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Technical Cement Forum / Factors affecting poor collection efficiency of preheater cyclones

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Ramesh Aital 11/03/2018 05:44:58

Factors affecting poor collection efficiency of preheater cyclones

Recently we have upgraded plant capacity from 500 tpd to 850 tpd with the existing 5 stage preheater with separate line calciner. With the present set up we are able to feed 60 tph. Which is equal to 900 tpd. But we are getting only 600 tpd clinker and return dust to bag house is 25%.

The bottom 3 stage cyclones are HP cyclones and to 2 stage are LP cyclones. Pressure drop across the cyclones are as follows. Calciner to Cyclone 5 : 95 mm wg, Cycone 5 to 4 : 184 mm wg, Cyclone 4 to 3 : 185 mm wg, Cyclone 3 to 2 163 mm wg, Cyclone 2 to 1 is 40 mm wg.

Please any body share your ideas what are the coarse of actions we can take to increase collection efficiency of the cyclones.

Kumar 11/03/2018 07:41:00

Pl check the kiln feed residue, finer the material, lower the collection. Moreover check preheater outlet oxygen, is their any overdraft?

Ramesh Aital 28/03/2018 07:10:05

Kiln feed residue we are maintaining 2% on 212 and around 12% on 90 mic sieve.

As you said regarding finar particles affecting collection efficiency we also tried to increase the residue in 212 up to 4% and 14 to 16% on 90 mic. There is no considerable changes in the efficiency. Morever this is affecting the burning due to high residue in 212 mic.

The pressure drop across twin cyclone we are getting 40 to 60 mm wg. What could be the optimum pressure drop across twin cyclone. If it possible we may opt to increase immersion tube height little bit.

Cu Chulainn 26/04/2018 15:17:04

Dear Mr Ramesh,

It seems you have weird pressure loss values over cyclones. This indicates either measurement error (will assume not) or gas flow too high or wrong design.

dP of 5 St preheater usually (from bottom up) around 5,6,7,7,10 hPa (=mbar). The top stage separation efficiency is the responsible for high amounts of CKD.

I suggest investigate gas flow per ton clinker, usually 1,6 Nm3/kg cli. O2 about 5%. Temp 300 to 400 C. Pressure <100 hPa.

And reassess cyclone designs. Velocity in diptubes between 13 and 15 m/s. Velocity in inlets between 15 and 20 m/s.

Best regards,

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