KR20230168627A - Ammonia Fuel Supply System For Ship - Google Patents

Abstract

The ship's ammonia fuel supply system is initiated. The ammonia fuel supply system for a ship of the present invention includes a fuel supply line connected from an ammonia tank storing ammonia to an engine on board the ship; A fuel supply pump that transfers ammonia from the ammonia tank to the fuel supply line; A compression pump provided in the fuel supply line and compressing ammonia to the pressure required for the engine; a fuel recovery line through which unconsumed ammonia among the ammonia supplied to the engine is discharged from the engine; a separator provided in the fuel recovery line to accommodate ammonia discharged from the engine; a recirculation line connected from the separator to the fuel supply line to recirculate liquid ammonia to the engine; And a temperature controller provided downstream of the confluence point of the recirculation line in the fuel supply line to adjust the temperature of ammonia according to the fuel supply conditions of the engine, wherein the fuel supply pump is installed inside the ammonia tank or in the fuel supply. It is characterized by being provided upstream of the temperature controller of the line.

Description

Ammonia Fuel Supply System For Ship}

The present invention relates to an ammonia fuel supply system for ships, and more specifically, to supply ammonia from an ammonia tank to an engine, discharge ammonia not consumed from the engine and recirculate it into the engine, or recover ammonia from a ship to an ammonia tank. It's about the fuel supply system.

As the global warming phenomenon intensifies, efforts are being made to reduce greenhouse gas emissions around the world, and as the 1997 Kyoto Protocol, which included obligations for developed countries to reduce greenhouse gases, expires in 2020, the event held in Paris, France in December 2015 The 195 parties participating in the Paris Climate Change Accord, which was adopted at the 21st United Nations Framework Convention on Climate Change and came into effect in November 2016, are making various efforts with the goal of reducing greenhouse gases.

Along with this global trend, interest in renewable energy (or renewable energy) such as wind power, solar power, solar heat, bioenergy, tidal power, and geothermal heat as a pollution-free energy that can replace fossil fuels and nuclear power is increasing, and various technologies are being developed. I'm losing.

Although LNG is considered an eco-friendly fuel compared to other fossil fuels, it still produces carbon dioxide when burned, and ships that use it as fuel emit carbon dioxide during operation.

Several studies are being conducted on eco-friendly fuels that can reduce carbon dioxide emissions during ship operations, and recently, technologies for ship engines that can use hydrogen, ammonia, etc. as fuel are being developed.

IMO (International Maritime Organization), a UN specialized organization established to internationally unify shipping routes, traffic rules, port facilities, etc., also plans to reduce greenhouse gases by 50% in 2050 compared to 2008 and reduce greenhouse gases by 100% by 2100. % reduction (GHG Zero Emission) is proposed as the goal, and regulations in each country and region are expected to be strengthened accordingly.

According to EEDI (Energy Efficiency Design Index), a mandatory carbon dioxide reduction regulation applied by IMO to new ships, the initial EEDI announcement called for a 10% reduction in carbon dioxide emissions in 2015 based on carbon dioxide emissions from 2013 to 2015. EEDI Phase 1 was applied, and it was planned to apply Phase 3 in 2025 by strengthening and applying one step every five years. However, for LPG carriers, EEDI Phase 3 will be applied early from 2022, two years after applying EEDI Phase 2. As international interest in climate change and greenhouse gas emissions grows, it has been decided that ships ordered after 2030 will reduce carbon emissions by 40% compared to ships ordered in 2008, and by 50% by 2050. As regulations are rapidly being strengthened, the need for alternative fuels is increasing.

In particular, if the standards of Phase 4 (40% reduction in carbon dioxide emissions) or higher are applied in the future, it may be difficult to achieve carbon dioxide emission regulations for ships using current LNG or LPG as fuel. In order to completely decarbonize shipping from a long-term perspective, ships Since it is inevitable to replace fuel with carbon-neutral fuel, there is a need to further expedite the development of technology for eco-friendly ship fuel and its application to ships.

Among carbon-neutral fuels, ammonia (NH ₃ ) is a substance in which 3 hydrogens are bonded to 1 nitrogen. It can form strong hydrogen bonds between molecules, making it easy to liquefy. It has a boiling point of -33.34°C and a melting point of -77.73 at normal pressure. It is ℃. Ammonia is particularly easy to store and transport, is easy to mass-produce through the Haber-Bosch method, and has excellent economic efficiency compared to other carbon-neutral fuels, so research and development for using ammonia as a ship fuel is being actively conducted.

