Paper Technology International 2020 - Journal - Page 72

PAPERTECHNOLOGYINTERNATIONAL
Change in Moisture Content (Before Nip – After Uhle Box vs. Energy)
Figure 9: Energy Savings Possible by Controlling Felt Moisture.
In a series of stepwise reductions, vacuum was reduced
until sheet dryness was affected. It also became obvious from our
measurements, that the 2nd uhle box was ineffective. Through
these trials, we were able to redirect vacuum from the blower to the
pick-up roll, and totally eliminate the liquid ring pump and the 2nd
uhle box.
Summary of Savings
• 2% of 2260 kWh blower reduction: 45 kWh
• 1 Liq. Ring Pump shut down: 190 kWh
• Total: 1900 MWh/year
CASE STUDY THREE: Energy Savings and Process Control Enhancement
FFT Analysis of Energy Data Shows a Peak at 8 Hrs.
Figure 10: The frequency graph of the data shows discrete periodicity at 8 hrs.
In this study continuous measurements were taken with the
3 heads and compared to energy consumption on the machine.
A chart of these measurements is shown in (Figure.10.above)
The moisture content from the heads were plotted continuously
along with the energy being used to dry the sheet. By correlating
the amount of water removed (felt water content with sheet on,
minus felt moisture after the uhle boxes, to the amount of energy
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consumed during the felt start-up phase, we established a bi-modal
distribution (Fig. 11 opposite). By comparing the population of felts
with high moisture removal after the uhle boxes (≥ 2500 l/min. vs
those lower than 2500 l/min.), it can be shown that the population
with the lower total water eliminated though the interaction among
flooding showers, high pressure cleaning showers, and vacuum
dewatering, also consumed 2.2% less energy.

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