Famous people
Carl
Gustaf Patrik de Laval
(1845
– 1913)
Carl Gustaf Patrik de Laval was a Swedish engineer and inventor who made important contributions to the design of steam turbine. In 1887 he built a small turbine turned by jets of steam. The de Laval turbine accelerated the steam to full speed before running it against a turbine blade. This was good, because the turbine was simpler and less expensive. It could operate with any pressure of steam. It was also, however, less efficient. In 1890 de Laval added a convergent-divergent nozzle to increase the speed of the steam entering the turbine. He was the first to use this type of nozzle. This is known as a de Laval nozzle and is widely used in some types of steam turbine and is an essential part of the modern rocket engine and supersonic jet engines. He also invented various devices for the dairy industry, including a high-speed centrifugal cream separator and a vacuum milking machine. De Laval's other interests ranged from electric lighting to electrometallurgy in aerodynamics. In the 1890s he employed more than 100 engineers in developing his devices and inventions, which are exactly described in the 1,000 or more diaries he kept.
Unit IX. The Complex Subject
Read the following sentences. State the voice and the tense forms of the predicates. Translate the sentences into Russian, paying attention to the complex subject.
Nowadays semiconductors are known to be used in TV sets, radio sets and computers.
They are known to have used a new computer programme in their work.
They are known to work hard at a new device.
In ancient times light was thought by some philosophers to be a property of the eye.
Heat was for a long time thought to be an invisible fluid.
Light intensity proves to be measurable.
The method didn’t prove to be of any help to us.
The laser beam seems to have unlimited industrial possibilities.
Alpha-rays were found to be positively charged helium atoms.
Only a limited number of reactions are known to be influenced by light.
The lack of data is certain to slow down our work.
Air was considered by the ancients to be an element.
Many substances appeared to dissolve in hot water.
This substance is reported to possess the property of radioactivity.
The changing velocity of the object is likely to affect the accuracy of the measurements.
Read the following text. Find the predicate in each sentence and state the voice and the tense form. Which of the sentences contain the complex subject? Translate the text into Russian.
Gas Burners
Gas is known to be burnt in many industrial furnaces used for heat treating, metal melting, steam generation etc., as well as in commercial applications such as pizza ovens, baker’s ovens, dishwashers, etc., because of its cleanliness, ease of control of furnace atmosphere, ability to produce a long slow burning flame with uniform and gradual energy liberation, and ease of temperature regulation. Environmentally, natural gas burns cleaner than other fossil fuels, such as oil and coal, and produces less greenhouse gases. For an equivalent amount of heat, burning natural gas produces about 30% less carbon dioxide than burning petroleum and about 45% less than burning coal. Thus, power generation using natural gas is the cleanest source of power using fossil fuels, and this technology is widely used wherever gas can be obtained at a reasonable cost.
A gas burner is a device that burns a continuous stream of a flammable gas, such as natural gas. The amount of air mixed with the gas stream affects the completeness of the combustion reaction in the flame. Less air provides an incomplete and thus cooler reaction, while a gas stream well mixed with air provides a complete and hotter reaction. For steam generation, where a short flame is desired in order to reduce the required furnace volume, the burner is expected to provide for rapid and thorough mixing of the fuel and air in the correct proportions for good combustion. For such applications, a good burner is primarily a proportioner and a mixing device. When a molecule of combustible gas is mixed with the oxygen at a temperature above the ignition temperature, combustion is practically instantaneous. In industrial furnaces where long "lazy" flames are desired, slow and gradual mixing of the air and fuel in the furnace is required.
Natural gas is used for steam generation in gas producing areas and in areas where coal is not available at a competitive price. It is also used extensively in coal or oil-fired units during the summer months, when the houses are not heated so there is a temporary surplus of natural gas. Because of the variable or seasonal supply of gaseous fuels, combination burners have been developed to permit the simultaneous burning of the available gas together with pulverized coal or oil.
Transcribe the following words, practice reading them, give Russian equivalents:
Burner, furnace, oven, environment, fossil fuel, carbon dioxide, cycle, surplus, simultaneous, pulverize, molecule, combustible, oxygen, instantaneous.
Are the following sentences true or false? Correct the false sentences
1. Burning natural gas in industrial furnaces has many disadvantages.
2. Gas is never used in coal and oil-fired units.
3. Combination burners permit the burning of gas together with pulverized coal and oil to
produce steam.
4. Combustion is instantaneous when combustible gas is mixed with oxygen at a
temperature below the ignition temperature.
5. In industrial furnaces rapid and thorough mixing of the fuel and air in the correct
proportions are necessary for good combustion.
Answer the questions.
1. What are the advantages of burning gas in industrial furnaces?
2. What is the role of air in a gas burner?
2. In what regions is gas used for steam generation?
3. What conditions are necessary for instantaneous combustion of gas?
4. What kind of flame is desired for steam generation, and why?
5. How can short and long flames be achieved?
6. What is the advantage of combination burners?