KR102418128B1 - Fuel Supply System And Method For Ship - Google Patents

Abstract

A fuel supply system and method for a ship are disclosed. A fuel supply system for a ship of the present invention includes: a fuel supply tank provided in the ship and storing liquefied gas supplied to the engine in the ship; a fuel supply line through which liquefied gas is supplied from the fuel supply tank to the engine; a boosting pump provided in the fuel supply line and compressing the liquefied gas to a pressure required for the engine; a return line for recovering liquefied gas not consumed by the engine from the engine and recirculating it to an upstream of the boosting pump of the fuel supply line; a temperature controller provided in the fuel supply line for heating or cooling the liquefied gas according to a temperature required by the engine; and a bypass line branched from the fuel supply line downstream of the temperature controller and connected to the return line, wherein the high-temperature liquefied gas recovered from the engine and the liquefied gas passing through the temperature controller pass through the return line. It is characterized in that it is mixed with the low-temperature liquefied gas supplied from the fuel supply tank through the lubricating oil to prevent hardening of the lubricant in the fuel supply line.

Description

Fuel Supply System And Method For Ship

The present invention relates to a fuel supply system and method for a ship, and more particularly, in a ship using a liquefied gas such as LPG or NH3, while recirculating the remaining liquefied gas from an excess supply to the engine, the lubricating oil introduced from the engine It relates to a fuel supply system and method for a ship capable of preventing hardening or solidification.

The consumption of liquefied gas such as LNG (Liquefied Natural Gas) or LPG (Liquefied Petroleum Gas) is rapidly increasing worldwide. Liquefied gas is transported in a gaseous state through a gas pipeline on land or offshore, or stored in a liquefied gas carrier in a liquefied state and transported to a remote consumer. Liquefied gas such as LNG or LPG is obtained by cooling natural gas or petroleum gas to cryogenic temperatures (approximately -163°C in the case of LNG).

Although there is a difference in liquefaction temperature depending on the composition, petroleum gas containing propane as a main component has a liquefaction temperature of about -42°C at normal pressure, and can be stored in a liquid state up to a temperature of about 45°C at 18 bar and 20°C at 7 bar. do. Since LPG evaporates when the atmospheric pressure is higher than -42℃, the LPG storage tank of the ship is insulated. However, since external heat is continuously transferred to the LPG, the LPG is continuously vaporized in the LPG storage tank during the LPG transportation process, thereby generating boil-off gas in the LPG storage tank.

In LPG carriers, when BOG accumulates in the LPG storage tank, the pressure in the LPG storage tank rises excessively. do.

On the other hand, conventional LPG carriers employ a fuel supply system using heavy oil such as bunker C oil, which is relatively inexpensive as a propulsion fuel for ships. Due to the strengthening of regulations, a LSHFO tank with low sulfur content had to be installed separately, and the demand for an eco-friendly fuel supply system that meets international environmental regulations has grown.

Recently, the application of fuel supply systems that use LPG or LNG and boil-off gas generated therefrom as propulsion fuel is increasing in LPG or LNG carriers. The number of ships used as propulsion fuel is increasing.

In particular, LPG is easier to store than LNG, which is liquefied at cryogenic temperatures, and it does not significantly fall in SPECIFIC ENERGY and ENERGY DENSITY compared to conventional HFO, and has an excellent effect in reducing SOX, NOX, CO2, PM, etc. compared to conventional HFO.

In ships using LPG as fuel, LPG to be supplied to the engine as fuel goes through the fuel supply system including the compression pump and heater from the fuel supply tank, and is supplied to the engine of the ship according to the fuel supply conditions of the engine. is supplied

When supplying an incompressible fluid such as LPG as fuel, a greater amount of fuel than the fuel required by the engine is oversupplied in order to respond immediately to changes in engine load, and then the remaining LPG or engine load changes LPG remaining due to changes in fuel consumption rate and LPG remaining in the engine and piping when the engine is stopped is discharged from the engine and recovered.

