JPS62199588A - Tank cooling method for lng ship in sailing - Google Patents

Abstract

PURPOSE:To enable an economical shipping service to be performed, by calculating a sprayed gas amount and its time necessary for cooling a tank from each information of tank pressure, spray valve opening and closing condition, spray nozzle pressure, tank temperature, ship speed, etc. and introducing a process for cooling the tank into a small computer. CONSTITUTION:A small computer 1 stores in memory an arithmetic expression establishing two conditions in which a tank condition is periodically repeated by a necessary boil-off gas amount, tank temperature (d) and tank pressure (a) suitable for a ship speed (e). And this computer 1, which inputs the tank pressure (a), spray valve opening and closing condition information (b), spray nozzle pressure information (c), tank temperature information (d) and the ship speed information (e), calculates the boil-off gas amount and its nozzle injection time necessary for cooling a tank, automatically performing a control for the operation time of a spray pump 4 and the opening adjustment of a spray valve 5 and cooling the tank 9. As a result, an economical operation schedule can be planned with no loss of surplus energy.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention utilizes evaporated gas from cargo (LNG (natural liquefied gas)) as propulsion material, and the LNG tank needs to be cooled during a voyage. The present invention relates to a method for cooling tanks during a voyage in an LNG ship.

[Conventional technology]

Tanks on LNG ships require regular spraying of liquefied gas to maintain a low temperature due to tank structural strength, or excessive boil-off gas is generated due to the relatively high temperature of the tank during loading.

If this cannot be handled safely, it is necessary to periodically spray liquefied gas into the tank during the voyage (the tank is cooled by the heat of vaporization when the liquefied gas spray evaporates).

In this case, the ship's crew used their experience and intuition to find a better method through trial and error.

[Problem that the invention seeks to solve]

In other words, relatively complex thermal calculations are required to calculate the amount of gas generated by spraying and the decrease in tank temperature, so there are problems in the ability and time for crew members to perform the calculations, and as a result, based on experience, it is difficult to determine the spray procedure. Because the process was searching for the gas, the amount of gas generated was too large, tending to generate unnecessary steam, making it uneconomical and not the most economical method.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology, and allows tanks to be cooled without losing surplus energy, allowing economical operation schedules to be drawn up, as well as manpower saving and safe and speedy operation. The purpose of the present invention is to provide a method for cooling tanks during a voyage in an LNG ship, which can cool tanks during a voyage.

[Failure to solve the problem]

The method of cooling tanks during voyage in an LNG ship according to the present invention uses a small computer to monitor the tank pressure, the opening/closing status of the spray valve, and the like.
A process has been introduced to cool the tank by calculating the amount of gas to be sprayed and the time required to cool the tank from information such as spray nozzle pressure, tank temperature, and ship speed.

[For production]

This invention uses information on tank pressure, spray valve opening/closing status, spray nozzle pressure, tank concentration, and ship speed that are manually entered into a small computer to inject the boil-off gas necessary for cooling the tank and the nozzle injection for cooling. It calculates the time and automatically adjusts the operating time of the spray pump and the opening of the spray valve to cool the tank.

〔Example〕

Hereinafter, the enforcement order for the tank cooling method during voyage in LNG ships of the present invention will be explained based on the drawings. FIG. 1 is a block diagram of a cooling control device applied to one embodiment.
1 in the figure is a small comviator, and this small computer 1 contains tank pressure information a from the Senna that detects the tank pressure of the LNG ship, spray valve open state information, spray nozzle pressure information C, and tank 9. Tank temperature information d from a sensor that detects the temperature of the tank and ship speed information e from a sensor that detects the ship's speed are input, and based on these pieces of information, the necessary information to cool the tank from the cruising ship speed is input. It is designed to calculate the amount and time of gale-off gas.

In addition, the most economical calculation method for tank temperature is to take into account the working conditions of the crew and set the spray time to daytime, so that the optimum spray method can be repeated every - day. The program is programmed in advance and stored in the storage device of this small comviator 1.

This small computer 1 is designed to control the spray zone destarter 2 and the spray valve solenoid pulp 3.
4 start and stop controls are performed.

This Spreponzo 4 is filled with LN in the tank 9.
This is for pumping up G and sending it to the spray pump discharge section 6. Tank 9 is mounted on the LNG ship, and is filled with LNG as propulsion fuel and cargo for the LNG ship.

Moreover, the spray valve solenoid pulp 3 has a plurality of spray valves 5.
Opening/closing control of the spray pump discharge valve 6 is performed. The gas pressure of the circulating gas based on the valve opening/closing degrees of these spray valves 5 and spray pump discharge part 6 is measured by the spray nozzle pressure gauge 7.
It is now detected by . This spray nozzle pressure gauge 7 allows the above-mentioned spray valve opening/closing state information, spray nozzle pressure information C, etc. to be obtained.

Each spray valve 5 communicates with a spray nozzle 8, and the spray nozzle 8 communicates with a tank 9. The tank 9 is cooled by injecting oil-off gas.

Next, a tank cooling method during a voyage in an LNG ship according to the present invention will be explained with reference to the flowchart shown in FIG. 2. Is this second diagram necessary to match the ship's speed? There are two conditions in which the tank conditions due to the amount of shear-off gas, tank temperature, and pressure are repeated periodically.In other words, the amount of sheil-off gas required for cooling the tank and the tank temperature change repeatedly on a daily basis. This is a calculation flowchart for establishing the conditions, and this formula is stored in the small computer 1.

