UNITED STATES

ENVIRONMENTAL

PROTECTION

AGENCY Office of Air {)uality

Planning

and Standards Research Triangle

Park, North Ca•o]ina

2771]

ThePm•l Incinerators

and Flares
Jack R. Farmer,

Chtef/•l_•
Chemicals and Petroleu•"B•ch- (MI)-13) II-B-31

The attached

•atertals

provide,

guidance

on the performnce,

of •ic• a• evaluat•

f• a •PS or •. Da•e Nascone's

two memoranda

on themal

incinerator

performance present a good summary

of all the information

we currently

have on thermal incinerators.

Most questions

that may need answering

for a lISPS or NESHAP

should be addressed

in these two memoranda.

These two mmm-anda should be added to the docket of any standard

where thermal incinerators are included

as a control

device

tn a rngulatory alternettve,
A report

ts being prepared

by EEAwhich

is an assessment

of a German .•tud¥.on fl•;

..The.•_.•wt]|.•a!SQ:be distrtbuted:.as

scan. as At•aclmentsAddressees:CPD Section

Ch|efs

and Lead Engineers SDB Section

Chtefs and Lead Engineers •ob Ajax0tin BathDon Goodwi nFred Porter

roe Standards

Contractors Tom 6t1•UNITED STATES ENVIRONMENTAL

PROTECTION

AGENCY

Thernml Incinerator

Pe.-formance

for •6PS
David C. •scon•Ch•cal •nufactur•ng

•,

•B Jack R. Fair,

•ef :h•cals aM Pet•le•

Br'•ch
•er •e p•st f• •n•s,

• has investigated

incinerator

efficiency, cos• •nd fuel use. • pu•se

of this stud• has •n to pick an efficJenc• •at •p•sen•

the h•ghest

c•t•l

level •chJewble

b• •1• • incinerator,

consisting

•vsJl8b]e

•chnolo•,

cos• •nd ene• use. •c 1 us tonsBased on our study, we conclude

that 98 percent

VOC reduction,

or 21:) ppmv by compound

exit concentration,

whichever

is less stringent,

is the highest

control

level achievable

by all new incinerators,

considering avatlab|e technology,

cost and energy use. Thts leve'l is expressed

in both percent

reduction

and ppmv to account

for the leveling

off of exit _.c•_c.en.t_r•t!o•s .as:•..a:]et•.c•m•eetratiees...clrop.:• ..This •vel..-is.

based.•n.. lnclnerazor operation

at a maximum

of 1600"F and .75 second residence time. The costs and energy use of achieving

thts levelare

based "on recuperative heat •covery

capable

of lowering

the flue gas temperature to 510"F.Fr•a our stud•, we also conclude,

that mixing ts a critical

factor in efficiency,

a factor of equal or greater

importance

than other factors such as temerature.

After surveying

available

means of improving mixing,•e conclude

that incinerator

ad•iusta•nt

after start-up

is the most feasible

and efficient.

The control

levels tn the previous

paragraph are based on such an adjustment. F•IOui" s (u • ( also conclude

that. With proper USe Of recuperative heat recove•

(•R). no sl•iflcant

•er• l•naltles

occur •ith changes in c•ustlon

•rat•re.

The reas• is that. based on the technical l•It$ of l•t-•.c•:and

preset

fuel: costs, the _optl•

incinerator exit $•as •rat•re

is sli•tly

above 600"F, regardless

of conOustion t•m)erature. Sln• .!nci•r•or

fuel .t•e de4)end$

• ex-it gas.-and

not C•$t•-•;atU•. •R can essentially

eliminate

• fuel l•nalty of Increa$1no

c•ustl•

•rat•re.-2- D| scuss•onThis

sectio•

discusses

our dal• and findings

on incinerator

efficiency, cost and fuel use, and presents

the logic behind the choice of the above control level.

This section

has three parts, one on efficiency,

one on cost and fuel use, and one on control

levels.

Tables cited in this section are at the end of the memo. In using the conclusions

and data from this discussion,

the reader should be aware of several

qualifications.

First, this discussion

picks

a control

level applicable

t• all new incinerators,

*yen the worst
cases. In reality,

there wi|l be a distribution

of cases from worst to best. Thus, in •any situations,

incinerators

will achieve

greater

than 98 percent,

or less than 20 ppmv, control

at less than 1600"F and -75 • residence

ti•e. Second, this discussion

lists specific

incinerator

conditions (temperature, residence

time, heat recovery)

for analysis

purposes

only, i.e. to calculate

cost, fuel and emission

tr•acts.

This memo does not reco•wend that these conditions

be specified

in regulations.

As just noted, this set of conditions

represents

only oneof men• with which to achieve

98 percent

reduction

or 20 ppmv. Thus, the control

levels in the above conclusions,

not the incinerator

conditions,

should be the basis for regulations.Third, this discussion

focuses

on thermal

incineration

since this control method has the widest applicability

to control

of ducted emiss•,ts .Tais.mema-does

net•c•lude

that. tnclnera•ton.

!s a•p|•¢a_bl.e. to all situations

or that, when applicable,

incineration

is the only feasible control

method.Fourth, this discuss|on

covers incinerators

operating

with relatively constant inlets and flows and with waste gas flows greater

than GO0 scfm. This in general

tncluoes

incinerators

on solvent

drying operations, polymer production

plants,

and.air

ox'..dation

units.

For incinerators with varying

inlet conditions

or small flows, such as those on organic liquid storage

tanks, the fuel and capital

cost calculations

in this memo may not hold. Since these calculations

are a critical

basis for the above conclusions

on efficiency,

these efficiency

conclusions

are Finally, this discussion

covers new incinerators

applied

for control of VOC fo, .•xtdant

reduction

purposes.

Existing

incinerators

may not be physically capable

of achtevtn•

the.. l•mperal;ure,

r•stdence

time and heat recovery conditions

listed in this memo. Thus, these incinerators

may not he able to reach..g8

percent

or 20 .ppmv..Oa

the other hand, incinerators for control

of toxic or haza•lous

VOC need not be 1tin|ted

to 98 percent
or 20 pp•v. As discussed

helow, .htgher efficiency

incinerators

are possible for a•l comounds

with so• devel.ot•ent

and design .cost.-3- •- The available

data on incinerator

efficiency

is described in Table I and summarized

in Tables 2-4. The data include

results

from lab scale incinerator

tests conducted

by Union Carbide

and from field tests run by EPA, LOS Angeles

County and chemical

companies. These data were analyzed

to determine

the impact of incinerator variables on efficiency.

Six variables

were studied,

namely temperature, residence time, mixing,

inlet concentration,

flow regime,

and type of compound, in three analyses.

These analyses

are described

below. Mixing and flow regime are defined

in Appendix

A. The first analysis

was designed

to remove the influence

of mixing. This was desired

since mixing cannot be measured

and thus its impact on efficiency cannot be readily

separated

when studying

the effect of other variables. The Union Carbide

lab w•rk. wa• chosen,for..th.•s

ana]ys•s since, its sin11 size and careful

.design be•t assu•ed

consts•en•

and proper mixing.The results

of the Union Cartlxle

work are shown in Table 2. These results show moderate

increases

in efficiency

with temperature,

residence time and type of compound.

These results

also show the impact of flow regime on efficiency.

This subject

is discussed

further

in Appendix

A on mixing and flow regime.

Ftnally,

the results

show that a given temperature does not correspond

•o a given efficiency.

Rather,

increasing temperature increases

efficiency,

by narrowing

the •'ange over which effictenctes fall and increasing

the average

of the range. The nex• analys•s

focused

on mixing.

To accomplish

this, cases •erelptckedwbere.a11 variablesexceptlmi)dngwe•e.held_cons,cen•.or l.•.• accounted for in other wa•s. It was then assumed

any changes

in efficiency would be due to changes

in mixing. The case most Jtrectly

showing

the effect of mixing on efficiency is presented

in Table 3. The Petro-tex

data show the efficiency

changes due to two mdtf!cattons

of the incinerator

after start-up.

These modifications increased

efficiency

from 70 percent

to over gg percent, with no change in temperature.

