Combustion Performance and Emissions Control - Program 71

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1 Combustion Performance and Emissions Control - Program 71 Program Description Program Overview Forced outages due to fireside corrosion, circumferential cracking, and deposition of ash (e.g., slagging and fouling), which in many cases are significantly exacerbated by low-no x operation, remain a costly issue. As coal plants shift to lower-cost/lower-quality coals in many instances, to take advantage of recently installed flue gas desulfurization (FGD) systems and as coal plants increase the level of combustion staging (needed to comply with more stringent NO x regulations), innovative and cost-effective solutions will be needed to maintain boiler tube reliability. As the most cost-effective means of reducing emissions from coal-fired power plants, combustion considerations should be viewed as the first step in any compliance strategy. Recent regulations, such as the Cross State Air Pollution Rule (CSAPR) and Mercury and Air Toxics Standard (MATS), will make an even stronger case to deploy cost-effective combustion-based controls for reduction of nitrogen oxides (NO x ), SO 3, mercury, and other hazardous air pollutants (HAPs), and unburned carbon. Rising fuel costs will increase the need to improve plant heat rate and combustion performance. In addition to fuel costs, heat rate improvements bear a direct relationship on tonnage releases of all pollutants, including CO 2. The three general issues addressed in the Electric Power Research Institute s (EPRI s) Combustion Performance and Emissions Control Program (P71) include combustion and fuels impacts on boiler tube life; impacts of combustion modifications and fuel quality on emissions; and plant heat rate. For all of these issues, understanding of fuel quality considerations, accurate measurement and control of coal and air flow to individual burners, and improved performance of pulverizers, burners, and other critical combustion- and performancerelated hardware is imperative. This program provides the knowledge and resources needed to develop, demonstrate, and apply cost-effective combustion-based solutions to resolve these and other combustion- and fuels-related issues. Research Value The Combustion Performance and Emissions Control program focuses on a holistic approach to combustion and fuel quality impacts, including emissions, performance, and reliability. Avoiding a single forced outage due to fireside corrosion, circumferential cracking, or slagging and fouling can save more than $1 million per unit. Heat rate improvements yield significant savings in fuel costs and are by far the lowest-cost and only commercially available method of reducing CO 2 at this point in time. A 1% heat rate improvement on a single 500-MW base-loaded unit can save as much as $1M/year in fuel costs alone, and can reduce CO 2 emissions by approximately 40,000 tons per year. Enhancing NO x reductions with cost-effective combustion modifications, even on units equipped with selective catalytic reduction (SCR) systems, may yield significant revenues in an anticipated NO x credit market. Approach Projects in three distinct groups help mitigate fireside corrosion and waterwall wastage in low-no x systems; develop and demonstrate cost-effective emissions control through combustion modifications and assessments of emerging technologies; and optimize heat rate. p. 1

2 Mitigation of the impacts of combustion and fuel quality on boiler tube life, including waterwall wastage, circumferential cracking, and slagging and fouling, will significantly reduce the number of costly forced outages. Participation in EPRI s Combustion and Fuels Impacts Interest Group (CFIG) helps members identify applicable projects, disseminate results, and share best practices regarding all aspects of the impacts of combustion and fuel quality on boiler tube life. Members also receive assistance in analysis of tube wastage, circumferential cracking, and ash deposition problems, fuel quality and blend ratio impacts, and selection of protective coating alternatives. State-of-the-art modeling tools are used to develop guidelines to assess waterwall wastage based on coal quality, furnace design, and operability. Combustion modifications may provide the most cost-effective first step in controlling a number of pollutants in addition to NO x. Development of guidelines and best practices, data from full-scale demonstrations, and assessments of emerging technologies provide important information to make informed decisions. Value to members may include the ability to capitalize on the anticipated NO x credit market and avoid higher-cost emissions controls. Solutions for fuel quality issues enhance fuel flexibility, unit reliability, and combustion performance. Members can achieve substantial cost savings through improved boiler performance, regain lost capacity, and benefit from increased flexibility in fuel sourcing. Improved heat rate can reduce the cost of operation through fuel savings