Jairam gopal - Academia.edu (original) (raw)

Papers by Jairam gopal

Industrial & Engineering Chemistry Process Design and Development, 1985

Solubility data for mixtures of naphthalene wlth phenanthrene, phenol, and biphenyl in supercriti... more Solubility data for mixtures of naphthalene wlth phenanthrene, phenol, and biphenyl in supercritical carbon dioxide were obtained. The equilibrium solubilities were measured in a semicontinuous flow apparatus. Experiments were conducted at 308 and 318 K isotherms, over a pressure range of 5 to 28 MPa. Selectivity of carbon dioxide to dissolve these heavy components preferentially is discussed as a function of pressure and extent of solubliity.

The Canadian Journal of Chemical Engineering, 1983

The role of vapor liquid equilibrium in the coal liquefaction process and its effect on the proce... more The role of vapor liquid equilibrium in the coal liquefaction process and its effect on the process kineticswere studied. Available experimental data were analyzed by inclusion of vapor-liquid equilibrium in an existing model to study its effect on the kinetics. The analysis showed that due to liquid vaporization, a significant increase in the slurry residence time occurs. In the range of operating variables investigated. the actual slurry residence time was observed to be higher by a factor of I. I4 to 1.41. Model simulations for some typical operating conditions (717-737 K , 13.8-20.7 MPa) showed the wt. fraction of liquid vaporized to be in the range of 0. I to 0.3. This is seen to be in agreement with published data on the volatility of typical coal liquids. This study has shown that consideration of vapor-liquid equilibrium in the kinetics and design of coal liquefaction process can be of importance. especially at high temperatures, where vaporization would be significant.

The Canadian Journal of Chemical Engineering, 1982

The hydrodynamic and mass transfer characteristics of bubble and packed bubble columns with downc... more The hydrodynamic and mass transfer characteristics of bubble and packed bubble columns with downcomer were investigated. The contactor consisted of two concentric columns of 0.1 1 and 0.2 m i.d., with the annulus acting as the downcomer. The packing used in this investigation was standard 16 mm stainless steel Pall rings. The superficial gas and liquid velocities, Vcj and VL, were varied from 0.01 to 0.09 and I X 10-' to 8.8 x lo-' m s-' respectively. Two flow patterns, namely the bubble and pulse flows were observed in the packed bubble column with downcomer. as shown by a flow map. The liquid circulation velocity in both the contactors was observed to be constant throughout the ranges of V, and V, covered in this work. The effect of liquid viscosity (0.8 to 9.5 mPa.s) and surface tension (45 to 72 mN m-') on the flow pattern, liquid circulation, gas holdup and pressure drop was investigated. The pressure drop characteristics across the two contactors have been compared with those across a bubble column. Values of the effective interfacial area, a, and the volumetric mass transfer coefficient, kL a, were measured by using chemical methods. Values of a as high as 180 and 700 m and kLa as high as 0.075 and 0.22 s-', in the bubble and packed bubble columns with downcomer, respectively, were obtained. The values of true liquid-side mass transfer coefficient, kL, were found to be independent of Vo and were of the order of 5.5 X and 3.5 X I0-j m s-' , respectively, in the two contactors. .~ On a Ctudie les caracttristiques de I'hydrodynamique et du transfert de masse des colonnes bulles et des colonnes B bulles avec garnissage et dbverse. Les contacteurs consistaient en 2 colonnes concentriques dont les diametres interieurs Ctaient respectivement 0.1 1 et 0.2 m., I'espace annulaire servant de deverse. Le garnissage employe Ctait des anneaux Pall en acier inoxydable de 16 mm. On a fait varier respectivement les vitesses superficielles du gaz et du liquide (V , et V,) de 0.01 a 0.09 et 1 x Dans la colonne a bulles avec garnissage et deverse, on a observe deux regimes d'ecoulement, h savoir I'ecoulement B bulles et le regime pulse representes sur un diagramme d'ecoulement. On a constate que la vitesse de circulation du liquide dans les deux contacteurs Ctait constante sur toute la gamme de V,, et VL couverte dans le present travail. On a Ctudie l'effet de la viscosite du liquide (0.8-9.5 mPa-s) et de la tension superficielle (45-72 mN rn-') sur le regime d'ecoulement, sur la circulation du liquide, sur la retention du gaz et sur la perte de charge. On a compare les pertes du charge des deux contacteurs avec celles de la colonne a bulles. On a mesure, par des mtthodes chimiques, les valeurs de I'aire interfaciale effective a et du coefficient volumktrique de transfert de masse kLa. On a obtenu des valeurs de a allant jusqu'h 180 et 700 m-' et des valeurs de kL a allant jusqu'a ' Presently post-doctoral fellow, Department of Chemical Engineering,

