Drying optimization

Kimball G. Direct vs. indirect drying Optimizing the process. Chemical Engineering, 108, 74—81, May 2001. 

Drying. Optimizing of this stage was the most important to ensure the absence of cracks. Only slow drying in controlled humidity conditions was shown to be suitable for obtaining monoliths without cracks. 

Another phenomenon is so called two-side filling of one-side closed conical capillaries with liquid [5]. On the one hand the more penetrant is trapped by the defect the wider indication will appear. Contrariwise it is almost impossible to extract a penetrant from the completely filled surface defects by dry developer [6]. In this study we propose the theory of the phenomenon. Besides experimental results of the investigation of two-side filling with various penetrants of conical capillaries are presented. Practical recommendations to optimize liquid penetrant testing process are proposed. 

In order to design and optimize anisotropic dry etching processes, severai issues must be understood ... 

Composites can be created ia which the core optimizes desired physical properties such as modulus, whereas the outer layer optimizes surface coasideratioas aot inherent ia the core material. SoHd outer—foam core can provide composites with significant reductions ia specific gravity (0.7). Dry blowiag ageats can be "dusted" onto the peUets orHquid agents iajected iato the first transitioa sectioa of the extmder. 

If ah of the nonfiltration operations are grouped together into a downtime, assumed to be fixed and known, an optimum filtration time in relation to p can be derived by optimizing the average dry cake production obtained from the cycle. Eor constant pressure filtration and where the medium resistance R and the specific cake resistance are constant, the fohowing equation appHes ... 

A report on the continuous flash pyrolysis of biomass at atmospheric pressure to produce Hquids iadicates that pyrolysis temperatures must be optimized to maximize Hquid yields (36). It has been found that a sharp maximum ia the Hquid yields vs temperature curves exist and that the yields drop off sharply on both sides of this maximum. Pure ceUulose has been found to have an optimum temperature for Hquids at 500°C, while the wheat straw and wood species tested have optimum temperatures at 600°C and 500°C, respectively. Organic Hquid yields were of the order of 65 wt % of the dry biomass fed, but contained relatively large quantities of organic acids. 

Combinations of anionic and cationic resins are used. Some of the eady systems involved the use of a cationic wet-strength resin with an anionic dry-strength additive to provide both increased wet and dry strength (63). Combinations of anionic and cationic dry-strength additives also are used to provide strength effects which cannot be achieved by using either polymer alone (64). The ratio of the two polymers must be optimized to achieve maximum performance (see Acrylamide polymers). 

The economics seem to be better for systems where dry powdered fresh hme plus ground recycled hme is injected along with a relatively coarse spray which impinges on and dries out from the reagent, as described by Stouffer et al. [Hs EC Res., 28(1) 20 (1989)]. Witnum et al. [9th Ann. Pitt. Coal Prep. Util. Euv. Control Contractors Conf. (1993)] describes an advanced version of that system that has been further optimized to the point that it is competitive with wet hme-stone scrubbing for >90 percent flue gas desirffurization. 

Optimized modern dry scrubbing systems for incinerator gas cleaning are much more effective (and expensive) than their counterparts used so far for utility boiler flue gas cleaning. Brinckman and Maresca [ASME Med. Waste Symp. (1992)] describe the use of dry hydrated lime or sodium bicarbonate injection followed by membrane filtration as preferred treatment technology for control of acid gas and particulate matter emissions from modular medical waste incinerators, which have especially high dioxin emissions. 

The received results can be used at a choice of a drying mode for optimization of power expenses, at operation of drying installation, and correction of mineral stmcture. 

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