JP5276475B2 - Liquefied gas carrier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the viscosity of fuel oil and promptly supply fuel oil of required viscosity. <P>SOLUTION: This liquefied gas carrying vessel includes: a heating part 11 provided in a supply line 2 for supplying fuel oil to a boiler 14 and heating the fuel oil made to flow in the supply line 2 to adjust the viscosity; a viscosity measuring instrument 12 for measuring the viscosity of the heated fuel oil; a fuel control valve 13 for controlling the flow rate of the fuel oil made to flow in the boiler 14; a first instruction value calculation part 16 for calculating a first instruction value to adjust the heat quantity to be added in the heating part 11 based on the measured viscosity by the viscosity measuring instrument 12 and target viscosity; a second instruction value calculation part 17 for calculating a second instruction value to adjust the heat quantity to be added in the heating part 11 based on a valve opening of the fuel control valve 13; and a control amount calculation part 18 for calculating a third instruction value based on the first and second instruction values and applying the third instruction value as control amount to the heating part 11. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a liquefied gas carrier.

  Conventionally, for example, in a liquefied gas carrier ship that transports liquefied natural gas in a cold state, steam is generated by burning fuel with a boiler, and this steam is used as a propulsive force. As fuel for generating the steam, boil-off gas and fuel oil (referred to as heavy oil or HFO) generated by heat entering from the outside of the tank that stores the liquefied gas are used.

JP 7-317614 A

  By the way, when the fuel combusted in a boiler is fuel oil, it adjusts so that the viscosity of the fuel oil to flow in may become target viscosity. Conventionally, as shown in FIG. 3, the heating unit is controlled based on the difference between the viscosity measured by the viscosity meter and the target viscosity, and the fuel oil heated by the heating unit is adjusted by the fuel control valve. The flow rate of fuel flows into the boiler.

However, in the conventional method, the heating of the fuel oil heater is adjusted so that the viscosity of the fuel oil becomes the target viscosity, but the change rate of the viscosity is lower than the fluctuation rate of the fuel amount used in the boiler. There is a problem that fuel oil having a desired viscosity state cannot be obtained promptly according to the fluctuation speed of the fuel amount.
Further, since the change speed of the fuel oil viscosity is significantly different between the case where the main engine side is operating normally and the case where the main engine load fluctuates rapidly, it has been difficult to always stabilize the viscosity.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a liquefied gas carrier ship that can stabilize the viscosity of fuel oil and can quickly supply fuel oil having a desired viscosity. To do.

  In order to solve the above problems, the present invention employs the following means.

  The present invention is provided in a supply line for supplying fuel oil to a boiler, heating means for adjusting the viscosity by heating the fuel oil flowing through the supply line, and the viscosity of the fuel oil after passing through the heating means A viscosity measuring means for measuring the fuel, a fuel control valve provided on the downstream side of the heating means in the supply line for controlling the flow rate of the fuel oil flowing into the boiler, and the viscosity measured by the viscosity measuring means Based on the target viscosity, the first instruction value calculation means for calculating the first instruction value for adjusting the amount of heat applied by the heating means, and the heating means based on the valve opening of the fuel control valve Second instruction value calculation means for calculating a second instruction value for adjusting the amount of heat, a third instruction value is calculated based on the first instruction value and the second instruction value, and the third instruction value is calculated. Control over the heating means Providing liquefied gas carrier, characterized in that and a control amount calculating means for providing a quantity.

  According to such a configuration, the fuel oil is heated by the heating unit to adjust the viscosity, and the viscosity is measured by the viscosity measuring unit. Based on the viscosity measured by the viscosity measuring means and the target viscosity, a first instruction value for adjusting the amount of heat applied to the fuel oil by the heating means is calculated by the first instruction value calculating means. Further, the fuel oil flowing into the boiler is controlled by adjusting the valve opening degree in the fuel control valve. Based on this valve opening, a second instruction value for adjusting the amount of heat applied to the fuel oil by the heating means is calculated by the second instruction value calculation means. Further, based on the first instruction value and the second instruction value, a third instruction value that is a control amount for the heating unit is calculated by the control amount calculation unit.

