KR102189278B1 - Treatment system of gas and ship having the same - Google Patents

Abstract

The present invention relates to a gas treatment system and a ship, comprising: a liquefied gas storage tank for storing liquefied gas; A liquefied gas supply unit for delivering the liquefied gas from the liquefied gas storage tank to a plurality of customers; And a condenser provided in the liquefied gas supply unit and condensing the boil-off gas of the liquefied gas storage tank with liquefied gas, wherein the condenser is upstream of a point at which the liquefied gas diverges from the liquefied gas supply unit to the plurality of customers. It characterized in that it is provided.

Description

Treatment system of gas and ship having the same}

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

A ship is a means of transport that navigates the ocean with a large amount of minerals, crude oil, natural gas, or more than a few thousand containers. It is made of steel, and the thrust generated by the rotation of the propeller while floating on the water surface by buoyancy Go through.

These ships generate thrust by driving an engine or a gas turbine. At this time, the engine uses fuel such as gasoline or diesel to move the piston so that the crankshaft is rotated by the reciprocating motion of the piston, and the shaft connected to the crankshaft is It rotates to drive the propeller, while gas turbines burn fuel with compressed air, and generate power by rotating the turbine blades through the temperature/pressure of the combustion air and transmit power to the propeller.

However, in recent years, LNG carriers that transport liquefied natural gas have used LNG as fuel to drive customers such as engines and turbines, and the LNG fuel supply method is being used. This method is also applied to other ships other than LNG carriers.

In general, it is known that LNG is a clean fuel and its reserves are also richer than petroleum, and its usage is rapidly increasing as mining and transportation technologies are developed. Such LNG is generally stored in a liquid state by lowering the temperature to -162°C or less under 1 atmosphere of methane, the main component of this LNG.The volume of liquefied methane is about 1/600 of the volume of methane in the gaseous state, which is the standard state. Its specific gravity is 0.42, which is about a half of that of crude oil.

However, the temperature and pressure required to drive the customer may be different from the state of the LNG stored in the tank. Therefore, in recent years, continuous research and development has been made on a technology that controls the temperature and pressure of LNG stored in a liquid state and supplies it to a customer.

In addition, liquefied gas is stored in the liquefied gas storage tank in a forced liquefied state, but because the liquefied gas storage tank cannot achieve perfect insulation, some liquefied gas stored in the liquefied gas storage tank is As a result, the phase changes to evaporation gas, which is a gas.

At this time, the volume of the boil-off gas converted to gas increases significantly, which increases the internal pressure of the liquefied gas storage tank.If the internal pressure of the liquefied gas storage tank exceeds the pressure that the liquefied gas storage tank can withstand, the liquefied gas is stored. There is a risk of damage to the tank.

Therefore, conventionally, in order to keep the internal pressure of the liquefied gas storage tank constant, a method of lowering the internal pressure of the liquefied gas storage tank by discharging boil-off gas to the outside was used when necessary. Alternatively, the boil-off gas was discharged to the outside of the liquefied gas storage tank, liquefied using a separately provided re-liquefaction device, and then recovered to the liquefied gas storage tank.

However, when the boil-off gas is simply discharged to the outside, there may be a problem of contamination of the external environment, and when a re-liquefaction device is used, problems such as cost and manpower required to equip and operate the re-liquefaction device occur. Therefore, there is a need to develop an effective treatment method for the boil-off gas generated by external heat penetration.

The present invention was created to solve the problems of the prior art as described above, and an object of the present invention is to provide a condenser for condensing boil-off gas using liquefied gas, so that the boil-off gas can be recycled without simply discharging it to the outside. It is to provide a gas treatment system and a ship.

A gas treatment system according to an aspect of the present invention includes: a liquefied gas storage tank for storing liquefied gas; A liquefied gas supply unit for delivering the liquefied gas from the liquefied gas storage tank to a plurality of customers; And a condenser provided in the liquefied gas supply unit and condensing the boil-off gas of the liquefied gas storage tank with liquefied gas, wherein the condenser is upstream of a point at which the liquefied gas diverges from the liquefied gas supply unit to the plurality of customers. It characterized in that it is provided.

Specifically, the liquefied gas supply unit may include a liquefied gas supply line connected from the liquefied gas storage tank to a high pressure consumer; And a low-pressure liquefied gas supply line branched from the liquefied gas supply line and connected to a low-pressure consumer.

Specifically, the condenser may be provided upstream of a point at which the low-pressure liquefied gas supply line is branched from the liquefied gas supply line.

Specifically, the liquefied gas supply unit, a forced vaporizer provided in the low pressure liquefied gas supply line; A gas-liquid separator provided downstream of the forced vaporizer in the low pressure liquefied gas supply line; And a heater provided downstream of the gas-liquid separator in the low pressure liquefied gas supply line.

Specifically, the forced vaporizer may forcibly vaporize the liquefied gas heat-exchanged with the evaporation gas in the condenser.

Specifically, a boil-off gas supply unit for delivering boil-off gas from the liquefied gas storage tank to the customer; And it may further include a boil-off gas recovery unit for returning at least a portion of the boil-off gas delivered to the customer to the liquefied gas storage tank.

Specifically, the boil-off gas supply unit includes an boil-off gas supply line connected from the liquefied gas storage tank to a low-pressure consumer, and the boil-off gas recovery unit is branched from the boil-off gas supply line and connected to the liquefied gas storage tank. It may include a boil-off gas recovery line.

Specifically, the condenser may be provided in the liquefied gas supply line and the boil-off gas recovery line.

A gas treatment system according to an aspect of the present invention includes: a liquefied gas supply line connected from a liquefied gas storage tank to a high pressure consumer; A low-pressure liquefied gas supply line branched from the liquefied gas supply line and connected to a low-pressure consumer; And a condenser provided in the liquefied gas supply line upstream from a point at which the low-pressure liquefied gas supply line is branched and condenses the boil-off gas of the liquefied gas storage tank with liquefied gas.

Specifically, a boil-off gas supply line connected from the liquefied gas storage tank to a low-pressure consumer; And a boil-off gas recovery line branched from the boil-off gas supply line and connected to the liquefied gas storage tank.

Specifically, the condenser may be provided in the liquefied gas supply line and the boil-off gas recovery line.

A ship according to an embodiment of the present invention is characterized by having the gas treatment system.

In the gas treatment system and ship according to the present invention, after the boil-off gas generated in the liquefied gas storage tank is condensed by heat exchange with the liquefied gas while passing through a condenser, it is returned to the liquefied gas storage tank to prevent overpressure of the liquefied gas storage tank Can prevent and not waste evaporation gas.

1 is a conceptual diagram of a gas treatment system according to a first embodiment of the present invention.
2 is a partial conceptual diagram of a gas treatment system according to a first embodiment of the present invention.
3 is a pressure-temperature graph of liquefied gas in the gas treatment system according to the first embodiment of the present invention.
4 is a conceptual diagram of a gas treatment system according to a second 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 related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, a gas treatment system of the present invention will be described, and the present invention includes a gas treatment system and a ship having the same.

Hereinafter, in the present specification, the liquefied gas may be used to encompass all gaseous fuels generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, etc., and boil-off gas (BOG) is natural vaporization or It may mean forced vaporized liquefied gas. However, the boil-off gas may be used to mean not only a gaseous boil-off gas but also a liquefied boil-off gas.

In addition, in the present specification hereinafter, both decompression and expansion are used to lower the pressure, and are used interchangeably. In other words, decompression can be interpreted as expansion, whereas expansion can be interpreted as decompression.

In addition, hereinafter, the high and low pressures may be relative and may not be limited to absolute values, and of course, the high and low pressures may be replaced by main and auxiliary, first and second, and the like.

In addition, hereinafter, it is noted that the vent includes both discharged to the atmosphere or draining to a separate tank, etc., and can be interpreted as a term encompassing all flows that deviate from the flow in a specific line.