However, if the recovered LPG is discharged and burned as it is, there is a problem of wasting fuel. In addition, since the recovered LPG is compressed and heated according to the fuel supply condition of the engine and is in a high temperature and high pressure state, there is a problem of increasing the pressure and temperature in the tank when it is sent to the fuel supply tank.

In consideration of this, the LPG recovered from the engine may be sent back to the fuel supply unit, mixed with the liquefied gas supplied from the fuel supply tank, and then supplied to the engine again.

However, LPG recovered from the engine has a relatively high temperature with a maximum temperature of around 60°C, and lubricating oil introduced from the engine may be mixed. In contrast, LPG stored in the fuel supply tank has a low temperature of around -52°C based on atmospheric pressure. The temperature of LPG passing through the gas tank drops considerably, and especially in the section where the engine load is high, the amount of high-temperature LPG recovered from the engine is small and the amount of low-temperature LPG supplied from the fuel supply tank is large. This can harden or solidify, clogging the piping or impeding the smooth fuel supply.

An object of the present invention is to solve this problem, and to provide a system that can smoothly supply fuel by preventing the lubricating oil in LPG recovered from the engine from being hardened.

According to one aspect of the present invention for solving the above-described problems, a fuel supply tank provided on a ship and storing liquefied gas supplied to an in-board engine;

a fuel supply line through which liquefied gas is supplied from the fuel supply tank to the engine;

a boosting pump provided in the fuel supply line and compressing the liquefied gas to a pressure required for the engine;

a return line for recovering liquefied gas not consumed by the engine from the engine and recirculating it to an upstream of the boosting pump of the fuel supply line;

a temperature controller provided in the fuel supply line for heating or cooling the liquefied gas according to a temperature required by the engine; and

A bypass line branched from the fuel supply line downstream of the temperature controller and connected to the return line includes:

The high-temperature liquefied gas recovered from the engine and the liquefied gas passing through the temperature controller are mixed with the low-temperature liquefied gas supplied from the fuel supply tank through the return line to prevent hardening of lubricant oil in the fuel supply line. A fuel supply system is provided.

a control valve provided in the bypass line to adjust the flow rate and temperature of the liquefied gas supplied from the fuel supply line to the return line; and a temperature control unit configured to control the control valve according to the temperature of the liquefied gas passing through the fuel supply line downstream of the junction of the return line in the fuel supply line.

Preferably, the temperature control unit comprises: a temperature sensor for sensing the temperature of the liquefied gas downstream of the junction in the fuel supply line; and a controller for controlling the opening and closing and opening degrees of the control valve according to the temperature sensed by the temperature sensor, wherein the amount of liquefied gas passing through the bypass line through the control valve according to the control of the controller is adjusted It is possible to maintain the temperature of the liquefied gas downstream of the confluence point above the set temperature.

Preferably, the temperature controller is provided at the rear end of the boosting pump in the fuel supply line, and operates as a heater for heating liquefied gas when the load of the engine is high, and cooling the liquefied gas when the load of the engine is low. It can work as a cooler.

Preferably, the temperature controller is provided at the front end of the boosting pump in the fuel supply line, and operates as a heater for heating liquefied gas when the load of the engine is high, and cooling the liquefied gas when the load of the engine is low. It can work as a cooler.

Preferably, a compressor for compressing the boil-off gas generated in the fuel supply tank; and a condenser for cooling and condensing the boil-off gas compressed in the compressor, wherein the liquefied gas condensed in the condenser is supplied to the fuel supply line and may be supplied to the engine through the boosting pump.

Preferably, a re-liquefaction device for receiving boil-off gas generated from the fuel supply tank and re-liquefying it may be further included.

