ILLINOIS POLLUTION CONTROL BOARD

January 31, 1974

)

B

•

I. DUPONT de NEMOURS AND COMPANY

)

PCB 73-411

)

ENVIRONMENTAL PROTECTION AGENCY

)

MR. JAMES C. HILDREW, appeared on behalf of E.I. DuPont

MR. MICHAEL C. BENEDETTO, ASSISTANT ATTORNEY GENERAL, appeared

on behalf of the Environmental Protection Agency

OPINION 

AND

ORDER OP THE BOARD (by Mr. Dumelle):

This case concerns a Petition of Appeal filed under Section

40 of the Environmental Protection Act by E.I. duPont de Nemours

and Company (duPont). The Appeal concerns the denial of an

operating permit to duPont by the Illinois Environmental Protection

Agency (Agency).

On November 20, 1972 duPont applied to the Agency for an

operating permit for duPont’s ammonium nitrate prill plant located

in Grundy County near Seneca, Illinois (petitioner’s exhibit 2).

Following a period of correspondence between duPont and the Agency

on the acceptability of the permit application,(pet. ex. 3, 4, 5)

the Agency on June 6, 1973 denied the operating permit application

(pet ex. 6). Subsequently duPont on September 20, 1973 filed

a Petition of Appeal to the Board on the Agencies permit denial

(pet. ex. 8). Public hearings on this matter were held November 27

and 28, 1973 in Morris, Illinois with final arguments from both

parties due January 15, 1974.

The Agency denied the permit because in their opinion the

Prilling Tower, a portion of the plant, was not shown to be in

compliance with the Air Regulations (pet. cx. 6). DuPont’s

permit application, using duPont’s calculations, did show

compliance with the Air Regulations. The issue, therefore, is

whether or not the Prilling Tower is in compliance

because if it is, as duPont alleges, then the Agency acted improperly

in denying the permit application on that basis, and the permit

appeal should be granted. If the tower is not in compliance,

as the Agency alleges, then the appeal should be denied.

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The rule to be complied with was itself a subject of 

conten-

tion; with the Agency contending that the old particulate emission

rule, Rule 3-3.111, is still in effect and duPont contending that

the new particulate emission rule, Rule 203(b) is operative.

Both rules relate the allowable particulate emissions to the size

of the process, defined in terms of the process weight rate, with

larger processes allowed to emit greater amounts of particulates.

DuPont used an erroneously high process weight rate, in the

Agency’s opinion, in showing compliance with the particulate emissions

limitation. They did this the Agency contends by including the

cooling and drying air flowing through the process. The

Agency maintains that this air, which constitutes 93 of the total

process weight rate, should not be included. DuPont calculated

a maximum process weight rate of 1,599,000 lb•/hr, including

1,494,000 lb./hr. of process air for cooling and drying, 67,000 lb./hr.

of ammonium nitrate prills, and 38,000 lb./hr. water vapor which

is evaporated in the process  (pet. ex. 2, page 9). The allowable

emissions according to duPont would therefore be 75 lb•/hr. (actually

74.7 lb./hr.) (Petition of Appeal). Based on stack tests at the

plant, duPont estimates maximum particulate emissions of 73 lb./hr.

from the plant (Pet. Ex. 2) (69 lb /hr. according to. the Petition

of Appeal). The Agency says that the process weight rate should

exclude the cooling and drying air and is therefore only 105,000 lb./hr.

The allowable emissions would then, according to either Rule 3-3.111

or Rule 203(b), be only 45 lb•/hr. and thus the plant is not in

compliance.

The overall process for manufacturing ammonium nitrate (AN)

prills involves the following steps: 1) anhydrous ammonia and nitric

acid are combined to form an AN solution, 2) water is evaporated to

concentrate the AN solution to 96-97., 3) droplets of solution,

formed by spray heads at the top of the prill tower, fall through

the tower, cooling and solidifying into pellets or prills as they

fall through a countercurrent flow of air, 4) the prills are then

further dried and cooled and finally 5) coated with clay (R. 32-37,

43-45).

The bulk of the process air used and particulates emitted

originate in the prill tower, so that the hearing was concerned

primarily with this portion of the process. The AN solution

enters the spray nozzles at the top of the prill tower at about

1550C and the droplets being to solidify in the tower when

they cool at 137°C;at which point they could be considered

prills (R. 36-37). They further cool and dry during failing so

that at the tower exit the prills have a temperature nE 70°C

and a water content of 2 to 2.5 (R. 43).

