Advances in NOx Compliance Testing with Portable Electrochemical Analyzers

Transcription

1 Advances in NOx Compliance Testing with Portable Electrochemical Analyzers LADCO Workshop: Emission Control and Measurement Technology for Industrial Sources March 24-25, 2009 Craig McKim, Emission Division Manager Testo Inc. Sparta NJ

2 Summary Testing and approvals - for portables States agency experiences with portables The technology the good, the bad, and the solutions Analyzer/technology description Data acquisition Application examples 2

3 Last Night - State Roundtable Statement OHIO Identified an untapped source of NOx Reduction Combustion tuning where did it go? Nobody doing it. Source testing Once every 5 years, once/year This speaker- No measurement data no reason for change/optimization Combustion is dynamic system things change over time Proposal Implement periodic monitoring program for Combustion Tuning - for Compliance, for NOx reduction, 3

4 History - Testing Programs for Portables European TUV Approval for official Source testing (NOx & CO) since early 1990s (yearly testing approvals) 1996 GRI tested 6 models of compliance level Emission Analyzers. Results of testing showed consistent laboratory performance, typically within 1% Result = development of referenced-level test method 2000 EPA ETV tested seven multi-gas models 6 analyzers within about 1% of reference, 1 within 5% Result of the ETV testing = 4

5 EPA s Revised Method 7E Method 7E DETERMINATION OF NITROGEN OXIDES EMISSIONS FROM STATIONARY SOURCES (INSTRUMENTAL ANALYZE PROCEDURE) 5

6 EPA s Revised Method 7E 6

7 What EPA said about Electrochemical Analyzers In its Final Rule for the Update of Continuous Instrumental Test Methods, the EPA stated: The electrochemical analyzer has been shown capable of producing reliable results in an Environmental Technology Verification study and we do not believe special restrictions should be placed on this technology. Federal Register Vol 71/ No 93, Page

8 White Paper 2009 Gas Machinery Conference - Atlanta Title - Exhaust NO/NOx Ratio from Lean Burn Natural Gas Engines NO2 to NO ratio can be significant with ultra lean conditions or when using oxidation catalyst. Large NO2/NOx ratios may results in additional uncertainty in NOx Measurements since the most common technique chemiluminescence was developed for Low NO2/NOx ratios. Three measurement technologies were tested - Chemiluminescence - Electrochemical cell - Fourier Transform Infrared (FTIR) Spectroscopy 8

9 White Paper 2009 Gas Machinery Conference - Atlanta - Conclusions The portable analyzer with chemical cell technology was found to be the most accurate for measuring exhaust NOx with Large NO2/NOx ratios. 9

10 States Identify Compliance Problems Numerous state agencies use portable electrochemical analyzers to identify noncompliance - three examples Oklahoma - DEQ (stationary engines) Texas TCEQ (stationary engines) California - SCAQMD - (stationary engines & boilers) 10

11 States Identify Compliance Problems Oklahoma DEQ Original intent to develop a one-year training program for inspectors. Included Spot checks with portable analyzer to better understand gas transmission market Findings of program Found approximately 75% of sources not meeting emission limit Results News quickly spread of agencies spot checking ability 90% compliance after one year of spot checking. Unintended - Companies developed new programs (i.e trained employees to be engine analyst & emissions analyst. 11

12 States Identify Compliance Problems Texas TCEQ Used portable analyzers for spot checking sources. If source out of compliance, reason to cite and require immediate 3 rd party source testing. Findings of program Similar to Oklahoma experience - Found approximately 75% of sources not meeting emission limit Tested a small V8 engine - found it comparable to title V source Results News quickly spread of agencies spot checking ability Approximately 90% compliance after one year. Companies developed new programs (i.e - engine analyst & emissions analyst. 12

13 States Identify Compliance Problems Draft 2007 AQMP - Sufficient emissions reductions had not been identified Identify sources by unannounced emission tests by AQMD - Target Stationary Engines then Boilers Rich-Burn Engines Lean-Burn Engines No. of Tests No. of ICEs Tested % of Tests on ICEs with BACT Limits 79% 91% % Non-Compliance 51% 27% % NOx Violations 40% 27% % CO Violations 28% 0% 13

14 Emission Exceedances NOx CO Rule Limits, ppm* Typical BACT Limits, ppm* Maximum Test Concentration, ppm* ,500 Average Violation Concentration, ppm* 137 2,520 15% O2 Maximum % Over Limit 7,430% 18,400% Average % Over Limit 912% 1,830% Tested Excess Emissions, Tons/Year 385 4,894 Major contributor for Non-Compliance Engines loads change frequently. Many older air-to-fuel ratio (AFR) devices have difficulty controlling emissions with changing loads or detecting non-compliance operation 14

15 Amendments to Monitoring, Recordkeeping and Reporting Source Testing Amendments Increase frequency from every 3 years to every 2 years (or 8760 op. hrs) Multiple load tests No pre-test adjustment, no abort for non-compliance Compliance Amendment Continuous Emission Monitoring Put CO CEMS requirement back into rule (Require (CEMS for engines with a combined rating of 1000 hp) Inspection & Monitoring Plan Required for engines with no CEMS Determine parameter ranges for emission compliance over engine load range (i.e.- O2 sensor voltage, cat. temps, reagent rate (if SCR), etc. 15

16 Amendments to Monitoring, Recordkeeping and Reporting Inspection & Monitoring ( I & M ) Plan Daily monitoring and recording of engine and control equipment parameters, faults and alarms Preventative and corrective maintenance and schedules Weekly Testing (or 150 hrs) using Portable Analyzer Monthly if three successive weekly tests OK Portable Analyzer Training Course Agency Certified Testers Portable Analyzer Testing Protocol Developed Periodic Monitoring Protocol (for Boilers & Engines) 16

