EP4621333A2

EP4621333A2 - Apparatus and process for providing nitrogen and oxygen

Info

Publication number: EP4621333A2
Application number: EP25164112.2A
Authority: EP
Inventors: Christopher Robert Bongo
Original assignee: Air Products and Chemicals Inc
Current assignee: Air Products and Chemicals Inc
Priority date: 2024-03-18
Filing date: 2025-03-17
Publication date: 2025-09-24
Also published as: US20250290692A1; EP4621333A3

Abstract

An apparatus and process for providing nitrogen and oxygen can include a multicolumn tower that includes a lower pressure column (LP) positioned in alignment with an intermediate pressure (MP) column. At least one of these columns and at least one higher pressure (HP) column can receive air from a feed intake system. Embodiments can be adapted so that the diameter of the LP and MP columns are similar, if not the same so that the columns can be aligned with each other in the tower. Embodiments can be adapted to allow for high purity nitrogen recovery from at least one HP column while also obtaining at least one oxygen stream from the LP column with equipment that has an overall lower height, or length, that can be easier to fabricate and install.

Description

The present innovation relates to processes and apparatuses for recovery of nitrogen and oxygen from a feed (e.g., a feed of air, etc.).
Air separation processing has been utilized to separate air into different constituent flows of fluid (e.g., nitrogen, oxygen, etc.). Examples of systems that were developed in conjunction with air separation processing include U.S. Pat. Nos. 4,022,030 , 4,254,629 , 4,822,395 , 5,305,611 , and 5,682,764 , International Patent Publication Nos. WO 2014/099848 , WO 2015/003808 , WO 2020/169257 , WO 2020/244801 , and WO 2021/078405 , European Patent Application Publication Nos. EP 2 824 407 A1 and EP 2 489 968 A1 , and U.S. Pat. App. Pub. Nos. 2019/0331417 , 2019/0331418 , and 2019/0331419 .
Some air separation processes may utilize a tower having a low pressure column and a high pressure column. Conventionally, such columns can be integrated into a dual column tower arrangement because vapor flow rates between these columns can be reasonably well matched and standard sizing calculations can result in those columns having similar diameters for construction in an aligned tower. When making lower purity oxygen products, there can be an intermediate pressure column that may be utilized to reduce power requirements. However, such an arrangement involves a very large separate intermediate pressure column, which greatly increases the footprint, fabrication and installation cost associated with that arrangement. The larger sized equipment can also involve larger delays in installation due to increased work that can be involved and the longer lead times that can be needed for the larger equipment.
Embodiments of a process for providing of nitrogen and oxygen can include an arrangement of columns that can include at least one first column, a second column, and a third column. Each first column can be a high pressure (HP) column that operates at a pressure range that is higher than the pressure range of operation of the second column and also the pressure range of operation for the third column. The second column can be an intermediate pressure (MP) column that operates at a pressure range of operation that is less than the pressure of the first column and also greater than the pressure range of operation for the third column. The third column can be a low pressure (LP) column that operates at a pressure range that is less than the operational pressure range of the second column and also less than the operational pressure range of the first column.
The MP column and the LP column can be aligned with each other and stacked in a linearly extending tower having similar diameters in some embodiments. Each HP column can be arranged at a spaced apart location that is distanced from the aligned MP and LP columns. Some embodiments can utilize a single HP column. Other embodiments may utilize multiple HP columns. An HP column (e.g., the single HP column or one of the multiple HP columns) can be configured to output a high purity nitrogen stream as a product stream in some configurations. Some embodiments can be configured so that at least one oxygen product stream and at least one nitrogen stream (e.g., a nitrogen product stream output from an HP column) can be produced as well as one or more waste streams or refrigeration streams.
For instance, the LP column can output at least one oxygen product flow and the MP column may also output at least one nitrogen flow that can be passed to an expander for providing additional refrigerant for cooling a feed of air. The expander can be an expander or an expanding component of a compander. The oxygen product flow can be output from the LP column. The MP column, LP column and/or HP column can also output one or more waste flows that can be utilized for refrigeration in a heat exchanger used for pre-cooling a feed of air prior to venting or other use of the waste flows.
In some embodiments, the diameter of the MP column and the LP column can be the same (e.g., exactly the same) or substantially the same (e.g., within +/- 10% of the same value). This size similarity can help make fabrication and installation of a stacked column that includes the aligned MP and LP columns with an internal reboiler-condenser positioned between the columns a practical option that can be provided to permit easier installation of equipment that can have a smaller overall footprint compared to designs that may have a stacked and aligned low pressure and high pressure columns. The inventor has found that this type of feature can permit some embodiments to provide substantially greater design flexibility in the design, installation and operation of an air separation system or air separation apparatus.
For example, in some embodiments, the MP and LP columns can be aligned to extend vertically in a stacked arrangement and have a reboiler-condenser positioned between the MP and LP columns in this arrangement. In some embodiments, the LP and MP columns can be aligned and positioned within the same vessel shell with an internal reboiler-condenser positioned between the LP and MP columns within the vessel shell, for example. The inventor has also found that utilization and positioning of an expander for a nitrogen stream output from the MP column can facilitate fabrication of the multicolumn assembly of the tower having the MP column and the LP column so that the diameters of these columns can be the same or substantially the same to provide an improved fabrication of towers for air separation that can also provide a smaller overall footprint for the apparatus operating the air separation process.
The inventor has also found that embodiments can be configured for use with lower feed compression requirements (e.g., smaller compression systems, or compressors that may use less stages of compression as compared to conventional systems), which can provide reduced power requirements for operation of an air separation process and also provide more design flexibility, a lower footprint, and reduced operational costs and capital costs. Embodiments can also provide a higher pressure nitrogen product stream that can avoid a need of further compression of the product stream or reducing the compression requirement for such a stream depending on the pressure requirements for the nitrogen product stream. The reduced power consumption can also provide a beneficial ecological impact by reducing carbon emissions associated with operation of the air separation process.
The inventor has found that high purity nitrogen can be provided efficiently via an HP column while oxygen product is also provided, which can reduce the warm end compression power and/or stages on a nitrogen product compressor (if needed). The inventor has surprisingly found that the power penalty for making high purity nitrogen from the HP column instead of the MP column is sufficiently low that the benefit of reducing product compression more than justifies doing so. This can be particularly beneficial for embodiments in which the nitrogen product flow rate to oxygen product flow rate ratio is less than 0.5 or in a range of 0.2 to greater than 0.005.
The air that may be used in embodiments of the air separation process can include ambient air. For example, the air that is fed for air separation can also include a fresh feed air.
In a first aspect a process for providing nitrogen and oxygen can include splitting a feed of air for feeding some of the air to a first column and some of the air to a second column. The first column can operate at a first pressure range and the second column can operate at a second pressure range wherein first pressure range is a higher pressure range than the second pressure range.
