BARRIER ISSUES TO THE UTILIZATION OF BIOMASS

Folkedahl, Bruce C. ; Schmidt, Darren D. ; Weber, Greg F. ; Zygarlicke, Christopher J.

National Energy Technology Laboratory (U.S.)

关键词: Stokers;    Biomass;    Chlorides;    Hydroxides;    01 Coal, Lignite, And Peat;   

DOI  :  10.2172/791079
RP-ID  :  FC26-00NT41014--02
RP-ID  :  FC26-00NT41014
RP-ID  :  791079

美国|英语

来源: UNT Digital Library

【 摘 要 】

The Energy & Environmental Research Center (EERC) is conducting a project to examine the fundamental issues limiting the use of biomass in small industrial steam/power systems in order to increase the future use of this valuable domestic resource. Specifically, the EERC is attempting to elucidate the ash-related problems--grate clinkering and heat exchange surface fouling--associated with cofiring coal and biomass in grate-fired systems. Utilization of biomass in stoker boilers designed for coal can be a cause of concern for boiler operators. Boilers that were designed for low volatile fuels with lower reactivities can experience damaging fouling when switched to higher volatile and more reactive lower-rank fuels, such as when cofiring biomass. Higher heat release rates at the grate can cause more clinkering or slagging at the grate because of higher temperatures. Combustion and loss of volatile matter can start too early for biomass fuels compared to the design fuel, vaporizing alkali and chlorides which then condense on rear walls and heat exchange tube banks in the convective pass of the stoker, causing noticeable increases in fouling. In addition, stoker-fired boilers that switch to biomass blends may encounter new chemical species such as potassium sulfates and various chlorides, in combination with different flue gas temperatures because of changes in fuel heating value which can adversely affect ash deposition behavior. The goal of this project is to identify the primary ash mechanisms related to grate clinkering and heat exchange surface fouling associated with cofiring coal and biomass--specifically wood and agricultural residuals--in grate-fired systems, leading to future mitigation of these problems. The specific technical objectives of the project are: Modification of an existing EERC pilot-scale combustion system to simulate a grate-fired system; Verification testing of the simulator; Laboratory-scale testing and fuel characterization to determine ash formation and potential fouling mechanisms and to optimize activities in the modified pilot-scale system; and Pilot-scale testing in the grate-fired system. The resulting data will be collected, analyzed, and reported to elucidate ash-related problems during biomass-coal cofiring and offer a range of potential solutions.