Crushed coal from 1.6 mm to 6 mm is injected into the bed by means of an ________.
A ) elevator
B ) air-stream
C ) injector
D ) pulverizer
Answer: B
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3rd Class B1
- Only some of the firetubes in firetube boilers are:
- Boiler tubes may be fabricated in a _________ form, or they may be welded.
- To form a drum or shell of the required diameter, the plates must be rolled to the correct _________.
- Boiler tubes are sometimes welded to _____, which have already been welded to the headers or drum.
- Directly after rolling and while the tube is still hot, a reeling machine shown in Fig. 14 smooths the outer surface. This is called __________.
- _______ boilers must be built or put together in the field (field erected).
- In the field, the stress relieving of welded pipe joints may be accomplished by means of __________ induction coils, which are wrapped around the welded section of the pipe.
- The ASME Code Section __ specifies that the size of an elliptical manhole shall not be less than 280 mm by 380 mm or 250 mm by 410 mm.
- Postweld heat treatment, often called stressrelieving, consists of heating the welded parts uniformly, to a temperature sufficient to relieve most of the stresses created by the heat from the welding. The parts are then cooled at a constant rate.
- Drum manhole openings may be elliptical or _____.
- The gaskets used are the woven type for pressures up to _____ kPa and the metallic type for higher pressures.
- The drum is used as the major anchor point for other boiler components, and for this reason, accurate location is important.
- Coal pulverizers must be installed _____ to allow installation of coal piping to the boiler.
- The _________ steel carries the weight of the steam drum and the major pressure components.
- Large quantities of ______ are used to complete the foundations, which must support the loads from the boiler and all of the auxiliary equipment.
- The covers fit on the ______ of the drum and are held in place by means of bolts and yoke pieces.
- The boiler tubes themselves are used to support the top _____ in a bottom-supported boiler.
- The use of a membrane or water-cooled walls has reduced the use of __________ in modern water tube boilers.
- Tubes for boiler application are either hot-finished, or _____ -drawn depending on the size, tolerance, and finish desired.
- Another method used to produce seamless tubes is known as ________.
- Nozzles and stubs for connecting the drum to tubes and piping are formed by _____ forging from a solid steel cylinder, or "billet".
- Upon completion of the structural steel installation, the "U" shaped hangers are attached to the structural steel for support of the main steam ______.
- A final test which is carried out in the manufacturer's shop is a hydraulic or hydrostatic test, (conducted according to the ASME Code Section I, PW-54), at a pressure of ____ times the design pressure.
- What is meant by the foundation of a boiler?
- For pressures up to ______ and temperatures up to 454°C, handhole covers with gaskets are used and are bolted into place.