Rice Straw/Paddy Straw as fuel in Boiler

Paddy straw is being burnt in the field of  Punjab and Haryana region as crop residue. It has gross calorific value (GCV) nearly 3000-3300Kcal//kg. If we compare it with coal as fuel for boiler some challenges have to overcome.  New boiler technology and fuel management are  required to overcome those challenges. And it is found that this is successful ,efficient  and environment friendly for power generation.

}Biomass( Rice Straw) Fired Boiler

}Comparison with Coal

}Challenges for Biomass as Fuel

}Biomass having high percentage of chlorine (.3 to 1.2%)

}High percentage of Volatile Matter (VM-48-60%)

}Ash is having high temperature corrosion properties on the boiler tube  specially super heater tubes

}Ash deposition on the Boiler tube surface

}Fuel is available in seasonal so huge storage is required

}Fuel management is also a big challenge ( fuel collection to storage to feeding to Boiler)

}Comparison of Rice straw and coal analysis

Ultimate Analysis (% bt wt)	Rice Straw	Coal
Carbon	34-37	39.27
Hydrogen	3.8-4.5	2.8
Nitrogen	0.58 -0.9	0.92
Chlorine	0.3-1.2	0
Sulphur	0.15-0.61	0.55
Oxygen	22-32	9.18
Moisture	15-27	8
Ash	14-21	39
Proximate analysis
Moisture	15-27	8
Ash	14-21	52-34
Volatile Matter	48-60	23-25
Fixed Carbon	14-28	22-26
GCV, Kcal/kg	2100-3350	3650-3890

Composition

}Ash Fusion Temperature Comparison

	IDT, DegC	HT, Deg.C	AFT, Deg.C
COAL	1180-1290	1425- 1500	1480- 1530
RICE STRAW	720	900	1040	Very Low, ash is sticky in nature and deposits on the surface of the tubes

}Chemical Composition of Ash

Composition	Coal Ash (%)	Rice Straw Ash (%)	Remarks
SiO2	37-68	54.35
Fe2O3	7.05-28	1.2
Al2O3	7.83-33	1.87
CaO	0.11-.96	4.48
MgO	0.24-1.27	4.93
TiO2	0.08-1.91	-
SO3	0.15-1.48	3.22
P2O5	0.15-2.95	0.11
K2O	0.14-.21	14.23	Due to present of present of these chemical IDT/AFT is lower in Rice straw ash
Na2O	-	7.66
Cl	-	6.27

}Fuel Collection

}Total rice straw requirement is 2laks Ton per annum for 20MW capacity of Power Plant

}100 acres of land is required to store

}100 nos of  supplier are required for collection and store the rice straw in baler form from 1lak acres of land.

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}Risk

}Fuel degradation

}Fire in fuel

}Boiler Technology

}Vibrating grate of Boiler technology

}Screw Feeders for Boiler Fuel Feeding system

}Super heater and water tube materials should be higher in grade

}Soot blowing and cleaning mechanism should be required in Furnace, Superheater and economiser zone

}Air preheater should be done by feed water

}Oxygen, CO analysers, Furnace temperatures and draft measurement instruments should work

}Fly ash collection system should work properly

}Surface area is higher side as it has four pass system

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