THERMAL DIFFUSION IN SPIRAL WIRED COLUMNS WITH TRANSVERSE SAMPLING STREAMS

The equations that may be employed to predict the optimum wire angles of inclination for performance in a concentric-tube thermal-diffusion column with a tight-fitting wire spiral, having a diameter equal to the annular spacing, wrapped on the entire inner tube, and operating with transverse sampling streams, have been derived. Considerable improvement in performance is obtainable if the wire angle is adjusted at the optimum angle, instead of the absence of a wire spiral, 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, essential savings in fixed charges and operating expense can be achieved, particularly for lower production rate operations or for a smaller degree of separation.     

热扩散塔分离甲烷和氢的实验研究

引言用甲烷直接合成C_2以上的碳氢化合物非常困难,例如,由甲烷脱氢合成乙烯,按热力学计算在1000K下甲烷的平衡转化率只有4.8％,所以至今甲烷仍主要用作燃料．为了充分利用这一化工基础原料,作者利用热扩散塔进行了甲烷的催化脱氢反应,使反应与分离同时进行,大幅度提高了甲烷的转化率．为考察热扩散的分离效果,本文用甲烷脱氢反应的主要成分甲烷和氢混合物为原料,在热扩散塔中分别进行了空塔和填料塔的热扩散分离实验,考察了一些操作参数对分离效果的影响,以期对反应操作条件提供必要的参考．l原理所谓热扩散现象,就是在温度场…     

THERMAL DIFFUSION IN A FLAT-PLATE COLUMN WITH TRANSVERSE SAMPLING STREAMS

The optimum angles of inclination for maximum separation, maximum production rate and minimum column length in a fiat-plate thermal diffusion column with transverse sampling streams, have been determined. Considerable 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.     

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.     

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.     

MASS TRANSFER IN LAMINAR FLOW IN CONCENTRIC-TUBE THERMAL-DIFFUSION COLUMNS FOR HEAVY WATER ENRICHMENT UNDER THE EFFECTS OF FLOW-RATE FRACTIONS AND RECYCLES

An orthogonal expansion technique for solving separation problems in laminar countercurrent concentric circular thermal-diffusion columns under flow-rate fraction variations is developed analytically and applied to heavy water enrichment. Experimental work for the H₂O–HDO–D₂O system has been also conducted. The present theoretical predictions are based on Sturmian theory, and positive and negative eigenvalues are needed for enriching and stripping sections, respectively, during the calculation procedure. The results show that the theoretical predictions are in better agreement with the experimental results than those predicted in previous works by using the transport equation.     

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.     

胶体超滤法去除水中低含量重金属离子

本文研究了用超滤膜去除水中胶态重金属离子氢氧化物的可能性。实验表明，选用一定孔径的ＣＮ－ＣＡ膜和Ｇ－ＣＳ膜可以有效地去除水中Ｃｕ＾２＋，Ｎｉ＾２＋，Ｃｄ＾２＋，Ｐｂ＾２＋，Ｚｎ＾２＋等金属离子的氢氧化物，实验所采用的方法还可用来研究氢氧化物的两性及金属离子随溶液ｐＨ值的变化而引起的化学形态的变化。     

EXPERIMENTAL STUDIES OF DIFFUSION FLUXES F TERNARY DISTILLATION OF THE ACETONE-METHANOL-ETHANOL YSTEMS BY A WETTED-WALL OLUMN

Measurements of mass and diffusion fluxes for ternary distillation of the acetone-methanol-ethanol systems were made by a wetted-wall column under total reflux conditions for wide ranges of the liquid concentrations. Intermediate component methanol showed peculiar behavior of a finite mass flux near the zero-driving force region. This was explained as being due to the effect of the interfacial velocity caused by mass fluxes of the other components. The diffusion fluxes were shown to be proportional to concentration driving forces, whereas the mass fluxes were not. Discussions on the use of the number of transfer units for correlation of mass transfer data in ternary distillation were also made.     

THE OPTIMUM PLATE-SPACING FOR THE BEST PERFORMANCE IN A FLAT-PLATE THERMAL DIFFUSION COLUMN WITH TRANSVERSE SAMPLING STREAMS

The equations for estimating optimum plate-spacing for maximum separation and for maximum production rate in a flat-plate thermal diffusion column with transverse sampling stream and with fixed operating expense, have been derived. Considerable improvement in performance is obtainable if the optimum plate-spacing is selected so that the convective strength can be properly reduced and controlled, resulting in suppressing the undesirable remixing effect while still preserving the desirable cascading effect and thereby leading to improved performance.     

