In the context of green transformation in shipping, methanol is widely used as a low emission alternative
Fuel for marine
engines in inland and offshore ships. Compared to traditional
Diesel Engines, methanol has the advantages of low sulfur and low carbon, but it is toxic, volatile, and corrosive, requiring special requirements for installation processes, pipeline materials, safety protection, and crew operation. Many ships, in the process of retrofitting or installing methanol engines, face risks such as leakage, poisoning, and fire due to neglecting classification society regulations, selecting incorrect pipeline materials, and lacking safety systems. This article combines practical experience to explain the key points of pre preparation, on-site installation, commissioning and acceptance, standardized operation, and daily maintenance of methanol marine engines.
1、 Pre installation preparation and ship adaptation assessment
The installation of methanol marine engines cannot be directly copied from the construction process of ordinary diesel engines. Pre evaluation is the foundation for safe operation. Firstly, the space review of the ship's engine room should be completed. In addition to the main engine, the methanol model is also equipped with a methanol supply unit, nitrogen purging system, and leak detection alarm device. The engine room needs to reserve maintenance and ventilation space, and the fuel preparation room should be isolated from the engine room. The methanol delivery pipeline should preferably adopt a double wall pipe structure.
Material selection is crucial. Methanol is corrosive, and galvanized steel and ordinary aluminum alloy are prohibited from being used in fuel pipelines and valves. 316L stainless steel is preferred, and sealing materials such as polytetrafluoroethylene and perfluoroether rubber are made of alcohol resistant materials to prevent leakage faults caused by medium corrosion. At the same time, it is confirmed that the fuel tank and methanol tank adopt a double shell structure, equipped with nitrogen inerting protection and supporting waste liquid collection devices.
Construction personnel must be familiar with the specifications for methanol fuel ships, hold qualifications for installing marine power equipment, read the relevant guidelines for CCS methanol fuel ships, equip with methanol concentration detectors, explosion-proof tools, chemical protective equipment, prepare installation and construction plans and emergency response plans, and complete ship inspection and reporting work.
2、 Host positioning and piping installation construction
Lift the host into place, locate the center of gravity according to the drawing, use a lifting device to smoothly lower it to the machine base, adjust it with shims to complete the axis alignment, strictly control the alignment deviation, and avoid excessive vibration in the later stage that may damage the entire machine and pipeline joints. After the fastening of the machine base is completed, the installation of the cooling system, lubricating oil system, and exhaust system should be carried out in sequence.
The methanol fuel pipeline system is the core installation link, and all methanol pipelines should be routed reasonably to reduce unnecessary joints and minimize the risk of leakage; Double walled pipes must be used to pass through the cabin area, with a leak detection interface set in the interlayer. After the welding of the pipeline is completed, a series cleaning is carried out to remove internal impurities and avoid damage to the high-pressure spray components caused by impurities. After the completion of the pipeline, a pressure sealing test shall be conducted to confirm that there is no leakage. Clear methanol medium warning signs shall be posted on the outer wall of the pipeline.
Synchronize the construction of electrical and safety systems, install methanol gas detection alarms in the engine room and fuel preparation room, and connect the alarm signals to the ship monitoring system; Set up an emergency shut-off valve to quickly cut off methanol supply in case of leakage alarm. The whole machine and pipeline metal components are reliably grounded to eliminate the risk of static electricity accumulation, and the supporting ventilation system ensures air circulation in the cabin.
3、 Complete machine debugging and ship inspection and acceptance
All mechanical, piping, and electrical installations have been completed, and direct introduction of methanol fuel for start-up is prohibited. Firstly, carry out static debugging to complete the circulation exhaust of the cooling water circuit and lubricating oil system, verify the security system, alarm output, emergency cut-off, and nitrogen purging functions, and confirm that the sensor signal feedback is normal.
First, conduct a trial run in diesel mode to check the starting, idle, and various load operating conditions of the entire machine, and investigate vibration, abnormal noise, and leakage issues. After passing the diesel mode test, methanol fuel is then connected to complete the fuel system purge and replacement, gradually switching to methanol mode. The test progresses from low load to rated load to verify the dual fuel switching logic, check the working status of the injection system, and verify key parameters such as exhaust temperature and cylinder pressure.
The overall load test, mode switching test, and security protection test have all met the standards. The construction drawings, material certificates, pipeline test reports, and commissioning records have been organized, and the ship inspection has been completed to obtain relevant certificates. At the same time, special training has been provided to the engine crew to master the operation of methanol engines, risk identification, and emergency response.
4、 Standard Operating Procedure for Methanol Marine Engines
During the preparation phase of the ship, the crew checked the pressure of the methanol tank and the inerting status of the nitrogen gas. The methanol concentration detector showed normal readings, the ventilation system was turned on, and it was confirmed that there was no leakage in the fuel pipeline. Priority should be given to completing the pre check before starting. If there are no faults in the alarm system, diesel mode can be used to start the engine first, and then switch to methanol mode after warming up. It is not recommended to operate the refrigeration unit directly using methanol.
During the navigation process, closely monitor the engine operating parameters, with a focus on methanol supply pressure, cylinder oil consumption, and lubricating oil status. Methanol combustion generates acidic substances, and it is necessary to use lubricating oil suitable for high alkali value cylinders to neutralize the acidic products produced by combustion and prevent cylinder liner corrosion and pulling. When switching between dual fuels, the lubrication system automatically matches the oil injection rate, and do not manually change the parameters at will.
Strictly follow the water refueling regulations when adding methanol fuel, ensure proper static grounding, monitor the liquid level and pressure during operation, and blow the pipeline with nitrogen after refueling. When shutting down, prioritize switching back to diesel mode and running for a few minutes to blow off residual methanol in the injection pipeline before executing the entire machine shutdown to reduce residual media inside the pipeline.
5、 Daily operation and safety precautions
Daily inspections focus on checking for leaks in methanol pipeline joints and seals, regular calibration of gas alarm equipment, and ensuring that ventilation equipment is in good condition. Regularly extract oil samples for testing, monitor whether the oil is mixed with methanol, and promptly dispose of and replace the oil if the concentration exceeds the standard. When repairing methanol related components, it is necessary to cut off the supply, blow the pipeline with nitrogen, release residual media, fully ventilate the engine room, wear protective equipment, and strictly prohibit open flame operations.
If there is a methanol leak, the emergency shutdown should be triggered immediately, and the collection device should be activated to recover the waste liquid. Do not directly flush it into the water with water; Personnel who come into contact with methanol should be washed in a timely manner. In case of alarm faults, priority should be given to stopping the machine for troubleshooting. Unauthorized personnel are prohibited from disassembling the methanol injection components. Standardizing maintenance and upkeep is necessary to fully leverage the environmental advantages of methanol engines and ensure long-term safe navigation of ships.
