Mini chemical plant

In fact a fuel cell is a mini chemical plant with a number of pumps, valves and recirculation loops. Obviously it is hard to miniaturize it to a pocket size system. Miniaturizing fuel cells is not a simple matter of reducing physical dimensions as macro-sized (conventional) fuel cell components are limited by characteristic fabrication constraints (Cha et al., 2004, Lee et al., 2002). The materials and the manufacturing processes used in the conventional fuel cells have restrictions on dimensions and scalability. The machining of flow structures, for example, is constrained by the brittleness of graphite, and molding is limited in deep narrow... 

Major advancement in minimizing processing risks will be accomplished by using arrays of micro-reactors, in series or in parallel, in conjunction with robotics and sophisticated control schemes. The use of mini-factories will also enhance product flexibility and production agility. Most chemical plants, except those for petroleum cracking and well-established bulk materials, will be miniaturized to the extent possible. This will be another paradigm of manufacturing. 

Chemical reagents wbicb are capable of reacting specifically with an unreactive component of tbe oil, namely PCBs, while leaving other essential components intact, must be carefully researched in terms of chemical reactivity, safe handling, storage capability, toxicity and cost. Tbe following discussion gives a brief overview of some of tbe work wbicb has so far been completed in tbe development of tbe Mini-Oil-Plant (MOP) system for tbe PCB decontamination of mineral oils. 

The above remarks throw a critical view onto the contemporary efforts to simulate entire chemical processes on the smallest possible scale. Beyond all doubt, this technology can produce the proof about the feasibility of a synthesis. In addition, all process steps carried out in a homogeneous medium and dependent on micro-mixing, will be correctly executed on the micro-scale. Furthermore, the scale-dependent process steps will also be carried out in a satifactory manner on the micro-scale, because their scale-dependence could not express itself. But from these results no statement concerning the scale-up can be made In other words Mini-plants are not suitable to gain any scale-up rules for scale-dependent steps. 

In 1968, an electrolytic reduction process was proposed by A. Schneider and A. L. Ayers (6) to circumvent the above disadvantages. A research program was carried out in the Allied Chemical Corporation s laboratories during the years 1968 to 1972 to develop the process and equipment. The work resulted in the development of the Electropulse Column ( 7) for the continuous (differential) electrolytic uranium-plutonium partition process, which was later scaled up, fabricated, and installed in the Allied-General Nuclear Services reprocessing plant at Barnwell, South Carolina. About the same time, a stagewise electrolytic uranium-plutonium partition process was tested on a mini mixer-settler unit in Germany. (8)... 

Much of the material in this chapter was presented in a technical paper at the 25th Annual AIChE Loss Prevention Symposium in August 1991. A paper entitled Mini Modification Miseries - Small Quick Changes in a Plant Can Create Bad Memories was presented by Roy E. Sanders. About two-thirds of this chapter was published as an article entitled Small, Quick Changes Can Create Bad Memories in Chemical Engineering Progress, May 1992. The publisher, the AIChE has given permission to freely use this material in this chapter. 

In the present day a different scale-up procedure is usually followed. Various aspects of the chemical reaction are studied extensively in very small but often continuously operating bench scale reactors and in "mini-plants , equipped with very accurate measuring devices. Specific physical effects are studi in the absence of chemical reaction on larger scales. Mathematical models are developed that will describe the process accurately as a function of scale, so that they can be extrapolated with confidence to predict the behaviour of larger equipment. 

Mini-fuel cells and mobile fuel cells have some specific features. One of the most important jobs of ordinary (large-sized) fuel cells is the highly efficient conversion of chemical fuel energy to electrical energy. For higher fuel utilization efficiency, power plants involving such fuel cells include many peripherals to monitor and regulate the rate of the fuel supply, as weU as external parameters such as temperature and pressure that influence this efficiency. 

Most likely, the main barrier to implementing these improvements is the cost of modifying existing plants. Nonetheless, after contacting all producers of IB and terpene based polymers in North America and Europe, the lead author found that Arizona Chemical [199], Chevron-Oronite [200], and Gevo [45] are interested in development of more environmentally acceptable business practices. Hopefully, this mini-review will help prompt the replacement of older systems with cleaner and greener methodologies. 

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