1
MEMORANDUM
DATE:
June
21,
2005
SUBJECT:
Applicability
of
DPF
on
Large
Stationary
Engines
FROM:
Tanya
Parise,
Alpha­
Gamma
Technologies,
Inc.

TO:
Sims
Roy,
EPA
OAQPS
ESD
Combustion
Group
The
purpose
of
this
memorandum
is
to
document
information
related
to
the
application
of
diesel
particulate
filters
(
DPF)
on
large
stationary
compression
ignition
(
CI)
internal
combustion
engines
for
the
new
source
performance
standards
(
NSPS).
For
the
purpose
of
this
memorandum,
stationary
CI
engines
greater
than
750
horsepower
(
HP)
with
a
displacement
less
than
30
liters
per
cylinder
are
considered
large
engines.

Background
The
EPA
is
in
the
process
of
developing
proposed
NSPS
for
stationary
CI
internal
combustion
engines.
The
proposed
standards
are
primarily
modeled
on
EPA's
final
rule
for
control
of
emissions
from
nonroad
diesel
engines,
which
was
published
in
the
Federal
Register
on
June
29,
2004
(
69
FR
38957).
The
final
rule
requires
that
nonroad
diesel
engines
between
75
and
750
HP
meet
a
particulate
matter
(
PM)
standard
of
0.01
grams
per
brake
horsepower­
hour
(
g/
bhp­
hr)
as
early
as
2011
based
on
the
use
of
catalyzed
DPF.
For
nonroad
diesel
engines
greater
than
750
HP,
two
categories
were
established
for
the
final
rule
to
account
for
significant
differences
in
application:
mobile
machines
and
generator
sets.
For
generator
sets,
the
final
rule
requires
that
these
engines
meet
a
PM
standard
of
0.02
g/
bhp­
hr
in
2015.
The
2015
PM
standard
for
mobile
machines
was
set
slightly
higher,
at
0.03
g/
bhp­
hr,
to
account
for
expectations
that
engine­
out
emissions
from
generator
sets
can
be
reduced
below
mobile
machine
levels
due
to
operation
at
a
single
engine
speed.

As
noted
above,
the
final
rule
for
nonroad
diesel
engines
has
a
slightly
higher
PM
standard
for
engines
above
750
HP.
The
PM
standard
in
the
proposed
rule
for
nonroad
diesel
engines
was
0.01
g/
bhp­
hr
for
all
engines
above
75
HP.
The
Engine
Manufacturers
Association
(
EMA)
submitted
comments
to
EPA
on
the
proposed
rule
for
nonroad
engines
indicating
that
they
had
concerns
with
applying
DPF
technology
to
large
CI
engines.
The
comment
from
EMA
stated
the
following:
1Summary
and
Analysis
of
Comments:
Control
of
Emissions
from
Nonroad
Diesel
Engines.
United
States
Environmental
Protection
Agency,
Office
of
Transportation
and
Air
Quality.
EPA420­
R­
04­
008.
May
2004.

2
"
EMA
further
added
that
they
do
not
believe
it
will
be
feasible
to
apply
PM
filter
technology
to
larger
nonroad
engines
(
above
750
HP).
For
nonroad
engines
greater
than
750
HP,
there
are
significant
challenges
associated
with
the
use
of
multiple
parallel
PM
filters.
A
large
number
of
parallel
filters
must
be
used
on
the
larger
engines
if
on­
highway
technology
is
to
be
used
directly.
A
600
HP
highway
truck
will
require
at
least
two
parallel
filters,
while
a
3,000
HP
engine
will
require
up
to
five
times
as
many,
or
10
parallel
PM
filters.
Each
filter
must
reach
sufficient
temperatures
to
burn
out
the
accumulated
soot,
but
the
filters
will
not
all
run
at
the
same
temperatures
and
only
some
will
reach
sufficient
temperatures
to
burn
out
the
soot.
Excessive
soot
accumulation
in
the
coolrunning
filter
can
lead
to
excessive
thermal
gradients
causing
cracks
or
temperatures
so
high
that
the
ceramic
trap
will
melt,
or
causing
a
pressure
drop
across
the
filter.
The
likelihood
of
at
least
partial
failures
and
cracks
allowing
soot
bypassing
for
large
filters
made
up
of
smaller
segments
or
of
multiple
parallel
units
is
high.
Therefore,
without
substantial
new
technology
development,
it
will
not
be
feasible
to
apply
PM
filter
technology
in
these
applications."

