Pulp Paper & Logistics
FEATURE 17 VALMET
engineers during the energy optimisation become automated and continuous. The system can be easily
installed both on new machines and on those already in use for a number of years. The ABC can be implemented with different levels, starting from a base level for managing a single machine with access limited to some users, up to corporate level which can be used for the management and benchmarking of a range of machines in various premises, implementing an SQL database and a SCADA data capture and supervision system.
Real-life references The ABC system has been installed and tested with confirmed positive
results. One of the reference installations is a European tissue mill that mostly produces toilet, napkin and towel tissue with basis weights between 16 and 26 gr/m2, from virgin and deinked pulp. The target for the mill was to
decrease energy consumption or increase drying capacity. The mill management decided to focus the future investments on two technologies: a new heat exchanger and the ABC system. This two-fold change reduced gas consumption significantly: indeed, only after five months in operation, a saving of more than 15 per cent had been accomplished.
“In the short term the system
proved efficient and there is a great potential for further saving possibilities,” said the mill’s director. “At the moment, the system works while the make-up air is almost entirely closed. A small modification will enable us to exploit the heat exchanger capacity even more as for combustion air temperature and we expect a further gas consumption reduction equal to about one to two per cent.” After the ABC system was
installed another benefit was revealed. Because the hood and air system settings are monitored and optimised, it means that
the energy consumption “no longer depends on the operator’s skills, as the system performs a continuous check to find optimum conditions”.
A focus on air system balance and drying strategy Today a tissue machine uses about 70 per cent of its total energy for the drying process: most of this energy normally goes to the hood/ air system (using natural gas and electricity), while the remainder is consumed by the Yankee cylinder (using steam). A correct setting of hood and air
system, together with the proper dryness parameters, boosts the improvement of both production and quality performances and enables what Valmet regards as remarkable energy consumption reductions. Valmet’s constant data collection
from numerous different tissue machines around the world has during the years built a database of energy performance information. With this valuable information it can support customers in finding the best machine settings and improve performance.
4 January/February 2016
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