A tissue machine is a simplified version of a paper machine. The head box is part of the tissue machine where the pulp suspension is spread evenly over a wire, which then accelerates close to the overall tissue machine speed.
Controlling the flows
High speeds and quality standards require a good ability to control the flows. When handling steam, large pipe sizes are often in place that require a cost-efficient valve selection. Also, the tightness of the steam valves is often an issue that jeopardizes the plant's energy efficiency. Another challenge is tissue additives, which can be hazardous to the environment or even toxic.
For flow control services, V-port segment valves are recommended. For large pipe sizes, cost-efficient triple eccentric disc valves are the right choice. Metso's high-quality ball valves are recommended for applications that need extra tightness and reliability. Triangle-shaped, live-loaded packing can be installed into the shaft if toxic or environmentally hazardous chemical leakage is a problem.
Minimized process variability
- V-port segment valves give better controllability of the flows; this can affect the quality of the product
- The total valve price can be reduced significantly if butterfly valves are used in the right places
- Steam economy and energy efficiency can be increased with an extra tight ball valve sealing
- A plant's environmental impact can be reduced and safety improved with a tight shaft sealing