### EPA **HCl Performance Specification Stakeholder Kickoff Meeting**  **Conference Call Summary Tuesday, May 17, 2011**  **1) Welcome** 

**– Introduction** 

**– Purpose**  EPA is gathering information from instrument and gas vendors, affected facilities, testers, and regulatory bodies with experience performing continuous measurements of HCl from stationary source emissions . At a conference call Attendees (Attachment 1) provided stakeholder perspective on the current state of the science for CEM systems used to measure HCl in stationary source emission gases. **2) Technology**  **discussion from the instrument vendor perspective** Table 1 summarizes the current instruments from equipments vendors participating in the call. Vendors are shown in alphabetical order. Additional comments from equipment vendors include descriptions of their systems and how they are used for field measurements. A summary of these comments are provided below. **Thermofisher** Thermofisher offers a GFC system. Water is removed as an interferent from the emissions gas using a permapure dryer system. GFC equipment is based on the standard simple rack mount design used for other Thermofisher CEMS equipment. The system has longer response time than their FTIR system approach to HCl monitoring. That means the GFC has to b e conditioned longer and calibrations are required more frequently. The GFC is subject to more interference. Thermofisher is also gaining experience with FTIR HCl measurement. Lab and field evaluations are being conducted in waste incinerator, power util ity and cement plant gas streams with up to 40% moisture. FTIR is more complicated and more expensive than the GFC system. Thermofisher uses twice the standard deviation of the zero noise to determine detection limit. Hot, wet operation is a challenge at higher moisture levels. The advantage of FTIR is the opportunity to perform multi

component analysis with one instrument. **Sick**
**- Maihak**  Sick

- Maihak offers GFC, FTIR and TDLS bases HCl monitors. All systems are run hot and wet. The Sick

- Maihak GFC is a multi

- com ponent capable system. Cross interferences are measured real time and used to process the data. The simplicity of the GFC makes this technology easier to operate in the field. Sick

- Maihak has more field experience with the GFC and has tested this te chnology at cement production, waste combustion, and power generation sites. The Sick

- Maihak TDLS system can be used as extractive, cross stack or insitu with a probe. TDLS are less susceptible to cross interference because of the narrow wavelength range generated by the laser. Less interference and a stronger optical source allows lower detection limits.**Table 1 Summary of Conference Call Vendors and Technologies** Vendor Technology Base Extractive or Cross Stack Wet or Dry Lab Detection Li mit (ppm) Full

Scale Range (ppm) Averaging

Time Initial

Calibration Field

Performance Checks ABB FTIR (1

- 2

wavenumber resolution) Extractive Hot Wet 0.1 to 0.2 HovaCal

- Hot Wet at instrument detector Checked at the

analyzer/cell

Altech Environment GFC

-

multicomponent Permapure® water removal at the detector HovaCal

- Hot Wet at instrument detector Checked at the

analyzer

Altech Environment FTIR CEMTEC K CRDS Extractive Wet 0.2 0

– 3 CEMTEC K TDL Cross Stack or extractive Insitu or

hot/wet 0.2

Eco Chem analytics GFC

-

multicomponent Extractive Hot Wet 0.1 0

– 10 HovaCal

- Hot Wet at instrument detector HCl Certified

cylinder Gas

Gasmet FTIR (8 wave

number resolution) Extractive 0.1 HovaCal

- Hot Wet at instrument detector Can be

checked at p robe or analyzer MKS Instruments FTIR (0.5

wavenumber resolution) Extractive Hot Wet 0.1 1 min

Sick

- Maihak FTIR (0.5

wavenumber resolution) Multi

Component Hot Wet 0.1

Sick

- Maihak GFC Multi Component Hot Wet 0.2 At the analyzer Sick

- Maihak TDLS Extractive and insitu Hot Wet 0.1 0

– 5 Thermo fisher FTIR (0.4

wavenumber resolution) Extractive Hot Wet 0.1 10

– 100’s HovaCal

- Hot Wet at instrument detector Can be

checked at probe or analyzer Thermo fisher GFC Extractive Permapure® water removal at the detector 0.2 5

