# u"Ëon 

# LYJ UNITED 

### STATES ENVIRONMENTAL PROTECTION 

### AGENCY RESEARCH 

### TRIANGLE PARK, 

### NC 27711 

### JUN 

## 13 20t2 

### MEMORANDUM 

## SUBJECT: Particulate 

### Matter Continuous Emission 

### Monitoring System 

### (PM

# CEMS) orr,".o,

Capabilities AIR OUALITY PLANNING AND STANDARDS 

# FROM: ConniesueOldham,Groupleader 

# (** ;- W

OAQPS/AQAD 

# TO: Bob Schell, Group Leader

OAQPS/SPPD
The purpose 

### ofthis memo is

### to review and summarize current 

### knowledge regarding the 

### capabilities 

### of PM CEMS technology related 

### to Performance 

### Specifrcation 

### l1 (PS I

## l) of Appendix B

### to Part 60 and 

### applicationto new and revised 

### New Source Performance Standards (NSPS) and 

### MaximumAchievable Control Technology 

### (MACT) rules.

### This memo addresses the 

### particular challenges 

### in developing PS I

## I correlationswhen applied 

### to units using 

### fabric 

### filters as

### control devices, 

### to units

### with highly variable fuel or rawfeed materials, and in exhaust streams subject 

### to 

### low PM emissions concentration 

### limits. Background - PS 11 

### and 

### PM CEMS Technolosy
Performance 

### Specification I

## I for PM CEMS isstructured 

### differently than other performance specifications applied 

### to evaluating the performance 

### of a gaseous 

### pollutant Continuous Emission 

### Monitoring System 

### (CEMS). This is 

### primarily because the 

### pollutant, particulate matter, is defined 

### entirely by thetest method specified 

### by regulationto measure 

### it. There are 

### no independent standard reference materials 

### for particulate matter concentrations asthere are

### for gaseous 

### pollutants (e.g., 

### National Institute 

### of Standards and 

### Technology 

### (NIST) traceable compressed gases

### for SOz or 

### NO.). The only reference standard

### for determining the 

### PM concentration 

### in an 

### airor stack gassample isthetest method. 

### Inthe case 

### of the Portland cement and 

### Commercial/Industrial Solid Waste Incinerators 

### (CISWI) rules and many other regulations under 40 

### CFR Parts 60, 61 and 63, that reference method is 

### EPA Method 5

### for measuring 

### filterable particulate matter concentration 

### or mass rate (e.9., 

### in mg/dscm 

### or lb/hr).
The structure 

### of PS I

## I is

### further dictated 

### bythetypes 

### of CEMS technologies used as 

### PM CEMS.

### Two basic types are

### currently sold 

### commercially and are 

### generally installed 

### by 

### industry: light scattering devices and beta gauges.
The output or response 

### of light scattering detectors is a

### function of the 

### index 

### of refraction and size 

### distribution 

## of the particles inthe exhaust stream. 

### In addition 

### to being more sensitive than 

### opacity monitors, 

### light scattering 

### PM CEMS provide more degrees 

### of design 

### freedom. PM CEMS manufacturers account 

### for characteristics such as 

### light wavelength, scattering angle, and 

### solid angle 

### of detection 

### indesigning instruments 

### with desired response features.
There are potential drawbacks 

### to using 

### light scattering devices

### for measuring 

### PM concentrations 

### in industrial stacks. 

### Light scattering techniques 

### effectively respondto 

### particle shape, size and 

### color rather than 

### particle mass meaning that using 

### light scattering 

### to infer 

### PM mass concentrations introduces an 

### additional dependence on 

### particle density. 

### To the extent that stack 

### particles emitted 

### from a process change 

### in density 

### or have 

### multiple and 

### variable constituents, the 

### ability of a 

### light scattering device 

### to provide consistent responses may be 

### limited. 

### Light

lntemet Address (URL) 

