The Improvement of Thermal Diffusion Performance in the Modified Frazier Scheme by Increasing the Column Heights at a Constant Ratio

The effects of column number and the variation of column heights on thermal diffusion along the modified Frazier scheme, has been investigated with the total sum of column heights fixed. The equations, which may be employed to predict the optimal number of columns and the optimal column-height ratio for the maximum separation, have been derived. Considerable improvement in performance is obtainable if the column-height ratio and/or column number in a modified Frazier scheme with the total sum of column heights fixed are properly assigned for a certain flow-rate operation, instead of using the conventional Frazier scheme of uniform column height with the same total sum of column heights.     

Thermal diffusion in the modified Frazier schemes with column heights varied at a constant increment for improved performance

The effects of column number and column-height increment on the degree of separation in the modified Frazier scheme of thermal diffusion columns with the total sum of column heights fixed, has been investigated. The equations, which may be employed to predict the optimal column number and the optimal column-height increment for the maximum separation, have been derived. Considerable improvement in performance is obtainable if the column number and column-height increment in a modified Frazier scheme with the total sum of column heights fixed, are properly assigned under a certain flow-rate operation, instead of using the conventional Frazier scheme of constant column height with the same total sum of column heights.     

THE PROPER COLUMN NUMBER FOR BEST PERFORMANCE IN THERMAL DIFFUSION COLUMNS OF THE FRAZIER SCHEME WITH TOTAL SUM OF COLUMN HEIGHT FIXED

The effect of column number on the Frazier scheme performances with total sum of column heights fixed has been investigated. The equations that may be employed to predict the optimal number of columns (generally not integers) for the maximum performance are derived. Accordingly, the proper number of columns, which are the integers nearest to and smaller than the optimal column numbers, are obtained for practical applications. Considerable improvement in performance is obtainable if the scheme is constructed with the proper number of thermal diffusion columns, instead of using a single column, with the same total sum of column heights.     

Enrichment of Heavy Water by Thermal Diffusion in the Frazier Schemes with Column Heights Varied at a Constant Increment for Improved Performance

The improvement of heavy water enrichment by thermal diffusion in the Frazier scheme with column heights varied at a constant increment and with the total sum of column heights fixed, has been investigated. The equations, which may be employed to predict the optimal column number and the optimal column-height increment for maximum separation, have been derived. Considerable improvement in heavy water enrichment is obtainable if the column number and column-height increment in a modified Frazier scheme with the total sum of column heights fixed, are property assigned under certain flow-rate operation, instead of using the conventional scheme of uniform column height.     

The Optimum Column Number for the Best Performance of Thermal Diffusion in the Frazier Scheme with the Total Sum of Column Height Fixed

The effect of column number N, as well as the column height h of thermal diffusion columns, on the degree of separation in the Frazier scheme with the total sum of the column height L (=Nh) fixed, has been investigated. The equations, which may be employed to predict the optimum column number N* for the maximum separation Δ _N,max, have been derived. Considerable performance in separation is obtainable if the column number, as well as the column height, in a Frazier scheme with the total sum of the column height fixed is properly assigned for a certain flow-rate operation.     

The best performance of spiral wired thermal diffusion columns of the frazier scheme

Equations have been derived for the optimum wire angles of inclination for maximum separation, maximum production rate and minimum column height in the Frazier scheme of concentric‐tube thermal diffusion columns with a tight fitting wire spiral, having a diameter equal to the annular spacing, and wrapped on the entire inner tube. Considerable improvement in performance is obtained when a Frazier scheme is operated at the optimum corresponding wire angle of inclination, especially for the scheme of high column number.     

The best performance of inclined thermal diffusion columns of the frazier scheme

The equations for the best angles of inclination for maximum separation, maximum production rate and minimum column length in inclined flat-plate thermal-diffusion columns of the Frazier scheme, have been derived. Considerable improvement in performance is obtained when a Frazier scheme is operated at the best corresponding angle of inclination, especially for the schemes of high column number.     

The optimum plate aspect ratio for the best performance in a flat-plate thermal diffusion column of the frazier scheme

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

OPTIMAL PLATE ASPECT RATIO FOR THE BEST PERFORMANCE OF THE ENRICHMENT OF HEAVY WATER IN THERMAL-DIFFUSION COLUMNS OF A COUNTERCURRENT-FLOW FRAZIER SCHEME

The effect of plate aspect ratio on the performance of enrichment of heavy water in thermal-diffusion columns of a countercurrent-flow Frazier scheme was investigated. The equation for the optimal plate aspect ratios and the corresponding best performance were derived. Considerable improvement in performance is obtained when thermal-diffusion columns are operated at the optimal plate aspect ratio. Further improvement can be achieved if the scheme is connected and operated in countercurrent flow, instead of concurrent flow.     

OPTIMAL PLATE ASPECT RATIO FOR THE BEST PERFORMANCE OF THE ENRICHMENT OF HEAVY WATER IN THERMAL-DIFFUSION COLUMNS OF A COUNTERCURRENT-FLOW FRAZIER SCHEME

The effect of plate aspect ratio on the performance of enrichment of heavy water in thermal-diffusion columns of a countercurrent-flow Frazier scheme was investigated. The equation for the optimal plate aspect ratios and the corresponding best performance were derived. Considerable improvement in performance is obtained when thermal-diffusion columns are operated at the optimal plate aspect ratio. Further improvement can be achieved if the scheme is connected and operated in countercurrent flow, instead of concurrent flow.     

