Abstract: In most industrial fiuidization units, two- or three-stage cyclone systems are used to
clean the product gases. To return the solids to the bed, these cyclones are fitted with
diplegs. By pass of gas from the bed through the dipleg is partially overcome by the back
pressure build-up in the dipleg and by adding a trickle valve at the bottom of the dipleg.
Diplegs of primary cyclones, operating at a high solid loading behave differently from
diplegs of secondary and tertiary cyclones which operate at low solid loading. Both types
have been investigated by pressure drop measurements, visual observation and by
measurements of the air flow rate flowing up the riser. The primary dipleg was also studied
using electrical capacitance tomography. The results are reported hereafter and will give a
first indication towards the right design of the dipleg and the selection of the trickle
valve. The influence of gas flow in the dipleg on the conversion in a catalytic fluidized
bed reactor is found to be negligible.

Key words: cyclone dipleg, fluidized bed, physical model

摘要： In most industrial fiuidization units, two- or three-stage cyclone systems are used to
clean the product gases. To return the solids to the bed, these cyclones are fitted with
diplegs. By pass of gas from the bed through the dipleg is partially overcome by the back
pressure build-up in the dipleg and by adding a trickle valve at the bottom of the dipleg.
Diplegs of primary cyclones, operating at a high solid loading behave differently from
diplegs of secondary and tertiary cyclones which operate at low solid loading. Both types
have been investigated by pressure drop measurements, visual observation and by
measurements of the air flow rate flowing up the riser. The primary dipleg was also studied
using electrical capacitance tomography. The results are reported hereafter and will give a
first indication towards the right design of the dipleg and the selection of the trickle
valve. The influence of gas flow in the dipleg on the conversion in a catalytic fluidized
bed reactor is found to be negligible.

关键词: cyclone dipleg;fluidized bed;physical model