Material balance of Diethyl ether production plant. Calculation of recycle stream using overall material balance.

1. 13
CHAPTER 3
MATERIAL BALANCE
This chapter includes material balance of reactor flash vessels and distillation column also
gives the final product purity and flowrate.
By analysis of the import data in Chemical Weekly (June 2015, volume 29) we can
assume the plant capacity as 50,000 tons per annum. Taking 340 working day of the
plant for 3 shift of 8 hours
plant capacity=
50000×1000
340×24
kg/hr
=6127.4 kg/hr
Product Diethyl Ether purity is 99.5% rest is water and ethanol, for convert mass flow rate
into molar flow rate finding out average molecular weight of product
M.W. of Diethyl Ether is 74.14 kg/kmol.
M.W. of Water is 18.01528 kg/kmol.
M.W. of Ethanol is 46 kg/kmol.
Taking average molecular weight= 0.995(74.14) + 0.0025(18.01528) + 0.0025(46)
= 73.9293 kg/kmol
product molar flow rate =
6127.4
73.9293
kmol/hr
=82.88 kmol/hr.
REACTOR (1)
For reaction 1
1 kmol diethyl ether (DEE) @ 2 kmol C2H5OH
@ 1 kmol H2O
For reaction 2
1 kmol C2H4 @ 1 kmol C2H5OH @ 1 kmol H2O

2. 14
Conversion = 52.5% [7]
Yield of diethyl ether (DEE) = 96.19% [7]
Feed = 0.13818 kmol/sec
Ethanol = 0.12533 kmol/sec
Water = 0.01285 kmol/sec
Diethyl ether produced = conversion x Yield x Ethanol / 2
= 0.525 x 0.9619 x 0.12533/2
= 0.03164 kmol/sec
Ethylene produced = conversion x (1 - Yield) x Ethanol
= 0.525 x (1 – 0.9619) x 0.12533
= 0.00238 kmol/sec
Water produced = conversion x Yield x Ethanol / 2 + conversion x (1 - Yield) x Ethanol
= 0.525 x 0.9619 x 0.12533/2 + 0.525 x (1 – 0.9619) x 0.12533
= 0.03164 + 0.00238 kmol/sec
= 0.03402 kmol/sec
Total water in the product stream = 0.03164 + 0.01285
= 0.04449 kmol/sec
Unreacted Ethanol = feed x (1- conversion)
= 0.12533 x (1-0.525)
=0.05953 kmol/sec
For the reactor feed and product molar flowrate is given in table 3.1.
Table 3.1: feed and product molar flowrate for reactor
in kmol/sec Feed Product
Ethanol 0.12533 0.05943
Water 0.01285 0.04449
Diethyl Ether 0.00000 0.03164
Ethylene 0.00000 0.00238
Total 0.13818 0.13794

3. 15
FLASH VESSEL (5)
For the flash vessel feed, top and bottom molar flowrate is given in table 3.2.
Table 3.2: flowrate of inlet and outlet stream for flash vessel
in kmol/sec Feed
Top
product
Bottom
product
Ethanol 0.05943 0.00003 0.05940
Water 0.04449 0.00009 0.04440
Diethyl Ether 0.03164 0.00063 0.03101
Ethylene 0.00238 0.00127 0.00111
Total 0.13794 0.00202 0.13592
DISTILLATION COLUMN: (3)
Feed: 0.13592 kmol/sec
Diethyl ether = 0.03101 kmol/sec
Ethylene = 0.00111 kmol/sec
Ethanol = 0.05940 kmol/sec
Water = 0.04440 kmol/sec
F = D + W
XF x F = D x XD + W x XW
For XF = 0.2258 XD = 0.9636 XW = 0.0029
From Diethyl Ether above equations
D = 0.03153 kmol/sec W = 0.1043 kmol/sec
In table 3.3 flowrate of distillate, residue (bottom) and feed is given for all compound

4. 16
Table 3.3: molar flowrate of inlet and outlet streams for distillation column (3)
in kmol/sec Feed
Top
product
Bottom
product
Ethanol 0.05940 0.00000 0.05940
Water 0.04440 0.00000 0.04440
Diethyl Ether 0.03032 0.03018 0.00014
Ethylene 0.00111 0.00111 0.00000
Total 0.13183 0.03153 0.10430
DISTILLATION COLUMN: (4)
Feed: 0.1043 kmol/sec
Diethyl ether = 0.00014 kmol/sec
Ethylene = 0.0000 kmol/sec
Ethanol = 0.05940 kmol/sec
Water = 0.04440 kmol/sec
F = D + W
XF x F = D x XD + W x XW
For Ethanol XF = 0.5578 XD = 0.8588 XW = 0.01563
From above equations
D = 0.067 kmol/sec W = 0.03549 kmol/sec
In table 3.4 flowrate of distillate, residue (bottom) and feed is given for all compound
Table 3.4: molar flowrate of inlet and outlet streams for distillation column (4)
in kmol/sec Feed
Top
product
Bottom
product
Ethanol 0.05940 0.05753 0.00187
Water 0.04440 0.00915 0.03525
Diethyl Ether 0.00014 0.00014 0.00000
Ethylene 0.00000 0.00000 0.00000
Total 0.10430 0.067 0.03730

5. 17
FLASH VESSEL: (7)
For the flash vessel feed, top and bottom molar flowrate is given in table 3.5.
Table 3.5: flowrate of inlet and outlet stream for flash vessel
in kmol/sec Feed
Bottom
Product
Top
Product
Ethanol 0.00000 0.00000 0.00000
Water 0.00000 0.00000 0.00000
Diethyl Ether 0.03018 0.02336 0.00582
Ethylene 0.00111 0.00006 0.00105
Total 0.03153 0.02342 0.00870
Diethyl ether produced = 0.02342 kmol/sec
= 0.02342 x 3600 x 24 x 340 kmol/sec
= 687985.92 kmol/year
= 687985.92 x 74 /1000 TPA
= 50910.95 TPA
Purity of Diethyl ether = 0.02336/0.2342 x 100
= 99.74 %