The process of the first aspect can also include feeding a stream of crude oxygen to a third column. The crude oxygen can be comprised of at least a portion of a crude oxygen stream output from the first column and/or at least a portion of a crude oxygen stream output from the second column. The third column can operate at a third pressure range that is a lower pressure range than the second pressure range.
The process of the first aspect can also include outputting a nitrogen-enriched vapor stream from the second column and feeding the nitrogen-enriched vapor stream output from the second column to an expander to be expanded therein, feeding the expanded nitrogen-enriched vapor stream to a heat exchanger as a refrigerant for pre-cooling the air being fed to the first column and the second column, and outputting a nitrogen-rich stream from the first column or a fourth column that is fluidly connected to the first column and operates at a fourth pressure range that is greater than the second pressure range, and outputting an oxygen product stream from the third column.
The process of the first aspect can also include other features as well as other steps. Also, embodiments of an apparatus can be provided to implement an embodiment of the process. In some embodiments, the process can also result in outputting of one or more nitrogen-enriched stream and/or nitrogen-rich streams as well as one or more oxygen-enriched streams. In some embodiments, at least some of these streams may be waste streams.
In a second aspect, the nitrogen-rich stream can be output from the first column and can comprised between 98.5 mole percent (mol%) nitrogen and 100 mol% nitrogen (i.e., from 98.5 mol% nitrogen to 100 mol% nitrogen). In other embodiments, the nitrogen-rich stream may have another composition of nitrogen (e.g., at least or over 95 mol% nitrogen, between 95 mol% nitrogen and 100 mol% nitrogen (i.e., from 95 mol% to 100 mol%), etc.).
In a third aspect, the nitrogen-rich stream can be output from the fourth column. The fourth column can operate at a high pressure range (e.g., a pressure range similar to the first pressure range). In such embodiments, the process can also include other steps.
For example, the process can also include the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column and feeding a stream of crude oxygen to the reboiler-condenser of the fourth column wherein the crude oxygen fed to the fourth column is comprised of a portion of the crude oxygen stream output from the first column and/or a portion of the crude oxygen stream output from the second column.
As another example, the process can also include feeding a stream comprising vapor output from a reboiler-condenser of the fourth column to an intermediate section of the third column and/or feeding a liquid stream output from a bottom portion of the fourth column to the first column and/or the third column as a reflux stream.
In a fourth aspect, the process can include the nitrogen-rich stream being output from the fourth column and the process also including the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column and feeding a portion of the oxygen product stream output from the third column to the reboiler-condenser of the fourth column. In some embodiments, the portion of the oxygen product stream output from the third column to the reboiler-condenser of the fourth column can be considered a first portion of the oxygen product stream and the remaining portion can be output as a product stream and be considered a second portion of the oxygen product stream. This second portion of the oxygen product stream can be produced as a product stream or can be split into one or more other portions, at least one of which can be a product stream.
In a fifth aspect, the process can be performed with the first, second, and third pressure ranges being pre-selected pressure ranges. For instance, the first pressure range can be between 0.42 MPa and 0.7 MPa (i.e., from 0.42 MPa to 0.7 MPa), the second pressure range can be between 0.22 MPa and 0.45 MPa (i.e., from 0.22 MPa to 0.45 MPa), and the third pressure range can be between 0.10 MPa and 0.18 MPa (i.e., from 0.1 MPa to 0.18 MPa). In other embodiments, the first, second, and third pressure ranges can have other numerical range values for an operational pressure range.
In a sixth aspect, the process can also include passing at least a portion of a nitrogen-enriched vapor output from the first column to a first reboiler-condenser to condense the nitrogen-enriched vapor. The first reboiler-condenser can be positioned between the second column and the third column within a vessel shell so that liquid at a bottom portion of the third column is vaporizable via the first reboiler-condenser. Vaporization of this liquid can be provided via heat of the nitrogen-enriched vapor output from the first column, which can facilitate condensation of this stream.
In some embodiments, the process can also include passing a first portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser to the first column as a reflux stream for the first column and splitting a second portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser from the first portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser. This split second portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser can be a liquid nitrogen (LIN) product stream.
In a seventh aspect, the process can be implemented so that the outputting of the oxygen product stream from the third column comprises outputting a product stream comprising oxygen from a bottom portion of the third column. The oxygen product stream can comprise at least 90 mole percent (mol%) oxygen (e.g., be between 90 mol% and 100 mol% oxygen, i.e., from 90 mol% to 100 mol% oxygen).
In some embodiments, the process can also include passing at least a portion of the oxygen product stream through a heat exchanger to vaporize the portion of the oxygen product stream passed through the heat exchanger. The oxygen product stream that is vaporized can also, optionally, undergo compression to a pre-selected product pressure that is within a pre-selected product pressure range.
In an eighth aspect, the process can be implemented so that the nitrogen-rich stream is output from the fourth column and the process also includes the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream is fed to a first reboiler-condenser to condense the first portion of the nitrogen-enriched vapor and a second portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column. The first reboiler-condenser can be positioned between the second column and the third column within a vessel shell so that liquid at a bottom portion of the third column is vaporizable via the first reboiler-condenser for condensing the first portion of the nitrogen-enriched vapor. The first reboiler-condenser can output the condensed first portion of the nitrogen-enriched vapor for feeding to the first column as a reflux stream.
In a ninth aspect, the feeding of the stream of crude oxygen to the third column can include feeding at least a portion of the crude oxygen stream output from the first column and/or at least a portion of the crude oxygen stream output from the second column to a second reboiler-condenser for vaporization to form at least one at least partially vaporized crude oxygen stream for feeding to the third column as the stream of crude oxygen. For example, a crude oxygen stream output from the first column can be fed to the second reboiler-condenser for being vaporized and subsequently fed to the third column. As another example, a crude oxygen stream output from the second column can be fed to the second reboiler-condenser for being vaporized and subsequently fed to the third column. As yet another example, a crude oxygen stream output from the first column can be fed to the second reboiler-condenser for being vaporized and subsequently fed to the third column and a crude oxygen stream output from the second column can be fed to the second reboiler-condenser for being vaporized and subsequently fed to the third column. As yet another example, a crude oxygen stream output from the first column can be merged with a crude oxygen stream output from the second column and that merged stream of crude oxygen can be fed to the second reboiler-condenser for being vaporized and subsequently fed to the third column.
