Demonstrating Dirty Biomass Technologies
“Technology is Technology – it is replicable, transferable but best effectiveness comes with cross industry application” A year ago, one phone call for a new plant changed the mindset. The existing plant was being scrapped to set up a new project (USD 6 million). The design fuel was expensive, and the only viability was local dirty biomass. The plant operation was inefficient and under-capacity. The persuasion to scrap the consultant’s recommendations rather than the plant itself took six months, several technical discussions and biomass plant visits.
Finally, the plant has been modified with in-bed technology firing, wide space tubing, new fuel cleaning system and retrofit/ repair of worn out equipment.
The new biomass cleaning system based on density separation technology cleaned the dust, sand and stones from the biomass. The system was designed for 20% foreign matter and achieved final output of less than 1% sand fed to boiler and 100% stone removal. This also helped company control the collection and procurement process.
The in-bed firing system provided opportunity to achieve the original design capacity with large steam generation rate in the furnace. The plant achieved 100% capacity in 7 days but took about a month to stabilize primarily due to training and learning of the operation staff. The plant operates on multiple dirty biomass straw fuels – either mixed or separate.
The fluidized operations are not recommended for dirty biomass but there was no option. The plant space and limited shutdown time were major constraints. The special patented wide spacing screen panels were installed. These bolstered the steam generation capacity and provided the much-needed quick response time to changing loads. The design and installation of screen panels require precise technology as these are subjected to circulation ratio issues. Globally, very few companies can claim expertise for this. All the competitors recommended against this design.
The large spaced superheaters avoid ash deposition and bank zone is practically useless. The temperature drop across bank reduced from 100 Deg c to about 30 Deg C. The boiler outlet temperature has been reduced from 435- 445 Deg C to 355 Deg C, thereby improving the operational efficiency.
Most of the old tubes in heat recovery sections were replaced with new tubes.
Turbine and alternator was overhauled. The condenser was re-tubed to achieve the efficiency. The cooling tower was relocated to correct for air flow design errors.
The new PLC based automation and control system was introduced to have fully automatic boiler controls including the fuel feeding. The SCADA operations help management have a tight control on the critical parameters and identify the impending plant deterioration. This is resulting in quick corrective actions to maintain the achieved efficiencies.
Our belief of “Echoing technology” helped us overcome another challenge that resulted in additional 20% capacity with same fuel input (efficiency degradation reversed) at a small investment of USD 0.623 million only (Investment saving of about USD 5.3 million).[/ultimate_heading][/vc_column][/vc_row]