According to another aspect of the present invention, liquefied gas is compressed in a boosting pump along a fuel supply line from a fuel supply tank provided on a ship, heated or cooled with a temperature controller according to the temperature required in the engine, and supplied as fuel to the onboard engine,

The liquefied gas not consumed in the engine is recirculated upstream of the boosting pump along a return line,

Supplying the liquefied gas passing through the temperature controller to the return line through a bypass line connected to the return line downstream of the temperature controller,

The high-temperature liquefied gas recovered from the engine and the liquefied gas that has passed through the temperature controller are mixed with the low-temperature liquefied gas supplied from the fuel supply tank through the return line to prevent curing of lubricant oil in the fuel supply line. A method for supplying fuel to a ship is provided.

Preferably, the fuel supply line detects the temperature of the liquefied gas downstream of the merging point of the return line, and adjusts the amount of liquefied gas passing through the bypass line according to the sensed temperature to the temperature of the liquefied gas downstream of the confluence point can be maintained above the set temperature.

In the present invention, the liquefied gas that is not consumed in the engine is recovered and recirculated upstream of the boosting pump along the return line, and the liquefied gas that has passed through the temperature controller through the bypass line is supplied to the return line, and the high temperature liquefied gas recovered from the engine is supplied to the return line. The liquefied gas that has passed through the temperature controller together with the gas is mixed with the low-temperature liquefied gas supplied from the fuel supply tank.

By maintaining the temperature of the liquefied gas passing through the fuel supply line above the set temperature as described above, it is possible to prevent the lubricating oil mixed in the recirculated liquefied gas recovered from the engine from being hardened or solidified in the fuel supply line and clogging the pipeline.

In particular, the liquefied gas temperature of the fuel supply line is adjusted by adjusting the flow rate of the liquefied gas supplied along the bypass line even if the amount of the recirculated liquefied gas recovered according to the load change of the engine and the amount of the low-temperature liquefied gas supplied from the fuel supply tank change. can be effectively controlled, and by not installing a separate heater or heating coil, etc., it is possible to reduce the installation cost of the device and related facilities and contribute to securing the space inside the ship.

1 schematically shows a fuel supply system for a ship according to a first embodiment of the present invention.
2 schematically shows a fuel supply system for a ship according to a second embodiment of the present invention.
3 schematically shows a fuel supply system for a ship according to a third embodiment of the present invention.
4 schematically shows a fuel supply system for a ship according to a fourth embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Here, it should be noted that in adding reference signs to the elements of each drawing, the same elements are indicated with the same reference numerals as much as possible even though they are indicated on different drawings.

In an embodiment of the present invention to be described later, the vessel may be any type of vessel in which an engine capable of using liquefied gas as a fuel for a propulsion engine or a fuel for a power generation engine is installed. Typical examples include ships with self-propelled capabilities such as LPG carriers, LNG carriers, liquid hydrogen carriers, LNG regasification vessels (RVs), liquefied gas-propelled container carriers, and liquefied gas-propelled tankers, as well as LNG Floating Production Storage (FPSO). Offloading) and LNG FSRU (Floating Storage Regasification Unit) may include offshore structures that do not have propulsion capabilities but are floating in the sea.

In addition, the present embodiment can be transported by being liquefied at a low temperature, and BOG is generated in a stored state and can be applied to a fuel supply system of all kinds of liquefied gas that can be supplied as fuel of an engine. Such liquefied gas is, for example, liquefied petrochemicals such as LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), Liquefied Ethylene Gas, Liquefied Propylene Gas, etc. gas and ammonia (NH ₃ ), and the like. However, in the embodiments to be described later, the representative liquefied gas LPG or NH ₃ will be described as an example to be applied.

1 schematically shows a fuel supply system for a vessel according to a first embodiment of the present invention, FIG. 2 shows a fuel supply system for a vessel according to a second embodiment, and FIG. 3 shows a vessel according to a third embodiment of the present invention. A fuel supply system, and FIG. 4 shows a fuel supply system for a ship according to the fourth embodiment, respectively.