In some embodiments, a portion of crude oxygen output from the first column and/or a portion of crude oxygen output from the second column can be split upstream of the second reboiler-condenser for being fed to the third column as a third column feed stream or reflux stream. For example, at a portion of the crude oxygen output from the first column can be split away from a remaining portion of the crude oxygen and fed to the third column as a reflux stream. As another example, at a portion of the crude oxygen output from the second column can be split away from a remaining portion of the crude oxygen and fed to the third column as a reflux stream.
In a tenth aspect, the process of the first aspect can include one or more features of the second aspect, third aspect, fourth aspect, fifth aspect, sixth aspect, seventh aspect, eighth aspect, and/or ninth aspect to form other embodiments. Examples of such combinations of features can be appreciated from the exemplary embodiments of the process discussed herein, for example. It should therefore be appreciated that embodiments of the process can also include other features, process steps, and/or other combinations of features and process steps.
In an eleventh aspect, an apparatus for providing nitrogen and oxygen is provided. Embodiments of the apparatus can be configured to implement an embodiment of the process for providing nitrogen and oxygen.
In some embodiments, the apparatus can include a first column configured to operate at a first pressure range wherein the first column is positioned to receive a first column feed of air output from a compression system. The apparatus can also include a second column configured to operate at a second pressure range wherein the second pressure range is a lower pressure range than the first pressure range and the second column is positioned to receive a second column feed of air output from the compression system. The second column can be configured to output a stream of nitrogen-enriched vapor. A third column can be positioned to receive at least one stream of crude oxygen via at least one of: a portion of a stream of crude oxygen output from a bottom portion of the first column and/or a portion of a stream of crude oxygen output from a bottom portion of the second column and output an oxygen product stream. An expander can be positioned to receive the nitrogen-enriched vapor output from the second column to expand the nitrogen-enriched vapor and feed the expanded nitrogen-enriched vapor to a heat exchanger as a refrigerant. The heat exchanger can be positioned to pre-cool the air upstream of the first column and the second column.
In some embodiments, the expander can be an expanding unit of a compander that is coupled to a compressor unit. The compressor unit of the compander can be a component of the compression system or a booster compressor that may be positioned to help compress at least a portion of the feed air before the air is fed to the first column, second column, or third column. In other embodiments, the expander can be a different type of expander. In some configurations, the expander can be connected to a generator so that the expansion of the nitrogen-enriched vapor can also drive generation of electricity. That electricity can be utilized to power part of the apparatus or used in other ways.
As may be appreciated from the above, the first, second, and third pressure ranges can be pre-selected pressure ranges at which the first, second and third columns can be operated. In some embodiments, the first pressure range can be between 0.42 MPa and 0.7 MPa, the second pressure range can be between 0.22 MPa and 0.45 MPa, and the third pressure range can be between 0.10 MPa and 0.18 MPa. Other embodiments may utilize other pressure ranges.
In a twelfth aspect, the second column and the third column can be vertically aligned, have a substantially similar diameter, and be within a vessel shell. In some embodiments, a first reboiler-condenser can be positioned within the vessel shell between the second column and the third column. The first reboiler-condenser can be configured to receive a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor to the first column as a stream of reflux and also boil liquid from a bottom portion of the third column.
In a thirteenth aspect, the first column can be configured to output a nitrogen-rich stream as a product stream and/or a liquid nitrogen product portion of the stream of reflux is splittable from the stream of reflux to form a liquid nitrogen product stream.
In a fourteenth aspect, the apparatus can include a first reboiler-condenser positioned within a vessel shell between the second column and the third column. The first reboiler-condenser can be configured to receive a first portion of a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor to the first column as a stream of reflux and also boil liquid from a bottom portion of the third column. A fourth column can be positioned to receive a second portion of the nitrogen-enriched vapor output from the first column. The fourth column can be configured to output a nitrogen-rich stream as a product stream.
In some embodiments, the reboiler-condenser of the fourth column can be configured to output a liquid nitrogen reflux stream. A portion of the liquid nitrogen reflux stream can be splittable from the liquid nitrogen reflux stream outputtable from the reboiler-condenser of the fourth column to form a liquid nitrogen product stream.
In some embodiments, the fourth column can also optionally output at least one stream for feeding to the third column as a reflux stream or other type of third column feed stream. For example, the fourth column can output a third column feed stream for a bottom region of the fourth column for providing a liquid containing stream or a liquid stream as a reflux to the third column.
In a fifteenth aspect, the apparatus can include the heat exchanger. The heat exchanger can be positioned to receive the nitrogen-enriched vapor output from the second column to warm the nitrogen-enriched vapor via cooling of the air fed to the heat exchanger and feed the warmed nitrogen-enriched vapor to the expander to expand the nitrogen-enriched vapor. The heat exchanger can also be configured and positioned to receive the expanded nitrogen-enriched vapor outputtable from the expander to pre-cool the air.
In a sixteenth aspect, the apparatus can include a first reboiler-condenser positioned within a vessel shell between the second column and the third column. The first reboiler-condenser can be configured to receive a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor for feeding to the first column as a stream of reflux. A second reboiler-condenser can be positioned to receive at least one of the stream of crude oxygen output from the bottom portion of the first column and/or the stream of crude oxygen output from the bottom portion of the second column for vaporization to form at least one at least partially vaporized crude oxygen stream for feeding to the third column. The third column can be fluidly connected to the second reboiler-condenser to receive the at least one at least partially vaporized crude oxygen stream as the at least one stream of crude oxygen received via the portion of the stream of crude oxygen output from the bottom portion of the first column and/or the portion of the stream of crude oxygen output from the bottom portion of the second column.
In a seventeenth aspect, the apparatus of the eleventh aspect can include one or more features of the twelfth aspect, thirteen aspect, fourteenth aspect, fifteenth aspect, and/or sixteenth aspect. It should therefore be appreciated that other embodiments can utilize other features and combinations of features. Examples of such additional features can include features of the exemplary embodiments discussed herein.
It should be appreciated that embodiments of the process and apparatus can utilize various conduit arrangements and process control elements. The embodiments may utilize sensors (e.g., pressure sensors, temperature sensors, flow rate sensors, concentration sensors, etc.), controllers, valves, piping, and other process control elements. Some embodiments can utilize an automated process control system and/or a distributed control system (DCS), for example.
Various different conduit arrangements and process control systems can be utilized to meet a particular set of design criteria.
Other details, objects, and advantages of our apparatus for providing high purity nitrogen, process for providing high purity nitrogen, and methods of making and using the same will become apparent as the following description of certain exemplary embodiments thereof proceeds.
Exemplary embodiments of our apparatus for providing high purity nitrogen, process for providing high purity nitrogen, and methods of making and using the same are shown in the drawings included herewith. It should be understood that like reference characters used in the drawings may identify like components.