and increased availability. In addition, improving heat rate is by far the most cost-effective method and the only ready now method of reducing CO 2 emissions, as well as reducing all other pollutants on a tonnage basis. Members can use project deliverables to assess and implement tools and technologies to improve plant performance and lower heat rate and CO 2 emissions. Participants in full-scale demonstrations, available to all program members, will gain firsthand experience with issues and solutions. Accomplishments For more than two decades, EPRI has led the power industry in developing, advancing, and demonstrating costeffective NOx and other emissions control technologies and best operating practices for achieving compliance at minimal cost and maximum reliability. More recently, EPRI has led the industry in identifying, quantifying, and seeking cost-effective solutions to operability and performance issues associated with low-emissions operation, such as fireside corrosion, circumferential cracking, heat rate, and fuel quality impacts. Accomplishments include: Development of the Vista model to assess the impacts of coal quality on the total cost of operation. Development of advanced models to predict and assess methods of combating fireside corrosion consequential to implementation of low-no x systems. The Flame Doctor Flame Diagnostics System, an advanced burner diagnostics tool to improve performance and reduce emissions on wall-fired and cyclone boilers. Innovative, cost-effective technologies for combustion NO x controls, such as advanced staging methods Slagging and fouling guidelines that offer quantifiable methods of identification and mitigation methods for ash deposition issues. Site evaluations for production cost optimization and boiler air in-leakage reduction, which provide participating companies the framework to apply these methods to improve plant performance at other units across their fleets. Sponsorship of workshops, conferences, and webcasts in which funders and other key industry participants can share ideas and best practices, and outline needed solutions. Combustion Performance and Emissions Control - Program 71 p. 2

3 Current Year Activities The program R&D for 2013 will continue to focus on a holistic approach to combustion optimization, including combustion and fuel quality-related impacts on emissions, performance, and operability. Specific efforts will include: Cost-effective solutions for the impacts of low-no x combustion and fuel quality on boiler tube life, such as fireside corrosion, circumferential cracking, and ash deposition. Advanced sensors and feedback loops to quantify gaseous species distributions (i.e., O 2 and CO) and enable corrective actions that optimize fuel/air distribution in the boiler. Holistic impacts of combustion modifications on all pollutants, including mercury speciation for downstream capture (with Program 75). Predictive tools to assess the impacts of coal quality, boiler design, and operation on fireside corrosion, circumferential cracking, and slagging and fouling. Guidelines, demonstrations, and conferences and workshops for improved heat rate for lower fuel costs and as a first step in minimizing CO 2. Estimated 2013 Program Funding $4.0M Program Manager Anthony Facchiano, , afacchia@epri.com Summary of Projects Project Number Project Title Description P Combustion and Fuel Impacts on Boiler Tube Longevity This project develops assessment and mitigation strategies for combustion-related boiler tube failures due to low-no x operation, such as fireside corrosion and circumferential cracking, based on coal quality, boiler design, and operational considerations. P Cost-Effective Emissions Control via Combustion Modifications P Heat Rate and Cost Optimization This project develops guidelines and best practices that enable implementation of cost-effective combustion modifications to minimize NO x levels and other pollutants such as mercury and unburned carbon, as well as optimize combustion performance. This project develops and demonstrates a variety of deliverables and services to promote optimal heat rate and minimal cost of operations, including economic evaluation of fuel quality impacts on heat rate; the effects of increased cycling and load following operation; best practices for plant performance monitoring and improvement, and conferences and workshops focused on key topics prioritized by participants. Combustion Performance and Emissions Control - Program 71 p. 3

