KR102241817B1 - Gas Treatment System and Vessel having the same - Google Patents

Abstract

A gas processing system according to an embodiment of the present invention includes: an boil-off gas compressor that supplies boil-off gas generated in a liquefied gas storage tank to a customer, and is provided in a plurality of boil-off gas compressors; And a buffer tank provided downstream of the boil-off gas compressor, wherein the boil-off gas compressor is controlled in a state in which at least one of the boil-off gas is stopped or in a standby state in which compression of the boil-off gas is not implemented, the buffer tank, the plurality of It is characterized in that the boil-off gas discharged at different pressures from the boil-off gas compressor is temporarily stored to have a preset pressure required by the customer and then supplied to the customer.

Description

Gas Treatment System and Vessel having the same

The present invention relates to a gas treatment system and a ship including the same.

According to recent technological developments, liquefied gases such as Liquefied Natural Gas and Liquefied Petroleum Gas have been widely used in place of gasoline or diesel.

Liquefied natural gas is liquefied by cooling methane obtained by refining natural gas collected from a gas field. It is a colorless and transparent liquid that contains little pollutants and has high calorific value, making it an excellent fuel. Liquefied petroleum gas, on the other hand, is a fuel made into a liquid by compressing gas containing propane (C3H8) and butane (C4H10) as main components from oil fields together with petroleum at room temperature. Liquefied petroleum gas, like liquefied natural gas, is colorless and odorless, and is widely used as fuel for home, business, industrial, and automobiles.

Such liquefied gas is stored in a liquefied gas storage tank installed on the ground or in a liquefied gas storage tank provided on a ship, which is a transportation means for sailing the ocean, and the liquefied natural gas is stored in a volume of 1/600 by liquefaction. The volume of liquefied petroleum gas is reduced to 1/260 of propane and 1/230 of butane by liquefaction, which has the advantage of high storage efficiency. The temperature and pressure required to drive the engine using the liquefied gas as fuel may be different from the state of the liquefied gas stored in the tank.

In addition, when the LNG is stored in a liquid state, some LNG is vaporized as heat permeation occurs into the tank to generate boil off gas (BOG).This boil-off gas can cause problems in the liquefied gas treatment system. We tried to solve the problem by discharging the boil-off gas to the outside and burning it (previously, the boil-off gas was simply discharged to the outside to remove the risk of damage to the tank by lowering the tank pressure). Is causing problems.

Accordingly, in recent years, as a technology for efficiently treating boil-off gas, research and development on utilization methods such as recondensing the generated boil-off gas through liquefied gas, liquefying it, and supplying it to the engine are being actively conducted.

The present invention was created to improve the conventional technology, and an object of the present invention is to provide a gas treatment system for effectively supplying liquefied gas and/or boil-off gas from a liquefied gas storage tank to a customer, and a ship including the same. .

The gas treatment system according to the present invention includes: an boil-off gas compressor that supplies boil-off gas generated in a liquefied gas storage tank to a consumer, and is provided in a plurality of boil-off gas compressors that are built in parallel with each other; And a buffer tank provided downstream of the boil-off gas compressor, wherein the boil-off gas compressor is controlled in a state in which at least one of the boil-off gas is stopped or in a standby state in which compression of the boil-off gas is not implemented, the buffer tank, the plurality of It is characterized in that the boil-off gas discharged at different pressures from the boil-off gas compressor is temporarily stored to have a preset pressure required by the customer and then supplied to the customer.

Specifically, a boil-off gas supply line connecting the liquefied gas storage tank and the customer, and including the boil-off gas compressor; A bypass line for bypassing from an upstream to a downstream side of the buffer tank on the boil-off gas supply line; And controlling at least one of the boil-off gas compressors in an operation stop state or a standby state in which no compression of the boil-off gas is implemented according to the amount of boil-off gas generated in the liquefied gas storage tank, but the boil-off gas generated in the liquefied gas storage tank Further comprising a control unit for controlling the boil-off gas flow downstream of the boil-off gas compressor according to the generation amount, wherein the control unit is discharged from the boil-off gas compressor when the boil-off gas generation amount generated in the liquefied gas storage tank is greater than or equal to a preset generation amount. Boil-off gas is controlled to flow to the bypass line, and when the amount of boil-off gas generated in the liquefied gas storage tank is less than a preset amount, the boil-off gas discharged from the boil-off gas compressor can be controlled to flow to the buffer tank. have.

Specifically, the preset generation amount is an amount of boil-off gas introduced into the boil-off gas compressor at an inefficiency point of the boil-off gas compressor, and the inefficiency point of the boil-off gas compressor is a ratio of the amount of power consumption to the flow rate of the boil-off gas compressor, Even if the flow rate supplied to the boil-off gas compressor decreases, power consumption may not decrease.

Specifically, the load amount at the point of inefficiency of the boil-off gas compressor may be a flow rate of 20 to 40% of the flow rate at which the boil-off gas compressor has a maximum load.

Specifically, the boil-off gas compressor is provided with a component compressor in which a four-stage or five-stage piston is connected in series, and the component compressors are provided with four first to fourth boil-off gas compressors and may be connected in parallel with each other.

Specifically, further comprising boil-off gas first to fourth supply lines connecting the liquefied gas storage tank and the customer, and having the first to fourth boil-off gas compressors, and on the first to fourth supply lines Upstream and downstream of the first to fourth boil-off gas compressors may be provided with an upstream common line and a downstream common line that are formed in common.

Specifically, the buffer tank may be provided on the downstream common line.

Specifically, the boil-off gas compressor may be a standard high pressure compressor.

Specifically, it may be a ship comprising the gas treatment system.

The gas treatment system and the ship including the same according to the present invention have an effect of increasing system stability and reliability by effectively supplying liquefied gas and/or boil-off gas from a liquefied gas storage tank to a customer.

1 is a conceptual diagram of a ship including a gas treatment system according to a first embodiment of the present invention.
2 is a conceptual diagram of a ship including a gas treatment system according to a second embodiment of the present invention.
3 is a conceptual diagram of a ship including a gas treatment system according to a third embodiment of the present invention.
4 is a conceptual diagram of a ship including a gas treatment system according to a fourth embodiment of the present invention.
5 is a conceptual diagram of a ship including a gas treatment system according to a fifth embodiment of the present invention.
6 is a conceptual diagram of a ship including a gas treatment system according to a sixth embodiment of the present invention.
7 is a conceptual diagram of a ship including a gas treatment system according to a seventh embodiment of the present invention.
8 is a conceptual diagram of a ship including a gas treatment system according to an eighth embodiment of the present invention.
9 is a conceptual diagram of a ship including a gas treatment system according to a ninth embodiment of the present invention.
10 is a conceptual diagram of a ship including a gas treatment system according to a tenth embodiment of the present invention.
11 is a conceptual diagram of a ship including a gas treatment system according to an eleventh embodiment of the present invention.
12 is a graph of power consumption versus flow rate of the boil-off gas compressor according to an embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments associated with the accompanying drawings. In adding reference numerals to elements of each drawing in the present specification, it should be noted that, even though they are indicated on different drawings, only the same elements are to have the same number as possible. In addition, in describing the present invention, when it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, the liquefied gas may be LPG, LNG, ethane, etc., for example, may refer to LNG (Liquefied Natural Gas), and the boil-off gas may refer to BOG (Boil Off Gas), such as naturally vaporized LNG.

Liquefied gas may be referred to regardless of state change, such as a liquid state, a gas state, a liquid and gas mixture state, a supercooled state, and a supercritical state, and it is noted that the boil-off gas is the same. In addition, it is apparent that the present invention is not limited to liquefied gas, and may be a liquefied gas treatment system and/or a boil-off gas treatment system, and the systems of each of the drawings to be implemented below may be applied to each other. In addition, the mixed fluid described below may be a mixed boil-off gas or a fluid containing at least some liquid phases.

In addition, it goes without saying that the embodiments of the gas treatment system 1 of the present invention may be configured in combination with each other, and the addition of the respective components may be made crosswise with each other. And the gas treatment system 1 according to the embodiment of the present invention may be mounted on a hull (not shown), and at this time, the ship 100 may be a ship such as an LNG carrier or a container carrier, and is limited thereto. It doesn't work.

The standby state described in the present specification refers to a state in which compression of the boil-off gas is not implemented and a state in which the boil-off gas compressor is in an operating standby state or an operation stop state.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a ship including a gas treatment system according to a first embodiment of the present invention.

As shown in Figure 1, the gas treatment system 1 according to the first embodiment of the present invention, a liquefied gas storage tank 10, a boosting pump 20, a forced vaporizer 21, a preheater 30, It includes a standard high-pressure boil-off gas compressor 40, a propulsion engine 50, and a control unit (not shown).

Hereinafter, a gas treatment system 1 according to a first embodiment of the present invention will be described with reference to FIG. 1.

Before describing the individual configurations of the gas treatment system 1 according to the embodiment of the present invention, basic flow paths organically connecting the individual components will be described. Here, the flow path may be a line through which a fluid flows, and is not limited thereto, and any configuration in which a fluid flows is possible.

In an embodiment of the present invention, a forced vaporization gas supply line L1, a boil-off gas supply line L2, and a first bypass line BL1 may be further included. Valves (not shown) capable of adjusting the opening degree may be installed in each line, and the supply amount of the boil-off gas may be controlled according to the adjustment of the opening degree of each valve.

The forced vaporization gas supply line (L1) connects the liquefied gas storage tank 10 and the boil-off gas supply line (L2), and includes a boosting pump 20 and a forced vaporizer 21 to provide a liquefied gas storage tank (10). The liquefied gas stored in may be forcibly vaporized and supplied to the boil-off gas supply line (L2).

The boil-off gas supply line L2 connects the liquefied gas storage tank 10 and the propulsion engine 50, and includes a first preheater 30 and a standard high-pressure boil-off gas compressor 40, and the liquefied gas storage tank ( The boil-off gas generated from 10) can be supplied to the propulsion engine 50. At this time, the boil-off gas supply line L2 may connect the first to fifth boil-off gas compressors 41 to 45 in parallel, and a line provided with each of the first to fifth boil-off gas compressors 41 to 45 May be referred to as first to fifth supply lines (not shown).

Since the boil-off gas supply line L2 is formed in common upstream and downstream of the first to fifth supply lines, the upstream of the first to fifth supply lines may be referred to as an upstream common line, and the first to fifth supply lines. The downstream of the supply line can be referred to as a downstream common line.

The first bypass line BL1 is branched from the downstream of the standard high-pressure boil-off gas compressor 40 on the boil-off gas supply line L2 and is connected to the upstream of the first preheater 30, and the first control valve B1 By providing, the boil-off gas supplied from the liquefied gas storage tank 10 and compressed by the standard high-pressure boil-off gas compressor 40 may be supplied to the upstream of the first preheater 30 again. Here, the first control valve B1 may be connected to the control unit by wire or wirelessly to receive a command for adjusting the opening degree of the control unit.