1 is a conceptual diagram of a gas processing system according to a first embodiment of the present invention, FIG. 2 is a partial conceptual diagram of a gas processing system according to a first embodiment of the present invention, and FIG. 3 is a first embodiment of the present invention. It is a pressure-temperature graph of the liquefied gas in the gas treatment system according to.

1 and 2, the gas treatment system 1 according to the first embodiment of the present invention includes a liquefied gas storage tank 10, a liquefied gas supply unit 20, a boil-off gas supply unit 30, and a boil-off gas. It includes a recovery unit 40, a condenser 50, a condenser bypass unit 60, an oil supply unit 70, and a control unit 90.

The liquefied gas storage tank 10 stores liquefied gas. The stored liquefied gas may be supplied to and consumed by the consumer 100, where the consumer 100 may be a propulsion engine (or turbine) for a ship, and does not limit high pressure, medium pressure, low pressure, and the like.

The consumer 100 may be provided in plural, and may include a high pressure consumer 101 and a low pressure consumer 103. The high pressure consumer 101 may be a ME-GI engine having a required pressure of 200 to 400 bar or an XDF engine having a required pressure of 15 to 50 bar, and the low pressure consumer 103 may be a DFDE engine having a required pressure of about 10 bar, etc. have. Of course, the XDF engine may be referred to as a separate medium-pressure consumer 100 that is separated from the high-pressure consumer 101.

For reference, a gas valve train 102 is provided upstream of the high pressure consumer 101 to control the supply of liquefied gas, and a gas valve unit 104 is provided upstream of the low pressure consumer 103 to supply liquefied gas, etc. Can be adjusted.

In addition, the demand destination 100 may be a boiler (BLR), a gas combustion device (GCU), or the like, city gas provided on a ship or on land, or an engine (or turbine) for various purposes. That is, the consumer 100 comprehensively refers to all configurations that consume the liquefied gas or the boil-off gas of the liquefied gas storage tank 10.

The liquefied gas storage tank 10 should store the liquefied gas in a liquid state. At this time, the liquefied gas storage tank 10 may store the liquefied gas at a pressure of 1 bar to 10 bar (for example, 1.03 bar).

The liquefied gas storage tank 10 may be a standalone type, a membrane type, etc., and various insulating structures may be used to store the liquefied gas in a liquid state, and the boil-off gas generated in the liquefied gas storage tank 10 will be described later. It can be processed by the boil-off gas compressor (32).

A pressure gauge 11 may be provided in the liquefied gas storage tank 10, and the internal pressure of the liquefied gas storage tank 10 measured by the pressure gauge 11 may be utilized for control of the controller 90.

Since the liquefied gas is stored in the liquefied gas storage tank 10, the boil-off gas from which the liquefied gas is naturally evaporated is continuously generated in the liquefied gas storage tank 10. At this time, if the boil-off gas is not taken out, the internal pressure of the liquefied gas storage tank 10 may be excessive, and thus the boil-off gas generated in the liquefied gas storage tank 10 may be condensed by the condenser 50 and returned. Therefore, the internal pressure of the liquefied gas storage tank 10 is maintained at an appropriate level.

The liquefied gas supply unit 20 delivers the liquefied gas from the liquefied gas storage tank 10 to the customer 100. The liquefied gas supply unit 20 can deliver the liquefied gas to the high-pressure consumer 101 and the low-pressure consumer 103, and in order to deliver the liquefied gas to the high-pressure consumer 101, the liquefied gas supply unit 20 is provided with a liquefied gas supply line ( 21), a liquefied gas pump 22, and may include a liquefied gas heat exchanger 23.

The liquefied gas supply line 21 is connected from the liquefied gas storage tank 10 to the high-pressure consumer 101. The liquefied gas supply line 21 may have one end provided inside the liquefied gas storage tank 10, and a boosting pump 211 may be provided at one end of the liquefied gas supply line 21.

A liquefied gas pump 22 and a liquefied gas heat exchanger 23 may be sequentially provided in the liquefied gas supply line 21. After the liquefied gas is discharged from the liquefied gas storage tank 10 along the liquefied gas supply line 21, the liquefied gas pump 22 is pressurized to a high pressure and the liquefied gas heat exchanger 23 requires the high pressure consumer 101 After being heated to temperature, it is delivered to the high pressure consumer 101 through the gas valve train 102.

The liquefied gas supply line 21 may be provided with a valve (not shown) for controlling a flow rate or pressure, and the opening degree of the valve may be controlled by the controller 90.

The liquefied gas pump 22 is provided in the liquefied gas supply line 21 and pressurizes the liquefied gas to a high pressure. The pressure at which the liquefied gas pump 22 pressurizes the liquefied gas may vary according to the required pressure of the customer 100.

The liquefied gas pump 22 is provided downstream of the boosting pump 211 in the liquefied gas supply line 21, and the liquefied gas pump 22 receives the liquefied gas pressurized to a low pressure by the boosting pump 211 and converts it to a high pressure. You can pressurize. At this time, the pressure of the liquefied gas flowing into the liquefied gas pump 22 may correspond to the required pressure of the low-pressure consumer 103.

The liquefied gas heat exchanger 23 is provided downstream of the liquefied gas pump 22 in the liquefied gas supply line 21. The liquefied gas heat exchanger 23 may heat the liquefied gas using a heat medium.

A heat medium circulation line 231 may be connected to the liquefied gas heat exchanger 23, and a heat medium pump 232 for pumping heat medium and a heat medium heater 233 for heating the heat medium with a heat source such as steam. ) May be provided, and a heat medium tank 234 for temporarily storing the fruit passed through the liquefied gas heat exchanger 23 may also be provided in the heat medium circulation line 231.

At this time, the heat medium circulation line 231 may have a parallel structure at least partially so that at least some of the heat medium bypasses the heat medium heater 233, and the heat medium pump 232 may be provided in parallel to back up each other.

Of course, since the heat medium used in the liquefied gas heat exchanger 23 is not particularly limited, the configuration for transferring the heat medium to the liquefied gas heat exchanger 23 is also not limited to the above-described configurations.

The liquefied gas supply unit 20 may further include a low-pressure liquefied gas supply line 24, a forced vaporizer 25, a gas-liquid separator 26, and a heater 27 to deliver the liquefied gas to the low-pressure consumer 103. have. The forced vaporizer 25, the gas-liquid separator 26, and the heater 27 provided in the low-pressure liquefied gas supply line 24 include a liquefied gas pump 22 and a liquefied gas heat exchanger provided in the liquefied gas supply line 21 (23) can be provided in parallel.

The low-pressure liquefied gas supply line 24 is branched from the liquefied gas supply line 21 and is connected to a low-pressure consumer 103. The low pressure liquefied gas supply line 24 may be branched from the liquefied gas supply line 21 upstream of the liquefied gas pump 22.

The boosting pump 211 can pressurize the liquefied gas up to the required pressure of the low-pressure consumer 103, and the low-pressure liquefied gas supply line 24 is a low-pressure consumer without additional pressurization of the liquefied gas pressurized by the boosting pump 211. Can be passed to (103).

The low pressure liquefied gas supply line 24 may be branched from the liquefied gas supply line 21 upstream of the condenser 50. The low-pressure consumer 103 can basically consume boil-off gas and supplementally consume liquefied gas. When the liquefied gas is supplied along the low-pressure liquefied gas supply line 24, it means that the boil-off gas is insufficient. can do.

At this time, the boil-off gas may not flow through the condenser 50, but if the liquefied gas flows to the condenser 50, there is a risk that the condenser 50 may be damaged due to thermal deviation in the condenser 50. Therefore, in this embodiment, the low-pressure liquefied gas supply line 24 is branched upstream of the condenser 50, and when the boil-off gas is insufficient (if the boil-off gas does not flow in the condenser 50), the liquefied gas passes the condenser 50 It can be delivered to the low pressure consumer 103 without going through.

Of course, there is a concern that the liquefied gas delivered to the high-pressure consumer 101 passes through the condenser 50, but in this embodiment, as the liquefied gas bypasses the condenser 50, the boil-off gas in the condenser 50 When it does not flow, the condenser 50 can be protected by preventing cryogenic liquefied gas from flowing through the condenser 50.

