It’s a typical story after twenty years or so. Paper machine quality control systems from the 1980s must be replaced because they are technically obsolete. The critical issue is that spare parts supplies are drying up and finding the experts to repair them is getting increasingly difficult. Many have retired. The costs of service are climbing and system failures are beginning to affect machine productivity and paper quality. Simply put, it’s time to change or face the consequences.

However, if an immediate leap in product quality or efficiency can be achieved at the same time, a QCS system replacement can be a win-win situation for a paper mill. A liability is removed and a more valuable process quality management asset replaces it. After all, there have been major advancements in QCS sensing and control technology over the past ten or twenty years. Added together the service cost savings, improved customer satisfaction and waste reduction and you have a good return on investment.

Nordic Paper in Säffle, Sweden has gained such a quality boost, and solved the service cost problems as well, as an aging 1980s-vintage QCS system on PM2 has been replaced by Metso’s PaperIQ Select system. The mill is now producing more consistent product quality with less in-mill waste and satisfied customers. The mill produces 30,000 tonnes per year of greaseproof paper with the totally chlorine free (TCF) fiber furnish supplied by an on-site sulfite pulp mill. Nordic papers have a wide range of end uses due to their resistance to oils, water, atmosphere and heat, creating a protective barrier for foods, cookware and food preparation surfaces. The papers find end uses as baking parchment papers, baking cups, food packaging, take-out food wrapping papers, and some specialty laminating and release papers.

Service cost driven, quality focused

The obsolete system on PM2 was replaced with a new PaperIQ Select system in October 2009. PaperIQ Select is Metso’s most recent offering. As reported by Jakob Isaksson, Automation Engineer for Metso Mill Services, solving the service problems of the old QCS was a primary driving factor behind the investment. Problems with dwindling supplies of spares, lack of service expertise and reliability-related machine downtime had to be solved. Metso Mill Services looks after all maintenance in the mill. Of course, modern QCS systems like PaperIQ Select are more service friendly than previous generations, with extensive predictive maintenance diagnostics and quick-change module replacement procedures. This lowers the long-term costs of ownership.

In addition to alleviating the escalating service costs, the mill staff was focused on how a modern QCS could help them to make more consistent quality for their own on-site baking paper sheeting line and for the converting lines of external customers. White greaseproof baking paper and baking cup papers for muffins and cakes are the major products produced on this 4.2 meter width machine which has a design speed of 250 m/min. The grammage varies from 38 to 75 gsm.

Uniformly low air permeability is one of the primary quality specs of this heavily refined sheet, as it indicates good barrier resistance to fat and moisture penetration. Good formation and consistent moisture are key requirements, as is uniform crossdirection caliper. Mattias Wigelius, PM2 Production Manager, says. “Even profiles are very important for our converting processes and those of our customers. We produce some small rolls (1 meter width) and the converting lines are slowed down if the profiles across the roll width are not so good. Roll hardness differences cause wrinkles and there can be problems with the forming of baking cups.”

After evaluating competitive offers, the mill decided on the Metso PaperIQ Select system. A previous generation Metso PaperIQ Plus system with automatic color control was installed on PM3 in 2007, and that good internal mill reference helped to make the repeat order for PM2 decision clear and logical.

The system on PM2 comprises a scanner at the reel with grammage, moisture and caliper measurements and a single-sided scanning moisture measurement before the size press, where the moisture level is controlled between 6 to 7%. The PM2 system also includes a new Metso formation sensor, called IQFormation, which was installed on the reel scanner in March 2010. The development of this image capture and analysis capability was a significant advantage for Nordic Paper as formation is a key quality of their products, many of which are used for wrapping food.

Machine direction grammage and moisture controls are coordinated with the system’s IQwetendMD model predictive controller. The system manages the cascade control of nine steam sections in the main and after dryer sections. Cross-direction caliper control was re-implemented in the new system by interfacing to an existing induction profiler on the machine calender.

Better working effectiveness

One of the major goals of the project was to streamline and integrate the operator interface so the operators would have a much better view of the entire operation and would therefore control it better. Typical of older QCS systems, the operator interface and control operation was not consolidated in one place. The video interface station showed quality profiles, but the system’s supervisory control functions were distributed to panel controllers. This scattered and awkward operating method was resolved by removing the panel controllers and consolidating all measurements and controls in a unified DNAUse operator interface. Operators can now see cause and effect relationships for the paper quality and machine controls and their time trends. The more compact system also freed up much more space in the control room.

Wigelius says the better process overview has made a positive contribution to the operators working effectiveness. Profile resolution is better, so operators are more conscious of optimizing the sheet uniformity. “The operators see more and spend more time cleaning fabrics. It’s had a noticeable affect on quality,” he adds. Grammage changes are faster, as well.

60% less sheeting waste; customers notice

L to R: Mr. Jakob Isaksson, Mr. Mattias Wigelius & Mr. Mats Nording, Production Supervisor

The uniformity of the caliper profile has had the most significant impact on paper reel quality and how it converts into sheets. Wigelius states, “After the change of the system our sheeting department reports the waste for hard or loose edges totally disappeared and the reels are also much smoother than before. All this is due to the improved control with the new Metso system. The waste is down by 60% – about 6 tons per month less waste. Of course, our other (external) customers notice and are aware of smoother and better reels.”

Although the control of caliper is accomplished with the same number of profiler actuator zones, each control “cell” has much more information about the CD profile since sensors are faster and more precise and the CD resolution has improved by leaps and bounds from the 1980s. The IQwebCD control algorithm takes full advantage of this improved resolution and helps to recover paper quality quickly after a break or other upset. The Metso IQWebCaliper sensor has a CD resolution of 10mm, so across a web width of 4.2 meters there are 420 points which can be used for control. The result is faster and more precise control as seen by Nordic Paper.

The PM2 system started up quickly with paper quality established without delay. The excellent quality has been maintained, according to Wigelius, “I know our quality is better than before, and that results in lower broke in the mill and fewer claims.”

* Mark Williamson is a Journalist Engineer specializing in Paper industry based in Thornhill, Ontario, Canada

Abstract

In India all leading newspaper publishers are printing their business & financial news mainly on imported pink newsprint. Financial Times has used the pink newsprint paper in 1893 in UK to distinguish it from other publications. A detailed R&D was carried out by Emami Paper Mills to develop pink newsprint from 100% recycled fiber and it was commercialized in April, 2009 and supplied to the leading newspaper publishers. A

system was developed to manufacture pink newsprint at PM3 & white newsprint at PM2 simultaneously by taking pulp from same de-inking plant. Emami Paper Mills is one of the largest manufactures of recycled fiber based newsprint and writing & printing paper in India, producing 400 TPD at Balasore unit & 50 TPD at Gulmohar unit.

