Model-based Scale Up of Solid Bowl Centrifuges Using Experimentally Determined Material Functions

The scale up of solid bowl centrifuges is a major challenge as the process and material behavior are complex and difficult to describe. A common approach to forecast the process behavior is to use analytical models and transfer the experience gained from the lab to the industrial scale. In this context, time-consuming and cost-intensive pilot scale experiments are necessary. This paper presents a methodology to improve the scale up process and make it more sustainable by using a numerical model that allows the real-time tracking of the process and a more reliable scale up process. For this approach, the material behavior is derived from laboratory experiments whereby the scalability is given. Here, the determination of material functions allows an accurate representation of the material behavior for solid bowl centrifuges of different scales. The focus of this paper is the detailed explanation of material related functions for the scale up of decanter centrifuges.     

Neue apparative Entwicklungen bei Filterzentrifugen

New equipment developments in filter centrifuges . Industrial filter centrifuges are used for solid throughputs from ca. 0.01 to 250 t/h per machine. The specific filtration resistance of the solids to be separated likewise covers a range of ca. 1 :25 000. In addition to the enormous range of physical properties and mass flows, a wide variety of demands is placed on the chemical resistance of the materials of construction and the safety of the plant. These demands led to the development of a wide range of filter centrifuges, the most important types of which are first surveyed from a chemical engineering standpoint. There follows an account of the principal characteristics of recent types and the development of various details.     

Dewatering of Sewage Sludge

Dewatering of sewage sludges is usually carried out using belt filter presses or centrifuges. The ability to remove water from sludges by mechanical dewatering is a property of both the sludge and the equipment used for dewatering. Newer high-solids centrifuges can remove more water than a belt press but require a higher chemical conditioning dose. The Gt value, the product of the mean velocity gradient and the shear time, has been found to be a useful parameter for characterizing the shear in mechanical dewatering equipment. Dewatering can be considered a two-step process, filtration followed by expression. The expression step is the most important of these and the benefits of various sludge processing techniques and conditioning chemical types remains a fruitful area of research.     

Dewatering of Sewage Sludge

Dewatering of sewage sludges is usually carried out using belt filter presses or centrifuges. The ability to remove water from sludges by mechanical dewatering is a property of both the sludge and the equipment used for dewatering. Newer high-solids centrifuges can remove more water than a belt press but require a higher chemical conditioning dose. The Gt value, the product of the mean velocity gradient and the shear time, has been found to be a useful parameter for characterizing the shear in mechanical dewatering equipment. Dewatering can be considered a two-step process, filtration followed by expression. The expression step is the most important of these and the benefits of various sludge processing techniques and conditioning chemical types remains a fruitful area of research.     

Die diskontinuierliche Zentrifuge als Betriebssystem in der Chemischen Industrie

Discontinuous centrifuges as operating systems in the chemical industry . Centrifuges are machines with rotors as working spaces in which the relative concentrations in mixtures of substances can be modified. Batch operating centrifuges are particularly suitable for this purpose when high demand on quality are made with regard to separation and purity of the substances separated or when the material parameters are subject to variation. The construction permits optimum adaptation to all operating parameters. The structural components for basic and additional functions have achieved a high standard of technical maturity and some have be specified in proven DIN standards. Centrifuges are particularly suitable for use as components of combined mechanical-thermal demoisturing plants. The technology of the drive systems of centrifuges and the control systems for conducting the process and for safety purposes utilize advanced hydraulics, pneumatics and electronics. Numerous materials of construction are available, including highly corrosion-resistant metals and alloys and those bearing a corrosion-resistant protective layer. The choice and utilization of a particular structural form are determined by the specific operational behaviour on filling, washing of the filter cake residual moisture content attainable, output of solids, demoisturizing capacity, industrial hygiene aspects of sealing during demoisturization and on output, optimum arrangement of the centrifuge in the overall plant, as well as costs of acquisition, installation and operation. Safety features are of particular importance in view of the large amount of energy stored and the possibility of operating with flammable liquids. On the basis of systematic analyses of the sources of danger, constructive measures and systems have been developed for the avoidance of explosion and fire which ensure safe operation of centrifuges.     

