Best Tutorial on Marine Air Compressor
In this post on Best Tutorial on Marine Air Compressor,We will discuss the following topics
- What is a compressor,
- Uses of main Air Compressor on Board a ship,
- Compressor working principles,
- The general problem in compressors,
- How does a compressor work?
What is Air Compressor?
An Air compressor is a machine to increase the pressure. by compressing from low pressure to higher pressure by utilizing. some external source of energy.Electric motor or Diesel Engine drives the compressor
Classification of compressed air
- Main Air
- Instrument Air
Main Air: – (11 to 30 bar)
- Use of main air is for starting the main and auxiliary engines onboard a ship
- For supercharging purpose the engines
- For the operation of Lambda controller to boos the air at the change of loads in the engine.
Instrument Air; – (7 bars)
Use of Instrument air
1. Control system for several controls and automation.
2. Service air and control air application
3. Paint and spray instruments
4.Pneumatic hand tools
5. For machine cleaning
6. For Hydrophore ( A system to maintain the water pressure)
Important terminology used for compressor
Compression Ratio; – Ratio of volume pre- compression to the volume of air. post- compression is compression ratio.
Compressor Capacity; – Absolute volume of air delivered by a compressor in M3 / minute. is compressor capacity.
Free Air Delivery; – Quantity of air in M3 / minute produced by. existing temperature and pressure. at the suction of compressor is free air delivered.
Swept Volume; – The swept volume is the volume of air displaced by the diameter of the piston in one full stroke. from BDC to TDC
Classes of Compressors
Positive displacement compressor
Compresses the volume of air and forces it to a smaller volume
- Rotary compressor
Centrifugal type of compressor
This type of compressor accelerates the air and. converts the energy into kinetic energy
In reciprocating type, compressor
- compressor sucks the air in the cylinder
- The piston compresses the air and expels to the discharge line.
- The valves fitted in the cylinder regulate the flow of air from the cylinder.
Types of reciprocating compressor
- Double acting
Single-acting compressor is with one discharge stroke in each revolution of the crankshaft.
Double acting compressor is with two discharge strokes in every revolution of crankshaft.
1) Screw type
2) Reciprocating Type
3) Centrifugal Type
4) Rotary Type
5) Diaphragm Type
Use of Reciprocating Compressors.
1) Marine Engines
2) Industrial Diesel Engines
Air Compressor working principle
- A spring-loaded Non- return delivery valve operates.
- The compressed air flows through at constant pressure.
- The cycle completes the stroke.
- The differential pressure across the valve shuts the discharge valve.
- This process traps a small quantity of high-pressure air in the. clearance area between the piston and the cylinder head.
- On the induction stroke, the air in the clearance space expands.
How does a Marine compressor work?
A single crank single-acting Marine Air Compressor is the connection of- Low-pressure and high-pressure piston is tandem to a single crankpin low-pressure stage.
The external power of an Electric motor or a Diesel Engine rotates the crankshaft. Crankshaft gives drive to the piston.
In single-acting crank compressors.
The low-pressure and high-pressure pistons connects to two separate cranks. As the low-pressure piston moves down, the air sucks in through the air filter. And delivers the compressed air to the second stage through the intercooler.
During this cycle piston compresses the air in the second stage. Delievers high-pressure air to the aftercooler.
The compression process takes place during the upward and downward strokes.
As per the Arrangement, The low-pressure first-stage piston is at the top, and the high-pressure piston is at the bottom. Thus, as the piston moves up in the first stage, it compresses the air. Compressed air enters in the second stage.
The compressed air is once again pressurized in the second stage in the down stroke of the piston.
In the meantime the low-pressure side sucks. The fresh charge from the atmosphere through the filter. This process completes the cycle.
In the three-stage compressor type, the First stage sucks the air. Compresses the air and after the compression. Sends the air to intercooler for the cooling. From the IntercoolerIntercooler, the air eneters the second stage.
After compressing the air, compressed air gets in to 3rd stage
In the upward stroke of the piston, the piston compresses the air in the first and third stages. The air from the first stage enters into the second stage.
Advantage of Multistage compressors
- Power reduction in driving the compressor
- Enhanced mechanical balancing of the complete unit with uniform torque.
- Improved volumetric Efficiency
- Minimized losses due to leakages.
- Low working temperatures enable easy lubrication.
- Reduction in-cylinder weights.
- Due to low working temperature, could use low-cost material.
- Volumetric Efficiency. Volumetric efficiency is the ratio of air discharged to the volume a displaced by piston.
- Isothermal Efficiency;- Is the ratio of isothermal power to the indicated power.
- Mechanical Efficiency- indicated power to the brake power ratio is the definition of Mechanical efficiency
Components of Marine Air Compressor
We will discuss about the major working parts of a reciprocating air compressors.
