April 2008
By Steve Polemitis
The demand for higher quality product at reduced costs in today's pulp and paper industry has provided a stream of opportunities for a paper industry supplier with a penchant for problem solving. Ryeco, Inc. has been providing products and services for the industry since 1991. Tim Rye, the president and general manager of Ryeco, contends that despite significant advances in technology, there are still unresolved problems with producing quality product at significantly lower costs, vital to compete in the today's global market. Diagnosing and solving those problems remains a challenge for both papermakers and their suppliers.
Ryeco has stepped up to the challenge by developing and applying technology that provides solutions to some of these unsolved problems, from identifying defective and off-spec product to almost instantaneous signaling of a sheet break, the company offers a complete range of defect marking systems, edge crack detection systems and sheet break detections systems.
Edge Marking
Defect markers are optimized to mark defects, grade changes and other off-spec paper with up to six clear vibrant colors. Multiple colors allow for specific identification of various defect types. The multi-color spray head delivers instant color change. The defect marker is generally interfaced to a web inspection system or to the mill's quality control scanner and all Ryeco marking systems are designed to work with any web inspection system. Defects and off-spec paper are marked for later removal during the unwind process.
Edge Marking Case Study
A major North American newsprint mill approached Ryeco to help solve a common production problem. The mill was experiencing paper loss problems that had direct effect on their overall cost of production. Its goal was to reduce losses by 2.5% which would result in an annual savings of $2.5 million.
The installation of the Ryeco marking system gave the mill the means to determine good paper from bad and assured it that only good paper went to the customer and the bad went to the broke system. By marking the areas of off-spec paper on the coater and marking the transition point from on-spec paper to off-spec on the supercalenders, the mill was able to minimize the amount of off-spec paper being sent out the door and minimize its slab-off and spool cores losses. The mill recorded a 3.6% reduction in paper loss only one year after installation of the marking system.
Edge Crack Detection
Ryeco's edge crack detection systems offer a solution to the costly problems related to undetected paper edge defects leading to hours of production downtime and lost profits. It offers dual edge crack detection systems with and without edge marking. The patented edge crack detector directs two precise streams of air toward opposite surfaces of the web. As a non-separated crack passes through the sensor jaws, the defect is deflected to for a small opening for the optics to penetrate. The same air that deflects the crack closes it as it leaves the sensor.
Edge Crack Detection Case Study
If a mill can categorize and quantify a problem as it is happening, that problem can usually be solved. The operation of high-speed paper machinery can be adversely affected by paper edge defects: cracks, folds and tears. Detecting these flaws is essential before there can be a solution. An uncoated freesheet mill suspected that edge cracks were the cause of many of its winder breaks. It was having six to seven breaks a day on the winders, each break lasting for about 20 minutes. It needed a system to detect the edge cracks, solve the problem and avoid winder downtime.
An edge crack detection and marking system was installed on a paper machine which ran about 3,360 ft/min with a reel trim of 303 in. Results proved to be immediate and within a couple of weeks, the winder breaks were reduced to three from seven per day. The problem was identified by the edge crack detector, but needed to be solved by using the color edge marking module to indicate crack locations. The winder speed was reduced as the crack approached and possible sheet breaks were diverted. Mill workers could actually see and cut out any detected cracks or flaws. By this problem-solving approach, the mill reduced its winder break frequency to about one per day and paper machine runability was improved more than 80% compared with baseline level.
Sheet Break Detection
Break detectors are usually not high priority until a problem occurs such as a false break or a non-detected break which causes costly downtime, wastes good paper or causes damage to the machine with wads of wrapped paper. Break detectors are typically placed in some of the most challenging locations on the machine subjecting them to direct contact with broken webs and dust accumulation that can affect measurement reliability. Ryeco manufactures sheet break detection systems that are designed for extreme heat and humidity for both open draw and closed draw locations. All sensors are single-sided and no reflectors are needed on the other side. The sensors have a unique patented process that includes a continuous air purge. This air purge keeps the sensors clean and cool, making the system low maintenance.
Sheet Break Detection Case Study
In one mill, which produces fine paper, sheet break detection systems were installed at four positions: the press section, before and after the size press in the dryer section and before the calender stack. The electrical and instrumentation supervisor commented that previous sensors were constantly knocked out of alignment and were hard to keep clean which caused missed breaks and false breaks. Ryeco's SBD 9000 sensor uses a pulsed light source, which keeps stray light sources from interfering with the operation. The electronics not only sense a sheet break but also the presence of a sheet in a separate channel, comparing the two signals and providing a fail-safe break output.
With the reliability of the break detectors, the mill was able to suspend and perform major processes such as cutting the sheet back or suspending chemical additions needed during a break condition with complete confidence.
Innovations
Recent innovations include:
- A third generation series of edge marking systems with proprietary marking modules that can make marks as short as 1 millisecond (0.75 in. at 3500 ft/min) for code in addition to conventional longer defect marks;
- Sheet-on-fabric fiber-optic break detection systems for closed draw locations that use true color recognition technology along with intensity to distinguish between all grades of paper on any color fabric;
- Jawless edge model marking systems utilizing non-atomized marks for the tissue industry;
- Marking systems for the converting and non-paper industries compatible with solvent based dyes.
In closing, Rye states, "We plan to continue to be a preferred supplier for quality control solutions in the pulp and paper industry by staying on the leading edge of technology and by following our corporate vision of innovating, improving and growing."
Steve Polemitis is vice president, engineering and product development, Ryeco, Marietta, GA.
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