# Petroleum Refinery Sector Risk and Technology Review

Presentation to the U.S. EPA Science Advisory Board July 19, 2013

# Overview

► 

## Exposure and Risk Assessment Process

► 

## Refinery Emissions: Inventories and Emission Sources

► 

## Monitoring Approa ches

216. 3 Planning and Scoping

Exposure Assessment Toxicity Assessment

Risk Characterization

Quantitative and Qualitative Expressions of Risk/Uncertainty POPULATION CHARACTERISTICS Measures of

Exposure CHEMICAL CONCENTRATIONS Air, Soil, Water, Food (monitor/model) 

## Human Risk Assessment Process

Dose/ Response Assessment

Y

X Chemical Release SOURCES FATE AND TRANSPORT ANALYSIS Hazard Identification

EXPOSURE

information DOSE/RESPONSE information SOURCE IDENTIFICATION

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# Estimating Inhalation Risks under the Risk and Technology Review Program

For the inhalation pathway, the concentration (C) of the chemical in air (in ug/m 3 

## ) at the point of exposure (called the exposure concentration or EC) can be used as a measure of exposure

For chronic inhalation exposure

, usually use an estimate of annual arithmetic average concentration at census blocks centroids to represent the long

- term EC The basic equations for calculating risk from breathing air toxics is :



### Cancer Risk = EC x URE Noncancer Hazard Quotient = EC /RfC

Where : EC = concentration of the chemical in air at the point of exposure (ug/m 3 )

URE = Unit Risk Estimate (risk/ug/m 3 )
RfC = Reference Concentration in (ug/m3) For acute inhalation exposure

, usually use an estimate of highest 1

- hour ambient concentrations at or near the facility fenceline to represent the short

- term EC

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# Developing Exposure Estimates

► 

## We use the EPA Human Exposure Model (HEM) risk modeling system to estimate exposure, which contains:

► 

### AERMOD dispersion model (EPA’s approved local

- scale model)

► 

### 2010 Census data at census block resolution (about 10 households)

► 

### Terrain elevation data

► 

### Meteorological data



### • Uses historical (2011) data from weather stations nationwide


### ► 

## Exposure estimates are conservative

► 

### We assume that there is a person at the centroid of census block who is continually exposed for 70 years

• If the highest concentration is at residence closer to the facility than the centroid , we use that concentration as our exposure estimate

► 

### This reflects the Clean Air Act mandate to assess risks to the ‘individual most exposed’

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# Human Health Benchmarks

► 

### RTR assessments includes benchmarks developed from EPA (IRIS) and other peer reviewed sources (ATSDR, CALEPA), and is compiled and maintained by EPA air program toxicologists http://www.epa.gov/ttn/atw/toxsource/summary.html

► 

### Cancer (URE)

-- Noncancer (RfC)

-- Acute (REL, AEGL, ERPG)

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# Inhalation Risk Outputs

► 

### Chronic

► 

### Cancer: Maximum Individual Risk (MIR)

– highest cancer risk (in a million) at a location where people live (census block centroid or nearest residence)

► 

### Noncancer: Hazard Index (HI)

– highest noncancer risk at a location where people live (census block centroid or nearest residence)

► 

### Annual cancer incidence (cases/year)

► 

### Cancer risk bin distributions (>100 in a million, 10 in a million...)

► 

### Source category and facility wide risks

► 

### Process level risk contributions

► 

### Acute

► 

### Maximum off

- site impact: pollutant

- specific highest 1

- hour Hazard Quotient (HQ) outside estimated facility fenceline

• Default factor of 10x time the annual emissions rate unless source category specific information is provided



### • Can be refined with site

- specific boundary conditions

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# Development of Emission Inventories

► 

## The purpose of the risk and technology review is to evaluate the MACT standards to determine if:

► 

### It is necessary to tighten the standards to protect human health and the environment with an “ample margin of safety”

► 

### There are advancements in practices, processes or technologies that warrant tightening the standards

► 

## Risk and technology review requires emission inventory data

► 

## Emission inventories are developed to satisfy state requirements

► 

### EPA provides guidance in the form of AP

- 42 emission factors, but does not mandate their use

► 

### Inventories are not consistent among states

► 

### Speciation and completeness of data for air toxic pollutants vary

► 

### EPA houses state inventories in the Emission Inventory System (EIS)

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# Refinery Emissions Inventory

► 

### EPA was petitioned in 2008 under the Data Quality Act to improve emission factors from refineries

► In response, EPA developed a refinery emissions estimation protocol, which was put through two rounds of public notice and comment in 2010

• http://www.epa.gov/ttn/chief/efpac/protocol/index.htm

► 

### Refinery Emissions Estimation Protocol

► Provides consistent set of methods for estimating emissions (criteria pollutants and air toxics)

