To optimize the runability of the Yankee cylinder in the overall Tissue machine system.
Diagnostic tools are „On-the-Run Topography-TNG“ and „Real Time Infrared Thermography „. These Services are targeted to mill production staffs.
„On-The-Run; The-Next-Generation“ in cylinder profile and topography measurements.
For the past decade the limitations in the existing ability to do an „On-The-Run“ profile of a dryer surface has been limited due to harmonic vibrations in the cable supporting the sensor. Harmonics have nearly always resulted in areas where the surface topography data could not be evaluated because the harmonic cable vibration was greater than the surface deviations
At the left you can see the results of the elimination of the cable harmonics. In the lower graph you can see the trace of the sensor movement (the white oscillating line) and the yellow line showing the actual surface (the sensor measurement minus the sensor movement):
Additionally, the elimination of the air cylinder for providing the cable tension has removed another source of inaccuracy with the older generation system, by eliminating the minor variations in cable tension due to air cylinder hysteresis variations. Shown below are the tensioning springs for providing uniform and controllable cable tension to as great as 5,500 newtons cable force. In the images below you can clearly see the springs used for cable tensioning, and the „load cell’ for continuous measurement of this force. Minor cable tension variations are „alerted“ to the operator during the measurement.
Once collected, the data can be immediately reviewed in 2D topographical maps, 3D topographical maps, and polar plots. The entire surface can be displayed at one time, or any section of the dryer can be „zoomed“ or expanded for a more detailed view.
Examples of the data presentation are shown below, beginning with the crown profiles. In the first view you can see the theoretical profile (blue) and the maximum/minimum profiles measured (red/green).
On the topography graphs he black horizontal dashed lines are the positions of the condensate removal system, the left axis is the rotational position of the cylinder (zero is the #1 bolt), the horizontal axis is the cross direction position of the cylinder as the distance from centerline, and the right axis is the deviations of the surface displayed in millimeters above or below the average theoretical position.
Once collected, the data can be immediately reviewed in 2D topographical maps, 3D topographical maps, and polar plots. The entire surface can be displayed at one time, or any section of the dryer can be „zoomed“ or expanded for a more detailed view.
Examples of the data presentation are shown below, beginning with the crown profiles. In the first view you can see the theoretical profile (blue) and the maximum/minimum profiles measured (red/green).
On the topography graphs he black horizontal dashed lines are the positions of the condensate removal system, the left axis is the rotational position of the cylinder (zero is the #1 bolt), the horizontal axis is the cross direction position of the cylinder as the distance from centerline, and the right axis is the deviations of the surface displayed in millimeters above or below the average theoretical position.
You can also review the surface topography (shown below) with the polar runout (the red graph to the left) and deviation from theoretical profile (the red graph at the bottom) at the curser location.
Deviations in millimetres in Polar plot form are shown below, with the header positions (solid circles) noted, the manhole position noted as the open circle, and deviations displayed in millimeters.
Large screen displays of the polar plots can be generated, as is shown in the graph below, again with deviations in millimeters.
3D topographical representations of the data can also be quickly generated and rotated about the vertical axis for different views. An example is shown below.
b) IRSense temperature profiles
CAP - IRSense
In corporation with the Fraunhofer Institute, msquared GmbH has developed a new approach to high speed infrared sensing – IRSense: a technology to measure the Yankee temperature profile directly from the cylinder surface during production.
None of the existing IR-technologies (line scan or field view array) can accurately measure the Yankee surface directly during production. This makes a direct comparison between the operating surface profile and the temperature at best, very difficult.
With the new msquared IRSense technology, the eddy current and acceleration sensor arrangement for measuring the contour profile are replaced with a small, ultra fast IR sensor. Then a temperature measurements and calibration routine is applied. OTR-TNG and IRSense use the same CD (cross machine) spacing and data file formats, allowing a direct comparison between profile and temperature to easily be made using our software.
By analyzing the contour profile (OTR-TNG) and the temperature profile (IRSense) accurately measured correlations are noted, clearly indicating the importance of a good and smooth Yankee shape profile for uniform pressing. Any shape deviation of the Yankee surface will directly result in variances in the effectiveness of mechanical dewatering. This then shows as variations in temperature of the Yankee surface. Additionally, Yankee shape variations due to the problems or limitations with the operation of the steam and condensate system will also show as variations in temperature. Both of these conditions will initiate Yankee wear (if it is operated as a significant colder area).
These deviations will always be manifested in the reel as moisture and profile variations.
CAP – OTR-TNG plus IRSense; A tool for improving efficiency
Yankee dryers in a wide range sizes and speeds have been analyzed by msquared GmbH during the initial development and field tests of the IRSense measurement technology.
The Yankee shape and surface temperature are, in all field measurements conducted, very closely related. Low areas result in colder areas and conversely, high spots result in a hotter surface. Non uniform performance of the condensate removal system (short circuited headers or blocked straws) can be clearly distinguished.
These deviations show up as sheet moisture profile variations in the reel.
Auxiliary sheet profiling equipment like press roll steam boxes, inductive heating of the Yankee shell, or hood zoning can to a certain extent, hide Yankee shape and temperature deficiencies but do not correct the cause of the shape or temperature deviation. They predominantly are used solely to add additional drying to as narrow of a zone as possible.
Comparing OTR-TNG (shape) with IRSense (temperature) profiles opens an unlimited potential for machine efficiency optimization through proper problem identification and solution. If you can’t measure it, you can’t control it.
Analysis of dryer contour:
Figure 1.1 below shows the Yankee Contour Profile compared to a smoothing curve. This is a regression curve drawn through both the MD & CD data and a deviation from the expected crown, not the actual crown!
Data resolution at 1750 m/min: CD every 25 mm. MD every 5.5 mm.
Figure 1.1
Figure 1.2 below shows the average Yankee Temperature Profile
Data resolution at 1750 m/min: CD every 25 mm. MD every 50-60 mm.
Figure 1.2
A direct correlation between high/low areas in the shape profile and high/low average surface temperature is already clearly visible.
This strong shape/temperature relation can be very clearly seen in viewing the entire surface in 2D “carpet” shown on the following page.
Figure 1.3 below shows the contour of the dryer and Fig. 1.4 the temperature profile in a side by side comparison.
Even slight low areas (marked blue) in the profile yield to slightly lower surface temperatures and, especially on the sheet edges, a higher drive side edge in shape (marked purple) shows directly in the same position as the higher Yankee surface temperature.
Figure 1.3 - Yankee Contour Shape by OTR-TNG
(sheet area only)
Figure 1.4 - Yankee Surface Temperature
(also showing only the sheet area of the surface)
