JP6903539B2 - Compressor - Google Patents

Description

The present invention relates to a compressor, and particularly to a compressor used in a gas field that produces natural gas.

In recent years, with the increase in demand for fossil fuels and the development of mining technology, development is shifting from conventional gas fields to unconventional gas fields. For example, compressors are used in harsh environments such as deep water and directly under gas fields. It has become necessary to install it.

In deep water, a method of installing a compressor on the seabed several hundred meters and pumping natural gas from the underground reservoir (subsea compressor) is being studied. In addition, directly under the gas field, a method has been proposed in which a compressor is put inside a gas well several thousand meters underground, and the gas is compressed at the bottom of the well and sent out to the ground. A compressor for that purpose (downhole compressor) Research and development is being carried out. Underground pressure is high at the beginning of development, but internal pressure decreases as gas is collected. Natural gas can be self-injected to the ground while the underground pressure in the gas field is high, but when the pressure drops below the limit, the gas cannot be self-injected. It was supposed to be. However, even after the underground pressure has dropped to a level insufficient for self-injection of gas, a considerable amount of natural gas still remains inside the gas field.

Therefore, it is considered possible to restore the production capacity of the gas field by applying a downhole compressor to boost the pressure directly under the gas field.

Since the subsea compressors and downhole compressors described above are installed at the bottom of the gas field or directly under the gas field, the operating environment is extremely harsh. The working fluid of compressors used in gas fields that generally produce natural gas is in an operating environment where not only natural gas but also water and liquids containing light liquid hydrocarbons called condensate are mixed. Is mentioned as a feature. Especially in the deep water and directly under the gas field mentioned above, the liquid fraction is very high. In such an environment, the liquid that has entered the compressor will have reduced efficiency due to collision with the impeller, reduced operating range due to blockage of the flow path due to fouling, generation of unstable fluid force, and erosion. It is thought that the wall thickness of the impeller will be reduced, and the compressor used in gas fields that produce natural gas has the technology to operate the compressor in an operating environment where liquids are mixed without degrading the performance. You will need it.

Therefore, the present invention relates to a method for controlling droplets mixed in an impeller in order to enable operation without reducing the efficiency and operating range of the impeller in a compressor operating in an operating environment in which liquids are mixed. Is. [Patent Document 1] is mentioned as a structure for removing droplets mixed in a conventional impeller.

Special table 2013-508618

An object of the present invention is compression that controls the operating state of an impeller when liquid is mixed in order to enable operation of a compressor operating in an operating environment where liquid is mixed without reducing the efficiency and operating range of the impeller. To provide an opportunity.

In order to achieve the above object, the present invention is attached to the rotating shaft, a motor for driving the rotating shaft, an inverter for supplying electric power to the motor, a calculation means for controlling the inverter, and the rotating shaft. In a compressor equipped with an impeller, at least the information of the axial power detected from the motor is used to control the rotational state of the impeller so as to suppress the adhesion of droplets to the blades of the impeller. It is characterized by doing.

Further, the present invention is characterized in that, when the formation of a liquid film is determined in the compressor, the calculation means controls the motor to temporarily increase the rotation speed via the inverter. Is to be.

Further, in order to achieve the above problems, the present invention uses a rotating shaft, a motor for driving the rotating shaft, an inverter for supplying electric power to the motor, a calculation means for controlling the inverter, and the rotating shaft. In a compressor equipped with an attached impeller, a sensor arranged upstream of the impeller is provided, and at least information on the flow velocity of the liquid from the sensor is used to attach droplets to the impeller blades. It is characterized in that the rotational state of the impeller is controlled so as to suppress it.

Further, the present invention uses the information on the droplet diameter together with the information on the flow velocity of at least the liquid from the sensor in the compressor so as to suppress the adhesion of the droplets to the blades of the impeller. It is characterized by controlling the rotational state of the impeller.

Further, the present invention is characterized in that the compressor is provided with a storage means, and the storage means is provided with a database for determining that the formation of a liquid film is determined.

It is possible to suppress a decrease in compressor efficiency and operating range when liquid is mixed. In addition, since no auxiliary equipment is required to remove the liquid, the equipment can be miniaturized.