This
comment
can
be
found
on
page
3­
49
of
the
Summary
and
Analysis
of
Comments
on
the
nonroad
diesel
engines
rule.
1
As
a
result
of
this
and
other
related
comments,
the
final
PM
standard
for
nonroad
diesel
engines
above
750
HP
is
slightly
higher
than
for
smaller
engines.
As
noted
by
EPA
in
the
response
to
comments
and
also
in
the
preamble
for
the
final
rule
for
nonroad
diesel
engines,
the
PM
emission
standard
for
engines
greater
than
750
HP
was
based
on
a
different
type
of
DPF,
a
wire
or
fiber
mesh
depth
filter
rather
than
a
ceramic
wall
flow
filter,
which
was
the
basis
for
the
PM
standard
for
engines
between
75
and
750
HP
and
other
smaller
engines.
The
Office
of
Transportation
and
Air
Quality
(
OTAQ)
stated
in
the
preamble
to
the
final
rule
that
the
application
of
wall
flow
filters
has
not
currently
been
adequately
demonstrated
on
large
engines.
According
to
OTAQ,
wire
or
fiber
mesh
depth
filters
are
less
efficient
at
reducing
PM
emissions
than
the
ceramic
wall
flow
filters,
and
are
capable
of
reducing
PM
by
70
percent
or
more,
whereas
ceramic
wall
flow
filters
can
reduce
PM
by
more
than
90
percent.
The
technology­
based
PM
standard
for
engines
between
175
and
750
HP
was
therefore
set
at
a
lower
(
more
stringent)
level,
at
0.01
g/
bhp­
hr.
However,
OTAQ
noted
that
it
would
certainly
be
possible
to
utilize
ceramic­
based
technology
for
larger
engines,
but
could
not
guarantee
that
these
filters
would
be
as
robust
as
needed
at
this
time.
In
addition,
OTAQ
stated
that
it
believes
it
may
be
possible
in
the
time
frame
of
the
regulation
for
conventional
DPF
to
be
applied
to
nonroad
diesel
engines
greater
than
750
HP,
however,
based
on
comments
received,
there
is
too
much
uncertainty
to
reach
a
conclusion
at
the
time
of
the
final
rulemaking.
Developments
3
may
occur
and
the
future
application
of
the
more
effective
PM
filter
media
to
engines
greater
than
750
HP
is
certainly
possible,
according
to
OTAQ.

Due
to
the
concerns
raised
by
EMA,
the
EPA
contacted
several
DPF
system
vendors
to
obtain
their
input
and
thoughts
on
the
applicability
of
DPF
to
large
stationary
CI
internal
combustion
engines.
The
information
provided
by
the
vendors
is
discussed
below.

Information
from
Catalyst
Vendors
Information
from
vendors
indicated
that
the
application
of
multiple
smaller
filters
is
certainly
possible
and
vendors
did
not
indicate
that
there
are
specific
concerns
with
the
application
of
multiple
smaller
filters
to
large
engines.
It
appears
based
on
information
received
that
ceramic­
based
filters
may
also
be
available
for
use
on
large
engines.
The
applications
may
be
few,
however,
according
to
vendors,
the
technology
is
available.

