Biomass as Fuel in Small Boilers (PDF 6.4 - APO Asian Productivity ...
Biomass as Fuel in Small Boilers (PDF 6.4 - APO Asian Productivity ...
Biomass as Fuel in Small Boilers (PDF 6.4 - APO Asian Productivity ...
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<strong>Biom<strong>as</strong>s</strong> <strong>as</strong> <strong>Fuel</strong> <strong>in</strong> <strong>Small</strong> <strong>Boilers</strong><br />
Table 5-1 Selection criteria for boiler retrofit<br />
S.<br />
No<br />
Type of<br />
Boiler<br />
1. Vertical fire<br />
tube small<br />
boiler up to<br />
1 Tons/hr<br />
capacity<br />
2. Stationary<br />
grate coalfired<br />
water<br />
tube boilers<br />
up to 5 Tons/<br />
hr capacity<br />
3. Oil-fired fire<br />
tube package<br />
boiler<br />
4. Cha<strong>in</strong> grate<br />
spreader<br />
stocker coalfired<br />
boiler<br />
Furnace<br />
Selection for<br />
Retrofit<br />
Stationary<br />
and step grate<br />
furnace<br />
Stationary<br />
grate,<br />
spreader<br />
stocker,<br />
fluidized bed<br />
Step or<br />
suspension<br />
grate external<br />
furnace<br />
Spreader<br />
stocker<br />
suspension<br />
fir<strong>in</strong>g<br />
- 36 -<br />
Remarks<br />
• Mostly coal is used <strong>in</strong> this type<br />
of boiler. In the same stationary<br />
grate, wood can be burned, and<br />
there will be little de-aeration <strong>in</strong><br />
steam generation capacity.<br />
• For rice husk-type biom<strong>as</strong>s,<br />
external step grate furnace is<br />
recommended.<br />
• <strong>Biom<strong>as</strong>s</strong> hav<strong>in</strong>g large sized pieces<br />
can be e<strong>as</strong>ily burned <strong>in</strong> stationary<br />
grate.<br />
• <strong>Biom<strong>as</strong>s</strong> of f<strong>in</strong>e particles such <strong>as</strong><br />
rice husk/sawdust can be used<br />
for suspension fir<strong>in</strong>g. Furnaces<br />
should have sufficient combustion<br />
volume.<br />
• For uniform and small sized<br />
biom<strong>as</strong>s, a fluidized bed furnace is<br />
one of the most efficient retrofits.<br />
In this system, boiler can have an<br />
efficiency level of 80±2%.<br />
• In oil-fired package boiler the<br />
combustion volume <strong>in</strong>side the<br />
boiler is the limitation. In such<br />
c<strong>as</strong>es external furnace can be<br />
designed for biom<strong>as</strong>s burn<strong>in</strong>g.<br />
Provision may be made for regular<br />
clean<strong>in</strong>g of fire tube.<br />
• <strong>Biom<strong>as</strong>s</strong> can be e<strong>as</strong>ily fed with<br />
spreader stocker <strong>in</strong> boiler furnace.<br />
Steam generation capacity of<br />
boiler will be reduced.<br />
• Major modification will be required<br />
if the same boiler is redesigned<br />
for fluidized bed combustion.<br />
Efficiency will be higher <strong>in</strong> FBC <strong>as</strong><br />
compared to spreader stocker.
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