INTEGRATED MULTICOMPONENT REFRIGERANT AND AIR SEPARATION PROCESS FOR PRODUCING LIQUID OXYGEN

Abstract

A hybrid process of air separation and gas liquefaction, including dividing a compressed multicomponent refrigerant stream into a first portion and a second portion, introducing the first portion into a gas liquefaction system, thereby producing a first multicomponent refrigerant return stream, and introducing the second portion into an air separation system, thereby producing a second multicomponent refrigerant return stream. Wherein the first multicomponent refrigerant return stream and the second multicomponent refrigerant return are recompressed in a common compression system, thereby producing the compressed multicomponent refrigerant stream.

Claims

1. A hybrid process of air separation and gas liquefaction, comprising: dividing a compressed multicomponent refrigerant stream into a first portion and a second portion, introducing the first portion into a gas liquefaction system, thereby producing a first multicomponent refrigerant return stream, and introducing the second portion into an air separation system, thereby producing a second multicomponent refrigerant return stream. wherein the first multicomponent refrigerant return stream and the second multicomponent refrigerant return are recompressed in a common compression system, thereby producing the compressed multicomponent refrigerant stream.

2. The hybrid process of claim 1, wherein the multicomponent refrigerant stream comprises one or more of the following components: nitrogen, argon, methane, ethane ethylene, propane, butane, pentane, and fluorocarbons.

3. The hybrid process of claim 1, wherein a gaseous natural gas stream enters the gas liquefaction system and a liquid natural gas stream exits the gas liquefaction system.

4. The hybrid process of claim 1, wherein the air separation system produces at least one liquid oxygen stream.

5. The hybrid process of claim 1, wherein the compression system is a single compressor.

6. The hybrid process of claim 1, wherein the compression system comprises at least two or more parallel compressors.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0032] For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

[0033] FIG. 1 is a schematic representation of a combined multicomponent refrigerant cycle used with an air separation unit, as known in the art.

[0034] FIG. 2 is another schematic representation of a combined multicomponent refrigerant cycle used with an air separation unit, as known in the art.

[0035] FIG. 3 is a schematic representation of the heat flow within the main heat exchanger in a system configured as described in FIG. 2.

[0036] FIG. 4 is a schematic representation of a combined multicomponent refrigerant cycle used with an air separation unit, in accordance with one embodiment of the present invention.

[0037] FIG. 5 is a schematic representation of the heat flow within the main heat exchanger in a system configured as described in FIG. 4.

[0038] FIG. 6 is a schematic representation of a combined multicomponent refrigerant cycle used with an air separation unit, in accordance with one embodiment of the present invention.

