Brochure
Chlorine Dioxide Addition
After digestion, end products that are required to be whitened go to the bleach plant. Chlorine dioxide has rapidly become the industry
standard bleaching agent because of its selectivity in destroying pulp lignin without degrading cellulosic fibers, thus preserving pulp strength
and providing stable brightness.
Modern mills typically have pulp stock enter the oxygen delignification stage before the medium consistency pulp heads to the conventional
bleaching sequence. These can vary from four to six separate stages depending on the end-user’s requirements. A standard mill would
utilize a DE
OP
DED sequence, or an alternating sequence of chlorine dioxide (D), alkaline extraction stages (E), oxygen (O), and peroxide (P)
brightening stage. This alternating sequence of chlorine dioxide and alkaline help to break down the increasingly smaller amounts of residual
lignin.
This valve is subjected to high corrosion due to the chlorine dioxide material, and accurate control is necessary because of the high costs
of chemicals.
Product Solutions
Fisher
®
Pulp and Paper Solutions | 17
Bleaching
n MAXIMUM FLOW CONTROL V-notch ball contouring provides modied equal percent characteristic.
n ZERO LOST MOTION Splined driveshaft and shaft-to-ball pinning allows for tight control.
n LONG SERVICE LIFE Rugged seal and bearing design for extended service.
n LOW FRICTION Bearings with minimal friction provide optimal control and drop-in-place for
easy maintenance.
n REDUCED MAINTENANCE Flanged valve body reduces alignment and installation time.
n ASSEMBLY SIZE Actuator prole promotes smaller envelope package size for tight spaces.
n EXOTIC MATERIALS Alloy valve capabilities available for high corrosion applications.
Fisher V150 Vee-Ball control valve, 2052 actuator, and FIELDVUE DVC6200
Bleaching