NITROGEN SEPARATION COLUMN SYSTEMS

Abstract

A system for separating nitrogen from hydrocarbon streams comprising a distillation column, a first heat exchange system, and a second heat exchange system. The distillation column has an inlet configured to receive a hydrocarbon feed stream comprising nitrogen and at least 50 mol % hydrocarbons. The first heat exchange system is coupled to a top end of the distillation column and comprises one or more heat exchangers configured to cool the vapor to separate nitrogen from the vapor while simultaneously achieving mass transfer to produce a first product. The second heat exchange system is coupled to a bottom end of the distillation column and comprises one or more heat exchangers configured to heat the liquid to separate liquefied natural gas from the liquid while simultaneously achieving mass transfer to produce a second product.

Claims

1. A system for separating nitrogen from hydrocarbon streams, the system comprising: a distillation column comprising: an inlet configured to receive a hydrocarbon feed stream comprising nitrogen and at least 50 mol % hydrocarbons; and a plurality of trays or packed beds located above and/or below the inlet and configured to separate the hydrocarbon feed stream into vapor and liquid; a first heat exchange system coupled to a top end of the distillation column, wherein the first heat exchange system comprises one or more heat exchangers configured to cool the vapor to separate nitrogen from the vapor while simultaneously achieving mass transfer in the first heat exchange system to produce a first product; and a second heat exchange system coupled to a bottom end of the distillation column, wherein the second heat exchange system comprises one or more heat exchangers configured to heat the liquid to separate liquefied natural gas from the liquid while simultaneously achieving mass transfer in the second heat exchange system to produce a second product.

2. The system of claim 1, wherein the first heat exchange system receives a cooling medium and the one or more heat exchangers of the first heat exchange system are configured to cool the vapor utilizing heat transfer from the cooling medium.

3. The system of claim 2, wherein the first heat exchange system receives a second cooling medium, wherein a first heat exchanger of the one or more heat exchangers utilizes heat transfer from the first cooling medium to cool the vapor, and wherein a second heat exchanger of the one or more heat exchangers utilizes heat transfer from the second cooling medium to cool the vapor.

4. The system of claim 2, wherein the cooling medium is at least one of the hydrocarbon feed stream, mixed refrigerant, methane, natural gas, and combinations thereof.

5. The system of claim 1, wherein the second heat exchange system receives a heating medium and the one or more heat exchangers of the second heat exchange system are configured to heat the liquid utilizing heat transfer from the heating medium.

6. The system of claim 5, wherein the second heat exchange system receives a second heating medium, wherein a first heat exchanger of the one or more heat exchangers utilizes heat transfer from the first heating medium to heat the liquid, and wherein a second heat exchanger of the one or more heat exchangers utilizes heat transfer from the second heating medium to heat the liquid.

7. The system of claim 5, wherein the heating medium is at least one of the hydrocarbon feed stream, mixed refrigerant, methane, natural gas, and combinations thereof.

8. The system of claim 1, wherein the first product comprises about 90 mol % to about 99.99999 mol % nitrogen.

9. The system of claim 1, wherein the hydrocarbon feed stream enters a separation section within the distillation column.

10. A system for separating nitrogen from hydrocarbon streams, the system comprising: a distillation column comprising: an inlet configured to receive a hydrocarbon feed stream comprising nitrogen and at least 50 mol % hydrocarbons; and a plurality of trays or packed beds located below the inlet and configured to separate the hydrocarbon feed stream into vapor and liquid; and a heat exchange system coupled to a bottom end of the distillation column, wherein the heat exchange system comprises one or more heat exchangers configured to heat the liquid to separate liquefied natural gas from the liquid while simultaneously achieving mass transfer in the heat exchange system to produce a product.

11. The system of claim 10, wherein the heat exchange system receives a heating medium and the one or more heat exchangers of the heat exchange system are configured to heat the liquid utilizing heat transfer from the heating medium.

12. The system of claim 11, wherein the heat exchange system receives a second heating medium, wherein a first heat exchanger of the one or more heat exchangers utilizes heat transfer from the first heating medium to heat the liquid, and wherein a second heat exchanger of the one or more heat exchangers utilizes heat transfer from the second heating medium to heat the liquid.

13. The system of claim 11, wherein the heating medium is at least one of the hydrocarbon feed stream, mixed refrigerant, methane, natural gas, and combinations thereof.

14. The system of claim 10, wherein the product comprises about 0.1 mol % to about 50 mol % nitrogen.

15. The system of claim 10, wherein the hydrocarbon feed stream enters a separation section within the distillation column.

