Systems and processes disclosed herein relate to the recovery of sorbates that are removed from process streams by adsorption.
The separation of specific components of process streams in certain applications can be accomplished by the use of adsorption to remove the desired component, followed by recovery of the component during regeneration of the adsorbent. Process streams are typically liquid or gaseous, and can have a wide variety of compositional components depending upon the industrial application of the process.
Packed beds of adsorbent materials are typically used in adsorption processes. Adsorbent materials are generally in the form of spherical beads, or pellets. Adsorbent materials are typically oxygen-containing compounds, carbon-containing compounds, or polymer-based compounds. Oxygen-containing compounds can be, for example, hydrophilic and polar, including materials such as silica gel and zeolites. Carbon-based compounds can be, for example, hydrophobic and non-polar, including materials such as activated carbon and graphite. Polymer-based compounds can be, for example, polar or non-polar functional groups in a porous polymer matrix.
Typical adsorption processes utilizing packed beds can be thermal (temperature) swing adsorption (TSA) processes or pressure swing adsorption (PSA) processes. In operation, a process stream is introduced into a packed bed, and the adsorbent material contained therein removes a desired component, known as the sorbate, from the stream as it filters through the packed bed. After a given time period, the adsorbent material becomes saturated with the sorbate, and the adsorption process must be halted in order to regenerate the adsorbent and remove the sorbate. PSA processes utilize a de-pressurized regeneration gas that is introduced to the packed bed in a direction reverse to the flow of the process stream. After a regeneration cycle is complete, a new adsorption cycle can begin. TSA processes utilize heat to remove the sorbate from the adsorbent material. The heat in a typical TSA process is added through the regeneration stream. Thus, the regeneration or purge gas can be utilized to supply all of the heat required to heat the vessel, bed supports, and the adsorbent, as well a providing the energy to desorb the sorbate from the adsorbent. A large volume of regeneration gas is necessary to accomplish this task, which results in a very dilute regeneration effluent stream, which increases the cost of processes utilized to recover the sorbate from the regeneration effluent stream.