An energy-saving marine ammonia energy BOG recovery and reuse system

Abstract

The present invention relates to an energy-saving marine ammonia BOG recovery and reuse system, comprising: an ammonia BOG recovery device connected to a liquid ammonia tank to achieve low-energy recycling of absorbed ammonia BOG; an NH3 injection metering device connected to the ammonia BOG recovery device to directly control the amount of BOG gas reused; a pressure regulating device for regulating the pressure between the liquid ammonia tank and the ammonia BOG recovery device, and the pressure between the ammonia BOG recovery device and the NH3 injection metering device; sensors disposed on the ammonia BOG recovery device, the NH3 injection metering device, and the liquid ammonia tank; and a control unit connected to the pressure regulating device and the sensors to control the operating state of the ammonia BOG recovery device, control the pressure regulating device to adjust the injection pressure, and adjust the NH3 injection metering device to achieve the designed pressure and dosage. The present invention can recover liquid ammonia BOG, improve energy utilization, and reduce storage costs.

Description

Technical Field

[0001] The present invention relates to an energy-saving marine ammonia energy BOG recovery device and a recycling system, belonging to the technical field of marine energy. Background Art

[0002] The shipping industry should also respond to carbon reduction targets, with increasing emphasis on research into zero-carbon fuels. Ammonia, a carbon-free fuel with high energy density and low storage pressure, has a lower room-temperature liquefaction pressure than H2 and LNG. At room temperature (25°C), it requires only 10.3 atmospheres of pressure, making its actual compression and maintenance costs far lower than other gas fuels. Consequently, it has attracted widespread attention in the shipping industry.

[0003] When transporting and using large quantities of liquid ammonia, ships experience flash gas (BOG) due to ship movement and heat, causing increased pressure within the tanks and posing a safety hazard. Gaseous NH3 is toxic, corrosive, flammable, and explosive. Discharging it directly as a gas or after absorption in water causes pollution and wastes NH3. Common recovery methods include the following: full-pressure storage and recovery, which requires high storage space and safety requirements for gaseous NH3. Cooled storage and recovery is relatively safe, but the investment is high and the recovery process is not energy-efficient. While room-temperature, low-pressure recovery is energy-efficient and requires low investment, the process is complex and places high demands on the crew. Because the daily BOG production of liquid ammonia is far lower than that of LNG, the cooling or compression recovery units must be frequently started and stopped, placing high demands on the reliability of the power recovery units.

[0004] Therefore, a more energy-saving and safer energy-saving marine ammonia energy BOG recycling system is needed. Summary of the Invention

[0005] The technical problems to be solved by the present invention are:

[0006] (1) Ammonia fuel in tanks on ships is affected by sunlight and ship movement at sea, and flash gas (BOG) will be produced during storage and use. It is difficult to recover and utilize NH3 at room temperature and pressure.

[0007] (2) The amount of liquid ammonia BOG produced is much lower than that of LNG, and the current mainstream recovery method (compression and cooling) requires additional energy consumption, which is not energy-efficient. Secondly, it will cause the cooling or compression recovery unit to start and stop frequently, affecting its service life.

[0008] To this end, the present invention provides an energy-saving marine ammonia energy BOG recovery and reuse system.

[0009] To achieve the above objectives, the technical solution of the present invention is: an energy-saving marine ammonia energy BOG recovery and reuse system, comprising:

[0010] The ammonia energy BOG recovery device is connected to the liquid ammonia tank and is used to absorb the high-pressure / low-temperature BOG gas generated in the liquid ammonia tank. After heating with waste heat, the absorbed NH3 is released, achieving low-energy reuse of the absorbed ammonia energy BOG.