Engine manufacturers such as MAN-ES announced that they will complete the development of ammonia engines using ammonia fuel by 2025, and in addition to research on the characteristics of ammonia fuel, related regulations are being announced by classification societies.

Challenges that must be overcome when using ammonia as a fuel include handling of ammonia, which is defined as a toxic substance, low reactivity when used as a fuel, and high production of nitrogen oxides.

Due to its toxicity, ammonia is a substance that requires careful handling as it can have a fatal impact on the lives of seafarers if the concentration exceeds a certain level.

In the “Guidelines for Ammonia Fueled Ships” recently distributed by the Korean Register of Shipping, it is defined as “To prevent air pollution, ammonia discharged directly into the atmosphere through vent pipes must be minimized,” and is basically processed in the fuel supply system. It is proposed to minimize external emissions and devise various safety measures that can be applied during driving.

Additionally, in order to overcome the low reactivity of ammonia, a method of increasing combustion efficiency has been proposed through mixed combustion of pressurized liquefied ammonia or vaporized ammonia and various marine fuels.

Problems that arise when using low-temperature liquefied fuel by pressurizing it include deterioration of performance or equipment failure due to blockage of pipes due to leakage of lubricating oil in the operation of pumps or compressors normally used for pressurization, or ammonia It may circulate through tanks and cargo holds, contaminating ammonia tanks and cargo holds.

In the case of LPG, which has recently been used as a marine fuel, the fuel supply section is operated in a closed loop to prevent contamination or performance degradation by oils such as lubricants.

The present invention, when applying an environmentally friendly fuel such as ammonia as a fuel for a ship engine, effectively supplies ammonia fuel to the engine, and ammonia recovered from the engine, ammonia discharged from each pipe in the event of purging or emergency, and ammonia gas generated therefrom. We would like to propose a fuel supply system that can effectively process fuel.

According to one aspect of the present invention for solving the above-described problem, a fuel supply line connected from an ammonia tank in which ammonia is stored to the ship's engine;

A fuel supply pump that transfers ammonia from the ammonia tank to the fuel supply line;

A compression pump provided in the fuel supply line and compressing ammonia to the pressure required for the engine;

a fuel recovery line through which unconsumed ammonia among the ammonia supplied to the engine is discharged from the engine;

a separator provided in the fuel recovery line to accommodate ammonia discharged from the engine;

a recirculation line connected from the separator to the fuel supply line to recirculate liquid ammonia to the engine; and

A temperature controller provided downstream of the confluence point of the fuel supply line and the recirculation line to adjust the temperature of ammonia according to the fuel supply conditions of the engine,

An ammonia fuel supply system for a ship is provided, wherein the fuel supply pump is provided inside the ammonia tank or upstream of the temperature controller of the fuel supply line.

Preferably, the fuel supply line includes a vertical pipe provided at a front end of the compression pump, and in the vertical pipe section, gas is separated from ammonia that has passed through the temperature controller, so that ammonia in a liquid state is compressed. It can be transported by pump.

Preferably, a reliquefaction line that discharges ammonia boil-off gas from the ammonia tank, reliquefies it, and returns it to the ammonia tank; a gas discharge line that discharges gaseous ammonia from the separator and transfers it to the reliquefaction line; and an oil filter provided in the re-liquefaction line, wherein the ammonia re-liquefied along the re-liquefaction line can be recovered into the ammonia tank after removing the oil through the oil filter.

Preferably, a post-processing unit that receives vent gas discharged from the ammonia tank, engine, and fuel supply system and processes it in accordance with atmospheric emission standards; and a vent line branched from the gas discharge line and connected to the post-processing unit.

Preferably, the post-processing unit includes a catch tank for receiving vent gas discharged from the ammonia tank, engine, and fuel supply system; And an ammonia scrubber that receives the gas separated from the vent gas contained in the catch tank and removes the ammonia in the gas by dissolving it in water, and the liquid separated from the vent gas contained in the catch tank is recovered into the ammonia tank. And the gas that has passed through the ammonia scrubber can be discharged overboard.

Preferably, a first control unit for controlling the pressure at the rear end of the fuel supply pump; a second control unit that controls the liquid level and pressure of the separator; And a third control unit that controls the pressure at the rear end of the compression pump.