The forced vaporizer 25 is provided in the low pressure liquefied gas supply line 24 and forcibly vaporizes the liquefied gas. The forced vaporizer 25 may heat the liquefied gas to a temperature higher than the boiling point by using the heat medium or various heat sources mentioned in the liquefied gas heat exchanger 23.

The forced vaporizer 25 may heat the liquefied gas to about -100 degrees. This is a temperature higher than the boiling point of the liquefied gas, but may be less than the temperature required by the low pressure consumer 103. The forced vaporizer 25 heats the liquefied gas to such a temperature to control the methane number.

For example, when the liquefied gas is liquefied natural gas, the liquefied gas contains heavy carbon such as propane and butane in addition to methane. Since the boiling point of butane and heavy carbon does not exceed -100 degrees, the forced vaporizer 25 can heat the liquefied gas so that only methane and nitrogen are changed into a gas phase while the heavy carbon remains in a liquid state.

In this case, only a part of the liquefied gas passing through the forced vaporizer 25 becomes a gaseous state, and the rest (heavy carbon) may remain in a liquid state. At this time, the components remaining in the liquid state may be separated in the gas-liquid separator 26.

The gas-liquid separator 26 is provided downstream of the forced vaporizer 25 in the low pressure liquefied gas supply line 24. The gas-liquid separator 26 can separate heavy carbon remaining in a liquid state from the liquefied gas heated in the forced vaporizer 25, and the separated heavy carbon is returned to the liquefied gas storage tank 10, or a separate customer It can be passed to 100 and consumed.

A high-pressure liquefied gas delivery unit 28 is connected to the gas-liquid separator 26, so that a high-pressure liquefied gas having a high methane number can be delivered. The high-pressure liquefied gas delivery unit 28 will be described later.

The heater 27 is provided downstream of the gas-liquid separator 26 in the low-pressure liquefied gas supply line 24. As described above, the forced vaporizer 25 is heated to vaporize the liquefied gas, but can be heated to a temperature that is less than the required temperature of the low-pressure consumer 103 in order to separate heavy carbon. Accordingly, the heater 27 can raise the liquefied gas from which the heavy carbon is separated by the gas-liquid separator 26 to the required temperature of the low pressure consumer 103.

The heat source used in the heater 27 may be a heat source used in the forced vaporizer 25 or a heat source used in the liquefied gas heat exchanger 23. That is, components requiring a heat source in the present embodiment may share the heat source with each other. Of course, in the present invention, the type or whether or not to share the heat source is not particularly limited.

The liquefied gas supply unit 20 may further include a high-pressure liquefied gas delivery unit 28. The high-pressure liquefied gas delivery unit 28 delivers at least a portion of the liquefied gas pressurized by the liquefied gas pump 22 to the gas-liquid separator 26.

The low pressure consumer 103 may be a consumer 100 whose operation efficiency varies depending on the methane number, such as a DFDE engine. That is, the low-pressure consumer 103 may have a preferable configuration to consume a gas having a high methane number.

The low-pressure consumer 103 may basically be operated by consuming boil-off gas, and may be operated by supplementingly consuming liquefied gas. However, due to factors such as a decrease in the storage amount of the liquefied gas stored in the liquefied gas storage tank 10, the liquefied gas supplied along the boil-off gas and the low-pressure liquefied gas supply line 24 is the amount of the gas supplied to the low-pressure consumer 103. You may not have enough methane number.

Accordingly, in this embodiment, the methane number can be adjusted by mixing the high-pressure liquefied gas with the boil-off gas. That is, the high-pressure liquefied gas can be delivered to the low-pressure consumer 103 through the gas-liquid separator 26.

To this end, the high-pressure liquefied gas delivery unit 28 may include a high-pressure liquefied gas delivery line 281 connected from the liquefied gas supply line 21 to the gas-liquid separator 26 or the low-pressure liquefied gas supply line 24. .

The high-pressure liquefied gas from the liquefied gas supply line 21 may be delivered to the low-pressure liquefied gas supply line 24 through the high-pressure liquefied gas delivery line 281. In this case, the methane number of the gas supplied to the low pressure customer 103 may be adjusted upward by the high pressure liquefied gas.

The high-pressure liquefied gas delivery line 281 may be connected from the liquefied gas supply line 21 to the gas-liquid separator 26 at the downstream of the liquefied gas pump 22, and at least one of the upstream and downstream of the liquefied gas heat exchanger 23 At one side, it may be connected from the liquefied gas supply line 21 to the gas-liquid separator 26.

When the high-pressure liquefied gas delivery line 281 delivers the high-pressure, high-temperature liquefied gas to the gas-liquid separator 26 downstream of the liquefied gas heat exchanger 23, the load of the heater 27 may be reduced. However, there is a concern that heavy carbon may be vaporized as the high-temperature liquefied gas flows into the gas-liquid separator 26. To prevent this, the high-pressure liquefied gas delivery line 281 is a low-pressure liquefied gas supply line downstream of the gas-liquid separator 26. Of course it can be connected to (24).

However, the high-pressure liquefied gas may be pressurized by the liquefied gas pump 22 according to the pressure required by the high-pressure consumer 101. Accordingly, the liquefied gas pressure reducing valve 282 may be provided in the high-pressure liquefied gas delivery line 281.

The liquefied gas pressure reducing valve 282 can reduce the liquefied gas pressurized to a high pressure by the liquefied gas pump 22 in accordance with the required pressure of the low pressure consumer 103. That is, the liquefied gas pressure reducing valve 282 can reduce the liquefied gas by a difference between the pressure required by the high pressure consumer 101 and the pressure demanded by the low pressure consumer 103.

When the high-pressure liquefied gas delivery line 281 is connected to the gas-liquid separator 26 before and after the liquefied gas heat exchanger 23, the liquefied gas pressure reducing valve 282 supplies liquefied gas upstream of the liquefied gas heat exchanger 23 The high-pressure liquefied gas delivery line 281 branched from the line 21 and the high-pressure liquefied gas delivery line 281 branched from the liquefied gas supply line 21 downstream of the liquefied gas heat exchanger 23 may be provided, respectively. .

In this way, the high-pressure liquefied gas delivery unit 28 controls the methane number of the gas supplied to the low-pressure consumer 103 by delivering the high-pressure liquefied gas to the low-pressure consumer 103 after decompression, thereby improving the operation efficiency of the low-pressure consumer 103 Can be guaranteed. In addition, when the high-pressure liquefied gas delivery unit 28 uses an expander (not shown) when lowering the pressure of the high-pressure liquefied gas, power generation may be possible.

The boil-off gas supply unit 30 delivers the boil-off gas of the liquefied gas storage tank 10 to the customer 100. As described above, in the liquefied gas storage tank 10, evaporated gas naturally vaporized due to factors such as heat penetration from the outside is present.

At this time, the boil-off gas may be discharged from the liquefied gas storage tank 10 and supplied to the low-pressure consumer 103, and therefore, the internal pressure of the liquefied gas storage tank 10 may be maintained at an appropriate level. To this end, the boil-off gas supply unit 30 includes a boil-off gas supply line 31, a boil-off gas compressor 32, and a boil-off gas preheater 33.

The boil-off gas supply line 31 is connected from the liquefied gas storage tank 10 to the low-pressure consumer 103. The boil-off gas supply line 31 can deliver the boil-off gas generated in the liquefied gas storage tank 10 to the low-pressure consumer 103, and the boil-off gas supply line 31 includes a boil-off gas preheater 33 and an boil-off gas compressor 32. ) Can be provided in series.

The low pressure liquefied gas supply line 24 may be connected to the boil-off gas supply line 31. That is, the low-pressure liquefied gas that has passed through the forced vaporizer 25, the gas-liquid separator 26 and the heater 27 may be joined to the boil-off gas compressed by the boil-off gas compressor 32 and supplied to the low-pressure consumer 103.

