Hydrocarbon Processing - March 2021 - 59

Heat Transfer
side of the tile. In addition to the highspeed fuel from the primary tips flowing
through those holes, furnace gases are
entrained by the fuel and flow into the
primary flame zone, as well. That entrainment of furnace gases helps to homogenize the flame temperature and reduce
flame hot spots, which helps minimize
NOx. The size of those holes is important.
If the holes are too small, less furnace gas
is entrained and more NOx is produced;
if the holes are too big, too much furnace
gas could be entrained, which could cause
flame instability.

FIG. 7. Damaged (left) regen tile and (right) burner tiles.

Minimize costs. While many tile shapes

could be made, round and rectangular
are by far the most common shapes for
process burners. They are typically the
cheapest to make because the tile molds
are simpler to build. Those tile shapes
are also usually stronger because they
have fewer sharp changes in direction
that produce corners, which are more
likely to crack.
Tile fabrication, installation and
maintenance. Proper tile fabrication is

critical to burner performance. Obviously, the shape must be correct, but the actual fabrication process is important, as
well. For example, if the ceramic is made
from a water-based slurry, it must be
slowly dried to prevent steam from rapidly forming inside the mold, which could
cause the ceramic to spall apart. If the
tile is improperly dried prior to installation in a heater, a rapid startup could also
cause steam formation in the tile to spall
the refractory. There are chemically-base
ceramic materials that do not need to be
slowly dried because of the lack of water
in the ceramic.
Burner tiles will not operate properly
if they are installed incorrectly.6 Some
burner tiles consist of four segments or
sections that make it easier to lift the tile
into position without the use of a forklift. It is important that enough-but not
too much-mortar is applied between
the segments. The burner drawings and
manual should be followed to make sure
the proper tile throat area is maintained.
Tiles must be properly aligned to allow
the design combustion air flowrate.7
Tile maintenance is relatively simple:
ensure that any damaged tiles are repaired
or replaced. FIG. 7 shows some tiles that
have been damaged beyond repair. FIG. 8

shows a tile that has been coated with catalyst. That coating reduces the burner
outlet, which reduces the air flow through
the tile for a given draft level. Some cracks
in the tile are evident, as well.
Troubleshooting and takeaways.
Burner tiles usually degrade over a period
of time, although they can become damaged suddenly, as well. For example, refractory falling out of the roof onto a tile can
cause damage. Operators should examine burner tiles on a regular basis during
heater operation. Burners can be operated
with damaged tiles, as long as the damage
is not too severe. A much closer inspection should be made during maintenance
turnarounds. Typically, turnarounds are
somewhat infrequent, so any damaged
tiles should be repaired or replaced during
turnarounds as another chance may not
be available for some time.
The burner tile is an important and
integral part of a process burner that may
impact the fuel/air mixing, burner stability, flame shape and pollution emissions. It
must be properly manufactured, installed
and maintained for optimum performance. A variety of possible tile problems
exist, such as cracking, buildup, chemical
attack and improper installation. Most of
these are easy to detect and should be corrected, as appropriate.
LITERATURE CITED
Baukal, C., " Introduction, " Industrial Burners
Handbook, Chapter 1, CRC Press, Boca Raton,
Florida, 2003.
2
Venizelos, D., R. Hayes and W. Bussman, " Radiant
wall burners, " Industrial Burners Handbook, Chapter
15, CRC Press, Boca Raton, Florida, 2003.
3
Waibel, R. T., M. G. Claxton and B. Reese, " Burner
design, " Vol. 2: Design and Operations, Chapter 6,
The John Zink Hamworthy Combustion Handbook,
CRC Press, Boca Raton, Florida, 2013.
1

FIG. 8. Catalyst buildup on a regen tile.

Baukal, C. and W. Bussman, " NOx emissions, "
Vol. 1: Fundamentals, The John Zink Hamworthy
Combustion Handbook, CRC Press, Boca Raton,
Florida, 2013.
5
Baukal, C., R. Waibel and M. Claxton, " Natural-draft
burners, " Industrial Burners Handbook, Chapter 16,
CRC Press, Boca Raton, Florida, 2003.
6
Johnson, W., M. Pappe, E. Platvoet and M. G.
Claxton, " Burner installation and maintenance, " Vol.
2: Design and Operations, Chapter 11, The John Zink
Hamworthy Combustion Handbook, CRC Press, Boca
Raton, Florida, 2013.
7
Platvoet, E., I. -P. Chung, M. G. Claxton and T.
Fischer, " Process burners, " Vol. 3: Applications,
Chapter 1, The John Zink Hamworthy Combustion
Handbook, CRC Press, Boca Raton, Florida, 2013.
CHUCK BAUKAL is the Director
of the John Zink Institute, part of
John Zink Hamworthy Combustion,
where he has been since 1998.
Dr. Baukal is the author/editor
of 13 books on industrial
combustion, including The John
Zink Hamworthy Combustion Handbook.
BILL JOHNSON provides technical
support for the Customer Support
Solutions group at John Zink
Hamworthy Combustion, where
he has worked since 1977. He has
been an instructor for the John
Zink Institute for more than 35 yr.
Mr. Johnson has co-authored numerous technical
papers for the HCPI industry and is the lead author
on several chapters in The John Zink Hamworthy
Combustion Handbook.
Hydrocarbon Processing | MARCH 2021

Hydrocarbon Processing - March 2021

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