From the answers above, it seems that it is possible to run without dip tubes. From personal experience, we had a premature failure on our IV stage dip tubes halfway through the year. After the failure we could not run the kiln at full production, we experienced a 10% loss in production and associated increase in heat consumption, without any noticeable increase in top stage exit temperature or a change in pressures across the tower. This leads me to think that it may be possible to run without dip tubes, depending on the type of cyclone you have (specifically what generation). We have a 4 stage preheater/precalciner kiln (Humboldt wedag) early 80's, reason why we probably have a harder time running without dip tubes.

Regards,