Hereinafter, individual components that are organically formed by the above-described lines L1 to L3 and BL1 to implement the gas treatment system 1 will be described.

The liquefied gas storage tank 10 stores liquefied gas to be supplied to the propulsion engine 50. The liquefied gas storage tank 10 should store the liquefied gas in a liquid state, and at this time, the liquefied gas storage tank 10 may have a pressure tank shape.

Here, the liquefied gas storage tank 10 is disposed inside the hull (not shown) and may be formed in front of the engine room (not shown) as an example. In addition, the type of the liquefied gas storage tank 10 is not particularly limited in various forms such as a membrane-type tank, but not limited thereto, and a stand-alone tank, for example.

The boosting pump 20 may supply the liquefied gas stored in the liquefied gas storage tank 10 to the forced vaporizer 21 by being provided on the forced vaporization gas supply line L1.

The boosting pump 20 supplies the liquefied gas stored in the liquefied gas storage tank 10 to the forced vaporizer 21 or liquefied supplied to the forced vaporizer 21 according to the required amount of fuel required by the propulsion engine 50 The supply of gas can be stopped.

Here, the boosting pump 20 may be provided inside or outside the liquefied gas storage tank 10, and may be, for example, a centrifugal pump.

The forced vaporizer 21 is provided on the forced vaporization gas supply line L1, receives the liquefied gas stored in the liquefied gas storage tank 10 from the boosting pump 20 and forcibly vaporizes the standard high-pressure boil-off gas compressor 40 ).

The forced vaporizer 21 may receive steam supplied from a boiler (not shown) as a heat source, and exchange the steam and the boil-off gas generated in the liquefied gas storage tank 10 to exchange liquid liquefied gas. It can be phase-changed with forced vaporization evaporation gas in the gas phase. Here, it goes without saying that various heat sources other than steam may be used as the heat source used in the forced vaporizer 21.

At this time, the liquid liquefied gas is approximately minus 163 degrees, and the liquefied gas can be heated to a forced evaporation gas having a minus 40 degrees to -20 degrees Celsius, which causes the phase change from liquid to gaseous as described above. Accompany.

The forced vaporizer 21 may share steam with the preheater 30. Specifically, the boiler may supply steam to the forced vaporizer 21 as well as to the preheater 30.

The preheater 30 is disposed upstream of the standard high-pressure boil-off gas compressor 40 on the boil-off gas supply line L2, and preheats the boil-off gas discharged from the liquefied gas storage tank 10 to preheat the standard high-pressure boil-off gas compressor 40. ).

The preheater 30 may receive steam supplied from the boiler as a heat source, and heat exchange between the steam and the boil-off gas generated in the liquefied gas storage tank 10 to reduce the boil-off gas of about -110 degrees to -40 degrees to -40 degrees. The temperature can be raised to -20 degrees below zero. Here, as a heat source used in the preheater 30, it goes without saying that various heat sources other than steam may be used.

The standard high pressure boil-off gas compressor (40; Standard High Pressure Compressor; SHP compressor) pressurizes the boil-off gas generated in the liquefied gas storage tank 10 and supplies it to the propulsion engine (50; customer), and a plurality of boil-off gas is supplied. They are provided in parallel with each other on the line L2.

In this case, the standard high-pressure boil-off gas compressor 40 may be provided as first to fifth boil-off gas compressors 41 to 45 (constituent compressors), and may be provided in parallel with each other on the boil-off gas supply line L2.

Each of the boil-off gas compressors 41-45 in the standard high-pressure boil-off gas compressor 40 is connected in series with a plurality of stages (pistons) to pressurize the boil-off gas in multiple stages. For example, the first to fifth boil-off gas compressors 41 to 45 have a structure in which four or five pistons are connected in series, that is, a structure connected in series in four or five stages, and the boil-off gas is 150 at the final stage. It can be compressed to 350bar (preferably about 300bar) and discharged to be supplied to the propulsion engine 50. At this time, the fifth boil-off gas compressor 45 may serve as a spare compressor.

Here, the first bypass line BL1 may be branched between the first boil-off gas compressor 41 and the propulsion engine 50 on the boil-off gas supply line L2 to be supplied upstream of the preheater 30. At this time, a valve (not shown) may be provided at the branch point on the boil-off gas supply line L2, and the valve is a flow rate of boil-off gas supplied to the propulsion engine 50 or boil-off gas supplied to the preheater 30 It can control the flow rate of, and it can be a three-way valve.

The first to fifth boil-off gas compressors 41 to 45 may be provided with an boil-off gas cooler (not shown) between the stages. When the boil-off gas is pressurized by the first to fifth boil-off gas compressors 41 to 45, the temperature of the boil-off gas may also be increased according to the pressure increase, and thus the temperature of the boil-off gas is lowered again using the boil-off gas cooler. Can give. Boil-off gas coolers may be installed in the same number as each stage of the first to fifth boil-off gas compressors (41 to 45), and each boil-off gas cooler is downstream of each stage of the first to fifth boil-off gas compressors (41 to 45). Can be provided in.

In addition, the first to fifth boil-off gas compressors 41 to 45 may be boil-off gas compressors for room temperature in which the temperature of the boil-off gas sucked from the first stage is -40 degrees to -20 degrees. To this end, a separate heating device is required at the front end of the first to fifth boil-off gas compressors 41 to 45, and a preheater 30 is provided in the embodiment of the present invention.

This preheater 30 heats the boil-off gas generated in the liquefied gas storage tank 10 to about -110 degrees below -40 degrees to -20 degrees Celsius to flow into the first to fifth boil-off gas compressors (41 to 45). I can.

Here, in the standard high-pressure boil-off gas compressor 40 (SHP compressor), the cylinder is formed in a V-shape, so that the size of the compressor itself can be significantly reduced, and thus the space occupied by the compressor can be drastically reduced.

In addition, when any one of the standard high-pressure boil-off gas compressors 40 is stopped, for example, when the first boil-off gas compressor 41 is stopped, it is controlled to an operational standby state under a preset condition, and the operational standby state is When the predetermined period is exceeded, the first boil-off gas compressor 41, which is on standby for operation, is operated to preheat the boil-off gas discharged from the first boil-off gas compressor 41 started to operate through the first bypass line BL1 ( 30) can be bypassed upstream.

The propulsion engine 50 uses boil-off gas or liquefied gas from the liquefied gas storage tank 10 as fuel. At this time, the propulsion engine 50 may be a high-pressure gas injection engine (for example, MEGI), and in the case of a MEGI engine, a boil-off gas pressurized at a high pressure of about 150 to 350 bar may be used as a fuel.

In the propulsion engine 50, as a piston (not shown) inside a cylinder (not shown) reciprocates by combustion of liquefied gas or evaporative gas, a crankshaft (not shown) connected to the piston is rotated, A propeller shaft (not shown) connected to the crankshaft can be rotated. Therefore, when the propulsion engine 50 is driven, as the propeller (not shown) connected to the propeller shaft rotates, the ship 100 may move forward or backward.

The propulsion engine 50 is a two-stroke DF engine driven by a conventional diesel cycle and may be a low-speed engine. Basically, in such a diesel cycle, air is compressed by a piston, the compressed high-temperature air is ignited by ignition fuel, and the remaining high-pressure gas is injected to cause an explosion.

At this time, the ignition fuel is HFO (Heavy Fuel Oil) or MDO (Marine Diesel Oil), and the ratio of ignition fuel and high-pressure gas is about 5:95, and the injection amount of ignition fuel can be adjusted to 5~100%. It is possible. Therefore, the ignition fuel can also be used as the driving fuel of the engine.

In other words, when the injection amount of ignition fuel is about 5%, boil-off gas (or heated liquefied gas; about 95%) is mainly used as engine driving fuel, and when the injection amount of ignition fuel is 100%, ignition is ignited as engine driving fuel. All of the fuel (oil) is used.

At this time, if the injection amount of ignition fuel is about 50% (and evaporation gas is about 50%), the ignition fuel is ignited first to produce the calorific value, and then the remaining evaporation is not mixed with the ignition fuel and flows into the engine. Gas is introduced and exploded to produce a calorific value, thereby producing a calorific value required for driving the propulsion engine 50.

In the embodiment of the present invention, it may further include a first control valve (B1) and a pressure sensor (P).

The first control valve B1 is provided on the first bypass valve BL1 and has an opening degree to supply at least a part of the boil-off gas discharged from the first boil-off gas compressor 41 to the upstream of the preheater 30. Can be opened and closed. In this case, the first control valve B1 may be connected by wire or wirelessly from the control unit to receive an opening or closing instruction.

The pressure sensor P may be provided inside or outside the liquefied gas storage tank 10, and the liquefied gas storage tank 10 that rises or falls by the boil-off gas generated in the liquefied gas storage tank 10 It can measure the internal pressure of and transmit it to the control unit. At this time, of course, the pressure sensor P may be connected to the control unit by wire or wirelessly, and the amount of boil-off gas generated may be calculated through the measured internal pressure. (Specifically, the liquefied gas storage according to the internal pressure of the liquefied gas storage tank 10 The amount of boil-off gas generated in the liquefied gas storage tank 10 can be measured through the physical properties of the boil-off gas remaining inside the tank 10.) Accordingly, the pressure sensor P is a sensor for measuring the amount of boil-off gas generated. It can be called.

The control unit may control the driving of the standard high-pressure boil-off gas compressor 40 by receiving the amount of boil-off gas generated from the pressure sensor P.

Specifically, the control unit stops any one of the standard high-pressure boil-off gas compressors 40 (for example, the first boil-off gas compressor 41) when the boil-off gas generation amount received from the pressure sensor P is less than or equal to the preset generation amount. It can be controlled to increase the load of the rest of the standard high-pressure boil-off gas compressors 40 connected in parallel (for example, the second to fourth boil-off gas compressors 42 to 44).

At this time, the control unit may control the boil-off gas compressor 41 that has been stopped to operate in a standby state under a preset condition, and operates the boil-off gas compressor 41 that is standby for operation when the standby state for operation exceeds a preset period. Thus, it is possible to control to bypass the boil-off gas discharged from the boil-off gas compressor 41 started to operate through the first bypass line BL1 to the upstream of the preheater 30.

That is, the control unit restarts the boil-off gas compressor 41 in the standby-to-operation state and the first control valve B1 when the standby-to-operation state exceeds a preset period. By opening the opening, it is possible to control the boil-off gas discharged from the boil-off gas compressor 41 in the standby state to bypass upstream of the preheater 30 through the first bypass line BL1.

Unlike this, the control unit may control to stop the operation of the boil-off gas compressor 41 waiting to be operated when the operation standby state exceeds a preset period, but this may be carried out as a separate embodiment.

Here, the preset condition refers to a condition that reaches the previous time by the amount of time it takes to operate the stopped boil-off gas compressor 41 at the time point for restarting the boil-off gas compressor 41 that has been stopped. And the time when the boil-off gas compressor 41 that has stopped operating is a time when the internal pressure of the liquefied gas storage tank 10 exceeds a preset pressure or the amount of boil-off gas generated in the liquefied gas storage tank 10 is It refers to the point in time when the set generation amount is exceeded.