Preferably, a tank recovery line connected from the fuel supply line to the ammonia tank at a rear end of the fuel supply pump; and a first control valve provided in the tank recovery line and controlled by the first control unit.

Preferably, the first control unit sets a process variable based on the pressure detected at the rear end of the fuel supply pump and a set point based on a pressure in a range where ammonia maintains the liquid phase at the operating temperature of the fuel supply pump. ) a first pressure controller that outputs a first output value (output) determined according to; a second pressure controller that outputs a second output value determined according to the ammonia saturation pressure at the temperature detected at the rear end of the fuel supply pump; And a low selector that receives the first and second output values from the first and second pressure controllers, selects a low value, and outputs an actual output value for controlling the opening of the first control valve. can do.

Preferably, a second control valve provided in the gas discharge line and controlled by the second control unit; And a third pressure controller that outputs a third output value according to the ammonia saturation pressure at the internal temperature detected by the separator, wherein the second control unit compares the internal pressure detected by the separator with the third output value. Therefore, when it is determined that the separator is saturated, the opening degree of the second control valve can be adjusted according to the liquid level of the separator.

Preferably, an ammonia discharge line connected from the rear end of the compression pump to the fuel recovery line; a third control valve provided in the ammonia discharge line and controlled by the third control unit; And it may further include a fourth pressure controller that senses the pressure at the rear end of the compression pump and outputs a fourth output value to the third control unit.

Preferably, the third control unit receives the fourth output value from the fourth pressure controller, and if the sensed pressure is higher than the set value, adjusts the VFD of the compression pump to lower the pump speed, and if the detected pressure is still higher than the set value, the third control unit lowers the pump speed. 3 By adjusting the control valve, the pressure at the rear end of the compression pump can be controlled by discharging some of the ammonia from the rear end of the compression pump through the ammonia discharge line.

Preferably, the engine is a propulsion engine of a ship, and the ship is provided with a power generation engine that receives gaseous ammonia at a lower pressure than the propulsion engine, and the fuel supply line branches off from the compression pump upstream of the fuel supply line. Fuel branch line connected to the power generation engine; And a fuel vaporizer provided in the fuel branch line to heat ammonia according to the fuel supply conditions of the power generation engine.

Preferably, the reliquefaction line includes a compressor that compresses the ammonia boil-off gas discharged from the ammonia tank; a heat exchanger that cools the ammonia boil-off gas compressed in the compressor by heat exchange with uncompressed ammonia boil-off gas to be supplied to the compressor from the ammonia tank; and a pressure reducing valve that depressurizes the ammonia cooled as it passes through the heat exchanger and transfers it to the ammonia tank. The oil filter may be disposed between the heat exchanger and the pressure reducing valve.

Preferably, the reliquefaction line includes a compressor that compresses the ammonia boil-off gas discharged from the ammonia tank; a heat exchanger that cools the ammonia boil-off gas compressed in the compressor by heat exchange with uncompressed ammonia boil-off gas to be supplied to the compressor from the ammonia tank; and a pressure reducing valve that reduces the pressure of ammonia cooled as it passes through the heat exchanger and transfers it to the ammonia tank. The oil filter may be disposed at a rear end of the pressure reducing valve.

In the present invention, ammonia, an eco-friendly fuel, is supplied as fuel for marine engines to reduce greenhouse gas emissions during ship operation and meet regulatory standards set by international conventions.

In particular, by providing an oil filter to separate and remove oil from ammonia discharged from the engine, it is possible to prevent clogging and performance degradation of equipment such as pipes and valves, prevent ammonia contamination in the ammonia tank, and prevent internal contamination of the ammonia tank. .

Figure 1 schematically shows an ammonia fuel supply system for a ship according to a first embodiment of the present invention.
Figure 2 schematically shows an ammonia fuel supply system for a ship according to a second embodiment of the present invention.
3 to 5 show the first to third control units in the fuel supply system according to the first and second embodiments in more detail.

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.

Hereinafter, the ship in the present invention refers to all types of ships equipped with an engine that can use ammonia as fuel for the ship's engine, and representative examples include LPG carrier (LNG Carrier), LNG carrier (LNG Carrier), liquid hydrogen carrier, and ammonia carrier. , vessels with self-propulsion capabilities such as container carriers, crude oil carriers, bulk carriers of minerals or grains, and Ro-Ro (Roll on/Roll off) ships, as well as offshore structures that do not have propulsion capabilities but are floating at sea. may also be included.

