KR102626180B1 - Fuel Supply System and Method For Ship - Google Patents

Abstract

A ship fuel supply system and method are disclosed. The ship's fuel supply system of the present invention includes a fuel supply line through which liquefied gas is supplied from a fuel supply tank provided on the ship to the ship's engine; A fuel supply pump provided in the fuel supply tank to pump liquefied gas into the fuel supply line; A pressurizing pump provided in the fuel supply line and pressurizing liquefied gas to the pressure required for the engine; And a return line for recovering liquefied gas not consumed by the engine among the liquefied gas supplied to the engine to the upstream of the engine, wherein the fuel supply tank is an atmospheric pressure tank disposed inside the hull of the ship. It is characterized by being.

Description

Fuel supply system and method for ship {Fuel Supply System and Method For Ship}

The present invention relates to a fuel supply system and method for ships, and more specifically, to effectively supply fuel to the engine by recovering and recirculating the remaining liquefied gas that has been oversupplied to the engine in ships using liquefied gas such as LPG as fuel. It relates to a fuel supply system and method that can be used.

Consumption of liquefied gases such as LNG (Liquefied Natural Gas) and LPG (Liquefied Petroleum Gas) is rapidly increasing worldwide. Liquefied gas is transported in a gaseous state through gas pipes on land or at sea, or is stored in a liquefied state on a liquefied gas carrier and transported to a distant consumer. Liquefied gases such as LNG or LPG are obtained by cooling natural gas or petroleum gas to extremely low temperatures (approximately -163°C in the case of LNG), and their volume is significantly reduced compared to the gaseous state, making them very suitable for long-distance transportation by sea.

The liquefaction temperature of propane in petroleum gas is low at about -42°C at normal pressure, and it can be stored in liquid form up to a temperature of about 45°C at 18 bar and up to 20°C at 7 bar. Propane in LPG evaporates at temperatures higher than -42°C at normal pressure, so the ship's LPG storage tank is insulated. However, because external heat is continuously transferred to LPG, LPG is continuously vaporized within the LPG storage tank during the LPG transport process, generating boil-off gas within the LPG storage tank.

In LPG carriers, when boil-off gas accumulates in the LPG storage tank, the pressure inside the LPG storage tank rises excessively, so the LPG storage tank is equipped with a pressure-resistant structure and a boil-off gas reliquefaction device is used to process the boil-off gas generated within the tank. do.

Meanwhile, conventional LPG carriers, etc., adopt a fuel supply system that uses relatively inexpensive heavy oil such as bunker C oil as propulsion fuel for ships. This heavy oil fuel supply system has the international exhaust gas emissions associated with the use of heavy oil fuel. Due to strengthened regulations, a separate low-sulfur heavy fuel fuel tank (LSHFO tank) had to be installed, and the demand for an eco-friendly fuel supply system that meets international environmental regulation standards has increased.

Recently, the application of fuel supply systems that use LPG or LNG and boil-off gas generated therefrom as propulsion fuel has been increasing in LPG or LNG carriers, and in accordance with the strengthening of international exhaust gas emission regulations, LPG or LNG is used not only in LPG or LNG carriers but also in general ships. The number of ships using fuel as propulsion fuel is increasing.

In particular, LPG is easier to store than LNG, which is liquefied at extremely low temperatures, and does not fall significantly in SPECIFIC ENERGY and ENERGY DENSITY compared to existing HFO, and has excellent savings in SOX, NOX, CO2, and PM compared to existing HFO.

On ships that use LPG as fuel, the LPG to be supplied as fuel to the engine goes from the fuel supply tank through the fuel supply system, which includes a pressurization pump, heater, etc., to the ship's engine according to the fuel supply conditions of the engine. supplied.

Liquid LPG, which is an incompressible fluid, can be supplied in excess of the fuel required by the engine so that it can immediately respond to changes in engine load. LPG that is oversupplied and consumed as fuel or LPG that remains due to changes in fuel consumption rate due to changes in engine load , When the engine is stopped, the LPG remaining in the engine and pipes is recovered upstream of the engine.

However, if the recovered LPG is released into the atmosphere as is, there is a problem of wasting fuel and causing environmental pollution, and if it is sent to a cargo tank, there is a risk of contamination of the LPG cargo and freezing of the lubricant due to sealing oil flowing in from the engine. In addition, since the recovered LPG is pressurized and heated according to the fuel supply conditions of the engine and is in a high temperature and high pressure state, there is a problem that sending it to the fuel supply tank increases the amount of BOG generated and increases the pressure in the tank.

The present invention solves these problems and seeks to provide a system that can effectively process LPG recovered from an engine and effectively supply fuel.