– 5000 5 min HovaCal

- Hot Wet at instrument detector FTIR

– Fouier Transform I nfrared GFC

– Gas Filter Correlation TDLS

– tunable diode laser spectroscopy.**MKS instruments**

MKS instruments is currently testing a multi

- component FTIR, extractive CEM that measures HCl in hot wet gas. The system has been operated up to 40% moisture. FTIR is more expensive than a single component analyzer. Other components measured include hydrocarbons, NOx, SOx, HF, CO, and CO2. Challenges measuring HCl involve sampling rather than instrument analysis. MKS prefilter the gas stream. **ABB** ABB offers an FTIR CEM for HCl similar to those described by other vendors except their unit operates at a resolution of 1 to 2 wave numbers. **Cemtech** Cemtech offers a TDL and a laser based cavity ring down (CRDS) CEM unit for HCl monitoring. The TDL technology offers a fiber coupled optical system which allows the optical system to be remotely located from the measurement location . This technology can be multiplexed which allows the laser to be directed to multiple lines of sight or locations. These systems are offered as cell based extractive or cross stack units.
The CRDS unit that operates at reduced pressure to maintain stack emissions in the gas phase. No other sample conditioning is performed for this unit. The gas is maintained at 50  C. The sampling system uses a critical orifice through a filter sampling at 3 L/hour. The low pressure sampling and analysis system reduc es or eliminates interference. The probe and transfer line is fused silica lined and heated to 50  C to improve response time. The CRDS system can be used for multiple components by adding lasers or adding an optical bench that can be multiplexed with the system to measure at appropriate wavelengths for each component. The same probe, umbilical transport line and pumps are used for single or multiple analyte configurations. Typical applications merge water measurement with HCl measurement

. CRDS cell is maintained at a constant temperature and pressure. The effective path length for this application is approximately 10 kilometers . Therefore, the sample pressure can be reduced which keeps materials in the gas phase and narrows spectral lines thus reducing interference. Cell sizes range from 5 to 10 inches consistent with small rack mountable CEMS. Cemtech will perform its first field trial at a cement plant in July of 2011. This system is currently operational at a waste water treatment facility and a waste incinerator. **Gasmet Technologies** Gasmet Technologies offers an FTIR HCl CEM system that has been installed in multiple locations in Europe including cement plants and waste incinerators. The system measures multiple gases. Less resolution is used to improve detection limits by reducing noise. **Eco Chem Analytics** Eco Chem Analytics has experience with a hot, wet, multi

- com ponent CEM syst em based on GFC technology. Their GFC monitor measures eight (8) total gases including HCl, water and up to 6 otherinterfering compounds. Units are installed in multiple U.S. facilities such as municipal waste water

facilities and chemical facilities. Altech has experience with multi

- com ponent CEM system based on GFC technology. Installations include cement plants and municipal waste incinerators.
**Altech Environment**  Systems currently offers GFC multi

- com ponent system. US installations include cement plants, and municipal waste incinerators. Altech also has experience using FTIR to measure HCl through its support to European facilities. **3) Initial Calibration, System Checks**  Vendors perform calibration of new units at the factory. Vendors perform initial calibration using the HovaCal equipment or certified gas cylinders

. HovaCAL equipment is used (ABB, Altech Environment, Thermofisher) t o generate various concentrations of HCl at temperatures as high as 375

 F and up to 40% moisture. HovaCal vaporize s an aqueous solution of the compound(s) of interest. Instrument initial calibration is done during production.
Some Gas Filter Correlation vendors (Thermofisher , Altech Environment) reduce or remove water interference by membrane (Permapure®) drying the gas stream. Residual water after membrane dryers can be measured by IR and appropriate corrections can be included if necessary. FTIR systems are initially calibrated using the HovaC AL and with certified gas cylinders (Thermofisher)