[0011] NH3 injection metering device, connected to the ammonia energy BOG recovery device, is used to directly control the amount of BOG gas reuse;

[0012] The pressure regulating devices are installed on the connecting pipelines between the ammonia energy BOG recovery device and the liquid ammonia tank, and on the connecting pipelines between the NH3 injection metering device and the ammonia energy BOG recovery device, respectively, to regulate the pressure between the liquid ammonia tank and the ammonia energy BOG recovery device, and between the ammonia energy BOG recovery device and the NH3 injection metering device;

[0013] The sensor is installed on the ammonia energy BOG recovery unit to monitor the internal pressure and NH3 concentration of the ammonia energy BOG recovery unit, NH3 pressure fluctuations, NH3 leakage during the heat exchange process, and the heat regulation outlet temperature; it is installed on the NH3 injection metering device to monitor the pressure of the NH3 injection metering device and serve as the solenoid valve opening adjustment signal for the NH3 injection metering device; it is installed on the liquid ammonia tank to monitor the temperature and pressure of the hydraulic tank;

[0014] The control unit is connected to the pressure regulating device and various sensors to control the operating status of the ammonia energy BOG recovery device, control the pressure regulating device to adjust the injection process pressure, and adjust the NH3 injection metering device to achieve the design pressure and design dosage.

[0015] Furthermore, the ammonia energy BOG recovery device consists of three parts: an ammonia storage material, a heat regulation loop, and a recovery and reuse loop. The heat regulation loop and the recovery and reuse loop are two independently operating cavity loops in the tank body.

[0016] Furthermore, the heat regulation loop includes a heat regulation inlet and a heat regulation outlet. The waste hot water in the heat regulation loop enters from the heat regulation inlet and exits from the heat regulation outlet. The NH3 in the recovery and reuse loop enters from the ammonia storage inlet and is released from the ammonia storage outlet. The ammonia storage inlet is connected to the liquid ammonia storage device and can absorb the BOG generated by the liquid ammonia device. The ammonia storage outlet is connected to the use device and can provide gaseous NH3 to the use device.

[0017] Furthermore, the recovery and reuse loop is filled with ammonia storage materials and includes an ammonia storage inlet, an ammonia storage outlet, a filling port, and a cleaning port. Heat and mass transfer are carried out between the ammonia storage inlet, the ammonia storage outlet and the ammonia storage materials; the filling port and the cleaning port are operating ports for later replacement of the ammonia storage materials.

[0018] Furthermore, the ammonia energy BOG recovery device stores NH3 required for reuse. The reused NH3 comes from the following two states: one is the recovery of liquid ammonia BOG gas generated by heating or movement, and the other is the direct injection of liquid ammonia tank caused by insufficient NH3 content in the ammonia energy BOG recovery device. The ammonia storage material is a substance that can absorb NH3 when cooled and release NH3 when heated, and the substance can be recycled multiple times without drastic changes in its adsorption physical properties.

[0019] Furthermore, the pressure regulating device is an electronic pressure regulating valve, which adjusts the pressure gradient between different pressure devices according to design requirements to ensure safe operation of the equipment.

[0020] Furthermore, the NH3 injection metering device includes a nozzle structure and an electromagnetic control valve device, which are made of corrosion-resistant materials, are controlled by a control unit signal, have opening and closing adjustment capabilities, and can reuse the NH3 usage in the process.

[0021] Furthermore, the sensor includes an NH3 content sensor, a pressure sensor, and a temperature sensor, which are made of corrosion-resistant materials, and the sensor signals serve as input signals of the control unit.

[0022] Furthermore, the control unit is used to control the total amount of liquid ammonia BOG and liquid ammonia absorbed by the ammonia energy BOG recovery device, control the release of NH3 from the ammonia storage material of the ammonia energy BOG recovery device during the recycling process by controlling the heating heat, and control the pressure and injection amount of the recycling process.

[0023] A marine SCR system based on an energy-saving marine ammonia BOG recovery unit is designed. The ammonia BOG recovery unit is connected between the liquid ammonia tank and the SCR reactor. NH3 recovered by the ammonia BOG recovery unit serves as the SCR system's reducing agent, compensating for shortcomings in the SCR's reducing agent control. The NH3 in the ammonia BOG recovery unit comes from two sources: one is liquid ammonia BOG gas generated by heat or movement recovered by the ammonia BOG recovery unit; the other is direct injection of the ammonia BOG recovery unit from the liquid ammonia tank due to insufficient NH3 content in the ammonia BOG recovery unit.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Liquid ammonia (BOG) can be recovered, improving energy utilization. NH3 can be stored at room temperature, resulting in low storage costs. Solid-state storage is safer and more energy-efficient than gaseous high-pressure / low-temperature storage. It also features high ammonia storage density and a compact device.

