Preface
Ship generator and prime mover are an important part of ship mechanical and electrical equipment, and its operation status plays a decisive role in the reliability and safety of ship operation. When the generator and prime mover fail suddenly during the ship's navigation, it is easy to cause the whole ship to lose power and the ship to lose power, and only rely on the emergency power supply to control the direction of the ship, especially when navigating in narrow waterways, it is easy to collide, run aground and other accidents.
Since April 7, the Maritime Safety Administration of the Ministry of Transport has carried out a nationwide special operation to prevent the failure of ship mechanical and electrical equipment. Next, the editor will introduce the main power supply capacity of ships that are less concerned in ship operation, and elaborate on a case of overload and power loss of ship power loss when a ship sails through a narrow waterway. This case will reveal the importance of strengthening the management of the ship's power grid when large ships enter narrow waterways to prevent ship power loss.
Overview of breakdown hazards
Recently, the C ship (396 meters long, gross tonnage 176435 the first draft of 7.4 meters, 9.7 meters of tail draft, 4965TEU of cargo, 32 people on board) entered the port and sailed through the western channel of Shenzhen, just completed the turn, the ship's generator failed, the whole ship lost power, and the speed of the power loss was 8.5 knots. At 0006 hours, the emergency generator was started, the emergency distribution board was supplied normally, the servo was restored, and all the equipment related to the generator was restarted. At 0009 hours, the ship's main engine only resumes slow. At 0106 hours, with the assistance of four tugboats, the berth was safely docked.
Causes of power loss on ships
The overload of the ship's power grid is the direct cause of the ship's power loss.
(1) Analysis of the capacity of the ship's power grid and the ship's main power supply
The C wheel is equipped with 4 generators, the manufacturer HYUNDAI HIMSEN, NO.1 and NO.4 power are both 3840KW, NO.2 and NO.3 power are 3300KW, the main power supply capacity is 14280KW, and the automatic power station management system is adopted. When entering the port on the same day, the ship's No. 3 generator was overhauled in accordance with the maintenance plan, and the overhaul time was 15 days, and the No. 1, No. 2 and No. 4 generator sets were running in parallel, with a load capacity of 10,980KW. When the navigation passes through the turning point of the channel, the fuel injection control system of the No. 4 generator fails, and the power generation prime mover runs at excessive speed, triggering the speeding car alarm to stop and automatically disconnect. The No. 1 and No. 2 generators could not meet the power load demand of the ship, the ship's power grid was overloaded, and the whole ship lost power.
According to the power load calculation book (as shown in Figure 1), when the ship enters and leaves the port for maneuvering, the main power load includes continuous power load, intermittent load, desulfurization tower (closed) load, refrigerated container load (full load is 1200 refrigerated containers), and the load under the use of side thrust, a total of 10349KW, and 3 generator sets need to be operated in parallel to provide sufficient load.
Fig.1 Calculation of ship power load
When entering the channel, the refrigerated container load is only 10% of the total load, about 520KW, and the rest of the continuous and intermittent loads are 7832.5KW, with a total load of 8352KW. In the case of the overhaul of the NO.3 generator, the NO.4 generator failure occurred when entering the channel, and the remaining NO.1 and NO.2 generators could only provide 7140KW of main power capacity, which could not meet the load requirements of the ship, the ship power grid was overloaded, and the ship lost power.
(2) The cause of generator failure
NO.4 GENERATOR, MANUFACTURER HYUNDAI HIMSEN, MODEL 7H40, RATED POWER 3840KW. At the time of the incident, the diaphragm of the fuel injection solenoid valve of the NO.4 generator (shown in Figure 2) was damaged.
Fig.2. Fuel system injection solenoid valve diaphragm
According to the schematic diagram of the fuel injection system of this generator (Fig. 3), this component is the 4 faults in the schematic diagram.
Fig.3. Schematic diagram of generator fuel injection system
The main function of the fuel injection system is: when the load increases instantaneously, prevent the amount of fuel injected in the combustion chamber from being more than the amount that can be burned by the supplied air, and prevent the black smoke from the power generation diesel engine. The working principle is as follows: when the load of the ship power grid increases, the fuel supply increases instantaneously, the adjusting rod 1 and 2 rise, and the piston rod of the piston 3 is connected to the circuit, after the solenoid valve 4 is electrified, the solenoid valve opens the compressed air and enters the turbine of the power generation diesel engine for short-term supplementary air supply, and the supply time is 3-8 seconds (according to the change time of the load, the greater the load increase, the longer the air time). During air supply, after the air supply receiver stores a certain amount of air, the piston 3 is pushed upward, the piston rod is separated from the adjusting rod, the circuit is disconnected, and the short-term supplementary air supply of the power generation diesel engine ends. When the short air supply exceeds 10 seconds, the generator will give an alarm of "fuel injection system failure". The diaphragm of the fuel injection solenoid valve of the NO.4 generator is damaged, and the air is continuously supplied to the NO.4 power generation diesel engine, which activates the alarm of "fuel injection system failure", and the generator is protected and parked at the same time, and the NO.4 generator is disconnected from the power grid. The power supply of the ship is supplied by NO.1 and NO.2 generators.