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Much testimony concerned the characteristics of prilled AN.

The prills produced by duPont are used in industrial applications,

mainly in explosives manufacturing, and are required to have a lower

density and higher porosity then AN prills used in agriculture.

The prills are also required to have a high resistance to breakup

(R. 45-47).

There are several areas in the process where the prill

characteristics are controlled: the concentration and temperature

of the AN solution leaving the evaporator, the temperature of the

prill as it leaves the prill tower, and temperature and moisture

removal rate in the pre-dryer, dryer and cooler (R• 50). In each

case air is used to dry and/or cool the AN solution or prills and

on the operating permit application duPont included the total air

used in these units, excluding ~erroneouslythe evaporator, as part of

the process weight rate (R. 244). It seems, however,, that the main

control point is the prill temperature at the tower exit. The desired

prill temperature at this point is 60°-70°Cwith lower temperatures

resulting in the operator decreasing the airflow and a higher tempera-

ture resulting in the operator increasing the airflow in the prill

tower. It has been found that higher temperatures mean a softer pellet

will be produced and at lower temperatures a harder pellet (R. 57).

The amount of air flow in the prill tower is controlled by a

series of fans and louvers. There are eight fans at the top of the

tower which operate in various combinations to pull air up through

the tower; in addition there are air inlet louvers at the bottom

of the tower and louvers in front of the exhaust fans to help control

the airflow (R. 51, 162). The total rated capacity of the 8 fans

is 240,000 cfm or about 1,150,000 lb./hr. (R. 76), with denser air

in winter resulting in higher mass flows than occurs in summer.

DuPont says that the production rate of prills is largely

controlled by the available airflow in the prill tower (R. 66);

but it is really the available cooling capacity in the tower that

is important. The maximum prill production rate experienced is

approximately 725 tons per day and can be reached “anytime that the

temperature (ambient) gets down to 30°For below” (R. 78) and with

anywhere from six and a half to seven and a half fans operating.

On the other hand when the ambient temperature is around 

750

to 800P,

the production rate begin to be limited even with all eight fans

operating (R. 71).

The Agency played down the uniqueneSs of the air

used in the prill tower. Mr. Mellott of duPont stated that the prill

tower could not be operated in a vacuum but that it was possible

that another gas such as nitrogen could be used (R. 107-108).

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It was also learned that during the period from 1968 to 1972,

the production rate of prills was increased without increasing the

maximum capacity of airflow (R. 265).

The Board finds, based on the above process information,

that the air used in the prill chamber serves to cool the AN

liquid into solid prills, and controls to some extent the

characteristics of the prills produced. This air is important

to the process in the same way that heated air is important to the

drying process such as in a grain or sand dryer. In cases before

the Board involving emissions from dryers such as these, e.g.

PCB 72-215, EPA v. Weldon Grain Co-op, and PCB 72-392 EPA v.

Aurora Metals, Paskure Division, air used in the dryers was not

included in the process weight calculation; and we do not believe

that air used in the prill plant in the instant case should be

included in the process weight rate either.

DuPont’s position on the inclusion of the cooling and dry-

ing air  is based on the definition of process weight. The

difference between the definitions in the old and new regulations

is shown below.

1)  Rules and Regulations Governing the Control of Air Pollution

(old regulations) Section 1

Process Weight 

The total weight of all materials introduced

into any source operation. Solid fuels charged will be

considered as part of the process weight but liquid and

gaseous fuels and combustion air will not.

Process Weight Rate 

(a) For pontinuous or long-run

steady state source operations, the tctal process weight

for the entire period of continuous operation or for a typical

portion thereof, divided by the number of hours of such period

or portion thereof. (b) for a cyclical or batch source

operation, the total process weight for a period that covers

a complete operation or an integral number of cycles., divided

by the hours of actual process operation during such a period.

Where the nature of any process or operation or the design

of any equipment is such as to permit more than one interpre-

tation of this, definition, the interpretation that results

in the minimum value for allowable emission shall apply.

2)  Air Pollution Regulations (new regulations) Rule 201

Process Weight Rate: The actual weight or engineering

approximation thereof of all materials except liquid

and gaseous fuels and combustion air, introduced iuto any

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process per hour.

