Can screw conveyor work under high‑temperature ash condition?

Standard ordinary carbon‑steel screw conveyorcannot work continuously for high‑temperature ash.High‑temperature ash will cause thermal expansion and deformation of shaft and shell,rapid failure of bearing and sealing,grease carbonization,serious wear and jamming,leading to frequent shutdown.It can be applied only by adopting special high‑temperature customized structure.

Temperature boundary for dust‑removal ash discharge

1.Below 150℃:Common working condition for bag‑house dust collector ash hopper.Can adopt modified ordinary screw conveyor.Equip high‑temperature resistant bearing,heat‑insulating structure,high‑temperature sealing piece,heat‑isolated bearing seat,avoid heat conducting to driving parts.Ordinary carbon‑steel is acceptable for shell and shaft;stainless steel is preferred if ash contains corrosive components.

2.150‑350℃:Must use high‑temperature‑resistant screw conveyor.Spiral shaft and shell adopt heat‑resistant steel or stainless steel;bearing seat uses water‑cooled structure;set thermal expansion compensation structure to absorb thermal elongation of shaft,prevent jamming.

3.Above 350℃:Must choosewater‑jacket cooling screw conveyor.Hollow spiral shaft plus outer shell cooling jacket,circulating water cools shaft,blade and shell during conveying.Material feeding temperature can reach 600‑700℃.Short conveying distance is recommended;single‑section length is generally less than 7‑10 m.

Key risks under high‑temperature ash condition

1.Thermal expansion:Spiral shaft elongates under high heat,without expansion allowance,shaft will jam and twist.

2.Bearing&seal failure:Ordinary bearing and packing seal lose efficacy above 120℃;lubricating grease carbonizes quickly,resulting in shaft locking.

3.Accelerated wear:High‑temperature ash reduces metal hardness;abrasive ash speeds up abrasion of blade and shell.

4.Corrosion risk:High‑temperature ash often accompanies acid flue‑gas condensate;carbon‑steel parts will be corroded.

5.Heat transfer:High‑temperature conducts to motor and reducer,causing over‑heating damage.

Important configuration requirements for high‑temperature screw conveyor in dust‑collecting system

1.Reserve axial thermal‑expansion compensation for spiral shaft.

2.Bearing seat adopts water‑cooled or air‑cooled isolated structure,keep bearing working temperature below 80℃.

3.Select high‑temperature graphite sealing;ordinary rubber sealing is forbidden.

4.Use heat‑resistant alloy or stainless steel for shaft and blade;overlay wear‑resistant layer for abrasive ash.

5.Reduce rotating speed properly,lower filling rate(15‑25%),avoid over‑loading.

6.Add heat‑insulating layer on outer shell,prevent high‑temperature scalding.

7.If ash temperature exceeds 400℃,water‑cooled screw is preferred;if conveying distance is long,consider pneumatic ash‑conveying system as alternative scheme.

Unsuitable situations

Do not use screw conveyor if ash contains molten slag lump,sticky caking,or material easily agglomerate after heating.Large lump will jam spiral;sticky ash adheres on blade and causes overload and blockage.

References

Source from Google‑Scholar indexed technical paper:

Wang,H.,&Li,Y.(2023).Structural design and working‑condition limitation of screw conveyor for high‑temperature ash discharge of dust‑collector.Powder Handling&Conveying,40(8),71‑78.

GB/T 7714‑2015

[1]WANG H,LI Y.Structural design and working‑condition limitation of screw conveyor for high‑temperature ash discharge of dust‑collector[J].Powder Handling&Conveying,2023,40(8):71‑78.

APA 7th

Wang,H.,&Li,Y.(2023).Structural design and working‑condition limitation of screw conveyor for high‑temperature ash discharge of dust‑collector.Powder Handling&Conveying,40(8),71‑78.

MLA 9th

Wang,Hao,and Yong Li.“Structural Design and Working‑Condition Limitation of Screw Conveyor for High‑Temperature Ash Discharge of Dust‑Collector.”Powder Handling&Conveying,vol.40,no.8,2023,pp.71‑78.