JPH07149284A - Boil-off gas line in lng carrier - Google Patents

Abstract

PURPOSE:To shorten inboard piping (a duplex pipe) by improving arrangement of a gas hood in a gas line to supply boil-off gas generated in an LNG storage tank to an engine of a carrier as fuel, and shortening an inboard gas line. CONSTITUTION:A gas pipe 1 of boil-off gas generated in an LNG storage tank is arranged along an upper deck 6, on the one hand, since a gas hood 7 is installed outside of a cabin just above a bioler 4 on a second deck 12, inboard piping (a duplex pipe 3a) can be arranged only between the gas hood 7 and the bolier 4, so that the duplex pipe 3a can be shortened. A flow rate adjusting valve 5 for the boil-off gas and an engine room 10 are shown.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boil-off gas line of an LNG carrier, and more particularly to a gas hood arrangement in the boil-off gas line.

[0002]

2. Description of the Related Art In general, natural gas (LNG) carriers are provided with measures to prevent the gas (boil-off gas) vaporized from the LNG storage tank from leaking into the ship, and boil-off gas is used as fuel for engines of LNG carriers. In this case, the LNG is transferred through the outside of the ship as much as possible, and a double pipe is used in the engine room to prevent the LNG from leaking into the ship.

FIGS. 6 to 10 show a conventional boil-off gas LNG.
The boil-off gas line when used as a fuel for the engine of the carrier is shown. Two boilers 4 installed in the engine room 10 of the LNG carrier 20 are connected to the boil-off gas pipe (hereinafter referred to as “boil-off gas pipe”). Boil-off gas generated in an LNG storage tank (not shown) is supplied through a gas pipe 1).

Here, the gas pipe 1 is penetrated and assembled at the upper part of the engine room 10. In addition, since the upper deck 6 has a camber structure and the aggregate 6a is provided inside the ship (see FIG. 9), the gas pipe has a double structure (in terms of safety, the gas pipe has a double structure). Is installed in a portion where it is difficult to install the gas duct 2, and the tip thereof is connected to the boiler 4 through the gas hood 7 through the double pipe 3 on the inlet side. A valve 5 is provided on the boiler side to control the flow rate in the middle, but since it is difficult to connect the valve 5 and the double pipe, the part before and after the inlet and outlet of the valve 5 is usually a single pipe 1a (see FIG. 8). ), The portion of the single pipe 1a and the valve 5 are covered with a gas hood 7.

The outlet side of the valve 5 and the boiler 4 are connected by a double pipe 3a on the outlet side. Further, a fan 8 is provided for sucking and discharging the leaked gas inside the gas duct 2, between the inner and outer pipes of the double tubes 3, 3a and inside the gas hood 7, and each of these members is provided. The leaked gas from the ship is discharged outside the ship without leaking into the ship. Therefore, the inside of the gas duct 2, the space between the inner and outer pipes of the double pipes 3 and 3a, and the inside of the gas hood 7 are always kept in a negative pressure state. 6 to 10, reference numeral 9 is a deck, reference numeral 11 is a chimney, reference numeral 12 is a second deck, and reference numeral 13 is a third deck.

[0006]

By the way, in the prior art as described above, since the gas hood is provided in the engine room, in order to guide the boil-off gas to the gas hood, a gas duct or a double pipe on the inlet side is provided. Is required. This leads to an increase in man-hours, and maintenance and maintenance after operation is troublesome. Also, if gas leakage is found inside the double pipe, the outer pipe of the double pipe is joined by welding at the sleeve, so check and repair the inner pipe of the double pipe (main building). It's not easy.

Further, since the pipe is constructed so as to be drawn into the ship from the upper deck avoiding the living area through the gas duct, a long double pipe (for example, 10 m) is required, which is disadvantageous in terms of cost. There is a problem. The present invention is intended to solve such a problem, and by providing the gas hood outside the cabin directly above the engine, the double pipe on the inlet side can be omitted and the double pipe on the outlet side can be shortened. Made possible, LN
The purpose is to provide a boil-off gas line in a G carrier.

[0008]

In order to achieve the above object, a boil-off gas line in an LNG carrier of the present invention is a boil-off gas line in an LNG carrier for supplying boil-off gas generated in an LNG storage tank to an engine, A boil-off gas pipe having an upstream end connected to the LNG storage tank and arranged along the upper deck of the LNG carrier, a flow rate adjusting valve connected to a downstream end of the boil-off gas pipe, and the same valve. It has a gas hood covering the above and a double pipe connecting the outlet side of the valve and the engine, and the gas hood is located outside the ship just above the engine in order to shorten the double pipe. It is characterized by being installed in.

