GCI TECH NOTES ©
by
Jim Woodford and David Constans, Gossman Consulting, Inc.
Craig Chrispell and Carlos Buckelew, Lonestar Industries
In 1991 & 1992, boilers and industrial furnaces faced EPA regulation for their hazardous waste burning activity. In fact, this led to the steel mills dropping the activity. The BIF rule, as it came to be called, was designed to protect human health and the environment. But over the years, the rules kept getting more and more attention. EPA Administrator Carol Browner even managed to flip-flop waste disposal priorities and whereas burning waste and getting rid of it had once been at the top, that activity now found itself at the bottom with land fills coming back in favor. Over the past several years, EPA has been developing MACT rules for boilers and industrial furnaces and now the industry faces new limits with some new ways of calculating how you meet those limits. Some BIFs wondered how their existing BIF (or final permit) data would fare without doing new testing. This paper looks at one facility’s compliance data from late 2000 in order to determine how that data stacks up under the 2002 waste combustor MACT rules.
REQUIREMENTS OF THE HWC REGULATIONThe first thing to do is take a look at the waste/combustor rule (as of April 2002) and compare requirements with BIF. If two or more test sequences are needed to complete all the required tests and there are subsequently two or more sets of data for a particular operating parameter the more stringent is applied as the operating limit. As an example both the DRE test and the PCDD/PCDF test require the establishment of a minimum combustion chamber temperature, whichever test sequence gives the higher average of run averages establishes the limit.
These are the operating limits to be considered:
Minimum Combustion Chamber TemperatureDRE Test - Operating Limit will be an HRA (hourly rolling average) greater than the average of the run averages. PCDD/PCDF Test – Same
Maximum Flue Gas Flow Rate or Production RateDRE Test – Operating Limit will be an HRA less than the average of the maximum HRA for the runs. PCDD/PCDF Test, SVM/LVM Test and Chloride Test – Same
Maximum Liquid HWF Feed RateDRE Test - Operating Limit will be an HRA less than the average of the maximum HRA for the runs. PCDD/PCDF Test – Same
Maximum Total HWF Feed RateDRE Test - Operating Limit will be an HRA less than the average of the maximum HRA for the runs. PCDD/PCDF Test – Same
Maximum APCD Inlet Temperature
PCDD/PCDF Test - Operating Limit will be an HRA less than the average of the run averages.
SVM/LVM Test – Same
Element Feed Rate LimitsMercury Feed Rate - Operating Limit will be a 12 HRA less than the average of the average HRA for the runs. SVM/LVM Feed Rate – Same. Chloride Feed Rate - Same
Minimum Power Limits for ESPsThis requirement was dropped from the rule in an amendment in the May 14, 2001 FR
Minimum Pressure Drop Limits for Baghouses
This requirement was dropped from the rule in an amendment in the May 14, 2001 FR
Maximum Combustion Chamber PressurePressure must be less than ambient pressure
Maximum CO (max 100 ppmv) or THC (max 20 ppmv) in the StackMonitoring is the same as BIF, i.e. PS4B and PS8A. Note: If CO is chosen as the standard the POHC test must demonstrate a <20 ppmv of THC in the stack gases.
The next thing on the agenda is to look at existing compliance data and run it through the limit setting exercises of the HWC MACT rule.
IMPACT OF “AVERAGE OF RUN AVERAGES” ON OPERATING ENVELOPE SPECIFIC TO GREENCASTLE
Using actual 2000 ROC test the differences in establishing the various parameters are demonstrated.
