In the papermaking process, water is a key component from start to finish. Whether assisting the chemical processes that break down the wood, enabling fibers to travel through papermaking equipment or serving as a flushing fluid to protect seals, a substantial amount is required to perform most essential functions. If not managed properly, higher water consumption rates bring higher energy costs, leading to more waste and less profit for paper mills.
Background
That is why a Georgia paper mill turned to the Garlock HYDRA-JUST system for help. The plant was having trouble sealing its digester pumps and needed a quick solution. The abrasive content and caustic nature of the raw white liquor resulted in chronic leakage.
Leaking media was just one problem, though. The mill was wasting resources and losing money because of the amount of flush water being introduced to the system. Any water that entered the media had to be removed through mechanical means or by evaporation. In addition to the cost of removal, the water removed from the media had to be processed through the plant’s wastewater treatment facility before being returned to the environment, which resulted in additional capital and energy costs.
Challenges Faced
The mill tried mechanical seals but found they lasted no longer than packing with flush bushings. In the digester pump, they had to use a flush rate of 40 gallons per minute, approximately 9.5 million gallons per year, to keep the pump operational. At a cost of over $200 per million gallons to use the water and over $1,800 per million in additional cost to remove and treat it, the mill was spending $21,000 annually on this one pump. With $21,000 going out the door each year, it became more than a process improvement, it was affecting the bottom line. Not to mention, this net loss was occurring from just one pump; there were additional water usage, energy, maintenance and equipment costs yet to be considered.
Finding a Solution
At this point, the mill decided to see if the HYDRA-JUST Sealing System could solve both problems. HYDRA-JUST is a leak free, no-dilution engineered sealing system designed for industrial pumping applications with high potential for water consumption reduction. This system not only provides water and energy savings, but it can withstand conditions in which mechanical seals would wear prematurely and have catastrophic failure. The unique design allows it to survive system upsets, just as the seal's chemical- and abrasion-resistant components allow it to excel in the toughest applications. Additionally, its heat dissipation properties enable the seal to be maintained with as little as two U.S. gallons per hour.
When compared to mechanical seals, The HYDRA-JUST provided comparable leak rate and flush water consumption. The list of benefits continued: significantly lower initial costs, greater ability to handle system upsets and temporary loss of flush water supply, a split design that allowed in-situ installation of replacement seals, and less likelihood of suffering any catastrophic failures.
Versus standard braided compression packing products, the HYDRA-JUST presented a much tighter seal, while offering much lower leakage rates both into the process and out to the environment. Because of this, the rate of flush water consumption was considerably lower than that required by a braided compression packing set. In fact, the flushing rate for the HYDRA-JUST could be as little as 1/10th of that required for braided packing.
Like compression packing, HYDRA-JUST can be installed on site. It is not necessary to move the equipment to the shop as installation of a mechanical seal requires. If water is a scarce resource, HYDRA-JUST might still allow sealing in an effective and reliable way because its water requirements are less. If a system upset occurs, the HYDRA-JUST is not subject to catastrophic failure, which can give more time to react and address the issue.
Results
In total, the HYDRA-JUST option offered lower water consumption rates, less media dilution, less thermal dilution, lower energy costs, lower water treatment costs and fewer “housekeeping” issues related to excessive water leakage in the plant. After installing HYDRA-JUST, the mill operated with 75% less water and extended its mean time between maintenance by over three times. In all, the mill was able to realize almost $17,000 in savings.
About the author: Mike Kupin is product manager of compression packing for Garlock Sealing Technologies, a multinational manufacturer of high-performance fluid sealing and pipeline solutions. He has a bachelor’s degree in industrial engineering from Ecole Polytechnique-Montreal and a bachelor's degree in business administration from Sherbrooke University. During his 20 years with Garlock, Kupin has held various positions in sales, engineering, product development and marketing. He is also an active member of the Fluid Sealing Association’s Compression Packing Technical Committee.
