Continuous Emissions Monitoring - Program 77

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1 Program Description Program Overview Coal-fired power plants are in increased need of 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. 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 Mercury and Air Toxics Standards (MATS) 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 costs 10% to 25% of current technologies. Research Value The Electric Power Research Institute s (EPRI s) Continuous Emissions Monitoring program (Program 77) helps members evaluate and implement monitoring options to achieve 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 monitoring technologies work; Prepare for anticipated mercury measurement requirements below today s proven quantization levels, as well as PM measurements (filterable and condensable) as surrogates for non-mercury 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 the American Society of Testing and Materials (ASTM) 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. 1

2 2 Electric Power Research Institute Portfolio 2014 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. Some components of this effort will be performed jointly with the Sampling and Analytical Methods project (P ) in EPRI s Environment Sector. The program provides members: R&D focusing on improvements in compliance monitoring the near-term emphasis of this program provides a forum for dynamic interaction among members 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 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 monitors 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 U.S. Environmental Protection Agency (EPA). This recognition is demonstrated annually by the successful CEMs User Group meetings organized by EPRI, which attracts strong participation by the 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 s R&D 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 a PM monitor troubleshooting and development test platform organized and managed by EPRI.

3 3 Electric Power Research Institute Portfolio 2014 Current Year Activities The program R&D for 2014 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; revisiting the search for methods to measure condensables in wet stacks without artifacts; completing field tests of techniques to calibrate 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 backend for process control and the continuing Tech Watch for concepts that could lead to significantly lower-cost CEMs. Estimated 2014 Program Funding $1.75M Program Manager Charles Dene, , [email protected] Summary of Projects P Continuous Emissions Monitoring (TBD) Description This project develops and demonstrates a variety of deliverables and services that advance the state of the art of CEMs, which in turn enables improved emissions monitoring accuracy and obtainment of lowest emissions for a given application and installed environmental controls. The project will focus on three general areas: Improvements in compliance monitoring Gas monitoring for process control Advanced monitoring technologies Improvements in compliance monitoring will address the need to demonstrate CMMs accuracy and reliability at the very low flue gas concentrations expected upon implementation of the MATS 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 also must be demonstrated. Gas monitoring and process control will include 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 arise, and EPRI would try to provide the suppliers with the test platform and periodic reference tests as they enhance 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 also 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, 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.

4 4 Electric Power Research Institute Portfolio 2014 Advanced monitoring technologies will include working with 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. 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. This area will also include issuances of Tech Watches 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 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. 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. 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 quantization 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.

5 5 Electric Power Research Institute Portfolio 2014 Supplemental Projects Demonstration of Alternative PM CEMs Calibration at Multiple Sites (072052) Background, Objectives, and New Learning 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 are not only difficult, time-consuming, and expensive to perform, but are also 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. A clear need exists 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. 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.