As described above, in the embodiment of the present invention, when the operation standby state continues for a long time when the standard high pressure boil-off gas compressor 40 is driven, the boil-off gas is immediately transferred to the propulsion engine 50 by bypassing the boil-off gas without stopping the operation. By supplying the bypassed boil-off gas to the upstream of the preheater 30 while enabling the supply of the boil-off gas, the boil-off gas supplied back to the standard high-pressure boil-off gas compressor 40 has an appropriate temperature, and the standard high-pressure boil-off gas compressor There is an effect of increasing the driving efficiency of (40) and minimizing the construction cost.

In addition, the control unit controls whether or not the standard high-pressure boil-off gas compressor 40 is driven according to the amount of boil-off gas generated in the liquefied gas storage tank 10, but when the boil-off gas generation is less than a preset amount, the standard high-pressure boil-off gas compressor ( 40) can be controlled to shut down at least one of.

At this time, the preset generation amount is the amount of boil-off gas introduced into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40, the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

Detailed information about this will be described in detail with reference to FIG. 12.

12 is a graph of power consumption versus flow rate of the boil-off gas compressor according to an embodiment of the present invention. Here, since the fifth boil-off gas compressor 45 is the same or a spare compressor as the first to fourth boil-off gas compressors 41 to 44, it is not included in the control of the present invention, and thus is not included in the following description.

As shown in the graph of FIG. 12, when the flow rate of the first to fourth boil-off gas compressors 41 to 44 is a section greater than or equal to the inefficiency point A, the power consumption increases proportionally when the flow rate increases. This means that a lot of power consumption is required to compress the boil-off gas of a large flow rate. At this time, the inefficiency point (A) is a flow rate value determined according to the specifications and driving conditions of the first to fourth boil-off gas compressors (41 to 44), and the first to fourth boil-off gas compressors (41 to 44) are at maximum load. It is a flow rate of 20 to 40% of the flow rate with.

On the other hand, in the section where the flow rate of the boil-off gas flowing into the first to fourth boil-off gas compressors 41 to 44 is less than the inefficiency point A, power consumption does not decrease even if the flow rate decreases. This is because power consumption is consumed to prevent surging that occurs when a certain volume of boil-off gas does not flow into the first to fourth boil-off gas compressors 41 to 44.

That is, by recycling a part of the boil-off gas flowing into the first to fourth boil-off gas compressors (41 to 44), the volume of boil-off gas to the first to fourth boil-off gas compressors (41 to 44) is not less than a certain value. If it is maintained, surge can be prevented in the first to fourth boil-off gas compressors 41 to 44. In this case, separate power consumption is generated in the first to fourth boil-off gas compressors 41 to 44 in order to carry out the recycling, and due to this power consumption, the first to fourth boil-off gas compressors 41 to 44 Even if the amount of boil-off gas is reduced, power consumption does not decrease.

Therefore, in the embodiment of the present invention, when the first to fourth boil-off gas compressors 41 to 44 are driven in parallel, the characteristics of the first to fourth boil-off gas compressors 41 to 44 disclosed in FIG. 12 By using the power consumption of the first to fourth boil-off gas compressors 41 to 44 can be minimized.

That is, in the embodiment of the present invention, when the amount of boil-off gas is less than or equal to a preset value (this is the section below point A shown in FIG. 12), at least one of the first to fourth boil-off gas compressors 41 to 44 It is possible to prevent power consumption from being wasted by standby of the boil-off gas compressor and increasing the load of the remaining boil-off gas compressor.

For example, when the flow rate at the inefficiency point (A) is 50, the power consumption at that time is also 50, and the ratio (slope) of the flow rate and power consumption in the section above A is 1 (based on one boil-off gas compressor) , When the flow rate of the boil-off gas flowing into the first to fourth boil-off gas compressors 41 to 44 is 30 (when the amount of boil-off gas generated in the liquefied gas storage tank 10 is less than a preset amount) 1) Power consumption when all the first to fourth boil-off gas compressors 41 to 44 are driven and 2) when the first boil-off gas compressor 41 of the first to fourth boil-off gas compressors 41 to 44 is standby Let's compare.

In the case of 1), since all the first to fourth boil-off gas compressors 41 to 44 are driven, the power consumption is 50*4=200. However, in the case of 2), the driving of the first boil-off gas compressor 41 is stopped, and the boil-off gas is additionally supplied to the remaining second to fourth boil-off gas compressors 42 to 44 by a flow rate of 10, resulting in 60*3=180.

That is, compared to 1), the driving of 2) becomes very efficient in terms of power consumption of the boil-off gas compressor.

As described above, in an embodiment of the present invention, when the first to fourth boil-off gas compressors 41 to 44 are driven in parallel, the first to fourth boil-off gas compressors 41 By standby at least one of ~44), it is possible to minimize power consumption consumed by the first to fourth boil-off gas compressors 41 to 44.

In addition, the control unit may alternately control at least one of the first to fourth boil-off gas compressors 41 to 44 in a standby state when the amount of boil-off gas is repeatedly generated below the preset amount.

Specifically, the control unit controls at least one of the first to fourth boil-off gas compressors 41 to 44 in a standby state when the boil-off gas generation amount is less than or equal to the preset generation amount, but the boil-off gas generation amount again becomes less than or equal to the preset generation amount. In this case, the remaining one of the first to fourth boil-off gas compressors 41 to 44 may be controlled in a standby state.

As an example, the control unit controls the first boil-off gas compressor 41 to be in a standby state and the second to fourth boil-off gas compressors 42 to 44 to maintain the operating state when the boil-off gas generation amount is less than or equal to the preset generation amount. .

Thereafter, when the boil-off gas generation amount returns to exceed the preset generation amount, the control unit releases the standby state of the first boil-off gas compressor 41 and operates again, so that all the first to fourth boil-off gas compressors 41 to 44 are operated. I control it very much.

Then, when the amount of boil-off gas generated again changes below the preset amount, the second boil-off gas compressor 42, instead of the first boil-off gas compressor 41, is controlled to a stop operation, and the first, third, and fourth The boil-off gas compressors 41, 43, and 44 are controlled to maintain an operating state.

Accordingly, in the embodiment of the present invention, by performing the above alternating control through the control unit, there is an effect of improving the durability of the first to fourth boil-off gas compressors 41 to 44.

In addition, the control unit controls at least one of the first to fourth boil-off gas compressors 41 to 44 to an operation stop state, and controls the boil-off gas compressor 41 that has been stopped to operate from a preset condition to an operation standby state.

Here, when the operation standby state of the boil-off gas compressor (for example, the first boil-off gas compressor 51) that is on standby for operation exceeds a preset period, the control unit controls to stop the operation of the boil-off gas compressor 41 on standby or , Control to bypass the boil-off gas discharged from the boil-off gas compressor 41, which has been started to operate through the first bypass line BL1, to the front end of the preheater 30, and restarts the boil-off gas compressor 41. have.

Of course, bypass lines (not shown) may be provided in the second to fourth boil-off gas compressors 42 to 44, respectively, and a control valve (not shown) is provided in each of the bypass lines, and each control The bypass control may be performed through a valve.

Here, the preset condition may be a condition that reaches the previous time as much as the time it takes to restart the boil-off gas compressor 41 that has stopped operating at the time when the boil-off gas compressor 41 is restarted, and the operation is stopped. The time point for the boil-off gas compressor 41 to restart is a time when the internal pressure of the liquefied gas storage tank 10 exceeds the preset pressure or the time when the amount of boil-off gas generated in the liquefied gas storage tank 10 exceeds the preset amount Can be

As described above, in the embodiment of the present invention, through the control unit 90, the first to fourth boil-off gas compressors 41 to 44 can quickly return to the operating state from the standby state or from the stopped state, so that the reliability of the supply of boil-off gas. This has the effect of improving and maximizing stability.

2 is a conceptual diagram of a gas treatment system according to a second embodiment of the present invention.

As shown in Figure 2, the gas treatment system 1 according to the second embodiment of the present invention, a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, a standard high-pressure boil-off gas compressor ( 40), the propulsion engine 50, and includes first and second control units (not shown).

In the embodiment of the present invention, the components except for the standard high pressure boil-off gas compressor 40 and the first and second control units are each in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. The same reference numerals are used for configuration and convenience, but do not necessarily refer to the same configuration.

Hereinafter, a gas treatment system 1 according to a second embodiment of the present invention will be described with reference to FIG. 2, and a standard high pressure boil-off gas compressor 40 and a control unit will be mainly described.

The standard high-pressure boil-off gas compressor 40 is the same as described in the first embodiment, and the difference exists in that at least some of the compressors are equipped with a variable frequency drive device as described below.

The standard high-pressure boil-off gas compressor 40 is provided with at least one variable frequency drive (VFD) device among the first to fifth boil-off gas compressors 41 to 45, which are constituent compressors, and a variable frequency drive by the first and second controllers. Can be controlled.

For example, in the embodiment of the present invention, the first boil-off gas compressor 41 and the second boil-off gas compressor 42 may be controlled by a variable frequency drive (VFD), and the fifth boil-off gas compressor 45 is built for a spare. The variable frequency drive (VFD) can also be controlled.

The variable frequency drive control of the standard high pressure boil-off gas compressor 40 is described in detail in the control unit.

In an embodiment of the present invention, it may further include a flow sensor (F) and a pressure sensor (P).

The pressure sensor P may have a first pressure sensor P1 disposed between the standard high-pressure boil-off gas compressor 40 and the propulsion engine 50 on the boil-off gas supply line L2, as well as Like the pressure sensor P in the first embodiment, it may have a second pressure sensor P2 installed inside or outside to measure the internal pressure of the liquefied gas storage tank 10. Of course, the pressure sensor P may be connected to the control unit by wire or wirelessly, the first pressure sensor P1 may be connected to the first control unit, and the second pressure sensor P2 may be connected to the second control unit.

The flow sensor F may be disposed between the standard high-pressure boil-off gas compressor 40 and the propulsion engine 50 on the boil-off gas supply line L2, and of boil-off gas discharged from the standard high-pressure boil-off gas compressor 40 The flow rate can be measured and transmitted to the control unit. At this time, of course, the flow sensor F may be connected to the control unit by wire or wirelessly.

The control unit controls the standard high-pressure boil-off gas compressor 40 according to the pressure or flow rate of the boil-off gas required by the propulsion engine 50, or the standard high-pressure boil-off gas compressor according to the amount of boil-off gas generated in the liquefied gas storage tank 10. You can control 40. Here, the control unit may be divided into a first control unit and a second control unit. Hereinafter, according to the role of the controller, the description will be divided into first and second controllers.

The first control unit controls the pressure or flow rate of the boil-off gas discharged from the plurality of boil-off gas compressors (standard high-pressure boil-off gas compressors 40) according to the pressure or flow rate of the boil-off gas required by the propulsion engine 50, and propulsion One of a plurality of boil-off gas compressors (standard high-pressure boil-off gas compressors 40) is controlled by a variable frequency drive according to the pressure or flow rate of the boil-off gas required by the engine 50.

