PNNL

Abstract

Scaled tests were conducted to develop correlations describing pulse jet mixer (PJM) performance with non-cohesive solids in water. These correlations were developed in scaled test systems that incorporated certain simplified aspects including non-prototypic refill associated with closed-loop operation of the mixing jets. When this test data was compared with experiments that used prototypic PJM refill, a difference in the critical suspension velocity (UCS) was identified. The non-prototypic aspects of the initial testing were reviewed and assessed. The effects of non-prototypic refill associated with the closed loop operation of the jets, previously known to affect solids cloud height, can be described in terms of a modified settling velocity. When the modified settling velocity is incorporated into the physical model, the adjusted new physical model does a better job of predicting UCS results for prototypic PJM refill tests. The adjusted new physical model was bench-marked with data taken during three prototypic drive tests with a mono-disperse simulant, a 3-part medium distribution stimulant and a 5-part broad distribution simulant The applicability of the non-prototypic scale-up behavior to prototypic testing was analyzed. The effects of non-prototypic refill caused measured values of UCS to be somewhat reduced at larger scales. Hence the scale-up exponents for the non-prototypic drive tests are believed to be smaller than they would have been had there been prototypic refill. Estimated scale-up exponents for the prototypic testing were developed for 8 and 12 pulse tube configurations.