System and method for safely storing and combusting ammonia

Abstract

[Problem] The present invention relates to a system capable of safely storing ammonia and supplying the ammonia to a combustion device in a diesel engine, a boiler, or a gas turbine, and performing desirable combustion to reduce nitrogen oxides generated during combustion. [Solution] A system and method for safely storing and combusting ammonia, the system and method being configured from: a device that prevents ammonia from leaking from an ammonia tank and a pipe to the outside including in the atmosphere by setting the pressure inside the tank and the pipe to a value lower than an atmospheric pressure, and that, in order to reduce nitrogen oxides generated during the combustion, suctions vaporized ammonia inside the ammonia tank and the pipe and thereby maintains the pressure inside the ammonia tank and the pipe to the atmospheric pressure or less; a device that compresses the vaporized ammonia that has been suctioned to raise the temperature and pressure thereof, and supplies the compressed ammonia to a nitrogen oxide reduction device (SCR) installed in an exhaust pipe; a device that condenses and liquefies the ammonia by lowering the temperature of the gaseous ammonia of which the temperature and pressure have been increased by compression; and a device that returns the liquefied ammonia to the ammonia tank.

Description

Systems and methods for safely storing and burning ammonia

[0001] The present invention relates to a system and method for safely supplying toxic ammonia stored in a tank to a diesel engine, boiler, or gas turbine, and for effectively and efficiently burning it in the combustion chamber while reducing the amount of nitrogen oxides produced during combustion.

[0002] Considering that the combustion of fossil fuels containing large amounts of carbon (C) contributes to global warming, hydrogen and ammonia have attracted attention as carbon-free fuels. While hydrogen faces many challenges in terms of storage and transportation, ammonia, primarily as a fertilizer feedstock, has already established production, transportation, and storage technologies, and is widely distributed worldwide. Research is currently being conducted into the use of ammonia as a fuel for diesel engines, boilers, and gas turbines. However, ammonia is toxic and, compared to the fossil fuels currently used as fuels for diesel engines, boilers, and gas turbines, has combustion-related challenges that must be overcome. These challenges include poor ignition, a slow combustion rate, and a high likelihood of generating nitrogen oxides (NOx), another air pollutant, during combustion. Furthermore, ammonia has physical properties such as an extremely low calorific value per unit mass (volume) (approximately 2.5 times lower than petroleum-based fuels). Therefore, many technical challenges must be overcome before it can be used as a fuel for diesel engines, boilers, and gas turbines.

[0003] For example, Patent Document 1 describes "a technology relating to a diesel engine that forms an ammonia premixture in the combustion chamber and burns the mixture, the technology having a fuel injection means for injecting fuel oil and gaseous ammonia as an ignition source into the combustion chamber in order to increase the combustion rate of ammonia, reduce unburned ammonia, and reduce CO2 emissions." Patent Document 2 describes "a technology for efficiently burning ammonia in an ammonia combustion engine, in which ammonia gas decomposed using an ammonia decomposition catalyst is supplied to a secondary combustion chamber connected to the main combustion chamber via a nozzle, and the ammonia gas is ignited and burned under fuel-excess conditions after adjusting the equivalence ratio of hydrogen contained in the ammonia decomposition gas to be equal to or higher than a predetermined lower limit, and the combustible gas containing unburned hydrogen is ejected from the nozzle into the main combustion chamber as a jet torch flame, and the premixed gas of ammonia and air supplied to the main combustion chamber is ignited and burned by the combustion of the unburned hydrogen by the jet torch flame." Patent Document 3 describes a technology in which "in an internal combustion engine that uses ammonia as fuel, there is a possibility that some of the ammonia supplied to the combustion chamber will be discharged without being burned in the combustion chamber, and there is also a possibility that NOx will be generated as the air-fuel mixture is burned in the combustion chamber. Therefore, there is a technology in which unburned ammonia and NOx contained in exhaust gas discharged from the combustion chamber are effectively purified by an aftertreatment device."

[0004] However, neither technology addresses the fundamental issue that ammonia is toxic, and has poor ignition properties and a slow combustion rate compared to fossil fuels, which are currently the main fuels for diesel engines, boilers, and gas turbines.

[0005] Japanese Patent No. 6702475 Japanese Patent Application No. 2021-161921

[0006] Ammonia (NH3) does not contain carbon (C), and is therefore considered a fuel that does not emit CO2 upon combustion (oxidation reaction). However, when compared to petroleum-based fuels in terms of combustion characteristics, such as ignition ability, combustion speed, and the possibility of generating large amounts of NOx, an air pollutant, ammonia is toxic. Compared to fossil fuels, which are currently the primary fuels for diesel engines, boilers, and gas turbines, ammonia has combustion-related issues that must be resolved, such as poor ignition ability, slow combustion speed, and a high possibility of generating nitrogen oxides (NOx), another air pollutant. Furthermore, ammonia's physical property, its extremely low calorific value per unit mass (about 1 / 2.5 of that of petroleum-based fuels), poses many technical challenges that need to be addressed. As a result, its calorific value per unit mass is significantly lower, about 40% (1 / 2.5) of that of petroleum-based fuels (diesel oil and heavy oil A), requiring about 2.5 times the fuel tank and fuel injection system to achieve the same performance (output) in diesel engines and boilers.