Other cases of power loss of ships in narrow waterways
"DALI" ship Baltimore bridge crash accident (picture 4)
Figure 4 Screenshot of the collision video of the "DALI" wheel (picture from the Internet)
In the early morning of March 26, 2024 local time, the Singaporean flag flying the "DALI" ship crashed into the Francis Scott Key Bridge in Baltimore, Maryland, USA, causing the bridge to collapse and eight people falling into the water, two of whom were rescued. At the time of the incident, the ship lost power.
Prevention of overload and loss of power in the ship's power grid
The SOLAS Convention requires that the capacity of the generator shall be satisfied: "The capacity of the generator set shall be such that it shall be able to supply power to the equipment necessary for the normal operation and safety of any generator set when the power supply to any of the generating sets is lost." At the same time, minimum comfortable living conditions, including facilities such as cooking, heating, food freezing, mechanical ventilation, sanitation and fresh water, should be ensured. "When one or more generators of the ship cannot be used, the power supply capacity of the remaining generator is prone to not meet the requirements of the Convention, such as the use of high-power equipment such as side thruster is not restricted, and the ship's power grid is prone to overload and power loss. By carrying out preventive checks and formulating preventive measures for the ship's main power supply capacity, the ship's power grid is overloaded and lost power.
In April 2024, when the Shenzhen Maritime Safety Administration PSCO inspected the "Y" ship, it was found that the ship was equipped with 4 generators, of which the NO.1 generator failed (Figure 5) and could not be used.
Figure 5 NO.1 Generator failure and cannot be used (body is broken)
According to the ship's power load book (Fig. 6), the ship is charged with the power load. The ship single generator power of 2100KW, the total power capacity of 8400KW, loading 80 refrigerated containers, according to the power load calculation, the ship in and out of the port of motor navigation, the use of side thrust when the total power of 4231KW, the need for 3 generators to run in parallel, in order to meet the load demand of the whole ship. However, the ship only has three generators in use, and there is no backup generator, which does not meet the requirements of the Convention.
Fig.6. Y round power load calculation
After communication and confirmation with the ship, the defect was issued: when the NO.1 generator failed, the ship did not make special arrangements for the entry and exit operations. The ship proposes the following measures to prevent power loss from ships:
In May 2024, the M ship took the initiative to report the failure of a single generator, and after accounting, it also did not meet the requirements of the ship's main power supply capacity, and the entry and exit measures, especially the use of the side thruster device, were implemented with reference to the above inspection case.
Safety Regulatory Recommendations
(1) Pay attention to the problem of overload of ship power grid and power loss of ship
At present, the degree of automation management of ship power stations is high, and the problem of ship power capacity has been paid less attention. It should be recognized that when a single or multiple generators of the ship fails, measures such as automatic disconnection of the ship's power station cannot effectively avoid the overload of the ship's power grid and the loss of power of the whole ship.
(2) Reasonably formulate a maintenance plan for ship generators
Reasonable planning of generator maintenance plan, it is recommended that the generator overhaul should be arranged during sea voyage, and try to avoid overhauling the ship's generator set during the port to ensure that the power supply capacity of the generator set is sufficient.
(3) Formulate measures to prevent overload on the ship's power grid
It is recommended that when the ship enters and leaves the port, especially when entering the narrow waterway, if the generator cannot be used, it is necessary to calculate according to the ship's electrical load calculation to determine whether the thruster device can be used. Before the ship enters the port, the pilot needs to inform the pilot of the information in advance, and if necessary, additional tugboats will be sent to assist in entering and leaving the port.
(4) Strengthen emergency management in the event of a power failure of a ship
It is recommended that ships strengthen the management of ship emergency power supply and ship power failure emergency drills. Ensure that after the ship loses power, the emergency generator is activated and supplies power to emergency equipment such as the steering gear, controlling the direction of the ship while providing sufficient buffer time for power recovery. Strengthen emergency drills to ensure that the ship's main power supply is supplied as soon as possible and restore the ship's propulsion power. Strengthen information communication and coordination with pilotage and docks, optimize measures for the use of tugboats, and use tugboats to control ships when necessary.
Source: Shenzhen Maritime
Picks:
Today's Notices and Warnings
The 2024 National Low Carbon Day initiative for the transportation sector
Just find a ladder that can be used as a ship-to-shore passage?
Haiqing role model丨2023-2024 "Top Ten Outstanding Youths" of the directly affiliated maritime system, Liu Chao
Media Spotlight丨Maritime News Quick Facts, Issue 94