. Cross stack TDL (CemTech) is calibrated during manufacturing at the factory

. An internal gas cell is used to lock the laser and to calib rate or check calibration. The laser light is redirected through the cell in line with the measurement path to perform a span and off peak zero check. The frequency of span and off peak zero check is programmable. In the field a span check is typically performed once every 24 hours. The frequency of c alibration checks of instrument performance are programmable using a constant pressure constant temperature cell in the optical measurement path. This performance check acts as a matrix spike interference check on the instrument performance. Since the calibration is based on a ratio of the cell path length (typically multiple cm) and the measurement path length, the concentration in the cell is not as constrained as other methods and certified calibration gas can be used that is much higher concentration. Path length is measured independently and entered into system software allowing continuous concentration reporting. Temperature and pressure corrections need to be made to compensate for the difference between stack and reference cell conditions. Initial manufacturing setup for CRDS

- TDL systems involves evaluation of the optical spectra for a new target gas and potential interfering gases. A laser wavelength is selected from available TDLs that best match the sensitivity and lack of spectral interference found in the optical spectra review. A wavelength specific to that laser is selected where there is no spectral overlap of any of the interfering gases including moisture with the target gas. Once the new monitoring system is fabricated, it isevaluated using laboratory generated test gas that includes up to 50% moisture to demonstrate

interference free measurement of the target gas. The system is also tested with other common emission gases to ensure int erference free operation. The system is calibrated with known concentrations of calibration gas as part of the manufacturing process. **4) Field Calibration/Drift Checks**  **and Dynamic Spike Performance Checks** Field calibration checks are intended to verify the manufacturing calibration. Two types of field calibration checks and drift checks were discussed for FTIR and GFC. Some vendors report ed checking instrument performance with hot wet gas at the instrument detector using HovaCal equipment. Others report checking field performance using certified cylinder gas either through the probe or at the instrument detector.
The HovaCAL hot wet instrument is more difficult to use in the field due to weight and complexity. Performance checks done under hot wet conditions with the HovaCal equipment reduce conditioning and response time. Vendor preference , in general, is to check instrument calibration and drift at the instrument cell/detector with the HovaCal and not to use the equipment on the stack to perform through the probe system checks. Recalibration using the HovaCal to evaluate water vapor interference in the field is performed yearly (Eco Chem Analytics) , typically when Relative Accuracy (RATA) is performed.
Vendors and testers also us e C ertified HCl gas cylinders to re calibrate or check the instrument calibration in the field . Through the probe system performance checks have been done using dry cylinder gases. For field calibration testers can flood the probe with cylinder gas at each concentration of interest. Checking instrument performance with a certified (d ry) HCl gas cylinder can take 20 minutes or more to stabilize through the probe. In Europe it is not common to check HCl field calibration through the probe. Instead, European systems are challenged directly at the analyzer detector

. When TUV tested HCl monitors using the HovaCal hot wet calibration gas they found response times on the order of 3 minute s. Gasmet does field performance checks at the analyzer and checks sample line integrity through the probe with NO or SO 2 cylinder gas. Field performance checks of CRDS

- TDL systems are performed through the probe using silica coated stainless steel line s from the cal gas supply to the probe. Since this system samples at about 3 L/hour, and calibration checks take about 10 minutes, very little calibration gas is needed. Gas can be run directly to the analyzer as a check of sample line integrity. Zero check of this system occurs every 10 seconds (6 times a minute) by turning off the laser and measuring background signal. Facilities needing to measure HCl at 3 ppm or lower, the calibration and linearity of the equipment become significant issues. In the field, facilities check their equipment and vendor supplied spectra using the best quality gas standard they can find. The best spectra to use in the field are those that are generated on the equipment with known concentration of known quality gas standards. These instrument specific reference spectra are important for low concentration measurements. In addition to the target gas, spectra of interferents such as water and carbon dioxide are important.**5) What’s the alternative to RATAs, are they**  **necessary**

Dynamic spikes have been performed in numerous field tests (GFC and FTIR systems) , and the most difficult challenge to this approach is measuring HCl in the presence of alkaline particulate (e.g., lime) as is found at cement plants. Dynamic spi kes less than 10% of the gas volume from the stack provide a robust challenge that evaluates the effect of both interfering gases and reactive particulate during HCl CEM field tests or monitoring programs. This approach is consistent with PS

