THE EXHAUST TURBINE

Dominion, Volume 23, Issue 83, 2 January 1930, Page 14

THE EXHAUST TURBINE

AUXILIARY ELECTRIC PROPULSION A new variation of the exhaust turbine auxiliary drive has been fitted in the Elleriiian liner City of Hongkong. The exhaust-turbine takes steam through a bypass valve' and separator from the low pressure cylinder of the 80 r.p.m., 4400 i.h.p. triple-expansion engine. The output of the generator lias beeu designed to supply ample current to tlie 1300 s.h.p., 83 r.p.m. dual-current motor, which is mounted on au after section of tlie propeller shaft. The control of the by-pass valve which deilects tlie exhaust steam either to tlie exhaust turbine or directly to the condenser is effected by a hand-opera-ted lever on an oil relay system. Suitable contact reversing switches are also provided, which enable the auxiliary propelling motor to be reversed witli the engine. The capacity of the condenser Ims been adapted to meet the new conditions, and a steam ejector has been added to increase tlie working vacuum, and a new circulating pump has been installed. In comparative consumption trials which extended over a period of nearly three hours, tlie machinery was run with the propelling motor in and out of commission. With both the engine and motor working, 11 total of approximately 4900 equivalent i.h.p. was developed, at a propeller speed 0f”84.5 r.p.m. With the engine alone a power of 3190 i.h.p. was recorded at 75.2 revolutinos per minute. The corrected steam consumptions, after allowing for the increase in back pressure caused by placing a steam separator between tlie engine and tlie turbine, showed that witii the electrical plant, in operation the actual steam consumption was 90851b5. per i.h.p. compared with 12.121b5. .for the i.h.p. reciprocating engine alone, thereby showing a decrease in steam consumption due to the exhaust turbo system of 23 per eent. Tlie endurance trials, reversing trials, and tests in heavy weather to demonstrate tlie steadying effect of the auxiliary propelling machinery on the propeller were equally satisfactory.