Enrichment Of Heavy Water Research Articles

An Analytical Study of Separation Efficiency on the Enrichment of Heavy Water in Double-Flow Thermal-Diffusion Columns with Flow-Rate Fraction Variations

Considerable improvement in heavy water separation efficiency in a thermal diffusion column is obtainable by inserting an impermeable sheet or permeable barrier in parallel to divide an open duct into two subchannels for double-flow operations. The analytical results developed and investigated using an orthogonal expansion technique are represented graphically and compared with that in a Clusius-Dickel column of the same size. The impermeable-sheet or permeable-barrier location effect on heavy water separation efficiency enhancement is also discussed.

Theoretical and Experimental Studies on the Heavy Water Enrichment by Thermal Diffusion for Improved Performance Under Countercurrent‐Flow Frazier Scheme and Flow‐Rate Fraction Variations

The separation equation for heavy water enrichment by thermal diffusion in countercurrent‐flow Frazier schemes has been derived and the average value of concentration‐product term was treated separately in the enriching and stripping sections. The effect of the flow‐rate fraction variation of a countercurrent‐flow device on separation efficiencies for a H2O–HDO–D2O system, has also been investigated theoretically and experimentally. A qualitative agreement is achieved between the analytical predictions and experimental results. The analytical predictions are represented graphically and are compared with that in a classical Frazier scheme of the concurrent‐flow device. Considerable improvement in the device performance is obtained by using a countercurrent‐flow Frazier scheme with flow‐rate fraction variations, instead of using a concurrent‐flow device.

Effects of Inclined Angle and Aspect Ratio on Heavy Water Separation Efficiencies in Double‐Flow Thermal‐Diffusion Columns with External Refluxes

The heavy water separation efficiency enhancement in double‐flow, by inserting an impermeable sheet or a permeable barrier into double‐flow thermal‐diffusion columns with external refluxes at the ends has been investigated analytically. The analysis is conducted when using an orthogonal expansion technique. The separation efficiencies are compared with conventional Clusius–Dickel columns of the same size. Considerable improvements in heavy water enrichment in double‐flow thermal‐diffusion columns can be obtained by increasing the inclined angle and/or by decreasing the aspect ratio. Analytical results also show that both the recycle ratio and the position of insertion are important design parameters.

Improvement in Performance of Thermal Diffusion Columns on Heavy Water Enrichment under Sidestream Operations and Flow-Rate Fraction Variations

ABSTRACTDevelopment of the separation equation in a classical Clusius-Dickel column with sidestream operations for the heavy water enrichment has been accomplished theoretically. Performance of the modified Clusius-Dickel column with sidestream operations and its corresponding maximum separation was determined with the sidestream flow-rate ratio at the feed position and top flow-rate fraction as parameters. The effect of the sidestream operation of a modified Clusius-Dickel column on separation efficiencies for the H2O-HDO-D2O system has been investigated theoretically and experimentally. The theoretical predictions were in good agreement with the experimental results. The theoretical results indicated that the maximum separation efficiency increases with the side stream flow-rate fraction but decreases with feed flow rate and are represented graphically and compared with that in a classical Clusius-Dickel column. Considerable improvement in the device performance is obtained by employing a modified Clusius-Dickel column under sidestream operations and flow-rate fraction variations, instead of using a classical Clusius-Dickel column.

The Study of Continuous Thermal-Diffusion Columns on Modified Frazier-Scheme for the Enrichment of Heavy Water with Column Length Varied at a Constant Ratio

A study of heavy water in continuous thermal-diffusion columns on modified Frazier-scheme, resulting in substantial improvement of the separation efficiency of heavy water, was developed and investigated with column length varied at a constant ratio and with flow-rate fraction variations. The analytical results are represented graphically and compared with that in a classical Frazier-scheme of the same column length. Considerable improvement in the enrichment of heavy water was obtained by employing such a modified Frazier-scheme, with column length varied at a constant ratio and with flow-rate fraction variations instead of using a classical Frazier-scheme thermal diffusion column with the same column length. The effect of the ratio of column length and the column number as well as the flow-rate fraction variation on the enhancement of the separation efficiency of heavy water is discussed.

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.

AN ANALYTICAL STUDY ON THE ENRICHMENT OF HEAVY WATER IN THE CONTINUOUS THERMAL-DIFFUSION COLUMN WITH EXTERNAL REFLUXES

A new device of inserting an impermeable sheet or a permeable barrier to divide the thermal-diffusion columns into two subchannels with external refluxes at the ends, resulting in substantial improvement of the separation efficiency of heavy water, has been developed and investigated using orthogonal expansion technique. The analytical results are represented graphically and compared with that in a Clusius–Dickel column of the same size with recycle. Considerable improvement on enrichment of heavy water is obtained by employing such devices with an impermeable sheet or a permeable barrier instead of using the Clusius–Dickel thermal-diffusion column. The effect of sheet or barrier location on the enhancement of the separation efficiency of heavy water has also been discussed.