[0007] Therefore, the present invention aims to provide a system that safely stores and transfers ammonia in a tank and that is applicable to existing diesel engine, boiler, and gas turbine combustion equipment, and that improves ammonia combustion in diesel engine, boiler, and gas turbine combustion equipment, thereby reducing nitrogen oxides (NOx) contained in exhaust gas, and that includes the following elements: 1. In tanks and piping that store and transfer ammonia installed in diesel engines, boilers, and gas turbines that use ammonia as fuel, the pressure inside the ammonia tank and piping is set to a value lower than atmospheric pressure, thereby preventing ammonia from leaking from the tank and piping to the outside, including the atmosphere. 2. By utilizing the heat of vaporization generated when ammonia evaporates to lower the temperature of the ammonia itself, it is possible to maintain the ammonia in a liquefied state even when the pressure inside the ammonia tank and piping is set to a value lower than atmospheric pressure. 3. A system consisting of a device that sucks vaporized ammonia from inside the ammonia tank and piping and maintains the pressure inside the ammonia tank and piping below atmospheric pressure, a device that compresses the sucked vaporized ammonia to increase its temperature and pressure, a device that condenses and liquefies the compressed gaseous ammonia by lowering the temperature of the ammonia whose temperature and pressure have been increased, and a device that returns the liquefied ammonia to the ammonia tank is given a structure and function that allows the ammonia to remain liquefied even when the pressure inside the ammonia tank and piping is made lower than atmospheric pressure. 4. In combustion devices installed in ammonia-fueled diesel engines, boilers, and gas turbines, the combustion of ammonia is improved using electrical energy supplied from an electrical energy supply device in order to eliminate CO2 emissions from ammonia-fueled diesel engines, boilers, and gas turbines by zeroing the co-firing ratio of petroleum-based fuel supplied from an auxiliary combustion tank. 5. By sealing the outer periphery of the tank and piping that stores and transports ammonia with a double-layered structure, creating a vacuum inside, and installing an ammonia leak detection device inside the double-layered structure, it is possible to prevent ammonia from being released into the outside, including the atmosphere, and by being notified of leaks in real time with the ammonia leak detector, it is possible to respond quickly.6. By installing a vacuum insulation device around the entire or partial periphery of an ammonia storage tank to create a sealed structure and installing valves at multiple locations in the sealed space formed between the tank and the vacuum insulation device, it is possible to maintain a low temperature inside the tank when all valves are closed, and to flow a fluid at a temperature higher than the boiling point of the ammonia stored in the tank by opening the valves, it is possible to promote the vaporization of the ammonia stored in the tank. 7. By sucking and compressing the vaporized ammonia inside the ammonia tank and piping, the temperature and pressure can be increased and supplied to a selective catalytic reduction (SCR) system installed in the exhaust pipe, nitrogen oxides (NOx) generated by ammonia combustion can be reduced. 8. By adjusting the opening of the ammonia storage tank's supply main valve while operating the pump (ammonia supply pump) that supplies ammonia to diesel engines, boilers, and gas turbine combustion devices, the pressure inside the ammonia supply system from the ammonia storage tank to the ammonia supply pump can be maintained below atmospheric pressure, thereby preventing ammonia leaks from the supply system. 9. In the ammonia supply system, the part of the system where the internal pressure becomes higher than atmospheric pressure is covered with a container, and while the inside is sealed, part of it is sucked in by a blower. A heat exchanger is provided that can set the temperature of the gas sucked in inside the sealed container to any value, and an ammonia concentration meter is installed between the blower and the heat exchanger. This ensures safety by preventing ammonia from being released to the outside even if it leaks from the sealed ammonia supply system, and makes it possible to quickly detect any ammonia leak.

[0008] Compared to fossil fuels, which are currently the main fuels for diesel engines, boilers, and gas turbines, ammonia has combustion-related issues that must be resolved, such as toxicity, poor ignition, a slow combustion rate, and a high likelihood of generating nitrogen oxides (NOx), another air pollutant, during combustion. It also has the physical property of having an extremely low calorific value per unit mass (volume) (approximately 1 / 2.5 of that of petroleum-based fuels). Furthermore, since ammonia may generate large amounts of nitrogen oxides (NOx) during combustion, it is necessary to develop technologies to address this issue. To address these issues, the present invention provides the following system.

[0009] The invention described in claim 1 is characterized in that a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel is provided with a device for reducing the pressure inside the ammonia tank to a value lower than atmospheric pressure in order to prevent ammonia from leaking from the tank to the outside, including the atmosphere.

[0010] The invention described in claim 2 is characterized in that, in a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device is installed to make the pressure inside the ammonia tank lower than atmospheric pressure, thereby making it possible to prevent ammonia from leaking from the tank to the outside, including into the atmosphere.

[0011] The invention described in claim 3 is characterized in that in piping for storing and transporting ammonia, which is installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device is installed to make the pressure inside the ammonia piping lower than atmospheric pressure in order to prevent ammonia from leaking from the piping to the outside, including the atmosphere.

[0012] The invention described in claim 4 is characterized in that, in piping for storing and transporting ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device is installed to make the pressure inside the piping for ammonia lower than atmospheric pressure, thereby making it possible to prevent ammonia from leaking from the piping to the outside, including into the atmosphere.

