Any number of ways:

• Air blast from a pneumatic line and a nozzle close to it
• Hit it on the outside by some sort of automatic remote hammering device
• Teflon coating on the affected part
• Reduce the moisture content of the powder
• Fluidise the contents during discharge
• Etc.

Does the ring include stiff brushes that press against the cylinder wall? If not, I'd fabricate a collar of brushes and attach this 'collar around the ring'. Perhaps that would clean up your detergent problem.

_{/Yeah, I know; I'm reverse-channeling an old Whisk commercial. Why is that useless bit of info is still stored in my noggin', yet sometimes I'll go blank on a person's name?}

Thanks for your kind reply we already have a steel sheets assembeled on the collar this sheet has cut and bended every 20cm to make the scratches to clean up

can you send me photos of your bruches may be it is mor effecient than ours

Check these:

http://www.tankjet.com/?gclid=CMz42pbK8q8CFWQKRQodeCvMXA

http://www.icsindustrialservices.co.uk/cip-tank-cleaning-equipment/

http://www.spray.co.za/tank-cleaning.php

and many more...