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Manufacturing Industrial chemicals

Chandran udumbasseri

cudumbasseri@yahoo.co.in.

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

2

C12H22O11 + H2O 2C6H12O6

2C6H12O6 + 12HNO36HOOC-COOH + 12NO + 12H2O

C6H12O6 + 9[O] 3HOOC-COOH + 3H2O

6HNO3 6NO + 9[O] +3H2O

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

minutes = 378/30 = 12.6 gpm ~ 10 gpm capacity centrifugal CS pump.

Nitric acid pump

Volume of nitric acid required per cycle = 192gal/cycle.

The nitric acid is to be pumped within ½ hr, 192/30 = 6.4 gpm ~ 6gpm capacity SS

pump

Air blower

Total amount of NO gas liberated daily = 2073Liters

Gas evolution per minute =

= 1.4 liters/minute

The blower should have capacity to blow 1.5Lt/minutes

Liquid extractor (Liquid solid separator)

The total bulk volume of oxalic acid = 4000Kg

Bulk density of oxalic acid = 833 kg/m3

One cubic meter of oxalic acid weighs 833Kg

4000 kg oxalic acid has bulk volume =

= 4.8 m3

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4.8m3 oxalic acid is to be unloaded from the reactor in 1hr. The extractor should

have the capacity to extract 4.8/60 = 0.08 m3/minute = 80Liters/minute

Liquid extractor capacity = 100 liters of solid/minutes

Mother liquor storage tank

Total mother liquor is

Volume of sulfuric acid + non reacted Nitric acid + water from sugar solution +

water from oxidation reaction=

+

+

+

= 750 + 1043 + 2640 + 1666 = 6099 Liters

Considering 75% working volume, then

= 8132 liters~8000 Liters

Mother liquor storage tank volume (carbon steel) = 8000 liters =

=2113

gal/day

SS pump is used to pump mother liquor to the reactor.

Nox scrubber (2Nos)

Scrubber of 1 ½ ft diameter, 10ft height, 4-7 gal/min flow with circulating pump;

construction, PP/ Fiberglass.

Alkaline nitrate tank

Nitric oxide has a solubility of 75ml per liter of water. Scrubber can take up to

4gallons per minute. Air blower operates at 2 liter per minute. Nox gas evolution

is 1.5 liters per minute. 100 gallons of 10% caustic alkali is used for scrubbing.

Tank capacity is 150 gallons

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Dryer

Bulk volume of oxalic acid produced per day 4.8m3. Hot air circulated tray dryer of

capacity 400Kg (48 trays in each batch of drying) drying per hour at 105oC-110oC.

Total amount per day production is 4000Kg.Total time of drying is 1-1 ½ hrs.

Unloading for 400 Kg is ½ hr. 4000 K of crystals is dried by 20 hrs.

Cooling tower

The flow of ambient temperature water (25oC) through the jacket of the reactor

should be to maintain a reaction temperature of 60-65oC.

Alkali tank

Tank capacity is 150 gallons. 10% of NaOH solution is used as scrubber solution

Alkaline sprayer pump

Heat of reaction

Reaction

C6H12O6 + 6HNO33HOOC-COOH + 6NO + 6H2O

Heat of formation of glucose = -1268 kJ/mol

Heat of formation of HNO3 = -207.36kJ/mol

Heat of formation of oxalic acid = -822.2 kJ/mol

Heat of formation of NO = +90.25kJ/mol

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Heat of formation of water = -241.82 kJ/mol

3HOOC-COOH – (C6H12O6 + 6HNO3- 6NO - 6H2O)

3 ∆Hoxalic acid – (∆Hglucose + 6∆Hnitric acid -6∆HNO - 6∆Hwater)

3(-822.2)-(-1268+6(-207.36)-6(+90.25)-6(-241.82) = -863kJ/mol = -818BTU/mol = -

818000 Btu/kgmol

If this heat is liberated in 3hrs (sugar addition time)

=

= 272670

For 3 cycle,

= 90890 BTU/kgmol = 90890x7.713 = 701034 Btu/hr

Assuming a difference of 15oC for cooling water

Mass of water required

m =

=

= 46735 Kg/hr =

= 205 gal/min

Heat transfer area to cool reactor

Inlet water temperature = 25oC

Water outlet temperature = 40oC

Equation to be used, Q = AU∆Tim

Heat transfer coefficient = 45 Btu/ (h) (ft2) (oF)

∆Tlm =

=

= 68oF

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Cooling area = A =

=

=229ft2

Equipment specification

1. Reactor vessel, SS316 make = 900gallon 2. Nitric acid addition tank, SS 316 make, 250 gal 3. Sugar addition tank, CS/Al/ PP, 500gal 4. Liquid sugar stock tank, PP/HDPE, 1500gal 5. Sugar pump, CS, 10gpm 6. Nitric acid, SS, 6gpm 7. Air blower, flow rate, 2 Lt/minute 8. Liquid extractor, SS, 100liters of solid/min 9. Mother liquor tank, SS, 2000gal 10. Mother liquor pump, SS, 11. Nox scrubber, Fiberglass, 1 ½’ x10’ 4 gal/min 12. Alkaline nitrite tank, HDPE, 150 gal 13. Dryer, 48 tray, 500 kg/hr 14. Cooling tower, 15. Alkali tank, 150 gal, HDPE 16. Alkali sprayer pump