Engines supplied with ammonia as fuel include those supplied with ammonia as fuel together with other marine fuels such as LNG, LPG, HFO, MGO, and Diesel Oil, and those supplied with ammonia alone as fuel. Includes both propulsion engines and power generation engines.

Figures 1 and 2 schematically show a ship's ammonia fuel supply system according to the first and second embodiments of the present invention, respectively.

As shown in Figures 1 and 2, the fuel supply system of the present embodiments includes a fuel supply line (FSL) connected from the ammonia tank (FT) in which ammonia is stored to the onboard engine, and ammonia that is not consumed among the ammonia supplied to the engine. A fuel recovery line (FRL) discharged from the engine, a separator 200 provided in the fuel recovery line to accommodate ammonia discharged from the engine, and a recirculation line connected from the separator to the fuel supply line to recirculate liquid ammonia to the engine ( LL).

The ammonia tank may be a fuel tank placed near the deck, a cargo hold, or the cargo hold and fuel tank may be operated in conjunction.

Ammonia is supplied from the ammonia tank (FT) to the engine (E1) along the fuel supply line (FSL). The fuel supply pumps (100A, 100B) for transferring ammonia from the ammonia tank to the engine may be provided inside the ammonia tank as in the first embodiment system, or may be provided with fuel outside the ammonia tank as in the second embodiment. It can also be installed in the supply line. The system of the second embodiment is configured differently from the system of the first embodiment in the placement position of the fuel supply pump and the oil filter, which will be described later.

In these embodiments, not only the ship's propulsion engine (E1) but also the power generation engine (E2) for power supply within the ship can be supplied with ammonia as fuel.

This propulsion engine may be an engine supplied with high-pressure liquid ammonia at around 50 to 100 bar and 30 to 100°C as fuel, and the power generation engine is an engine supplied with gaseous ammonia at a lower pressure than the propulsion engine. It can be provided.

Looking at the first and second embodiment systems, the fuel supply line includes a temperature controller that adjusts the temperature of the ammonia to the fuel supply conditions of the engine in order to match the ammonia transported along the fuel supply pump to the fuel supply conditions required by the engine. (110) and a compression pump (120) that pressurizes ammonia and supplies it to the engine according to the fuel supply conditions of the engine are provided. A vertical pipe 130 is provided between the temperature controller and the compression pump. If vapor flows into the suction side of the pump, there is a risk of deteriorating pump performance and causing device malfunction. In the present embodiments, a vertical pipe is provided between the temperature controller and the compression pump to control the temperature in the vertical pipe. The gas is separated from the coarse ammonia and discharged to the top of the vertical pipe, and the liquid ammonia can be transferred to the compression pump.

Upstream of the compression pump of the fuel supply line, a fuel branch line (FSL2) connected from the fuel supply line to the power generation engine is branched, and the fuel branch line has a fuel vaporizer (150) that heats ammonia according to the fuel supply conditions of the power generation engine. is prepared.

In the first and second embodiments, the temperature controller and the compression pump were arranged in the fuel supply line in that order, but if necessary, they may be arranged in the order of the compression pump and the temperature controller.

Ammonia transferred from the ammonia tank to the fuel supply pump is supplied as fuel to the propulsion engine in a high-pressure liquid state through a temperature controller and compression pump. Ammonia supplied to the propulsion engine through a fuel supply pump, temperature controller, and compression pump through the fuel supply line may be in a high-pressure liquid state at around 50 to 100 bar and 30 to 100°C.

At this time, when an incompressible fluid with little or no change in volume even when pressure is applied, that is, liquid fuel, is supplied to the engine, excess liquid fuel is supplied to the engine to respond to changes in engine load and prevent cavitation. Among the liquid fuel supplied to the engine, the remaining fuel consumed as fuel and the liquid fuel remaining in the engine when the engine is stopped are discharged from the engine. To this end, a fuel recovery line (FRL) is installed to recover and recirculate unconsumed ammonia from the engine. It is prepared.

Fuel discharged without being consumed by the engine is recovered to the separator 200 along the fuel recovery line, and after gas-liquid separation in the separator, liquid ammonia is transferred back to the fuel supply line through the recirculation line (LL) and recirculated to the engine. It can be.

The gaseous ammonia separated from the separator is discharged from the separator along the gas discharge line (GL). Through the gas discharge line, the gaseous ammonia separated from the separator can be recovered to the ammonia tank, or re-liquefied through a re-liquefaction unit described later and then recovered to the ammonia tank or supplied as engine fuel.

