Types and characteristics
Turbines have developed to their present forms along various lines according to steam conditions, condensing water available, types of service, and requirements as to cost and economy; and this process is still going on, with all builders continually changing, experimenting with, and improving their product.
Definitions.
A steam turbines may be defined as a form of heat engine in which the energy of the steam is transformed into kinetic energy. The kinetic energy of the resulting jet is in turn converted into force doing work on rings of blading mounted on a rotating-part.
The usual turbines consists of four fundamental parts: the rotor which carries the blades or buckets; the stator consisting of cylinder and casing, which are often combined and within which the rotor turns; the nozzles or flow passages for the steam; and the frame or base. Cylinder, casing, and the frame are often combined, particularly in small turbines. For adjusting the energy supply to the turbine to suit the load to be carried and maintaining constant speed, a lubricating system, piping for steam supply and exhaust, and a condensing system.
Make the translation of Steam Turbines classifications.
Classifications of Steam Turbines.
Steam turbines may be classified in the following ways:
A. With respect to form of steam passage between the blades:
a. Impulse
1. Simple, or single-stage
2. Velocity-stage, Curtis
3. Pressure-stage, Rateau
4. Combination pressure and velocity-stage
b. Reaction, Parsons
c. Combination impulse and reaction
B. With respect to general arrangement of flow:
a. Single-flow
b. Double-flow
c. Compound, two or three-cylinder, cross or tandem
d. Divided-flow
C. With respect to direction of steam flow relative to plane
a. Axial-flow
b. Radial-flow
c. Tangential-flow
D. With respect to repetition of steam flow through blades;
a. Single-pass
b. Re-entry or repeated flow
E. With respect to rotational speed:
a. For 60-cycle generators
b. For 50-cycle generators
c. For 25-cycle generators
d. For geared units and for direct-connected or electric-drive
F. With respect to relative motion of rotor or rotors:
a. Single-motion
b. Double-motion
G. With respect to steam and exhaust conditions:
a. High-pressure condensing
b. High-pressure non-condensing
c. Back -pressure
d. Superposed or topping
e. Mixed-pressure
f. Regenerative
g. Extraction, single
h. Extraction, double
i. Reheating or re-superheating
j. Low-pressure.
3. Answer the questions of the text:
1. Have turbines developed to their present forms along various lines?
2. May a steam turbine be defined as a form of heat engines?
3. What is the kinetic energy?
4. What does a steam turbine consist of?
5. Cylinder, casing and frame are combined in small turbines, are not they?
6. What way may steam turbine be classified in?
4. Is it true or false?
- A steam turbine may not be defined as a form of heat engine.
- The energy of the steam is transformed into electric energy.
- The kinetic energy of the resulting jet is in turn converted into heat.
- The usual turbines consist of six fundamental parts.
- The stator consisting of cylinder and casing.
- The nozzle or flow passages for the steam fixed to the cylinder.
- The frame or base for supporting both the stator and the robot, carried in bearing.
- Cylinder and rotor are often combined.
- Accessories are controlling or governing system for the energy.
- Steam turbines may be classified in the seven ways.
5. Find the Ukrainian equivalents of the expressions:
v Low-pressure
v Impulse
v Velocity-stage
v Reactions
v Back-pressure
v Double-flow
v Radial-flow
v Single-pass
v Single-motion
v regenerative
6. Make un 5 sentences with following words:
| Cylinder, turbines, engine, heat, steam, rotor, frame, bearings. |
