All "dry" roads lead to Research Center.
Most papermakers come to the Center with a problem in hand. They may have a poor moisture profile, limited drying capacity, poor system stability, flooding dryers, long thermal response times, or a lack of energy efficiency. The Johnson Research Center is able to duplicate many of these problems on its pilot dryers and then work to develop a solution. According to the company, cooperation with papermakers at the Center has played a key role in advances in drying technology, including high-speed stationary syphons, Turbulator[R] bars, De-tuned bars, Vortec[TM] vacuum generators, high-efficiency thermocompressor configurations, high-efficiency separator stations, sheet break recovery strategies, and advanced steam system controls.
Many projects at the Center focus on specific issues on a particular machine. Because of the nature of these projects, trial programs developed at the Center typically have an immediate payoff as well as long-term benefits, according to Johnson.
INSIDE THE RESEARCH CENTER
The Johnson Research Center focuses on testing different equipment combinations and system components (such as rotary joints, stationary syphons, rotary syphons and Turbulator bars) under the conditions of a particular customer's operation. Through the data gathered, Johnson can help determine the right components to maximize machine performance. System analysis and seal technology is also a major area of study for Johnson engineers. Real-time simulations on the JOCO 4000 and 6000 test dryers allow mill personnel to see the performance of recommended equipment before making an investment decision.
The 1350 m2 (14,500 ft2) facility includes:
* Control room with closed circuit video system for real time observation inside the test cylinders
* Product development and performance test areas include Seal Technology Laboratory and Hot Oil Evaluation area
* Conference room seating for 50, with closed circuit television for live viewing of testing
ARKANSAS KRAFT, UP & RUNNING FASTER
Arkansas Kraft produces high-quality linerboard at speeds up to 520 m/min (1700 feet/min). Mill representatives visited the Johnson Research Center and were initially focused on quantifying the potential improvements in drying capacity and profile uniformity from the installation of stationary syphons and Turbulator bars. In the process of conducting these trials, dryer flooding and flood recovery were added to the program. Plant engineer Don White and PM1 Manager Lonnie Flowers also expressed interest in the influence of the syphons and bars on the dryer surface temperature response. This was quantified and Johnson representatives also demonstrated the ability to quickly adjust the steam pressures to greatly reduce the magnitude and duration of the dryer surface temperature overshoot, and to anticipate the recovery after the sheet is re-established.
As a result, sheet moisture is back on line in a fraction of the previous time. Arkansas Kraft recognized the significance of this capability in improving machine efficiency and productivity, leading to the installation of a full Dryer Management System, along with the stationary syphons and Turbulator bars.
SCA OBBOLA GAINS DRYER CAPACITY
SCA Obbola, Sweden produces 410,000 metric tons/yr of two-ply linerboard, in the range of 100-186 gsm, at speeds up to 800 m/min (2625 feet/min). The 10 m wide machine was installed in 1975. At that time, it was the widest paper machine in the world, and it retained that distinction for nearly 20 years. The machine production was, however, limited by drying capacity, even following a number of major machine rebuilds. Trials at Johnson served to quantify the existing dryer performance and then demonstrate the potential improvements resulting from the installation of PTX rotary joints, stationary syphons, and new Turbulator Tube bars. The ensuing rebuild included the installation of new joints, syphons, and bars, and the elimination of all of the front side joints. The result was a reduction in operating differential pressures, an improvement in the moisture profiles, and an increase in drying capacity of more than 20%.
AYLESFORD NEWSPRINT'S BETTER PROFILES
Aylesford Newsprint faced the issue of nonuniform cross-machine moisture profiles. This appeared as periodic dry streaks in the sheet, often in the center and occasionally at the quarter points. Further, the machine had excess drying capacity (too many dryers) and could not reduce the steam pressures any further without causing problems with dryer flooding. During trials at the Center, Johnson engineers were able to demonstrate the source of the profile variations and develop a unique set of Turbulator bars that was able to improve the profile uniformity while maintaining the low heat transfer rate of the older rotary syphons. When PM13 started up with the new equipment, the operating differential pressures were reduced, blow through was reduced, profiles were improved, steam pressure turn-down was increased, picking problems were reduced, and dryer flooding was eliminated.
OPTIONS FOR OPTIMIZATION
Depending on the mill, the following considerations can be critical to long term efficiency and optimization:
1. Heat transfer comparison, before and after installation of Johnson equipment, such as Turbulator bars, stationary syphons, rotary syphons, and steam joints.
2. Control and adjustment of dryer edge temperature profiles.
3. Evaluation of blow through characteristics for specific syphon and dryer configurations.
4. Evaluations of dryer drive and torque requirements over a wide range of operating and non-production conditions.
5. Evaluation of drying capacity using detailed dryer simulation programs.
6. Demonstration of the potential for reducing energy consumption by installing new joints, syphons, and bars (reduced venting, less vacuum condenser flow, lower steam pressures).
7. Education on the behavior of condensate in the dryer under a wide range of machine conditions. The behavior is monitored live, with a closed circuit TV, and indirectly with measurement of dryer surface temperatures, condensing loads, steam pressures, and drive power.
8. Measurement of dryer surface temperature response to changes in pressure, heat load, or speed.
9. Demonstration of advanced dryer system control strategies.
WHAT YOU WILL LEARN
* How mill visitors use the Johnson Research & Development Center to solve specific problems.
* The Center's Capabilities.
* Johnson web site: www.joco.com.
* Email questions on the Research Center to: firstname.lastname@example.org.
RELATED ARTICLE: WHAT PRODUCTION AND MAINTENANCE SUPERVISORS WANT
From working with mill personnel, The Johnson Corp. has created the following "checklist" of what production and maintenance supervisors look for in visits to the company's Research Center:
* The ability to test drive dryer equipment before the purchase
* The opportunity to improve operating efficiencies and reduce operating costs
* The ability to look inside the dryer at the mill's operating conditions
* Installation and maintenance practice
* Reduced maintenance time due to factory certified training and proper installation
According to the company, results of customer trials at the Center typically focus on:
* Dryer limited production
* Chronic flooding
* Rebuild project under consideration
* Machine speed increase project
* The need to reduce energy consumption
* The desire to improve operating efficiencies
* Large moisture profile deviations
* Wet edges
* Dry edges
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|Publication:||Solutions - for People, Processes and Paper|
|Date:||Sep 1, 2004|
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