Mobile
vs.
Stationary
Applications
The
EPA
asked
the
vendors
if
the
DPF
that
are
applied
to
stationary
engines
are
different
than
those
applied
to
mobile
(
highway/
nonroad)
engines.
Engelhard
responded
to
this
question
by
stating
that
most
DPF
technologies
are
very
similar
if
not
even
the
same
and
that
this
includes
on­
highway
as
well
as
off­
highway/
stationary
engines.
Clean
Air
Systems
responded
to
this
question
by
stating
that
the
filter
substrates
are
the
same,
but
that
the
catalyst
formulation
can
be
different,
depending
on
factors
such
as
the
fuel
sulfur
content,
the
percent
efficiency
needed,
the
regeneration
conditions,
etc.
Miratech's
response
was
that
particulate
filters
for
mobile
engines
are
almost
all
based
on
a
cordierite
ceramic
material
and
that
stationary
engines
have
used
this
material
as
well
as
porous
wall
silicon
carbide,
other
ceramic
oxides,
woven
fiberglass
and
metal
fibers
woven
or
formed
into
filter
elements.
According
to
Miratech,
these
units
have
traditionally
been
made
in
cylinders
and
the
size
is
limited
based
on
the
manufacturing
process
and
material
limitations.
Miratech
stated
that
based
on
this,
the
comments
made
by
EMA
are
true,
but
the
vendor
pointed
out
that
new
filters
are
also
made
in
rectangular
blocks
that
can
be
stacked
and
arranged,
in
a
similar
but
more
robust
manner
due
to
the
pressure,
to
a
traditional
catalyst
array.
The
vendor
said
that
the
main
difference
between
what
Miratech
supplies
for
large
engines
and
the
typical
ceramic
wall
flow
filters
is
the
material.
Miratech
uses
silicon
carbide
instead
of
cordierite.
According
to
Miratech,
the
properties
of
silicon
carbide
makes
it
more
suitable
for
filter
applications
than
cordierite.
The
vendor
noted
the
following
characteristics
of
silicon
carbide:

°
It
conducts
heat
much
better
than
cordierite,
which
eliminates
much
of
the
thermal
stress
problem,
°
It
is
stronger
and
will
not
crack
as
easily,
and
°
It
can
withstand
higher
temperatures.
4
Miratech
indicated
to
EPA
that
its
partner
in
Switzerland
has
sold
units
up
to
2.5
megawatt
(
MW)
with
catalyzed
silicon
carbide
filters
and
the
vendor
stated
that
it
is
now
manufacturing
units
for
2
MW
engines.
Finally,
Miratech
said
that
designs
are
currently
available
for
units
up
to
6.5
MW
in
size.
If
the
engine
exhaust
temperature
is
too
cool,
a
diesel
fuel
burner
can
be
added
to
oxidize
the
soot.

Problems
Mentioned
by
EMA
The
EPA
also
asked
the
vendors
if
any
of
the
types
of
problems
mentioned
in
the
comment
made
by
EMA
would
apply
when
DPF
are
applied
to
stationary
engines.
Johnson
Matthey
responded
that
it
uses
parallel
filters
on
the
larger
engines.
The
largest
engine
this
vendor
has
equipped
with
DPF
was
a
3,300
HP
engine.
Johnson
Matthey
indicated
that
this
engine
is
comprised
of
sixteen
filters.
The
vendor
further
stated
in
response
to
EMA's
comment
that
their
Continuously
Regenerating
Trap
(
CRT),
a
catalyzed
diesel
particulate
filter
(
passive
DPF),
provides
a
continuous
burning
of
the
particulate
and
that
it
is
not
expected
that
the
temperature
mentioned
in
EMA's
comment
will
ever
become
so
high
that
it
will
cause
the
problems
noted.
Additionally,
there
will
be
few
occasions
when
soot
will
accumulate
excessively
on
hotter
running
stationary
engines,
according
to
the
vendor.
Miratech
stated
in
response
to
this
comment
that
with
proper
housing
design
and
gasketing,
several
filter
blocks
can
be
stacked
into
a
single
large
housing
without
having
significant
leakage
around
the
filters.
The
vendor
indicated
that
this
has
been
demonstrated
by
HUG
Engineering
in
Europe.
Miratech
also
stated
that
the
problems
listed
by
EMA
are
correct
but
can
be
addressed
with
an
active
regeneration
system.
In
response
to
this
question,
Engelhard
said
that
there
can
be
problems
with
any
type
of
aftertreatment
technology
if
it
is
not
applied
correctly.
However,
with
proper
sizing
and
engineering,
the
problems
can
be
avoided.
The
representative
from
Engelhard
indicated
that
he
has
personally
manifolded
six
soot
filters
together
and
that
these
filters
have
operated
without
any
problems
for
more
than
5
years.
Clean
Air
Systems
responded
that
stationary
engines
normally
do
not
have
strict
space
requirements
and
assuming
that
load
management
and
the
duty
cycle
are
understood,
the
problems
mentioned
by
EMA
do
not
apply.