16. A system for separating nitrogen from hydrocarbon streams, the system comprising: a housing comprising: an inlet configured to receive a hydrocarbon feed stream comprising nitrogen and at least 50 mol % hydrocarbons; and a separation section, wherein the inlet is configured to direct the hydrocarbon feed stream into the separation section, wherein the separation section is configured to separate the hydrocarbon feed stream into vapor and liquid; a first heat exchange system located at a top of the housing, wherein the first heat exchange system comprises one or more heat exchangers configured to cool the vapor to separate nitrogen from the vapor while simultaneously achieving mass transfer in the first heat exchange system to produce a first product; and a second heat exchange system located at a bottom of the housing, wherein the second heat exchange system comprises one or more heat exchangers configured to heat the liquid to separate liquefied natural gas from the liquid while simultaneously achieving mass transfer in the second heat exchange system to produce a second product.

17. The system of claim 16, wherein the first heat exchange system receives a cooling medium and the one or more heat exchangers of the first heat exchange system are configured to cool the vapor utilizing heat transfer from the cooling medium.

18. The system of claim 16, wherein the second heat exchange system receives a heating medium and the one or more heat exchangers of the second heat exchange system are configured to heat the liquid utilizing heat transfer from the heating medium.

19. The system of claim 18, wherein the heating medium is at least one of the hydrocarbon feed stream, mixed refrigerant, methane, natural gas, and combinations thereof.

20. The system of claim 16, wherein the first product comprises about 90 mol % to about 99.99999 mol % nitrogen.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, may admit to other equally effective embodiments.

[0007] FIG. 1 illustrates a schematic view of a nitrogen separation column, according to one or more embodiments.

[0008] FIG. 2 illustrates a schematic view of another nitrogen separation column, according to one or more embodiments.

[0009] FIG. 3 illustrates a schematic view of a nitrogen separation column system, according to one or more embodiments.

[0010] FIG. 4 illustrates a schematic view of another nitrogen separation column system, according to one or more embodiments.

[0011] FIG. 5 illustrates a method for separating nitrogen from hydrocarbon streams, according to one or more embodiments.

[0012] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

[0013] Embodiments disclosed herein relate to nitrogen separation columns for processing hydrocarbon streams to generate nitrogen and hydrocarbons, such as Gas Processing and/or liquefied natural gas (LNG) production.

[0014] FIG. 1 illustrates an exemplary nitrogen separation column 100. The nitrogen separation column 100 receives an inlet feed 101 from an inlet feed source. The inlet feed 101 may be in the form of liquid, gas, and/or a combination of liquid and gas. The inlet feed 101 (e.g. hydrocarbon feed stream) comprises a mixture of at least hydrocarbons and nitrogen. The inlet feed 101 may also include argon, hydrogen, helium, and/or oxygen. At least 50 mole percent (mol %) or more of the inlet feed 101 may be comprised of hydrocarbons. The inlet feed 101 may comprise nitrogen and at least 50 mol % hydrocarbons. The hydrocarbons may include at least methane and/or ethane. The nitrogen separation column 100 is configured to separate a desired amount of nitrogen and/or hydrocarbons from the inlet feed 101. In some embodiments, the separation of nitrogen causes separation of other light components such as argon, hydrogen, helium, and/or oxygen.

[0015] The nitrogen separation column 100 includes a housing 110, a Reboil Mass Transfer exchanger system (RMX) 120 where simultaneous mass and heat transfer occurs, and a Cold Mass Transfer exchanger system (CMX) 130 where simultaneous mass and heat transfer occurs. The CMX 130 is located on top of, and coupled to the top of, the housing 110. The RMX 120 is located on the bottom of, and coupled to the bottom of, the housing 110.

[0016] In some embodiments, such as the one shown in FIGS. 1-3, the housing 110 is a distillation column (hereinafter referred to as distillation column 110). The distillation column 110 includes a cylindrical vessel and a plurality of packed beds and/or trays 111 (hereinafter referred to as trays 111 for brevity). The distillation column 110 includes an inlet 112 located in the midsection of the distillation column 110 where the distillation column 110 receives the inlet feed 101. The inlet feed 101 flows through the inlet 112 into a separation section 117 of the distillation column 110. Portions of the inlet feed 101 may separate out as vapor in the separation section (such as by flashing due to a drop in pressure upon entering the separation section of the distillation column).

[0017] One or more trays 111 may be located above the inlet 112 (and the separation section 117) and one or more trays 111 may be located below the inlet 112 (and the separation section 117) within the distillation column 110. There may be between 0 and 50 (such as 1, 2, 3, 4, 5, 6, 7, 8 or more) or more trays 111 above and/or below the inlet 112. The distillation column 110 further includes a first outlet 114 at its top end 113 and a second outlet 115 at its bottom end 116. In some embodiments, a reduction or increase in diameter is specific to the top end 113 and bottom end 116. In some embodiments, the assembly comprised of CMX 130, RMX 120, and distillation column 110 components are combined into a single assembly.

