System and method for removing acid gas from a sour gas stream

#Embodiments of the present disclosure generally relate to methods and systems for removing acid gas from a sour gas stream and more specifically relate to maintaining thermal control of the process with an encapsulated phase change material.

#Amine gas treating, also known as amine scrubbing, gas sweetening and acid gas removal, is a process that uses aqueous solutions of various amines to remove hydrogen sulfide (H2S), carbon dioxide (CO2), and other acid gases from sour gas streams. It is a common unit process used in refineries, petrochemical plants, natural gas processing plants and other industries. Amine gas treating is present in various industries as natural gas and commonly contains H2S and CO2 when removed from the ground. However, it is desirable to have those constituents removed before utilizing the natural gas in further processes as they may cause undesirable side reactions, corrode process piping, or lead to other undesirable outcomes. During amine gas treating the temperature of the aqueous solutions used in the process increase in temperature as a result of the exothermic treating reactions. Left uncontrolled the temperature of the amine gas treating systems may increase to an undesirable point leading to process inefficiencies, equipment damage, processing speed limitations, or other undesirable outcomes. Current amine gas treating processes are limited in their ability to control temperature increase of the aqueous solutions used in the processes.

#Ongoing needs exist for methods and related systems of removing acid gas from a sour gas stream and more specifically methods and related systems which maintain thermal control of the acid gas removal process. Inclusion of an encapsulated phase change material in the system for acid gas removal provides added temperature control and stability.

#FIG. 1A is a representative temperature profile in a standard amine-based absorption process.

#FIG. 1B is a representative temperature profile in an enhanced amine-based absorption process with encapsulated phase change material in accordance with one or more embodiments of the present disclosure.

#FIG. 2 is a schematic illustration of an absorption reaction of monoethanolamine (MEA) with carbon dioxide in the presence of encapsulated phase change material in accordance with one or more embodiments of the present disclosure.

#Reference will now be made in detail to embodiments of the method of removing acid gas from a sour gas stream of the present disclosure and associated system.

#Sour gas is natural gas or any other gas containing significant amounts of hydrogen sulfide (H2S) or other acid gas such as carbon dioxide which are desirably removed before utilization of the natural gas in further operations. Sour gas with the acid gases eliminated or reduced to below a threshold value is termed sweet gas. Acid gases are deleterious to operations in the oil and gas industry interfering with desired utilization of natural gas. For example, acid gases may interfere with chemical reactions or the simple burning of the natural gas. Additionally, the presence of acid gases in the natural gas may have a corrosive to other undesirable effect on piping and other process systems which it contacts during utilization. As such, the methods of removing acid gas from a sour gas stream and associated systems provided in the present disclosure advance the usability of collected sour gas by the elimination of the acid gases from the provided sour gas stream.

#The removal of acid gases from a sour gas may be achieved using an absorption process. An absorption process utilizes a mass transfer operation in which acid gases, such as carbon dioxide or hydrogen sulfide, are absorbed from the sour gas by means of a liquid in which the solute gas is more or less soluble. In the oil and gas industry, a common absorption process is an amine-based process, also known as “amine treating” or “amine scrubbing” to those skilled in the art. In an amine-based process, an amine solution is directly or indirectly contacted with the sour gas to allow for the absorption of acid gases therein for removal.