For a cyclical or batch operation, the

process weight rate shall be determined by dividing such

actual 

weight

or

engineering approximation thereof by

the number of hours of operation excluding any time during

which the equipment is idle. For continuous processes,

the

process

weight rate shall be determined by dividing such

actual

weight or engineering approximation thereof by the

number of hours 

in one complete operation, excluding any time

durin~ which the equipment is idle.

The Agency argues that the old regulations are still in effect

(TI. l25~l26) so that the old definition of process weight rate,

especially the last sentence of the definition,

could be used to

exclude the air from

the

process weight rate,

DuPont maintains

that

the

definition section of the new air regulations became

effective April, 1972 (TI. 126), and that the new definition

process

weight 

rate does not include room for interpretation.

They

also reference the Opinion 

in PCB 73-.71

Johnson 

and

Johnson (Pet,

Ex. 1) as indicating that the Board interprets

the definition of

process weight rate to include all mateiials except those

specifically

excluded i.e. everything is included except liquid and

gaseous fuels and combustion air.

The Agency responded by re-

ferencing

the

June 29, 1973

Order of 

the Board in this Johnson and

Johnson

case (Pet. lx I) which says that 

the Board interpretation

applies only to

the

sneci a I

ci i’cums 

tances

at

Johnson and Johnson,

it is tic I

nion 

ci~t the ucl~nitions do not stand alone

but cxi st in terms of tliei r use in particular

rules.

Therefore

since for cxi stin

sources the compliance date for particulate

em~ssJon5

~s Occember 3, 9~3~ we 

Find that prior to that time

diPont ~

c 1~ion limits and de~nitions contained

in the old Ru cc and legui at i ons Governing the Control of Air

Pollution. tIe Inenry points this out 

the

fol lowing excerpt

from the le

ttc cf den lot to duPont (Pet. 

Ex. 6)

The

part 

c ul ate

emissions from the 

process described in

the

above role 

conned operating pennit application are

covered by

the particulate 

emission standards and limita-

tions

contained 

Chapter 

2 of the Regulations of the Illinois

Pollution 

Control Board and in the Rules and Regulations

Governing 

the Control

of

Air Pollution until superseded by

the provisions of Chapter 2.

In your operating permit application,

you have not shown

that the following significant

emission sources are

in

compliance with presently applicable standards:

Prilling Tower

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The Agency chose to use this case as the forum to respond

to the Board’s request for information on process weight rate in the

July 19, 1973 Opinion in PCB 73-71 Johnson and Johnson (Pet. Ex. 1).

Therefore, one of the exhibits entered into the record is the

Bay Area Air Pollution Control District Regulation 2 (EPA Ex. 4)

for the purpose of historical background. Not much insight is

provided by this document, however, since the definitions of process

weight and process weight rate are identical to those in our Rules

and Regulations. The Agency contention is that in establishing the

new process weight tables in Rule 203, non-reacting air was not

included (R. 294). The process rate tables were designed to result

in meeting the federal ambient air quality standards and did not

include the weight of air (R. 327). If non-reacting air had been

included in establishing the tables, a more stringent regulation

would have resulted (R. 328). That air should not be included seems

recognized by almost all industries since less than 1 of the

applications for operating permits include process air as part of the

process weight rate (R. 387). In addition, the Pgency in determining

the technical feasibility of the then proposed process weight tables

did not include air (R. 310).

After considering the record in this case, we find that process

air should not be included in the calculation of process weight

rate; therefore, duPont’s emissions exceed the standards, the

permit was denied properly, and the Board hereby denies duPont’s

appeal. The Board also finds that in using the process weight rate

tables of Rule 203 of the Air Pollution Regulations, the definition

of process weight rate shall be interpreted as never including the

weight of non-reactive air such as that used for drying and cooling.

This opinion constitutes the Board’s findings of fact and

conclusions of law.

ORDER

IT IS THE ORDER of the Board that duPont’s Petition of

Appeal is denied.

IT IS SO ORDERED.

I, Christan L. Moffett, Clerk of the Illinois Pollution Control

Board, hereby certify the above Opinion and Order were adopted

on the ~3/~~” day of January, 1974 by a vote of 

Illinois Polluti

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