[0018] The RMX 120 and the CMX 130 comprise one or more heat exchangers, such as braised aluminum heat exchangers, and/or plate fin and tube heat exchangers, configured to transfer heat and achieve mass transfer of a working fluid.

[0019] The RMX 120 includes one or more heat and/or mass transfer stages 121. Each of the one or more heat and/or mass transfer stages 121 includes a heating medium inlet 122 and a heating medium outlet 123. The heating medium inlet 122 is configured to receive a heating medium 106. The heating medium outlet 123 is configured to expel the heating medium 106 after it has passed through the one or more heat and/or mass transfer stages 121. The one or more heat and/or mass transfer stages 121 receives one or more heating mediums 106, which heat the working fluid before expelling the now-cooled heating mediums 106 out of the heating medium outlet 123.

[0020] In some embodiments, the heating medium outlet 123 of a first stage of the one or more heat and/or mass transfer stages 121 is fluidly coupled to the heating medium inlet 122 of a second stage of the one or more heat and/or mass transfer stages 121. In such embodiments, the heating medium 106 passes through the one or more heat and/or mass transfer stages 121 in series. In some embodiments, each of the one or more heat and/or mass transfer stages 121 are individually plumbed to receive heating mediums 106 separately allowing different heating mediums 106 to be used at each of the one or more heat and/or mass transfer stage 121.

[0021] The RMX 120 is configured to heat the working fluid, such as one or more portions of the inlet feed 101, passing through the RMX 120 using one or more heating mediums 106. The RMX 120 is further configured to simultaneously transfer heat and mass from the working fluid thus reducing or eliminating stages of mass transfer above the RMX 120. In one or more embodiments, heat transfer only zones and/or mass transfer only zones may be located above, below, and/or between one or more of the heat and/or mass transfer stages 121 of the RMX 120. The RMX 120 may include a housing 124 that is coupled to the bottom end 116 of the distillation column 110. In some embodiments, the housing 124 is in the shape of a rectangular prism. The RMX 120 includes a product inlet 125 at its top end that is fluidly coupled to the second outlet 115 of the distillation column 110. The RMX 120 includes a product outlet 126 fluidly coupled to a product conduit 140. As such, the working fluid may leave the distillation column 110 through the second outlet 115 and enter the RMX 120 through the product inlet 125 as illustrated by reference arrow 118. The working fluid then may pass through, and be heated by, the one or more stages 121 of the RMX 120 using heat and/or mass transfer from the one or more heating mediums 106. Working fluid that flows through the RMX 120 may be vaporized and flow back into the distillation column 110 as illustrated by reference arrow 109. At least a portion of the heated working fluid leaves the RMX 120 through the product outlet 126 to the product conduit 140.

[0022] The RMX 120 further includes one or more heating medium inlets 127 and one or more heating medium outlets 128 coupled to one or more heating medium conduits 142. The one or more heating medium inlets 127 are plumbed to the heating medium inlets 122 of the one or more heat and/or mass transfer stages 121 of the RMX 120. The one or more heating medium outlets 128 are also plumbed to the heating medium outlets 123 of the one or more heat and/or mass transfer stages 121. Each of the one or more heat and/or mass transfer stages 121 may be plumbed separately to allow each of the one or more heat and/or mass transfer stage 121 to use a different heating medium 106. Each of the one or more heat and/or mass transfer stages 121 may be plumbed in series so one heating medium 106 is used for more than one of the heat and/or mass transfer stages 121. There may be one or more heating medium inlets 127 and one or more heating medium outlets 128 depending on the number of heating mediums 106 used and depending on the desired configuration of the one or more heat and/or mass transfer stages 121.

[0023] The heating medium 106 may include any number of streams so long as the stream is of a sufficient temperature to reboil (e.g. heat) the working fluid in the RMX 120 and transfer heat and mass in the RMX 120 to separate nitrogen and hydrocarbons from the working fluid. The heating medium 106 may include hydrocarbons (e.g. methane and/or ethane), mixed refrigerant, the inlet feed 101, natural gas, and/or any combination thereof. In one or more embodiments, the mixed refrigerant may be a mixture comprising nitrogen, methane, ethane, ethylene, propane, propylene, isobutene, butane, isopentane, and/or pentane. The mixed refrigerant may be selected to optimize desired vaporization characteristics of the mixture, minimize power consumption in a mixed refrigerant compressor (such as compression assembly 500 of FIG. 3), maximize production of a first and/or second product (such as nitrogen vapor phase 104 and/or nitrogen stripped phase 105), and/or improve purity of a first and/or second product (such as nitrogen vapor phase 104 and/or nitrogen stripped phase 105).

