Paper Machine, Beloit Bel Bai III, 9,372mm, Supercalandered newsprint (SCB), 1,371m/min, 825TPD
- Originally installed as a newsprint machine in 1988. Design speed 1,371m/min on 47gsm Newsprint (825 mtd @100% efficiency)
- Shut down in 1993.
- Metso rebuild to manufacture SCB.
- Rebuild Consisted of :
- New headbox.
- Former rebuild to Metso roll-gap former design.
- Replacement third press frames designed for future shoe press.
- On line OptiLoad Supercalender (6 rolls).
- Reel rebuild to include secondary arms centerwind assist.
- New Winbelt winder.
- Metso XDi DCS and Metso QCS (gauging)
- Re-Started up in 2001. Design speed 1,371 m/min on 47gsm SCB. (825 mtd @100% efficiency).
- Shut down December, 2003.
VALUE ADDED PRODUCTS
By varying supercalender loadings, temperatures, and furnish, three grades of uncoated groundwood papers are made on SM2161, in the basis weight range of 47-52gsm. If needed, newsprint can also be produced on the machine, but the last General Manager said that the game plan, as much as possible, was to keep value added grades on SM2161 and newsprint production on No. 2 PM. Grades currently produced on SM2161 are:
Product Characteristics Uses
Abical SC-B Supercalendered, Inserts, Flyers,
35 Gloss Circulars, Magazines,
Catalogs
Abical SNC Supercalendered, Inserts, Circulars,
28 Gloss Special Sections,
General Commercial
Printing
Abibrite 65 & 70 Non-glossy, Machine Inserts, Circulars,
Finished, 65-70 GE General Commercial
Brightness Printing
Before the decision was made to go to value added grades at the mill, the mill superintendent for value added production, said that three separate trials using the mill’s yellow pine furnish and anticipated chemistry were conducted by Metso in Finland. These trials confirmed that a quality supercalendered paper could be made on the machine without any major deposition problems. Printing trials also showed that the paper would be very suitable for use in traditional SC and uncoated groundwood applications.
SM2161 Modernization
SM2161 PM is a 9.372mm wide Bel Baie III unit that was completely rebuilt by Metso Paper for production of SC and groundwood specialty grades. The wet end was outfitted with a new headbox and the forming section was overhauled to not only streamline it for value-added production but also to eliminate the wet end misting problems typically associated with Bel Baie formers
The old Beloit ConverFlo headbox was replaced with an OptiFlo dilution controlled headbox with consistency profiling, dry weight control, and an IQ dilution CD profiler. The headbox produces excellent CD dry weight, filler, and fibre orientation profiles, essential ingredients for total profile management within the supercalendering process. Kajanni RMi low consistency analyzers were installed to measure the fibre and filler consistencies of headbox flow and wire water. These units also provide automatic control of the retention and break time filler in the process.
The forming section was rebuilt into an OptiFormer roll and blade type gap former, which produces more symmetric Z-direction sheet properties, especially the filler distribution, and added dewatering capacity. Addition of a HiDry fabric conditioner and rebuild of the former ventilation system were designed to improve overall former cleanliness and reduce misting.
The old Beloit Tri-Vent press section was rebuilt by Metso and modified by removing the fourth press and replacing it with a SymRun four-drum dryer group, equipped with VacRolls and SymRun HS Blow Boxes. Metso fitted a new ceramic cover on the center press roll along with a double doctor. A PressRun Blow Box was installed in the press-to-dryer transfer.
Currently there are 39 total dryers in the dryer section, arranged into one single tier (the new SymRun group) followed by three single-tier and three double-tier groups. This section of the machine is basically the same as it was originally except the steam and condensate system was rebuilt to have DriCompact stationary syphons and steam joints, thermo compressors, separators, and valves. A VIB AirTech re-moisturing shower was added in the fourth dryer section, which, along with a VIB rebuilt steam box in the press section, is used to control final moisture profile of the sheet. The original dyer hood was rebuilt by Enerquin.
The six-roll OptiLoad calender is located at the end of the dryers. It has four effective nips, where the paper web is pressed against a hot steel roll. Depending on the grade being produced, a maximum loading of 2,430 pli can be applied in every nip. Three different grades are made on SM2161 by varying the temperature and linear load on the supercalender, along with furnish properties.
The original Beloit reel was rebuilt to an OptiReel unit with an air doctor and secondary center wind assist. The new 1,219mm dia reel spools are “beefed-up” versions of the old reel spools to handle the additional weight of supercalendered papers compared with newsprint. In fact, all frames in and around the dry end had to be “beefed-up” to handle the heavier weight spools and paper. Water-jet tail cutters are used at the end of the machine.