Specifically, the first control unit compares the pressure or flow rate of the boil-off gas required by the propulsion engine 50 with the pressure measured by the first pressure sensor P1 or the flow rate measured by the flow sensor F. The fourth boil-off gas compressors 41 to 44 can be controlled.

More specifically, the first control unit, when the pressure of the boil-off gas required by the propulsion engine 50 is lower than the pressure measured by the first pressure sensor (P1), the first and second boil-off gas compressors (41, 42) The variable frequency drive is controlled to increase the load, and when the pressure of the boil-off gas required by the propulsion engine 50 is higher than the pressure measured by the first pressure sensor P1, the first and second boil-off gas compressors 41 The variable frequency drive can be controlled to reduce the load of ,42).

The second control unit may control the standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated in the liquefied gas storage tank 10.

Specifically, the second control unit controls any one of the standard high-pressure boil-off gas compressors 40 in a standby state when the boil-off gas generation amount transmitted from the second pressure sensor P2 is less than or equal to the preset generation amount, and the boil-off gas compressor connected in parallel. The variable frequency drive can be controlled to increase the remaining load.

Here, the preset generation amount is the amount of boil-off gas flowing into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is the standard high-pressure boil-off gas compressor ( Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40), the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

As described above, in the second embodiment of the present invention, by controlling the standard high-pressure boil-off gas compressor 40 through variable frequency drive control without additional construction of a bypass line, valve, or buffer tank, the propulsion engine 50 ), since a stable supply of fuel to be supplied is possible, there is an effect of reducing the construction cost and expanding the space used in the vessel 100.

3 is a conceptual diagram of a ship including a gas treatment system according to a third embodiment of the present invention.

As shown in Figure 3, the gas treatment system 1 according to the third embodiment of the present invention, a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, a standard high pressure boil-off gas compressor ( 40), a propulsion engine 50, a buffer tank 51 and a control unit (not shown).

In the embodiment of the present invention, components other than the buffer tank 51 and the control unit use the same reference numerals for convenience as those in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. However, they do not necessarily refer to the same configuration.

Hereinafter, a gas treatment system 1 according to a third exemplary embodiment of the present invention will be described with reference to FIG. 3, and the buffer tank 51 and the control unit will be mainly described.

Hereinafter, before describing the buffer tank 51 and the control unit, the second bypass line BL2 and the second control valve B2 additionally provided in the embodiment of the present invention will be described, and the pressure sensor P and the boil-off gas supply Further description of the line L2 will be given.

The second bypass line BL2 is branched from the downstream of the standard high-pressure boil-off gas compressor 40 on the boil-off gas supply line L2 and is connected upstream of the standard high-pressure boil-off gas compressor 40, and a second control valve ( With B2), the boil-off gas supplied from the liquefied gas storage tank 10 and compressed by the standard high-pressure boil-off gas compressor 40 can be supplied upstream of the standard high-pressure boil-off gas compressor 40 again.

The second control valve B2 is provided on the second bypass line BL2 and transfers at least a portion of the boil-off gas discharged from the first boil-off gas compressor 41 to the upstream of the first boil-off gas compressor 41. The opening can be opened and closed to supply. In this case, the second control valve B2 may be connected by wire or wirelessly from the control unit to receive an opening or closing instruction.

In an embodiment of the present invention, the pressure sensor P may have a first pressure sensor P1 disposed between the standard high-pressure boil-off gas compressor 40 and the propulsion engine 50 on the boil-off gas supply line L2, and , In addition, it may have a second pressure sensor P2 installed inside or outside to measure the internal pressure of the liquefied gas storage tank 10 like the pressure sensor P in the first embodiment. Of course, the pressure sensor P may be connected to the control unit by wire or wirelessly.

In an embodiment of the present invention, the boil-off gas supply line (L2) may be connected in parallel to each of the first to fifth boil-off gas compressors (41 to 45), each of the first to fifth boil-off gas compressors (41 to 45) A line having a may be referred to as first to fifth supply lines (not shown).

Since the boil-off gas supply line L2 is formed in common upstream and downstream of the first to fifth supply lines, the upstream of the first to fifth supply lines may be referred to as an upstream common line, and the first to fifth supply lines. The downstream of the supply line can be referred to as a downstream common line.

The buffer tank 51 is provided between the standard high-pressure boil-off gas compressor 40 and the propulsion engine 50 on the boil-off gas supply line L2, and has different pressures in the constituent compressors of the standard high-pressure boil-off gas compressor 40. After the boil-off gas discharged as a temporary storage so as to have a preset pressure required by the propulsion engine 50, it is supplied to the propulsion engine 50.

The buffer tank 51 may be provided downstream of the first to fourth boil-off gas compressors 41 to 44 on the first to fourth supply lines, and unlike this, may be provided singly only on the downstream common line.

The control unit controls at least one of the standard high-pressure boil-off gas compressors 40 to a state in which the operation is stopped or in a standby state in which no compression of the boil-off gas is implemented, depending on the amount of boil-off gas generated in the liquefied gas storage tank 10, but the liquefied gas The flow of boil-off gas downstream of the standard high-pressure boil-off gas compressor 40 can be controlled according to the amount of boil-off gas generated in the storage tank 10.

Specifically, when the amount of boil-off gas generated in the liquefied gas storage tank 10 is greater than or equal to a preset amount, the control unit allows the boil-off gas discharged from the standard high-pressure boil-off gas compressor 40 to flow to the second bypass line BL2. And, when the amount of boil-off gas generated in the liquefied gas storage tank 10 is less than the preset amount, the boil-off gas discharged from the standard high-pressure boil-off gas compressor 40 may be controlled to flow to the buffer tank 51.

Here, the preset generation amount is the amount of boil-off gas flowing into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is the standard high-pressure boil-off gas compressor ( Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40), the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

As described above, in the third embodiment of the present invention, it is possible to provide a stable supply of fuel to be supplied to the propulsion engine 50 by constructing only the buffer tank 51 without additional construction of a bypass line, valve, etc., thereby reducing construction cost. And there is an effect that the space used in the vessel 100 is expanded.

In addition, since it is possible to provide a stable supply to the propulsion engine 50 with only the buffer tank 51 without complicated control logic, there is an effect of improving the reliability of fuel supply and maximizing system stability.

4 is a conceptual diagram of a ship including a gas treatment system according to a fourth embodiment of the present invention.

As shown in Fig. 4, the gas treatment system 1 according to the fourth embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, and a standard high-pressure boil-off gas compressor ( 40), a propulsion engine 50, an oil storage tank 60, an oil pump 61 and a control unit (not shown).

Components except for the oil storage tank 60, the oil pump 61, and the control unit in the embodiment of the present invention are each component in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. For convenience, the same reference numerals are used, but they do not necessarily refer to the same configuration.

Hereinafter, the gas treatment system 1 according to the fourth embodiment of the present invention will be described with reference to FIG. 4, and the oil storage tank 60, the oil pump 61, and the control unit will be mainly described.

Hereinafter, before describing the oil storage tank 60, the oil pump 61, and the control unit, an oil supply line L3 additionally provided in an embodiment of the present invention will be described.

In the embodiment of the present invention, an oil supply line (L3) may be further included.

The oil supply line (L3) is stored in the oil storage tank (60) by directly connecting the oil storage tank (60) and the propulsion engine (50) or by connecting the oil storage tank (60) and the boil-off gas supply line (L2). Oil can be supplied to the propulsion engine (60).

Here, the oil supply line L3 may include a valve (not shown) and an oil pump 61 for controlling the supply of oil, and the oil pump 61 is connected by wire or wirelessly from the controller to supply or You may be ordered to stop supply.

In the embodiment of the present invention, the pressure sensor (P), like the pressure sensor (P) in the first embodiment, can be installed inside or outside to measure the internal pressure of the liquefied gas storage tank 10, of course, the pressure The sensor P may be connected to the controller by wire or wirelessly.

The oil storage tank 60 stores oil to be supplied to the propulsion engine 50, and may be directly connected to the propulsion engine 50 through the oil supply line L3 or may be connected to the boil-off gas supply line L2.

Here, the oil storage tank 60 may have a form of a storage tank for storing oil, and the oil may be marine diesel oil (MDO) or heavy oil (HFO).

The oil pump 61 supplies the oil stored in the oil storage tank 60 to the propulsion engine 50, but the pressure required by the propulsion engine 50 and the boil-off gas supplied by the standard high-pressure boil-off gas compressor 40 are Oil is supplied to the propulsion engine 50 to compensate for the difference in pressure.

In this case, the oil pump 61 may be provided inside or outside the oil storage tank 60, and may be, for example, a centrifugal pump.

The control unit controls at least one of the standard high-pressure boil-off gas compressors 40 to a state in which the operation is stopped or in a standby state in which no compression of the boil-off gas is implemented, depending on the amount of boil-off gas generated in the liquefied gas storage tank 10, but the liquefied gas The oil pump 61 may be controlled according to the amount of boil-off gas generated in the storage tank 10.

Specifically, the control unit, when the amount of boil-off gas generated in the liquefied gas storage tank 10 is less than a preset amount, the pressure required by the propulsion engine 50 and the boil-off gas supplied by the standard high-pressure boil-off gas compressor 40 The oil pump 61 may be controlled to supply the required amount of oil equal to the difference in pressure to the propulsion engine 50.

The control unit allows the oil to be directly supplied to the propulsion engine 50 through the oil supply line L3, so that the pressure generated by the propulsion engine 50 burns the oil, and the pressure required by the propulsion engine 50 and the standard high pressure It can be controlled to compensate for the difference in the pressure of the boil-off gas supplied by the boil-off gas compressor 40.

Here, the preset generation amount is the amount of boil-off gas flowing into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is the standard high-pressure boil-off gas compressor ( Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40), the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

As described above, in the fourth embodiment of the present invention, only the oil storage tank 60 and the oil pump 61 are constructed without additional construction of bypass lines, valves, buffer tanks, etc., and then the standard high pressure boil-off gas compressor 40 In order to prevent the pressure fluctuation of the boil-off gas discharged from, by compensating for the pressure difference due to the pressure fluctuation by the control of the control unit that controls the supply of oil, it is possible to provide a stable supply of fuel to be supplied to the propulsion engine 50, and the construction cost This is reduced and there is an effect that the space used in the vessel 100 is expanded.

5 is a conceptual diagram of a ship including a gas treatment system according to a fifth embodiment of the present invention.

As shown in Fig. 5, the gas treatment system 1 according to the fifth embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, an additional preheater 31, and a standard high-pressure boil-off gas compressor. 40, a propulsion engine 50, a boil-off gas heat exchanger 70, and a control unit (not shown).

Components except for the additional preheater 31, the boil-off gas heat exchanger 70, and the control unit in the embodiment of the present invention are each in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. The same reference numerals are used for configuration and convenience, but do not necessarily refer to the same configuration.

