MANUFACTURE OF CHLORINE - CAUSTIC SODA USING ELECTROLYSIS PROCESS (MEMBRANE CELL) ...
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Transcript of MANUFACTURE OF CHLORINE - CAUSTIC SODA USING ELECTROLYSIS PROCESS (MEMBRANE CELL) ...
PROJECT TOPIC
MANUFACTURE OF CHLORINE–CAUSTIC
SODA USING ELECTROLYSIS PROCESS
BHARATI VIDYAPEETH COLLEGE OF ENGINEERING
CHEMICAL DEPARTMENTProf. R.K.Kulkarni
Presented by Ankush Gupta
PROCESS FLOW DIAGRAM
Membrane Cell Process
MATERIAL BALANCE
Basis : 1150 kg/hr NaOH , 1000 kg/hr Chlorine
2NaCl + 2H2O 2NaOH + H2 + Cl2
(58.5) (18) (40) (2) (70)
( 28.75) (28.75) (28.75) (14.375) (14.375) Kmoles/hr
(1681.8) (517.5) (1150) (28.75) (1006) kg/hr
• Sample calculationMoles = weight / molecular weight
For NaCl
Moles = 1150/40 28.75 Kmol/hr
NaCl required (Kg) = 28.75 * 58.5 1681.8 kg (1700 Kg/hr).
Assumption : 1700 kg/hr of NaCl 20 kg/hr Na2Co3
• 15/100 x Feed =1700 Feed = 11333.33 Kg/hr.
OVERALL MATERIAL BALANCEFeed (F) + Na2Co3 = |Sludge|4 + |NaCl|311333.33 + 20 = |Sludge|4+ |NaCl|3………………………eqn(1)
MATERIAL BALANCE OF NaCl 1700 = 28%|NaCl|3 + 10%|Sludge|4170000 = 28|NaCl|3 + 10|Sludge|4…………………………….eqn(2)
On Solving Eqn(1) & eqn(2) we get|NaCl|3 = 3137.03 Kg/hr.|Sludge|4 = 8216.3 Kg/hr.
For 55% efficiency of Caustic Soda &Cl2:
2NaCl + 2H2O = 2NaOH + H2 + Cl2
Mass flow(kg/hr) 878.36 270.25 330.28 8.256 289.01
Molecular Weight 58.5 18 40 2 70
Moles flow(Kmol/hr) 15.014 15.014 15.104 7.552 7.552
Moles flow(Kmol/hr) 8.257 8.257 8.257 4.153 4.153 (55%)
Sample Calculation: For NaOH : • Amount of NaCl entering a membrane cell = 28%|NaCl|3=28% (3137.03)=878.368kg/hrConverting into molar flow rate = 878.368/58.5=15.014 Kmol/hr
•By Stoichiometry , No of moles of NaCl = No of moles of NaOH = 15.014 Kmol/hr.But since we have for 55% efficiency for Membrane cell
• No of moles of NaOH = 55%(15.014)= 8.257 Kmol/hr.Therefore the amount of NaOH obtained= 8.257*40=330.28 Kg/hr
OVERALL MATERIAL BALANCE OVER EVAPORATOR Aq. NaOH(35%NaOH) = Aq.NaOH(50% NaOH) + Water vapour 330.28 = 231.196 + 99.081
Calculation for amount of aq.NAOH obtained as a main product:• Pure NaOH out of aq. NaOH = 35% of (330.28) = 115.598 kg/hr• Water content in incoming aq. NaOH = 330.28 – 115.98 = 214.68 kg/hr
Amount of NaOH obtained after 50% concentration is• 50% of (aq. NaOH) = 115.598 kg/hr• Therefore aq. NaOH (50%) obtained as product = 231.196 kg/hr• Water content in obtained aq. NaOH (50%) = 231.196-115.598=115.598 kg/hr• Therefore Water Vapour = 214.68-115.98=99.082 kg/hr
OVERALL MATERIAL BALANCE OVER DRYER:
Wet Cl2 + H2SO4(98% conc) = Dry Cl2 + H2SO4 (70% conc)289.019 + 98% of (25kg) = Dry Cl2 + H2SO4 (70%)
…….eqn1
MATERIAL BALANCE OF H2SO4 OVER DRYER:
Inlet H2SO4 (98%conc) = Outlet H2SO4 (70%conc) 98%(25) = 70% H2SO4
98x25 = 70% H2SO4
H2SO4 (70%) = 35 kg/hrSubstituting in …..eq1 Dry Cl2 = 278.519 kg/hr.