The boil-off gas recovery line 41 of the boil-off gas recovery unit 40 may be connected upstream of the low-pressure consumer 103 from the boil-off gas supply line 31. The boil-off gas recovery line 41 receives the excess boil-off gas that cannot be consumed by the low-pressure consumer 103 from among boil-off gas supplied to the low-pressure consumer 103 along the boil-off gas supply line 31, and receives the liquefied gas storage tank. You can go back to (10). The boil-off gas recovery unit 40 will be described later.

The boil-off gas compressor 32 is provided in the boil-off gas supply line 31 and compresses the boil-off gas. A plurality of boil-off gas compressors 32 may be provided in series and configured in multiple stages, and/or a plurality of boil-off gas compressors 32 may be provided in parallel and may be provided to enable backup of each other.

The boil-off gas compressor 32 can compress the boil-off gas up to the required pressure of the low-pressure consumer 103. However, when the boil-off gas is compressed, the volume may expand as the boil-off gas is heated by the compression heat, and an intermediate cooler (not shown) may be provided downstream of the boil-off gas compressor 32 to prevent this. The intermediate cooler may be provided for each downstream of the plurality of boil-off gas compressors 32 provided in multiple stages.

The boil-off gas compressed by the boil-off gas compressor 32 is delivered to the low-pressure consumer 103. The boil-off gas at the downstream of the boil-off gas compressor 32 is mixed with the low-pressure liquefied gas and then supplied to the low-pressure consumer 103. have.

However, since the temperature of the boil-off gas supplied to the low-pressure consumer 103 may not meet the required temperature of the low-pressure consumer 103 due to mixing of the low-pressure liquefied gas, compression heat, or cooling by an intermediate cooler, the low-pressure consumer 103 ) Upstream of the boil-off gas supply line 31 is provided with an boil-off gas heater (not shown) to adjust the temperature of the boil-off gas to the required temperature of the low-pressure consumer 103.

A boil-off gas return line 321 may be provided in the boil-off gas supply line 31 so that some boil-off gas is returned to the upstream of the boil-off gas compressor 32 from the downstream side of the boil-off gas compressor 32. The boil-off gas return line 321 may adjust the flow rate of the boil-off gas supplied to the low-pressure consumer 103 among boil-off gas compressed by the boil-off gas compressor 32.

In addition, the boil-off gas compressor 32 may be capable of controlling unloading to lower the compression load, and may adjust the suction amount of the boil-off gas using an inlet guide vane or the like. This control may be performed by the control unit 90 to be described later.

The boil-off gas preheater 33 preheats the boil-off gas. The boil-off gas preheater 33 may be provided upstream of the boil-off gas compressor 32 to preheat boil-off gas discharged from the liquefied gas storage tank 10 and flowing into the boil-off gas compressor 32, wherein the heat source is a heater 27 ) Or a heat source used in the forced vaporizer 25 or the liquefied gas heat exchanger 23, or a separate heat source.

For example, the boil-off gas preheater 33 may receive at least a portion of the boil-off gas compressed by the boil-off gas compressor 32 to preheat the boil-off gas delivered to the boil-off gas compressor 32. That is, the boil-off gas preheater 33 may be a boil-off gas heat exchanger for exchanging boil-off gas before compression with compressed boil-off gas.

The boil-off gas recovery unit 40 returns at least a part of the boil-off gas delivered to the consumer 100 (especially the low pressure consumer 103) to the liquefied gas storage tank 10. The boil-off gas recovery unit 40 returns the excess boil-off gas that cannot be consumed by the customer 100 among the boil-off gas supplied to the low-pressure consumer 103 by the boil-off gas supply unit 30 to the liquefied gas storage tank 10 I can make it.

To this end, the boil-off gas recovery unit 40 may include a boil-off gas recovery line 41 branched from the boil-off gas supply line 31 and connected to the liquefied gas storage tank 10. The boil-off gas recovery line 41 may be branched from the boil-off gas supply line 31 downstream of the boil-off gas compressor 32, for example, the low-pressure liquefied gas supply line 24 joins the boil-off gas supply line 31 It can be branched from the boil-off gas supply line 31 at the downstream of the point.

Since the boil-off gas recovered along the boil-off gas recovery line 41 is compressed by the boil-off gas compressor 32, the pressure may be higher than that of the liquefied gas storage tank 10 and the temperature may be higher. At this time, when the boil-off gas is returned to the liquefied gas storage tank 10 without separate treatment, the internal pressure of the liquefied gas storage tank 10 may increase and the amount of boil-off gas generated may increase.

However, the boil-off gas recovery line 41 is provided with a condenser 50 to be described later, and the boil-off gas flowing along the boil-off gas recovery line 41 is recovered in the liquefied gas storage tank 10 at a low temperature. It is possible to prevent an increase in the internal pressure of the liquefied gas storage tank 10 according to the recovery of.

The boil-off gas delivery line 45 may be branched to the boil-off gas recovery line 41. The boil-off gas recovery line 41 is connected to the liquefied gas storage tank 10 to supply the condensed boil-off gas to the liquefied gas storage tank 10, but if the condensation of the boil-off gas is not sufficiently performed in the condenser 50 When the boil-off gas is recovered to the liquefied gas storage tank 10, the pressure of the liquefied gas storage tank 10 may increase.

The case that the condensation of the boil-off gas is not sufficiently performed in the condenser 50 may be a case in which the flow rate of the liquefied gas supplied to the condenser 50 is insufficient, and this may be due to a low load of the high-pressure consumer 101 or , This may occur when the high pressure consumer 101 is operated with oil.

At this time, in this embodiment, in order to prevent the flow of the liquefied gas from flowing into the condenser 50 from being sufficiently condensed in the condenser 50 from flowing into the liquefied gas storage tank 10, at least some It is possible to put a boil-off gas delivery line 45 for delivering the boil-off gas to the low-pressure consumer 103.

The boil-off gas delivery line 45 is branched from at least one of the upstream and downstream of the condenser 50 in the boil-off gas recovery line 41 and may be connected to the boil-off gas supply line 31. Since the boil-off gas delivery line 45 may be connected to a downstream point at which the boil-off gas recovery line 41 is branched from the boil-off gas supply line 31, the boil-off gas delivered by the boil-off gas delivery line 45 is a condenser ( 50) can be consumed in the low pressure consumer 103 without re-inflow.

The boil-off gas delivery line 45 may be provided with a valve (not shown) whose opening degree is controlled by the control unit 90, and the control unit 90 is the flow rate of the boil-off gas flowing into the condenser 50 (liquefied gas The flow rate of the boil-off gas in the storage tank 10, the internal pressure of the liquefied gas storage tank 10, the load of the low-pressure consumer 103, etc.) and the flow rate of the liquefied gas flowing into the condenser 50 (liquefied gas Based on the liquefied gas flow rate of the storage tank 10, the load of the high pressure consumer 101, etc.), it is possible to open the boil-off gas delivery line 45 by grasping that sufficient condensation of the boil-off gas does not occur.

Alternatively, the controller 90 may open the boil-off gas delivery line 45 when it is determined that the temperature of the boil-off gas has not been sufficiently lowered by sensing the temperature of the boil-off gas downstream of the condenser 50. Prior to control through the flow rate may be pre-control, and control through temperature may be post control.

When the boil-off gas recovery unit 40 connected to the liquefied gas storage tank 10 returns the condensed boil-off gas to the liquefied gas storage tank 10, the liquid level of the liquefied gas stored in the liquefied gas storage tank 10 is It can be returned to the upper and lower sides as a standard.

To this end, the boil-off gas recovery unit 40 may have an upper recovery unit 42 and a lower recovery unit 43. The upper recovery unit 42 has an upper recovery line 42 connected from the boil-off gas recovery line 41 to the upper side of the liquefied gas storage tank 10, and collects the condensed boil-off gas from the liquefied gas storage tank 10. It can be injected from the upper side of the liquefied gas.

When the gas-liquid separator 44 for separating the condensed boil-off gas is provided, the upper recovery unit 42 may inject a liquid component separated from the condensed boil-off gas. Since the liquid component is in a cryogenic state, it can be liquefied by lowering the temperature of the boil-off gas present in the liquefied gas storage tank 10 while being injected from the upper side of the liquefied gas storage tank 10.