Hereinafter, the gas treatment system 1 according to the fifth embodiment of the present invention will be described with reference to FIG. 5, and the additional preheater 31, the boil-off gas heat exchanger 70, and the control unit will be mainly described. In an embodiment of the present invention, the standard high-pressure boil-off gas compressor 40 may be referred to as an boil-off gas compressor for room temperature.

Hereinafter, before describing the additional preheater 31, the boil-off gas heat exchanger 70, and the control unit, a reliquefaction line L5 additionally provided in an embodiment of the present invention will be described.

The re-liquefaction line (L5) is branched from the downstream of the standard high-pressure boil-off gas compressor (40) on the boil-off gas supply line (L2) and is connected to the liquefied gas storage tank (10), and includes a boil-off gas heat exchanger (70). I can. Here, the reliquefaction line L5 may include a valve (not shown) that controls the supply of the boil-off gas.

The additional preheater 31 is provided between the boil-off gas heat exchanger 70 on the boil-off gas supply line L2 and the boil-off gas compressor 40 for room temperature, and supplies boil-off gas to the boil-off gas compressor 40 for room temperature. It is preheated and can be operated only when the boil-off gas heat exchanger 70 is provided in at least one of the plurality of room temperature boil-off gas compressors 40 and the boil-off gas heat exchanger 70 is not operated.

The additional preheater 31 is provided only in any one of the constituent compressors 41 to 44 (for example, the first boil-off gas compressor 41) and can be operated only when the boil-off gas heat exchanger 70 is not operated.

The additional preheater 31 has a capacity capable of preheating the amount of boil-off gas that can be processed by one of the boil-off gas compressors 40 for room temperature (one constituent compressor; for example, one of the first boil-off gas compressors 41). Can have.

The boil-off gas heat exchanger 70 is provided on the reliquefaction line L5 and the boil-off gas supply line L2, and supplies boil-off gas supplied from the liquefied gas storage tank 10 in the boil-off gas compressor 40 for room temperature. Heat exchange with compressed boil-off gas.

The boil-off gas heat-exchanged in the boil-off gas heat exchanger (70) includes boil-off gas compressed by the first to fourth boil-off gas compressors (41 to 44) and boil-off gas supplied from the liquefied gas storage tank (10). The boil-off gas supplied from the liquefied gas storage tank 10 is heated through heat exchange, and the boil-off gas compressed by the first to fourth boil-off gas compressors 41 to 44 is cooled.

Among the boil-off gases heat-exchanged in the boil-off gas heat exchanger 70, the boil-off gas compressed by the first to fourth boil-off gas compressors 41-44 is supplied to the liquefied gas storage tank 10, and the boil-off gas heat exchanger 20 The boil-off gas supplied from the liquefied gas storage tank 10 among the boil-off gas heat-exchanged in) may be supplied to the first to fourth boil-off gas compressors 41 to 44.

Through this, the boil-off gas compressed by the first to fourth boil-off gas compressors 41 to 44 can be partially reliquefied by receiving cold heat from the boil-off gas supplied from the liquefied gas storage tank 10, and the liquefied gas storage tank The boil-off gas supplied from (10) receives a heat source from the boil-off gas compressed by the first to fourth boil-off gas compressors (41 to 44) and preheats before being supplied to the first to fourth boil-off gas compressors (41 to 44). Can be.

The control unit may control the boil-off gas heat exchanger 70 and the additional preheater 31 according to whether or not the boil-off gas compressed by the boil-off gas compressor 40 for room temperature is supplied to the boil-off gas heat exchanger 70.

Specifically, when the boil-off gas compressed by the boil-off gas compressor 40 for room temperature is not supplied to the boil-off gas heat exchanger 70, the control unit operates the additional preheater 31, and in the boil-off gas compressor 40 for room temperature When the compressed boil-off gas is supplied to the boil-off gas heat exchanger 70, the additional preheater 31 may be controlled to stop operating. Here, when the boil-off gas heat exchanger 70 is not operated (when the boil-off gas compressed by the boil-off gas compressor 40 for room temperature is not supplied to the boil-off gas heat exchanger 70), the boil-off gas heat exchanger 70 It may take precedence over a case in which the boil-off gas compressed by the boil-off gas compressor 40 for room temperature is supplied to the boil-off gas heat exchanger (70).

The control of the control unit may be performed before the boil-off gas heat exchanger 70 is driven, that is, in an initial driving section of the boil-off gas heat exchanger 70.

In the initial driving section of the boil-off gas heat exchanger 70, there is a period in which the boil-off gas compressed by the boil-off gas compressor 40 for room temperature is not supplied to the boil-off gas heat exchanger 70 for a while. In this case, there is a concern that the boil-off gas that is not preheated may be supplied to the boil-off gas compressor 40 for room temperature, so that the initial driving efficiency of the boil-off gas compressor 40 for room temperature is very deteriorated.

Accordingly, in the embodiment of the present invention, the preheater 30 is not provided, and the additional preheater 31 is provided only upstream of the first boil-off gas compressor 41, and then, the initial stage of the boil-off gas heat exchanger 70 through the control unit. It can be controlled to drive only the first boil-off gas compressor 41 only in the driving section.

Through this, the boil-off gas compressed by the first boil-off gas compressor (41) is supplied to the boil-off gas heat exchanger (70) in the initial driving section of the boil-off gas heat exchanger (70). The preheated boil-off gas may be supplied to the remaining second to fourth boil-off gas compressors 42 to 44.

That is, in the embodiment of the present invention, the driving efficiency of the room temperature boil-off gas compressor 40 can be optimized through the control of the control unit as described above to maximize the driving efficiency, and the first to fourth boil-off gas compressors 41 to 44 ), instead of a preheater having a large capacity to cover the flow rate of the boil-off gas flowing into the first boil-off gas compressor 41, only the additional preheater 31 having a capacity to cover the flow rate of the boil-off gas flowing into the first boil-off gas compressor 41 It is possible to optimize the preheating of the boil-off gas supplied to the fourth boil-off gas compressors 41 to 44, thereby reducing construction costs and maximizing space utilization.

In an embodiment of the present invention, a boil-off gas pressure reducer (not shown) and a gas-liquid separator (not shown) may be further included.

The boil-off gas reducer is provided downstream of the boil-off gas heat exchanger 70 on the reliquefaction line L5 and is pressurized by the first to fourth boil-off gas compressors 41 to 44 to heat exchange in the boil-off gas heat exchanger 70 At least a part of the evaporated gas is reduced or expanded to liquefy. For example, the boil-off gas pressure reducer can reduce the boil-off gas of 150 to 350 bar to 1 bar to 10 bar, and when the boil-off gas is liquefied and transferred to the liquefied gas storage tank 10, it can be reduced to 1 bar. The cooling effect can be achieved.

In this embodiment, the boil-off gas pressurized in the first to fourth boil-off gas compressors 41 to 44 is heat-exchanged with the boil-off gas supplied from the liquefied gas storage tank 10 in the boil-off gas heat exchanger 70 and cooled, The pressure may maintain the discharge pressure discharged from the first to fourth boil-off gas compressors 41 to 44.

Accordingly, this embodiment uses the fact that the boil-off gas pressurized in the first to fourth boil-off gas compressors 41 to 44 as above is heat-exchanged in the boil-off gas heat exchanger 70 to maintain high pressure even after receiving cold heat. Thus, the boil-off gas can be further cooled by decompressing the boil-off gas through the boil-off gas pressure reducer.

Through this, the boil-off gas pressurized in the first to fourth boil-off gas compressors 41 to 44 is partially reliquefied in the boil-off gas heat exchanger 70, but can be finally completely liquefied in the boil-off gas reducer.

Specifically, the boil-off gas may be multi-stage pressurized by the first to fourth boil-off gas compressors 41 to 44 to have a pressure of 150 to 350 bar, and the temperature may be about 45 degrees. The boil-off gas that has risen to a temperature of around 45 degrees is recovered by the boil-off gas heat exchanger (70) and exchanges heat with the boil-off gas of -100 degrees Celsius supplied from the liquefied gas storage tank (10), and is cooled to a temperature of -97 degrees. And then supplied to the boil-off gas pressure reducer. In this case, the boil-off gas in the boil-off gas reducer may be cooled by decompression to have a pressure of about 1 bar and a temperature of about -162.3 degrees.

As described above, in this embodiment, since the boil-off gas has a temperature lower than -162 degrees due to the depressurization of the boil-off gas through the boil-off gas reducer, the boil-off gas liquefaction rate of about 30 to 40% can be realized. This is because the cooling effect of the boil-off gas can be increased as the pressure range of the boil-off gas is reduced.

Here, the boil-off gas pressure reducer may be made of a Joule-Thomson valve. Alternatively, the boil-off gas pressure reducer may be formed of an expander (expander).

The expander can be driven without using extra power. In particular, by utilizing the generated power as power to drive the first to fourth boil-off gas compressors 41 to 44, the efficiency of the gas treatment system 1 may be improved. Power transmission may be performed, for example, by gear connection or transmission after electric conversion.

The gas-liquid separator is provided on a downstream side of the boil-off gas pressure reducer provided downstream of the boil-off gas heat exchanger 70 on the reliquefaction line L5, and temporarily stores the boil-off gas depressurized or expanded in the boil-off gas reducer, It separates the boil-off gas into liquid and gas through gravity.

At this time, the gas is a flash gas, and the temperature is approximately -162.3 degrees. The flash gas and the boil-off gas of -100 degrees generated in the liquefied gas storage tank 10 are mixed upstream of the boil-off gas heat exchanger 70 to become a mixed gas having a temperature of -110 to -120 degrees (about -114 degrees). , The mixed gas may be introduced into the boil-off gas heat exchanger 70 in a state having a temperature of -110 to -120 degrees (about -114 degrees).

Therefore, the boil-off gas of 45 degrees recovered along the reliquefaction line (L5) is cooled by heat exchange with the mixed gas of -110 to -120 degrees supplied through the boil-off gas supply line (L2) in the boil-off gas heat exchanger (70). I can. It can be seen that when there is no recovery of the flash gas (evaporated gas of 45 degrees heat exchange with the evaporation gas of -100 degrees), additional cooling of the evaporated gas can be implemented.

For this reason, the boil-off gas discharged from the boil-off gas heat exchanger 70 and introduced into the boil-off gas reducer may be about -112 degrees lower than that in the case of no circulation of flash gas (about -97 degrees), and reduced pressure by the boil-off gas reducer. If so, it can be cooled to about -163.7 degrees. In this case, more boil-off gas is liquefied by the boil-off gas pressure reducer than when there is no circulation of the flash gas, and can be recovered to the liquefied gas storage tank 10.

Therefore, in this embodiment, by supplying the flash gas generated through the gas-liquid separator to the upstream of the boil-off gas heat exchanger 70, the temperature of the boil-off gas supplied from the liquefied gas storage tank 10 to the boil-off gas heat exchanger 70 is It becomes sufficiently low, and thus there is an effect of increasing the liquefaction efficiency of the boil-off gas compressed by the first to fourth boil-off gas compressors 41 to 44 and returned to the boil-off gas heat exchanger 70 to 60% or more.