[0024] The CMX 130 includes one or more heat and/or mass transfer stages 131. Each of the heat and/or mass transfer stages 131 includes a cooling medium inlet 132 and a cooling medium outlet 133. The cooling medium inlet 132 is configured to receive a cooling medium 107. The cooling medium outlet 133 is configured to expel the cooling medium 107 after it has passed through the one or more heat and/or mass transfer stages 131. The one or more heat and/or mass transfer stages 131 receives one or more cooling mediums 107, which cool the working fluid before expelling the now-heated cooling mediums 107 out of the cooling medium outlet 133.

[0025] In some embodiments, the cooling medium outlet 133 of a first stage of the one or more heat and/or mass transfer stages 131 is fluidly coupled to the cooling medium inlet 132 of a second stage of the one or more heat and/or mass transfer stages 131. In such embodiments, the cooling medium 107 passes through the one or more heat and/or mass transfer stages 131 in series. In some embodiments, each of the one or more heat and/or mass transfer stages 131 are individually plumbed to receive cooling mediums 107 separately allowing different cooling mediums 107 to be used at each of the one or more heat and/or mass transfer stage 131.

[0026] The CMX 130 is configured to cool the working fluid, such as one or more portions of the inlet feed 101, passing through the CMX 130 using one or more cooling mediums 107. The CMX 130 is further configured to simultaneously transfer heat and mass from the working fluid thus reducing or eliminating stages of mass transfer below the CMX 130. In one or more embodiments, heat transfer only zones and/or mass transfer only zones may be located above, below, and/or between one or more of the heat and/or mass transfer stages 131 of the CMX 130. The CMX 130 may include a housing 134 that is coupled to the top end 113 of the distillation column 110. In some embodiments, the housing 134 is in the shape of a rectangular prism. The CMX 130 includes a product inlet 135 at its bottom end that is fluidly coupled to the first outlet 114 of the distillation column 110. The CMX 130 includes a product outlet 136 fluidly coupled to a second product conduit 141. As such, the working fluid may leave the distillation column 110 through the first outlet 114 and enter the CMX 130 through the product inlet 135 as illustrated by reference arrow 119. The working fluid then may pass through, and be cooled by, the one or more heat and/or mass transfer stages 131 of the CMX 130 using heat and/or mass transfer with the one or more cooling mediums 107. Working fluid that flows through the CMX 130 may be condensed and flow back into the distillation column 110 as illustrated by reference arrow 129. At least a portion of the cooled working fluid leaves the CMX 130 through the product outlet 136 to the second product conduit 141.

[0027] The CMX 130 further includes one or more cooling medium inlets 137 and one or more cooling medium outlets 138 coupled to one or more cooling medium conduits 144. The one or more cooling medium inlets 137 are plumbed to the cooling medium inlets 132 of the one or more heat and/or mass transfer stages 131 of the CMX 130. The one or more cooling medium outlets 138 are also plumbed to the cooling medium outlets 133 of the one or more heat and/or mass transfer stages 131. Each of the one or more heat and/or mass transfer stages 131 may be plumbed separately to allow each of the one or more heat and/or mass transfer stage 131 to use a different cooling medium 107. Each of the one or more heat and/or mass transfer stages 131 may be plumbed in series so one cooling medium 107 is used for more than one of the heat and/or mass transfer stages 131. There may be one or more cooling medium inlets 137 and one or more cooling medium outlets 138 depending on the number of cooling mediums 107 used and depending on the desired configuration of the one or more heat and/or mass transfer stages 131.

[0028] The cooling medium 107 may include any number of streams so long as the stream is of a sufficient temperature to cool the working fluid in the CMX 130 and to transfer heat and mass in the CMX 130 to separate nitrogen from the working fluid. The cooling medium 107 may include hydrocarbons (e.g. methane and/or ethane), mixed refrigerant, the cooled inlet feed 101, natural gas, and/or any combination thereof. In one or more embodiments, the mixed refrigerant may be a mixture comprising nitrogen, methane, ethane, ethylene, propane, propylene, isobutene, butane, isopentane, and/or pentane. The mixed refrigerant may be selected to optimize desired vaporization characteristics of the mixture, minimize power consumption in a mixed refrigerant compressor (such as compression assembly 500 of FIG. 3), maximize production of a first and/or second product (such as nitrogen vapor phase 104 and/or nitrogen stripped phase 105), and/or improve purity of a first and/or second product (such as nitrogen vapor phase 104 and/or nitrogen stripped phase 105).

[0029] According to one mode of operation, the inlet feed 101 is fed from the inlet feed source to the nitrogen separation column 100. The inlet feed 101 may include, at least, a mixture of hydrocarbons (e.g. methane and/or ethane) and nitrogen. In some embodiments, the inlet feed 101 is about 50 mole percent (mol %) to about 99.5 mol % hydrocarbons (e.g. methane and/or ethane) and about 0.5 mol % to about 40 mol % nitrogen. The inlet feed 101 may pass through a Joule-Thompson (JT) valve 143 or feed expansion device before entering the nitrogen separation column 100.

