Economic viability

Since process design starts with the reactor, the first decisions are those which lead to the choice of reactor. These decisions are among the most important in the whole design. Good reactor performance is of paramount importance in determining the economic viability of the overall design and fundamentally important to the environmental impact of the process. In addition to the desired products, reactors produce unwanted byproducts. These unwanted byproducts create environmental problems. As we shall discuss later in Chap. 10, the best solution to environmental problems is not elaborate treatment methods but not to produce waste in the first place. 

As decommissioning approaches, enhanced recovery e.g. chemical flooding processes are often considered as a means of recovering a proportion of the hydrocarbons that remain after primary production. The economic viability of such techniques is very sensitive to the oil price, and whilst some are used in onshore developments they can rarely be justified offshore at current oil prices. 

Chiesa and Con.sonni [1,3] have made detailed studies of how a CO2 tax would affect the economic viability of several of these cycles when a tax and CO2 removal are introduced. Fig. 8.27 shows their results on the cost of electricity for natural gas-fired plants plotted against the level of a carbon tax (in c/kg CO2 produced), for two of the novel cycles studied here, in comparison with an existing CCGT plant with natural gas firing. 

In other instances, it is sufficient for the plant engineer to have a less accurate measurement of what is going on. As well as being technically suitable for the purpose, the instrument chosen will reflect these considerations. In the case of process control, the instrumentation must be reliable and it must yield information, often over very long periods of time, which represents the state of the plant or the process and its history. It is on the basis of this information that the plant engineer will make decisions, many of which will affect the economic viability of the process and some of which will have a direct impact on the safe operation of the plant. 

There is a very wide range of condensate polishers available, and it is important to properly understand the background to the problem to make the correct selection and ensure the economic viability of the project. 

The intention of this chapter is to provide a general survey on the preparative methodologies for the size- and shape-selective synthesis of metallic nanoparticles that have emerged from the benches of chemical basic research during the last few decades and become established as practical standard protocols. Industrial scale-up, however, has only just started to test the economic viability of these procedures and to determine whether they can meet the challenges of a number of very specific applications. The commercial manufacture of such thermodynamically extremely unstable nanoparticles in defined sizes and shapes on the kilo-scale is still confronted by a number of major problems and it remains to be seen how these can be solved. 

Asymmetric membranes have a tight, low-permeability, retentive zone that performs the desired separation and a more open, high-permeability zone that provides mechanical strength to the overall membrane. This structure is particularly critical to the economic viability of reverse-osmosis membranes. Asymmetric membranes operated in TFF mode must have the tight side facing the feed channel so that particles are retained on its surface and can be acted upon by the tangential flow. Asymmetric membranes operated in NFF mode can... 

A reactor is principally meant to bring the reacting species together under conditions in which chemical reactions are favorable, to supply the requisite energy, and ultimately to allow a separation of the reacted product phases. More often than not, the chemical treatment step that occurs in a reactor is the heart of the process. This step can be crucially important to make or break the process, on the basis of considerations of economic viability. 

Nevertheless, there are several hurdles to overcome. Biotransformation has to compete with a chemical production process. The production of bio-based bulk chemicals and intermediates from white biotechnology must be economically viabile [67]. This means that the biotechnological product must be cheaper to produce or of higher quality than products based on classical chemical routes. And, incidentally, switching to a novel process takes time and money. Therefore, process solutions are required which are adapted to the special needs of biocatalyzed reactions. Within this chapter, several specific tasks have been addressed, illustrating universal possibilities to overcome the limitations found in bioprocesses. 

The economic viability of the whole process is consequently determined, in addition to various market forces, by the efficiencies of these three stages and the velocities of the syntheses. Since the synthesis of poly(3HB) requires the cells both as a catalyst and as a reactor (cell factory), the overall yield is also influenced by the cellular content of the polymer. 

If we want to improve the economic viability and to reduce the price of the product, we have to maximize the yield coefficients for growth as well as for formation of the product. 

Depending on the scale of production, an important parameter determining the economic viability of poly(3HB) production (besides overall yield and poly(3HB) content) is productivity. Productivities of poly(3HB) production at-... 

Extraction of PHA from plants is likely to be a major factor affecting the production cost of PHA from crops and, therefore, the economic viability of this approach. In contrast to production of PHA from bacterial fermentation, where the production system is designed to produce only PHA, an agricultural production of PHA is likely to be most viable only through the recovery of not only PHA but also all other useful components of the harvested crop, i.e., oil, proteins, and carbohydrates. This fact, combined with the lower level of PHA accumulation in plants in comparison to micro-organism, is likely to make PHA recovery from plants a challenging task. 

The conditions used industrially for the Haber process are those that sustain the economic viability of its manufacture. Out of necessity, a high yield in a long time must be balanced against a low yield in a shorter time, whilst minimising energy costs. The conditions employed indicate a compromise between these opposing outcomes, as the graphs illustrate. 

Table 3. Factors determining the economic viability of an electrosynthetic/electrochemical or an electrolytic effluent treatment process [49]...

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