The finished thermo-mechanical pulp contains the lignin of the wood, so that the pulp yield is double that of the pulp yield obtained from a chemical pulping process.
Sometimes chemicals, in addition to temperature control, are used to improve the yield in the mechanical pulping process, which is called the CTMP process.
Energy consumption is the main driver in mechanical pulp production. For reason this it's essential to select the valves and related equipments so that they meet the process requirements.
In addition, contaminated steam and very erosive flow media sets challenges to valve selection.
Metal seated valves
Valmet's Neles™ valves and actuators have performed successfully in TMP systems since their inception.
The R-series control valve with its rugged seat design has quickly proved itself to be the answer. The availability of the Neldisc™ metal-seated butterfly valve is the right choice for contaminated steam control.
In TMP discharge, the specially designed MC segment valve provides an optimized flow path for medium-consistency pulp.
The body may be cobalt-based alloy coated, and the flow path in the valve is continuously increased to eliminate restrictions where material may build up.
The seat is designed in such a way that its sealing surface is not located directly in the flow stream. This gives the seat an extended service life.
The seat is located inside the valve body, which prevents forces in the pipe system from influencing the sealing effect.