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Process Cleaning Magazine
© 2012
AMT-The Association For Manufacturing Technology
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Inside the building, a tilting tower can position the core drill vertically for drilling and horizontally for core removal.
The Barrett 401 Sludge Extractor separates the drilling fluid from the ice.
The operator uses an integrated lift-and-dump mechanism to load the centrifuge.
The drill cutter is shown here with the ice core.
Problem: Getting a reliable system to recover drilling fluid from ice chips before they are reintroduced to the environment in Antarctica.
Solution: Kine-Spin/Barrett 401 SES centrifuge
Results: Without interruption, the unit has continued to deliver in its mission to conserve drilling fluid while reducing the impact on the environment.
One of the most exciting things about technology is when someone uses creativity to effectively put it to use in a way that is outside the scope of the original design. Such was the case when a team from the University of Wisconsin’s Ice Drilling Designs and Operations (IDDO) group ran into a need that was totally new to Kinefac/Barrett, the Worcester, MA-based centrifuge maker that they approached for help. The process stretched every boundaries of the fluid processing capabilities of the company’s Kine-Spin centrifuges.
For the past several years, and probably for two years to come, IDDO has participated in the “West Antarctic Ice Sheet Divide Ice Core.” This program is part of a government-funded global effort to better understand climatic changes that have occurred over the most recent 100,000 years of geologic evolution. Ice cores—cylindrical samples—are taken from the ice sheet in sequence to examine what is happening in our environment and how it validates or refutes current historical data generated by other means.
To get these samples, IDDO developed a core drill system first tested in Greenland and then put it into operation in the Antarctic. The system is based on a conventional ice core drilling machine supplemented by a Kine-Spin Centrifuge system and a core refrigeration system. The core drilling machine used to obtain the cores is similar to that used in hydraulic and other in-ground applications.
The drilling tube is a hollow-centered element that traps the core while teeth on the end of the drill tube cut through the ice sheet. The bore hole is filled with a drilling fluid to keep the hole from closing as the cores are removed. Cuttings generated while drilling a core are saturated with drilling fluid, then collected in the drill and brought to the surface at the end of each drill run. To conserve drilling fluid and reduce the impact on the environment, the fluid must be recovered from the ice chips before they are reintroduced to the local environment.
It’s at this point that the Kine-Spin/Barrett Division of Kinefac Corp. enters the picture. The University had already performed initial tests, and as a result, in 2005, a 401 Sludge Extractor with an explosion-proof motor and controls was installed to separate the drilling fluid from ice at the West Antarctic Ice Sheet ice flow divide.
The concept of the equipment was straightforward—separate the fluid from the ice—but it had one problem that the users at the University had to solve: The variation in density between the two fluids is relatively small and does not lend itself to easy separation.
Luckily, the team was aware of the capabilities of Kinefac’s Barrett 401 centrifuge. In addition to the machine’s basic functional capabilities, its simple design provided low-maintenance reliability—critical characteristics considering what a service call would involve.
“The centrifuge continues to work problem-free for us and was integral to the success of this season,” says Jay Johnson, drill operations engineer for IDDO.
The operator uses an integrated lift-and-dump mechanism to load the centrifuge at as many as four 16-gal cycles per hour. The residual drilling fluid is almost totally removed, and the ice cake is available to be broken up and emptied outside of the drilling building.
The cores, which contain successive layers of ice, combine trapped CO2 and other gasses that are capable of further defining what was happening in the atmosphere above it. The core drill is housed in a drilling building that is essentially half covered by the existing snow line. A tilting tower positions the drill vertically for drilling and horizontally for core removal. The system, which can run 24 hours a day, generates cores that are 4.8 inches (122 mm) in diameter and up to 9.84 ft (3 m) long. It is capable of drilling through the entire ice sheet, which is about 11,300 ft (3450 m) thick at the site.
As each core is removed from its hole, the ends are cleaned up and stored in their solid frozen state to clearly illustrate what is happening at the surface of the Antarctic. Finally, the core is removed and placed in an inspection station where researchers record preliminary data regarding the layers and their locations. Thereafter, the cores are stored in refrigerated shipping containers for subsequent return to the U.S., where sections are made available for further scientific analysis. The team believes that the current process for drilling and handling the core drilling swarf results in a series of very high quality cores.
The core drilling location was selected for its high snow accumulation rate, which translates into thicker annual layers than other locations. This high resolution core will make it possible for scientists to see yearly climate history approximately 40,000 years back and decadal history dating back about 100,000 years.
As the project is described, “The coordination of timeline resolution and the small age offset will allow the universities to study interaction between climate operations and atmospheric composition with a level of detail previously not possible in deep, long Antarctic ice core records.”
Additional Applications
Since Kinefac acquired Barrett’s centrifuge business six years ago, the company has seen a number of new and unexpected opportunities in addition to the Antarctic studies. Centrifugal force (coined the “invisible force,” by Kinefac engineers) operates on all materials being spun. As a result, it allows for a range of new opportunities such as hypotube cleaning, where cleaning fluid is forced through long (up to 12-inch) tubes with bores as small as 0.007 inches.
Before centrifugal cleaning was considered as an option, such tubes were cleaned through a sluggish process whereby solvent cleaning fluids were pushed through the tiny hole with pressure. By spinning such tubes in the correct orientation, it’s practical to achieve high flow without any major external application of fluid pressure. Centrifugal cleaning can be applied in a variety of small exit areas and achieved with significantly lower processing time than that required for ultrasonic cleaning.
Kine-Spin/Barrett also produces centrifugal cleaning systems that subject batches of machined, stamped, or headed parts to a force 300 times greater than gravity to quickly remove liquid process lubricant. Then, various wash, spray or swirl cycles with aqueous or other dissolving solutions are added to remove any other residual material. When necessary, heat supplements the cleaning and drying action, and then rust preventive or other protective coatings can be applied—all within a Kine-Spin centrifuge equipped with fluid handling, fluid storage, drying and process control devices.
Although Kinefac wasn’t looking to go beyond the relatively normal fluid separating capabilities of its centrifuges, when the need presented itself in the form of the IDDO project, service and support were readily available to expand the centrifuge line as needed.
The imaginations of engineers and scientists can find many uses for the “invisible” cleaning force.
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Photos courtesy of Jay Johnson, drill operations engineer at IDDO.