Logistics plant size

Table I lists the categories of laboratory reactors used for catalyst testing and catalytic process studies, viz., in the order of decreasing size pilot-plant, bench-scale and microflow reactors. Table II compares the feed requirements of some representative examples of these three classes for a typical case of oil hydroprocessing. The large effect of scale is evident whereas the pilot plant consumes monthly amounts of liquid and gas that require supply on a periodic basis by tank car and tube trailers, the microflow needs can be covered by a small drum or can and a few gas bottles. The size of the test reactor does not only have consequences for the logistics of supply, storage and disposal of feeds and products, but can also dictate the scale of preparation of special feedstocks and catalysts.

Figure 2.2 shows seven possible solutions for the problem. The routes examined included direct shipments from component plants to assembly plants, shipments through the warehouse, peddling (whereby trucks, originating from component plants, would make deliveries across various assembly plants), and combinations of such strategies. For each route, the shipment size could be full truckloads or the optimal shipment size. Figure 2.2 also shows the composition of transport and inventory costs in each of the seven possible logistics systems. 

Suppose Optima were to replace full truckloads by optimal shipment sizes. How would the optimal shipment sizes be determined Given the symbolic description earlier, consider the expression for the total logistics cost for a component from its component plant to the assembly plant. 

If a production plant is required to produce 900 tons of chlorine per day using rectification equipment capable of sustained operation at 90,000 amperes, the plant must operate a minimum of 300 cells. If the cell voltage is 3.4 volts at 90 kA, rectification equivalent to 1020 volts is required. In practice, the logistics of production requirements, plant reliability, and maintenance outages will dictate the size (i.e., number of cells and nominal amperage) of each circuit. In the example above, the plant would use a minimum of two circuits, with two nominal 90-kA, 600-volt rectifiers. 

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