It is sectional drawing of the compressor which shows the 1st Embodiment of this invention. It is sectional drawing of the compressor which shows the 2nd Embodiment of this invention. It is a figure which shows the relationship between the liquid fraction and the shaft power. It is sectional drawing of the conventional compressor. It is sectional drawing of the gas well in which the compressor which concerns on embodiment of this invention is installed.

Hereinafter, the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

FIG. 5 shows a cross-sectional view of a gas well in which the compressor according to the present embodiment is installed.

The gas well 100 is a drilling hole that reaches the gas layer 102 from the ground, and a steel pipe 104 for protecting the inner wall is installed inside the drilling hole. The compressor 1 is attached to the inner wall of the steel pipe 104 at the bottom of the gas well 100 by the support member 130. The compressor 1 is connected to a power supply device 134 installed on the ground via a power transmission cable 132 arranged in the steel pipe 104. In the gap between the compressor 1 and the inner wall of the steel pipe 104, the lower side (upstream side) and the upper side (downstream side) of the compressor 1 are separated to prevent backflow of gas from the downstream side to the upstream side of the compressor 1. A packer (not shown) is attached. The compressor 1 sucks in the natural gas (hereinafter referred to as ambient gas) 120 of the gas layer 102 whose pressure has dropped to a level at which it cannot self-inject, compresses it to a pressure at which it can self-inject, and then releases it toward the ground. The compressed gas 122 released from the compressor 1 rises in the steel pipe 104, is ejected to the ground, is sent to the separator 140 via the gas transport pipe 142, and is separated into a gas component and an oil component. FIG. 1 shows a cross-sectional view of a compressor showing a first embodiment of the present invention. As shown in FIG. 1, a turbo type compressor is adopted as the compressor 1, and the compressor 1 is held inside the casing 11 by a rotating shaft 13 and a rotating shaft 13 which are rotationally driven by a motor 12, and are provided at substantially equal intervals in the circumferential direction. An inverter 4 having an impeller 15 having a turbocharged blade 14 and converting power supplied from a transmission cable 132 to drive a motor 12, and a database 2 of storage means and a calculation means 3 as control mechanisms of the inverter 4 It is equipped. In the above configuration, the working fluid sucked from the suction port by the rotation of the impeller 15 is accelerated and boosted by the rotation action of the impeller 15 and guided to the downstream.

In the conventional apparatus, when operating in an operating environment in which liquids are mixed, the liquids mixed in the impeller 15 in the conventional compressor shown in FIG. 4 adhere to the blades 14 to form a liquid film. As a result, not only the efficiency of the compressor is lowered because the shaft power of the impeller 15 is increased, but also the permissible shaft power of the motor 12 for driving the impeller is exceeded, which causes a stop due to a trip. Further, the liquid film adhering to the blade 14 blocks the flow path, so that the operating range is reduced and unstable fluid force is generated, and the wall thickness of the impeller is reduced due to erosion.

On the other hand, in the form of the compressor of the present embodiment, at least the tendency of the axial power acquired from the motor 12 is determined in the database 2 by referring to, for example, the amount of increase in the axial power with respect to the liquid fraction shown in FIG. In this case, the calculation means 3 controls the rotation speed of the motor 12 to be temporarily increased via the inverter 4.

Specifically, in the state of a certain liquid content ratio 306, since there is no adhesion to the blade 14 at the beginning, the axial power can be low according to the solid line data 302, but when the liquid mixed in the impeller 15 adheres to the blade 14, Axial power increases according to the dotted line 304. The formation of the liquid film is determined with reference to the amount of increase in the axial power, and the rotation speed of the motor 12 is controlled to be temporarily increased.

As a result, the liquid flowing into the impeller 15 is atomized by the shearing force due to the rotation speed into droplets to prevent the formation of a liquid film, so that the liquid content is prevented from adhering to the blades 14 and is shown in FIG. As shown above, since the increase in the axial power of the impeller 15 is suppressed as compared with the case where the liquid film is formed, it is possible to suppress a decrease in efficiency and a stop due to a trip of the motor 12.

