Continuous Emissions Monitoring - Program 77

Transcription

1 Continuous Emissions Monitoring - Program 77 Program Description Program Overview In the United States, consent decrees, state laws, and the proposed federal Maximum Achievable Control Technologies (MACT) standards for coal-fired power plants drive the need for robust, accurate, and certifiable continuous emissions monitors (CEMs) for mercury, particulate matter (PM), acid gases, and potentially selenium. Experience with continuous mercury monitors (CMMs) remains limited, and their operation and maintenance (O&M) are labor-intensive. PM monitors are not yet used routinely, and their calibration currently is cumbersome, while hydrochloric acid (HCl) is not measured continuously. Under the United Nations' Environmental Program, a growing number of countries or regions such as Europe are considering similar regulations and face similar compliance monitoring needs. Of particular interest to a number of power companies are instruments that continuously measure solid (filterable) and aerosol (condensable) PM, acid gases (e.g., HCl, hydrofluoric acid [HF], and hydrogen cyanide [HCN]), and ammonia in post-flue gas desulfurization (FGD) stack conditions. Enabling technology needs for these species include: Operation and maintenance practices for mercury CEMs that enable operators to approach the O&M now achieved with criteria pollutant CEMS through harvesting the lessons learned by early CMMs users; Sampling techniques that lend themselves to the very low pollutant concentrations that may be required by MACT limits, especially for mercury; Acceptable ways to calibrate PM monitors at plants with wet stacks without having to disrupt the operation of the wet SO 2 control; Droplet monitors to measure condensables; and Direct measurement of mass emissions to overcome the uncertainty of indirect measurements as PM characteristics change. Longer term, to remain competitive, the industry needs advanced, microchip- or laser-based CEMs, which hold the promise of 10 25% of the cost of current technology. The Electric Power Research Institute s (EPRI s) Continuous Emissions Monitoring program (Program 77) develops, enhances, and evaluates CEM systems that measure solids and chemical species of regulatory and operational interest. Research Value This R&D helps utilities objectively evaluate and implement monitoring options to achieve their measurement needs using robust, accurate, and easy-to-operate instruments. Benefits include: Save months of plant instrument technician and environmental engineer time needed to make newly procured CMMs work; Prepare for proposed regulations that, if promulgated as proposed, will require mercury measurements below today s proven quantitation levels, as well as PM measurements (filterable and condensable) as surrogates for nonmercury metal hazardous air pollutants (HAPs); Obtain credible, non-ash-property-dependent particulate mass emission measurements made in the stack to benefit from particulate capture by the SO 2 control; Ensure that ASME receives the data needed to adopt a digital opacity method for power plant stacks as an objective alternative to human observations; Optimize NO x and sulfur trioxide (SO 3 ) control operations, or flue gas conditioning for electrostatic precipitator (ESP) performance, via in situ continuous measurement systems for ammonia (NH 3 ), SO 3, and sulfuric acid; and Potentially save hundreds of thousands of dollars per stack if advanced sensors-on-a-chip are developed and accepted for power plant applications. p. 1