- 15. Stakehol ders did not know of a manufacturer or test facility that performed long term dynamic spiking to support continuous monitoring of HCl. However, Eco Chem reports that the HovaCal can be programmed to produce a variety of concentrations in any sequence required. Sources with both HCl and ammonia emissions pose a particular problem for performance checks because of the acid base reaction potential between these two gases. Emissions Testing Inc. reports making measurements of HCl above 180  C to minimize thi s reaction. However, the accumulated alkaline dust on the sample conditioning filter scrubs significant amounts of HCl from the gas stream. Analyte spikes of at least 10% of the gas stream leave the sample relatively “undisturbed” resulting in a true c heck of the measurement performance. While the standard version of the HovaCal can perform episodic dynamic spiking it is not an automated system and requires dedicated operator oversight to function properly. Eco Chem reports that a “process” version of the HovaCal can produce a daily dynamic spike without an operator continuously onsite. However, current facility experience with through the probe dynamic spiking suggests it is difficult and time consuming on a periodic basis and not demonstrated for use on a continuous basis. Regular dry gas spiking is performed and data exists but may not be related to instrument agreement with reference methods during (RATAs). Thermofisher reports plans to manufacture units that allow dynamic spiking and it is their intent to evaluate monitor performance over the next several months as they field test their instrument designs. Thermofisher also plans to use SF 6 as a tracer (for FTIR monitor tests) to evaluate dynamic spiking with a stable easily measured compound. From a facility standpoint, many current compliance systems (Altech, SICK, Eco Chem and TDL systems) use dry cylinder gas for performance and calibration spikes. Typical measurement ranges for current compliance systems are between 0 and 25 ppm. Current compliance levels are 25 ppm. The current cement rule poses a related challenge since it requires measuring a 30 day rolling average with a limit of 3 ppm. Contemporary cement plants with in line raw mills the emissions are 10 times higher when the raw mill is off, which may translate to the need to measure 0.5 ppm for ~90 % of the time to compensate for 10% of the time when the plan generates 15 ppm when the mill is off. Since quantification limits are higher than the 0.1 to 0.2 ppm detection limit, demonstrating compliance may be a daunting task with today’s measurement equipment. The stakeholders will need an agreement on the relationship between the detection limit and the practical quantitation limit to determine if current measurement equipment can measure emissions present 90% of the time. As sampling systems age between maintenance intervals, the effective quantitation limits change.6) **Frequency of Performance checks**

Vendors or facilities conduct performance checks weekly in Great Britain. Based on performance data, facilities can petition for less frequent checks if they demonstrate instrument stability for longer than a week. The maximum time between checks is the maintained interval of the instrument, approximately 90 days. European tests to evaluate monitor stability and calibration drift require field tests over a year period before reduced performance check schedules are approved. The stability test requires two identical units evaluated over at least 2 performance or maintenance period s based on CEN requirements. In Europe, each country defines specific performance check frequency which can be stricter than the CEN standard. Some European countries require more frequent performance check after the initial performance period, but none require daily checks. **7) Protocol Gases** 

**– Availability and Certification**  Gas Vendors (Airgas and Linde) reported availability of HCl gas in cylinders at 10 ppm to 1% using FTIR. Compressed gas under 1000 ppm is shippable in aluminum cylinders, however the vendors agreed nickel lined steel cylinders were preferable for stability. The main issues with lower level certified standard preparation involve stability in cylinders and availability of NIST certified standards as a check on vendor certification analysis accuracy. Vendors highly recommend using nickel lined cylinders. Some states that have HCl compliance requirements require nickel lined gas cylinders for HCl standards. Vendors agreed that nickel lined or treated hardware (e.g., regulators) may be needed to spike HCl at concentrations below 10 ppm. Moisture is also a key issue in the transport and stability of HCl. Any moisture in the valve or regulator will bias results low due to reactions with the cylinder valve or regulator. Gas vendors and testers added that keeping regulators on the cylinders once they are first put into service minimiz es water contamination of the valve and regulator. The analytical accuracy certified by the vendors for gasses from 10 ppm up to 1% is about 3%. Below 10 ppm vendors are only willing to certify gas cylinders to  10% because the gas vendors do not have a traceable standard to compare to their measurements. Vendors report NIST is currently capable of certifying gas to 2% accuracy. Analysis is performed using (heated cell?) FTIR. Airgas uses MKS equipment and vendor supplied library calibration curves t o determine cylinder gas concentration. The MKS spectra are traceable to HITRAN spectra. For gasses at higher concentrations (i.e., from 1000 ppm to 1%) Airgas performs wet chemical analysis of HCl cylinder gas. Low concentration (1000 ppm) wet chemical analysis of HCl cylinder gas can be compared to FTIR results to verify FTIR determined concentrations. Linde follows a similar process with a different IR vendor ’ s equipment. They also compare the results from wet chemical analysis to the FTIR.
The challenge for gas vendors is NIST standard availability. The request has been made through the process of upgrading the “Green Book” to encourage NIST to generate a certified gas standard for HCl. The request for NIST support involves preparation of a NIST prime, orpreferably a batch of NIST reference gas materials available for gas vendor purchase and use as a

