Task 3.0: Advanced power systems. Semi-annual report, April 1--June 30, 1993

A variety of activities are incorporated into the Advanced Power Systems program. Tasks included are (1) fuel utilization properties, (2) pressurized combustion, (3) catalytic gasification, and (4) hot-gas cleanup. ATRAN is stochastic and combines initial coal inorganics in a random manner in order to predict the resulting fly ash particle size and composition. ASHPERT, is an expert system yielding a first-order estimate of fly ash size and composition. Both models are designed to emulate pulverized-coal combustion. Input data required include identity, chemistry, size, quantity, and mineral-to-coal associations. The pressurized combustion task has focused on the construction of a versatile reactor system to simulate pressurized fluidized-bed combustion. Both castable and monolithic refractories have been investigated in determining slag prevention under a variety of conditions. Catalytic gasification coupled with a molten carbonate fuel cell offers an extremely efficient and environmentally sound power generating system using coal. Work with an Illinois No. 6 bituminous coal has not been successful. Continued efforts will focus on using the more reactive low-rank coals to try to achieve this goal. Hot-gas cleanup is the critical issue in many of the proposed advanced power system operations on coal. The key to successful ash removal is an understanding of the properties of the ash to be collected as well as the interactions of this material with the barrier itself. The knowledge base under development will assist in assessing many of these barrier material issues for a variety of coal ashes

JV 58-Effects of Biomass Combustion on SCR Catalyst

A portable slipstream selective catalytic reduction (SCR) reactor was installed at a biomass cofired utility boiler to examine the rates and mechanisms of catalyst deactivation when exposed to biomass combustion products. The catalyst was found to deactivate at a much faster rate than typically found in a coal-fired boiler, although this may have been the result of high ash loading rather than a general property of biomass combustion. Deactivation was mainly the result of alkali and alkaline-earth sulfate formation and growth in catalyst pores, apparently caused by alkaline-earth ash deposition on or near the pore sites. The high proportion of biomass in the fuel contributed to elevated levels of alkali and alkaline-earth material in the ash when compared to coal ash, and these higher levels provided more opportunity for sulfate formation. Based on laboratory tests, neither catalyst material nor ammonia contributed measurably to ash mass gains via sulfation. A model constructed using both field and laboratory data was able to predict catalyst deactivation of catalysts under subbituminous coal firing but performed poorly at predicting catalyst deactivation under cofiring conditions. Because of the typically higher-than coal levels of alkali and alkaline-earth elements present in biomass fuels that are available for sulfation at typical SCR temperatures, the use of SCR technology and biomass cofiring needs to be carefully evaluated prior to implementation

EERC Center for Biomass Utilization 2005

Biomass utilization is one solution to our nation’s addiction to oil and fossil fuels. What is needed now is applied fundamental research that will cause economic technology development for the utilization of the diverse biomass resources in the United States. This Energy & Environmental Research Center (EERC) applied fundamental research project contributes to the development of economical biomass utilization for energy, transportation fuels, and marketable chemicals using biorefinery methods that include thermochemical and fermentation processes. The fundamental and basic applied research supports the broad scientific objectives of the U.S. Department of Energy (DOE) Biomass Program, especially in the area of developing alternative renewable biofuels, sustainable bioenergy, technologies that reduce greenhouse gas emissions, and environmental remediation. Its deliverables include 1) identifying and understanding environmental consequences of energy production from biomass, including the impacts on greenhouse gas production, carbon emission abatement, and utilization of waste biomass residues and 2) developing biology-based solutions that address DOE and national needs related to waste cleanup, hydrogen production from renewable biomass, biological and chemical processes for energy and fuel production, and environmental stewardship. This project serves the public purpose of encouraging good environmental stewardship by developing biomass-refining technologies that can dramatically increase domestic energy production to counter current trends of rising dependence upon petroleum imports. Decreasing the nation’s reliance on foreign oil and energy will enhance national security, the economy of rural communities, and future competitiveness. Although renewable energy has many forms, such as wind and solar, biomass is the only renewable energy source that can be governed through agricultural methods and that has an energy density that can realistically compete with, or even replace, petroleum and other fossil fuels in the near future. It is a primary domestic, sustainable, renewable energy resource that can supply liquid transportation fuels, chemicals, and energy that are currently produced from fossil sources, and it is a sustainable resource for a hydrogen-based economy in the future

EERC Center for Biomass Utilization 2006

The Center for Biomass Utilization (CBUî) 2006 project at the Energy & Environmental Research Center (EERC) consisted of three tasks related to applied fundamental research focused on converting biomass feedstocks to energy, liquid transportation fuels, and chemicals. Task 1, entitled Thermochemical Conversion of Biomass to Syngas and Chemical Feedstocks, involved three activities. Task 2, entitled Crop Oil Biorefinery Process Development, involved four activities. Task 3, entitled Management, Education, and Outreach, focused on overall project management and providing educational outreach related to biomass technologies through workshops and conferences

