PPI Awards 2011: Honors well earned

w w w . r i s i . c o m - D e c e m b e r 2 0 1 1

By BRIAN DUFFY and BRAD BENZ

Nalco technology helped a linerboard mill improve strength and increase machine speed while reducing basis weight and steam use

ACHIEVING STRENGTH AND PRODUCTIVITY

In recent years, containerboard demand has been

rebounding in the worldwide economic recovery

and globalization of the market. Faster machine

speeds, increased operating rates, and the demand for

fiber to fulfill production capacity needs has been an

ongoing challenge to the industry. This demand has

caused fiber prices to escalate, especially recycled fiber

such as OCC from recovery processes. Many produc-

ers are implementing plans around fiber reduction

as it directly relates to manufacturing cost and selling

prices. Additionally, management teams are discussing

this every day in their plants. Having a well-managed

chemical program and a well-run mechanical opera-

tion is a highly important and effective way to sustain

the process of fiber reduction without compromising

strength such as ECT or compression strength.

Moving to lighter weights, strength, and energy

costs are critical drivers in the board and packaging

market. However, achieving the desired end-product

performance to satisfy demand while maintaining and

improving production efficiency can be a difficult task.

THE “L IGHT-WEIGHT ING” OF CONTAINERBOARD

The shift to lighter basis weights for containerboard

has been a compelling industry trend for the last

20 years. Since the adoption of Alternate Rule 41 in

1990, many users have opted for box compression

standards as the preferred method for specifying their

boxes. Several factors have significantly influenced

this shift, including advances in manufacturing tech-

nology, shifts in fiber supply, supply chain consider-

ations and sustainability awareness. Over time, basis

weights have also been steadily declining for key

linerboard grades, as illustrated in Table 1.

Achieving strength and reduced basis weight

targets can be a challenge for any papermaker,

especially when lower quality fibers are part of

the furnish mix. Use of Nalco’s patented METRIX®

technology program allows paperboard manufactur-

ers to increase strength, lower basis weight, enhance

production and improve sheet quality.

Variability in quality and supply of raw materials

also presents significant challenges to paperboard

manufacturers. Increasing refining to achieve

strength often leads to reduced drainage, lower

retention and higher energy costs. Increasing starch

dosages may also be ineffective as fibers become

saturated and additional starch cannot be retained.

Overuse of other cationic additives such as alum

and coagulants may also cause the furnish to become

cationically dispersed, affecting retention, sizing, system

Pulp & Paper International (PPI) D e c e m b e r 2 0 1 1

Table 1 - BASIS WEIGHTS FOR KEY LINERBOARD GRADES (SOURCE: RISI INTERNATIONAL, 2007)

foam, and finished product quality. Nalco developed

the multi-component METRIX retention, drainage, and

pressability program to allow board manufacturers to

simultaneously optimize basis weight, strength, caliper

and sheet smoothness. For example, the METRIX tech-

nology program provides papermakers with the flexibil-

ity to increase strength, while at the same time reducing

basis weight, increasing machine speed, improving

sheet properties and lowering fiber and energy costs.

Over the past 10 years, Nalco has committed signifi-

cant time and research investment into the continued

development of METRIX technology. Currently, the 7th

generation of this technology is being marketed, and

the 8th generation will be available globally in late 2012.

CASE STUDY EXAMPLE

Mill OverviewGrade: Linerboard

Basis weight produced: 35 and 42#/1000ft2 (170 and

205 g/m2)

Machine type: Single ply fourdrinier

Press type: 1st Straight through, 2nd LNP

Production rate: 45 tons/hr

Machine speed: 1,700-2,250 ft/min (518-686 m/min)

Furnish: 65% OCC and 35% kraft

Wet-end chemistry: CAT PAM flocculant, thin & thick

stock starch, rosin size & alum

pH: Acid

A linerboard manufacturer capable of produc-

ing 1,200 tons/day (1,091 tonnes/day) realized

serial reductions in production. Most days averaged

1,030 tons (938 tonnes) which was due to a need for

higher basis weight to meet quality specifications.

Low production was most prevalent on 35# (170 g/

m2) high performance linerboard and 42# (205 g/m2)

linerboard. This integrated board mill was using a

higher percentage of recycle fiber in comparison with

unbleached kraft pulp, 65% and 35% respectively. Re-

cycled fiber quality had also suffered over the years.

