Skip to main content

Difference between air coolers for shipboard reciprocating main air compressor and Large slow speed two stroke Marine diesel propulsion engines


  • In both cases the  air coolers are  for increasing the efficiency of the compressors by inter cooling.  
  • Both T/C and Reciprocating compressors are meant to increase pressure , however to a different degree ( T/C : 4 for single stage , and 10 bar for 2stage turbo chargers) 
  • During the compression the air temp raises when the pressure is increased, and need to be cooled. 
  • Cooling is by fresh water / sea water / air in the Main Air Compressors and  Either Sea water or Fresh Water(LT)
  • Cooling is controlled in Engine Coolers to maintain the Air Temperature to the required value, to reduce water impingement on to the liners. Cooling is not controlled in air coolers of Main Air Compressors ( the lower the temp is better for the efficiency), hence there will be control valves for Engine Air Coolers and no control valves for Air Compressor coolers.
  • Engine Coolers are very large in comparison to Main Air Compressors as the air flow is very large ( depend on the Engine power rating)
  • Engine coolers are difficult to remove  and maintain and hence there will be a system installed to clean the coolers by using the chemical, where as air compressor coolers are not fitted with cleaning  arrangement.
  • Engine Coolers are not required to be fitted with any pressure safety devices, as the pressure is lesser and safety can be achieved by the construction itself. However for Main Air Compressor coolers each and every cooler must be fitted with safety valve to relieve excessive pressure which can be due to leakage of interstage valves.
  • Both Engine Coolers and Main Air Coolers  are fitted with water ( condensate from air ) separators.

Labels:

Comments

Post a Comment

If you have any doubts.Please let me know

Popular posts from this blog

Manganese bronze is not typically used as a propeller material .Why

1. High cost: Manganese bronze is a costly alloy, making it less economical for large propellers. 2. Low strength-to-weight ratio: Compared to other propeller materials like nickel-aluminum bronze or stainless steel, manganese bronze has a lower strength-to-weight ratio. 3. Susceptible to corrosion: Manganese bronze can corrode in seawater, especially when exposed to high velocities and turbulence. 4. Poor cavitation resistance: Manganese bronze is more prone to cavitation damage than other materials. 5. Difficult to cast and machine: Manganese bronze is challenging to cast and machine, making it less desirable for complex propeller geometries. 6. Limited weldability: Manganese bronze has poor weldability, making repairs and modifications difficult. Nickel-aluminum bronze or stainless steel are commonly used for propellers due to their: - High strength and durability - Excellent corrosion resistance - Good cavitation resistance - Ease of casting and machining - Weldability
107 comments
Read more

MAN B&W MC Engine VIT Pump

The pump is basically a jerk type with a plunger moving in a matched barrel, using two helical grooves machined in the plunger to control the end of injection by uncovering spill ports and causing the discharge pressure to drop rapidly, thus causing the needle valve in the injector to close. Oil is supplied to the barrel via the spill ports and a suction valve. The suction valve, situated at the top of the barrel opens when the pressure in the  barrel falls below the supply pump pressure; i.e. during downward stroke of plunger, while spill ports are covered by plunger. Replaceable erosion plugs  are fitted in the pump housing opposite the spill ports. The high pressure oil, spilling back, as the edge of the helix uncovers the s...
Post a Comment
Read more

Main engine interlocks

Interlocks are provided so that the engine can be started or reversed only when certain conditions have been fulfilled. When there is a remote control of engines, it is essential to have interlocks. This reduces the possibility of engine damage and any hazards to the operating personnel. Turning gear Interlock . This device prevents the engine from being started if the Turning gear is engaged. Running Direction Interlock . This prevents the fuel from being supplied if the running direction of the engine does not match the Telegraph. Starting Air Distributor in end position . This prevents starting from taking place if the shifting of the Distributor has not been completed. Main Lube. oil pressure, Piston cooling pressure, Jacket water pressure, and important parameters must be above the required minimum. Auxiliary Blower Interlock . The Auxiliary Blower is provided in case of Constant pressure turbo charging. Air Spring pressure Interlock . In case of the present generation...
9 comments
Read more