According to one aspect of the present invention for solving the above-described problem, a fuel supply line for supplying liquefied gas from a fuel supply tank provided on the ship to the engine on board the ship;

A fuel supply pump provided in the fuel supply tank to pump liquefied gas into the fuel supply line;

A pressurizing pump provided in the fuel supply line and pressurizing liquefied gas to the pressure required for the engine; and

It includes a return line for recovering liquefied gas not consumed by the engine among the liquefied gas supplied to the engine to the upstream of the engine,

A fuel supply system for a ship is provided, wherein the fuel supply tank is an atmospheric pressure tank disposed inside the hull of the ship.

Preferably, it may further include a fuel heater provided in the fuel supply line and heating the liquefied gas pressurized by the pressurization pump to a temperature required by the engine.

Preferably, the return line includes: a first return line connected from the engine to a fuel supply line in front of the pressurization pump; a second return line branched from the first return line and connected to a fuel supply line in front of the pressurization pump via a catch tank connected to the vent mast of the ship; and a third return line connected from the fuel supply line at the rear of the fuel heater to the fuel supply line at the front of the pressurization pump.

Preferably, the fuel supply line further includes a first pressure transmitter that detects the pressure at the rear end of the pressurization pump, and when the pressure detected by the first pressure transmitter is higher than the set value, the pump speed of the pressurization pump is first increased. lowered, and if it is still higher than the set value, some of the liquefied gas at the rear end of the pressurization pump can be discharged to the first return line to lower the pressure at the rear end of the pressurization pump.

Preferably, it further includes a second pressure transmitter that senses the pressure of the catch tank, and when the pressure detected by the second pressure transmitter is higher than the set value, some of the gas is discharged from the catch tank to the vent mast. The pressure of the catch tank can be adjusted.

Preferably, it further includes: a re-liquefaction unit for receiving and re-liquefying the boil-off gas generated from the cargo tank provided on the ship and storing the liquefied gas to be transported and the boil-off gas generated from the fuel supply tank, and in the re-liquefaction unit The fuel supply tank can be cooled by spraying the re-liquefied liquefied gas into the fuel supply tank.

According to another aspect of the present invention, liquefied gas is transferred from a fuel supply tank provided on a ship along a fuel supply line, and is pressurized by a pressurization pump to the pressure necessary for the engine onboard the ship and supplied as fuel,

Among the liquefied gas pressurized by the pressurization pump, the liquefied gas that is not consumed in the engine is recirculated along the return line to the fuel supply line upstream of the engine,

A fuel supply method for a ship is provided, wherein the fuel supply tank is an atmospheric pressure tank disposed inside the hull of the ship.

Preferably, the return line includes: a first return line connected from the engine to a fuel supply line in front of the pressurization pump; a second return line branched from the first return line and connected to a fuel supply line in front of the pressurization pump via a catch tank connected to the vent mast of the ship; and a third return line connected from the fuel supply line at the rear of the fuel heater to the fuel supply line at the front of the pressurization pump.

In the present invention, liquefied gas not consumed in the engine can be recirculated along the return line to the front of the pressurizing pump upstream of the engine.

In particular, the fuel supply tank is set up as an atmospheric pressure refrigerated tank in Hull, and a separate room temperature storage tank such as a C-Type tank is not placed on the upper deck, which reduces costs and makes it easy to secure installation space, and reduces the weight increase on the upper deck. It can be prevented. Additionally, since the hull experiences less temperature change than the upper part of the deck exposed to the external environment, evaporation gas generation from the fuel supply tank can be reduced.

Figure 1 schematically shows a fuel supply system for a ship according to an embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objectives achieved by practicing 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 structure and operation of a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Here, in adding reference numerals to components in each drawing, it should be noted that identical components are indicated with the same reference numerals as much as possible, even if they are shown in different drawings.

In the embodiment of the present invention described later, the ship may be any type of ship installed with an engine that can use liquefied petroleum gas as fuel for a propulsion engine or fuel for a power generation engine. Representative examples include ships with self-propelled capabilities such as LPG carriers, LNG carriers, liquid hydrogen carriers, and LNG RVs (Regasification Vessels), as well as LNG FPSOs (Floating Production Storage Offloading) and LNG FSRUs (Floating Storage Regasification Units). Marine structures that do not have propulsion capabilities but are floating in the sea may also be included.

In addition, this embodiment can be applied to a fuel supply system for all types of liquefied gas that can be liquefied at low temperature and transported, generate boil-off gas in a stored state, and be supplied as fuel for an engine. These liquefied gases are, for example, liquefied petrochemicals such as LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), Liquefied Ethylene Gas, and Liquefied Propylene Gas. It may be gas, ammonia, etc. However, in the examples described later, the application of LPG, one of the representative liquefied gases, will be described as an example.

Figure 1 schematically shows a fuel supply system for a liquefied gas carrier according to an embodiment of the present invention.

