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Marine auxiliary machinery - various installations on board
Ships are large, complex vehicles which must be self-sustaining in their
environment for long periods with a high degree of reliability. A ship is
the product of two main areas of skill, those of the naval architect and
the marine engineer.
The naval architect is concerned with the hull, its
construction, form, habitability and ability to endure its environment.
The marine engineer is responsible for the various systems which propel
and operate the ship. More specifically, this means the machinery
required for propulsion, steering, anchoring and ship securing, cargo
handling, air conditioning, power generation and its distribution. Some
overlap in responsibilities occurs between naval architects and marine
engineers in areas such as propeller design, the reduction of noise and
vibration in the ship's structure, and engineering services provided to
considerable areas of the ship.
A ship might reasonably be divided into three distinct areas: the
cargo-carrying holds or tanks, the accommodation and the machinery
space. Depending upon the type each ship will assume varying
proportions and functions. An oil tanker, for instance, will have the
cargo-carrying region divided into tanks by two longitudinal bulkheads
and several transverse bulkheads. There will be considerable quantities
of cargo piping both above and below decks.
The general cargo ship will
have various cargo holds which are usually the full width of the vessel
and formed by transverse bulkheads along the ship's length. Cargo handling
equipment will be arranged on deck and there will be large
hatch openings closed with steel hatch covers. The accommodation areas
in each of these ship types will be sufficient to meet the requirements for
the ship's crew, provide a navigating bridge area and a communications
centre. The machinery space size will be decided by the particular
machinery installed and the auxiliary equipment necessary.
ship, however, would have a large accommodation area, since this might
be considered the 'cargo space'. Machinery space requirements will
probably be larger because of air conditioning equipment, stabilisers and
other passenger related equipment.
Three principal types of machinery installation are to be found at sea
today. Their individual merits change with technological advances and
improvements and economic factors such as the change in oil prices. It is
intended therefore only to describe the layouts from an engineering
point of view. The three layouts involve the use of direct-coupled
slow-speed diesel engines, medium-speed diesels with a gearbox, and the
steam turbine with a gearbox drive to the propeller.
A propeller, in order to operate efficiently, must rotate at a relatively
low speed. Thus, regardless of the rotational speed of the prime mover,
the propeller shaft must rotate at about 80 to 100 rev/min. The
slow-speed diesel engine rotates at this low speed and the crankshaft is
thus directly coupled to the propeller shafting. The medium-speed
diesei engine operates in the range 250—750 rev/min and cannot
therefore be dircci'f coupled to the propeller shaft. A gearbox is used to
provide a low-speed drive for the propeller shaft. The steam turbine
rotates at a very high speed, in the order of 6000 rev/min. Again, a
gearbox must be used to provide a low-speed drive for the propeller
Machinery, other than the main propulsion unit, is usually called
'auxiliary' even though without some auxiliaries the main machinery
would not operate for long. The items considered are air compressors, heat
exchangers, distillation equipment, oil/water separators, sewage treatment plants
Operational guideline for various auxiliary machinery described here:
- Compressed Air Systems for various shipboard operations
The main aim of a compressor, as the name suggests, is to compress air or any fluid in order to reduce its volume. Some of the main applications of compressors onboard ships are main air compressor, deck air compressor, AC compressor and refrigeration compressor. Failure to start or control air compressor can be inconvenient, costly and can carry risks, which need to be managed.....
- Marine air compressors working principles
Control or instrument air supplies have particular requirements with regard to being moisture and oil free and without impurities. A special type of oil-free compressor may be used to supply control air or it may be treated after delivery from an ordinary air compressor. This treatment results in the air being filtered and dried in order to remove virtually all traces of oil, moisture and any atmospheric impurities.....
- Coolers at sea- Shell and tube type coolers and plate type coolers Heat exchangers on board ship are mainly coolers where a hot liquid is cooled by sea water. There are some instances where liquid heating is required, such as heavy fuel oil heaters and sea water heaters for tank cleaning. Although being heat exchangers, the main condenser for a steam ship and the evaporator/distiller are dealt with separately .....
- Distillation system- Production of distilled water for ships use - The evaporation process
Distillation is the production of pure water from sea water by evaporation and re-condensing. Distilled water is produced as a result of evaporating sea water either by a boiling or a flash process. This evaporation enables the reduction of the 32000 parts per million of dissolved solids in sea water down to the one or two present in distilled water. The machine used is called an 'evaporator', although the word 'distiller' is also used.....
- Oily water separator and filter unit for 15 parts per million purity
Oil/water separators are used to ensure that ships do not discharge oil when pumping out bilges, oil tanks or any oil-contaminated space. International legislation relating to oil pollution is becoming more and more stringent in the limits set for oil discharge.....
Sewage treatment on board- biological and chemical sewage treatment plantThe discharge of untreated sewage in controlled or territorial waters is usually banned by legislation. International legislation is in force to cover any sewage discharges within specified distances from land. As a result, and in order to meet certain standards all new ships have sewage treatment plants installed.....
- Incinerator for ships Stricter legislation with regard to pollution of the sea, limits and, in some instances, completely bans the discharge of untreated waste water, sewage, waste oil and sludge. The ultimate situation of no discharge can be achieved by the use of a suitable incinerator. When used in conjunction with a sewage plant and with facilities for burning oil sludges, the incinerator forms a complete waste disposal package.....
Marine machineries - Useful tags
Marine diesel engines ||Steam generating plant ||Air conditioning system ||Compressed air ||Marine batteries ||Cargo refrigeration ||Centrifugal pump ||Various coolers ||Emergency power supply ||Exhaust gas heat exchangers ||Feed system ||Feed extraction pump ||
Flow measurement || Four stroke engines || Fuel injector || Fuel oil system || Fuel oil treatment ||Gearboxes || Governor ||
Marine incinerator ||
Lub oil filters ||
MAN B&W engine ||
Marine condensers ||
Oily water separator ||
Overspeed protection devices ||
Piston & piston rings ||
Crankshaft deflection ||
Marine pumps ||
Various refrigerants ||
Sewage treatment plant ||
Starting air system ||
Steam turbines ||
Steering gear ||
Sulzer engine ||
Turbine gearing ||
Two stroke engines ||
UMS operations ||
Drydocking & major repairs ||
Critical machinery ||
Deck machineries & cargo gears
|| Control and instrumentation
||Engine room safety ||
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