The modifications

include

repositioning baffles and burners,

and rerouttng

inlet combustion

air. A case indirectl•

showing

th• effect of mixing is presented

in Ta•b]e 5. These_da•.

cmtzare.the

efficiency

of-.the Roll-.and-Haas

.(RSH) tnct•re•r tn ¢•usttng

f•r s•tfic

¢••

wt• •at-of

the Union •t• 1• •tt. T• lab •tt clearl•

•om

•e • unit. T• • f• • • a• •s• en •e s• •re•,

•st•nce

tim and •nle2 s• condtt•sj

• m• c•le•

•xtng of the •ab •it ts Jud• •e ca•e of •e differing

efftcte•t•, •t•r •se tndt•l•

s•tng

•e effect of mixing is p•sented tn Tab!e 6, •se • a• a •tal

11st of L.A. •t• •sts • efftct•c• d•d

or •t•

t• s• wt• tnc•astng

•rature.

In •] •hts •sult •cur•d

in 21 of •e 50 L.A. • •sts in which-4- the same inctneretor

•s •este• at different

temperatures.

As above, al1 factors

except afixing r•r•ined

t•.• s•me or can be accounted

for in other •ays. Thus, chan•es

in •he com•lete-,ess

of mixing are judged to be t•e cause of the resutts. The final analysis

was designed

to study the effect of all variables at once. The L.A. data were chosen for •is analysis

since the L.A. units operated

over a wide ran• of each :f the variab,es

of interest. In addition,

the L.A. re.s•Its

represented

:he largesC

body of available efficiency data and zhus were the most amenable

to statistical

analysis. The results

of the ana!:vsis

of the L.A. d•ta are show• in Table 4. These results

show a •eak relation

between

efficiency

and inlet concentration and no relation

betwee;•

efficiency

and temperature. The temperature

vs. efficiency.res.ults

.are. surprising.

Kinetic theory.and t•e .lab scale results

show large IBcreeses

inefficiency

over the 300"F range in Table 4, but in fact no such increase

occurred

in the L.A. data. Detailed

analysis

of th•s data •oints to poor mixing as the cause of these result.

This ana•ysts

is described

in Appendix

A to this memo.The conclusion

from these three analysis

is that mixing is the most Important variable

in incinerator

efficiency.

This is based on the large changes

in efficiency

in the R&H and Petro-tex

results

and the ability of mixing to mask the impact of temperature

in the L.A. data. This is not to conclude

that temperature,

residence

time and other variables have no i,...•f]uence

on efficiency.

These var'.'•b]es

do have an important, though smaller,

influence. energY•ned in the Hydroscience

report on theme1

inctneretton. Selected parts of these data are shown in Table 7 and 8. These data were used to analyze

the relations

between

capttal

cost, energy use and heat recovery.

In addition,

the costs of efforts

to improve

mixing were also analyzed.

These analyzes

are discussed

below. The first analysts

studied

the cost trede-offs

between

heat recovery and energy use. The resu|ts

of this analysis

are shown in Table 7. This table lists the tncremnta•

capita|

costs and energy sa':tngs

with increasing recuperative

heat recovery

(RHR).

The 70 percent

I•R case, which. •¢orres _pp.,dS ¢•.. a •11•._ gas .temperature

sl|ghtt•

above .•XI•-F, represents the maximum

feasib]e

|evel of recovery.

Beyond 70 percent

RHR, problems arise with precombustion

in the heat exchanger

and with condensation

of water in the trlue gas and possible

corrosion. The resu•l:s

on Table 7 indicate

that the maximum

t'eastb|e

RHR should be used. Up to. this -max•mJa,

except-for

the t000 scfm case, the capttal cost of each increment

of RNR is more than offset by the incremntaI erie _rgy. savings..

The basis for these savings

is tee increasing

cost of-5- energy. In older designs,

based on cheaper

fuel, cost savings

fr•, heat recovery were not large enoJ•h to justify

maximum

IiHR. Rowever,

with escalating fuel co•ts, e×tr.•-c•pita•

equipment

has become cheaper

than

The results

on table also indicate

that, with the proper use of hea• recovery,

negligible

energ}, penalties

occur with increasing

combustion temperature. The reason }.• that the energy use of an incinerator

depends on exit gas temperature,

no: combustion

temperature.

And as noted above, the optimum

exit c•s te .m•.rature

is slightly

above SOD'F, regardless of combustion

temperature.

Higher exit gas temperatures

are not warranted since additional

heat recovery

produces

a net savings.

Lower exit gas temperatures are prevented

by technical

limits.

Thus, wlth'optlmma

RHR, increasing combustion

t•-•aperatures

will lead to negligible

increases

in energy use.The Second analysis

concerned

the capital

cost differences

between incinerators designed

at 14OD°F and 1600"F.

The results

of this analysis are shown in Table 8. These results

show m•derate

increases

in capital costs and small to moderate

increases

in annuallzed

costs between

the 1400"F and 1600°F incinerators.

The major factors

in the increase

are the larger recuperative

heat exchanger

and larger combustion

chamber needed for the 1600"F degree unit. The final ana]ysis

concerned

the cost and feeslbl]Ity

of various methods to improve

mixing.

Four methods

were studied:

pilot plants, |ab work, engineering

design and adjustment

after start-up. .Pilot..p|a•t.work is •ud•e•.• too .exp•n:i•IYe....

The costs, involve•

.in construCtIng and •}pe•ating

-fJ•-pii•t-plant

unit, providing

a waste gas stream, and col]ectlng

and ana1•rzleg

the data could well exceed the capital cost of the full scale unit. A quarter

to a half million

dollars' could be required

for such work for small Inc|nerators,

and up to a million dollars

for larger units.

Pilot plant work appears

more appropriate as an EPA or vendor research

project. Two of the alternatives,

lab work and engineering

design,

appear affordable but a•e not feasible.

Lab work provides

good data on kinetics, but no useable

data on m•xing.

Engineering

equations

are useful in many situations, but few such equations

exist for m•xlng.

The number of tra•,s in a distillatlo•

colm• can be reasonably

calculated;

the nt•r
The final alternative,

adjusting

the incinerator

after start-up, does al•e•r-both

affordeb•e

and-feasible.--S• an ad•us•n•-•uld involve •sttt•ing

baffle,

a•usting

•c• and •rfomtng

si•lar •Sks •ht !e .•r!.ng.

effacing,

•ra•.•d

s•]ar.,

va•les. •ch a ••

a•li•

to tnc•to•

the •m adJus•n•

•hat p•cess •ut•nt •tm

a•r s•-•

•d •ld t•olve

the sa•, m•rate tt•. e•t•,

.• •s•.

Ft•]•,

•e s•c•s

of such a pr•edu• h• b•n •stra•

by Pet•x.Control Level

l•sed on the above t•tndtn•s,

a series of c•clus•ons

• •ad

• t• c•tce of • •ent

•uc•,

o• 20 (98/•) as •e h•es•

con•

level ach•ev•le

•o• all n• •nc•ra•, conspiring •va•lab•e

•ch•lo•,

•st a-• e• use. •e •clus•
a• •iscuss•

•1•.First, Incinerator

combusl•on

•e•per•ture

has lttt.le impact on cost and energy effectiveness

•t•os.

Th•s ••on

•3 • • •he • c•s •th t•ra•

that •cur •n • • •t•, •ly a•ual•zed cost, ener• use and V• c•t•l

efficiency,

•at rake up •e ratios. • d•sc•sed

a•, •e • tt• all •nc•ase

less t•n 15 •rcent • •e•a•

over a I•'F • I•F ran•.

S•mle m• s•s •t su• sm• c•n•s

•n • ••n

a• •na•

of • c•t and

cos• and essentially

• c•n• •n e• •e (s• T•e 2 and 8 and p•v•s d•scussi•),

a I•'F to 16•'F c•n• tn ••

•es cost •r •und V• c•t•!l•

only 5 • 10 •nt

a• ac•lly

decreases ener• •ses per •und V• cont•lled. Second, the highest

control

11m•t should be based on |nc•nerator operal;•on at •600°F.

Th|s conclusion

|s based dtrecl;ly

on the f•rst, •.e. that over the range of •ntemt

temperature

does not adversely affect cost or ene•w effecttvenoss.