As shown in Figure 1, the fuel supply system of this embodiment is provided in the fuel supply line (SL), which supplies liquefied gas from the fuel supply tank (FT) provided on the ship to the engine (E) on board the ship, and the fuel supply tank. A fuel supply pump (FP) that transfers liquefied gas from the fuel supply tank to the engine, a pressurization pump (100) provided in the fuel supply line and pressurized liquefied gas to the pressure required for the engine, and liquefied gas that is not consumed by the engine among the liquefied gas. It includes return lines (RL1, RL2, RL3) that recirculate upstream of the engine.

In this embodiment, the system provides a fuel supply tank with an atmospheric pressure refrigerated tank placed inside the hull of the ship, supplies liquefied gas as fuel from the fuel supply tank to the onboard engine, and recovers the fuel without being consumed by the engine. It is characterized by supplying liquefied gas along return lines (RL1, RL2, RL3) upstream of the engine and in front of the pressurized pump (100) of the fuel supply line (SL) so that it can be recirculated.

If the ship of this embodiment is a ship that transports liquefied gas as cargo, such as an LPG carrier, a cargo tank (not shown) is provided to store and transport the cargo, LPG, and, separately from the cargo tank, liquefied gas to be used as fuel on the ship. A fuel supply tank to store fuel is provided separately on board the ship.

This fuel supply tank (FT) can be provided as an atmospheric pressure refrigerated tank placed inside the hull of the ship. In this way, by providing the fuel supply tank as an atmospheric pressure refrigerated tank in the Hull, costs are reduced and installation space is easily secured compared to placing a separate room temperature storage tank such as a C-Type tank on the upper deck, and the weight of the upper deck is reduced. The increase can be prevented. Additionally, since the hull experiences less temperature change than the upper part of the deck exposed to the external environment, evaporation gas generation from the fuel supply tank can be reduced.

LPG, which contains propane as its main ingredient, is stored at around 0 barg and -42 ℃ in a fuel supply tank located in Hull, and can be pressurized and heated through a fuel supply line and supplied to the engine at around 50 barg and 25 to 45 ℃.

The liquefied gas stored in the fuel supply tank (FT) is transferred to the fuel supply line (SL) through the fuel supply pump (FP) provided in the tank, is pressurized to the fuel supply pressure of the engine through the pressurization pump 100, and then is transferred to the fuel heater. At (200), it is heated to the temperature required by the engine and supplied to the engine. The fuel heater 200 may use, for example, glycol water, steam, or hot water as a heat source.

The fuel supply line (SL) may be additionally provided with a filter (not shown) and a service valve unit (not shown) that filter out foreign substances in the pressurized liquefied gas fuel. The service valve unit supplies LPG to the engine, and when the LPG fuel supply is interrupted due to the engine's fuel oil change, LPG mode stop, trip, etc., each pipe is double blocked through the valve to relieve pressure in the pipe.

An example of an engine supplied with pressurized and heated LPG as fuel may be the ME-LGIP engine from MAN Diesel & Turbo. In this case, LPG is transferred from the fuel supply pump and supplied to the engine as a high-pressure liquid at around 50 barg and 25 to 45 ℃ through a pressurized pump. It works.

In the engine of this embodiment, pressurized and heated fuel is supplied to the engine in a liquid state. Unlike engines supplied with compressible fluid, that is, gas fuel, whose volume changes greatly in response to pressure changes, there is no change in volume even when pressure is applied. When a small amount of incompressible fluid, liquid LPG, is supplied as engine fuel, sufficient fuel is supplied to immediately respond to changes in engine load, and excess LPG is supplied to the engine to prevent cavitation. Among the LPG supplied to the engine, the LPG remaining after being consumed as fuel can be discharged from the engine through a return line and recirculated.

In this embodiment, the return line is pressurized through a first return line (RL1) connected from the engine to the front end of the pressurization pump of the fuel supply line, and a catch tank (CT) branched from the first return line and connected to the ship's vent mast. It includes a second return line (RL2) connected to the fuel supply line in front of the pump, and a third return line (RL3) connected from the rear end of the fuel heater in the fuel supply line to the front end of the pressurization pump in the fuel supply line.

A temperature transmitter is provided to detect the temperature of the liquefied gas in the pipe downstream of the point where the return line joins the fuel supply line. The temperature transmitter detects the temperature of the liquefied gas in the fuel supply line where the recirculated liquefied gas is joined, and the third return line The opening/closing and opening degree of the valve provided in can be adjusted.

The liquefied gas discharged from the engine may be recirculated to the fuel supply line in front of the pressurization pump through the first return line, and may be transferred to the catch tank (CT) through the second return line and then transferred from the catch tank (CT) to the fuel supply line. It can also be supplied at the front end of the pressurized pump.