[0030] The inlet feed 101 enters the nitrogen separation column 100 at the inlet 112 of the distillation column 110. As the inlet feed 101 enters the distillation column 110 (e.g. the separation section 117), it may flash and may separate into vapor 102 and liquid 103. Vapor 102 coming from inlet feed 101 may be combined with vapor 108 vaporizing on the trays 111 within the distillation column 110, as well as vapor 109 coming from the RMX 120. Liquid 103 coming from inlet feed 101 may be combined with liquid 139 condensing on the trays 111 within the distillation column 110, as well as liquid 129 coming from the CMX 130. The vapors 102, 108, 109 rise through the trays 111 of the distillation column 110. The liquids 103, 129, 139 fall through the trays 111 of the distillation column 110. The inlet feed 101 stream can be in liquid, vapor, or two-phase in equilibrium.

[0031] As the liquids 103, 129, 139 fall through the trays 111 of the distillation column 110, it is stripped from its nitrogen, and leaves the distillation column 110 through the product inlet 125 to enter the RMX 120. The RMX 120 utilizes one or more heating mediums 106 to heat the liquids 103, 129, 139 through the one or more stages 121. As the liquids 103, 129, 139 are heated, a portion of liquids 103, 129, 139 are vaporized which rises back into the distillation column 110 as vapor 109. The remainder of liquids 103, 129, 139 that have not vaporized is the nitrogen stripped phase 105 that leaves the nitrogen separation column 100 through the product conduit 140 to be processed further. As such, the RMX 120 is used for both heat transfer and mass transfer of the working fluid.

[0032] As the vapors 102, 108, 109 rise through the trays 111 of the distillation column 110, they are rectified from their heavy components, leaves the distillation column 110 through the first outlet 114, and enters into the CMX 130. The CMX 130 utilizes the one or more cooling mediums 107 to cool the vapors 102, 108, 109 through the one or more stages 131. As the vapors 102, 108, 109 are cooled, a portion of the vapors 102, 108, 109 become liquid and fall back down into the distillation column 110 as reflux, thereby becoming part of the liquid 129. The remainder of the vapors 102, 108, 109 that have not become part of the liquid 129 is the nitrogen vapor phase 104 that leaves the nitrogen separation column 100 through the second product conduit 141 to be processed further. As such, the CMX 130 is used for both heat transfer and mass transfer of the working fluid.

[0033] Further, the liquid 103 flowing from the inlet 112, the liquid 129 falling from the CMX 130, and the liquid 139 falling from the trays 111 interact with the rising vapors 102, 108, 109 on the trays 111, and otherwise in the distillation column 110, to pre-cool and provide mass transfer of the rising vapors 102, 108, 109 and convert a portion of the rising vapors 102, 108, 109 into the liquid 139. Similarly, the vapor 102 flowing from the inlet 112, the vapor 108 rising from the trays 111, and the vapor 109 rising from the RMX 120 interact with the falling liquids 103, 129, 139 on the trays 111, and otherwise in the distillation column 110, to preheat the liquids 103, 129, 139 and may convert a portion of the falling liquids 103, 129, 139 into the vapor 108.

[0034] In some embodiments, where the nitrogen vapor phase 104 is used as a low BTU fuel, the nitrogen vapor phase 104 may comprise about 0.1 mol % to about 50 mol % nitrogen and/or about 50 mol % to about 99.99 mol % hydrocarbons (e.g. methane and/or ethane). Where the nitrogen vapor phase 104 is to be used as a low BTU fuel, the nitrogen stripped phase 105 may comprise about 0 mol % to about 5 mol % nitrogen and/or about 90 mol % to about 99.99 mol % hydrocarbons (e.g. methane and/or ethane).

[0035] In some embodiments, the nitrogen vapor phase 104 comprises about 50 mol % to about 99.99999 mol % nitrogen. In some embodiments, the nitrogen vapor phase 104 comprises about 90 mol % to about 99.99999 mol % nitrogen. In such embodiments, the remainder portion of the nitrogen vapor phase 104 may comprise about 90 mol % or greater hydrocarbons (e.g. methane and/or ethane). In some embodiments, the nitrogen stripped phase 105 may comprise about 0 mol % to about 3 mol % nitrogen. In some embodiments, the nitrogen stripped phase 105 is liquefied natural gas (LNG).

[0036] FIG. 2 illustrates an exemplary nitrogen separation column 200. Unlike the nitrogen separation column 100, the nitrogen separation column 200 does not include a CMX (such as CMX 130). Rather, the nitrogen separation column 200 only includes an RMX 220 (such as the RMX 120) located at the bottom of, and coupled to the bottom of, the distillation column 210. For brevity, all components of the nitrogen separation column 200 that are similar to components of the nitrogen separation column 100 have been given reference numbers with the same last two digits, and a full description of such similar components may not be repeated herein. Rather than a CMX being located at and coupled to the top of the distillation column 210, a dome may be located at the top and coupled to the top of the distillation column.

