Adsorber Vessel

Pressure Swing Adsorption. A number of processes based on Pressure Swing Adsorption (PSA) technology have been used in the production of carbon dioxide. In one version of the PSA process, CO2 is separated from CH using a multibed adsorption process (41). In this process both CH4 and CO2 are produced. The process requires the use of five adsorber vessels. Processes of this type can be used for producing CO2 from natural gas weUs, landfiU gas, or from oil weUs undergoing CO2 flooding for enhanced oil recovery (see Adsorption, gas separation). 

Adsorber Vessel The most frequently used method of fluid-solid contac t for adsorption operations is in cyhndrical, vertical vessels, with... 

FIG. 16-46 Pressurized adsorber vessel. (Reptinted with peirrussion of EPA. Reference EPA, Process Design Manual for Carbon Adsorption, U.S. Envir. Protect. Agency., Cincinnati, 1973.)... 

HG. 16-47 Ambient pressure adsorber vessel. (Reptinted with permission of Ann Arhor Science. Reference Leatherdale in Cheremisinoff and Ellerhusch, Carbon Adsorption Handbook, Ann Arhor Science, Ann Arhor, 1978. )... 

FIG, 16-52 Hypersorption adsorber vessel [Reptinted with permission of AIChE. Reference Berg, Chem. Eng. Progr., 47, 585 590 (1951).]... 

FIG, 16-53 PiiraSiv HR adsorber vessel. [Reprinted with permission of Chemical Engineering. Reference Anon., Chem. Eng., 84(18), 39 0 (1977).]... 

A larger fraction of the heat content of the steam is used up to heat the adsorber vessel and the adsorbent thus, it is essential that the steam condenses quickly in the bed. The steam should contain only a slight superheat to allow condensation. 

Internal or external insulation for the adsorbers may be used. The main purpose of internal insulation is to reduce the total regeneration gas requirements and costs. Internal insulation eliminates the need to heal and cool the steel walls of the adsorber vessel. Normally, a castable refaciory lining is used for internal insulation. The refractory must be applied and properly cured to prevent liner cracks. Liner cracks will per-... 

In each step in the process there is a change in the adsorbate (impurity) loading on the adsorbent bed and a change in the total gas storage within the adsorber vessel. These changes are caused by ... 

The third process used in the production of carbon dioxide is pressure swing adsorption. The feed gas usually contains approximately 20 percent carbon dioxide, 70 percent hydrogen, and the remainder methane, carbon monoxide, nitrogen, and water. The feed gas is typically under a pressure of 125 100 psig at temperatures of 80-120°F. The carbon dioxide and water are strongly adsorbed in the adsorb beds and the residual gas stream is depressurized for further recovery. The adsorber vessel is then evacuated through vacuum blowers where the carbon dioxide, which has been adsorbed by the bed, is released at purities of essentially 99+ percent pure. 

The concept is to use frister cycle times (seconds) than those used by the conventional PSA cycles (minutes) in order to obtain a step change in the productivity of the process (volume of product/volume of adsorbent our). Some of these designs use a conventional PSA cycle but they are operated faster by appropriate changes in the mechanical designs [6]. Others, propose novel process schemes in order to accommodate t cycle times [7-9]. An example of the second case is a RPSA process for air separation where a single adsorber vessel is packed with two or more (even numbers) shallow layers of small zeolite particles (-0.5 mm). The layers are separated... 

The adsorbent is placed in an annular section between two co-axial cylinders. The walls of the cylinders are perforated for gas flow in a radial direction. The entire assembly is enclosed inside the adsorber vessel with gas inlet and outlet conduits. Many different designs are patented [11-13]. The adsorbers allow faster cycle times, lower pressure drops, and higher gas dirou puts without fluidization. However, the equipment design is more complex and costly. 

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