Plant size limiting capacity

Motor voltage selection is determined by economics and by the availability of adequate system capacity to permit motor starting without excessive voltage drop. Restrictions by the utility or by the size of the plant s generating capacity may limit the maximum drop to less than 20%. In some cases, system dips as small as 5% or less may be the maxi-... 

A battery limits cspital investment of 2.8 millicxi was estimated for the base case, and 6.2 million for the hi capacity design. A battery limits production cost for an average ioe of l.l/kg ( 0.50/lb) was estimated, based on raw material, for the base case plant. Production co declines significantly as plant size increases, reaching 0.5/kg ( 0.24/lb) for the hi capacity case. 

Fundamentally it is of great significance that tests in laboratories or pilot plants are able to reproduce to the greatest possible extent the parameters relevant to shaping in actual production plants. But this is only possible to a limited degree, simply in view of the difference in the size and capacity of the equipment and the products. Therefore it is one of the most impor-... 

The first ten runs were conducted on a laboratory decanter of 150 mm diameter. The following year, tests were conducted on a small plant with a pilot plant size decanter of 425 mm bowl diameter. The plant capacity was limited, but results (runs 13-29) were sufficiently encouraging to warrant work on a larger plant the following year (runs 31-34). 

An alternative to a factored estimate, in some cases, can be a scaled estimate if the battery limits cost of a similar plant is known, but the size is different. The cost of the new plant, C , is equal to the known plant cost, C, times the ratio of the two plants capacity raised to a fractional power. That is ... 

The maximum values of electric power and unit output of electrochemical cells vary within wide limits. The total current load admitted by individual electrolyzers for the electrochemical production of various materials in plant or pilot installations (their capacity) is between 10 A and 200 kA, while the current loads that can be sustained by different types of battery (their current ratings) are between 10 A and 20 kA. Corresponding differences exist in the linear dimensions of the electrodes (between 5 mm and 3 m) as well as in the overall mass and size of the reactors. 

For a single-product plant the calculation of equipment sizes is straightforward. First the limiting cycle time ti is determined using Eqn. (7.4-14) or Gantt charts. The batch size is then evaluated for an assumed production capacity Q and available production time H ... 

In other cases, it is the maximum possible size of the equipment itself that places limits upon plant capacity. For example, the size of glass-lined reactors (where the whole vessel must be annealed in an oven) is limited by the size of the largest oven available to the equipment manufacturers. 

The plant is used to produce type A and type B of the polymer expandable polystyrene (EPS) in F = 5 grain size fractions each from a number of raw materials ( ). The availability of raw materials and the product storage capacity are assumed to be unlimited. The preparation stage is not limiting the production process... 

Many factors act together to determine the optimum scale of a process. These include the demand for the product, competitors share of the market, any technical limitations on the size of operation and also economies of scale effects. There is an approximate logarithmic relationship between the unit production costs for a product and the volume of production, whereby considerable economies of scale can be achieved. If the costs of a process of one size (C ) is known then the costs of larger or smaller factories (C ) can be approximately obtained from the relationship C = Cx (or n° ), where n is the scale-up ratio, i.e. n=l for a plant that is twice as big. Alternatively, a graph of log capital costs vs. log of plant capacity gives a straight line with a slope equal to the scale-up factor (n). The power term varies from case to case, but is invariably less than one. This scale effect is one reason why unit production costs are inversely proportional to the scale of manufacture. For example, most amino acids are expensive and can only be used in... 

A cost equation may be written to include all the costs, which are expressed in terms of the capacity of the flow-scheme components. The selection of equipment sizes that minimize capital investment is (1) complicated by interrelations between pieces of equipment, (2) limited by the discontinuity in size of standard equipment, (3) fixed by the availability of idle or used equipment, and (4) restricted by the higher cost of custom-made equipment. Writing one equation for a complete plant is a complex task. It is more likely that it may be done for small sections of the plant which can be operated as interrelated trains. 

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