Page 31 - dust collection systems

effectively cleaned, and a reduction in cleaning efficiency
must be expected if very long bags are used.

The phenomenal growth of the Cement Industry has seen the

advent of plants of much bigger size. The traditional pulse jet

filters have been found to be inadequate to handle large gas

flows due to severe limitations on aspects like high space

requirement and high compressed air consumption. To

overcome this, in the advanced cleaning system, pulse jet

filters use low-pressure high-volume air with long bag.

If of sufficient energy (low-pressure x high-volume) to

reverse the forward air flow through the bag and expand the

bag along its entire length, venturi less advanced cleaning

system cleans the bag adequately. The idea behind the

introduction of the venturi in the traditional pulse jet bag

filter is to use the injected air pulse to form a region of

greatly reduced pressure in the venturi throat, thereby

aspirating a large quantity of cleaned gas from the outlet

plenum to supplement the directly injected cleaning pulse.

The venturi thus acts as a jet pump to more efficiently create

a cleaning shock wave. However, the importance of the

venturis is debatable.

. In case of traditional pulse jet system, as pulse is injected

through venturi nozzle, aspirating secondary air flow is 6-7
times greater than the primary air flow. However, in case of