4 P Combustion and Fuel Impacts on Boiler Tube Longevity (070555) Key Research Question Boiler system owners and operators need cost-effective solutions to reduce the number of costly forced outages stemming from fireside corrosion, circumferential cracking, slagging and fouling, and other boiler tube impacts consequential to low-no x operation and fuel quality considerations. Low-NO x operation often results in fireside corrosion and waterwall wastage-related boiler tube failures, and although weld overlays may alleviate this situation in many instances, associated problems with circumferential cracking may be exacerbated. Addressing the impacts of low-no x combustion and fuel quality on boiler tube longevity is critical to maintaining and improving unit reliability and performance. Approach EPRI's multifaceted approach to understanding and resolving the costly consequences of accelerated fireside corrosion, circumferential cracking, slagging, fouling, and other impacts of low-no x combustion and fuel quality on boiler tube longevity will include: Role of fuel properties such as chlorine, sulfur, ash compounds, and fuel blend ratios Effects of boiler design and various modes of low NO x operation; and Operational- and materials-based solutions and issues The Simple Corrosion Predictor Model, the Advanced Slagging Predictor, and other state-of-the-art modeling tools will be used to develop guidelines to assess circumferential cracking, waterwall wastage, slagging and fouling, and other operational and reliability issues based on coal quality, furnace design, and operability. Costeffective solutions will be developed and demonstrated. The issue of circumferential cracking, exacerbated both by low-no x operation and utilization of weld overlays, will be addressed, and alternative material solutions such as thermal spray and ceramic coatings will be assessed. Impact Reduce the number of costly forced outages due to fireside corrosion and circumferential cracking-related boiler tube failures. Reduce O&M costs by selecting effective protective coatings and weld overlays, as well as by taking into account coal quality considerations. Participate in EPRI s Combustion and Fuels Impacts Interest Group (CFIG), which helps members identify specific projects, disseminate results, and share best practices through meetings and/or webcasts. Receive technical assistance in all aspects of circumferential cracking, fireside corrosion, and slagging and fouling-related issues, including analysis of wastage problems, weld overlay cracking, fuel quality and blend ratio impacts, and appropriate selection of protective coating alternatives. How to Apply Results Plant personnel responsible for boiler systems reliability and performance can employ project findings and deliverables to mitigate accelerated fireside corrosion, circumferential cracking, and slagging and fouling impacts on reliability. Mitigation methods may be applied to boiler operation (especially combustion considerations), material-based coatings such as weld overlays and thermal sprays, and fuel quality. Combustion Performance and Emissions Control - Program 71 p. 4

5 2013 Products Product Title & Description Combustion Guidelines for Maximum Boiler Tube Life: and dissemination of operational guidelines, which includes all combustion and fuels aspects of boiler operation affecting boiler tube life. Dissemination may include seminars for plant engineering and O&M staffs. Impacts of Off-Specification Fuels and Blends: Continuation of the work initiated in The impacts of off-design or off-specification fuels and blends will be assessed for consequences regarding corrosion, slagging and fouling, and other operability issues through the holistic approach of the EPRI Vista analysis tool. Coating Corrosion Fatigue/Cracking Lab Testing: Lab tests will continue to assess the impacts of corrosion and thermal fatigue mechanisms, leading to the circumferential cracking phenomena on a variety of weld overlays, thermal sprays, and ceramic coatings, and deposits (e.g., reducing sulfur and chlorine species). Tests will investigate the impacts of temperature, surface roughness and defects, and new alloys, and assess crack initiation mechanisms. Advanced coating materials will be assessed. Tests will assess the impacts of a greater variety of ash deposits than used in previous years, in an effort to increase focus on the impacts of fuels and fuel blends for a given temperature and coating. Assessment of Wall Wastage, Slagging and Fouling, and NOx for Members: Member-specific fuel quality assessments using advanced predictive tools such as the Simple Corrosion Predictor, NOx LOI Predictor, and advanced slagging indices will be conducted at the request of EPRI members. Informal letter reports will be prepared for each participant. Planned Completion Date Product Type Resource Future Year Products Product Title & Description Combustion Guidelines for Maximum Boiler Tube Life: of latest findings in a format amenable to application by plant personnel. Long Term Assessment of Coatings Performance: Assessment of overlays, thermal sprays, and ceramic coatings to minimize corrosion and circumferential cracking. Correlations for Off-Spec Fuels and Blends: Advanced mechanisms to better quantify fuel impacts on slagging, corrosion, circumferential cracking. Planned Completion Date 12/31/14 Product Type Resource 12/31/14 Report 12/31/15 Report P Cost-Effective Emissions Control via Combustion Modifications (050311) Key Research Question Combustion modifications are the most cost-effective first-line approach to reducing