S•ven •s, h|gher temperatures, with htgher control

eff|ctenctes,

ar• preferred. Thts conclusive"

on operating

t•q•erature

ts also based on the --•,ect•caT.-tluflts on.--ueta]

;recupera•ve-.hea•exchange•-,--8asedenthe logic |n the preceding

paragraph,

there |s no upper ]tuflt to the combustion temerature which should be used. Hemever,

above 1600"F,

ceraadc

recuperative heat exchangers

are required.

Since these exchangers

are sere comlex and costly,

and :ess t•ptcal,

than hera1 Oestgns,

the dectston

was made not to rely on *.hem tn considering

the achievable

control

levels.

Thus, 160•F ms chosen for the |nctnerator

operating

temperature.

Th•s conclusion •s further

suppor•ced

by the high control

levels found achievable at thts te•pereture,

as discussed

below. Third, and f•nally,

98 percent

VOC reduction,

or 20 ppmv by compound, whichever ts less stringent,

repments

the highest

a•.htevable

control 1eve1 fo•-.•ll.ne•

.•nc•nerat•r•;.-•ns.•Ser•ng av•.•lable-technelegy., cost and enor•v use. Thts fs based on |nctneretor

operation

at 1600"F,

as discussed tn the preceding

perag•ph,

and on a•us•tmant

of the •nc|nerator after $•a•t•up,

as d•scussed

tn .the s.ectto•

on cost. The dual statement of the conct,s on,

t.e.-.as

percen:

red,ctt

or

accosts

he observed.fall-off of efftc|enc¥

at lo•er tnlet concentrations.

The 98/20-numers l•eeselvesuere

p•cxed by analyzing

three•fferent

co,•ol levels, 99 percent

or 10 plxav, 98 percent

or 20 ppmv, and gS percent

or 30. ppav.Second, the difference

between

65 percent

failing

99/10 and 43 percent failing 98/20 is larger than e direct comparison

of the percentages would reveal.

At 98/20, not only did fewer units fail, but those that did miss the criteria

did so by a smaller

margin and would require

less adjustment. Dropping

the criteria

from 99/10 to 98/20 drops the failure rate by 20 percent,

but is judged to. drop the overall

time and cost for adjustment by over 50 percent. -The difference

between

the two levels is even greater

when the adjustment effort forthe

worst case is considered.

The crucial

point is how close a.gg/lO

level pushes actual field unit efficiencies

to those of the lab unit. Lab unit results

for complete

backmixino

range throughout the 99 range at 160O°F,

meaning

a 9g/lO level would •orce field units to almost match lab unit mixing.

Appendix

A describes

the reasons the complete

backmix

results

were used. Backing

off *-o 98/20 increases the margin,

especially

for the worst cases.

Given that exponential increases may occur in costs to improve,

mixing, as .field units approach ..: lab unit efficlencies,

a drop from 99/10 to 98/20 may decrease

costs to i,•rove mixing in the worst case• by an order of magnitude. '-•-e--gS/•O-ilb•el was judged too lenient.

The only data inCicating such, a low efficiency

was from L.A. All other data showed 98/20.

The nonoL.A, data and lab data meet 98/20 and •he Pe*-ro-tex

experience shewed-that .•re.te._

ed•us1•ent

can ihcrease-.efficle•y abov-egB.-

In addition, in the previous

discussion

on efficiency,

the L.A. units .were j..u.dged, _l;o. fi•.ve poor_ mixing

T•e..mi-xing

.defici.enc•res

were-l•rae--enough-to mae-k the-effect

of increasing

temperature.

Thus, it is ju.dge• that 98/20 could be reached

with ..moder.a_.te

e•ustment

a•d .that a. 95/30 level would represent.a

Criteria.

no• based on thebest

available

unit• consideri#,g cost, enero.y,

and environmeni•1

impact.Table lDescription AJailable incinerator Test Data

86•.; are described

the aJailable

incinerator

test data. Four sets of such data are •resent.

Thes• sets are lab scale incinerator

dat• from tests by Union Carbide

and field unit data fro• tests conducted

by EPA, chemical c•pa•ies and L.L. County. Union. Carbide

Test Data l- These data show the co•..b:•stion

efficiencies

achieved o• •S organic

co•.pounds

in a Jab scale incinerator

operatin•

between

8DD and iSODOF •2 .• :o 2 second residence

time. The incinerator

consiste•

of a 130 centimeter t•i- •t.= t•be in a bench size tube f•rnace.

Outlet analyzes

were done by direct rout:y; of :he incinerator

outlet to a FID and GC. All inlet gases were set at IOOD pPmv.EPA Test Da•{'•hese

data show the co,.•bustion

efficiencies

for full scale incinerators on air oxidation

ve•ts at three chemical

plants.

These three plants
are the Unit•n Caribde,

Talc, Louisiana,

and Roh• & Haas, Deer Park, Texas, acrylic aci= =nits and the Denka, Houston,

Texas unit. The data "or Unior Carbid•

includ•

test results

based on t•o different

incinerator

temperatures and the dat• frc• R•ha & Haas, results

fro• three te.•peratures.

In all tests integrate• )•s •ere use• for s•pling

and a GCI•ID •as used for organic analysis. 5,6.7•8 Ohemic•l C•pany

Test Data These data are fr• tests performed

by chemical c•a•ies

on incinerators

at three air oxidation

units.

The com•anles and units are, lCDnsanto

at their acrylonitrile

unit at Alvin, Texas, Petri•tex •% their oxi•eiive

l•tadle•

unit at •$I•,

Texas,

•K•

at thelr•leic anhydride

unit at )ridge•ille,

Pennsylvania.

The •nsanto incinerator );ms both liouid and Qasecus

•astes from the acrylonitrile

unit •,,d Li)e Kuppers

incinerator

is actually

a boiler adapted

to burn gaseuus in all tests, analysis

.as •rfor•d

by GCRID.

l•ne sa•,•ling

was performed as follcwws:MOnsanto

Cold water scrubbing

AN, ACR, HCR; metal sa•le bo•s remaining co•x}•nds Petro-tex- Integrated

bag inlet; glass syr'nge

outlet Noppers- Glass s•.m•le bombs and charcoal

tubes L.A. •unty Test I)ata g- •he,.•t;

are.fr•over

2• tests.byL.A.•nty
on v•rious

•ste gas incinerator,

•st of •ich are on coating

operations.

Data fr• 1(7 tests •re used, •ith the r•inin•

tests being discarded

since ba•-up •ta •re •jssin•I

the incinerators

were catal•ic

units or similar

reasons.

]n •he L.A. •.a, •,y fl•, t•eracure,

and inlet and outlet VOC c•n•e,tratlon are reposed;

data • c•ounds

and residence

ti• are not present. [•-•t• lit• g•s.c•l-ind•..• us•f•

s•li•

and •iO•!onto

CO 2Table 2Results Union Carbide

Tests* Destruction Efficiency Under State• Conditions F]o•.,' •em•erature Regime** Residence

Time/Co•pound .75 seconds 5 & 3.5 second; Ethyl Vinb, l Acrb'l&t• Ethanol

Ethylene

Chloride

Ethylene T•;•-S+• 13O•

99. c 78 94.6 92.6

.6

•7.2/97.• •a•kmixin• 14Ou

99.9

99.6

99.3

99.C

9•.6/99.8 ISDO 99.9

99.9

99.9

99.9

99.9/99.9 16DO 99.9

99.9

99.9

99.9

99.9/99.9 Co•..•lete 13DO

9•.9

8•.8

84.4

69.9

78.2/91.5 Baci:mixin• l•OO

99.7

96.8

95.6

93.1

93.7/97.8 iS•O 99.9

99.0

98.7

98.4

98.0/99.0 I•9D 9•.9

99.7

99.6

99.6

99.4/9•.B Plug Flow

13•

99.9

99.9

99.5

90.2

97.3/99.9 %•OD 99.9

9g.g

99.9

99.9

99.9/9•.9 I•0• 99.9

99.9

99.9

99.9

99.9/99.9 %•OD 9B.9

99•9

..9•.9

99•.9

99.9/99.9-
*The results

• the Us, Zion Car•i•

work are presented

as a series of equations.