Safety devices on Air Compressor
Relief valve on HP and LP stage.
Intercooler bursting disc( water side)
After cooler fusing plug
Auto Moisture drain valve
Cooling water supply failure alarm
Low lubricating pressure alarm
Crankcase lube oil pump relief valve
Discharge air high temperature cut out alarm.
Starting procedure of a Marine Air Compressor
- Always keep the Marine Air Compressor unloading system in on position.
- Turn the supply of cooling water on and check the flow and inlet pressure of cooling water.
- Rotate the wheel drive belt by few turns for the freeness. This action is mandatory for the compressor starting after a prolonged period.
- Check the oil level and operate the force-feed lubricator for around 8 to 10 turns.
- Ensure the availability of lube oil to cylinders.
- Check the oil level in the sump and top up if needed.
- Position of the safety shut down switches in normal working condition.
- Drain the condensate from the intercooler and aftercooler.
- Ensure the V belt is tight as per norms.
- Open the stop valve for the air to flow to the air bottle/receiver.
- Press on the button from the control panel to start the compressor.
- Watch the oil pressure with the pressure gauge. stop the compressor immediately If the indicator is not showing the proper pressure.
- Check the lubricating oil flow from the lubrication pump.
- Put the compressor load after 5 minutes of satisfactory operation.
- Check the water flow to the cylinder and coolers.
- The inter-stage pressure should be within range.
- Check and rectify leakages in the system.
- The voltage at each terminal must be as per the specified levels.
- Check the discharge air temperature. The greatest permitted air outlet temperature is 75Deg C.
- Check and tighten the fasteners at regular intervals of operation.
- Listen to the abnormal noises and take immediate action. if any obnoxious noise is present.
Stopping procedure of a Marine Air Compressor
- Unload the compressor with the help of the installed control/ device
- Run the compressor at idle for 5minutes.
- Stop the compressor
- Close the cooling water supply
- Drain the condensate from the points.
- Isolate the power supply to the starter.
How to make a Marine Air Compressor more efficient?
- Supply the cool air to comressor for better efficiency.
- Clean the air filters at correct interval.
- Maitain the Compressor valves.
- The manometer instrument across the filter should be in good condition.
- Reduce the compressor low load operations.
- clean the inter coolers as per schedule or is the air temperature increases..
- Conduct the free air delivery test and compare with the compressor design data.
- Keep Option of Multistage compressor as far as possible.
- Regulate the delivery pressure.
- Maitain the closer range between load and unload.
The key points of the Marine Air Compressor efficiency
- Regulate the drain frequency.
- Check and take the action on logbook abnormal records.
- Carry out periodic leakage test.
- Install the solenoid valve to interlock and cutoff the machine if not in use.
- Maintain all the pneumatic tools with proper lubrication.
- Discourage the improper use of compressed air for cleaning the body and floor.
- Maintain the correct operating pressure of instruments to prevent waste of air.
- Replace the tools with tools operating on electricity.
- Try to use welded connections.
- Always use ball or gate valves.
General Problem of Marine Air Compressor on Ship
Pressure Test of Air Compressor
Carry out the hydraulic test on Cylinders, cylinder cover, Inter & After coolers
- Air Side: 1.5 x max. Working Pressure.
- Water Side: 4 bar or 1.5 x max. WP (whichever is greater)
Each vessel will have two similar air receivers and a emergency bottle.
The total capacity of air receivers must be enough to meet the following need.
1) For 12 starts for the reversible engine
2) For 6 starts for the non-reversible engine, without refilling the receivers.
Mountings on Air Receiver
- Fusible Plug;- Each receiver will have a fusible plug at the bottom of the receiver.
Material of Fusible Plug- Bismuth 50%, Tin 30%, lead20%
Melting Point; – 104 Deg C
- Safety Valve;- Set pressure of safety valve will be 32 to 35 bar ( working pressure 30 bar).
- Compensating Ring;- This ring is mounted on a cut or machining hole to reduce the stresses.
- Manual or Automatic drain valve
- Pressure gauge
- Pressure switch.
Internal Surface coating;- an epoxy coating inside the receiver protects the receiver from corrosion, anti toxic or anti-oxidation.
Safety Device on Main Air Bottle
- Fusing Plug
- Pressure relief valve
- Low air pressure alarm
- Automatic moisture drain valve.
Reciprocating Compressors:: Operation and Maintenance
For anyone responsible for purchasing, servicing, or operating reciprocating compressors, this book discusses the theory of operation and explains how to install, troubleshoot, overhaul, and repair all types of compressors.
This broad comprehensive text offers practical details on how to purchase, service, operate, and maintain compressors used in any of the process industries, Marine etc
Important Marine Engineering books
Introduction to Marine Engineering
This second edition deals comprehensively with all aspects of a ship’s machinery from propulsion and steering to deck machinery and electrical equipment with a strong emphasis upon correct and safe procedures.