Feasibility
of
meeting
nonroad
diesel
engine
PM
limits
When
asked
by
EPA
if
vendors
believe
that
the
technology
is
available
that
would
allow
large
stationary
CI
internal
combustion
engines
to
meet
PM
limits
similar
to
those
for
large
nonroad
diesel
engines,
all
vendors
contacted
were
generally
in
agreement
that
those
PM
levels
are
achievable
for
large
stationary
CI
engines.
Johnson
Matthey
stated
that
it
has
achieved
85
percent
reduction
of
PM
on
stationary
engines
with
its
CRT
system.
Miratech
was
of
the
opinion
that
the
catalyzed
silicon
carbide
filters
(
with
or
without
an
active
regeneration
system)
are
on
the
market
and
available
today
to
meet
the
PM
levels
required
for
nonroad
diesel
engines.
The
vendor
added
that
5
meeting
that
PM
limit
will
depend
on
the
engine
soot
production,
but
that
greater
than
90
percent
reduction
is
possible.
Catalyst
vendor
Engelhard
also
agreed
that
the
technology
is
currently
available
to
meet
the
PM
levels
in
question,
but
pointed
out
that
it
will
depend
on
what
the
baseline
uncontrolled
level
of
PM
is
and
the
test
protocol
used
to
measure
PM.
At
such
low
levels,
test
equipment
and
human
errors
are
factors
that
can
affect
the
level.
Finally,
Clean
Air
Systems
also
agreed
that
the
technology
is
available
today
to
meet
levels
similar
to
the
limits
for
nonroad
diesel
engines.

Filter
Material
The
EPA
also
asked
vendors
to
comment
on
OTAQ's
conclusion
to
base
its
PM
standard
for
large
engines
on
wire
or
fiber
mesh
depth
filters
as
opposed
to
the
conventional
ceramic
wall
flow
filters.
As
previously
mentioned,
OTAQ
believes
that
wire
or
fiber
mesh
depth
filters
are
less
efficient
at
reducing
PM,
achieving
about
a
70
percent
reduction
in
PM,
versus
the
conventional
filter,
which
is
capable
of
reducing
PM
by
90
percent.
According
to
OTAQ,
the
application
of
the
wall
flow
filter
technology
on
large
nonroad
engines
has
not
been
adequately
demonstrated
at
this
time.
Johnson
Matthey
responded
that
the
number
of
applications
of
ceramic
wall
flow
filters
on
large
engines
are
few,
but
that
wall
flow
filters
appear
to
be
a
viable
solution.
Catalyst
vendor
Miratech
agreed
that
there
are
few
installations
of
ceramic
wall
flow
filters
on
large
engines.
The
vendor
further
stated
that
wire
mesh
filters
are
not
as
effective
as
through
wall
filters
and
that
it
has
found
that
packaging
wire
mesh
filters
becomes
more
difficult
for
larger
engines,
as
the
filters
cannot
be
stacked
as
easily.
Finally,
Miratech
added
that
electrical
regeneration
also
becomes
difficult
due
to
the
number
of
electrical
connections
and
the
amount
of
energy
required
become
significant.
Engelhard
indicated
that
it
has
successfully
applied
ceramic
wall
flow
filters
on
several
stationary
applications
for
over
8
years.
The
applications
have
been
on
engines
ranging
in
size
from
40
kilowatt
to
2
MW.
Engelhard
noted
however
that
there
may
be
applications
where
it
would
decline
to
supply
such
a
filter
due
to
incompatibility
and
the
wire
or
fiber
mesh
depth
filters
would
work.