  Thus, the control amount of the heating means for controlling the viscosity of the fuel oil is calculated according to the measured viscosity and the valve opening of the fuel control valve that allows the fuel oil to flow into the boiler. Thereby, compared with the case where the heating control amount of fuel oil is calculated | required conventionally based on a viscosity, the followable | trackability of the viscosity of fuel oil can be improved and the stable fuel oil can be supplied to a boiler.

  Provided with a steam supply line that outputs steam generated by the boiler of the liquefied gas carrier ship to the downstream side, and includes a steam flow rate measuring unit that measures a flow rate of steam flowing through the steam supply line, and calculates the second indicated value The means may calculate a second indication value for adjusting the amount of heat applied in the heating means based on the steam flow rate measured by the steam flow rate measuring means and the valve opening of the fuel control valve. .

  In this way, the flow rate of the steam generated by the boiler is measured by the steam flow rate measuring means, and the second indicated value is calculated by the second indicated value calculating means based on the steam flow rate and the valve opening of the fuel control valve. Calculated. Thereby, since the steam flow rate is taken into account in the calculation of the second instruction value, the heating unit can be controlled based on the value of steam actually generated from the boiler.

The heating means of the liquefied gas carrier ship may include a steam control valve that controls the amount of heat applied to the fuel oil, and the steam control valve may adjust the amount of heat by adjusting the valve opening.
As described above, the amount of heat applied to the fuel oil is controlled by adjusting the valve opening of the steam control valve, so that the heating can be easily performed.

The boiler of the liquefied gas carrier is composed of a heavy oil combustion mode that burns the fuel oil, a gas combustion mode that burns natural gas flowing from a liquefied gas tank, and a mixed combustion that mixes and burns the fuel oil and the natural gas. Steam may be generated in any one of the modes, and the valve opening degree of the steam control valve may be controlled according to the mode.
Thus, since the valve opening degree of the steam control valve is controlled according to the combustion mode in the boiler, the heating of the fuel oil can be controlled according to the combustion mode.

The control amount calculation means of the liquefied gas carrier ship may have a parameter for determining a weight between the first instruction value and the second instruction value.
Thus, since the control amount calculation means has a parameter for determining the weighting of the first instruction value and the second instruction value, based on the weighting of the viscosity of the fuel oil and the valve opening of the fuel control valve, A control amount for heating the fuel oil can be determined.

  According to the present invention, it is possible to stabilize the viscosity of the fuel oil and to quickly supply the fuel oil having a desired viscosity.

It is a block diagram which shows an example of schematic structure around the boiler mounted in the liquefied gas carrier ship which concerns on one Embodiment of this invention. It is a figure which shows an example of the relationship between the valve opening degree of a fuel control valve and a steam control valve. It is a figure which shows schematic structure around the boiler mounted in the conventional liquefied gas carrier ship.

  Hereinafter, an embodiment of a fuel oil viscosity control device for a liquefied gas carrier according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration around a boiler mounted on a liquefied gas carrier according to the present embodiment.
In FIG. 1, a supply line 2 that supplies fuel oil to a boiler 14 includes a heating unit (heating means) 11 that reduces the viscosity of the fuel oil by heating the fuel oil, and after the viscosity is adjusted by the heating unit 11. A viscosity measuring device (viscosity measuring means) 12 for measuring the viscosity of the fuel oil is provided. In the supply line 2, a fuel control valve 13 for adjusting the flow rate of the fuel oil supplied to the boiler 14 is provided further downstream of the heating unit 11. The second steam supply line 4 that supplies steam generated in the boiler 14 to the steam turbine is provided with a steam flow measuring unit (steam flow measuring means) 15 that measures the flow rate of the circulating steam.

The heating unit 11 includes a fuel oil heater 21 and a steam control valve 20. The amount of heat given to the fuel oil in the fuel oil heater 21 is adjusted by the amount of steam supplied to the fuel oil heater 21 through the first steam supply line 3. For this reason, a steam control valve 20 for adjusting the flow rate of steam supplied to the heating unit 11 through the first steam supply line 3 is provided.
In the present embodiment, the viscosity of the fuel oil supplied to the boiler 14 is adjusted to an appropriate viscosity by adjusting the amount of heat given to the fuel oil in the fuel oil heater 21 by adjusting the opening of the steam control valve 20. adjust.

