含氟废气处理设备——冲击管吸收器

过磷酸钙生产产生的含氟废气难以处理,其主要原因是处理过程中产生的大量硅胶会粘结在拨水轮、喷头、塔板上,造成设备不能长期正常运转,运行费用高,且严重影响生产。我公司采用新型含氟废气处理设备,效果好,每月只需清理1次设备。磷肥车间生产用的是高硅质磷矿石,含氟气体主要以SiF4形式逸出,SiF4易被水吸收,大量硅胶产生在第1台处理设备上。针对此特点,第1台设备采用冲击管吸收器(道尔吸收器),见图1。冲击管吸收器结构:主要由冲击管和冲击槽组成,冲击管由一直管和可用于调节狭缝宽度的“炮弹头”组成。冲击管吸收器工作原理:从冲击管…     

湿法磷酸降低过滤系统结垢方法初探

湿法磷酸生产中过滤系统结垢严重，利用同离子效应的有关原理，在混酸中加入H2SiF6可减少Na2SiF6和K2SiF6的结晶量，有效降低真空抽滤时Na2SiF6和K2SiF6的结垢量。     

氟硅酸钠制备白炭黑氨解过程影响因素研究

利用磷肥副产品Na2SiF6为原料,采用氨解法制备白炭黑。Na2SiF6水解反应的机理研究表明pH对水解反应影响很大,是调控白炭黑结构与性能的重要因素;Na2SiF6氨解反应为放热反应,反应初期是调控白炭黑产品结构与性能的关键时期。实验还研究了氨水的加入量、溶液pH、反应温度、氟化钠的加入等因素的影响,该工艺Na2SiF6转化率较高,白炭黑收率可达97%。     

K_2SiF_6容量法测定SiO_2的操作

K2SiF6容量法测定SiO2在我国推行已久,但由于各种原因,这种操作方法的优势没有充分发挥出来,即使在分析方法逐渐仪器化的今天,出于标定仪器的需要,正确掌握K2SiF6容量法的操作仍有其重要的意义。在我多年的化验室工作过程中,了解到许多单位反映K2SiF6容量法测定SiO2的难度较大,不易掌握,更有一些单位到现在仍在使用重量法做系统分析,特别是对于立窑企业,酸融重量法测定SiO2的弊端显而易见,而采用K2SiF6容量法又不好掌握,为此笔者结合自己多年来的工作经验对现行的K2SiF6容量法的操作结合率值控制中采用的快速测定生料中的SiO2方法…     

氟硅酸盐制取四氟化硅的研究进展

SiF4多被应用于电子行业和半导体行业,氟硅酸盐制备SiF4是制备方法中的一种.本文介绍了氟硅酸盐的性质,制备方法,以及氟硅酸盐制备SiF4的方法,并对部分氟硅酸盐制备SiF4的条件及产物进行了对比.     

南化公司磷肥厂从普钙生产中回收硅胶获得成功

普通过磷酸钙是目前我国生产最普遍、使用量最大的磷肥,在其生产过程中会逸出有害的含氟废气,用水加以吸收生成氟硅酸(H2SiF6)和硅胶(H2SiO3)。氟硅酸可用于生产氟硅酸钠和冰晶石等多种产品,大部分厂家已回收并加以利用。而对硅胶,绝大部分厂家均是直接排放,严重污染了环境,浪费了宝贵的资源。     

萃取磷酸生产中磷氟化合物的性质分析(续完)

氟硅酸是由以SiF4为核心的过氟氟硅酸nH2F2.SiF4、氟硅酸H2F2.SiF4和氧氟硅酸H2O.SiF4组成,萃取磷酸不是正磷酸H3PO4,而是以氟磷酸——mH2O.nH2F2.(P2O5.kSiF4)形式存在的,HF、SiF4还可与硫酸结合成氟硫酸。分析了在萃取磷酸浓缩过程中,当磷酸能量浓度CE(H3PO4)>73.13%条件下,SiF4与P2O5的能量系数α(SiF4)与α(P2O5)相接近,因此要从氟磷酸中脱氟非常困难,尤其是从含有Fe2O3、Al2O3、MgO等杂质的萃取磷酸中脱氟更为困难。     

萃取磷酸生产中磷氟化合物的性质分析(待续)