2 Approach This program promotes the development and validation of accurate, robust, and low-maintenance CEMs for compliance with new reporting requirements. It has a near-term emphasis on continuous particulate mass, HCl, and very low mercury concentrations. Based on similar technologies and skills, the program also develops and validates gas monitoring systems intended for optimizing pollutant control operation. Looking ahead to further cost constraints, it identifies, develops, and demonstrates innovative measurement systems with the potential to significantly reduce CEMs costs in the longer term. R&D focusing on improvements in compliance monitoring the near-term emphasis of this program provides a forum for dynamic interaction among power companies during the first years of implementing CMMs and particulate mass monitors for all emission levels and stack conditions (especially wet stacks). It assists members with issues, documents lessons learned, and tests upgraded CMMs for accurate measurements at very low mercury concentrations. In addition, it will seek or develop and evaluate instruments to measure HCl (and possibly HF), and will demonstrate the accuracy and reliability of digital opacity measurements as a replacement for human observer approaches. A longer-term goal is to find and demonstrate a method to measure aerosols (droplets) as a means of understanding and monitoring sulfuric acid formation and emissions. R&D on monitors for process control continues to identify and conduct field tests of continuous monitors for chemical species, the measurement of which could help in operating air pollution controls. The project will retain its collaboration with EPRI s Post-Combustion NO x Control program (Program 73) to demonstrate in situ NH 3 monitors. It also will develop an understanding of the accuracy of CO 2 measurement at 1% concentration level (for future operations with CO 2 capture). EPRI s work on advanced monitors microsensors, CEMS for hostile environments, and automated diagnostics will reinvigorate its Tech Watch for new advances in continuous monitors (having not had success with the earlier finds), and conduct proof-of-concept tests if any appear promising. Accomplishments EPRI s leadership in identifying and resolving performance and O&M issues with CEMs is recognized by the power industry, CEMs equipment suppliers, and regulatory agencies, especially the EPA. This is demonstrated annually by the successful CEMs User Group meetings organized by EPRI, which attracts strong participation by the U.S. Environmental Protection Agency (EPA), vendors/exhibitors, and users. EPRI's value also has been demonstrated in recent years by a number of EPA decisions on mercury monitors that have relied in part on EPRI findings, as presented to the EPA by industry. Examples include: EPA approval of the sorbent trap method for continuous mercury monitoring and use as a reference method; EPA approval to use an instrumental reference method in lieu of the complex, costly, slow-turnaroundtime Ontario Hydro batch method; Accelerated development of National Institute of Standards and Technology (NIST)-traceable calibration procedures for CMMs; Determination of CMMs' abilities to measure low mercury concentrations, leading instrument vendors to develop and demonstrate monitors capable of measuring accurately the very low concentrations expected after implementation of MACT standards; Proposed methodology for calibrating particulate mass emission monitors that avoids the need to exceed emission limits for other pollutants; and Strong positive response by the host power station and instrument suppliers to an EPRI-organized and managed PM monitor troubleshooting and development test platform. Current Year Activities The program R&D for 2012 will focus on completing efforts to demonstrate the capabilities of CMMs to measure very low mercury concentrations and to operate with less-intensive staff demands; finding and assessing reliable and accurate CEMs for HCl (and possibly other acid gases); re-visiting the search for methods to measure condensables in wet stacks without artifacts; completing field tests of techniques to calibrate Continuous Emissions Monitoring - Program 77 p. 2

3 continuous PM monitors without unusual processes; and enabling the use of digital opacity systems on large stacks. Additional efforts may continue the development and demonstration of continuous in situ, spatial measurements of NH 3 and SO 3 in the boiler back-end for process control and the continuing Tech Watch for concepts that could lead to significantly lower-cost CEMs. Specific efforts will include: Development and analysis of data that may still be needed to demonstrate the validity of alternate calibration approaches for continuous PM monitors (e.g., to answer EPA questions) Assessing the results of a supplemental project to determine the performance of digital opacity measurements on power plant size stacks, and providing the findings to the ASME committee considering certification of this approach Determination of detection and quantitation limits for current CMMs and proof-of-concept tests of potential enhancements that enable accurate measurement at emission concentrations expected from controlled power plants Demonstration of any concepts for measuring total particulate mass emissions (filterable and condensable) in both dry and wet stacks Evaluation and possible proof-of-concept demonstration of potential CEMS for acid gases Estimated 2012 Program Funding $1.2M Program Manager George Offen, , goffen@epri.com Summary of Projects Project Number Project Title Description P Improvements in Compliance Monitoring P Gas Monitoring for Process Control P Development of Advanced Emission Monitoring Technologies By monitoring field experience with CEMs for proposed MACTregulated pollutants and testing potential new CEMs for species not currently monitored, EPRI will provide information that power company staff can use to optimize operation of their mercury and PM CEMs and procure/operate CEMs for currently unmeasured species. CEMs capable of accurately measuring NH 3 and SO 3 at levels <5 ppm will be identified and validated for the locations in the flue gas path where these measurements are needed. This project seeks out and determines the technical merit of advanced sensors that promise substantial cost reductions for monitoring the full suite of pollutants and are accurate at projected very low future concentrations, whether to demonstrate compliance with proposed MACT limits (especially for new units) or to fine-tune reagent injection. Continuous Emissions Monitoring - Program 77 p. 3