Figure 1 is a block diagram of a first exemplary embodiment of an apparatus for providing high purity nitrogen. An exemplary embodiment of a process for providing high purity nitrogen can also be appreciated from Figure 1.
Figure 2 is a block diagram of a second exemplary embodiment of the apparatus for providing high purity nitrogen. An exemplary embodiment of a process for providing high purity nitrogen can also be appreciated from Figure 2.
Figure 3 is a flow chart illustrating an exemplary embodiment of a process for providing high purity nitrogen. The first and second exemplary embodiments of the apparatus for providing high purity nitrogen can implement this first exemplary embodiment of the process.

Referring to Figures 1-3, an apparatus 1 for providing high purity nitrogen can include an air separation unit (ASU). The ASU can be configured to provide at least one product stream of high purity nitrogen. The ASU can also be configured to provide one or more other product streams as well as one or more waste streams, or refrigeration streams that may be used for cooling a feed of air before being vented or fed to another plant process for use (e.g., as a heat transfer fluid, regeneration gas, etc.).
For example, the apparatus 1 can include a compression system 100 that is configured to compress a feed of air to a pre-selected feed pressure. The feed of air can be output from the compression system 100 and fed to an aftercooler 102 for cooling to form a pre-treatment feed stream 101. The pre-treatment feed stream 101 can be fed to a pre-purification unit (PPU) 103. The PPU can be configured as an adsorption system or adsorption unit in some embodiments. For example, the PPU can be configured as a temperature swing adsorption (TSA) system, a pressure swing adsorption (PSA) system, a vacuum swing adsorption system (VSA) or other type of suitable pre-treatment system that is configured to remove undesired impurities from the feed that can cause problems with downstream equipment (e.g., may freeze or otherwise pose problems). The PPU 103 can be configured to remove water and carbon dioxide from the feed of air, for example. A treated feed stream having a pre-selected composition that includes nitrogen and oxygen therein can be subsequently output from the PPU 103 for being fed toward multiple columns of the apparatus.
In some embodiments or some operational cycles, a single feed stream may be provided to the first column 111 or the second column 109. In other embodiments, or other operational cycles, the treated feed stream output from the PPU 103 can be split into more than one portion for being fed to different columns of the ASU at different pressures and/or temperatures. For example, the treated feed stream can be split into first and second portions 160 and 140 or can be split into first, second, and third portions 160, 140, and 210 for feeding toward the first column 111, second column 109, and third column 113.
The first column 111 can be a high pressure (HP) column that operates at a higher operational pressure range than a second column 109. The first column 111 can also operate at a higher operational pressure range than a third column 113. The second column can operate at a higher operational pressure range than the third column 113 such that the second column 109 can be an intermediate pressure (MP) column and the third column 113 can be a low pressure (LP) column. In some embodiments, the operational pressure range for the HP column (e.g., first column 111) can be in a range of 0.42 MPa and 0.70 MPa or in a range of between 0.45 MPa and 0.60 MPa, the operational pressure range for the MP column (e.g., the second column 111) can be in a range of between 0.22 MPa and 0.45 or in a range of between 0.25 MPa and 0.35 MPa, and the operational pressure range for the LP column (e.g., third column 113) can be in a range of between 0.12 MPa and 0.15 MPa or in a range of between 0.10 MPa and 0.18 MPa (wherein these pressure ranges are provided on an absolute pressure basis).
The operational pressure range of the first column 111 can be a pressure range that is of a higher pressure than the operational pressure range of the second column 109. The operational pressure range of the third column 113 can be a pressure range that is of a lower pressure than the operational pressure range of the second column 109.
As noted above, the first portion 160 of the treated feed can be passed to the second column 109. In some embodiments, the first portion 160 can have the second portion 140 split from the first portion 160 upstream of a second feed compressor 104 and the first portion 160 can be passed through a heat exchanger 108 for cooling therein to a pre-selected first portion feed temperature for feeding to the second column as a second column treated feed stream 180. In some embodiments, the second column treated feed stream 180 can be comprised of a fluid. For instance, the second column treated feed stream 180 can be a gaseous stream (e.g., be entirely a gas or be mostly a gas with a small portion being liquid, etc.).
In the splitting of the first portion 160 of the treated feed to form the second portion 140, the first portion 160 can be between 65% and 25% of the mass flow rate of the treated feed output from the PPU and the remaining portion (e.g., 35% to 75% of the feed) can be split off to form the second portion 140 in some embodiments. For example, the first portion 160 can be between 40% and 50% of the mass flow rate of the treated feed output from the PPU and the remaining portion (e.g., 60% to 50% of the feed) can be split off to form the second portion 140 in some embodiments.
In some operational cycles, the second portion 140 of the treated air that can be formed via splitting the second portion 140 from the first portion 160 upstream of the second feed compressor 104 can be passed through the second feed compressor 104 to undergo further compression to a second portion pre-selected feed pressure that is greater than the feed pressure of the first portion 160 of the treated feed after the second portion 140 of the treated feed is split from the first portion 160. A second aftercooler heat exchanger 105 can be positioned downstream of the second feed compressor 104 for providing cooling of the second portion of the treated air. The second portion 140 can subsequently be fed toward the first column 111. For instance, the second portion 140 of the treated feed output from the second aftercooler heat exchanger 105 can be passed through the heat exchanger 108 for cooling to a pre-selected second portion feed temperature. The cooled second portion 140 can be output from the heat exchanger 108 as a first first column feed stream 150 at a pre-selected feed stream temperature for the first first column feed stream 150. The first first column feed stream 150 can be cooled such that this stream is a gaseous stream in some embodiments (e.g., is entirely gas or is mostly gas that also has some liquid).
In some embodiments or operational cycles, the second portion 140 can be split to form the second portion 140 and a third portion 210 after the second portion is output from the second feed compressor 104 and second aftercooler heat exchanger 105. The upstream splitting can form a stream 209 that is split from the second portion for forming the third portion 210. The stream 209 can be split from the second portion such that the third portion can be between 20% to 30% of the total mass flow rate of the total treated feed output from the PPU 103 and the second portion 140 can be the remainder of the second portion (e.g., 55% to 15% of the total treated feed output from the PPU 103 or 40% to 20% of the total treated feed output from the PPU 103) for some embodiments. In such embodiments, the first portion 160 of the of the treated feed can be between 25% to 65% of the of the total treated feed output from the PPU 103
The stream 209 can be passed through another third feed compressor 106 and third aftercooler heat exchanger 107 downstream of the third feed compressor 106 to output the third portion 210 for feeding to the first column 111. The third portion 210 can be at a pre-selected feed pressure that is greater than a feed pressure of the second portion 140 of the treated feed and can also be greater than the feed pressure of the first portion 160 of the treated feed. For example, the pre-selected feed pressure for the first portion 160 can be a pressure that is selected for being suitable for feeding to the second column 109, the pre-selected feed pressure for the second portion 140 can be a pressure suitable for feeding to the first column 111, and the pre-selected feed pressure for the third portion 210 can be a pressure suitable for feeding to the first column 111 at a different location from where the second portion 140 can be fed to the first column 111.
The third portion 210 can be passed through the heat exchanger 108 for being pre-cooled therein to be output for being fed to the second column 111, the first column 109, and/or the third column 113. For example, the third portion 210 can be output from the heat exchanger 108 as a feed stream 220 for being fed to (a) the first column 111 at a location that is above the location at which the first first column feed stream is fed to the first column 111, (b) the second column 109 as a second second column feed stream 235, and/or (c) the third column as a reflux stream 250. The feed stream 220 can be a liquid stream (e.g., entirely liquid) in some embodiments. In other embodiments this stream can be a fluid that is a mixture of gas and liquid (e.g., is mostly liquid, has a significant amount of gas mixed with liquid, etc.).
The third portion 210 that can be output from the heat exchanger 108 as a feed stream 220 can be split for being fed to the first column 111, second column 109 and/or the third column 113 in some operational cycles or some embodiments. For example, the feed stream 220 that may be output from the heat exchanger 108 can be split so a first portion of this stream is fed to the first column 111 as a second first column feed stream 221 and a second portion of the feed stream 220 is fed to the second column 109 as a second second column feed stream 235. This second portion can also be split to form a third portion of the feed stream 220 that can be passed through a heat exchanger 114 for being subcooled therein before it is fed to the third column 113 as a reflux stream 250. In some embodiments, the subcooling of the third portion that is provided as a reflux stream 250 to the third column 113 may not be needed or used.
