Friday, July 27, 2012

Learn about the starting process and checks to be made while starting a ship's generator engine

Starting of generator engine

Starting of an engine from "stop" state is something which needs to be done with care, especially if the interval of starting is sufficiently long. The following is a checklist of all the checks which ideally need to be carried out before starting the generator. In actual practice sometimes the engineers might take some of these for granted and skip, but it is advisable not to indulge in such a practice. Infact these checks are generic for any four stroke engine starting process
  1. Check the turbocharger sump oil level, governor, alternator, forward and aft lube oil levels, and diesel oil level in service tank
  2. Open the indicator cock
  3. Prime the lube oil to all parts by hand pump or by motor driven priming pump
  4. Ensure that all jacket cooler valves, lube oil cooler valves, air cooler valves should be in open position
  5. With use of the Turning bar turn the fly wheel and check for any resistance on the bottom end bearing and check any water / fuel coming out through indicator cocks
  6. While turning engine, check all visible lube oil points are lubricated
  7. Remove the turning bar from fly wheel and put in the place
  8. Drain the auxiliary air bottle
  9. Blow through engine (ie: by turning engine with air). In order to ensure that no water is inside combustion chamber if it is present it may cause water hammering
  10. Close the indicator cocks and pull lever from stop to start
  11. When the needle in RPM indicator deflects to some value of (0-25 rpm) put the lever in run condition
  12. The engine will run on fuel oil once the generator picks up the rated speed
  13. Put generator on load by closing air circuit breaker
  14. For checking the alternator fore and aft bearing lube oil level by opening oil plug in the alternator and the ring bearing while rotating splash lube oil from the sump can be seen
  15. In order to synchronize the incoming generator with running generator syncroscope method/dark lamp method is used

  • Checks to be made while running

    Once the generator has actually started to run, there are several checks which must be performed before it is left on its own to continue running. These checks pertain to verifying various parameters related to lube oil levels, temperatures and so forth. Given below is a brief checklist related to the same.

    Lube oil checks

    1. Sump lube oil level
    2. Governor lube oil level
    3. Rocker arm lube oil level
    4. Alternator forward and aft bearing lube oil level
    5. Lube oil in turbine & blower side of turbo charger

    Temperature checks

    1. Exhaust gas temperature
    2. Turbocharger (inlet-outlet) temperature
    3. Booster air inlet temperature

    Cooler temperatures

    1. Cooling sea water (inlet - out let) temperature in cooler
    2. Jacket cooling water (inlet - outlet) temperature
    3. Air cooler (inlet -outlet) temperature

  • Safety devices

    Once the above mentioned parameters have been checked and found within normal range, it is safe to continue running the generator. Yet a fault can develop even at a later stage, so for this very purpose various trips and alarms are situated on the generators. An alarm gives the signal of an impeding danger and requires quick action while a trip actually trips the generator immediately because of the nature of the fault.
    The various trips and alarms are mentioned as follows
    1. Alternator bearing low oil level alarm & trip
    2. Alternator bearing high temperature lube oil alarm &trip
    3. Low sump oil level alarm and trip
    4. Lube low oil pressure alarm and trip
    5. Reverse current trip
    6. Over speed trip
    7. Over load trip
    8. High and low frequency trip
    9. Jacket cooling water low pressure alarm