reference in the HCl gas certification process. Without an NIST standard HCl gas there is no inter

- comparison of vendor generated standard gases. G as vendors believe NIST can generate a stable reference gas material no sooner than 18 mo nths from the time they start. Frank Guenther is the NIST contact for this activity. Gas vendors report the ability to generate gas in cylinders at less than 10 ppm if a NIST standard was available to check the certified concentration. The analytical uncertainty increases to 10% for standards prepared below 10 ppm because there is no (NIST) gas standard to check the bias of their results. Certified standard gas cylinders in the range of 10 ppm to 1% are stable for 12 months. Vendor ’ s best estimate of stability in the absence of a NIST low concentration HCl standard, for gas less than 10 ppm will be no better than 6 months. Moisture contamination and inert transfer l ines are a large component of HCl field cylinder stability. Testers have generated low concentration HCl gas in the field by diluting high concentration gas standards. Mass flow controller calibration, construction material and conditioning are contrib utors to the original standard gas uncertainty for dilution system generating low concentration HCl test gas. However, the accuracy and precision a tester experiences is based on the combination of the uncertainty contributed by the calibration gas and th e uncertainty contributed by the field dilution and delivery system. Testers and facilities need to qualify both the detection limit and the linearity of their monitors. Vendor(s) asked if the NIST reference standard development was limited to standards in the gas phase. Reference was made to the HOVACAL as a reference standard. Facility(s) responded they would prefer using a dry gas standard to keep the spiking process as simple as possible. 8) Other relevant performance specifications
State Performance Spec ifications (e.g., Pennsylvania) exist for waste to energy processes. The Pennsylvania performance specification mirrors PS

– 2. The concentration measured at these sources is well above 1 ppm. Typically facilities perform RATA tests using Method 26A. Instruments well measuring dry gas streams. Daily QA/QC and calibration is consistent but needs to be tracked regularly. Early RATA tests failed the 20% agreement requirement and Pennsylvania agreed to accept an absolute  5 ppm agreement between Metho d 26A and the CEM. According to Ralph Roberson at RMB consulting , t he EGU facilities are concerned about the issue of RATA agreement because the mean difference divided by a small concentration results in a value that can be 100% of the target concentration. The issues here are similar to the issues encountered with Mercury CEMs. The important technical issue for the Industry is performance evaluations where concentrations can be accurately measured by both the CEM and the reference method.Ji m Peeler at Emission Monitoring Inc

. commented that f or tests involving the cement industry area sources, Method 26 or 26A have not been allowed and testers must use Method 321. The instrument (FTIR) is validated using known addition of spikes. Testers are hard pressed to get 2 ppm or lower spikes through the alkaline cement kiln dust caked onto the instrument inlet filter. RATAs using a reference FTIR method to quality a FTIR CEM will not identify common interference issues. Jim proposed automated analyte spikes as one way to demonstrate the performance of continuous HCl monitors. According to Peeler, the s tate s of Michigan and Maryland have approved dynamic spiking as an alternative to qualify HCl and SOx/NOx systems.
EPA Method 321 also has a provision for dynamic spiking as an integral part of the QC for FTIR measurements. 9) Other Issues to Address