These equations relate destruction

•fficienc•

to t.•erature;

residence

time and flow regime f•r each of l• co•poun•s.

The ef{iciencies

in this table were calculated

frun these e•uations.
•* Three flow re•i•es

are presented,

two-stage

back•ixlng,

complete

back•ixing

and pluo flm,,. T•;o steoe ba•kmixin•

is considered

• reasonable

approximation

of actu•l fi•O units, •ith c•le•e

back•ixin•

and plug flow representing

the extr•es;

The subject o¢ f]o• regime is further

discussed

in Appendix

A.Table 3Results EPA and Company Incinerator Tests
ResidenceTim•/In].etFlow Temperature

•:u•-ber of(FO) Test Rums

Inlet

OutletVOC V0C

% VDC • (ppmv)*** (ppmv)

Control
b•icn 2 to 3 sec/ C•rbide 20,600 1160

6*

11900

243

96.1 1475 3*

11900

10

9g.9
Ro•:n &

I sec/ Haas Tank F•rm Vent,Oxidizer Vemt,(0XVi-=•,OO0

14251510
I•5 TFV 25•O

1330

82.6 OXV 11600TFV 2600

150

•8.3 OXV IZBO0TFV 2410

25

99.7 OXV 122O0
Denka .6 sE:.Z•,DDO 950

13

98.5 T.•nsan%o (Unit }::e)

Confidential

Koppers i• .6 se:/3•:,OO0 IBO0

Uni: 1-6"

Conf.

25

>99 •it 2-8"*

Conf.

47

>99

Iniet-4 •*Outlet-6*

850 Set I 7 99.0Set 2 11 97.2 •:L• •-•.ex

.6 sec/la,4OO 1•,00

•IA SoL 1 10300

1000

70.3 Set 2 10650

2i5

94.1 Set 3 10300

10

99.6 *•ling ¢onducte•

•th grab s•ple bc•rd}S or S•n'tnges. ..• '-•'*I/OC • not Inc•u:e

methane

of ethane.

This definition

of VOC is different

fro• that use• in ea-lier

•.•,.•s or EPA tests, and thus results

reported

here •i differ fro• results in the ear]ier•:o.• •eSt•ction

is by •ei•t perc•t. "The •ta •n Set i an• • for Ko•pe•

were taken dur•n• different

ti• periods. a• •t1• Y• for •et•-tex.r• •s • •thane.

The data in S• one •re taken prior %O adjus•n%

of the inci•rator;

the data in sets t•o and three, after adjus•n:. The s•e:ific

alter•ti•s

• b• Pe%r•tex

a•e •scribed

In referees

• •d •,Table •Results L.A. Incinerator

Tests Destruction Efficiency* Ueder Stated Conditions DestructiDn •fficiency

vs. Tem•ara%ure
Nedian

3rdQuartile 13D•.- 13•D 32

93.0

96.4

98.0 1385 1420 4•

94.0

96.0

98.6 1425 1475 49

91.5

95.0

97.4 1480 and gre,_-_.:- 2:•

9•.5

96.5

98.6

Is• Median

3rd Quartile Quartile
D 399 16

85.t •OD 7)• 21

91.0 800 !199 1•

90.0 1200 1599 16

86.0 1600 1999 9

•3.0 2OOO 2399 II

91.0 2400 3199 12

95.9 3200 3999 9

97.0 4D20 •999 13

95.5 50• 5999 •

9•.9 600• 699• 8

96.0 7000 or more I•

98.2

90.8

96.093.3 97-. 292.5 94.792.9 97.994.5 96.095.5 97.398.497.8 99.098.4 99.297.5 98.197.5 9•.498.7 99.5 efficiency as •eight.percent

carbon. •e •ue•t•es

a•e used ra•her tha•.ave•ages

and standard

deviations •Ju•-Tm•••h•-Ch-•-C,=-T•-•ere--•-•Ie-d.Table 5Resu]t Comparison Lab incinerator

vs. Ro,hm & Haas Incinerator*

Roh• & Haas Lab ]nciT•erator Incinerator Inlet Outlet Inlet

Outlet C.o•,,;pound (•bs/hr)

(l•s/hr) (grams/sec)

{9rams/sec)

pro•ane 900

150 9.0

.08 propylene iBOO**,

150"* 18.0

.70 ethane IO

375 .I

.50 ethylene 33

19O .3

.43 ZT•D 8•5 27.4

1.71
% VOC Destructic•

6•.a% 93.8
*Table shows t•a :eszru:tion

efficiency

on the four listed compounds

for the Ro•f•. & Haas (R•) field and U•ion Carbide

(UC) lab incinerators.

The R&H results are measured;

the •C res•ICs•are

calculated.

Both sets of results

are based on •-•25"F combastiom

le•er•ture

and I second residence

time. In addition,

the UC results

are base• on co•plete

backmixin•

and a four step combustion

sequence •unsistlag of pr•ane

to •ropvleqe

*• e ÷W--- -- --•..• •...- ...: ,¢ne Lo •v 2 =,•G =•.:. ,o--:-• i:•,,,• a•'= •orst case assumptions. **Are not actua•

values.

Actual values are confidential.

Calculations

with actual give similar

results. •aluesTable 6 Results Selected

L.A. Incinerator

Tests*
Te•pera t u re

] nl et "*

(•ut] et ** Test ICc.

{°F}

Concentration

Concentration

Destruction ]lSE 13DO

2300

60 1400 16DD

83

94.9 1214 14OD

i2DD

23

95.2 151• 1200

89

92.7 1215 1400 !500

94

o=•. 9 ISOO ISOO

170

89.I 1329 1300

3100

27

99.2 1325 3700

70

98.1 1375 3800

120

96.9

-• 2700 7

99.7 17•6 1320

7430

83

98.9 1410 6247 88

98.6 1509 7370

104

98.6 1842 ]140

1260

83

93.5. 1285 1090

60

9•.5 I•25 1420

109

93,9 2130 1300 801

3•

93.9 1375 777

66

89.4 1495 890

63

90.7 2235 1400

110/55 97

99.1 l•Sg 10731

254

97.6 2359 I•DO 871

90

85.1 I•50 871

131

72.3 2624A 1ZOO

4110 60

98.1 1450 3090

65

9•.• 2624B 1200 1405

23

9B'.4 • •

18_

* artla,

•s%m 9 o tests w 7re •n¢Iner•tor

te,apera:ure

was Jncrease• chan•e Or a •C•Se

in Y• nOTable ?
Cost Comparison

Incremental Capital Cost and Fuel Savings with Heat Recovery*

!ncineret•rs not Requirino

Supplem•ntal

Air** Inlet Flow Recuperative (SCFM) H_--at Recovery

30

70 1000Incr. •ncr.Capital FuelS15,600 Sll ,500$6,600 $7,500$ID,800 $7,500 2O00Incr. Incr.Capital Fuel$I$,600 $23,000$9,900 $15,000$13,500 $15,000

3000Incr. Incr.Capi tel

Fuel 30 $22,5•0

.c3•,500 50 $12,000

$22,500 ?f), $18,000

$22,500

Incinerators R•ntal Air

Hea% Recover•

SO7O lO000Inc•. Incr.Capital Fuel$35,000 $I15,000S29,000 $75,000$59,000 $75,000

700 5C90 Incr. Incr.

Incr.

incr. Capital Fuel

Capital

Fuel $.13,000 $27,000

$27,000

$178,000 SS,DO0 $I0,000

$12,0OO

$84,000 $2,000 S9,000

$13,000

$77,000

Dc..l•ar figures

are the incremental

annualized

capital

cos:s and inc;ement•l a,mu•l fue• cos% savin•

for increasing

the heat recovery

from the previous lewel to t•e li$:ed level.

For example,

She figure•

on the 50% line are the cos:s end savings

of going f•o• 30% to 50% heat recovery,

and on the 30% line, of going fro• no heat recover•

t• •O% recover•.