[0026] 2. When reusing the NH3 in the energy-saving marine ammonia energy BOG recovery device, low-temperature waste heat can be used, and the NH3 storage and absorption process can be reused, which is energy-saving and environmentally friendly;

[0027] 3. The injection pressure during reuse is related to the temperature, the control is direct, and the injected NH3 is gaseous, so the transient responsiveness of the control is high;

[0028] 4. The energy-saving marine ammonia BOG recovery unit is suitable for use with SCR reactors. This device stabilizes ammonia pressure, allowing the SCR to better utilize the NH3 in the liquid ammonia tank and addressing issues with SCR reductant supply control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of an energy-saving marine ammonia energy BOG recovery device;

[0030] Figure 2 yes Figure 1 Middle AA section view;

[0031] Figure 3 This is a typical schematic diagram of the filling port / cleaning port of the energy-saving marine ammonia energy BOG recovery device.

[0032] Figure 4 yes Figure 3 Middle BB cross-section;

[0033] Figure 5 This is a schematic diagram of the anti-corrosion material pad installed on the filling port / cleaning port;

[0034] Figure 6 yes Figure 5 Middle CC section view;

[0035] Figure 7 It is an energy-saving marine ammonia energy BOG recovery and reuse system;

[0036] Figure 8 This is a schematic diagram of an energy-saving marine ammonia energy BOG recovery and reuse SCR system embodiment;

[0037] Figure numerals: ammonia storage material 1; pressure regulating device 2; energy-saving marine ammonia energy BOG recovery device 3: heat regulation inlet 3-1, heat regulation outlet 3-2, ammonia storage inlet 3-3, ammonia storage outlet 3-4, heat exchange tube 3-5, filling port 3-6, cleaning port 3-7, front end cover 3-8, rear end cover 3-9, tank body 3-10; metering device 4; sensor 5: sensor 5-1, sensor 5-2, sensor 5-3, sensor 5-4; control unit (ECU) 6; liquid ammonia tank 7; combustion equipment 8; SCR reactor 9. DETAILED DESCRIPTION

[0038] To facilitate understanding of the technical means, creative features, objectives, and effects achieved by the present invention, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate the technical solutions of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, and not all of them. All other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort are also within the scope of the present invention.

[0039] To make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0040] The present invention provides an energy-saving marine ammonia energy BOG recovery device 3, such as Figure 1 , 2. It is assembled from a filling port 3-6, a cleaning port 3-7, a front cover 3-8, a rear cover 3-9, and a tank body 3-10, and is filled with ammonia storage material 1. The device has good thermal insulation capabilities.

[0041] Among them, the structure of the filling port 3-6 is similar to that of the cleaning port 3-7, and a double cover plate design is adopted. Figure 3 , 4, bolt connection, each connection is covered with anti-corrosion material pads, see Figure 5 6. Ensure that there is no leakage of NH3 in the tank. It can meet the needs of later maintenance and replacement of ammonia storage materials 1.

[0042] Among them, the front end cover 3-8 and the tank body 3-10 are also fastened together, and the rear end cover 3-9 is similar and can be connected by bolts.

[0043] The energy-saving marine ammonia BOG recovery unit's tank 3-10 is divided into two independently operating chamber loops. In the heat regulation loop, waste hot water enters through the heat regulation inlet 3-1 and exits through the heat regulation outlet 3-2. In the recovery and reuse loop, NH3 enters through the ammonia storage inlet 3-3 and is released through the ammonia storage outlet 3-4.

[0044] Among them, the ammonia storage material is fixed in the recovery and reuse loop of the energy-saving marine ammonia energy BOG recovery device 3 tank body 3-10.

[0045] The ammonia storage inlet 3 - 3 is connected to the liquid ammonia storage device and can absorb the BOG generated by the liquid ammonia storage device.

[0046] Among them, the ammonia storage outlet 3-4 is connected to the use device and can provide gaseous NH3 to the use device.

