JPH03217395A - Compressor controller for liquefied gas carrier - Google Patents

Abstract

PURPOSE:To make it possible to perform automatic control over plural units of compressors by displaying a fact that discharge of plural compressors is changed in accordance with the setting side of pressure in a cargo tank, and executing the discharge change of each compressor according to the input of a starting permission signal. CONSTITUTION:When liquefied gas 5 is loaded, first of all, a loading start is inputted by a keyboard 1b, and conveyance of this liquefied gas 5 is started from a ground side base 3. When output of a pressure gauge 7 detecting pressure in a cargo tank 4 to be raised by evaporated gas 6 is reached to a setting value P0, the starting of a No.1 compressor 8 is displayed on a cathode-ray tube 1a. When an operator has inputted the starting permission after looking this display, a motor 9 for this No.1 compressor 8 is started. Next, after full- closing of a surge valve 11, opening of a guide vane 12 is regulated, controlling the pressure so as to become a setting value F0. In this connection, when a pressure setting value P1 is reached, drive of a No.2 compressor 2 is accelerated, starting a motor 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compressor control device for a liquefied gas carrier used for processing vaporized gas accompanying the transfer of liquefied gas.

[Conventional technology]

Traditionally, due to the nature of the cargo (cryogenic), liquefied gas carriers
A large amount of vaporized gas is generated during loading, so a compressor is used to return the generated gas to the land base to prevent the pressure from increasing in the cargo tank.

Therefore, it is necessary to operate the compressor to maintain a constant pressure in the cargo tank.

[Problem to be solved by the invention]

By the way, at the beginning and end of loading, the volume of gas in the cargo tank decreases (as the liquid level rises, the gas layer capacity decreases).
are different. Additionally, since the cargo tanks are also cooled by liquefied gas, the amount of gas generated gradually decreases. Therefore, it is difficult to control the pressure of the compressor to be constant. Also, usually. Two congressors are used, but constant pressure control does not allow them to be operated with the same load.

In the conventional control method, the discharge pressure of the conzoresor was controlled to be constant so that the two compressors were operated in the same way regardless of the cargo tank pressure. Therefore, when controlling cargo tank pressure, it was necessary to manually change the discharge pressure setting. Also, in constant discharge pressure control. When the suction pressure of the compressor (which is almost the same as the pressure of the cargo tank) changes, the flow rate also changes, which has caused problems in receiving cargo at land bases.

Sara K. When using two compressors, first
Start the first compressor, and when its load increases, start the second compressor. Here, since the discharge pressure of the first unit is high, it is necessary to squeeze the inlet guide pane once, and then when the second unit is started, the inlets of the two units have to open the idle panes in the same way, which is difficult to do manually. become.

The present invention has been made in view of the above points, and an object of the present invention is to provide a compressor control device for a liquefied gas carrier that can automatically control a plurality of congressors and maintain a constant allowable pressure in a cargo tank.

[Means and actions to solve the problem]

In other words, the present invention provides a method for controlling the pressure increase in a cargo tank due to the evaporation bus that occurs when liquefaction is carried out on a carrier ship, using step control based on the upper and lower limits of the allowable pressure of the cargo tank, and adjusting the flow rate of the compressor according to the set pressure. It was designed to change the .

In addition, when making changes, the changes are made in response to the operator's startup permission input, so that changes can be made after confirming the receiving system of the land base. This allows the compressor load and cargo tank pressure to be controlled simultaneously. Furthermore, by inputting signals for detecting the operating states of a plurality of compressors into one condenser control device, complex automatic control of a plurality of compressors at the same time becomes possible.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A condepressor control device for a liquefied gas carrier according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing its configuration. First, an operator uses the key card 1b to control the pressure of the cargo tank, the flow rate of the compressor, etc. necessary for the automatic control of the compressor of the present invention, as shown in FIG. Initial setting values of various control information are inputted and stored in compressor control device #2. The configuration of this compressor control device 2 is shown in FIG.

In FIG. 2, an input device 31 controls the input of various signals. Necessary information is provided to each device based on the status of various signals obtained through the arithmetic unit 32 and input device 3. The storage device 33 stores initial setting values shown in FIG. The control device 34 is a control device for the monitoring CRT 1a and the keypad lb. The PID controller 35 is for the No. 1 compressor 8, and the inlet for controlling the flow rate of the No. 1 compressor determines the opening degree of the pipe 712.

