the flow rates of all streams in kmol/h · pdf file1 plant design: acetone the flow rates of...

1

Plant Design: Acetone

The flow rates of all streams in Kmol/h

Table 1:Calculated mol of substances

Figure 1: Aceton Production from IPA

Streams Acetone Isopropyl Alcohol Water Hydrogen

1 - 90.926 32.571 -

2 - 100 37.04 -

3 - 100 37.04 -

4 - 100 37.04 -

5 90 10 37.04 90

6 90 10 37.04 90

7 90 10 37.04 90

8 24.366 0.784 2.82 90

9 66.134 9.2 34.16 -

10 24.342 0.784 603.37 -

11 - - 600.554 -

12 0.024366 - - 90

13 90.477 9.987 637.53 -

14 90.387 0.9129 - -

15 0.0905 9.074 637.53 -

16 - - 633.061 -

17 0.0905 9.074 4.469 -

2


Production:

115000 ton/year

115000𝑡𝑜𝑛

𝑦𝑒𝑎𝑟×

1𝑦𝑒𝑎𝑟

11𝑚𝑜𝑛𝑡ℎ×

1𝑚𝑜𝑛𝑡ℎ

30𝑑𝑎𝑦𝑠×

1𝑑𝑎𝑦

24ℎ𝑜𝑢𝑟𝑠×

1ℎ𝑜𝑢𝑟

60𝑚𝑖𝑛𝑠×

1𝑚𝑖𝑛𝑠

60𝑠𝑒𝑐𝑜𝑛𝑑𝑠×

1000𝑘𝑔

1𝑡𝑜𝑛

×1000𝑔

1𝑘𝑔×

1𝑚𝑜𝑙

58𝑔𝑟𝑎𝑚𝑠= 6.67 𝑚𝑜𝑙/ sec

Production rate=6.67 mol/sec

Reactor:

Figure 2: Reactor column

Based on the available information, the weight percent in the reactor

should be 90% therefore; we can apply weight percent formula in order

to get the weight of water since we have remaining unknown

parameters.

Weight percent = weight of solute weight of solution

x 100%

0.90= (weight of IPA)/ (weight of IPA+ weight of water)

3


0.90= (100*60)/ (100*60+weight of water)

Weight of water = ( 6000/0.90)-6000

= 666.66 kg/hr

Since we have calculated the weight of water, we can get know the

number of mole of water entering the reactor:

Nwater,in= mwater/Mrwater

= (666.67/18)

= 37.04 Kmol/hr

At T=350C, conversion=90% so we can get Ntotal leaving the reactor:

Naceton,out=100*0.9=90 kgmol/hr

Nhydrogen,out=100*0.9=90 kgmol/hr

Nwater,out=37.04kgmol/hr

NIPA,out=100*10=10kgmol/hr

Ntotal,out= Naceton,out+ Nhydrogen,out+ Nwater,out+ NIPA,out

Ntotal,out=90+37.04+10+90=227.04Kgmol/hr

To check, the summation of mole fraction should be equal to 1:

Yaceton= Naceton/Ntotal = 90/227.04 = 0.396406

Yhydrogen= Nhydrogen/Ntotal =90/227.04= 0.396406

Ywater= Nwater/Ntotal = 37.04/227.04= 0.16314

YIAP= NIAP/Ntotal =10/227.04= 0.044045

∑ 𝑦𝑖 = 1

Yaceton+ Yhydrogen+ Ywater+ YIAP=1

0.396406+0.396406+0.16314+0.044045=1

Nin=Nout

4


Nwater,in+ NIPA,in= Nwater,out+ NIPA,out+ Naceton,out+ Nhydrogen,out

6000 kg/hr +666.72 kg/hr =666.72 kg/hr +600 kg/hr +5220 kg/hr +180

kg/hr

6666.72kg/hr=6666.72 kg/hr

So, the material balance around the reactor is justified.

Flash Unit:

Figure 3: Flash Unit

It is assumed that there is no change in temperature and pressure.

Ki=Pi*/PTotal =yi=xi at bubble point (T=81C)

The partial pressure for Aceton, 2-Propanol and water is calculated using the following

formula :

Where, Ptotal= 1125.092

The interpolation should be used to get the A, B and C at temperature of 81C

5


For Acetone:

(205-70)/(81-70)=( 7.6313- 7.1327)/(XA-7.1327) (205-70)/(81-70)=( 1566.69- 1219.97)/(XB- 1219.97)

(205-70)/(81-70 )=(273.419-230.653)/(XC- 230.653)

For 2-Propanol (C3H8O)

83-10/81-10) = (7.9584-8.00308)/(XA-8.00308) )

(83-10/81-10) = (1519.66-1505.52)/(XB-1505.52)

(83-10/81-10) =(216.829-211.6)/(XC-211.6)

Antoine Equation Parameters (P in mmHg, T in °C)

No. A B C Tmin [°C] Tmax [°C]

1 8.07131 1730.63 233.426 1 100

2 8.14019 1810.94 244.485 99 374

(99 -1)/(81-1)= (8.14019- 8.07131)/(XA- 8.07131)

(99 -1)/(81-1)= ( 1810.94- 1730.63)/(XB- 1730.63)

(99 -1)/(81-1)= ( 244.485- 233.426)/(XC- 233.426)

From the interpolation,the partial pressure for Aceton, 2-Propanol and water at the

bubble point T= 81C is calculated. According to Antoine equation, the K is calculated

using (the partial pressure/ the total pressure).