Costs are based on an incinerator operating

at l•OO°F and .75 seconds

residence

time. 70• recuperative heat recovery

corresponds

So an exit gas t•perature

of approximately

550OF. Cos$$ based on Reference

10.Table 8 Cost C•mparison

Incremen•al Coszs of CombustionTemperature Inzrease
•mcinerators Requirine

S:•mlemental

Air* Capital Incr. Anmu•lized

Incr. Flov: Cosl

Capital

Percent

Cosz

Annuel

Percent (scfm" 1400OF ** tc 160•°F

increase

140•F ***.

to 160O°F

]ncrease

7 O0

32 S

38

1%

137

i 1 5900 5•3

97

17% 288

28

10% 25',}00 •-",,..-

438

24% 965

127

13% 50000 2•73

855

28% 1741

248

14%

inci•erator• •t Read!rime

S:;D•lemental

Air IOUO 3Z•

36

II% 139

I0

7%

•.• 7C-•

135

19• 363

40

I0%
P 13!0 96 _D•, 330

25• 728 13%

• •,mne•-• ousanc•

o o ars *÷T;•e zc•iLai

cc•t c•l•mm •ho:.• the tmt•l inst•iled

capital

for an incinermtor

om•ratin

9 c;. ;s•,:.;;,

.V• :•ccm:•

rasi•,ae

Li,,•e, recupe)'a•ive

recovery

wizn an exi: gas.temperature of 510°F, and Znm lis%em flow. Th• next column shows the extra capital

for a similar incinerator operati.n§

at 16OOmF.

The fourth column shows the percent

increase

in capital cost from 14DDOF to 16OO°F. ***The annualized

cost column shows the total annual cost !depreciation,

inte•e•t,

taxes, utilities and maintenance)

for 14000F,'.75

seconds,

51D•F exit tmmperature

a;•d the. listed flow. The next columm s•ows the incremental

annualized

cost for a similar incineKator at 16DD•F.

The seventh

column shows the percent

increase

in annualized cost from,. 14OC•F to I•OO•F.Appendix A Mixing is a key concept

in incinerator

efficiency.

Th•s, a discussion of incinerator

efficiency

will likely rely heavily

on this concept. However, Mixing is also a complex

concept.

Thus, discussions

of efficiency

can beco• burdened

with.%echnizal

explanations

of mixing.

To handle this difficulty,

this memo only cites mixing in the •in discussion

and leaves detailed

explanation

of this concept

to this appendix.
This appendix

discusses

mixing in three parts.

The first describes the actual physical

events involved

in mixing and contrasts

proper and improper •ixin 9. The second discusses

a related

item, flow regime,

and explains the importance

of this idea in interpreting

the lab scale data. The third analyzes

the lack of a relationship

between.te.•.•erature and efficiency in the L.A. data and concludes

that poor mixing was the
cause. Mixing can be understood

in terms of the two items required

for combustion of organic

compounds,

high temperature

and sufficient

oxygen. In incineration,

these are provided

by combustion

gases and supplemental •ir. The c•bustion

gases from burning

supplemental

fuel provide

the heat to achieve

high temperatures.

Supplemental

air, when needed, provides oxygen to combust

the supplemental

fuel and VOC's. Mixing concerns

these two streams,

i.e. combustion

gases and supplemental air. Mixing

involves

the speed and completeness

with which these two streams are dispersed

into the waste gas. In proper mixing,

these two streams are broken apart and intermingled

with the waste gas on a molecular level. In addition,

this process

occurs within only a smaI1 fraction

of the incinerator

residence

time.
In contrast,

in improper

mixing,

packets

of waste gas pass through the incirerator

intact.

The turbulence

in the incinerator

fai•s to break the waste gas into sufficiently

small units for intermingling

on a molecular level :o occur.

Poor mixing also results

if this intermingling

occurS too late. If the waste gas is mixed just prior to exiting

the incinerator, then the actual residence

time (R.T.) is much shorter

than the nominal R.T., and complete

combustion

may not occur.

Fine11•

poor lrixlng

results if only one of the t•o required

.streams,

i.,e, combustion

gas or supplemental air, is proper•y

dispersed.

For example,

the waste gas may be proper1• intermingled wi•h ¢•b•stion

gases, but the supplemental

air f]ow ma• be stratified. •he re•It wou•d be incoe•lete

combustion.

Flow regime involves

the large scale gas currents

in an incinerator. In a diagram

of the gas flows in an incinerator,

flow regime corresponds to broad arrows represen%ing

the macroscopic

currents.-2-

Certain flow re_times

have been labelled.

In plu_o flow, inlet .oases remain within fixe• vertical

"slices"

that travel directly

fro• inlet to outlet with no backflo•'.

]n complete

backmixing,

the opposite

occurs. inlet .Gases are rapidly

spread throughout

the incinerator

and significant backf]o• occurs.

DtheF flow re_eimes

are composites

of these.

In two sZa_o• bacK•ixin;,

the incinerator

operates

like two units in series, vo'i:h each undergoing

com,.late

backm, ixin•.

Clearly,

ac:ual flow patterns rare•y ccrrespond

to these idealized

types, but •hese types can serve as •ppr•xi•tions.Flow regim• is related

to bo:h mixing and efficiency.

Specifically, the f•ow reEimes

most favorable

to high efficiency

are the least favorable to •ixing,

and vice versa.

Based on engineering

kinetics,

plug flow achieves the highest

efficiencies

at a given temperature.

However,

to achieve goo• •ixing and still maintain

plug flow, the gases in each vertical "slice"

•st completely

mix with each other while remaining separate from the adjoining

"slices."

Such a phenomena

is difficul:

to create. Es the gases •ix vertically

they also tend to mix horizontally, resul%in• in a flow patte•,

closer to complete

backmixing.

Thus, providin• good •ix!ng inherently

creates

flow patterns

less advantageous

to high efficiencies.Flow regime is important

in interpreting

the Union Carbide

(UC) unit results.

These results

are significant

since the UC unit was designed for optin•

•ixing and thus the UC results

represent

the upper li•i• of incinerator

efficiency.

This upper limit is used in evaluating the costs involved

in adjusting

and desi•ening

an incinerator

to reach a giv• effici•y.

Tim closer this giv• efficier•y

is to the upper li•it, the higher

•he costs will be.
An understanding

of flow regime is required

to choose which part of the UC results

represents

the upper limit.

As seen in Table 2, the UC results vary by flow regime.

Based on the above discussion,

the results under complete

backmixing

were chosen as the upper limit for the discussion in this memo. Though some incinerators

may achieve

good mixing and plug flow,, the worst cases will likely require

flow patterns

similar

to complete backmixing

to achieve

complete

•ixing.

Thus, since this memo is considering

efficiencies

applicable

to all incinerators,

a conservative assumption of complete

backmixingwas

required

when considering

the upper limit of efficiency. L.A. DataThe L.A. d•ta surprisingly

showed no relation

between

temperature and effic•encj¢.

Various

factors

were analyzed

to determine

the cause for this r•sult.In a search for the cause, sampling

error and the incinerator variables of residence

time, inlet concentration

and type of compound were ruled out. For sampling

error to be the cause, the sampling

would have had to consistently

underestimate

efficiency

in high temperature tests and overestimate

it in low temperature

tests.

With over 150 tests, this is essentially

impossible.

For the thr•e incinerator

variables to have been the cause, these variables

would need to mask the effect of temperature. However,

based on the Union Carbide

work and kinetic theory, these variables

only scatter

the efficiencies

around an average determined by temperature.

In the UC cases, the effect of te•erature

is still seen in the increasing

average

efficiency. The remaining

variable

is mixing.

A plausible

explanation

of the results is possible

if this variable

is considered.

The reason lies in two factors

which allow mixing to mask the relation

of temperature

and efficiency. First, the co•leteness

of mixing can drop with te•N)erature. Thus, improper

mixing can offset the effect of increasing

te•erature. In contrast,

the other variables

remain the s• as te•erature

changes and thus offsetting

cannot occur.