1, the small computer 1 is started, and in step s1, the small computer 1
The spray valve opening/closing status information is sent from the spray nozzle pressure gauge 7.
In addition to inputting spray nozzle pressure information C, the pressure in the tank 9 is detected by a sensor (not shown) and tank pressure information a is inputted to the small computer 1.

Furthermore, the temperature of the tank 9 is detected by a temperature sensor (not shown) and tank temperature information d is inputted to the small comviator 1, and ship speed information e is also inputted to the small computer 1 from a speedometer (not shown). do.

Next, in step S2, these tank pressure information a
, spray valve opening/closing status information, spray nozzle pressure information C, tank temperature information d, and ship speed information e, the small computer 1 calculates the spray amount and spray time of boil-off gas, sends a signal to the spray 4 pump starter 2, and sends a signal to the spray nozzle 4. start.

At the same time, the Elispray valve solenoid noggle 3 is controlled based on the above calculation result of the small comviator 1, and a predetermined spray valve 5 is controlled by the spray valve solenoid noggle f3.
is selected and the opening degree of the spray bonder discharge part 6 is adjusted to set the pressure of the spray nozzle 8 indicated by the spray nozzle pressure gauge 7.

As a result, the boil-off gas from the spray pump 4 passes through the spray bonder discharge section 6, passes through the selected spray valve 5, and is injected into the tank 9 from the corresponding spray nozzle 8 to start spraying.

With this start of spraying, the tank 9 begins to be cooled, the temperature Tl of the tank 9 at that time is detected by the sensor, and the tank temperature information d is sequentially input to the small computer 1.

Next, in the spray fs3, the tank cooling time and the amount of gas to be sprayed are calculated using the tank temperature information d, and the spray valve solenoid noggle 3 is controlled based on the calculation result. Adjust the opening and closing of the spray pump discharge section 6.

In this way, by spraying the boil-off gas from the selected spray nozzle 8 into the tank 9,
is cooled, and when the temperature and boil-off gas amount calculated in step S4 are sprayed and the spraying is completed,
The output at the end of spraying is output to the spray 4 pump starter 2 and the spray valve solenoid pulp 3.

As a result, the operation of the spray pump starter 2 and the spray valve solenoid pulp 3 is stopped, the operation of the spray pump 4 is stopped, and the spray valve 5 and the spray valve discharge section 3 are closed. The temperature of the tank 9 at the end of this spraying is input into the small computer 1 as tank temperature information d.

Next, in step S5, the spray interruption time is inputted into the small comviator 1, and the temperature of the tank 9 is calculated by the small comviator 1 during the spray interruption time by 7 ps.
6)e Due to this temperature rise of the tank 9, in step S7, spraying of boil-off gas to the tank 9 is restarted in the same manner as above.

The temperature of the tank 9 at the time of restarting this spraying is detected and input into the small computer 1. This temperature T2 is compared with the temperature T1 at the beginning of spraying which was input to the small combinator 1 in step S2 in the Stellar S8.

As a result of this comparison, both temperatures T1 and T! are not equal (
T'1'; when Ts), the process returns to the spray fS1 again from step S8, and a series of processes from step S1 to step 58-1 are performed.

Further, in step S8, when the temperature T1 is equal to the temperature Tt (Tt=Tt), the process moves to step S9, detects the pressure in the tank 9 at the time of starting and ending spraying, and transmits the tank pressure information a to a small computer. 1, the small comviator 1 calculates the amount of gas to be sent, and when spraying, the amount of gas to be sent ss (step 511), and when interrupting spraying, the amount of gas to be sent at that time Vz (spray 7). 'S
12) and apply the calculation results to the spray fS.
Compare with I3.

As a result of this comparison, if the gas supply m V 1 = V s, the series of processing is completed, and if Vl ′ = Vz, step S
Returning to step 9, the processes of spray fS9 to S13 are performed again.

〔Effect of the invention〕

As described above, according to the tank cooling method for an LNG ship during voyage according to the present invention, the tank cooling method for an LNG ship during voyage allows A small computer is used to calculate the optimum spray amount and time so that the two conditions of cyclic repetition of the tank state depending on the tank temperature and pressure are calculated, and the male Ill-Off sprays the spray into the tank. As a result, an economical operation schedule can be planned without wasting surplus energy.

Along with this, it becomes possible to save labor and take safe and quick measures without worrying about dangerous situations such as rising or falling tank pressure.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a cooling control device applied to an embodiment of the tank cooling method during voyage in an LNG ship of the present invention, and Fig. 2 is a block diagram for explaining the tank cooling method during voyage in the LNG ship. It is a flowchart.

Claims (1)

[Claims] The tank of an LNG ship filled with liquefied natural gas is cooled by spraying liquefied natural gas, the gas amount of which is adjusted by the valve opening of the spray valve, from a spray nozzle, and the tank pressure information and spray valve opening/closing status information of this tank are collected. , spray nozzle pressure information,
A small computer calculates the optimal spray amount and time of gas to be sprayed from the above spray nozzle from the tank temperature information and ship speed information, and based on the calculation results, the operation time of the spray pump that pumps up the liquefied natural gas in the tank and sends it to the spray nozzle side. and a tank cooling method during a voyage in an LNG ship, characterized in that the opening degree of the spray valve is controlled on a daily basis.