Development of Pink Newsprint

Experiment Undertaken

Detailed analysis of two imported pink newsprint samples (received from leading newspapers publisher) was done in R&D section. The color of the paper samples were measured as per TAPPI standard (Table No – 1) and shade of the imported pink newsprint paper sample no – 2 was approved as Emami is producing de-inked pulp having brightness 60-61% (ISO). Three leading indigenous dye suppliers were approached to supply suitable direct dye as per requirement. Several experiments were conducted to develop required shade. Out of three suppliers, one supplier with their technical expertise was able to supply suitable dyes to match required shade. Emami was able to get the required shade in laboratory by using orange & yellow dyes in proper ratio.

Outcomes

1. Emami was able to produce international quality pink newsprint from 100% de-inked pulp maintaining all the properties (Physical, Strength & Optical). However it is important to develop similar pink shade.

2. Consistent quality was maintained in terms of shade in the entire commercial run (Table No-2).

3. Strength properties are better than imported pink newsprint (Table No-3) and in case of color properties except L* value was almost nearer to imported pink newsprint paper, while a* & b* values are similar to the pink newsprint. However L* value is slightly lower as our base pulp is 100% de-inked pulp in comparison to 100% virgin pulp (thermo mechanical pulp) of imported pink newsprint .

We should not see ΔE as a whole, individual ΔL*, Δa* & Δb* are most important for matching the shade. ΔE is used for –

– How far off is a print proof from the original

– How effective is a particular profile for printing or proofing

ΔL* = difference in lightness / darkness value +

= lighter, – = darker ΔL* = L* sample – L* standard

Δa* = difference in red / green axis +

= redder, – = greener Δa* = a* sample – a* standard

Δb* = difference in yellow / blue axis +

= yellower, – = bluer Δb* = b* sample – b* standard

ΔE* = total color difference value ΔE

= ΔL2 + Δa2 + Δb2

ΔE is not always reliable by itself. In the following example batch 1 is visually a good match to the standard. Batch 2 is not similar to batch 1, however they both have the same ΔE value. For Batch 2 all of the difference is in the “a” value (less green) and is visually unsuitable.

Standard Batch 1 ΔE* = (0.57)2 + (0.57)2 + (0.57)2 = 1

Batch 2 ΔE* = (0.0)2 + (1.0)2 + (0.0)2 = 1

1. Modern De-inking plant equipped with latest technology & automation for producing base pulp of 60-61% (ISO) brightness. De-inking plant installed at Emami includes high consistency pulping, high density centri-cleaning, combiscreening, heavy weight centri-cleaning, pre-flotation, fine screening, dispersing system, oxidative bleaching, post flotation, reductive bleaching systems. The stickies and dirt specks removal efficiencies are 98 % and 96 % respectively.

2. Paper Machine with latest technological advanced equipments & QCS system

• Special Features in PM3:

•  Wire Section: Bel-BaieIV Horizontal Gap former designed to dewater from both side of paper web resulting in minimal, two sidedness, good formation and tensile ratio.

•  Press Section: The press is having Nipco Roll in I & III Nip and Center Roll is ceramic coated for better sheet release.

•  Calender Section: Two stack softnip calender.

•  Entire Plant is being operated through D.C.S.

•  QCS System

•  QCS System: To sense & control machine direction GSM, moisture & ash, along with cross direction dry weight, moisture and caliper.

•  Head Box: Equipped with cross direction dry weight control for better quality final product.

•  Press Section: Equipped with steam profiler (Devronizer) on suction roll to control cross direction moisture profile.

•  Calender Section: Heated roll is equipped with Cal Coil for cross direction caliper profile.

• Proper planning is done during change over from white to pink & pink to white with minimum down time.

3. Water Circuit

It plays a major role in the quality of pink newsprint. During the first pink newsprint run, part of PM3, disc filter filtrate was used only for diluting final tower pulp going to PM3. Excess water was getting drained causing fiber losses which reduces yield. During pink run in PM3 fresh water was utilized for PM2 pulp supply dilution. Gradually by improving the dye quality, optimizing the dye consumption, and minding the water circuit we were able to utilize complete back water of PM3 in de-inking plant & for dilution of pulp going to both paper machines without affecting paper quality of PM2 producing white newsprint. It improved yield by eliminating fresh water consumption even in pink run.

4. Superior quality dyes along with preparation & dosing system

Tailor made dyes were developed with a mixture of powder direct dyes having very good light fastness & bleed fastness. The exhaustion and substantively is also good resulting clear back water.

• Measure taken at supplier end to have consistent supplies

All the basic components of dyes were tested and after approval from QA, the batch was charged by the dye manufacturer. The final product was also evaluated by making paper sheet against standard sample for L*, a*, b* values, based on which the batch was passed. Thus the quality of each and every consignment was assured before dispatching. The consistent values were reflected L*, a*, b* in final product, and in all the pink paper production run.

• Measures taken at Emami for consistent quality

Each consignment of dye was tested for L*, a*, b* values & also compared with the previous consignment in the R&D section before issuing to process. Dye was dissolved in hot water in a dye preparation tank maintaining temperature from 850 to 900C. Temperature of dye storage tank was also maintained from 850 to 900C for better dissolution of undissolved particles. Various sizes of mesh were provided at different points before dosing the dye for eliminating undissolved dye particles & foreign material.

5. Spectrophotometer for Color Measurement

Color is often discussed in terms of shade. Shades are described on the basis of 3 primary colors red, blue & green (though the set of red, yellow & blue is popular among artists). In the paper industry the CIE L*, a*, b* scale has been widely adopted and provides an easily understanding system for specifying how one sample differ in color from another. The L* value represents the mathematical approximation of the black & white response of the eye. A perfect white has an L value of 100, while black has an L value zero. A plus value of a* indicates redness & a minus value greenness. A plus value of b* indicates yellowness and a minus value, blueness. In the L*, a*, b* color system, the total color difference between standard & sample can be computed with the equation i.e. ΔE = ΔL2 + Δa2 + Δb2. The goal in color matching is to reduce ΔE in the figure to the point where the sample & the standard appear to be the same color to a human observer. The spectrophotometer is the basic instrument (confirms to the direction in ISO 2469) for measuring color, brightness & opacity of paper).

Conclusion

• Imported pink newsprint paper is replaced by Emami’s pink newsprint paper.

• ΔE is maintained below 0.4 in different commercial run except in the trial run (0.9) & ΔL, Δa & Δb are being maintained minimum for correct & consistent color shade.

• Emami standard pink newsprint is comparable with imported pink newsprint manufactured from virgin pulp (thermo mechanical pulp) in terms of shade with better strength properties

PM5 base paper machine

The capacity of the line since the relocation has been increased to 200,000 tonnes/year. The design speed of the 4.55 metre wire width machine is now 1,100 m/min compared to an 800 m/min operating speed in Canada. Chenming purchased new drives for the paper machine, the off-machine coater and the supercalender. The basis weight of the art paper produced on the PM5 lines ranges from 60 to 120 g/m2 (coated we i g h t ) . The end-use applications include inserts and covers for books & magazines.

The startup of the line was scheduled for mid-2008 and, to the credit of Metso’s and the customer’s project team, that’s exactly what happened. Mr. Yin Jianhua, Vice Factory Manager, reports the first reel of paper was produced only 10 hours after the paper machine startup was commenced on July 28, 2008. He credits the excellent commissioning to the professional efforts of Metso and Chenming engineers alike. After producing uncoated paper for a month, the off-machine coater and the supercalender started production on August 28.

