Water and Kg 0c
MATERIAL AND ENERGY BALANCE
We produce acetaldehyde by dehydrogenation of ethanol. Flow chart is as shown in the figure. Reaction: C2H5OH Catalyst:
Æ
CH3CHO +
H2
Cu -Co-Cr2o3
Temperature: 280 – 3500 C.
Process description: The raw material i.e., ethanol is vaporized and the vapors, so generated, are heated in a heat exchanger to the reaction temperature by hot product stream. The product stream is cooled to –100 C and in doing it, all unreacted ethanol and acetaldehyde are condensed. The out going gaseous stream, containing hydrogen mainly, is scrubbed with dilute alcohol (alcohol + water) to remove uncondensed products and the undissolved gas. The remaining pure hydrogen (98%) is burnt in stack. The material and energy balance in a plant design is necessary because this fixes the relative flow rates of different flow streams and temperatures in the flow sheet.
Notations used: Msteam = Mass flow rate of steam.
N
+steam
= enthalpy of steam.
E = Mass flow rate of ethanol. A = Mass flow rate of acetaldehyde. H = Mass flow rate of hydrogen. Cp = specific heat capacity.
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Basis: One hour of operation. Amount of acetaldehyde to be produced = 150 TPD = 6250kg/hr. Molecular weight of ethanol = 46 kg/kmol. Molecular weight of acetaldehyde = 44 kg/kmol.
Molecular weight of hydrogen = 2 kg/kmol. Therefore, amount of acetaldehyde to be produced = 142.04 kmol/hr. Let conversion be 94%. Taking into account the losses let, the acetaldehyde produced to be some extra. Let acetaldehyde to be produced = 6500 kg/hr. Amount of ethanol required for 100% conversion = 6795.45 kg/hr. Therefore, ethanol required for 94% conversion = 7229.2 kg/hr.
Vaporizer:
1000 C, super heated stream of ethanol
Steam (Heating fluid)
Condensed steam 300 C, ethanol As shown in the figure, Ethanol liquid inlet temperature = Ti=300 C. Ethanol leaves as superheated steam at 1000 C = To Heating fluid is assumed to be saturated
We produce acetaldehyde by dehydrogenation of ethanol. Flow chart is as shown in the figure. Reaction: C2H5OH Catalyst:
Æ
CH3CHO +
H2
Cu -Co-Cr2o3
Temperature: 280 – 3500 C.
Process description: The raw material i.e., ethanol is vaporized and the vapors, so generated, are heated in a heat exchanger to the reaction temperature by hot product stream. The product stream is cooled to –100 C and in doing it, all unreacted ethanol and acetaldehyde are condensed. The out going gaseous stream, containing hydrogen mainly, is scrubbed with dilute alcohol (alcohol + water) to remove uncondensed products and the undissolved gas. The remaining pure hydrogen (98%) is burnt in stack. The material and energy balance in a plant design is necessary because this fixes the relative flow rates of different flow streams and temperatures in the flow sheet.
Notations used: Msteam = Mass flow rate of steam.
N
+steam
= enthalpy of steam.
E = Mass flow rate of ethanol. A = Mass flow rate of acetaldehyde. H = Mass flow rate of hydrogen. Cp = specific heat capacity.
/DWHQW KHDW RI YDSRUL]DWLRQ
Basis: One hour of operation. Amount of acetaldehyde to be produced = 150 TPD = 6250kg/hr. Molecular weight of ethanol = 46 kg/kmol. Molecular weight of acetaldehyde = 44 kg/kmol.
Molecular weight of hydrogen = 2 kg/kmol. Therefore, amount of acetaldehyde to be produced = 142.04 kmol/hr. Let conversion be 94%. Taking into account the losses let, the acetaldehyde produced to be some extra. Let acetaldehyde to be produced = 6500 kg/hr. Amount of ethanol required for 100% conversion = 6795.45 kg/hr. Therefore, ethanol required for 94% conversion = 7229.2 kg/hr.
Vaporizer:
1000 C, super heated stream of ethanol
Steam (Heating fluid)
Condensed steam 300 C, ethanol As shown in the figure, Ethanol liquid inlet temperature = Ti=300 C. Ethanol leaves as superheated steam at 1000 C = To Heating fluid is assumed to be saturated