17 Technology - Nothing Measures Perfectly All technologies have measurement variability in uncontrolled base forms. Temperature Influences (drift) Cross-sensitivity (to other gases) Flow sensitivity must be controlled Technology specific...saturation, sensor aging Manufacturer expertise Portable EC technology is no different. 17

18 Solution to Eliminate Measurement Variability Manufacturing solutions - Analyzer design and manufacturing innovation help to eliminate measurement variability ICAC Purchase Document Guidance Portable Analyzer for Combustion Emissions (PACE) specifies analyzer requirements. Emission Grade Analyzers can eliminate measurement variability 18

19 Solutions to Eliminate Measurement Variability Procedural solutions -Testing protocols EPA Reference Method 7E CTM - 030, ASTM D6522 (for reference level) CTM-034 (for periodic monitoring) State & Local protocols Recommendation CA SCAQMD Periodic Monitoring Protocol for engines & 1146 for boilers 19

20 What is an Electrochemical sensor? Tens of 10,000s used extensively Safety Ambient air monitoring Combustion applications Emissions & process monitoring Similar to Car Battery - Dissimilar metals set up potential current Electric current generated is proportional to gas concentration permeating through diffusion barrier (oxidization or reduction) Measured parameter is targeted through sensor chemistry 20

21 Technology Specific Solutions for Measurement Variability Saturation (or over-exposure) of sensor At extreme concentrations or long term exposure, the electrolyte chemistry can be temporarily depleted. Long-Term testing with low O 2. Long term exposure to calibration gas (stability testing) The fresh air purge is a process where the sensors breath ambient air to balance electrolyte. Extends sensor life & improves the accuracy. Manufacturers recommended purge rates 21

22 Technology Specific Solutions for Measurement Variability Methods to control temperature influence 22

23 Methods to Prevent & Identify Cross-sensitive Responses Maintain Filters (scrubbers) - remove before depleted (i.e. NOx beads before the CO sensor) External filters replace beads when color changes Internal filters - remove interfering gases inside the sensor Electronically cross compensate by measurement Identify cross sensitivity through the calibration procedure. 23

24 Flow Control and Monitoring EC sensors depend upon ambient conditions for proper diffusion into sensor. Extreme high or low sample flow rates (or pressure) can change diffusion rate. Emission- Grade Analyzers - control flow rate through precision valves and/or orifice plates and flow rate through instrument is measured. 24

25 Sensor Aging EC sensors use chemistry for operation. The chemistry simply wears out, but wears out in linearly. No decrease in accuracy over time. Talk Louder Solution for Aging Sensor Replace sensor Plug & Play New developments 3-year O2, 6-year other sensors 25

26 Sample Conditioning Definition - Process of changing the hot, wet, dirty exhaust gas into a cool, dry, clean gas sample without loosing constituent concentration. Prime consideration in the design of an instrument to deliver accurate measurements Electrochemical sensors require cool, dry gas delivered at proper flow and pressure. Proper sample conditioning results in longer sensor life, higher accuracy and repeatability Remove moisture continuously - Dry Basis for reporting 26

27 Sample Conditioning Dry Basis Data required by most permits Moisture acts as a diluent Moisture reduces measured readings Wet Measurement may Result in False Compliance Wet Basis Dry Basis Oxygen 2.20% 2.53% Carbon Dioxide 13.20% 15.23% Nitrogen 71.10% 82.05% Carbon Monoxide 1.000% =10,000 ppm 1.115% = 11,150ppm Oxides of Nitrogen 0.02% = 200 ppm 0.023% = 230 ppm 27

28 Sample Conditioning Heated Sample Lines Ice Bath type Peltier type Permeation type Peltier type 28

29 Data acquisition has come a long way Look and remember it Chisel it into rock 1 st binary code? 29

30 Software has come a long way 30

31 Software has come a long way 31

32 Data acquisition has come a long way SCR Sampling Typical Outlet Grid Setup 32

33 Industrial NOx Testing applications Selective Catalytic Reduction (SCR) SCR Reactor Source: Riley Power Inc SCR Reactor Source: ABB Alstom Power 33

34 Industrial NOx Testing applications Selective Catalytic Reduction (SCR) Principle of SCR Source: KAWASAKI HEAVY INDUSTRIES, LTD.,

35 NOx Tuning for Process Control (SCR) Multiple (6 Point) Sampling Port different depths of sample points Samples from each point for ~ 1-2 minutes. SCR Reactor Laptop - Controls analyzers Simultaneously collects real-time emission data from up to 16 ports (from daisy-chained t350 analyzers) 35

36 NOx Tuning for Process Control (SCR) NOx Instrument group Calculation through a special program Reactor profile Aim: Adjust Ammonia Whole area should be the same color (lowest NOx concentration here in blue) 36

37 NOx Tuning for Marine Applications Exhaust Stack- Container Ship TYPE Approval GL Certificate approved NOx Technical code 37

38 Benefits - Electrochemical-based Analyzers Technology accepted by US EPA Accepted Periodic monitoring protocols Measures: NOX (NO, NO2), CO, CO2 & others Cross Utilized for Process & Combustion Optimization Lower Cost Alternative $ 8-12 K Thank you for your time and attention Testo Sparta NJ

39 Thank you for you time and attention. Questions: Testo Inc. 40 White Lake Road, Sparta NJ