 6 is shown.
In the fourth embodiment, in order to increase the pressure loss of the main process gas g0 flowing through the gap 12 between the motor frame 5 and the casing 6, the flow passage structure of the gap 12a is formed into a labyrinth shape 6r.

Specifically, in the fourth embodiment, the motor frame 5 is provided with a plurality of annular projections 13 projecting outward. As a result, the flow path between the motor frame 5 and the casing 6 becomes a narrow gap 12 a and becomes the labyrinth flow path 14.
The labyrinth flow path 14 has a configuration in which the flow path is folded, and the flow is blocked by the resistance of the projection 13. That is, the resistance of the flow from the upstream side to the downstream side of the main flow process gas g0 is increased by the throttling effect at the tip of the projection 13 and the vortex generated between the projections 13.

As a result, the main process gas g0 does not easily flow in the gap 12a between the motor frame 5 and the casing 6, and more process gas g branches into the air passage 9 and flows into the motor frame 5. In addition, since the surface area of the motor frame 5 is increased by the projections 13, the cooling efficiency of the motor m can also be increased.

In addition, although the protrusion 13 shown in FIG. 6 is made into the cross-sectional rectangular shape, if the shape of the protrusion 13 is a labyrinth flow path 14 which makes a flow path hard to flow by the shape of several annular rings, the cross-sectional shape is triangular The shape may be any shape other than the cross-sectional rectangular shape.

According to the configuration of the fourth embodiment, since the gap 12a between the motor frame 5 and the casing 6 is the labyrinth passage 14, the process gas g can be guided to the air passage 9 and branched to the air passage 9 for the process gas g. The amount of process gas g1 can be increased. Therefore, more process gas g1 can flow in the air gap 7 between the rotor 2 and the motor stator 3. Thereby, the cooling effect around the air gap 7 by the process gas g1 can be enhanced. Further, the surface area of the motor frame 5 including the projections 13 is increased, and the cooling efficiency can be improved by the labyrinth flow path 14.

In the fourth embodiment, the motor frame 5 is provided with the annular projection 13 projecting outward to form the labyrinth shape 6r, and the labyrinth flow path 14 is configured. A projecting labyrinth protrusion may be provided to form a labyrinth shape, and the labyrinth flow path 14 may be configured.

The same labyrinth shape may be formed on both the motor frame 5 and the casing 6 to provide a labyrinth flow path.

As described above, according to the configuration of the present embodiment, for example, the main process gas g0 of about 140 ° C. is used to cool the periphery between the high-temperature rotor 2 and the motor stator 3 of about 400 to 500 ° C. It can be cooled to about 150 ° C.

In addition, since the motor m is cooled using the process gas g1 before the pressure rise and temperature rise by the impeller 1 of the compressors C1 to C4, an external accessory necessary for cooling the motor m is not necessary. Therefore, the whole structure of the apparatus for gas pumping system S shown in FIG. 4 can be reduced.
Therefore, for example, the compressors C1, C2, and C3 can be installed in the well 21 that produces natural gas.

«Other Embodiments»
1. The above embodiments are described in detail for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the configurations described. Moreover, it is possible to add, delete, and replace another configuration with respect to a part of the configuration of the embodiment.

2. Further, the present invention can be variously modified and embodied within the scope described in the claims, and is not limited to the described embodiments and examples.

1 impeller 2 rotor 3 motor stator (stator)
5 Motor frame 6 Casing 6t Convex part (step, part of downstream part)
6r Labyrinth shape g Process gas g0 Main flow process gas g1 Part of process gas 9 Ventilation path (first vent)
10 air passage (second air vent)
12i narrow gap 12a narrow gap 12 gap 13 protrusion 14 labyrinth flow path 21 well C1, C2, C3, C4 compressor m motor S gas pumping system (motor cooling system)

Claims

A motor having a rotor fixed to the shaft and a stator, and an impeller driven by the motor to boost the process gas, and having a compressor for boosting and conveying the process gas;
It has a cylindrical motor frame in which the stator is installed,
The motor frame is
The motor cooling system, wherein a plurality of or a plurality of first vent holes are installed upstream of the motor.
In the motor cooling system according to claim 1,
It comprises a cylindrical casing provided along a well for extracting process gas and in which the motor frame is accommodated.
The gap between the motor frame and the casing is
A motor cooling system characterized in that a part of a portion downstream of the first ventilation hole is formed narrower than other portions.
In the motor cooling system according to claim 1,
It comprises a cylindrical casing provided along a well for extracting process gas and in which the motor frame is accommodated.
At least one of the casing or the motor frame is
A motor cooling system, comprising: a step for narrowing a part of a portion downstream of the first vent hole in a gap between the motor frame and the casing.
In the motor cooling system according to claim 1,
The motor frame is
The motor cooling system, wherein a plurality of or a plurality of second vent holes are installed downstream of the motor.
In the motor cooling system according to claim 1,
It comprises a cylindrical casing provided along a well for extracting process gas and in which the motor frame is accommodated.
At least one of the casing or the motor frame is
A motor cooling system characterized by having a labyrinth shape in a flow passage downstream of the first vent hole in the gap between the motor frame and the casing.