## . http://www.epa,gov Recyclêd/R€cyclablo

. Prlnted wilh Vegetable Oil Based lnks on Recycled Paper (Minlmum 25% Postconsumer)-2-

scattering instruments also

### will respond 

### to 

### liquid droplets 

### inthe sample gas stream meaning that 

### in-situ 

### light scattering devices type are inappropriate 

### for saturated or nearly saturãted exhaust streamr. 

## iigltt scatterin! devices that extract and heatthe sample gas

### prior to exposureto the detector may be used on saturateã or nearly sãturated exhaust streams.
The response 

### correlations

### for light scattering devices arealsovulnerable 

### to changes 

### inthe 

### particle size 

### distribution inthe sample stream. 

### Using 

### light scattering instruments on sample ,irearns 

### thai are 

### likely to have 

### varying particle size 

### distributions can be 

### problematic. There are 

### precautionr one can take

### to minimize the effects 

### of changing 

### particle sizes (e.g., by using 

### multiple conelation curïes). Onecanexpect 

### significant variations in 

### particle size 

### distribution particularly from combustion sources 

### burning 

### multiple fùels 

### (eg., mixed biofuel and 

### fossil fuel boilers, cement 

### kilns that burn waste) or a 

### mixture 

### of feed materiaìs and chemical additives. One possible 

### result isthat the 

### correlations

### for light scattering 

### PM CEMS can be rendered 

### unreliable when particle characteristics change eventhough 

### PM concentrations ãnd mass rates remain constant. The effects 

### offhanging pafticle size

### distributions and other physical characteristics on the responses 

### from light scattering devices aie 

### difficult to 

### quantify and are discussed 

### further inthe 

### EPA's technology background cíocuments (e-.g., 

# Itttp:¡¡www.eoa'eov andftWl/wwwTpa.gov/ttn/emc/cemñ4703-02- 

## otu{Ð. Other PM CEMS technologies are based more 

### directly on mass measurement than arethe 

### light scattering 

### pM 

## lltvtS tecnnologies. One 

### of these technologies relies on beta-attenuation and is

### often refegãd to as beta'gauge 

## lM CEMS.

### A beta gauge 

### PM CEMS extracts asample

### from the stack gasand collects the 

### pM on a

### filteräpe. The device 

### periodically advances the tape 

### from the 

### iampling mode

### to an areawhere the sample is exposed

### îo beta 

### radiation.

### After exposure,the detector measures the 

### differenie between a baseline beta count and the beta count

## of the 

### sample. This difference is

### directly 

### proportionalto the mass

### of the 

### pM sample. Beta gauge 

### PM CEMS have aweak dependence on 

### particle composition and astrong 

### correlation to particle mass. The 

### main issues associated 

### with the use

### of a beta gauge 

### PM CEMS or other 

### extractive type 

### pM CEMS are 

### practical ones. 

### Maintainjng isokinetic sampling may be necessary 

### to assure representative measurements. Because the sample is extracted 

### from the stack, there may be some samplà loss 

### inthe 

### extractive probe. 

### Also, the beta gauge 

### PM CEMS detection 

### limit capabilities are dependent on the 

### PM mass collected on the

### filter. That means that one can 

### improve (decrease) the beta gauge 

### CEMS detection 

### limitswith longer sampling times but there may beother 

### physical or 

### regulatory limitations to the degree 

### of adjustment possible. Sjnce beta gauge 

### type instruments are much lesssensitive 

### to changes 

### in particle size and other physical characteristics 

### of PM than are 

### light scattering instruments, beta 

### gaug" pVt CEN4S may be

## *o.. uppropriate 

### for exhaust streams that are 

### likely to have 

### varying particle size 

### distrìbutions (e.g., 

### following an 

### electióstaiic precipitator, sources that combust 

### multiple fuels 

### or apply 

### variable raw feed 

### ir'aterials). 

### Ãny pM CEMS that extracts and heatsthe sample gas, 

### including beta gauge 

### PM CEMS, may be more appropriate 

### for exhaust streams that are saturated or nearly saturated 

### with water. 

### Another PM massdetector projected 

### for greater use 

### in PM CEMS inthe near 

### future isthetapered element 

### oscillating microbalance 

### (TEOM). Often used 

### in measuring ambient levels 

### of PM, the

### TEOù operates on a basic 

### principle that can be made traceable to 

### NIST standards. The

### TEOM can 

### provide 

### acontinuou, 

### rèuru.e of 

### pM mass 

### in asample extracted 

### from the stack and routed to the detector. 

### At ihis time, a

### TEoM-based 

### pM GEMS is not yet 

### commercially available.

PS I

