The separation of air by carbon molecular sieve (CMS) adsorption was studied in this work over a range of adsorption pressure of (2–8) bar. Breakthrough curves showed no significant effect of the pressure on product nitrogen purity and adsorbent capacity above 4 bar. Maximum purity of about 98% is observed for time up to 60 s. Adsorbent capacity obtained is in agreement with multicomponent Langmuir isotherm up to 4 bar. Maximum constant adsorbent capacity of about 0.1 mol O2/kg CMS is obtained for pressure above 4 bar.For PSA two columns 6-steps process, no significant effect of the pressure on the product purity above 4 bar. The purity increases with decreasing the productivity. Maximum purity of 97.6% is obtained at productivity of 156 lit/kg CMS.hr, cycle time of 100 s, and purge flowrate of 1 lit/min. The productivity of 606 lit/kg CMS.hr is obtained at purity of 94%, cycle time of 60s, and purge flowrate of 4 lit/min.

The main objective of this study was to evaluate the use of batch bubble column to produce high particle size (>300 micron) of sodium bicarbonate product to improve filtration and drying operations in the production process. Lab scale batch bubble column of 80 mm diameter and 0.5 m height was used to study the process for sodium bicarbonate production using 20% sodium carbonate solution as a starting solution. Three operating variables were considered, CO2 gas content (20-100 %), temperature (30-70 oC) and time (0.5-2.5 h). The bicarbonate yield and crystals size were considered to be the objective variables of the process. Response surface methodology (RSM) was used with central composite design (CCD) of experiments. Empirical polynomial multivariable equations were obtained. The reaction time was found to be the most effective operating condition on the yield of sodium bicarbonate, and temperature was found to be the most effective operating condition on crystal size of sodium bicarbonate. The optimum conditions achieved 400 microns particle size at temperature 70 oC and time 2.5 h. Kinetics study of the process showed that zero order reaction with both sodium carbonate and CO2 concentrations was approximately fitted the experimental data, useful for shortcut process design purposes.

Single long spiral tube column pressure swing adsorption (PSA) unit, 25 mm diameter, and 6 m length was constructed to study the separation of water from ethanol at azeotropic concentration of 95 wt%. The first three meters of the column length acted as a vaporizer and the remaining length acted as an adsorber filled by commercial 3A zeolite. The effect of pressure, temperature and feed flow rate on the product ethanol purity, process recovery and productivity were studied. The results showed that ethanol purity increased with temperature and pressure and decreased with feed flow rate. The purity decreased with increasing productivity. The purity range was 98.9 % to 99.6 %, the recovery range was 0.82 to 0.92 and the productivity range was 0.3 to 1.05 kg ethanol/kg zeolite.h.

Utilization of CO2 in flue gases for the production of sodium bicarbonate is an environmentally friendly process. A mathematical model was constructed for the design and simulation of utilizing a low concentration CO2 (2-18%) in flue gas to produce sodium bicarbonate in a bubble column reactor. The model is based on the mass balance equations for three phases (gas, liquid, and solid). Danckwerts theory for mass transfer from the gas phase to the liquid phase coupling with chemical reaction, and crystallization mechanism was used. The effect of process variables; gas molar velocity or flux (G=2.5-10 mole/m2.s), liquid mass flow rate (mL=2800-3400 kg/h), sodium bicarbonate concentration (x1=0.04-0.1), CO2 gas mole fraction (y=0.02-0.18), column height (h=11-33 m), and column diameter (dR=1-3 m) on the objective variables; solid molar velocity (S), CO2 conversion, precipitation zone height (Zi), and crystal size distribution (CSD) were studied. The conversion of CO2 varied from 34% to 71% whereas the particle size range varied from 0 to 400 μm. The particle size range and the CO2 absorption efficiency of about 50% for 20 m column height are in agreement with the literature.

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