Flat-plate Thermal Diffusion Columns Research Articles

Conjugated mass transfer in an inclined thermal-diffusion column for heavy water enrichment with plate aspect ratio variations

A two-dimensional mathematical model was developed theoretically to predict the degree of separation of heavy water in an inclined flat-plate thermal-diffusion column. An orthogonal expansion technique for solving separation problems of heavy water enrichment under plate aspect ratio and inclination angle variations was carried out analytically. The effects of plate aspect ratio and inclination angle on the degree of separation have been investigated with a consideration of a fixed operating expense. Considerable improvements in device performance are obtained if the thermal-diffusion columns are inclined at the optimal angles as compared to the vertical orientation. Further improvement can be achieved if the flow-rate fractions of top and bottom products are suitably adjusted.

Modeling of mass transfer Graetz problems in flat-plate thermal-diffusion columns for heavy water enrichment

The mass transfer Graetz problem of flat-plate thermal-diffusion columns for heavy water enrichment was investigated. An orthogonal expansion technique was used to solve the laminar counter-current flat-plate thermal-diffusion column separation problems under flow-rate fraction variations and feed position. The present theoretical predictions for the degree of separation were solved based on the separation variable method. Positive and negative eigen-values are needed for the enriching and stripping sections, respectively, during the calculation procedure. The results show that the degree of separation increases with decreasing the feed flow rate and the maximum degree of separation is obtained for feed positions δ = 0.5 and feed concentration C F = 0.385. Moreover, the theoretical predictions are in better agreement with the experimental results than those predicted using the transport equation in the previous works.

Recovery of deuterium from water–isotope mixture by thermal diffusion in countercurrent-flow flat-plate Frazier scheme with optimum plate spacing

The effect of plate spacing on the degree of recovery and production rate for deuterium recovery from water–isotope mixture in flat-plate thermal diffusion columns of countercurrent-flow Frazier scheme with fixed operation expense, has been investigated. The equations for estimating optimum plate spacing for maximum recovery and maximum production rate have been derived. Considerable improvement in performance is obtainable when thermal diffusion columns with optimum plate spacing are employed for operation. The fact that countercurrent-flow operation is more effective than cocurrent-flow operation for the recovery of deuterium in a Frazier scheme, is also confirmed.

Enrichment of heavy water in flat-plate thermal-diffusion columns with optimal plate aspect ratio

The optimum plate aspect ratios for maximum separation of heavy water, maximum production rate and minimum plate surface area in flat-plate thermal-diffusion column with plate surface area fixed, have been determined. Essential improvement in performance is obtainable if the column is constructed with the best plate aspect ratio, so that the desirable cascading effect can be enhanced, while the undesirable remixing effect can be properly reduced. The maximum separation and maximum production rate are achieved without changing any total expense, while the design with minimum plate surface area results in minimizing the total expense.

Optimal plate aspect ratio for the enrichment of heavy water from water–isotope mixture in a flat-plate thermal diffusion column with transverse sampling streams

Suitably adjusting the plate aspect ratio in a flat-plate thermal diffusion column is one of the flexible ways of properly controlling the convective strength, resulting in reducing the remixing effect while still preserving the effectively cascading effect, and thereby leading to improved separation. The optimal plate aspect ratios for the performances of the separation of heavy water from water–isotope mixture in flat-plate thermal diffusion columns with transverse sampling streams have been determined. The maximum separation and maximum production rate are achieved without changing the total expenditure, while the design with minimum plate surface area results in minimizing the total expenditure.

Effects of inclination angle and plate spacing on the enrichment of heavy water in continuous-type flat-plate thermal diffusion columns

Abstract The effects of inclination angle and plate spacing on the separation of heavy water from water isotope mixture in continuous-type flat-plate thermal diffusion columns, has been investigated with the consideration of a fixed operating expense. Although there do not exist simultaneously the optimal angle of inclination and optimal plate spacing for maximum separation, increasing either the inclination angle or plate spacing will increase, respectively, the optimal plate spacing or optimal inclination angle, as well as the corresponding maximum separations. The equations for the optimal inclination angle and optimal plate spacing, as well as the corresponding maximum separations, have been derived. Considerable improvement in separation is achievable if the operations are conducted with the optimal operating conditions.