A filter (not shown) may be provided in the return line to filter out lubricant mixed in the liquefied gas discharged from the engine, and a pressure reducing valve may be provided in the RVT (Return Valve Train) to reduce the pressure of the liquefied gas discharged from the engine. there is.

The fuel supply line is equipped with a first pressure transmitter (PT1) that detects the pressure at the rear end of the pressurization pump. When the pressure detected by the first pressure transmitter is higher than the set value, the pump speed of the pressurization pump is first lowered, and the pump speed is still lower than the set value. If it is high, some of the liquefied gas at the rear of the pressurization pump can be discharged to the first return line to lower the pressure at the rear of the pressurization pump.

The catch tank (CT) is equipped with a second pressure transmitter (PT2) that detects the tank pressure, and when the detected pressure becomes higher than a certain pressure, the pressure can be adjusted by discharging part of the gas to the vent mast (VM). The catch tank transfers the LPG in the fuel supply line to the catch tank for storage, empties the pipe, and switches the engine to gas mode when the engine is switched to oil mode such as HFO or when the engine is not used while the ship is in port and at anchor. When setting sail or operating the engine in gas mode, the LPG stored in the catch tank can be reused as fuel.

In this way, the system of this embodiment recirculates the recirculated liquefied gas recovered from the engine to the fuel supply line, thereby preventing the lubricant mixed in the fuel while passing through the engine from flowing into the fuel supply tank (FT), and the liquefied gas recovered from the engine is prevented from flowing into the fuel supply tank (FT). It is possible to prevent the temperature of the fuel supply tank from rising due to gas.

The system of this embodiment is provided with a re-liquefaction unit (RS) capable of re-liquefying boil-off gas generated from liquefied gas such as a fuel supply tank and a cargo tank (not shown).

A liquid header (LH) capable of loading liquefied gas is connected to the fuel supply tank, and injection units (S1, S2, S3) are provided inside the fuel supply tank to spray the supplied liquefied gas into the tank. . A plurality of injection units may be provided along the height direction of the tank, and the liquefied gas re-liquefied through the re-liquefaction unit (RS) may be transferred to the liquid header and injected into the fuel supply tank through the injection unit.

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

E: engine
FT: Fuel supply tank
SL: Fuel supply line
RL1, RL2, RL3: Return lines
100: Pressurization pump
200: Fuel heater

Claims (8)

A fuel supply line that supplies liquefied gas from a fuel supply tank provided on the ship to the ship's engine;
A fuel supply pump provided in the fuel supply tank to pump liquefied gas into the fuel supply line;
A pressurizing pump provided in the fuel supply line and pressurizing liquefied gas to the pressure required for the engine;
A return line for recovering liquefied gas not consumed by the engine among the liquefied gas supplied to the engine to the upstream of the engine;
A re-liquefaction unit that receives and re-liquefies the boil-off gas generated from the cargo tank provided on the ship and storing the liquefied gas to be transported and the boil-off gas generated from the fuel supply tank; and
It includes an injection unit that injects liquefied gas into the interior of the fuel supply tank,
The fuel supply tank is an atmospheric pressure tank placed inside the hull of the ship,
The injection portion is provided in plurality along the height direction of the fuel supply tank,
A ship's fuel supply system, characterized in that the liquefied gas re-liquefied in the re-liquefaction unit is injected through the injection unit via a liquid header to cool the fuel supply tank. According to clause 1,
A fuel supply system for a ship further comprising: a fuel heater provided in the fuel supply line and heating the liquefied gas pressurized by the pressurization pump to a temperature required by the engine. The method of claim 2, wherein the return line is:
a first return line connected from the engine to a fuel supply line in front of the pressurization pump;
a second return line branched from the first return line and connected to a fuel supply line in front of the pressurization pump via a catch tank connected to the vent mast of the ship; and
A ship's fuel supply system comprising: a third return line connected from the fuel supply line at the rear end of the fuel heater to the fuel supply line at the front end of the pressurization pump. According to clause 3,
It further includes a first pressure transmitter that senses the pressure at the rear end of the pressurization pump in the fuel supply line,
If the pressure detected by the first pressure transmitter is higher than the set value, the pump speed of the pressurization pump is first lowered, and if it is still higher than the set value, a part of the liquefied gas at the rear end of the pressurization pump is discharged to the first return line and the pressure at the rear end of the pressurization pump is discharged. A ship's fuel supply system characterized by lowering pressure. According to clause 4,
It further includes a second pressure transmitter that detects the pressure of the catch tank,
A fuel supply system for a ship, characterized in that when the pressure detected by the second pressure transmitter is higher than the set value, some of the gas is discharged from the catch tank to the vent mast to control the pressure of the catch tank. delete delete delete

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