Meanwhile, the temperature and pressure of the ammonia tank may increase due to evaporation gas naturally generated from ammonia stored in the ammonia tank and gas introduced from the separator. In the present embodiments, the ammonia boil-off gas is discharged from the ammonia tank, re-liquefied, and then returned to the ammonia tank, so that the pressure of the ammonia tank can be safely maintained and controlled.

For this purpose, a re-liquefaction line (RL) is provided to discharge ammonia boil-off gas from the ammonia tank, re-liquefy it, and return it to the ammonia tank. A re-liquefaction unit 300 is provided in the re-liquefaction line to re-liquefy the ammonia boil-off gas.

The reliquefaction unit includes a compressor 310 that compresses the ammonia boil-off gas discharged from the ammonia tank, and a heat exchanger 320 that cools the ammonia boil-off gas compressed in the compressor by heat exchange with the uncompressed ammonia boil-off gas to be supplied to the compressor from the ammonia tank. , includes a pressure reducing valve 330 that depressurizes the ammonia cooled as it passes through the heat exchanger and transfers it to the ammonia tank.

Ammonia that has passed through the compressor and heat exchanger of the reliquefaction unit may be reduced in pressure through a pressure reducing valve and then returned to the ammonia tank, or may be supplied to the fuel supply line to be supplied as engine fuel.

The gaseous ammonia discharged from the separator through the gas discharge line is recovered into the ammonia tank. It is transferred to the front of the reliquefaction section of the reliquefaction line, reliquefied through the reliquefaction section, and then transferred to the ammonia tank or supplied as engine fuel. .

However, ammonia recovered from the engine may contain engine oil and sealing oil introduced from the engine along with gases such as evaporative gas generated through compression and heating for fuel supply. If this lubricant flows into the ammonia tank, it may contaminate the ammonia in the tank, contaminate the inside of the ammonia tank, and may crystallize and block the pipes in the tank.

Additionally, the compressor in the reliquefaction unit also uses lubricating oil, and this compressor lubricant may be mixed into ammonia during compression for reliquefaction.

In the present embodiments, oil filters 340A, 340B are provided in the re-liquefaction line to remove engine oil and compressor lubricating oil mixed in the ammonia, so that the ammonia discharged from the engine and recovered in the ammonia tank and the re-liquid from the ammonia tank are provided. Oil is removed from the ammonia to be recovered through the stoker and transferred to the ammonia tank.

The oil filters 340A and 340B may be disposed between the heat exchanger 320 and the pressure reducing valve 330, as in the first embodiment shown in FIG. 1, and as in the second embodiment shown in FIG. 2. It may be placed behind the pressure reducing valve 330.

Meanwhile, when ammonia is used as fuel, the exhaust gas may contain a large amount of nitrogen oxides.

In order to treat nitrogen oxides in such exhaust, although not shown in the present embodiments, a selective catalytic reactor (SCR), which is a nitrogen oxide treatment facility, can be placed in the exhaust discharge section, and anhydrous ammonia (NH3), which is a reducing agent, and NH3 Solution (25 % NH3) or Urea aqueous solution (32.5% or 40% aqueous solution) to reduce nitrogen oxides through a reduction reaction. When using an aqueous solution of urea, a typical reducing agent, urea reacts with nitrogen oxides and decomposes into ammonia and carbon dioxide. Instead of urea, ammonia can be discharged from the ammonia tank or separator, at the rear end of the compression pump, or from the reliquefaction section and supplied as a reducing agent to the SCR through a post-treatment section described later.

The systems of this embodiment may be provided with a post-processing unit 400 that receives vent gas discharged from the ammonia tank, engine, and fuel supply system and processes it in accordance with atmospheric emission standards. To process vent gas from the separator and gas discharge line, a vent line (VL) is provided that branches off from the gas discharge line and connects to the post-processing section. If it is impossible to process the vent gas in the re-liquefaction unit, the vent gas generated in the ammonia tank can be transferred to the post-processing unit for treatment from the re-liquefaction line (RL) or directly from the ammonia tank.

The post-processing unit includes an ammonia tank, a catch tank that accommodates the vent gas discharged from the engine and the fuel supply system, and an ammonia scrubber that receives the gas separated from the vent gas contained in the catch tank and removes the ammonia in the gas by dissolving it in water. It can be configured to include.