MUTUAL PROJECT EXPERIENCE

The order for the automation project was based to a large extent on the longlasting and trusting relationship developed between the Chenming Group and Metso. That relationship started in 1997 when PM1 was commissioned. Most recently, Metso provided the quality control, process control and machine control system as well as the runnability and condition monitoring system for Shandong Chenming’s PM4, located nearby. The Metso-supplied PM4, with a capacity of 480,000 tpy, is the world’s largest newsprint line.

Mr. Bian Wanliang, Assistant General Manager, says.” We have known Metso for a long time, we know their capabilities very clearly, and we have worked well with them in previous projects.” He says that project management has been and remains a strong point for Metso.

Familiarity with Metso machine controls was also a positive factor. Mr. Yin says that process operators transferred from other Chenming machines already knew how to work with the Metso interlock logic and machinery control help functions. That familiarity would certainly help during the PM5 line startup. Moreover, properly interlocked machine controls are essential for safe operation.

The PM5 production line comprises a base paper machine originally supplied by Valmet, a re-reeler, jumbo reel transport carts, an off-machine coater, a supercalender, a single- drum winder, and a two-drum winder – all from different OEM suppliers. The automation scope of supply includes replacement of previous PLC-based machine controls for all the line’s stages except the winders. The machine controls and paper quality controls were consolidated in the metso DNA CR platform.

The automation project also included a complete set of electrical, pneumatic and hydraulic field devices with related engineering. Metso made an extensive pre-delivery study with old documents to define the required scope of supply. To ensure a good line startup, Metso included mechanical installation supervision and process startup support in the automation package and commissioning scope.

All CD and MD quality controls and two new PaperIQ Plus paper quality scanners on the paper machine were also included. A new IQSteamPro moisture profiler was installed in the paper machine press section. Metso supplied new paper making equipment for PM5 including a ValSizer, a TurnDry air dryer after the size press, new and converted UnoRolls, PressRun blow boxes, a new press section solid roll and double doctor, SymRun blow boxes, and UnoRun ventilators. Additionally, a new top wire former was added.

UNKNOWN CHALLENGES, SOME RISKS

The re-commissioning of old, dismantled papermaking equipment is quite different and much more challenging than starting a brand new line which is precisely specified and made to order. With an old line there are a lot of unknown challenges and some risks to be managed. Mr. Yin says that combining automation, mechanical and process knowledge was a key ingredient for a good startup of the new line. He says that there is a very short, select list of companies in the world that can bring together the knowledge required for combining process and machine controls. Metso is one of them, he adds.

Faced with moving a complete line from another continent Mr. Bian says that Chenming needed a total solution. “The scope whole project had to be very carefully planned. We needed to know what to keep, what to replace, and what to renew,” he says. For instance, the change in motor voltages from 460 VAC, 60Hz in Canada to 380 VAC, 50Hz in China had to be addressed. The conversion from English to Metric units was another challenge.

GIANT JIG-SAW PUZZLE

The magnitude and complexity of the task ahead was brought into focus when the first site survey was made at the Domtar mill in early 2007. The agreement to purchase the mill equipment was concluded in November 2006. When engineers arrived, the paper machine had been disassembled and was laying in unconnected pieces like a large jig-saw puzzle. The off-machine coater and supercalender were still intact. After cataloguing, the machinery was shipped to Shouguang during 2007.

But a lot of work remained. Chenming engineers obtained original machinery drawings from Domtar and the OEM suppliers. Similarly, original machine control logic was acquired from the previous automation suppliers and machinery manufacturers. “It was a lot of detective work,” says Mr. Bian.

COMPATIBILITY AND INTERFACE ISSUES

Despite the documentation of the machinery beforehand, good on-site engineering and innovation was essential for an on-time startup. The list of compatibility and interface issues was long. For instance, there were initial problems to control the off-machine coater’s stepping cylinders. After opening up and analyzing the mechanical construction the control strategy was designed to match. Hydraulic control units were rebuilt and new field components were installed. The calender roll heating system was reengineered as well.

All flexible hoses had to be checked for compatibility and fittings were changed to convert from English to Metric sizing. because of the difference in motor electrical standards Chenming purchased a special MCC system for motor controls. The list of compatibility issues goes on. Nevertheless, the process of on-site engineering was accomplished successfully through a lot of diligence, leg-work and good communications between Metso and Chenming engineers.

RISING TO THE TASK

When implementing machinery controls for this Chenming PM5 project and other projects Metso’s automation engineers have faced challenges which are quite different from normal papermaking process controls and quality controls. The proper and effective engineering of machine controls requires detailed knowledge of paper machinery. Faced with disassembled machine components and twenty-year-old drawings the required pneumatic, hydraulic and electrical field devices had to be engineered and selected properly and the machinery logic controls had to be figured out without a lot of ready-made documents from the customer.

In this respect, the Metso engineers rose to the task at hand. For instance, a flying splice is a very demanding task requiring the very precise timing which is available in metsoACN control I/O. With the aid of a data-logging simulator the required timing for the flying splice was defined with millisecond precision. The result on the machine was an almost instant success. On the second try the flying splice took hold.

RISK EFFECTIVELY MANAGED

With so many details to work out at the project site there were some risks involved. Jukka Hirvonen, Metso’s onsite automation project manager, explains how these risks were successfully managed: “In the beginning of the project the risks were realized, listed and analyzed. Also, all necessary plans and actions were made and the resources needed were reserved. All the machine information that the customer had collected was carried to Finland for basic engineering. We had regular project meetings with the customer where the open or unknown issues were discussed. Site surveys were an extremely important part of the project work, so all unclear issues were checked. This was really a lot of work and the key issue of the project realization,” he says.

After the PM5 line startup and previous Chenming machine startups Mr. Yin Jianhua sums up his experiences: “Based on our experiences Metso is very strong in process automation and on the mechanical side as well. We have confidence in their capabilities, “he says.

Process used earlier:

Till late 2003, Abhishek Industries Ltd was using legacy computer applications, mainly developed using PB / FoxPro / VB and other heterogeneous programming languages.

Issues In front:

Constantly changing demand, increased market competition, higher cost of raw materials, equipments, transportation, maintaining margins and profitability are just a few challenges one faces in a business scenario.

Way outs:

In response to these challenges of global competitiveness in Business they had formulated a strategic plan to leverage IT to improve the operational efficiencies and decision support systems in five major areas, viz. Supply Chain, Financial Management, Customer Services, Manufacturing Processes and Human Resources Management.

