Biomass Fired Boiler is mostly single drum horizontal biomass fuel boiler with inclined reciprocating grate. Southeast Asia is rich in forestry resources, so wood veneer, sawdust and palm fiber from local wood board mill and palm oil mill are all good biomass fuels. In 2019, one Thailand energy company purchased 45t/h biomass boiler burning wood chip and palm fiber (10MW biomass power plant). The final design is high-temperature and high-pressure reciprocating grate boiler.
Main design parameters of the biomass fired boiler
Rated evaporation capacity: 45t/h
Rated steam pressure: 10MPa
Superheated steam temperature: 540C
Thermal efficiency: 86.4%
Feed water temperature: 210C
Exhaust flue gas temperature: 150C
Fuel: 70% wood chip + 30% palm fiber
Table 1: Fuel ultimate analysis
| Item | Unit | Wood chip | Palm fiber |
| C | % | 31.05 | 17.06 |
| H | % | 3.23 | 1.513 |
| O | % | 21.45 | 8.602 |
| N | % | 0.303 | 0.62 |
| S | % | 0.034 | 0.025 |
| A | % | 0.77 | 2.44 |
| M | % | 43.16 | 69.74 |
| V | % | 87.99 | 86.27 |
| Q | kJ/kg | 9697 | 3952 |
Main structure of the biomass fired boiler
The biomass fired boiler is of outdoor arrangement natural circulation single drum type. The furnace and superheater are suspended, and the tail flue duct is supporting structure. The lower part of front furnace wall is with a feeding port, and the reciprocating grate organizes the combustion. Superheaters are in three stages: high-temperature superheater, low-temperature superheater and low-temperature superheater, and also two-stage spray desuperheaters. The economizers are high temperature economizer and low temperature economizer, and air preheater is in two stages. Main feed water pipeline is DN80, with stop valve and electric regulating valve. The lower header of water wall and economizer as well as the drum are all with blowdown valves. The superheated steam outlet header is with safety valve, pressure gauge, vent pipe, backwashing pipe, thermometer, thermocouple socket, etc. The drum is with safety valve, pressure gauge, water level gauges, self-use steam pipe, dosing pipe and emergency discharge pipe.