1 to 4, the fuel supply system of the present embodiments is provided on a ship and liquefied from the fuel supply tank T, which stores liquefied gas supplied to the in-board engine, and the fuel supply tank to the engine ME. Fuel supply lines (SL, SLa, SLb, SLc) to which gas is supplied, boosting pumps (200, 200a, 200b, 200c) that are provided in the fuel supply line and compress liquefied gas to the pressure required for the engine, which are not consumed by the engine A return line (RL) that recovers liquefied gas from the engine and recirculates it upstream of the boosting pump of the fuel supply line, and a temperature controller (300, 300a, 300b) that is provided in the fuel supply line and heats or cools the liquefied gas according to the temperature required by the engine. , 300c).

The liquefied gas stored in the fuel supply tank (T) is pumped from the transfer pump (P) provided in the tank and supplied to the fuel supply lines (SL, SLa, SLb, SLc), and the boosting pumps (200, 200a, 200b, 200c) It is supplied to the engine ME at the pressure and temperature required by the engine through the and temperature controllers 300, 300a, 300b, and 300c.

In particular, compressed and heated fuel is supplied to the engine in a liquid state to the engine of the present embodiments, and unlike the engine to which a compressive fluid having a large volume change according to a change in pressure, that is, gas fuel is supplied, the volume of the engine is increased even when pressure is applied. When liquefied gas such as LPG or NH ₃ in liquid state is supplied as engine fuel, incompressible fluid with little or no change, excess liquefied gas is transferred to the engine to supply fuel and prevent cavitation in response to changes in engine load immediately. supply

Among the liquefied gas supplied to the engine, the remaining fuel consumed as fuel is discharged from the engine. If compressed and heated fuel is sent to the fuel supply tank as it is, the pressure and temperature in the fuel supply tank increase, which may threaten the safety of the tank and ship. have.

In the present embodiments, in order to solve this problem, the return line RL is connected to the upstream of the boosting pumps 200, 200a, 200b, and 200c of the fuel supply line, and the liquefied gas recovered from the engine is supplied from the fuel supply tank T. Together with the liquefied gas, it is supplied back to the engine through a device such as a boosting pump. A pressure control valve RV capable of adjusting the pressure of the liquefied gas recovered from the engine is provided in the return line RL.

However, when the amount of high-temperature liquefied gas recovered from the engine is small and the amount of low-temperature liquefied gas supplied from the fuel supply tank is large as in the section where the engine load is high, the lubricant introduced into the liquefied gas recovered from the engine is hardened or solidified. This can block the piping or prevent smooth fuel supply.

In order to solve this problem, as shown in FIGS. 1 to 4, in the present embodiments, it is branched from the fuel supply lines SL, SLa, SLb, and SLc downstream of the temperature controllers 300, 300a, 300b, and 300c and returned. By providing the bypass line BL connected to the line RL, the high-temperature liquefied gas (recovered liquefied gas) recovered from the engine ME and the liquefied gas passing through the temperature controllers 300, 300a, 300b, 300c ( By mixing the bypass liquefied gas) with the low-temperature liquefied gas supplied from the fuel supply tank (T) through the return line, the temperature of the liquefied gas in the fuel supply line is maintained above the set temperature to prevent hardening of the lubricant. .

A control valve (BV) for controlling the flow rate and temperature of the liquefied gas supplied from the fuel supply line to the return line is provided in the bypass line, and downstream of the junction of the return line from the fuel supply line is the flow rate of the liquefied gas passing through the fuel supply line. A temperature control unit 100 for controlling the control valve according to the temperature is provided.

The temperature control unit 100, the liquefied gas passing downstream of the junction in the fuel supply line, that is, the recovered liquefied gas supplied through the return line, the bypass liquefied gas, and the liquefied gas supplied from the fuel supply tank is mixed with the temperature of the liquefied gas It includes a temperature sensor 110 for detecting the temperature sensor, and a controller 120 for controlling the opening and closing and opening degree of the control valve (BV) according to the temperature sensed by the temperature sensor.

