Saturation, inlet, tubes, outlet, drums, safety valve, uptake, headers

1. The seamless tubes are rolled into the ….

2. The steam is heated above the temperature of … corresponding to the pressure.

3. If the steam pressure rises above the safe minimum, the … should open.

4. The multi-loop type superheater is installed in the lower part of the ….

5. The tubes are connected to the steam … header and to the superheater … header.

6. The diameter of superheater … varies from 1 to 2 in.

7. The boiler … are designed for a certain maximum working pressure.

3. Answer the questions:

1. Why is a superheater an essential part of the modern marine boiler?

2. What steam is said to be superheated?

3. What types of superheaters do you know?

4. Where are convention type superheaters placed?

5. Where are radiant type superheaters placed?

6. Where are multi-loop type superheaters installed?

7. What does the convection type superheater consist of?

8. Speak about the tube size and operating temperatures.

9. Can you describe multi-loop type superheaters?

10. Why must all superheaters have one or more safety valves?

TEXT C

THE ECONOMIZER

The economizer is a feed-water heater in which flue gases are used as a heating medium. It is used to increase the temperature of feed water before it enters the boiler, by absorbing heat from the flue gases leaving the boiler.

The economizer is interposed between the boiler and stack. The economizer increases boiler efficiency, it lowers the temperature of the exhaust gases and heats up the incoming feed water as it passes through the economizer on its way to the steam drum.

A typical economizer consists of two or more solid-forged mild steel headers, to which series of tubes are connected. The tubes are rolled into the headers. When headers are not employed, return bends, usually connected by flange joints to the straight run of tubing, are used. The steel tubes range from 1 to 2 in. in diameter.

Economizers are parallel or counterflow – parallel when the gases and water flow in the same direction; counterflow when they flow in opposite directions. The counterflow is considered to be more effective, resulting in a greater heat transfer.

Air vents must be provided for the release of air when filling the economizer, or when raising steam. Drain valves fitted to the lower headers enable the economizer to be emptied of water when required.

Efficient soot blowing arrangements must be provided to keep the heat exchange surfaces free from soot. This is important not only in the interests of efficiency, but also to reduce the possibility of an uptake fire starting in sooty deposits.

Vocabulary

flue gases топочные газы

absorb, v поглощать

interpose, v располагать между

stack, n дымовая труба

efficiency, n коэффициент полезного действия, КПД

uptake, n дымоход

solid-forged цельнокованый

header, n коллектор

return bend обратное колено

flange joint фланцевое соединение

counterflow, n противоток; противоточный

drain valve спускной дренажный клапан

soot blowing arrangement сажеобдувочное устройство

deposit, nотложение

Дата добавления: 2015-03-29