Durco Filters Systems for Pulp & Paper

Tubular Backwash Systems are a perfect solution to polish White Water for reuse and spray nozzle protection.

Pulp-Paper-Case-Study
Case Study
Tubular Backwash Filter1200 GPM TF System, 60-70 PSIG, producing clarified white water for re-use at the mill
Click here to learn more about Durco Filters Tubular Backwash Filters

Application

The unfiltered raw white water is removed from the pulp slurry at the wet end of the Fourdrinier paper machine, and undergoes multiple filtration steps before it can be reused. A Pre-filter step passes the raw white water through a device called a Sav-All. This separates out valuable cellulose fiber so it can be reclaimed to the Fourdrinier feed chest.

Challenge

After passing through the Sav-All, the white water still contains small amounts of fibers. Since these fibers have been mechanically and chemically treated to interlock and form a sheet of paper, they tend to form lumps and knots that can harm downstream systems like knock off showers that contain calibrated directional spray nozzles.

Solution

A Durco Filters Tubular Backwashing Filter (TF) Polishing System efficiently removes the trace quantities of cellulose paper fibers from the pre-filtered white water stream. Typically, for shower system spray nozzle protection, the required filter retention is calculated by dividing the nozzle orifice size by a factor of 6. For example, for a 0.035 inch orifice, a filter retention of 0.006 inches is required. 

The Benefits

Energy Savings: By re-using process white water (typically at ~120°F) versus consuming fresh water (averaging about 50°F) significant energy savings are made due to avoiding the necessity to heat the relatively cold fresh water.

Reduction in Chemical Additives: By reusing the process white water, which retains many of the special chemical additives required, the make-up volume of these costly additives is reduced.

Fast Payback: In A Typical Paper Mill Application, With A Fourdrinier Machine Or A Cylinder Type Machine, A Durco Filters Tubular Backwash Filter System Can Often Provide A Full ROI In As Little As 30 Days Of Operation!

Fewer Shutdowns for Nozzle Servicing: A clean nozzle is a productive nozzle.  By adequately protecting your spray nozzles, there is improved efficiency in overall production, as well as fewer downtimes for nozzle maintenance/replacement.

CASE STUDY:  18 TRILLION Gallons and Counting!

Technical Data

  Location Papter Mill, Northern Michigan, USA
  Equipment Durco Filters TF Tubular Filter ontinuous Filtration System, 6-filter tube array wth slotted filter elements and fully automatic backwash option.
  Flow Rate 1200 GPM @ 70 PSIG
  Application Pulp Slurry White Water Polishing for Water Re-Use
  Performance As of May 2012, this Durco Filters tubular backwashing system (installed in early 1987) has handled 17,996,800,000 gallons of water.  If you were to put each filtered gallon into a 1-gallon can, it would create a stack of cans that would reach to the moon more than 14 times!  The Durco Filters designed tubular filter is very reliable while achieving significant energy savings and reducing consumption chemicals.

Experience

Many years of empirical data and lab testing have proven that slotted filter elements perform best in fiber-laden water filtration applications. In comparison, wire mesh filters (that have a weave of fine stainless steel wires) tend to cause the fibers to 'staple' to the mesh, making their removal from the filter elements extremely difficult. The smooth surface of the slotted tubular filter media avoids the stapling effect, and allows the tubular filters to be cleaned in place by manual or automatic backwashing.

Consult a Durco Filters Application Engineer to arrange testing and analysis of your pulp slurry white water process stream and determine the optimum filtration technology for your particular operation.  You can also fill out our Filtration Fast Track Form (below) and one of our Application Engineers will get back to you right away.