Also (or as an alternative), in some configurations the third portion 210 that is output from the heat exchanger may only be split for the reflux stream 250 without forming of the second portion that may be fed to the second column 109. In such an embodiment or operational cycle, the reflux stream 250 that is formed can be considered a second portion of the feed stream 220 while a first portion of this stream can be fed to the first column as a second first column feed stream 221.
In yet other embodiments or operational cycles, the feed stream 220 can be split so that the second first column feed stream 221 is not formed and, instead, the stream is fed to the second column 109 and/or the third column 113. In situations where the entirety of the feed stream 220 is fed to the second column 109 as the second second column feed stream 235, the second second column feed stream 235 can be considered a first portion of the feed stream 220. In situations where the entirety of the feed stream 220 is fed to the third column as reflux stream 250, the reflux stream 250 can be considered a first portion of the feed stream 220. In situations where the feed stream 220 can be split so that the second first column feed stream 221 is not formed and this stream is split to form the second second column feed stream 235 and reflux stream 250, the second second column feed stream 235 can be considered the first portion of the feed stream 220 and the reflux stream 250 can be considered the second portion of this feed stream 220.
The first column 111 can be operated in a tower or stack that is spaced apart from a stacked tower having the second and third columns 109 and 113 in vertical alignment with a first reboiler/condenser 112 positioned in the multi-column assembly between the second column 109 and the third column 113. The first column 111 can be operated to separate the nitrogen and oxygen components of the feed stream(s) fed to the first column 111 to output a crude liquid oxygen (CLOX) stream 155, a nitrogen vapor stream 532, and/or a nitrogen product stream 665. The nitrogen product stream 665 can be a nitrogen vapor stream that is over 99 mole percent (mol%) nitrogen (e.g., between 99.9 mol% and 100 mol% nitrogen or between 95 mol% nitrogen and 100 mol% nitrogen). The nitrogen product stream 665 output from the first column 111 can be passed through the heat exchanger 108 to undergo warming therein (and also provide a source of cooling for pre-cooling the feed) for being output from the heat exchanger as a nitrogen product stream 690. The nitrogen product stream 690 can be a high purity nitrogen stream in some embodiments and can be output from the heat exchanger 108 at a relatively high pressure (e.g., a pressure of over 0.45 MPa or between 0.42 MPa and 0.7 MPa, etc.). The nitrogen product stream 690 can also be optionally further compressed after warming via at least one compressor.
In some embodiments, the nitrogen product stream 665 can be output as a liquid nitrogen stream that can be further elevated in pressure (e.g., via at least one pump) and fed to the heat exchanger 108 for being vaporized to form the nitrogen product stream 690. The nitrogen product stream 665 can also be optionally further compressed after vaporization via at least one compressor.
The nitrogen vapor stream 532 can be a high pressure gaseous nitrogen-enriched stream that is also relatively pure nitrogen (e.g., between 99.9 mol% and 100 mol% nitrogen or between 95 mol% nitrogen and 100 mol% nitrogen). The nitrogen vapor stream 532 can have the same concentration of nitrogen as the nitrogen product stream 665 in some embodiments.
The nitrogen vapor stream 532 can be output to the first reboiler-condenser 112 for being condensed to form a liquid nitrogen stream 533 that can be output for returning to the first column 111 as a high pressure column reflux stream 533. In some embodiments, or some operational cycles, a product portion of this high pressure column reflux stream 533 can be split to form a liquid nitrogen product stream 599, which can be fed to a storage device (not shown) or can be fed another unit for subsequent vaporization for providing as a nitrogen gas product. The liquid nitrogen product stream 599 that is split away from the high pressure column reflux stream 533 can be a liquid nitrogen product portion of the high pressure column reflux stream 533, for example.
The first reboiler-condenser 112 can be positioned within the same vessel shell as the second and third columns 109 and 113 and be positioned between the second and third columns 109 and 113 within the vessel shell. The first reboiler-condenser 112 can be configured to boil up liquid at or adjacent a bottom of the third column 109 to form vapor that is to pass upwards through the third column 113. The heat for this vaporization can come from the nitrogen vapor stream 532 fed to the first reboiler-condenser, which can help facilitate condensation of this stream for forming the high pressure column reflux stream 533.
The CLOX stream 155 output from the first column can be a liquid or a mostly liquid fluid (e.g., be two phase with some gas mixed with the liquid). The content of the CLOX stream can include a substantial portion of oxygen. For example, the CLOX stream 155 can be between 34 mol% oxygen and 50 mol% oxygen. The CLOX stream can also include nitrogen and a relatively small concentration of argon along with other elements (e.g., krypton, xenon, etc.). In some embodiments, the CLOX stream 155 can include between 0 mol% and 2 mol% argon and between 50 mol% and 66 mol% nitrogen.
The CLOX stream 155 that is output from the first column 111 can be fed to a second reboiler-condenser 110 to function as a boiling side fluid of the reboiler-condenser 110. Prior to being fed to the third column 113 as an intermediate vapor feed or mostly vapor feed (e.g., a stream that is mostly vapor and up to 35% liquid), the CLOX stream output from the first column 111 can be mixed or merged with a CLOX stream 191 that can be output from the second column 109 (e.g., output from a bottom of the second column 109 or a lower portion of the second column 109).
The first column 111 can also output a third column reflux stream 536 that is to be fed to the third column 113. The third column reflux stream 536 can also optionally be passed through the subcooling heat exchanger 114 for being subcooled therein as a subcooled third column reflux stream 536 prior to being fed to the third column 113.
The second column 109, which can be configured to operate as the MP column, can receive the second column treated feed stream 180 from the heat exchanger 108 that is precooled and compressed to a desired pre-selected second column feed pressure. The second column 109 can also receive a portion of the feed stream 220 for being fed to the second column 109 as a second second column feed stream 235 as noted above in some embodiments or some operational cycles. The second column 109 can be configured to operate to receive this fluid and separate the nitrogen and oxygen components form the feed fluid to form a second column CLOX stream 191 that can include a crude oxygen fluid (e.g., CLOX or a mixture of CLOX and some gaseous crude oxygen). The content of the CLOX stream can include a substantial portion of oxygen. For example, the CLOX stream 191 can be between 34 mol% oxygen and 50 mol% oxygen. The CLOX stream can also include nitrogen and a relatively small concentration of argon along with other elements (e.g., krypton, xenon, etc.). In some embodiments, the CLOX stream 155 can include between 0 mol% and 2 mol% argon and between 50 mol% and 66 mol% nitrogen.
The CLOX stream 191 that is output from the second column 109 can be fed to the second reboiler-condenser 110 to function as a boiling side fluid of the second reboiler-condenser 110. Prior to being fed to the third column 113 as an intermediate vapor feed or mostly vapor feed (e.g., a stream that is mostly vapor and up to 35% liquid), the CLOX stream output from the second column 109 can be mixed or merged with the CLOX stream 155 that can be output from the first column 111 (e.g., output from a bottom of the first column 111 or a lower portion of the first column 111) to form a second reboiler-condenser boiling side feed stream 400 that can be fed to the second reboiler-condenser 110. A portion of this merged CLOX stream can be split upstream of the second reboiler-condenser 110 for being fed to the third column 113 to function as feed stream 405. This split portion can be provided in embodiments or operational cycles when providing separate liquid and vapor feed streams to the third column 113 may be needed or desired.
The second reboiler-condenser 110 can output the boiling side fluid fed therein as an at least partially vaporized crude oxygen stream 440 that can be fed to the third column 113 at a desired location (e.g., at a middle region of the third column 113, near a bottom of the third column 113, etc.). The at least partially vaporized crude oxygen stream 440 can be entirely vapor (e.g., be entirely gaseous as an entirely vaporized stream) or can be a two-phase stream that includes liquid and vapor (e.g., be mostly vapor with a minor portion being liquid, etc.).
In some alternative arrangements, the CLOX streams 191 and 155 can be separately fed to the second reboiler-condenser 110 as boiling side fluids and a portion of one or both of these streams can also be split upstream for feeding to the third column 113 as a feed stream 405. These separate streams can also be output from the second reboiler-condenser 110 and each fed separately to the third column 113 as at least partially vaporized crude oxygen streams 440.