The Canadian Journal of Chemical Engineering, 1983

The mass transfer characteristics of 0.2.0.6 and I .0 m diameter bubble columns having a low heig... more The mass transfer characteristics of 0.2.0.6 and I .0 m diameter bubble columns having a low height to diameter ratio (0.6 < H / D < 4) and operated at low superficial gas velocities (0.01 < Vcj < 0.08 m/s) wcre investigated. Different types of spargers were used to study their effect on the column performance. The values of effective interfacial area. a, and volumetric mass transfer coefficient, kLa. were measured by using chemical methods. The values of a and kL.a were found to vary from 40 to 420 m2/m' of clear liquid volume and from 0.01 to 0.16 s-' , respectively. in the range of VG and VL. covered in this investigation. The value of the liquid-side mass transfer coefficient. kL, was found to vary from 3 x 10 m/s. The effect of the physical properties of the system on the values of a was also investigated. The height to diameter ratio and the column diameter did not have significant effect on the values of gas holdup. a and k,.a. It was found that the sparger design is not of critical importance, provided multipoint/multiorificc gas spargers are used. The comparative performance of bubble columns having low H / D with horizontal spargcd contactors and tall bubble columns has been considered. to 7 x 10 On a CtudiC les caracteristiques du transfert de m a w de colonncs bulles de diametres 0.2. 0.6 et 1 .0 m, avec un rapport hauteurldiametre faible (0.6 < H / D < 4) et pour de faibles vitesses superficielles du gas (0.01 < V , < 0.08 m/s). On a employe plusieurs types de barboteurs pour Otudier leur effet sur la performance des colonnes. On a mesure, au moyen de mtthodes chimiqucs, Ies valeurs de I'aire interfaciale effective (a) et le cocfficient de transfcrt de masse volumetrique (k,.a). On a trouve que les valeurs de a et kLa varient respectivement entre 40 et 420 m'/m' de volume de liquide clair et de 0.01 a 0.16 s ' sur les gammes dc V,; et V,, couvertes dans la presente etude.

The Canadian Journal of Chemical Engineering, 1980

Fuel, 1984

An experimental apparatus was developed to inject coal into an autoclave containing preheated sup... more An experimental apparatus was developed to inject coal into an autoclave containing preheated supercritical water. The supercritical water appears to act as both solvent and reactant in the conversion of coal to gases and liquids. Experiments were carried out with German brown coal, lignite and bituminous coal and with glucose at both subcritical and supercritical water densities. A significantly larger quantity of char was obtained when operating at subcritical densities and when the coal was mixed with water before heating to supercritical conditions. Smaller amounts of char were obtained as density increased and as reaction time increased.

Industrial & Engineering Chemistry Process Design and Development, 1985

Solubility data for mixtures of naphthalene wlth phenanthrene, phenol, and biphenyl in supercriti... more Solubility data for mixtures of naphthalene wlth phenanthrene, phenol, and biphenyl in supercritical carbon dioxide were obtained. The equilibrium solubilities were measured in a semicontinuous flow apparatus. Experiments were conducted at 308 and 318 K isotherms, over a pressure range of 5 to 28 MPa. Selectivity of carbon dioxide to dissolve these heavy components preferentially is discussed as a function of pressure and extent of solubliity.

The Canadian Journal of Chemical Engineering, 1983

The role of vapor liquid equilibrium in the coal liquefaction process and its effect on the proce... more The role of vapor liquid equilibrium in the coal liquefaction process and its effect on the process kineticswere studied. Available experimental data were analyzed by inclusion of vapor-liquid equilibrium in an existing model to study its effect on the kinetics. The analysis showed that due to liquid vaporization, a significant increase in the slurry residence time occurs. In the range of operating variables investigated. the actual slurry residence time was observed to be higher by a factor of I. I4 to 1.41. Model simulations for some typical operating conditions (717-737 K , 13.8-20.7 MPa) showed the wt. fraction of liquid vaporized to be in the range of 0. I to 0.3. This is seen to be in agreement with published data on the volatility of typical coal liquids. This study has shown that consideration of vapor-liquid equilibrium in the kinetics and design of coal liquefaction process can be of importance. especially at high temperatures, where vaporization would be significant.