– Open Discussion The proposed EGU MACT rule sets the HCl standard at 1.4 ppm for existing sources. Measurements will need to be qualified down to approximately 1 ppm. The gas vendors believe the path to an HCl NIST Reference Gas Material may occur sooner if NIST is willing to work with the Netherlands Measurement Institute NMi toward a memo of understanding regarding NMi HCl reference material. 10) A ction Items
Schedule a conference call with Frank Guenther at NIST to discuss the need for an HCl reference gas standard. Ray Merrill will talk with Bob Wright (EPA/ORD) to identify a small group of participants and schedule a conference call.
EPA has a ccess to an early draft HCl PS written by Eli Lilly which we will review for relevance to development of an HCl Performance Specification. EPA will review the status of dynamic spiking as an alternative to qualifying the performance in Method 7E.
EPA will prepare a summary of this conference call and distribute it to the stakeholders for review. After receiving review comments EPA will schedule the next conference call to update stakeholders on the HCl performance specification and to open topics that need additional input or clarification.**Table 1: Conference Call Attendees and Contact Information Name**  **Affiliation Interest**  **Em ail**  Allan Rilling ABB Equip Vend or allan.j.rilling@ca.abb.com Bob Davis AirGas Gas Vendor bob.davis@airgas.com Musa Zada Altech Equip Vendor Malik Hatar Altech Equip Vendor Bob Vantuyl Ash Grove Cement Facility bob.vantuyl@ashgrove Andy Edwards Ash Grove Cement Facility Deseri Haggard Calportland Facility Ty Smith Cemtech Environmental Equip Vendor Kieth Crab Cemtech Environmental Equip Vendor Joe Aldina Covanta Energy Facility jAldina@covantaenergy.com Edul Chikhliwala EcoChem Analytics Equip Vendor chikli@ecochem.biz Laura Kinner Emission Monitoring I nc. Tester lkinner@mindspring.com Jim Peeler Emission Monitoring I nc. Tester jimpeeler@mindspring.com Ray Merrill EPA/OAQPS/AQAD/MTG Regulatory Agency merrill.raymond@epa.gov Jason Dewees EPA/OAQPS/AQAD/MTG Regulatory Agency dewees.jason@ epa.gov Robin Segall EPA/OAQPS/AQAD/MTG Regulatory Agency segall.robin@@epa.gov Barrett Parker EPA/OAQPS/SPPD/MPG Regulatory Agency parker.barrett@epa.gov Rachael Agnew EPA/OAQPS/SPPD/MPG Regulatory Agency agnew.rachael@epa.gov Collin Boswell EPA/OAQPS/SPPD/MPG Regulatory Agency boswell.collin @epa.gov Gerri Garwood EPA/OAQPS/SPPD/MPG Regulatory Agency garwood.gerri@epa.gov Candace Sorrell EPA/OAQPS/AQAD/MTG Regulatory Agency sorrell.candace@epa.gov Lu c Sevrette Gasmet Equip Vendor luc.sevrette@gasmet.com Andre Hegre Gas Technologies, Finland Equip Vendor Hector Ybanez, Holcim I nc. Facility hybanez@gmail.com Matthew Rutledge La farge Facility Mike Hayes Li nde Gas Gas Vendor Barbara Marshick MKS I nstruments Equip Vendor Barbara_Marshik@mksinst.com Fred Grunewald MKS I nstruments I

nc. Equip Vendor fred.grunewald@mksinst.com Martin Spartz Prism Analytical technology Tester m.spartz@pati

- air.com Ralph Roberson RMB Consulting Facility

- ECU Roberson@mb

- consulting.com Dan Kietzer Sick

- Maihak Equip Vendor dan.kietzer@sickmaihak.com Kita Dieter Thermofisher Equip Vendor dieter.kita@thermofisher.com Stephen Johnson Thermofishter I nc. Equip Vendor Stephen.Johnson@thermosisher.com James Willis Titan America Facility jwillis@titanamerica.com Jeff Harrington Tyco Environmental Systems Equip Vendor Gary Catchatory Tyco Environmental Systems Equip Vendor Michael Corvese Thermofisher Equip Vendor Michael.corvese@thermofisher.com Frank Duckett Thermofisher Equip Vendor Frank.duckett@thermofisher.com Ashmud Patel Ethyl Smith Automation Henry Veger CEM Specialties Equip Vendor Dave Vigowax Marantee Tile Facility