4 P Improvements in Compliance Monitoring (051775) Key Research Question The March 16, 2011 proposal by the EPA of its MACT rule for HAPs emissions from electric generating units (EGUs) includes requirements to monitor mercury, total particulate matter (or individual nonmercury HAPs trace metals on an annual basis), and HCl (or SO 2 for units with an SO 2 control). For mercury, the needs are to demonstrate CMMs accuracy and reliability at the very low flue gas concentrations expected upon implementation of the MACT limits, and to reduce the labor intensity of maintaining these instruments. Beyond completing any residual work to demonstrate alternative calibration procedures for continuous filterable PM monitors, a need exists to demonstrate accurate measurement of total PM (filterable plus condensable) in the stack, even in a wet stack (post-fgd). Reliable, accurate HCl monitors must be demonstrated. Given the possibility that EPA may revert to a requirement for direct measurement of selenium in lieu of using condensable PM as a surrogate, EPRI will begin to investigate possible monitors for this species. Finally EPRI's 2011 results from a supplemental project to demonstrate the ability of digital opacity cameras to measure plume opacity accurately on power plant stacks (greater than the current method limitation to 7 feet in diameter) need to be analyzed and provided to its members, the American Society of Mechanical Engineers (ASME), and EPA for their consideration in expanding the ASME method to include these stacks. Approach EPRI's approach to facilitating the deployment of the CEMs expected to be required by the final MACT rule will depend on the pollutant, given the different development levels and needs: Mercury. 1. EPRI will maintain the web-based mercury measurement forum (CMMs and sorbent trap) created in 2008 for members to share their experiences and for EPRI and others to suggest solutions. By tracking the dialogue and contacting members of the program, EPRI will assemble the industry s lessons learned in updates provided to members of the program during the quarterly advisor meetings/webcasts. As needed, EPRI will seek fixes to problems or provide guidelines on how to implement CMMs or sorbent traps on particular applications. EPRI will also seek ways to reduce the labor intensity of operating and maintaining these instruments e.g., by finding, evaluating, documenting, and sharing with members cases in which power plants have significantly reduced their O&M burdens. 2. Working with Program 59, EPRI will conduct the tests needed to determine the detection and, most importantly, quantitation (DL and QL) limits of the leading mercury monitors. EPRI will encourage vendors that are enhancing their CMMs and sorbent trap analyzers to subject them to tests to determine these low concentration measurement limits, and will share its findings with members and EPA, as appropriate. Total Particulate Matter (TPM) 3. EPRI will complete its ongoing field evaluation (supplemental project) of PM CEMs to demonstrate their performance and calibration techniques that do not require extraordinary measures (e.g., turning off SO 2 scrubber modules to obtain calibration readings at much higher PM levels). The performance of the several PM CEMs will be reported by a supplemental project. Under the base program, EPRI will synthesize the calibration results and document the findings in a format that industry can use to provide information to the EPA on the use of the alternate procedures demonstrated by this project. 4. EPRI will revisit earlier studies of the performance of monitors for both filterable and condensable PM in a wet stack downstream of an FGD and consider ways to overcome remaining issues especially for the measurement of condensables. Continuous Emissions Monitoring - Program 77 p. 4

