Document ID: EPA-HQ-OAR-2009-0234-19974
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-12-21T05:00Z

Date:	December 14, 2011
Subject:	Calculation of Representative Detection Levels for Metals, Particulate Matter, and Hydrochloric Acid Emissions; Electric Utility Steam Generating Units MATS
From:	Roy Neulicht (RTI International)
To:  	Bill Maxwell
	OAQPS/SPPD/ESG (D243-01)
	U.S. Environmental Protection Agency
	Research Triangle Park, NC 27711

Introduction
This memorandum documents the calculation of representative detection levels (RDL) as emission rates, pound per million Btu (lb/MMBtu) for metals, filterable particulate matter (PM), and hydrochloric acid (HCl) emissions. A December 13, 2011, memorandum from Peter Westlin and Ray Merrill, US EPA, Office of Air Quality Planning and Standards entitled "Data and procedure for handling below detection level data in analyzing various pollutant emissions databases for MACT and RTR emissions limits," provides guidance for the handling of below detection level (BDL) data and for developing RDL data.  The referenced memorandum provides several tables that present RDLs for various pollutants in units of mass and concentration for representative sampling times. For the EGU MATS rule, RDLs expressed in terms of emissions rate, lb/MMBtu are needed.  The purpose of  this memorandum  is to document the calculations used to convert the RDLs for PM, HCl, and metal emissions presented in the referenced memorandum in terms of concentration, microgram per dry standard cubic meters (ug/dscm) to an emission rate, lb/MMBtu.   

Calculations

Except for IGCC units, the following equation was used to convert RDLs expressed as ug/dscm to units of lb/MMBtu:

E  =  Cd * Fd * (20.9 / (20.9 - % O2))
Where:
E = Emissions rate, lb/MMBtu
Cd  =  concentration (lb/dscf)
Fd  = F Factor, dscf/MMBtu
% O2  = percent oxygen in flue gas
Conversion: 1 lb/scf = 1.6 x 10[10] ug/dscm

An oxygen content of six percent (6 %) was used for the calculations. 

For IGCC units, the information available was the Fc and flue gas carbon dioxide concentrations.  Therefore, for IGCC units, the following equation was used to convert RDLs expressed as ug/dscm to units of lb/MMBtu:

E = Cd * Fc * (100 / % CO2)
Where:
E =  Emissions rate, lb/MMBtu
Cd  =  concentration (lb/dscf)
Fc  =  F Factor, scf/MMBtu
% CO2  =  percent carbon dioxide in flue gas
Conversion: 1 lb/scf = 1.6 x 10[10] ug/dscm

An Fc value of 2,313 scf/MMBtu was used for the calculations.  This Fc value is the average of the Fc values available from the two IGCC units in the MATS project database. A carbon dioxide content of nine percent (9 %) was used for the calculations. 

Results

The results are calculated and reported as three times (3x) the RDL because EPA's guidance is to compare the calculated MACT floor to three times the RDL value, and to use the higher of the two values.  Tables 1, 2, and 3 present the results for Method 29 metals, filterable PM, and HCl, respectively. Note, to convert the calculated RDL values from units of lb/MMBtu to units of lb/MWh, we derived a conversion factor of 10 MMBtu/MW from the 2010 EU MACT ICR data. This is an average factor derived from data and was needed so the minimum RDLs calculated in accordance with Method 19 could be compared to the output based UPLs in units of lb/MWh.  For all coal, oil and pet coke, we used a 3 x RDL value of 6.4E-4 for PM and 4.0E-5 for HCl. 

Table 1.  Calculation of Three Times the Representative Detection Level for Metals for Method 29 

                               Method 29 Metals
 
        3 x Representative Detection Level (RDL), 4 dscm sample volume
                                       
 
ug/dscm
lb/dscf
                               lb/MMBtu at 6% O2
                              lb/MMBtu at 9% CO2
 

 
 
 
                                   All Coal
                                      Oil
                                   Pet coke
                                     IGCC
 

                                   Fd, Fc =
 
 
                                                                          9,780
                                                                          9,190
                                                                          9,830
                                     2,313
Antimony

 
                                                                        8.3E-01
                                                                        5.1E-11
                                                                        7.1E-07
                                                                        6.6E-07
                                                                        7.1E-07
                                    1.3E-06
Arsenic

 
                                                                        3.0E-01
                                                                        1.9E-11
                                                                        2.6E-07
                                                                        2.4E-07
                                                                        2.6E-07
                                    4.8E-07
Beryllium

