Marine Power Plant (DMARPOWER) PDF

Marine Power Plant (DMARPOWER) Prepared by : Chief Eng. Hamid Reza Soltani Semester-1 2023-2024  LESSON 1...

Marine Power Plant (DMARPOWER) Prepared by : Chief Eng. Hamid Reza Soltani Semester-1 2023-2024  LESSON 13 Marine power plant (deck officer) - diesel engine operating systems(part 6 )  Marine Diesel Engine Objectives By the end of the lesson, students will be able to: -Discuss the reasons that the diesel engine need to turn to start - Discuss the reasons which can lead to the air bottle getting empty CLASS GROUP TASK ACTIVITY Task12: With reference to different methods of the diesel engine starting system, answer the following questions: Question 1: Why dose diesel engine need to turn in order to start by turning the flywheel but in the main diesel engine the starting air is supplied into the cylinder directly? Question2: Why are diesel engines difficult to start when they are cold? Question 3: why are the diesel engine need to turn to start? (IMCO,2016) CLASS GROUP TASK ACTIVITY Task12: Question 1: Why dose diesel engine need to turn in order to start by turning the flywheel but in the main diesel engine the starting air is supplied into the cylinder directly? It is depend to the size of the diesel engine. For small and medium size of the diesel engine, the best and simple method to start the engine is to turn the engine by turning the fly wheel. This system is simplest and easy to use and no need to use the air distributer and staring air valve for each cylinder. For big size of the diesel engine, it is difficult to turn the engine by starting air motor. In this condition the starting air supplies directly to the cylinder through the air start valve which is installed in each cylinder. Depend on the firing order, the distributer sends the air single the correct cylinder starting valve which is ready in the start position to urn the engine. (IMCO,2016) CLASS GROUP TASK ACTIVITY Task12: Question2: Why are diesel engines difficult to start when they are cold? In fact, the vaporization of the fuel is more difficult if the temperature is lower and so it’s more difficult to start combustion. Since diesel engines rely on compression to run, heat is directly involved in the combustion of the diesel in the combustion chamber. The way this occurs is that when the piston comes up it compresses the air which is in the cylinder. This creates heat. When the engine is cold, a lot of this heat gets transferred out of the combustion chamber and into the cylinder head, pistons, and cylinder walls. When the engine comes up to compress the air and reach the air temperature to the desire temperature which is necessary to ignite the fuel and the heat from the compressed air transfers to the engine cold parts such as cylinder liner. (IMCO,2016) CLASS GROUP TASK ACTIVITY Task12: Question 3: why are the diesel engine need to turn to start? A diesel engine has a very high compression ratio, an essential design feature, as it is the heat of compression that ignites the fuel.the combustion will not take place without the high air temperature and high compression ratio. The high compression ratio means high amount of the air or the air with high density. In low speed turning of the engine some amount of the air skips between the piston rings and cylinder liner. The sealing pressure is increased between the piston rings and cylinder liner by turning the engine and start the diesel engine. (IMCO,2016) Task13: The air for starting the engine is supplied from the air bottle. There is 2 air bottles onboard the vessel. The air bottle is filled with the air compressor. “To start the engine, a minimum pressure of air is required. If the bottle pressure drops below this minimum level, the engine cannot start and we have to wait until the bottle is filled”. -what are the reasons which can lead to the air bottle getting empty? Task13: -what are the reasons which can lead to the air bottle getting empty? 1) too many starting kicks on the engine - All deck officer must know the number of consecutive kick they have at their disposal. -In fact this information is also a part of pilot card and master pilot exchange. -Most of the times, we can get this information from the wheel house poster (Jassal, 2016) Task13: -what are the reasons which can lead to the air bottle getting empty? 2- problem with air compressor -Usually there is 2 compressors -One of these compressor has the source from the emergency supply and is the emergency compressor. (Jassal, 2016) Task13: -what are the reasons which can lead to the air bottle getting empty? 3- leakage in the air line -the air line leak on deck as well as in the engine room can affect the operation of the vessel during maneuvering. -with faulty air compressor, the situation can be more danger (Jassal, 2016) Task13: -what are the reasons which can lead to the air bottle getting empty? 3- leakage in the air line -during maneuvering deck officer must keep an eye on the air bottle pressure. -If they see the bottle pressure dropping too fast, the engine room must be informed. (Jassal, 2016) Task13: -give some important points about the air compressor related to the safety of the vessel during sailing and maneuvering 1-if one of the compressor is not working, then the single compressor is not able to fill the air bottle quick enough. This is a dangerous situation 2- if the vessel has to sail out or berth in this condition, a risk assessment must be conducted. It is important that we have the approval from the required authorities to sail in these conditions (Jassal, 2016) Task13: -give some important points about the air compressor related to the safety of the vessel during sailing and maneuvering 3- if we have to sail with one working compressor, it is the emergency compressor that should be working 4- the reason of the above point is, in case of black out, we still should have a running compressor (Jassal, 2016)  REFERENCES - Wharton, A.J. (1995). Diesel Engines, Third Edition. Oxford: Butterworth Heinemann. - Jassal, R. (2016). 5 Basic Marine engineering Principals Every Deck Officer must Understand. Marine engineering Principles for Deck Officer – MySeaTime -ship-technology (nd). Schaller Automation. Oil Mist Detection Systems for Ship Engines and Machinery. Schaller Automation - Ship Technology (ship-technology.com) -al-tech.in (nd). Oil Mist Detector. SHIP ENGINE OIL MIST DETECTOR, SCHALLER VISARTON OIL MIST DETECTOR, GRAVINER OIL MIST DETECTOR, DAIHATSU OIL MIST DETECTOR | AL-TECH MARINE, AL-TECH CENTRIFUGES