II. Read and translate text 7. Text 7

Non-reheat turbine

The main steam stop valve is installed under the front floor of the turbine room and the steam control valves are arranged on the top and bottom of the high pressure casing. During operation, steam is supplied through these valves from the top and bottom of the high pressure casing large temperature differences, which may otherwise occur between the top and bottom of the casing.

The cross-over pipe which conducts steam from the high pressure turbine to the low pressure turbine is constructed in one piece with the low pressure casing.

In the parts where the rotor passes through the casing, are installed packing glands and both labyrinth packings and water seal packings are provided. These devices help shorten the length of the gland packing part and prevent the leakage of steam from these parts into the air during operation.

Reheat Turbine

This turbine consists of a high pressure part and intermediate and low pressure parts. The high and intermediate pressure parts are encased in a high pressure casing and the low pressure part in a low pressure casing. The steam inlet to the turbine is installed in the centre of the high pressure casing and in the high and intermediate pressure parts steam flows in opposite directions. These devices contribute to balance and minimize the thrust force of the rotor. Moreover, they allow to collect high temperature zones in a part of the casing; an excessively great temperature gradient can be prevented.

III. Answer the questions to text 7.

1. Where is the main steam stop valve installed?

2. Where is the steam control valve arranged?

3. What is steam supplied through during operation?

4. What may occur between the top and bottom of the casing?

5. What can you say about construction of the cross-over pipe?

6. What devices help shorten the length of the gland packing part?

7. What does reheat turbine consist of?

8. Where are the high and intermediate pressure parts encased in?

9. Where is the steam inlet to the turbine installed?

10. What can you say about the main function of the turbine’s parts?

UNIT 8

1. In TEXT 8 find the answer to the following question

Найдите в тексте 8 ответ на вопрос: «Какое топливо для теплоэлектро-станций остается самым важным и самым дешевым?»

TEXT 8

THERMAL POWER STATION

A modern thermal power station is known to consist of four principal components, namely, coal handling and storage, boiler house, turbine house, switchgear.

Besides the principal components mentioned above there are many additional parts of the plant. The most important of them is the turbo-generator in which the current is actually generated.

A steam turbine requires boilers to provide steam. Boilers need a coal-handling plant on the one hand and an ash-disposal plant on the other. Large fans are quite necessary to provide air for the furnaces. Water for the boilers requires feed pumps. Steam must be condensed after it has passed through the turbines, and this requires large quantities of cooling water. The flue gases carry dust which must be removed by cleaning the gases before they go into the open air.

A modern thermal power-station is equipped with one or more turbine generator units which convert heat energy into electric energy. The steam to drive the turbine which, in its turn, turns the rotor or revolving part of the generator is generated in boilers heated by furnaces in which one of three fuels may be used – coal, oil, or natural gas. Coal continues to be the most important and most economical of these fuels.