Second,

increases

in temperature

only increase the efficiency

of the we]I-mlxed

portion

of the waste gas. Since this portion

contains

only part of the •co•usted

VOC, and likely the smaller

part, the impact of increasing

temperature

is greatly

diluted. In contrast,

the other variables

cannot "isolate"

parts of the waste gas from the affect of te•erature.REFERENCES

I. Predictive

Model of Ti•e-Temperature

requirements

for Thermal

Deszruction of Dilute Organic

Vapers,

Kun-chieh

Lee, Ja.•es L. Ha•sen,

Dennis C. •cCauley, U•o• Carbi•e,

South Sha:-•es•on,

West Virginia. 2. E•ission

Tesz of Acrylic

AciC and Eszer •nufacturi•

P•ant, Union Carbide, T•ft, Louisiana,

Draft Report b• Mi•esC

Resea:-c•,

t•y 1979.

•. Emission

Tes• of Acry]i:

Aci• ant Ester M•nufa•turin•

Plant, •ohm and Haas, Deer Park, Texas, Draft Final Report by Midwest

Research

Institute,

•. Stationary

Source Testin•

of a M•leic •hydride

Plant at the Denka Ch•ical Cor•oration, Houston,

Texas, Final Report by Midwest

Research

Institute.

•. ;•Dvemt.er

8, }979, •etter,

Michael

F. Weishaar,

Monsantc,

St. Louis, •4issouri, to Jack •. Farmer,

•.$. Environmental

Protection

Agency, Researr• Triang}e

Rark, 6. AuguSt 15, lg79,Let:er,

Roger Towe, Pet•o-Tex,

Houston,

Texas, to Jack R. Farmer,

U.S. EnvironmenSa}

Pro•ec$ion

Agency,

Research

Triangle Park, N.C.7. •rch •D, lg•D, Le•%er,

•eorge F. Martin,

PetrooTex,

Houston,

Texas, to Da•i• C. Mascone,

•.S. Environmental

Protec•io•

Agency,

Research Triangle Park, •.C. •7711.

•. •anuar}c

17, lg7g, LeSSer,

Al•o•zo

Wm. Lawrence,

Ko•ers,

Pt•%sburgfl, Pe•.ns•l•nia, %o Don R. •)o•.i•,

U.S. EnVironmental

Protec%ton

A•enc•,

g. Se$ of. sum•rie•

of e•issio•

•est$ I}erfo•med

b• Los A•eles

County personnel fram lg70 %o lg7g.
Knoxville, Tennessee,

I)ece•er

lg7g.UNITED STATES

Ei•V•RONME.•.'TAL

PROTECTIO•

AGENCY

FR Oft.;

TO: JUL 2 2 1•0
Tner•a• incinerator

Perfo.-•.•nz•

for NSPS, Addendur•

D•-vi d C. V•scone•'•
Chemical V•nufacturin.e

Section Jack R. Farmer,

Chief Chemicals and Petrole=•.

Branch, After reviewin•

the recent memo on incinerator

perfo,-mance, (Thermal Incin•_rato•

Perzformance

for RSPS, June II, I•0, DCM, to J•rme.•d• s--6•r•-•--ar-•

where further

eiscussion

was desired. These areas were as •fo]lows: continuous compliance

of thermal

incinerators the impact of compound

on efficiency the impact of inle• concentration

o• cos: effec•ivesness

and efficiencyThese three areas •re discussed

below preceeded

by a s•ar•

of the conclusions.Concl us ion......_._._•s
In the absence

of a demonstrated

continuous

V0C monitor

for •hermal incinerators, CPB is investigating

alternate

meth•s.

After study of. the cost and effective:•ss

of several

such methods,

the followlng

should be considered:

continuous

temperature

and flow monitorin•

and hi-annual compliance testing

and inspection/•tntenance. For example,

in monitoring :emperature and flow, a company

could be required

to run the incinerator be•e. *•0"F of the temperature,

and between

+20 percent

and -50 percent of the fTow, measured

during the performance

test. I)e•tled analysis

shows that type of compound

does aff=ct incinerator efficiency. However,

•ue to the co•lexit•

of the relationship,

no att•,mpts were made in the •une 11 m•mo to d•aw fi•-1•Ut•L•d

efficlenc3' conc1•sion$ relating

different

efficiencies

to different

compounds

at different t•rai•reS.

Rather,

a more ¢onversative

approach

was taken •.which. the efficiency

conclusions

were based on the most dlfficu•t co•=ounds to co.bust.

These conclusions,

based on such a worst case-2- Detailed analysi•

also shows that inlet concentration

affects incinerator efficiency.

However,

unlike •ype of compound,

statistical study of the relationship

between

inlet concentration

and efficiency

was possible. Based on this study, the co•clusions

in the June II incinerator
memo are expressed

in both ppmv and percent

reduction.

This dual format accounts for the effect of inlet conce•zration. Inlet concentration

also affects

cost effectiveness.

One effect is that as inlet concentration

drops the energy content

of the waste gas drops, increasing

supplemental

fuel use. However,

this is not the major effect. By far the largest

effect of inlet concentration

on cost effectiveness is to change the amount of VOC controlled.

Over a typical range of inlet concentrations

•..•. lO,O00 to 500 ppm) a,.• for an incinerator with 70 percent

recuperative

beat recovery,

increasing

fuel use can increase

cost effectiveness

5 to 50 percent

while decreasing

VOC can increase

cost effectiveness

5 to 2000 percent. DiscussionMonitoring One CPB goal is continuous

monitoring

of ai• pollution control equipment.

At present,

we are limited

in achieving

this goal for incinerators

by the lack of a demonstrated

continuous

VOC monitor. Given this limitation,

CPB is studying

alternate

r•nitoring

methods, s•ch as measuring

firebox

temperature,

to indicate

incinerator

performance. To develop

alternate

monitoring

methods,

two goals were considered. First, these alternate,

methods

should detect a11 or most cases of poo r incinerator performance.

Second,

t•e methods

should have reasonable costs and impose reasonable

recordkeeping

requirements. To meet these goals, the variables

that affected

incinerator

performance were anaIvx•d.

The•e variables

are ten•oerature,

mixing,

type of co•ound, inlet co. c ;ration,

residence

time, and flow regime.

Of these variables, the last •:,•ee were judged of little concern

when considering

continuous •w)nitoring. These three variables

are essentially

set after incinerator construction and adjusl•ent

and/or have only small impact on incinerator perfomance. The three remaining

variableswere

then analyzed

in more detail to define their impact on perfomance

and the ability

to monitor Temperature was analyzed

first.

This analysis

was based on data in •he previous

incinerator

memo. Even with good mixing,

the Union Carbide lab da•a and kinetic

•eory show that lower temperatures

cause significant decreases in efficiency.

In addition,

the L.A. data indicate

that increasleg i•emperature

cae also adversely

affect eff•.ciency,

apparently by changing

mlxin•.

In term of cost, temperature

monitors

are inexpensive, costing less than $5000 insta]le•

with strip c•arts,

and are ea•il• and cheaply operated.

Given the ]aroe e•fect of temperature

on efficiency and the ]•w cost of ten•rature

•onitors,

this variable

is clearly

an • •-1:•"ameter•o-•mnil:or;-.• an example,

• spec•.•c

re•ui•,ent

could be that •n incinerator cannot be operatic

for • than • h•u• at an evera•

fi•box

te•ratu-• B)ove 5•'F over, or under 5D•F •i•'. the aver•)

•r•ture

•co•ed •ur!n• perfo•nce

testing,

if an o•rating

ran• g•ater

than 10O'F is •esi•d, • co•anj'

coulC perfo•

perfo•nce

tes• •t • than one te•er•tu•. The •r• .hour ti• •eriod would co-festal

to t• •riod •qui•d

for ir, tegr•tec

)•g sa•ling

in a typical

•rfo•nce

test. This would •ke the averaging period for te•erature

•ni•ring

si•lar

to that of the •rfo•nce te•t. Fin•l!y.

the c•an),

coul• • •qui•d

tc install,

operate,

and c•ICbr•te the •nitor

accor0ir,

g to •nufac•r's

s•cifications.

These •pe:•fic•)ions general i) cover p•per plac•nt

of ihe •nitor. The r•ext variable

studied

was mixing.

Tl• •st likely it• to affect •ixing.

given a constant

•rature

and an already

constructed incinerator, woulC • fi•. No dl•ct field • is •vail•le

on •e e•fect of flo•, on •ixing efficie•y.

