Mid Consistency Screen

• Installation and Commissioning

  1. Foundation

  The machine adopts reinforced concrete structure; wait the foundation to reach the curing period, hang the screen to the foundation and pad the revising block and anchor bolts, grout for the first time after preliminary horizontal correction, then accurate calibration after the cement firmed and fix the anchor bolts with equipment; grout for the second time; the running stability of the screen is based on the levelness of the upper surface of the basket and big v-belt wheel, the above level should be corrected within 0.1mm/m.

  2. Crane equipment and space

  In order to facilitate the installation and maintenance, lifting equipment should be equipped on the work site with lifting capacity of weight of the whole screen; above the pressure screen should stay the 2m height of the space to facilitate hanging out rotor body, basket and spindle, etc.

  3. Pressurized screen installation

  Hang the whole pressure screen from the supporting plate with lifting lugs on the base plate and lifting holes and place it on the foundation; when installation, keep level to make the screen body stable and make all anchor bolts uniformly stressed. Ensure that the machine is completely empty and tighten all bolts.

  4. Installation of motor 

  Install vertically the motor onto base plate, which is arranged in the motor rail. Nest the v-belt wheel into motor shaft and make it at the same level with v-belt wheel of screen body; after the belt wheel installed, looking down from the top, the rotation of the motor should be clockwise.

  5. Installation of belt and belt wheel

  a. Correctly install the belt wheel to the shaft, check the contact condition of the two belt wheelswith ruler; turn two belt wheels half circle separately, ensure that the rotation of the belt wheel is correct; if any error, correct carefully.

  b. Install the V belt, adjust the center distance of the belt wheel to make the relax V belt tightened.

  c. Ensure the rotating direction of main shaft is correct; look down from the top , the rotation of the rotor should be clockwise. Start the motor to adjust the tightness of the V belt; the key factor for normaloperation of V belt driving device is the tightness of the V belt. Right tightness means no slip under the load of peak value and in the loading operation the relax side should be slightly arciform.

  d. When the v-belt is stable after running some days, and then adjust the tightness of the belt.

  6. Connection of pipes

  Notice: Pressure screen body cannot be a bracket for connection pipe.

  6.1 Inlet pulp pipe

  a. The height of the inlet pulp pipe and outlet pulp pipe should be generally about 0.8m higher than big flange of top cap of the equipment to ensure the pressure screen is full of water to avoid interrupting pumping pulp; what’s more, reverse pressure is formed to help effectively adjust the pressure screen.

  b. Inlet pulp pipeline should be equipped with valvetocontrol the inlet pulp pressure.

  Inlet pulp pipe should be equipped with pressure sensor and meter so as to know the inlet pulp pressure and operation pressure timely, identify whether the running is normal or not.

  Inlet pulp pipeline should be equipped with concentration control system in order to stabilize the inlet pulp consistency.

  6.2 Accepted pulp pipe

  a. The outlet(accepted)pulp pipe should be equipped with valve to control the flow rate and should be equipped with pressure sensor or pressure gauge at the same time; outlet pulp pipeline should has flow rate meter to know the throughput and make it stable. At the end of the pipeline entering into accepted pulp chest, equip a control valve. Generally the accepted pulp need not be pumped to next machine; if inevitable, install a control valve.

  b. Open a hole at the bottom of the accepted pulp outlet pipe, arrange washing/emptying pipe with valve, connect with pure water and pollution discharge pipeline separately, closed at ordinary times, open the valve when shut down the machine to wash and discharge pollution.

  6.3 Tailings pipe (rejects, light impurities and air exhaust pipe):

  a. Tailingspipe on the cap should be equipped with adjustment valve used for deslagging.  Because a large displacement of slag discharge at one timemay soon clog the tailings pipe, thus control the flow rate; ball valve is advisable.

  b. The cap should be opened when hang out the basket and check the inside, thus, use soft pipe to connect it to quick coupling; easy assembly and unassembly, convenient to move the cap

  6.4 Reject diluting water pipe

  a. Reject dilutingwater pipe insert into the cylinder followingtangential direction. The residual diluting water can be added to the lower part of screening area to washing heavy reject through the diluting water pipe nearby the discharging heavy reject nozzle; it also can be used for quickly watering before startup and washing before shutdown.

  b. Pipeline should be equipped with adjustment valve.