[0013] The invention described in claim 5 is characterized in that a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel is provided with a device that sucks vaporized ammonia inside the ammonia tank and maintains the pressure inside the ammonia tank at or below atmospheric pressure in order to prevent ammonia from leaking from the tank to the outside, including into the atmosphere, by keeping the pressure inside the ammonia tank lower than atmospheric pressure, a device that compresses the sucked vaporized ammonia to increase the temperature and pressure, a device that condenses and liquefies the compressed gaseous ammonia by lowering the temperature of the ammonia whose temperature and pressure have been increased, and a device that returns the liquefied ammonia to the ammonia tank.

[0014] The invention of claim 6 is characterized in that, in a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, the following are installed: a device that sucks vaporized ammonia inside the ammonia tank and keeps the pressure inside the ammonia tank at or below atmospheric pressure; a device that compresses the sucked vaporized ammonia to increase the temperature and pressure; a device that condenses and liquefies the compressed gaseous ammonia, the temperature and pressure of which have been increased, by lowering the temperature; and a device that returns the liquefied ammonia to the ammonia tank; and by using a method of keeping the pressure inside the ammonia tank at a value lower than atmospheric pressure, it is possible to prevent ammonia from leaking from the tank to the outside, including into the atmosphere.

[0015] The invention described in claim 7 is characterized by comprising a system that can detect cracks, holes, and gaps that have occurred in joints of a tank that stores ammonia or a pipe that supplies ammonia, using an oxygen concentration sensor installed near the liquid surface inside the ammonia tank, taking advantage of the characteristic that when a crack, hole, or gap occurs in a joint of a tank that stores ammonia or a pipe that supplies ammonia and air flows in, layers of vaporized ammonia, the flowing-in air, and liquefied ammonia are formed in that order from the top of the tank inside the tank into which the flowing-in air has flowed in, due to the difference in density between liquid ammonia, vaporized ammonia, and the flowing-in outside air (air).

[0016] The invention described in claim 8 is characterized by comprising a device that continuously sucks in outside air that has flowed into an ammonia storage and supply system and continuously releases it into the atmosphere either as is or after some kind of post-processing, utilizing the characteristic that outside air that has flowed in through cracks, holes, or gaps in the joints of the tank and the piping that supplies ammonia remains somewhere between the liquid ammonia in the lower part of the tank and the gaseous ammonia in the upper part of the tank due to the difference in density.

[0017] The invention described in claim 9 is characterized in that in a combustion device installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device is installed that improves ammonia combustion by using electrical energy supplied from a device that supplies electrical energy, in order to reduce to zero the mixed combustion ratio of fuel containing carbon (C) supplied from a combustion auxiliary tank, thereby reducing CO2 emissions from the diesel engine, boiler, or gas turbine that uses ammonia as fuel to zero.

[0018] The invention described in claim 10 is characterized in that, in a combustion device installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, the method involves improving ammonia combustion using electric energy supplied from an electric energy supply device and reducing the mixed combustion ratio of fuel containing carbon (C) supplied from a combustion auxiliary tank to zero, thereby making it possible to reduce CO2 emissions from the diesel engine, boiler, or gas turbine that uses ammonia as fuel to zero.

[0019] The invention described in claim 11 is characterized in that a vacuum insulation device is installed around the entire circumference or part of the circumference of a tank that stores ammonia to create an airtight structure, and valves are installed at multiple locations in the airtight space formed between the tank and the vacuum insulation device.This makes it possible to maintain a low temperature inside the tank when all valves are closed and the vacuum insulation device is operated, and to promote the evaporation of the ammonia stored in the tank when some of the valves are opened and a fluid with a temperature higher than the boiling point of the ammonia stored in the tank is circulated.

[0020] The invention described in claim 11 can also be utilized as a method for safely storing and burning ammonia, in which "a vacuum insulation device is installed around the entire periphery or part of the periphery of a tank for storing ammonia to form an airtight structure, and valves are installed at multiple locations in the airtight space formed between the tank and the vacuum insulation device. By using this method, when all valves are closed and the vacuum insulation device is operated, it is possible to maintain a low temperature inside the tank, and when some of the valves are opened and a fluid with a temperature higher than the boiling point of the ammonia stored in the tank is circulated, it is possible to promote the evaporation of the ammonia stored in the tank."

[0021] The invention described in claim 12 is characterized in that it comprises a device for increasing the temperature and pressure of vaporized ammonia inside the ammonia tank by sucking and compressing it, and supplying the ammonia to a nitrogen oxide reduction device (SCR) installed in an exhaust pipe, in order to reduce nitrogen oxides (NOx) generated by the combustion of ammonia.

[0022] The invention described in claim 12 can also be used as a method for safely storing and burning ammonia, in which "by sucking in and compressing vaporized ammonia inside the ammonia tank and piping to increase the temperature and pressure, and supplying it to a selective catalytic reduction (SCR) device installed in the exhaust pipe, it becomes possible to reduce nitrogen oxides (NOx) generated by the combustion of ammonia."

[0023] The invention described in claim 13 is characterized in that it comprises a device that maintains the pressure inside the ammonia supply system from the ammonia tank to the ammonia supply pump at a value lower than atmospheric pressure by adjusting the aperture of a supply valve installed in the ammonia tank while operating a pump (ammonia supply pump) that supplies ammonia to a diesel engine, a boiler, or a combustion device of a gas turbine, in order to prevent leakage from the ammonia supply system.

