Relationship between air velocity and residence time
Thread Content
Generally speaking, space velocity and residence time are inversely related. I had some arguments with my colleagues today; I’m curious to know how the more experienced among you view this What is the specific meaning?
Yeah, that’s right! So how should that be understood?
Let me share my understanding; I didn’t do very well in college either. First of all, it certainly isn’t an inverse relationship; I would say there is a negative correlation, to be more precise, a negative correlation between volume space velocity and average residence time. For continuously operating batch reactors, the residence time follows a distribution curve; the instantaneous residence time is not necessarily equal to the average residence time. It may be very short, as in the case of plug flow. Even when it comes to the average residence time, this can be quite long due to phenomena such as mixed flow and turbulence. Space velocity, on the other hand, refers to the amount of gas processed per unit volume of catalyst per unit time. In other words, the material may already have come into contact with the catalyst, but due to non-ideal flow conditions, the catalyst remains inside the reactor. Don’t these two concepts then have no connection? Personal opinion, not academic: P
For a fixed-bed batch reactor, the space velocity = volume flow rate/catalyst volume, and its unit is S-1; therefore, it is correct to say that it is inversely related to the residence time. This is just my humble opinion, and I welcome discussions and corrections
For a fixed-bed batch reactor, the space velocity = physical volumetric flow rate/catalyst bed volume, with the unit of S-1; therefore it is the reciprocal of the residence time