[0037] According to one mode of operation, the inlet feed 101 is fed to the nitrogen separation column 200 at a top feed point. The inlet feed 101 enters the nitrogen separation column 200 at the inlet 212 of the distillation column 210. As the inlet feed 101 enters the distillation column 210 (e.g. the separation section 217), it may flash and may separate into vapor 102 and liquid 103. Vapor 102 coming from the inlet feed 101 may be combined with the vapor 108 vaporizing on the trays 211 within the distillation column 210, as well as vapor 109 coming from the RMX 220. The liquid 103 coming from the inlet feed 101 may be combined with liquid 139 condensing on the trays 211 within the distillation column 210.

[0038] As the liquids 103 and 139 fall through the trays 211 of the distillation column 210 it is stripped from its nitrogen, and leaves the distillation column 210 through the second inlet 216 to enter the RMX 220. The RMX 220 utilizes the one or more heating mediums 106 to heat the liquids 103 and 139 through the one or more stages 221. As liquids 103, 139 are heated, a portion of liquids 103, 139 are vaporized which rises back into the distillation column 210 as vapor 109. The remainder of liquids 103, 139 that have not vaporized is the nitrogen stripped phase 105 that leaves the nitrogen separation column 200 through the product conduit 240 to be processed further. As such, the RMX 220 is used for both heat transfer and mass transfer.

[0039] As the vapors 102, 108, 109 rise through the trays 211 of the distillation column 210, they are rectified by the liquids 103, 139 and leave the distillation column 210 though the first outlet 214 at the top end 213, thereby leaving the nitrogen separation column 200 through the second product conduit 241 as the nitrogen vapor phase 104 to be processed further.

[0040] Further, the liquid 103 flowing from the inlet 212 and the liquid 139 falling from the trays 211 interact with the rising vapors 102, 108, 109 on the trays 211, and otherwise in the distillation column 210, to precool and provide mass transfer of the rising vapors 102, 108, 109 and convert a portion of the rising vapors 102, 108, 109 into liquid 139. Similarly, the vapor 109 rising from the RMX 220 interacts with the falling liquids 103, 139 on the trays 211, and otherwise in the distillation column 210, to preheat the falling liquids 103, 139 and may convert a portion of the falling liquids 103, 139 into vapor 108.

[0041] In some embodiments, nitrogen separation column 200 may produce a nitrogen vapor phase 104 used as a low BTU fuel similar to that discussed above with reference to FIG. 1. In some embodiments, the nitrogen vapor phase 104 comprises about 30 mol % to about 90 mol % hydrocarbons (e.g. methane and/or ethane) and about 0.1 mol % to 50 mol % nitrogen. In such embodiments, the nitrogen stripped phase 105 may comprise about 0 mol % to about 5 mol % nitrogen.

[0042] FIG. 3 illustrates a nitrogen separation column system 1000 utilizing inlet feed 101 as the heating medium and mixed refrigerant as the cooling medium 107. The nitrogen separation column 300 is an exemplary nitrogen separation column and the nitrogen separation column 100 as described with respect to FIG. 1 may be used in its place.

[0043] For brevity, all similar components to the nitrogen separation column 300 have been given reference numbers with the same last two digits, and a full description of such similar components may not be repeated herein.

[0044] The nitrogen separation column system 1000 includes the nitrogen separation column 300, a main heat exchanger 400, a compression assembly 500, a first JT valve 610 or a feed expansion device, a second JT valve 620 or a feed expansion device, and a flow control valve 630.

[0045] The cooling medium 107, i.e. mixed refrigerant, is cycled through the main heat exchanger 400, the compression assembly 500, the second JT or feed expansion device, valve 620 or feed expansion device, and the CMX 330.

[0046] The inlet feed 101 is being used as both the working fluid for the nitrogen separation column system 1000 and the heating medium that is cycled through the main heat exchanger 400, the first JT valve 610 or a feed expansion device, the nitrogen separation column 300, the RMX 320, and the flow/temperature control valve 630.

[0047] According to one mode of operation, the inlet feed 101 enters the main heat exchanger 400 and is cooled from location 1 to location 2. For example, the inlet feed 101 may be cooled from 60 degrees Fahrenheit (F) to 120 degrees F. from location 1 to location 2. The inlet feed 101 then enters the flow/temperature control valve 630 and is split between locations 3 and 4. The amount of inlet feed 101 that is portioned between locations 3 and 4 depends on the heat transfer needed in the RMX 320. At location 4, the inlet feed 101 enters into the RMX 320 and is used as the heating medium to heat the working fluid in the RMX 320 of the nitrogen separation column 300. The inlet feed 101 used as the heating medium is cooled as it goes from location 4 to location 5 due to heat transfer with the working fluid in the RMX 320. For example, the inlet feed 101 used as the heating medium may be cooled from about 120 degrees F. to 158 degrees F. from location 4 to location 5. The portion of inlet feed 101 at location 3 is then combined with the inlet feed 101 at location 5.

