Stripping efficiency

Estimate stripping efficiency for components other than the key by ... 

Absorption Efficiency, or fraction absorbed Overall tray efficiency, fraction Stripping efficiency, or fraction stripped Fraction of v + li absorbed by the liquid Fraction of loi stripped out of the liquid Mols individual components stripped per hour Total heat of absorption of absorbed components, thousand Btu/day... 

Kremser-Brown-Sherwood Method — No Heat of Absorption, 108 Absorption — Determine Component Absorption in Fixed Tray Tower, 108 Absorption — Determine Number of Trays for Specified Product Absorption, 109 Stripping — Determine Theoretical Trays and Stripping or Gas Rate for a Component Recovery, 110 Stripping — Determine Stripping-Medium Rate for Fixed Recovery, 111 Absorption — Edmlster Method, 112 Example 8-33 Absorption of Hydrocarbons with Lean Oil, 114 Inter-cooling for Absorbers, 116 Absorption and Stripping Efficiency, 118 Example 8-34 Determine Number of Trays for Specified Product Absorption, 118 Example 8-35 Determine Component Absorption in Fixed-Tray Tower, 119 Nomenclature for Part 2, 121... 

Up to a certain point, stripping efficiency is proportionate to increasing the stripping steam rate. However, excess stripping steam overloads... 

Catalyst residence time in the stripper is determined by catalyst circulation rate and the amount of catalyst in the stripper. This amount usually corresponds to the quantity of the catalyst from the centerline of a normal bed level to the centerline of the lower steam distributor. A higher catalyst residence time, though it increases hydrothermal deactivation of the catalyst, will improve stripping efficiency. 

Four stages are needed. The strip raffinate has a concentration of 1.71, and the stripped organic contains only 2% (0.0073/0.35) of the component A in the scrubbed extract, so the stripping efficiency is 98%. The less extractable (more readily stripped) component B was completely stripped in three stages. 

Air stripping of pharmaceutical wastewater is a partial treatment used in particular for the removal of volatile organics from wastewater. M/S Hindustan Dorr Oliver, Bombay, in 1977 studied the effect of air stripping on the treatment of pharmaceutical wastewater and reported that a COD removal efficiency up to 30-45% can be achieved by air stripping. It was found that adding caustic soda did not appreciably increase the air stripping efficiency. 

Disrupt uniform catalyst flow and catalyst to steam contacting in the spent catalyst stripper zone as reflected by rednced stripping efficiency. 

Cold flow tests indicate that a too high superhcial mass flux in the stripper causes a dramatic decrease in stripping efficiency. The normal stripping steam flow pattern is disrupted to the point where stripping steam becomes entrained downward [6]. 

Each component has a specific function. The Metasilicate will increase paint stripping efficiency provided sufficient alkalinity is present. The Gluconate or Glucoheptonate provide the derusting. Burco TME and Burco ADS-100 provide removal and dispersion of particulate soils while the Dodecylbenzenesulfonate adds wetting and oily soil detergency. Each component can be adjusted according to the improvement needed. 

One of the main reasons for this sort of poor stripping efficiency is subcooled liquid feed to the stripper. Liquid drawn from any tower or vessel is assumed to be in equilibrium with the vapor phase in the tower or vessel. We say that the liquid is at its bubble point, or boiling... 

If liquid drawn from a column cools below its bubble point, as a result of ambient-heat loss, we say it is subcooled. Mixing a small amount of steam with subcooled liquid, will reduce the partial pressure of any vapor in contact with the liquid, but not enough to promote boiling. Eventually, as more and more steam is mixed with a subcooled liquid, it will begin to boil. But, for a given amount of steam, the amount of vapor that can be boiled out of a liquid will always be less if the liquid is subcooled. In this way, ambient-heat loss reduces the stripping efficiency of steam. 

Wet steam will also reduce stripping efficiency. The water in the steam will be turned into steam when it contacts the hot diesel oil in the stripper, shown in Fig. 10.1. The heat of vaporization for this water must come from the sensible heat of the diesel. This reduces the temperature of the diesel, which also reduces its vapor pressure, which then makes it more difficult to vaporize its lighter gasoline components. 

High liquid levels in the bottom of the stripper will also reduce stripping efficiency. A liquid level above the steam inlet will cause the stripping trays to flood. Flooding vastly decreases tray efficiency, and hence stripping efficiency. 

From the designer s point of view, the top tray of the stripper must have a several times greater number of sieve holes or valve caps on its tray deck than the bottom tray. If, however, all the trays in the stripper are identical, then either the bottom tray will leak (see Chap. 2), or the top tray will flood. Either way, stripping efficiency will suffer. 

Uses of Oldershaw columns to less conventional systems and applications were described by Fair, Reeves, and Seibert [Topical Conference on Distillation, AIChE Spring Meeting, New Orleans, p. 27 (March 10-14, 2002)]. The applications described include scale-up in the absence of good VLE, steam stripping efficiencies, individual component efficiencies in multicomponent distillation, determining component behavior in azeotropic separation, and foam testing. 

The scrub solution joins the aqueous waste feed stream to constitute the aqueous phase in the extraction section of the contactor cascade its low flow rate and low electrolyte concentration have little effect on the extraction section. The scrubbed solvent passes to the strip section of the cascade, where it is contacted with 1 mM nitric acid to transfer the cesium to the aqueous phase. This concentration of nitric acid was chosen to minimize the DCs for best stripping efficiency, while maintaining sufficient acidity to keep the amine protonated and sufficient ionic strength for adequate coalescence. 

All reactive stripping experiments showed that reducing the water content level (due to better stripping performance) increases the per-pass conversions, but has a negative effect on selectivity in the chosen model reaction system. Nonetheless, the water contents are the result of a balance between stripping efficiency and catalyst hold-up. As a consequence, the space-time yield was highest for katapak-S , whereas in DX -packings, the excellent separation efficiency optimized the use of catalyst, but decreased the selectivity. For industrial applications, the choice will always depend on the balance between mass transfer performance, the kinetics, the activity of the catalyst, and the process economics. 

The stripping efficiency of a deodorizer can be improved either by incorporating a packed column or by reducing the operating pressure of the deodorizer (Table 15). The best solution, of course, is a combination of both, but this results in an expensive deodorization technology. 

Aside from a higher stripping efficiency, a packed column is also characterized by a very short holdup time. This may be sufficient for the stripping of certain volatile components (e.g., FFA, tocopherols, etc.) but not enough for a complete deodorization. Therefore, a holding vessel is usually placed after a packed column to properly deodorize the oil. The steam introduced in the retention vessel can be reused as stripping vapor for the packed column, which reduces overall steam consumption. The reuse of this dirty steam, however, may have a negative effect on the final oil quality. 

The main advantages of the packed column are the higher stripping efficiency and the short residence time (only a few minutes). 

The higher stripping efficiency is important because it will result in a lower overall steam consumption to achieve a given final FFA content. However, part of this advantage is lost because of the pressure drop over the structured packing. 

Extraction and stripping efficiency is greatly enhanced with smaller droplets due to an increased surface area for diffusion. In the study of copper ion extraction, Cahn et al. [45] have shown that the average size of the internal phase droplets significantly influence the extraction rate. They also report that smaller droplets enhance membrane stability and retard leakage. The internal phase and its impact on the ELM process are discussed in Section 25.4. 

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