## I provides procedures and acceptance 

### criteria 

### for evaluating the performance 

### of anytype 

### of pM CEMS 

### technology. There are 

### multiple instrument and data 

### reporting operational performance ctreti<s 

### in

### pS I

### I that are 

### similar in concept tothose

### for gaseous 

### pollutant CEMS. There is one 

### prinbipal PM CEMS performance-3-

requirement 

### that is

### distinctly different than 

### in CEMS performance 

### specifications

### for gaseous pollutants. PS I 

### I requires development 

### of a

### site-specific 

### PM CEMS conelation or mathematical response curve. There are

### two key procedural elements 

### to developing that 

### correlation according to PS I

## l. First, PS I

## I requires that the source conduct 

### multiple PM emission test runs using an 

### EPA PM reference test method (e.g., 

### Method 5) and 

### simultaneously collect PM CEMS output data.
The second key procedural 

### requirementspecific to developing PS 

### 1l correlations isthat the source must

### vary the operation 

### ofthe 

### control device 

### or process 

### manually in order to produce a range

### of PM concentrations. PS I 

### I requires at least 

### fîvetest runs at each 

### ofthree different operating 

### conditions (i.e., PM concentrations) that are

### to range

### from 25

### to I00 percent 

### of the 

### allowable emissions 

### for a

### total 

### of I5

### or more test runs.Then the source must usethe test method data and the 

### coresponding PM CEMS 

### ouþut data

### to develop an equation 

### (i.e., acalculated 

### linear or nonlinear curve) that

### will be used

### to define the 

### relationship between the 

### PM CEMS output andthe test method measured 

### PM concentrations. Each 

### site-specific correlation must meet several PS I

## I acceptance 

### criteria including 

### limits on the calculated confrdence 

### interval and tolerance 

### interval. Perturbingthe 

### PM control device operations 

### to produce a range 

### of PM concentrations is more 

### challenging

### for some

### control devices than 

### for others. One canadjust the secondary power 

### to an ESP 

### to produce 

### relatively controllable changes 

### to outlet PM concentrations. 

### Likewise, one can adjust gas

### flow rate or water 

### flow rate

### to a 

### venturi scrubber to produce changes 

### to outlet PM concentrations. Producing a range

### ofPM concentrations atthe 

### outlet of a

### fabric 

### filter control devices is more 

### challenging. For example, there are

### typically no physical adjustments one can apply 

### to a

### fabric 

### filter or

### to an associated combustion process 

### to change the

### outlet PM concentration in the range needed 

### for conelation development. 

### Awell operating 

### fabric 

### filter producesessentially
aconstant 

### outlet concentration even

### with changes 

### to the 

### inlet loading 

### or

### flow (see 

### http://www.epa.gov/ttnchiel/mkb/documents/ff-pulse.pdÐ. Testers have

### applied some techniques (e.g., bypass ducts, loosening seals around bags)

### for perturbing fabric 

### filter control devices, but these can produce unpredictable emissions levels, 

### stratified stack 

### PM concentrations, and altered 

### physicalcharacteristics of the particles.
PS 

### 1l allows some

### flexibility when 

### control device perturbations are not possible. 

### In such cases, the 

### resulting correlation would apply 

### for only the 

### naffow range 

### of concentrations measured 

### during the testing, presumably at a concentration below the

### applicable compliance 

### limit.Without the

### ability to calculate emissions should the

### fabric 

### filter performance change (e.g., bag leaks begin 

### to develop), acomelation based on essentially asingle emissions 

### level would be rendered 

### unreliable 

### for calculating emissions concentrations 

### or emissions rates when emissions are 

### significantly different (e.g., 

### more than 125percent 

### of the highest 

### PM CEMS response)

### from those used

### for the 

### correlation curve. 

### Another challenge 

### to meeting PS I

## I correlation requirements 

### would be

### very 

### low PM concentrations 

### with a corresponding 

### low applicable emissions 

### limit. In addition tothe measurement 

### uncertainty, sample representativeness, and the effects 

### of changing 

### particle characteristics that 

### apply tothe 

### PM CEMS data, the data 

### quality capabilities ofthe reference test method is a

### significant factor in successful development 

### of a 

### PM CEMS Correlation. The 

### Method 5 method 

### detection 

### limit, or 

### MDL, is about 2 mg/dscm 

### for a 

### l-hour test run. The 

### uncertainty of a measurement at

### this 

### PM concentration 

### would be

### from 50

### to 100 percent (i.e., 

### +1to 2 mg/dscm). The 

### Method 5 practical 

### quantitation 

### limit (PQL), using 

## -3 x 

### MDL, would then be 

### approximately 6 mg/dscm 

### with
a measurement 

