Equipment specification scale

Air separation by PSA on a large scale is today dominated by machines in which the pressure swing may be from near atmospheric to substantially sub-atmospheric pressure. The industry typically calls these machines vacuum swing adsorption (VSA) separators. A second sub-class in air separation is the machines that use a pressure swing the ranges from somewhat super-atmospheric to sub-atmospheric and these may be called trans-atmospheric PSA. The distinctions made here have implications as to equipment specifications and performance limitations in both bed size factor and O2 recovery. 

Thus, equipment specifications can be described in terms of the scale ratio L or, in the case of a distorted body, two or more scale ratios X, Y, Z). Scale ratios facilitate the comparison and evaluation of different sizes of functionally comparable equipment in process scale-up. 

This short-term pilot-scale evaluation was accomplished by testing various filtration units under the same set of process conditions. Not only did this work result in a final equipment specification, but revealed significant wafer fabrication process changes. The conclusions of this process design project are listed below ... 

Model Equations to Describe Component Balances. The design of PVD reacting systems requires a set of model equations describing the component balances for the reacting species and an overall mass balance within the control volume of the surface reaction zone. Constitutive equations that describe the rate processes can then be used to obtain solutions to the model equations. Material-specific parameters may be estimated or obtained from the literature, collateral experiments, or numerical fits to experimental data. In any event, design-oriented solutions to the model equations can be obtained without recourse to equipment-specific fitting parameters. Thus translation of scale from laboratory apparatus to production-scale equipment is possible. 

Sample calculations in reports, 462 Saran, 437, 440-442 Sawing for equipment fabrication, 447 Scale formation in evaporators, 355-360 Scaling for equipment cost estimation, 169-171 Scaling factors for heat transfer, 586-587 Scale-up for equipment specifications, 36-39 Schedule number for pipe, 493 Screen, cost of 567 Self insurance, 264-265 Sensitivity of results for pipe sizing, 367-368 Separators, cost of 559-561 Sequential analysis, 771-772 Series compound-amount factor, 227... 

Decide on the type of heat exchanger (e.g., 1 1, 1 2 type, or 2 4 type) to be used. Assume permissible scale factors and show the basic equipment specifications. 

Prior to dealing with the specific scale-up issues related to SCF extraction/ fractionation and SCF drug formulation plants, we will present the basic background used to build and operate any SCF equipment in compliance with GMP and the safety rules (26) that must be imposed in any case. 

Environmental Controls in Production. Environmental permit requirements should be evaluated based on the commercial-scale material balance and new equipment specifications. Testing requirements for environmental evaluation should include acute fish and invertebrate toxicity for raw materials, intermediates, and products biodegradation of raw materials, intermediates, and products microbial growth inhibition of raw materials, intermediates, and products water coefficients (KOW) and water solubility for raw materials, intermediates, and products and waste treatability test results. Particular emphasis should be placed on the evaluation of the compatibility of the new process waste streams with the existing waste-treatment systems. If any process waste streams require off-site disposal into regulated hazardous waste landfills, leaching experiments may also be required. 

The objective of scale up is to ensure that the process is scaled up to provide product which will comply with specification. Scale-up may encompass changes in process equipment and operation, with an associated increase in output, for example, in the following situations ... 

Often when simulating a process, it is the flowrate of products (not feeds) that is known—for exanple, production of 60,000 tonne/yr of chemical X, with a purity of 99.9 wt%. Assume that a converged solution has been found in which all the product specifications have been met except that the flowrate of primary product is not at the desired value. For this case, it is a single matter to miiltiply all the feeds to the process by a factor to obtain the desired flowrate of the product that is, just scale the solution up or down by a constant factor and rerun the simulation to get the correct equipment specifications. 

Another limitation is that the breakage and coalescence kernels and frequency information tend to be specific to the equipment used to acquire the data. It is highly scale dependent all quantities are flow dependent. Once information is obtained using PBEs, it cannot be used, with confidence, for scale-up work. At a specific scale, however, system information can prove useful. For example, the effect of surfactant concentration, stirring rate, impeller design, phase composition, and so on, could all be interpreted in terms of (v, v ), X(v, vO, P(v, vO, and g (v). This information could be used to improve and control product quality. 

First, considerably greater emphasis has been placed on semimicro techniques and their application to preparations, separations, analysis and physical determinations such as those of molecular weight. We have therefore greatly expanded the section on Manipulation on a semi-micro scale which was in the Third Edition, and we have described many more preparations on this scale, some independent and others as alternatives to the larger-scale preparations which immediately precede them. Some 40 separate preparations on the semi-micro scale are described in detail, in addition to specific directions for the preparation of many classes of crystalline derivatives required for identification purposes. The equipment required for these small-scale reactions has been selected on a realistic basis, and care has been taken not to include the very curious pieces of apparatus sometimes suggested as necessary for working on the semi-micro scale. 

Table 1 is condensed from Handbook 44. It Hsts the number of divisions allowed for each class, eg, a Class III scale must have between 100 and 1,200 divisions. Also, for each class it Hsts the acceptance tolerances appHcable to test load ranges expressed in divisions (d) for example, for test loads from 0 to 5,000 d, a Class II scale has an acceptance tolerance of 0.5 d. The least ambiguous way to specify the accuracy for an industrial or retail scale is to specify an accuracy class and the number of divisions, eg. Class III, 5,000 divisions. It must be noted that this is not the same as 1 part in 5,000, which is another method commonly used to specify accuracy eg, a Class III 5,000 d scale is allowed a tolerance which varies from 0.5 d at zero to 2.5 d at 5,000 divisions. CaHbration curves are typically plotted as in Figure 12, which shows a typical 5,000-division Class III scale. The error tunnel (stepped lines, top and bottom) is defined by the acceptance tolerances Hsted in Table 1. The three caHbration curves belong to the same scale tested at three different temperatures. Performance must remain within the error tunnel under the combined effect of nonlinearity, hysteresis, and temperature effect on span. Other specifications, including those for temperature effect on zero, nonrepeatabiHty, shift error, and creep may be found in Handbook 44 (5). The acceptance tolerances in Table 1 apply to new or reconditioned equipment tested within 30 days of being put into service. After that, maintenance tolerances apply they ate twice the values Hsted in Table 1.

Thermoformability is a property required by the many sheet materials used in the thermoforming industry. These properties are unique for the specific forming methods used, and are best determined by actual thermoforming tests on smaU-scale equipment. The softening or drape temperature of the material, residual stress in the sheet from its manufacture, and its melt strength and viscosity are important parameters relating to this use. 

The summation term is the mass broken into size interval / from all size intervals between j and /, and S is the mass broken from size internal i. Thus for a given feed material the product size distribution after a given time in a mill may be deterrnined. In practice however, both S and b are dependent on particle size, material, and the machine utilized. It is also expected that specific rate of breakage should decrease with decreasing particle size, and this is found to be tme. Such an approach has been shown to give reasonably accurate predictions when all conditions are known however, in practical appHcations severe limitations are met owing to inadequate data and scale-up uncertainties. Hence it is stiH the usual practice to carry out tests on equipment to be sure of predictions. 

The constant may depend on process variables such as temperature, rate of agitation or circulation, presence of impurities, and other variables. If sufficient data are available, such quantities may be separated from the constant by adding more terms ia a power-law correlation. The term is specific to the Operating equipment and generally is not transferrable from one equipment scale to another. The system-specific constants i and j are obtainable from experimental data and may be used ia scaleup, although j may vary considerably with mixing conditions. Illustration of the use of data from a commercial crystallizer to obtain the kinetic parameters i, andy is available (61). 

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