JPS5810592B2 - Compressor overspeed prevention device for gas pipeline booster station - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a gas pipeline booster station using a gas turbine-driven compressor, and particularly to a gas pipeline booster station that uses a compressor driven by a gas turbine to prevent overspeed due to the use of a turbine at the time of startup. This invention relates to an overspeed prevention device.

[Prior art]

A gas pipeline booster station using a gas turbine-driven compressor can be started by closing the station outlet valve, then opening the station outlet valve after a few minutes and closing the station bypass valve, or by closing the station outlet valve from the beginning of startup. A method is adopted in which the valve is fully opened and the station bypass valve is closed at the same time.

A systematic explanatory diagram of a conventional gas pipeline booster station is shown in FIG.

In the figure, 1 is the station inlet line, 2 is the station inlet valve, 3 is the gas turbine driven compressor, 4 is the gas cooler, 5 is the station outlet valve, 6 is the station outlet line, 7 is the station inlet line 1 and the station outlet 8 is a station bypass line provided with station bypass valve 7; 9 is a recycle valve; 10 is a recycle line provided with recycle valve 9; 11 is a suction header; 12 is station inlet valve 2 13 is a scrubber provided on the compressor inlet line 12, 14 is a compressor inlet valve, 15 is a compressor outlet line connected to the outlet side of the compressor 1, 16 is a compressor outlet line 15 17 is a compressor outlet valve, 18 is a discharge header, and 19 is a recycle header.

There, the gas to be transported passes through an inlet line 1 and an inlet valve 2 and is compressed by a compressor 3 and then into a cooler 4.
and the station outlet valve 5 to be routed to the outlet line 6.

In addition, if the station is completely stopped, the main bypass valve 7
Gas is sent through a bypass line 8 and bypassing the station.

When starting the station, as described above, two methods are mainly used: one method is to start the station with the station outlet valve 5 closed, and the other is to start it with the station outlet valve 5 fully open at the initial stage of startup.

Of these, in the case of the former method in which the station outlet valve 5 is closed and started, the gas turbine is internally started and maintained at an intermediate speed after passing through purge, pressure increase, and pressure equalization in each pipe.

After a few minutes, the station outlet valve 5 begins to open, the station bypass valve 7 closes, the rotation speed increases to 100%, and the remaining gas turbines are started sequentially every few minutes.

Figure 2 shows the characteristic curve of the compressor.

As mentioned above, when starting with the station outlet valve 5 closed, the flow rate does not increase even if the rotation speed of the compressor increases, and the compressor is operated in the surging region 21 on the upper left side of the surging line 20 shown in FIG. The compressor causes surging.

In this case, in order to prevent surging, a recycle operation is performed using the recycle valve 9 and recycle line 10 shown in FIG. 1 to prevent the compressor from entering the surging region 21.

However, since recycling operation involves an increase in temperature,
It has the disadvantage that it cannot be operated for long periods of time.

In other words, the gas temperature usually rises in a few minutes to ten-odd minutes to the point where it adversely affects equipment such as the compressor and valve body, or pipe coatings.

On the other hand, in the case of the latter startup method, if the station outlet valve 5 is fully opened from the initial stage of startup, the above drawbacks are resolved;
If the station bypass valve 7 is closed at the wrong timing, the suction pressure of the station will become higher than the discharge pressure, and the fluid will drive the compressor, which will rotate the gas turbine. The problem is that the compressor becomes a turbine and the compressor overspeeds.

[Purpose of the invention]

The purpose of the present invention is to prevent the compressor from becoming a turbine by preventing the compressor inlet pressure from becoming higher than the outlet pressure when starting a booster station of a gas pipeline, and to avoid the compressor from becoming overspeed. This allows the compressor to be started safely.

[Structure of the invention]

The present invention provides a compressor bypass line for the compressor of a gas pipeline booster station, a compressor bypass valve for the compressor bypass line, and a pressure detector for detecting the pressure difference before and after the compressor, and a pressure detector for detecting the pressure difference before and after the compressor. A flow rate detector is provided to detect the gas flow rate flowing through the compressor, and the opening and closing of the compressor bypass valve is controlled based on the detected values of the pressure detector and the flow rate detector. is used as a recycle line to prevent surging, and when the station bypass valve is closed and the compressor inlet pressure becomes higher than the outlet pressure, the compressor bypass line is used to temporarily reduce the compressor inlet and outlet pressures. By setting the pressure to the same level, the inlet pressure of the compressor is lowered and the compressor is prevented from becoming a turbine and overspeeding.

