Development and testing of a high efficiency advanced coal combustor: Phase 3, industrial boiler retrofit. Quarterly technical progress report number 12, July 1, 1994--September 30, 1994

The objective of this project is to retrofit the previously developed High Efficiency Advanced Coal Combustor (HEACC) to a standard gas/oil designed industrial boiler to assess the technical and economic viability of displacing premium fuels with microfine coal. During this reporting period, data reduction/evaluation and interpretation from the long term four hundred hours Proof-of-Concept System Test under Task 3 were completed. Cumulatively, a total of approximately 563 hours of coal testing was performed with 160 hrs on 100% coal and over 400 hours with co-firing coal and gas. The primary objectives of this testing were to: (1) obtain steady state operation consistently on 100% coal; (2) increase carbon conversion efficiency from 95% to the project goal of 98%; and (3) maintain NOx emissions at or below 0.6 lbs/MBtu. The following specific conclusions are based on results of coal-fired testing at Penn State and the initial economic evaluation of the HEACC system: a coal handling/preparation system can be designed to meet the technical requirements for retrofitting microfine coal combustion to a gas/oil-designed boiler; the boiler thermal performance requirements were met; the NOx emission target of was met; combustion efficiencies of 95% could be met on a daily average basis, somewhat below the target of 98%; the economic playback is very sensitive to fuel differential cost, unit size, and annual operating hours; continuous long term demonstration is needed to quantify ash effects and how to best handle ashes. The following modifications are recommended prior to the 1,000 hour demonstration phase testing: (1) coal feeding improvements--improved raw coal/storage and transport, installation of gravimetric feeder, and redesign/installation of surge bin bottom; (2) burner modification--minor modification to the tip of the existing HEACC burner to prevent change of flame shapes for no apparent reason