Largest steam/water heated calender rolls at Lang
May 1, 2001 By Pulp & Paper Canada
The Lang mill installed the largest steam/water heated calender rolls (1068 mm x 8530 mm) ever delivered, provided by SHW for the Janus MK 2 calender. The patented Aquitherm PS/W rolls can be switche…
The Lang mill installed the largest steam/water heated calender rolls (1068 mm x 8530 mm) ever delivered, provided by SHW for the Janus MK 2 calender. The patented Aquitherm PS/W rolls can be switched from steam to water, while the calender is operating.
The peripherally drilled Aquitherm rolls consist of a chilled cast iron roll body, bolted-on flanged journals, siphon tubes and a steam/water valve. When heated with water, the calender roll functions as an Aquitherm-P (Tripass) type roll. When heated with steam, the calender roll functions as an Aquitherm-PS type roll. Touch screen controls allow for adjustments in the flow of steam and water, allowing the mill greater flexibility in roll heating and cooling and in matching the heat required to the various grades of product produced. An automatic valve in the roll is the key to dual-mode heating.
When heating with water, water enters the roll through the centre siphon pipe, where the water pressure opens the steam / water valve and water is directed through the peripheral fluid passages transferring its heat to the roll surface.
When heating with steam, the flow is reversed. Steam is directed into the peripheral fluid passages first keeping the steam/water valve closed. Condensate is collected through the siphon tubes at the bore ends into the center siphon pipe and exited.
At Haindl, SHW Aquitherm -P calender rolls were delivered, as part of the Janus MK 2 calender. The TRIPASS-2 design compensates for temperature loss of thermal oil when passing through the roll in operation.
The oil is passed in two bores out of each three from the tending to the drive side and is reversed in the third one, thus doubling the flow speed.
Fine tuning is provided by the inserted TDC (Temperature Drop Compensation) displacers in the peripheral bores with diameters increased in a stepwise fashion.
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