THE DIFFUSION OF WATER VAPOUR THROUGH PULP AND PAPER

ABSTRACT

The diffusion of water vapour through pulp and paper was investigated experimentally in a diffusion cell. The diffusion cell consisted of two chambers differing in relative humidity. Any given sample was placed as a banier between the two chambers. Two pulp qualities and eleven paper grades were included in the investigation. The diffusivities measured ranged from 2.1.10^-8m²/s to 5.4.10^-6m²/. Effective vapour diffusivity was found to correlate with the density of the sheet. For five of the paper or pulp grades measurements were performed a t different temperatures and relative humidities. In the range of relative humidities investigated, effective vapour diffusivity was found to be independent of relative humidity.     

吸附法处理重金属废水研究进展

重金属离子严重危害人体健康,因此在废水处理中必须将其去除。传统去除重金属离子的方法很多,但都存在某些不足之处,而吸附法因其材料易得,价格低廉,去除效果好而受到人们的青睐,特别是近年发展起来的生物吸附技术,在水处理领域具有很好的应用前景。本文介绍了目前一些较为成熟的吸附法,同时探讨了今后吸附法去除重金属的发展趋势。     

生物法去除水中重金属离子的研究

微生物去除水中的重金属离子是微生物利用一个新的研究领域,微生物的这种性质在处理含有重金属离子的废水溶液中具有广阔的应用前景。本文对微生物去除重金属离子的原理,去除过程中的影响因素：溶液pH值、重金属离子的初始浓度、生物去除剂的预处理、去除时间、去除温度以及重金属离子的回收和重复使用等作了详细的综述。     

纳滤去除水中的有害离子

本文综述了纳滤去除饮用水和重金属废水中的有毒有害离子的应用研究,阐述了纳滤膜对无机盐的截留效果主要取决于膜对离子的电荷效应,表现在对多价离子的截留率高于单价离子。利用纳滤膜这种分离性能,可以去除部分饮用水中微量的有害单价离子（如NO2^-、NO3^-、F^-等）和大部分的有毒二价离子（如HAsO4^2-和重金属离子）,获取优质安全的饮用水;也可以用于处理重金属废水,能有效去除废水中的重金属离子。将纳滤和反渗透集成用于重金属废水处理,可以做到对有毒重金属离子的回收利用和出水回用,实现清洁生产,既具经济效益,又具环境效益,在工程实际中极具推广应用价值。     

水和重水物性数据的经验估算

本文提出用经验公式Y(?)=A(1)[1(?)T(?)]A(2)计算水和重水的密度、蒸发热,表面张力、声速和折射率以及水和重水的饱和熵、介电常数、热导率和粘滞系数。在0—360℃温变区间内,绝大部分性质的计算百分误差在1％以内。     

重金属的超临界络合萃取动力学

引　言超临界ＣＯ2 络合萃取是去除重金属的一种清洁高效的方法 .其原理是利用络合剂与带电的离子通过配位键生成电中性的、弱极性的、稳定的、易溶于超临界ＣＯ2 的络合物 ,从而可被超临界ＣＯ2萃取[1] .该技术具有萃取速度快、萃取率高、萃取温度较低、生物兼容性好和无毒、无污染等优点 .近年来 ,对土壤、河床污泥以及从模拟的滤纸和砂土上萃取金属离子的研究 ,国外已有大量报道[2 ] ,但从真实体系中萃取痕量重金属的报道则很少[3] .中药以其丰富的资源、独特的疗效、毒副作用小等优点已引起了世界各国的关注 .然而 ,由于环境污染、炮制…     

烃类热裂解的乙烯产率计算

烃类管式炉热裂解时，乙类产率可用公式ｙ＝５．３４＋０．０４６７ｔ－０．２９７ＢＭＣＩ－４．０６θ计算。该式具有形式简单，参数易得，应用范围广，预测准确度高等特点。     

水冷却塔热力性能参数的计算及评定

论述工业水冷却塔验收评定测试主要热力性能参数,如水气质量比Ｌ／Ｇ、塔冷却数ｋａｖ／Ｌ等的简明计算方法,以评定冷却塔原设计及改造后的能力。借经典湿球理论说明冷却塔的基本操作原理;借应用广泛的以焓差为推动力的迈克尔方程图解,比较原设计工况测试结果的性能。推荐的计算程序是美国冷却塔协会（ＣＴＩ）规范要求,可免除现场测试数据经数学归纳推导出的经验关系式的繁锁与缺陷,使测试计算方法统一而规范．     

循环水漏氨工况下高浓缩倍数运行的工艺控制

阐述大化肥循环冷却水系统漏氨的危害,论述系统在漏氨运行情况下,保证在高浓缩倍数5～7运行的药剂投加方案.