Separation method and apparatus

A method of separating a component from a feed gas stream comprising:

• introducing the feed gas stream to a retentate side of a membrane and separating the component from the feed gas stream such that the component collects at a permeate side of the membrane by establishing a positive partial pressure difference of the component between the retentate side and the permeate side;
• circulating a sweep stream in a vapor state to the permeate side of the membrane to at least in part establish the positive partial pressure difference and thereby to form a component laden sweep stream, the sweep stream formed from a multi-component mixture containing at least one higher boiling component and at least one lower boiling component that are not formed by the component of the feed gas stream;
• the sweep stream in the vapor state formed by heating the sweep stream in a liquid state;
• the sweep stream being heated, at least in part, through indirect heat exchange with the component laden sweep stream, thereby to at least partially condense the at least one higher boiling component contained in the component laden sweep stream and thereby to form a two-phase stream from the component laden sweep stream having the component in a vapor phase thereof and to at least partially vaporize the at least one lower boiling component in the sweep stream in the liquid state;
• cooling the two-phase stream such that a liquid phase of the two-phase stream is enriched in a substance making up the sweep stream and a vapor phase thereof is enriched in the component;
• separating the vapor phase from the liquid phase to produce a component-rich stream containing the component and a residual liquid stream containing the substance;
• and
• recirculating the residual liquid stream as at least part of the makeup for the sweep stream in the liquid state.

An apparatus for separating a component from a feed gas stream comprising:

• a membrane unit having at least one membrane configured to receive the feed gas stream on a retentate side of the membrane and to separate the component from the feed gas stream such that the component collects at a permeate side of the membrane when a positive partial pressure difference of the component is established between the retentate side and the permeate side;
• a flow network configured to circulate a sweep stream to the permeate side of the at least one membrane, thereby to at least in part establish the positive partial pressure difference and thereby form a component laden sweep stream;
• a pump positioned within the flow network such that-the sweep stream in a liquid state is pumped to a supercritical pressure and to circulate the sweep stream to the least one membrane and the component laden sweep stream from the at least one membrane at the supercritical pressure;
• heat exchangers positioned within the flow network and configured to indirectly exchange heat between the component laden sweep stream and the sweep stream in the liquid state, after having been pumped and while the sweep stream and the component laden sweep stream are at the supercritical pressure, such that the sweep stream is heated, at least in part, to a temperature level of no less than 100° F. below a supercritical temperature and the component laden sweep stream is cooled, thereby to form a two-phase stream from the component laden sweep stream having the component in a vapor phase thereof and to cool the two-phase stream such that a liquid phase of the two-phase stream is enriched in a substance making up the sweep stream and a vapor phase thereof is enriched in the component;
• at least one phase separator positioned within the flow network to receive the two-phase stream after having been cooled, thereby to separate the vapor phase from the liquid phase and to produce a component-rich stream containing the component and a residual liquid stream;
• the pump connected to the at least one phase separator such that at least the residual liquid stream is pumped by the pump to the supercritical pressure and the residual liquid stream therefore, forms at least part of a makeup for the sweep stream in the liquid state and the pump also connected to one heat exchanger of the heat exchangers;
• and
• the one heat exchanger connected to the permeate side of the at least one membrane such that the component laden sweep stream is directly introduced from the at least one membrane to the one heat exchanger and the indirect heat exchange between the sweep stream in the liquid state and the component laden sweep stream occurs within the one heat exchanger and thereby forms the two-phase stream.

An apparatus for separating a component from a feed gas stream comprising:

• a membrane unit having at least one membrane configured to receive the feed gas stream on a retentate side of the membrane and to separate the component from the feed gas stream such that the component collects at a permeate side of the membrane when a positive partial pressure difference of the component is established between the retentate side and the permeate side;
• a flow network configured to circulate a sweep stream in a vapor state to the permeate side of the membrane, thereby to at least in part establish the positive partial pressure difference and thereby form a component laden sweep stream;
• the sweep stream formed from a substance composed of a multi-component mixture containing at least one higher boiling component and at least one lower boiling component that are not formed by the component of the feed gas stream;
• a pump positioned within the flow network such that the sweep stream in a liquid state is pressurized;
• heat exchangers positioned within the flow network and configured to indirectly exchange heat between the component laden sweep stream and the sweep stream in the liquid state, after having been pumped, such that at least the at least one lower boiling component contained in the sweep stream in the liquid state is at least partially vaporized and the at least one higher boiling component in the component laden sweep stream is at least partially condensed, thereby to form a two-phase stream from the component laden sweep stream having the component in a vapor phase thereof and to cool the two-phase stream such that a liquid phase of the two-phase stream is enriched in the substance making up the sweep stream and a vapor phase thereof is enriched in the component;
• at least one phase separator positioned within the flow network to receive the two-phase stream after having been cooled, thereby to separate the vapor phase from the liquid phase and to produce a component-rich stream containing the component and the residual liquid stream;
• the pump connected to the at least one phase separator such that at least the residual liquid stream is pumped by the pump and the residual liquid stream therefore, forms at least part of a makeup for the sweep stream in the liquid state and the pump also connected to one heat exchanger of the heat exchangers;
• and
• the one heat exchanger connected to the permeate side of the at least one membrane such that the component laden sweep stream is directly introduced from the at least one membrane to the one heat exchanger and the indirect heat exchange between the sweep stream in the liquid state and the component laden sweep stream occurs within the one heat exchanger and thereby forms the two-phase stream.