Case studies material flow

As the collective LCA studies on plastics show, these three life cycles have in many cases not been respected. The LCA framework does not force the user to do so. In order to do that, additional tools may have to be used, especially Material Flow Analysis. 

This case study clearly shows that a worn screw will cause the discharge temperature to increase due to material flow over the flights and will decrease the heat transfer coefficient, limiting the transfer of energy through the barrel wall. With the restored flight clearance, the process was able to increase the rate by about 35%, and the quality of the product was improved. 

Wall-coated flow tube reactors have been used to study the uptake coefficients onto liquid and solid surfaces. This method is sensitive over a wide range of y (10" to 10 1). For liquids this method has the advantage that the liquid surface is constantly renewed, however if the uptake rate is fast, the liquid phase becomes saturated with the species and the process is limited by diffusion within the liquid, so that corrections must be applied [70,72,74]. Many experiments were designed to investigate the interaction of atmospheric species on solid surfaces. In this case the walls of the flow tube were cooled and thin films of substrate material were frozen on the wall. Most of the reaction probabilities were obtained from studies on flow tubes coated with water-ice, NAT or frozen sulfate. Droplet train flow tube reactors have used where liquid droplets are generated by means of a vibrating orifice [75]. The uptake of gaseous species in contact with these droplets has been measured by tunable diode laser spectroscopy [41]. 

The importance of dispersion and its influence on flow pattern and conversion in homogeneous reactors has already been studied in Chapter 2. The role of dispersion, both axial and radial, in packed bed reactors will now be considered. A general account of the nature of dispersion in packed beds, together with details of experimental results and their correlation, has already been given in Volume 2, Chapter 4. Those features which have a significant effect on the behaviour of packed bed reactors will now be summarised. The equation for the material balance in a reactor will then be obtained for the case where plug flow conditions are modified by the effects of axial dispersion. Following this, the effect of simultaneous axial and radial dispersion on the non-isothermal operation of a packed bed reactor will be discussed. 

Jansson, B.O., Wilmot, W. and Wulff, F., 1982. Coupling the sub-systems- the Baltic Sea as a case study. In M.J.R. Fasham (ed.), Flows of energy and materials in marine ecosystems theory and practice. Plenum Press, New York, pp. 549-595. 

Numerous case studies, examples, and problems illustrate the thermodynamic analysis of process performance to explain how to effectively analyze and optimize work flows and environmental resources. The authors compare the present industrial society with an emerging one in which mass production and consumption are in harmony with the natural environment through closure of material cycles. In this second edition, the book s structure of Basics, Thermodynamic Analysis of Processes, Case Studies, and Sustainability has been unaffected, but a few additions have been made. 

Fluid flow, heating and composition, which change by reaction or by transfer at one interface, represent the specificity of the chemical engineering processes. The response of a system to the applied effects that generate the mentioned cases depends on the nature of the materials involved in the process. All the properties of the materials such as density, viscosity, thermal capacity, conductivity, species diffusivity or others relating the external effects to the process response must be included as variables. The identification of these variables is not always an easy task. A typical case concerns the variation of the properties of the materials, in a nonlinear dependence with the operation variables. For example, when studying the flow of complex non-Newtonian fluids such as melted polymers in an externally heated conduct, their non-classical properties and their state regarding the effect of temperature make it difficult to select the properties of the materials. 

Although the literature contains numerous case studies involving the use of solutes (and sometimes solute isotopes) to trace water sources and flow paths, such applications include an implicit assumption that these solutes are transported conservatively with the water. Unlike the isotopes in the water molecules, the ratios of solute isotopes can be significantly altered by reaction with geological and/or biological materials as the water moves through the system. While the utility of solutes in the evaluation of rainfall-runoff processes has been repeatedly demonstrated, in a strict sense, solute isotopes only trace solutes. Solute isotopes also provide information on the reactions that are responsible for their presence in the water and the flow paths implied by their presence. 

Einsele, G., 1977. Range, velocity and material flux of compaction flow in growing sedimentary sequences. Sedimentology, 24, pp. 639-655 Engelen, G.B., 1984. Hydrological systems analysis a regional case study, Arnhem East. 

In order to illustrate the approach, a case study is considered. The case study is a multi-stage multiproduct chemical batch plant demonstrator with a plant topology similar to flexible flow shops. Two recipes to produce the end-products are given. The end-products blue (B) and green (G) are produced from three raw materials, yellow (Y), red (R) and white (W). Each batch of the product results from two batches of the raw materials. The production process considered is two batches of material Y and W reacts to produce one batch of B similarly two batches of R and... 

SOCOPSE is looking mostly at hazardous priority pollutants to provide guidelines and decision support tools for their management at river basin scale. Its activities include material flow analysis, a series of detailed substances reports, identification of measures and management options, and application to fonr case studies. A strong interaction with industry research networks, authorities and NGOs is envisaged. 

For die first case study, the particulate filled nanopolymers is studied. An investigation on viscometric flow for particulate filled nanopolymers is presented as the second case study in this chapter. Application of synthetic or natural inorganic fillers is reviewed as the third case study. The next two case studies are devoted to description of a multiscale micromechanical model and plication of cement materials reinforcement with nanoparticles. 

With a basic background in viscoelasticity, we can briefly discuss the basic parameters that a rheometer measures, and how they relate to the material that is under study. For the case of oscillatory flow, the rheometer will typically provide three basic parameters of interest in characterizing the properties of a gel under study. These parameters are ... 

---