FULL-SCALE PLANT DESIGN

There are four ways in which mixers are often specified when considering installation of more productive units in a fermentation plant. This can involve either a larger tank with a suitable mixer or improvement of the productivity of a given tank by a different combination of mixer horsepower and gas rate. These are listed below  

1 Some General Relationships in Large Scale Mixers Compared to Small Scale Mixers 

In general, a large scale mixing tank will have a lower pumping capacity per unit volume than a small tank. This means that its blend time and circulation time will be much larger than in a pilot tank. 

There is also a tendency for the maximum impeller shear rate to go up while the average impeller zone shear rate will go down on scaleup. In 

This means that there is a much greater variety of shear rates in the larger tank, and in dealing with pseudoplastic slurry it will have a quite different viscosity relationship around the tank in the big system compared to the smaller system. 

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According to the vendor, the capital costs for full-scale plant designed to compact 100 tons of fiy ash per 8-hr shift would be approximately 1,000,000. The operating costs were range from 100 to 500 per ton (D225058, p. 4 D225047, p. 2). 

Before the full-scale plant design is finalized, the committee also recommends demonstration tests for the following changes suggested by Foster Wheeler ... 

In addition to the preceding fluoride transport tests, laboratory-scale tests were conducted to investigate the possibility of containing or removing fluoride from the system to allow more economical materials of construction to be used in the design of the full-scale plant (AEA, 20011). A series of nine tests was to be conducted to obtain kinetic data on the use of calcium as an agent for fluoride removal from the GB simulant, fluorophosphoric acid. Data were to be obtained for the hydrolysis reaction under acidic, neutral, and alkaline conditions. 

AEA conducted a series of desktop studies (literature surveys) to establish certain design parameters for the full-scale plant. These studies were conducted in place of further tests. The conclusions of these studies are summarized below. 

Recommendation (Blue Grass) EFKE-1. Eco Logic should conduct additional grinding tests for the final design of the feed system to specify the size of the grinder and motor for the full-scale plant. 

Much of the optimization of the solvent extraction plant can be achieved in the pilot plant testing. As noted earlier on the subjeet of proeess design, one must investigate the dependence of the dispersion and eoaleseence char-aeteristies and their effect on extraction and phase separation. Also, such variables as metal concentration, equilibrium pH (or free aeidity or free basieity), salt concentration, solvent concentration (extraetant, diluent, and modifier), and temperature have to be studied to determine their effect on mass transfer. Although many of the variables can be tested in the pilot plant, many circuits are not optimized until the full-scale plant is in operation. 

Fluidity can be assumed to stay constant when scaling up an enzyme-substrate system, provided that solutions of identical composition are used for the laboratory-scale model and the full-size plant design. Application of the design criterion in Eq. (19.36) assumes operation in the linear regime of transmembrane pressure AP up to about 1-2 bar, as described in Chapter, Section 8.5.1, Eq. (8.78), so that... 

The other type of salt precipitating in the column is calcium based. Elimination or reduction of calcium ions in the liquor is critical if the temperature in the system drops. A larger amount of precipitate was observed in the pilot plant when overnight temperature dropped to about 60°F. Most of these salts returned to solution after the system was reheated to operating temperatures. This relationship between the temperature and precipitation must be taken into consideration in the design and operation of a full-scale plant. As indicated by the analysis shown in Table V, these salts are believed to be primarily calcium sulfite and sulfate. 

Scraper blades set to rotate at 35 rpm are used for a pilot plant addition of liquid ingredients into a body-wash product. What should the speed of the blades be in a full-scale plant, if the pilot and the full-scale plants are geometrically similar in design Assume scale-up is based on constant tip speed, diameter of the pilot plant scraper blades is 0.6 m, and diameter of the full-scale plant scraper blades is 8 ft. 

In order to analyze for process problems or design stochastic controllers one usually needs to run full scale plant tests and develop process dynamic models from the resulting data. This section discusses several aspects related to the modelling of polymer reactors for these purposes. 

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