Further, since the adhesion of the droplets to the blade 14 is suppressed, it is possible to suppress the reduction of the operating range and the generation of unstable fluid force due to the blockage of the flow path. From the above, it is possible to prevent the droplets mixed in the impeller 15 from changing into a liquid film by controlling the rotational state of the impeller 15 by using at least the information of the axial power detected from the motor 12. Therefore, it is possible to operate the impeller 15 without reducing the efficiency and operating range of the impeller 15. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

FIG. 2 is a cross-sectional view of a compressor showing a second embodiment of the present invention. As shown in FIG. 2, a turbo type compressor is adopted as the compressor 1, and the compressor 1 is held inside the casing 11 by the rotating shaft 13 and the rotating shaft 13 which are rotationally driven by the motor 12, and are provided at substantially equal intervals in the circumferential direction. It has an impeller 15 having a turbocharger 14, and is provided with a sensor 5, a database 2, a calculation means 3, and an inverter 4 arranged upstream of the impeller 15.

In the above configuration, the working fluid sucked from the suction port by the rotation of the impeller 15 is accelerated and boosted by the rotation action of the impeller 15 and guided to the downstream. When operating in an operating environment in which liquids are mixed, the liquids mixed in the impeller 15 in the conventional compressor shown in FIG. 4 adhere to the blades 14 to form a liquid film. As a result, not only the efficiency of the compressor is lowered because the shaft power of the impeller 15 is increased, but also the permissible shaft power of the motor 12 is exceeded, which causes a stop due to a trip. Further, the liquid film adhering to the blade 14 blocks the flow path, so that the operating range is reduced and unstable fluid force is generated, and the wall thickness of the impeller is reduced due to erosion.

On the other hand, in the form of the compressor of the present embodiment, the threshold value calculated by using at least the information on the flow velocity of the liquid content acquired by the sensor 2 provided upstream of the impeller 15 and the droplet diameter of the liquid. When the formation of the liquid film is determined by referring to the database 2 of the storage means, the calculation means 3 controls the rotation speed of the motor 12 to be temporarily increased via the inverter 4. As a result, the liquid flowing into the impeller 15 is atomized by the shearing force due to the rotation speed into droplets to prevent the formation of a liquid film, so that the liquid content is prevented from adhering to the blades 14 and is shown in FIG. As shown, since the increase in the axial power of the impeller 15 is suppressed, it is possible to suppress a decrease in efficiency and a stop due to a trip of the motor 12.

Further, since the adhesion of the droplets to the blade 14 is suppressed, it is possible to suppress the reduction of the operating range and the generation of unstable fluid force due to the blockage of the flow path.

From the above, the sensor 2 is installed upstream of the impeller 15, and the rotational state of the impeller is controlled by using at least the information on the flow velocity of the liquid and the information on the droplet diameter of the liquid acquired by the sensor 2. It is possible to prevent the droplets mixed in the impeller 15 from changing into a liquid film, and it is possible to operate the impeller 15 without reducing the efficiency and operating range of the impeller 15. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 Compressor, 2 Database, 3 Computational means, 4 Inverter, 5 Sensor, 11 Casing, 12 Motor, 13 Rotating shaft, 14 blades, 15 impeller

Claims (2)

Rotation axis and
The motor that drives the rotating shaft and
An inverter that supplies power to the motor and
An arithmetic means for controlling the inverter and
In a compressor equipped with an impeller attached to the rotating shaft,
It is equipped with a sensor located upstream of the impeller.
When the formation of a liquid film on the blades of the impeller is determined by using at least the information on the flow velocity of the liquid and the information on the droplet diameter from the sensor, the calculation means flows into the impeller. Is atomized by the shearing force due to the rotation of the impeller so as to temporarily increase the rotation speed of the motor via the inverter in order to suppress the adhesion of droplets to the blades of the impeller. A compressor characterized by controlling the rotational state. In the compressor of claim 1,
The storage means includes a database for determining the formation of a liquid film on the blades of the impeller based on at least the information on the flow velocity of the liquid and the information on the droplet diameter from the sensor. compressor, characterized in that.

Images