In Situ Measurements of Boiler Ash Deposit Emissivity and Temperature in a Pilot-Scale Combustion Facility

An instrument for in situ determination of ash deposit temperature and emissivity has been designed, assembled, calibrated, and used to characterize deposits in a coal-fired pilot-scale combustor. The temperature information has also been used to estimate the effective thermal conductivities of ash deposits. These measurements were made in the radiant section of the Pittsburgh Energy Technology Center’s pilot-scale combustion facility, the Combustion and Environmental Research Facility, which is nominally rated at 500,000 Btu/hr (145kW), for ash deposits from a Pittsburgh seam coal, an Alaskan coal, a Russian coal, and a blend of the latter two. The estimated thermal conductivities fall within the range of values reported by others; however, the deposit formed by the coal blend had a substantially higher thermal conductivity than either of the two parent coals. The in situ measurement system, which is called INSITE for In Situ Temperature and Emissivity, has been successfully operated in adverse conditions and without the need of specialized training.