Largest
Engines
with
DPF
The
EPA
also
asked
several
major
control
technology
vendors
for
information
regarding
the
application
of
DPF
to
stationary
engines
in
order
to
determine
what
the
largest
engines
with
DPF
are.
The
catalyst
vendor
Johnson
Matthey
indicated
to
EPA
that
its
largest
DPF
application
was
on
a
3,300
HP
engine.
Miratech
Corporation,
another
well­
known
control
technology
manufacturer,
indicated
to
EPA
that
it
works
alongside
HUG
Engineering
of
Switzerland
for
its
filter
supply
and
that
the
largest
filter
that
it
has
supplied
was
for
an
engine
approximately
4,000
HP
in
size.
Johnson
Matthey
further
noted
that
in
the
United
States,
it
is
currently
supplying
42
filters
for
the
Long
Island
Power
Authority
on
stationary
Cummins
engines
about
3,200
HP
in
size.
This
project
will
be
completed
in
the
fall
of
2004.
When
asked
what
the
largest
size
stationary
engine
Engelhard
(
another
major
catalyst
vendor)
has
equipped
with
DPF,
Engelhard
6
responded
that
it
has
retrofitted
Engelhard
filters
on
approximately
2,800
HP
engines
and
indicated
that
it
had
done
quite
a
few
of
these
installations
for
Caterpillar
and
Cummins
(
engine
manufacturers).
Finally,
EPA
consulted
Clean
Air
Systems
to
determine
the
largest
stationary
engine
it
had
equipped
with
DPF.
Clean
Air
Systems
replied
that
it
has
done
many
2
MW
engines
and
those
are
the
largest,
but
that
it
can
install
DPF
on
engines
larger
than
that.
Based
on
information
received
from
several
major
DPF
manufacturers,
it
appears
DPF
can
be
and
has
been
applied
to
large
stationary
engines
well
above
750
HP.

Finally,
during
a
recent
meeting
EPA
had
with
members
of
the
Institute
of
Clean
Air
Companies,
control
technology
vendors
indicated
that
ceramic
wall
flow
filter
technology
is
currently
available
and
can
be
applied
to
large
stationary
engines.
A
representative
from
Johnson
Matthey
indicated
that
Johnson
Matthey
has
been
working
on
applications
of
DPF
on
large
engines
and
85
percent
PM
reductions
has
been
achieved.

California
ATCM
In
addition
to
consulting
with
vendors
of
DPF
systems,
EPA
also
reviewed
information
gathered
by
the
California
Air
Resources
Board
(
CARB)
in
support
of
its
airborne
toxic
control
measure
(
ATCM)
for
stationary
CI
engines,
which
became
operative
on
December
8,
2004.
The
standards
require
stationary
new
and
in­
use
prime
CI
engines
greater
than
50
HP
to
meet
a
diesel
PM
limit
of
0.01
g/
bhp­
hr.
The
Board
believes
the
0.01
g/
bhp­
hr
is
technologically
feasible
because
results
from
a
demonstration
program
conducted
by
CARB
in
order
to
evaluate
the
feasibility
of
several
PM
control
technology
options
showed
that
two
stationary
diesel
engines
were
able
to
achieve
a
diesel
PM
emission
rate
of
equal
to
or
less
than
0.01
g/
bhp­
hr
following
the
application
of
DPF
technologies.
In
addition,
emissions
test
data
from
Clean
Air
Systems'
PERMIT
technology,
a
passive
DPF,
has
shown
that
the
technology
is
capable
of
reducing
PM
emissions
by
85
percent
or
more,
which
has
yielded
diesel
PM
emission
rates
below
0.01
g/
bhp­
hr.
The
PERMIT
technology
from
Clean
Air
Systems
has
been
verified
by
CARB
for
application
to
engines
and
is
verified
to
obtain
85
percent
PM
reduction
on
several
engine
models.
The
ATCM
does
not
contain
any
size
categories
for
engines
greater
than
50
HP,
but
instead
has
the
same
requirements
for
PM
for
all
new
and
inuse
prime
CI
engines
and
does
not
make
a
distinction
of
large
engines.
It
is
assumed
DPF
will
be
capable
of
reducing
PM
emissions
from
any
engine
by
85
percent.
2California
Air
Resources
Board
Staff
Report:
Initial
Statement
of
Reasons
for
Proposed
Rulemaking.
Airborne
Toxic
Control
Measure
for
Stationary
Compression
Ignition
Engines.
Stationary
Source
Division,
Emissions
Assessment
Branch.
September
2003.

