Pressure absorption

Processing pressure - generally, the carrying capacity of physical solvents increases with absorption pressure much more rapidly than that of chemical solvents (A). Therefore, AGR at high-pressures may make physical solvents look attractive, while low-pressure operation favors chemical solvents. 

Absorption test starts with purging process as well as evacuation and then system is thermally stabilized under vacuum. Subsequently, hydrogen at desired absorption pressure is admitted into the system and by observing the pressure decreasing as a function of time, the kinetic curve is registered. 

Absorption pressure-composition isotherms were established by metering fixed amounts of hydrogen into the system and determining the pressure after equilibrium. In each case, the sample chamber was isolated before hydrogen... 

The reactor effluent usually contains a mixture of reactants and products. It is fed into a separation section where the products are separated by some means from the reactants. Because of their economic value, reactants are recycled back to upstream units toward the reactor. The products are transported directly to customers, are fed into storage tanks, or are sent to other units for further processing. The separation section uses one or more of the fundamental unit operations distillation, evaporation, filtration, crystallization, liquid-liquid extraction, adsorption, absorption, pressure-swing adsorption, etc. In this book we typically use distillation as the separation method because of its widespread use and our considerable experience with it. Everyone is a victim of his or her experience. Our backgrounds are in petroleum processing... 

Absorption pressure Dissociation pressure at298K[MPa] at298K[MPa]... 

Similar effects have been found in pressure composition isotherms of LaNi5Hx measured volumetrically [11]. Figure 4 shows variations of the absorption pressure with time to execute an entire measurement loop. As clearly visible, even after a measurement time of one week per cycle, changes in the plateau pressures are observable. 

EXPOSURE ROUTES Inhalation (air in pressure treated log homes) ingestion (contaminated food/drinking water) absorption (pressure treated lumber) occupational exposure. 

Major applications of the absorption processes are the removal of acid gas components such as CO2 and H2S from gas mixes. Cases are not infrequent, however, in which other raw gas components such as higher hydrocarbons, trace impurities (metal carbonyls, NH3) or steam are eliminated either alone or in combination with acid gas components. Absorption processes, which by their very essence are gas separation processes, are as a rule used for gas purification, i.e. undesired components are eliminated fix>m a gas mix without significantly changing its pressure. Some absorption processes are, however, used to recover individual gas components. In these processes, the normally larger undesirable portion of the gas mix is left at absorption pressure while the desired gas component, after it has been desorbed, is usually obtained at ambient pressure. 

Lang et al. [80] were one of the early teams who lent support to the development of the above idea while working with aqueous solutions of sodium lauryl sulfate and laurylpyridinium chloride, bromide and iodide (CMC known in each case), and dissolved salts. They noticed two relaxation processes in the above micellar systems by examination through ultrasonic absorption, pressure jump, temperature jump and shock tube measurements. The two relaxation processes, one relatively fast and the other slow, were dependent on the... 

Absorption is an exothermic process, i.e., during the absorption process heat is released. If this heat cannot be removed, the temperature of the phase streams increases. Since the residence time in the absorber for the gas phase is short and its heat capacity is small at low absorption pressure, the heat of absorption is mainly removed by the liquid phase. In adiabatic absorption processes a significant increase in temperature... 

Depending on the purity required, hydrogen can be further processed by cryogenic adsorption, solvent absorption, pressure swing adsorption (PSA), cryogenic absorption using liquid nitrogen, membrane separation, and metal hydride adsorption. 

Industrial processes are single-pressure or two-pressure. In the single-pressure process, the absorption takes place at the same pressure as the catalytic oxidation. In the two-pressure process, the absorption pressure is higher than the catalytic oxidation. The cataljdic oxidation (first reaction) is favored by low pressures and the two subsequent reactions (nitric oxide oxidation and reaction with water) by high pressure. Therefore, newer plants tend to operate with the two-pressure process. The main advantage is less platinum consumption. 

Typical results from the pilot-plant test reported by Field et al. (1960) for simultaneous absorption of hydrogen sulfide and carbon dioxide are shown in Table 5-4. The absorption pressure w as 300 psig and the regeneration pressure slightly above atmospheric. No attempt was made to remove hydrogen sulfide selectively. 

Comparative operating data for two plants using solutions with and without Catacarb catalyst are shown in Table 5-7 (Eickmeyer, 1962). Plant A operated at an absorption pressure of 360 psig with single stage, uncooled absorption. Plant B used split-stream absorption at 300 psig with cooling of the smaller liquid stream. For Runs 1 and 2 in Plant A these data show that catalyst addition resulted in increased capacity and appreciably lower steam consumption for the same treated gas carbon dioxide concentration. In Runs 3 and 4 in Plant A and in Runs 5 and 6 in Plant B, use of the catalyzed solution appreciably improved the treated gas purity and heat economy,... 

The amount of BTEX absorbed in the contactor is a function of its solubility in the glycol used, concentration in the feed gas, absorption pressure and temperature, number of theoretical trays, and glycol circulation rate. The Henry s law constant for benzene in TEG at 1,000 psia is plotted in Figure 11 37, which presents values calculated by Fitz and Hubbard (1987)... 

---