High-pressure absorption

FIGURE 23.15 Typical pressure cells as used for high-pressure absorption testing (before insulation applied). 

Not selective High-pressure absorption may require intermediate flashing Commercial - developed for high-pressure natural gas treatment 1,2,3,5... 

W. Witt and H. Knapp, Tray efficiencies in high pressure absorption columns experiments and correlation, German Chem. Engng., 8 (1985) 158-164. 

Whereas a dual-pressure plant or a high-pressure, single-pressure plant (with high pressure absorption) may give acceptable emission levels, the medium-pressure absorption plant must be followed by an abatement system.97... 

High-pressure absorption spectroscopy is widely applicable for studying the reactivity and the selectivity of chemical transformations. Some results are shown concerning the investigation of the //ctc/ o-Diels-Alder reactions between the enamine carbaldehyde 1 and enamino ketones 2 with ethyl vinyl ether 3, which lead to the diastereomeric dihydropyrans 4-1-5 and 6 + 7, respectively. Scheme 6.7-1 (Buback et al., 1988 Buback et al., 1989). 

Plants for manufacture of highly concentrated nitric acid and modern high pressure absorption plants ... 

A process using adsorption was used from about 1920 to 1935. This involved adsorption of the gasoline by charcoal and recovery from the charcoal by steaming. High pressure absorption is a newer process for gases which are at high pressure in the field. 

The pilot facility used for the experiments is THAHRA (TNO s High pressure Absorption, Hybrid Regeneration Apparatus). A photo of the apparatus is shown in Figure 3 on the left. 

There is little opportunity to improve further the Oswald nitric acid process. The overall efficiency of ammonia conversion into acid is in the range of 949fr 96%, The process is self-sufficient in energy supply and can even export steam. Up to 80% of platinum catalyst losses can now be recovered. Capital investments were significantly reduced by the development of high-pressure absorption and with the design of efficient and reliable compressors and expanders. Economies of scale improve little for single-train units with capacities above 1,000 tpd. 

Contrary to NH3 oxidation, the absorption of NO2 operates best at high pressure. Thus there is a dilemma as to whether a low or a high pressure should be used. In industrial practice, both the oxidation and the absorption are carried out at constant pressure (Figure 6.4.23) or a combination of low pressure oxidation and high-pressure absorption is applied (dual pressure process. Figure 6.4.24). Table 6.4.5 gives typical data for nitric acid plants. 

Figure 6.4.24 Dual-pressure HNO3 plant using extended high pressure absorption for NO, abatement (BFW boiler feed water). Adapted from Moulijn, Makkee, and Van Diepen (2004).

This work has looked at calculation principles for approx. 200 classic as well as modern randomly filled and stacked lattice packing elements, tube columns and structured packings of various types and sizes. Today, these packings are used not only in rectification in the vacuum and normal pressure range, but also in many areas of high-pressure rectification and high-pressure absorption as well as in waste-air and wastewater treatment and groundwater treatment. 

Deviating from the above stmetural series, Wilmarth et al. (1989) reported phase transitions from the UCI3 -stmcture to the PuBrs -stmcture in the case of PrCls and PrBrs, deduced from high pressure absorption and Raman studies. The same transition was observed also in the case of CfCls (Peterson et al., 1986 Young et al., 1990) and CmCls (Del Cul et al., 1992). In... 

Depending on the process, the most frequently used liquid superficial velocity range is fix>m Z=2 mV(m h), in case of vacuum rectification, to X=300 m /(m h), in case of some high-pressure absorption processes [1]. In some cases of purification of waste gases, the optimal liquid superficial velocity in the packing is some times lower than L=2 sxr/(m ), which requires using distributors able to operate at lower liquid superficial velocities. 

The-use of crude oil as an absorption oil is sometimes economical. The success of the operation depends upon the substitution (see Fig. 22-6) of butanes and pentanes in the crude oil for propane (and ethane) by high-pressure absorption followed by fractionation. 

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