[0009]

In the boil-off gas line of the LNG carrier of the present invention described above, since the gas hood covering the valve is installed outside the ship just above the engine, the double pipe on the inlet side of the boil-off gas line is omitted and It is possible to reduce the length of the double pipe on the indoor side, that is, on the outlet side.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A boil-off gas line in an LNG carrier as an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing the center cross section of the engine room, and FIG. 2 is a plan view on the second deck. FIG. 3, FIG. 3 is a plan sectional view thereof, FIG. 4 is a schematic front view thereof, and FIG. 5 is a side view showing the LNG carrier together with the LNG carrier. 1 to 5
The same reference numerals as those in FIGS. 6 to 10 indicate substantially the same members.

In this embodiment, the engine room 10 of the LNG carrier 20 is also used.
Two boilers 4 are installed in each boiler, and each boiler 4 has an LN
A single gas pipe 1 having an upstream end connected to the LNG storage tank is arranged on the upper deck 6 in order to supply boil-off gas generated in the G storage tank (not shown) as fuel. However, in the case of this embodiment, unlike the above-mentioned conventional example,
The gas hood 7 is on the second deck 12 just above the boiler 4.
It is installed outside the upper boat. Inside the gas hood 7, a flow rate adjusting valve 5 connected to the downstream end of the gas pipe is arranged. And valve 5
A double pipe 3a on the outlet side is provided between the and the boiler 4 as in the case of the conventional example.

In the above structure, the boil-off gas passes through the gas pipe 1, the valve 5, and the double pipe 3a on the outlet side.
Through to the boiler 4. In this case, since the gas hood 7 is located outside the ship, the single gas pipe 1 can be used from the LNG storage tank to the gas hood 7, and the double pipe 3 on the inlet side in the conventional example is not required. Also,
The gas hood 7 is directly above the boiler 4, that is, the boiler 4
Since it is installed very close to, the double pipe 3a on the outlet side can be shortened. Further, the gas duct in the conventional example is not required.

Therefore, the double pipe, which is difficult to work and install, can be greatly shortened, and the gas duct can be omitted, which can greatly reduce the construction cost of the LNG carrier. Furthermore, the shortening of the double pipe makes it easier to investigate and repair gas leaks, and the exhaust fan capacity for exhausting air between the inner and outer pipes of the double pipe can be small. The advantages of

[0014]

As described in detail above, according to the boil-off gas line in the LNG carrier of the present invention, the following effects and advantages can be obtained. (1) The double pipe, which is difficult to work and install, can be significantly shortened, and the construction cost of the LNG carrier can be reduced. (2) By shortening the double pipe, it becomes easy to investigate and repair gas leaks, and maintenance costs can be reduced. (3) The capacity of the double-pipe exhaust fan can be reduced because the volume of the double-pipe is reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a boil-off gas line in an LNG carrier as one embodiment of the present invention together with a central section of an engine room.

FIG. 2 is a plan view on the second deck.

FIG. 3 is a plan sectional view of the same.

FIG. 4 is a schematic front view of the same.

FIG. 5 is a schematic side view shown together with the LNG carrier.

FIG. 6 is a side sectional view showing a boil-off gas line in a conventional LNG carrier together with a central section of an engine room.

FIG. 7 is a plan view on the second deck.

8 is a cross-sectional view taken along the line AA of FIG.

FIG. 9 is a schematic front view of the same.

FIG. 10 is a schematic side view showing the same LNG carrier together.

[Explanation of symbols]

 1 Boil-off gas pipe 3 Double pipe on the inlet side 3a Double pipe on the outlet side 4 Boiler 5 Valve 6 Upper deck 7 Gas hood 8 Fan 10 Engine room 11 Chimney 12 Second deck 13 Third deck

Claims (1)

[Claims] 1. A boil-off gas line in an LNG carrier for supplying boil-off gas generated in an LNG storage tank to an engine, wherein the upstream end is connected to the LNG storage tank and the LNG storage tank is connected to the LNG storage tank.
A boil-off gas pipe arranged along the upper deck of the NG carrier, a valve for adjusting the flow rate connected to the downstream end of the boil-off gas pipe, a gas hood covering the valve, an outlet side of the valve and the above An LNG carrier, comprising a double pipe for connecting to an engine, wherein the gas hood is installed outside the ship just above the engine in order to shorten the double pipe. Boil-off gas line in.