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BIF Operating Values |
HWC MACT Operating Values |
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Minimum Combustion Chamber Temp. °F Run 1, Min HRA, 1682 Run 2, Min HRA, 1675 Run 3, Min HRA, 1675 Avg. Min HRA, 1678 |
Minimum Combustion Chamber Temp. °F Run 1, Avg. 1723 Run 2, Avg. 1722 Run 3, Avg. 1720 Avg. of Averages 1722 |
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Maximum Kiln Feed Feedrate, tons(wet)/hr Run 1, Max HRA, 458 Run 2, Max HRA, 462 Run 3, Max HRA, 458 Avg. Max HRA, 460 |
Maximum Kiln Feed Feedrate, tons(wet)/hr Run 1, Max HRA, 458 Run 2, Max HRA, 462 Run 3, Max HRA, 458 Avg. Max HRA, 460 |
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Maximum ID Fan (alternate to feedrate), RPM Run 1, Max HRA, 897 Run 2, Max HRA, 899 Run 3, Max HRA, 904 Avg. Max HRA, 900 |
Maximum ID Fan (alternate to feedrate), RPM Run 1, Max HRA, 897 Run 2, Max HRA, 899 Run 3, Max HRA, 904 Avg. Max HRA, 900 |
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Maximum Liquid HWF Feedrate, tons/hr Run 1, Max HRA 12.6 Run 2, Max HRA 13.5 Run 3, Max HRA 13.2 Avg, Max HRA 13.1 |
Maximum Liquid HWF Feedrate, tons/hr Run 1, Max HRA 12.6 Run 2, Max HRA 13.5 Run 3, Max HRA 13.2Avg, Max HRA 13.1 |
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BIF Operating Values |
HWC MACT Operating Values |
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Maximum Total HWF Feedrate, tons/hr Run 1, Max HRA 12.8 Run 2, Max HRA 13.7 Run 3, Max HRA 13.4 Avg, Max HRA 13.3 |
Maximum Total HWF Feedrate, tons/hr Run 1, Max HRA 12.8 Run 2, Max HRA 13.7 Run 3, Max HRA 13.4 Avg, Max HRA 13.3 |
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Maximum ESP Inlet Temperature, °F Run 1, Max HRA 416 Run 2, Max HRA 428 Run 3, Max HRA 432 Avg. Max HRA 426 |
Maximum ESP Inlet Temperature, °F Run 1, Avg. 401 Run 2, Avg, 414 Run 3, Avg. 405 Avg. of Averages 407 |
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Maximum By-Pass APCD Inlet Temperature, °F Run 1, Max HRA 426 Run 2, Max HRA 430 Run 3, Max HRA 424 Avg. Max HRA 427 |
Maximum By-Pass APCD Inlet Temperature, °F Run 1, Avg. 389 Run 2, Avg, 386 Run 3, Avg. 395 Avg. of Averages 390 |
ELEMENT FEEDRATE LIMITS
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2000 ROC Maximum HRA Rates |
HWC MACT Operating Limits |
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As LVM (As + Be + Cr) 110 #/hr |
If set based on 2000 ROC data |
Same Data Monitored over a 12 HRA |
|
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LVM – 106.4 #/hr |
104.9 #/hr |
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As SVM (Pb + Cd) 43 #/hr |
SVM – 41.8 #/hr |
41.2 #/hr |
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Chlorine 712 #/hr |
Chlorine– 622.3 #/hr |
579.4 #/hr |
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The set point for the SVM, LVM, Hg and chlorine feedrate limits under the HWC MACT is the average of the three run average HRA input rates. In this case, the 2000 ROC mercury data is insufficient to provide an input rate limit primarily due to concentration values less than detection limit, especially for the raw feed materials. Under BIF it was unnecessary to have a precise input value for mercury from raw materials. HWC requirements are however more stringent. HWC does still have a provision similar to BIF’s Tier IA. See 63.1207(m) where an MTEC may be calculated. Amendments to the HWC MACT have also been made which ease the requirements on how non-detects are handled. See FR 66 No. 128 page 35098. Clearly the 12 HRA will flatten the data.
ADDRESSING EACH MONITORED PARA-METER IN TURN:
Minimum Combustion Chamber Temperature – The lower the value the better. The ideal would be to run as low of a temperature as possible during both the DRE and PCDD/PCDF tests. At the same time however we would want to maximize flue gas flow rate (or production), HWF feed rate and during the PCDD/PCDF test maximize the APCD inlet temperature. (Although maximizing production rate as an alternate for maximum flue gas flow rate will likely be difficult and still minimize combustion chamber temperature.) This should be possible but it will be necessary to sit down and work out the desired values, compromising as required, and plan out how this can be done.
Maximum Flue Gas Flow Rate – This will be somewhat easier because the limit is to be a HRA less than the average of the maximum HRA of the test runs. Here a large amplitude cycle will be an advantage.
Maximum HWF Feed Rate – Because of the way the limit is set the only thing that can be done is to feed at a high rate throughout the test runs. This can be a conflicting parameter with minimizing combustion chamber temperature for some kilns.
Maximum APCD Inlet Temperature – There is no upper limit on this value if the PCDD/DF is below 0.2 ng/dscm TEQ. Even if it is necessary to comply with the >0.2 but <0.4 ng/dscm at 7% O2 and therefore limited to a maximum of 400 F (per the HWC MACT rule, 63.1204(a)(ii)) it is worth while, if possible, to establish a set of “average of run averages” above 400 F so that 400 F is indeed the limit and not some value less than that like 398 F. If however, it is necessary to be at, say 300 F, to be below 0.4 ng/dscm@7% O2 it is still worth while to maximize this temperature limit to provide as much operating envelope as possible.
Element Feed Rate – The 12 HRA limit flattens the data however it is still possible to exceed the limit, particularly if there is a pronounced cycle in the metals feedrate which is not accommodated in the run start and stop times. Consistently feeding these elements at as high a rate as is allowable throughout the runs would be best.
CONCLUSIONWaste Combustor MACT versus BIF makes little or no difference for maximum raw material feedrate, ID fan rpm, liquid HWF feedrate or maximum HWF feedrate. There is clearly an impact on minimum combustion chamber temperature, maximum ESP inlet temperature and maximum by-pass APCD inlet temperature. Clearly, a facility has more flexibility under the new rules, but each facility will still have to decide which operating parameter they choose to dictate operations.