Process engineering perspective

Cooney, C.L., D. Hopkins, D. Petrides, and D.J. Monticello, Microbial Desulfurization of Fuels A Process Engineering Perspective, Dept. Chem. Eng., M.I.T., Cambridge, MA (1991). 

Once the candidate corrective measure alternatives have been identified, a more detailed evaluation of each alternative needs to be undertaken. From an engineering perspective, the first step in the evaluation process would include the development of a conceptual design for each alternative. The conceptual design would consist of a process description, a process flow diagram and a layout drawing. Preliminary sizing of equipment and utility and land requirements would be developed. In addition, chemical requirements and residuals produced can be estimated. From the conceptual design, permitability and residuals disposal issues can be identified and addressed. 

There are a number of attempts to provide quantitative answers in the htera-ture, but these are generally flawed from either a cost engineering or chemical engineering perspective and their results should be treated with extreme caution. This caveat notwithstanding, it is probably reasonable to say that for most products the threshold hes in the range of 1000—10 000 tonne per year process stream (not product) rate. The threshold value will not, however, be the same for aU products, processes, operating sites, and so on. 

In order that different perspectives may be applied, members from research, process engineering, project engineering, construction, and production should be at the review meeting. Notes should be taken at this meeting on how to shut down the plant under any set of circumstances. Startup procedures should also be documented to see that they can be done easily and safely. It is reviews like this that help prevent the multimillion-dollar fires and explosions that have destroyed many plants and taken many lives in recent years. 

H. Wu, M.A. Khan and A.S. Hussain, Process control perspective for process analytical technology integration of chemical engineering practice into semiconductor and pharmaceutical industries, Chem. Eng. Comm., 194, 760-779... 

Diffusion - In this text, we will dehne diffusion (and most other processes) from an engineering perspective, in that we will go to the level of detail that suits our objective. Diffusion can then be defined as the mixing of chemicals by random molecular motion. Diffusion coefficients in dilute solutions will be discussed in detail in Chapter 3. 

The chapter is organized as follows. First, to establish a common language, we define some common terms from both a pharmaceutical and an engineering perspective. Subsequently, we review model-based design and optimization as a framework for product and process development and optimization, process scale-up, and continuous improvement activities. The role of process and analytical technology (PAT) methods and principles in this framework is discussed. Finally, the main areas requiring effort are identified. 

The term in-process testing is synonymous with process control. From an engineering perspective tests at the end of a process do not provide any direct means to keep a process under control. It is well recognized that such tests simply accept or reject lots and depending on the operating characteristic curve of a test accepted lots are no better than the rejected ones (14). 

As a further activity the Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (BMLFUW) in co-operation with the OECD organised an international conference in Vienna in November 2003, which was called "Experiences and Perspectives of Service-oriented Strategies in the Chemicals Industry and Related Areas". The conference was attended by around 100 participants from 16 countries. The conference gave an excellent overview about international approaches how to introduce service elements into the chemical business. The participants comprised representatives from authorities, the chemical industry, in particular down stream users, process engineers and economists along with representatives from academia. 

From different disciplines, biotechnology and biocatalysis are seen from very dif ferent angles and perspectives (Figure 1.1). Chemistry and chemists emphasize a molecularly-oriented perspective dominated by compounds and transformations, whereas chemical engineering and thus chemical engineers favor a process-oriented perspective of reactions and processes lastly, biology and its practitioners contribute a systems-oriented perspective of description at the organism level as well as in their view of evolution. 

Whereas many authors have recognized the potential for enzymatic treatment systems, the development of these processes from an engineering perspective is conspicuously lacking. The primary reason for this appears to be the cost of enzymes that have traditionally been very expensive to produce in the quantities that are required at an industrial scale. Enzymes are expensive because of the cost of their isolation, purification, and production. 

This area is extremely rich with potential topics, each of which would require a separate paper to review in depth. The reader should be aware that, because of page limitations, this paper can cover only one of my favorite topics, analysis, in any depth. To provide perspective, computer technology will also be examined because of its enormous impact on process engineering. 

While this staged approach has long been recognized as deficient, it is defensible from a certain perspective. For example, it would be difficult for the control engineers to specify the instrumentation and the distributed control system (DCS) without knowing exactly what process it was intended for. Similarly, it would make no sense for the process engineers to request a control system design for all those flowsheets... 

FIGURE 8.35 Bubbling enhanced flux for filtration of dextran solution. (Adapted from Cui, Z.F., Experimental investigation on enhancement of crossflow ultrafiltration with air sparging, in Aterson, R.P. (Ed.), Effective Membrane Processes-New Perspective, Mechanical Engineering Publications, London, 1993, 237-245.)... 

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