Definition
of
Batch
&
Continuous
Process
Vent
in
the
MON
1
Continuous
Process
Vents
EPA
Should
Define
"
Process
Vent"
Consistent
With
the
HON
We
recommend
a
process
vent
definition
similar
to
the
HON
and
GMACT
for
the
MON,
and,
that
the
issue
of
requiring
control
of
certain
batch
storage
vessels
using
the
process
vent
requirements
be
handled
through
the
specification
of
control
requirements
not
through
use
of
unusual
process
vent
and
storage
tank
definitions.

"
Process
vent
means
the
point
of
discharge
to
the
atmosphere
(
or
the
point
of
entry
into
a
control
device,
if
any)
of
a
gas
stream
from
a
unit
operation
within
a
miscellaneous
organic
chemical
process
if
the
gas
stream,
at
such
point
of
discharge
(
or
such
point
of
entry
into
a
control
device,
if
any),
contains
greater
than
0.005
weight
percent
total
organic
HAP.
(
Examples
of
a
process
vent
include,
but
are
not
limited
to,
a
vent
on
a
condenser
used
for
product
recovery,
a
vent
on
a
reactor,
a
vent
on
a
filter,
and
a
vent
on
a
centrifuge.
Process
vent
excludes
the
following
gas
stream
discharges:
(
1)
A
gas
stream
discharge
from
a
wastewater
stream,
waste
management
unit,
or
liquid
stream
subject
to
the
emission
limitations
and
work
practice
standards
in
Table
3
of
this
subpart;
(
2)
A
gas
stream
discharge
from
a
storage
tank
subject
to
the
emission
limitations
and
work
practice
standards
in
Table
4
of
this
subpart;
(
3)
A
leak
from
equipment,
a
closed
vent
system,
or
a
heat
exchanger
system
subject
to
the
work
practice
standards
in
Table
5
of
this
subpart;
(
4)
A
gas
stream
discharge
from
a
transfer
operation
subject
to
the
emission
limitations
and
work
practice
standards
in
Table
6
of
this
subpart;
(
5)
A
gas
stream
discharge
from
a
combustion
device;
(
6)
A
relief
valve
discharge;
(
7)
A
gas
stream
going
to
a
fuel
gas
system
as
defined
in
§
63.101;
(
8)
A
gas
stream
exiting
a
control
device
used
to
comply
with
Tables
1
or
2
and/
or
7
of
this
subpart;
(
9)
A
gas
stream
transferred
to
other
processes
(
on­
site
or
off­
site)
for
reaction
or
other
use
in
another
process
(
i.
e.,
for
chemical
value
as
a
product,
isolated
intermediate,
byproduct,
or
coproduct,
or
for
heat
value);
(
10)
A
gas
stream
transferred
for
fuel
value
(
i.
e.,
net
positive
heating
value),
use,
reuse,
or
for
sale
for
fuel
value,
use,
or
reuse;
or
(
11)
A
gas
stream
exiting
an
analyzer."

The
bases
for
the
HON
process
vent
definition
and
the
key
exceptions
listed
here
are
discussed
at
66
Fed.
Reg.
6921,
6923­
24
(
January
22,
2001)
and
65
Fed.
Reg.
3169,
3170­
73
(
January
20,
2000).
They
apply
to
the
MON
category
equally
as
well.

Batch
Process
Vents
The
Council
recommends
that
EPA
develop
a
definition
of
"
batch
process
vent"
that
is
modeled
after
the
Subpart
JJJ
definition.
The
Council
recommends
the
following
definition
of
"
batch
process
vent"
that
should
be
inserted
into
the
final
MON
rule.

Batch
process
vent
means
a
point
of
emission
of
a
gas
stream
from
a
batch
unit
operation
having
annual
HAP
emissions
greater
than
500
pounds
per
year.
Batch
process
vents
are
gas
streams
that
are
discharged
to
the
atmosphere
(
with
or
without
passing
through
a
control
device)
either
directly
or
after
passing
through
one
or
more
recovery
devices.
Gas
streams
that
are
undiluted
and
uncontrolled
containing
less
than
50
ppmv
HAP,
as
determined
through
process
knowledge
that
no
HAP
are
present
in
the
emission
stream
or
using
an
engineering
assessment
as
discussed
in
Sec.
63.1257(
d)(
2)(
ii),
test
data
using
Methods
18
of
40
CFR
part
60,
appendix
A,
or
any
other
test
method
that
has
been
validated
according
to
the
procedures
in
Method
301
of
appendix
A
of
this
part,
are
not
considered
process
vents.
Batch
process
vents
do
not
include
(
1)
relief
valve
discharges,
(
2)
gaseous
streams
routed
to
a
fuel
gas
system(
s),
(
3)
vents
on
storage
tanks,
wastewater
emission
sources,
or
pieces
or
equipment
subject
to
the
emission
limitations
and
work
practice
standards
in
Tables
3
through
5
of
this
subpart,
or
(
4)
emissions
from
process
equipment
which
was
opened
to
provide
access
to
the
equipment
for
performing
routine
inspection,
maintenance,
or
other
activities
needed
for
normal
operations;
(
5)
vents
used
solely
for
health
and
safety
purposes.
A
gaseous
emission
stream
is
no
longer
considered
to
be
a
batch
Definition
of
Batch
&
Continuous
Process
Vent
in
the
MON
2
process
vent
after
the
stream
has
been
controlled
and
monitored
in
accordance
with
the
applicable
provisions
of
this
subpart.

