1 Manufacturing Industrial chemicals Chandran udumbasseri [email protected]. General Introduction This is a document site where new projects will be published now and then. All the projects were time tested, implemented and sometimes installed and continued to manufacture. Those who prefer to adopt can do so with a bit of gratitude to the author. The first project is industrial oxalic acid that can be manufactured from sugar or such related products. Sugar Oxidation - Oxalic Acid Production Introduction Oxalic acid finds use in pharmaceuticals, dye-stuff and textiles industries. Its derivative diethyl oxalate is the starting material for sulphamethoxazole drug. It is also used in equipment cleaning, textile finishing, leather tanning and purifying. Process Oxalic acid can be produced in pure form (98% +) by the oxidation of cane sugar products molasses, jaggery and sugar. Mixture of sulfuric acid and nitric acid is used as oxidizing agent using the catalyst vanadium pentoxide. A 50% sulfuric acid is used as heat sink and to produce reactive nitryl sulfuric acid which acts as the intermediate in the oxidation. The following conditions are used for manufacturing oxalic acid: 1. Conc:Sulfuric acid to Conc Nitric acid ratio = 1.5-2.3 (here for calculation 2.3 ratio is adapted) 2. The glucose to nitric acid mole ratio = 1:3.2
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3. Catalyst Vanadium Pentoxide required = 0.05% (m/m) of moles glucose 4. Reaction temperature is maintained at 60-65oC 5. Sucrose is added in 3 hours. 6. Conversion to oxalic acid by this method = 95-98% (~96%) 7. Sucrose is added as 50 % solution in water
Production batch calculation
Target 1200MT per year
Total number of working days per year = 300
Production per day =
= 4000 Kg
Molecular weight of Sucrose = 342.296
Molecular weight of Oxalic acid = 90.036
Molecular weight of Nitric acid = 63.018
Input Quantities
Moles of Oxalic acid, kg mol /day =
= 44.427 kg moles/day
The oxidation reaction shows 6 moles of oxalic acid is produced per mole of
sucrose.
So to produce 44.427 kg moles of oxalic acid the required kg moles of sucrose =
= 7.4 Kg moles of sucrose = 7.4 x 2 = 14.8 Kg moles of glucose.
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As the conversion is 96% the required sucrose is =
= 7.713 Kg mole of sucrose.
Weight of sucrose required = 7.713 x 342.296 Kg = 2640 Kg
The reaction mole ratio for glucose to Nitric acid is = 1:3.2
For 7.713x2 = 15.426 kg mole of glucose the required kg mole of Nitric acid is
15.426 x 3.2 = 49.36 Kg mole
Weight of Concentrated Nitric acid is = 49.36x 63.018 = 3110.77 Kg
98%Nitric acid =
= 3240 Kg
Conc Sulfuric acid to Conc Nitric acid is 2.3
Weight of concentrated Sulfuric acid is =
= 1352.5 Kg
98% of Sulfuric acid =
= 1380 Kg
Catalyst (Vanadium pentoxide) amount = 0.05% of sucrose moles
For 7.713 Kg mole of sucrose V2O5 required = 0.0039 kg mole = 0.7Kg
(it is sufficient to add catalyst in the first reaction mass if mother liquor is
recycled)
Quantity calculated per day -input
S/N Material description Quantity, Kg
1 Sucrose,50% Solution 5280
2 Nitric acid, 96% 3240
3 Sulfuric acid, 98% 1380
4 Vanadium Catalyst 0.7
Quantity per day -output
Oxalic acid produced = 4000Kg
Nox gas produced
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2C6H12O6 + 12HNO36HOOC-COOH + 12NO + 12H2O
1mole of NO at NTP occupies a volume of 22.4 liters.
12 moles has volume 22.4x12 = 269 Liters
For 7.713 sucrose the gas volume is 269 x7.713 = 2073 liters
Mother liquor
Nitric acid used = 12 HNO3 = 12x63.018 = 756 kgs per moles of sucrose
For 7.713 mole of sucrose = 756 x7.713 = 1619 =
=1686kg
Un- reacted nitric acid (96%) = 3240-1686 = 1554 Kg
Water from reaction
Water from 12 mole of HNO3 = 12 H2O = 12x18 = 216 Kg
For 7.713 mole sucrose = 216x7.713 = 1666 Kg
Final mother liquor composition
S/N Material description Quantity, Kg
1 Nitric acid 1554
2 Water 1666
3 Sulfuric acid 1380
Total 4600
Nitric acid in mother liquor as calculated = 24 % (in practice only 20% is found)
Specific gravity parameters of all mixtures
Sulfuric acid (98%) 1.84
Nitric acid (96%) 1.49
Sugar solution 1.23
Mother liquor 1.42
Caustic soda (10%) solution (scrubber solution) 1.12
Acid mixture (sulfuric acid/nitric acid) 1.67
Oxalic acid-Bulk density, Kg/m3 833
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Flow chart
Equipment Design and Selection
Equipments:
1. Reactor vessel 2. Nitric acid addition tank 3. Sugar addition tank 4. Liquid sugar stock tank 5. Sugar pump 6. Air blower
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7. Liquid extractor 8. Mother liquor tank 9. Mother liquor pump 10. Nox scrubber 11. Alkaline nitrate tank 12. Dryer 13. Cooling tower 14. Alkali tank 15. Alkali sprayer pump
Reactor Volume
Daily cycle = 8hrs (Charging time, ½ hr + Reaction time, 3 ½ hrs + crystallization
time, 3 hrs + unloading reactor content, 1 hr )
Number of cycles per day = 23/8 = 3
Process Parameters
Temperature = 60 – 65oC
Pressure = 1atm
Volume safety factor = 10%
Volume of acid mixture =
= 804 gal/day
(10% excess volume; 3.785Lt = 1gal; 1.67 = sp.gr)
Volume of sugar solution =
= 1248 gal/day
(10% excess volume; 1 gal = 3.785 Lt; sp.gr of sugar solution = 1.23)
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Total reaction volume = 804 + 1248 = 2052 gal/day
No of cycles per day = 3
Volume per cycle = 2052/3 = 684 gal/day
Considering the reactor 75% then volume of the reactor needed is =684/0.75 =
912 gallons ~900 gallons
Reactor 900 gallons made of non-corrosive SS
Nitric acid
Daily requirements of nitric acid =
= 575gal/day
Requirements per cycle = 575/3 = 192gal/cycle
Considering 75% working volume = 192/0.75 = 256 gal/cycle
Nitric acid addition volume ~ 250 gal
Material of tank construction = SS
Sugar addition tank
Daily requirements of sugar solution =
= 1134gal/day
Requirements per cycle = 1134/3 = 378gal/cycle
Considering the reactor 75% then volume of the reactor needed is = 378/0.75 =
504 gal ~500gal
Liquid sugar stock tank
The sugar is prepared for each day once for 3 cycle
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Total daily requirement of sugar solution = 1134 gal. Working volume is 75%
Required volume of stock tank = 1134/0.75 = 1512 gal ~1500 gal
Sugar pump
The sugar solution is to be pumped to the addition tank within ½ hr. 378 gal in 30