emissions primarily NO x but also mercury and other hazardous air pollutants (HAPs), sulfur oxide (SO x ), CO, and flyash unburned carbon or loss on ignition (LOI). This project will assess emissions reductions achievable with combustion modifications by considering fuel quality, boiler design, boiler operating modes, diagnostic tools and boiler control optimization approaches, as well as constraints imposed by other site-specific factors. The consequences of candidate combustion modifications on boiler performance, reliability, and other pollutants, and steps that can be taken to minimize these impacts also will be addressed. This project also will evaluate the performance of key combustion-related hardware components, such as pulverizers, along with application of Combustion Performance and Emissions Control - Program 71 p. 5

6 advanced sensors and monitors. The impacts of coal and combustion air distribution, along with devices to measure and control coal and combustion air flow, will be assessed. Approach This project will develop guidelines and best practices that enable members to employ cost-effective combustion modifications to the fullest extent for the purpose of reducing emissions and improving reliability and performance. Activities will include: Case studies documenting combustion factors influencing achievable NO x emissions. Methods of minimizing CO and LOI without sacrifice to NOx levels or heat rate. Impacts of combustion modifications on mercury capture. Methods of improving mill performance such as throughput, particle size, and distribution, which can, in turn, improve combustion performance and emissions. Demonstration of continuous in-furnace and economizer gaseous species monitoring devices. Cost and performance optimization of combustion-based NOx controls when used in combination with selective catalytic reduction (SCR). Boiler/SCR optimization of NOx levels. Objective assessments of emerging in-furnace NO x control technologies (including field data). Assessments of devices to measure and control coal and air flow, and impacts of burner-to-burner fuel and air distribution on emissions and performance. Impact Avoid higher-cost NO x controls required to comply with present and anticipated regulations, and capitalize on NO x credit markets when economically justified. Access performance data and third-party assessments of emerging combustion-based NO x control options to help select the most appropriate technologies. Apply results of the development and demonstration of the holistic impacts of combustion modifications on control of CO, unburned carbon, mercury, sulfur trioxide (SO 3 ), and other pollutants. How to Apply Results Utility staff involved in economic assessments, applicability issues, and considerations of combustion modification-related technologies can apply project information on emerging technologies maintained in real time on the EPRI website. In addition, participants in full-scale demonstrations of advanced technologies, which are available to all project members, will gain firsthand experience with technology performance and learn about the advantages and shortcomings of emerging options compared to more established approaches Products Product Title & Description Holistic Impacts of Combustion Modifications on Emissions: This project will build on earlier efforts that assessed tradeoffs between the control of criteria pollutants (NOx, SOx, and particulates), trace toxics (mercury, selenium, organics, and others) vs. CO 2 and overall heat rate impacts. The project will document case study examples of member sites that encounter tradeoffs between emissions due to implementation of combustion modifications. Based on site-specific operational constraints, quantitative assessments will be made using available tools to support development of a methodology for identifying optimum boiler operational strategies. Planned Completion Date Product Type Combustion Performance and Emissions Control - Program 71 p. 6

7 Product Title & Description Evaluation of the Integration of Combustion Optimization Sensors with Optimization Technologies: One potential benefit of spatially resolved combustion sensors is the integration of their output into combustion controls systems in order to maintain optimized boiler operating conditions over time as well as changes in load. Based on case study examples from site-specific applications of combustion sensors, a review will be conducted of available boiler controls compared to benefits achieved. A primary objective of the evaluations is to identify the level of boiler controls required to fully respond and act upon information provided by combustion sensors. Emerging NOx Control Technologies Web Site: This project continues the Emerging Combustion NOx Control Technologies website, providing up-to-date findings, performance data, and performance impacts of all combustion-based NOx controls. Gas Co-firing Assessments: The technical and economic considerations associated with co-firing or displacing coal fuel gas in a unit