ELEMENT NUMBERS

[0039] 101=purified feed air stream [0040] 102=main heat exchanger [0041] 103=higher-pressure column [0042] 104=nitrogen enriched vapor stream [0043] 105=main condenser [0044] 106=nitrogen-enriched liquid stream [0045] 107=sub-cooler [0046] 108=lower-pressure column [0047] 109=product liquid nitrogen stream [0048] 110=oxygen enriched liquid stream [0049] 111=sub-cooler [0050] 112=first portion (of oxygen-enriched liquid) [0051] 113=second portion (of oxygen-enriched liquid) [0052] 114=argon column condenser [0053] 115=nitrogen rich vapor stream [0054] 116=waste stream [0055] 117=nitrogen enriched liquid (to sub-cooler) [0056] 118=oxygen rich vapor stream [0057] 119=product gaseous oxygen stream [0058] 120=liquid oxygen [0059] 121=oxygen and argon containing stream [0060] 122=argon column [0061] 123=oxygen-richer fluid (from argon column) [0062] 124=product liquid argon [0063] 125=low-pressure multicomponent refrigerant stream [0064] 126=multicomponent refrigerant recycle compressor [0065] 127=multicomponent refrigerant aftercooler [0066] 128=compressed multicomponent refrigerant stream [0067] 129=cooled, compressed multicomponent refrigerant stream [0068] 130=multicomponent refrigerant stream throttle valve [0069] 131=refrigeration bearing multicomponent refrigerant stream [0070] 201=warm multicomponent refrigerant return steam [0071] 202=multicomponent refrigerant compressor [0072] 203=pressurized multicomponent refrigerant stream [0073] 204=multicomponent refrigerant cooler [0074] 205=cooled pressurized multicomponent refrigerant stream [0075] 206=first phase separator vessel [0076] 207=first vapor portion (from first phase separator) [0077] 208=first liquid portion (from first phase separator) [0078] 209=liquefaction heat exchanger [0079] 210=first nitrogen recycle stream [0080] 211=low-pressure nitrogen compressor [0081] 212=warm medium-pressure nitrogen stream [0082] 213=first nitrogen cooler [0083] 214=cooled medium-pressure nitrogen stream [0084] 215=air separation unit [0085] 216=second nitrogen recycle stream [0086] 217=combined medium-pressure nitrogen stream [0087] 218=medium-pressure nitrogen compressor [0088] 219=warm intermediate-pressure nitrogen stream [0089] 220=second nitrogen cooler [0090] 221=cooled intermediate-pressure nitrogen stream [0091] 222=high-pressure nitrogen booster [0092] 223=high-pressure nitrogen stream [0093] 224=first nitrogen refrigeration stream [0094] 225=second nitrogen refrigeration stream [0095] 226=nitrogen expander [0096] 227=expanded nitrogen stream [0097] 228=fifth phase separator vessel [0098] 229=nitrogen vapor portion (from fifth phase separator) [0099] 230=nitrogen liquid portion (from fifth phase separator) [0100] 231=combined nitrogen stream [0101] 232=internal liquid nitrogen stream [0102] 233=return portion (of internal liquid nitrogen stream) [0103] 234=storage portion (of internal liquid nitrogen stream) [0104] 235=cold nitrogen recycle stream [0105] 236=inlet natural gas stream [0106] 237=liquid natural gas stream [0107] 238=compressed and purified inlet air stream [0108] 239=first heat exchanger [0109] 240=medium-pressure nitrogen stream [0110] 241=liquid oxygen stream [0111] 242=warmed first vapor stream [0112] 243=second phase separator vessel [0113] 244=second vapor portion (from second phase separator) [0114] 245=second liquid portion (from second phase separator) [0115] 246=at least partially condensed portion [0116] 247=warm second liquid portion [0117] 248=warmed first liquid stream [0118] 249=third phase separator vessel [0119] 250=third vapor portion (from third phase separator) [0120] 251=third liquid portion (from third phase separator) [0121] 252=third combined multicomponent refrigerant stream [0122] 253=warm combined nitrogen steam [0123] 254=fourth phase separator vessel [0124] 255=fourth vapor portion (from fourth phase separator) [0125] 256=fourth liquid portion (from fourth phase separator) [0126] 257=fourth combined multicomponent refrigerant stream [0127] 301=warm multicomponent refrigerant return steam [0128] 302=combined multicomponent return stream [0129] 303=multicomponent refrigerant compressor [0130] 304=pressurized multicomponent refrigerant stream [0131] 305=first part (of pressurized multicomponent refrigerant stream) [0132] 306=multicomponent refrigerant cooler [0133] 307=cooled multicomponent refrigerant stream [0134] 308=first phase separator vessel [0135] 309=first vapor portion (from first phase separator) [0136] 310=first liquid portion (from first phase separator) [0137] 311=warmed first vapor stream [0138] 312=second phase separator vessel [0139] 313=second vapor portion (from second phase separator) [0140] 314=second liquid portion (from second phase separator) [0141] 315=second combined multicomponent refrigerant stream [0142] 316=warm combined nitrogen steam [0143] 317=warmed first liquid stream [0144] 318=third phase separator vessel [0145] 319=third vapor portion (from third phase separator) [0146] 320=third liquid portion (from third phase separator) [0147] 321=third combined multicomponent refrigerant stream [0148] 322=inlet air stream [0149] 323=main air compressor [0150] 324=inlet air cooler [0151] 325a/b=air purification vessel [0152] 326=purified inlet air stream [0153] 327=Claude compressor [0154] 328=boosted air cooler [0155] 329=cooled, boosted air stream [0156] 330=cold air stream [0157] 331=condensed first portion (of cooled inlet air) [0158] 332=second portion (of cooled inlet air) [0159] 333=Claude expander [0160] 334=expanded second portion [0161] 335=distillation column [0162] 336=liquid nitrogen product [0163] 337=liquid oxygen product stream [0164] 338=liquid oxygen stream [0165] 339=liquid oxygen pump [0166] 340=high-pressure liquid oxygen stream [0167] 341=high-pressure gaseous oxygen product stream [0168] 342=waste nitrogen stream [0169] 343=warmed waste nitrogen stream [0170] 344=waste nitrogen heater [0171] 345=hot waste nitrogen stream [0172] 346ab=regeneration waste stream [0173] 347=first liquefaction heat exchanger [0174] 348=multicomponent refrigerant cycle [0175] 349=first part (of pressurized multicomponent refrigerant stream) [0176] 350=warm multicomponent refrigerant return steam [0177] 351=supplemental compressor [0178] 352=cold inlet stream [0179] 402=multicomponent refrigerant cooler [0180] 403=cooled pressurized multicomponent refrigerant stream [0181] 404=first phase separator vessel [0182] 405=first vapor portion (from first phase separator) [0183] 406=first liquid portion (from first phase separator) [0184] 407=second liquefaction heat exchanger [0185] 408=inlet natural gas stream [0186] 409=cool natural gas stream [0187] 410=fifth phase separator vessel [0188] 411=fifth vapor portion (from fifth phase separator) [0189] 412=fifth liquid portion (from fifth phase separator) [0190] 413=liquid natural gas stream [0191] 414=warmed first vapor stream [0192] 415=second phase separator vessel [0193] 416=second vapor portion (from second phase separator) [0194] 417=second liquid portion (from second phase separator) [0195] 418=at least partially condensed portion [0196] 419=warm second liquid portion [0197] 420=warmed first liquid stream [0198] 421=third phase separator vessel [0199] 422=third vapor portion (from third phase separator) [0200] 423=third liquid portion (from third phase separator) [0201] 424=third combined multicomponent refrigerant stream [0202] 425=warm combined nitrogen steam [0203] 426=fourth phase separator vessel [0204] 427=fourth vapor portion (from fourth phase separator) [0205] 428=fourth liquid portion (from fourth phase separator) [0206] 429=fourth combined multicomponent refrigerant stream