3Note
that
information
received
from
Johnson
Matthey
indicated
that
the
CRT
is
not
a
catalyzed
filter
but
contains
a
catalyst
in
front
of
a
particulate
filter.
The
vendor
indicated
that
the
catalyst
produces
more
NO
2
in
the
exhaust
which
enables
regeneration
(
oxidation)
of
the
particulate
at
a
lower
temperature.
Johnson
Matthey
indicated
that
it
finds
this
technology
to
be
much
more
effective
than
a
catalyzed
filter.

7
The
Staff
Report
published
by
CARB
for
the
proposed
rulemaking
for
the
ATCM
for
stationary
CI
engines2
documented
several
installations
of
catalyzed
DPF
on
stationary
CI
engines
in
California.
The
stationary
CI
engines
ranged
in
size
from
67
to
2,848
HP,
with
the
majority
of
stationary
CI
engine
DPF
applications
greater
than
750
HP.
Testing
conducted
on
many
of
the
stationary
CI
engines
with
catalyzed
DPF
indicated
that
PM
emissions
were
frequently
reduced
by
85
percent.

In
addition
to
information
CARB
obtained
from
in­
use
stationary
CI
engines
with
PM
control,
it
also
conducted
a
demonstration
program,
as
previously
mentioned,
to
further
investigate
the
effectiveness
of
PM
control
technologies.
Among
the
control
technologies
tested
in
the
demonstration
program
were
the
following
particulate
filters:

°
Lubrizol­
Engine
Control
Systems'
Sequentially
Regenerated
Combifilter
­
a
triple
bank
silicon
carbide
particulate
filter
with
online
filter
regeneration
by
electrical
heating
(
active
DPF),
and
°
Johnson
Matthey's
CRT.
3
The
demonstration
program
showed
that
the
control
efficiencies
for
both
active
and
passive
particulate
filters
were
greater
than
85
percent
when
applied
to
stationary
engines
burning
ultra
low
sulfur
diesel
and
PM
levels
of
0.01
g/
bhp­
hr
were
achieved.

Conclusion
Based
on
the
information
summarized
in
this
memorandum
obtained
from
OTAQ,
CARB,
and
several
control
technology
vendors,
EPA
believes
that
it
is
feasible
to
apply
DPF
to
large
stationary
CI
internal
combustion
engines
and
obtain
similar
levels
of
PM
reduction
as
those
required
for
nonroad
diesel
engines.
Consistent
with
statements
made
by
OTAQ,
the
EPA
does
not
exclude
the
possibility
that
conventional
DPF
could
be
used
on
large
stationary
CI
engines
and
vendors
have
indicated
that
the
technology
is
available
to
meet
the
PM
levels
promulgated
for
nonroad
diesel
engines
(
and
potentially
also
lower
PM
levels).
However,
the
EPA
believes
it
is
appropriate
to
remain
consistent
with
decisions
made
by
OTAQ
for
nonroad
diesel
engines
to
ensure
that
the
proposed
PM
standards
for
stationary
CI
engines
are
achievable
by
large
engines.
For
this
reason,
the
EPA
believes
that
the
PM
emission
standards
8
promulgated
for
large
nonroad
diesel
engines
are
appropriate
for
large
stationary
CI
engines,
and
is
therefore
proposing
that
large
stationary
CI
engines
meet
the
nonroad
diesel
engine
PM
standards