[0047] The present invention provides an energy-saving marine ammonia energy BOG recovery and reuse system, such as Figure 7 As shown, it consists of an ammonia energy BOG recovery device, a pressure regulating device, an NH3 injection metering device, a control unit (ECU), sensors, etc.

[0048] The system is designed based on the energy-saving marine ammonia energy BOG recovery device 3, which can achieve low energy consumption and reuse of the absorbed ammonia energy BOG.

[0049] During the NH3 recycling process, the recycling amount is directly controlled by the NH3 injection metering device 4. To meet the NH3 usage pressure during the recycling process, a pressure regulating device 2 is provided between the NH3 injection metering device 4 and the ammonia energy BOG recovery device 3.

[0050] The pressure regulating device 2 can adjust the pressure gradient between different pressure devices according to design requirements to ensure safe operation of the equipment. This mainly involves the pressure between the liquid ammonia tank 7 and the ammonia energy BOG recovery device 3; and the pressure between the ammonia energy BOG recovery device 3 and the metering device 4.

[0051] The ammonia energy BOG recovery unit 3 stores NH3 required for reuse. Reused NH3 comes from two sources: one is the recovery of liquid ammonia BOG gas generated by heat or movement, and the other is direct injection into the liquid ammonia tank 7 due to insufficient NH3 content in the ammonia energy BOG recovery unit 3.

[0052] Sensor 5 serves as the signal source for the control unit (ECU) 6 and includes functions such as monitoring pressure, temperature, and NH3 content. Sensor 5-1 monitors the internal pressure and NH3 concentration of the ammonia energy BOG recovery unit 3. The NH3 concentration monitors whether the ammonia contained in the ammonia energy BOG recovery unit 3 is sufficient. During operation, sensor 5-1 monitors NH3 pressure fluctuations during the pressure buildup process of the energy-saving marine ammonia energy BOG recovery unit 3. Sensor 5-2 monitors the heat exchange process of heat exchange tube 3-5 for NH3 leakage and the temperature of the heat regulator outlet 3-2 to confirm sufficient heat exchange. Sensor 5-3 monitors the pressure of metering device 4, which serves as the solenoid valve opening adjustment signal for metering device 4. Sensor 5-4 monitors the temperature and pressure of the hydraulic tank, serving as a content and safety alarm.

[0053] The control unit (ECU) 6 controls the operating status of the energy-saving marine ammonia BOG recovery unit 3. During recovery and injection, the heat input to heat regulating inlet 3-1 is controlled based on the temperature signals from sensors 5-1 and 5-2. The injection rate of liquid ammonia tank 7 into the ammonia BOG recovery unit 3 is controlled based on the NH3 concentration signal from sensor 5-1. The pressure regulating device 2 is controlled based on the pressure signals from sensors 5-1 and 5-4 to adjust the pressure requirements during the injection process. During reuse, the pressure regulating device 2 is controlled based on the pressure signals from sensors 5-1 and 5-3 to adjust the metering device 4 to achieve the designed pressure and dosage.

[0054] Another embodiment of the present invention is a marine SCR system based on an energy-saving marine ammonia energy BOG recovery device 3, such as Figure 8 shown.

[0055] Ammonia, a high-nitrogen fuel, generates significant amounts of NOx in combustion equipment 8, requiring treatment in the SCR reactor 9. Using liquid ammonia as a reducing agent in the SCR reaction can make it difficult to control the SCR reducing agent due to its high concentration, potentially leading to ammonia leakage in the flue gas.

[0056] The energy-saving marine ammonia energy BOG recovery and reuse system can be modified to serve as the reducing agent of the SCR system, making up for the above-mentioned shortcomings of the SCR reducing agent control.

[0057] The NH3 source of the energy-saving marine ammonia energy BOG recovery device 3 can be in two states: one is that the energy-saving marine ammonia energy BOG recovery device 3 recovers liquid ammonia BOG gas generated by heat or movement; the other is that the liquid ammonia tank 7 directly injects the ammonia energy BOG recovery device 3 due to insufficient NH3 content in the ammonia energy BOG recovery device 3.