The steam control valve 20 is controlled by the fuel oil viscosity control device 1.
The fuel oil viscosity control apparatus 1 includes a first instruction value calculation unit (first instruction value calculation unit) 16, a second instruction value calculation unit (second instruction value calculation unit) 17, and a control amount calculation unit (control amount calculation). Means) 18.

  The first instruction value calculation unit 16 calculates the opening degree of the steam control valve 20 for making the viscosity measured by the viscosity measuring device 12 coincide with a preset target viscosity as a first instruction value. The instruction value is output to the control amount calculation unit 18.

  The second instruction value calculation unit 17 calculates the valve opening of the steam control valve 20 based on the valve opening of the fuel control valve 13, and outputs this valve opening as a second instruction value to the control amount calculation unit. . For example, the second instruction value calculation unit 17 has a table indicating the correspondence between the valve opening degree of the fuel control valve 13 and the control amount of the steam control valve 20 of the heating unit 11. Specifically, the second instruction value calculation unit 17 calculates the valve opening degree of the steam control valve 20 associated with the valve opening degree acquired from the fuel control valve 13 by referring to the table it has, Is the second indicated value '.

Moreover, the 2nd instruction value calculation part 17 has a table which matches the steam flow rate measured by the steam flow rate measurement part 15 and the valve opening degree of the steam control valve 20, and according to the measured steam flow rate. The valve opening degree of the steam control valve 20 is calculated, and this is set as the second instruction value ″. Further, the second instruction value calculation unit 17 calculates the second instruction value by adding the second instruction value ′ and the second instruction value ″, and outputs the second instruction value to the control amount calculation unit 18. To do.
In addition, when calculating a 2nd instruction value, it is good also as giving weighting and adding to 2nd instruction value 'and 2nd instruction value''.

  The control amount calculation unit 18 calculates a third instruction value based on the first instruction value and the second instruction value, and uses the third instruction value as the final valve opening (control amount) of the steam control valve 20. Output. Further, the control amount calculation unit 18 has a parameter that determines the weighting of the first instruction value and the second instruction value. For example, a gain of 0.8 is given to the second instruction value, and the result of adding this and the first instruction value is set as the third instruction value.

  In the above configuration, the boiler 14 is a mixed combustion type boiler that can use both fuel oil and boil-off gas as fuel, and is provided with a mode according to the fuel used. Specifically, there are a heavy oil exclusive combustion mode that uses only fuel oil in the boiler 14, a gas exclusive combustion mode that uses only gas in the boiler 14, and a mixed combustion mode that uses both fuel oil and gas.

In the heavy oil combustion mode and the mixed combustion mode, the fuel oil that has passed through the fuel control valve 13 flows into the boiler 14. When the boiler 14 is in a gas-only firing mode that does not use fuel oil, the fuel oil that has passed through the fuel control valve 13 is recirculated (recirculated) through a circulation path (not shown), and the fuel oil flows into the boiler 14. For example, it is returned to the fuel oil heater.
Thus, even in the gas-only firing mode, the fuel control valve 13 and the like are controlled in order to keep the fuel oil at a stable viscosity.

Next, the operation of the fuel oil viscosity control apparatus 1 according to this embodiment will be described with reference to FIG.
In the following description, a case where only the fuel oil is burned as fuel in the heavy oil exclusive combustion mode will be described, and then a case where only the liquefied natural gas is burned as fuel in the gas exclusive combustion mode will be described.

  First, when the fuel oil is burned as fuel in the heavy oil exclusive combustion mode, the opening degree of the boiler 14 is adjusted by the steam control valve 20 in the heating unit 11 (the adjustment of the opening degree of the valve will be described later). It is supplied to the fuel oil heater 21. In the fuel oil heater 21, a heat amount corresponding to the amount of steam controlled by the steam control valve 20 is given to the fuel oil, and the heated fuel oil is output. The viscosity of the heated fuel oil is measured by the viscosity measuring device 12, and this measured value is output to the first indicated value calculation unit 16.

In the first instruction value calculation unit 16, the measurement result of the viscosity is compared with the target viscosity, and the first instruction value for controlling the heating amount of the heating unit 11 so that the viscosity approaches the target viscosity is the control amount calculation unit 18. Is output.
Moreover, the fuel control valve 13 located on the downstream side of the heating unit 11 is controlled according to the load of the boiler 14 and the valve opening degree is adjusted. Information on the adjusted valve opening is output to the second instruction value calculator 17. Further, when the fuel oil that has passed through the fuel control valve 13 flows into the boiler 14, the fuel oil is burned in the boiler 14 and steam is generated. The generated steam is supplied to the steam turbine through the second steam supply line 4. Further, the flow rate of the steam flowing through the second steam supply line 4 is measured by the steam flow rate measuring unit 15, and this measured value is output to the second indicated value calculating unit 17.