DESCRIPTION OF PREFERRED EMBODIMENTS

[0207] Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

[0208] It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0209] FIG. 4 and FIG. 6 illustrate two separate parts of a single integrated system. FIG. 4 illustrates an ASU system with an integrated multicomponent refrigerant cycle. FIG. 6 illustrates a natural gas liquefaction system with an integrated multicomponent refrigerant cycle. Both multicomponent refrigerant cycles share a common mixed refrigerant compressor (multicomponent refrigerant compressor 303).

[0210] Turning now to FIG. 4, the multicomponent refrigerant cycle 348 includes warm multicomponent refrigerant return steam 301, which is at reduced pressure. Warm multicomponent refrigerant return stream 301 is combined with warm multicomponent refrigerant return steam 350 (described below) and combined multicomponent return stream 302 has the pressure increased in multicomponent refrigerant compressor 303, thereby producing pressurized multicomponent refrigerant stream 304. Pressurized multicomponent refrigerant stream 304 is split into a first part 349 and a second part 305. First part 349 is sent to second liquefaction heat exchanger 407 (described below). Second part 305 enters multicomponent refrigerant cooler 306, thereby producing cooled multicomponent refrigerant stream 307. Cooled multicomponent refrigerant stream 307 is introduced into first phase separator vessel 308, which produces first vapor portion 309 and first liquid portion 310.