The second column 109 can also output a nitrogen-enriched vapor stream 502 from the top or upper portion of the second column 109. The nitrogen-enriched vapor stream 502 can be fed to the second reboiler-condenser 110 as a condensing side feed for being at least partially condensed so that at least a first portion of the condensed nitrogen-enriched vapor stream 502 can be output from the second reboiler-condenser for being fed to the second column 109 as a second column reflux stream 503. A second portion 520 of the at least partially condensed nitrogen-enriched vapor stream output from the second reboiler-condenser 110 can be fed to the subcooling heat exchanger 114 to be subcooled therein for being fed to an upper portion or top of the third column 113 as a reflux stream.
The second portion 520 of the at least partially condensed nitrogen-enriched vapor stream output from the second reboiler-condenser 110 can be smaller than the third column reflux stream 536 from the first column. In some embodiments, the third column reflux stream 536 from the first column can be mixed with the second portion 520 of the at least partially condensed nitrogen-enriched vapor stream output from the second reboiler-condenser 110 for forming a merged third column reflux stream for feeding to the third column. Alternatively, such reflux streams can be fed to the third column 113 at different locations adjacent the top or upper portion of the third column 113.
The second reboiler-condenser 110 can be positioned in various different locations to be provided as an intermediate reboiler-condenser. For example, the second reboiler-condenser 110 can be stacked on top of the second column 109, positioned inside of the third column 113, or be positioned remote from the first column 111 and second column 109 and also positioned external to the third column 113.
The second column 109 can also output a nitrogen-enriched gaseous stream 780. The nitrogen-enriched gaseous stream can be relatively impure nitrogen (e.g., have a nitrogen content of between 95 mol% nitrogen and 100 mol% nitrogen with the remainder being mostly oxygen, have a nitrogen content of between 98 mol% and 99.5 mol%, etc.). This nitrogen-enriched gaseous stream 780 can be considered an expander feed stream 780 that can be directed to an expander 116 that is connected to a generator G for being expanded therein to generate refrigeration for use as a refrigerant flow fed to the heat exchanger 108 for pre-cooling the feed fed to the columns of the ASU. The expander 116 can be an expander coupled to a brake such as a generator or an expanding unit of a compander that is coupled to a compression unit of the compander that may be utilized for compression of the feed air (e.g., the third feed compressor 106 can be a compression unit of such a compander).
For example, the nitrogen-enriched gaseous stream 780 can be fed to the heat exchanger 108 to provide cooling to a downstream portion of the heat exchanger and subsequently be output from the heat exchanger 108 for being fed to the expander 116 for being expanded therein. The expansion of the warmed nitrogen-enriched stream output from the heat exchanger 108 can further cool that stream so that the expanded nitrogen-enriched stream can be passed from the expander to the heat exchanger 108 to provide further cooling therein as a refrigerant before being output from the heat exchanger 108 as a gaseous nitrogen-enriched stream 795. The gaseous nitrogen-enriched stream 795 output from the heat exchanger 108 can be vented. Prior to being vented, the gaseous nitrogen-enriched stream 795 can be fed to the PPU 103 as a regeneration gas and/or fed to one or more waste towers for production of chilled water.
The generator G can be coupled to the expander 116 so that the expansion of this gas also generates electricity to help power operation of the ASU. For example, electricity can be generated via the generator G to facilitate powering of one or more of the compressors of the ASU.
The inventor has found that having the expander feed stream 780 be output from the second column 109 instead of expanding feed air to the third column 113 can increase the flow of CLOX in stream 191 compared to other expander options. This increased total CLOX flow can decrease the fraction of CLOX boiled in the second reboiler-condenser 110 for a given condensing side flow provided by nitrogen-enriched vapor stream 502. The lower fraction of CLOX that is boiled can help lower the output temperature of the CLOX from the reboiler in stream(s) 440, which can also lower the condensing pressure of the second column 109, which can lower the operational pressure of the second column 109, which can provide a power savings by reducing a feed compression load needed for the feed to be fed to the second column 109 (e.g., reduce the electricity demand needed for compression).
The third column 113 can receive the various streams (e.g., a portion of feed 220 as a reflux stream 250, at least partially vaporized crude oxygen stream 440, CLOX streams that can be provided as at least one feed stream 405, second portion 520 of the at least partially condensed nitrogen-enriched vapor stream output from the second reboiler-condenser 110, etc.) for outputting a nitrogen-enriched stream 707, which can be considered a waste stream in some embodiments. The nitrogen-enriched stream 707 can be a vapor stream that is mostly nitrogen (e.g., between 98 mol% and 100 mol% nitrogen, is between 95 mol% nitrogen and 100 mol% nitrogen, etc.). The nitrogen-enriched stream 707 can be output from an upper portion or top of the third column 113 and fed to the heat exchangers 114 and 108 for providing refrigeration therein for subcooling reflux streams and cooling the feed and can be subsequently output from the heat exchanger 108 as a warmed nitrogen-enriched stream 765. This stream 765 can be vented. Prior to being vented, the nitrogen-enriched stream 765 can be further used by one or more other process elements of the ASU. For instance, the stream 765 can be fed to the PPU 103 as a regeneration gas and/or fed to one or more waste towers for production of chilled water.
The third column 113 can also output a relatively low purity oxygen stream 835 from a lower portion or bottom of the third column 113. The low purity oxygen stream 835 can be comprised of between 90 mol% and 98 mol% oxygen (e.g., between 94 mol% and 97.5 mol% oxygen) with the remainder of this stream mostly being argon and nitrogen, for example. This oxygen stream 835 can be output as a liquid and fed to a pump 115 to increase the stream's pressure to a pre-selected oxygen product stream pressure in some embodiments. The oxygen stream 835 can then be fed to the heat exchanger 108 as a cooling medium therein for pre-cooling the feed so the oxygen stream is warmed and output as a gaseous oxygen stream 840. This gaseous oxygen stream 840 can be a product stream in some embodiments (e.g., be utilized as an oxidant stream to facilitate combustion of another plant system, can be provided for storage for subsequent use in another plant unit's system, etc.). In some embodiments, the gaseous oxygen stream 840 can have the same oxygen content as that of the low purity oxygen stream 835 (e.g., between 90 mol% and 98 mol% oxygen, between 94 mol% and 97.5 mol% oxygen, etc.).
In some embodiments or some operational cycles, the pump 115 may not be utilized and the oxygen stream 835 can be output from the third column 113 for being fed to the heat exchanger 108 for being warmed therein without undergoing an elevation in pressure to a pre-selected oxygen product stream pressure.
In some embodiments, the first column 111, which can be operated as an HP column, can be split into multiple first columns that can each be HP columns. For example, there can be a first first column 111 and also a second first column 200 as shown in Figure 2. This second first column 200 can also be referred to as a fourth column that can also be configured to operate at a high pressure or the first first column 111 can be considered a lower first column 111 and the second first column 200 can be considered a top first column 111. In such a configuration, the second first column 200 can be configured to form the nitrogen product stream 665 based on receiving nitrogen-enriched vapor from the first first column 111. The second first column 200 can be configured to operate at a lower pressure range than the first first column 111 while also being at an operational pressure range that is greater than the pressure ranges of the second column 109 and third column 113 in some configurations. For example, the operational pressure range for the second first column 200 can be in a range of 0.42 MPa and 0.70 MPa or in a range of between 0.45 MPa and 0.60 MPa (in absolute pressure).
The nitrogen product stream 665 output from the second first column 200 can then be fed to the heat exchanger 108 for being warmed therein and being output as a nitrogen product stream 690. The nitrogen product stream 690 can be a high purity nitrogen stream in some embodiments and can be output from the heat exchanger 108 at a relatively high pressure.
In configurations where the HP column is split into the first and second first columns 111 and 200, the top first column (or second first column 200) can be positioned above the first column 111 and/or the second column 109 and can include a reboiler-condenser 201 that is positioned to receive a stream A of CLOX from the first first column 111 and/or second column 109 as a reboiler-condenser feed stream 207, which can be fed as the boiling fluid for the reboiler-condenser 201 of the second first column 200. The stream A of CLOX can be a portion of CLOX stream 155 output from the first first column 111, a portion of CLOX stream 191 output from the second column 109, and/or a portion of the second reboiler-condenser boiling side feed stream 400 after these CLOX streams are merged to form the second reboiler-condenser boiling side feed stream 400.