1 7.1327 1219.97 230.653 -64 70

2 7.6313 1566.69 273.419 57 205



1 8.00308 1505.52 211.6 10 90

2 7.9584 1519.66 216.829 83 205

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For Acetone:

LogP*IPA=8.37895-1788.02/(227.438+18)

P*IPA=381.89mmHg

KIPA=381.89/1125.092 =0.339

For water:

LogP*H2O=7.96681-1668.21/(228+81)

P*H2O= 369.89 mmHg

KH2O=369.89/1125.092=0.328

From trail-error, (V/F)=0.2

F=Nacetne,7+Nwater,7+NIPA,7

=90+37.04+10

=137.04kmol/hr

F=B+D

0.2=D/F

B=F-D

=137.04-27.908

0.2=D/137.04

D=27.408

B=109.132

For acetone:

Kacetone=XD/XB

XD=K XB

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=1467 XB

F=DXD+BXB

F=D+B

90=27.408XD+109.632XB

90=27.408*1.467XB+109.632XB

90=149.839XB

XB=90/149.839

=0.606

XD=0.889

For i-propyl alcohol:

XD=KXB

XD=0.339XB

F=D+B

F=DXD+BXB

10=27.408XD+109.132XB

10=27.408*0.339XB+109.132XB

10=118.42XB

XB=10/118.42

=0.0844

XD=0.0286

For water:

XD=KXB

XD=0.328XB

8


F=D+B

F=DXD+BXB

37.04=27.408XD+109.132XB

37.04=27.408*0.328XB+109.132XB

37.04=118.12XB

XB=37.04/118.12

= 0.313

XD=0.103

At stream 8: (vapor) D=27.408kml/hr

Naceton,8=DXD=27.408*0.889=24.366kmol/hr

NIPA,8=DXD=27.408*0.0286=0.784kmol/hr

Nhydrogen,8=DXD=27.408*0.103=2.82kmol/hr

At stream 9: (liquid) B=109.132

Naceton,9=BXB=109.132*0.606=66.134kmol/hr

NIPA,9=BXB=109.132*0.0844=9.2kmol/hr

Nwater,9=BXB=109.132*0.313=34.16kmol/hr

9


Scrubber:

T = 81 C (354.15 K); P = 1.5 bar (1.48 atm)

Assume 1/1000 of inlet acetone is in off-gas.

To calculate the flow rates @stream 12 & 10 for Acetone:

nacetone 12= (1\1000)*(24.366) = 0.024366 Kmol/h

nacetone 10= nacetone 8 – nacetone 12 = 24.366 - 0.024366 = 24.342 Kmol/h

Total molar flow rate @stream8:

ntotal 8= nacetone + nH₂O + nIPA + nH₂ = 24.366 + 2.82 + 0.784 + 90 = 117.97

Kmol/h


ntotal 12= nacetone + nH₂ = 0.024366 + 90 = 90.0244 Kmol/h

yacetone12 = nacetone 12

ntotal 12 =

0.0244

90.0244 = 2.71*10⁻⁴

yacetone8 = nacetone 8

ntotal 8 =

24.366

117.97 = 0.207

To know the amount of H₂O in stream 11:

Yacetone12

yacetone8 =

1−𝐴

1−𝐴⁶ A=

𝐿11

𝑚.𝑉8

m= 𝑒

(10.92−3598

𝑇 )

𝑃 =

𝑒(10.92−

3598354.15)

1.48 = 1.445

Figure 4: Scrubber Unit

10


Yacetone12

yacetone8 =

1−𝐴

1−𝐴⁶ =

2.71∗10⁻⁴

0.207 = 13.09*10⁻⁴ A=3.523

L11 = A.m.V8 = 3.523 * 1.445 * 117.97 = 600.554 Kmol/h

nH₂O 10= nH₂O8 + nH₂O11 = 2.82 + 600.554 = 603.37 Kmol/h


ntotal 10= nacetone + nH₂O + nIPA = 24.342 + 0.784 + 603.37 = 628.496 Kmol/h

Acetone column:

Stream(13):

nacetone = nacetone 9+nacetone10 = 66.134 kmol/h + 24.343 kmol/h = 90.477 kmol/h

nIPA = nIPA 9 + nIPA 10 = 9.2 kmol/h + 0.784 kmol/h = 9.987 kmol/h

nwater = nwater 9 + nwater 10 = 34.16 kmol/h + 603.37 kmol/h = 637.53 kmol/h

nT13 = nacetone + nIPA + nwater = 90.477 kmol/h + 9.987 kmol/h+ 637.53 kmol/h =

737.994 kmol/h

Assume that 1/1000 of acetone is in bottom product.