That is, the upper recovery unit 42 may liquefy the boil-off gas in the liquefied gas storage tank 10 by using the liquefied boil-off gas.

The lower recovery unit 43 has a lower recovery line 43 connected from the boil-off gas recovery line 41 to the lower side of the liquefied gas storage tank 10, and collects the condensed boil-off gas from the liquefied gas storage tank 10. It can be delivered in liquefied gas.

When the gas-liquid separator 44 for separating the condensed boil-off gas is provided, the lower recovery unit 43 may deliver the gas component separated from the condensed boil-off gas. The gas component is cooled by the condenser 50, but may be in a less liquefied state, and the lower recovery unit 43 injects the vaporized gas of the gas component into the liquefied gas of the liquefied gas storage tank 10, The vaporized gas of the gas component can be completely liquefied by the liquefied gas in the storage tank 10.

That is, the lower recovery unit 43 may liquefy the boil-off gas that has not been liquefied in the condenser 50 by using the liquefied gas in the liquefied gas storage tank 10.

The boil-off gas recovery unit 40 may include a gas-liquid separator 44, and the gas-liquid separator 44 is provided in the boil-off gas recovery line 41 to separate the boil-off gas condensed by the condenser 50 into a gas-liquid separation. At this time, the gas component can be liquefied by being injected into the liquefied gas from the lower side of the liquefied gas storage tank 10 by the lower recovery unit 43, and the liquid component is the liquefied gas storage tank 10 by the upper recovery unit 42. The boil-off gas in the liquefied gas storage tank 10 may be liquefied while being sprayed from the upper side of

Accordingly, in this embodiment, when the condensed boil-off gas is recovered, gas-liquid separation and supply to the inside and outside of the liquefied gas can be greatly improved, and the internal pressure of the liquefied gas storage tank 10 can be stabilized.

The condenser 50 (in this specification, the condenser 50 can be interpreted as a re-liquefaction device) is provided in the liquefied gas supply unit 20 and the boil-off gas recovery unit 40, and is a liquefied gas storage tank as liquefied gas ( The boil-off gas of 10) is condensed. The condenser 50 includes a liquefied gas flow path 51 connected to the liquefied gas supply line 21 of the liquefied gas supply unit 20 and a boil-off gas connected to the boil-off gas recovery line 41 of the boil-off gas recovery unit 40 It may have a flow path 52, and may have a structure having at least two or more flow paths.

The condenser 50 may be provided downstream from the point where the low-pressure liquefied gas supply line 24 branches off from the liquefied gas supply line 21. That is, the condenser 50 may be provided downstream from a point at which the liquefied gas diverges from the liquefied gas supply unit 20 to the plurality of consumers 100.

This is because, as described above, when the liquefied gas flows along the low-pressure liquefied gas supply line 24, an excess of the boil-off gas does not occur, so that there is no flow of the boil-off gas in the condenser 50, so that the cryogenic liquefied gas is This is to prevent a situation such as damage to the condenser 50 due to heat deviation due to the flow into 50.

That is, when there is an excess of boil-off gas (if there is (almost) no flow in the low-pressure liquefied gas supply line 24), the condenser 50 exchanges the excess boil-off gas with the liquefied gas flowing to the liquefied gas pump 22. I can make it. However, if there is no excess boil-off gas (if there is a flow in the low-pressure liquefied gas supply line 24), the condenser 50 does not (almost) receive the excess boil-off gas, so the liquefied gas is also not delivered. This can eliminate the risk of damage.

However, the liquefied gas flowing along the low-pressure liquefied gas supply line 24 does not pass through the condenser 50, so it is not a problem, but the liquefied gas delivered to the high-pressure consumer 101 through the liquefied gas pump 22 is Regardless of whether or not, thermal deviation may occur when passing through the capacitor 50. However, in the present invention, a capacitor bypass part 60 may be provided to solve this problem, which will be described later.

The condenser 50 condenses the excess boil-off gas into the liquefied gas delivered to the liquefied gas pump 22, and the liquefied gas heated while passing through the condenser 50 may flow into the liquefied gas pump 22.

In this case, when the liquefied gas is pressurized by the liquefied gas pump 22, some of the liquefied gas is vaporized, and there is a concern that cavitation may occur. Accordingly, the present embodiment can implement an anti-cavitation mode for controlling the temperature of the liquefied gas flowing into the liquefied gas pump 22 through the condenser 50 using the control unit 90 to be described later. This will be described later.

A purging part 53 may be provided in the capacitor 50 as shown in FIG. 2. The purging part 53 may remove liquefied gas and evaporation gas remaining in the condenser 50. The condenser 50 can operate to condense the boil-off gas into liquefied gas when excess boil-off gas is generated. Even if there is no inflow of boil-off gas and liquefied gas to the condenser 50 because the excess boil-off gas is not generated, the condenser Boil-off gas and liquefied gas may remain in (50).

If, for maintenance of the condenser 50, the liquefied gas flow path 51 and the boil-off gas flow path 52 of the condenser 50 must be separated from the liquefied gas supply line 21 and the boil-off gas recovery line 41 and opened to the outside. In this case, it is essential to remove the gases remaining in the condenser 50 to prevent the occurrence of an accident.

Therefore, the purging unit 53 can supply the purging gas to the condenser 50 and take out the liquefied gas and the boil-off gas together with the purging gas, and for this purpose, the purging unit 53 includes the purging gas supply unit 531 and the vent Includes part 532.

The purging gas supply unit 531 has a purging gas supply line 531 connected to one side of the condenser 50, and supplies the purging gas to one side of the condenser 50. The purging gas is a gas without risk of explosion, and may be a gas such as nitrogen, air or inert gas.

The purging gas supply unit 531 may supply purging gas to the liquefied gas supply line 21 or the boil-off gas recovery line 41 from one side of the condenser 50. For example, the purging gas supply unit 531 may supply purging gas to the liquefied gas supply line 21 from the upstream side of the condenser 50 based on the flow of the liquefied gas. In addition, the purging gas supply unit 531 supplies the purging gas to the boil-off gas recovery line 41 from the upstream side of the condenser 50 based on the flow of the boil-off gas.

When the purging gas is injected into the condenser 50, the purging gas may push the liquefied gas and boil-off gas remaining in the liquefied gas flow path 51 and the boil-off gas flow path 52 to the other side of the condenser 50. At this time, the liquefied gas and the boil-off gas exiting to the other side of the condenser 50 together with the purging gas are vented to the outside by the vent unit 532.

The vent part 532 has a vent line 532 connected to the other side of the condenser 50, and vents the liquefied gas or the boil-off gas together with the purging gas from the other side of the condenser 50. The vent part 532 may vent a mixture gas of purging gas and liquefied gas exiting from the liquefied gas flow path 51 and/or a mixture gas of purging gas and boil-off gas exiting from the boil-off gas flow path 52 to the outside. .

At this time, the mixed gas may have explosive properties even if the non-explosive purging gas is mixed, and the vent part 532 delivers the mixed gas to a gas combustion device (not shown), so that the mixed gas is forcibly burned and then discharged. You can do it. Of course, the vent part 532 can discharge the mixed gas into the atmosphere without using a gas combustion device.

However, in order to prevent environmental pollution, the vent part 532 analyzes the components of the mixed gas, determines the specific gravity of the explosive material contained in the mixed gas, and then determines that the ratio of the explosive material is sufficiently low, then removes at least a part of the mixed gas from the outside. It can be simply discharged. That is, the vent part 532 may discharge the mixed gas to the gas combustion device and/or to the atmosphere according to the component of the mixed gas.

The vent part 532 may vent the liquefied gas or the boil-off gas together with the purging gas from the liquefied gas supply line 21 or the boil-off gas recovery line 41 from the other side of the condenser 50. As an example, the vent unit 532 may vent the liquefied gas together with the purging gas from the liquefied gas supply line 21 from the downstream side of the condenser 50 based on the flow of the liquefied gas, based on the flow of the boil-off gas. As a result, it is possible to vent the boil-off gas together with the purging gas from the boil-off gas recovery line 41 on the downstream side of the condenser 50.

