Ship liquid ammonia supply and removal system with zero ammonia residue

Abstract

A zero-ammonia-residue ship liquid ammonia supply and removal system is characterized in that firstly, 30barg high-pressure nitrogen is used for purging a liquid ammonia supply system and the interior of a main engine, and most ammonia fuel is removed; the residual ammonia is further absorbed by using fresh water, the fresh water after absorbing the ammonia is completely blown away by using 30 barg of high-pressure nitrogen, and finally, the liquid ammonia supply system and the interior of the main machine are forcibly evaporated and blown by using 5 barg of heated low-pressure nitrogen, so that the effect of zero ammonia residue is finally achieved. After the device is used for removing the interiors of a liquid ammonia supply system and a main engine, zero ammonia residue can be realized, the removing effect is good, the safety of related systems and personnel on a ship can be guaranteed, the whole ammonia removing process is automatically executed after the main engine runs in an ammonia fuel mode, automatic treatment of ammonia can be realized, personnel operation is not needed, the automation degree is high, and the working efficiency is high. The operation is reliable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ship liquid ammonia fuel supply, and particularly relates to a ship liquid ammonia supply cleaning system with zero ammonia residue. BACKGROUND

[0002] The demand for green and environmentally friendly ships in the shipping industry is growing, and it is urgent to develop and apply innovative technologies and introduce alternative fuels and other emission reduction measures in the shipping industry. Using low-carbon or even zero-carbon fuels to replace traditional ship fuels is an important measure for the shipping industry to reduce emissions. Among many new types of fuels, ammonia is one of the potential zero-carbon fuels, which can be stored on ships at a temperature of minus 33°C, has an acceptable energy density, does not produce carbon and sulfur compounds when burned, is easy to store and transport, has abundant energy and low price, and has become the focus of industry research.

[0003] Similar to the LNG supply system, after the liquid ammonia fuel supply system is used, or before it needs to be overhauled, nitrogen is used to purge the entire supply system and the internal engine to ensure that there is no ammonia fuel residue to avoid danger. Since LNG is gaseous in the supply system, it can be easily blown out, but ammonia is liquid in the supply system, which is easy to accumulate and remain in the welds, elbow pipes, recesses of various equipment and pipe accessories, and blind ends of the pipeline, and it is difficult to completely purge and determine whether it has been completely purged. Moreover, unlike natural gas, ammonia gas is toxic, and if it is not completely removed, the following problems may occur:

[0004] First, ammonia has strong corrosive properties, and long-term residual ammonia can cause corrosion of equipment and pipelines, leading to system failure and even leakage risk.

[0005] Second, if the liquid ammonia fuel is not completely blown out and remains in the supply system or the engine, over time, the liquid ammonia slowly absorbs heat and evaporates, causing the pressure in the system to increase, which may cause the risk of system overpressure.

[0006] Third, if the supply system or the engine is not completely purged and residual liquid ammonia is exposed to the atmosphere, it will quickly evaporate and diffuse, and its toxicity will pose a serious threat to the personal safety of maintenance personnel, and even pose an explosion risk. SUMMARY

[0007] To solve the above problems, the application provides a ship liquid ammonia supply cleaning system with zero ammonia residue, which aims to completely purge the ammonia gas in the internal engine. The technical scheme adopted is:

[0008] A kind of zero ammonia residual ship liquid ammonia supply cleaning system, before liquid ammonia supply system operation, compressed dry air is provided to nitrogen generator by air compressor and air dryer, and the nitrogen produced is stored in nitrogen low-pressure tank.

[0009] Nitrogen booster stores further pressurized nitrogen in nitrogen high-pressure tank, fresh water buffer tank is filled with fresh water by fresh water system on ship, and maintains 80% liquid level water amount, nitrogen low-pressure tank, nitrogen high-pressure tank and fresh water buffer tank are filled with nitrogen and fresh water respectively, and the whole ammonia cleaning system is ready.

