How does a start air system work?
How does a start air system work?
When starting the engine, compressed air is admitted to whichever cylinder has a piston just over top dead center, forcing it downward. As the engine starts to turn, the air-start valve on the next cylinder in line opens to continue the rotation.
How is the starting air system admitted to engine cylinder?
Compressed air is supplied by air compressors to the air receivers. The compressed air is then supplied by a large bore pipe to a remote operating non-return or automatic valve and then to the cylinder air start valve. Opening of the cylinder air start valve will admit compressed air into the cylinder.
How does a marine engine start?
To start the main engine, first turning gear has to be disengaged. Air passed from turning gear interlock pushes the spring, opens the valve and closes the vent. Now the air is available in the cylinder head starting air valve manifold and in the distributor.
Why compressed air is used for starting the marine diesel engines?
Air Starting System Working Principle A Compressed air of 20 to 30 bar is required to start an engine by providing enough force to turn the engine at speed suitable to reach the combustion temperature and pressure.
What is the starting air pressure of main engine?
between 25 and 42 bars
The starting air pressure is generally of the same range for both the main propulsion engines and the auxiliary engines i.e. between 25 and 42 bars. If the air pressure goes higher than this, then the components of the engine should be sturdy and robust to cater for the same.
What is the most common type of air compressor in the marine industry?
double acting reciprocating air compressors
The most common type of compressor used in the marine industry are double acting reciprocating air compressors. There are multiple compressors provided on a ship to serve different purposes. They can run main and auxiliary engines.
Which must be moved to start the engine?
To make an engine start it must be turned at some speed, so that it sucks fuel and air into the cylinders , and compresses it. The powerful electric starter motor does the turning. Its shaft carries a small pinion ( gear wheel) which engages with a large gear ring around the rim of the engine flywheel .
What are the preparations before starting the auxiliary engine?
Lubrication of Main Engine: Start pre-lubrication of the engine well before starting the marine engine. For the main engine it should be started before 1 hour and for auxiliary 4-stroke engines at least 15 minutes in advance.
What is starting control pressure?
The starting air pressure is generally of the same range for both the main propulsion engines and the auxiliary engines i.e. between 25 and 42 bars. If the air pressure goes higher than this, then the components of the engine should be sturdy and robust to cater for the same.
What are the 4 types of compressor?
The four most common types of air compressors you will see are:
- Rotary Screw Compressor.
- Reciprocating Air Compressor.
- Axial Compressor.
- Centrifugal Compressor.
Which type of compressor is most efficient?
Discharge pressures can range from low pressure to very high pressure (>18000 psi or 180 MPa). In certain applications, such as air compression, multi-stage double-acting compressors are said to be the most efficient compressors available, and are typically larger, and more costly than comparable rotary units.
How is starting air system for marine diesel engine?
Starting air system for marine diesel engine A supply of compressed air is stored in air reservoirs or ‘bottles’ ready for immediate use. Up to 12 starts are possible with the stored quantity of compressed air. Machinery Spaces.com
How is the main engine of a marine engine started?
Main Engine Starting Air System Marine diesel engines are started by admitting compressed air to the cylinders at the appropriate point in the cycle. The air stored in receivers which are charged by compressors. A pressure of about 28 bar is usual.
How does the air motor start an engine?
The compressed air supplied from the air reservoir is lowered to a proper pressure through reducing valve around staring air motor, which is used for starting and stopping the engine. Engine Starting System. Engine Stop System. Engine Speed control System.
How is an auxiliary engine started on a ship?
In air motor starting system, the engine is started by a starting air motor which is operated by compressed air. Figure below shows the compressed air system for starting, stopping and fuel limiting for auxiliary engines on ships. Refer to the figure above. Compressed air reaches the auxiliary engine at 30 bar pressure.