5 Acid Gases (i.e., HCl) 5. EPRI has identified a few instruments that promise the capability of monitoring HCl continuously. In 2012, EPRI will look for any additional potential monitors and study the designs, experiences, and validation results provided by each potential supplier. EPRI will identify potential integration issues when implementing acid gas monitoring into existing compliance monitoring systems and demonstrate any required modifications to the sample conditioning/handling process. A test campaign in 2013 (or 2012 if there is enough interest among industry to accelerate this effort via a supplemental project) will verify vendor findings. Digital Opacity 6. EPRI will synthesize and analyze the results from the 2011 supplemental project aimed at determining the applicability and value of digital opacity measurements as a replacement/complement to human observer readings. The findings will be presented to industry, ASME, and EPA in a manner that can be used by the parties to determine whether and how to expand the current method's applicability beyond its current limitation to stacks with diameters of less than 7 feet. Impact By facilitating the sharing of experiences among early adopters of CMMs, power plant operators can avoid noncompliance and over-compliance costs due solely to inaccurate or incorrectly certified CMMs. Independent, substantive data on the performance of CEMs for the other MACT-regulated pollutants, or those being proposed as surrogates, can help operators demonstrate compliance with the final MACT limits with less uncertainty and risk. Acceptance by EPA of alternative calibration procedures for PM CEMs can allow power plants to certify their monitors without having to detune or bypass pollutant controls such as SO 2 scrubbers. How to Apply Results Plant instrument technicians and plant and corporate environmental compliance engineers can obtain information about CMMs through the EPRI website and staff technical support. They also will be able to compare their operations to best practices documented by EPRI and use the report to determine if improvements to their systems or procedures are warranted Products Performance of Digital Opacity Monitoring Schemes for Power Plant Stacks: Analysis of findings from supplemental project, documented in a format useful for presentation to ASME and EPA, to inform decisions on allowing digital opacity methods to be used on power plant stacks (> 7 ft. diameter). Continuous Monitoring of MACT-Regulated Pollutants: Update on field experience with CMMs and lessons learned for high reliability at reduced O&M costs. Includes assessment of detection/quantitation levels for CMMs enhanced to measure very low mercury concentrations. Provides a status report on the capabilities and limitations of mass PM CEMs, with special focus on measuring condensable PM in wet stacks, and on CEMs for HCl. 08/31/12 Technical Report 12/31/12 Technical Update Continuous Emissions Monitoring - Program 77 p. 5

6 Future Year Products Continuous Mercury Measurement Guidelines Final Report: Final report, with guidance based on up to four years experience, as well as newer developments/advances. Similar to well-known periodic CEMS Guideline updates. Continuous Monitoring of MACT-Regulated Pollutants: Final report on tests and evaluations of CEMs for filterable PM, condensable PM, and acid gases. Future work may be needed to document lessons learned from early applications and develop mitigations measures for any issues. 12/31/13 Technical Report 12/31/14 Technical Report P Gas Monitoring for Process Control (069168) Key Research Question Continuous measurement of ammonia (NH 3 ) and SO 3 /sulfuric acid (H 2 SO 4 ) can be used for real-time control of: a) the NH 3 injection grid used in selective catalytic (or non-catalytic) reduction (SCR or SNCR) systems for NOx; and b) the injection of alkali to manage SO 3, and c) the injection of SO 3 to improve electrostatic precipitator performance. In addition, as emission regulations become more strict, power plants are likely to be subject to limits on these species in addition to the criteria and MACT pollutants. The rules may limit these pollutants directly or indirectly as a regulation on condensable PM (CPM); SO 3 and NH 3 are believed to be the major contributors to CPM. Typically, emission regulations are accompanied by requirements for CEMS to demonstrate continuous compliance. CEMS for SO 3 are just beginning to be introduced and need to be demonstrated. Implementation of continuous NH 3 and SO 3 monitoring will require the development of appropriate QA/QC procedures to maintain/verify continuous accuracy of the monitors. Approach A few CEMS suppliers recently have announced their development of a continuous SO 3 /H 2 SO 4 monitor for use in either dry or wet stacks. In 2011, EPRI will try to arrange for field tests of one or two devices that appear to be ready for full-scale, real flue gas. The tests would be conducted, analyzed, and documented in EPRI will work with the system suppliers to develop QA/QC procedures and equipment necessary to deliver reliable standards for calibration of NH 3 and SO 3 monitors in field applications. Given their relatively early stage of development, these instruments may still need field test time to address issues that will inevitably arise, and EPRI would try to provide the suppliers with the test platform and periodic reference tests as they enhanced their systems (similar to EPRI's earlier approach with mercury CEMS and, in 2011, with PM CEMS). EPRI will continue to provide technical input to the ASTM International committee developing new standard procedures for measuring SO 3 concentrations using the controlled condensate method, with the aim of improving accuracy and consistency. EPRI will seek opportunities to demonstrate the accuracy of tunable diode lasers (TDL) when used for in-stack measurements in either dry or wet stacks (although NH 3 concentrations are expected to be very low following a wet FGD system). Given the opportunity (host site and resources), this program will collaborate with Program 73 (Post-Combustion NOx Control) to develop ways to measure NH 3 downstream of the SCR. EPRI staff will search for, and demonstrate, methods to overcome interference by the particulate in the flue gas at this location. If warranted, based on results published by others, EPRI also may revisit the possibility of using differential optical absorption spectroscopy (DOAS) to determine if successful approaches have been found to overcome a potential interference by SO 2. Continuous Emissions Monitoring - Program 77 p. 6

