Studies on Gas Hold-Up , Mass Transfer Coefficient,Mixing Time And Circulation Time In Bubble ColumnsWith Draught Tube For Pseudo Plastic (Carboxymethyl) Cellulose And Glycerol Solutions

Abstract

Bubble column reactors are widely used in chemical process industries for carrying out gas-liquid and gas-liquid-solid reactions such as absorption, biochemical process and coal liquefaction. To design such a column, four main parameters should by taken in consideration, the gas holdup (g ε), liquid phase mass transfer coefficient (K La), mixing time (t m) and circulation time (t c). The study includes the effect of gas velocity and liquid phase properties [Newtonian and non-Newtonian] on g ε , K La , t m and t c in bubble column with draught tube when the ratio of the draught tube diameter to column diameter equal to 0.5 and the gas dispersed into the base of the draught tube by using [amultihole, 0.15mm equivalent diameter and 0.61% free sectional area] distributor. Water and aqueous solutions of glycerol and CMC [Carboxymethyl Cellulose], were used as the liquid phase [Newtonian and non-Newtonian]. From experimental observations g ε , and K La increased with increasing gas velocity and coalescence inhibition of liquid, while tm and tc decrease with increasing gas velocity. It was found that increasing liquid viscosity and coalescence reduces g ε and K La but increases t m and t c. ‫ﻓﻲ‬ ‫ﺍﻟﺩﻭﺭﺍﻥ‬ ‫ﻭﺯﻤﻥ‬ ‫ﺍﻟﺨﻠﻁ‬ ‫ﻭﺯﻤﻥ‬ ‫ﺍﻟﻜﺘﻠﺔ‬ ‫ﺍﻨﺘﻘﺎل‬ ‫ﺍﻟﻐﺎﺯﻭﻤﻌﺎﻤل‬ ‫ﺍﺤﺘﺠﺎﺯ‬ ‫ﺯﻤﻥ‬ ‫ﺩﺭﺍﺴﺔﻋﻠﻰ‬ ‫ﻭﻜﻠﻴﺴﻴﺭﻭل‬ ‫ﺴﻴﻠﻴﻠﻭﺯ‬ ‫ﻤﺜﻴل‬ ‫ﺍﻻﺤﺎﺩﻱ‬ ‫ﻟﻠﻤﺤﺎﻟﻴل‬ ‫ﺩﺍﺨﻠﻲ‬ ‫ﺍﻨﺒﻭﺏ‬ ‫ﻤﻊ‬ ‫ﺍﻟﻔﻘﺎﻋﻴﺔ‬ ‫ﺍﻻﻋﻤﺩﺓ‬ ‫ﺍﻟﺨﻼﺼﺔ‬ ‫ﺃﻏﻠـﺏ‬ ‫ﻓـﻲ‬ ‫ﺍﻟﻁـﻭﺭ‬ ‫ﺜﻼﺜﻴﺔ‬ ‫ﺍﻭ‬ ‫ﺜﻨﺎﺌﻴﺔ‬ ‫ﻜﻤﻔﺎﻋﻼﺕ‬ ‫ﺍﻟﻔﻘﺎﻋﻴﺔ‬ ‫ﺍﻻﻋﻤﺩﺓ‬ ‫ﺍﺴﺘﺨﺩﺍﻡ‬ ‫ﺸﺎﻉ‬ ‫ﻟﻘﺩ‬ ‫ﺍﻟﻌﻤﻠﻴـﺎﺕ‬ ‫ﻭﻏﻴﺭﻫـﺎ‬ ‫ﺍﻟﻔﺤـﻡ‬ ‫ﻭﺍﺴـﺎﻟﺔ‬ ‫ﺍﻟﺒﺎﻴﻭﻜﻴﻤﻴﺎﺌﻴﺔ‬ ‫ﻭﺍﻟﺘﻔﺎﻋﻼﺕ‬ ‫ﺍﻻﻤﺘﺼﺎﺹ‬ ‫ﺫﻟﻙ‬ ‫ﻋﻠﻰ‬ ‫ﻤﺜﺎل‬ ‫ﺍﻟﺼﻨﺎﻋﻴﺔ‬ ‫ﺍﻟﻜﻴﻤﻴﺎﺌﻴﺔ‬. ‫ﻤﺜل‬ ‫ﻤﻬﻤﺔ‬ ‫ﻋﻭﺍﻤل‬ ‫ﻋﺩﺓ‬ ‫ﺍﻻﻋﺘﺒﺎﺭ‬ ‫ﺒﻨﻅﺭ‬ ‫ﺍﻻﺨﺫ‬ ‫ﻴﺠﺏ‬ ‫ﺍﻻﻋﻤﺩﺓ‬ ‫ﻫﺫﻩ‬ ‫ﻟﺘﺼﻤﻴﻡ‬ , ‫ﺍﻟﻐﺎﺯ‬ ‫ﺃﺤﺘﺠﺎﺯ‬ ‫ﻨﺴﺒﺔ‬ g ε ‫ﻤﻌﺎﻤل‬ ‫ﺍﻟﻜﺘﻠﺔ‬ ‫ﺍﻨﺘﻘﺎل‬) (K La , ‫ﺍﻟ‬ ‫ﺯﻤﻥ‬ ‫ﺨﻠﻁ‬) (tm ‫ﺍﻟﺩﻭﺭ‬ ‫ﻭﺯﻤﻥ‬ ‫ﺍﻥ‬) tc (‫ﻤـﻥ‬ ‫ﻜـﻼ‬ ‫ﺘـﺄﺜﻴﺭ‬ ‫ﺩﺭﺍﺴﺔ‬ ‫ﺍﻟﺒﺤﺙ‬ ‫ﻴﺘﻀﻤﻥ‬ ‫ﺍﻟﺴﺎﺌل‬ ‫ﻟﻠﻁﻭﺭ‬ ‫ﺍﻟﻔﻴﺯﻴﺎﻭﻴﺔ‬ ‫ﻭﺍﻟﺨﻭﺍﺹ‬ ‫ﺍﻟﻐﺎﺯ‬ ‫ﺴﺭﻋﺔ‬) ‫ﻨﻴﻭﺘﻭﻨﻲ‬ ‫ﻏﻴﺭ‬ ‫ﺍﻡ‬ ‫ﻨﻴﻭﺘﻭﻨﻲ‬ (‫ﺍﻟﺘﺎﻟﻴﺔ‬ ‫ﺍﻟﻌﻭﺍﻤل‬ ‫ﻋﻠﻰ‬ : ‫ﺃﻭﻻ‬ :-‫ﻟﻠﻐﺎﺯ‬ ‫ﺍﻟﺤﺠﻤﻴﺔ‬ ‫ﺍﻟﻨﺴﺒﺔ‬ Gas holdup ‫ﺜﺎﻨﻴﺎ‬ :-‫ﺍﻟﻜﺘﻠﺔ‬ ‫ﺍﻨﺘﻘﺎل‬ ‫ﻤﻌﺎﻤل‬ mass transfer coefficient ‫ﺜﺎﻟﺜﺎ‬ :-‫ﺍﻟﺨﻠﻁ‬ ‫ﻭﻗﺕ‬ mixing time PDF created with pdfFactory Pro trial version www.pdffactory.com