Storage
Tanks
vs
Process
Vents
Approach
1.
Define
continuous
vents
separately
from
other
process
vents.

2.
Maintain
consistency
with
the
HON
and
identify
continuous
vents
as
those
from
reactor
and/
or
air
oxidation
reactors,
and
distillation
columns.
These
are
the
only
vents
for
which
the
TRE
would
be
applied.

3.
Define
surge
control
vessels
and
bottoms
receivers
as
in
the
HON,
with
the
following
caveat:

bottoms
receivers
must
immediately
follow
a
continuous
distillation
operation,
surge
control
vessels
must
immediately
precede
continuous
reactors,
air­
oxidation
reactors,
or
distillation
operations.

4.
Define
storage
tank
with
the
capacity
exclusion
of
10,000
gallons.
In
other
words
a
storage
tank
cannot
be
less
than
10,000
gallons,
unless
it
is
the
first
raw
material
or
final
product
tank.
Also
note
that
the
tank
must
have
the
process
on
either
side
of
it.
This
incorporates
the
concept
of
intervening
tank.

5.
Define
process
tank
as
excluding
storage
tanks,
bottoms
receivers,
surge
control
vessels,
and
wastewater
tanks.
Vents
from
process
tanks
and
any
other
vents,
including
continuous
vents
that
are
not
from
continuous
reactor,
air­
oxidation
reactor
or
distillation
operations
would
be
considered
under
the
batch
process
vents
requirements.

Definitions:

A
continuous
process
vent
is
the
point
of
discharge
to
the
atmosphere
(
or
the
point
of
entry
into
a
control
device,
if
any)
of
a
gas
stream
if
the
gas
stream
has
the
characteristics
specified
in
paragraphs
(
b)
through
(
h)
of
this
section,
or
meets
the
criteria
specified
in
paragraph
(
i)
of
this
section.
(
b)
Some,
or
all,
of
the
gas
stream
originates
as
a
continuous
flow
from
an
air
oxidation
reactor,
distillation
unit,
or
reactor
during
operation
of
the
chemical
manufacturing
process
unit
MCPU.
(
c)
The
discharge
to
the
atmosphere
(
with
or
without
passing
through
a
control
device)
meets
at
least
one
of
the
conditions
specified
in
paragraphs
(
c)(
1)
through
(
3)
of
this
section.
(
1)
Is
directly
from
an
air
oxidation
reactor,
distillation
unit,
or
reactor;
or
(
2)
Is
from
an
air
oxidation
reactor,
distillation
unit,
or
reactor
after
passing
solely
(
i.
e.,
without
passing
through
any
other
unit
operation
for
a
process
purpose)
through
one
or
more
recovery
devices
within
the
chemical
manufacturing
process
unit
MCPU;
or
(
3)
Is
from
a
device
recovering
only
mechanical
energy
from
a
gas
stream
that
comes
either
directly
from
an
air
oxidation
reactor,
distillation
unit,
or
reactor,
or
from
an
air
oxidation
reactor,
distillation
unit,
or
reactor
after
passing
solely
(
i.
e.,
without
passing
through
any
other
unit
operation
for
a
process
purpose)
through
one
or
more
recovery
devices
within
the
chemical
manufacturing
process
unit
MCPU.
(
d)
The
gas
stream
contains
greater
than
0.005
weight
percent
total
organic
HAP
at
the
point
of
discharge
to
the
atmosphere
(
or
at
the
point
of
entry
into
a
control
device,
if
any).
(
e)
The
air
oxidation
reactor,
distillation
unit,
or
reactor
is
part
of
a
MCPU
chemical
manufacturing
process
unit
that
meets
the
criteria
of
Sec.
63.100(
b).
(
f)
The
gas
stream
is
in
the
gas
phase
from
the
point
of
origin
at
the
air
oxidation
reactor,
distillation
unit,
or
reactor
to
the
point
of
discharge
to
the
atmosphere
(
or
to
the
point
of
entry
into
a
control
device,
if
any).
(
g)
The
gas
stream
is
discharged
to
the
atmosphere
either
on­
site,
off­
site,
or
both.
(
h)
The
gas
stream
is
not
any
of
the
items
identified
in
paragraphs
(
h)(
1)
through
(
9)
of
this
section.
(
1)
A
relief
valve
discharge.
(
2)
A
leak
from
equipment
subject
to
subpart
H
of
this
part.
(
3)
A
gas
stream
going
to
a
fuel
gas
system
as
defined
in
Sec.
63.101.
(
4)
A
gas
stream
exiting
a
control
device
used
to
comply
with
Sec.
63.113.
(
5)
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).
(
6)
A
gas
stream
transferred
for
fuel
value
(
i.
e.,
net
positive
heating
value),
use,
reuse,
or
for
sale
for
fuel
value,
use,
or
reuse.
(
7)
A
storage
vessel
vent
or
transfer
operation
vent
subject
to
Sec.
63.119
or
Sec.
63.126.
(
8)
A
vent
from
a
waste
management
unit
subject
to
Secs.
63.132
through
63.137.
(
9)
A
gas
stream
exiting
an
analyzer.
(
i)
The
gas
stream
would
meet
the
characteristics
specified
in
paragraphs
(
b)
through
(
g)
of
this
section,
but,
for
purposes
of
avoiding
applicability,
has
been
deliberately
interrupted,
temporarily
liquefied,
routed
through
any
item
of
equipment
for
no
process
purpose,
or
disposed
of
in
a
flare
that
does
not
meet
the
criteria
in
Sec.
63.11(
b),
or
an
incinerator
that
does
not
reduce
emissions
of
organic
HAP
by
98
percent
or
to
a
concentration
of
20
parts
per
million
by
volume,
whichever
is
less
stringent.