     By Kenneth Sleight

Marine Diesel Engines - Assembly, Components Of, and Watchkeeping For

The invention of the diesel engine in 1893 has been attributed to Rudolf Diesel, a German mechanical engineer and inventor. This was an innovative internal combustion engine that was the fore-runner of today’s marine diesel engines used in ships worldwide.
  • I was first introduced to a marine diesel engine in the form of a Caterpillar (CAT) inboard engine in my Uncle Jimmy’s boat that he used for lobster/crab potting and local fishing trips. I accompanied him on many trips from when I was about ten years old and got to know the CAT engine's idiosyncrasies quite well.
    I them worked on much larger engines while serving my apprenticeship at Harland and Wolff of Belfast; they had a license to build Burmeister and Wain two-stroke diesel engines.
    Leaving the shipyard in 1966, I joined my first ship in Portland Maine, the MV Orama, a 30,000T Oil Tanker, as Junior Engineer Officer. She had a B&W main engine so I felt quite at home, except for rolling about across the North Atlantic and gas-freeing of the tanks. Like all first trippers, I suffered from sea sickness for a few days, from a combination of her gyrations and the constant smell of crude oil.
    The following sections supply links to marine articles here at Bright Hub that deal with diesel engines. After a brief introduction to the theory and terminology involved, we will move on to examining the components and systems of these engines, and then watch keeping duties, along with the operation and maintenance of a typical two-stroke marine diesel engine.
  • Engine Installation, Two Stroke & Four Stroke Engines

    Before we examine the two-stroke and four-stroke engines, it is worthwhile to have a look at one method of assembling the engines in the engine room.

    Engine Assembly aboard Ship

    There are a number of marine diesel engine manufacturers who assemble and test the engines before stripping them down to the main components and lowering them into the ship’s engine room. We used to re-assemble the components in the engine room in the following order. (I imagine the same procedures are used today, except for the main foundation components being of a more modern design.)

    The bed plate consists of two longitudinal girders, braced by cast steel traverse cross sections. At selected cross sections, the main bearing pockets are line-bored and two vertical holes drilled through them and the section. The main tie-rods are fitted through these into the bed plate.
    The bed plate is lowered into position onto the supports that form part of the ship’s hull, then shimmed level and caulked before being fitted with hold-down bolts that run right around the bottom support frame. The crankshaft main bearing bottom halves are then fitted to the bed plate bearing pockets and the crankshaft lowered into them. The top halves of the main bearing are then fitted and checked for clearance and alignment.

    The “A” frames and entablatures follow, being bolted together using fitted bolts, before other components are quickly fitted until the engine is completely rebuilt.
    There are two types of marine diesel engines: two-stroke and four-stroke.

    Two Stroke Cycle

    Starting with the piston at bottom dead center (BDC), the combustion air is supplied to the liner air inlet ports and the piston starts to rise up the liner. Depending on the scavenging system, the piston either ejects the previous cycle exhaust gases out exhaust ports in the liner or out through an exhaust valve in the cylinder head.
    The combustion air continues to be compressed to almost top dead center (TDC) when the fuel is injected and combusted by compression ignition, forcing the piston back down the liner.

    Four Stroke Cycle

    1. Exhaust Stroke - Starting again with the piston at BDC, it begins to rise up the liner, with the exhaust valve in the cylinder head opening and expelling the exhaust gasses during the upward stroke.
    2. Inlet Stroke - The inlet valve now opens and combustion air is drawn in as the piston continues downwards.
    3. Compression Stroke - After reaching BDC the piston starts to rise again and the inlet valve shuts.
    4. Ignition/Power Stroke - As the piston continues to rise with both valves shut, and just before TDC, fuel is injected and is combusted through compression ignition, forcing the piston downwards on its power stroke.

    Components of a Marine Diesel Engine

    The marine diesel engine has changed a bit since I was an engineer at sea in the 1960’s. In those days the popular engines were Sulzer, B&W, British Polar, and Doxfords. Most shipping companies had a preference for a particular make of engine and had these installed in all their ships. This gave continuity for their Engineer Officers, who were both watch keepers and maintenance engineers combined.
    Nowadays, modern diesel engines being manufactured by Wartsila Sulzer and MAN/B&W have recorded a thermal efficiency of over 50 percent. The Wartsila Sulzer RT96 flex-C is one of the world’s largest marine diesel engines: the14-cylinder model produces 108,000 horse power.

    Watch Keeping Duties & Engine Room Layout

    Most engine rooms follow a basic design that has stood the test of time. This includes the location of the main and auxiliary engines, pumps, coolers, and prop-drive shafting, allowing the watch keeping engineers to acquaint themselves quickly when joining a new ship.

