On ship, it is important to check the performance of the engine from time to time so as to ascertain working condition and fault finding. In earlier days, the performance of diesel engine was taken manually, but with the advancement of technology, automatic monitoring systems are being used.
Types of Diesel Engine Monitoring Systems
With the help of monitoring systems, the diesel performance of the engine can be taken easily and within no time. The new technology provides two types of monitoring systems.
In the first system, the diesel performance is monitored continuously and is thus known as online monitoring. Whereas in the second system, the engineer has to manually put the instrument on the cylinder head, connecting the wire to rpm sensor and taking the readings manually and later transferring to the computer. Generally on ships, the main engine has an online diesel performance system whereas for diesel generators have a manual system.
The type of system that is to be installed depends on the company and the type of ship and engine. The online system is quite costly than the manual one. In online system the diesel performance can be seen remotely in the control room as well as in the cabin of the chief engineer. The system also provides several graphs which precisely analyzes the condition of the engine. The graphs provide as similar to draw and indicator cards plotted by the manual system. They help in achieving reliable and efficient operation of the marine engine.
From the graphs obtained, various characteristics such as engine timing, compression pressure, cylinder output etc. can be analyzed. They also tell us whether the engine is balanced or if some units are overloaded. The graphs also indicates if the timing has to be adjusted, information on piston rings leaking etc., thus providing necessary maintenance and adjustments to avoid engine failure or damage to the engine.
Generally, the diesel performance of main engine and auxiliary engines are taken once every month and the report is then analyzed. A copy of the report is also sent to the company’s technical department along with the chief engineer’s comments on the report. The technical department checks and replies back if any points are missed by the ship’s staff.
For emergency purpose, the old method for checking diesel performance is kept as the standby method. This is done keeping in mind, monitoring system failure and lack of spare parts for repair.
The diesel performance reports are kept as records so that it can be compared with the recent reports and the trend can be checked to analyze if the diesel performance has deteriorated or improved. If the report shows a downward trend, then maintenance is done and necessary parts are replaced or adjusted.
Advantages of Diesel Performance System
1) Efficient and reliable operation of the engine.
2) Helps in saving fuel and optimizing SFOC( Specific Fuel Oil Consumption.
3) Helps in predicting the necessary repairs and preventing engine failure.
4) Helps in reducing spare parts cost and increasing time between overhauls.
Causes and Effects of SOx Emission
The sulphur oxides emission is due to the presence of sulphur compound in the marine fuels used in marine engines on board vessel. Better the grade, lower will be the sulphur content as it is removed by refining of the fuel.
It has also been recognised that the emission of SOx contributes in formation of secondary inorganic aerosol gases, fine particles which are harmful to humans.
Maritime industry consumes mostly low grade of fuel oil i.e. heavy oil and diesel oil with high sulphur content as compared to any other transportation medium. But due to MARPOL Annex VI stringent norms, marine engines are now using better grade of marine fuel like marine gas oil.
Limits for SOx Emission from a Merchant Vessel
When the ship is out of emission controlled area
- The sulphur content of any oil used onboard ship must not exceed 3.5% m/m.
When the ship is within emission controlled area
- The sulphur content of any fuel oil used on board ships must not exceed 0.1% m/m.
An exhaust gas cleaning system or other technological methods to be used onboard to reduce total sulphur emission from ships including auxiliary and main propulsion engine to less then or equal to 6.0g SOx/kwh.