[0010] The ship can only sail when ammonia cleaning system is ready, after main engine load reaches 25%, main engine operation switches from diesel mode to ammonia fuel mode, and switches back to diesel mode when the ship is about to arrive at port, after switching back to diesel mode, liquid ammonia remaining in liquid ammonia supply system and main engine is first purged by high-pressure nitrogen, after first purging, nitrogen is then absorbed by fresh water, after fresh water absorbs ammonia, second purging is then carried out by high-pressure nitrogen, and third purging is then carried out by low-pressure nitrogen heating.

[0011] The above-mentioned zero ammonia residual ship liquid ammonia supply cleaning system is further connected by pipeline in sequence with air dryer, nitrogen generator and nitrogen low-pressure tank for air compressor, connected by pipeline in sequence with electric heater and main engine for nitrogen low-pressure tank, and connected by pipeline in sequence with nitrogen booster, nitrogen high-pressure tank and main engine.

[0012] The main engine is connected by pipeline with ammonia treatment unit and ammonia water collection cabinet, the ammonia treatment unit is connected with air-permeable mast, the main engine is provided with second remote control valve and ammonia gas concentration transmitter on the access to ammonia treatment unit, and is provided with pressure transmitter and fourth remote control valve on the access to ammonia water collection cabinet.

[0013] The main engine is connected with fresh water buffer tank, and the fresh water buffer tank is provided with fresh water transfer pump and third remote control valve on the access to main engine.

[0014] The above-mentioned zero ammonia residual ship liquid ammonia supply cleaning system is further connected by pipeline in sequence with air dryer, nitrogen generator and nitrogen low-pressure tank for air compressor, connected by pipeline in sequence with electric heater and main engine for nitrogen low-pressure tank, and connected by pipeline in sequence with nitrogen booster, nitrogen high-pressure tank and main engine.

[0015] The above-mentioned zero ammonia residual ship liquid ammonia supply cleaning system is further connected by pipeline in sequence with air dryer, nitrogen generator and nitrogen low-pressure tank for air compressor, connected by pipeline in sequence with electric heater and main engine for nitrogen low-pressure tank, and connected by pipeline in sequence with nitrogen booster, nitrogen high-pressure tank and main engine.

[0016] The above-mentioned zero ammonia residual ship liquid ammonia supply cleaning system is further connected by pipeline in sequence with air dryer, nitrogen generator and nitrogen low-pressure tank for air compressor, connected by pipeline in sequence with electric heater and main engine for nitrogen low-pressure tank, and connected by pipeline in sequence with nitrogen booster, nitrogen high-pressure tank and main engine.

[0017] The zero-ammonia-residual marine liquid ammonia supply and removal system further comprises that the central control system controls the first remote control valve, the second remote control valve, the third remote control valve, the fourth remote control valve and the fifth remote control valve.

[0018] The zero-ammonia-residual marine liquid ammonia supply and removal system further comprises that when the high-pressure nitrogen blowing operation is used, the ammonia concentration transmitter monitors the ammonia concentration in the pipeline, and when the ammonia concentration is reduced to 300 ppm, the first remote control valve and the second remote control valve are closed.

[0019] The zero-ammonia-residual marine liquid ammonia supply and removal system further comprises that when the low-pressure nitrogen heating blowing operation is used, the ammonia concentration transmitter monitors the ammonia concentration in the pipeline, and when the ammonia concentration is reduced to 1 ppm or less, the fifth remote control valve and the second remote control valve are closed.

[0020] The zero-ammonia-residual marine liquid ammonia supply and removal system further comprises that when the low-pressure nitrogen heating blowing operation is used, the pressure regulating valve adjusts the low-pressure nitrogen to 5 barg, and then sends the low-pressure nitrogen to the electric heater to heat to 70 DEG C.

[0021] The zero-ammonia-residual marine liquid ammonia supply and removal system has the following beneficial effects:

[0022] 1. After the liquid ammonia supply system and the main engine are cleaned using the zero-ammonia-residual marine liquid ammonia supply and removal system, ammonia can be completely removed, and the ammonia removal effect is good.

[0023] 2. The zero-ammonia-residual marine liquid ammonia supply and removal system can ensure the safety of related systems and personnel on the ship.