To align with this strategy, numerous modules of SAP have been implemented successfully like mySAP ERP has generated many tangible and non-tangible benefits, which have been realized during the last three years:

• Materials Management (MM), Sales

• Distribution (SD)

• Production Planning (PP) /APO

• Finance and Costing (FI&CO)

• Funds Management (FM)

• Plant Maintenance (PM)

• Quality Maintenance (QM)

• BW/ SEM

• Human Resource (HR)

” The implementation of ERP solutions in Trident Paper has created a positive impact on the business revenue by enlarging the customer base, increasing customer satisfaction and forming best alignment between business infrastructure and IT solutions. It has created synergy among team members to realize the best value proposition in a globally competitive scenario with more focus on business processes”, says Mr. Rajinder Gupta, CEO, Trident Group.

Tangible Benefits:

• Business revenue increase of more than 100 % handled with basically the same non manufacturing infrastructure due to SAP implementation

• Reduction in WIP (work in progress)

• Reduction in typical Production Cycle time

• Delivery performance improvement from OTIF (On Time Delivery in Full)

• Integration with Process control system has resulted in elimination of duplicate work and improved accuracy.

• Reduction in bill of materials failure due to better control on waste.

• Automated workflows in the areas of approvals & authorizations have tremendous impact on the overall efficiency of the organization. A conservative 5% improvement has been estimated.

Intangible Benefits:

• Inbound & outbound logistics has improved significantly

• Decision support system has created agility among managers to take decisions in time

• Helps is setting up new benchmark and monitors KPI (Key performance indicators)

• Availability of information to all stakeholders/Employees

• Functional coordination and transparency of on-going activities

• Over all Business continuity in terms of plant uptime has improved

• Faster Customer service and fulfillment

• Efficiency of its post-sales operations, reducing the amount of time needed to process customer claims and product returns

• Improves productivity management and workforce optimization by offering online training options.

” For the success product quality alone isn’t enough. It takes differtiating your business from the rest in how you make and move your product. And that requires improvements in the supply chain efficiencies improvements that will ensure company’s ability to thrive by adapting to changing demands, enhancing service, and lowering costs”, says Mr. Rajinder Gupta, Chief Executive, Paper Division. ” In Trident Paper, SAP has made all the procurement work standardized and process oriented. mySAP SCM has transformed our supply chain into a responsive, adaptive network that is being instrumental in driving our business towards the ultimate goal of improved service, reduced costs, and increased profitability”, he adds.

Below mentioned are some of the features of SAP which ABIL has utilized optimally which has resulted into higher benefits

Vendor management: This has provided a platform where all the concerned commercial staff can request for the Vendor along with the concerned details and attachments (ITR, PAN, Balance sheet etc) which is approved from all the concerned authorities before the creation of a vendor code. This helps in making lean database of the vendors along with the required details.

Vendor categorization: In system it’s a management’s tool for rationalizing the vendors and converting performing vendors into Strategic partners which has resulted in reducing vendor base and involving vendors in the business. Hence this has enabled overall risk mitigation, reduced inventories, and procurement cost reduction.

Vendor evaluation: It proves to be a management’s tool to ensure timely deliveries, best quality products and bulk purchases at lowest prices.

SAP also provides a platform to do the consumption based planning where requisitions for the materials are generated keeping into consideration current stock levels, safety stock, planning and procurement lead time. Whenever stock of material (which is configured according to consumption based planning) falls below re-ordering point (which is calculated based on above mentioned parameters) then system automatically generates an indent for the same.

SAP also handles Vendor managed inventory which is maintained by the vendor at Trident’s location and material is consumed as and when it is required. Vendor is paid for the consumed material

Benefits Derived:

• Better communication and reporting

• SMS for goods receipt, expected deliveries.

• Auto mailers to vendor at the time of RFQ (Request for quotation) creation and Purchase Order/ Scheduling agreement release

• Daily auto mails about the Consumables, WIP and FG aging.

• Vendor overdue reports, Mat rejection mails etc

• Shift from procurement patterns of group level to single SKU (Stock keeping units) level

• Price histories

Trident group is a Rs. 25 billion conglomerate having interests in Paper, Textiles, Energy and IT. It has been conferred with the SAP Award for Customer excellence in the year 2007.

A conventional Tissue paper plant, featuring a Crescent Former Tissue machine (designed with two virgin fibre stock preparation lines with two refiners, approach flow with two layer headbox, single press solution, duo-system gas hood etc.), the total energy consumption can be broadly divided as follows:

• total electric power consumption:- 900-1000 kWh/ton;

• total gas consumption in the hood:- 1100 kWh/ton;

• total gas consumption for generating steam to Yankee:- 800 kWh/ton.

The “average” consumption of a tissue plant is therefore around 2.8-2.9 MWh/ton. If one considers a plant using recycled paper as raw material, the energy consumption further increases. A great amount (more than 2/3 of the total consumption) of energy is used for drying the tissue. Obviously, distribution of this thermal energy depends on the balance between the hood and the Yankee in the mill. Considering, the last few years, an average increase in the cost of energy in the World has been 25% for electricity and 50% for gas, hence in conventional mills, the target will be focused on the lower values of overall energy consumption and drying process in particular.

2. Thermal energy used in the tissue process

To define the necessary thermal energy required for paper drying, one can refer to Tappi formula TIP 0404-05 which is as follows:

R_w = B x S x W x [ L - 1]
E
R_w = Rw_hood +Rw_YD

• = total evaporation [ Kg /sec ] determined by the drying balance between hood and Yankee;

• B=basis weight at the reel [ g /m² ];

• S=machine speed [ m/sec ];

• W=paper width [m];

• L=dryness at the hood outlet [%];

• E=dryness at the hood inlet [%].

If we consider the terms B, S,Wand L as constants, linked to technological and production parameters, the total load for evaporation is therefore tied to the value of dryness at the hood inlet ‘E’ determined by the press action. The greater the value, the lesser will be the total evaporation value and therefore the “work” to be done by the hood and the Yankee. In a “conventional” installation, a two press solution, which guarantees dryness at the hood inlet of approximately 42% and is advantageous in terms of thermal energy saving, compared to a single press solution, which guarantee an average value of 38% only. This has an impact on tissue quality and increases electric power consumption.

Furthermore, considering both drying supplies at hood and Yankee, it can be said that the Yankee “system” is, more efficient than the hood in terms of energy. There is an interesting solution which allows considerable energy saving. This technology is the combination of a large diameter press (TT SPR 1430) with steel Yankee Dryer cylinder (TT SYD). The large diameter press, having the prospect of working with an “increased” nip, both in terms of width and linear pressure, is able to reach values of dryness at the hood inlet, comparable to those of a double press. Whereas the steel Yankee cylinder is able to supply a greater evaporation coefficient compared to a conventional cast iron cylinder, thus making the drying of paper more “efficient” and economical.

Opportunity for Yankee head insulation with possible increase in its efficiency, brings further energy saving. In the following paragraphs the two equipments are described as well as results obtained at some important installations by Toscotec Tissue Division are also explained.

