1. Water walls
•furnace wall that is comprised of refractory
and tubes in a water-tube boiler
•The tubes are evenly spaced and generally
connect to headers which in turn are
connected back to the main generating
bank of the boiler.

2. Boiler installation
• Simple
– Boiler is fully assembled and pretested by the
manufacturer, i.e, (an 150-hp oil burning fire-tube
boiler.)
– It is handled in one piece and slid on its own base
in a flat foundation.

3. • Complex
(large capacity unit)
– Boiler drum,superheater, water
walls,seting,trim,combustion equipment, and
control equipment are not assembled.
– These parts are transported separately by the
manufacturer.
– In some cases the manufacture’s contract includes
the installation of the boiler.

4. Furnace
• Is a chamber of combustion
• Provide support and enclosure for the
combustion equipment – burners or stokers.
• Important factors in the design of the furnace
1. Type of combustion equipment.
2. Character of the fuel used, especially its ash content
3. Draft equipment employed
4. Air supply and degree of preheating
5. Boiler and its baffling arrangement

5. Types of furnace walls
• Solid masonry
– Ranges from a single homogeneous refractory section to one
containing special insulation between refractory and casing.
– Common in small steam generating units.
• Air-cooled masonry walls
– Consists of a thin refractory section backed by an air space .
– The air is positively circulated by the furnace draft since it is desirable
to use the heated air for combistion.
• Partially water-cooled walls
– A portion of the surface are covered by water tubes.
• Water-jacketed furnace
– The combustion region is completely surrounded by heat absorbing
surface.
– Is suitable for pulverized coal firing.

6. Boiler accessories and trim
• Boiler cosists of heating surface and shell or drums.
• Trim, consists of valves and piping essential to the safe operation of
the boiler.
1. Feedwater entrance. A stop valve and a check valve, with the former
installed nearest the boiler.
2. Blow-off(water), including special valves not vulnerable to dirt in the
water.
3. Safety valves(steam) to prevent rise of steam pressure above a
predetermined limit.
4. Water column, with gauge glass, high- and low-water alarms.
5. Stop-and-check valve. This is mounted on the main steam outlet and
to it is connected to steam pipeline.
6. Steam vent. A small on the top drum normally closed by a valve,
which may be opened when it is desired to hold atmospheric
pressure in the boiler, as during initial boiling out.
7. Steam pressure guage with siphon,cock and inspector’s test cock.
8. Various special openings, in accordance with purchaser’s
requirements, for the accomodation of feedwater control elements,
reagent feed,water samplind.etc.