Biomass as Fuel in Small Boilers (PDF 6.4 - APO Asian Productivity ...

Biomass as Fuel in Small Boilers
- Fuel savings = 526,800-154,280
= USD3,72,520
- Investment for purchase of new rice husk-fired boiler
= USD50,000
- Simple payback period = 1.6 months
5.3 CHECKLIST FOR ENHANCING BOILER EFFICIENCY
5.3.1 Periodic tasks and checks outside of the boiler
• All access doors and plate work should be maintained airtight with effective
gaskets.
• Flue systems should have all joints sealed effectively and be insulated
where appropriate.
• Boiler shells and sections should be effectively insulated. Is existing
insulation adequate? If insulation was applied to boilers, pipes, and hot
water cylinders several years ago, it is almost certainly too thin even if it
appears in good condition. Remember, it was installed when fuel costs were
much lower. Increased thickness may well be justified.
• At the end of the heating season, boilers should be sealed thoroughly,
internal surfaces either ventilated naturally during the summer or very
thoroughly sealed with tray of desiccant inserted. (This is only applicable to
boilers that will stand idle between heating seasons.)
5.3.2 Safety and monitoring
• Explosion relief doors should be located and/or guarded to prevent injury
to personnel.
• Safety valves should have self-draining discharge pipes terminating in a
safe location that can be easily observed.
• Installed instruments should be maintained in working order and positioned
where they can be seen easily.
• Provide test points with removable seal plugs in the flue from the boiler, to
enable flue gas combustion tests to be carried out.
• Do you check boiler combustion conditions periodically? CO2 or O2 readings
and exit temperatures can be obtained using relatively inexpensive
portable equipment. Adjusting combustion by optimizing the fuel/air ratio
costs nothing and can lead to substantial savings.
• Do you monitor exit temperatures? There should be a steady rise between
boiler flue-duct cleaning intervals, and this should not be allowed to
exceed, say, 40 ºC. Try to clean based on temperature indications, rather
than on the calendar.
- 38 -