What are the reasons why the rotary airlock valve is stuck and locked?

The star unloader,also known as rotary airlock valve,is essential feeding and discharging equipment for dust removal,metallurgy,building materials and chemical industries.During continuous operation,jamming and mechanical locking failures frequently occur,which lead to equipment shutdown,motor burning,gear damage and production interruption.The main reasons for shaft locking,rotor jamming and mechanical seizure are analyzed as follows.

Main Causes of Jamming and Locking

Hard foreign matters mixed in materials

Large impurities such as iron blocks,welding slag,stones,wire scraps and hard particles enter the unloader body,which are clamped between the rotor blades and the shell.It directly causes the rotor to be stuck and cannot rotate,resulting in serious locking failure.

Material moisture and caking blockage

The conveyed powder material contains high moisture,resulting in agglomeration,hard bonding and wall sticking.The viscous materials accumulate and solidify inside the shell,wrapping the rotor blades and causing mechanical seizure.

Excessive feeding amount

Uncontrolled excessive feeding causes material accumulation inside the unloader cavity.Overload stacking leads to increased rotational resistance,overload operation of the motor,and finally shaft locking and dead clamping.

Severe wear of internal parts and clearance reduction

Long-term operation causes wear of rotor blades,end face and inner wall of the shell.The matching clearance between rotating parts decreases sharply.Thermal expansion at high temperature further reduces the gap,resulting in friction locking and rotation failure.

Lack of lubrication and bearing failure

The bearing of main shaft is short of lubricating oil,dry grinding,rusting,aging or damage.Bearing internal clamping causes inflexible rotation,and gradually leads to complete locking of the whole machine.

Shaft seal winding and winding blockage

Fiber materials,fine dust and thread impurities wind around the main shaft and sealing position continuously.The winding layer thickens gradually and hinders rotor rotation,resulting in jamming failure.

Motor overload and reducer failure

Aging damage of reducer gear,broken key connection,and motor overload protection failure will also cause the equipment to stop rotating and present a locked state.

Troubleshooting Methods

Clean hard impurities and blocked accumulated materials inside the unloader cavity completely.

Control material moisture,avoid wet and viscous materials entering the equipment.

Adjust stable feeding quantity to prevent overload operation.

Check and replace severely worn rotor and shell parts,and maintain reasonable matching clearance.

Regularly lubricate main shaft bearings and replace damaged bearings in time.

Remove winding impurities at shaft seal position and optimize feeding filtering device.

Inspect reducer and motor system,repair transmission structure faults.

References

1.GB/T 7714

Zhao L,Wang Y.Failure Analysis and Treatment of Rotor Jamming of Star Unloader[J].Environmental Machinery,2022,54(2):97-101.

2.MLA

Zhao,Lei,and Yu Wang."Failure Analysis and Treatment of Rotor Jamming of Star Unloader."Environmental Machinery,vol.54,no.2,2022,pp.97-101.

3.APA

Zhao,L.,&Wang,Y.(2022).Failure analysis and treatment of rotor jamming of star unloader.Environmental Machinery,54(2),97-101.