Design of flat-plate thermal diffusion columns for enrichment of heavy water with transverse sampling streams

Although there does not exist simultaneously the optimal angle of inclination and optimal plate spacing for maximum separation of heavy water from water–isotope mixture in flat-plate thermal-diffusion columns, increasing either inclination angle or plate spacing will increase, respectively, the optimal plate spacing or optimal inclined angle, as well as the corresponding maximum separations. The equations for the optimal angle of inclination and optimal plate spacing, as well as the corresponding maximum separations, have been derived. Considerable improvement in separation is achievable if the operations are conducted with the optimal conditions.

Thermal diffusion in a countercurrent-flow Frazier scheme with optimum plate spacing for improved performance

The degree of separation and production rate for a binary mixture in a countercurrent-flow Frazier scheme with N flat-plate thermal-diffusion columns of the same size and with total fixed expense and with a variation of plate spacing have been investigated. The equations of estimating optimum plate spacing for maximum separation and for maximum production rate have been developed. Considerable improvements in performance (112% for the degree of separation and 748% for the production rate) were obtained when the thermal-diffusion columns with optimum plate spacing were used. The fact that countercurrent-flow operation was more effective than cocurrent-flow operation in a Frazier scheme, was also confirmed.

Effects of design parameters on enrichment of heavy water in batch-type flat-plate thermal diffusion columns

The influences of inclination angle, plate-spacing and plate aspect-ratio changes on the performance of batch-type flat-plate thermal diffusion columns that are used for the enrichment of heavy water from water–isotope mixtures have been investigated, while the total expense was kept unchanged. Considerable improvement in the performance is achievable if operation is carried out by increasing plate aspect ratio, and/or properly increasing the inclination angle and/or properly decreasing plate spacing. The temperature differences between hot and cold plates, needed for keeping the operating expense unchanged, are also described.

Design of batch-type flat-plate thermal diffusion columns for recovery of deuterium from water–isotopes mixture with energy consumption rate fixed

The effect of design parameters on the recovery of deuterium from the separation of water–isotope mixture in batch-type flat-plate thermal diffusion columns with the consideration of the energy consumption rate kept unchanged, have been investigated. It was found that considerable improvement in performance can be achieved by increasing the aspect ratio, as well as increasing the inclined angle and/or decreasing the plate spacing, resulting in reduced the remixing effect.

Effect of plate aspect ratio on the recovery of deuterium from water–isotope mixture in flat-plate thermal diffusion columns with transverse sampling streams

The optimal plate aspect ratios for the best recovery of deuterium from water–isotope mixture in flat-plate thermal diffusion columns with transverse sampling streams have been determined. The maximum recovery and maximum production rate are achieved without changing the total expenditure, while the design with minimum plate surface area results in minimizing the total expense.

Recovery of deuterium from water–isotope mixture by thermal diffusion in inclined Frazier scheme

A separation theory for the recovery of deuterium from water–isotope mixture in flat-plate thermal diffusion columns of the Frazier scheme inclined for improved performance has been developed. Equations for the optimal angles of inclination and the corresponding maximum recovery, maximum production rate and minimum column length have been derived. Considerable improvements in performance are obtainable if the columns are inclined at the best angles, so that the convective strength can be properly reduced and controlled, resulting in suppression of the undesirable remixing effect while still reserving the desirable cascading effect.

Recovery of deuterium from water-isotopes mixture in flat-plate thermal-diffusion columns of the Frazier scheme with optimum plate-spacing

The effect of plate-spacing on the degree of recovery and production rate for the recovery of deuterium from water-isotopes mixture in flat-plate thermal-diffusion columns of the Frazier scheme with fixed operation expense has been investigated. The equations for estimating optimum plate-spacing for maximum recovery and maximum production rate have been developed. Considerable improvement in performance is obtainable when thermal-diffusion columns with optimum plate-spacing are employed for operation.

Thermal Diffusion in a Countercurrent-Flow Frazier Scheme with Optimum Plate Aspect Ratio for the Best Performance

The effects of plate aspect ratio on the degree of separation and production rate in a countercurrent-flow Frazier scheme with N flat-plate thermal-diffusion columns of same size and with plate surface area fixed, have been investigated. The equations for estimating optimum plate aspect ratio for maximum separation and maximum production rate have been derived. Considerable improvement in performance is obtainable when the thermal diffusion columns with optimum plate aspect ratio are employed for operation. The fact that countercurrent-flow operation is more effective than cocurrent-flow operation in a Frazier scheme, is also cinfirmed.