CIP modules for centrifuges working on chemical and pharmaceutical duties

The fully automated PharmaCIP cleaning unit from GEA Westfalia Separator is now available in two new versions for the efficient clean-in-place (CIP) of centrifuges, tanks, piping systems and other equipment.Visit www.filtsep.com for the latest filtration industry news     

工程机械涂装辅料成本控制和管理

通过分析油漆辅料在实际过程中的应用情况，明确油漆辅料的最终流向，从工艺、管理、设备等方面进行调整，从而最大限度的提升油漆辅料利用率，并形成定额管理机制，有理有节地施工和应用，最终达成油漆辅料的控制和管理，实现降本的目标。     

Secondary market for chemical processing equipment

More money is now spent, as a percentage of total capital, on used machinery and equipment, such as centrifuges, than ever before. Used equipment has several advantages including price, which can be 20-70% of new replacement costs. Gregg P Epstein, Perry Videx LLC, USA, discusses how to purchase and sell used process machinery, using the chemical processing industry as an example.     

我国石化装备技术国产化的进展

分述了我国反应设备、塔器、换热设备和工业炉等化工专用设备 ,包括离心机和烟气轮机等在内的专用机械 ,以及化工计测设备的国产化研发和生产技术进展情况 ,并提出了今后研发的方向。     

化工设备维修技能提高的办法

常见化工设备包括:离心机、压缩机、风机、汽轮机、各种泵、换热器、塔等。现代化工设备越来越复杂化、精密化,越来越需要维修钳工更高的维修技能,我们只有在多次维修实践中不断总结经验教训,才能满足现代化工设备对维修技能的需求。     

双级推料离心机在氯酸钠生产中的应用及改进

双级活塞推料离心机以其独有的自动连续操作、生产能力高、功率消耗低等优势,已被越来越多的氯酸盐生产企业认识和使用。针对双级推料离心机结构特点、氯酸钠物料特性及在氯酸钠脱水中存在的问题,提出了对双级推料离心机在结构及操作维护上的改进。     

Koaleszenzprobleme in chemischen Prozessen

Coalescence problems in chemical processes . Separation of liquid/liquid dispersions is a process step which often gives rise to considerable difficulties on an industrial scale. A number of selected examples taken from chemical processes demonstrates where phase separations occur, the consequences they may have, and what industrially practicable methods are available for their solution. The problem analysis presented starts from the mechanism of generation of the dispersion and leads to a qualitative characterization of the various coalescence problems without presuming any knowledge of the droplet spectrum. This procedure acquires important knowledge from an assessment of prior process steps. Measures for improvement are deduced from the causes of poor phase separation: modification of physical properties, change of dispersion, use of mechanical separation aids (packings, coalescing filters), application of an electrical field, centrifuges and hydrocyclones, coalescence-promoting chemical additives. Industrially applicable methods are reported for design of equipment for implementation of these approaches.     

TRH050离心机在PVC生产中的应用

介绍了TRH050离心机的特点及工作原理,分析了其在运行过程中出现的问题,并进行了相关的技术改造。给出了TRH050离心机的正常操作、维护与保养方法。     

用于城市污水处理用浓缩脱水一体机

机械浓缩脱水已被广泛用于城市及工业污水的污泥脱水中,目前被广泛采用的脱水设备有带式压榨过滤机、卧式螺旋卸料沉降离心机、板框厢式压滤机等,由于脱水工艺的要求,为了减少因浓缩过程时间较长,结合在污泥中的氮磷重新释放后进入水体,造成藻类的繁殖和对水系的进一步污染,要求机械脱水设备能够对沉淀池中底流进行直接处理,即浓缩脱水一体化处理。     

