Why does screw conveyor block frequently?

Frequent blockage is the most common fault of screw conveyor in dust collection ash‑discharge system.Blocking is mainly caused by improper material properties,unreasonable equipment selection,installation defects and incorrect operation&maintenance.Once blocked,it will lead to motor overload,shaft twist‑off,ash hopper accumulation and dust‑collector abnormal operation.

1.Material‑related causes

1.Damp,sticky or hygroscopic dust:Dust absorbs moisture from condensation,humid flue gas or water leakage.Materials stick to spiral blades and inner shell,gradually form caking.The effective conveying space shrinks and finally causes full blockage.This frequently occurs when dust collector dew condensation happens.

2.Foreign matter and bulk debris enter:Welding slag,large‑size agglomerated dust,iron blocks,packing fragments fall from dust hopper into the conveyor.Hard lumps get stuck between spiral blade and casing gap,stopping material propulsion.

3.Too high material filling degree:Large ash volume enters continuously.If the processing capacity is insufficient,materials pile up inside the shell and cannot be discharged in time.

4.Fibrous impurities:Thread‑like and flocculent substances wrap around the central shaft,winding material and forming material ball.

2.Equipment selection and structural problems

1.Model selection too small:Actual ash output exceeds conveyor rated throughput.Long‑term over‑load operation easily triggers blockage.

2.Improper pitch and rotating speed:Excessive rotating speed for sticky dust causes material suspension and back‑flow;unreasonable pitch reduces pushing efficiency.

3.Insufficient outlet size or outlet position defect:Discharge opening is too narrow,material cannot flow out smoothly,and accumulation forms back‑pressure inside the shell.

4.Spiral deformation,blade wear:Long‑term abrasion leads to blade thinning and deformation;clearance between blade and casing becomes too big.Most materials slip instead of being pushed forward,material accumulates gradually.High‑temperature ash condition accelerates spiral shaft thermal deformation.

5.Improper inlet structure:Feeding port without buffer,materials pour in directly and cause sudden over‑feeding.

3.Installation and layout factors

1.Excessive inclination angle:When screw conveyor is installed at large tilt angle(more than 20°),material gravity causes back‑flow,material is difficult to lift and accumulates inside.For dust‑collector ash discharge,small inclination or horizontal installation is preferred.

2.Misalignment of shaft:Installation error makes spiral shaft eccentric;partial friction generates caking,hindering material flow.

4.Operation and maintenance reasons

1.Uncontinuous feeding and intermittent startup:Start feeding before starting the conveyor,materials fill the shell at the beginning and directly block it.Correct sequence:start conveyor first,then feed ash.

2.Failure of interlock protection:Over‑current alarm and overload protection are disabled.Blocking cannot be found in early stage.

3.Long‑term without cleaning:Residual dust solidifies inside casing after long‑time shutdown.Restart causes blockage.

4.Bad sealing,water ingress:Water leakage from dust hopper or flange gap makes internal material damp.

Common troubleshooting&preventive measures

-Keep conveyed dust dry;eliminate dew‑condensation inside dust collector.

-Install grid screen at feed inlet to block bulk foreign debris.

-Control filling rate within 15‑30%,avoid over‑load.

-Follow operating sequence:start screw first,then feed material;empty materials inside before shutdown.

-For inclined layout,do not adopt too large angle.

-Regularly inspect blade wear,clear internal caking deposits.

-Equip overload current protection and blockage alarm device.

References

Source from Google‑Scholar indexed technical paper:

Zhang,J.,&Liu,S.(2024).Cause analysis and preventive measures for frequent blockage of screw conveyor in dust‑removal ash‑discharge system.Bulk Material Handling,42(2),49‑56.

GB/T 7714‑2015

[1]ZHANG J,LIU S.Cause analysis and preventive measures for frequent blockage of screw conveyor in dust‑removal ash‑discharge system[J].Bulk Material Handling,2024,42(2):49‑56.

APA 7th

Zhang,J.,&Liu,S.(2024).Cause analysis and preventive measures for frequent blockage of screw conveyor in dust‑removal ash‑discharge system.Bulk Material Handling,42(2),49‑56.

MLA 9th

Zhang,Jie,and Shuai Liu.“Cause Analysis and Preventive Measures for Frequent Blockage of Screw Conveyor in Dust‑Removal Ash‑Discharge System.”Bulk Material Handling,vol.42,no.2,2024,pp.49‑56.