Material has been added and revised to reflect the greater weight now being placed upon the cost-effective operation of ships; in terms of greater equipment reliability, more fuel-efficient engines, the ever-increasing shift towards automatically operated machinery, and the need for fewer engineering crew. This is an invaluable guide for professionals but equally covers the requirements for Class 4 and Class 3 Engineer’s Certificates of Competency, the first two years of the Engineer Cadet Training Scheme, and the Engineering Knowledge syllabus for the Master’s Certificate.
General Engineering Knowledge for Marine Engineers
This textbook is key for all marine engineering officer cadets. Accessibly written and clearly illustrated, General Engineering Knowledge for Marine Engineers takes into account the varying needs of students studying “general” marine engineering, recognizing recent changes to the Merchant Navy syllabus and current pathways to a sea-going engineering career. It includes the latest equipment, practices and trends in marine engineering, as well as incorporating the 2010 Manila Amendments, particularly relating to management.
It is an essential buy for any marine engineering student. This new edition reflects all developments within the discipline and includes updates and additions on, among other things:· Corrosion, water treatments and tests· Refrigeration and air conditioning· Fuels, such as LNG and LPG· Insulation· Low sulphur fuels· Fire and safety Plus updates to many of the technical engineering drawings.
Marine Auxiliary Machinery
“The strength and depth of information contained in the book, together with the clarity of the line drawings, makes it ideal for marine engineers studying for certificates of competency but it would also be extremely useful for marine engineer cadets and undergraduate marine engineers. Practising marine engineers, both ashore and afloat would also benefit from possession of this volume which is highly recommended.” Marine Engineer’s Review
Lamb’s Questions and Answers on the Marine Diesel Engine
The book is comprehensive and includes almost all topics needed to understand marine diesel engines. The book explains the role of heat in engineering science, the principles behind internal combustion engines, the role of fuels and lubricants, the cooling systems, the lubricating systems and the heat exchangers.
The book also explains the various parts of the marine engines and their functions. Air-storage tanks and air compressors are also dealt with in the book. Information on balancing and vibration, various instrumentation and control methods, along with the safety measures are covered in the book.
Lamb’s Questions and Answers on the Marine Diesel Engine was published by Butterworth-Heinemann in 1990. The eighth revised edition is available in hardcover.
- Lamb’s Questions and Answers on the Marine Diesel Engine is an ideal reference and guide for marine engineers.
- The book explains topics in detail, making it easy for beginners to understand the subject.
Pounder’s Marine Diesel Engines and Gas Turbines
Pounder’s Marine Diesel Engines and Gas Turbines, Tenth Edition, gives engineering cadets, marine engineers, ship operators and managers insights into currently available engines and auxiliary equipment and trends for the future. This new edition introduces new engine models that will be most commonly installed in ships over the next decade, as well as the latest legislation and pollutant emissions procedures. Since publication of the last edition in 2009, a number of emission control areas (ECAs) have been established by the International Maritime Organization (IMO) in which exhaust emissions are subject to even more stringent controls. In addition, there are now rules that affect new ships and their emission of CO2 measured as a product of cargo carried.
- Provides the latest emission control technologies, such as SCR and water scrubbers
- Contains complete updates of legislation and pollutant emission procedures
- Includes the latest emission control technologies and expands upon remote monitoring and control of engines
Marine Electrical Equipment and Practice
This book Caters to marine engineer candidates for Department of Transport Certification as Marine Engineer Class One and Class Two. It covers the various items of ships’ electrical equipment and explains operating principles.
David McGeorge is a former lecturer in Marine Engineering at the College of Maritime Studies, Warsash, Southampton. He is the author of General Engineering Knowledge.
Practical Marine Electrical Knowledge
This book’s objective is to help marine and electrical engineers acquire the knowledge required by STCW for management and operational level endorsements and to become more familiar with various electrical applications that can be found on board ship
A Pocket Book of Marine Engineering: Questions and Answers
A Pocket Book of Marine Engineering: Questions and Answers is a book that covers the topic of air filter for engine in great detail. This book is a great resource for anyone who wants to learn more about this topic. The author, John Myatt, is a world-renowned expert on marine engineering. In this book, he covers everything from the basics of how these engines work to more advanced topics like choosing the right air filter for your engine. If you’re looking for a comprehensive guide to air filter for engine, this is the book for you.
This handy pocket-sized guide is filled with hundreds of questions and answers on marine engineering, covering all the basics from engines and propulsion to steering and safety. It’s perfect for anyone who wants to learn more about this fascinating subject, whether they’re studying for a qualification or just interested in how boats work. With clear explanations and plenty of diagrams, this book is an essential reference for anyone with an interest in maritime engineering.
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