课程名称︰质能平衡甲 课程性质︰必修 课程教师︰蔡伟博 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰2011/5/17 考试时限（分钟）：110 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.(15 points) To remove chloroform vapor from an exhaust stream using the process shown in the following figure. The process has been designed to recover 95% of the chloroform from air by compression. What is the exit pressure from the compressor? T Air+Chloroform vapor ┌─|X|─→ │ 1atm,26℃ Air 26℃, 1atm 26℃ │ ┌┐ Vapor+Liquid ┌─┐ ─────→││───────→│ │ mol fr. └┘ └─┘ ──── compressor ↑ Chloroform 0.018 ↓ Liquid chloroform Air 0.982 ──── 1.000 2.(20 points) The Weather Bureau reports a temperature of 30℃, a relative humidity of 85%, and a barometric pressure of 750 mmHg. (a)What is the molal humidity? (b)What is the humidity (weight basis)? (c)What is the saturation temperature or the dew point? (d)Determine the molal humidity and dew point if the air is heated to 40℃, the pressure remaining steady. (e)Determine the molal humidity and dew point if the air is heated to 15℃, the pressure remaining steady. (f)What fraction of the original water is condensed at 15℃? 3.(15 points) A local utility burns coal having the following composition on a dry basis. component percent C 83.05 O 3.36 N 1.08 S 0.7 Ash 7.36 ─── Total 100 The average Orsat analysis of the gas from the stack during a 24-hour test was component percent CO2+SO2 15.4 CO 0.0 O2 4.0 N2 80.6 ─── Total 100 Moisture in the fuel was 3.90%, and the air on the average contained 0.0042kg H2O/kg dry air. The refuse showed 15.0% unburned coal, with the remainder being ash. You are ask to check the consistency of the data before they are stored in a database. Is the consistency satisfactory? What was the average percent excess air used? 4.(15 points) The following figure is a schematic of a process for the production of flake NaOH. ↑W H2O │ G P 95% NaOH Filiter A○ ┌─────┐ 50 wt% ┌──────┐ Cake F─────→│evaporator│───→│Crystallizer│────→ 10000 lb/hr↑ └─────┘ NaOH │And Filter │ 5%(a 45 wt% 40 wt% NaOH│ R └──────┘ solution of NaOH └────────────────┘ Filtrate 45 wt% NaOH The fresh feed to the process is 10000 lb/hr of a 40% aqueous NaOH solution. The fresh feed is combined with the recycled filtrate from the crystallizer, and fed to the evaporator where water is removed to product a 50% NaOH solution, which in turn is fed to the crystallizer. The crystallizer produces a filter cake that is 95% NaOH crystals and 5% solution that itself consists of 45% NaOH. You are asked to determine the flow rate of water removed by the evaporator, and the recycle rate for this process. Assume that the product solution from the evaporator still contains 50% NaOH. 5.(20 points) Benzene(C6H6) is converted to cyclohexane(C6H12) by dtrect reaction with H2. The fresh feed to the process is 260L/min of C6H6 plus 950 L/min of H2 at 100℃ and 150kPa. The single pass conversion of H2 in the process is 75%. The recycle stream contains 90% H2 and the remainder benzene. See the following figure. (a) Determine the molar flow rate of H2, C6H6, and C6H12 in the exiting product. (b) Determine the volumetric flow rates of H2, C6H6, and C6H12 in the product stream if it exits at 100kPa and 200℃. (c) Determine the molar flow rate of the recycle stream, and the volumeetric flow rate if the recycle stream is at 100℃ and 100kPa. Feed(gas) Recycle gas stream,R At 100℃ 150kPa┌───────────┐ 260L/min C6H6 ↓ 90% H2, 10% C6H6 │ 950L/min H2┌────┐ ┌─────┐ P(gas) H2 ────→│Reactor │────→│Separator │───→ C6H6 └────┘ └─────┘ C6H12 6.(15 points) A gas is fllowing at a rate of 100,000 scmh (standard cubic meter per hour). What is the actual volumetric gas flow rate if 50atm and the temperature is 420K? The critical temperature is 15℃ and the critical pressure is 14.3atm. 7.(15 points) The following figure shows the process and the known data. You are asked to calculate the compositions of every flow stream, and fraction of the sugar in the cane that is recovered. M Sugar ↑ 1000 lb/hr│ ┌──────┐L Water F Cane │Crystallizer│───→ │16% Sugar └──────┘ │25% Water K ↑40% Sugar ↓59% Pulp │ ┌──┐ E ┌───┐ H ┌─────┐J Water │Mill│────→│Screen│──→│Evaporator│──→ └──┘ 13% Sugar└───┘ └─────┘ │ 14% Pulp │ ↓ ↓Solids G Contain D Bagasse 95% Pulp 80% Pulp 附: Compressibility chart constants of Antoine equation Properties of Saturated Water --

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