[0048] At location 6, the inlet feed 101 reenters the main heat exchanger 400 and is cooled from location 6 to location 7. For example, the inlet feed 101 may be cooled from about 150 degrees F. to 190 degrees F. from location 6 to location 7. The inlet feed 101 then passes through the first JT valve 610 or a feed expansion device and decreases in temperature and pressure (e.g. expands) to a pressure and temperature optimized for nitrogen separation in the nitrogen separation column 300. For example, the pressure of the inlet feed 101 may be decreased from about 657 pounds per square inch gauge (psig) to about 310 psig from location 7 to location 8. Similarly, the temperature of the inlet feed 101 may be decreased from about 190 degrees F. to about 190.1 degrees F. from location 7 to location 8. At location 8, the inlet feed 101 becomes the working fluid in the nitrogen separation column 300 and proceeds as described above with reference to FIGS. 1 and 2.

[0049] Beginning at the compression assembly 500, the cooling medium 107 is compressed and the pressure is increased. For example, the compression assembly 500 may increase the pressure of the cooling medium 107 from about 103 psig to about 650 psig. At location 15, the cooling medium 107 enters the main heat exchanger 400 and is cooled. For example, the cooling medium 107 may be cooled from 105 degrees F. to about 263 degrees F. from location 15 to location 16. At location 16, the cooled cooling medium 107 enters the second JT valve 620 to reduce pressure and temperature of the cooling medium 107. For example, the pressure of the cooling medium 107 may be decreased from about 620 psig to about 117 psig from location 16 to location 17. Similarly, the temperature of the cooling medium 107 may be decreased from about 263 degrees F. to about 265 degrees F. from location 16 to location 17. At location 17, the cooling medium 107 enters the CMX 330. From location 17 to location 13, the cooling medium 107 is used as the cooling medium 107 to transfer heat and cause mass transfer from the working fluid in the nitrogen separation column 300. Also from location 17 to location 13, the cooling medium 107 is heated due to the heat transfer occurring in the CMX 330. For example, the cooling medium 107 may be heated from about 265 degrees F. to about 225 degrees F. from location 17 to location 13. At location 13, the cooling medium 107 reenters the main heat exchanger 400 and is reheated. For example, the cooling medium 107 may be heated from about 225 degrees F. to about 95 degrees F. from location 13 to location 14. At location 14, the cooling medium 107 enters the compression assembly 500 to be recompressed and recycled through the nitrogen separation column system 1000.

[0050] FIG. 4 illustrates the nitrogen separation column system 1000 of FIG. 3 but with a nitrogen separation column 700 including a housing 710, a CMX 730 located at the top of the housing 710, an RMX 720 located at the bottom of the housing 710, and a separation section 717 located there between. Unlike the embodiments of FIGS. 1-3, the separation section 717 contains no packed beds or trays located within the housing 710. In such embodiments, packed beds or trays may not be required between the RMX 720 and the CMX 730 because the heat transfer and/or mass transfer occurring within and between the RMX 720 and the CMX 730 is sufficient to separate nitrogen from an inlet feed 101.

[0051] For brevity, all similar components to the nitrogen separation column 300 have been given reference numbers with the same last two digits, and a full description of such similar components may not be repeated herein.

[0052] According to one mode of operation, the inlet feed 101 is fed from the inlet feed source to the nitrogen separation column 700 at the inlet 712 and into the separation section 717, it may flash and may separate into vapor 102 and liquid 103. Vapor coming from the inlet feed 101 may be combined with vapor 109 coming from the RMX 720. The liquid 103 coming from the inlet feed 101 may be combined with liquid 129 coming from the CMX 730. The vapors 102, 109 flow through the separation section 717 towards the CMX 730. The liquids 103, 129 flow through the separation section 717 towards the RMX 720.

[0053] As the liquids 103, 129 flow to the RMX 720, the liquids 103, 129 leave the separation section 217 and enter the RMX 720. As the liquids 103, 129 are heated by the RMX 720, a portion of the liquids 103, 129 are vaporized and flow back into the separation section 717 as vapor 109. The remainder of liquids 103, 129 is the nitrogen stripped phase 105 that leaves the nitrogen separation column 100. As such, the RMX 720 is used for both heat transfer and mass transfer of the working fluid.