[0211] After passing through first liquefaction heat exchanger 347, first vapor portion 309 exits as warmed first vapor stream 311. Warmed first vapor stream 311 is introduced to second phase separator vessel 312, which produces second vapor portion 313 and second liquid portion 314. Second vapor portion 313 and second liquid portion 314 are combined to form second combined multicomponent refrigerant stream 315, which is introduced into first liquefaction heat exchanger 347. After passing through first liquefaction heat exchanger 347 second combined multicomponent refrigerant stream 315 exits as warmed combined nitrogen stream 316.

[0212] After passing through first liquefaction heat exchanger 347, first liquid portion 310 exits as warmed first liquid stream 317. Warmed first liquid stream 317 and warmed combined nitrogen stream 316 are introduced into third phase separator vessel 318. Third phase separator vessel 318 produces third vapor portion 319 and third liquid portion 320. Third vapor portion 319 and third liquid portion 320 are combined to form third combined multicomponent refrigerant stream 321, which is introduced into first liquefaction heat exchanger 347. After passing through first liquefaction heat exchanger 347, third combined multicomponent refrigerant stream 321 exits as warm multicomponent refrigerant return steam 301.

[0213] Multicomponent refrigerant cycle and nitrogen refrigeration cycle work together to provide sufficient refrigeration duty to liquefy inlet natural gas stream 408 into liquid natural gas stream 413 (described below).

[0214] Inlet air stream 322 enters main air compressor 323 wherein the pressure is increased, and the pressurized air is cooled in inlet air cooler 324. The cooled, compressed air stream is then directed to one of air purification vessel 325a/b, wherein the inlet air stream is purified, thereby producing purified inlet air stream 326. Purified inlet air stream 326 is then compressed in Claude compressor 327 and cooled in boosted air cooler 328. Cooled, boosted air stream 329 then enters first liquefaction heat exchanger 347, thereby forming cold air stream 330. After having the temperature reduced, first portion 331 of cold air stream 330 exits first liquefaction heat exchanger 347, is optionally further compressed in supplemental compressor 351, and then enters distillation column 335 as cold inlet stream 352.

[0215] Second portion 332 of the cold air stream 330 exits first liquefaction heat exchanger 347 and then enters Claude expander 333. Expanded second air stream 334 then enters distillation column 335. Distillation column 335 produces at least liquid nitrogen product stream 336, waste nitrogen stream 342, optional liquid oxygen stream 338, and liquid oxygen product stream 337. In order to produce the desired flowrate in both optional liquid oxygen stream 338 and liquid oxygen product stream 337, it is necessary to introduce additional refrigeration duty, in the form of expanded second air stream 334. At least a portion of the liquid oxygen from distillation column 335 may be exported as a liquid oxygen product stream 337.

[0216] Optionally, liquid oxygen stream 338 may be removed from distillation column 335. Liquid oxygen stream 338 is increased in pressure in liquid oxygen pump 339, thereby producing high-pressure liquid oxygen stream 340. High-pressure liquid oxygen stream 340 is then introduced into first liquefaction heat exchanger 347, wherein it is heated and vaporized, thereby producing optional high-pressure gaseous oxygen product stream 341, which then exits the system. One skilled in the art will recognize that liquid oxygen pump 339 may just as easily product low-pressure or medium-pressure liquid oxygen, and therefore the system may produce low-pressure or medium-pressure gaseous oxygen (not shown) in addition to the high-pressure gaseous oxygen system as illustrated. All oxygen product streams may be only liquid. Or a portion may be liquid and additional (optional) portions maybe low-pressure gaseous oxygen and/or high-pressure gaseous oxygen.

[0217] After passing through first liquefaction heat exchanger 347, warmed waste nitrogen stream 343 is heated in waste nitrogen heater 344, thereby producing hot waste nitrogen stream 345. Hot waste nitrogen stream 345 is then used to regenerate air purification vessels 325a/b as needed, with the resulting regeneration waste exiting in regeneration waste streams 346a/b. FIG. 5 illustrates the heat flow within the main heat exchanger in a system configured as described in FIG. 4.

