Centrifuge Improves Waste Treatment

Article From: Products Finishing, , from Gardner Business Media

Posted on: 8/1/2001

Roll Coater needed a more reliable water pollution control system. Therefore, the company installed a centrifuge with a new design that reduced downtime and reduced the company's waste treatment problem...

Environmental regulations and waste treatment processes often leave many finishers exasperated. The regulations force finishers to deal with a mountain of paperwork and a pile of red tape to show regulating agencies that they are complying with the law. Waste treatment processes are often viewed as an added expense that finishers wish they didn't have. Some finishers even have problems with unreliable waste treatment systems that prevent them from coating parts. Basically, finishers spend a lot of time on a problem that has little to do with their core business or area of expertise.

Too Much Downtime

Roll Coater (Greenfield, IN), a steel coil coater, was one of those finishers that simply wanted a more reliable waste treatment system. The company was using a centrifuge to treat zinc-laden water from its pretreatment system. The centrifuge reduced the amount of sludge that Roll Coater needed to send to a landfill by removing particulate from the wastewater from its pretreatment system. Once the particulate was removed, the water could be reused, reducing the amount of wastewater produced and decreasing the company's operating expenses. Plus, the zinc particulate taken from the water could be recycled, generating income for the company.

But, the centrifuge proved unreliable. Quite often it would break down and require a substantial amount of time to repair. Despite the benefits of using the centrifuge, the extensive downtime was becoming quite a problem. "I was tired of our centrifugal separator breaking down. I didn't care whose separator we got. I just wanted a better one," stated Mona Salem, formerly of Roll Coater.

Reliability to the Rescue

To avoid downtime due to mechanical complexity and unreliability, many finishers have given up on centrifuges and turned to paper filtration systems, sludge tanks and disposal. This is especially true when the finisher is using the centrifuge for a critical filtration process, such as the one at Roll Coater. While the paper filtration systems and sludge tanks have been more reliable than centrifuges, their operating costs are significantly higher. However, the costs associated with downtime have outweighed the higher operating costs for many finishers.

But, Roll Coater knew the potential value of a reliable centrifuge, which is why it invested in a new centrifuge from Midwest Engineered Products. This centrifuge has a new bowl/blade clutch design with a single AC motor and single AC motor drive, making the centrifuge more reliable.

Why is this centrifuge more reliable? The new centrifuge at Roll Coater positively synchronizes the bowl and blade assembly. A positive locking clutch (see the Process Cycle animation and Scrape Cycle animation) couples the bowl's main spindle and the blade together so that both rotate at precisely the same speed when processing fluids. The fluid is forced to move smoothly throughout the bowl as it strikes an accelerator on entry and descends. Physically, that even, "quiet" flow maximizes the law of centrifugal force, which states that any particles heavier than the liquid are thrown outward and packed against the bowl wall. Such synchronized rotation also prevents any oscillation of the blade, maximizing separation efficiency and minimizing bearing wear. Oscillation is what you want to prevent, since it creates a washout of solids from the bowl, particularly superfines. Because the bowl is a thick, centrifugally cast stainless-steel precision-machined part, vibration is dampened, further enhancing bearing life. The increased bearing life is the key to the improved reliability of the centrifuge used by Roll Coater.

Now, not only is Roll Coater enjoying all the benefits a centrifuge has to offer, but it also can depend on the centrifuge's reliability. "I need it for my process. It saves hundreds of thousands of dollars in operating expense. We can't afford to be down," stated Mona Salem. Plus, this design is said to allow the centrifuge to remove up to four times the quantity of fines that traditional centrifuges can filter out and extend the fluid life of any process four times. While that doesn't completely eliminate the exasperation resulting from waste treatment problems, it sure does help.

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