 
                                                                        6.0E-02
                                                                        3.7E-12
                                                                        5.1E-08
                                                                        4.8E-08
                                                                        5.2E-08
                                    9.6E-08
Cadmium

 
                                                                        2.3E-02
                                                                        1.4E-12
                                                                        1.9E-08
                                                                        1.8E-08
                                                                        1.9E-08
                                    3.6E-08
Chromium

 
                                                                        2.3E-01
                                                                        1.4E-11
                                                                        1.9E-07
                                                                        1.8E-07
                                                                        1.9E-07
                                    3.6E-07
Cobalt

 
                                                                        2.3E-01
                                                                        1.4E-11
                                                                        1.9E-07
                                                                        1.8E-07
                                                                        1.9E-07
                                    3.6E-07
Lead

 
                                                                        2.3E-01
                                                                        1.4E-11
                                                                        1.9E-07
                                                                        1.8E-07
                                                                        1.9E-07
                                    3.6E-07
Manganese

 
                                                                        2.3E-01
                                                                        1.4E-11
                                                                        1.9E-07
                                                                        1.8E-07
                                                                        1.9E-07
                                    3.6E-07
Nickel

 
                                                                        4.1E+00
                                                                        2.5E-10
                                                                        3.5E-06
                                                                        3.3E-06
                                                                        3.5E-06
                                    6.5E-06
Selenium
 
 
                                                                        6.0E-01
                                                                        3.7E-11
                                                                        5.1E-07
                                                                        4.8E-07
                                                                        5.2E-07
                                    9.6E-07
total
 
 
                                                                              
 
                                                                        5.8E-06
                                                                        5.4E-06
                                                                        5.8E-06
                                    1.1E-05

Table 2.  Calculation of Three Times the Representative Detection Level for Filterable Particulate Matter

                                 Sample Volume
                                       
            3 x Representative Detection Level (RDL), 4 dscm sample
                                     dscm
                                       
ug/dscm
lb/dscf
                               lb/MMBtu at 6% O2
                              lb/MMBtu at 9% CO2
 
 
 
 
                                   All Coal
                                      Oil
                                   Pet coke
                                     IGCC
                                       
                                   Fd, Fc =
 
 
                                                                          9,780
                                                                          9,190
                                                                          9,830
                                     2,313
                                       1
 
                                                                           3000
                                                                        1.9E-07
                                                                        2.6E-03
                                                                        2.4E-03
                                                                        2.6E-03
                                    4.8E-03
                                       2
 
                                                                           1500
                                                                        9.4E-08
                                                                        1.3E-03
                                                                        1.2E-03
                                                                        1.3E-03
                                    2.4E-03
                                       3
 
                                                                           1000
                                                                        6.2E-08
                                                                        8.6E-04
                                                                        8.0E-04
                                                                        8.6E-04
                                    1.6E-03
                                       4
 
                                                                            750
                                                                        4.7E-08
                                                                        6.4E-04
                                                                        6.0E-04
                                                                        6.5E-04
                                    1.2E-03

Table 3.  Calculation of Three Times the Representative Detection Level for HCl

                                 Sample Volume
                                       
            3 x Representative Detection Level (RDL), 4 dscm sample
                                     dscm
                                       
ug/dscm
lb/dscf
                               lb/MMbtu at 6% O2
                              lb/MMBtu at 9% CO2
 
 
 
 
                                   All Coal
                                      Oil
                                   Pet coke
                                     IGCC
                                       
                                   Fd, Fc =
 
 
                                                                          9,780
                                                                          9,190
                                                                          9,830
                                     2,313
                                       1
 
                                                                        1.8E+02
                                                                        1.1E-08
                                                                        1.5E-04
                                                                        1.4E-04
                                                                        1.5E-04
                                    2.9E-04
                                       2
 
                                                                        9.0E+01
                                                                        5.6E-09
                                                                        7.7E-05
                                                                        7.2E-05
                                                                        7.7E-05
                                    1.4E-04
                                       3
 
                                                                        6.0E+01
                                                                        3.7E-09
                                                                        5.1E-05
                                                                        4.8E-05
                                                                        5.2E-05
                                    9.6E-05
                                       4
 
                                                                        4.5E+01
                                                                        2.8E-09
                                                                        3.9E-05
                                                                        3.6E-05
                                                                        3.9E-05
                                    7.2E-05