Pressure Swing Adsorber Unit

For the production of high purity helium from raw helium, pressure swing adsorbers are used, since helium is only poorly adsorbable, whereas methane and nitrogen are relatively well adsorbed. Thus, with zeolitic molecular sieves and fine-pored activated carbons, purities of 99.999-99.9999% molar fraction of helium can be adjusted without additional purification steps. A typical Pressure Swing Adsorber Unit (PSA) is shown in Fig. 4.2 [4.2] ... 

The objectives of the present study were to decrease the basic complexity of PSA and to increase its productivity - the amount of product produced per unit time per unit weight of adsorbent. Success in both of these areas should further enhance process economics and increase the potential application for pressure-swing-adsorption-based processes. 

After further heat recovery, final cooling and condensate separation (6), the gas is sent to the pressure swing adsorption (PSA) unit (7). Loaded adsorbers are regenerated isothermally using a controlled sequence of depressurization and purging steps. 

Pressure Swing Adsorption (PSA) unit is a dynamic separation process. In order to create a precise model of the process and thus an accurate design, it is necessary to have a good knowledge of the mixture s adsorption behaviour. Consequently, the dilAision rates in the adsorbent particles and the mixture isotherms are extremely vital data. This article intends to present a new approach to study the adsorption behaviour of isomer mixtures on zeolites. In a combined simulation and experimental project we set out to assess the sorption properties of a series of zeolites. The simulations are based on the configurational-bias Monte Carlo technique. The sorption data are measured in a volumetric set-up coupled with an online Near Infra-Red (NIR) spectroscopy, to monitor the bulk composition. Single component isotherms of butane and iso-butane were measured to validate the equipment, and transient volumetric up-take experiments were also performed to access the adsorption kinetics. 

Recent developments in rapid pressure swing H2 PSA processes are described. The rapid cycles are used to reduce adsorbent inventories, to reduce vessel size, and to lower the overall cost of the PSA unit. Research in the area of rotary valves and structured adsorbents, which enable the RPSA cycles, is outlined. 

The pilot unit consists of six reactors, each six meters tall. The reactors contain beds of pellets that simultaneously catalyze the water gas shift reaction and adsorb CO2. The unit is operated as a reactive pressure swing adsorption installation. By switching valves, the reactors are operated in cycles of C02-adsorption and desorption. Since at any time, at least one reactor is in adsorption mode and at least one reactor in desorption mode, a continuous production of purified hydrogen (and CO2) is obtained. Design, engineering, construction, and commissioning of the unit took less than one year. 

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