Of course, the present invention does not limit the positions of the purging gas supply unit 531 and the vent unit 532 to the above. However, in the liquefied gas supply line 21 and the boil-off gas recovery line 41, the purging gas supply unit 531 and the vent unit 532 may be provided with the condenser 50 interposed therebetween. That is, unlike described above, the vent part 532 may be provided upstream of the condenser 50 based on the flow of liquefied gas/evaporation gas.

Through the configuration of the purging part 53, the condenser 50 can safely remove all of the explosive liquefied gas/evaporated gas remaining therein before maintenance. However, the purging part 53 is not operated only for maintenance of the condenser 50.

For example, the purging unit 53 may be operated even when only the liquefied gas flows through the condenser 50 because excess boil-off gas is not generated. That is, if the excess boil-off gas is not recovered through the boil-off gas recovery line 41, the cryogenic liquefied gas may cause thermal deviation in the condenser 50, and thus the condenser 50 may be damaged.

In this case, however, in this embodiment, the liquefied gas bypasses the condenser 50 or supplies a purging gas to the boil-off gas recovery line 41 using the purging unit 53, so that the purging gas The condenser 50 can be protected by allowing heat exchange. That is, in this embodiment, the cooling heat of the liquefied gas may not be transferred to the condenser 50 itself, but may be transferred to the purging gas.

At this time, the purging unit 53 may implement the supply and vent of the purging gas parallel to/reverse to the flow of the boil-off gas. However, when the purging gas is supplied opposite the flow of the boil-off gas in the boil-off gas recovery line 41, that is, the purging gas is injected from the downstream of the condenser 50 and flows along the upstream of the condenser 50, the boil-off gas supply line When joined to 31, the purging gas can be consumed at the low pressure consumer 103.

However, since the purging gas may be nitrogen or air, etc., when the purging gas is mixed with the boil-off gas and supplied to the low-pressure consumer 103, the methane number may be a problem. In this case, as described above, since the high-pressure liquefied gas can be supplemented with the boil-off gas directed to the low-pressure consumer 103, a decrease in the methane number can be prevented.

The condenser bypass unit 60 allows liquefied gas or boil-off gas to bypass the condenser 50. The condenser bypass unit 60 may include a condenser bypass line 61 connected from an upstream of the condenser 50 to a downstream of the condenser 50 in the liquefied gas supply line 21.

The condenser bypass line 61 may allow at least some of the liquefied gas delivered from the liquefied gas storage tank 10 to the liquefied gas pump 22 to bypass the condenser 50. A condenser bypass valve 611 may be provided in the condenser bypass line 61, and the opening degree of the condenser bypass valve 611 may be adjusted by the control unit 90.

When there is no excess boil-off gas flowing into the condenser 50 or the flow rate is not high, if the liquefied gas flows into the condenser 50 in a large amount compared to the boil-off gas, the cold heat of the cryogenic liquefied gas will damage the condenser 50. I can.

Therefore, in this embodiment, when it is detected that the excess boil-off gas has not (almost) flowed into the condenser 50, the liquefied gas bypasses the condenser 50 through the condenser bypass line 61 without passing through the condenser 50. Thus, it can be delivered to the liquefied gas pump 22.

That is, the opening of the condenser bypass line 61 may be performed by the control unit 90 depending on whether or not an excess of boil-off gas is sufficiently generated, and the excess boil-off gas is generated by the boil-off gas flow rate of the liquefied gas storage tank 10 Or, it may be detected through the internal pressure of the liquefied gas storage tank 10, the load of the low pressure demander 103, or the like.

The oil supply unit 70 supplies oil to the customer 100. The plurality of demanders 100 may be different fuel demanders 100 operated by gas or oil. That is, the consumer 100 may consume liquefied gas or boil-off gas, or may consume oil.

The oil supply unit 70 may supply oil to the high-pressure consumer 101 and the low-pressure consumer 103, and the like, in this case, the oil may mean a fluid placed in a liquid state at room temperature, such as HFO or DO.

The oil supply unit 70 includes an oil tank 71 and an oil supply line 72. The oil tank 71 is provided on a ship to store oil, and at least one oil tank 71 may be provided.

However, in order to prevent the viscosity of the oil from increasing, the oil tank 71 may maintain the temperature of the oil above a certain temperature by using the heat source described above or a separate heat source.

The oil supply line 72 is connected from the oil tank 71 to the customer 100, and supplies oil to the customer 100. The oil supply line 72 may be connected to the oil tank 71 at one end and branched into two or more while going to the other end to be connected to each of the plurality of customers 100.

An oil supply valve (not shown) may be provided in the oil supply line 72, and a separate oil supply valve is provided for each part branched from the oil supply line 72 to each customer 100, and each customer ( The flow rate of oil supplied to 100) can be adjusted.

When the customer 100 is operated by oil, exhaust containing a large amount of pollutants such as nitrogen oxide (NOx) and sulfur oxide (SOx) may be generated from the customer 100. Such exhaust can be purified through an exhaust gas recirculation system (EGR) or a denitration system (SCR), but it can be a problem in the case of a ship without a purification device, and even a ship with a purification device, it consumes a lot of power. There is a problem that it is consumed and the purification device must be operated.

In particular, in the case of a ship including an area to which emission regulation is applied on a navigation route, purification of the exhaust is essential when operating the area, and the above problems arise. However, in this embodiment, even if the purification device is not used, the consumer 100 is operated using liquefied gas or evaporated gas, so that the pollution degree of exhaust can be reduced.

However, whether the consumer 100 consumes gas or oil may be determined based on the amount of gas or oil stored, but in the case of the low pressure consumer 103 that consumes boil-off gas, the liquefied gas storage tank 10 When the flow rate of the generated boil-off gas is less than the required flow rate of the low-pressure consumer 103, it can be converted into oil and operated.

However, as described above, when the demander 100 operates with oil instead of gas, the pollution level of the exhaust may increase, and there is a concern that the exhaust regulation applied to a certain area may not be satisfied when the ship is operated.

Therefore, in this embodiment, in consideration of whether or not exhaust is regulated, the consumer 100 can be operated with gas instead of oil. That is, when the flow rate of the boil-off gas of the liquefied gas storage tank 10 is less than the required flow rate of the consumer 100, the consumer 100 is operated with oil, but in the region where the emission regulation is applied, the flow rate of the boil-off gas is the demand destination. When the flow rate is less than the required flow rate of (100), the consumer 100 can be operated by consuming liquefied gas instead of being converted to oil.

Such control may be implemented by the control unit 90, and will be described in detail in the course of describing the control unit 90 below.

The control unit 90 controls all components that can be controlled in the present invention. The controller 90 may control flow of various lines, control openings of valves provided in the lines, and control operating loads of components provided on the lines.

In addition, in the present invention, for the control of the control unit 90, various sensors for detecting the flow rate, temperature, pressure, etc. of the liquefied gas and/or the boil-off gas on the flow of the liquefied gas or the boil-off gas can be freely placed. Even if not, it is not limited to the absence of sensors.

First, the control unit 90 may control the capacitor bypass unit 60. The controller 90 may control the condenser bypass unit 60 according to the flow rate of the boil-off gas of the liquefied gas storage tank 10 so that the liquefied gas bypasses the condenser 50.

If the flow rate of the boil-off gas of the liquefied gas storage tank 10 is less than the reference value, and/or the internal pressure of the liquefied gas storage tank 10 is less than the reference value, the condenser 50 contains a sufficient amount of boil-off gas. The condenser bypass unit 60 may be controlled so that at least some of the liquefied gas bypasses the condenser 50 by the condenser bypass unit 60 as viewed as not being introduced.

If the flow rate of the boil-off gas flowing into the condenser 50 is not sufficient, it means that the excess boil-off gas is not generated. At this time, when the cryogenic liquefied gas flows into the condenser 50, the heat generated by the condenser 50 The risk of damage to the capacitor 50 increases due to the deviation.