2.1 Large diameter suction press roll (TT SPR 1430)

As previously mentioned, the concept of this press is to fit the growing need for tissue products with high thickness and softness, with energy saving demands. This new concept of suction press roll with diameter greater than 1400 mm, has the characteristics of generating a wider nip compared to a conventional press roll. The approximate value of this nip will increase by 30%. Maintaining the advantages of a traditional press roll, such as low maintenance cost, reduced investment cost and quick installation, the suction press roll allows an increase in paper softness and bulk, without having the added constraints involved in managing a shoe press. The large diameter suction press roll is designed to operate with a maximum nip load of 120 kN/m, instead of 90-95 kN/m typical of a conventional press roll, thus it is possible to choose between operating at full power for an “economic” product grade and at reduced pressure to enhance softness and thickness of a higher quality product. The increase in terms of percentage of dryness at press outlet with larger nip is at least 2-3% compared to a conventional press roll with consequent energy saving.

A further advantage is also obtained by application of double blade on the press roll, which limits “rewetting”. This advantage means an improved moisture profile and an increase in degree of dryness of at least 1%. It is important to underline the fact that, in terms of energy, a decrease of 1% of dryness at the press outlet could be translated into approx. 400kg H²O/h more to evaporate in the drying process (~55kg H²O/t of Paper) with consequent increase in specific consumption of thermal energy.

2.2 Steel Yankee Dryer cylinder (TT SYD)
Traditionally, Yankee cylinder has always represented a critical element in tissue machines. The combined action of Yankee and hood is responsible for drying the most part of tissue. Paper drying is an energy intensive process and the Yankee cylinder supplies a relevant contribution, thus any possible energy saving connected to it is of great interest to all Tissue manufacturers. In tissue production with conventional crescent former machines, after the paper is formed and transferred to the cylinder by the presses, the drying process is mainly constituted by a change in the state of water contained in paper. This change is carried out by heat transfer, as a result the steam condensation inside the Yankee and hot air blowing in the hood. Thanks to these two actions, the water trapped inside the fibre matrix passes from liquid to vapour state and is then extracted by the hood exhaust.

In past years some companies started building steel Yankee cylinders, however many limitations in terms of thermal stability, maintenance in working conditions as well as deficiencies in the manufacturing process limited its development and this product wasn’t introduced in the tissue sector.

The use of steel plates instead of cast iron fusion allows significant reduction in shell thickness and therefore resistance to heat transfer. The result is an increase in drying capacity achieved through steam condensation inside the Yankee, which is known to be the most efficient paper drying system and often the least expensive. The energy yield of a cylinder is further improved by the possibility of operating at higher steam pressures; the development of an efficient system of condensate extraction allows furthermore reduction in steam pressure differential necessary for proper evacuation of the cylinder. The CD moisture profile on the tissue is also optimized, thanks to a uniform and constant condensate removal and thermal exchange taking place in the cylinder.

On some reference Yankee installations, it was possible to verify that heat transfer coefficient and condensation capacity of the SYD cylinder, on an average, at least 30% higher, compared to a cast iron cylinder with the same dimensions and operating conditions. Considering that drying could be equally shared between hood and cylinder, the total drying capacity of a tissue machine equipped with Steel Yankee Dryer is higher by 10- 12% (see Fig. 3 and 4) compared to traditional design with a cast iron dryer. Alternatively the same productive capacity can be obtained by increasing the contribution of the cylinder with obvious benefits in terms of energy saved on the hood heating.

A further possible significant contribution to reduction of energy consumption is the prospect to insulate the cylinder heads. This enables saving of approximately 5% on steam consumption in the cylinder. In case of a rebuild or modification of a tissue machine, the steel Yankee also has another advantage, which is to have a larger covering on the grooved surface compared to a cast iron cylinder and is therefore able to dry wider paper with same cylinder size. Another advantage is to have a lesser weight of about 30%, compared to a cast iron solution, which reduces civil work in installation and the related costs. Thanks to the metal coating, the surface of the cylinder is homogenous in terms of roughness, it isn’t porous and its hardness is far superior to a cast iron cylinder. These factors contribute in increasing the creping process efficiency with obvious benefits in productivity of the paper machine and with consequent saving on the coating consumption, thanks to absence of porosity on the cylinder and to even distribution of the product on its surface.

At the same thermal conductivity in cast iron and steel, the shell thickness reduction means a drastic reduction in resistance to thermal exchange and therefore an increase of 30% of thermal transmission efficiency of the cylinder. This increases productivity and saves energy.

Plant Case Study

Listed below are a few interesting examples of the significant achievements resulting in huge energy savings, obtained with this technology from application of the steel Yankee cylinder and the large diameter press roll in actual Tissue plant conditions:

Case 1: Installation of a new Yankee cylinder TT SYD 12FT

• Reference data:

- Paper width at the reel: 2,75m

- Test reference pressure: 5 bar

- Conventional single press design

- Test basis weight reference: 16,5 g/m²

• Evaporation rate of a 12ft cast iron cylinder at 5 bar:~60 kgH₂O/hr-m²

• Evaporation rate of TT SYD at 5 bar:~ 80 kgH₂O/hr-m²

• Comparative increase in Yankee cylinder evaporation rate:~34%

• Comparative reduction in thermal energy consumption:~64kWh/ton

• Comparative reduction in thermal energy consumption at maximum working pressure: ~6,5%

Case 2: Rebuild of a cast iron cylinder with a TT SYD 12FT steel cylinder

• Reference data:

- Paper width at the reel: 3,7m

- Test reference pressure: 5 bar

- Double press design

- Test basis weight reference: 35 g/m²

• Evaporation rate of the former 12ft cast iron cylinder at 5 bar: ~68,5 kgH₂O/hr-m²

• Evaporation rate of new TT SYD at 5 bar:~94 kgH₂O/hr-m²

• Comparative increase in Yankee cylinder evaporation rate: ~37%

• Comparative reduction in thermal energy consumption: ~71kWh/ton

• Comparative reduction in thermal energy consumption at maximum working pressure: ~7,3%

Case 3: Installation of a Yankee cylinder TT SYD 15FT combined with a TT SPR 1430

The energy consumption of the drying section (hoods+Yankee cylinder) verified on a Toscotec machine installation in Germany and equipped with a TT SYD 15FT and large diameter press roll TT SPR 1430, reported values less than 1700 kWh/ton.

The following were the operative conditions and results:

• Reference data:

- Daily production: 97,3 tpd

- Paper width at reel: 2,68m

- Basis weight at reel: 19,8 g/m²

- Raw material: 100% virgin pulp

- Test reference pressure: 6 bar;

- Single press design: dia. 1430 mm;

- Yankee: steel dia. 15 ft (4572 mm);

- Linear nip load: 120 kN/m;

• Paper dryness at reel: 95%;

• Hood blowing temperatures: 470°C wet end; 470°C dry end;

• Measured steam consumption: 1,24 ton/ton~791 kWh/ton (considering boiler efficiency of 90%);

• Measured gas consumption: 88,3 Nm3 /ton ~ 883 kWh/ton (gas calorific value: 8600 Kcal/Nm3 );

• Total energy consumption gas + steam: 791 + 883 = 1674 kWh/ton

It is interesting to note that in case of using SYD combined with TT SPR 1430, energy consumption values reach closer to those with double press configuration, however maintaining all the quality features like softness of tissue etc.