  The second instruction value calculation unit 17 has a table associating the valve opening degrees of the fuel control valve 13 and the steam control valve 20 as shown by line 1 in FIG. Based on the valve opening degree acquired from the control valve 13, the value of the steam control valve 20 is referred to, and this is set as the second instruction value '. Similarly, the second instruction value calculation unit 17 has a table in which the steam flow rate and the steam control valve 20 are associated with each other, and when information on the steam flow rate is acquired, the steam control valve 20 associated therewith is acquired. Is the second instruction value ″. Further, the second instruction value calculation unit 17 adjusts the amount of steam in the heating unit 11 by giving and adding a preset weight to the second instruction value 'and the second instruction value ″. The second instruction value is calculated and output to the control amount calculation unit 18. The control amount calculation unit 18 calculates a third instruction value for determining the heating amount of the heating unit 11 by giving a preset weight to the first instruction value and the second instruction value and adding them. And output to the heating unit 11.

  In addition, the table referred in the 2nd instruction | indication value calculation part 17 is the same table as the case of the heavy oil exclusive combustion mode also about the mixed combustion mode which mixes and burns fuel oil and boil-off gas.

  Next, the case where the boiler 14 burns only liquefied natural gas as fuel in the gas-only firing mode will be described, but different parts from the case of the heavy oil-only firing mode will be mainly described.

  When the boiler 14 is in the gas-only firing mode, the fuel oil is not used as the fuel to be burned in the boiler 14, but the fuel oil heater is used so that the fuel oil is recirculated (recirculated) in order to maintain the viscosity of the fuel oil. Return the fuel oil to the 21 side. At this time, the fuel control valve 13 is maintained at a constant opening, and the fuel oil that has passed through the fuel control valve 13 is returned to the fuel oil heater 21.

  Further, information on the valve opening degree of the fuel control valve 13 is output to the second instruction value calculation unit 17. In the second instruction value calculation unit 17, a table as shown in line 2 of FIG. In the case of the gas-only firing mode, the opening degree of the fuel control valve 13 is kept constant, and the opening degree of the steam control valve 20 corresponding to the opening degree of the fuel control valve 13 is set to 0%. (Second indication value '). In addition, the valve opening degree of the steam control valve 20 corresponding to the steam flow rate is also set to 0 percent (second instruction value ″). A second instruction value is calculated from the second instruction value ′ and the second instruction value ″.

In the control amount calculation unit 18, the third instruction value is calculated from the first instruction value and the second instruction value, and is output to the heating unit 11. The steam control valve 20 is adjusted based on the third instruction value, and the fuel oil is heated in the fuel oil heater 21 by the adjusted amount of steam.
Thus, in the case of the gas-only firing mode, the third control value is calculated from the first instruction value based on the viscosity measured by the viscosity measuring device 12 and the second instruction value. Thereby, in the case of the gas-only firing mode, the viscosity can be stabilized by circulating the fuel oil.

  As described above, according to the fuel oil viscosity control apparatus for a liquefied gas carrier according to this embodiment, the fuel oil is heated by the heating unit 11 to adjust the viscosity, and the viscosity is measured by the viscosity measuring device 12. The From the viscosity measured by the viscosity measuring instrument 12 and the target viscosity, a first instruction value for adjusting the amount of heat applied to the fuel oil by the heating unit 11 is calculated by the first instruction value calculation unit 16. Further, the fuel oil flowing into the boiler 14 is controlled by adjusting the valve opening degree in the fuel control valve 13. Further, the steam flow rate acquired from the steam flow rate measurement unit 15 that measures the steam generated from the boiler 14 is output to the second instruction value calculation unit 17. In the second instruction value calculation unit 17, a second instruction value for adjusting the amount of heat applied to the fuel oil by the heating unit 11 is calculated based on the valve opening of the fuel control valve 13 and the steam flow rate. Furthermore, based on the first instruction value and the second instruction value, a third instruction value that is a control amount for the heating unit 11 is calculated by the control amount calculation unit 18.