Optimal plate aspect ratio for the improvement in recovery of deuterium from water-isotopes mixture in flat-plate thermal diffusion columns

The effects of plate aspect ratio on the degree of deuterium recovery, production rate and plate surface area in a flat-plate thermal diffusion column with plate surface area fixed, have been investigated. Theoretical considerations show that when the thermal diffusion columns are constructed with the best plate aspect ratio, maximum recovery of deuterium, maximum production rate or minimum plate surface area can be achieved. The optimal plate aspect ratio for maximum recovery of deuterium is obtained with given production rate and plate surface area, while that for maximum production rate is determined with the degree of deuterium recovery and plate surface area fixed, and that for minimum plate surface area is estimated with known degree of deuterium recovery and production rate. The maximum degree of separation and maximum production rate are achieved without changing any total expense, while the design with minimum plate surface area results in minimizing the total expense.

Optimum plate spacing for the best recovery of deuterium from water–isotopes mixture in flate-plate thermal-diffusion columns with total expense fixed

The optimum plate spacings for maximum recovery, maximum production rate and minimum column length in a flat-plate thermal-diffusion column for the improvement of deuterium (D) from water–isotopes mixture (H 2O–HDO–D 2O) have been determined. The recovery of deuterium was estimated from the degree of separation of HDO and D 2O. Considerable improvement in performance is obtainable if the plate spacing is suitably adjusted. The appropriate temperature differences between two vertical plates of a thermal-diffusion column for keeping the total expense fixed are also delineated.

Optimum Plate Spacing for the Best Performance of the Enrichment of Heavy Water in Thermal Diffusion Columns of a Countercurrent-Flow Frazier Scheme

The effect of plate spacing on the degree of separation and production rate for the enrichment of heavy water in a countercurrent-flow Frazier scheme with N flat-plate thermal diffusion columns of same size and with total expense fixed, has been investigated. The equations for estimating optimum plate spacing for maximum separation and maximum production rate have been developed. Considerable improvement in performance for the enrichment of heavy water is obtainable when the` thermal diffusion columns with optimum plate spacing are employed for operation. The fact that countercurrent-flow operation is more effective than concurrent-flow operation for the enrichment of heavy water in a Frazier scheme, is also confirmed.

Improvement in recovery of deuterium from water–isotopes mixture in inclined thermal-diffusion columns

The optimal angles of inclination for maximum recovery, maximum production rate and minimum column length in a continuous-type flat-plate thermal diffusion column inclined for the improvement in recovery of deuterium (D) from water–isotopes mixture (H 2O–HDO–D 2O), have been determined. The recovery of deuterium was estimated from the degrees of separation of HDO and D 2O. Considerable improvement in performance is obtainable if the column is tilted at the optimal angle of inclination, instead of being placed vertically, so that the convection strength can be properly reduced and controlled, resulting in suppressing the undesirable remixing effect while still preserving the desirable cascading effect.

Effects of Inclined Angle and Plate Spacing on the Degree of Separation in Batch-Type Flat-Plate Thermal Diffusion Columns

Effects of inclined angle and plate spacing on the degree of separation in batch-type flat-plate thermal diffusion columns, with operating expense and fixed charge kept unchanged, are discussed. It was found that the degree ofseparation increases when the inclined angle increases or when the platespacing decreases. However, decreasing the plate spacing will lead to decreasingthe amount of solution to be treated in the column, while increasing the inclined angle will enlarge the operating time for reaching the steady state.

Enrichment of heavy water in flat-plate thermal diffusion columns inclined for improved performance

The optimum angles of inclination for maximum separation, maximum production rate and minimum column length in a flat-plate thermal-diffusion column for enrichment of heavy water have been determined. Essential improvement in performance is obtainable if the column is tilted at the optimum angle, instead of being placed vertically, so that the convection strength can be properly reduced and controlled, resulting in suppressing the undesirable remixing effect while still preserving the desirable cascading effect. Accordingly, considerable saving in fixed and operating charges can be achieved, particularly for lower production rate operations, or for smaller degree of separation.