Conclusions
Conventional technology for the production of tissue paper has shown that it continues to have strong validity and the energy consumption could be significantly reduced by the use of reliable tools. Toscotec’s long time experience in the optimization of the production process for tissue and paper industry, and in particular in the drying area, has highlighted the fact that energy saving is possible through smart and easy to run applications.

Metso Water Jet turn up system

In a recent upgrade, the Cartiere del Garda mill successfully replaced a conventional tape turn-up device with Metso’s WaterJet turn-up system. Cuts performed using WaterJet are clean and precise, which ensures an excellent base from the very first spool wrap. WaterJet has the ability to improve turn-up efficiencies and reduce bottom waste on all grades of paper.

The Cartiere del Garda mill is located in the middle of the famous tourist town of Riva del Garda in Italy. The mill houses two paper machines that produce 335,000 tpy of woodfree coated paper in a basis weight range of 90-350 g/m2. The paper produced by PM 3 is coated on a 4.1 m-wide off-machine coater (OMC) equipped with a conventional pope reel that dates from 1980.

Background

“We had two reasons to purchase a new turn-up system. Firstly, we suffered from bad turn-up efficiency of less than 90% at the reel. Secondly, our tape turn-up device marked the sensitive coated paper surface, causing excess bottom waste,” explains Antonio Di Blas, Production Director. “The continuous need for heavy maintenance was an additional negative aspect of the tape turn-up system.”

The WaterJet turn-up system seemed to be the right technology to get rid of these problems. “We examined the offering on the market before making a decision in favor of Metso. The simplicity and ease of use of the Metso system convinced us. Further, we appreciated the high technological competence of Metso’s people, who really understood the challenges set by the old reel.”

99% reliable reel change

At Cartiere del Garda, going from a tape device to the WaterJet system improved the turn-up efficiency remarkably. “The WaterJet system is working great. We are above 99% in turn-up efficiency now. It is really very difficult to fail a turn-up,” says Antonio Di Blas.

The mill’s other goal of reducing bottom waste has also been reached. “Before we lost 5 cm in bottom waste on each parent roll because of tape marking. But now it is only around 2.5 cm with the lower grammages and a bit more with the higher ones. The reason we still produce some bottom waste lies in the reel itself, which needs to be modernized. But this is another story…”

WaterJet success leads to repeat order

“We are extremely satisfied with Metso’s WaterJet turn-up system. It performs very well. Actually so well that we purchased a similar system for our PM 2 off-machine coater,” says Antonio Di Blas.

The whole team responsible for production agrees that Metso’s WaterJet turn-up system is extremely reliable. Shown from the left are: Antonio Di Blas, Matteo Marocchi, Vittorio D’Olif, Maurizio Ferraris and Stefano Betta.

Several centimeters of paper left on a parent reel spool is a common sight in many paper mills. These “left-on-spool” or “bottom waste” losses, which cannot be wound because of tension control problems and crepe wrinkles during the initial phases of reel building, may add up to several percent points of lost production. These chronic losses are common on older paper machines with imprecise pneumatic control of the loading, positioning, and coordination of the primary and secondary arms. But the Stora Enso mill in Kvarnsveden, Sweden encountered an acute problem when three of their newsprint machines started production of value-added grades containing fillers. In many cases, whole sets could not be wound because of density control problems in the first set near the spool.

To solve this problem, the mill installed three reel density optimization systems (ROS) provided by Vishay Nobel of Karlskoga, Sweden. Building on its expertise in hydraulic force and position control systems, ROS was developed in a Swedish mill in 1996. Since then, 22 systems have been installed.

The systems at the Kvarnsveden mill have solved the previous reel density control problems and have allowed the machines to produce jumbo reels with the right density profile from the spool up to their maximum diameter. The mill can now produce jumbo reels with a full complement of sets with a minimum of left-on-spool losses.

Losing whole sets

PM9 was the first to be equipped with ROS. PM9 was started up in 1956 as a standard newsprint machine. Kjell Sundin, Maintenance Technician, says that when the machine started producing improved newsprint with clay filler content up to 5%, the winding problems became very apparent. “The sheet was wrinkling and we were experiencing a lot of breaks in the winder,” he states. The problem was so severe that the machine jumbo reels were often limited to two sets of 125-mm diameter rolls instead of the normal three sets.

PM8 had similar problems producing well-built, full sized jumbos. The original newsprint 5.48-meter trim machine was started up in 1931 and rebuilt in 1983 when it was converted to SC production. The machine is designed to make 2.6- meter diameter 3-set jumbo reels for offline supercalending. But wrinkles and rope marks (caused by lateral paper wandering) caused similar winding problems and many breaks. “We could lose whole sets. And often we could make only two sets on the jumbo reel, “says Sundin.

The problems on these two lines resulted in a typical scenario seen in many mills. If the winders are having break problems and falling behind on their winding schedules, full parent reels build up in inventory until the reel spools run out. Then the paper machine has to be shut down. The whole line efficiency is affected.

To rectify these problems, the mill installed ROS systems on PM9 and PM8 in 2001 and 2002 respectively. Old pneumatic positioning and loading systems for primary and secondary arm control were replaced with hydraulic systems required for the precise position and force controls provided by the ROS system. The reel drums on PM8 and PM9 were carbide-coated at the same time to reduce paper slippage against the reel drum and to avoid the rope marking encountered on PM8.

The mill’s largest, newest (1998 startup) newsprint machine, the 8.68-meter trim width PM11, was also encountering similar winding problems when it started running filled grades. The machine is designed to produced 4-set jumbo reels, but the first sets were difficult to wind when filler was added to the furnish. Based on the success of the preceding two installations, a ROS was installed on PM11 in 2005.

Closed loop control

The old pneumatic pressure-controlled systems for the primary and secondary arms were based on open loop controls; there was no feedback measurement of the exact position of the cylinders nor was there any indication of nip pressure during the reel buildup. Friction and stickiness in the mechanical systems also caused imprecise control over the initial phases of reel building. Moreover, the all-important transfer from primary to secondary arms was not controlled precisely and sheet tension could change dramatically. Uneven nip loading and uncoordinated primary-to-secondary arm transfer often created irregular web tension, stressing the sheet and causing crepe wrinkles. Several centimeters of paper on the bottom set had to be discarded.

In contrast, Vishay Nobel’s ROS solution is based on precise feedback control of arm position, relief cylinder position, and nip loading during the primary and secondary arm phases. By using feedback measurements from load and position transducers, any mechanical friction, stickiness, or hysteresis is taken into account. In fact, the measurements are used to diagnose mechanical problems with the reel mechanics. With these measurements, time delays between hydraulic actuation commands and actual movements are measured and accommodated in the control strategy.

The hydraulic position and nip loading system operates in a closed-loop mode, providing even and repeatable nip loading against the reel drum, smooth primary arm lowering, and a bumpless web tension transition during the transfer from primary to secondary arms. The position and nip load are controlled on both the tending side and the drive side, ensuring parallel arm lowering and avoiding any skewing of the sheet tension. With the even tension provided by this system, the paper sheet is not subjected to changing stresses that might cause crepe wrinkles.

