Coal-water slurry fuel combustion testing in an oil-fired industrial boiler. Semi-annual technical progress report, February 15--September 15, 1995

Abstract

A coal-water slurry fuel (CWSF) program is being undertaken to determine if CWSFs prepared from cleaned coal (containing approximately 3.5 wt.% ash and 0.9 wt.% sulfur) can be burned effectively in a heavy fuel oil-designed industrial boiler without adverse impact on boiler rating, maintainability, reliability, and availability. Information will also be generated to help in the design of new systems specifically configured to fire these clean coal-based fuels. The project consists of four phases: (1) design, permitting, and test planning, (2) construction and start up, (3) demonstration and evaluation (1,000-hour demonstration), and (4) expanded demonstration and evaluation (installing a CWSF preparation circuit, conducting an additional 1,000 hours of testing, and installing an advanced flue gas treatment system). The boiler testing and evaluation will determine if the CWSF combustion characteristics, heat release rate, fouling and slagging behavior, corrosion and erosion tendencies, and fuel transport, storage, and handling characteristics can be accommodated In a boiler system designed to fire heavy fuel oil. In addition, the proof-of-concept demonstration will generate data to determine how the properties of a CWSF and its parent coal affect boiler performance. The economic factors associated with retrofitting boilers will also be evaluated. The first three phases have been completed and the combustion performance of the burner that was provided with the boiler did not meet performance goals. A maximum coal combustion efficiency of 95% (target is 98%) was achieved; however, natural gas cofiring was necessary to maintain a stable flame. Consequently, the first demonstration was terminated after 500 hours. The second demonstration (Phase 4) will be conducted after a proven CWSF-designed burner is installed on the boiler. Prior to starting the second demonstration, a CWSF preparation circuit was constructed to provide flexibility in CWSF production.