武汉理工大学：《船舶辅机》课程教学资源（PPT课件，英文版）1.5 COMPRESSED AIRSYSTEMS

1.5 COMPRESSED AIR SYSTEMS Air at high pressure, i.e. at 25 bar or more, is required for starting main 口owTR SEPARATOR and auxiliary engines in motorships Air at low pressure, say at 6 bar or less is required for much remote or temperature or pressure controlled equipment, for which purpose it must be clean and oil-free

1.5 COMPRESSED AIR SYSTEMS • Air at high pressure, i.e. at 25 bar or more, is required for starting main and auxiliary engines in motorships. • Air at low pressure, say at 6 bar or less is required for much remote or temperature or pressure controlled equipment, for which purpose it must be clean and oil-free. OIL/WATER SEPARATOR

1.5 COMPRESSED AIR SYSTEMS a typical simple h p. air system is shown in the below Figure; the arrangement of a larger system can be readily envisaged from this diagram

1.5 COMPRESSED AIR SYSTEMS • A typical simple h.p. air system is shown in the below Figure; the arrangement of a larger system can be readily envisaged from this diagram

STOP VALVES ON AIR RECEIVERS TO BE SLOW OPENING TYPE OILWATER AIR SEPARATOR RECEIVER NrV COMPRESSORS FROM EMERGENCY COMPRESSOR SDNR ALL AIR COMPRESSORS AND VALVE AUX. AIR RECEIVERS TO BE FITTED WITH DNR RECEIVER SUITABLE SAFETY VALVWS AND ENGINE VALVE AUX DRAIN VALVES ENGINE MAIN ENGINE

OIL/WATER SEPARATOR AIR COMPRESSORS FROM EMERGENCY COMPRESSOR ALL AIR COMPRESSORS AND RECEIVERS TO BE FITTED WITH SUITABLE SAFETY VALVWS AND DRAIN VALVES AUX. ENGINE SDNR VALVE SDNR VALVE AIR RECEIVER STOP VALVES ON AIR RECEIVERS TO BE SLOW OPENING TYPE MAIN ENGINE NRV AUX. ENGINE AUX.AIR RECEIVER

1.5 COMPRESSED AIR SYSTEMS AIR RECEIVER It is a requirement that there shall be at least two reservoirs whose combined capacity allows the main engines to be started twelve times if they are reversible and six times if they are not, while the e compressors are idle

1.5 COMPRESSED AIR SYSTEMS • It is a requirement that there shall be at least two reservoirs whose combined capacity allows the main engines to be started twelve times if they are reversible and six times if they are not, while the compressors are idle

1.5 COMPRESSED AIR SYSTEMS Safety valves must be fitted these may be common to the compressors but if they can be isolated from the reservoirs the latter must have fusible plugs fitted to prevent rupture in the event of fire Reservoirs are designed built and tested similarly to boiler drums Compressors are discussed, two or more independently driven are usually fitted each capable of charging one reservoir from zero to working pressures in a reasonable time

1.5 COMPRESSED AIR SYSTEMS • Safety valves must be fitted; these may be common to the compressors but if they can be isolated from the reservoirs, the latter must have fusible plugs fitted to prevent rupture in the event of fire. • Reservoirs are designed, built and tested similarly to boiler drums. • Compressors are discussed, two or more, independently driven, are usually fitted, each capable of charging one reservoir from zero to working pressures in a reasonable time

1.5 COMPRESSED AIR SYSTEMS Explosions can and do occur in starting air pipes caused b the ignition of oil or vapour gaining access from compressors or defective engine starting valves

1.5 COMPRESSED AIR SYSTEMS • Explosions can and do occur in starting air pipes caused by the ignition of oil or vapour gaining access from compressors or defective engine starting valves

1.5 COMPRESSED AIR SYSTEMS The need for careful maintenance, cleaning and draining is important →· Bursting discs are fitted (usually in the form of a thin copper closed-ended cylinder)to minimize and localize the effects

1.5 COMPRESSED AIR SYSTEMS • The need for careful maintenance, cleaning and draining is important. • Bursting discs are fitted (usually in the form of a thin copper closed-ended cylinder) to minimize and localize the effects

1.5 COMPRESSED AIR SYSTEMS Starting air for AIR auxillary engines RECEIVER may be taken directly from the main reservoirs or NRV through an auxiliary reservoir (which can be kept at full pressure at all times) SDNR VALVE

1.5 COMPRESSED AIR SYSTEMS • Starting air for auxiliary engines may be taken directly from the main reservoirs or through an auxiliary reservoir (which can be kept at full pressure at AUX.AIR all times). RECEIVER SDNR VALVE AIR RECEIVER NRV

1.5 COMPRESSED AIR SYSTEMS Low pressure air is usually taken through reducing valves or pressure regulators to a low pressure reservoir Alternatively, the l p reservoir may be charged by an oil-free compressor, rotary or reciprocating

1.5 COMPRESSED AIR SYSTEMS • Low pressure air is usually taken through reducing valves or pressure regulators to a low pressure reservoir. • Alternatively, the l.p. reservoir may be charged by an oil-free compressor, rotary or reciprocating