2 Process flow diagram description
A 10-MW small-scale biomass power plant under construction in Indonesia was simulated. The overall process consists of a shredding process, a drying process, a boiler, and a steam cycle (Figure 1). The amount of dried EFB to generate 10-MW will be less than raw-EFB, since the dried EFB increase the heating value and boiler efficiency. In other words, simulation was designed to vary the amount of EFB to 10-MW power generation. The process flow proceeds as follows.
1. EFB of 60% moisture content is finely crushed by shredder to 5mm size, Moisture content is lowered to 48%. EFB at 48% moisture content enters the hot air rotary dryer.
2. The air entering the rotary dryer rises the temperature by heat exchange with part of the steam coming out of the turbine. The heated air comes into direct contact with the EFB and the inside of the dryer, and moisture is evaporated through the material and heat exchange, reducing the moisture content of the EFB to 20%. Air and EFB are supposed to ideally mix well. The steam(191 ° C, 12atm) used for drying is fully condensed (188 ° C, 12atm) after preheating the air and the condensed water enters the Boiled Feed Water Tank (BFWT) to preheat the water.
3. The dried EFB enters the boiler and burns and the flue gas is discharged at 200 degrees Celsius. The heat generated by the burning of the EFB results in a steam of 433 degrees Celsius 60 atm.
4. The high-temperature and high-pressure steam is discharged at 0.107 atm after turning the turbine and produces 10 MW of electricity. A portion of the steam coming out of the turbine extraction valve is used for drying. The VLP discharged at 0.107atm recirculates the steam cycle when it is fully condensed by the condenser.
2.1 properties of EFB
As the results of industrial and elemental analyzes are required to model the biomass combustion reaction in Aspen Plus, industrial and elemental analyzes were conducted on EFB. (Fig. 2) If we know the water content of EFB and the high calorific value at that time, The high calorific value according to the water content can be estimated by AspenPlus (Figure 3) Estimation of the high calorific value according to the remaining water content using AspenPlus is very similar to the experimental value. Also, when the constant water content is exceeded, black out area where EFB does not burn occurs. [Consider the quotation]