| OCR Text |
Show East Ohio Gas and Dover Light & Power. The approach selected by GRI and the project team included the following criteria: • Small burner throat diameter with minimum watertube penetration • High-pressure drop burner for strong penetration • Large turndown to address cofire benefits at low cofire, low capacity and high cofire, high capacity • Dual, staggered, opposed burner positioning where appropriate for strong mixing • Large turndown in stoichiometry to permit stable substoichiometric operation for in-situ reburn, using excess combustion air for burnout • Pre-retrofit engineering, including computational fluid dynamics, to position and operate burners, and evaluate cofire boiler impacts • Cofiring benefits performance analysis to identify targets and payback for each candidate application • Performance testing to quantify performance benefits and evaluate mechanisms of cofire effects on opacity, NOx formation, and slagging. COFIRING BENEFITS Conceptually, stoker cofiring produces several changes in the operating characteristics of the boiler: • Improved thermal distribution in the firebox • Improved mixing of combustion gases over the grate • Rapid thermal response to capacity changes • Reduced load on stoker for constant boiler load These operational effects directly and indirectly offer a spectrum of performance improvements. Evaluation of cofiring feasibility at numerous stoker operations has shown these performance improvements translate into a broad range of possible economic benefits. The type and magnitude of the benefits for a specific site is dependent upon several factors: • Relative coal and gas pricing; seasonal gas pricing • Coal and gas supply security 4 |