designed for coal will be assessed. Issues may include required burner and other combustion systems modifications, heat distribution, and operability. Emission benefits will be quantified. Planned Completion Date Product Type Resource Future Year Products Product Title & Description Holistic Impacts of Combustion Modifications on Emissions: Quantifiable assessments of emissions tradeoffs based on earlier conducted case studies. Gas Co-firing Case Studies: Summary and correlations of performance and emissions benefits of gas co-firing, based on available data. Evaluations of Emerging NOx Control Technologies: Findings based on available data. Planned Completion Date Product Type 12/31/14 Report 12/31/14 12/31/15 P Heat Rate and Cost Optimization (051807) Key Research Question Improving heat rate can reduce the cost of operation through fuel savings, increased availability, and emissions reductions. In addition, improving heat rate is by far the most cost-effective method and the only ready now method of reducing CO 2 levels. Approach This project group will develop and demonstrate a variety of deliverables and services that promote optimal heat rate and minimal cost of operations. Specific efforts will include evaluations of methods to improve steam condenser performance; cost-benefit analyses of steam turbine modifications; improvement to fluid flow measurements; the effects of increased cycling and load-following operation; best practices for plant performance monitoring and improvement; and technology transfer vehicles such as conferences, workshops, and webcasts. In addition, participation will include membership in the Heat Rate Interest Group, where best practices, information, and prioritizing of available resources are shared. Finally, this project will house the Production Cost Optimization Interest Group, dedicated to seeking significant heat rate improvements for existing power generating facilities through cost-effective operational modifications, and significantly more improvements through more capital-intensive improvements. Combustion Performance and Emissions Control - Program 71 p. 7

8 Impact Reduce fuel costs Improve availability and emissions goals with existing hardware Realize future benefits, including reduced CO 2 emissions at costs far lower than those of post-combustion options How to Apply Results Participants can use project deliverables to assess and implement tools and technologies that improve plant performance and lower heat rate and CO 2 emissions. In addition, participants in full-scale demonstrations, which are available to all program members, can gain firsthand experience with issues and solutions. Participants can use deliverables to apply findings and best practices at their units, enabling savings in fuel costs, reduced CO 2 emissions, and increased productivity and availability Products Product Title & Description Routine Performance Test Guidelines: This project will update the current set of routine performance test guidelines based on several years of in-plant experience. Additional test guidelines will be developed in response to the needs demonstrated/requested by the industry. Methods to Mitigate the Effects of Increased Cycling and Load-Following Operation on Heat Rate: This project will build on the results of work completed in recent years to evaluate the methods used to mitigate the heat rate effects of increased load-following, using a series of field tests at sites where those methods have been employed. Improved Fluid Flow Measurements: Best practices will be identified to improve and maintain accurate fluid flow measurements in power plant settings. Some methods used by calibration labs will be explored for application in field settings. This effort will address attemperating sprays, feedwater, condensate, circulating cooling water, and other fluid flow measurements. This is a joint effort with Program 68. Evaluation of Sensor Advances to Improve Heat Rate: This project compares currently installed control systems to those available and identifies the advances required for a step-change improvement in plant heat rate. Applications of new/advanced sensors will be explored to best use the real-time operating information to improve plant heat rate. The spatial effects of sensor placement for key parameters with large effects on plant efficiency will be analyzed. Cost-Benefit Evaluation of Steam Turbine Improvements: This project will evaluate the opportunities for implementing hardware changes to improve turbine performance. In addition, the project will quantify the expected gains in heat rate, estimate any reliability changes, and compare the gains to the costs for engineering, fabrication, and installation. Improved Condenser Performance: This study will evaluate recent advances in the state-of-the-art in condenser design, resulting in applications for both retrofits and new plant condensers. Information on improved measurement and monitoring techniques will be evaluated. Planned Completion Date Product Type Combustion Performance and Emissions Control - Program 71 p. 8

