A large pulp and paper mill in the Bío Bío region of Chile was looking to install a new evaporator unit to improve uptime and reduce energy consumption. Mill engineers were concerned that contaminated water could cause unplanned downtime and unscheduled maintenance. The mill needed to find a cost-effective long-term solution to the dirty water issue before the new evaporator unit went into operation.
The Diagnosis
John Crane proposed the unit’s 44 new centrifugal pumps include mechanical seals instead of gland packing as well as a water filtration system to eliminate the contaminants. When implemented, the proposal would result in low system maintenance and high reliability. A John Crane water monitoring and control system were included to reduce water and energy costs.
Finding a Solution
John Crane’s Safejet 330 in-line seal water filter was installed to clean the contaminated water before entering the evaporator unit. The Safejet 330 uses layers of laminar filtering to automatically remove impurities before they reach the mechanical seals, flushing impurities through valves located at the bottom of the unit, releasing the contaminants to a drain. Type SE2 dual mechanical seals were installed on the pumps because of their well-known reliability in other severe pulp and paper applications. Safeunit™ seal water control and monitoring systems were added to each pump to further optimize the process.
The Outcome
The three-component system remains in operation with a mean time between repair rate (MTBR) of more than eight years. The installation has dramatically reduced costs, saving the mill over $255,000 in annual water expenses and saving over 50 million gallons (191,163 cubic meters) of water.
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