Paper Technology International 2024 - Journal - Page 87
PAPERTECHNOLOGYINTERNATIONAL
Figure 2: Water consumption for suction roll sealing technologies.
Figure 3: Voith’s HydroSeal con昀椀guration.
Figure 4: Cooling water circuit con昀椀guration: Open vs Closed loop.
In this study three kinds of cooling units have been evaluated:
•
Cooling tower
•
Adiabatic liquid cooler
•
Chiller unit
The cooling tower has the highest water consumption of all
the above, usually this type of machine requires a constant water
昀氀ow make-up of about 10 to 15 lpm.
The adiabatic liquid cooler has the lowest energy
consumption, but still requires a water 昀氀ow of 1 to 5 lpm.
Chiller units have the highest energy consumption but do
not need a constant make-up of water. With reference to the case
study of Toscotec AHEAD 2.2 tissue machine plant with a maximum
production capacity of 125 tpd, we must cool down a total water
昀氀ow of about 400 lpm, which can be managed in a closed loop
con昀椀guration that guarantees a cooling capacity of about 282 kW.
According to the above data, a close loop con昀椀guration
based on cooling tower technologies requires 7205 m3 of water per
year and an annual electricity consumption of about 52,440 kWh.
Whereas, if one selected an adiabatic liquid cooler, the annual water
consumption would drop to 692 m3 and annual electricity
consumption would also drop to 13,585 kWh.
A proper chiller unit would allow to save water and reduce
the annual water consumption up zero, but it would require the
highest annual energy consumption of all three option, equal to
307,979 kWh.
Besides the energy and water evaluation, it is also important
to underline that mill location plays an important role in the selection
of the cooling unit. When the wet bulb temperature is too high, the
cooling tower and the adiabatic cooler become inef昀椀cient, and a
proper chiller unit is needed to guarantee the necessary cooling
capacity.
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