Solid delivery

A number of new approaches to the way in which precursors are delivered to a substrate have been developed in which the precursor is dispersed into the gas phase without having to be volatile. These new systems each have their own advantages for a particular precursor depending on its physical state. Most of the delivery systems in use can be classified as one of the following a liquid injection system (LIS), where a precursor is vaporized directly from a neat liquid or solution containing the precursors a solid delivery system (SDS), where the precursor is vaporized... 

Table 1-3. Advantages and disadvantages of Solid Delivery System (SDS).

Figure 1-4. Schematic of HP Solid Delivery System (SDS), (Reproduced from Appl. Phys. Lett. 1991, 59, 606).

The resultant formulation, in a liquid form, is dispersed into fine droplets by dripping (drop-by-drop), spraying, or emulsification. This step increases the liquid surface available for further transformations (evaporation, cooling, gelation, chemical reactions) and favors the generation of dispersed (liquid or solid) delivery structures. 

In cases where the resins are to be supplied in a solvent anyway, azeotropic distillation can be used to remove the water more efficiently and at lower temperatures. Figure 16.3 describes the reactor design for polyester resin production, which can also be applied to alkyd resin production (see Section 16.5). The product resin can be either cooled and discharged via a cooling belt in case a solid delivery form is required, or thinned with solvents. 

If it is desired to carry out the combined operations of stirring, refluxing, and addition of a liquid in a stream of gas, the apparatus of Fig. 77, 7, 12, a may be used the side tube for the gas is sealed on to the separatory funnel. For the passage of a gas into a stirred liquid, the aperture carrying the modified separatory funnel may be fitted with the device shown in Fig. 77, 7, 12, 6 the glass rod inside the tube is held in position by a short length of heavy-wall rubber tubing and is employed to clear the lower end of the gas delivery tube, should it become blocked with solid reaction product. 

Amount of material required. It is convenient to employ an arbitrary ratio of 0 10 g. of solid or 0 20 ml. of liquid for 3 0 ml. of solvent. Weigh out 0 10 g. of the finely-powdered solid to the nearest 0 01 g. after some experience, subsequent tests with the same compound may be estimated by eye. Measure out 0-20 ml. of the liquid either with a calibrated dropper (Fig. 11,27, 1) or a small graduated pipette. Use either a calibrated dropper or a graduated pipette to deliver 3 0 ml. of solvent. Rinse the delivery pipette with alcohol, followed by ether each time that it is used. 

Small concentrations of volatile components in a liquid mixture may accumulate in the vapor space of a container over time and appreciably reduce the flash point relative to the reported closed-cup value. This may be the result of degassing, chemical reaction or other mechanism. An example is bitumen [162]. Similarly, if a tank truck is not cleaned between deliveries of gasoline and a high flash point liquid such as kerosene or diesel oil, the mixture might generate a flammable atmosphere both in the tmck tank and the receiving tank. Contamination at the thousand ppm level may create hazards (5-1.4.3 and 5-2.5.4). Solids containing upward of about 0.2 wt% flammable solvent need to be evaluated for flammable vapor formation in containers (6-1.3.2). 

Where inerting is not used, one guideline restricts operations to metal or enameled metal tanks having a volume no greater than 5 m, a diameter no greater than 3 m and all conductive parts grounded. The liquid should contain a maximum of 1 wt% insoluble solids, have a maximum feed rate of 60 L/min and the delivery pressure should not exceed 50 bar. The vessel should be continuously drained to prevent liquid accumulation [127]. 

The production of aluminum begins with the mining and beneficiation of bauxite. At the mine (usually of the surface type), bauxite ore is removed to a crusher. The crushed ore is then screened and stockpiled, ready for delivery to an alumina plant. In some cases, ore is upgraded by beneficiation (washing, size classification, and separation of liquids and solids) to remove unwanted materials such as clay and silica. 

Figure 2.12 Schematic representation of an on-line SPE-GC system consisting of three switching valves (VI-V3), two pumps (a solvent-delivery unit (SDU) pump and a syringe pump) and a GC system equipped with a solvent-vapour exit (SVE), an MS instrument detector, a retention gap, a retaining precolumn and an analytical column. Reprinted from Journal of Chromatography, AIIS, A. J. H. Eouter et al, Analysis of microcontaminants in aqueous samples hy fully automated on-line solid-phase extraction-gas chromatography-mass selective detection , pp. 67-83, copyright 1996, with permission from Elsevier Science.

The potential use of poloxamers in the medical field has been extensively investigated [5,35]. The use of poloxamers in drug delivery, as gels in the controlled release of drugs and in solid form in the targetting of drugs at specific sites in the body, has received significant atten-... 

External to the boiler house, provision for the storage and handling of solid and liquid fuel is required with access for delivery vehicles. With some small boilers such as electrode or steam-coil generators, where the boiler only serves a single item of plant or process, it is practical to install them immediately adjacent to that process. The electrode boiler is eminently suitable here as no combustion gases are produced. 

Polaris Missiles. US nuclear delivery system (UGM-27 series). A solid propint two-stage... 

Sullivan, L. A., and Bin Han., Vapor Delivery Methods for CVD, An Equipment Selection GmdQ, Solid State Technology, pp. 91-101 (May 1996)... 

The commercialization of developments in biotechnology will require a new breed of chemical engineer, one with a solid foundation in the life sciences as well as in process engineering principles. This engineer will be able to bring iimovative and economic solutions to problems in health care delivery and in the large-scale implementation of advances in molecular biology. 

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