氟硅酸是由以SiF4为核心的过氟氟硅酸nH2F2.SiF4、氟硅酸H2F2.SiF4和氧氟硅酸H2O.SiF4组成,萃取磷酸不是正磷酸H3PO4,而是以氟磷酸——mH2O.nH2F2.(P2O5.kSiF4)形式存在的,HF、SiF4还可与硫酸结合成氟硫酸。分析了在萃取磷酸浓缩过程中,当磷酸能量浓度CE(H3PO4)73.13%条件下,SiF4与P2O5的能量系数α(SiF4)与α(P2O5)相接近,因此要从氟磷酸中脱氟非常困难,尤其是从含有Fe2O3、Al2O3、MgO等杂质的萃取磷酸中脱氟更为困难。     

湿法磷酸中氟的测定

湿法(萃取)磷酸的生产是用硫酸分解磷矿石。磷矿石与硫酸反应,生成磷酸和磷石膏:Ca5(PO4)3F＋5 H2SO4＋nH2O→3H3PO4＋5CaSO4·nH2O+HF所产生的氟化氢继续与原料中的二氧化硅或共它含硅化合物作用,生成四氟化硅:4HF＋SiO2→SiF4+2H2O四氟化硅与水作用生成氟硅酸:3 SiF4 + 2H2O→2 H2SiF6＋SiO2SiF4+2HF→H2SiF6此时只有少量SiF4和HF逸入气相,而大部分的氟留在磷酸中,影响磷酸的净化,并严重腐蚀设备。     

四氟化硅的生产概况

四氟化硅（SiF4）是电子工业中的一种重要原料，它还能用作光导纤维、太阳能电池和水泥硬化剂等的原料。详细介绍了SiF4的物理、化学性质及危险特性。SiF4的工业生产方法主要有硫酸法、六氟硅酸盐热解法和Si-HF直接合成法3种。电子工业用SiF4需要有较高的纯度，重点介绍了SiF4的精制工艺，同时还介绍了SiF4经济概况。     

Study of the effect of different electron irradiation doses on the decomposition temperature of azodicarbonamide

Azodicarbonamide (ADCA) is a well‐known chemical blowing agent used in the fabrication of polyolefin foams which decomposes into gases at temperatures above the melting temperature of the polymer. In these polymer foams, the polymer is usually crosslinked before or during the foaming process to increase its viscosity and make it capable of supporting the pressure of the gas during foaming. This crosslinking process allows producing low‐density foams with homogeneous cellular structures. A typical procedure to crosslink the polymer is to irradiate it using a high energy‐electron beam. When ADCA is incorporated into the polymer before the irradiation process, it is also exposed to the high energy electron beam. However, the effect of the irradiation on the decomposition process of ADCA has not been explored yet. In this research, it has been found that there is a reduction of the thermal decomposition temperature of ADCA when this material is electron irradiated with different doses ranging from 25 to 150 kGy, being this reduction higher when the irradiation dose is increased. It has also been found, that the reduction of the decomposition temperature is due to a modification of the lattice parameters of the crystalline structure of ADCA. POLYM. ENG. SCI., 59:791–798, 2019. © 2018 Society of Plastics Engineers     

A temperature programmed desorption study of the interaction of acetic anhydride with zeolite beta (BEA)

The interaction of acetic anhydride with the Na- and H-forms of zeolite BETA, as well as with materials where copper or iron has been introduced into BEA by ion exchange, has been studied by temperature programmed desorption (TPD). In all cases acetic acid is a main desorption product in the temperature range 370–570 K. Ketene desorption is also significant, although it is argued that much of it is retained in the zeolite pores, where it undergoes further decomposition into carbon monoxide, hydrogen and water. There is an inverse correlation between the quantity of ketene desorbed and the activity of the catalysts in the catalytic acylation of anisole by acetic anhydride to yield p-methoxyacetophenone. The significance of this observation is discussed and an acylation mechanism involving ketene is proposed.     

Importance of coupling between specific energy and viscosity in the modeling of twin screw extrusion of starchy products

During the twin extrusion process, starch basic structure is modified and it is very important to be able to predict the changes experienced by the product. To model the transformation of starch during twin screw extrusion, it is thus necessary to take into account the strong coupling between viscosity and thermomechanical treatment. It is the purpose of the present work. We have used the software Ludovic^© to calculate the flow of a molten starch along a twin screw extruder. We have assumed that the degradation reaction (viscosity decrease) was linked to the specific mechanical energy received during the flow. We have compared extrusion cases with and without viscosity/energy coupling, and we show that it is important to take it into account to correctly predict the parameters of the extrusion process (torque, energy, product temperature, etc.) and the level of starch transformation. POLYM. ENG. SCI., 50:1758–1766, 2010. © 2010 Society of Plastics Engineers     

Thermal effects in the necking of polymers

A certain fraction of the mechanical work performed on a specimen is converted into heat during necking of plastic material. A method for measuring this fraction is proposed when specimens are drawn in two different surroundings, air and water. Differences in the heat transfer coefficients of these two media influence the temperature rise during necking. The fraction (α) of mechanical work converted into heat can be calculated using data determined at only one draw rate. The value of α calculated for polypropylene is 0.55 and for polyethylene it is 0.48.     

