Rice husk boiler is another name for rice hull boiler and rice chaff boiler. Rice husk is the hard protecting coating on a seed or grain of rice. It is a major by-product of the rice mill and agro-based biomass industry.
I. Rice husk boiler design parameter
Model: SZL10-2.5/400-SW
Capacity: 10t/h
Steam pressure: 2.5MPa
Steam temperature: 400C
Feed water temperature: 105C
Design fuel: rice husk
Fuel element analysis: C=37.74%, H=4.36%, O=28.62%, N=0.41%, S=0.04%, A=15.97%, W=12.86%, V=57.6%, Q=13055kj/kg.
II. Combustion mode
The biomass boiler burning rice husk adopts a duel mode of chamber combustion plus layer combustion. The combustion equipment includes the rice husk spraying device and chain grate. The bulk specific weight is about 120kg/m3, water content is around 8-15%, which is not good for sufficient burning.
There are two rice husk spraying devices on the lower front wall of furnace, the combustion chamber is rectangular. High thermal load promotes the ignition and combustion of rice husk. The spraying mouth is about 3m above the chain grate, and the rice husk is sprayed into the furnace. The rice husk is heated and dried during the flying tour, in a suspended combustion state. The unburnt rice husk falls on the grate and is burnt out.
III. Structure
This rice hull boiler is a double drum longitudinal layout water tube boiler. Front arch is in the front water wall, rear arch is in the upper rear water wall, while convection superheater and tail heating area are in the convection flue duct.
1. Furnace and water wall: water wall tube of Φ51×3 is surrounding the furnace. Upper drum diameter is Φ950mm, lower drum diameter is Φ944mm, and the center distance is 3m.
2. Superheater: superheater contains 24 pcs of coiled pipes of Φ38×3.5, and the heating area is 37m2.
3. Economizer and air preheater: economizer is cast iron tube of Φ56, air preheater is vertical tube of Φ40×1.5. Economizer heating area is 70.8m2, while air preheater heating area is 306m2.
4. Soot blower: soot blower is in convection tube, economizer and air preheater, which ensures good heat transfer effect.
IV. Rice Hull Boiler Operation parameter
Main parameter Design value Test value
Capacity (t/h) 10 10.3
Steam pressure (MPa) 2.5 2.48
Steam temperature (C) 400 397
Feed water temperature (C) 105 104.3
Fuel heating value (kj/kg) 13055 13105
Fuel consumption (kg/h) 2565 2632
Thermal efficiency (%) 83.8 84.1
Flue gas temperature (C) 158 156
Ash carbon content (%) 5 4.8