离心机氮气保护防爆系统设计

离心机在国民经济许多领域如化工、制药等行业中应用极广，这些行业大多对离心机具有防爆等保护措施要求。介绍离心机在这些工业应用中，一种有效的保障安全生产的结合应用数字测氧仪的氮气保护防爆系统设计。     

浅谈化工压力容器的安全附件

压力容器安全附件是防止压力容器因超温、超压、超负荷而引发生产事故而安装在容器设备上的一种附属装置。本文主要针安全阀、压力表、液面计、温度计这四种常见的压力容器安全附件的选用、安装、维护、检查等方面进行分析讨论。     

Methods of Aerosol Measurement before the 1960s

ABSTRACT

The time period before the 1960s can be described as the classical age of aerosol science and aerosol measurement. The measurement philosophy during this period was different from that of the period after the 1960s. Particle number concentration was considered the most important parameter. Optical microscopy was the determinative procedure for sample evaluation, for particle counting, and for size measurement. The most frequently used sampling methods were impaction and impingement, thermal and electrostatic precipitation, and filtration. Condensation samplers, as well as manual condensation nuclei counters, were used also. Manual and simple light scattering and light absorption methods played an already important role. Ultramicroscopy and nephelometry were commonly used methods. Elutriators and aerosol centrifuges were used for determining aerodynamic particle sizes, particle shape factors, and mass size distributions. Chemical aerosol analysis was in a developing state. Silica, silicates, and heavy metals were the most often detected dust and aerosol components. Titration, colorimetry, photometry, and polarography were the most commonly used analytical procedures. Practically no automatic or computer-supported measurement or analytical equipment was available at this time. Sampling instruments often were made in the laboratory, rather than produced commercially.     

Precipitation of food proteins and their recovery by centrifuging and ultrafiltration

Food proteins in solution and as precipitates are subjected to intense forces during industrial processing. Given proper equipment design, the individual protein molecules in solution are remarkably robust; this extends the potential range of conditions under which they can be processed. Protein precipitates are sensitive to shear fields, and this influences the design of precipitation reactors and recovery equipment. Ultrafilters represent an alternative to centrifuges for recovery and, with precipitated protein, can yield solids of comparable concentration. The properties of food protein precipitates can be improved, with respect to recovery, by acoustic conditioning. Detailed physical measurements of proteins in solution or when precipitated, and laboratory-derived kinetic studies of precipitation, can yield information which may be applied directly to industrial operations.     

Measurement of enzyme laundry product dust levels and characteristics in consumer use

Prior to the adoption of improved dust control measures, some factory workers developed allergic respiratory symptoms during the manufacture of enzyme laundry detergents. Since then, the industrial hygiene problem is being brought under control by maintaining dust exposure below levels where allergic respiratory symptoms develop. However, the fact that enzyme allergies could develop in manufacturing plants prompted questions from outside the soap and detergent industry regarding consumer safety of enzyme detergents. Although detergent dust levels in consumer use were known to be very low, a comprehensive testing program was undertaken to place quantitative dimension on the difference between home use and factory operation. Levels and characteristics of detergent dust and enzyme dust generated during home use of laundry detergents have been measured using specialized equipment and procedures. Data from laboratory and in-home studies confirm that laundry products containing an agglomerated enzyme complex are safe from the standpoint of potential consumer exposure to enzyme dust. Even under conditions of excessive home use, consumer exposure is extremely low and can be compared to only a minute fraction of the industrial exposures which are considered to be safe.     

Cleaning process waste water with pressure centrifuges

Conclusions Pressure centrifuges of diameter 25–50 mm can be used to clean process waste water contaminated with fine fireclay, magnesite, chrome-magnesite, or fireclay-clay mixtures; the centrifuges may be combined into blocks.Pressure centrifuges may be used to clean the process water used in wet air-cleaning systems to free the air from fireclay, magnesite, and clay dusts.Translated from Ogneupory, No. 7, pp. 19–24, July, 1968.