  As described above, the control amount of the heating unit 11 for controlling the viscosity of the fuel oil includes the measured viscosity, the valve opening degree of the fuel control valve 13 for introducing the fuel oil determined according to the load of the boiler 14, And it is calculated based on the steam flow rate measured by the steam flow rate measuring unit 15. As a result, in addition to controlling the viscosity by feedback control of the information on the viscosity of the fuel oil that has been conventionally performed, information on the fuel control valve controlled according to the load on the boiler and the flow rate of the steam generated from the boiler Since feedforward control is performed based on the information, it is possible to improve the followability of viscosity control.

  Further, even in the case of the gas-only firing mode, the viscosity can be stabilized in order to adjust and recirculate the fuel control valve.

  Moreover, since the 2nd instruction | indication value calculation part 17 changes the adjustment of the valve opening degree of the steam control valve 20 according to the combustion mode of the boiler 14, it maintains the viscosity of the fuel supplied to the boiler 14 at desired viscosity. be able to.

  In addition, in the fuel oil viscosity control apparatus of the liquefied gas carrier ship which concerns on this embodiment, although the heating part 11 was supposed to heat based on a vapor | steam, it is not limited to this. For example, the heating unit 11 may include fuel, and the fuel oil heater 21 may heat the fuel oil with heat generated by burning the fuel.

  Moreover, in the 2nd instruction value calculation part 17 of the fuel oil viscosity control apparatus 1 which concerns on this embodiment, although FIG. 2 was shown as a table which shows the valve opening degree of the steam control valve 20 with respect to the valve opening degree of the fuel control valve 13, FIG. However, the present invention is not limited to this. For example, it may be a table in which the curve indicated by line 1 shows a steeper curve.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

DESCRIPTION OF SYMBOLS 1 Fuel oil viscosity control apparatus 2 Supply line 3 1st steam supply line 4 2nd steam supply line 11 Heating part 12 Viscosity measuring device 13 Fuel control valve 14 Boiler 15 Steam flow rate measurement part 16 1st instruction value calculation part 17 2nd instruction Value calculation unit 18 Control amount calculation unit 20 Steam control valve 21 Fuel oil heater

Claims (5)

Heating means provided in a supply line for supplying fuel oil to the boiler, and adjusting the viscosity by heating the fuel oil flowing through the supply line;
Viscosity measuring means for measuring the viscosity of the fuel oil after passing through the heating means;
A fuel control valve that is provided downstream of the heating means in the supply line and controls the flow rate of fuel oil flowing into the boiler;
First instruction value calculating means for calculating a first instruction value for adjusting the amount of heat applied in the heating means based on the viscosity measured by the viscosity measuring means and the target viscosity;
Second instruction value calculation means for calculating a second instruction value for adjusting the amount of heat applied in the heating means based on the valve opening of the fuel control valve;
And a control amount calculating means for calculating a third instruction value based on the first instruction value and the second instruction value, and providing the third instruction value as a control amount to the heating means. Liquefied gas carrier. Provided in a steam supply line that outputs steam generated by the boiler downstream, and includes a steam flow rate measuring unit that measures a flow rate of steam flowing through the steam supply line;
The second instruction value calculating means calculates a second instruction value for adjusting the amount of heat applied in the heating means based on the steam flow rate measured by the steam flow rate measuring means and the valve opening of the fuel control valve. The liquefied gas carrier according to claim 1, wherein the liquefied gas carrier is calculated. The heating means includes a steam control valve that controls the amount of heat applied to the fuel oil,
The liquefied gas carrier according to claim 1 or 2, wherein the steam control valve adjusts a heat amount by adjusting a valve opening degree. The boiler is one of a heavy oil combustion mode for burning the fuel oil, a gas combustion mode for burning natural gas flowing from a liquefied gas tank, and a mixed combustion mode for mixing and burning the fuel oil and the natural gas. Or steam in one mode,
The liquefied gas carrier according to any one of claims 1 to 3, wherein the steam control valve has a valve opening controlled in accordance with the mode.   The said control amount calculation means has a parameter which determines the weight of the said 1st instruction | indication value and the said 2nd instruction | indication value, The one in any one of Claims 1-4 characterized by the above-mentioned. Liquefied gas carrier.

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