Surge
control
vessel
means
feed
drums,
recycle
drums,
and
intermediate
vessels
immediately
preceding
continuous
reactors,
air­
oxidation
reactors,
or
distillation
operations.
Surge
control
vessels
are
used
within
a
chemical
manufacturing
process
unit
MCPU
when
in­
process
storage,
mixing,
or
management
of
flow
rates
or
volumes
is
needed
to
assist
in
production
of
a
product
to
introduce
material
into
continuous
reactors,
air­
oxidation
reactors,
or
distillation
operations.
Bottoms
receiver
means
a
tank
that
collects
distillation
bottoms
before
the
stream
is
sent
for
storage
or
for
further
downstream
processing.

Storage
tank
means
a
tank
or
other
vessel
that
is
used
to
store
raw
material
feedstocks
or
organic
liquid
products
that
contain
one
or
more
HAP
as
raw
material
feedstocks.
of
the
organic
HAP
listed
in
Table
2
of
Subpart
F
of
this
part.
Storage
tank
also
means
a
tank
or
other
vessel
in
a
tank
farm
that
receives
and
accumulates
used
solvent
from
multiple
batches
of
a
process
or
processes
for
purposes
of
solvent
recovery.
Storage
tanks
either
precede
or
follow
process
unit
operations,
but
are
not
located
between
process
unit
operations.
The
following
are
not
considered
storage
tanks
for
the
purposes
of
this
subpart:
(
1)
Vessels
permanently
attached
to
motor
vehicles
such
as
trucks,
railcars,
barges,
or
ships;
(
2)
Pressure
vessels
designed
to
operate
in
excess
of
204.9
kilopascals
and
without
emissions
to
the
atmosphere;
(
3)
Vessels
storing
organic
liquids
that
contain
HAP
only
as
impurities;
(
4)
Wastewater
storage
tanks;
and
(
5)
Process
tanks
(
including
product
tanks
and
isolated
intermediate
tanks).
(
6)
Except
for
the
first
vessel
to
accept
raw
material
from
offsite
product
distribution
or
the
last
vessel
to
store
product
prior
to
offsite
shipment,
vessels
with
capacities
smaller
than
10,000
gallons.
(
7)
Bottoms
receiver
tanks;
(
8)
Surge
control
vessels.

Process
tank
means
a
tank
or
vessel
that
is
not
considered
one
of
the
following:
(
1)
storage
tank
(
2)
bottoms
receiver
(
3)
surge
control
vessel
(
4)
wastewater
storage
tank.
Process
tanks
are
subject
to
the
emission
limitations
63.2450
(
a)(
2).