[0024] The invention described in claim 13 can be applied to a system for safely storing and burning ammonia, in which, when a pressure lower than atmospheric pressure cannot be maintained on the inlet side of the ammonia feed pump because a diesel engine, boiler, or gas turbine is not operating or the consumption of ammonia-containing fuel is low, the inlet pressure of the ammonia feed pump can be maintained at a value lower than atmospheric pressure by operating the ammonia feed pump with the outlet piping of the ammonia feed pump connected to the ammonia tank. The invention can also be applied to a system for safely storing and burning ammonia, in which "while a pump for supplying ammonia to a diesel engine, boiler, or gas turbine combustion device (ammonia feed pump) is operating, the pressure inside the ammonia supply system from the ammonia storage tank to the ammonia supply pump is maintained at a value lower than atmospheric pressure by adjusting the aperture of the supply valve of the ammonia tank and the pressure control valve installed on the discharge side of the ammonia feed pump. This method makes it possible to prevent leakage from the ammonia supply system."

[0025] The invention described in claim 14 is characterized in that in an ammonia supply system, when the internal pressure becomes higher than atmospheric pressure, safety is maintained such that even if ammonia leaks from the ammonia supply system, the ammonia concentration meter is installed in a space whose interior is sealed and whose portion where the internal pressure becomes higher than atmospheric pressure is covered with a container so that ammonia leakage can be detected promptly.

[0026] The invention described in claim 14 can also be applied to a method for safely storing and burning ammonia, in which "a portion of an ammonia supply system where the internal pressure becomes higher than atmospheric pressure is covered with a container, and while the inside is kept sealed, a portion of it is sucked in by a blower, and a heat exchanger is provided which can set the temperature of the gas sucked in inside the sealed container to an arbitrary value, and an ammonia concentration meter is installed between the blower and the heat exchanger. By using this method, when the pressure inside the ammonia supply system becomes higher than atmospheric pressure, even if ammonia leaks from the ammonia supply system, the safety is maintained such that the ammonia will not be released to the outside, and if ammonia leaks, it becomes possible to quickly detect this."

[0027] By using the present invention, it becomes possible to safely store and transport ammonia and combust it effectively and efficiently in a combustion device in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, and it also becomes possible to reduce NOx produced by the combustion of ammonia in a NOx reduction device installed in the exhaust pipe.

[0028] 1 shows an example of a basic configuration according to an embodiment of the present invention. 2 shows an example of a configuration related to combustion according to an embodiment of the present invention. 3 shows an example of a detection and discharge function when air is inhaled due to damage to an ammonia supply system installed inside a fuel supply tank according to an embodiment of the present invention. 4 shows an example of a heat retention system using vacuum insulation in a fuel supply tank and an example of a device that promotes evaporation of ammonia according to an embodiment of the present invention. 5 shows an example of a device that effectively evaporates ammonia in a fuel supply tank according to an embodiment of the present invention.

[0029] First, an overview of this system will be described using Figure 1. In Figure 1, ammonia stored in an ammonia storage tank (1) flows through an ammonia supply valve "V-1" to an ammonia supply tank (2). The ammonia supply tank (2) is equipped with a device (3) that sucks vaporized ammonia and transfers it to the ammonia tanks (1) and / or (2), lowers the pressure inside the piping below atmospheric pressure, compresses the sucked ammonia, and increases its temperature and pressure, and a device (4) that cools and condenses the ammonia whose temperature and pressure have increased. Furthermore, the gaseous ammonia discharged from the device (3) with its increased temperature and pressure passes through the flow control valve "V-2" and is used as a reducing agent in the elemental oxide reduction device (5). The ammonia in the ammonia supply tank (2) is supplied by an ammonia supply pump (6) to a combustion device (7) installed in a diesel engine, boiler, or gas turbine, and is then injected into the combustion chamber (8) of the diesel engine, boiler, or gas turbine. In Figure 1, the space enclosed by the dashed line, including the device (3), device (4), pump (6), and device (7), is a sealed space. This sealed space is equipped with a blower (9), an ammonia detector (10), and a heat exchanger (11). The gas in the sealed space is sucked in by the blower (9), passes through the ammonia detector (10), and the heat exchanger (11), and then returns to the closed loop. This repeats this cycle, allowing for temperature control and confirmation of the properties of the gas in the sealed space (presence or absence of ammonia leakage).

[0030] Next, we will explain an apparatus and method for preventing ammonia leakage outside the storage and transfer system due to rupture, cracks, or loosening of packings installed on joints and valves in the tank or piping by maintaining the pressure in the ammonia tank and supply system lower than atmospheric pressure. Ammonia is supplied from the ammonia storage tank (1) to the ammonia supply tank (2) so that the liquid ammonia level remains constant. Simultaneously, vaporized ammonia is sucked in using a device (3) so that the pressure in the piping from the ammonia tank to the ammonia supply pump (6) is lower than atmospheric pressure. As a result, the temperature of the liquid ammonia drops below its boiling point at atmospheric pressure, approximately -33.34°C. However, if a portion of the liquid ammonia evaporates due to external heat input, the temperature of the liquid ammonia itself drops due to the heat of vaporization. Therefore, a stable ammonia state can be maintained by sucking in the vaporized ammonia using a device (3), condensing it using a device (4), and returning it to the tank (2). In this way, by using the device (3) to maintain the pressure in the ammonia storage and supply system from the ammonia storage tank (1) to the ammonia supply pump at or below atmospheric pressure, if a situation arises in which ammonia leaks due to rupture, cracks, loosening, etc. in the packings installed on the tanks, fittings installed on the pipes, or valves installed in the ammonia storage and supply system, it is possible to prevent ammonia from leaking to the outside by sucking in outside air from that location.

