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Volume 1 Issue 2 1st Quarter 2025

In this Issue

Welcome to Fiber Foundations for 1st Quarter 2025, exclusively sponsored by Kadant Black Clawson.

Kadant Black Clawson



Heli-Drum - Why and What is it?

With waste paper furnish continuing to change – what will be your furnish next year – or 5 years from now? Furnish trends are towards more difficult to pulp, higher trash loads and small specialty grades. Ideally – for system flexibility and maximum yield following the pulper the furnish should be close to flake free. If your pulping technology isn’t working well for you today – what should you be looking at for a replacement?


When Kadant started working on the Heli-Drum system the concept was to combine the pulping characteristics of high consistency batch pulping where pulping is generally done to flake free and is relatively gentle on contaminants – with the trash handling capability of a drum pulper. This removes the batch detrasher volume limitation typically operated with the high consistency batch pulper.

 

The first attempt was well over a decade ago, directly connected an existing pulper with a drum screen. Note than an extraction chamber needs to be fitted to the pulper in order to extract though a bedplate in the pulper, concentrating the debris in the pulper (versus in a detrasher). This didn’t work well as the instantaneous trash load could overwhelm the drum screen.


The next installation utilized a (required) buffer tank between the pulper and the (large) drum screen. The buffer tank is sloped and as its name suggests it buffers the instantaneous flow of rejects from the pulper to a more moderate 5 to 8 minutes feed to the large drum screen.


As the installations progressed – on Tetra Pak®, mixed paper, office waste and other furnishes it quickly became evident that the filtrate from the drum screen needed to be addressed for glass and other heavy contaminants. The system has evolved to have a horizonal screw at the bottom of the sloped side drum screen filtrate tank to feed an inclined screw for removal of heavies.


The system has matured to include pulpers up to 60m3 in pulping volume. It includes a high consistency pulper with extraction plate, rejects door to a buffer tank, on the discharge from the buffer tank there is a weir gate to limit the flow to the large drum and the drum has a conical discharge to help retain material in the drum and recover fiber from the rejects. Also as noted above the filtrate tank removes settled heavies. Most systems have two pulpers sharing a common buffer tank and drum.


North America has over a dozen of these pulpers with over 600 m3 of pulping volume – most operating on mixed paper sized for trash loads up to 30%. Europe has numerous pulpers in operation including an installation using 100% post-consumer Tetra Pak® at over 40% out throws.


By Neale Fetterly

Senior Application Engineer

Kadant Black Clawson

Kadant Homepage

https://fiberprocessing.kadant.com

 

Kadant Pulping Systems

https://fiberprocessing.kadant.com/en/products/pulping


Heli-Drum Webpage

https://fiberprocessing.kadant.com/en/products/pulping/heli-drum-pulping-system


Heli-Drum Brochure

https://fiberprocessing.kadant.com/en/?preview=1&option=com_dropfiles&format=&task=frontfile.download&catid=22&id=64&Itemid=1000000000000


Heli-Drum Videos

https://vimeo.com/1005852023


and


https://vimeo.com/736574945


Green Liquor Clarification: Comparing Current Systems in the Field

Chris Knollman, Sr. Applications Engineer

Chemical Pulping Group

Kadant Black Clawson

I met with Senior Applications Engineer of the Chemical Pulping Group at Kadant Black Clawson, Chris Knollman, to discuss some of the available options currently employed in kraft mills for the clarification of liquors. For today’s discussion we have selected to compare the pros and cons of the top three most common systems – Clarifiers, Pressure Disk Filters, and Pressure Tube Filters.


We’ll be looking at the relative cost, footprint, and general performance of each system, as well as other important considerations such as maintenance and energy consumption.


Clarifiers


Most recognized as the large cylindrical storage tanks common to many chemical production facilities, clarifiers can be considered the option with the largest footprint and apparently greatest initial capital expenditure. This cost, however, is greatly mitigated by the fact that most mills have suitable storage tanks already onsite. Additionally, current upgrade and retrofit technologies are available that can vastly improve performance in existing systems which give this option an attractive edge over filtration solutions.

 

Chemical recovery from clarifiers provides a low green to white ratio and high solids underflow. These units run slow and steady, reliably delivering 38 to 40 percent solids for conventional systems and up to 55 percent or more with high-torque rake systems.

 

That said, energy use is the real advantage found with clarifiers. Current systems can run efficiently and reliably with the low power draw of a 5-horsepower motor, while the other solutions demand the vastly greater energy draw of 500-horsepower vacuum pumps.

