浮选过程中的消泡研究

实验研究了浮选过程中三相泡沫产生和维持稳定的机理,分别利用物理、化学以及物理与化学相结合的方法进行消泡实验,结果表明,物理、化学结合消泡法是最经济有效的方法。     

一种具有机械消泡功能的新型塔板

研究开发了一种具有机械消泡功能的新型塔板。该塔板是在普通塔板上放置一种特制的新型机械消泡构件。该构件由相互平行的波纹消泡板组成,构件下半部分沉浸在塔板泡沫层中,起削弱泡沫层波峰高度和降低泡沫层高度的作用,上半部分处于泡沫层上部的气相空间,起惯性除沫的作用。实验结果表明:对于易起泡物系,机械消泡构件能降低雾沫夹带量61%~76%,并大幅削弱泡沫层表面过高的泡沫波峰;对不易起泡物系,机械消泡构件还能降低泡沫层高度15.2%~17.1%。因此,该塔板可以起到延缓塔板泡沫层过高液泛和过量雾沫夹带液泛的作用,具有良好的消泡效果。     

鲁克沁泡沫稠油消泡方法研究

针对鲁克沁泡沫油的特点,分析了加热消泡、加热-超声波消泡、加热-负压消泡和化学消泡对泡沫油的作用机理及效果。结果表明,加热-超声波消泡、加热-负压消泡和化学消泡(DC消泡剂用量100mg/kg)与常温自然消泡方法比较,消泡速率依次提高75%、70%和72.5%。综合考虑现场的实际生产情况,推荐加热-负压消泡方法作为鲁克沁泡沫油的消泡方法。     

金属微填料旋流消泡器的研发及在石油泡沫体系的消泡研究

金属微填料旋流消泡器将旋流离心气液分离与填料机械破碎消泡相结合,应用于高温高压的石油物系——丙烷-脱油沥青泡沫体系的消泡试验研究。研究表明,利用自制的金属微填料旋流消泡器,无需加入消泡剂,能够达到100%的消泡效果。推荐的实验条件是,金属微填料填充密度190~210 g/L,泡沫流量3.0~4.0 kg/h,金属丝径在20μm以下,在相同当量直径下,不规则横截面金属丝消泡效果优于规则横截面,但在一定范围存在一个优化的几何尺寸。     

影响滨海电厂冷却水出口泡沫产生的因素及控制措施

近年来环境的污染问题被日益受到重视,冷却水的排放有时会夹带大量泡沫且不容易消散,影响了周边的自然环境。冷却水产生泡沫的原因主要是排水时的掺气作用,与海水水质、水温、排水时海水的撞击程度和循环水加药等因素有关;提出了加装拦泡网、消泡喷淋管和化学消泡等综合处理措施,能够有效减轻滨海电厂排水口泡沫的污染问题。     

消泡和抑泡技术

泡沫的种类有液体泡沫、弹性泡沫、固液泡沫、乳状泡沫等。泡沫的出现主要取决于起泡性和泡沫稳定性两个因子。起泡性是以液体表面张力的下降以及动态下具有弹性的泡膜的形成为前提的。至于泡沫的稳定性是与表面粘性和表面塑性相关的。消泡方法主要有物理消泡和化学消泡两种。前者是靠加热、超声波、泡沫界面疏水等办法;后者是靠:     

胶磷矿浮选过稳定泡沫消泡技术初探

以王集磷矿浮选精矿泡沫为研究对象，通过物理方法和化学方法的组合旨在找出胶磷矿浮选过稳定泡沫的最佳消泡技术，以达到最佳的消泡效果，并对胶磷矿浮选泡沫过稳定原因及消泡技术机理进行了初步探讨。     

板式塔降液管的机械消泡研究

研究开发了板式塔降液管机械消泡板组件。在降液管中加设特制的新型消泡板组件,该组件由数列若干块相互平行的倒V字形波纹板垂直排列组成,倒V字形波纹板的开口端向下。消泡板组件半浸于降液管泡沫层中,越堰的泡沫液与波纹板碰撞,以及波动的泡沫层不停地与波纹板摩擦,都加速泡沫的破裂,促进降液管内气液分离,降低了泡沫层高度。开口端向下的倒V字形波纹板还对降液管内液体产生向下的作用力,降低了降液管清液层高度。试验结果表明,对易起泡物系,降液管机械消泡板组件能降低泡沫层高度13.1%—36.2%,降低清液层高度10.5%—32.5%。对不易起泡物系,消泡板组件能降低泡沫层高度7.1%—33.2%,降低清液层高度5.1%—24.6%。因此,该消泡板组件可以起到降低降液管液层高度和延缓降液管液泛的作用,具有良好的消泡效果。     