7 Impact Successful demonstration of an NH 3 monitor accurate at emission levels consistent with the regulatory limits will prevent exceedances or costly over-control. Accurate measurement of SO 3 concentrations can minimize the consumption (and cost) of reagents used for SO 3 control or, in the case of SO 3 injection for ESP performance, the amount of SO 3 injected. The ability to monitor SO 3 and/or NH 3 continuously could make it easier to demonstrate compliance with the MACT rules for condensables than the approach proposed by EPA on March 16, How to Apply Results Engineers responsible for CEMs procurement and compliant operation can use the performance data generated under this project to determine if instruments are ready for commercial operation, how they need to be installed and operated, and what to require in a bid package for such devices Products Ammonia and SO3 Monitors for Ultra-low Emission Levels -- Technology Readiness Report: Field test results from two to three sites with very low NH 3 emissions and assessment of the technology readiness of the monitor. Field test results from one to two sites of continuous, post-particulate control SO 3 monitors for process control and potential compliance. 12/31/12 Technical Update Future Year Products Ammonia and SO3 Monitors for Ultra-low Emission Levels -- Technology Demonstration: Final report (projected) on availability and performance of in situ NH 3 and SO 3 monitors for compliance monitoring (in-stack). Potential results on use upstream of particulate collection device for control of SCR NH 3 injection and management of SO 3 entering the particulate collector. CEMS Guidelines Update: Update of CEMS Guidelines, last issued in /31/13 Technical Report 06/30/14 Technical Report P Development of Advanced Emission Monitoring Technologies (072051) Key Research Question As emission limits become more strict, measurement equipment will be challenged to monitor more species and at low concentrations. Significant cost advantages are expected if new multicomponent, lower-detection-level monitoring systems can be developed. Recent advances in microchip and nanotechnology offer the promise of drastic reductions in CEMs costs, both through miniaturization and multipollutant measurement capabilities in a single system, as well as greater sensitivity. However, given the small market size of the power industry relative to other industries that use microsensors, developers are not devoting resources to flue gas measurements; hence, the power industry needs to lead the effort to gain the benefits. A substantial portion of the investment in continuous emission monitoring systems is related to sample acquisition and delivery to the appropriate analyzers. EPRI will seek innovative approaches to sample acquisition and delivery that provide alternatives to the current dilution extractive systems. Potential benefits might include reductions in hardware, validation requirements, and opportunities for advanced sensor technologies. Continuous Emissions Monitoring - Program 77 p. 7

8 Approach With the appearance of a few new developers of quantum cascade laser (QCL) technology for low concentration measurements of gaseous species an advanced technology with promise for significant cost savings in the future EPRI will resume its efforts to demonstrate it. Pending developer cooperation and the availability of a host site, EPRI will conduct field tests on real power plant flue gas and compare the measurements to reference methods. Innovative approaches to sample conditioning will be investigated in both laboratory and field settings to determine the potential for further enhancement of CEM system designs. EPRI will continue its Tech Watch for new CEMS developments emerging technologies or field-tested devices used in other applications that may be applicable to stack monitoring or process control. EPRI also will follow EPA's regulatory calendar in order to stay abreast of any new requirements or technology determinations. The findings will be documented and test plans prepared for the members for any promising new approaches. Impact Successful deployment of emerging measurement technologies could lower capital and operating costs and improve accuracy at the anticipated future lower emission limits (P77.001). It could also reduce the costs of measurements for process control (P77.002). Advanced knowledge of potential new monitoring requirements will give the industry time to prepare, lessening the chances of being saddled with unnecessarily costly instruments. How to Apply Results Planners considering the next round of CEMs replacements will be able to anticipate significantly advanced monitors with greater confidence Products Advanced Sensors for Continuous Flue Gas Species Measurements: Identification (through Tech Watch) and engineering assessment of microsensors that might be applicable for use in CEMS or for flue gas species monitoring for automated process control. Lab or field test results if such sensors are found. 12/31/12 Technical Update Future Year Products Advanced Sensors for Continuous Flue Gas Species Measurements -- Update 2014: Update of 2012 report on microsensors that might be applicable for use in CEMS or for flue gas species monitoring for automated process control. Tech Watch findings and laboratory or field test results if promising sensors are found. 12/31/14 Technical Update Continuous Emissions Monitoring - Program 77 p. 8