 

With well-run clarifier systems, maintenance is low and there are few spare parts costs. There is an additional integral benefit as all volume above the bustle pipe is considered as liquor storage removing the need for any post-filtration White Liquor storage tanks.

 

Pressure Tube Filtration


These once popular systems were valued for their relatively small footprint and low upfront cost. However, these undersized units proved inconsistent performers and required frequent maintenance, and an ongoing annual replacement cost of the filtrate “socks” worn from frequent mud build up.

 

They deliver a high ratio of green to white liquor and suffer from low underflow solids, 38 to 40 percent maximum with no options to increase. They also require lime mud washing in the post-filter stage, more causticizer retention time than clarifiers, and provide no liquor storage. As a result, these units are outdated and have had few if any new installations.


Pressure Disk Filtration


Disk filters provide excellent chemical recovery, delivering a low green to white liquor ratio and solids up to 75 to 80 percent. Additionally, lime mud washing is not required.

 

Unfortunately, this is where the good news ends. High maintenance and frequent disk segment replacements add to a large initial capital investment and generally high operating cost. As discussed earlier, high energy use is the real cost accelerator, with demanding high horsepower vacuum pumps at the heart of the system.

 

Like tube filtration, disk filters demand more causticizer retention time than clarifiers and a dedicated liquor storage tank is required.

By Peter Alexander

Staff Writer

Kadant Black Clawson

Kadant Recausticizing:

https://fiberprocessing.kadant.com/en/products/recausticizing

 

“What’s Inside a Great Clarifier?” Video

 https://vimeo.com/488566779

 

“Chemical Pulping Recaustisizing Loop” Video

https://vimeo.com/687232391

 

Kadant Fiber Processing:

https://fiberprocessing.kadant.com/en/

Innovation is constant


I remember twenty-five years or so ago when Jon Kerr was touring me through the old Black-Clawson shops in Middletown, Ohio. He was showing me some of the first pulper rotors that were foil shaped (as in built like an airplane wing). Neale Fetterly's article at the top this month reminded me of this.


Folks outside the pulp and paper industry just don't understand our business from fiber sources to manufacturing to distribution. They certainly don't understand the continual innovation, either.


I have been having fun recently explaining our business to my private strength training instructor. She's older than me, in better shape than me, but naive about our business. She thinks it is fascinating.


Like an evangelist, I take it upon myself when the opportunity presents itself to tell the lay person about our business. I think it is important to explain our business to the every day person on the street. Most get the news about us from unfriendlly sources and it is our job to spread the good word about how pulp and paper products enhance their life.


Now, go back and read Neale's article again. Saving the good fiber and getting rid of the dirt is what it is all about--and continuously improving the way we do that is paramount.


By Jim Thompson, CEO


Talo Analytic

International &

Paperitalo Publications


jthompson@taii.com

Mixed paper, OCC prices end year on downward trend

By Recyling Today

Last year ended with some cautious optimism around demand trends, particularly with packaging grades made of recovered paper, but price trends for mixed paper and old corrugated containers (OCC), especially, leave much to be desired.

Read the full article here

Identification and characterization of sticky contaminants in multiple recycled paper grades

By Western Michigan University

Organic sticky contaminants represent one of the biggest technical challenges in the paper recycling process.

Read the full article here

Recent Innovations in Sustainable Practices in the Pulp and Paper Industry

By ResourceWise

In today's rapidly evolving world, the pulp and paper industry is at the forefront of sustainability efforts, playing a crucial role in the transition towards a circular economy. As environmental concerns continue to rise, the industry is innovating to reduce waste and enhance recyclability, ensuring that resources are used efficiently and responsibly.

Read the full article here

Europes Pulp and Paper Industry Shows Resilience

By American Recycler

The decrease in paper and board production in 2023 (-13 percent) resulting from low demand was far more pronounced even than during the Covid-19 crisis (-4.7 percent in 2020). This is a trend that is not particular only to Europe, but the global slowdown has been worsened in the EU by comparatively high costs for production inputs, notably energy. The European economy as a whole has lost momentum, against the background of a high cost of living, monetary tightening, and a weak external demand.

Read the full article here

Fiber Foundations™ is a joint production of Paperitalo Publications and Kadant Black Clawson, LLC and is exclusively sponsored by Kadant Black Clawson, LLC