BALANCE DE MATERIA PROCESOS SIN REACCIÓN QUIMICA

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9) A liquid mixture containing 45.0 wt% benzene (B) and 55.0% toluene (T) is fed to a distillation column operating at steady state. Product streams emerge from the top and bottom of the column. The top product stream contains 95.0 wt% B, and the bottom product stream contains 8% of the benzene fed to the column. The volumetric flow rate of the feed stream is 2000 liters/h and the specific gravity of the feed mixture is 0.872. Determine the mass flow rate of the overhead product stream and the mass flow rate and composition (mass fractions) of the bottom product stream. Suggestion: start using the approach: draw and label a flow chart, do a degree of freedom analysis, lay out a solution strategy, and then write equations and solve for the required quantities.

10) Strawberries contain about 15 wt% solids (assuming sugar) and 85 wt% water. To make strawberry jam, crushed strawberries and sugar are mixed in a 45:55 mass ratio, and the mixture is heated to evaporate water until the residue contains one-third water by mass.(a) Draw and label a flowchart of this process. (b) Do the degree-of-freedom analysis and show that the system has zero degrees of freedom. (c) Calculate how many pounds of strawberries are needed to make a pound of jam. (d) Repeat (a), (b) and (c), assuming the 15 wt% solids in the feed contain mainly orange fibers (not sugar as initially assumed)

11) A liquid adhesive, which is used to make laminated boards, consists of a polymer dissolved in a solvent. The amount of polymer in the solution has to be controlled for this application. When the supplier of the adhesive receives an order for 3000kg of an adhesive solution containing 13% by weight polymer, all it has on hand is (1) 500kg of a10% by weight solution, (2) a very large quantity of a 20 wt% solution, and (3) pure solvent. Calculate the weight of each of the three stocks that must be blended together to fill the order. Use all of the 10% by weight solution.

12) An evaporator is concentrating solutions coming from two different sources. The solutions from the first source containing 10% NaCl and 10% NaOH flows at the rate of 50 kg/min. The other solution containing 8% NaCl and 12% NaOH flows at the rate of 70kg/min. The two streams are fed directly to the evaporator. If 50% of the total water is to be evaporated, calculate the composition and the flow rate of the product.

13) The waste acid from a nitrating process contains 30% H2SO4, 35% HNO3 and 35% H2O by weight. The acid is to be concentrated to contain 39% H2SO4 and 42% HNO3 by addition of concentrated sulfuric acid containing 98% H2SO4 and concentrated nitric acid containing 72% HNO3 (wt). Calculate the quantities of 3 acids to be mixed to get 1000 kg of desired mixed acid.

14) A feed stock available at the rate of 1000 mol/h and consisting of (all in mol%) 20% propane (C3), 30% isobutane (i-C4), 20% isopentane (i-C5) and 30% n-pentane (nC5) is to be separated into two fractions by distillation. The distillate is to contain all the propane fed to the unit and 80% of the isopentane fed to the unit and is to consist of 40% isobutane. The bottoms stream is to contain all the normal pentane fed to the unit. Calculate the complete distillate and bottoms analysis.

15) The conventional method for separating ethyl alcohol from an alcohol/water mixture is by distillation. However, this procedure can at best only produce a product 95% by volume alcohol because alcohol and water form a constant boiling mixture, called an azeotrope, of that composition. Simple distillation cannot eliminate the azeotrope. Instead, if a pure alcohol product is desired, benzene is added to the feed solution. The benzene itself forms an azeotrope with water but one, which has a lower boiling point than the alcohol, and thus the alcohol can be purified. Suppose it is desired to produce 1000 lbm/h pure ethyl alcohol in this manner by distilling a feed mixture containing 60% water and 40% alcohol (in mass %). If the bottom stream contain only alcohol, and the distillate composition (in mass %) is 75% benzene and 24% water, with the rest alcohol, how much benzene must be fed to the column?

16) Una columna de destilación es alimentada por dos corrientes. Por la corriente de tope sale un 100% de compuesto A. Los componentes se separan tal y como se muestra en el diagrama de la figura. Calcular las corrientes desconocidas y la composición de la corriente M.

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