[0031] When the pressure in the ammonia tank and supply system is maintained below atmospheric pressure using the devices (3) and (4) installed in the tank (2), power is required to operate the devices (3) and (4). This section describes a method for maintaining the pressure in the ammonia tank and supply system below atmospheric pressure using the system shown in Figure 1 without operating these devices. In Figure 1, ammonia supplied to the combustion system is drawn into the ammonia supply pump (6) from the ammonia storage tank (1) via the ammonia supply valve V-1 and the ammonia supply tank (2). Due to the pipeline resistance of these supply systems, the pressure is usually lower than atmospheric pressure. In contrast, the discharge pressure of the pump (6) must be high enough to prevent ammonia from vaporizing even when its temperature is increased in the combustion system (for example, approximately 2 MPa, which is the saturated vapor pressure at 50°C). Therefore, in this system, a branch pipe connected to the intake side of the pump (6) is installed midway through the piping connecting the pump (6) to the combustion system (7), and a pressure regulating valve is installed midway through the branch pipe, enabling ammonia to be supplied to the combustion system (7) at a stable pressure. In this system, by narrowing the aperture of the ammonia supply valve, the pressure in the ammonia supply system from the ammonia supply valve to the pump (6) is set to a value lower than atmospheric pressure, and by narrowing the aperture of the pressure regulating valve V-3, the pressure and supply amount of ammonia supplied to the combustion device (7) are maintained. This makes it possible to keep the pressure in the piping from the ammonia storage tank (1) to the ammonia supply pump (6) lower than atmospheric pressure while the ammonia supply pump (6) is operating, even if the devices (3) and (4) installed in the tank (2) are not operated, and to prevent ammonia leakage due to rupture, cracks, loosening, etc. in the joints installed in the tank or the piping or in the packing installed in the valve.

[0032] FIG. 2 shows an example of a basic configuration according to an embodiment of the present invention. In the figure, ammonia discharged from an ammonia supply tank (2) travels through ammonia transport piping to a combustion device (7) for a diesel engine, boiler, or gas turbine. Compared to fossil fuels, which are currently the primary fuels for diesel engines, boilers, and gas turbines, ammonia has combustion characteristics such as poor ignition and a slow combustion rate. Therefore, the ignition and combustion rate of ammonia can be improved by blending, stratifying, or independently injecting ammonia fuel, such as diesel oil, heavy oil, or LNG, transferred from a tank (12) storing a petroleum-based fuel that acts as a combustion improver for ammonia, into the combustion device (7). Whether the ammonia injected into the combustion device (7) is in a liquid or gaseous state is determined by the configuration of the combustion device, which has a structure and function for improving combustion by blending, stratifying, or independently injecting petroleum-based fuel.

[0033] The objective of this invention is to contribute to the prevention of global warming by providing a system and method for safely supplying ammonia, a carbon-free fuel, to diesel engines, boilers, and gas turbines, burning it effectively and efficiently in the combustion chamber, and reducing the nitrogen oxides produced during combustion.However, because fuels such as diesel, heavy oil, and LNG, which act as combustion improvers for ammonia, contain carbon, a technical challenge is to reduce the co-firing ratio of these fuels as much as possible, but achieving zero is difficult.To solve this problem, this invention uses an apparatus and method that uses electrical energy to improve the ignition and combustion characteristics of ammonia, thereby reducing GHG (greenhouse gas) emissions to zero.

[0034] The electricity transmitted from the electric energy supply device (12) can improve the combustion characteristics of ammonia, such as poor ignition and slow combustion speed, by forming a high-temperature zone using a discharge device and / or a heating device installed in the combustion device (7) to help the ammonia burn. Furthermore, by generating electricity to be supplied to the electric energy supply device (12) using renewable energy, ammonia that does not generate GHGs, or a diesel engine, boiler, or gas turbine equipped with a combustion device that uses only hydrogen as fuel, it is possible to reduce GHG emissions to zero for the entire system.

[0035] When using ammonia as a fuel, it is necessary to overcome the combustion characteristics issues of poor ignition and slow combustion speed compared to fossil fuels, which are currently the main fuels for diesel engines, boilers, and gas turbines. Ensuring safety during storage and transportation of ammonia is also an important issue. Because the boiling point of ammonia at atmospheric pressure is approximately -33°C, its temperature at atmospheric pressure must be maintained below this level in order to transport and store it in its high-energy-density liquid state. Furthermore, maintaining a liquid state at ambient temperatures requires high pressures, such as 0.43 MPa at 0°C, 0.86 MPa at 20°C, and 1.55 MPa at 40°C. Therefore, when using liquid ammonia as a fuel for diesel engines, boilers, and gas turbines, either an insulated, low-temperature storage container and fuel supply system or a pressurized storage container and fuel supply system are required.