PID controller se. This is for the No. 2 compressor 16, and the inlet for controlling the flow rate of the No. 2 compressor determines the opening degree of the idle pane 20. The output device 37 performs output control of various signals.

Also, the signal lines & are 7.13, 14, 11 in Figure 1.
5. Transmit signals from various devices indicated by 12, 11, 21, 22, 23, 120, and 19 to the input device 3. Signal lines 13.74, 15, 21, 22.2 in Figure 1
The signals from various devices indicated by 3 are transmitted to the arithmetic unit 32.

The signal line C transmits the signal of the inlet guide vane 12 to the PID controller 35. The signal line d has an inlet that transmits the signal of the ID pane 20 to the PID controller 36 . Signal line e, arithmetic unit @. s 2 transmits the initial value of reception to the memory device 33, and the memory device f33
The value of is transmitted to the arithmetic unit 1jsz. The signal line f transmits the CRT 1a signal output from the arithmetic device 32 to the control device 34. The key data 1b signal output from the control device 34 is transmitted to the arithmetic device 32. The signal line g transmits start/stop signals for the driving motors 9, 17 to the output device 37.

The signal line h transmits the flow rate of the No. 1 compressor 8 corrected by the arithmetic unit 32 and its set value to the PID controller 35.
tell to. The signal line 1 is the signal line 2 corrected by the arithmetic unit 32.
Flow rate of compressor 16 and its set value'& PID
The controller 36 is informed.

Signal line jVi. Information about the inlet guide pane J2 determined by the PID controller 35 is transmitted to the output device 37. The signal line k, an inlet determined by the PID controller 36, conveys the information of the ID pane 20 to the output device 37.

Signal line 1 connects signals from keyboard 1b to control device 34.
2 and transmits the signal of the control device 34 to the CRTJ&. The signal line m transmits start/stop signals to the driving motors 9, 17. The signal line n is connected to the inlet guide pane 12.
transmits control signals to.

Signal line 0 has an inlet that conveys a control signal to the id pane 20 .

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG.

First, before loading begins, the operator must check the key? - By inputting the loading start through the code 1b, the compressor control system W
2 controls the two consoles 8 and 6 based on the set values shown in FIG. 4 (step S). The delivery of liquefied gas 5 is started from the land base 3 and is loaded into the cargo tank 4. The loaded liquefied gas 5Fi is vaporized by heat input from the liquid supply pipe and the cargo tank 4. This vaporized gas 6 increases the pressure in the cargo tank 4. The pressure in the cargo tank 4 is detected by a pressure gauge 7 and sent to the compressor control device 2.

The compressor control device 2 sets the pressure of the cargo tank 4 to a set value P. When the image (a) in Figure 4 is displayed on CRT 1a
The start of the No. 1 compressor 8 determined at t is displayed (steps S2, S3). This display allows the operator to enter permission to start through the key card 1b, and the compressor control device 2 activates the No. 1 compressor. / Outputs a start signal to the motor 9 of the Delessa 8 and starts the motor 9 (Stede S
4, Ss). After the motor 9 is started, the surge control device 10 of the No. 1 compressor 8 fully closes the surge valve 1, and a full close signal is input to the compressor control device Pt2. After the compressor control device 2 confirms that the surge valve is fully closed (step S6). Adjust the opening degree of the inlet guide pane 12 to set value F in FIG.

It is automatically controlled so that Here, since the control fluid is controlled by temperature and pressure, the compressor control device 2F
The value of the i-flow meter 13 is corrected based on the values of the thermometer 14 and the pressure gauge 15, and the inlet automatically controls the ID vane 12 based on this correction value (S7.88).

