Intermediate scale

II of the actual atoms (or at least the non-hydrogen atoms) in the core system are lented explicitly. Atomistic simulations can provide very detailed information about haviour of the system, but as we have discussed this typically limits a simulation to nosecond timescale. Many processes of interest occur over a longer timescale. In the if processes which occur on a macroscopic timescale (i.e. of the order of seconds) rather simple models may often be applicable. Between these two extremes are imena that occur on an intermediate scale (of the order of microseconds). This is the... 

Scale- Up of Electrochemical Reactors. The intermediate scale of the pilot plant is frequendy used in the scale-up of an electrochemical reactor or process to full scale. Dimensional analysis (qv) has been used in chemical engineering scale-up to simplify and generalize a multivariant system, and may be appHed to electrochemical systems, but has shown limitations. It is best used in conjunction with mathematical models. Scale-up often involves seeking a few critical parameters. Eor electrochemical cells, these parameters are generally current distribution and cell resistance. The characteristics of electrolytic process scale-up have been described (63—65). 

Disadvantages of these continuous countercurrent systems are associated primarily with the complexity of the equipment required and with the attrition resulting from the transpoiT of the ion exchanger. An effective alternative for intermediate scale processes is the use of merry-go-round systems and SMB units employing only packed-beds with no movement of the ion-exchanger. 

Product or Process Development—A company can develop a new product or process as a quasi-research effort with a toller while simultaneously building the in-house production capacity. This allows problems found in the toller s intermediate scale efforts to be fixed in the large-scale process and to reduce development time and costs. It may simply be a case of a company wanting to try new raw materials in a well-known process without disrupting existing production or establishing a pilot facility. Tollers can provide a way to achieve these activities in a parallel fashion. 

Switching from Batch to Continuous Processing for Fine and Intermediate-Scale Chemicals Manufacture... 

The former may be considered the true fine chemical while the latter may conveniently be termed intermediate-scale chemicals commodity chemicals produced at a relatively small scale. This crude division starts to indicate the complexity of the economic drivers for B2C that is discussed later. First, however, progress in making the switch is reviewed and the essential elements of plant design structures and costs are briefly introduced. 

Similar observations can be made on other installation factors - for example, stractures and building. While traditionally (large) continuous plants are built outdoors and (small) batch plants indoors, it may not necessarily imply that small and intermediate-scale continuous plants should follow this mle. Product containment and contamination requirements may dictate the need for an enclosed manufacturing environment, meaning that little saving in capital may be realized. 

Cost of Fine and Intermediate-Scale Chemical Plants... 

An explosion occurs when energy previously confined is suddenly released to affect the surroundings. Small explosions, like the bursting of a toy balloon, are familiar and innocuous, but large-scale explosions, like an atomic bomb, are rare and usually disastrous. Between these two extremes lie the commercial and conventional military fields where explosions are produced on a limited scale to cause specific effects. It is with explosions of this intermediate scale that this book is concerned. 

On an intermediate scale, smaller than the workpiece, but larger than the features, is a regime in the range of tens to hundreds of micrometers that is influenced by convection. This is the same size range in which convectively controlled fine structure is observed in pattern formation studies. In this regime, Debecker et al. [139] treated mass-transfer limited deposition on a set of lines in the presence of flow. They defined a Peclet number based on the line width L, the flow velocity U0 and the distance B between electrodes. 

We have synthesized two small scale batches (PA-DBX 1 and 2) of 2-3 g each and one intermediate scale batch (PA-DBX 3) of 8-10 g of DBX-1 from our NaNT. The procedure used to synthesize DBX-1 was based on literature methods.[5,6] For each batch, sensitivity tests, thermal stability by differential scanning calorimetry (DSC), and performance tests were performed and compared to the standard DBX-1 that was obtained from PSEMC (Pacific Scientific Energetic Materials Company, inventors of DBX-1). 

In addition to these full-scale tests, EPA has initiated a program to conduct extensive intermediate-scale incinerator studies, i.e., studies that would approximate the actual conditions that exist in full-scale incinerators but that at the same time would be close enough to the laboratory studies previously discussed to allow correlation of the results from both scales of operation ( ). The EPA Combustion Research Facility (CRF) has been constructed to conduct this program at the National Center for Toxicological Research (NCTR), Jefferson, Arkansas. 

Plate 27. Large-scale image of the Au(lll)-22X-y/F recc truction. The Au(lll) surface reconstructs at room temperature to form a 22Xy/3 structure, which has a two-fold symmetry. On a large scale, three equivalent orientations for this reconstruction coexist on the surface. Furthermore, on an intermediate scale, a herring-bone pattern is formed. See Barth et al. (1990) for details. Original image be courtesy of J. V. Barth. 

Tables 2 and 3 show an antibody purification process scale-up from laboratory scale (1 mL) to intermediate scale (500 mL) to large scale of 10-85 L column volumes, maintaining the column bed height constant. Product quality and biocontaminant levels were maintained throughout the scale-up, though operational flow rates were significantly changed, demonstrating the consistency of the overall purification process. Thorough analysis of each coliunn performance is essential in order to sustain the process robustness at different scales of operation.

This intermediate scale affords a preliminary validation of the intrinsic kinetics determined on the basis of microreactor runs. For this purpose, the rate expressions must be incorporated into a transient two-phase mathematical model of monolith reactors, such as those described in Section III. In case a 2D (1D+ ID) model is adopted, predictive account is possible in principle also for internal diffusion of the reacting species within the porous washcoat or the catalytic walls of the honeycomb matrix. 

Validation at intermediate scale was first performed by comparing the results of kinetic runs over small honeycomb catalyst samples (volumes in the range... 

The final surmise as to the cause of transformation of fire into expln aboard the Grandcamp was an increase in gas pressure due to a condition of confinement. In an effort to simulate the conditions existing in the hold of the Grandcamp, small and intermediate scale tests in bomb cases were made at Pic... 

Vaughan, L. M. R. W. McMullen "Intermediate-scale aerosol cloud travel and diffusion from low-level aerial line releases." Technical Report No. 97, U. S. Army Chemical Corps Contract No. DA-42-007-CML-543, 1963. 

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