Threshold Energy: A Dimensional Extension of the Critical Energy for Jet Attack Application

The critical energy criterion (E_c) developed by Walker and Wasley is widely used to determine the response of explosive submitted to flyer plate impacts. As it has been shown previously to be limited in the pressure range over which it applies, in the number of explosive formulations which appear to obey it and in the range of projectiles covered by it, we have modified twice this criterion. The first modification, taking into account a trend toward lower minimum energy with increasing pressure (pressure fluence) enables it to be applied to explosives previously found to be outside the original criterion and to extend the pressure range. The second modification taking into account a trend toward higher minimum energy with decreasing impact surface area (impact surface dependence) is a bidimensional extension of the critical energy concept. The threshold energy per unit area thus defined allows to predict the shock initiation limits of bare explosives (PBX and cast formulations) impacted by shaped charge jets.     

On the combinatorial part of the UNIFAC and UNIQUAC models

The excess Cibbs energy of liquid mixtures may be predicted using group contribution models (f.ex. UNIFAC and ASOG), or it may be correlated using molecular models such as UNIQUAC. Group contribution models and the UNIQUAC model contain a combinatorial contribution which accounts for size- and shape-effects and a residual contribution which accounts for interactions among groups or molecules. A new expression for the combinatorial contribution is given which yields much improved predictions of the excess Gibbs energy of systems where the residual contribution may be expected to be zero (e.g., mixtures of aliphatic hydrocarbons). It is shown that it is advantageous to incorporate the new combinational expression into future modifications of the UNIFAC model.     

Should the removal of water be taken into account in the analysis of kinetic data of polyesterification reactions?

Summary In most polyesterification reactions, the concentrations of acid, alcohol and catalyst (if present) are expressed in moles per unit mass of the charge, denoted as moles/kg. In this paper, a general kinetic equation that takes water removal into account has been derived. It has been shown that (i) when the progress of reaction is followed by titration of acid, the removal of water affects the concentrations of alcohol and catalyst; and (ii) the ratio of the rate constants that do and do not account for water removal is smaller than unity, and it varies with the degree of reaction. On the other hand, it has been found that the rate constant obtained using moles/kg as the unit of concentration is not a real constant but a function of the charge density. Treating it as a constant may lead to appreciable error or misinterpretation.     

Impregnation of PVP microparticles with ketoprofen in the presence of supercritical CO2

The aim of the work is to enhance the oral bioavailability of ketoprofen by inserting it into a water-soluble polymer, poly(vinylpyrrolidone) (PVP) K30, using supercritical carbon dioxide as the impregnating solvent. Ketoprofen is a non-steroidal anti-inflammatory drug (NSAID) characterized by low solubility and a low dissolution rate in the gastrointestinal tract, PVP is a biocompatible water-soluble polymer with a fast dissolution rate and supercritical CO₂ is a clean non-toxic solvent that is able to plasticize amorphous polymers.The physical state of the drug in the polymer has been investigated through Fourier Transform Infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) and it has been compared with that of the PVP-ketoprofen physical mixtures. The results of the analyses show that an amorphous solid dispersion of the drug in the polymer can be obtained even at high concentrations.Impregnated polymer powders were compressed into tablets and the release kinetics was evaluated to study the drug dissolution rate. The release curves of the physical mixtures, with the same drug content, were also measured and compared with those of the impregnated polymer tablets. The results show that the release mechanism depends on the tablet composition and that it is necessary to work with not too high a drug content to obtain a large enhancement of the dissolution kinetics.     

氨合成系统双塔并联改造运行总结

将闲置的氨塔并联到氨合成系统,投运后,合成系统压力下降,压差减少,合成氨生产能力由310t/d上升到350t/d。     

关于炉料中"焦比"对电炉制磷影响的探讨

根据制磷电炉的构造和运行特点 ,引入了炉料焦比的概念。阐述了磷矿和焦炭的化学组成对炉料焦比的影响 ,从电能转换成热能过程出发 ,探讨了炉料焦比和炉料电阻率 (熔池电阻率 )、操作电阻 (熔池电阻 )的关系 ,以及它对电炉的电气参数、几何尺寸和操作运行的影响 ,并指出炉料焦比不仅是电炉设计时必须考虑的因素 ,而且是生产中控制操作电阻的主要因素。