  6.5 Sealing water pipe

  Water supply system has been equipped on the mounting plate of sealing water distributing pipe. When installing, link the clean water pipe with water inlet pipeline of this system.

  6.6 Discharging pipe

  There is a discharge interface in the accepted pulp connection mouth to discharge through controlling the pollution discharge valve. Discharge pipe should be extend to ground, try to minimize splashing near the belt. When design the pipeline, notice that discharge pipeline can also be used as probe tube.

• Key Points for Operation

  1. Start up 

  a. Check whether there is sundries in the machine before starting up. The rotor should rotate lightly when stir with hand.Lubrication system has been added with lubrication grease. The driving system and the direction of rotating should meet with installation requirements. (drum rotation should be clockwise seeing from above)

  b. Open the sealing water valve and tailingsvalve, close the inlet pulp pipe valve.

  c. Open the dilution water valve, make the pressure screen full of water, adjust the opening degree of reject pipe valve

  d. Switch on the motorand open the inlet pulp valve,increase the flow rate of the stock slowly to prevent it clogging the basket; the consistency of the stock should be increased slowly to avoid exceeding the scope of the required consistency.

  e. Adjust tailings quantity with valves, so as to meet the requirements of reject rate

  f. Open the accepted pulp valve slowly, avoid excessive pulp clogging the basket;observe the pressure meter on the inlet pulp pipe and accepted pulp pipe until reaching the required throughput.

  2. Running

  a. Keeping stable inlet consistency and flow rate is a vital precondition of running steadily.

  b. Inlet pulp pressure: 0.1-0.5Mpa in general

  c. Operating pressure: 0.02-0.04Mpa in general

  d. Dilutingwater pressure should be 0.04-0.1 Mpa higher than inlet pulp pressure

  e. The pressure of mechanical sealing water should be 0.1Mpa higher than inlet pulp pressure, with flow rate 2-5L/min, the water temperature discharged cannot exceed 60 centigrade.

  3. Clean basket.

  a. If the basket is clogged, the electric current of the driving motor will increase and the pressure of the accepted pulp pipe will decrease. To handle the problem, close the accepted pulp valve,open the reject pipe valveand add diluting water to accepted pulp opening; when the accepted pulp pipe pressure close to the inlet pulp pressure, indicating that the clog has been dredged. Open the accepted pulp valve slowly and put the discharge valve to its original position.

  b. If the pressure of accepted pulp pipe is still very low and inlet pulp pipe pressure very high, this indicates that the clog has not been removed. At this time, the pressure screen must stop running, open the upper cap, hang out the basket, wash the basket with high pressure water and examine wear degree of the basket.

  4. Stop running  

  a. Stop to supply pulp and then pump into water.

  b. Open the discharge valve and heavy rejectvalve, empty the waste water and heavy rejects.

  c. Let the water circulate in the screen to dilutethe stock and clean the screen; don’tturn off the accepted pulp pipe valve at this moment; otherwise, the liquid will flow into the inlet pulp area and clog the screen; clean the screen body until there is no fiber.

  d. Turn off the motor, acceptedpulp valve, diluting water valve, discharge valve and heavy reject valve.

  e. Close the sealing water valve.

• Maintenance

  1. The main shaft adopts lubricating grease, at the front end of engine base board set a device for adding oil, oil twice every week.
  2. Bearing of cap lifting device be oiled once a year.
  3. The tensity of the v-belt must be checked frequently.
  4. Frequently check if the supply of mechanical sealing cooling water is normal or not.
  5. To avoid restarting difficultly, when shut down for a long time, the basket must be cleaned carefully and the screen must be fully filled with water.

• Spare Parts

  1. Rotor

  2. Basket

  3. Mechanical sealing

  4. V belt