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Monday, 8 December 2014

Methods of Compounding Steam Engines

Methods of Compounding Steam Engines Points : Methods of Compounding Steam Engines, Tandem compound engines, Woolf compound engines, Receiver compound engines The compounding of steam engines can be prepared with combining above one cylinder of steam engines such that expansion of steam occurs consecutively in these cylinders. There are mostly two approach of compounding, which is tandem type and cross type. Cross type compounding can be of woolf type and receiver type. Therefore compound steam engines can be classified as under based on method of compounding.
(i) Tandem Compound Engines
(ii) Woolf Compound Engines
(iii) Receiver Compound Engines
(i) Tandem Compound Engines A tandem compound engine has the in line cylinders have pistons mount on similar piston rod which is more having crosshead and connecting rod given that power output on crankshaft. Shows diagram of tandem compound steam engine have two in line cylinders. Steam on high pressure first enters HP cylinder and gone getting partly extended enters the LP cylinders. Two pistons of HP and LP cylinders are mounting such that two cylinders make power output with no any phase disparity. Highest output and lowest output as of both cylinders is existing at same crank angle position and output is of additive type i.e. highest torque as of compound engine. Hence there exists very large variation of torque through a cycle and for compensate this large variation heavy flywheel with large balancing weights are necessary.
(ii) Woolf Compound Engine Woolf compound engine is a cross type compounding have two cylinders have pistons on 180° stage difference that is at several position one cylinder might have piston at inner dead centre with other cylinder have piston at outer dead centre. Cylinders are set parallel to one an additional and steam leaving HP cylinder enters into LP cylinder directly thus expansion remains continuous all over the stroke. As the power output as of two cylinders is offered by phase difference of 180° so the torque variation is extremely large similar to that in case of tandem compounding. So, in woolf compound engine too large flywheel is necessary.
(iii) Receiver Compound Engine Receiver compound engine is too a cross compound engine have two cylinders with no of phase pistons and receiver in among. Here cranks for two cylinders are at 90°. In this steam leaving HP cylinder pass into receiver and then at correct time steam enters LP cylinder. Receiver is requisite as two cylinders have out of phase pistons and exhaust as of HP does not go directly into LP cylinder, so a few type of storage is a need. Maximum torque and smallest torques are not at same time so torque difference is not over in this compounding. Therefore size of flywheel necessary is smaller in this arrangement. Too balancing must is not too much lest of receiver compounding. As steam is store in reservoir so there are chances of pressure drop and heat beating on in receiver. These losses decrease efficiency of receiver compound engine and so need a few jacketing/ steam heating of receiver to stop heat loss.

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