Good mixing makes the difference.

In February 2003, Sappi Fine Paper North America's Somerset mill in Skowhegan, Maine invested in a new solution for injection of retention aid and silica. The main objective was to eliminate wet end breaks caused by polymer lumps from the chemical injection system. The breaks ended and at the same time Sappi saw better paper quality and an acceptable ROI.

Previously, in 2002, Sappi Somerset recognized that it had a problem with polymer build-up on the post screen saw quill used for retention aid injection on PM 1, which produces fine coated paper. This would create lumps that caused breaks in the sheet.

"We needed to find a new way to inject polymer to reduce wet end breaks," said Jeff Lettenberger, production engineer for PM #1. "When I saw the TrumpJet chemical injection system, I realized that not only would it solve our problems with breaks, but also improve mixing and sheet formation."

HIGH SPEED INJECTION

The TrumpJet injects chemicals at high speed and high volume without damaging shear sensitive chemicals. This results in immediate and better mixing, without a quill actually penetrating into the pipe, according to the manufacturer and marketer, Wetend Technologies Ltd., Finland.

TrumpJet mixing technology makes it possible to use headbox stock or white water as the injection media, which replaces the need for hot water dilution, according to Wetend Technologies. Sappi Somerset will save by using process white water instead of heated fresh water. "Limiting the waste of fresh water was a big factor when pushing for TrumpJet," said Lettenberger.

Major mills--including the world's largest newsprint machine in Sachsen, Germany--use this technology for key applications. This was another reason why Somerset was willing to try it.

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"We must continue to invest in cutting edge equipment," said Lettenberger. "This is a technology that works. The initial investment may be a little larger than building a cross quill or a ring, but the result is much better and it keeps saving money for the mill."

Lettenberger believes that the flexibility the installation gives him is another important benefit. Now that the system is installed, he can experiment with different ways to inject polymer and other materials.

According to Wetend Technologies, references show that TrumpJet systems result in better retention, improved formation, and lower 2 sigma values. In addition, the amount of polymer can often be substantially decreased. Improved formation shows secondary benefits such as less wear on supercalender rolls and better machine runnability, according to the company.

At Sappi Somerset, formation has improved and there is better "see through." In addition, basis weight standard deviation has decreased. Sappi has reduced the polymer dosage dramatically and will save significantly on energy and water and lower polymer consumption with fewer breaks.

The results seen on PM1 led the mill to install a similar system on PM3. "We have seen that TrumpJet gives the best result. Because it was a cost saving project, we were able to motivate the investment," said Debbie Tozier, project engineer at the mill.

The TrumpJet was invented by Jouni Matula, an entrepreneur and the CEO of Wetend Technologies Ltd. Wetend has installed over 100 systems in 16 countries with more than 300 TrumpJet mixers. One of the most recent installations is at Stora Enso's mill in Duluth, Minnesota. Five TrumpJet models are available and are used for retention aid polymers, micro and nano particles, sizing agents, dye, starch, biocide, polymer for sludge and PAC for mill fresh water treatment.

KAROLINA EHRLEN, KPS 

ABOUT THE AUTHOR:

Karolina Ehrlen is project engineer for KPS, Bethel, Maine, USA. Please contact her by email at [e-mail].