The Canadian Journal of Chemical Engineering, 1982

The hydrodynamic and mass transfer characteristics of bubble and packed bubble columns with downc... more The hydrodynamic and mass transfer characteristics of bubble and packed bubble columns with downcomer were investigated. The contactor consisted of two concentric columns of 0.1 1 and 0.2 m i.d., with the annulus acting as the downcomer. The packing used in this investigation was standard 16 mm stainless steel Pall rings. The superficial gas and liquid velocities, Vcj and VL, were varied from 0.01 to 0.09 and I X 10-' to 8.8 x lo-' m s-' respectively. Two flow patterns, namely the bubble and pulse flows were observed in the packed bubble column with downcomer. as shown by a flow map. The liquid circulation velocity in both the contactors was observed to be constant throughout the ranges of V, and V, covered in this work. The effect of liquid viscosity (0.8 to 9.5 mPa.s) and surface tension (45 to 72 mN m-') on the flow pattern, liquid circulation, gas holdup and pressure drop was investigated. The pressure drop characteristics across the two contactors have been compared with those across a bubble column. Values of the effective interfacial area, a, and the volumetric mass transfer coefficient, kL a, were measured by using chemical methods. Values of a as high as 180 and 700 m and kLa as high as 0.075 and 0.22 s-', in the bubble and packed bubble columns with downcomer, respectively, were obtained. The values of true liquid-side mass transfer coefficient, kL, were found to be independent of Vo and were of the order of 5.5 X and 3.5 X I0-j m s-' , respectively, in the two contactors. .~ On a Ctudie les caracttristiques de I'hydrodynamique et du transfert de masse des colonnes bulles et des colonnes B bulles avec garnissage et dbverse. Les contacteurs consistaient en 2 colonnes concentriques dont les diametres interieurs Ctaient respectivement 0.1 1 et 0.2 m., I'espace annulaire servant de deverse. Le garnissage employe Ctait des anneaux Pall en acier inoxydable de 16 mm. On a fait varier respectivement les vitesses superficielles du gaz et du liquide (V , et V,) de 0.01 a 0.09 et 1 x Dans la colonne a bulles avec garnissage et deverse, on a observe deux regimes d'ecoulement, h savoir I'ecoulement B bulles et le regime pulse representes sur un diagramme d'ecoulement. On a constate que la vitesse de circulation du liquide dans les deux contacteurs Ctait constante sur toute la gamme de V,, et VL couverte dans le present travail. On a Ctudie l'effet de la viscosite du liquide (0.8-9.5 mPa-s) et de la tension superficielle (45-72 mN rn-') sur le regime d'ecoulement, sur la circulation du liquide, sur la retention du gaz et sur la perte de charge. On a compare les pertes du charge des deux contacteurs avec celles de la colonne a bulles. On a mesure, par des mtthodes chimiques, les valeurs de I'aire interfaciale effective a et du coefficient volumktrique de transfert de masse kLa. On a obtenu des valeurs de a allant jusqu'h 180 et 700 m-' et des valeurs de kL a allant jusqu'a ' Presently post-doctoral fellow, Department of Chemical Engineering,

The Canadian Journal of Chemical Engineering, 1983

The mass transfer characteristics of 0.2.0.6 and I .0 m diameter bubble columns having a low heig... more The mass transfer characteristics of 0.2.0.6 and I .0 m diameter bubble columns having a low height to diameter ratio (0.6 < H / D < 4) and operated at low superficial gas velocities (0.01 < Vcj < 0.08 m/s) wcre investigated. Different types of spargers were used to study their effect on the column performance. The values of effective interfacial area. a, and volumetric mass transfer coefficient, kLa. were measured by using chemical methods. The values of a and kL.a were found to vary from 40 to 420 m2/m' of clear liquid volume and from 0.01 to 0.16 s-' , respectively. in the range of VG and VL. covered in this investigation. The value of the liquid-side mass transfer coefficient. kL, was found to vary from 3 x 10 m/s. The effect of the physical properties of the system on the values of a was also investigated. The height to diameter ratio and the column diameter did not have significant effect on the values of gas holdup. a and k,.a. It was found that the sparger design is not of critical importance, provided multipoint/multiorificc gas spargers are used. The comparative performance of bubble columns having low H / D with horizontal spargcd contactors and tall bubble columns has been considered. to 7 x 10 On a CtudiC les caracteristiques du transfert de m a w de colonncs bulles de diametres 0.2. 0.6 et 1 .0 m, avec un rapport hauteurldiametre faible (0.6 < H / D < 4) et pour de faibles vitesses superficielles du gas (0.01 < V , < 0.08 m/s). On a employe plusieurs types de barboteurs pour Otudier leur effet sur la performance des colonnes. On a mesure, au moyen de mtthodes chimiqucs, Ies valeurs de I'aire interfaciale effective (a) et le cocfficient de transfcrt de masse volumetrique (k,.a). On a trouve que les valeurs de a et kLa varient respectivement entre 40 et 420 m'/m' de volume de liquide clair et de 0.01 a 0.16 s ' sur les gammes dc V,; et V,, couvertes dans la presente etude.

The Canadian Journal of Chemical Engineering, 1980

Fuel, 1984

An experimental apparatus was developed to inject coal into an autoclave containing preheated sup... more An experimental apparatus was developed to inject coal into an autoclave containing preheated supercritical water. The supercritical water appears to act as both solvent and reactant in the conversion of coal to gases and liquids. Experiments were carried out with German brown coal, lignite and bituminous coal and with glucose at both subcritical and supercritical water densities. A significantly larger quantity of char was obtained when operating at subcritical densities and when the coal was mixed with water before heating to supercritical conditions. Smaller amounts of char were obtained as density increased and as reaction time increased.