### unceftainty

### from 

### l0 to 20 percent or 

### +0.6

### to 1.2 mg/dscm. 

### This means that 

### for a 

### PM CEMS measuring compliance 

### with an 

### emission 

### limit equivalent

### to 

### l0 mg/dscm, 

### the inherent 

### uncertainty associated 

### with the 

### Methõd 5 measurement alone

### would be about 

### halfof PS I

## I correlation acceptance threshold 

### of

### *25 percent 

### of the applicable 

### limit.
One can 

### improvethe method 

### detection capabilities of the 

### Method 5or other 

### filterable PM test methods by increasing sampling 

### volume and 

### runtime. For example, the 

### PQL for

### a2 hour test run 

### would be 3 mg/dscm 

### with a 

### measur.,ient uncertainty 

### from +0.3 to 0,6 mg/dscm. 

### A test run

### time of 4 hours 

### would improvethe 

### Method 5-4-



### PQL to about 1.5 mg/dscm and a measurement 

### uncertainty of+O.15 to 0.3 mg/dscm. 

### To achieve a 

### PQL

### of I mg/dscm (as

### would be necessary 

### to demonstrate compliance 

### with 

### a2 to 3 mg/dscm emissions 

### limit), one

### would need

### to conduct a

### Method 5test run 

### of 6 hours 

### or longer. The measurement 

### uncertainty associated 

### with a6-hour 

### Method 5test run at

### this concentration 

### would be

### +0.1to 0.2 mg/dscm. 

### Using data 

### from longer 

### Method 5test runs

## will improvethe 

### probability 

### of a

### PM CEMS meeting PS 

### 1l 

### corelation requirements but

### will also raise 

### practicality concerns.The

### time to complete 

## l5 l-hour test runs under three 

### different emissions 

### conditions would nominally involve three

### to six days 

### offield work. The time 

### to complete 

### l5 6-hour test runs under three

### different emissions 

### conditionswould require at least 

### two weeks 

### offield work and

### very likely longer in order 

### to produce and maintain the operating 

### conditions associated 

### with three 

### different emissions rates. 

### For processes that 

### utilize 

### multiple fuels, produce 

### widely varying particle characteristics 

### or experience 

### widelyvarying load 

### conditions,the 

### effect could be even longer comelation test program durations. 

### For some operations, certain process 

### conditions are available 

### only a

### few hours per week and to 

### complete

### l5 6- hour test runs could take longer than 

### two weeks.
For the 

### low PM emissions 

### level range 

### particularly, the stack concentration 

### levelwould have 

### to remain steady 

### during each test run to capture the relevant 

### corelation values. 

### It is

### worth repeating that meeting PS I

## I corelation requirements becomes 

### increasingly problematic

### with decreasing 

### numerical emissions 

### limits given that confidence and tolerance 

### intervals âre expressed as a percent 

### of the emissions 

### limit.
The 

### quality 

### of the 

### Method 5 data 

### (i.e., precision and accuracy) factors 

### into achievingthe PS I

## I acceptance 

### criteria regardless

### of the 

### type

### of PM CEMS technology used. One may 

### improve the 

### quality of the 

### Method 5 data 

### with co-located dual sampling 

### trains, often called paired trains. 

### With paired trains, one discards any pairs 

### of data 

### showing poor precision, thus, increasing the 

### likelihoodof high quality reference method data. PS I

## I recommends but does not require paired sampling 

### trains. Conducting tests 

### with paired trains 

## will increase the cost

### of PS I 

### I correlation development. 

### Typical costs 

### to perform 

### l5 6-hour 

### (non-paired) test runs are at least $25,000 plus 

### approximately $900 

### dollars

### for each 

### additional test 

### run not including the 

### time required 

### to perturb and

### fix the 

### control device operations. 

### Correlation test costs 

### could increase 

### dramatically 

### if asource has 

### intermittent process operations or uses 

### multiplefuels necessitating development 

### of 

### multiple correlations. 

### Review 

### of Existing 

### PM CEMS 

### Correlation Data
We reviewed a series 