In the gas-liquid separator, the boil-off gas is separated into a liquid and a gas, and the liquid is supplied to the liquefied gas storage tank 10, and the gas can be recovered as a flash gas upstream of the first to fourth boil-off gas compressors 41 to 44. have.

That is, when the boil-off gas is separated into liquid and gas in the gas-liquid separator, the liquefied boil-off gas (liquid) and flash gas (gas) are each recovered to the liquefied gas storage tank 10 through the re-liquefaction line (L5), or The boil-off gas may be recovered upstream of the heat exchanger 70 through a flash gas supply line (not shown).

As described above, the gas-liquid separator in this embodiment recovers the liquefied boil-off gas to the liquefied gas storage tank 10, and recovers the flash gas generated in the gas-liquid separator to the upstream of the boil-off gas heat exchanger (70). The gas can be re-liquefied and re-stored in the liquefied gas storage tank 10, and the flash gas can be re-pressurized through the first to fourth boil-off gas compressors 41 to 44 and supplied for reuse in the propulsion engine 50 without discarding the flash gas. have.

6 is a conceptual diagram of a ship including a gas treatment system according to a sixth embodiment of the present invention.

As shown in Fig. 6, the gas treatment system 1 according to the sixth embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, a high pressure pump 22, a carburetor 23, It includes a preheater 30, a standard high-pressure boil-off gas compressor 40, a propulsion engine 50, and a control unit (not shown).

Components except for the high-pressure pump 22, the vaporizer 23, and the control unit in the embodiment of the present invention are each configuration and convenience in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. Although the same reference numerals are used, they do not necessarily refer to the same configuration.

Hereinafter, the gas treatment system 1 according to the sixth embodiment of the present invention will be described with reference to FIG. 6, and the high pressure pump 22, the carburetor 23, and the control unit will be mainly described.

Hereinafter, before describing the high-pressure pump 22, the vaporizer 23, and the control unit, a liquefied gas supply line L4 additionally provided in an embodiment of the present invention will be described.

The liquefied gas supply line (L4) is a standard high-pressure boil-off gas compressor (40) connecting the liquefied gas storage tank (10) and the propulsion engine (50) or on the liquefied gas storage tank (10) and the boil-off gas supply line (L2) It is connected to the downstream of the, and may be provided with a high pressure pump 22 and a vaporizer (23). Here, the liquefied gas supply line L4 may include a valve (not shown) for controlling the supply of the liquefied gas.

The high-pressure pump 22 is provided between the boosting pump 20 and the vaporizer 23 on the liquefied gas supply line L4, and receives pressurized liquefied gas from the boosting pump 20 and pressurizes it at high pressure.

The carburetor 23 is provided between the high-pressure pump 22 and the propulsion engine 50 on the liquefied gas supply line L4, and receives and vaporizes the liquefied gas pressurized at high pressure from the high-pressure pump 22.

The control unit may control the standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated in the liquefied gas storage tank 10, and evaporate at least one of the standard high-pressure boil-off gas compressors 40 according to the amount of boil-off gas generated. It can be controlled in a standby state that does not implement gas compression.

Specifically, the control unit controls any one of the standard high-pressure boil-off gas compressors 40 to a standby state, and increases the load of the rest of the standard high-pressure boil-off gas compressors 40 connected in parallel when the boil-off gas generation amount is less than or equal to the preset generation amount. Can be controlled.

At this time, the preset generation amount is the amount of boil-off gas introduced into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40, the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

In this way, in the sixth embodiment of the present invention, it is possible to reduce the load of the standard high-pressure boil-off gas compressor 40 for processing boil-off gas, and there is an effect of reducing the construction cost.

7 is a conceptual diagram of a ship including a gas treatment system according to a seventh embodiment of the present invention.

As shown in Figure 7, the gas treatment system 1 according to the seventh embodiment of the present invention, a liquefied gas storage tank 10, a boosting pump 20, a high pressure pump 22, a carburetor 23, A preheater 30, a standard high-pressure boil-off gas compressor 40; hereinafter, it may be referred to as a boil-off gas compressor for room temperature), a cryogenic boil-off gas compressor 40a, a propulsion engine 50, a power generation engine 50a, and a control unit (not shown). Not included).

Components except for the cryogenic boil-off gas compressor 40a, the power generation engine 50a, and the control unit in the embodiment of the present invention are each in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. The same reference numerals are used for configuration and convenience, but do not necessarily refer to the same configuration.

Hereinafter, a gas treatment system 1 according to a seventh embodiment of the present invention will be described with reference to FIG. 7, and a cryogenic boil-off gas compressor 40a, a power generation engine 50a, and a control unit will be mainly described.

Hereinafter, before describing the cryogenic boil-off gas compressor 40a, the power generation engine 50a, and the control unit, a power generation engine fuel supply line L2a additionally provided in an embodiment of the present invention will be described.

The power generation engine fuel supply line (L2a) connects the liquefied gas storage tank 10 and the power generation engine 50a or branches between the preheater 30 and the liquefied gas storage tank 10 on the boil-off gas supply line L2. It is connected to the power generation engine (50a), it may be provided with a cryogenic boil-off gas compressor (40a).

The power generation engine fuel supply line (L2a) can supply the boil-off gas generated from the liquefied gas storage tank 10 to the power generation engine 50a, and compresses the unpreheated boil-off gas using a cryogenic boil-off gas compressor (40a). After that, it can be supplied to the power generation engine 50a.

Here, the power generation engine fuel supply line L2a may include a valve (not shown) that controls the supply of boil-off gas, and evaporates when the boil-off gas supply line L2 is called the boil-off gas first supply line. It may be referred to as a gas second supply line.

The cryogenic boil-off gas compressor 40a pressurizes the boil-off gas supplied from the upstream of the preheater 30 among the boil-off gas supplied from the liquefied gas storage tank 10 and supplies it to the power generation engine 50a.

The cryogenic boil-off gas compressor (40a) is provided on the power generation engine fuel supply line (L2a) to receive and compress the boil-off gas generated from the liquefied gas storage tank (10) without preheating, and the compressed boil-off gas to the power generation engine (50a) can be supplied.

The power generation engine 50a uses the boil-off gas supplied from the liquefied gas storage tank 10 as fuel. That is, the power generation engine 50a requires evaporation gas and can be driven using this as a raw material. The power generation engine 50a may be, for example, DFDE or DFDG as a generator, but is not limited thereto.

Specifically, the power generation engine (50a) may be connected through the cryogenic boil-off gas compressor (40a) and the power generation engine fuel supply line (L2a), in the cryogenic boil-off gas compressor (40a) low pressure (2 to 8 bar; preferably 4 To 6bar) compressed boil-off gas may be supplied and used as fuel.

In addition, the power generation engine 50a may be a heterogeneous fuel engine capable of using different types of fuel, so that not only the boil-off gas but also oil can be used as a fuel, but the boil-off gas and oil are not mixed and supplied, and the boil-off gas or oil is selectively used. Can be supplied. This is to prevent the two materials having different combustion temperatures from being mixed and supplied, thereby preventing the efficiency of the power generation engine 50a from deteriorating.

In addition, the power generation engine 50a may generate steam by heating fresh water as a boiler, and may generate power from the generated steam or store the remaining steam in a separate steam storage medium.

The power generation engine 50a may supply the generated steam to the preheater 30, the additional preheater 31, or the forced vaporizer 21, through which the preheater 30, the additional preheater 31, or the forced vaporizer 21 Make it possible to heat the boil-off gas.

At this time, the power generation engine 50a may be referred to as a low-pressure consumer when the propulsion engine 50 is referred to as a high-pressure consumer.

The control unit may control the standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated in the liquefied gas storage tank 10, and the standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated. ) At least one of them can be controlled in a standby state that does not implement compression of the boil-off gas.

Specifically, the control unit controls any one of the standard high-pressure boil-off gas compressors 40 to a standby state, and increases the load of the rest of the standard high-pressure boil-off gas compressors 40 connected in parallel when the boil-off gas generation amount is less than or equal to the preset generation amount. Can be controlled.

At this time, the preset generation amount is the amount of boil-off gas introduced into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40, the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

As described above, in the seventh embodiment of the present invention, when the room temperature boil-off gas compressor 40 and the cryogenic boil-off gas compressor 40a are used together, the characteristics of the cryogenic boil-off gas compressor 40a that can be used without the preheater 30 By designing to supply the boil-off gas branching from the upstream of the preheater 30 to the cryogenic boil-off gas compressor 40a, the energy for processing the boil-off gas can be optimized and the system efficiency can be increased. There is an effect of reducing the construction cost.

8 is a conceptual diagram of a ship including a gas treatment system according to an eighth embodiment of the present invention.

As shown in Figure 8, the gas treatment system 1 according to the eighth embodiment of the present invention, a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, a standard high-pressure boil-off gas compressor ( 40), a propulsion engine 50, first to fourth block valves 81 to 84, and a control unit (not shown).

In the embodiment of the present invention, components except for the first to fourth block valves 81 to 84 and the control unit are each component in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. 1. For convenience, the same reference numerals are used, but they do not necessarily refer to the same configuration.

Hereinafter, a gas treatment system 1 according to an eighth embodiment of the present invention will be described with reference to FIG. 8, and the first to fourth block valves 81 to 84 and the control unit will be mainly described.

The first to fourth block valves 81 to 84 are provided downstream of each of the first to fourth boil-off gas compressors 41 to 44 on the boil-off gas supply line L2, and the first to fourth boil-off gas compressors It is possible to control the flow rate of the boil-off gas discharged from (41 to 44) supplied to the propulsion engine (50).

At this time, the first to fourth block valves 81 to 84 may be referred to as first to fourth control valves, and each of the valves is wired or wirelessly connected to the control unit to transmit an open degree open signal or an open degree close signal. Can be received and driven.

The control unit controls at least one of the standard high-pressure boil-off gas compressor 40 in a standby state according to the first control unit for controlling the start of driving of the standard high-pressure boil-off gas compressor 40 and the amount of boil-off gas generated in the liquefied gas storage tank 10 It may include a second control unit.

The first control unit controls the start of driving of the standard high-pressure boil-off gas compressor 40 (a plurality of boil-off gas compressors), but when starting the driving of the standard high-pressure boil-off gas compressor 40, the standard high-pressure boil-off gas compressor 40 is sequentially Control to be driven.

Specifically, the first control unit, when the processing flow rate of the first boil-off gas compressor driven among the standard high-pressure boil-off gas compressors 40 exceeds a preset flow rate, controls the boil-off gas compressor to be driven in the following sequence. can do.

For example, the first boil-off gas compressor that is driven first may be referred to as a first boil-off gas compressor 41, and the boil-off gas compressor that is driven after the first boil-off gas compressor 41 may be referred to as a second boil-off gas compressor 42, and then The boil-off gas compressors that are continuously driven may be the third boil-off gas compressor 43 and the fourth boil-off gas compressor 44.