〔Effect of the invention〕

According to the compressor overspeed prevention device for a gas pipeline booster station of the present invention, the compressor inlet pressure can be made lower than the compressor outlet pressure when starting the gas pipeline booster station, and the compressor can be prevented from becoming a turbine. This has the excellent effect of completely preventing the compressor from overspeeding, thereby making it possible to start the compressor safely.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A compressor overspeed prevention device for a gas pipeline booster station, which is an embodiment of the present invention, will be described in detail below with reference to the drawings.

FIG. 3 shows a system diagram of a booster station according to an embodiment of the present invention.

This system diagram is generally the same as that shown in FIG. 1, but a compressor bypass valve 22 and a compressor bypass line 23 are provided in the compressor 3 instead of the recycle line 9 shown in FIG. ing.

Therefore, when the station bypass valve 7 is closed at the wrong time and the compressor inlet pressure becomes higher than the outlet pressure when starting the station, the compressor bypass valve 22 is opened to prevent the compressor from becoming a turbine, and to prevent the compressor from turning into a turbine during startup or operation. Even when the compressor enters a surging region during operation, the compressor bypass valve 22 is opened to prevent surging.

FIG. 4 shows a more detailed partial view of the overspeed prevention device in one embodiment of the present invention.

In the figure, 24 and 25 are differential pressure transmitters 26
27 is an electric signal, 28 is an arithmetic unit, 29 is an electric signal, and 30 is a transducer.

Therefore, the differential pressure transmitter 24 detects the flow rate Q, and the differential pressure transmitter 25 detects the compressor head ΔP and converts them into electrical signals 26 and 27, respectively.

The calculator 28 calculates the surging line 20 (ΔP/Q2) shown in FIG. 2 from the electric signals 26 and 27,
If this is larger than the set value α, the transducer 30
The compressor bypass valve 22 is opened to prevent surging.

Further, when a back pressure is generated in the differential pressure transmitter 24, an electric signal 29 is sent to the transducer 30 to open the compressor bypass valve 22 and prevent the compressor 3 from becoming a turbine.

The mechanism for preventing the compressor 3 from becoming a turbine can prevent overspeed due to the compressor becoming a turbine when starting up the booster station, making it possible to start up the station with high reliability and safety.

FIG. 5 shows another embodiment of the present invention, in which a check valve 31 is used as a compressor bypass valve provided in a compressor.

This check valve 31 opens when the inlet pressure of the compressor 3 becomes higher than the outlet pressure, and prevents the compressor 3 from becoming a turbine.

In this embodiment, the recycle line is installed separately, exactly as shown in FIG. 1, but the equipment shown in FIG. 4 is not required.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a conventional gas pipeline booster station, Fig. 2 is a graph showing the characteristics of a general compressor, Fig. 3 is a system diagram of a gas pipeline booster station in an embodiment of the present invention, and Fig. 4 is a system diagram of a conventional gas pipeline booster station. This figure is a system diagram showing an example of the control mechanism of the compressor overspeed prevention device in FIG. 3, and FIG. 5 is a system diagram of a gas pipeline booster station in another embodiment of the present invention. 1...Station entrance line, 3...
・Compressor, 6...Station exit line, 7
...Station bypass valve, 8...
Station bypass line, 22... Compressor bypass valve, 23... Compressor bypass line,
31...Check valve.

Claims (1)

[Scope of Claims] 1. In a gas pipeline booster station using a plurality of gas turbine-driven compressors, a bypass line is provided to bypass the entire booster station and allow gas to flow, and a compressor bypass line is provided to the compressor. At the same time, a compressor bypass valve is provided in the compressor bypass line, and a pressure detector for detecting the pressure difference before and after the compressor and a flow rate detector for detecting the gas flow rate flowing through the compressor are provided. 1. A compressor overspeed prevention device for a gas pipeline booster station, characterized in that opening and closing of the compressor bypass valve is controlled based on detected values of a gas pipeline booster station and a flow rate detector.