New ways to save energy

By Steve Cole, Director Global Product Management - Xerium Technologies, US

BRUSSELS, Sept. 19, 2011 (RISI) - The primary uses of energy on a paper machine are in the water removal processes. In the forming section, 97% of the water is removed from the paper slurry through gravity, inertia, and vacuum. In the press section, another 2% is removed through a nip of nip rolls, vacuum, and press felts which impart sheet properties and strength. And even though the dryer section removes the least amount of water, it is the highest consumer of energy.

This paper will focus on the key products designed to reduce energy consumption and the actual case histories demonstrating the results each customer experienced using Xerium's innovative product portfolio, engineered to create financial value for customers, both in roll and paper machine clothing (PMC) products.

Figure 1 - Energy consumption on typical paper machine

Forming section: PMC technology

Here, the high energy consumption processes are vacuum systems and related pumps, and sectional electric drive systems that rotate the forming fabric which account for 77% of the total energy used.

Weavexx and Huyck.Wangner have recently developed and launched two product platforms designed to address energy consumption in the forming section.

EDC (Engineered Drainage Channel) is an innovative warp and weave concept that allows for more efficient drainage of the paper in the formation zone. This new structural concept provides enhanced drainage by providing a more open sheet side surface thereby enabling reduced drainage velocity. This controlled drainage velocity improves the efficiency of sheet formation during initial matt building process which leads to improved sheet characteristics and reduced wet-end vacuum requirements.

In addition to the unique EDC fabric structure, a new raw material technology, EnerSTAR, that significantly reduces friction in forming fabrics, has been introduced.

Figure 2 - Energy used in forming section

Forming case history #1

A European customer, producing LWC on a twin-wire former running 1,700 m/min, was not meeting sheet quality specifications and asked for Xerium's assistance in optimizing its forming section. After careful evaluation of the machine and fabric application, Huyck.Wangner applications engineers recommended a set of Finetexx forming fabrics incorporating EDC technology to improve sheet porosity on heavy weight grades. After startup of these new fabrics, not only did the customer experience a reduction in sheet porosity, but the combination of reduced refining, increased retention, and reduced sheet drying energy created $280,000 in annualized savings. Integrating Finetexx fabrics also allowed for a 2% increase in machine speed.

Figure 3 - Influencing the Drive Load (42%)

Forming case history #2

A European papermaker, producing SC-A at 1,200 m/min on a twin wire former, requested assistance with high drive loads and less-than-optimal fabric life due to premature wear. Huyck.Wangner application engineers recommended a set of advanced triple layer fabrics with EnerSTAR yarn technology to address the issue. As a result of incorporating the new fabric and yarn technology, the machine's drive load dropped by 10% and fabric life increased by 20% enabling fewer fabrics and shutdown cycles per year. With the benefits of EnerSTAR technology, the customer reported a savings of approximately $100,000.

Figure 4 - EDC drainage paths through forming fabric

Press section: PMC technology

Press clothing technology is a major influencing factor in the efficiency and energy consumption in the pressing process. Xerium has developed and introduced exclusive technology to specifically improve the effectiveness of dewatering and to improve sheet quality.

Figure 5 - EDC forming fabric structure

Case history #1

A North American customer was looking for help in reducing energy consumption on a tissue machine making 16 to 20 g/m² sheet at up to 1,900 m/min. Weavexx Application Engineers recommended the Huyspeed tissue felt. Huyspeed base fabric and batt technology is specifically designed to maximize pressure uniformity and dewatering, leading to improved dryness. Immediately upon startup, the customer reported a post pressure roll consistency improvement of 1.75%. This improvement translated to nearly $1 million in energy savings per year. In addition, since adopting Huyspeed as the standard technology on its tissue machine, the customer is setting production records.

To be continued ... Read Part II here.

Pulp & Paper International is FREE to qualified subscribers. Click here to find out more.