FOSSIL FUELS”..

Task 13

Fill the gaps in sentences below with a preposition

of at to in due to

1. The once-through generating units are widely used…high pressures.

2. The main aggregate…the steam-generating equipment…thermal power plant is the steam-generating unit

3. The loss…the energy …combustion…the fuel is reduced… minimum.

4. A bank of tubes is connected… the drum.

5. The discharge…gaseous products will result… a large loss…energy.

Task 14

Complete the text using the following words

Boilers

Boiler surface (1) ____________ as the tubes and drum shells that are part of the steam-water circulation system, and that are in contact with the hot gases (flue gas). Although the term boiler now frequently (2) _______________ the overall steam generating system, the term boiler sur­face (3) _______________ the economizer, superheater, reheater, or any component other than the steam-water circulation system itself.

While boilers (4) __________broadly _________as fire tube and water tube types, modern high capacity boilers are of the water tube type. In the water tube boiler, the water and steam flow inside the tubes and the hot gases flow over the outside surfaces. The boiler circulation system (5) ______________ of tubes, headers, and drums joined in an arrangement that provides water flow to generate steam while cooling all parts. The water tube construction (6) ____________ greater boiler capacity and higher pressure than shell or fire tube designs. The water tube boiler also (7) ______________ greater versatility in arrangement; this

(8) ______________ the most efficient use of the furnace, superheater, reheater, and other heat recovery components.

Modern high capacity boilers come in a variety of designs, sizes, and configurations to suit a broad range of applications. Sizes (9) ________________ 1000 to 10,000,000 lb/h (0.13 to 1260 kg/s) and pressures range from one atmosphere to above the critical pressure.

The combustion system, fuel, ash characteristics, operating pressure, and total capacity largely

(10) ____________________ the boiler configuration.

WRITING

Ways of linking ideas

When we write, we may have to describe, explain, argue, persuade, complain, etc. In all these forms of writing, we use ideas. To make our writing effective, we have to make sure our readers can follow our ideas. One way of helping our readers is to make the links between the ideas in our writing.

What are the links between these pairs of ideas? What words can we use to mark the links?

1 Mechanisms are important to us.

2 They allow us to travel.

3 Mechanisms deliver the power to do work.

4 They play a vital role in industry.

5 Friction is sometimes a help.

6 It is often a hindrance.

Sentence 2 is a reason for sentence 1. We can link 1 and 2 like this:

Mechanisms are important to us because /since /as they allow us to travel

Sentence 4 is the result of sentence 3. We can link 3 and 4 like this:

Mechanisms deliver the power to do work so they play a vital role in industry. Mechanisms deliver the power to do work; therefore they play a vital role in industry.

Sentence 6 contrasts with sentence 5. We can link 5 and 6 like this:

Friction is sometimes a help but it is often a hindrance.

Task 15

Show the links between these sets of ideas using appropriate linking words.

1. Once-through boiler is widely used.

It has many advantages.

2. The costly drum is eliminated.

Capital costs are lower.

3. Steam temperature is related to enthalpy.

Steam temperature will depend on the ratio of heat input to throughput.

4. Such steam generating units are called the once-through generating units.

Water passes through the whole aggregate without multiple circulation.

Task 16

Write an abstract of the text “Boilers” according to the plan. Writing an abstract use the following linking devices: firstly, first of all, furthermore, in addition to, moreover, finally, in conclusion and so on.

1. The definition of boiler surface.

2. Classification of boilers, their advantages.

3. Boiler configurations.

FUEL

Tuning in

Task 1

List the different types of fuel.

Task 2

Study the diagram below. Answer these questions using the diagram and your own knowledge.

1. In what regions are there the largest reserves of crude oil, natural gas and coal ?

2. What regions have the smallest reserves of crude oil, natural gas and coal?

3. How do you think, what countries are the principal exporters of these fossil fuels?

WORDLIST

Task 3

The following words will help you understand the text. Try to remember the pronunciation and meanings of these words.

Pronunciation

Task 4

Read the following words and remember their pronunciation

source [ ]

carbon [ ]

purpose [ ]

gaseous [ ]

cause [ ]

hydrogen [ ]

liquefaction [ ]

Task 3

Define the meanings of the words in bold.

The basis for hydrogen manufacture, modern equipment, industrial purposes, 28 per cent of all commercial energy, energy concentrated in the decay, they may be divided into two main groups, there is a strong tendency, is used as a raw material, include other processes, petroleum is a mixture of hundreds of different hydrocarbons, reduce its economic value, energy applied for transportation, derived from natural gas.

READING

FOSSIL FUELS”..

Task 4

Look at these questions and read the passage to find answers.

1. What fuels are often referred to as fossil fuels?

2. What types of fossil fuels do you know?

3. Is coke a natural or artificial solid fuel?

4. How are coke and charcoal produced?

5. What are the advantages of gaseous fuels?

The chief sources of energy available to man today are oil, natural gas, coal, water power and atomic energy. Coal, gas and oil represent energy that has been concentrated by the decay of organic materials (plants and animals) accumulated in the geologic past. These fuels are often referred to as fossil fuels.

Most fuels are carbon- containing substances that are burned in air. In burning fuels give off heat which is used for different purposes.

Fuels may be solid, liquid and gaseous. Solid fuels may be divided into two main groups, natural and manufactured. The former category includes coal, wood, peat and other plant products. The latter category includes coke and charcoal obtained by heating coal in the absence of air.

Coal is of great importance for the development of modern industry. It provides about 28 per cent of all the commercial energy used in the world. It may be used for domestic and industrial purposes. Being the main source of coke, coal is widely used in the iron and steel industry.

There is a strong tendency now for increased research into new technologies to utilize coal. No doubt, coal will be used as a raw material for the chemical industry and petrochemical processes. All these processes involve coal conversions which include gasification designed to produce

synthetic gas from coal as the basis for hydrogen manufacture, liquefaction for making liquid fuel from coal and other processes.

The mining, transportation and burning of coal involve serious problems. Strip mining destroys trees and produces some disturbances on the Earth’s surface which reduce its economic value. After coal has been mined, it is expensive to haul it from the mines. And when burned, it releases sculpture and other impurities that pollute the air and cause acid rains.

Liquid fuels are derived almost of petroleum. In general, natural petroleum, or crude oil, as it is widely known, is the basis of practically all industrial fuels. Petroleum is a mixture of hundreds of different hydrocarbons – compounds composed of hydrogen and carbon – together with the small amount of other elements such as sculpture, oxygen and nitrogen. Petroleum is one of the most efficient fuels and raw materials. It furnishes about 40 per cent of the commercial energy used in the world. It provides most of the energy applied for transportation and heats millions of homes as well.

Petroleum is easier to get out of the ground than coal, and pipelines carry it cheaply over long distances. Like coal, oil contains impurities that cause air pollution. But refineries can remove many of these pollutants when they process the petroleum.

Of gaseous fuels the most important are those derived from natural gas, chiefly methane or petroleum. Using gaseous fuels makes it possible to obtain high thermal efficiency, ease of distribution and control. Gas is the most economical and convenient type of fuels. It is the cleanest one and can easily be transported through pipelines, and it causes almost no pollution. Today gas is widely utilized in the home and as a raw material for producing synthetics. It accounts for about 20 per cent of the commercial energy used in the world.

Generally speaking, all types of fossil fuels described in the text are of great economic importance as they represent the sources of energy the man uses today.

Date: 2014-12-29; view: 2344