Further study on the enrichment of heavy water in continuous-type thermal-diffusion columns

The separation equations for the enrichment of heavy water in the continuous-type thermal-diffusion columns have been derived by treating the enriching and stripping sections separately. The experimental works for the separation of H2O–HDO–D2O system have been also conducted. The present theoretical predictions are in better agreement with the experimental results than those predicted in previous works, in which the average value of concentration–product term was taken as one at the feed position, while in the present study it was made separately in enriching and stripping sections.

Enrichment of Heavy Water in Spiral Wired Thermal Diffusion Columns of the Frazier Scheme

A separation theory for the enrichment of heavy water in the Frazier scheme of concentric-tube thermal diffusion columns with a tight fitting wire spiral, having a diameter equal to the annular spacing, wrapped on the entire inner tube, has been developed. Equations for the best wire angle of inclination for maximum separation, maximum production rate and minimum column height have been derived. Considerable improvement in performance is obtainable if the wire spiral is employed in the column at the optimum angle, instead of the absence of wire spiral, so that the convection strength can be properly reduced and controlled, resulting in suppression of the undesirable remixing effect while still preserving the desirable cascading effect.

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.

ENRICHMENT OF HEAVY WATER BY THERMAL DIFFUSION IN COUNTERCURRENT-FLOW FRAZIER SCHEME INCLINED FOR IMPROVED PERFORMANCE

The theory for enrichment of heavy water by thermal diffusion in a countercurrent-flow inclined Frazier scheme was developed and investigated. The equations for the optimal angles of inclination and the corresponding best performance were derived. Considerable improvement in performance is obtained when the Frazier scheme is operated at the optimal angle of inclination. Further improvement can be achieved if the operation is conducted in countercurrent flow instead of concurrent flow.

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

Based on the operating and fixed charge kept unchanged, considerable improvement in the performance for enrichment of heavy water in a batch-type flat-plate thermal diffusion column is obtainable if operation is carried out by increasing the inclined angle and/or by decreasing the plate spacing. However, decreasing the plate spacing will lead to decreasing the 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 of the frazier scheme with the optimal plate aspect ratio for best performance

AbstractThe solutions of the optimum plate aspect ratio as well as the corresponding maximum separation, maximum production rate and minimum plate surface area in thermal diffusion columns of the Frazier scheme for enrichment of heavy water have been obtained, analogous to those obtained in the previous work for separation of a binary system. It was found that all the optimum plate aspect ratios do not depend on feed concentration, while the corresponding best performances do. It is found that considerable improvement in performance is obtained when the operation is carried out with the optimal plate aspect ratio.

Simplified analysis of the enrichment of heavy water in a batch thermal-diffusion column

Simpler, but still precise, equations of separation that apply to the whole range of concentration for the enrichment of heavy water in a batch-type thermal-diffusion column have been derived by considering the concentration to be of constant pseudoquadratic form. The theoretical predictions compare qualitatively well with the experimental results of previous studies. The present modified equations of separation are easier to use than those obtained in previous studies for optimum design and operation of a batch-type thermal diffusion column for enrichment of heavy water, while the degrees of precision of the present and previous theoretical predictions from the experimental data are almost the same.

ENRICHMENT OF HEAVY WATER BY THERMAL DIFFUSION

Equations of the best wire angle of inclination for the maximum separation, maximum output and minimum column height for enrichment of heavy water in a concentric-tube wired thermal diffusion column have been derived. Considerable improvements in performance were obtained by employing the wired column instead of using the open column (without wire). It was also found that the wire inclination for maximum separation is also the wire inclination required to obtain the maximum production rate, or minimum column height, for a specified degree of separation.

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

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

Enrichment of Heavy Water in Flat-Plate Thermal Diffusion Columns of the Frazier Scheme Inclined for Improved Performance

A separation theory for the enrichment of heavy water in flat-plate thermal diffusion columns of the Frazier scheme inclined for improved performance has been developed. Equations for the best angle of inclination and maximum separation have been derived. Considerable improvement in separation is obtainable if the columns are inclined at the best angle, so that the convective strength can be properly reduced and controlled, resulting in suppression of the undesirable remixing effect while still preserving the desirable cascading effect.

Separation of Heavy Water by Vapor-Phase Thermal Diffusion Coupled with Distillation and Condensation

A study on the enrichment of heavy water in a vapor-phase thermal-diffusion column has been conducted. With the combination of the effects of distillation, vapor-phase thermal diffusion, and partial condensation, considerable improvement in the degree of enrichment has been achieved in a vapor-phase column rather than in a liquid-phase column. It was also found that even the part of enrichment contributed only by vapor-phase thermal-diffusion effect is much higher than that obtained by liquid-phase thermal diffusion.

The Simplified Equation of Separation for the Enrichment of Heavy Water in a Batch-Type Thermal Diffusion Column

A simple but precise equation of separation for the enrichment of heavy water in a batch-type thermal diffusion column has been derived with the consideration of a pseudobinary mixture. The experim...

Experimental Studies on the Separation of Deuterium Oxide in Continuous Thermal Diffusion Column for Low Concentration Range

Abstract Separation equations for the enrichment of heavy water in a continuous-flow thermal diffusion column have been derived for low-concentration operations. Experimentals on two feed concentrations of the H2O-HDO-D2O system have also been conducted, and the results quantitatively confirm the predictions of theory.