Therefore, when the control unit 90 detects that the excess boil-off gas flow rate flowing along the boil-off gas recovery line 41 is less than the reference value, at least a portion of the liquefied gas bypasses the condenser 50 by the condenser bypass unit 60. You can do it.

At least some of the liquefied gas discharged from the liquefied gas storage tank 10 and flowing toward the condenser 50 flows along the condenser bypass line 61 as the control unit 90 controls the condenser bypass unit 60 It can be introduced into the pump 22. Therefore, when the inflow of the boil-off gas into the condenser 50 is insufficient, the control unit 90 can suppress the inflow of the liquefied gas into the condenser 50.

Accordingly, the control unit 90 can prevent in advance from occurring a problem such as damage to the condenser 50 or stop operation due to direct transfer of cold heat from the cryogenic liquefied gas to the condenser 50.

The control unit 90 may control the flow of the liquefied gas in the low-pressure liquefied gas supply line 24 according to the flow rate of the boil-off gas in the boil-off gas recovery unit 40. As described above, a point at which the low-pressure liquefied gas supply line 24 branches off from the liquefied gas supply line 21 may be upstream from a position where the condenser 50 is provided in the liquefied gas supply line 21.

If the excess boil-off gas does not flow into the condenser 50, this means that the flow rate of the boil-off gas delivered from the boil-off gas supply line 31 to the low-pressure consumer 103 is less than the required flow rate of the low-pressure consumer 103. I can.

Therefore, the control unit 90, when the flow rate of the boil-off gas in the boil-off gas recovery unit 40 is less than the reference value, at least a portion along the low-pressure liquefied gas supply line 24 so that the liquefied gas can be replenished to the low-pressure consumer 103 The liquefied gas can flow.

The remaining liquefied gas that does not flow to the low-pressure liquefied gas supply line 24 is transferred to the liquefied gas pump 22 through the condenser 50 or bypasses the condenser 50 to be transferred to the liquefied gas pump 22. I can. Even if the liquefied gas passes through the condenser 50, the boil-off gas may not flow into the condenser 50, and in this case, as mentioned above, the purging gas may be supplied to receive the cooling heat of the liquefied gas.

The control unit 90 may control the liquefied gas supply unit 20 according to the flow rate of the boil-off gas in the liquefied gas storage tank 10. That is, the controller 90 may control the flow of the liquefied gas supply line 21 (especially the low pressure liquefied gas supply line 24) according to the flow rate of the boil-off gas. At this time, the control unit 90 may consider whether or not to regulate the exhaust emission from the customer 100 together.

When the application of the exhaust regulation is confirmed and the boil-off gas flow rate of the liquefied gas storage tank 10 is less than the reference value (if the internal pressure of the liquefied gas storage tank 10 is less than the reference value), the control unit 90 is the liquefied gas supply unit 20 The liquefied gas may be delivered to the customer 100.

Here, the customer 100 may be a low pressure customer 103 operated by the boil-off gas. If the flow rate of the boil-off gas is insufficient, the customer 100 may be operated using oil. However, when the customer 100 is operated with oil, there is a concern that the pollution level of the exhaust increases compared to the case where the gas is operated with evaporation gas, and thus the exhaust regulation cannot be satisfied.

Accordingly, in this embodiment, in order to prevent the consumer 100 from converting to oil when the flow rate of the boil-off gas is insufficient, the liquefied gas may be delivered to the consumer 100 by the liquefied gas supply unit 20.

To this end, the control unit 90 may control the oil supply unit 70 while controlling the liquefied gas supply unit 20 according to whether or not exhaust is regulated. That is, when the application of the exhaust regulation is confirmed, the control unit 90 limits the supply of oil by the oil supply unit 70, and limits the flow rate of the boil-off gas delivered to the customer 100 among the required flow rates of the customer 100. Silver can be eliminated by supplying liquefied gas by the liquefied gas supply unit 20.

In this way, as the control unit 90 suppresses the oil operation of the customer 100 in consideration of the emission regulation, the ship equipped with this system always satisfies the emission regulation while operating in an area to which the emission regulation is applied. Can implement navigation.

The control unit 90 can control the operation of the boil-off gas supply unit 30. Specifically, the control unit 90 may set the tank pressure control mode and the anti-cavitation mode, and control the boil-off gas supply unit 30 accordingly.

The tank pressure control mode may be a mode for maintaining the internal pressure of the liquefied gas storage tank 10 in a predetermined range. Boil-off gas is continuously generated in the liquefied gas storage tank 10, and the generation of the boil-off gas increases the internal pressure of the liquefied gas storage tank 10.

At this time, only when the boil-off gas of an appropriate flow rate is discharged from the liquefied gas storage tank 10, the internal pressure of the liquefied gas storage tank 10 can be maintained at an appropriate level. Accordingly, the control unit 90 may set a tank pressure control mode for adjusting the internal pressure of the liquefied gas storage tank 10.

On the other hand, the anti-cavitation mode may be a mode in which cavitation does not occur in the liquefied gas pump 22 when the liquefied gas is introduced into the liquefied gas pump 22. The liquefied gas is transferred from the liquefied gas storage tank 10 to the liquefied gas pump 22 along the liquefied gas supply line 21, and the condenser 50 is in the liquefied gas supply line 21 upstream of the liquefied gas pump 22. ) Is provided, the liquefied gas may be heated by the boil-off gas and then introduced into the liquefied gas pump 22.

That is, when the temperature of the liquefied gas flowing into the liquefied gas pump 22 rises in the condenser 50, there is a greater concern that the liquefied gas is vaporized in the liquefied gas pump 22, which may lead to cavitation soon.

Therefore, the control unit 90 can set the anti-cavitation mode so that the temperature of the liquefied gas flowing into the liquefied gas pump 22 is less than the reference value, and the reference value is the pressurization of the liquefied gas in the liquefied gas pump 22 It may be a value set to suppress the occurrence of cavitation during time.

The control unit 90 may operate the boil-off gas supply unit 30 in a tank pressure control mode or an anti-cavitation mode according to the flow rate or temperature of the boil-off gas and the liquefied gas flowing into the condenser 50.

In the tank pressure control mode, the control unit 90 controls the flow rate of the boil-off gas received from the liquefied gas storage tank 10 by the boil-off gas supply unit 30 in order to maintain the internal pressure of the liquefied gas storage tank 10 in a certain range. I can.

For example, the control unit 90 may operate the boil-off gas compressor 32 in a tank pressure control mode. That is, the controller 90 adjusts the flow rate of the boil-off gas sucked by the boil-off gas compressor 32 by adjusting the inlet guide vane of the boil-off gas compressor 32 so that the internal pressure of the liquefied gas storage tank 10 is within a certain range. Can be kept as

Of course, the control unit 90 also controls the tank pressure through control such as adjusting the flow rate at which the boil-off gas is recovered upstream of the boil-off gas compressor 32 along the boil-off gas return line 321 from the downstream of the boil-off gas compressor 32. You can implement the adjustment mode. That is, in the tank pressure control mode, the control unit 90 can implement various controls such that the internal pressure of the liquefied gas storage tank 10 is maintained within a predetermined range.

On the other hand, the control unit 90 can adjust the flow rate of the boil-off gas flowing from the boil-off gas supply unit 30 to the condenser 50 in order to control the temperature of the liquefied gas flowing into the liquefied gas pump 22 in the anti-cavitation mode. have.

The control unit 90 may operate the boil-off gas compressor 32 in an anti-cavitation mode, and at this time, the inlet guide vane or the like may be controlled. And/or the controller 90 may perform various controls such as controlling the flow of the boil-off gas return line 321 in the anti-cavitation mode.

In the anti-cavitation mode, the control unit 90 may control the flow rate of the boil-off gas flowing into the condenser 50 through the boil-off gas recovery unit 40, which is a valve 411 provided in the boil-off gas recovery line 41. The opening of the can be achieved by adjustment.

