8 CRISTINI
Microwave consistency measurement
Energy and process optimisation in the forming section are possible with the use of Cristini microwave array sensor technology, as explained by Peter Resvanis, Phillipos Vrizas and Luca Canali *
papermaking expertise to run at their best efficiency. Recent instrumentation
T
technology from Cristini Diagnostic Systems allows real time data outputs for consistency and drainage in the most critical parts of the forming section, even where the access spatially limited, as shown in Figure 1. The logic of the Cristini planar microwave array sensor technology is typically oriented to the easy integration into other elaborate systems (DCS-MCS- QCS), found in the control loop of the papermaking processThe substitution of radioactive sources or standard radio frequency resonance sensors with innovative microwave sensors arrays is the key point of a successful story started more than 20 years
ago.This new and innovative application of the microwave technology has changed forever the technology and principles of the consistency meters, setting what is now a standard in the paper industry for these sensors. Cristini Diagnostic Systems,
after introducing the world’s first portable microwave consistency meter, has developed fixed point and/or traversing measurement sensors that allow direct connections to the machine’s own DCS/MCS systems for data analysis. Fast Fourier Transform
May 2013
oday’s paper machines require an impressive amount of data collecting and huge
efficiency while reducing the energy consumption of the forming, pressing and drying operations. Changes on the table are measured in real time and these measurements can then be used in a variety of methodologies. Advancements in
Figure 1: FiberScanFIX installation point in restricted areas The direct measurement of
(FFT) capabilities are included with this line of sensors, providing near instantaneous read-out of pulsation or vibration issues. The 24/7 unmanned data
collection in the forming section has allowed impressive results of process control and paper quality improvement.
water on the wire provides visibility into drainage rates and the effects of stock preparation (raw material quality, chemicals/ additives) and former set-up. This information can help
improve product quality, forming fabric performance and process
instrumentation have opened new avenues for effective use of vacuum table elements to control sheet consistency for a variety of papermaking applications including dandy rolls for improved formation, multiple formers for optimum formation, coverage, and ply bond, as well as numerous chemical dosage applications. Several studies, performed in
different formers configuration, including traditional Fourdriniers, revealed the opportunity to reduce the electricity consumption, without compromising the machine efficiency. Figure 2 provides a good
example of what can happen when too high a vacuum is applied to a gap former producing white top liner. Consistency level in the two
critical points (before bonding and before couch roll) remain almost unchanged although there is a decrease of low vacuum equal to 50 per cent.
Figure 2: Drive load saving
In addition, a better distribution of the dewatering between the low and medium vacuum zones can often lead to higher paper quality aspects elimination,
Pulp Paper & Logistics
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36