[0036] Because the boiling point of ammonia under atmospheric pressure is approximately -33°C, if ammonia is stored under pressure, it will vaporize and be released in gaseous form if a crack, hole, or leak occurs in the tank storing the ammonia or in the piping supplying the ammonia. Vaporized ammonia (NH3) has a molecular weight of 17, which is lighter than the molecular weight of air (approximately 29), so it will move upward in the atmosphere. For this reason, safety issues are reduced when ammonia storage and transport equipment is installed outdoors. However, if the equipment is installed indoors, especially at the bottom of an enclosed space such as a ship, ammonia will spread throughout the enclosed space (engine room) and continue to erupt from the bottom, potentially causing a major disaster.

[0037] In contrast, the heat of vaporization (heat of evaporation) of ammonia is approximately 1370 kJ / kg, which is lower than the approximately 2250 kJ / kg of water, but is higher than that of other substances. Taking advantage of this property, ammonia can be maintained in a liquid state by using the heat of vaporization (heat of evaporation) generated when it evaporates to lower the temperature of the ammonia itself. By using this device and method, even if ammonia leaks from cracks, holes, or joints in the tank that stores ammonia or the piping that supplies ammonia, the ammonia will not erupt as long as the pressure in the tank that stores ammonia or the piping that supplies ammonia is the same as atmospheric pressure. Since the temperature outside, including the atmosphere, is higher than that of a tank that stores ammonia in a liquid state below -33°C or a piping that supplies ammonia, the vaporization of the leaked ammonia lowers the temperature of the vaporized ammonia and its surrounding areas, thereby preventing the ammonia from erupting (leaking).

[0038] Taking advantage of these characteristics, in the present invention, a device (3) is installed that sucks vaporized ammonia from the ammonia tank and piping and maintains the pressure inside the ammonia tank and piping at or below atmospheric pressure. This utilizes the heat of vaporization (heat of evaporation) generated when the ammonia evaporates to lower the temperature of the ammonia itself and maintain it in a liquid state, and by maintaining the pressure inside the ammonia supply tank (2) and the piping that transports it at or below atmospheric pressure, even if cracks, holes, or gaps occur in the tank that stores the ammonia or the piping that supplies the ammonia, the ammonia will not leak to the outside, but will instead draw in outside air. Since the drawn-in outside air has a lower density than liquid ammonia, it will remain at a position higher than the liquid level in the ammonia supply tank (2), and will not be mixed into the piping that supplies the ammonia installed below the ammonia supply tank (2) to the diesel engine, boiler, or gas turbine.

[0039] When the pressure in the tank (2) supplying ammonia and the piping for transporting it is maintained at or below atmospheric pressure, if a crack, hole, or gap occurs in the tank storing the ammonia or the piping supplying the ammonia, allowing outside air to flow in and remain in the tank, due to the density difference between the liquid ammonia, vaporized ammonia, and the inflowing outside air (air) in the tank, layers of vaporized ammonia, the inflowing outside air (air), and liquefied ammonia will form in the tank from the top of the tank. Utilizing this characteristic, by installing a sensor that detects gas flowing in slightly above the liquid ammonia level (for example, an oxygen concentration sensor in the case of air), it becomes possible to detect the inflow of outside air due to a crack, hole, or gap in the tank storing the ammonia or the piping supplying the ammonia.

[0040] A large amount of nitrogen oxides are generated from combustion equipment (7) in diesel engines, boilers, and gas turbines that use ammonia as fuel, so a nitrogen oxide reduction device (5) is required to convert these into nitrogen and water using a catalyst and a reducing agent.Currently, ammonia produced from urea is used as the reducing agent in nitrogen oxide reduction devices, but this system uses a device (3) that sucks in vaporized ammonia and compresses it to increase its temperature and pressure, and uses the vaporized ammonia, whose temperature and pressure have been increased, discharged from this device as the reducing agent directly, thereby eliminating the need for a urea tank, urea injection device, or device that converts urea to ammonia.

[0041] In Figure 2, vaporized ammonia is sucked in to reduce the pressure inside the ammonia tank and piping below atmospheric pressure, and the temperature of the ammonia at the outlet of the device that compresses the sucked in ammonia to increase its temperature and pressure is raised above atmospheric temperature, and the pressure is raised above atmospheric pressure, making it possible to use the vaporized ammonia directly as a reducing agent in the nitrogen oxide reduction device (5). In the present invention, a flow rate control valve V-2 for vaporized ammonia is installed between the device (3) that sucks in vaporized ammonia and compresses it to increase its temperature and pressure, and the nitrogen oxide reduction device (5), so that an amount of vaporized ammonia optimal for the nitrogen oxides contained in the exhaust gas is supplied to the nitrogen oxide reduction device (5).