    Fire and Explosion in the Main Engine & Engine Room

    Fire and explosion aboard ship is still the most feared condition by today’s seafarers. The ship’s engine room is particularly susceptible to fire due to the hot surfaces and pipes carrying the fuel and lube-oil.
    In today’s ships the crew is trained in firefighting both while at sea and by courses when on leave. This has led to the formation of fire teams who are competent at extinguishing all types of shipboard fires and rescuing the survivors of explosions.

    Main & Auxiliary Engine Breakdown at Sea

    When the main engine or generators break down at sea, it is the responsibility of the ship’s engineer officers to repair them. Sometimes there are no spare parts, so these have to be made by the engineers using the quite extensive engine room workshop. Major repairs can take a long time. I remember one occasion where we broke down in the Red Sea and were working for twenty hours to effect repairs. Then I stood my watch, totaling 24 hours on my feet. Fortunately this is the exception rather than the rule, and nowadays engines are more reliable and a better selection of spares is carried by the major shipping companies.
    By Willie Scott

Firefighting Equipment in Ship's Engine Room

Ships engine rooms are susceptible to fires and explosions, as well as the engines themselves. However, there is firefighting equipment in a ships engine room to combat these hazards, such as hand held fire extinguishers and seawater hydrants/ hoses; CO2 or mist injection being used in engine spaces
  • As long as men have gone to sea in ships there has been a fear of fire aboard; more so on the old wooden hulled sailing ships than today’s modern ships. However major fires still occur on modern ships accounting for a large number of lives lost, especially on cruise ships and ferries.
    Ship's engine rooms are the usual sources of shipboard fires; either from a fire in the engine room, or an engine internal fire or explosion causing a subsequent fire. The main portable means of fire fighting equipment are the different types of hand held extinguishers. These are located throughout the engine room at different levels, along with hoses and hydrants supplied by the seawater pumps. Fires in the engine internal spaces can be attacked and extinguished using inert gas such as CO2, foam, or water mist sprays.

    The following sections examine the firefighting equipment used in today's modern engine rooms. The first sections deals with the common causes of fires in the engine room.
  • Common Causes of Shipboard Fires

    The causes of engine room fires can usually be traced back to a lack of maintenance or bad watchkeeping practices. They are usually caused by fuel spills, overheating components or careless use of electric welding or gas brazing gear.

    Oil Spills

    It is imperative to combat the risk of engine room fires by maintaining the fuel and lube oil systems, more so on diesel engine ships than steam turbines; although I have had a few hairy oil-fired boiler room moments where the donkey man has used sawdust to mop up burner oil spills, instead of sand from the old red-painted sand bucket. There must be constant vigilance against leaking oil of any type, pipes and unions being especially vulnerable. Any leaking or damaged fuel pipe should be reported to the senior engineer immediately. There is not much you can do about oil spraying onto a hot exhaust, except shut off the supply and fight the fire, however but engine room housekeeping is another matter, this is something that we can all participate in.

    • Engine room Housekeeping

    The engine room should be kept clean and tidy, free from inflammable materials such as wooden crates, cardboard boxes, oily rags and paper. Any oil spills cleaned up immediately and the source investigated, repaired and logged. An engine room No Smoking Policy should be enforced, which should stop people stubbing out their cigarette ends in a sand bucket!


