When Premium Plant Services tested Jetstream's DrillJet™ and Banshee rotating nozzles while cleaning heat exchangers at an ethanol plant in the Midwest, the experiment yielded inarguable results.
Using automation set to feed both tools at the same rate, the DrillJet™ cleaned 50-foot tubes three to five seconds faster than the Banshee, which, at 1400 tubes per bundle, this suggests the Drilljet™ cleaned the 50-foot tubes 12% more efficiently. Furthermore, on completely plugged tubes, the DrillJet™ eliminated blockages faster per tube according to the operators. Operators found that both the Drilljet™ and Banshee cleaned with equal thoroughness, but the Drilljet™ traversed the tubes faster.
Premium Plant used a total of six Jetstream 4220 pumps for the heat exchanger portion of this shut down. The exchangers were 60ft above the pumps, requiring 400 feet of 13mm 20K hose and 65 feet of 8mm 9/16LH lances for each nozzle. The water source was a filtered local well at 53° F, making it slightly warmer than the outdoor temperature of 51° F. Three heat exchangers, labeled Alpha, Bravo and Charlie, were scheduled to be cleaned using automation equipment. Alpha was the exchanger where the comparisons were made and where data acquisition took place. Bravo was kept only for StoneAge® Banshees while Charlie was utilized for DrillJet™ only. Operators mounted dual lance feeders on Alpha and Bravo for their cleaning operation, while Charlie used a single lance feeder for its cleaning operation. Each exchanger contained around 1400 tubes, 1.4 inches in diameter and 50 inches long.
Before the cleaning, a hard shell of baked Calcium Oxalate coated and clogged the interior tube walls of the exchangers. This material is almost impenetrable by a 20K PSI jet and is usually dislodged when the water jet is injected forcefully between the product and the wall of the tube. As the tube walls of these exchangers are only rated for a maximum of 30K PSI, using a 20K PSI blasting pressure through a rotating nozzle was adequate.
Scale and contamination blocked around 5% of the tubes in both exchangers, and a hard scale coated the remaining ID of the tubes. Operators used a purpose built bore scope to inspect the tube before cleaning. They estimated that the scale lay around .5mm to 1.5mm thick throughout the tubes, and in some areas, the scale coated the tube up to 3mm thick. This generally reduces the 35.6mm tube diameter to around 31mm. Consequently, only about 7mm of clearance is available, or 3.5mm on either side of the DrillJet™. With only 3.5mm between the jet orifice and the tube contaminant, the orifices were all very close to the calcium deposited on the ID of the tubes.
In the morning, operators cleaned heat exchanger Alpha using a dual lance feeder equipped with two 24mm 7-Jet High Flow Drilljets™ capable of 10-24 GPM at 20K PSI. Cleaning operations on heat exchanger Bravo began around the same time, using another dual lance feeder equipped with two Banshee 24mm nozzles using 044-D universal heads with a flow rate of 17-20 GPM at 20K PSI. The 7-jet DrillJet™ used is most comparable to a Banshee when equipped with a universal head rather than a polishing head.
After two hours of cleaning Heat Exchanger Alpha using only DrillJets™, operators replaced one of the DrillJets™ with a Banshee 24mm with the Universal 044-D head in order to directly compare the cleaning ability of the two nozzles. Even with the same feed rate on the lance feeder, the DrillJet™ reached the end of the 50-foot tube around three to five seconds faster than the Banshee.
Operators could not distinguish between tubes cleaned by the DrillJets™ and Banshee after bore scoping a sample of four tubes from heat exchanger Alpha. On moderately obstructed tubes, the DrillJet™ and Banshee provide equivalent cleaning power, but the DrillJet™ cleaned faster than the Banshee.
When the nightshift relieved the dayshift personnel and continued cleaning operations, operators inspected the original DrillJets™ that ran for over seven continuous hours on Heat Exchanger Alpha. They found that the borescope displayed an indistinguishable difference in cleanliness.
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