Combustion Performance and Emissions Control - Program 71

Transcription

1 Program Description Program Overview As the most cost-effective means of reducing emissions from coal-fired power plants, combustion modifications should be viewed as the first step in any emissions control strategy. Even if emissions control cannot be achieved with combustion modifications alone, when deployed in concert with post-combustion controls such as selective catalytic reduction (SCR) or selective noncatalytic reduction (SNCR), optimization of the combustion process in many cases can reduce the overall cost of emissions compliance. Recent and impending regulations, such as the successor to 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. In addition, 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. Finally, 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 (1) combustion and fuels impacts on boiler tube life; (2) impacts of combustion modifications and fuel quality on emissions; and (3) plant heat rate. All of these issues require an understanding of fuel quality considerations, accurate measurement and control of coal and air flow to individual burners, and improved performance of mills, burners, and other critical combustion- and performance-related hardware. 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. The ultimate goal of EPRI s Maintaining NZE Throughout Flexible Operations R&D roadmap is to enable emissions compliance throughout the load range (including low load), during load transients, and considering changes in fuel quality and blend ratios. Program 71 supports this roadmap by assessing the performance of environmental control technologies during these conditions. This research is pursued through both the P71 base and supplemental funded efforts. As NZE technologies are developed through the roadmap effort, the intent of the program is to assess these technologies under full-scale conditions. You can view the roadmap here. 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. Members can achieve substantial cost savings through improved boiler performance, regain lost capacity, and benefit from increased flexibility in fuel sourcing. Avoiding a single forced outage due to fireside corrosion, circumferential cracking, or slagging and fouling can save more than $1 million per unit. 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. 1

2 2 Electric Power Research Institute Portfolio 2014 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. A 1% heat rate improvement on a single 500-MW baseloaded 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. Approach Projects in three distinct groups help mitigate fireside corrosion and waterwall wastage in low-no x systems; develop and demonstrate cost-effective emissions controls through combustion modifications and assessments of emerging technologies; and optimize heat rate. For all of these areas, EPRI s approach is to develop and demonstrate cost-effective solutions to key issues, conduct comprehensive demonstrations, correlate data, and provide ample technology transfer through the issuance of best practices, technical updates, and user-led forums (webcasts, meetings, and workshops). Accomplishments For more than two decades, EPRI has led the power industry in developing, advancing, and demonstrating costeffective NO x 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 with the framework to apply these methods to improve plant performance at other units across their fleets. Site evaluations of gaseous species measurements using advanced laser diagnostic tools, to quantify improvements in emissions reductions, heat rate, and reduction in fireside corrosion. Issuance of best practices for plant engineers and operators, to best understand and respond to instances of accelerated fireside corrosion and circumferential cracking of boiler tubes. Laboratory assessments of various boiler tube coatings to assess their ability to mitigate fireside corrosion while minimizing circumferential cracking. Sponsorship of workshops, conferences, and webcasts in which funders and other key industry participants can share ideas and best practices, and outline needed solutions. Current Year Activities The program R&D for 2014 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).

3 3 Electric Power Research Institute Portfolio 2014 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 2014 Program Funding $3.5M Program Manager Anthony Facchiano, , afacchia@epri.com Summary of Projects Project Number Project Title Description P Combustion and Fuel Impacts on Boiler Tube Longevity P Cost-Effective Emissions Control via Combustion Modifications P Heat Rate and Cost Optimization P Combustion and Fuel Impacts on Boiler Tube Longevity (070555) Description 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. In addition to mitigating the above-described combustion- and fuel-based issues, owner/operators of coal-fired plants need to be able to make informed economic decisions based on holistic considerations of inter-related variables. For example: Will the savings achieved by using a lower cost fuel or blend, or by achieving a lower NOx level, or by increasing the rate of load cycling, outweigh the negative impact on boiler tube life, and the increased probability of early boiler tube failures? Accordingly, a long-term goal of EPRI s P program is to be able to quantify the tradeoff between savings in fuel, NO x reduction, load cycling, etc. against the cost of tube failures and other operability issues. 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

4 4 Electric Power Research Institute Portfolio 2014 Operational- and materials-based solutions and issues Development and implementation of best combustion practices Demonstration of optimal material solutions, such as coatings and fuel additives Demonstration of more robust process controls Improved system responsiveness to load changes 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. Enhance ability to make informed economic decisions on tradeoffs between increased flexible operations (e.g., fuel flexibility, emissions, cycling) and impacts on unit reliability. Provide quantified information on the relative impacts of deeper staging, fuel quality, load following on fireside corrosion, circumferential cracking, slagging and fouling. Reduce O&M costs by selecting effective protective coatings and weld overlays, as well as by taking into account coal quality considerations. 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 on slagging, 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. P Cost-Effective Emissions Control via Combustion Modifications (050311) Description Combustion modifications are the most cost-effective first-line approach to reducing emissions primarily of NO x but also mercury and other hazardous air pollutants (HAPs), sulfur oxide (SO x ), CO, and flyash from 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, along with application of 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:

5 5 Electric Power Research Institute Portfolio 2014 Application of results from 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. Assessing economic trade-offs between increased emissions reductions and boiler reliability and performance impacts. Conducting case studies documenting combustion factors influencing achievable emissions. Documenting cost and performance optimization of combustion-based NOx controls when used in combination with selective catalytic reduction (SCR). Demonstrating continuous in-furnace and economizer gaseous species monitoring devices. 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 identify the most promising technologies. 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. P Heat Rate and Cost Optimization (051807) Description 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. The heat rate and cost optimization projects in P focus on methods to improve and maintain equipment and plant efficiencies and support EPRI s Energy Efficiency (End-to-End) R&D roadmap. Optimizing or reducing the consumption of plant auxiliary power is one method under exploration. You can view the roadmap here. Approach This project 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, in which best practices, information, and prioritizing of available resources are shared. The Combined-Cycle Thermal Plant Performance Interest Group, supported by this program and Programs 79 (Combined-Cycle Turbomachinery) and 88 (Combined-Cycle HRSG and Balance of Plant) provides, promotes and facilitates an open information exchange among performance engineers, plant operations personnel, and others tasked with improving and monitoring combinedcycle plant performance. Finally, this project houses the Production Cost Optimization Interest Group, dedicated to seeking significant heat rate improvements for existing power generating facilities through costeffective operational modifications, and significantly more improvements through more capital-intensive improvements.

