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Toscotec unveils measurement system for Yankee hood efficiency

May 20, 2021  By P&PC Staff

Photo: Toscotec

Toscotec has released the TT Drying Equilibrium for tissue line drying efficiency.

The system was originally designed by Voith and transferred to Toscotec for further development after Voith’s acquisition of the company last year. It ensures automatic regulation of the air balance in the Yankee hoods and air system.

The control and regulation logics are managed by a dedicated PLC (programmable logic controller) that communicates with the DCS (distributed control system) of the tissue machine.


The mill can easily access the data collected, stored and organized by the PLC on local monitors, tablets, or smartphones, through a remote connection.

TT Drying Equilibrium consists of a set of various transmitters of physical data, including speed, flow rate, temperature, humidity, and pressure, and of a data acquisition and processing system.

The calculation algorithms produce the mass flow rates inside all the air ducts leading into and out of the Yankee hoods, including outgoing air, make-up air, and combustive air both on wet-end and dry-end.

The combustion air is regulated by the burner control system, while the flow of exhaust air can be regulated by the moisture control loop. TT Drying Equilibrium controls the dampers that allow for make-up air to enter the system, thereby maintaining a condition of balance over time.

In addition to controlling the air mass flows, the system also checks the actual balance using temperature sensors installed just outside the Yankee-hoods gap and of pressure transmitters inside the hoods.

As a result, TT Drying Equilibrium delivers two-fold balance control in real time, based on the calculated balance of the masses, and on the confirmation that hot air is not escaping or cool air is not being pulled in around the Yankee and hoods.

TT Drying Equilibrium enables real-time monitoring of the energy performance of the tissue machine. It processes production data acquired from the DCS and produces precise figures or trends relating to the tissue machine’s energy consumptions, including steam, gas, and electrical power consumption.

It also acquires key data of the air system’s heat recovery units, including inlet and outlet temperatures and flow rates, to monitor their performance, and plan maintenance activities. This allows the mill to check production efficiency by product over time, and to perform preventive maintenance.

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