Construction of Centrifugal Compressor
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Compressor Proper (Air end)
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Scroll : Circular and tubular casting widening its sectional areas toward rotating direction. Accommodates impeller in center portion of it. Form diffuser together with inlet. (vane less diffuser)
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Inlet : Covers scroll and impeller. Constructs compression chamber at rear side together with scroll. Form ventuli tube at front side. Makes air flow to impeller smooth.
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Diffuser: Vane less type: Space or area formed by inlet and scroll (in between tubular portion and outlet circumference of impeller).
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Impeller: Stainless casting machined to attain designed profile. Blade number is 16. Impeller are fitted at the end of pinion shafts.
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Pinion shaft : Drives impeller at specified speed. This compressor has two pinions arranged on both sides of the bull (wheel) gear. Gear ratio is as follows.
Bull gear speed is ..... r.p.m. , driving
Low speed pinion at ..... r.p.m. , and
high speed pinion at ..... r.p.m. ,
Low speed pinion is fitted two impellers at both ends, that is, 1st stage and 2nd stage impeller. High speed pinion is fitted 3rd stage is supported by tilting-pad type journal bearings at two points.
Thrust collars are fitted on both ends of gear teeth to transmit thrust force caused by impeller and gear meshing to the bull gear (thrust shoulder)