The old Super 1 winder configuration was rebuilt into a Metso WinBelt type having a web threading splicer and a new windup section. The slitter section was supplied by GL&V. ABB rebuilt some the drives and installed new AC drives on the calender and winder.
The entire paper machine is equipped with integrated DCS and QCS supplied by Metso Automation. A new PaperIQ measuring frame was installed after the OptiLoad calender, for online measurement of basis weight, moisture, ash, colour, opacity, brightness, and gloss on both sides of the sheet. Retention and consistency monitoring on the wet end was also provided by Metso Automation, along with a rebuild of the existing paper testing facilities.
All quality controls are performed by Metso Automation’s Damatic XDi system. CD basis weight is controlled by IQDilution, CD Moisture is handled by the aforementioned VIB rewet shower, and CD gloss and caliper are controlled by the OptiLoad Sym Z rolls and three VIB steam boxes. Defect detection (spots, holes, streaks shives, wrinkles, etc) is provided by a Metso Parsytec system. IQTension control is used before and after the calender stack. A Sensodec 6S system provides online runnability and condition monitoring. Metso also supplied the machine’s break monitoring cameras.
New and rebuilt pumps for SM2161 and elsewhere were provided by ITT Goulds. Cutler Hammer supplied new switchgear, valve refurbishing was handled by Fisher, and Abbot Machine rebuilt the Herkules roll grinder. Startup machine clothing was provided by Weavexx.
As part of the project, a new roll handling system connects SM2161 to the existing mill complex. This flexible, high capacity conveyor system, also supplied by Metso, separates, marks, and moves roll sets from combined narrow rolls to jumbo rolls in three different levels, from winder to warehouse.
Online Supercalendering
Online, multinip supercalendering was just coming into use when the decision was made to go to value added grades at The mill. The cost advantages of online supercalendering, compared with traditional offline finishing, were significant, despite the challenges of such a new application.
Effective control of the OptiLoad for maximum performance, however, has taken some time.“Metso has been with us every step of the way. We currently have the most up-to date control software for the OptiLoad, and are ahead of the curve in terms of implementing the latest technology.”
Metso installed a “black box” on the OptiLoad that feeds real-time operating information directly to Finland and the Metso Future Care. With real-time information from the black box and other areas of the machine, Metso control and process specialists helped the mill progressively optimize SM2161.
“We’ve been going back to some of the basics on how the technology is being applied and how it’s functioning in regard to our specific paper machine. We’re looking at reliability issues and made sure that we ramped-up on our productivity curve”.
With the help of Metso, the mill and the company’s corporate engineering department were able to pinpoint and prioritise some of the OptiLoad control issues. Metso committed additional resources and an “action plan” was been developed to “help us systematically go through and resolve these issues.
“We made very positive progress. Most of the software and process changes were taken care of. We installed new mirror finish thermo rolls on the calender, which gives us better gloss. Higher gloss let us back off a little on calender loadings on some grades, which in turn gave us a corresponding bump in brightness, which then allowed us to reduce the more costly calcined clay ratio in the sheet.”
The mill emphasized that one very important key to efficiency on SM2161 was the flexibility of the online OptiLoad calender. It can be loaded and unloaded and temperatures increased or decreased to produce the gloss and other properties needed for the various grades produced on the machine. The target gloss for Abical SC-B, for example is 35, which is attained by running about a 2,400-pli loading on the calender nips.
Wet End Optimization
An Abitibi-Consolidated wet end chemistry expert was working with the mill to “fine tune” the chemistry and wet end operations of SM2161 paper machine. “The way we’re operating now, we have no pitch problems at all on SM2161 machine, and our production was ramped up to corporate standards of efficiency and quality, which, I can tell you, were very high.”
Attributing at least some of the mills’ success to the quality of fibre going into its processes, “for someone with a background in forest engineering, I’m very impressed with the quality of fresh pine fibre available to the mill, and the quality of SC papers that are being produced on the SM2161 machine with such fibre.”
Stabilising pH and temperatures in the process is critical to controlling pitch and deposition problems on the machine. “De-coupling” pitch control from pH control “helped a lot, we were previously using alum for both pitch and pH control. But now we’re using an organic acid to stabilise pH while continuing to use alum to control pitch. This has reduced the swings in pH, and along with it the swings in wet end retention we were experiencing earlier.
“The work we’ve been doing lately has resulted in a much tighter pH range of furnish coming from the pulp mills. We’ve also been able to lower pH in the thick stock tanks to the 5.2-5.4 range, which means we don’t have to use as much acid to trim the machine,” Stevens explains. Headbox pH on SM2161, he adds, averages 4.8.
“Overall, we’ve been doing a much better job of holding filler in the sheet. We’ve seen dramatic reductions in our alum-aluminate usages as well as similar retention aid reductions.”