Solids processing sequence

Crystallization is flequently the initial step in a solids processing sequence, similar to that shown in Fig. 11.1-1, that subsequently includes solid-liquid separation and drying equipment. Since product size... 

The success of continuous processing heavily hinges on the speed and continuity of the feed materials into the process. A main problem with the continuous processing of energetic composites is the surging in the solids feed, making the process sequence hazardous and product... 

Quantitative descriptions of MOS devices are available (2, 8, 9,12). This short summary of solid-state physics was intended to illustrate the importance of carrier concentrations, transport, generation, and recombination in device performance. These properties, in turn, depend critically on material parameters resulting from a large number of chemical process sequences. 

The role of chemical analysis and materials characterization has become a central one in advanced IC fabrication. Starting materials, the raw semiconductor wafer, as well as each gas, liquid, and solid used in the processing sequence are coming under increasing scrutiny to assure the highest standards of purity. As a result, analytical methods for bulk chemicals and materials are often used at their lowest attainable detection limits, and techniques are being developed to meet new demands. 

The adsorption step in a process sequence can be used to remove a contaminant from a fluid stream by contact with a stationary solid adsorbent bed. Is this an example of purification, concentration, or fractionation, and why ... 

As shown in Fig. 11.1-1, the solids—liquid separation device is the link between the solids formation equipment and the diying operation, Thus, predictable and reliable operation is essential in this stage of the processing sequence. Continuous or baich-automatic centrifuges nad continuous vacuum filters are typically used to recover solid material from continuous crystal I ization operations. Many factors are considered in [ha final selection of the device. In any case, an equipment testing program is always essential to determine the capacity and performance of solids separation equipment. 

Simplification of the water-recovery process sequence following treatment in the ICB units would improve process operations and reduce capital expenditures. Industrial experience and preliminary testing indicate that solids in the crystallizer could be cohesive or sticky, that foaming could occur, and that environments could be extremely corrosive. These conditions could exist under both acidic and alkaline conditions because of the presence of chlorides, sulfates, phosphates, nitrates, and carbonates. 

Figure 4.7 illustrates the VLS whisker growth sequence. At 1400 °C, the soUd catalyst melts and forms the liquid catalyst ball. Carbon and silicon from the gas phase are dissolved in the liquid alloy, which soon becomes supersaturated such that solid SiC precipitates at the interface with the carbon substrate. Continued dissolution of the gas species into the liquid catalyst allows the whisker to grow, lifting the catalyst ball from the substrate as additional SiC precipitates. These VLS whiskers are typically larger in diameter (4—6 pm) than those formed by the vapor solid process (VS-whiskers) in fact, they frequently grow to a length of tens of millimeters. 

The manufacturing process sequence to crystalline layered sodium disilicate may start with the production of sodium silicate solution of a Si02 Na20 ratio of 2 by the hydrothermal process (see Table 22.1 and Figure 22.11). Quartz sand is reacted at temperatures of 180-240 C with sodium hydroxide solution of 50 wt% strength. The reaction can be performed in a nickel-clad autoclave, which is equipped with a stirring device and heated by injection of steam. The reaction solution is filtrated after addition of perlite as the filter aid. The 45 wt% solids content of the final liquor was realized by dilution with water [21,49,51,95],... 

Kim S-J, Jeon BH, Choi K-S, Min N-K (2000) Capacitive porous silicon sensors for measmement of low alcohol gas concentration at room temperature. Solid State Electrochem 4 363-366 Kitsara M, Goustouiidis D, Chatzandroulis S, Beltsios K, Raptis I (2006) A lithographic polymer process sequence for chemical sensing arrays. Microelectron Eng 83 1192-1196... 

For certain types of stochastic or random-variable problems, the sequence of events may be of particular importance. Statistical information about expected values or moments obtained from plant experimental data alone may not be sufficient to describe the process completely. In these cases, computet simulations with known statistical iaputs may be the only satisfactory way of providing the necessary information. These problems ate more likely to arise with discrete manufactuting systems or solids-handling systems rather than the continuous fluid-flow systems usually encountered ia chemical engineering studies. However, there ate numerous situations for such stochastic events or data ia process iadustries (7—10). 

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