Ammonia is a water-soluble substance that dissolves well in water. Ammonia discharged to the post-treatment unit is received in a catch tank, the liquid can be separated from the catch tank and recovered in the ammonia tank for reuse as fuel, and the gas is sent to an ammonia scrubber and dissolved in water to generate ammonia water for treatment. You can. The solubility of ammonia is 89.9g/100ml in water at 0℃, 52.0g/100ml in water at 20℃, and 7.4g/100ml in water at 96℃. It is highly soluble in low-temperature water, and the solubility decreases as the temperature increases. . Dissolution of ammonia in water is an exothermic reaction, so solubility is high when the temperature is low, so ammonia solubility can be increased by supplying low-temperature water to an ammonia scrubber or by providing a cooling device to cool the ammonia scrubber.

When the ammonia water in the ammonia scrubber reaches a saturated state, the ammonia water in the scrubber is discharged and replaced with new water. The liquid level in the ammonia scrubber is detected, and when the ammonia water level in the scrubber rises above a certain value, the liquid level can be adjusted by discharging the ammonia water in the scrubber. . The discharged ammonia water can be transferred to a sewage tank or bilge system, treated on board to meet the discharge standards, and then discharged overboard or sent to an onshore facility for treatment when the ship is docked. Instead of discharging the ammonia water that has reached a saturated state from the ammonia scrubber, pure ammonia is separated from the ammonia water by heating it to a temperature higher than the boiling point of ammonia and lower than the boiling point of water. Then, it is discharged from the scrubber, cooled, liquefied, and reused as fuel. You may.

The gas from which ammonia has been removed by passing through an ammonia scrubber can be discharged overboard.

The ammonia separated in the post-treatment unit may be supplied as a reducing agent to the SCR, and the post-treatment unit may include a component for controlling the temperature and concentration of ammonia water to be supplied as a reducing agent to the SCR. In this way, a reducing agent is manufactured from ammonia vent gas supplied from an ammonia tank and separator and supplied to the SCR, thereby reducing nitrogen oxides in the exhaust gas.

The systems of this embodiment include a first control unit (CR1) that controls the pressure at the rear end of the fuel supply pump, a second control unit (CR2) that controls the liquid level and pressure of the separator, and a third control unit (CR3) that controls the pressure at the rear end of the compression pump. It is prepared.

3 to 5 show the configuration of the first to third control units in the first and second embodiment systems in more detail.

First, let's look at the first control unit shown in FIG. 3.

At the rear of the fuel supply pumps (100A, 100B), a tank recovery line (PL) is connected from the fuel supply line to the ammonia tank, and the tank recovery line is provided with a first control valve (V1) controlled by the first control unit (CR1). do. The first control unit can control the pressure at the rear end of the fuel supply pump by controlling the first control valve.

The first control unit (CR1) controls a process variable (PV) based on the pressure detected at the rear end of the fuel supply pump and a set point (set point, A first pressure controller (PIC1) that outputs a first output value (output, OP1) determined according to SP), and a second pressure that outputs a second output value determined according to the ammonia saturation pressure at the temperature detected at the rear end of the fuel supply pump. A low selector (low selector) receives the first and second output values output from the controller (PIC2) and the first and second pressure controllers, selects a low value, and outputs the actual output value for adjusting the opening degree of the first control valve. LS).

The pressure detected through the PIT in the fuel supply line at the rear of the fuel supply pump becomes PV, and the value at which ammonia can maintain the liquid phase at the operating temperature is set to SP. Accordingly, OP1 is determined by the first pressure controller, and the pressure at the rear end of the fuel supply pump can be maintained by adjusting the opening degree of the first control valve provided in the tank recovery line according to OP1.

In order to maintain the pressure at the rear of the fuel supply pump above the ammonia saturation pressure at the operating temperature, first, calculate the saturation pressure based on the temperature detected through TI in the fuel supply line at the rear of the fuel supply pump.

The calculated saturation pressure or a partially corrected value is used as the output of the second pressure controller, that is, the second output value (OP2). The opening degree of the first control valve is adjusted according to OP2 to maintain the ammonia in liquid form.

The low selector (LS) receives OP1 and OP2, and outputs the lower output among the compared values as the actual output of the first control valve.

Next, let's look at the second control unit shown in FIG. 4. The second control unit is a system for controlling the liquid level of the separator 200.

A second control valve (V2) controlled by a second control unit (CR2) is provided in the gas discharge line connected to the upper part of the separator.