More specifically, the first control unit closes all of the first to fourth control valves 81 to 84 when the driving of the first boil-off gas compressor 41 starts, and the boil-off gas processing flow rate of the first boil-off gas compressor 81 When this preset flow rate is reached, the second boil-off gas compressor 42 is started to be driven, and when the boil-off gas processing flow rate of the first boil-off gas compressor 41 is the maximum driving flow rate, the first control valve 81 is opened. By controlling, it is possible to supply the high-pressure boil-off gas required by the propulsion engine 50 to the propulsion engine 50. Of course, at this time, since the second to fourth control valves 82 to 84 are in a closed state, only the boil-off gas compressed by the first boil-off gas compressor 41 is supplied to the propulsion engine 50.

Subsequently, when the boil-off gas processing flow rate of the second boil-off gas compressor 42 becomes a preset flow rate, the third boil-off gas compressor 43 is started to be driven, and the boil-off gas processing flow rate of the second boil-off gas compressor 42 is driven to the maximum. When the flow rate is reached, the second control valve 83 is controlled to open, so that the high-pressure boil-off gas compressed at the pressure required by the propulsion engine 50 in the first and second boil-off gas compressors 41 and 42 is driven by a propulsion engine ( 50) can be supplied. (The third and fourth control valves 83 and 84 remain closed until this time.)

Next, when the boil-off gas processing flow rate of the third boil-off gas compressor 43 becomes a preset flow rate, the fourth boil-off gas compressor 44 is started to be driven, and the boil-off gas processing flow rate of the third boil-off gas compressor 43 is driven to the maximum. When the flow rate is reached, the third control valve 83 is controlled to open, so that the high-pressure boil-off gas compressed at the pressure required by the propulsion engine 50 in the first to third boil-off gas compressors 41 to 43 is driven by a propulsion engine ( 50) can be supplied.

Next, when the boil-off gas processing flow rate of the fourth boil-off gas compressor 44 is the maximum driving flow rate, the fourth control valve 84 is opened to the propulsion engine 50 in the first to fourth boil-off gas compressors 41 to 44. The required high-pressure boil-off gas can be supplied to the propulsion engine 50.

Here, the preset flow rate may be a flow rate of 85 to 95% of the maximum driving flow rate of the standard high-pressure boil-off gas compressor 40.

Through the control of the first control unit, the pressure of the boil-off gas to be supplied to the propulsion engine 50 can be constantly supplied at the high pressure required by the propulsion engine 50, so that flexible fuel can be supplied to the propulsion engine 50. As a result, there is an effect of increasing the stability of the gas treatment system 1 and maximizing the driving efficiency of the propulsion engine 50.

The second control unit may control a standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated in the liquefied gas storage tank 10, and a standard high-pressure boil-off gas compressor according to the amount of boil-off gas generated. At least one of (40) may be controlled in a standby state in which compression of the boil-off gas is not implemented.

Specifically, the second control unit controls any one of the standard high-pressure boil-off gas compressors 40 to a standby state when the boil-off gas generation amount is less than or equal to the preset generation amount, and increases the load of the rest of the standard high-pressure boil-off gas compressors 40 connected in parallel. You can control to let it happen.

At this time, the preset generation amount is the amount of boil-off gas introduced into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40, the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

9 is a conceptual diagram of a ship including a gas treatment system according to a ninth embodiment of the present invention.

As shown in Fig. 9, the gas treatment system 1 according to the ninth embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, and a standard high-pressure boil-off gas compressor ( 40), a propulsion engine 50, a power generation engine 50a, and a control unit (not shown).

In the embodiment of the present invention, components other than the control unit use the same reference numerals for convenience as the components in the gas treatment system 1 according to the seventh embodiment of the present invention described with reference to FIG. Does not refer to.

Hereinafter, a gas treatment system 1 according to a ninth embodiment of the present invention will be described with reference to FIG. 9, and a control unit will be mainly described.

Hereinafter, before describing the control unit, a third bypass line BL3 additionally provided in an embodiment of the present invention will be described.

The third bypass line BL3 is branched at the intermediate stage (between the second stage and the third stage) of each of the standard high-pressure boil-off gas compressors 40 provided on the boil-off gas supply line L2, and the power generation engine ( 50a) can be connected.

The third bypass line BL3 may supply low-pressure boil-off gas compressed in the second to third stages of each of the standard high-pressure boil-off gas compressor 40 to the power generation engine 50a, and boil-off gas on each line It may be provided with a valve (not shown) for controlling the supply of. Here, when the boil-off gas supply line L2 is called a high-pressure boil-off gas supply line, the third bypass line BL3 may be called a low-pressure boil-off gas supply line.

The control unit controls the standard high-pressure boil-off gas compressor 40 according to whether or not the ship 100 is sailing.

Specifically, the control unit controls to supply at least one of the standard high-pressure boil-off gas compressors 40 to only the power generation engine 50a when the ship 100 is a ballast voyage, and the remaining evaporation of the standard high-pressure boil-off gas compressors 40 The gas compressor can be controlled to be supplied to both the power generation engine 50a and the propulsion engine 50.

At this time, the control unit, the amount of the boil-off gas supplied to the power generation engine (50a) among the boil-off gas compressed by the remaining boil-off gas compressors of the standard high-pressure boil-off gas compressor (40) is less than the amount of boil-off gas supplied to the propulsion engine (50). It can be controlled to be less.

For example, the control unit controls the boil-off gas compressed by the first and second boil-off gas compressors 41 and 42 to be supplied only to the power generation engine 50a, and compresses the boil-off gas compressed by the third and fourth boil-off gas compressors 43 and 44. The evaporated gas can be controlled to be supplied to both the propulsion engine 50 and the power generation engine 50a.

At this time, the control unit supplies a value of 200 as the boil-off gas supply flow rate of the first and second boil-off gas compressors (41, 42) to the power generation engine (50a), but controls not to supply boil-off gas to the propulsion engine (50) at all. And, as the boil-off gas supply flow rates of the third and fourth boil-off gas compressors 43 and 44, a value of 200 may be supplied to the power generation engine 50a and a value of 700 may be controlled to be supplied to the propulsion engine 50.

As described above, in the ninth embodiment of the present invention, it is possible to very efficiently process the boil-off gas during the ballast voyage with a small amount of boil-off gas, so that the consumption of the boil-off gas is optimized to prevent environmental pollution and increase the system driving efficiency. There is an effect.

10 is a conceptual diagram of a ship including a gas treatment system according to a tenth embodiment of the present invention.

As shown in Fig. 10, the gas treatment system 1 according to the tenth embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, and a standard high-pressure boil-off gas compressor ( 40), and a propulsion engine 50 and a control unit (not shown).

In the embodiment of the present invention, components other than the control unit use the same reference numerals for convenience as the components in the gas treatment system 1 according to the first embodiment of the present invention described with reference to FIG. Does not refer to.

Hereinafter, a gas treatment system 1 according to a tenth embodiment of the present invention will be described with reference to FIG. 10, and a control unit will be mainly described.

In an embodiment of the present invention, a load sensor (L; load measurement sensor) may be further included.

The load sensor (L) may be provided inside or outside the propulsion engine 50, and may measure the load or load of the propulsion engine 50 and transmit it to the control unit. At this time, of course, the load sensor L may be connected to the controller by wire or wirelessly.

The control unit controls the standard high-pressure boil-off gas compressor 40 according to the load of the propulsion engine 50, but compresses at least one of the standard high-pressure boil-off gas compressors 40 according to the load of the propulsion engine 50. It is controlled in a standby state that is not implemented.

Specifically, the control unit receives the load amount of the propulsion engine 50 measured from the load sensor L and controls the driving of the standard high-pressure boil-off gas compressor 40, but the amount of load received from the load sensor L is preset. If the load is less than or equal to the load amount, one of the standard high-pressure boil-off gas compressors 40 may be controlled in a standby state, and the load of the remaining standard high-pressure boil-off gas compressors 40 connected in parallel may be controlled to increase.

At this time, the preset generation amount is the amount of boil-off gas introduced into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40, the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

As described above, in the tenth embodiment of the present invention, the standard high-pressure boil-off gas compressor 40 can be differentially driven according to the load of the propulsion engine 50, so that the boil-off gas can be treated very efficiently, and the standard high-pressure boil-off gas Since the load of the compressor 40 can be optimized, the consumption of boil-off gas is optimized, thereby preventing environmental pollution and increasing system driving efficiency.

11 is a conceptual diagram of a ship including a gas treatment system according to an eleventh embodiment of the present invention.

As shown in FIG. 11, the gas treatment system 1 according to the eleventh embodiment of the present invention includes a liquefied gas storage tank 10, a boosting pump 20, a preheater 30, and a standard high-pressure boil-off gas compressor ( 40), a propulsion engine 50, a power generation engine 50a, a gas combustion device 50b, a reliquefaction device 90, a pressure reducing valve 91, the first and second oil separators 92 and 93, and a control unit ( Not shown).

Components except for the gas combustion device 50b, the reliquefaction device 90, the pressure reducing valve 91, the first and second oil separators 92 and 93, and the control unit in the embodiment of the present invention are described with reference to FIG. 7 For convenience, the same reference numerals are used for each configuration in the gas treatment system 1 according to the seventh embodiment of the present invention, but the same configurations are not necessarily referred to.

Hereinafter, a gas treatment system 1 according to an eleventh embodiment of the present invention will be described with reference to FIG. 11, and the gas combustion device 50b, the reliquefaction device 90, the pressure reducing valve 91, and the first And the second oil separators 92 and 93 and the control unit will be described in focus.

In addition, the standard high pressure boil-off gas compressor 40 may be a compressor that uses lubricating oil by implementing lubrication of the lubrication method in this embodiment, and after mixing and compressing the lubricating oil with the boil-off gas, the propulsion engine 50 or the power generation engine ( 50a) and the gas combustion device 50b. (Of course, the meaning that it can be supplied to the power generation engine 50a and the gas combustion device 50b includes the supply to the pressure reducing valve 91.)

Hereinafter, before describing the control unit, a power generation engine fuel supply line L5a and a gas combustion device fuel supply line L5b additionally provided in an embodiment of the present invention will be described. Unlike in the fifth embodiment, in the reliquefaction line L5, the power generation engine fuel supply line L5a and the gas combustion device fuel supply line L5b are branched, and the boil-off gas heat exchanger 70 on the reliquefaction line L5. ), a reliquefaction device 90, a pressure reducing valve 91, and first and second oil separators 92 and 93 may be provided.

The power generation engine fuel supply line L5a may be branched upstream of the reliquefaction device 90 on the reliquefaction line L5 to be connected to the power generation engine 50a, and the gas combustion device fuel supply line L5b is It may be branched upstream of the reliquefaction device 90 on the liquefaction line L5 to be connected to the gas combustion device 50b.

