Design extraction

After the flue gas leaves the combustion chamber, most furnace designs extract further heat from the flue gas in horizontal banks of tubes in a convection section, before the flue gas is vented to the atmosphere. The temperature of the flue gases at the exit of the radiant section is usually in the range 700 to 900°C. The first few rows of tubes at the exit of the radiant section are plain tubes, known as shock tubes or shield tubes. These tubes need to be robust enough to be able to withstand high temperatures and receive significant radiant heat from the radiant section. Heat transfer to the shock tubes is both by radiation and by convection. After the shock tubes, the hot flue gases flow across banks of tubes that usually have extended surfaces to increase the rate of heat transfer to the flue gas. The heat transferred in the radiant section will usually be between 50 and 70% of the total heat transferred. 

This type of extraction can be carried out in two different ways. A soil sample can be brought into the laboratory and extracted with relatively large amounts of water to try to determine its inorganic composition. The water-to-soil ratio can be either on a mass-to-mass basis or a volume-to-mass ratio. A one-to-one ratio is commonly used, although other ratios have been used. After a designated extraction time, with or without shaking, water is filtered from the soil and analyzed. A typical water extraction of soil is given in Procedure 11.1. 

Control of the liquid gas (L/C) ratio in the towers is critical in maintaining the design extraction performance relatively small changes can result in significant loss of extraction. 

Aqueous samples were extracted for phenol and 4-chlorophenol using pure carbon dioxide in a specially designed phase separator apparatus (111). The extraction efficiency for these phenols was reported to be over 85%, with a RSD of 8% for eight samples. Additional liquid sample extractions have been investigated for the extraction of phenol from a 6M sulfuric acid solution as well as the extraction of the components of commercial soft drinks and orange juice (112-113). In all cases, specifically designed extraction vessels were utilized. 

Supercritical fluid extraction system - Hewlett Packard Model 7680A totally automated system with unlimited-capacity reciprocating pump, specially designed extraction chamber with safety interlocks, a variable restrictor nozzle and analyte collection trap. The operation of the extractor is controlled by a personal computer which is a Microsoft Windows-based system. An animated status screen provides real-time monitoring of the extraction process. Table II gives the SFE conditions for the HP extractor. 

Mason, G.W. Griffin, H.E. Demonstration of the potential for designing extractants with preselected extraction properties possible application to reactor fuel reprocessing, In Actinide Separations, J.D. Navratil and W.W. Schulz (Eds.), American Chemical Society, Washington, DC (1980), pp. 89-99. 

The self-designed extraction facility consists of a high pressure liquid pump, two heat exchangers, two parallel extraction tubes and a separator with a window and a throttle valve. A mass flow meter gives information about flow rate (kg/h), density, temperature and total mass of the solvent. 

Demonstration of the Potential for Designing Extractants with Preselected Extraction Properties Possible Application to Reactor Fuel Reprocessing... 

The wide range of separation factors, Ku/K h for the extraction of U(VI) and Th(IV) from 2.00 M HNO3 into eleven selected neutral phosphorus-based extractants shown in Table I, demonstrates the potential for designing extractant systems for specific metal separations. The separation factors range from 0.71 for B[DBP] to 162 for D(4-MPe-2) [iBP] a R j/K h ratio of 228. 

Proprietary Extractors. Manufacturers or proprietary design extraction equipment (such as the Podbielniak Centrifugal Extractor or the RTL (raining bucket) Contactor) provide catalogs listing the relative capacities of the various sizes of equipment which are offered. Pilot equipment is usually available for determining extraction performance, and the manufacturer utilizes both the pilot data and experience with similar systems to provide assured commercial designs. 

As before, we find a design of 9 experiments to be the most efficient. The remaining points, 4 and 9, add little information. It can be seen in figure 10.6 that they are very close to point 3. The individual points in the design are very close to those of the D-optimal design extracted from the total data-set of 42 experiments, as just described in section 3. The statistical properties of the two designs, 9 and 9 in table 10.12, are also very close. 

Many groups have published phase behavior data which is needed to design extraction and reaction processes necessary for these applications [13,17,31,33,37,... 

The kfr here is for use with a driving force expressed as Aca. To obtain a suitaUe fi>r use with Axa, the right-hand side of Eq. (7.1-31) must be multiplied by (plM) for the disperse phase between I and 2. Equation (7.i-3I) is used in the design extraction equipment such as spn colnmns, perforated plate... 

One category of the vadose zone treatment technologies which has been apphed in relatively numerous instances is soil vapor extraction (SVE) (with or without the introduction of air) (Hutzler et ai, 1989 Johnson et ai, 1990, 1994). The most effective apphcations of SVE employ careful control of apphed vacumn through designed extraction points about which are arrayed air introduction points to ensure airflow through the most contaminated zones. Figure 6a shows a typical SVE process diagram (NRC, 1994). Success with SVE methods has been more difficult to achieve where toxic nonvolatile compoimds are present in the source, or where permeabihty of the subsurface limits the zone influence of gas flow. 

Precious metal feed materials are almost always leached in HCl, with chlorine gas as the oxidizing agent. The dominant aqueous species formed under these conditions are shown in Table 5.7. A variety of oxidation states and coordination structures exist. These differences are exploited in designing extractant systems that will be selective for one element over the others (Al-Bazi and Chow 1984). 

Table 3 Typical predicted properties of the designed extractants.

The essential parameter in designing extractions is die distribution coefficient Kq which expresses the ratio ... 

Source Valko, K., et al. "Chromatographic Hydrophobicity Index by Fast Gradient RP-HPLC A High Tliroughput Alternative to P/logD." Analytical Chemistry, 691997,2022-2029. As an interesting tidbit, this article has a comprehensive table of lipophilicity values that can be useful in designing extractions. 

Plant design extracts the isometrics from the 3-D electronic model automatically. The isometric checker reviews each isometric. The stress engineer then signs off on the isometric. The extraaed isometric also includes pipe supports. 

---