The thick stock Canadian standard freeness of

recycled fiber had declined by 100 mL or greater from

the facility’s recycle plant. Lower freeness was making it

increasingly difficult to achieve sheet quality parameters

at nominal basis weight and target speed/produc-

D e c e m b e r 2 0 1 1 Pulp & Paper International (PPI)

chemicals

Fig. 1 - METRIX TECHNOLOGY RESULTS – 35# HIGH PERFORMANCE LINERBOARD

Pulp & Paper International (PPI) D e c e m b e r 2 0 1 1

tion. On occasion, the paper machine in question was

running at target speed, but rarely longer than one day.

Several mechanical changes (refining, fourdrinier set-

up, pressing, drying) contributed to minimal improve-

ments in strength and speed. In addition, several wet

end chemical trials (coagulant, flocculant, starch, silica,

strength resin) achieved minimal to moderate benefit

in quality parameters. To meet quality goals, the mill

was forced to run 2-3 lb (0.9-1.4 kg) over standard basis

weight on select grades for this paper machine. This

manufacturer sold finished board on a manufactured

square foot/meter basis. Therefore, running over target

created several drawbacks which included increased

fiber cost, slower machine speed, decreased produc-

tion rates, and higher energy and unit cost per ton of

linerboard produced.

The manufacturer wanted to run the machine

at nominal basis weight or below while maintaining

strength targets in ring crush and mullen. In addition,

other key business drivers were increased production

rates and reduced operating costs. Nalco understood

that meeting these goals could prove difficult given the

present and past operating conditions on the paper

machine and that minimal impacts had been realized

with previous changes.

Nalco’s Industry Technical Consultants in coop-

eration with its on-site team performed a thorough

mechanical, operational and chemical (MOC) audit.

The team provided several recommendations in each

area with a major focus on chemistry. From a chemis-

try standpoint, there was a need to address drainage

on the fourdrinier without disrupting sheet forma-

tion. This particular machine has a very long forming

section. The wet end chemistry and their injection

point was not overly complex with the use of alum,

starch, rosin size and cationic flocculant.

A review of audit findings was communicated

to the manufacturer and a plan was proposed to

improve machine speed and increase strength.

Chemical recommendations were made to limit early

fourdrinier drainage, focusing on vacuum drainage

and pressing, as well as strength development.

PROGRAM DES IGN

As a first step, a high molecular weight cationic floc-

chemicals

Fig. 2 - METRIX TECHNOLOGY RESULTS – 42# LINERBOARD

culant along with colloidal silica and a balance of thin

versus thick stock starch provided necessary drainage

on the fourdrinier. The ability to move the dry line on

the fourdrinier was evident.

However, this particular chemical program did

not result in increased machine speed or strength.

Several parameters were adjusted on the fourdrinier

and press section to take advantage of the drainage,

but no adjustment provided sustained results. This

was not a major setback as pre-trial audit findings

suggested this was possibly due to water handling

in the press section. The initial chemical program

provided important technical information and

demonstrated that the Nalco team had the ability to

understand the papermaking process dynamics and

provide a technical reason for the paper machine

response observed as well as propose a solution.

The next step focused on a two-component poly-

mer approach using a high molecular weight cationic

flocculant in combination with a METRIX technol-

ogy product. The technology was selected for this

customer due to proven effectiveness with similar

furnishes and also due to the inability of a traditional

retention and drainage program to meet the mill’s key

business drivers.

In addition, METRIX technology provides addi-

tional strength to allow for reduction in basis weight

and refining. Experience with the technology, along

with a thorough understanding of the papermaking

process at this manufacturer’s facility, allowed Nalco

to design a program that would provide maximum

environmental and financial savings at the lowest

sustainable cost. This program integration provides

the customer an Environmental Return on Invest-

ment (eROI), delivering both environmental perfor-

mance and financial payback.