9 Supplemental Projects Cyclone Boiler Performance Optimization (044771) Background, Objectives, and New Learnings Cyclone boilers represent a substantial fraction of the coal-fired boiler capacity in the United States and offer some of the lowest electricity generation costs. Production of cyclone boilers by the original equipment manufacturer ceased in the 1970s in response to the Clean Air Act and the difficulty of cost-effectively meeting NOx emission requirements under New Source Review standards. Due to shifting operating practices that have been adopted in response to recent environmental mandates, an ongoing need exists to address operational issues specific to cyclone boilers. The Cyclone Boiler Performance Optimization Group develops and demonstrates cost-effective solutions for improved operability and performance of cyclone boilers. Its research and development (R&D) fills a void in the marketplace, because no other organization currently focuses on the needs specific to cyclone boilers. Tasks that the group has adopted include establishing advanced diagnostic capabilities (for example, cyclone barrel fuel/air balance, individual cyclone barrel temperature measurement, real-time measurement of coal crusher size distribution, and unburned carbon in ash levels), which address increasingly more stringent NOx emission mandates, as well as the growing trend in spot market coal purchase. Project Approach and Summary The current project scope represents a continuation of work initiated in prior years, as well as new projects identified by project participants, with specific tasks including: Continued development of the Flame Doctor TM for application on cyclone boilers, with the goal of providing a tool for optimizing individual cyclone barrel operation. Assessment of real-time crushed coal size distribution, to enable an evaluation of factors contributing most to its variability and control. Real-time measurement of cyclone barrel temperature to provide unit operators with a diagnostic capability prior to encountering frozen slag taps. Application of tunable diode lasers to continuously monitor spatial concentration gradients of CO/O 2 to enable individual cyclone barrel tuning. Identification of maximum NOx reductions achievable with overfire air (OFA), in combination with validation of improved instrumentation capable of monitoring individual cyclone barrel operation. Projects in areas of interest identified as high priority by participating members. Benefits With collaborative research efforts focused on improving cyclone boiler operation and performance, value can be realized through improved boiler performance and operation, reduced operating costs, and a reduction in the unit forced outage rate. Combustion Performance and Emissions Control - Program 71 p. 9

10 Production Cost Optimization Phase 2: Cost-Benefit Analyses of Capital Projects (067872) Background, Objectives, and New Learnings The benefits of improved performance of coal-fired power plants continue to grow as the costs of fuels rise and carbon dioxide regulations loom on the legislative horizon. Power generating companies looking to enhance their heat rate programs to reduce production costs are invited to participate in Phase 2 of EPRI s Production Cost Optimization project. This project is Phase 2 of a two-phase project that addresses these challenges. Phase 1 of the Production Cost Optimization (PCO) Project (EPRI ) utilizes site-specific performance appraisals to identify potential improvements with the highest benefit-to-cost ratios, with the emphasis on relatively lower cost operational improvements. Phase 2 will focus on the evaluation of potential capital projects that show promise to significantly improve performance well beyond Phase 1 levels. Project Approach and Summary Phase 2 of the Production Cost Optimization Project will include a more detailed assessment of capital projects. Cost-benefit analyses will be developed for each site to identify and rank a list of projects and their projected heat rate improvements. The assessment will include production costs and potential CO 2 credits. Although potential efforts considered will be site-specific, projects will focus on significant upgrades and enhancements to the major common plant components including condensers, turbines, feedwater heaters, cooling systems, major electrical drives, and combustion systems. The site-specific completion of Phase 1 of the Production Cost Optimization Project is required before implementing Phase 2. The tasks identified below will be conducted for each participating site. Task 1 Data Request The project team will collect data from each site to conduct the analysis. Even though much of the necessary data will have been acquired during Phase 1, additional information pertaining to emission records, operations, and budgetary considerations will be needed to complete the analysis. Any information deemed proprietary will be treated appropriately. Task 2 Plant Interviews Follow-up phone