Механика WORDLIST просмотров - 132
|1. to release||освобождать|
|2. to ensure||обеспечивать, гарантировать|
|4. to pulverize||распылять, размельчать|
|7. correct||соответствующий, правильный|
|8. regardless of||несмотря на|
|9. to maintain||поддерживать, сохранять|
|10. due to||благодаря|
|11.to reduce||уменьшать, сокращать|
|12.to escape||давать утечку, улетучиваться|
|15.cyclone furnace||термическая печь с принудительной циркуляцией газа|
|16.pulverized coal furnace||пылеугольная топка|
|17.spreader stoker||топка с разравнивающей решёткой|
|18.chain grade stoker||механическая топка с цепной решёткой|
Remember the pronunciation of the following words
Fill in the table
Read the text and look for answers to these questions:
1. What is a furnace? 2. What does the design of the furnace depend upon? 3. What is the design of a satisfactory furnace based upon?
4. What is the ignition temperature?
5. What is turbulence?
6. What conditions is the required furnace volume dependent upon?
7. What kinds of furnaces do you know?
The design of the furnace depends considerably upon the fuel to be burned. On the other hand, it also depends upon the supplement equipment so that satisfactory ignition and heat release may be ensured.
A furnace is a gas-tight and well-insulated space, in which gas, oil or pulverized coal may be burned. If combustion is to be complete, the combustible gases must be brought into close contact with oxygen. Also, the oxygen must be kept to a minimum and the excess air from room temperature to chimney-gas temperature also is to be low. The design of a satisfactory furnace is based upon the "three T's of combustion": temperature, turbulence, and time.
For each particular fossil fuel, there is a minimum temperature, known as the ignition temperature, below which the combustion of that fuel in the correct amount of air will not take place. If the combustible gases are cooled below the ignition temperature, they will not burn, regardless of the amount of oxygen present. A furnace must therefore be large enough and be maintained at a high enough temperature to permit the combustible gases to burn before they are cooled below the ignition temperature. Thus, the principle function of the furnace is to provide space in which the fuel may be burnt with a minimum amount of excess air and with a minimum loss due to the escape of unburned fuel.
Turbulence plays an important role in combustion. It is the turbulence that gives an effective combustion. Violent mixing of oxygen with the combustible gases in a furnace increases the rate of combustion, shortens the flame, reduces the required furnace volume, and decreases the chance that combustible gases will escape from the furnace without coming into contact with the oxygen necessary for their combustion.
Since combustion is not instantaneous, time must be provided for the oxygen to find and react with the combustible gases in the furnace.
In burning fuels such as gas, oil, or pulverized coal, the incoming fuel-air mixture must be heated above the ignition temperature by radiation from the flame or hot walls of the furnace. Since gaseous fuels are composed of molecules, they burn very rapidly when thoroughly mixed with oxygen at a temperature above the ignition temperature.
The required furnace volume is dependent upon the kind of fuel burnt, the method of burning the fuel, the quantity of excess air in the furnace, and the effectiveness of furnace turbulence. The shape of the furnace depends upon the kind of fuel burnt, the supplement equipment, and the type of boiler used to absorb the energy if the fuel is burnt for steam generation. There are different kinds of furnaces, namely, cyclone furnaces (crushed coal), pulverized coal furnaces, spreader stokers and chain-and traveling - grade stokers.
Group any words which go together.
Find in the text the English equivalents to the following phrases.
Значительно зависит от, с другой стороны, также, несмотря на, в связи с этим, таким образом, благодаря утечке, так как, такой как.
Give the Russian equivalents of the phrases below.
the supplement equipment, satisfactory ignition, heat release, gas-tight, fuel-burning equipment, pulverized coal, the excess air, chimney-gas temperature, fossil fuel, ignition temperature, if combustion is to be complete, combustible gases, to shorten the flame, instantaneous, fuel-air mixture, steam generation.
Which words in this box are not connected with the theme of the text.
Tick the statements which are true.
1. The design of the furnace doesn't depend upon the fuel to be burned.
2. A furnace is a gas-tight and well-insulated space, in which gas, oil, or pulverized coal may be burnt.
3. The design of a satisfactory furnace is based upon the "three T's of combustion": temperature, turbulence, and time.
4. For each particular fossil fuel, there is a maximum temperature, known as the ignition temperature, below which the combustion of that fuel in the correct amount of air will not take place.
6. If the combustible gases are cooled below the ignition temperature, they will burn.
7. Violent mixing of oxygen with the combustible gases in a furnace increases the rate of combustion.
8. The shape of the furnace depends upon the kind of fuel burnt, the method of burning the fuel, the quantity of excess air in the furnace.
Work in pairs. Discuss some common features of industrial furnaces.
A furnace or direct fired heater is equipment used to provide heat for a process or can serve as reactor which provides heats of reaction. Furnace designs vary as to its function, heating duty, type of fuel and method of introducing combustion air. However, all furnaces have some common features.
Fuel flows into the burner and is burnt with air provided from an air blower. There can be more than one burner in a particular furnace which can be arranged in cells which heat a particular set of tubes. Burners can also be floor mounted, wall mounted or roof mounted depending on design. The flames heat up the tubes, which in turn heat the fluid inside in the first part of the furnace known as the radiant section. In the chamber where combustion takes place, known as the firebox, the heat is transferred mainly by radiation to tubes around the fire in the chamber. The heating fluid passes through the tubes and is thus heated to the desired temperature. The gases from the combustion are known as flue gases. After the flue gas leaves the firebox, most furnace designs include a convection section where more heat is recovered before venting to the atmosphere through the flue gas stack. (HTF=Heat Transfer Fluid. Industries commonly use their furnaces to heat a secondary fluid with special additives like anti-rust and high heat transfer efficiency. This heated fluid is then circulated round the whole plant to heat exchangers to be used wherever heat is needed instead of directly heating the product line as the product or material may be volatile or prone to cracking at the furnace temperature.)
|duty – мощность||anti – rust - против ржавчины|
|сell – отсек, камера||product line – поточная линия|
|firebox – топка||prone – склонный|
|vent – выпускать||cracking – образования трещин|
|stack – дымовая труба||volatile - летучий|
Work in groups. Scan the text and find information about the main function of the stack damper. Describe principle of its operation, using the diagram.
1. to release освобождать 2. to ensure обеспечивать, гарантировать 3. gas-tight газонепроницаемый 4. to pulverize распылять, размельчать 5.ignition воспламенение 6. combustion горение 7. correct соответствующий, правильный 8. regardless of несмотря на 9. to maintain ... [читать подробенее]