Development of a new CRS for key-screening

The aim of the „CRS project“ (Continuous Reject Screen) is to reduce energy consumption when screening coarse impurities in final screening. Big energy savings are accepted in such a key-screening equipment (reject purity at the same level as in case of washing screen is assumed).

Screening efficiency:

• reject purity (fiber content in rejects) at concentration of impurities 4 % is 30 – 40 % at optimal parameters,
• at concentration of impurities 20 % is 20 – 30 % at optimal parameters,
• reject purity (fiber content in rejects) for washing screen VSV-30 is 20 – 40 % at optimal paramaters.

When compared with competitive machines of world producers, who achieve reject purity of 50 – 65 %, these results are excellent.

Conclusions from tests:

Optimal consistency:	1,5 - 2,0 % (extremely 2,5 %), the fibre content in reject grows with increasing consistency
Optimal throughput:	500 - 700 l/min
Optimal throughput of washing water:	150 - 250 l/min, according to concentration of reject impurities and momentary throughput

The machine is fully functioning in this configuration and suitable both for the concentration of impurities 4 % and in the position after the deflaking screen VDT-40 where it is able to process up to 20 % impurities in stock.

Reject sample:

Concentration of impurities in screened stock:	20 %
Flow rate of screened stock:	500 l/min
Amount of washing water:	200 l/min
Consistency of screened stock:	1,8 %
Fibre content in reject:	20,7 %
Reject consistence:	26 %

 

The machine tests are successfully completed, now the prototype installation in a paper mill is negotiated.