H•ver,

bas• on engin•ring judgmr•t, increasing

fl•, •4)' lead to "sNmci•uiting." •m tN increased kinetic

ener•, of 6,igh(r fl• stream

causes was• gas to jet through the incimrator

un•ixed.

•cmased

•" r¢y lead to t• opposite. •'hem i•er fl•' ra•s result in insufficlent

kirtle

mer• for coml•te • i•:ing.

A• •'Ith temeratum,

• mnltom

am Imxpensive

and easily o•rated. •iven the p•tential

Imact of •m-on

efficiency,

and the lo•" cost of fl• mnitom,

fl•, rate i% also an •ffectlve

•ramter

to •or,! tot.A• an exile,

a s;)eclfic

requirement

coulo be that an incinerator cannot be o;•r•ted

for •re •an three hours •t an avera)

flow less tY•n 5D ;>ercent

or greater

•han ll0 l•.'cent

of tl• aver•

wast• gas •' recor•d

du•ng a •rfor•an:e

lest. )l• Nnmisslble

range •uld be intentiOn611y b•ad d• to • lack cf field • • the (matt of flo. on •ixing •nd efflclency.

The .p•r •stricti•

•Id be tighter

than the l•er $ince increase

61• not only •y adve.ely

affect mlxln) but decreases rest•nce

ti•. •y adve•e

effec•

of •c•ased

• •y • offset by the tnc•aseO

•st•nce

ti•. T• above discussion

for temeratu• on ,'i•r, in; t• o•r•ting

ran•, the thr• hour tim ltmtt, and Installation, o•ration •:-J c•tibr•tion

of the •nitor

•ould hold for this • •nftortn e•le.The final variable

ar•l)'.-ed

•S type of c•und.

For most incinerator • ;•llc•tlons,

the c•d•

in the •s• •s • se• by •he p•cess

to •ch the incilrator

is attac•.

Yhus, :yR of C•und

iS of no conce•. •ver,

ce•in

applicatl•s

•y have differing

c•un0s

in
an •K base. a.d •en swit• to a ;olvent

.ith a toluene

base. •K Is oxidizeU ea;l•r t•n •lue•.

and •us an incinerator

which achieves-4- The judgement

on this it• is that no general

monitoring

requirement
on type of compound

can be specified.

Most cases will have the waste gas compounds

set by the process.

In those that do not, considerable difficulty is envisioned

in defining:

in a general

wiy, when the waste gas compounds

have changed

enough to require

additional

compliance tests. For example,

dif•erentiatin•

be•ween

solvent

for•ulations

would be difficult.

The same generic

name ef solvent

may s.how greater

variations in composition

than two different

name specialized

solvents.

However, though a general

requirement

on type of compound

cannot be set, specific requirements may be desired

for certain

standards. Temperature and flow monitoring

do not measure

incinerator

performance directly. Thus, concern

exists over the long term. stability

of incinerator performance, even with temerature,

flow and type of compound

held constant. Data on this issue is shown in Table I. The top pa• of the table shows data from L.A. County where the same incinerator

was tested in different

years.

The bottom part lists possible

incinerator

malfunctions that could affect performance,

without

changing

temperature

and flow. Based on Table 1, incinerators,

if properly

designed

and adjusted, are judged to have fairly stable performance

over time. The L.A. units showed only small changes

in efficiency

over time. The efficiencies

of these units changed

less than two percentage

points over several

years, except one case.

In addition,

the lid.ted malfunctions

are judged to occur infrequently.

This is based on several

factors.

First, these talfunctions involve

non-moving

parts subject

to little wear. Also, the typical was¢e gases are not highly corrosive

and the typical

incinerator fuels, nature1

gas and fue] oil, have low sulfur and ash content. Finally, even t•ough Incinerators

undergo

wide temperature

s•ngs, incinerator components

are designed

to withstand

these changes,

given proper coollng

and heating

of the unit.. The above conclt,sion

should not be overstated.

Though fairly stable, all four L.A. data sets show so• drop in performance

over time. And though improbable,

incinerator

malfunctions

are not impossible. Thus, the conclusion

fro• the data is not that no additional

requirements are needed over temperature

and flow monitoring.

Rather,

the conclusion iS that the costs and recordkeeping

of additional

,onttortng

requirements must be carefully

balanced

against

emissions

potentially

prevented

by them. After l•is balance

was studied,

t•o additional

requirements

were considered. These are hi-annual

perfomance

l•sttng

and hi-annual inspection and mintenaece

(I & M) for incinerators.

The performnc• testing (uld follow the method $l•Ifled

in the standard.

The I &M would involve

visual

Inspecti•

f•r item $•h as corr•)sion

aed firebox deterioration, calibration

and testing

of control

instrumentation,

and so on. Suc• I & M could rest likely be performed

at the s• time as a process tur•ar•n•.-5- These two additional

monitoring

nethods

would effectively

detect drops it. incinerator

performance

no: detected

by temperature

and flow moni%orin.c. Perfor•.•nce

te_•tin.o

is the m•st direct m•ar.s of detecting •oor efficiency.

The I & M will catch drops in performance

by spotting equipment failures

or impendin•

failures

•hat could lead to poor performance. The ] & • has the added advantag=,

that i .mpending

failures

which could •ea• to incinerator

shutdown

would also be spotted.

The two year period •or compliance

testing

and • & M is based on the rate at which incinerator per,•o•ance is likely to deteriorate.

The two year period for & V, also correspon•.s to the typical

•in• betweer,

process

turnaround.•.

Thus, with a bi-annua% .• •; M %he incinerator

! & V. could be performed

at the san• time. •s process

equip•nt

I & M, and it would not be necessary

to shut down the [.-ocess

just •o check the incinerator.

Finally,

the timin@ of the performance test and the I & Y, are no% linkea.

They can be done together in any order or apart.Type of Coln•und

One factor which affects

incinerator

efficiency is type of co•)ound.

The June 11 memo on incinerator

efficiency

excludes this factor fro• its conclusions,

but discusses

only briefly

•he reasons for this exclusion.

This section

discusses

the i•act of this factor on efficiency and explains

in more detail the reasons

for its exclusion. In terms cf the in•ct of c•und

on efficiency,

the available incinerator daT• d•es show a moderate

i•act.

The Union Carbide

lab ¢ata demonstrates

this most clearly.

In cases w•ere different

coa•ounds were incinerated

at the same tea•rature,

residence

time, and flow regime, variations

in. efficiency

of up to • percent

points occurred

for temperatures a•ove ]4OO°F.

At lower temperatures,

the efficienc• variations increased

up to 20 and 30 percentage

points. However, as a practical

matter,

including'co•ound as a factor in an efficiency conclusion

would be difficult.

First, a precise

quantitative relation between

compound

and efficiency

could not be determined.

As with mixing,

no single value could be assigned

to an Individual

compound to represent

ease of co•ustion

Thus, analysis

of the relation

between efficiency and coe•)ound

was limited.

Second,

even if a relationship could be devised,

it would be complex

and difficult

to apply..The relationship would likely involve

kinetic

rate constants,

autoignition temperatures, factors

for •lecularconfiguration and structural

groups an• similar

variables.To avoid these di•flcu]ties,

an alternative

approach

was taken.

No initial a•te•ts

were •de at drawin•

a fine-iyJned

efficiency

conclusion showleg differin•

efficiencle•

a• diff•rin

9 te•eratures

for different coe•unds. P•the•,

a conservative

approach

of choosing

a simple set of in{i•al•r •r•i•ioes

and efficienciesbased on the .most difficul• c•,upounds to coe#)ust

was pursued.

This approach

proved successful.-6- Several factors

aided in the success

of this approach.

First, the available test data covered

a wide range of cou•ounds.

The confounds

on which test data were available

included

C l to C 5 alkanes

and olefins, aromatics such as benzene,

toluene,

and xylene,

oxygenated

co•ounds such as I•£K and isopropanol,

nitrogen

containing

species

such as acrylonitr•l• and ethylamines

and chlorinated

compounds

such as vinyl chloride.

With such a range of con•unds

and the consideration

of kinetics,

it was concluded that worst case c(xnpounds

had been taken into account.