[0058] The recovery and injection process involves the following: The BOG recovery and injection signals for the energy-saving marine ammonia energy BOG recovery unit 3 are determined by the pressure signal from sensor 5-1 transmitted to the control unit (ECU) 6; the direct injection signal is determined by the concentration signal from sensor 5-1 transmitted to the control unit (ECU) 6. After throttling, high-pressure / low-temperature NH3 enters the ammonia storage inlet 3-3 and is complexed and absorbed by the ammonia storage material 1 (ball-milled SrCl2). This absorption process is exothermic. The NH3 from the liquid ammonia tank 7 is a high-pressure / low-temperature gas, and its temperature is further reduced after throttling, which promotes the complexation and absorption of NH3 by the ammonia storage material 1. Furthermore, once the pressure of the energy-saving marine ammonia energy BOG has been established, central fresh water cooling can be used to cool it down, assisting the complexation and absorption of NH3 by the ammonia storage material 1. The pressure gradient and injection rate between the liquid ammonia tank 7 and the ammonia energy BOG recovery unit 3 are regulated by the pressure regulating device 2.

[0059] The desorption and pressure buildup process is heated by waste heat. The waste heat enters the ammonia energy BOG recovery unit 3 through the heat regulation inlet 3-1 of the ammonia energy BOG recovery unit 3, where it undergoes heat exchange with the ammonia storage material 1, prompting the ammonia storage material 1 to continuously release NH3 and build up a saturated NH3 gas pressure within the tank 3-10 of the energy-saving marine ammonia energy BOG recovery unit 3. The control unit (ECU) 6 adjusts the water volume in the heat regulation inlet 3-1 based on the temperature signal from sensor 5-2 and the NH3 temperature and pressure signals from sensor 5-1 in tank 3-10, controlling the NH3 release process from the ammonia storage material 1 and, in turn, regulating the pressure within tank 3-10. The ammonia storage material 1 begins releasing NH3 in stages once it is heated to 20°C. Therefore, the cylinder jacket cooling water (~90°C) from the combustion equipment 8 can be used for the heat regulation inlet 3-1. The NH3 pressure buildup process is slower than the preparation process of the combustion equipment 8. Therefore, during the initial operation phase, the pressure buildup of tank 3-10 within the ammonia energy BOG recovery unit 3 must be prioritized over the combustion process. The marine SCR system of the energy-saving marine ammonia energy BOG recovery device 3 can switch to other stable low-temperature heat sources in the early stage, and then switch to the cylinder jacket water of the combustion equipment 8 to carry out the waste heat pressure building process after the combustion conditions are stable.

[0060] Among them, the recycling process. Ammonia is burned in the combustion equipment 8 to produce high-NOx flue gas, which enters the mixing section of the SCR reactor 9 from the combustion outlet and is directly mixed with the gaseous reducing agent NH3, which can reduce the mixing reaction time, and then enters the catalyst section of the SCR reactor 9 for reaction. The gaseous NH3 reducing agent is injected by the nozzle of the metering device 4 and injected at a set pressure. The amount of gaseous NH3 reducing agent is controlled by the control unit (ECU) 6. The injection amount is based on the flue gas flow, temperature, NOx concentration at the inlet of the SCR reactor 9, and the flue gas flow, temperature, NOx concentration and NH3 comprehensive control at the outlet. Since the SCR device uses the gaseous NH3 reducing agent from the energy-saving marine ammonia energy BOG recovery device 3, the reducing agent state is stable and easy to mix evenly with the flue gas. Therefore, it is easier to achieve efficient operation of the catalyst of the SCR reactor 9 than the original urea aqueous solution.