9 Supplemental Projects Demonstration of Alternative PM CEMs Calibration at Multiple Sites (072052) Background, Objectives, and New Learnings Some electric generating units (EGUs) are required to monitor particulate matter (PM) emissions using continuous emissions monitoring systems (CEMS). Many more expect they will have to install PM monitors under proposed MACT rules. Currently, simultaneous EPA manual reference method tests (EPA Reference Method 5) must be used to calibrate and audit these PM CEMS, following EPA Performance Specification 11 guidelines (PS-11). These audits not only are difficult, time-consuming, and expensive to perform, but they are particularly onerous, because the method requires the EGU to modify plant operating controls and procedures to achieve a range of PM stack concentrations that is adequate to calibrate the CEMS. There is a clear need for better methods to calibrate and audit these PM CEMS, providing sufficient concentration range while eliminating complicated modifications to plant operations. Under other EPRI-sponsored efforts, Cooper Environmental Services (CES) has optimized a quantitative aerosol generator (QAG) to produce precisely known quantities of PM aerosols in the laboratory. The applicability of the QAG for PM CEMS calibration has been evaluated using laboratory and field tests. This project will support field testing of the QAG unit at different sites and stack conditions, and represents new learning for calibrating PM monitoring equipment without increasing emissions over a range of plant sites and stack monitoring conditions. Project Approach and Summary This project will support field testing of the QAG unit at different sites and stack conditions. The QAG system will be validated using the EPA PS-11 procedures as currently required. By validating the QAG calibration approach on multiple units and stack conditions, the project will provide implementation guidance and performance information for users to propose as an alternative to utilizing the full PS-11 procedure in future PM CEMS certifications. Benefits The successful demonstration of this method will provide more robust calibrations of PM monitors over a wider range of monitoring types and stack conditions, while minimizing the need to recalibrate due to out-of-range instrument readings. The public will benefit through more accurate demonstrations by power plants that they remain in compliance with their PM limits. Continuous Emissions Monitoring - Program 77 p. 9

10 Developing Digital Opacity Methodology for Large Diameter Stacks (072053) Background, Objectives, and New Learnings The ASTM D committee recently approved a test method (D ) that uses digital cameras and associated software to make stack opacity determinations. The method is restricted to stacks less than 7 feet in diameter, primarily because it has never been evaluated on larger stacks. The method was developed to mimic EPA Method 9, and does not take advantage of the technology offered by the digital cameras available today but rather uses the same acceptance criteria applied to human observers qualified via smoke school. This project will focus on developing the data suitable for applying the precision and bias calculations mandated by ASTM, using a standard against which all method measurements are compared. The project will use the available software with multiple digital cameras compared to a certified transmissometer at a smoke generator used for Method 9 training, as well as field testing on large-diameter stacks with certified opacity monitors. The data generated will cover the full range required by Method 9, but will concentrate on the low 0 20% and 20 40% opacity ranges more typical of electric generating units with large stack diameters. Field studies will cover both wet and dry stack applications. The project will be conducted with advice and consultation from the ASTM D committee on data and procedure needs to support future modification of the current Digital Opacity Method. Project Approach and Summary This project will establish a methodology for using digital camera technology for remote measurement of opacity in largediameter stacks. The project will be conducted in two phases. The first phase will establish the calibration of the digital camera(s) with respect to a certified transmissometer associated with an accredited smoke school. This calibration phase will establish the precision and bias data required by ASTM. The second phase will be a field validation of the method on both wet and dry stacks. Benefits The proposed project will provide a more reliable opacity method for large stacks, eliminating much of the variability and inconsistency of current Method 9 readings. The resulting revision to the ASTM D Digital Opacity Method could be a major step forward in opacity observations, removing subjectivity and providing a documented record of opacity events. Continuous Emissions Monitoring - Program 77 p. 10