Heat balance stirred vessel

Two limiting modes of operating chemical reactors employ (a) a vessel so well stirred that the composition and temperature are the same throughout (b) a vessel typified by a tube without mixing in which all molecules have the same residence time, and in which gradients of composition and temperature exist. Material and heat balances on these devices utilize the conservation law,... 

A common process task involves heating a slurry by pumping it through a well-stirred tank. It is useful to know the temperature profile of the slurry in the agitated vessel. This information can be used to optimize the heat transfer process by performing simple sensitivity studies with the formulas presented below. Defining the inlet temperature of the slurry as T, and the temperature of the outer surface of the steam coil as U then by a macroscopic mass and energy balance for the system, a simplified calculation method is developed. 

Not shown in the flowsheet is a 60-gal, heated, stirred tank used to prepare and store feedstock. The feed flows from this mixing tank to the reed tank, which is an 8-L vessel. The liquid inventory in the feed tank was monitored with a differential pressure transmitter from which the liquid flow rate was determined. The feed tank holds enough liquid for one balance period up to 8 hr. 

Merzhanov et al. stated in the latter case that the heat transfer in molten tetryl was performed by convection only, because molten tetryl was stirred vigorously by means of a piston stirrer, so that, while the temperature distribution in molten tetryl was uniform, the temperature gradient was present only in the vessel wall [40]. On the other hand, the balance between the rate of heat generation in a liquid and the rate of heat transfer from the liquid to the atmosphere at the critical state for the thermal explosion which exists at the end of the early stages of the selfheating process, is dealt with in the approach adopted herein with regard to the thermal explosion of the liquid. The latter orthodox approach to the thermal explosion of every liquid has thus no concern with any convective flow in liquids. 

The main vessels used for weighing out solids in environmental analyses are weighing bottles, plastic weighing dishes or weighing boats. These containers are used to accurately weigh the solid, using a four-decimal-place balance, and to transfer a soluble solid directly into a volumetric flask. If the solid is not totally soluble it is advisable to transfer the solid to a beaker, add a suitable solvent, e.g. deionized or distilled water, and stir with a clean glass rod until all of the solid has dissolved. It may be necessary to heat the solution to achieve complete... 

---