Chemical production problems

While the principal value of the book is for the professional chemist or student of chemistry, it should also be of value to many people not especially educated as chemists. Workers in the natural sciences—physicists, mineralogists, biologists, pharmacists, engineers, patent attorneys, and librarians—are often called upon to solve problems dealing with the properties of chemical products or materials of construction. Eor such needs this compilation supplies helpful information and will serve not only as an economical substitute for the costly accumulation of a large library of monographs on specialized subjects, but also as a means of conserving the time required to search for... 

The value of many chemical products, from pesticides to pharmaceuticals to high performance polymers, is based on unique properties of a particular isomer from which the product is ultimately derived. Eor example, trisubstituted aromatics may have as many as 10 possible geometric isomers whose ratio ia the mixture is determined by equiHbrium. Often the purity requirement for the desired product iacludes an upper limit on the content of one or more of the other isomers. This separation problem is a compHcated one, but one ia which adsorptive separation processes offer the greatest chances for success. 

By 1980, research and development shifted from relatively inexpensive surfactants such as petroleum sulfonates to more cosdy but more effective surfactants tailored to reservoir and cmde oil properties. Critical surfactant issues are performance in saline injection waters, adsorption on reservoir rock, partitioning into reservoir cmde oil, chemical stabiUty in the reservoir, interactions with the mobiUty control polymer, and production problems caused by resultant emulsions. Reservoir heterogeneity can also greatly reduce process effectiveness. The decline in oil prices in the early 1980s halted much of the work because of the relatively high cost of micellar processes. 

M. Realff, n A.naljsis of the Chemical Patch Production Problem and a Detailed Methodologyfor Schedulings technical report no. LISPE-88-054, Laboratory for Intelligent Systems in Process Engineering, MIT, Cambridge, Mass., 1989. 

Excellent control and response to process changes No chemical-disposal problem when pollutant (product) recovered and returned to process... 

Air, soil, and water are vital to life on this planet. We mnst protect these resonrces and nse them wisely— onr snrvival as a species depends on them. Despite recent impressive strides in improving the environment, evidence is overwhelming that more effective action mnst be taken to address snch critical issnes as acid rain, hazardons waste disposal, hazardous waste landfills, and groundwater contamination. It is also vital that we assess realistically the potential health and enviromnental impacts of emerging chemical products and technologies. The problems are clearly complex and demand a broad array of new research initiatives. 

Many chemical batch production facilities are dedicated to producing a set of products that require for their manufacturing a common set of unit operations. The unit operations are performed in the same sequence for each product. This type of production problem is often solved by configuring the available equipment so that each unit operation is carried out by a fixed set of equipment items that are disjoint from those used in any other operation. If one unit is assigned to each step, this is called a flowshop (Baker, 1974). 

Felcht reports on Degussa s activities in cooperation with partners from academia and industry to develop innovative industrial-scale micro-structured reactors for making large-tonnage products by liquid- and gas-phase reactions [137]. The aim is to make the potential of micro reactors more widely available for a larger variety of processes, naturally with focus on Degussa s fine and specialty chemical productions. Also, the aim is to circumvent traditional problems of scale-up. 

The solution of these problems is based on a simple idea the developed laboratory-scale process is used for manufacturing of a chemical product by parallelization of many small units. Although promising great advantages over scale-up, this procedure, denoted numbering-up , is not trivial by far. It cannot be carried out in a simple way due to the tremendous technological effort necessary a chemical plant with hundreds or even thousands of small-scaled vessels, stirrers, heaters, pumps. 

A practical problem faced by tanneries is that many chemical products are proprietary products. Many suppliers do not specify the chemical composition of the products, so tanneries may have to seek additional information from the chemical suppliers in order to determine the environmental impact of the products they use. Sometimes it is also difficult for tanneries to receive accurate information also from the suppliers of the chemicals. Material safety data sheets generally provide some data on the toxicity of the products to humans and environment, and many tanneries use these as the sole source of information to determine the environmental impact of a certain substance. It can be expected in the EU in the future that tanneries will receive more detailed information about the substances used because of the REACH legislation. 

To tackle these problems successfully, new concepts will be required for developing systematic modeling techniques that can describe parts of the chemical supply chain at different levels of abstraction. A specific example is the integration of molecular thermodynamics in process simulation computations. This would fulfill the objective of predicting the properties of new chemical products when designing a new manufacturing plant. However, such computations remain unachievable at the present time and probably will remain so for the next decade. The challenge is how to abstract the details and description of a complex system into a reduced dimensional space. 

Edwin Drake drilled the first oil well in Pennsylvania in 1859 to use extracted oil as a substitute for whale oil—the main lighting source and feedstock for consumer and chemical products then. This resource was hazardous to get and dwindling due to heavy exploitation, as it happens currently with oil. Petroleum presented many advantages over whale oil and solved a great deal of ecological and resource security problems associated with the old resource. Nevertheless, after a century and a half of use, petroleum has created new problems related to environmental pollution and energy security [1]. 

In this book, we have examined the chemistry behind the possible new approaches to solving the separation problem and have discussed process designs that could be used to implement the Chemistry. In this chapter, we have addressed what we believe to be the biggest problems remaining to be solved for the different approaches described in the rest of the book and have attempted to provide pointers towards possible solutions. These should provide impetus for further research in this important area aimed at improving the chemistry, phase behaviour, differential solubility and process design and eventually lead to the commercialisation of many more homogeneous catalytic processes so as to make chemicals production much more environmentally acceptable. 

Oxides play many roles in modem electronic technology from insulators which can be used as capacitors, such as the perovskite BaTiOs, to the superconductors, of which the prototype was also a perovskite, Lao.sSro CutT A, where the value of x is a function of the temperature cycle and oxygen pressure which were used in the preparation of the material. Clearly the chemical difference between these two materials is that the capacitor production does not require oxygen partial pressure control as is the case in the superconductor. Intermediate between these extremes of electrical conduction are many semiconducting materials which are used as magnetic ferrites or fuel cell electrodes. The electrical properties of the semiconductors depend on the presence of transition metal ions which can be in two valence states, and the conduction mechanism involves the transfer of electrons or positive holes from one ion to another of the same species. The production problem associated with this behaviour arises from the fact that the relative concentration of each valence state depends on both the temperature and the oxygen partial pressure of the atmosphere. 

In the previous section, a simple chemical production process has been introduced and formally described by the means of RTN extended by places. The solution of the above problem is a straightforward task and can be performed without... 

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