Reference Manual

Paper Mill Achieves One Year ROI on Installation
of Fisher
®
Control-Disk
™
Valve
RESULTS
• Saved $120,000 in valve maintenance
• Increased uptime to 24 months
APPLICATION
Turbine used to control header pressure.
CUSTOMER
Paper mill in United States.
CHALLENGE
This application was originally designed using an eccentric disc
buttery valve. In the late 1990s, the mill installed a segmented ball
valve in order to achieve greater control. With the greater control
came an increase in maintenance. Yearly maintenance was around
$40,000 USD. Loop response required fast and frequent adjustments
to maintain tight control of the header. Because of the constant
movement, excessive seal, ball, and bearing wear was occuring on
the segmented ball valve. The extensive wear was causing high
maintenance costs. A seal with PEEK (polyetheretherketone) bearings
was tried in an effort to reduce the ball wear and help reduce damage
to the ball, but annual maintenance was still required. The paper mill
needed a solution that maintained control and improved maintenance
time between shutdowns. They wanted to reduce maintenance costs
and go two years without shutting down the turbine.
SOLUTION
The segmented ball valve was replaced with a NPS 18 Fisher
®
Control-Disk
™
valve. Sizing showed the NPS 18 Control-Disk valve
would operate in the 25-70% area, which would provide an acceptable
control range per Emerson’s EnTech
™
Toolkit denition for installed
gain (between .5 and 2). Installing the Control-Disk valve resulted in
no seal-to-disk contact or wear when controlling and the lighter disk
weight caused less bearing wear. Since the installation in 2010, an
estimated $40,000 USD per year has been saved on valve maintenance
costs.
PULP & PAPER
The valve has operated for three
years with no problems.