The controller 120 controls the control valve (BV) to adjust the amount of liquefied gas passing through the bypass line (BL) to set the temperature of the liquefied gas passing downstream of the confluence point to a set temperature or higher, preferably to -10°C or higher. can keep

For example, in a section where the load of the engine is high, the amount of low-temperature liquefied gas supplied from the fuel supply tank T is large, and the amount of liquefied gas recovered from the engine ME is relatively small, so that the temperature of the mixed liquefied gas is lowered. In this case, while operating the temperature controllers 300, 300a, 300b, and 300c as a heater, a part of the liquefied gas heated through the temperature controller is mixed with the recovered liquefied gas of the return line through the bypass line to join the fuel supply line. By sending it to the point, the temperature of the mixed liquefied gas is maintained at -10°C or higher to prevent the lubricating oil that may be introduced due to the recovered liquefied gas from being hardened or solidified in the fuel supply line.

Conversely, in the section where the engine load is low, the amount of low-temperature liquefied gas supplied from the fuel supply tank is small, and the temperature of the mixed liquefied gas increases because the amount of liquefied gas recovered from the engine is large. It can be operated to cool the mixed liquefied gas to the required temperature in the engine.

In the arrangement order of the temperature controller and the boosting pump, as in the first and second embodiments of FIGS. 1 and 2 , the temperature controllers 300 and 300a are provided at the rear end of the boosting pumps 200 and 200a in the fuel supply line, and the boosting pump The compressed fuel may be heated or cooled through a temperature controller, and as in the third and fourth embodiments of FIGS. 3 and 4 , the temperature controllers 300b and 300c are the boosting pumps 200b and 200c in the fuel supply line. ), the liquefied gas heated or cooled through the temperature controller first through the boosting pump may be compressed to the required pressure in the engine.

When the temperature controller is provided at the rear end of the boosting pump as in the first and second embodiments, since the liquefied gas compressed through the boosting pump is also introduced into the temperature controller, the temperature controller must be designed at a relatively high pressure with the rear end pressure of the boosting pump. , since the inlet temperature of the boosting pump is low, the volume flow is reduced and the capacity of the boosting pump can be reduced. As in the third and fourth embodiments, when a temperature controller is provided in front of the boosting pump, the inlet temperature of the boosting pump increases, the volumetric flow rate increases, and the capacity of the boosting pump must be increased. There are advantages to design. In consideration of other design conditions, the arrangement order of the thermostat and boosting pump can be selected as needed.

On the other hand, since boil-off gas is generated from the stored liquefied gas in the fuel supply tank, and the internal pressure of the fuel supply tank T may be increased by the boil-off gas, the first and third As in the embodiment, it is discharged from the fuel supply tank through the gas lines GL and GLb, is reliquefied through the reliquefaction unit RU, and then recovered to the fuel supply tank T to safely maintain the tank pressure. Alternatively, the boil-off gas discharged from the fuel supply tank may be condensed through a gas line and supplied as fuel for the engine. In this case, as in the second and fourth embodiments of FIGS. Compressors (400a, 400c) for compressing BOG and condensers (450a, 450c) for cooling and condensing BOG compressed in the compressor are provided, and the gas line is connected upstream of the boosting pump of the fuel supply lines (SLa, SLc). Thus, the liquefied gas condensed in the condenser may be supplied to the fuel supply line, and may be supplied to the engine ME through the boosting pumps 200a and 200c and the temperature controllers 300a and 300c.

