In a typical Chlor-Alkali plant, salt (28 kg/h) and water (72 kg/h) are mixed to form...

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In a typical Chlor-Alkali plant, salt (28 kg/h) and water (72 kg/h) are mixed to form brine solution. It is then purified by chemical dosing. Purified brine is then sent to an electrolyzer. The depleted brine solution from the electrolyzer contains 25 wt% NaCl. Salf Water Salt composition (wt%) NaCl 96.756 Boiling point of sodium hydroxide solution (°F) 250 -Water Vapor Sat'd ( 0.2 bar لب 300 200 Mixer Condensate 150 100 50 c) Determine the steam requirement for the first evaporator. d) What is the concentration of final caustic soda product? e) Determine the steam economy. 0 -Dosing -Brine-> Ca²+ 0.26 25 L 50 Brine Treatment The caustic soda stream from the electrolyzer (33 wt% NaOH at 95°C) is sent to a double effect evaporator. The first evaporator is atmospheric and the second evaporator is operated at 0.2 bar pressure absolute. Saturated steam at 5 bar pressure is fed to the first evaporator. The steam is condensed and exits the evaporator as a saturated liquid. The concentrated caustic soda stream from the first evaporator contains 42 wt% NaOH. The water vapor from first effect is sent to the second effect to further concentrate the caustic soda stream. Consider the water vapors and concentrated liquid streams that come out from the evaporators are saturated vapors and saturated liquids respectively. Evaporator 60 wt. % N₂OH 50 wt. % N₂OH 40 wt. % N₂OH Boiling point of water (°C) 50 75 42% NaOH a) Which chemicals are used for brine treatment? Determine the required flow rate of those chemicals. b) Determine the flowrates of H₂ and Cl2 gases. -Treated Brine-> Depleted Brne Water Vapor Sat'd (a 1 atm 30 wt% N OH 20 wt. % NOH 10 wt% N₂OH water 100 SO₂²- 0.38 Chionne 125 2- 100 150 200 Boiling point of water (°F) FIGURE 8.4-2. Dahring lines for aqueous solutions of sodium hydroxide. 250 Figure 1: Duhring's plot for NaOH-Water system Electrolyzer Hydrogen Gas 300 Evaporator 3 125 100 75 o 9 Water 33% NaOH Mg²+ 0.024 Saturated Steam Sat'da 5 bar Boiling point of sodium hydroxide solution (°C) Enthalpy (btu/lbm solution) 300 250 200 150 50 250°E F200°F 150°F- 100°F- Moisture 2.58 -50°F. (148.9°C) 0.10 (121.1°C); (93.3°C) (65.6°C) (37.8°C)- 600 500 -400 300 200 100 (10°C). 0.20 0.30 0,40 0.50 Concentration (wt fraction NaOH) Figure 2: Enthalpy concentration diagram for NaOH-Water system (Reference: Liquid water at 0°C) Enthalphy (kJ/kg solution) 0.60 In a typical Chlor-Alkali plant, salt (28 kg/h) and water (72 kg/h) are mixed to form brine solution. It is then purified by chemical dosing. Purified brine is then sent to an electrolyzer. The depleted brine solution from the electrolyzer contains 25 wt% NaCl. Salf Water Salt composition (wt%) NaCl 96.756 Boiling point of sodium hydroxide solution (°F) 250 -Water Vapor Sat'd ( 0.2 bar لب 300 200 Mixer Condensate 150 100 50 c) Determine the steam requirement for the first evaporator. d) What is the concentration of final caustic soda product? e) Determine the steam economy. 0 -Dosing -Brine-> Ca²+ 0.26 25 L 50 Brine Treatment The caustic soda stream from the electrolyzer (33 wt% NaOH at 95°C) is sent to a double effect evaporator. The first evaporator is atmospheric and the second evaporator is operated at 0.2 bar pressure absolute. Saturated steam at 5 bar pressure is fed to the first evaporator. The steam is condensed and exits the evaporator as a saturated liquid. The concentrated caustic soda stream from the first evaporator contains 42 wt% NaOH. The water vapor from first effect is sent to the second effect to further concentrate the caustic soda stream. Consider the water vapors and concentrated liquid streams that come out from the evaporators are saturated vapors and saturated liquids respectively. Evaporator 60 wt. % N₂OH 50 wt. % N₂OH 40 wt. % N₂OH Boiling point of water (°C) 50 75 42% NaOH a) Which chemicals are used for brine treatment? Determine the required flow rate of those chemicals. b) Determine the flowrates of H₂ and Cl2 gases. -Treated Brine-> Depleted Brne Water Vapor Sat'd (a 1 atm 30 wt% N OH 20 wt. % NOH 10 wt% N₂OH water 100 SO₂²- 0.38 Chionne 125 2- 100 150 200 Boiling point of water (°F) FIGURE 8.4-2. Dahring lines for aqueous solutions of sodium hydroxide. 250 Figure 1: Duhring's plot for NaOH-Water system Electrolyzer Hydrogen Gas 300 Evaporator 3 125 100 75 o 9 Water 33% NaOH Mg²+ 0.024 Saturated Steam Sat'da 5 bar Boiling point of sodium hydroxide solution (°C) Enthalpy (btu/lbm solution) 300 250 200 150 50 250°E F200°F 150°F- 100°F- Moisture 2.58 -50°F. (148.9°C) 0.10 (121.1°C); (93.3°C) (65.6°C) (37.8°C)- 600 500 -400 300 200 100 (10°C). 0.20 0.30 0,40 0.50 Concentration (wt fraction NaOH) Figure 2: Enthalpy concentration diagram for NaOH-Water system (Reference: Liquid water at 0°C) Enthalphy (kJ/kg solution) 0.60

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Solutions Step 1 The Chloralkali process is used in the electrolysis of NaCl The import... View the full answer