► Requires speciation of air toxic pollutants

► Describes what refinery emission sources should have pollutant emission estimates

► No new sampling is required

► Ranking of methodologies depending on available data

► More detailed and comprehensive than AP

- 42 emission factors

► 

### 2011 Refinery ICR required refiners to use the Refinery Emissions Estimation Protocol to develop their inventory

► 

### Refinery inventory submitted in response to the ICR will be used to perform the risk and technology review of the MACT standards

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# Air Toxics Emissions from Refineries

10 Petroleum Refinery HAP Emissions

Source: 2011 ICR Equipment Leaks

Cooling Towers

Wastewater Treatment Flares

Storage Misc Processes

FCCU

Combustion “Fugitive " sources account for half of the air toxics inventory and most of the

# Refinery Emission Sources

► Point sources (vents or stacks)

► Emissions generally well understood and well characterized, and some test data available where pollutants were directly measured

► Examples include vents at catalytic cracking, fluid coking, delayed coking, catalytic reforming, sulfur recovery, hydrogen plants

► As part of risk and technology review, EPA is amending rules to require electronic submission of performance test data; will be used to periodically update emission factors

► Flares

► Destruction of pollutants in an open flame

► Difficult to directly measure pollutants

► Flare studies available to develop correlations for parameters that affect flare destruction efficiencies (2012 peer review)

► September 2012 NSPS flare amendments will require all flares to eventually have monitors to measure waste gas flow

► Flare operational requirements ensure good combustion and provide information (waste gas composition and flare destruction efficiency) that can be used to estimate emissions from flares

► Fugitive emission sources

► Tend to be open sources or not emitted through a stack or vent, thus difficult to directly measure pollutants

► Examples include equipment leaks and pressure relief devices, tanks and transfer operations and wastewater handling and treatment

► Emission models and estimates are used to predict pollutant emissions

► An emission standard at the fenceline can help ensure fugitive emission standards are being met

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# Fenceline Monitoring

► Fugitive emission sources may not be well characterized in the inventories but are likely significant contributors to overall emissions

• Fugitives from process piping

• Wastewater sources

• Pressure relief events

• Tanks

► Highest concentrations of these fugitive emission sources outside the facility likely occur by the property boundary near ground level

► Air monitoring at the property boundary can provide a direct measure of the annual average concentrations of air toxics directly surrounding the refinery

► Benzene is a refinery risk driver and also primarily emitted from fugitive sources; 85% of benzene emissions from refineries is from fugitive, ground

- level sources, so reducing emissions of benzene from fugitive sources will reduce emissions of other toxic pollutants

► Perimeter or fenceline monitoring provides an indicator of the level of emissions at refineries and is a way to ground

- truth fugitive emission estimates

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### Low

- cost

sensor networks 

## Different technologies and approaches to detect and measure pollutants over extended areas and time

Mobile inspection

systems 

# Monitoring for Assessment of Fugitives

Leak detection power and feasibility of widespread deploymentAnalytical power and implementation cost 

### Current open

path and auto GC systems Lower cost optical systems

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## 0.2 0.5 2 5 10 ( μ m)

UV DOAS FTIR TDL FLIR



### UV Diff. Optical Absorption Spectroscopy Tunable Diode Laser (scanning)
Forward

- Looking InfraRed ( leak imaging) Fourier Transform InfraRed (scanning)

Open

- path optical systems 

# Open

- Path Instruments

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### N 

## Low

- Cost Sensors C an Provide 24

- 7 Observation and Enable N ew R egulatory Approaches

Facility fenceline monitoring Passive sampling

Low

- cost

sensor networks • Locate passive samplers around the perimeter of each refinery

• Calculate annual average concentration

• If rolling average concentration exceeds benzene concentration standard (the action level), initiate tiered approach to positively identify facility contribution and conduct corrective action to reduce emissions

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## Developments in Lower

- Cost T ime

- Resolved M onitoring to Support T ime

- Integrated P assive S ampler F enceline Measurements

Mobile inspection systems SECONDARY MIRROR

PRIMARY MIRROR SEALED UV WINDOW

BEAM SPLITTER DETECTORS

FOCUSING LENS 

### Lower cost
open

- path optical systems Deep UV optical sensor

Drive

- by leak inspection

Drop

- in

- place sensor packages

Prototype PID sensor package (pres. temp. , RH., VOC) 

### Combining senor and wind data

New leak

- location algorithms

Low

- cost stand

- alone

sensors

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## Wind

April 2013 passive sampler and GMAP demo with a cooperating refinery Mobile inspection detected benzene leak at location of the highest passive sampler reading Passive sampler Geospatial measurement (GMAP) mobile benzene
survey Passive sampler fenceline and mobile inspection demonstration

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