用于P-PVC装置新型消泡剂的筛选

针对ＰＶＣ生产装置单体回收时间长,回收系统“泡沫夹带”严重的现状,决定采用新型,高效的消泡剂来消除泡沫捕集器,间歇汽提器和连续汽提器中的泡沫。采用德国高施米特公司的消泡剂评价试验装置,对收集的消泡剂样品进行了消泡,抑泡性能测定。实验结果ＳＰＪ￣３０１消泡剂具有良好的消泡,抑泡性能,并且对聚合浆料的稳定性和树脂质量无影响。     

气体分布器孔径对泡沫分离过程影响的研究

气体分布器孔径是控制气泡大小的重要因素,也是制约泡沫分离效率的重要因素。开发了一种高分子膜材料用于泡沫分离气体分布器,以十二烷基硫酸钠(SDS)为体系,研究了气体分布器孔径对表面过剩,质量流率,消泡液的表观液体流速,泡沫排液速率以及泡沫分离效率的影响。结果表明高分子膜材料适合用于泡沫分离塔的气体分布器。气体分布器孔径对表面过剩影响不明显,而对质量流率有显著影响。当平均孔径从23μm增大到165μm时,消泡液的表观液体流速降低89%,泡沫排液速率降低93%;SDS富集比从1.14增大到2,提高75%,回收率下降80%。由导出的富集比和回收率计算式得出的计算值与实验值吻合很好。     

Performance characteristics of novel mechanical foam breakers in a stirred tank reactor

Unlimited foam formation and insufficient foam collapse can have serious effects in an aerated system such as a fermentation process. Mechanical foam breakers are used in foam control to avoid the drawbacks associated with the use of chemical antifoams and defoaming agents. In this paper, two new foam breakers consisting of a two‐blade paddle with three slits, and a two‐blade paddle with 168 thin needles have been tested. They gave significantly reduced critical speeds and power consumption for foam control in a stirred vessel, compared with some conventional foam breakers. The effects of various parameters, namely the physical properties of the foaming solution, type of gas sparger, surfactant concentration, and foam‐breaker clearance above liquid level, have been investigated. The degree of difficulty of controlling dynamic foams generated continuously in a stirred vessel is found to be a function of the nature of the foam, ie its bubble size, its liquid holdup, and the degree of foamability of the system. © 1999 Society of Chemical Industry     

Mechanical foam breaking – a physical model for impact effects with high speed rotors

During recent years in chemical engineering processes for instance with aerated stirred tanks containing surface-active components foams and their mechanical control have become very important. However, there are still no rules for calculating mechanical foam breakers. As a contribution to foam control the present paper discusses the fundamentals of foam breaking by means of foam densities and gives a physical model for the mechanisms of a mechanical foam breaker when the main breaking effect is based on impact. The mechanisms were proved by measuring pressures in a foam breaker box. Diameters of secondary foam bubbles produced by foam breakers are calculated and discussed. Experimental investigations were made with different surfactants in aqueous solutions. The paper points out their influence on the process of foam breaking.     

Performance characteristics of mechanical foam‐breakers fitted to a stirred‐tank reactor

In a stirred‐tank reactor (STR), a comparison of the performance of mechanical foam‐breakers: a six‐blade turbine (F‐B), a six‐blade vaned disk (V‐D), a two‐blade paddle (T‐P), a conical rotor (C‐R), a fluid‐impact dispersion apparatus (FIDA) and a rotating disk mechanical foam‐breaker (MFRD) was carried out using defined foaming media. The foam‐breaking ranges (relative to the gas superficial velocity, U_g) of the T‐P, C‐R and FIDA were inferior to that of the F‐B, V‐D and MFRD. The power consumption, P_kc, for foam‐breaking in the MFRD was the lowest among the F‐B, V‐D and MFRD. Operation of the F‐B and V‐D in the STR caused a considerable amount of liquid droplets from the collapsed foam to be entrained with the exhaust air. © 2002 Society of Chemical Industry     