The present invention is not limited to the above embodiments, and it is to those of ordinary skill in the art that various modifications or variations can be implemented without departing from the technical gist of the present invention. it is self-evident

T: fuel supply tank
SL, SLa, SLb, SLc: fuel supply line
RL: return line
BL: bypass line
BV: control valve
100: temperature control unit
110: temperature sensor
120: controller
200, 200a, 200b, 200c: boosting pump
300, 300a, 300b, 300c: thermostat
RU: reliquefaction unit
400a, 400c: Compressor
450c, 450c: condenser

Claims (9)

a fuel supply tank provided on the ship and storing liquefied gas supplied to the onboard engine;
a fuel supply line through which liquefied gas is supplied from the fuel supply tank to the engine;
a boosting pump provided in the fuel supply line and compressing the liquefied gas to a pressure required for the engine;
a return line for recovering liquefied gas not consumed in the engine from the engine and recirculating it to an upstream of a boosting pump of the fuel supply line;
a temperature controller provided in the fuel supply line for heating or cooling the liquefied gas according to a temperature required by the engine;
a bypass line branched from the fuel supply line downstream of the temperature controller and connected to the return line;
a control valve provided in the bypass line to adjust the flow rate and temperature of the liquefied gas supplied from the fuel supply line to the return line; and
a temperature control unit for controlling the control valve according to the temperature of the liquefied gas passing through the fuel supply line downstream of the junction of the return line in the fuel supply line;
The high-temperature liquefied gas recovered from the engine and the liquefied gas that has passed through the temperature controller are mixed with the low-temperature liquefied gas supplied from the fuel supply tank through the return line to prevent curing of lubricant oil in the fuel supply line. A ship's fuel supply system. delete According to claim 1, wherein the temperature control unit
a temperature sensor for sensing the temperature of the liquefied gas downstream of the junction in the fuel supply line; and
A controller for controlling the opening and closing and opening of the control valve according to the temperature sensed by the temperature sensor:
A fuel supply system for a ship, characterized in that by adjusting the amount of liquefied gas passing through the bypass line through the control valve according to the control of the controller, the temperature of the liquefied gas downstream of the merging point is maintained above a set temperature. 4. The method of claim 3,
The temperature controller is provided at the rear end of the boosting pump in the fuel supply line, and operates as a heater for heating liquefied gas when the load of the engine is high, and as a cooler for cooling the liquefied gas when the load of the engine is low. Ship's fuel supply system, characterized in that. 4. The method of claim 3,
The temperature controller is provided at the front end of the boosting pump in the fuel supply line, and operates as a heater for heating liquefied gas when the load of the engine is high, and as a cooler for cooling the liquefied gas when the load of the engine is low. Ship's fuel supply system, characterized in that. 6. The method according to claim 4 or 5,
a compressor for compressing the boil-off gas generated from the fuel supply tank; and
Condenser for cooling and condensing the boil-off gas compressed in the compressor: further comprising,
The liquefied gas condensed in the condenser is supplied to the fuel supply line and may be supplied to the engine through the boosting pump. 6. The method according to claim 4 or 5,
A fuel supply system for a ship further comprising: a re-liquefaction device receiving the boil-off gas generated from the fuel supply tank and re-liquefying it. From the fuel supply tank provided on the ship, the liquefied gas is compressed by the boosting pump along the fuel supply line, heated or cooled with a temperature controller according to the temperature required by the engine, and supplied as fuel to the onboard engine,
The liquefied gas not consumed in the engine is recirculated upstream of the boosting pump along the return line,
supplying the liquefied gas passing through the temperature controller to the return line through a bypass line connected to the return line downstream of the temperature controller;
In the fuel supply line, the temperature of the liquefied gas downstream of the junction of the return line is sensed, and the amount of liquefied gas passing through the bypass line is adjusted according to the sensed temperature so that the temperature of the liquefied gas downstream of the merging point is higher than the set temperature. by keeping it as
The high-temperature liquefied gas recovered from the engine and the liquefied gas that has passed through the temperature controller are mixed with the low-temperature liquefied gas supplied from the fuel supply tank through the return line to prevent curing of lubricant oil in the fuel supply line. A method of supplying fuel to a ship. delete

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