Multistage stabilization

Compressors are used whenever it is necessary to flow gas from a lower pressure to a higher pressure system. Flash gas from low-pressure vessels used for multistage stabilization of liquids, oil treating, water treating, etc., often exists at too low a pressure to flow into the gas sales pipeline. Sometimes this gas is used as fuel and the remainder flared or vented. Often it is more economical or it is necessary for environmental reasons to compress the gas for sales. In a gas field, a compressor used in this service is normally called a flash gas compressor. Flash gas compressors are normally characterized by low throughput rate and high differential pressure. 

Low-temperature exchange (LTX) units use the high flowing temperature of the well stream to melt the hydrates after they are formed. Since they operate at low temperatures, they also stabilize the condensate and recover more of the intermediate hydrocarbon components than would be recovered in a straight multistage flash separation process. 

From a hydrate melting standpoint it is possible in the winter time to have too cold a liquid temperature and thus plug the liquid outlet of the low temperature separator. It is easier for field personnel to understand and operate a line heater for hydrate control and a multistage flash or condensate stabilizer system to maximize liquids recovery. 

In almost all cases the molecules have a higher value as liquid than as gas. Crude oil streams typically contain a low percentage of intermediate components. Thus, it is not normally economically attractive to consider other alternatives to multistage separation to stabilize the crude. In addition, the requirement to treat the oil at high temperature is more important than stabilizing the liquid and may require the flashing of both intermediate and heavy components to the gas stream. 

The physicochemical models consistent with foam formation and stabilization are derived from the work on pasteurized and UHT processed miUc-creams advanced by Besner (1997). Foam formation and stabilization can basically be explained as a multistage process, with some significant differences between non-homogenized (pasteurized cream) and homogenized (UHT cream) systems. These differences... 

Stabile, R.L., Economics of reverse osmosis and multistage evaporation for concentrating skim milk from 8.8% to 45% solids, J. Dairy Sci., 66, 1765, 1983. 

Reaction orders in monomer and transition metal compound are normal with most catalysts, but reactions second order in monomer have been reported for TiCl4/ZnBu2 [140] and Al/TiC [141]. No data on the stabilities of the active sites are available so it is not possible to decide whether these observations imply the involvement of two monomer units in the propagation step. It is to be noted that, with catalysts from zinc alkyls with a-TiClj, the rates decline rapidly with time at constant monomer concentration [94], while the latter system is complex in that active species are produced in a multistage reaction sequence (indicated by an induction period and an acceleration stage) and the operating conditions are severe (150 C and 10—70 kg cm ethylene pressure). 

The search for new methods of HTSC synthesis is stimulated by the necessity of combining HTSCs in various devices with certain metals, semiconductors, or dielectrics. In each particular case, the technologies should be based on a method that simultaneously ensures the stability of all the materials in the configuration as well as the optimal characteristics for performance. Therefore, multistage combined methods which have the potential for optimization are finding increased use. 

Chemical activity Apparent contact time 3 < T < 30 sec Stability of operation Homogeneous temperature in bed LJDt = 1-2 High activity excess reaction in dilute phase Low activity decrease of reaction yield Dilution with inert particles Multistage fluid bed... 

As noted in the introduction to this chapter and in Section 16.1, several factors may compromise the effectiveness and stability of conventional control techniques for multiple variable processes, and specifically for multistage separations. A successful, comprehensive control strategy for such processes must take into account these factors, most of which are interrelated. 

The mantle up to several hundred kilometers beneath the continents, particularly under the older cratons, forms deep keels characterized by fast seismic velocities, is Mg-rich, and depleted in Fe. It is less dense than the surrounding mantle, a factor that imparts stability to the keels, which thus float under the continents. Although the low Fe/Mg ratio and low Ca and A1 contents are generally attributed to the extraction of a partial melt, this subcontinental lithospheric mantle (SCLM) is apparently enriched in incompatible elements such as Ba, Th, U, Ta, Nb, La, Ce, and Nd and depleted in HREE, Ti, Sc, V, Al, and Ca relative to average abundances in the mantle. This element pattern indicative of both enrichment and depletion indicates that multistage processes must have occurred, with an initial extraction of a partial melt, followed by at least one stage of a secondary enrichment, often referred to a metasomatic event. Curiously, this event has apparently not affected the Fe/Mg ratios. 

The extraction of heavy hydrocarbons from the gas is conducted in a special multistage absorber equipped with devices for condensate deflation. A higher efficiency of extraction of heavy hydrocarbons from the separated gas and a higher quality of condensate stabilization is achieved as the result. 

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