Planta producción de acetona

Energy Balances, Numerical Methods Design Project Production of Acetone Process Description
Figure 1 is a preliminary process flow diagram (PFD) for the acetone production process. The raw material is isopropanol. The isopropanol (IPA) feed is a near azeotropic mixture with water at 88 wt % IPA at 25°C and 1 atm. The feed is heated, vaporized, and superheated in a heat exchanger (E-401), and itis then sent to the reactor (R-401) in which acetone is formed. The reaction that occurs is shown below. The reactor effluent is cooled and partially condensed in a heat exchanger (E-402), and it is then sent to a separation unit (V-401) in which all of the light gas (hydrogen) enters Stream 7 while the remaining components (acetone, IPA, and water) distribute according to Raoult’s Law. Some ofthe acetone in Stream 7 is recovered by absorbing it into pure water in T-401. The liquid in Stream 12 is distilled to produce “pure” acetone in Stream 13 and waste water (containing IPA) in Stream 14. The desired acetone production rate is 15,000 metric tons/yr.

Process Details
Feed Streams Stream 1: Stream 9: Effluent Streams Stream 11: Stream 13: off-gas stream to incinerator, credit may betaken for LHV of fuel acetone product, liquid, 99.9 mol% purity, must contain 99.5 mol% of acetone in Stream 12 waste water stream, treatment cost $50.00/106 kg must contain less than 0.04 mole fraction IPA and acetone isopropyl alcohol, liquid, 88 wt % IPA, 12 wt % water, 1 atm, 25°C distilled process water, 3 bar, 25°C

Stream 14:

3 Equipment Heat Exchanger (E-401): This unit heats,vaporizes, and superheats the feed to 235°C at 2.2 bar. A pump, which is not shown and which you do not have to be concerned with this semester, increases the pressure of the feed to the indicated pressure. Reactor (R-401): Following development of a new catalyst, only the following reaction occurs: CH 3CHOHCH 3 → CH 3COCH 3 + H 2 IPA acetone (1)

The reaction occurs at 350°C, and the conversion atthis temperature is 90%. The reactor exit pressure is 1.9 bar. The reaction is endothermic with heat being supplied by hot molten salt. Fired Heater (H-401): This unit heats the molten salt that provides heat to the reactor. Energy is supplied by combustion of natural gas, which may be assumed to be pure methane. The molten salt enters the fired heater at 360°C (Stream 3) and leaves the fired heaterat 410°C (Stream 4). The heat capacity of molten salt is 1.56 J/g K. Heat Exchanger (E-402): This unit cools and partially condenses the reactor effluent. None of the hydrogen condenses. The exit pressure may be at any pressure below 1.6 bar and any temperature below 50°C that can be achieved by using cooling water (cw) or refrigerated water (rw) is possible. Separation Vessel (V-401): This unitdisengages the vapor and liquid effluent from E-402. In this separator, all hydrogen in the feed enters the vapor phase, Stream 7. All other components distribute according to Raoult’s Law at the temperature and pressure of E-402. The combination of E-402 and V-401 is often called a flash operation. Absorber (T-401): Here, additional acetone is recovered by absorption into pure process water. Theabsorber operates at the same temperature and pressure as V-401 Stream 11 contains all of the hydrogen and the acetone and water which are not in Stream 10. Stream 10

4 contains all of the IPA in Stream 7, 95% of the water in Streams 7 and 9. The amount of acetone in Stream 10 can be calculated from: y stream 11 ystream 7 where y is the mole fraction of acetone, A= L mV (3) = 1− A 1 − A6 (2)L is the total molar flowrate of liquid in Stream 9, and V is the total molar flowrate of liquid in Stream 7. The parameter m is an equilibrium constant that is a function of temperature and pressure 3598   exp10.92 −  T   m= P where T is in Kelvin and P is in atm. Distillation Column (T-402): In this distillation column, the acetone, IPA, and water in Stream 12 are separated. The column...