Claims

1. An energy-saving marine ammonia energy BOG recovery and reuse system, characterized by: include: The ammonia energy BOG recovery device is connected to the liquid ammonia tank and is used to absorb the high-pressure / low-temperature BOG gas generated in the liquid ammonia tank; after heating with the waste heat source, the absorbed NH3 is released again, realizing low-energy reuse of the absorbed ammonia energy BOG; the ammonia energy BOG recovery device consists of three parts: ammonia storage material, a heat regulation loop, and a recovery and reuse loop. The heat regulation loop and the recovery and reuse loop are two independently operated cavity loops in the tank body; the heat regulation loop includes a heat regulation inlet and a heat regulation outlet, and the waste hot water in the heat regulation loop is recycled from the heat regulation loop. The ammonia enters the ammonia quantity regulating inlet and exits the ammonia quantity regulating outlet; the NH3 in the recovery and reuse loop enters the ammonia storage inlet and is released from the ammonia storage outlet; the ammonia storage inlet is connected to the liquid ammonia storage device and can absorb the BOG generated by the liquid ammonia device; the ammonia storage outlet is connected to the use device and can provide gaseous NH3 to the use device; the recovery and reuse loop is filled with ammonia storage material and includes an ammonia storage inlet, an ammonia storage outlet, a filling port, and a cleaning port. Heat and mass transfer are carried out between the ammonia storage inlet, the ammonia storage outlet and the ammonia storage material; the filling port and the cleaning port are operation ports for replacing the ammonia storage material in the later stage; NH3 injection metering device, connected to the ammonia energy BOG recovery device, is used to directly control the amount of BOG gas reuse; The pressure regulating devices are installed on the connecting pipelines between the ammonia energy BOG recovery device and the liquid ammonia tank, and on the connecting pipelines between the NH3 injection metering device and the ammonia energy BOG recovery device, respectively, to regulate the pressure between the liquid ammonia tank and the ammonia energy BOG recovery device, and between the ammonia energy BOG recovery device and the NH3 injection metering device; The sensor is installed on the ammonia energy BOG recovery unit to monitor the internal pressure and NH3 concentration of the ammonia energy BOG recovery unit, NH3 pressure fluctuations, NH3 leakage during the heat exchange process, and the heat regulation outlet temperature; it is installed on the NH3 injection metering device to monitor the pressure of the NH3 injection metering device and serve as the solenoid valve opening adjustment signal for the NH3 injection metering device; it is installed on the liquid ammonia tank to monitor the temperature and pressure of the hydraulic tank; The control unit is connected to the pressure regulating device and various sensors to control the operating status of the ammonia energy BOG recovery device, control the pressure regulating device to adjust the injection process pressure, and adjust the NH3 injection metering device to achieve the design pressure and design dosage.

2. The energy-saving marine ammonia energy BOG recovery and reuse system according to claim 1 is characterized by: The ammonia energy BOG recovery device stores the NH3 required for reuse. The reused NH3 comes from the following two states: one is the recovery of liquid ammonia BOG gas generated by heating or movement, and the other is the direct injection of liquid ammonia tanks caused by insufficient NH3 content in the ammonia energy BOG recovery device. The ammonia storage material is a substance that can absorb NH3 when cooled and release NH3 when heated, and this substance can be recycled multiple times without drastic changes in its adsorption physical properties.

3. The energy-saving marine ammonia energy BOG recovery and reuse system according to claim 1 is characterized by: The pressure regulating device is an electronic pressure regulating valve, which adjusts the pressure gradient between different pressure devices according to design requirements to ensure safe operation of the equipment.

4. The energy-saving marine ammonia energy BOG recovery and reuse system according to claim 1 is characterized by: The NH3 injection metering device includes a nozzle structure and an electromagnetic control valve device, which are made of corrosion-resistant materials and are controlled by a control unit signal. It has the ability to adjust the opening and closing, and can reuse the NH3 used in the process.

5. The energy-saving marine ammonia energy BOG recovery and reuse system according to claim 1 is characterized by: The sensors include an NH3 content sensor, a pressure sensor, and a temperature sensor, and are made of corrosion-resistant materials. Sensor signals serve as input signals of a control unit.

6. The energy-saving marine ammonia energy BOG recovery and reuse system according to claim 1 is characterized by: The control unit is used to control the amount of liquid ammonia BOG and the total amount of liquid ammonia absorbed by the ammonia energy BOG recovery device, control the release of NH3 from the ammonia storage material of the ammonia energy BOG recovery device during the recycling process by controlling the heating heat, and control the pressure and injection amount during the recycling process.

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