interviews with plant contacts will be conducted to discuss proposed projects, plans, future operating scenarios, and condition assessment of major equipment. Benefits The benefits of heat rate reduction are substantial. Lower fuel costs directly affect the bottom line. In addition, heat rate improvement is the only commercially proven and the most cost-effective control for lowering CO 2 on the margin. All other emissions (NOx, SOx, particulates, mercury) also are lowered on a ton/mw basis. For example, a 1% heat rate reduction at a typical 500-MW plant operating at 90% capacity factor and firing bituminous coal can cut CO 2 emissions by 40,000 tons/year, which equates to $800,000 if a $20/ton CO 2 tax is implemented. The plant also will experience more than $700,000 in fuel savings (based on a fuel cost of $2/Mbtu) for the same 1% improvement in heat rate. Global climate concerns will continue to exert pressure on the existing fleet of coal-fired power plants to minimize CO 2 levels for well beyond the nominal 1% improvement goal specified in Phase 1 of the Production Cost Optimization Project. Along with the drivers of increasing fuel costs and ever-lower emission standards, global climate change concerns will mandate that the existing fleet of coal-fired power plants operate as efficiently as possible. Additional efficiency improvements may be realized, at least in part, through implementation of more site-specific, capital-intensive efforts. It s estimated that, depending on the site, a minimum of 2% to 4% improvement in heat rate may be realized through these efforts. Combustion Performance and Emissions Control - Program 71 p. 10

11 A Systematic Approach to Reduce Power Plant Auxiliary Power (072828) Background, Objectives, and New Learnings Power plants both generate and consume electricity. The house load or auxiliary power consumption is a cost of generating electricity and is used by the motors, lights, and controls that operate the plant. Optimal auxiliary power consumption usually refers to lower levels at which operating only those components necessary for continuous and reliable is desired. A systematic approach to reducing and optimizing auxiliary power consumption has not been established. The results of the application of such an approach can be increased net generation and reduced heat rate. In 2011 EPRI issued a report, Electricity Use in the Electric Sector Opportunities to Enhance Electric Energy Efficiency in the Production and Delivery of Electricity (EPRI document ) summarizing the electrical use by the power generation industry and listing some potential areas for improvements. Due to increasing fuel costs and a desire to minimize CO 2 levels, improved plant performance has become a renewed focus for many power generating companies. Optimizing auxiliary power consumption is a part of improving plant performance. Auxiliary power consumes 6 to 10% of the power generated at coal-fired power stations. That percentage has increased with the addition of modern environmental control systems. Auxiliary power at nuclear and gas-fired power stations is a smaller fraction of their gross generation, but still may have room for reduction. Project Approach and Summary This project will develop an approach to optimize auxiliary power consumption and apply that approach at host units to evaluate its applicability and determine if it results in the expected improvements. The approach will provide methods to assess the additional risks and costs involved with reducing specific auxiliary power loads. The results will be compared to those estimated in EPRI report and will be published in a report. Benefits The potential benefits of optimizing auxiliary power consumption include heat rate improvements, as well as increases in generating capacity. On the other hand, reducing certain auxiliary loads may potentially increase O&M costs and negatively affect reliability. For example, a 0.25% heat rate improvement at a typical 500-MW unit operating with a 90% capacity factor can result in a fuel savings of more than $180,000 annually, and a reduction in CO 2 emissions of 10,000 tons/year (an added $200,000 savings if a $20/ton CO 2 tax is enacted). But a unit trip may cost more than $100,000 in replacement power costs and could potentially damage plant equipment. Reducing auxiliary power consumption can reduce unit heat rate. Reductions in unit heat rate translate directly to reductions in both fuel costs and emissions. Power plant owners and operators who are able to apply the methods developed as part of this project may reduce their plant heat rates, which may result in reduced emissions and fuel costs. The resulting cost savings may outweigh the risks and costs of the actions required to reduce auxiliary power consumption. Reducing auxiliary power by cycling components off when load drops off increases the wear-andtear on those components, increasing the associated maintenance costs, and the risk for sudden failures and associated unit derates or trips. Operating without redundant equipment can be more efficient but adds some risks to power plant stability and reliability. Combustion Performance and Emissions Control - Program 71 p. 11