The stream A that can alternatively be fed to the reboiler-condenser 201 of the fourth column (or second first column 200) can be a portion of the oxygen product stream 835 that can be split from that stream or a portion of reflux stream 250. These alternative options for stream A are shown in Figure 2. In yet other embodiments, the stream A can be a combination of such streams and/or another stream that may be able to provide sufficient cooling as a reboiler-condenser feed stream 207 for forming a nitrogen reflux stream for the reboiler-condenser 201 of the second first column 200 that can optionally have a portion split from this reflux to provide a liquid nitrogen product stream 599.
The second first column 200 can also receive a portion of the nitrogen vapor stream 532 output from the first first column 111 as a nitrogen-enriched vapor feed 205. The second first column 200 can be operated so that the nitrogen-enriched vapor feed 205 undergoes further separation to form the high purity nitrogen product stream 665.
The nitrogen-enriched vapor feed 205, when utilized, can be considered a second portion of the of the nitrogen vapor stream 532 output from the first first column 111. A first portion of the nitrogen vapor stream 532 in such embodiments can be fed to the first reboiler-condenser 112 for being condensed to form the high pressure column reflux stream 533.
The reboiler-condenser 201 of the second first column 200 can provide reflux for this separation via the reboiler-condenser feed stream 207, which can be boiled in the reboiler-condenser with vapor from the enriched nitrogen to also form a reflux stream for the second first column. A portion of this reflux stream of the reboiler-condenser of the second first column 200 can be split out as a high pressure liquid nitrogen product stream 599, which can be fed to a storage device (not shown), in some embodiments or operational cycles as well. In such a configuration, the first reboiler-condenser 112 can receive the nitrogen vapor stream 532 from the first first column to form the liquid nitrogen stream 533 that can be output for returning to the first column 111 as the high pressure column reflux stream 533 without splitting of any portion of the fluid as a liquid nitrogen product stream.
The second reboiler-condenser 201 of the second first column 200 can also output third column intermediate feed stream 208 having boiled vapor of the second first column 200 (e.g., third column intermediate feed steam 208 can include vapor or be mostly vapor). The lower portion or bottom of the second first column 200 can output a liquid stream 206 for feeding to the third column 113 as a reflux stream and/or for joining with stream 533 as reflux to the first first column 111.
The embodiment of Figure 2 can be utilized to provide multiple high pressure columns of shorter height or length. Such a configuration can provide added process design and plant design flexibility to facilitate production of product streams that can also allow design flexibility to provide different nitrogen production flows without excess costs associated with use of a larger first column 111. Having the expander 116 feed stream 780 be provided by the second column 109 can increase the flow of CLOX in stream 191 compared to other expander options. This increased total CLOX flow can decrease the fraction of CLOX boiled in the second reboiler-condenser 110 for a given condensing side flow 502 output from the first column 111. The lower fraction of CLOX that is boiled can help lower the output temperature of the CLOX from the reboiler in stream(s) 440, which can also lower the condensing pressure of the second column 109, which can lower the operational pressure of the second column 109, which can provide a power savings by reducing a feed compression load needed for the feed to be fed to the second column 109 (e.g., reduce the electricity demand needed for compression).
Figure 3 illustrates an exemplary embodiment of a process for providing high purity nitrogen. The first and second exemplary embodiments of the apparatus 1 discussed above in connection with Figures 1 and 2 can be configured to implement this first exemplary embodiment of the process.
For instance, in a first step S1, a feed of air can be fed to at least one high pressure column (e.g., first column 111) and an intermediate pressure column (e.g., second column 109) for separation of nitrogen and oxygen from the air for forming at least one oxygen product stream via a low pressure column (e.g., third column 113) that can be aligned with the intermediate pressure column (e.g., second column 109). The low pressure column can be in fluid communication with the intermediate pressure column and at least one of the high pressure columns.
In a second step S2, a high pressure column can feed a stream of nitrogen to a reboiler condenser (e.g., first reboiler-condenser 112) and the intermediate pressure column can output a nitrogen-enriched stream for being fed to an expander (e.g., expander 116) for providing refrigeration for pre-cooling the feed fed to the high pressure column(s) and intermediate column. In some embodiments, the expander 116 utilized to facilitate this refrigeration can be connected to a generator G so power can also be recovered from the expansion of the nitrogen-enriched stream.
In third step S3, a high pressure column that receives a feed of air (e.g., first column 111) can output a high purity nitrogen stream and/or feed fluid to another high pressure column (e.g., second first column 200, which can also be considered a fourth column) for forming the high purity nitrogen stream (e.g., high purity nitrogen product stream 665).
The process can also include other steps. For example, the low pressure column (e.g., third column 113) can output an oxygen stream for providing an oxygen product stream (e.g., a relatively low purity oxygen stream 835). As another example, a high pressure column and/or an intermediate pressure column can output a CLOX stream for feeding to the low pressure column (e.g., the third column 113) and/or a second high pressure column (e.g., second high pressure column 200, when utilized). The intermediate pressure column can feed a CLOX stream to a second reboiler-considered 110, for example, for being at least partially vaporized therein so the vaporized crude oxygen stream can be fed to the low pressure column (e.g., third column 113).
As yet another example, a second reboiler-condenser can be positioned to receive at least one of: a CLOX stream from a high pressure column and/or a CLOX stream from an intermediate pressure column for boiling the same to provide reflux to the intermediate pressure column (e.g., second column reflux stream 503) and an at least partially vaporized oxygen-enriched stream to the low pressure column (e.g., an at least partially vaporized crude oxygen stream 440).
It should also be appreciated that other modifications can also be made to meet a particular set of criteria for different embodiments of the apparatus 1 or process. For instance, the arrangement of valves, piping, and other conduit elements (e.g., conduit connection mechanisms, tubing, seals, valves, etc.) for interconnecting different units of the apparatus for fluid communication of the flows of fluid between different elements (e.g., pumps, compressors, fans, valves, conduits, etc.) can be arranged to meet a particular plant layout design that accounts for available area of the apparatus, sized equipment of the apparatus, and other design considerations. For example, the size of each column, number of stages each column has, the size and arrangement of each reboiler-condenser, and the size and configuration of any heat exchanger, conduits, expanders, pumps, or compressors can be modified to meet a particular set of design criteria. As another example, the flow rate, pressure, and temperature of the fluid passed through one or more heat exchangers as well as passed through other plant elements can vary to account for different plant design configurations and other design criteria. As yet another example, the number of plant units and how they are arranged can be adjusted to meet a particular set of design criteria. As yet another example, the material composition for the different structural components of the units of the plant and the plant can be any type of suitable materials as may be needed to meet a particular set of design criteria.
For example, the first reboiler-condenser 112 can be positioned in various different locations to be provided as a reboiler-condenser for the first first column 111. For example, the first reboiler-condenser 112 can be stacked on top of the first column 111, positioned inside of the third column 113, or be positioned remote from the first column 111 and also positioned external to the third column 113 and/or second column 109. As another example, the subcooling heat exchanger 114 may not be utilized in some embodiments for optional subcooling. As yet another example, the HP column for the ASU can be provided in a single column arrangement (e.g., Fig. 1) or in a multiple column arrangement (e.g., embodiment of Fig. 2).
As yet another example, embodiments of the apparatus 1 and process can each be configured to include process control elements positioned and configured to monitor and control operations (e.g., temperature and pressure sensors, flow sensors, an automated process control system having at least one work station that includes a processor, non-transitory memory and at least one transceiver for communications with the sensor elements, valves, and controllers for providing a user interface for an automated process control system that may be run at the work station and/or another computer device of the plant, etc.). It should be appreciated that embodiments can utilize a distributed control system (DCS) for implementation of one or more processes and/or controlling operations of an apparatus or process as well.
As another example, it is contemplated that a particular feature described, either individually or as part of an embodiment, can be combined with other individually described features, or parts of other embodiments. The elements and acts of the various embodiments described herein can therefore be combined to provide further embodiments. Thus, while certain exemplary embodiments of the process, apparatus, system, and methods of making and using the same have been shown and described above, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Claims