[0218] Turning now to FIG. 6, the multicomponent refrigerant cycle includes warm multicomponent refrigerant return steam 350, which is at reduced pressure. As described above, warm multicomponent refrigerant return stream 350 is combined with warm multicomponent refrigerant return stream 301 and combined multicomponent return stream 302 has the pressure increased in multicomponent refrigerant compressor 303, thereby producing pressurized multicomponent refrigerant stream 304. Pressurized multicomponent refrigerant stream 304 is split into a first part 349 and a second part 305. First part 349 enters multicomponent refrigerant cooler 402, thereby producing cooled pressurized multicomponent refrigerant stream 403. Cooled, pressurized multicomponent refrigerant stream 403 is introduced to first phase separator vessel 404, which produces first vapor portion 405 and first liquid portion 406.

[0219] After passing through second liquefaction heat exchanger 407, first vapor portion 405 exits as warmed first vapor stream 414. Warmed first vapor stream 414 is introduced to second phase separator vessel 415, which produces second vapor portion 416 and second liquid portion 417. Second vapor portion 416 is introduced into second liquefaction heat exchanger 407. After passing through second liquefaction heat exchanger 407 second vapor portion 416 exits as cooled to form at least partially condensed portion 418. Second liquid portion 417 is introduced into second liquefaction heat exchanger 407. After passing through second liquefaction heat exchanger 407, second liquid portion 417 exits as warm second liquid portion 419.

[0220] After passing through second liquefaction heat exchanger 407, first liquid portion 406 exits as warmed first liquid stream 420. At least partially condensed portion 418 is introduced into third phase separator vessel 421. Third phase separator vessel 421 produces third vapor portion 422 and third liquid portion 423. Third vapor portion 422 and third liquid portion 423 are combined to form third combined multicomponent refrigerant stream 424, which is introduced into second liquefaction heat exchanger 407. After passing through second liquefaction heat exchanger 407, third combined multicomponent refrigerant stream 424 exits as warm combined multicomponent refrigerant steam 425.

[0221] Warmed second liquid portion 419, warmed first liquid stream 420, and warm combined multicomponent refrigerant steam 425 are introduced to fourth phase separator vessel 426. Exiting fourth phase separator vessel 426 are fourth vapor portion 427 and fourth liquid portion 428. Fourth vapor portion 427 and fourth liquid portion 428 are combined to form fourth combined multicomponent refrigerant stream 429, which is introduced into second liquefaction heat exchanger 407. After passing through second liquefaction heat exchanger 407, fourth combined multicomponent refrigerant stream 429 exits as warm multicomponent refrigerant return steam 350.

[0222] Inlet natural gas stream 408 is introduced into liquefaction heat exchanger 407 and exits as cool natural gas stream 409. Cool natural gas stream 409 is introduced to fifth phase separator vessel 410, which produces fifth vapor portion 411 and fifth liquid portion 412. Fifth vapor portion 411 reenters liquefaction heat exchanger 407 and exits as liquid natural gas stream 413.

[0223] It is understood, but not shown in FIG. 6, that there will be pressure reducing valves on streams 419, 420, and 418

[0224] Multicomponent refrigerant cycle and nitrogen refrigeration cycle work together to provide sufficient refrigeration duty to liquefy inlet natural gas stream 408 into liquid natural gas stream 413.

[0225] One skilled in the art will recognize a number of advantages of the proposed common MR compression system 348 with independent heat exchange systems for a) NG liquefaction 407 and b) ASU refrigeration 347. [0226] 1) Significant compression equipment cost savings as compared to individual ASU and NG compression and liquefaction systems. [0227] 2) The NG liquefaction system design may now be standardized and/or copied from typical known stand-alone NG liquefaction systems but with the savings (removal of) the MR compression since the compression is now common. [0228] 3) Oxygen rich streams are common in ASU exchangers, and it is desirable to keep flammable components away from oxygen rich streams. With the proposed arrangement, the flammable NG product is removed from the ASU exchanger. The common MR components may be selected from a list of nonflammable components such as environmentally acceptable fluorocarbons.

[0229] It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.