    The repair of components by welding and brazing is common practice in ships engine rooms. However, both are potential fire hazards, due to the electric-arcing of the welding rod and the open flame on the brazing torch tip. There is also the additional hazard when welding where the ensuing molten metal can fall down through several floors into the bilges.
    It is therefore imperative that the component for repair should be brought to the engine room workshop. If this is not possible, then a fire retardant blanket should be laid under the component to be welded or brazed. A fire watcher should be employed to keep an eye on the proceedings; with a set of extinguishers to hand.
  • Engine Room Fire Fighting Equipment

    • Engine room Sprinkler System

    This is of the more modern type of water nozzles that actually supply a very fine mist, rather than a flow of water. These systems cover of different areas of the engine room, but not the switchboard or the electrical generating component of the power generators. The sprinkler system can be operated automatically by sensors or manually by the engineer. This starts the water booster pump and opens up the compressed air supply which can be from dedicated high pressure air bottles or the engine air-start receivers.
    As we all know water is not normally used on oil fires but, because fine mist is injected into the area it not only starves the fire of oxygen, but also dissipates the smoke.

    • Engine room Fire Extinguishers

    There are four main types of fire extinguishers all colored red nowadays, with a different colored band around the top of the body, denoting the type of medium it contains. They are operated by removing the protective pin, before pulling the trigger smartly.
    Fire extinguishers are usually stored in a container together as shown below in a group of four; one of each type. The containers are positioned at different levels in the engine room at high fire risk locations.

    The four types are:

    1. Dry Powder Fire Extinguisher– it has a black band around the body and is used for extinguishing electrical and liquid fires.
    2. Foam Fire Extinguisher – this has a yellow band around the body and is used for extinguishing oil fires.
    3. Water Fire Extinguisher – this has a red band contained between two thin white bands around the body. It is used to extinguish paper, wood and cloth.
    4. CO2 Fire Extinguisher – this has a black band around the body and is used to extinguish electrical and liquid fires.

    Remember, only the Dry Powder and CO2 extinguishers should be used on electrical fires.

    • Fire Hydrants and Hoses

    These are positioned throughout the engine room; a fire axe is sometimes alongside the fire hoses. The hydrant valves should be opened; hoses run out and discharged to the bilges at regular intervals to ensure operation.

    • Aqueous Film Forming Foam

    Known as AFFF and (pronounced A triple F) was developed in the sixties and is a great innovation to firefighting not only in ships engine rooms, but on oil and gas platforms worldwide. AFFF is supplied in its own containers and added to an AFFF storage tank and is operated by pressurized seawater. The seawater mixes with the specialist liquid and exits the 11/2" rubber hose through a brass nozzle as a pressurized film of thick, viscous foam. This is directed to the base of the fire, quickly smothering the flames, dissipating the heat, smoke and fumes.
  • Prevention and Control

    The two main causes of engine room fires are scavenge fires and crankcase explosions occurring on the main diesel engines. Both can be detected and prevented if discovered early enough. The scavenge fire is detected by high exhaust temperature, paint peeling of the scavenge door or the Mate phoning down to inform us of black smoke and sparks emitting from the flue.

    The much more serious crankcase explosion is caused by a build up of lube-oil mist inside the crankcase. This triggers the oil-mist detector and the alarm will sound, giving the engineer enough time to slow down the engine allowing it cool. In the event of an explosion, the explosion relief devices on the crankcase doors will lift. This device prevents injury from a flying crankcase door; the fine wire mesh in the relief valve taking the heat out of the flames, reducing the risk of fire. The explosion door re-closes immediately, preventing any entry of fresh oxygen entering the crankcase promoting further explosion and fire.
    Both the above hazards have similar fire control methods; injection of CO2 or water mist into the scavenge space and injection of CO2 into the crankcase. The inspection doors must remain shut until the relevant components and spaces have cooled down.
  • Firefighting Team and Equipment

    This is a dedicated team with a team leader in charge, who attend regular courses when on leave. The team is usually made up from members of the crew, engine room and deck officers. They practice fire drill, evacuation and rescue operations regularly on the deck, accommodation and engine room areas.

    Breathing Apparatus Set

    The BA set consists of an oxygen tank which is strapped to the firefighters back, supplying a full face mask with oxygen.

    Personal Protection

    This consists of loose fitting fire retardant clothes, fire retardant boots and a yellow fireman's safety helmet; team leader having a red band around his helmet.

    By Willie Scott