Superior Tools for Adjustable Screening Process Metso Paper Valkeakoski Oy, Finland Minna Puro

Transcription

1 Superior Tools for Adjustable Screening Process Metso Paper Valkeakoski Oy, Finland Minna Puro 8th Research Forum on Recycling

2 Content of the presentation Introduction Numerical study Results - simulation results - pilot trial results Conclusions 2 10/17/2007 Minna Puro

3 Introduction Operational demands set for DIP screening have intensified - raw material contains more and more impurities - accept pulp quality has to remain at high level - economical and environmental aspects become more significant Intensifying demands force us to use narrower slots capacity problems strong reject thickening remarkable operation problems and fiber losses with conventional technology new foil and screen basket technology was needed 3 10/17/2007 Minna Puro

4 Numerical study The basic data of simulated foils and baskets 4 10/17/2007 Minna Puro

5 Foil simulations Flow geometry static pressure [Pa] accept frame basket rotor frame periodic boundaries - 2D periodically symmetric slice - screen basket modelled as a porous media - no inlet or outlet - different viscosity values tested 5 10/17/2007 Minna Puro

6 Screen basket simulations Comparison of different wire designs - slot speeds 1 10 m/s } corresponds foil-induced - tangential velocity 0,5 m/s pulsation on the feed side feed static pressure [Pa] accept wires - 2D periodically symmetric section - constant slot width #0.12 mm - constant 0.5 m/s tangential velocity on the accept side - water material properties periodic boundaries 6 10/17/2007 Minna Puro

7 Simulation results of foil study New foil shape - ProFoil - very effective suction pulse - less co-rotation radial velocity tangential velocity ProFoil ProFoil Conventional foil 7 10/17/2007 Minna Puro

8 Simulated foil pressure pulses results New foil shape - adjustability in respect to foil speed 8 10/17/2007 Minna Puro

9 Simulation results of screen basket wire study New wire shape - Nimax - smooth and streamlined accept channel - optimised basket surface shape Conventional wire Nimax wire 9 10/17/2007 Minna Puro

10 Simulation and measured pressures Screen basket wire study Good correlation between simulation and measurements 10 10/17/2007 Minna Puro

11 Foil pilot-scale trial results Capacity study Comparison of reference and new foil - with #0.12 mm narrow slot and reference foil, plugging occurred at 0.8 m/s slot speed too low capacity - with #0.12 mm narrow slot and new foil, operation was excellent 11 10/17/2007 Minna Puro

12 Foil pilot-scale trial results Energy consumption study Comparison of reference and new foil - with #0.12 mm narrow slot, new foil used 10 % less energy than reference foil - energy saving can be even 30 % less as reported in one customer project 12 10/17/2007 Minna Puro

13 Foil pilot-scale trial results Reject thickening Comparison of reference and new foil - reference foil is not in operation window with narrow #0.12 mm slot due to very strong thickening - new foil fulfilled the target of controlled thickening regardless of slot size and reject rate 13 10/17/2007 Minna Puro

14 Foil pilot-scale trial results Stickies Comparison of reference and new foil - quality is at the same level with new foil and reference foil when running with #0.15 mm basket - with narrow #0.12 mm slot high quality was reached with reasonable low reject rates 14 10/17/2007 Minna Puro

15 Screen basket pilot-scale trial results Capacity study Comparison of conventional wires (A, B) and new wire - new wire gives 20 % more capacity 15 10/17/2007 Minna Puro

16 Screen basket pilot-scale trial results Energy consumption study Comparison of conventional wires (A, B) and new wire - new wire energy consumption is 10 % less than conventional wires 16 10/17/2007 Minna Puro

17 Screen basket pilot-scale trial results Reject thickening Comparison of conventional wires (A, B) and new wire - new wire gives low level of thickening 17 10/17/2007 Minna Puro

18 Screen basket pilot-scale trial results Stickies Comparison of conventional wires (A, B) and new wire - quality is at the same level with new foil and conventional foils 18 10/17/2007 Minna Puro

19 Conclusions Major benefits By combining the new screen basket wire with the new foil design, optimal screening result can be summed up: % more capacity % energy saving % less thickening - excellent pulp quality - excellent runnability 19 10/17/2007 Minna Puro