Synthesis and characterization of elastomeric polyurea foam

Polymeric foams are ubiquitous in impact mitigation for civilian and military applications; the performance in such loading scenarios can be elucidated through quasi-static and dynamic mechanical testing. The present study reports on the complex microstructure of newly synthesized polyurea foams exhibiting a hierarchical structure consisting of large perforated semi-closed spherical cells with a mean diameter of 370 ± 162 μm surrounded by smaller closed, spherical cells with size distribution of 69 ± 18 μm. The stress–strain curves were used to calculate the basic mechanical properties and to predict the dynamic behavior of the foams. Nonlinear regression and finite element analyses were used to calibrate the Ogden hyperfoam model to explicate the hyperelastic behavior. The performance of the polyurea foam was found to outperform a benchmark foam in nearly all the elastic and energy absorbing properties. For example, one variation of the newly synthesized foam stored nearly doubled the energy of the benchmark foam while being 12% lighter. Low-density polyurea foam was found to decelerate an incoming impact mass with a minimum G-level that was nearly one third lower than the higher density polyurea and benchmark foams. In all, the behavior of the foam is dependent on the parameters of the fabrication process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48839.     

一体化活性污泥处理工艺中泡沫的形成和控制

城市污水处理厂采用的一体化活性污泥法处理污水工艺较易受到泡沫干扰,主要成因是丝状微生物异样快速生长,其中pH值、温度、溶解氧浓度等是影响泡沫的主要因素。可采用喷洒水、投加化学试剂、降低细胞平均停留时间和调节pH值等方法进行控制。     

Span-20和Tween-80对发酵液中Nisin泡沫分离的影响

研究了微量非离子表面活性剂Tween-80和Span-20对发酵液中乳链菌肽(Nisin)泡沫分离的影响. 结果表明,发酵液泡沫分离时泡沫层轴向气泡直径、连续通气过程的泡沫层高度、泡沫层平均持气量等均因添加活性剂而明显变化. 不同体系气泡大小为,含0.2 g/L Span-20发酵液>含0.5 g/L Span-20发酵液>发酵液>含0.2 g/L Tween-80发酵液>含0.5 g/L Tween-80发酵液;Tween-80的加入破坏了气泡表面的网状结构,因而泡沫层持气量较高;连续通气时,2种表面活性剂都会引起泡沫层高度降低,但Tween-80会增加泡沫层的稳定性. 当Tween-80浓度达0.5 g/L时,Nisin的收率大幅度提高,原因是分离过程中Nisin失活率减少.     

爆炸法生产网化聚氨酯泡沫塑料

以聚醚多元醇、聚合物多元醇、甲苯二异氰酸酯及多种添加剂为原料，采用水发泡，制成块状软质聚氨酯泡沫塑料；将其放入网化箱中，充入氢气与氧气，混合均匀后，引爆，制得网状泡沫塑料，介绍了块泡生产的基本配方，爆炸法网化工艺过程，对氢气与氧气的用量及混合时间进行了讨论，并介绍了网化泡沫的物理性能。     

泡沫对工业发酵的影响及控制

从泡沫的形成和消长规律出发,介绍泡沫对工业发酵的影响和泡沫的控制方法,并提出控制泡沫的措施。     

泡沫稳定剂在阻燃高回弹聚氨酯泡沫塑料中的应用

分别采用L-5 333,Y-10 366和B-8716三种泡沫稳定剂制备阻燃高回弹泡沫塑料;探讨了泡沫稳定剂对阻燃高回弹聚氨酯（FRHRPU）组合料反应活性、泡孔结构及制品力学性能的影响。结果表明：泡沫稳定剂Y-10 366制备的FRHRPU的拉伸强度为171.18 kPa,撕裂强度为3.23 N/cm和回弹性为58.70%,均高于其他两种硅油的,并且当Y-10 366与多元醇的质量比从0.5/100增加到1.2/100时,制品的泡孔孔径先减小后增大,而制品的开孔率从93%降低到35%。     

A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry