KR101350803B1 - Compressor load controlling module of lng carrier and the control method using this - Google Patents

Abstract

The present invention provides an inlet guide vane mounted on an inlet side of a compressor mounted on a pipe supplied from a LNG tank toward a boiler side in order to supply BOG generated from an LNG tank of an LNG carrier as a fuel gas. Inlet Guide Vane (hereinafter referred to as 'IGV') and a compressor load controller electrically connected to the drive motor of the compressor operate the IGV in the low flow rate section of the compressor and control the RPM of the drive motor in the high flow rate section of the compressor. In LNG carriers, the BOG generated from liquid cargo tanks, such as LNG carriers, is used as fuel gas for boilers. It relates to a load control module and a control method using the same.

Description

COMPRESSOR LOAD CONTROLLING MODULE OF LNG CARRIER AND THE CONTROL METHOD USING THIS

The present invention relates to a compressor load control module of an LNG carrier and a control method using the same. More specifically, in the case of using BOG generated from a liquid cargo tank such as an LNG carrier as fuel gas of a boiler, low flow operation is performed like a boiler. The present invention relates to a compressor load control module of an LNG carrier and a control method using the same to stably control a compressor load in a required system and to smoothly supply fuel.

In industrial sites using compressors, compressors are controlled in various ways depending on the type of compressor and the type of system in which the compressor is mounted.

The load of the compressor is generally controlled by a variable RPM method.

In particular, BOG (Boil off gas) is always generated from the liquid cargo tank containing cryogenic liquid cargo, such as LNG carriers, it can be considered to use the BOG as a fuel gas by supplying the boiler to the boiler in the ship, where the compressor Load control is very important.

However, in a system requiring a low flow rate operation such as a boiler, the compressor operation is impossible due to the surge of the compressor.

This will be briefly described with reference to the pressure ratio-flow rate graph of FIG. 4.

For reference, the curve indicated by the solid line in FIG. 4 is the performance curve of the compressor, and the curve indicated by the dotted line indicates the system resistance curve, respectively, and the '●' mark at the intersection of the performance curve and the system resistance curve indicates the operating point.

That is, the load of the compressor can be reduced by varying the drive motor RPM of the compressor at the point where the performance curve above the operating point and the system resistance curve intersect.

However, in the low flow rate (Boiler Demand) required by the boiler, which is a section below the operating point, a surge line is encountered as shown in FIG. 4, that is, a surge occurs in the compressor and the compressor shuts down. As a result, the entire fuel supply system may be paralyzed.

The present invention has been invented to improve the above problems, and when using BOG generated from a liquid cargo tank such as an LNG carrier as fuel gas of a boiler, the compressor load is stably applied in a system requiring low flow operation such as a boiler. An object of the present invention is to provide a compressor load control module of an LNG carrier and a control method using the same so that fuel can be smoothly supplied while controlling.

In order to achieve the above object, the present invention provides a compressor mounted on a pipe for supplying a BOG generated from an LNG tank of an LNG carrier as a fuel gas to a boiler, and a suction amount of fuel gas mounted on an inlet side of the compressor. It is electrically connected to the inlet guide vane (IGV) controlling the IGV and the driving motor of the compressor, respectively, to operate the IGV in the low flow section of the compressor, and to the RPM of the driving motor in the high flow section of the compressor. It will be possible to provide a compressor load control module of the LNG carrier, characterized in that it comprises a compressor load controller to control the.

Meanwhile, the present invention provides an inlet guide mounted on an inlet side of a compressor mounted on a pipe supplied from a LNG tank toward a boiler side in order to supply BOG generated from an LNG tank of an LNG carrier as a fuel gas to the boiler. A compressor load controller electrically connected to the inlet guide vanes (IGV) and the drive motor of the compressor operates the IGV in the low flow rate section of the compressor and controls the RPM of the drive motor in the high flow rate section of the compressor. It may also be possible to provide a control method using a compressor load control module of an LNG carrier.

Here, it is preferable that the compressor load controller operates the IGV in an interval of 0.001 to 30% of the design point of the compressor.

At this time, the compressor load controller preferably controls the RPM of the drive motor in 30 to 100% of the design point of the compressor.

In addition, the compressor load controller operates the IGV in an interval of 0.001 to 30% of the design point of the compressor, and the IGV increases the surge margin of the compressor while reducing the compression ratio increase of the compressor with respect to the BOG supply amount directed toward the compressor. will be.

In addition, the compressor load controller, it is preferable to reduce the RPM of the drive motor to 50 to 99% of the normal operating RPM in 30 to 100% of the design point of the compressor.

Here, the boiler load control valve is preferably further provided on the pipe between the compressor and the boiler.

At this time, it is preferable that an anti-surge valve is further mounted on the bypass pipe bypassed from the inlet pipe of the compressor to the outlet pipe of the compressor.

In addition, the boiler load control valve mounted on the pipe between the compressor and the boiler and the boiler load controller electrically connected to the sensors embedded in the boiler control the opening and closing of the boiler load control valve according to the remaining amount of fuel gas in the boiler. Compressor load controller preferably controls the drive motor and IGV of the compressor in conjunction with opening of the boiler load control valve.

According to the present invention of the above configuration, the inlet guide vanes controlled by the compressor load controller at the inlet side of the compressor to operate in the low flow rate by increasing the surge margin to turn the operation (turndown) appearing on the compression ratio-flow graph The effect of extending the ratio can be achieved.

Therefore, by controlling the opening and closing degree of the inlet guide vanes it is possible to control the flow rate of the stable compressor in the low flow rate section and to facilitate the fuel supply.

In particular, the present invention can be modularly mounted to the compressor load controller and the inlet guide vanes in any fuel supply system including the existing compressor, it is easy to install and operate as well as convenient maintenance.

1 is a conceptual diagram showing the overall configuration of a compressor load control module of the LNG carrier according to an embodiment of the present invention
2 is a performance curve of a compressor controlling IGV using a compressor load controller which is a main part of a compressor load control module of an LNG carrier according to an embodiment of the present invention in a low flow rate section;
3 is a flowchart illustrating a control method using a module for controlling a compressor load of an LNG carrier according to an embodiment of the present invention.
4 is a performance curve of a compressor according to a general RPM variable control method

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a conceptual diagram showing the overall configuration of the compressor load control module of the LNG carrier according to an embodiment of the present invention, Figure 2 is a main portion of the compressor load control module of the LNG carrier according to an embodiment of the present invention in a low flow rate section This is the performance curve of a compressor that controls IGV using a denier compressor load controller.

For reference, in FIG. 2, the x axis represents a flow rate, the y axis represents a pressure ratio, the curves represented by the solid lines represent the performance curves of the compressor 100, and the curves represented by the dotted lines represent the system resistance curves. In each case, '●' at the intersection of the performance curve and the system resistance curve indicates an operation point.

The present invention can be seen that the compressor load controller 300 is a module for controlling the RPM of the inlet guide vanes 200 (hereinafter referred to as 'IGV') and the drive motor 110 as shown.

Here, reference numeral 310 denotes a control program of the compressor load controller 310 having a built-in control function, and 800 denotes a cooler for preventing overheating of the BOG passing through the compressor 100.

It is to be understood that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention.

According to the present invention, the IGV 200 is mounted at the inlet side of the compressor 100 together with the compressor 100, and the compressor load controller 300 controls the drive motor 110 and the IGV 200 of the compressor 100. Embodiments may be applied.

The compressor 100 is mounted on a pipe 600 for supplying BOG generated from the LNG tank 400 of the LNG carrier to the boiler 500 as a fuel gas.

The IGV 200 is mounted at the inlet side of the compressor 100 to control the suction amount of the gas for fuel.

The IGV 200 generally varies the inlet area of the compressor 100 while changing the rotation angle according to the operation of the actuator. Since the IGV 200 is known to have a myriad of opening and closing methods, detailed structure and operation mechanism will be omitted for convenience. .

The compressor load controller 300 is electrically connected to the IGV 200 and the drive motor 110 of the compressor 100, respectively, to operate the IGV 200 in a low flow rate section of the compressor 100, By controlling the RPM of the drive motor 110 in the high flow rate, the boiler 500 is generally focused on requiring the compressor 100 to operate in a low flow rate section.

That is, the compressor load controller 300 controls the RPM of the drive motor 110 in a 30 to 100% section of the design point of the compressor 100 as shown in FIG. Make it possible.

In more detail, the compressor load controller 300 typically sets the RPM of the drive motor 110 at a range of 50 to 99%, preferably 50%, of the normal operating RPM in a range of 30 to 100% of the design point of the compressor 100. By reducing the flow rate, the low flow rate operation of the compressor 100 is realized.

In addition, surge is provided on the bypass pipe 600 'which is bypassed from the inlet side i of the pipe 600 on which the compressor 100 is mounted to the outlet side o of the pipe 600 on which the compressor 100 is mounted. In preparation for the occurrence of the phenomenon, it is preferable that an anti-surge valve 120 is further mounted.

However, in the section below the driving point, as mentioned in the background art, since the surge occurs when the system resistance curve and the surge line cross, the anti-surge valve 120 alone cannot achieve the intended purpose. Bars need to take additional measures.

Therefore, the compressor load controller 300 operates the IGV 200 in the 0.001 to 30% of the design point of the compressor 100 (the area below the operating point in the graph), so that the IGV 200 is directed toward the compressor 100. The surge margin of the compressor 100, that is, the straight section having a smaller slope than the surge line is increased while reducing the amount of increase in the compression ratio of the compressor 100 with respect to the amount of BOG supplied.

That is, the compressor 100 is capable of stable operation while preventing the surge phenomenon occurring in the compressor 100 in the low flow rate region below the operating point compared to the graph of FIG. 4.

On the other hand, the boiler load control valve 510 is preferably further provided on the pipe 600 between the compressor 100 and the boiler 500.

Here, the boiler load control valve 510 and a sensor (hereinafter, not shown) built in the boiler 500 are electrically connected to the boiler load controller 700 separately provided, respectively, and the boiler load controller 700 is a boiler 500. The opening and closing of the boiler load control valve 510 according to the residual amount of fuel gas inside is controlled.

Therefore, the compressor load controller 300 controls the drive motor 110 and the IGV 200 of the compressor 100 in conjunction with the opening of the boiler load control valve 510.

The control method using the compressor load control module of the LNG carrier according to the present invention having the above configuration will be described with reference to FIG. 3.

For reference, reference numerals of drawings not shown in FIG. 3 refer to FIG. 1.

The boiler load control valve 510 mounted on the pipe 600 between the compressor 100 and the boiler 500 is determined to require fuel supply by a sensor built in the boiler 500. Is opened by

Thereafter, the compressor load controller 300 electrically connected to the boiler load control valve 510 selectively connects the drive motor 110 and the IGV 200 of the compressor 100 in association with the opening of the boiler load control valve 510. You're in control.

Here, the compressor load controller 300 allows a low flow rate operation while controlling the RPM of the drive motor 110 in a section that is 30% or more than the design point of the compressor 100, that is, the region above the operating point in FIG. 2.

At this time, the compressor load controller 300 operates the IGV 200 in a section 30% or less than the design point of the compressor 100, that is, the region below the operating point in FIG. 2, so that the IGV 200 is directed toward the compressor 100. The surge margin of the compressor 100, that is, the straight section having a smaller slope than the surge line is increased while reducing the amount of increase in the compression ratio of the compressor 100 with respect to the amount of BOG supplied.

Therefore, the compressor 100 stably supplies the BOG of the LNG tank 400 to the boiler 500 while performing a low flow rate operation.

Subsequently, the boiler load control valve 510 is shut off when the fuel supply to the boiler 500 is completed, and a series of control is completed. When the fuel supply is required at the boiler 500 side, the aforementioned control method is repeatedly performed. Could be.

As described above, the present invention uses BOG generated from a liquid cargo tank such as an LNG carrier as a fuel gas of a boiler so that fuel supply is smoothly performed while stably controlling the compressor load in a system requiring low flow operation such as a boiler. It is understood that the basic technical idea is to provide a compressor load control module for a LNG carrier and a control method using the same.

It will be apparent to those skilled in the art that many other modifications and applications are possible within the scope of the basic technical idea of the present invention.

Compressor 200 ... Inlet guide vanes
300 ... compressor load controller

Claims (9)

delete Inlet guide vanes mounted on the inlet side of the compressor mounted on a pipe supplied from the LNG tank toward the boiler to supply BOG generated from the LNG tank of the LNG carrier to the boiler. Inlet Guide Vane (hereinafter referred to as 'IGV') and the compressor load controller electrically connected to the drive motor of the compressor, respectively, operate at a low flow rate while controlling the RPM of the drive motor of the compressor in a section of 30% or more than the design point of the compressor. In the section that is 30% or less than the design point of the compressor, the surge margin of the compressor is increased while reducing the amount of increase in the compression ratio of the compressor relative to the amount of BOG fed to the compressor by the IGV. Control method using a module for controlling the compressor load of an LNG carrier, characterized in that. delete delete delete The method according to claim 2,
The compressor load controller, the control method using a compressor load control module of the LNG carrier, characterized in that for reducing the RPM of the drive motor to 50 to 99% of the normal operating RPM in the 30 to 100% of the design point of the compressor. . The method according to claim 2,
The control method using a compressor load control module of the LNG carrier, characterized in that the boiler load control valve is further provided on the pipe between the compressor and the boiler. The method according to claim 2,
And an anti-surge valve is further mounted on the bypass pipe that is bypassed from the inlet pipe of the compressor to the outlet pipe of the compressor. The method according to claim 2,
A boiler load control valve mounted on a pipe between the compressor and the boiler and a boiler load controller electrically connected to a sensor embedded in the boiler respectively open and close the boiler load control valve according to the remaining amount of fuel gas in the boiler. Controls the
The compressor load controller controls the drive motor and the IGV of the compressor in conjunction with the opening of the boiler load control valve using a compressor load control module of the LNG carrier.

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