ENERGY BALANCE
STEAM REQUIREMENT FOR HEATING BRINE
m = mass flow rate of Aq NaCl in kg/hrCP = specific heat capacity of Aq NaCl At 60OCΔT = Temperature Difference λ = latent Heat of evaporization in kJ/kg m1 = Flow rate of steam kJ/hr
mcPΔT = m1 λ
3137.03 x 3.274 (333-298) = m x 2358.40 m1 = 151.186 kJ/hr
ENERGY BALANCE OVER MEMBRANE CELL
Assumption Datum temperature = 25oC
INLET STREAM
OUTLET STREAM
MATERIAL NAME
SPECIFIC HEAT AT 60oC FLOW RATES kg/hr
H2O 4.185 kJ/kgK 270.252
Aq.NacL solution
3.247 kJ/kgK 876.368
MATERIAL NAME SPECIFIC HEAT AT 80oC FLOW RATES kg/hr
Hydrogen (g) 14.43 kJ/kgK 8.256
Chlorine (l) 0.48 kJ/kgK 289.019
NaoH (35% by wt) 3.594 kJ/kgK 330.28
Depleted brine 3.247 kJ/kgK 521.065
• INPUT STREAM Material mcPΔT Aq .NaCl 876.368 x 3.247x (333-298) = 99594.84 kJ/hr H2O 270.252 x 4.185 x (333-298) = 39585.16 kJ/hr
TOTAL HEAT INPUT = 99594.84 + 39585.16 = 139180 kJ/hr
• OUTPUT STREAMMaterial mcPΔT Hydrogen (g) 8.256 x 14.43 x (353-298) = 6552.37 kJ/hrChlorine (l) 0.48 x 289.019 x(353-298) = 4855.51 kJ/hr Aq.NaoH 3.594 x 330. 28 x (353-298) = 41545.92 kJ/hr Depleted Brine 3.247 x 521. 065 x (353-298)= 59216.43 kJ/hr
TOTAL HEAT OUTPUT = 6552.37 + 4855.51 + 41545.92 + 59216.43 = 112170.23 kJ/hr
2Na (s) + 2H2O 2NaOH + H2O ΔH = -368.4 kJ/gmNa
Depleted brine = 526.064 kg/hr (50% by wt of NaCl)0.5 x 526.064 x -368.4 = - 96900.98 J/hr
MATERIAL NAME
SPECIFIC HEAT AT 80oC FLOW RATES kg/hr
Aq.NaoH 35% by wt
3.594 kJ/kgK 330.28
MATERIAL NAME SPECIFIC HEAT AT 110oC FLOW RATES kg/hr
50 % Caustic soda 3.564 kJ/kgK 231.196
INLET STREAM
OUTLET STREAM
MATERIAL NAME Latent Heat AT 110oC FLOW RATES kg/hr
Steam 2231.86 kJ/kg 94.127
ENERGY BALANCE OVER EVAPORATOR
• INPUT STREAM Material mcPΔT Aq .NAOH 330.28 x 3.594 x (353-298) = 65286.44 kJ/hr
TOTAL HEAT INPUT = 65286.44 kJ/hr
• OUTPUT STREAMMaterial mcPΔT Aq.NaoH (50% by wt) 231.196 x 3.564 x (383-298) = 45319.03 kJ/hr Material mλ Water vapour (g) 94.127 x 2231.86 = 210078.28 kJ/hr
TOTAL HEAT OUTPUT = 45319.03 + 210078.28 = 255397.31 kJ/hr
MATERIAL NAME
SPECIFIC HEAT FLOW RATES kg/hr
Wet chlorine 0.48 kJ/kgK 289.019
H2SO4 (98% by wt)
1.465 kJ/kgK 10
MATERIAL NAME
SPECIFIC HEAT FLOW RATES kg/hr
Dry chlorine 0.48 kJ/kgK 285.019
H2SO4 (70% by wt)
2.177 kJ/kgK 14
INLET STREAM
OUTLET STREAM
ENERGY BALANCE OVER DRYER
• INPUT STREAM Material mcPΔT Wet Chlorine 289.019 x 0.48 x (353-298) = 7630.10kJ/hr
TOTAL HEAT INPUT = 7630.10 kJ/hr
• OUTPUT STREAMMaterial mcPΔT Dry Chlorine (l) 285.019 x 0.48 x (343-298) = 6156.41 kJ/hr H2SO4 70% 14 x 2.177 x (303-298) = 152.39 kJ/hr
TOTAL HEAT OUTPUT = 6156.41 + 152.39 = 6308.8 kJ/hr
% conversion NaCl = (Reacted moles / Total no moles) x 100
= {(878.36 – 261.032)/878.36} x 100= 70.28 %
%Yield = (NaoH moles Formed /Reacted moles of NaCl) x 100
= {(115.598/ 40) / (617.328/58.5) } x 100 = 27.37 %
REFERENCES1 ) Subrata Basu , Swapan Kumar Mukhopadhyay , Amitava Gangopadhyay
and Sujata G. Dastidar “International Research Journal of Environment Sciences Characteristic Change of Effluent from a Chlor-alkali Industry of India due to Process Modification” 2013.
2) S.Koter.A.Warszawski “Polish Journal of Environmental Studies Electro- membrane Processes in Environment Protection” (2000)
3) Yohannes Kiros and Martin Bursell “International Journal Electrochemistry Science Low Energy Consumption in Chlor-alkali Cells Using Oxygen Reduction Electrodes (2008)”
4) Rezaee, J. Derayat, S.B. Mortazavi,Y. Yamini and M.T. Jafarzadeh “American Journal of Environmental Sciences Removal of Mercury from Chlor-alkali Industry Wastewater using Acetobacter xylinum Cellulose(2005)”
5) Dryden’s outlines of chemical technology (2012)