Calculation of Liquid Level Difference

2 Calculation of the Liquid Level Difference between the Front and Back Cyclones 

Substituting these values into Eq. 13.B.11, we obtain a pressure difference between the back and front cyclones of about -0.224 kPa (about -23 mm or -1 inch of water column). Since this pressure differential (back - front) is negative, the liquid level in the two back cyclones will be 23 mm of water column higher than that for the two front cyclones. The level in the two middle cyclones can be expected to lie between that of the front and back cyclones. 

Before closing this discussion we wish to call attention to the fact that the liquid seal at the bottom of each cyclone causes their performance to be rather unaffected by flow imbalances of the type we just observed. This would not be the case had the cyclone underflows not been isolated from one another. In this case, any pressme imbalance that would exist between the cyclone underflows will cause gas to flow down some of the underflow openings and up other underflow openings. This, in turn can lead to a serious degradation of separation performance and is the reason why most multiclone systems do not perform as well as one of its individual cyclones tested in isolation. 

When faced with a cyclone performance problem it is almost always advisable to focus attention on the underflow configuration. The majority of performance problems are due, for one reason or the other, to the inability of particulates to properly discharge out the underflow openings. 

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