[0024] 3. After the ammonia fuel mode of the main engine is completed, the ammonia removal process is automatically executed, and ammonia can be automatically processed without manual operation, so that the automation degree is high and the operation is reliable. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a system schematic diagram of the zero-ammonia-residual marine liquid ammonia supply and removal system;

[0026] 1-air compressor, 2-air dryer, 3-nitrogen generator, 4-nitrogen low-pressure tank, 5-nitrogen booster, 6-nitrogen high-pressure tank, 7-fresh water buffer tank, 8-main engine, 9-first remote control valve, 10-second remote control valve, 11-ammonia concentration transmitter, 12-ammonia treatment unit, 13-air vent mast, 14-third remote control valve, 15-fresh water transfer pump, 16-pressure transmitter, 17-fourth remote control valve, 18-ammonia water collection cabinet, 19-fifth remote control valve, 20-pressure regulating valve, 21-electric heater. DETAILED DESCRIPTION

[0027] The zero-ammonia-residual marine liquid ammonia supply and removal system will be further described in combination with the drawings.

[0028] A kind of zero ammonia residual ship liquid ammonia supply cleaning system, such as Figure 1 As shown in the liquid ammonia supply system and main engine operation, it has passed air compressor 1, air dryer 2, compressed, dry air is provided to membrane nitrogen generator 3, the nitrogen produced is stored in nitrogen low-pressure tank 4, and the storage pressure is 10barg.Nitrogen is further pressurized by nitrogen booster 5, and stored in nitrogen high-pressure tank 6, and the storage pressure is 30barg.Fresh water buffer tank 7 is filled with fresh water by the fresh water system on the ship, and a certain amount of water is maintained at a certain liquid level.Above all, before the liquid ammonia supply system and the main engine are operated, the nitrogen low-pressure tank, the nitrogen high-pressure tank and the fresh water buffer tank have been filled with nitrogen and fresh water respectively, and the entire ammonia cleaning system is ready.

[0029] The ship can only sail under the condition that the ammonia cleaning system is ready, and the main engine is switched from diesel to ammonia fuel mode after the load reaches 25%.After switching back to diesel mode when the ship is about to arrive at the port, liquid ammonia is left in the liquid ammonia supply system and the main engine 8, and the ammonia cleaning system in standby starts to work, and the specific process can be divided into the following four operation steps:

[0030] Step one: high-pressure nitrogen purge operation.Open the first remote control valve 9 and the second remote control valve 10, and use 30barg high-pressure nitrogen to purge the inside of the liquid ammonia supply system and the main engine 8.During the purging process, the ammonia concentration after purging can be monitored in real time by the ammonia gas concentration transmitter 11 in the central control system, and when the concentration is about 300ppm, the first remote control valve 9 and the second remote control valve 10 can be closed to stop the high-pressure nitrogen purge operation.After purging, the mixture containing liquid ammonia, ammonia and nitrogen enters the ammonia treatment unit 12, where the liquid ammonia is recycled as fuel, the ammonia is absorbed and treated, and the remaining nitrogen is discharged into the atmosphere through the air vent 13.

[0031] Step two: fresh water absorption operation.After the above high-pressure nitrogen purge operation is completed, open the third remote control valve 14, and use the fresh water transfer pump 15 to transport the fresh water in the fresh water buffer tank 7 to the inside of the liquid ammonia supply system and the main engine, and use the fresh water to absorb the ammonia still remaining in the high-pressure nitrogen after purging, by virtue of the characteristic that ammonia is easily soluble in water.As the fresh water slowly fills the inside of the liquid ammonia supply system and the main engine, the pressure value detected by the pressure transmitter 16 will increase, and when it reaches the set value, it means that the fresh water has been filled, at which point the third remote control valve 14 and the fresh water transfer pump 15 are automatically closed by the central control system, and then the central control system automatically takes water from the fresh water system on the ship to fill the fresh water buffer tank 7 to about 80% liquid level, ready for the next use.

[0032] Step three: high pressure nitrogen gas purging secondary operation. After the above fresh water absorption operation is completed, open the first remote control valve 9 and the fourth remote control valve 17, and use high pressure nitrogen gas to purge the fresh water into the ammonia water collection cabinet 18, and the remaining nitrogen gas containing a small amount of ammonia gas is discharged through the gas venting mast after passing through the ammonia treatment unit 12. After the operation is completed, close the first remote control valve 9 and the fourth remote control valve 17.