[0042] FIG. 3 shows an example of the detection and discharge functions for detecting and discharging air intake due to damage to the ammonia supply system installed inside an ammonia tank according to an embodiment of the present invention. In FIG. 3 , by installing an oxygen concentration sensor (14) several centimeters above the ammonia liquid level, it is possible to detect air inflow due to cracks, holes, or gaps in the ammonia storage tank or the ammonia supply piping. By placing a float equipped with the sensor on the ammonia liquid level, the oxygen concentration sensor (14) can constantly detect the presence of air accumulating near the liquid level, even if the liquid level changes due to the replenishment or consumption of liquid ammonia. This is because, if a crack, hole, or gap occurs in the ammonia storage tank (1), the ammonia supply tank (2), or the ammonia supply piping, allowing outside air to inflow and remain in the tank, due to the density differences between the liquid ammonia, vaporized ammonia, and the inflowing outside air (air) within the tank, layers of vaporized ammonia, the inflowing air, and liquefied ammonia will form in the tank from the top of the tank. Furthermore, outside air that flows in through cracks, holes, or gaps in the joints of the tank and the piping that supplies ammonia remains inside the tank, between the liquid ammonia at the bottom of the tank and the gaseous ammonia at the top of the tank. Therefore, by continuously sucking this air in and releasing it into the atmosphere either as is or after some kind of post-processing, it becomes possible to continuously discharge the outside air that has flowed into the ammonia storage and supply system and continue operation.

[0043] FIG. 4 shows an example of a specific configuration according to an embodiment of the present invention. In FIG. 4, a tank (2) for supplying ammonia is surrounded by a sealable double structure, and the interior of this double structure is connected to a vacuum pump (15) and a blower (16). The vacuum pump and the double structure can be separated using an on-off valve V-4. The blower (16) and the double structure can also be separated using an on-off valve V-5. On the opposite side of the on-off valve V-5 installed in the double structure, an on-off valve V-6 is installed; when the on-off valve V-6 is opened, the double structure is open to the outside, and when the on-off valve V-6 is closed, the double structure is closed to the outside, i.e., it becomes an airtight space.

[0044] This device is used when it is necessary to increase the amount of ammonia supplied to the nitrogen oxide reduction device (5) shown in Figure 1. In Figure 4, by closing on-off valves V-5 and V-6 and opening on-off valve V-4 to operate the vacuum pump (15), the inside of the sealed double space is evacuated, and the temperature inside the ammonia supply tank (2) can be maintained. When the pressure inside the sealed double space reaches a set value, the operation of the vacuum pump (15) is stopped and on-off valve V-4 is closed, thereby maintaining the pressure in the sealed double space.

[0045] In Figure 4, by operating the blower (16) with the on-off valve V-4 closed and the on-off valves V-5 and V-6 open, outside air (air) with a temperature higher than the temperature of the ammonia stored in the tank (approximately -33°C or lower) flows into and out of the double structure formed around the ammonia supply tank (2), promoting the evaporation of the ammonia stored in the tank. This makes it possible to increase the amount of ammonia supplied to the nitrogen oxide reduction device (5) shown in Figure 1.

[0046] Figure 5 shows an example of an apparatus for effectively evaporating ammonia in a fuel supply tank according to an embodiment of the present invention. In Figure 5, a heating device (17) is installed between the blower (16) and the dual structure to promote the vaporization of ammonia stored in the ammonia supply tank (2), thereby enabling an increase in the amount of ammonia supplied to the nitrogen oxide reduction system (5) shown in Figure 1. Also, as shown in Figure 5, a partition is installed within the tank to increase the contact area and retention time of the air flowing into the dual structure, thereby further promoting the vaporization of ammonia stored in the supply tank (2), enabling an increase in the amount of ammonia supplied to the nitrogen oxide reduction system (5) shown in Figure 1.

[0047] By installing this invention in diesel engines, boilers, and gas turbines, it becomes possible to safely store and supply ammonia, burn it effectively and efficiently in the combustion chamber, and reduce the amount of nitrogen oxides produced during combustion.

[0048] 1. Ammonia storage tank 2. Ammonia supply tank 3. Equipment that sucks in vaporized ammonia to lower the pressure inside the ammonia tank and piping below atmospheric pressure, and compresses the sucked in ammonia to raise the temperature and pressure 4. Equipment that cools and condenses ammonia whose temperature and pressure have increased 5. Nitrogen oxide reduction equipment 6. Ammonia supply pump 7. Combustion equipment for diesel engines, boilers, and gas turbines 8. Combustion chambers for diesel engines, boilers, and gas turbines 9. Blower 10. Ammonia detector 11. Heat exchanger 12. Fuel (fuel to support the combustion of ammonia) tank 13. Equipment that supplies electrical energy 14. Oxygen concentration sensor 15. Vacuum pump 16. Blower 17. Heater V-1. Ammonia supply main valve V-2. Flow rate adjustment valve for ammonia supplied to the nitrogen oxide reduction equipment V-3. Pressure adjustment valve V-4. Vacuum pump communication valve V-5. Blower communication valve

Claims

1. A system for safely storing and burning ammonia, characterized in that a device is installed in an ammonia storage tank installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, to reduce the pressure inside the ammonia tank to a value lower than atmospheric pressure in order to prevent ammonia from leaking from the tank to the outside, including into the atmosphere.

2. A method for safely storing and burning ammonia, characterized in that in a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device is installed to make the pressure inside the ammonia tank lower than atmospheric pressure, thereby preventing ammonia from leaking from the tank to the outside, including into the atmosphere.

3. A system for safely storing and burning ammonia, characterized in that a device is installed in the piping for storing and transporting ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, to reduce the pressure inside the ammonia piping to a value lower than atmospheric pressure in order to prevent ammonia from leaking from the piping to the outside, including the atmosphere.

