Modern ships are far more automated than their predecessors and, as such, tend to have smaller crews. Machinery with reduced and easy maintenance is a factor whose importance has changed from being desirable to becoming essential. The problem for the machinery designers is that the physical space available is continually being reduced. Simultaneously, the acceptable standards for vibration and noise are also being reduced. In this short talk I would like to outline how Tanabe Pneumatic Machinery Co Ltd is coping with these problems and also future developments.
One consequence of these developments is that there are now considerably fewer compressors on board ship than there were 40 years ago. At that time there were commonly 6 or 7 air compressors for different duties, (main starting, topping-up, emergency starting, control air, general service & soot blowing). Due to space and cost restrictions, this number has been reduced, with modern compressors often having to fulfil multiple duties, resulting in longer running hours. The consequences of a breakdown have thus increased and so reliability and ease of servicing has taken on an even greater importance
Examining the types of compressors, which are commonly found on board, we note the following:
Engine Starting Compressors
These normally operate at 30 bar, (sometimes 25 bar) and are required to be class approved. Regulations require that such essential equipment is duplicated. Traditionally these have been of the 2 stage, water cooled type.
Tanabe recently introduced a new range (4 models) of 2 stage air-cooled starting air compressors extending up to 80 m3/hr. These rugged, inexpensive machines have splash lubrication and a composite cylinder, eliminating the need for a separate cylinder head. The L.P. valve is held in place with a simple valve retainer bolted directly into the cylinder. For the two larger machines the crankshaft is supported at each end by taper roller bearings, whilst the smaller, single cylinder machines have a drive element supported from just one side, using cylindrical roller bearings.
For larger capacities, Tanabe offers the 3 stage VLHH range, which extends up to 660 m3/hr at 30 bar.