The second factor was the discovery

that increasing

combustion

te•erature

resulted in only negligible

energy penalties

and moderate

cost increases.

Thus, choosing a higher ten•erature

to cover the worst cases did not make incinerators unaffordable

or too energy intensive. Inlet Concentration

A second factor which affects

efficiency

is inlet concentraton.

Unlike type of co•und,

an allowance

for this factor was include•

in the efficiency

conclusions.

Specifically,

these conclusions included

not only an e,•ficiency

of g8 percent

but a m4nimum exit concentration

of 20 ppmv by co•ound,

l•us, as inlet concentration drops, the minimum

ppmv lowers the efficiency

required.

For example, with a 5DO ppmv inlet concentration

for a waste gas containing

oxygen, the 20 ppmv minimum

translates

to a 96 percent

efficiency;

with a 250 ppmv in',6t, a 92 percent

efficiency.

This section

explains

in more detail the reasons

for this allowance

for inlet concentration. The test results

fre• L.A. County form the mjor basis for this allowance. These results

show a strong trend w ._•re lower inlet concentration results in lower efficiency.

For exan•le,

for Inlet concentrations

less t•n 16DO ppmv as carbon,

the median L.A. efficiency

was approximately g2 percent.

For inlet concentrations

between

1600 and 2400, the median L.A. efficiency

was approximately

g• percent.

For inlet concentratlor.s above 2400, the median efficiency,

was approximately

g7 percent. Kinetic considerations

also support

the allowance

for Inlet concentration. The most likely kinetic

model where inlet concentration

does not affect efficiency is a first order model.

However,

availab•e21itera•e indicates that co•bustion

follows

complexreaction

mechanisms.

In cases, these •echar,;sms can be fit to a first order model.

However,

as a general rule, these mechanisms,

which invol:e

rhain reactions,

free radicals

and multiple pathways,

cannot be reduced

to first order •w)dels. The June II, Ig$O, incinerator

memo concluded

that the L.A. incinerators did not all achieve

proper mixing.

T;•.is i•roper

mixing may have caused or influenced

the •lction

between

efficiency

and inlet concentration

in the L.A. data.

Ifthis

i$ the case, then an allowance

for inlet concentration may permlt

lower efficiencies

than are actually

achievable

in incinerators with proper mixing.

However,

the possible

effect of poor mixincj on the relation of efficiency

and inlet concentration

remains

Just that, possible; no conclusive

statement

can be made. Given this, a more conservative approach was taken and lower efficiencies

for lower inlet concentrations were allowed.-7-
Inlet concentration

also impacts

cost effectiveness,

i.e. costs per unit weight VOC controlled.

The precise

impact depends

on molecular weight, the size of the incinerator

an• the ratio of was:e gas energy content to VOC. Figure l show these impacts.
A surprising

conclusion

in the analysis

of inlet concentration

vs. cost effectiveness

is the role of supplemental

fuel. The increasing cost for supplemental

fuel as inlet ppm drops is not a m•jor factor in cost effectiveness.

Incinerator

size and the amo•of

VOC being destroyed are much more important

factors.

An illustrative

example

is a 5000 SCFM incinerator burning

benzene

in nitrogen.

The extra fuel required

when dropping the inlet contration

fro•, 50D0 to 5OD ppmv increases

the cost effectiveness only Z0 percent.

The fact t•t only one-tenth

the benzene is being destroyed

for about the same cost increases

the cost effectiveness lO00percent. Ar, d decreasin§

the stream s•ze to 1000 SCFI• increases

the cost effectiveness

about 300 percent.

Clearly,

increasing

fuel costs at lower ppmv is only a minor factor.
Rolke, R.k'., at. al. Afterburner

System Stud/, U.S. Environmental Protection Agency,

Report S-14121,

Shel• l)evelo•ment

Company,

1971. 2Barnes, R.H., at. al Chemical

Aspects

of Afterburner

S•tems,

IERL Repor• U.S. Environmental

Protection

Agency,

EPA-6OO/7-7g-O96. l•telle

Colm•bus Laboratories, April 1979.ICe

Parz A L.A. Test Data*

Inlet.

Outlet Test No.

Dote

(ppmv carbon)

% VOC

FIow(SCFM)/ Destruction Temp. (OF)

& •icht

1754

I0-30-73

•¢3

33 zurino 2442

7- 7---•6

1030

9• 2443 B-lO-78

716

94 Znc. 2226

5-12-75

6020

52 2402 2-17-76

5860

71 onal Can

1430

6-I0-70

4900

31 1746 •-21-74

7370

104 Can 1451

6-I0-70

3500

22 17• 3-21-74

6247

827370 79

92.5

3270/13(•) 91.4 2020/130D 87.3 2050/ 99.0 1210/1260 ga.• 4150/1375 99•4 2520/1500 98.6 19g0/1500 99.4 4620/1460 98.0 4660/1420 98.0 4650/1525

Part 5 Possible

Incinerator

F•Ifunctions** function Cause Possible

Effect on VOC Control Firebrick Deterioration

Insulazion Loss fro• Incinerator Exterior Improper

heating

& c•ling ,.of incinerator

duringstart-up & shut•;flrebox t•erature

toohighGeneral •eathering

& corrosion fro• rain, cold, incinerator start-up

& shutdown & so on

Deteriorated

wall allow•.local heat loss resulting

in cool spots in firebox,

and thus potentially.- lower destruction

efficiency

in those spotsSame:as previous;

insulation

loss leads to local heat loss & cool s•: in the incinerator
Corrosion of ducts,baffles & otherexposed n•talPlugging cf Burners

Ash, acids, salts, etc. in fuel or waste gas

Ash & carbon buiJd-up

Severe corrosion

of metal parts affects the gas flow patterns through and around them, potentiaT affecting mixing & thus efficient)-
A plugged

or partially

plugged

bu• affects the flow patterns& temperature profiles

in the fireb• potentially lowering

destruction efficiency Breaking of Recuperative •enerel

corrosion;

t•er-

Inlet waste gas leaks into the out7 Heat Exchanger

Seals

ature warping

fro• hot spots flue gas without

passing

through •L•_ej•J•je•• •J•_• r•oL heating & c•ling

during start-up & Shut•
lnc s

were testeo in more•

one year. list• •lfunc¢i•s

include

•ly those •ich •uld likely not affect t•erature

at a li•le [mint flr•ox

te•erature

•itor

or inlet/outlet

flow.Figure l Notes and Explanation Figure shows the cost effectiveness

of thermal

incinerators

by inlet c•centration and waste gas flow. The cost effectiveness

is in hundred

dollars per 2000 pound ton; inlet concentration

is ppmv by compound;

and the flow rate is in SCFK. The costs in the figure assume a waste gas deficient

in air, and

a Compound

with a n•lecular

weiQhC of 80 and a heat of combustion

of.15,000

BTU/Ib VOC. The thermal

incinerator

operates

at 1600OF and .75 seconds

and achieves

70 percent recuperative heat recovery.The.figure can be used to approximate

cost effectiveness

for situations

other than that described

in the above paragraph.

For co•pounds

with different

molecular weights, the x-axis scale should be increased

by 80 over thKmolecular

weight of the compound. -For example,

for a compound

with molecular

weight of 40, the x-axis scale would read 2DOO, 4000, and 6000. For cases where the waste gas contains

sufficient oxygen for coW,simon,

the cost effectiveness

should be decreased'by

the following

• percentages: lO00 SCFM2500 SCFM 14%5000 SCFM 21•lO000 SCFM 26%25000 SCFM 30% This adjustment

accounts

for the sr, aller size and lower fuel requirements

of these
cases. Finally,

for cases where the con•ustion

value of the stream per pound of VOC is higher,

the below listed decreases

approximate

the costs. assume 30,000 BTU/Ib

for ppmv <500

No adjustn•nt for ppmv between

I000 SCFM

5% •00 & 3000

2500 SCF•

10%5000 SCFM

15%I0000 SCF•

20g25000.SCFM 25g These adjustments

for ppmv >3000

No adjustment

This adjustment

accounts

for the l.ow•r fu•l use at higher BTU/Ib levels.