If the second control valve is controlled by simply detecting the separator liquid level, the separator liquid level does not rise even if the separator internal pressure is lowered by opening the second control valve during initial operation, so an additional control method is needed to smoothly adjust the separator liquid level.

Accordingly, a third pressure controller (PIC3) is provided that outputs a third output value according to the ammonia saturation pressure at the internal temperature detected by the separator.

The third pressure controller outputs the saturation pressure (Psat) calculated based on the internal temperature of the separator or a partially corrected value (Psat + α) as a third output value, and compares this with the actual pressure of the separator detected by the PIT. Therefore, when it is determined that the internal pressure is higher than the saturation pressure, a signal for adjusting the separator liquid level is sent to the second control unit (CR2).

The second control unit compares the separator liquid level detected by the LIT with the third output value according to the saturation pressure calculated based on the internal pressure detected through the PIT in the separator and the separator temperature, and when it is judged to be saturated, the control is performed by a signal output. 2 The liquid level of the separator can be adjusted by adjusting the opening degree of the control valve.

Next, let's look at the third control unit shown in FIG. 5. The third control unit (CR3) is a system for controlling the ammonia pressure supplied to the propulsion engine (E1) at the rear end of the compression pump (120).

An ammonia discharge line (EL) is connected to the fuel recovery line from the rear end of the compression pump, and a third control valve (V3) controlled by a third control unit is provided in the ammonia discharge line. In addition, a fourth pressure controller (PIC4) is provided that senses the pressure of the fuel supply line (FSL1) at the rear end of the compression pump and outputs a fourth output value to the third control unit.

The third control unit (CR3) receives the fourth output value output as the pressure at the rear end of the compression pump from the fourth pressure controller (PIC4), and when the detected pressure is higher than the set value, it adjusts the VFD (Variable Frequency Drive) of the compression pump to control the pump. Lower the speed, and if it is still higher than the set value, adjust the opening/closing and opening degree of the third control valve to control the pressure at the rear end of the compression pump by discharging some of the ammonia from the rear end of the compression pump to the fuel recovery line through the ammonia discharge line.

When applying VFD to a compression pump power device, split ratio control can be applied to maintain stable pressure and flow rate.

It is obvious 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 was done.

FT: Ammonia tank
E1: Engine for propulsion
E2: Engine for power generation
FSL: Fuel supply line
FRL: Fuel recovery line
LL: Recirculation line
RL: Reliquefaction line
GL: Gas discharge line
100A, 100B: Fuel supply pump
110: Temperature controller
120: Compression pump
130: Vertical pipe part
150: Fuel vaporizer
200: Separator
300: Reliquefaction unit
310: compressor
320: heat exchanger
330: Pressure reducing valve
340A, 340B: Oil filter
400: Post-processing unit

Claims (14)