Force and position measurement

For primary arm control, force transducers are installed in the overhead reel spool hook, to measure its downward force, and in the relief cylinder underneath the reel spool to measure the pressure of the reel drum against the accumulating paper on the reel spool. To achieve an accurate measurement of nip pressure, these transducers are located as close to the spool as possible. Position transducers indicate the relief cylinder position and the angular location of the primary arms as they move downward. The position transducers are embedded in the cylinder to keep out papermaking dust and ensure reliability.

Before the reel turn-up, the relief cylinders start moving towards the spool. Once contact is made, the system changes to force control. As the winding of paper progresses, the ROS system automatically makes adjustments to the relief cylinder to compensate for the weight of the paper in the building reel. During the precisely controlled arm lowering period, the force of the paper on the reel drum is kept constant. In the lowered position, the system compensates for the force change when the hook is released.

The ROS system smoothly controls the movement of the secondary arms to achieve a bumpless transfer of sheet tension and nip force from the primary to secondary arms. The system then continues to control the nip force and the reel density with the secondary arms to the outside of the reel. The secondary arms are also equipped with force transducers (drive side and tending side) near the reel spool and positions transducers in the arm positioning cylinders.

The system builds the reel according to a target density profile. The paper thickness and density are calculated using the continuous readings of the reel drum rotation speed via a tachometer and the angular rotational speed of the reel spool via an optical or magnetic trigger sensor. The spool rotation speed changes as the reel builds up. To make this measurement, each reel spool is marked with an optical reference or a magnetic reference is embedded. The thickness and density are calculated by an equation that includes a basis weight factor. These measurements are updated after every three layers of paper.

High speed of response

To avoid uneven web tension, the speed of response of the ROS system measurements and controls is extremely important. Anders Olsson, Vishay Nobel’s Systems and Sales Engineer, notes that crepe wrinkles can occur if the web tension changes significantly within 100 milliseconds. Typically, the cycle times f o r force and position measurements are 2 to 5 milliseconds, providing the fast response time needed for responsive control.

Olsson reports that control can start very soon after the reel turn-up. Typically, the reel density is on control after 200 to 300 meters of paper have been wound. At 1500 m/min, that is only about 8 to 12 seconds of production time.

The real-time progress of the reel density optimization controls is shown to the operators on a control room video monitor. The reel density machine-direction profiles are selected from a recipe table according to the paper grade being run. The system also reports reel length and diameter so the operators can build the reel to the needed dimensions to suit the winders’ set production requirements.

Winding problems solved

Kjell Sundin reports that the bottom set winding problems were solved on all three machines after the installation of the ROS system. “On PM9, it was possible to make three good sets with filler levels ranging from 10 to 15%. We were not nervous about it,” he says. Previously, they could not produce three sets with filler levels at 5%. PM9 has since been shut down and the ROS is being re-installed on PM10.

On PM8, parent reels to the winder are run down to about 2 to 3 cm of paper left on the reel spool. According to Sundin, that is a minimum amount of waste, considering the start-up losses on the supercalenders. The winding problems with filled grades on PM 11 were similarly solved. The filled grades on PM11 have been discontinued. The ROS is still proving its worth on the lighter grades (40 g/m2), which were difficult to wind.

Excellent results on other newsprint machines

The Kvarnsveden mill solved the reeling density and winding problems related to value-added newsprint grades containing fillers. Producers of standard unfilled newsprint have also seen the benefits of more precise and repeatable reel density control. Recently, a newsprint mill equipped five newsprint machines with ROS systems. The bottom waste has been reduced significantly, adding to saleable production. At the same time, reel snap-off breaks have been reduced or eliminated and the consistency of winding density and wound roll sheet area yield has been improved. Reprinted with the permission of the original publisher, Pulp & Paper International magazine.

We always hear about the success stories of modern “world class” paper machines which have been built to produce massive volumes of paper for global markets. Without any doubt these machines set the standard for productivity, efficiency and quality.  That’s to be expected. But there is another important tier of papermaking capacity which serves local or specialized markets. Many of these mills have paper machines that have been built to the more modest specifications of previous decades – in many cases less than 4 meters width with correspond- ingly lower production rates. But lower capacity mills are faced with the same important issues common to all papermakers – keeping the costs low, the productivity high and the paper quality competitive. Productivity, cost and quality improvement projects on these smaller machines get less press coverage but they are nevertheless very important for the market success and profitability of the paper companies who run them.

Santa Maria Cia. de Papel e Celulose in Guarapuava, Brazil is a case in point. The mill’s two paper machines are by no means ancient in papermaking terms; the 2.5 meter trim PM1 was built in 1975 and the 3.5 meter trim PM2 was built in 1983. Brazil is the main market for their products. Over the years, the mill has invested in machinery upgrades to produce new paper grades.

In the early 2000s, Santa Maria realized that they had to keep control of the costs and boost the productivity of these machines. They reasoned that better, more complete automation and operator information tools were important ingredients needed to accomplish these goals. They implemented a multi-year plan to increase the level of automation, quality control and information accessibility on both machines, while keeping within the budget constraints of a smaller capacity mill. The phased plan, which continues today, included the installation of a PaperIQ system on PM1 in 2001 and the most recent installation of a PaperIQ Plus system on PM2 in 2006. These two QCS systems, with their integral DNAhistorian information applications, have turned the productivity of these machines around and have improved the paper quality to a very competitive level.

Decrease costs, Increase production

Luiz Tadeu Perussolo, Paper Division Industrial Manager, says that, before the new automation systems were installed, operators of PM1 were out of touch with the papermaking process because of a lack of good information about product quality and the variations within the process. “The machine was unstable. Each operator had different ways to operate the machine. This caused variations in quality,” he says.

This instability was also affecting productivity and production cost. “We had many web breaks and high operating costs. Our owners said we must decrease the costs and increase the level of production,” adds Tadeu. Combined with the need for better quality, these directives pointed to a higher level of automation. The mill considered several vendors and, in the evaluation process, visited a very positive Metso Automation PaperIQ reference in Brazil.

The mill purchased first a PaperIQ system for PM1 to standardize the operation and solve the stability problems. The multi-grade machine makes offset paper, machine glazed paper and bleached kraft paper. Grammages range from 50 to 240 gsm. The top machine speed is 400 m/min.

Many things became clear

In addition to the scanning quality measurements, the process information provided by the system’s DNA historian application was seen as an essential ingredient in the mill’s plan to open up the papermaking process to the operators. The system comprised 1000 I/O points including the stock preparation system. “We supplied the information to the operators to help them to make decisions and operate the paper machine in a better way,” says Tadeu. “Once the IQScanner was installed many things (about the machine operation) became clear to the operators. Operators realized some variations were impossible to control. Then, we needed to take actions to solve the process problems we could now see,“ he adds. After these process improvements were made themill began to reap the benefits of the improved process visibility and automated controls. After startup of the new system quality tests were 50% better than before says Tadeu. Web breaks were reduced dramatically, from more than 8 per day to 1 or 2 per day. Average production rose from 65 to 73 tons per day. Today, average production is at 87 tons per day & the record is 112 tons per day.

