Mid Consistency Screen

Mid Consistency Screen

ZNS mid consistency screen is a new-generation and internationally advanced stock screening equipment for pulp at mid consistency in modern time. It was developed by reference of international advanced technology, applied to thermal screening of wood pulp or straw pulp, coarse screening or fine screening of chemical pulp and waste paper pulp, and screening of preheated ground wood pulp, etc. Compared with ordinary low consistency pressure screen, mid consistency pressure screen has stronger adaptability, lower power and water consumption, higher production efficiency, etc.


  • Multi-foil design, no winding, gentle pulse, good screening effect, high pulse frequency and bigger capacity.
  • Mid consistency screen (Max. 4%), less water consumption in production, less energy cost, smaller screen basket size and lower investment and maintenance cost for same capacity.
  • Lower densification in screening section and higher screening efficiency, longer service life of screen basket.
  • Equipped with automatic oiling device and mechanical sealing water flow detection device, DCS interface reserved (detection of temperature rise and vibration of bearing), high degree of automation.

Structure and Principle

Pressure screen is made of machine body, cap, screen basket, rotary drum, base and transmission part, etc. All parts exposing to stock are made of stainless steel. Pressure screen has vertical structure and cylindrical shell, on top equipped with a detachable cap, on shell body installed all necessary connection pipe flanges, screen body and motor rack are fixed on base with bolts, cylindrical screen basket installed in shell, rotor and bearing installed in the basket; main shaft adopts mechanical sealing. Pipe-end bracket is arranged closest to the rack, connect sealing water and bearing lubrication with sealing component and bearing separately.
  1. Shell
As machine main body, made of welding stainless steel plates, annular seat set inside used for installing screen basket, drive bearing is installed at the base plate of the shell, tangential direction inlet pipe arranged on the upper part, accepted pulp outlet pipe on lower part, reject pipe and dilution pipe at bottom, the whole shell is fixed on the base plate by bolts.
  1. Top cap
Top cap is a spherical head made of stainless steel plate, connected with shell by bolts, equipped with valve connection in central part for discharging the residual gas in machine and light impurities.
  1. Screen basket
Basket has two types: plate-type waveform and bar-type waveform. Plate-type is made of stainless steel, holed and slotted. Waveform grooves on surface contacting with pulp make fiber pass screen holes (slots) easily and separate accepted fiber from impurities and fiber floc, thus to improve the screening efficiency and obtain high quality stock. After drilling holes or cutting slots, the screen plate is polished. Thus the surface of plate is bright and clean. Reinforcing rings are welded on outside surface of basket to bring sufficient strength and stiffness; flange is fixed to basket top end by bolts while the bottom end set in basket, being firmly combined and running stably. The bar-type waveform basket has hundreds of specially designed wedge-shaped bars, evenly inlaid in grooves cut on annular plates along the circle direction; the upper end is flange surface, connecting cylinder body; the lower end is a cone; the surface of basket is waveform, screen slots can be narrower than slots of plate-type, with higher precision, thus increase the open area apparently; bar strength is greatly improved than cut slots of plate-type screen; especially the surface hardening treatment extends the service life of basket; so, it is an advanced structures in the world in modern time.
  1. Rotary drum  
Rotary drum is cylindrical, on outside surface reasonably welding some lugs. High rotating velocity of drum produces high-frequency impulse to screen pulp and clean screen holes. The rotor shaft adopts mechanical sealing; in order to avoid stock leakage or entering into driving chamber, the machine is equipped with mechanical seal and sealing water connection, requiring hydraulic pressure about 0.1Mpa higher than inlet pulp pressure.
  1. Driving device
The rotor shaft is supported in a bearing seat, driven by motor through a set of narrow V type belts; lubrication device is installed in the rack base to lubricate the bearing regularly.

Technical Data

Model ZNS80 ZNS81 ZNS82 ZNS83 ZNS84 ZNS85 ZNS86 ZNS875 ZNS87 ZNS88
Nominal Area (㎡) 0.25 0.38 0.76 1.06 1.42 1.88 2.27 2.95 3.54 4.83
Inlet Consistency (%) 1—4
Capacity-Hole (T/D) 30-40 50-80 90-160 135-250 180-320 220-420 260-500 300-600 400-700 500-1000
Capacity-Slot (T/D) 20-30 30-50 60-100 90-150 120-190 150-210 200-300 250-400 300-450 320-730
Inlet Pressure (MPa) 0.15-0.4
Motor Power (kW) 15-22 11-37 22-75 30-90 37-110 25-132 55-160 75-200 75-220 132-280