1 

# Review of OGI Wind Tunnel Tests

and 

# Refinery and Chemical Plant OGI and Bagging Studies

Jeff Siegell – ERM EPA – API Meeting August 18, 2011 - RTP, NC2 

## Conduct Wind Tunnel Tests

– Controlled wind conditions



## – Known species

– Controlled leak rate 

## Conduct Plant Tests

– Field wind conditions

– Typical plant process streams

– Real-world leaks 

# Can Optical Imaging Meet/Exceed AWP Required Performance?

Photo courtesy Leak Surveys Inc.3

Species Lowest Detected

Mass Leak Rates (g/hr) Methane 0.3 - 49 Ethane 0.6 – 17.8 Propane 0.4 - 19 Butane 0.4 - 15.9 Pentane 3 - 45.8 Hexane 1.7 - 57.8 Heptane 1.8 - 48 Octane 1.2 - 62.2 Propylene 2.9 - 59.8 Toluene 3.8 - 75.3 Xylene 1.9 - 75.3 Data for FLIR GasFindIR camera, from papers presented at “Smart LDAR Symposium,” AWMA 99th Annual Meeting, New Orleans, June 2006. 

# Wind Tunnel Tests for Instrument

Detection Limits

Detection Depends on Wind Speed & Distance from Leak

– Less sensitive at higher wind speeds

– Less sensitive at longer distances but can be addressed with alternate camera lens 

### Easier to Find Leaks in Field Compared to Wind Tunnel

– Less uniform wind speeds in field

– Less uniform wind direction in field4

Compound Lowest Detected Mass Leak Rates - g/hr(a) 1,3 – butadiene 1.3 - 2.7 Acetic acid < 0.02 - < 4.6(b)(c) Acrylic acid 0.92 - 1.2 Benzene 0.35 - 35 (c) Methylene chloride 4.9 - >70 (c) Ethylene 0.35 - 278(c) Methanol 0.28 - 22 (c) Pentane < 0.28 - 28(c) Propane < 0.44 - 13(c) Styrene 0.35 - 0.70 

# FLIR GasFindIR MW Camera Method Detection Limits from ETV

(a) Detection limits determined at zero mph wind speed unless otherwise noted (b) Measured at 2.5 mph wind speed (c) Measured at 5 mph wind speed Adapted from Table 1 of ETV Verification Statement, 12/1/10
Test variables include wind speed, background, and distance5 

## US Gulf Coast

– 

### Project plans reviewed and approved by EPA

– 

### Completed as part of SEP 

## One Week Test – Spring 2006 73,000 Piping Components Monitored

– 

### 11 different process areas 

## 28 Leaks Found by Optical Imaging

– 

### Method 21 for leaks found by OGI

– 

### 16 leaks bagged to obtain mass emissions rate 

## Monitoring Rate: 3,600 components/hour 

# Chemical Plant Test Description6 

# Chemical Plant Test Results Methane - 3.7 g/hr Propane - 4.7 g/hr 

## Butane - 10.6 g/hr Propylene - 23.8 g/hr Toluene - 50.2 g/hr 

## Xylenes - 17.8 g/hr Note: These rates are for leaks found during the test program and do not necessarily reflect the smallest leak that could have been found by the instrument. Data from Environmental Progress, Vol. 26, No. 2, July 2007 

## These Leak Rates are all Within the Range of the Wind Tunnel Results Lowest Emission Rates Found by OI During Test Monitoring Rate = 3,600 components / hour7

US Gulf Coast Refinery

– Completed as part of SEP for Consent Decree

– Project plans reviewed and approved by EPA

– EPA participated during data collection Two Test Periods - Each One Week Long

– Fall 2006

– Spring 2007 Plant Areas Monitored

– Alkylation unit

– Cat Cracker light-ends fractionation

– Crude light-ends fractionation

– Hydroforming unit

– Tank farm > 110,000 Piping Components Monitored Method 21 for All “Leaks” Found by OGI and Also for “Non-Leaks” That Were Bagged 

# Refinery Test Description8



# Refinery Test Results 72 leaks found with optical imaging

− 0.065% of total components

− Consistent with API SCAQMD study: 0.13% above 10,000 ppmv 

### Actual mass emissions measured by bagging of 70 components

− 40 leaks found with optical imaging; preferentially bagged the smallest leaks found by optical imaging

− 30 leaks found by Method 21 monitoring that optical imaging did not show leaking; preferentially bagged the largest leaks not found by optical imaging 

### Smallest leak detected by optical imaging was 0.18 g/hr as 

### measured by bagging “Marginal Detects”

− Leaks visual by some instrument operators but not others

− Leaks found first by Method 21 after initial miss by instrument, then found by instrument operator after closer inspection 

### All leaks above 11 g/hr were detected by optical imaging9 

# Detection Sensitivity Well Below 60 g/hr

Data from Environmental Progress & Sustainable Energy, Vol. 28, No. 2, July 2009. Detects Marginal Detects Non-Detects Leak Rate g/hr Monitoring Rate = 4,500 components / hour10



# Other Refinery Findings  Monitoring Efficiency

– 24 hours of data collection over 8 days

– 4,500 components / hour

– Compared to Method 21 monitoring • Method 21 typically 400-600 components/day • Method 21 requires “touching” each component 

###  Method 21 Reading Not Always a Good Indicator of Relative Leak Rate

– Some high concentration Method 21 components had lower mass leak rates

– Some low concentration Method 21 components had higher mass leak rates 

###  High Method 21 components not detected by Optical Imaging confirmed by bagging to have relatively low mass rates (i.e. “False Positives”)11



# CONCLUSIONS Chemical Plant and Refinery tests confirm ability of optical imaging to find leaks in field at AWP-required emission rates Chemical Plant tests show sensitivities within ranges of wind tunnel tests for individual species - can initially predict field 

### performance from wind tunnel tests Wind tunnel generally provides conservative conditions for leak detection – uniform wind speed and direction Leaks at AWP level are quickly and easily found using optical imaging  No need to focus excessively on each component 

###  Many components can be monitored in a single view