Customers notice the difference

Tadeu reports many other benefits on PM1 and in customer’s converting plants. He says, with better stability, the ash content of the paper has been raised and strength and optical properties have been optimized. “In the sheeting process the paper is more stable. Customers notice the difference. Also, caliper measurement helped us to achieve more consistent quality,” he states.

As the next step of the multi-year plan, the PM1 system will be upgraded to include CD control.

Impressive results on PM

PM2 was the next candidate for an automation upgrade. The machine makes offset and bond papers with grammage from 50 to 90 gsm. The maximum machine speed is 800 m/min.

The situation on PM2 was quite similar to PM1; the operators had minimal indication of product quality or information about the papermaking process. The existing scanner was unreliable so they needed trustworthy online measurements as starting point. They knew that the PaperIQ system on PM1 had proven its reliability. So the mill started another evaluation process for a new QCS and process information system. The evaluation led to another order for Metso Automation.

The new PaperIQ Plus system and Metso DNA-based information system also includes a first for the mill – cross direction controls. CD grammage control is accomplished via IQSlice control on the headbox and CD moisture control via IQSteamPro located on the suction pickup roll.

The papermaking results after the installation in September 2006 have been impressive. CD grammage variation has been reduced by 35% on the average and CD moisture variation has been reduced by 50%. Moreover, the IQSteamPro on the pickup roll has improved sheet dryness after the third press from between 46 and 47 % to the present 49%. This saves specific drying energy and allows for extra speed potential. Tadeu reports specific steam consumption has been reduced from 2.5 tons of steam per ton of paper to about 2.4 or 2.3.

The extra sheet dryness into the dryer section has also improved machine direction moisture control. Before the steam profiler installation the last dryer section was run with the steam valve running at 100% opening; thus moisture was controlled poorly. Now, with a 60% average steam valve opening, machine direction moisture control at the machine reel is optimized.

PM2 runnability has improved as well. Breaks per day have been reduced from 3 or 4 to the current level of 2 or 3 breaks per day. Overall production rates have increased by about 10%. Machine speed is up 50 m/min on the average.

The mill uses a Maximum Sustainability Rate (MSR) index to evaluate how production rates are maintained at a consistently high value. The index, which compares average actual production to a maximum sustainable rate, has increased from 83% to 85% after the system installation. This index implies a high degree of production rate stability.

Improved quality = better market position

Quality has also improved substantially. With betterCDprofiles operators can run at a higher moisture level without dealing with streaking problems. The increase in reel moisture is around 0.5% percent. Tadeu says low moisture causes static electricity and dimensional stability problems; hence the higher moisture levels avoid these issues.

The improved paper stability has been noticed by Santa Maria’s customers, says Tadeu. “Our customers are very happy because our profiles are better. In our mill the quality rejects related to wrinkles and ridges in jumbo reels have been reduced by 1.6%.”

IQSlice Pro has reduced CD grammage variation by 35%

All told, the installation of the PaperIQ and PaperIQ Plus systems at Santa Maria has been a major factor in improving the mill’s productivity, manufacturing costs and quality positioning. Tadeu sums up the important points about the mill’s focus on improving automation and process information: “The automation systems are valuable tools to keep our position in the paper market with bigger (competitive) companies. And it is important to keep our costs as low as possible by improving manufacturing efficiency.”

In the following years, the Santa Maria mill will build on the current successes and continue on their plan to upgrade paper machine automation, quality management and information systems to achieve better quality and productivity.

Major benefits compared to a conventional roll press

There are several considerable benefits that support a press section realised with a made-in-ABK shoe press. Technically and more generally speaking, the shoe press is now state-of-the-art product for the board-making sector and the packaging paper machines because of the advantages it brings in terms of improved paper quality and enormous increases in productivity; flat pressure gradients which ensure: high dry content; increased and improved strength values; uniform web compaction and a constant CD moisture profile; and also minimized open draw which reduces the paper breaks due to the structure design.

Characteristics of the shoe press

ABK state-of-the-art shoe press

The PLC (Press Long Contact) is operated with a belt which turns around a shoe. The belt functions like a roller jacket, but it is elastic and flexible. Shoe press belts are either smooth or grooved. The dewatering capacity depends upon the type of belt and felt.The nip force is provided through a 6” piston that reaches completely across the machine. A lubrication shower placed ahead of the shoe forming a thin film of oil between the shoe and the belt. This allows the blanket to turn and prevents the shoe from acting like a brake. At the exit side of the nip, the oil is doctored off into the save all pan by the air loaded wipe.

Characteristics of the CC roll

The CC roll is a roll with variable crown and internal piston. The one installed on Indonesian site is of the hydrostatic type bearing in mind the efforts implemented (1000 kN/ml). But ABK is able to manufacture also a shoe press with a CC roll of the hydrodynamic type which can have some advantages especially in terms of maintenance. But whatever the type of CC roll manufactured, ABK always supplies simple system easy to maintain, and does not manufacture too complex products (especially in regards to pumps) so to avoid potential wad damage over ribs, and maintenance constraints.

Load system (CC roll / PLC)

The load system can also makes the difference:, ABK has one or two continuous rectangular pistons, similar to the CCR piston. It has a very good CD profile. MD profiling is an option. Other suppliers propose shoe presses with two cylindrical in-line rows of pistons which make the control of the MD and CD profiling more complex.

Benefits from cantilever Frame

ABK has decided to manufacture its shoe press with a cantilever frame coupled with the use of strungs instead of mounting beam so that disassembly of any press can be done easily and rapidly independently from all other presses. This specific structure also permits a very efficient felt changing process.

Mounting and changing performances

The technology developed by ABK in the engineering and production of the shoe press allows for incredible mounting and changing performances for all elements of the shoe press: for transfer roll 3h00; for Pick Up Press 2h00; for 1st Press 4h00; for Central press 4h00; for CCR 5h00; for PLC module 2h00; for Blanket 0h45; for Pick-up felt 1,5 hours; for 2^nd NIP felt 1,5 hours; and for Shoe Press felt 1 hour.

Tail threading device

The technology developed by ABK in regards to the press structure leads to no open draw; the sheet is always sustained by felt, and all rolls are driven and synchronized so that there is no sheet break.

Blanket clamping

ABK has improved the inflatable ring for a much cheaper and efficient clamping, by means of an inclined ring which is very simple to install and with a changing time around 1.5 hours. This is another advantage of the ABK shoe press compared to competitors where the shoe press has a slow system which requires the tightening and loosening of the front and backside bolts.

Cost saving and paper quality

In shoe press systems, a long-nip residence time will positively affect dewatering dynamics, while using less costly raw materials. This saves energy and cost in paper manufacture. Besides, it improves paper quality and strength. Moreover in terms of investment, it is worth the main strong point of ABK is that the customer can integrate in its paper lines proven technology at an affordable price.