Abstract: A process is provided for the purification of natural gas wherein the nitrogen content of natural gas is reduced to pipeline specification using a pressure swing adsorption processes with a suitable selective adsorbent for methane purification. More specifically, the present invention relates to the use of a particular combination of steps in the PSA cycle to produce a product natural gas having a reduced nitrogen content, a nitrogen-rich stream and a high heat content fuel gas stream.

Abstract: Disclosed are a process and apparatus for virtually complete isomerization of normal paraffin hydrocarbons which reduces recycle rates and enables operation of reactors and adsorbers at more favorable conditions and otherwise improve operating efficiencies based on constant quantities of adsorbents and catalysts. Also, and according to a preferred embodiment, a process and apparatus are provided for utilizing reformer offgas as a hydrogen makeup in such a process wherein the offgas is first purified by a pressure swing adsorption apparatus. Reactor and adsorber pressures and recycle rates can be lowered due to higher concentration of hydrogen in the recycle stream and higher reactant concentrations in the reactor. Recycle capital and operating costs are greatly reduced.

Abstract: The present invention provides a method and apparatus for automatically controlling product purity in a pressure swing adsorption process without risking unacceptable impurity breakthrough as the feedstock changes, yet providing rapid response and high stability. The process comprises sensing a characteristic of the effluent from cocurrent depressurization, and taking corrective action responsive thereto. Any action can be taken which is effective to vary the impurity concentration in the product gas in the direction necessary to obtain desired product purity. Among the suitable corrective actions are the following: (1) adjusting the adsorption step time to control the impurity loading of each adsorbent bed; (2) adjusting the cocurrent depressurization termination pressure to control the impurity breakthrough at the product end of each adsorbent bed; and/or (3) adjusting the amount of purging gas received by each adsorbent bed to control the extent of regeneration.

Abstract: Normal paraffins present in high concentrations in light naphtha streams are separated from non-normal paraffins in a four or more bed adsorption system employing, on a cyclic basis, the processing steps of (1) cocurrent purge/adsorption, (2) cocurrent feed/adsorption, (3) countercurrent purge and (4) countercurrent displacement. A processing sequence is employed wherein the cocurrent purge/adsorption and countercurrent purge steps are carried out on a discontinuous basis, while cocurrent feed/adsorption and countercurrent displacement steps are carried out in overlapping sequence.

Abstract: An invention is described in which a portion of one of the product streams from an adsorption system is used to wash a recycle gas stream in order to improve the quality of one of the products.