In addition, the control unit 90 may control the temperature of the boil-off gas flowing into the condenser 50 together with or separately from the flow rate of the boil-off gas flowing into the condenser 50, and in this case, the cooling load in the intermediate cooler is controlled by the control unit. Can be adjusted by 90.

In this way, the control unit 90 can adjust the flow rate or temperature of the boil-off gas flowing into the condenser 50 in the anti-cavitation mode, so that the liquefied gas heat-exchanged in the condenser 50 does not generate cavitation. have. This is as shown in FIG. 3.

Referring to FIG. 3, when the control unit 90 operates the boil-off gas supply unit 30 in the anti-cavitation mode, the liquefied gas may be placed in a range within the dotted line indicated on the left side of the saturation line in FIG. 3. That is, since the liquefied gas has a pressure and a temperature at a position far from the saturation line to the left, cavitation can be suppressed in the liquefied gas pump 22.

As described above, in this embodiment, the boil-off gas can be recycled by condensing the boil-off gas using liquefied gas, and the system operation efficiency is increased and safety and stability are secured by providing configurations that efficiently implement the flow of the liquefied gas and boil-off gas. I can.

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

Referring to FIG. 4, in the gas treatment system 1 according to the second embodiment of the present invention, the position of the point where the low-pressure liquefied gas supply line 24 diverges from the liquefied gas supply line 21 is the first embodiment. Is different from

Hereinafter, descriptions will be made mainly on points that the present embodiment is different from other embodiments, and portions omitted from the description are replaced with descriptions in the first embodiment.

In this embodiment, the condenser 50 may be provided upstream of a point at which the liquefied gas is branched from the liquefied gas supply unit 20 to the plurality of customers 100. That is, the condenser 50 may be provided upstream of a point where the low-pressure liquefied gas supply line 24 branches off from the liquefied gas supply line 21.

In this case, unlike the first embodiment, the low pressure liquefied gas supply line 24 may receive the liquefied gas passing through the condenser 50. Accordingly, the forced vaporizer 25 provided in the low-pressure liquefied gas supply line 24 may forcibly vaporize the liquefied gas that has been heat-exchanged with the boil-off gas in the condenser 50.

Of course, in this embodiment, as in the previous embodiment, the problem of damage to the condenser 50 when the excess boil-off gas is not supplied to the condenser 50 may be solved by the condenser bypass unit 60.

However, in this embodiment, since the liquefied gas delivered to the forced vaporizer 25 may be heated by the boil-off gas, the load of the heat source used in the forced vaporizer 25 can be reduced.

When the liquefied gas is delivered to the forced vaporizer 25 placed in the low-pressure liquefied gas supply line 24, it means that the flow rate of the boil-off gas delivered to the low-pressure consumer 103 is insufficient. However, in this case, there may be no excess boil-off gas, and thus the boil-off gas may not flow into the condenser 50.

However, in this embodiment, although the flow rate of the boil-off gas delivered to the low-pressure consumer 103 along the boil-off gas supply line 31 exceeds the required flow rate of the low-pressure consumer 103, supplementation of the liquefied gas is required. It can be advantageous.

In this case, as a large amount of boil-off gas is generated in the liquefied gas storage tank 10, in a situation where an excess that the low-pressure consumer 103 cannot consume occurs, the amount exceeding the excess boil-off gas is generated by the condenser 50. It may be a case in which the internal pressure of the liquefied gas storage tank 10 needs to be sufficiently lowered by condensing and returning it to the liquefied gas storage tank 10.

In addition, if the methane number for increasing the operation efficiency of the low-pressure consumer 103 is not satisfied with the boil-off gas, the liquefied gas may be supplemented even if the flow rate of the boil-off gas is large, and at this time, the low-pressure liquefied gas supply line ( Liquefied gas and excess boil-off gas may flow into 24).

As described above, in this embodiment, when the liquefied gas needs to be replenished to the low-pressure consumer 103 while the excess boil-off gas is generated, the liquefied gas heated by the boil-off gas in the condenser 50 flows into the forced vaporizer 25. Thus, the load of the forced vaporizer 25 can be reduced.

Of course, in the present invention, the low-pressure liquefied gas supply line 24 can be branched both upstream and downstream of the condenser 50, but liquefied gas is transferred from the upstream of the condenser 50 to the forced vaporizer 25 depending on the situation. It may be introduced or flowed into the forced vaporizer 25 from the downstream of the condenser 50. The flow of the liquefied gas may be controlled by the controller 90.

In addition to the above-described embodiments, the present invention encompasses all embodiments generated by a combination of at least one embodiment and a known technology or a combination of at least two or more embodiments.

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, 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 10: liquefied gas storage tank
20: liquefied gas supply unit 21: liquefied gas supply line
22: liquefied gas pump 23: liquefied gas heat exchanger
24: low pressure liquefied gas supply line 25: forced vaporizer
26: gas-liquid separator 27: heater
28: high pressure liquefied gas delivery unit 30: boil-off gas supply unit
31: boil-off gas supply line 32: boil-off gas compressor
40: boil-off gas recovery unit 41: boil-off gas recovery line
45: boil-off gas delivery line 50: condenser
51: liquefied gas flow path 52: boil-off gas flow path
53: purging unit 60: condenser bypass unit
70: oil supply unit 90: control unit
100: customer

Claims (12)

A liquefied gas storage tank for storing liquefied gas;
A liquefied gas supply unit for delivering the liquefied gas from the liquefied gas storage tank to a plurality of customers;
A boil-off gas supply unit for delivering boil-off gas from the liquefied gas storage tank to the customer;
A boil-off gas recovery unit for returning at least a portion of the boil-off gas delivered to the customer to the liquefied gas storage tank; And
It is provided in the liquefied gas supply unit and includes a condenser for condensing the boil-off gas of the liquefied gas storage tank with liquefied gas,
The liquefied gas supply unit,
A liquefied gas supply line connected from the liquefied gas storage tank to a high pressure consumer;
A low-pressure liquefied gas supply line branched from the liquefied gas supply line and connected to a low-pressure consumer;
A forced vaporizer provided in the low pressure liquefied gas supply line;
A gas-liquid separator provided downstream of the forced vaporizer in the low pressure liquefied gas supply line; And
And a heater provided downstream of the gas-liquid separator in the low pressure liquefied gas supply line,
The boil-off gas supply unit,
And a boil-off gas supply line connected from the liquefied gas storage tank to the low-pressure consumer, and receiving forced vaporized liquefied gas from the low-pressure liquefied gas supply line,
The boil-off gas recovery unit,
A boil-off gas recovery line branched from the boil-off gas supply line to a point downstream of the point at which the low-pressure liquefied gas supply line is connected, and connected to the liquefied gas storage tank,
The capacitor,
A gas treatment system, characterized in that provided in the liquefied gas supply line upstream of a point at which the low-pressure liquefied gas supply line is branched, and provided in the liquefied gas supply line and the boil-off gas recovery line. delete delete delete delete delete delete delete A liquefied gas supply line connected from the liquefied gas storage tank to a high pressure consumer;
A low-pressure liquefied gas supply line branched from the liquefied gas supply line and connected to a low-pressure consumer;
A boil-off gas supply line connected from the liquefied gas storage tank to a low-pressure consumer, and receiving liquefied gas from the low-pressure liquefied gas supply line;
A boil-off gas recovery line branched from the boil-off gas supply line downstream of a point at which the low-pressure liquefied gas supply line is connected and connected to the liquefied gas storage tank;
A forced vaporizer provided in the low pressure liquefied gas supply line;
A gas-liquid separator provided downstream of the forced vaporizer in the low pressure liquefied gas supply line;
A heater provided downstream of the gas-liquid separator in the low pressure liquefied gas supply line; And
A condenser provided in the liquefied gas supply line upstream of a point at which the low-pressure liquefied gas supply line is branched, and provided in the liquefied gas supply line and the boil-off gas recovery line to condense the boil-off gas of the liquefied gas storage tank with liquefied gas Gas processing system comprising a. delete delete A ship comprising the gas treatment system of any one of claims 1 and 9.

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