### of PM CEMS correlation tests available 

### to us. 

### Of the eighteen PS I

## I comelation tests we have on hand, the 

### majority were conducted using 

### light scattering 

### PM CEMS. Only three were 

### for beta gauge 

### PM CEMS. Fourteen 

### of the 

### PM CEMS operated on combustion units that burned 

### only coal, threewere installed on units that burned a

### combination 

### of fuels, such as natural gas, sludge and bark,

### while only one 

### PM CEMS was installed on a 

### unit that 

### would be considered abiomass 

### unit. Only one 

### of the sources had a 

### PM emissions 

### limit 

### of l0 mg/dscm 

### or below.The test report 

### for this unit indicated that the 

### PM CEMS correlations met the PS I

## I requirements. 

### Six of the units were subject 

### to emissions 

### limits between I

## I mg/dscmand20 mg/dscm. 

### Five ofthe 

### PM CEMS installed on these 

### units produced correlations that met PS I

## I criteria. Fourteen 

### of the units tested were subject emissions 

### limits of

## 2l mg/dscm 

### or greater.Thirteen 

### of the 

### PM CEMS on these 

### units produced an acceptable comelation.

PS I

## I provides 

### for developing several 

### different correlation relationships (e.9., 

### linear, nonlinear, logarithmic). Fourteen 

### of the eighteen 

### PM CEMS inour database met PS I

## I requirements using a linear 

### correlation relationship. Another two could not pass using a 

### linear comelation 

### relationship but passed using another 

### relationship and the

### final trvo 

### did not pass using any possible 

### relationship. For the 

### correlationsfor which we have 

### raw data, 

### it appears that most used 60 

### minutetest runs.

### -5-

In some instances, the actual emissions 

### during the test were 

### well below 50 percent 

### of the source's emissions 

### limit. As noted above,

### only one

### of the reports 

### we have is

### for a source 

### with an emissions 

### limit less 

### than

## l0 mgldscm.To simulate 

### howthe 

### PM CEMS in other cases 

### would perform relativeto PS I

## I requirements 

### for low emissions 

### limits,we recalculated the 

### correlations using data 

### from tests 

### of a

### few units 

### with low emissions results 

### substituting a 

### lower emissions 

### limit inthe 

### conelation calculation. For

### two of these 

### correlation test projects, the testers 

### collected larger samplevolumes 

### to improve measurement data 

### quality. 

### ln at least one case, the 

### PM CEMS 

### would have 

### failed the PS I

## I corelation requirements calculated using the 

### lower (e.g., 

### < l0 mg/dscm) emissions 

### limit.
Conclusions
In summary, there are

### different analytical technologies used 

### for PM CEMS and each has capabilities 

### variably suited 

### to different stack

### conditions and process 

### applications. 

### It is 

### imperativethat 

### facilities weigh the pros and cons

### of the available technologies when choosing a 

### PM CEMS for their specific application.
We also conclude that acceptable 

### corelations for PM CEMS installed on units 

### with very 

### low emission 

### limits, which burn 

### multiple fuels or

### which have

### varying load 

### conditions, are possible but 

### require special care. One

### factor already mentioned isthe 

### technology selected.

### A second consideration isthe cost 

### of thetesting that may increase 

### dramatically 

### if it is necessary 

### to conduct longer test runs.

### Additionally, thistype 

### of testing requires 

### avery experienced testcrew 

### to ensure that samples are collected and handled 

### properly to minimize the 

### error so 

### critical at these 

### lower emissions levels. Furthermore, as

### we have described above, 

### developing a PS I

## I correlation 

### for a 

### unit that employs a

### fabric

### filter control device may 

### result in a

### correlation that can be used 

### only for a 

### limited range 

### of emissions. 

### References "Current Knowledge of Particulate 

### Matter 

### (PM) Continuous Emission 

### Monitoring." EPA-454/R-00-039. U.S. 

### Environmental Protection 

### Agency, Research 

### Triangle Park, 

### NC. September2000.



### Air Pollution Control Technology Fact Sheet: 

### Fabric Filter

## - Pulsed-Jet Cleaned

### Type" EPA-452/F-03-025. U.S. 

### Environmental Protection 

### Agency, Research 

### Triangle Park, 

### NC.
40 

### CFR 60,

### Appendix 

## B, "Performance Specification I

### I

# - Specifications and Test procedures 

### for Particulate 

### Matter Continuous Emission 

### Monitoring Systems at Stationary Sources." 

### "PS I

## I Data 

### Summary." Spreadsheet. 

### Environmental Protection 

### Agency, Research 

### Triangle Park, 

### NC. June 5, 1012. 

### OAQPS/AQAD/MTG/KGarnett, ext. I158, E'43-02/PM CEMS Capabilities Memo

## - 6-13-20l2ldca