12 Feasibility of Advanced Coal Cleaning for Minimizing Emissions (073632) Background, Objectives, and New Learnings Since the implementation of the Clean Air Act, power producers have relied on combustion modifications (e.g., low-nox burners) and post-combustion environmental controls (e.g., selective catalytic reduction [SCR] and flue gas desulfurization [FGD] systems) to achieve regulatory compliance. This strategy has been successfully adopted for SO 2, NO x, and particulate matter. More recently, emission regulations for acid gases and hazardous air pollutants (HAPS), such as mercury, also have been mandated and post-combustion-based solutions have been developed and successfully implemented. However, as allowable emissions of air pollutants (e.g., NO x, SO x, HAPs, etc.) are further reduced, and as further liquid discharge and solid waste regulations are implemented, the industry will need to address emission controls and effluents from a holistic, total-mass-balance, control-volume approach. This approach may start with the feedstock fuels and extend to the gas (stack) and related power plant waste streams (fly ash, bottom ash, FGD discharge, and stack gases.) Most bituminous coals used for steam production in the U.S. and elsewhere currently undergo some level of cleaning or washing in order to remove a portion of the sulfur and contaminant mineral matter. The resulting washed coal generally is designed to meet a plant s fuel specification. Contract fuel specs usually limit sulfur, ash, moisture and sometimes chlorine contents. More advanced coal cleaning technologies target removal of organically bound sulfur and heavy metals such as mercury, selenium and arsenic. The objective of this project is to assess the technical and economic feasibility of implementing more advanced coal cleaning technologies at existing power plants. The project results will determine if this approach can result in advantageous reductions in emissions, plant efficiency gains, and better economics while operating at a nearzero-emission levels when used in combination with existing post-combustion controls. This project is designed to: 1) Evaluate existing plant characteristics (e.g., design, equipment limitations, available space, operating features, etc.) for adapting a range of coal cleaning concepts; 2) Assess the feasibility of retrofitting a selection of these concepts into existing and new facilities; and 3) Quantify the expected benefits of operating selected unit designs with coal that has been cleaned to remove most of the mineral matter and associated heavy metals. The concept of approaching a near-zero-emission level using a combination of coal cleaning with postcombustion controls should be validated and, if feasible, the scope of an in-plant pilot-scale test will be defined. Project Approach and Summary A review of several promising advanced technologies has been conducted through EPRI s Near Zero Emissions (NZE) Technology Innovation program. However, some aspects of coal cleaning which could be achieved for a reduced cost need to be further investigated. Thus, the project scope includes an assessment of potential modifications to existing cleaning technologies to further reduce pollutants, an economic and technical assessment of the balance-of-plant impacts from operating with a NZE fuel, and finally, a test plan development for a demonstration at candidate sites. Benefits Removing mineral matter and associated pollutant precursors avoids the transformation of these compounds from their solid, natural, stable state into a gas phase and, subsequently, either a liquid or solid waste. For instance, the treatment of certain heavy metals such as mercury with sodium-based sorbents provides an effective capture solution. However, the fate of the adsorbed mercury and related sodium species is a potential future water quality concern. The option proposed in this project is to reduce sulfur and heavy metal concentration in the feedstock fuel in order to reduce the conversion of these compounds from solid to gas or liquid. Even for units that currently are equipped with best available control technology, this would mean a Combustion Performance and Emissions Control - Program 71 p. 12

13 substantial reduction in O&M costs, as well as a proactive strategy to minimize the costs of compliance with future air and water environmental regulations. By taking a more holistic approach to environmental compliance (e.g., one that incorporates front-end coal cleaning), increases in unit reliability and lower environmental impacts may be realized. As is the case with all new endeavors, there are risks and many unknowns, including overall costs savings, when it comes to operating an existing unit with a highly cleaned coal. This project aims to identify the research gaps and needs in this area. Combustion Performance and Emissions Control - Program 71 p. 13