In designing the feed strategy of step two, existing

wet end additives were considered as well as their

respective location to each unit operation. A feed

location was selected that provided maximum reten-

tion with minimal interference from disruptive fines

and colloidal material. The strategy incorporated a

co-mix approach with high molecular weight cationic

flocculant and METRIX technology. At this facility an

overfeed situation occurred at 3.0 lb/ton (1.36 kg/ton)

of METRIX technology; therefore, the team selected

2.0 lb/ton (0.91 kg/ton) as the final dosage.

PROGRAM RESULTS

Analysis was completed on 35# and 42# grades,

running the paper machine at maximum steam

consumption/speed optimization.

• 4-5%basisweightreduction

• 7-10%manufacturedsquarefootageincrease

• 7-10%reelspeedincrease

• 1.5-2tonperhourproductionincrease

• 6%reductioninrefiningenergyperunittonon42#

(205 g/m2), no change on 35# (170 g/m2)

• Maintainedtargetringcrushandmullen

• OptimumMETRIXtechnologydosage–2to2.5lb/

ton (0.91 to 1.13 kg/ton)

• Minimaldosagechangesforexistingwetend

chemistry

• CustomerROI:$750/operatinghour

• Saved 90,000 gallons/yr in flocculant makedown water

The METRIX Technology response prior to a

speed and basis weight change showed a 14% reduc-

tion in steam consumption and a 10% increase in

both ring crush and mullen, grade dependent.

CONCLUS ION

METRIX technology is a synergistic, multi-compo-

nent program developed to enhance productivity,

press section dewatering and strength development

for paperboard manufacturers. It encompasses the

use of a reactive polymer and one of Nalco’s advanced

retention and drainage programs. Program benefits

are designed to include increased sheet strength and

machine speed from enhanced dewatering during

pressing and drying operations. PPI

Brian Duffy is Senior Industry Development Manager,

Board & Packaging Grades, and Brad Benz, Senior

Industry Technical Consultant, Nalco Company

Literature

1. The Future of Lightweight Containerboard in North

America, RISI International, 2007

2. Corrugated Today Magazine, July/August 2011

chemicals

To read more articles on Chemicals, visit our Chemicals Technology Channel at www.risi.com/technologychannels/chemicals

R e p r i n t e d w i t h p e r m i s s i o n f ro m P u l p & P a p e r I n t e r n a t i o n a l © D e c e m b e r 2 0 1 1

Nalco – Your partner for sustainable growth

Cost reduction is a key business driver for every papermaker.

Nalco solutions are specially designed to deliver cost improvement, while reducing environmental impact.

Water usage◆ System closure◆ Shower optimization◆ Additive dilution◆ Water management

Nalco’s key solutionsPARETO mixing technologyNAL-TEX® advanced cleaning 3D TRASAR® technology for cooling and boiler waterVELOX® press dewatering Integrated Water Management (IWM)

Energy savings◆ Felt performance◆ Press dewatering◆Boilerefficiency

Water reuseGRADE: uncoated fine paperAPPLICATION: PARETO ◆ increased production by

reducing wet-end breaks◆ reduced fresh water

usage: 105,000 m3/year ◆ estimated annual

savings: US$3,400,000

Steam savingsGRADE: coated fine paperAPPLICATION: VELOX◆ increased machine speed

from 1,150 to 1,200 m/min◆ estimated annual

savings: US$1,500,000

Water & energy savingsGRADE: boardAPPLICATION: 3D TRASAR technology◆ real-time monitoring

and control◆ reduced acid cleaning

frequency by 50%◆ eliminated unscheduled

shutdown◆ estimated annual savings:

US$30,000

Waste water recycleGRADE: gypsum linerAPPLICATION: Waste Water Treatment◆ improved end product quality

by eliminating chlorine ions from waste stream

◆ enabled 16,000 m3 per day of waste water to be recycled to papermaking process

Value delivered

Nalco is your partner in achieving your economic, environmental and social goals.Nalco Company1601 WestDiehlRoad•Naperville,Illinois60563-1198•USA•6303051000Latin America: Av.dasNaçõesUnidas17.891•6°Andar04795-100•SãoPaulo•SP•Brazil•551156446500Europe: A-One Business Center•Z.A.LaPièce1•Routedel’Etraz•1180-Rolle•Switzerland•41(0)216146400Asia Pacific: 2InternationalBusinessPark•#02-20TheStrategyTower2•Singapore609930•6565056868

www.nalco.com/paper

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