In modern pulp and paper production, efficiency, reliability, and ease of maintenance are key factors in selecting equipment for process optimization. One such critical piece of equipment is the hydrocyclone cleaner—a device that uses centrifugal forces to separate contaminants from pulp slurries. Although this technology has been present in systems for decades, improvements and innovations continue to redefine performance expectations across the board.

The Xcel NT™, Kadant Black Clawson’s newest forward cleaner, stands out with several industry-leading features: simplified and modular maintenance, integrated reject dilution, optimized flow paths that prevent pressure loss, and the capability to operate at high consistency with high efficiency. Together these innovations are not just incremental—they offer a transformative impact on mill operations by reducing downtime, improving yield, and maintaining high-quality output with minimal energy consumption.

High Consistency Operation with High Efficiency

Perhaps the most game-changing capability of this cleaner is its ability to operate at high feed consistencies—up to 2.2% or higher—without sacrificing separation efficiency. This is a major advancement, as conventional cleaners often require dilution to operate effectively, which increases water usage and process complexity.

Through a combination of carefully balanced cone geometry and vortex stability, the unit maintains tight separation thresholds even at elevated consistencies, removing contaminants like sand, plastic, bark, and shives with minimal fiber loss. This allows mills to simplify upstream dilution processes, reduce water consumption, and increase the overall system capacity without major capital investments.

Lower stages in an Xcel NT™ system utilize an innovative design where the hydrocyclones are installed inverted, with the reject tip pointing up! Although this looks odd at first, the forces at work inside the cone are hundreds of times greater than the force of gravity, so the orientation doesn’t impact separation, but it does have a huge impact on maintenance.

Unfortunately, equipment plugs occasionally. As much as equipment design tries to minimize this, it is a fact of life in a paper mill. With the inverted design of the Xcel NT™ reject stages, unplugging is simplified; sometimes to the point of being automatic. Once a plugged hydrocyclone is isolated and there is no pressure driving flow to the reject tip, plugs of sand or other grit often submit to gravity, falling and breaking apart in the hydrocyclone to be processed when the hydrocyclone is brought back on-line. In more stubborn scenarios, the inverted design does make disassembly and reassembly easier since the components naturally stack together. 

The reject area of a stock preparation system in a paper mill is typically one of the most ignored and neglected areas unless something occurs which impacts the system operation. That is not ideal as this is one of the areas in a stock preparation system that should be constantly monitored as it can have a direct impact on mill operation. The final rejects from a stock preparation system drive the overall system yield. A higher yield means that less fiber is required to be fed into the system compared to what is produced off the Paper Machine. An improved yield results in direct cost savings when looking at the cost per ton of paper produced.

When reviewing the overall losses from a stock preparation system, the coarse rejects area processes most of the reject material. This is because the incoming recycled fiber contains outthrows (material not suitable for producing a given paper grade). The amount of outthrows can vary depending on the recycled fiber furnish that is being used. For OCC furnish, this value is typically up to a maximum of 5% by mass. However, for systems that run a blend of Mixed Waste furnish, the outthrows can reach up to 20% by mass. This can be a huge volume of material that needs to be efficiently separated from the fiber that is used for producing paper.

Outthrows can be made up of a variety of materials (plastics, wax, metal, off grade recycled paper, etc.). The majority of these outthrows are large enough to be removed in the pulping and coarse screening loops. For a continuous pulping system, these rejects are primarily removed in the ragger and detrasher. There is also a portion of the outthrows that makes it through the openings in a pulper bedplate and can be removed from the HD cleaning and coarse screening systems.

In most stock preparation systems, the detrasher rejects and coarse screening rejects are combined and processed through a coarse reject press. The purpose of the coarse reject press is to compact the material and remove as much water as possible to achieve a high solids content in the discharge stream. Maintaining a high solids content is important for the press as it will directly reduce the amount spent on transportation of the material from the mill site.  

It wasn't that long ago that reaching a supplier such as KBC was "High tech" using a fax machine. I remember being on a project less than thirty years ago where the incoming fax machine in the construction trailers was loaded only with yellow paper. If you need a copy of a fax, you made a copy on white paper in the copier next to the fax. The yellow faxes went into a special tray for the project manager. You were in trouble if you had a yellow fax on your desk--that meant you circumvented the project manager.

Of course, cell phones came along about that time, too.

I started my career working for a small machinery manufacturer in the engineering department. In those days, all in and out phone calls came through a PBX (Private Branch Exchange) plug board operated by a human operator. One called in on the only phone number, the operator answered, and then sent the call to the person who was the recipient. For outbound calls, one called the operator, gave her the number and person you wanted to call, and then she reached them and rang you back when she had a connection. Of course, there was no voicemail.

We all know what we can do today...take out our phone, make a movie of the issue and then call our service tech directly. Life has changed.

By Jim Thompson, CEO

Talo Analytic

International &

Paperitalo Publications

jthompson@taii.com

The paper recycling industry and the initiatives guiding this industry have significantly evolved in recent years. According to Justine Reichman, founder and chief executive officer of NextGen Purpose, over the past 10 to 20 years, the paper-based recycling industry has evolved and most of that is due to both technological innovation and growing environmental awareness.

The European Union (EU) has long been at the forefront of environmental policy, with recycling serving as a cornerstone of its sustainability efforts.

The demand for sustainable solutions in packaging has never been higher, particularly in the food industry, where consumers are increasingly drawn to products that promise environmental responsibility. This trend has sparked a significant shift towards paper-based packaging, driven by both market forces and regulatory imperatives.

The organization says the industry “utilized its assets more effectively,” while containerboard capacity faced a third-straight decline.