Boilers

A boiler is a closed vessel in which water, under pressure, is transformed into steam by the application of heat. Open vessels and those generating steam at atmospheric pressure

are not considered to be boilers. The furnace converts the chemical energy in the fuel into heat. The function of the boil­er is to transfer this heat to the water in the most efficient manner.

Progress in steam-boiler development has been rapid. The first boilers were very crude affairs, as contrasted with our present-day standards. The greatest number of contribu­tions have been made in the last half century. The field of application is diversified. Boilers are used for heating, sup­plying steam for processes, furnishing steam to operate en­gines etc.

Maintaining the correct boiler water level is the most important duty of the boiler operator. It is of the utmost im­portance that the manufacturer supply suitable and reliable devices for indicating the water level. Coal as well as liquid and gaseous fuels are used for boiler firing. The ideal boiler must be of correct design, sufficient steam and water space and good water circulation.

VIII. Oral Practice

Speak about different types of engines and turbines according to the plan.

1. Internal combustion engines

1. heat engines

2. diesel engines

3. steam engines

2. Turbines

1. Definition of steam turbines

2. Fundamental parts of steam turbines

3. Other types turbines

3. Boilers

1. Definition of boiler

2. History of the boiler development

3. Ideal boiler.

Supplementary reading The Wankel Engine

The Wankel engine is form of heat engine which has a rotary piston. In other words, instead of going up and down the Wenkel piston rotates in the cylinder. Both cylinder and piston are quite different in shape from those of conventional engines. The Wankel engine is triangular with curved sides and the cylinder is roughly oval in shape. The piston has an inner bore which is linked through an eccentric gear to the output shaft. The other end of the bore is toothed and engaged with a stationary gear fixed to the cylinder end. This arrangement ensures that the piston follows an elliptical path round the cylinder so that the apexes of the piston, which carry gastight seals, are always in contact with the inside surface of the cylinder.

The Wankel engine has many advantages over the reciprocating piston engine. Fewer moving parts are necessary because it produces a rotary movement without using a connecting rod and a crankshaft. Because of this rotary movement it has no vibration. In addition it has no valves, it is smaller and lighter than conventional engines of the same power, and it runs economically on diesel and several other fuels.

Notes:

reciprocating movement – зворотньо поступальний рух

triangular – трикутний

inner bore – внутрішній отвір

gear – шестерня

apex – верхівка

gastight seal – газонепрониклива прокладка

connectying rod - шатун