My tank has been batch transferred with mogas components and has a couple of streams entering through the blender as well. Mogas components can have density difference of 0.55 to 0.78 SG. The tank was mixed for 18 hours. Based on calculation, the mixer's horsepower is not adequate. Thus, we have recommended to take three samples (upper, middle and lower part) of the tank to check for homogeneity after mixing. However, we realize after sending to the ship, there was a density difference from the tank. After checking back the tank contains only residual contents, we realize the density is much lower than expected. Questions: 1) After mixing the tank, will the light components be able to settle out if the tank sits for one day? 2) How much will be settled out? Is there a formula/simulation to find out?
Topic: Will light components be able to settle out if the tank sits?17 July 2012 Last edited: 17 July 2012 At 11:02am
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Dave Dickey Forum Moderator 287 Posts
Re: Will light components be able to settle out if the tank sits?17 July 2012 at 11:02am Last edited: 17 July 2012 at 11:02amUnless the mogas components are immiscible (which I doubt), once blended they will not separate. The different density components become a single fluid with approximately a weighted average density. If the mixer size is not adequate, the most likely answer to both of your questions is that the tank contents were never blended. Two layers of different density liquid may tank longer than 18 hours to blend with out sufficient mixing intensity. Blending layers of different density can be difficult. The best solution to avoid future problems is to add the denser fluid on top of the lower density liquid, or add either fluid near the mixing impeller. You want to avoid layers of different density liquid. 1) The lighter or denser components should not separate if the tank is well mixed, no matter how long they sit. 2) I do not know of any calculation, formula or simulation, that will predict separation, even for immiscible fluids. The answers by this expert are based on the best available interpretation of the information provided. The consequences of the application of this information are the responsibility of the user. If clarification is needed, please submit a further question.