A process for providing nitrogen and oxygen comprising:
splitting a feed of air for feeding some of the air to a first column and some of the air to a second column, the first column operating at a first pressure range and the second column operating at a second pressure range, the first pressure range being a higher pressure range than the second pressure range;

feeding a stream of crude oxygen to a third column, the crude oxygen being comprised of at least a portion of a crude oxygen stream output from the first column and/or at least a portion of a crude oxygen stream output from the second column, the third column operating at a third pressure range, the third pressure range being a lower pressure range than the second pressure range;

outputting a nitrogen-enriched vapor stream from the second column and feeding the nitrogen-enriched vapor stream output from the second column to an expander to be expanded therein;

feeding the expanded nitrogen-enriched vapor stream to a heat exchanger as a refrigerant for pre-cooling the air being fed to the first column and the second column; and

outputting a nitrogen-rich stream from the first column or a fourth column that is fluidly connected to the first column and operates at a fourth pressure range that is greater than the second pressure range; and

outputting an oxygen product stream from the third column.
A process according to Claim 1, wherein the nitrogen-rich stream is output from the first column and comprises between 98.5 mole percent (mol%) nitrogen and 100 mol% nitrogen.
A process according to Claim 1, wherein the nitrogen-rich stream is output from the fourth column, the process also comprising:
the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column;

feeding a stream of crude oxygen to the reboiler-condenser of the fourth column, the crude oxygen fed to the fourth column being comprised of a portion of the crude oxygen stream output from the first column and/or a portion of the crude oxygen stream output from the second column.
A process according to Claim 3, comprising:
feeding a stream comprising vapor output from a reboiler-condenser of the fourth column to an intermediate section of the third column; and/or

feeding a liquid stream output from a bottom portion of the fourth column to the first column and/or the third column as a reflux stream.
A process according to Claim 1, wherein the nitrogen-rich stream is output from the fourth column, the process also comprising:
the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column;

feeding a portion of the oxygen product stream output from the third column to the reboiler-condenser of the fourth column.
A process according to any of the preceding claims, comprising:
passing at least a portion of a nitrogen-enriched vapor output from the first column to a first reboiler-condenser to condense the nitrogen-enriched vapor, the first reboiler-condenser positioned between the second column and the third column within a vessel shell so that liquid at a bottom portion of the third column is vaporizable via the first reboiler-condenser; and

passing a first portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser to the first column as a reflux stream for the first column; and

splitting a second portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser from the first portion of the condensed nitrogen-enriched vapor output from the first reboiler-condenser as a liquid nitrogen (LIN) product stream.
A process according to any of the preceding claims, wherein the outputting of the oxygen product stream from the third column comprises outputting a product stream comprising oxygen from a bottom portion of the third column, the oxygen product stream comprising at least 90 mole percent oxygen.
A process according to Claim 7, comprising:
passing at least a portion of the oxygen product stream through a heat exchanger to vaporize the portion of the oxygen product stream passed through the heat exchanger.
A process according to Claim 1, wherein the nitrogen-rich stream is output from the fourth column, the process also comprising:
the first column outputting a nitrogen-enriched vapor stream such that a first portion of the nitrogen-enriched vapor stream is fed to a first reboiler-condenser to condense the first portion of the nitrogen-enriched vapor and a second portion of the nitrogen-enriched vapor stream output from the first column is fed to the fourth column, the first reboiler-condenser positioned between the second column and the third column within a vessel shell so that liquid at a bottom portion of the third column is vaporizable via the first reboiler-condenser for condensing the first portion of the nitrogen-enriched vapor; and

the first reboiler-condenser outputting the condensed first portion of the nitrogen-enriched vapor for feeding to the first column as a reflux stream.
A process according to any of the preceding claims, wherein the feeding of the stream of crude oxygen to the third column comprises:
feeding at least a portion of the crude oxygen stream output from the first column and/or at least a portion of the crude oxygen stream output from the second column to a second reboiler-condenser for vaporization to form at least one at least partially vaporized crude oxygen stream for feeding to the third column as the stream of crude oxygen.
An apparatus for providing nitrogen and oxygen, comprising:
a first column configured to operate at a first pressure range, the first column positioned to receive a first column feed of air output from a compression system;

a second column configured to operate at a second pressure range, the second pressure range being a lower pressure range than the first pressure range, the second column positioned to receive a second column feed of air output from the compression system, the second column configured to output a stream of nitrogen-enriched vapor;

a third column positioned to receive at least one stream of crude oxygen via at least one of: a portion of a stream of crude oxygen output from a bottom portion of the first column and/or a portion of a stream of crude oxygen output from a bottom portion of the second column and output an oxygen product stream;

an expander positioned to receive the nitrogen-enriched vapor output from the second column to expand the nitrogen-enriched vapor and feed the expanded nitrogen-enriched vapor to a heat exchanger as a refrigerant, the heat exchanger positioned to pre-cool the air upstream of the first column and the second column.
An apparatus according to Claim 11, wherein the second column and the third column are vertically aligned, have a substantially similar diameter, and are within a vessel shell.
An apparatus according to Claim 12, comprising:
a first reboiler-condenser positioned within the vessel shell between the second column and the third column, the first reboiler-condenser configured to receive a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor to the first column as a stream of reflux and also boil liquid from a bottom portion of the third column.
An apparatus according to Claim 13, wherein the first column is configured to output a nitrogen-rich stream as a product stream and/or a liquid nitrogen product portion of the stream of reflux is splittable from the stream of reflux to form a liquid nitrogen product stream.
An apparatus according to Claim 11, comprising:
a first reboiler-condenser positioned within a vessel shell between the second column and the third column, the first reboiler-condenser configured to receive a first portion of a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor to the first column as a stream of reflux and also boil liquid from a bottom portion of the third column;

a fourth column positioned to receive a second portion of the nitrogen-enriched vapor output from the first column;

the fourth column configured to output a nitrogen-rich stream as a product stream.
An apparatus according to Claim 15, wherein a reboiler-condenser of the fourth column is configured to output a liquid nitrogen reflux stream, a portion of the liquid nitrogen reflux stream being splittable from the liquid nitrogen reflux stream outputtable from the reboiler-condenser of the fourth column to form a liquid nitrogen product stream.
An apparatus according to any of Claims 11 to 16, comprising:
the heat exchanger, the heat exchanger positioned to receive the nitrogen-enriched vapor output from the second column to warm the nitrogen-enriched vapor via cooling of the air fed to the heat exchanger and feed the warmed nitrogen-enriched vapor to the expander to expand the nitrogen-enriched vapor, the heat exchanger also configured and positioned to receive the expanded nitrogen-enriched vapor outputtable from the expander to pre-cool the air.
An apparatus according to Claim 11, comprising:
a first reboiler-condenser positioned within a vessel shell between the second column and the third column, the first reboiler-condenser configured to receive a nitrogen-enriched vapor from the first column to condense the vapor and output the condensed nitrogen-enriched vapor for feeding to the first column as a stream of reflux; and

a second reboiler-condenser positioned to receive at least one of the stream of crude oxygen output from the bottom portion of the first column and/or the stream of crude oxygen output from the bottom portion of the second column for vaporization to form at least one at least partially vaporized crude oxygen stream for feeding to the third column;

the third column being fluidly connected to the second reboiler-condenser to receive the at least one at least partially vaporized crude oxygen stream as the at least one stream of crude oxygen received via the portion of the stream of crude oxygen output from the bottom portion of the first column and/or the portion of the stream of crude oxygen output from the bottom portion of the second column.
A process according to any of Claims 1 to 10 or an apparatus according to any of Claims 11 to 18, wherein:
the first pressure range is from 0.42 MPa to 0.7 MPa,

the second pressure range is from 0.22 MPa to 0.45 MPa, and

the third pressure range is from 0.10 MPa to 0.18 MPa.