4. A method for safely storing and burning ammonia, characterized in that in piping for storing and transporting ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device is installed to reduce the pressure inside the ammonia piping to a value lower than atmospheric pressure, thereby preventing ammonia from leaking from the piping to the outside, including into the atmosphere.

5. A system for safely storing and burning ammonia as described in claim 1, characterized in that in a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, the system is equipped with: a device for sucking vaporized ammonia inside the ammonia tank and maintaining the pressure inside the ammonia tank at or below atmospheric pressure in order to prevent ammonia from leaking from the tank to the outside, including into the atmosphere, by making the pressure inside the ammonia tank lower than atmospheric pressure; a device for compressing the sucked vaporized ammonia to increase the temperature and pressure; a device for condensing and liquefying the compressed gaseous ammonia by lowering the temperature of the compressed gaseous ammonia whose temperature and pressure have been increased; and a device for returning the liquefied ammonia to the ammonia tank.

6. A method for safely storing and burning ammonia as described in claim 2, characterized in that in a tank for storing ammonia installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device for sucking vaporized ammonia inside the ammonia tank and maintaining the pressure inside the ammonia tank at or below atmospheric pressure, a device for compressing the sucked vaporized ammonia to increase the temperature and pressure, a device for condensing and liquefying the compressed gaseous ammonia by lowering the temperature of the ammonia whose temperature and pressure have been increased, and a device for returning the liquefied ammonia to the ammonia tank are installed, thereby preventing ammonia from leaking from the tank to the outside, including the atmosphere.

7. A system for safely storing and burning ammonia as described in claim 1 or 3, characterized in that it is equipped with a system that can detect cracks, holes or gaps that have occurred in the tank storing ammonia or in the piping supplying ammonia using an oxygen concentration sensor installed near the liquid level inside the ammonia tank, taking advantage of the characteristic that when a crack, hole or gap occurs in the tank storing ammonia or in the piping supplying ammonia and air flows in due to the density difference between liquid ammonia, vaporized ammonia, and the flowing in outside air (air), layers of vaporized ammonia, the flowing in air, and liquefied ammonia are formed in that order from the top of the tank into which outside air has flowed in.

8. A system for safely storing and burning ammonia as described in claim 1 or 3, characterized in that it is equipped with a device which continuously draws in outside air which has flowed into the ammonia storage and supply system and continuously releases it into the atmosphere either as is or after some kind of post-processing, taking advantage of the characteristic that outside air which has flowed in through cracks, holes or gaps in the joints of the tank and the piping which supplies ammonia remains somewhere between the liquid ammonia at the bottom of the tank and the gaseous ammonia at the top of the tank due to the difference in density.

9. A system for safely storing and combusting ammonia as described in claim 1 or 3, characterized in that in a combustion device installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, a device for improving ammonia combustion using electrical energy supplied from a device for supplying electrical energy is installed in order to reduce the mixed combustion ratio of fuels containing carbon (C) to zero, thereby reducing CO2 emissions from the diesel engine, boiler, or gas turbine that uses ammonia as fuel to zero.

10. A method for safely storing and combusting ammonia as described in claim 2 or 4, characterized in that in a combustion device installed in a diesel engine, boiler, or gas turbine that uses ammonia as fuel, the method uses electrical energy supplied from an electrical energy supply device to improve ammonia combustion and reduce the co-combustion rate of fuel containing carbon (C) to zero, thereby reducing CO2 emissions from the diesel engine, boiler, or gas turbine that uses ammonia as fuel to zero.

11. A system for safely storing and burning ammonia as described in claim 1, characterized in that a vacuum insulation device is installed around the entire circumference or part of the circumference of a tank for storing ammonia to form an airtight structure, and valves are installed at multiple locations in the airtight space formed between the tank and the vacuum insulation device, so that when all valves are closed and the vacuum insulation device is operated, it is possible to keep the temperature inside the tank low, and when some of the valves are opened and a fluid with a temperature higher than the boiling point of the ammonia stored in the tank is circulated, it is possible to promote the evaporation of the ammonia stored in the tank.

12. A system for safely storing and burning ammonia as described in claim 1 or 3, characterized in that it comprises a device for increasing the temperature and pressure of vaporized ammonia inside the ammonia tank by sucking in and compressing it in order to reduce nitrogen oxides (NOx) produced by the combustion of ammonia, and supplying the ammonia to a selective nitrogen oxide reduction (SCR) device installed in the exhaust pipe.

13. A system for safely storing and combusting ammonia as described in claim 1 or 3, characterized in that it comprises a device for maintaining the pressure inside the ammonia supply system from the ammonia tank to the ammonia supply pump at a value lower than atmospheric pressure by adjusting the opening of a supply valve installed in the ammonia tank while a pump (ammonia supply pump) for supplying ammonia to a diesel engine, boiler, or gas turbine combustion device is in operation, in order to prevent leakage from the ammonia supply system.

14. A system for safely storing and burning ammonia as described in claim 1 or 3, characterized in that in the ammonia supply system, when the internal pressure becomes higher than atmospheric pressure, ammonia is not released to the outside even if it leaks from the ammonia supply system, and an ammonia concentration meter is installed in a space that is sealed and covered by a container in the part where the internal pressure becomes higher than atmospheric pressure, so that ammonia leakage can be detected quickly.

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