REDUCING POWER PRODUCTION COSTS BY UTILIZING PETROLEUM COKE

Petroleum coke, a byproduct of the petroleum-refining process, is an attractive primary or supplemental fuel for power production primarily because of a progressive and predictable increase in the production volumes of petroleum coke (1, 2). Petroleum coke is most commonly blended with coal in proportions suitable to meet sulfur emission compliance. Petroleum coke is generally less reactive than coal; therefore, the cofiring of petroleum coke with coal typically improves ignition, flame stability, and carbon loss relative to the combustion of petroleum coke alone. Although petroleum coke is a desirable fuel for producing relatively inexpensive electrical power, concerns about the effects of petroleum coke blending on combustion and pollution control processes exist in the coal-fired utility industry (3). The Energy & Environmental Research Center (EERC) completed a 2-year technical assessment of petroleum coke as a supplemental fuel. A survey questionnaire was sent to seven electric utility companies that are currently cofiring coal and petroleum coke in an effort to solicit specific suggestions on research needs and fuel selections. An example of the letter and survey questionnaire is presented in Appendix A. Interest was expressed by most utilities in evaluating the effects of petroleum coke blending on grindability, combustion reactivity, fouling, slagging, and fly ash emissions control. Unexpectedly, concern over corrosion was not expressed by the utilities contacted. Although all seven utilities responded to the question, only two utilities, Northern States Power Company (NSP) and Ameren, sent fuels to the EERC for evaluation. Both utilities sent subbituminous coals from the Power River Basin and petroleum shot coke samples. Petroleum shot coke is produced unintentionally during operational upsets in the petroleum refining process. This report evaluates the effects of petroleum shot coke blending on grindability, fuel reactivity, fouling/slagging, and electrostatic precipitator (ESP) fly ash collection efficiency

Development of fireside performance indices, Task 7.33, Development of methods to predict agglomeration and deposition in FBCS, Task 7.36, Enhanced air toxics control, Task 7.45

The Energy & Environmental Research Center (EERC) has been developing advanced indices that rank coals according to their fouling and slagging propensity in utility boilers. The indices are based on sophisticated analytical techniques for identifying and quantifying coal inorganics and are useful in predicting the effects of proposed operational changes on ash deposition in coal-fired boilers. These indices are intended to provide an economical way to reduce the amount of full-scale testing needed to determine the best means of minimizing ash-related problems. The successful design and operation of the fluidized-bed combustor requires the ability to control and mitigate ash-related problems. The major ash-related problems in FBC are agglomeration of bed material, ash deposition on heat-transfer surfaces, ash deposition on refractory and uncooled surfaces, corrosion, and erosion. The focus of the Development of Methods to Predict Agglomeration and Deposition in FBCs is on the agglomeration and deposition problems in atmospheric bubbling and circulating beds. The 1990 Clean Air Act Amendments require study of air toxic emissions from coal combustion systems. Since most of the toxic metals present in coal will be in particulate form, a high level of fine-particle control appears to be the best approach to achieving a high level of air toxics control. However, over 50% of mercury and a portion of selenium emissions are in vapor form and are not typically collected in particulate control devices. Therefore, the goal of this project is to develop methods that capture the vapor-phase metals while simultaneously achieving ultrahigh collection efficiency of particulate air toxics

BARRIER ISSUES TO THE UTILIZATION OF BIOMASS

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

Task 3.0 -- Advanced power systems: Subtask 3.18 -- Ash behavior in power systems. Semi-annual report, June 1--December 31, 1997

Advanced power systems such as integrated gasifier combined cycle systems and fluidized bed systems are at the forefront of power industry research because of the need for increased efficiency and the reduction of greenhouse gases. Ash behavior in power systems can have a significant impact on the design and performance of these systems. The Energy and Environmental Research Center (EERC) has developed a focused research initiative aimed at filling gaps in the understanding of fundamental mechanisms of ash behavior, which has relevance to commercial application and marketable products associated with advanced power systems. This program develops methods and means to better understand and mitigate adverse coal ash behavior in advanced power systems and can act to relieve the US reliance on diminishing recoverable oil resources and other greenhouse-producing fossil fuels. Subtask 3.18 is structured as three tasks. Task 1 pertains to summarizing the critical issues in ash behavior, especially for advanced power systems. Task 2 focuses on fundamental ash sintering and viscosity-ash composition relationships that are critical for developing a better mechanistic understanding of ash deposit formation and for predicting ash behavior. Task 3 is aimed primarily at determining the role of the ash chemistry and phase relationships for specific ash interactions in advanced power systems. The role of sulfides in the formation of ash deposits in gasification systems and the factors that influence alloy corrosion in supercritical boilers will be specifically analyzed. Task results to date are presented

BARRIER ISSUES TO THE UTILIZATION OF BIOMASS

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 with biomass fuels compared to design fuel, vaporizing alkali and chlorides which then condense on rear walls and heat exchange tube banks in the convective pass of the boiler, 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