Thermal diffusion in inclined flat-plate columns of the frazier scheme

The separation theory of thermal diffusion in inclined flat-plate columns of the Frazier scheme has been developed and investigated. The equations for the best angle of inclination and maximum separation have been derived. Considerable improvement in separation is obtained when thermal diffusion columns are operated at the best angle of inclination.     

Modified Separation Theory of Heavy Water Enrichment by Thermal Diffusion in the Cocurrent-Flow Frazier Schemes

The separation theory for heavy water enrichment from water-isotope mixture in the cocurrent-flow Frazier scheme of thermal diffusion columns, has been modified with the values of pseudo product form of concentration determined by the method of least squares method, instead of simply taking the concentration in the product form as the feed concentration performed in previous works. The results indicate that serious errors occurred for the estimation of heavy water enrichment in the previous works, especially for employing the Frazier scheme with a larger number of thermal diffusion columns.     

Recovery of Deuterium from Water‐Isotopes Mixture in Flat‐Plate Thermal‐Diffusion Columns of the FRAZIER Scheme with Optimal Plate Aspect Ratio for Improved Performance

Abstract

The equations for estimating the optimal plate aspect ratio as well as the corresponding maximum recovery, maximum production rate, and minimum plate surface area for recovery of deuterium from water‐isotopes mixture in flat‐plate thermal diffusion columns of the Frazier scheme, have been derived. Considerable improvement in performance is obtainable if the operation is carried out with the optimal plate aspect ratio. It was found that all the optimal plate aspect ratios, as well as the improvements in performance, do not depend on feed concentration.     

Enrichment of heavy water in flat‐plate thermal diffusion columns of the frazier scheme with the optimal plate aspect ratio for best performance

The 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.     

PREDICTION OF SOLUTE CONCENTRATION CHANGES ALONG PULSED SIEVE PLATE EXTRACTION COLUMNS

Pulsed columns are one of the most important extraction columns that have extensive application in different industries. Obtaining the solute concentration in different heights of the column has a great influence on achieving the physical property changes of the phases along the column. An experimental work of mass transfer in a pilot pulsed sieve plate extraction column at different operating conditions is carried out in this research, and the solute concentration in different heights of the column is obtained for two different systems with medium and high interfacial tensions. The solute concentration changes along the column are calculated using previous models in the literature and the model presented for achieving the effective diffusivity in a previous work of the present authors. Comparison of the experimental results and the models is made and the best one is suggested.     

PREDICTION OF MASS TRANSFER COEFFICIENTS IN REGULAR PACKED COLUMNS

Developments in the area of packed columns, particularly structured packed columns, are ongoing, specifically in the area of liquid-liquid extractions. Accurate predictions of mass transfer coefficients lead to more accurate design of columns. In the present study, mass transfer coefficients were measured experimentally for packed columns of different heights to study the effect of packing height and specific area. Two experimental pilot regular packed extraction columns were examined using toluene/acetic acid/water and n-butyl acetate/acetic acid/water systems. Based on the results, a novel model for prediction of effective diffusivity has been proposed that is a function of column height and specific area. The mass transfer coefficients obtained by this prediction were compared with other models. The results of this new model are in good agreement with the experimental data. Therefore, this new model can be used to design better regular packed columns.     

New predictive correlation for mass transfer coefficient in structured packed extraction columns

Developments in the area of packed columns, particularly structured packed columns, are ongoing, specifically in the area of liquid–liquid extractions in different industries. In the present study, mass transfer coefficients have been obtained experimentally in a structured packed extraction column to develop a new correlation for prediction of continuous phase Sherwood number. The experiments were carried out for toluene/acetic acid/water and n-butyl acetate/acetic acid/water systems with counter current flow in different heights of column. A new dimensionless parameter, d₃₂/h, is introduced in proposed equation. This number considers the effect of column height (h) and mean drop diameter (d₃₂) jointly. The main advantage of this approach is that the principal effect of column height is considered in correlation without which the experimental data could not be fitted with a acceptable accuracy.     

甲基氯硅烷精馏流程的模拟与优化

采用Aspen plus软件对工业七塔精馏过程进行全流程建模与模拟,优化工艺参数,研究了新的精馏节能工艺。对一甲塔等7个精馏塔采用双因素水平的灵敏度分析,考察了塔釜采出率、回流比、进料位置和塔顶压力对产品浓度和热负荷的影响,确定一甲塔最优的工艺参数：塔釜摩尔采出率为0.92,摩尔回流比为130,塔顶压力为0.18 MPa,总理论板数为400,在210块理论板位置进料。在此基础上,针对高能耗的脱高塔/脱低塔,模拟研究了双效精馏新工艺,新工艺可节省39.70%的年总成本;针对一甲塔模拟研究了热泵精馏新工艺,新工艺可降低41.42%的年总成本。     

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.     

THE OPTIMUM PLATE-SPACING FOR THE BEST PERFORMANCE IN FLAT-PLATE THERMAL DIFFUSION COLUMNS OF THE FRAZIER SCHEME

The effect of plate spacing on the degree of separation and production rate 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 the thermal diffusion columns with optimum plate-spacing are employed for operation.