nacetone15 = 90.477 𝑘𝑚𝑜𝑙/ℎ

1000= 0.090477 𝑘𝑚𝑜𝑙/ℎ

Figure 5: Acetone column

11


nacetone14 = 90.477𝑘𝑚𝑜𝑙

ℎ− 0.090477

𝑘𝑚𝑜𝑙

ℎ= 90.387

𝑘𝑚𝑜𝑙

ℎ

since acetone purity is 99%

nIPA 14 = 90.387𝑘𝑚𝑜𝑙

ℎ×

0.01

0.99= 0.9129

𝑘𝑚𝑜𝑙

ℎ

nIPA15 = nIPA13 - nIPA14 = 9.987 kmol/h – 0.9129kmol/h = 9.074 kmol/h

nwater15 = nwater13 = 637.53 kmol/h

IPA column:

Figure 6: IPA column

Since all the IPA is at the top product,

nIPA17 = nIPA15 = 9.074 kmol/h

nacetone17 = nacetone15 = 0.0904 kmol/h

Assume the composition of the recycle stream is a feed.

ywater = 0.33 , yIPA = 0.67

nacetone17= 9.074𝑘𝑚𝑜𝑙

ℎ×

0.33

0.67= 4.469 kmol/h

nwater16 = nwater15 - nwater17 = 637.53 kmol/h – 4.469 kmol/h = 633.064 kmol/h

12


Feed Drum:

Figure 7: Feed Drum

Input = Output

nIPA2 = nIPA1 + nIPA17

nIPA1 = nIPA2 - nIPA17 == 100 kmol

ℎ– 9.074

kmol

ℎ= 90.926

kmol

ℎ

nwater2 = nwater1 + nwater17

nwater2 = nwater1 - nwater17 = 37.04 kmol

ℎ– 4.469

kmol

ℎ= 32.571

𝑘𝑚𝑜𝑙

ℎ

Since 115000 tons/year acetone is wanted to produce

Amount = 90.477𝑘𝑚𝑜𝑙

ℎ𝑥 58.08

𝑘𝑔

𝑘𝑚𝑜𝑙 𝑥

1 𝑡𝑜𝑛

1000𝑘𝑔 𝑥 8760

ℎ

𝑦𝑒𝑎𝑟= 46825.54

𝑡𝑜𝑛

𝑦𝑒𝑎𝑟

Convert the amount of acetone to 𝑚𝑜𝑙

𝑠

46825.54 𝑡𝑜𝑛

𝑦𝑒𝑎𝑟

x 1 𝑦𝑒𝑎𝑟

11 𝑚𝑜𝑛𝑡ℎ 𝑥

1𝑚𝑜𝑛𝑡ℎ

30 𝑑𝑎𝑦𝑠 𝑥

1 𝑑𝑎𝑦

24 ℎ 𝑥

1 ℎ

60 𝑚𝑖𝑛 𝑥

1𝑚𝑖𝑛

60𝑠 𝑥

1000 𝑘𝑔

1 𝑡𝑜𝑛 𝑥

1000𝑔

1𝑘𝑔 𝑥

1 𝑚𝑜𝑙

58 𝑔= 28.316

𝑚𝑜𝑙

𝑠

Scale factor

115000

𝑡𝑜𝑛

𝑦𝑒𝑎𝑟

46825.54 𝑡𝑜𝑛

𝑦𝑒𝑎𝑟

= 2.46

6,67

𝑚𝑜𝑙

𝑠

28.316 𝑚𝑜𝑙

𝑠

= 0.235

13


Summary of all streams components:

Stream1:

Components Mole % Flow rater

Acetone - -

IPA 73.63 mol% 90.026 kmol/h

Water 26.374 mol% 32.571 kmol/h

H2 - -

Stream2:


Acetone - -

IPA 72.97 mol% 100 kmol/h


H2 - -

Stream4:


Acetone - -



H2 - -

Stream5:


Acetone 39.64 mol% 90 kmol/h



H2 39.64 mol% 90 kmol/h

14


Stream16:


Acetone - -

IPA - -

Water 100 mol% 633.061 kmol/h

H2 - -

Stream17:


Acetone 0.663 mol% 0.0905 kmol/h

IPA 66.56 mol% 9.074 kmol/h


H2 - -

Stream9:





H2 - -

Stream7:


Acetone 39.46 mol% 90 kmol/h



H2 39.64 mol% 90 kmol/h

15


Stream14:


Acetone 99 mol% 90.387 kmol/h


Water - -

H2 - -

Stream15:





H2 - -

Stream13:





H2 - -

Stream10:





H2 - -

16


Stream12:




Water - -

H2 - -

Stream11:


Acetone - -

IPA - -


H2 - -

Stream8:





H2 76.29 mol% 90 kmol/h

the flow rates of all streams in kmol/h · pdf file1 plant design: acetone the flow rates of...

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