After the No. 1 conzoresor 8 is started, the pressure in the cargo tank 4 further increases and when it reaches the set value P1 in Fig. 4, the compressor control device M2 displays an increase in the flow rate of the No. 1 compressor 8 on the CRT 1a Steps 89-811). When the operator inputs startup permission here, the compressor control device 2 automatically controls the inlet vane 12 so that the set value F shown in FIG. 4 is reached (steps 812 to S
14). Furthermore, when the pressure in the cargo tank 4 reaches the set value P, the compressor control device 2
Displaying the activation of the No. combresa 12 (step S15)
, S16). Based on this display, when the operator inputs permission, the compressor control device 2 automatically starts the inlet of the No. 1 co/compressor 8 to gradually reduce the opening of the valve/12 to the minimum opening, and then starts the motor l7 of the No. 2 compressor 6. Outputs a signal and starts the motor 17 (step 81)
7-S19). After starting the motor 17, the surge control device 18 of the No. 2 compressor 16 fully closes the surge valve 19, and a full close signal is input to the compressor control device fl2K. The compressor control device fjI2 is. After confirming that the surge valve 19 is fully closed (step fs20), each compressor 8, 16
The flow rate is the set value F. The inlet guides 712 and 20 are automatically controlled so that (steps 821 and 822
). When the pressure in the cargo tank 4 reaches P again, the compressor control device 2 displays on the CRT 1a an increase in the flow rates of the two compressors 8 and 16 (Stede 823, S2
4). Then, the operator inputs activation permission through the keyboard 1b. The compressor control device 2 automatically adjusts the inlet guy F to the set value F1 shown in Fig. 4.
Control vane 12.20 (step 825, S2
6). If the pressure in the cargo tank 4 falls below the set value P,
The compressor control device 2 controls the flow rate of the No. 2 compressor 16 on the CRT 1a as normal F. to return to k CRT
1 Display on a (Stede 827, 828). Based on this display, when the operator inputs startup permission. The compressor control device 2 is F. K control is performed so that (Stede 829, 830).

The pressure in cargo tank 4 further decreases to the set value P shown in Figure 4.
2, compressor control system 2ViCRT 1
The stoppage of No. 1 compressor 8 is displayed on a (steps 831, 832). Then, according to the operator's permission input, the compressor control device 2-hole inlet is
2. When the flow rate of the compressors 8 and 16 reaches the set value FS, the inlet guide pane 12 is fully closed after outputting a stop signal to the motor 9.
~S37).

Thereafter, the control device 2 determines that the inlet is
Set value F. (Step 83)
8).

Nearing the end of loading, the amount of gas 6 decreases and the cargo tank 4
When the pressure reaches the set value P, shown in FIG. 4, the compressor control device 2 displays a decrease in the flow rate of the No. 2 compressor 16 on the CRTJa (S39, S40). Based on this display, the compressor control device automatically controls the inlet input port 720 to the set value F (steps 841 to S43). After that, if the pressure in the cargo tank 4 is below P3 even after several minutes have passed, the compressor control system #2
Displays the stop of No. compressor 16, outputs a stop signal to motor 17 according to the operator's permission input, and outputs a stop signal to motor J7.
is stopped (steps 844 to S47).

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be achieved by
can be done.

■ All setting values necessary for automatic control are entered and stored in the compressor control device in advance, and the flow rate of the compressor is not changed until the operator inputs startup permission. This allows communication with land bases without causing any problems.

■ By changing the cargo tank pressure to step control, the compressor can be automatically controlled to maintain a constant flow rate, and load distribution can be automatically adjusted.

■ By using a conventional surge control device, the compressor itself can also be a conventional one.

- By inputting the operating status of multiple compressors to the conzoresor control device, it is possible to simultaneously start/stop multiple congressors and control the flow rate.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a system configuration according to an embodiment of the present invention, FIG. 2 is a block diagram showing a circuit configuration of a compressor control device of the same embodiment, and FIG. 3 is a diagram for explaining the operation of the same embodiment. The flowchart of FIG. 4 is the automatic control K of the same embodiment.
FIG. 3 is a diagram showing necessary initial setting values. 11...CRT. Jb...keyboard r, 2...compressor control device, 3...land base, 4...cargo tank. 5...Liquification is... 6... Vaporization is good. 7. J
5, 23, 24 and 25...pressure gauge, 8...1
No. compressor, 9 and 17... motor, 10 and 18... surge control device. IJ and 19... Surge valve, 12 and 20... Inlet is ID pane, 13 and 21... Flow meter, 14 and 22...
Thermometer, J6-゜゛No. 2 compressor. 2 Humbrenosa allocation device Fig. 2 Fig. 3 (Part 1) Fig. 3 (Part 2) Chest 3 Fig. (Part 5) Fig. 4

Claims (1)

[Claims] A plurality of compressors that adjust the pressure of the cargo tank; a setting means that sets the pressure of the cargo tank in advance; and a flow rate of each of the compressors that changes according to the set pressure set by the setting means. 1. A compressor control device for a liquefied gas carrier, comprising: a control means for displaying a message indicating that the start permission signal is input, and for changing the flow rate of each of the compressors in response to input of a startup permission signal.