could you please help me out to do this Homework? It is chemistry homework. Your
ID: 878709 • Letter: C
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could you please help me out to do this Homework? It is chemistry homework. Your team is about to install a heat exchanger to preheat the acetone fed to a reactor. The acetone will entering the preheater will be at 60 to 70 °C and a pressure of 1.0 atm, and it will leave the preheater at 225 °C. Under normal operating conditions, the flow rate ofacetone through the preheater will be between 5000 and 6000 SLPM (standard liters per minute). Your plant has utility steam available at 40 bar absolute pressure (saturated steam); you plan to return the condensate from your heat exchanger as a liquid at 150 °C and 40 bar. Write a message to the superintendent of utilities at your plant to make her aware of the anticipated steam usage for the new heat exchanger. You should write about your calculations. Not the key operating parameters that determine steam usage, so that if those operating parameters change in the future, engineers will be alerted to the anticipated change in utility needs. Note assumptions that you madeExplanation / Answer
1gmoles of any gas at STP occupies 22.4 liters
Maximum flow rate is 6000 liters/ min which is 60000/22.4 moles/ min =267.85 gmoles/m
1 mole correspnds to 56 gms of acetone
267.85 gmoles corresponds to =15000 gm/min = 15 kg./min
Acetone boiling point is 56 Deg.c and 1 atm pressure, at 60 Deg.C acetone remain as vapor.
Let us assume that it enters at 60 Deg.c ( This gives maximu duty of heat exchanger)
and leaves at 225 Deg.C
Specific heat of acetone= 1.47 Kj/Kg.K
Amount of heat to be supplied = masss * Specific heat of acetone vapor * Temperature difference =
= 15*1.47(225-60) Kj/min=3638.25 Kj/Min
From steam tables, the latent heat of vaporization of steam ( correspinding to a saturation temperature of 250 deg.C) = 2800 Kj/Kg
Liquid water leaves at 150 Deg.C and hence, sensible heat = mas of water * specific heat * (250-150)
m*4.18 *( 250-150)= 418m ( m =mass flow rate of water )
Latent heat =2800m
Total heat = 2800m+ 418 m =3218m = 3638.25 Kj/Min
m= 3638.25/ 3218 =1.13 Kg/min = 67.8 kg/hr
The latent heat is much higher than sensible heat and hence only latent heat will be considered for arriving at a conservative value of Water flow rate
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