[0033] Step four: low pressure nitrogen gas heating purging operation. After the above high pressure nitrogen gas purging secondary operation is completed, at this time the liquid ammonia supply system and the main machine inside have been basically cleaned, open the fifth remote control valve 19 and the second remote control valve 10, and adjust the low pressure nitrogen gas to 5 barg through the pressure regulating valve 20, then heat it to about 70°C through the electric heater 21, and then enter the liquid ammonia supply system and the main machine inside, to force the evaporation of the remaining small amount of fresh water and ammonia and discharge it through the ammonia treatment unit and the gas venting mast. During the process, the ammonia gas concentration is monitored in real time through the ammonia gas concentration transmitter 11, and when it is reduced to below 1 ppm, the fifth remote control valve 19 and the second remote control valve 10 are closed, and the entire ammonia removal operation is completed. At this time, the liquid ammonia supply system and the main machine inside are completely dry and filled with nitrogen gas, and the ammonia has been completely removed, and there will be no safety hazards due to ammonia residues in the future.

Claims

1. A zero-ammonia-residue marine liquid ammonia supply scavenging system characterized by, The air compressor (1) is connected with the air dryer (2), the nitrogen generator (3) and the nitrogen low-pressure tank (4) in sequence through pipelines, the nitrogen low-pressure tank is connected with the electric heater (21) and the main machine (8) in sequence through a pipeline, and is connected with the nitrogen booster (5), the nitrogen high-pressure tank (6) and the main machine in sequence through another pipeline; the fifth remote control valve (19) is arranged on the passage of the electric heater to the main machine, and the first remote control valve (9) is arranged on the passage of the nitrogen high-pressure tank to the main machine; The main machine is connected with the ammonia treatment unit (12) and the ammonia water collecting cabinet (18) through pipelines, the ammonia treatment unit is connected with the air breather mast (13), the second remote control valve (10) and the ammonia gas concentration transmitter (11) are arranged on the passage of the main machine to the ammonia treatment unit, and the pressure transmitter (16) and the fourth remote control valve (17) are arranged on the passage of the main machine to the ammonia water collecting cabinet. The main machine is connected with the fresh water buffer tank (7), and the fresh water transfer pump (15) and the third remote control valve (14) are arranged on the passage of the fresh water buffer tank to the main machine.

2. A marine liquid ammonia supply purge system with zero ammonia slip according to claim 1, characterized in that, The storage pressure of the nitrogen low-pressure tank is 10 barg.

3. A zero-ammonia-residue marine liquid ammonia supply scavenging system according to claim 1, characterized in that, The storage pressure of the nitrogen high-pressure tank is 30 barg.

4. A zero-ammonia-residue marine liquid ammonia supply scavenging system according to claim 1, characterized in that, The inlet of the electric heater is provided with a pressure regulating valve.

5. A zero-ammonia-residue marine liquid ammonia supply scavenging system according to claim 1, characterized in that, The central control system controls the fresh water transfer pump, the first remote control valve, the second remote control valve, the third remote control valve, the fourth remote control valve and the fifth remote control valve.

6. A zero-ammonia-residue marine liquid ammonia supply scavenging system according to claim 1, characterized in that, When the ammonia gas concentration transmitter monitors that the ammonia gas concentration in the pipeline is reduced to 300 ppm, the first remote control valve and the second remote control valve are closed.

7. A zero-ammonia-residue marine liquid ammonia supply scavenging system according to claim 1, characterized in that, When the ammonia gas concentration transmitter monitors that the ammonia gas concentration in the pipeline is reduced to 1 ppm or below, the fifth remote control valve and the second remote control valve are closed.

8. A marine liquid ammonia supply purge system with zero ammonia slip according to claim 4, wherein, After the pressure regulating valve adjusts the low-pressure nitrogen to 5 barg, the low-pressure nitrogen is sent to the electric heater to be heated to 70 DEG C.

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