Temperature and Atmosphere Control

Before powdered carbon can be used commercially or reused for tertiary treatment of sewage effluents, a method of regeneration is required. The use of the fluidized bed for regeneration offers the key advantages of excellent temperature and atmosphere control and the ability to process the powdered solids conveniently and continuously. 

The second method, based on measurements of IR reflection spectra, is simpler and enables working with larger volumes of molten salt. No special problems involving temperature and atmosphere control exist. The method was used successfully by Fordyce and Baum [336-338] in the investigation of fluoride melts containing tantalum and niobium. 

A more complex system of temperature and atmosphere control used in the study of decomposition rates is quasi-isothermal and quasi-isobaric thermogravimetry [6]. In this method a heating programme linearly increases the sample temperature until a mass change is detected. On detection of a mass... 

Figure 4.41. Schematic diagram of cell for temperature- and atmosphere-controlled measurements using DRIFTS accessory shown In Fig. 4.25 (1) cell cover (38.1 x 21 x 3.2 mm) (2) window (16x2 mm) (3) cell assembly (38.1 x 21 x 29.2 mm) (4) cartridge heater (12.7 X 38.1 mm) (5) thermocouple (6) gas Inlet (0 = 6.35 mm) (7) gas outlet (0 = 6.35 mm). Reprinted, by permission, from B. Li and R. D. Gonzalez, > pp/. Spectrosc. 52, 1488-1491 (1998), p. 1489, Fig. 2. Copyright 1998 Society for Applied Spectroscopy.

Hydrolysis of the alkoxide precursor by addition of water (spraying, passing of vapor) under temperature- and atmosphere-controlled conditions. 

A prefilter should be used ahead of the membrane filter in order to reduce the pressure drop when filtering through the membrane, thus reducing the size of the housing needed for the filter cartridges. This will increase the life of the process system and take the load off the membrane filter that performs the removal of the finer particulates. As for the chemicals used to develop photoresists, continuous recirculation and membrane filtration are the preferred techniques. Strict temperature and atmospheric control must be maintained. Compressed air and water are two separate, but essential, tools in the production of electronic components and systems. 

There are methods to manipulate the backbones of polymers in several areas that include control of microstructures such as crystallinity, precise control of molecular weight, copolymerization of additives (flame retardants), antioxidants, stabilizers, etc.), and direct attachment of pigments. A major development with all this type action has been to provide significant reduction in the variability of plastic performances, more processes can run at room temperature and atmospheric pressure, and 80% energy cost reductions. 

In the dip coating, a substrate is immersed in a liquid solution and then withdrawn with a well-defined extraction speed under controlled temperature and atmospheric conditions. There are five essential steps involved in this process immersion, extraction, wet layer formation, drainage, and solvent evaporation, as illustrated in Fig. 3.9. 

The carbon or silica-loaded nanoparticles were treated in a tube-furnace under controlled temperature and atmosphere. A typical protocol involved shell removal by heating at 300°C under 20% O2/N2 for 1 h and calcination at 400°C under 15% H2/N2 for 2 h. The carbon-loaded Au or AuPt nanoparticles are denoted as Au/C or AuPt/C. The silica-loaded AuPt nanoparticles are denoted as AuPt/Si02. 

Experiments to measure pressure drop and flooding limits were performed in a set-up accommodating monoliths with diameters of 43 mm (Fig. 8.16), while the length of the monoliths varied up to total length of 1 meter. The liquid was distributed by a nozzle the gas was introduced in countercurrent mode via mass flow controllers in the system. At the outlet of the monolith, a special device was mounted (Fig. 8.17), which improved draining of the monolith. The pressure drop along the column was measured using differential pressure transmitters. All experiments were performed at room temperature and atmospheric pressure. 

For all these equipments, attachments permit measurements at high temperatures and in controlled atmospheres. 

Char compositions can be controlled quite precisely through the proper choice of polymer composition, pyrolysis temperature, and atmosphere, as well as through an improved understanding of the mechanisms of polymer pyrolysis. 

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