I.- Ping Chung, PhD, is a senior development engineer in the Technology and Commercial Development Group at
2.6 Oil Burner Maintenance .1 Oil Burner
2.6.2 Oil gun
The majority of oil guns currently in operation in the refining and petrochemical industry use steam or air as the atomization medium. The use of mechanical or high-pressure atomization is very rare and limited to specific types of equipment.
This section describes the design and maintenance for steam-atomized oil guns. The procedures and parts are basically the same for air-atomized oil guns.
The major components of an oil gun are the oil body, oil body receiver, oil tip, atomizer, and the orifice spud.
Figures 2.20 through 2.24 show some oil gun compo- nents from several different oil gun types.
Figure 2.12
Regen tile and one section of secondary tile.
Figure 2.13
Regen oil tile with an oil gun in the center (secondary tile not shown).
Oil gun maintenance requires basic hand tools and the oil gun drawing. A normal list of tools would include 1. Cooling water bath
2. Stationary vise 3. Wire brush
4. 12 or 24 in. (305 or 610 mm) pipe wrench 5. 1 1/2 in. (38 mm) open end wrench 6. 1 5/8 in. (41 mm) open end wrench 7. 3/4 in. (19 mm) open end wrench
8. 1/4 in. (6 mm) Allen wrench (male hex drive) 9. Standard screw driver (slot type)
10. Copper-, bronze-, or nickel-containing high- temperature pipe thread lubricant with applica- tor brush
11. Hole gauges—contact the manufacturer for specific sizes
2.6.2.1 Oil Gun Insert Removal
Two types of oil gun assemblies are available from John Zink Company. These oil guns vary only in the method for supply connections.
One style, the Z-39-C oil body style, requires the oil and atomizing medium to be broken for oil gun insert removal, while the most common, the Z-56 oil body style, does not. In both cases, the oil gun guide tube, which provides the tip adjustment, does not have to be removed with the tip/atomizer assembly for cleaning.
In all fuel cases, when breaking the closed oil and atom- izing medium systems, safety is of utmost importance. It is highly recommended that a full purge of the oil side be completed prior to insert removal. This will minimize the possibility of oil spills exterior to the burner.
2.6.2.2 Z-39-C
After purging the oil gun, disconnect the oil and steam piping making sure to shield any possible pressure spray from the connections due to oil gun blockage.
Then, loosen the three set screws located at the back of the oil gun guide tube. The oil gun should then be completely retractable without disturbing the guide tube location.
2.6.2.3 Z-56 “Quick Change”
After purging the oil gun, loosen the oil gun clevis by use of the clevis handle making sure to shield any possible pressure spray from the interface sleeves due to oil gun blockage. Swing the clevis away and retract the insert.
2.6.2.4 Disassembly
1. Using the cooling water bath, quench any residual heat buildup in the tip area until the tip/sleeve may be gripped, in a bare hand, without discomfort.
2. Position the oil body in the stationary vice and tighten.
3. Using the 1 5/8 in. (41 mm) end wrench as a backup on the oil gun sleeve remove the oil tip using the 1½ in. (38 mm) wrench.
4. Using the pipe wrench, remove the steam tube/
sleeve assembly from the oil body.
5. Using the pipe wrench as a backup on the oil tube remove the atomizer assembly using the 3/4 in. (19 mm) end wrench.
6. Holding the atomizer body with the 3/4 in.
(19 mm) end wrench, remove the oil spud using either the Allen wrench or the slotted screw driver.
Figure 2.14
Swirler for oil firing on forced draft.
Figure 2.15
Diffuser cones for light oil firing.
NOT E : Depending upon the materials of construction, the type of drive supplied on the oil spud may be either style. A quick inspection from the threaded end of the atomizer assembly will determine the proper tool.
2.6.2.5 Inspection
Oil tip—external inspection of the port region will reveal much about the condition of the oil gun. Visually, carbon or oil buildup around the exit ports is an indicator of
three possible problems: the tip is inserted too far, low atomizing medium pressure or flow, and erosive or cor- rosive action on the tip.
After cleaning all foreign materials from the face of the oil tip, inspect the exit ports for wear. Visual erosion, egg- shaping of the exit ports, will cause disruption of the flame pattern and should be accepted as reason for replacement.
Atomizer—external inspection of steam ports should show them free of any foreign material and the exit port should be concentric and uneroded/corroded. The labyrinth seal should be clean and unscored in the lon- gitudinal direction (see Figure 2.25).
Oil spud—oil spud should be free of foreign matter.
Tip/atomizer—atomizer labyrinth seal should insert into the oil tip with a minimum amount of tolerance.
New atomizers often require a twisting motion to achieve insertion. If atomizer/tip fit is not “firm,” steam bypassing of the atomizing chamber is possible. Check the atomizer in a new tip to determine if it is the tip or the atomizer that is worn.
2.6.2.6 Assembly
1. Lightly lubricate the threads of the oil spud and install into atomizer.
2. Lightly lubricate the pipe threads on the 3/8 in.
(10 mm) SCH 40 oil tube, and using the pipe wrench for backup, screw the atomizer assem- bly firmly onto the oil tube.
Figure 2.16
Typical rotary-type air registers.
Figure 2.17
Air register with rollers for easy operation.
Figure 2.19
Integral plenum box with inlet air damper and muffler.
Figure 2.18
Vane-type air register.
Figure 2.20
Oil gun insert and oil body receiver (with red caps).
Oil tip
Atomizer discharge
port Atomizer
steam inlet port
Fuel oil spud
Figure 2.21 EA oil gun parts.
Figure 2.22 EA oil tip.
Figure 2.23 MEA oil tip.
Oil tip Sleeve Atomizer
MEA oil gun components
Orifice spud
Figure 2.24 MEA oil gun parts.
Figure 2.25
Atomizer with labyrinth seals and steam ports.
3. Lightly lubricate the labyrinth seal of the atom- izer taking care to not load up labyrinths or fill exit port or steam ports.
4. Lightly lubricate the threads on the 1 in. (25 mm) SCH 40 steam tube and replace firmly onto the oil body. This procedure should result in the atom- izer end being 1/4 ± 1/8 in. (6 ± 3 mm) inside of the sleeve (see Figure 2.26).
5. Lightly lubricate the threads on the oil tip and install onto the oil gun making sure that the beveled portion of the tip firmly seats on the bev- eled portion of the sleeve.
The oil gun is now ready to be reinstalled into the burner.