Cause Analysis and Treatment Methods of Plugging Material by Pneumatic Lift Pump

The first-line raw material storage and transportation system of our company adopts Φ1.6m × 8.5m pneumatic lift pump, which is supplied by 3 Roots blowers. In this paper, the phenomenon of blocking material appeared in the use of pneumatic lift pump is analyzed and the solution is found out.
1, Roots blower fan failure

1.1, Roots blower outlet relief valve pressure setting is too small

Trial production early, with the amount of mill feed increased, appear to enhance the pump blocking material. Roots blower current value of about 65%, is a normal range, but Roots blower outlet safety valve exhaust. On-site pipeline barometer readings did not reach the safety valve emptying pressure 80kPa. Re-adjust the safety valve pressure screw, such blocking material can be ruled out.

1.2, Roots blower belt off or burning

In the V-belt wear or aging when the new triangle tension is not suitable, easy to make the V-belt off or burn. For example, the central control room screen shows a Roots blower current value dropped from about 70% of normal to no-load current 40%, while the other two Roots blower current from about 70% to 80%. In the control room did not pay attention to this alarm, switching standby Roots blower is not timely, leading to the pneumatic lift pump blocking material. The on-site inspection revealed that the safety valves on the outlet pipes of the three Roots blowers were all exhausted outward. The triangle of the first Roots blower was dropped off or burnt out, causing the motor to run idle, resulting in an increase in the current of the other two blowers. Switching to a backup Roots blower solves the problem.

1.3, Roots blower outlet check valve spool off, closing valve disc wear

Roots blower outlet check valve role is to prevent the pressure air flow back to the rotor cavity after the fan down. Globe valve pneumatic control, open before the fan motor operation, shut down after the motor shutdown, cut off the anti-channeling pressure air flow. Due to the cut-off valve wear and tear of the valve plate, resulting in pressure flow from the gap anti-channeling, impact check valve spool, a long time, resulting in spool off. The blocking phenomenon caused by such causes is as follows:

The control room screen shows three Roots blower current value from the normal value of about 70% of the peak instantly dropped to no-load current about 40%. On-site inspection of gas lift pump blocking material, but 3 Roots blower safety valve does not exhaust. Air flows from the failed Roots blower through the exhaust pipe, rotor chamber to the suction line. Stop the Roots blower, the shut-off valve is closed, the other two Roots blower current value instantly increased from 40% to 80%, safety valve exhaust.

2, pneumatic lift pump damaged canvas layer, air chamber material

After the canvas is damaged, the raw material fed into the pneumatic lift pump can not be well vaporized, reducing the conveying capacity of the pump. When the feeding amount exceeds the conveying capacity of the pump, blocking occurs. 3 Roots blower fan current values ​​are about 80%, safety valve deflated.

Approach: no need to stop immediately replaced, usually wait until the shutdown and then replace the canvas. On-site treatment may not need to open the pump body manhole door to discharge material, just open the big raw material warehouse top bag dust removal exhaust fan inlet valve, and at the same time chooses to open 3 Roots blowers to pump the material in the body to the air.

3, incoming wet caking

Due to material factors leading to the airlift pump plugging material is mainly caused by moisture, especially wet end of the humidification tower blocking material, clear down the wet material into the pneumatic lift pump by the screw conveyor, can not be vaporized away. The control room showed 3 Roots blower current values ​​are about 40% of the no-load current, the safety valve does not deflate, but the feed chute is diffuse material, percussion pump body, sound dull.

Approach: Stop raw mill system, open the pump manhole, manual shoveling, clear canvas layer and then reboot.

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