Reference Manual

CHEMICAL

For more information: www.Fisher.com

U.S. Paper Mill Significantly Reduces Process

Variability with Fisher

Control-Disk

™

Valves

RESULTS

•Process Variability Significantly Reduced

Loop 1: from 8.0% to 3.0%

Loop 2: from 3.5% to 1.6%

APPLICATION

Vacuum control loops that remove water from pulp stock

CUSTOMER

A paper manufacturer in the U.S.

A paper-producing machine at a U.S. paper manufacturer outputs

more than 5,000 feet per minute on a 30-foot-wide roll. It uses a twin

wire former to turn pulp stock, which is approximately 98% water, into

paper. The former is the first place that water is removed from the

pulp stock, using a vacuum control loop on the multi-foil shoes.

Water removed from the pulp stock at this point has a big effect on

the operation of the rest of the paper machine. Poor control in the

former can lead to problems with consistency and sheet formation.

CHALLENGE

The two troublesome high-performance butterfly valves were both

operating below 20% travel. The valves spent most of their time in

manual control after their installation 7 to 8 years prior. Plant

personnel made unsuccessful attempts at placing these loops in

automatic control. High-performance butterfly valves have an

After replacing two

troublesome valves with

Fisher

Control-Disk

™

valves,

poor control was not an issue

anymore.

PULP & PAPER

PAGE 1
PULP & PAPER CHEMICAL U.S. Paper Mill Significantly Reduces Process Variability with Fisher® Control-Disk™ Valves RESULTS •Process Variability Significantly Reduced Loop 1: from 8.0% to 3.0% Loop 2: from 3.5% to 1.6% APPLICATION Vacuum control loops that remove water from pulp stock CUSTOMER A paper manufacturer in the U.S. A paper-producing machine at a U.S. paper manufacturer outputs more than 5,000 feet per minute on a 30-foot-wide roll.
PAGE 2
POWER PULP & PAPER GENERATION inherent flow characteristic that is linear. With an inherent linear characteristic, valves commonly have a narrow travel band over which they exhibit an optimum installed process gain. Typically, this range is 30 to 50 percent of total travel. This band is called the control range. Outside the ideal range, process gains become very high or very low, and high process variability results. Installed process gains were greater than 4 (the EnTech desirable range is 0.5 to 2).