Burners should be visually inspected to ensure
proper operation once per shift. Conditions that need to be corrected include
flame impingement on tubes and supports, abnormal flame dimensions and pattern,
oil drippage, and smokey combustion. In addition, the burners should provide an
even heat distribution. Poor firing from unbalanced burners can cause serious
deterioration of the heating elements and setting. Defective burners that can
not be repaired in service should be replaced so that they do not lead to
premature failure of other components. Obtain the burner drawings from the
burner vendor. The drawings will include the installation tolerances, tile
diameter and tip drilling information.
Burner plugging problems sometimes can be
solved by proper sizing of the fuel drum and demister pad, heat tracing the
fuel gas delivery lines, and providing filters or coalescing systems.
Regardless, deposits should be analyzed to determine if the source of the
plugging can be identified and eliminated.
The following guidelines are general
recommendations for maintenance outage inspection. Always consult the
guidelines from the burner vendor.
a. The burner tile is an air orifice. It controls
the amount of air flow. Since it is extremely desirable to have even air flow
to each burner, the tile dimensions are critical. Typical installation
tolerance is ± 1/8 in. (0.32 cm) on the diameter as shown on the burner
drawing. Measure the diameter in three to four locations. Most round tiles are
installed as a slight oval shape. This will result in poor fuel-air mixing and
a bad flame shape. Burner tiles should not be cracked or spalled. The use of a plywood
template helps set the tiles in the proper diameter and concentricity. The
burner tile must be centered on the gas tip to obtain uniform fuel air mixing.
Typical installation tolerance is ± 1/8 in. (0.32 cm). Poor installations
result in bad flames.
b. Check the burner drawing for the number of tip
drillings and the drill bit size of the port. Use drill bits to check the
proper hole size and the proper included angle of the drillings. Do not mix
parts from other burners. Be sure to install tips with high-temperature
anti-seize compound.
c. The installation tolerance on gas risers is
typically ± 1/8 in. (0.32 cm) on horizontal spacing and ± 1/8 in. (0.32 cm) on
vertical spacing. Bent gas risers can cause these dimensions to be wrong. A
common problem is different lengths on the gas risers. Many burners are
designed such that the gas jets intersect in the center of the burner. The tips
usually have arrows or cutouts to aid in tip orientation. Welding rods can be a
valuable check for alignment.
d. Air dampers and registers should be checked
for operability. Sticking air registers and dampers are a problem. Sometimes,
dry graphite lubricant can improve air register operability. Penetrating oil,
grease fittings and the addition of bearings to damper shafts can improve
operability.
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