It has always puzzled me--the location of the paper machine gauge. It is at the dry end, often after the calender stack. I once worked on a machine that had three gauges, but that is another story--most just have one.
This has troubled me for a long time--the location of the gauge. After all, if you go to any quality seminars they will tell you to build quality into the product, do not "test it in" after the product is made. Granted, feedback from the gauge can be sent back upstream quickly and parameters changed quickly, but there is still a lag.
Last week, I attended the AUVSI Convention here in Atlanta. AUVSI is the Association for Unmanned Vehicle Systems International. These folks are interested in robots--in the sea, on the land or in the air (drones). If you have read me for a while, you know I am fascinated about the potential of drones.
What if we added drones to our quality control and measurement protocols? Wild ideas...In recycled mills, the drones could look at the bales and indicate which ones to load in the pulper next, based on the grade we are making. In virgin pulp manufacture, they could survey the chip piles in real time and tell operators which chips to feed based on moisture and other parameters. Granted, we do these things now by positioning, placing bales of recycled paper in segregated groups and aging our chip piles in distinct batches. However, as we desire to make higher quality paper with the lowest cost inputs, I can see us moving to this higher standard of operation.
Soon, you will be able to deploy drones some distance, to check on your fiber supply long before it gets to your mill. You will employ drones to see how your recycled fiber suppliers bale and store bales off site. You will send drones to the forest to examine logging methods and species selection in real time. No doubt about this.
Your thoughts? Other applications related to quality?
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Well, last week's idea resulted in a resounding thumbs down:
Jim, I'm sorry but, I really don't see the need for all of this. All of the AC VFD motors for the machine are TEFC grade motors with 1.5:1 service factors. You can hit these things with a hose and have zero problems unlike the old DC drives that had exposed brushes and rotors. Up time of the newer drives is far better these days than ever before.
The weak links in the drive setup are the mechanical reducers and drive shafts. These days we are bringing the motors closer to the machine and in some cases using "C" flange motors to eliminate all reducers and shafts. In some cases the motors are actually inside the hood of the dryer section and mounted directly on the roll bearing housing. Up time efficiency is driven by the reduction in the number of parts that can fail.
Bryan Creagan
KSH Consulting
Montreal, Quebec
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It is good to see the electrical equipment discussed in LGM weekly. I am an electrical engineer, and have been involved with projects to build and upgrading paper machines since 1979. My perspective is that the motors are the most important part of any process or machine from an electrical point of view. For modern paper machines the drive motors are BIG, up to 1500 HP. The location and drive trains for these motors are an integral part of the machine design, and are best left to the machine OEM to optimize. Some rolls even have the motors built in, with no separate motor bearings. The closer the larger motors can be to the driven rolls the better, to minimize drive shaft windup and other low frequency time constants. With today's TEFC and TENV AC motors, the environment is not as much of a problem as it was for DC motors. The environment for the motor control centers and variable speed drives is a major concern, thus I would not even consider locating this equipment anywhere but an air conditioned motor control room. Plenty of space on back side of the machine should be provided for maintenance and good air flow. The electrical equipment would take up valuable real estate if located in this space. For other areas of the mill, such as the roll wrapper, I agree that the electrical equipment can be located as close to machine as practical, with no need for a dedicated motor control room in many cases.
Jubin Jackson
Resolute Forest Products
Catawba, South Carolina
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