[0054] As the vapors 102, 109 rise towards the CMX 730, they leave the separation section 717 and enter the CMX 730. As the vapors 102, 109 are cooled by the CMX 730, a portion of the vapors 102, 109 are condensed and flow back into the separation section as reflux, thereby becoming part of the liquid 129. The remainder of vapors 102, 109 is the nitrogen vapor phase 104 that leaves the nitrogen separation column 700.

[0055] FIG. 5 illustrates a method 2000 for separating nitrogen from hydrocarbon streams.

[0056] At step 2001, an inlet feed (such as inlet feed 101) is fed to a nitrogen separation column (such as nitrogen separation columns 100, 200, 300). The nitrogen separation column receives the inlet feed at an inlet (such as inlets 112, 212) of a housing (such as housing 710) and/or a distillation column (such as distillation columns 110, 210) and enters the housing and/or distillation column at a separation section (such as separation sections 117, 217, 717).

[0057] In some embodiments, the inlet feed 101 may include about 0.50 mol % to about 99.99 mol % hydrocarbons (e.g. methane and/or ethane) and about 0.1 mol % to about 50 mol % nitrogen

[0058] At step 2002, the inlet feed is separated into a vapor (such as vapor 102) and a liquid (such as liquid 103) in the distillation column. In some embodiments, the inlet feed is flashed in the distillation column to induce separation.

[0059] At step 2003, a cooling medium (such as cooling medium 107) is fed to a CMX (such as CMXs 130, 230, 330, 730) located on top of the distillation column. In some embodiments, the cooling medium includes hydrocarbons (e.g. methane and/or ethane), mixed refrigerant, cooled inlet feed, natural gas, and/or any combination thereof so long as the stream is of a sufficient temperature to cool the working fluid of the CMX to a desired temperature to separate nitrogen from the working fluid.

[0060] At step 2004, at least a portion of the vapor flows up through the distillation column and into the CMX. The CMX utilizes heat transfer from the cooling medium to cool at least a portion of the vapor. As the portion of the vapor is cooled, nitrogen is separated from the inlet feed and is routed out of the nitrogen separation column. Further, as the portion of the vapor is cooled, some of the vapor becomes liquid (such as liquid 129) and can be combined with the liquid from the inlet feed.

[0061] In some embodiments, a portion of the vapor that does not flow into the CMX interacts with the liquid on trays and/or packing (such as trays and/or packing 111, 211), or otherwise in the distillation column, and is condensed (such as liquid 139) before it reaches the CMX, thus becoming part of the falling liquid now including the condensed vapor from the CMX and the liquid from the inlet feed.

[0062] At step 2005, a heating medium (such as heating medium 106) is fed to an RMX (such as RMXs 120, 220, 320, 720) located at the bottom of the distillation column. In some embodiments, the heating medium includes hydrocarbons (e.g. methane and/or ethane), mixed refrigerant, inlet feed, natural gas, and/or any combination thereof so long as the stream is of a sufficient temperature to reboil (e.g. heat) the working fluid of the RMX to a desired temperature to separate nitrogen from the working fluid.

[0063] At step 2006, at least a portion of the liquid including the liquid from the inlet feed, from the CMX, and from the packed trays, flows down through the distillation column and into the RMX. The RMX utilizes heat transfer from the heating medium to heat at least a portion of the liquid. As the portion of the liquid is heated, a nitrogen stripped phase (such as nitrogen stripped phase 105) is separated from its nitrogen and is routed out of the nitrogen separation column.

[0064] As the portion of the liquid is heated, another portion is vaporized from heat transfer in the RMX (such as vapor 109) and reenters the distillation column to join the vapor from the inlet feed.

[0065] In some embodiments, a portion of the liquid that does not flow into the RMX interacts with the vapor in the distillation column on the trays and/or packing, or otherwise in the distillation column, and is vaporized (such as vapor 108) thus becoming part of the rising vapor now including the vaporized liquid from the RMX and the vapor from the inlet feed.

[0066] Any one or more components of the nitrogen separation columns 100, 200, 300, 700 and nitrogen separation column system 1000 may be integrally formed together, directly coupled together, and/or indirectly coupled together and are not limited to the specific arrangement of components illustrated in FIGS. 1-4. Any one or more of the embodiments of the nitrogen separation column 100, 200, 300, 700 and nitrogen separation column system 1000 may be combined, in whole or in part, with any one or more of the embodiments of the nitrogen separation column 100, 200, 300, 700 and nitrogen separation column system 1000.

[0067] It will be appreciated by those skilled in the art that the preceding embodiments are exemplary and not limiting. It is intended that all modifications, permutations, enhancements, equivalents, and improvements thereto that are apparent to those skilled in the art upon a reading of the specification and a study of the drawings are included within the scope of the disclosure. It is therefore intended that the following appended claims may include all such modifications, permutations, enhancements, equivalents, and improvements. The disclosure also contemplates that one or more aspects of the embodiments described herein may be substituted in for one or more of the other aspects described.

[0068] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.