The
Council's
Recommended
Definition
For
Batch
Process
Vents
Provides
A
Much
Needed
Mass
Threshold
Our
proposed
definition
includes
a
de
minimis
level
based
on
mass
emissions
that
is
necessary
for
batch
operations
in
addition
to
the
50
ppmv
cutoff.
There
can
be
short
duration
emissions
of
greater
than
50
ppmv
that
still
represent
trivial
emissions.
Examination
of
the
MACT
floor
database
supports
the
need
for
a
mass
threshold.
For
example,
by
combining
the
dedicated
and
nondedicated
batch
databases
and
summing
HAP
emissions
by
emission
source,
we
have
found
that
emission
sources
smaller
than
500
pounds
per
year
HAP
emissions
comprise
nearly
50%
of
the
emission
sources
in
the
database
while
accounting
for
only
0.2%
of
the
baseline
emissions.
(
See
related
comments
in
V.
C.
3.)

The
Council's
Recommended
Definition
Incorporates
An
Exemption
for
Opening
Equipment
I
n
batch
manufacturing
reactors
must
be
opened
to
add
ingredients
or
filter
devices
must
be
opened
for
product
inspection
or
removal.
In
these
cases,
there
are
minor
quantities
of
unavoidable
emissions
from
the
equipment.
These
emissions
are
very
difficult
to
estimate
and
are
not
normally
thought
of
as
process
vent
emissions.
In
the
OSWRO
MACT,
EPA
recognized
that
there
are
times
when
tank
operators
must
be
relieved
of
the
requirement
to
vent
to
a
closed­
vent
system.
See
e.
g.,
40
CFR
685(
g)(
2)(
i)).
These
times
include
sampling
of
tank
contents
and
removal
of
sludges
from
tanks.
EPA
must
likewise
recognize
that
batch
manufacturing
involves
these
same
types
of
activities.

Support
for
such
an
exclusion
is
also
derived
from
the
floor
database.
There
was
only
sporadic
reporting
of
this
type
of
emissions
in
the
114
survey
and,
apparently,
EPA
has
included
these
emissions
in
its
MACT
floor
determination.
Logically,
there
would
be
fugitives
from
virtually
any
batch
operation,
so
evidently,
many
companies
did
not
report
them.
Of
those
that
did,
no
emission
source
described
as
"
fugitives",
"
area
fugitives",
"
building
exhaust",
etc.
was
reported
as
being
controlled.
EPA
should
recognize
it
is
not
industry
practice
to
collect
and
control
such
minor
quantities
of
emissions
from
batch
operations
and
that
there
is
no
MACT
floor
for
this
category
of
emissions.

The
Council's
Recommended
Definition
Provides
an
Exemption
for
Health
and
Safety
Vents.

There
are
different
and
special
kinds
of
vents
associated
with
batch
process
operations,
which
cannot
appropriately
be
lumped
together
under
a
98%
overall
control
requirement.
EPA
failed
to
consider
important
sub­
categories
of
vents
and
either
exclude
them
or
develop
separate
MACT
requirements.

Vents
used
periodically
for
safety
and
occupational
health
purposes,
for
example,
should
be
excluded
from
the
definition
of
"
process
vents".
Such
safety
and
health
related
vents
include
vents
used
to
such
vapors
away
from
operating
personnel
when
opening
equipment,
and
vents
used
when
purging
the
system
air­
free
before
venting
to
a
source
of
combustion.
These
vents
have
historically
not
been
viewed
as
being
normal
process
vents
by
industry
or
local
regulatory
agencies.

Air­
bearing
vents
(
that
cannot
safely
go
to
common
flares
or
incinerators)
should
have
been
considered
separately
from
non­
air­
bearing
vents,
since
it
is
much
harder
to
obtain
high
control
efficiencies
without
using
a
combustion
device.

The
definition
of
batch
operation
or
batch
process
from
40
CFR
§
63.1251
that
was
referenced
in
the
proposed
Subpart
FFFF
is
not
usable
because
it
states
that
" 
Addition
of
raw
material
and
withdrawal
of
product
do
not
occur
simultaneously
in
a
batch
operation."
The
definition
of
batch
mode
in
Subpart
JJJ
better
fits
the
MON
sources,
it
reads
" 
the
addition
of
material
and
withdrawal
of
material
do
not
typically
occur
simultaneously."
Many
batch
processes
in
the
organic
chemical
industry
add
raw
materials,
transfer
various
intermediates
among
several
vessels,
and
withdraw
products
from
different
vessels
after
several
additional
batch
steps
have
been
conducted.
Thus,
the
definition
in
Subpart
JJJ
is
much
more
consistent
Definition
of
Batch
&
Continuous
Process
Vent
in
the
MON
3
with
batch
organic
chemical
operations
than
the
Subpart
GGG
definition,
which
is
restricted
to
a
very
specialized
industry,
and
we
recommend
it
be
used
in
the
MON.

Emissions
From
Non­
Routine
Cleaning
Operations
Should
Not
Be
Included
As
Batch
Process
Emissions
I
t
becomes
overly
complicated
if
emissions
from
non­
routine
cleaning
operations,
which
occur
only
occasionally,
rather
than
every
batch,
are
considered
"
batch
process
vent
emissions".
As
a
matter
of
practicality,
batch
process
vent
emissions
should
be
only
those
emissions
that
occur
routinely
each
batch,
so
that
one
can
multiply
the
emissions
per
batch
by
the
number
of
batches
made
to
determine
if
the
10,000
lb/
yr
HAP
threshold
is
exceeded.
Non­
routine
cleaning
activities
are
unpredictable
and
often
the
result
of
process
fouling
and
upsets.
Trying
to
include
emissions
that
occur
irregularly
as
batch
process
vent
emissions
adds
unnecessary
burden
and
complexity.
Such
non­
routine
emissions
should
be
excluded
from
the
MON
as
being
ancillary
or
maintenance
activities.