At this time, a valve (not shown) for controlling the supply of boil-off gas may be provided on each line of the power generation engine fuel supply line L5a and the gas combustion device fuel supply line L5b, wherein the boil-off gas supply line L2 ) Is referred to as a high-pressure boil-off gas supply line, the reliquefaction line (L5), the power generation engine fuel supply line (L5a), and the gas combustion device fuel supply line (L5b) may be collectively referred to as a low-pressure boil-off gas supply line, The power generation engine fuel supply line L5a may be referred to as a first low-pressure boil-off gas supply line, and the gas combustion device fuel supply line L5b may be referred to as a second low-pressure boil-off gas supply line.

The gas combustion device (50b; Gas Combustion Unit) is connected to the gas combustion device fuel supply line (L5b) to receive and burn the boil-off gas depressurized by the pressure reducing valve (91), and to discharge the burned boil-off gas to the outside. I can.

The gas combustion device 50b may be combusted by receiving a low-pressure boil-off gas, such as the power generation engine 50a, and receiving boil-off gas mixed with a lubricating oil for combustion.

Here, the gas combustion device 50b may be referred to as a low-pressure consumer, such as the power generation engine 50a, when the propulsion engine 50 is referred to as a high-pressure consumer, and in detail, the first low-pressure together with the power generation engine 50a It can be subdivided into demand and called.

The re-liquefaction device 90 is provided on the re-liquefaction line L5 to receive and re-liquefy the boil-off gas depressurized by the pressure reducing valve 91, and supply the re-liquefied boil-off gas to the liquefied gas storage tank 10. I can.

The reliquefaction device 90 may have a separate refrigerant cycle and, for example, may have a refrigerant cycle using nitrogen.

Unlike the power generation engine 50a and the gas combustion device 50b, the reliquefaction device 90 cannot use the boil-off gas mixed with lubricating oil, so that the lubricating oil is supplied by the first and second oil separators 92 and 93 to be described later. Separate boil-off gas can be supplied.

The reliquefaction device 90 may be further provided with a gas-liquid separator (not shown) downstream to supply the boil-off gas that has not been re-liquefied to other boil-off gas consumers (for example, a gas combustion device 50b, etc.). Through this, the internal pressure of the liquefied gas storage tank 10 can be prevented from rapidly increasing.

Here, the reliquefaction device 90 may be referred to as a low-pressure consumer, such as a power generation engine 50a and a gas combustion device 50b, when the propulsion engine 50 is called a high-pressure consumer, and in detail, a power generation engine ( When 50a) and the gas combustion device 50b are referred to as a first low-pressure consumer, they may be subdivided into a second low-pressure consumer and called.

The pressure reducing valve 91 is provided upstream of a branch of the power generation engine fuel supply line L5a and the gas combustion device fuel supply line L5b on the reliquefaction line L5, and a standard high-pressure boil-off gas compressor 40 At least some of the boil-off gas supplied from may be reduced to a pressure required by the power generation engine 50a and the gas combustion device 50b. Here, the pressure reducing valve 91 may be referred to as a pressure reducing device.

The pressure reducing valve 91, for example, receives the boil-off gas compressed to 200 to 400 bar from the standard high-pressure boil-off gas compressor 40,

The first and second oil separators 92 and 93 are provided downstream of the pressure reducing valve 91 on the reliquefaction line L5, and are mixed with the evaporated gas reduced by the pressure reducing valve 91. Can be separated, and the boil-off gas from which the lubricating oil has been separated can be supplied to the reliquefaction device 90.

That is, the first and second oil separators 92 and 93 separate the lubricating oil by receiving the boil-off gas depressurized by the pressure reducing valve 91, and thus lower than the boil-off gas before being depressurized by the pressure reducing valve 91. Since the lubricating oil can be removed by receiving the evaporated gas at a temperature, a large amount of lubricating oil is solidified, so that the removal efficiency of the lubricating oil is increased rather than removing the lubricating oil from the evaporated gas before the pressure reduction valve 91 is reduced.

Specifically, the first oil separator 92 is between the pressure reducing valve 91 and an upstream of the point at which the power generation engine fuel supply line L5a and the gas combustion system fuel supply line L5b on the reliquefaction line L5 are branched. It may be provided, it is possible to perform the primary lubricating oil removal of the boil-off gas reduced by the pressure reducing valve 91.

The first oil separator 92 transfers the boil-off gas from which the lubricating oil is separated to the power generation engine 50a through the power generation engine fuel supply line L5a, and the gas combustion device 50b through the gas combustion system fuel supply line L5b. Can be supplied with.

The second oil separator 93 is provided between the reliquefaction device 90 and downstream of the branch of the power generation engine fuel supply line L5a and the gas combustion device fuel supply line L5b on the reliquefaction line L5. The evaporation gas from which the primary lubricant has been removed by the first oil separator 92 can be removed from the secondary lubricant.

The second oil separator 93 can safely supply the boil-off gas from which the lubricating oil is finally removed to the reliquefaction device 90, thereby maximizing the driving efficiency of the reliquefaction device 90 and maximizing safety.

That is, the second oil separator 93 is provided as a complementary to the first oil separator 92, so that the lubricating oil that cannot be separated due to the excessive flow of boil-off gas being supplied to the first oil separator 92 is completely removed. Since it can be removed, the driving reliability of the reliquefaction device 90 may be improved and the driving efficiency may be increased due to the complete removal of the lubricating oil.

Also, unlike the embodiment of the present invention, the first oil separator 92 may be removed and only the second oil separator 93 may be provided. In this case, the second oil separator 93 does not need to remove the lubricating oil up to the boil-off gas to be supplied to the power generation engine 50a and the gas combustion device 50b, which is possible even when the boil-off gas mixed with lubricating oil is used. As the flow rate of the boil-off gas is reduced, the size can be reduced, thereby reducing construction costs and enabling system optimization.

The control unit can control the standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated in the liquefied gas storage tank 10, and the standard high-pressure boil-off gas compressor 40 according to the amount of boil-off gas generated. At least one of them may be controlled in a standby state in which compression of the boil-off gas is not implemented.

Specifically, the control unit controls any one of the standard high-pressure boil-off gas compressors 40 to a standby state, and increases the load of the rest of the standard high-pressure boil-off gas compressors 40 connected in parallel when the boil-off gas generation amount is less than or equal to the preset generation amount. Can be controlled.

At this time, the preset generation amount is the amount of boil-off gas introduced into the standard high-pressure boil-off gas compressor 40 from the inefficiency point of the standard high-pressure boil-off gas compressor 40, and the inefficiency point of the standard high-pressure boil-off gas compressor 40 is Even if the flow rate supplied to the standard high-pressure boil-off gas compressor 40 decreases in the ratio of the amount of power consumption to the flow rate of 40, the power consumption does not decrease.

In addition, the load amount at the point of inefficiency of the standard high-pressure boil-off gas compressor 40 may be a flow rate of 20 to 40% of the flow rate at which the standard high-pressure boil-off gas compressor 40 has a maximum load.

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, and the present invention is not limited thereto, and within the technical scope of the present invention, by those of ordinary skill in the art. It would be clear that the transformation or improvement is possible.

All simple modifications to changes of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

1: gas treatment system 100: ship
10: liquefied gas storage tank 20: boosting pump
21: forced carburetor 22: high pressure pump
23: carburetor 30: preheater
31: auxiliary preheater 40: standard high pressure boil-off gas compressor
41: first boil-off gas compressor 42: second boil-off gas compressor
43: third boil-off gas compressor 44: fourth boil-off gas compressor
45: fifth boil-off gas compressor 40a: cryogenic boil-off gas compressor
50: propulsion engine 50a: power generation engine
50b: gas combustion system (GCU) 51: buffer tank
60: oil storage tank 61: oil pump
70: boil-off gas heat exchanger 81: first block valve
82: second block valve 83: third block valve
84: fourth block valve 90: reliquefaction device
91: pressure reducing valve 92: first oil separator
93: second oil separator
L1: Forced vaporization gas supply line L2: Boil-off gas supply line
L2a: Power generation engine fuel supply line L3: Oil supply line
L4: Liquefied gas supply line L5: Reliquefaction line
L5a: Power generation engine fuel supply line L5b: Gas combustion system fuel supply line
BL1: first bypass line BL2: second bypass line
BL3: 3rd bypass line B1: 1st regulating valve
B2: second control valve P: pressure sensor
F: flow sensor L: load sensor

Claims (9)

A boil-off gas compressor that supplies the boil-off gas generated in the liquefied gas storage tank to a customer, and is provided in plurality and is built in parallel with each other;
A buffer tank provided downstream of the boil-off gas compressor;
A bypass line bypassing from an upstream to a downstream side of the buffer tank; And
Controls some of the boil-off gas compressors in a standby state according to the amount of boil-off gas generated in the liquefied gas storage tank, and controls the flow of boil-off gas downstream of the boil-off gas compressor according to the amount of boil-off gas generated in the liquefied gas storage tank It includes a control unit,
The buffer tank,
The boil-off gases discharged at different pressures from the plurality of boil-off gas compressors are temporarily stored to have a preset pressure required by the customer, and then supplied to the customer,
The control unit,
When the amount of boil-off gas generated in the liquefied gas storage tank is greater than or equal to a preset amount, the boil-off gas discharged from the boil-off gas compressor is controlled to flow to the bypass line,
When the amount of boil-off gas generated in the liquefied gas storage tank is less than a preset amount, the boil-off gas discharged from the boil-off gas compressor is controlled to flow to the buffer tank. delete The method of claim 1, wherein the preset generation amount is
It is the amount of boil-off gas flowing into the boil-off gas compressor at an inefficiency point of the boil-off gas compressor,
The inefficiency point of the boil-off gas compressor is,
A gas processing system, characterized in that in the ratio of the amount of power consumption to the flow rate of the boil-off gas compressor, the power consumption does not decrease even if the flow rate supplied to the boil-off gas compressor decreases. The method of claim 3, wherein the load at the point of inefficiency of the boil-off gas compressor is
Gas processing system, characterized in that the flow rate of 20 to 40% of the flow rate of the boil-off gas compressor having a maximum load. The method of claim 1, wherein the boil-off gas compressor,
A gas processing system comprising: a compressor having four or five pistons connected in series, wherein the compressors are provided with four first to fourth boil-off gas compressors and are connected in parallel with each other. The method of claim 5,
Further comprising boil-off gas first to fourth supply lines connecting the liquefied gas storage tank and the customer, and having the first to fourth boil-off gas compressors,
Gas processing system, characterized in that the upstream and downstream of the first to fourth boil-off gas compressors on the first to fourth supply lines are provided with an upstream common line and a downstream common line that are formed in common. The method of claim 6, wherein the buffer tank,
Gas processing system, characterized in that provided on the downstream common line. The method of claim 1, wherein the boil-off gas compressor,
Gas treatment system, characterized in that the standard high pressure compressor (Standard High Pressure Compressor). A ship comprising the gas treatment system of claim 1.

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