Reference Manual

Fisher
®
Control-Disk
™
Valve Improves Filter Water Flow Control
and Plant Availability, Saving E.On $5000 per year
RESULTS
• Improved backwash ow control, without compromising
water-plant capacity at peak demand
• Saved $5000 dollars per year by avoiding lter media
replacement
• Improved plant availability and indirectly, customer
service
APPLICATION
Water lter control at a combined heart-and-power (CHP) plant
CUSTOMER
E.On in Northwich, Cheshire, United Kingdom
CHALLENGE
A combined heat-and-power (CHP) plant is capable of supplying 360
to 380 tons of steam every hour. Raw water is cooled and then pre-
treated to remove any algae or silt. Next, it passes through one of six
dual-media lters (containing anthracite and three different media
levels of garnet) before being sent to the ltered-water holding tank.
Once the ow across the lter bed drops signicantly, a cleaning
procedure is initiated. The last step (cleaning) involves air scouring and
back washing to remove any material blinding the lter.
Besides providing power to area residents, the E.On-CHP facility
supplies steam for two nearby soda-ash (Sodium Carbonate)
production plants in Winnington and Lostock. The two sites use a large
quantity of steam and return about 37% of the un-used portion to the
CHP plant as “hot condensate.”
The constant challenge for the E.On-CHP plant is to replace the boiler
feed water lost  either during the steam-transfer process or during
boiler blow-down. The E.On-CHP water-treatment operation faces a
continuous demand for make-up boiler feed water, between 400 and
520 m3/hour.
The facility has also had problems controlling the back-wash ow. The
original buttery valve in this process could not provide a steady ow
rate and caused media to be lost through the lters. The lter materials
(anthracite and Fine Garnet) had to be replaced or relled at an average
cost of $5000 USD per year.
“The Fisher
®
Control-Disk valve
not only controls the backwash
flow rate more accurately, but
also it delivers, when 100% open,
a flow rate adequate to meet the
water plant demands, without
restrictions. Its performance
and reliability led to a savings
of $5000/year and enabled us to
improve our customer service.”
Neil Price,
Improvement and Performance Coordinator
Winnington CHP, E.On
United Kingdom
POWER
The Control-Disk
™
rotary valve offers excellent throttling
performance and an equal percentage ow characteristic,
which provides an improved throttling range comparable
to that of a segmented ball valve. This improved capability
enables control closer to the target set point, regardless of
process disturbances, and reduces process variability.