A fuel supply line connected from the ammonia tank where ammonia is stored to the ship's engine;
A fuel supply pump that transfers ammonia from the ammonia tank to the fuel supply line;
A compression pump provided in the fuel supply line and compressing ammonia to the pressure required for the engine;
a fuel recovery line through which unconsumed ammonia among the ammonia supplied to the engine is discharged from the engine;
a separator provided in the fuel recovery line to accommodate ammonia discharged from the engine;
a recirculation line connected from the separator to the fuel supply line to recirculate liquid ammonia to the engine; and
A temperature controller provided downstream of the confluence point of the fuel supply line and the recirculation line to adjust the temperature of ammonia according to the fuel supply conditions of the engine,
The fuel supply pump is a ship's ammonia fuel supply system, characterized in that provided inside the ammonia tank or upstream of the temperature controller of the fuel supply line. According to clause 1,
It includes a vertical pipe provided at the front of the compression pump in the fuel supply line,
A ship's ammonia fuel supply system, characterized in that in the vertical pipe part, gas is separated from ammonia that has passed through the temperature controller, and liquid ammonia is transferred to the compression pump. According to clause 1,
A reliquefaction line that discharges ammonia boil-off gas from the ammonia tank, reliquefies it, and returns it to the ammonia tank;
a gas discharge line that discharges gaseous ammonia from the separator and transfers it to the reliquefaction line; and
It includes an oil filter provided in the reliquefaction line,
Ammonia fuel supply system for a ship, characterized in that the ammonia reliquefied along the reliquefaction line is returned to the ammonia tank after removing the oil through the oil filter. According to clause 3,
A post-processing unit that receives vent gas discharged from the ammonia tank, engine, and fuel supply system and processes it in accordance with atmospheric emission standards; and
A vent line branched from the gas discharge line and connected to the after-treatment unit. The method of claim 4, wherein the post-processing unit
A catch tank that accommodates vent gas discharged from the ammonia tank, engine, and fuel supply system; and
An ammonia scrubber that receives the gas separated from the vent gas contained in the catch tank and removes ammonia in the gas by dissolving it in water,
A ship's ammonia fuel supply system, wherein the liquid separated from the vent gas contained in the catch tank is recovered into the ammonia tank, and the gas that has passed through the ammonia scrubber is discharged overboard. According to clause 4,
A first control unit that controls pressure at the rear end of the fuel supply pump;
a second control unit that controls the liquid level and pressure of the separator; and
A ship's ammonia fuel supply system further comprising: a third control unit that controls the pressure at the rear end of the compression pump. According to clause 6,
A tank recovery line connected from the fuel supply line to the ammonia tank at a rear end of the fuel supply pump; and
A ship's ammonia fuel supply system further comprising: a first control valve provided in the tank recovery line and controlled by the first control unit. The method of claim 7, wherein the first control unit
A first output value (output) determined according to a process variable based on the pressure detected at the rear end of the fuel supply pump and a set point based on a pressure within a range in which ammonia maintains the liquid phase at the operating temperature of the fuel supply pump. A first pressure controller that outputs;
a second pressure controller that outputs a second output value determined according to the ammonia saturation pressure at the temperature detected at the rear end of the fuel supply pump; and
A low selector that receives the first and second output values output from the first and second pressure controllers, selects a low value, and outputs an actual output value for adjusting the opening degree of the first control valve. Ship's ammonia fuel supply system. According to clause 6,
a second control valve provided in the gas discharge line and controlled by the second control unit; and
It further includes a third pressure controller that outputs a third output value according to the ammonia saturation pressure at the internal temperature detected by the separator,
The second control unit compares the internal pressure detected in the separator with the third output value and, when the separator is determined to be saturated, adjusts the opening degree of the second control valve according to the liquid level of the separator. Ammonia fuel supply system for ships. According to clause 6,
An ammonia discharge line connected from the rear end of the compression pump to the fuel recovery line;
a third control valve provided in the ammonia discharge line and controlled by the third control unit; and
A fourth pressure controller that senses the pressure at the rear end of the compression pump and outputs a fourth output value to the third control unit. According to clause 10,
The third control unit receives the fourth output value from the fourth pressure controller,
If the detected pressure is higher than the set value, the VFD of the compression pump is adjusted to lower the pump speed, and if it is still higher than the set value, the third control valve is adjusted to discharge some of the ammonia from the rear end of the compression pump through the ammonia discharge line. A ship's ammonia fuel supply system, characterized in that it controls the pressure at the rear end of the compression pump. According to any one of claims 1 to 11,
The engine is a propulsion engine of a ship, and the ship is provided with a power generation engine that is supplied with gaseous ammonia at a lower pressure than the propulsion engine,
a fuel branch line branched from the fuel supply line upstream of the compression pump and connected to the power generation engine; and
A ship's ammonia fuel supply system further comprising: a fuel vaporizer provided in the fuel branch line to heat ammonia according to the fuel supply conditions of the power generation engine. The method of claim 12, wherein the reliquefaction line,
A compressor that compresses the ammonia boil-off gas discharged from the ammonia tank;
a heat exchanger that cools the ammonia boil-off gas compressed in the compressor by heat exchange with uncompressed ammonia boil-off gas to be supplied to the compressor from the ammonia tank; and
A pressure reducing valve is provided to reduce the pressure of ammonia cooled as it passes through the heat exchanger and transfer it to the ammonia tank,
A ship's ammonia fuel supply system, wherein the oil filter is disposed between the heat exchanger and the pressure reducing valve. The method of claim 12, wherein the reliquefaction line,
A compressor that compresses the ammonia boil-off gas discharged from the ammonia tank;
a heat exchanger that cools the ammonia boil-off gas compressed in the compressor by heat exchange with uncompressed ammonia boil-off gas to be supplied to the compressor from the ammonia tank; and
A pressure reducing valve is provided to reduce the pressure of ammonia cooled as it passes through the heat exchanger and transfer it to the ammonia tank,
A ship's ammonia fuel supply system, wherein the oil filter is disposed behind the pressure reducing valve.

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