6 6 Electric Power Research Institute Portfolio 2014 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 to help increase savings in fuel costs, reduce CO 2 emissions, and increase productivity and availability.

7 7 Electric Power Research Institute Portfolio 2014 Supplemental Projects Production Cost Optimization Phase 2: Cost-Benefit Analyses of Capital Projects (067872) Background, Objectives, and New Learning 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.

8 8 Electric Power Research Institute Portfolio 2014 A Systematic Approach to Reduce Power Plant Auxiliary Power (072828) Background, Objectives, and New Learning 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.

9 9 Electric Power Research Institute Portfolio 2014 Combined Cycle Thermal Performance Interest Group (072489) Background, Objectives, and New Learning The mode of operation for many combined-cycle units has changed, and currently, most plants are spending more time on-line, resulting in higher capacity factors. Accordingly, thermal performance now constitutes a much larger effect on the plant s economics. Historically, very little attention has been paid to the thermal performance of combined-cycle units. With the new operating schemes for combined-cycle units, improved performance has become more important. Many combined-cycle units have experienced significant cycling and load following, and have operated for a number of years; hence they can no longer be considered new. In many instances, past operating schemes have advanced wear rates on components and degraded the plants efficiency. Thus, a need exists to identify programmatic methods to improve and maintain good plant performance. Performance monitoring programs also provide insight towards improving equipment and plant reliability. Higher fuel costs, competition, and the expectation of a carbon tax are the main drivers for the increased interest in plant heat rate. Decreases in other emissions, such as NOx and CO, are additional benefits. Project Approach and Summary The Combined Cycle Plant Performance Interest Group promotes and facilitates an open information exchange among performance engineers, plant operations personal, and others tasked with improving and monitoring combined-cycle plant performance. This interest group will meet periodically in person and at times, virtually via webcasts or teleconferences, to promote that information exchange, and when deemed necessary, propose research projects pertinent to improved performance of combined-cycle plants. Based on the interest group s preferences, guest speakers from other industry groups may be included in some or portions of some meetings. 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 CO2. For example, a 1% heat rate reduction at a typical 500-MW natural gas-fired combined cycle plant, operating at 50% capacity factor, can cut CO2 emissions by 10,000 tons/year, which equates to $200,000 if a $20/ton CO2 tax is implemented. A 500 MW gas-fired plant also will experience more than $700,000 in fuel savings for the same 1% improvement in heat rate, based on a fuel cost of $4/Mbtu. Traditional steam plants with active performance monitoring programs or on-site performance teams have experienced the best heat rates.

10 10 Electric Power Research Institute Portfolio 2014 Production Cost Optimization Phase 1 - Heat Rate Program Improvements (065662) Background, Objectives, and New Learning The benefits of improved performance of coal-fired power plants continue to grow as the costs of fuels rise and a carbon dioxide cap-and-trade program looms on the legislative horizon. Site-specific performance appraisals will identify potential improvements with the highest benefit-to-cost ratios, and follow-on analyses will document the results. Power generating companies looking to enhance their heat rate programs to reduce production costs are invited to participate in Phase 1 of EPRI s Production Cost Optimization project. This project will provide a third-party, EPRI-sponsored assessment and ranking of the potential benefits and costs of heat rate improvement opportunities to improve performance, which utility managers can use to justify the investment. Phase 2: Cost Benefit Analysis of Capital Projects (EPRI ) is the follow-on project that builds on the needs identified in Phase 1 by providing cost-benefit analyses of major capital projects. Higher fuel costs and the expectation of a carbon tax are the two main drivers for the increased interest in heat rate. Decreases in other pollutants, such as NOx, mercury, and SO 2, are additional benefits. However, for many utilities, the benefits of heat rate improvement are not transferred to the individual plant, leaving little incentive for plant managers to implement programs. Project Approach and Summary Participants will be asked to commit to achieving a minimum of 1% heat rate improvement at one operating unit. An experienced site contact who is familiar with the performance of the unit will be identified as site project coordinator. EPRI will coordinate an initial one-week, on-site performance appraisal using a team of heat rate experts. The team will assess both steam- and fire-side parameters, looking at turbine efficiency, feedwater heater and condenser performance, cycle isolation, and boiler efficiency. Average heat rate at full and partial loads will be calculated, using either the existing performance monitor or data downloaded from the distributed control system (DCS). The accuracy of the heat rate, found to be in the range of +/-3% for many plants, also will be determined. The team will provide a minimum of five recommended improvements, along with estimated costs and projected heat rate savings. These recommendations could take the form of operating changes or capital improvements. The host site will need to commit to funding/supporting one or more of these recommendations to achieve the 1% goal. 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. And all other emissions are also 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 for the same 1% improvement in heat rate, based on a fuel cost of $2/Mtu.