Patent Application
20190063826
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An oil production site generates gas while recovering crude oil from a subterranean formation. The gas can include lighter hydrocarbons such as C1-C8 hydrocarbons, water, nitrogen, carbon dioxide, and other components. The gas is commonly combusted to convert the hydrocarbons in the gas into carbon dioxide and water, which are then released into the environment. The combustion of the gas may be referred to as a flare, and the gas that is combusted may be referred to as flare gas.
In one aspect, the disclosure includes a method for flare recovery. A flare gas inlet stream is received, wherein the flare gas inlet stream comprises C1-C8 hydrocarbons. The flare gas inlet stream is separated in a recovery column to produce a C1-C2 hydrocarbon stream and a C3-C8 hydrocarbon stream. The C3-C8 hydrocarbon stream is separated in a separation column to produce a C3 hydrocarbon stream and a C4-C8 hydrocarbon stream.
In another aspect, the disclosure includes a set of process equipment for flare recovery. The set of process equipment includes a first multi-stage distillation column and a second multi-stage distillation column. The first multi-stage distillation column receives a flare gas inlet stream and produces a first overhead stream and a first bottoms stream. The second multi-stage distillation column receives the first bottoms stream and produces a second overhead stream and a second bottoms stream. The second bottoms stream comprises C4+ hydrocarbons, and the first multi-stage distillation column and the second multi-stage distillation column are the only two multi-stage distillation columns in the set of process equipment.
In yet another aspect, the disclosure includes a set of process equipment comprising a first column, a second column, an expander, and a compressor. The first column receives a C1-C8 hydrocarbon stream and produces a C1-C2 hydrocarbon stream and a C3-C8 hydrocarbon stream. The second column receives the C3-C8 hydrocarbon stream and produces a C3 hydrocarbon stream and a C4-C8 hydrocarbon stream. The expander expands the C1-C2 hydrocarbon stream to generate energy, and the compressor compresses the C1-C8 hydrocarbon stream using the energy generated by the expander before the C1-C8 hydrocarbon stream is fed to the first column.
These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims.
For a more complete understanding of the disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.
It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.
Disclosed herein is a flare recovery process that recovers at least a portion of flare gas that would otherwise be combusted in a flare. In one embodiment, flare gas is separated into a C4+ hydrocarbon stream and a C1-C3 hydrocarbon stream. The C4+ hydrocarbon stream is combined with crude oil to increase the production of crude oil, and the C1-C3 hydrocarbon stream is used to generate energy or is flared. In another embodiment, the flare gas is separated into a C4+ hydrocarbon stream, a C3 hydrocarbon stream, and a C1-C2 hydrocarbon stream. The C4+ hydrocarbon stream is combined with crude oil, the C3 hydrocarbon stream is transported away by pipe, truck, or rail as saleable product, and the C1-C2 hydrocarbon stream is used to generate energy or is flared. The process reduces carbon emissions because a portion of the flare gas, which would normally be burned and produce carbon dioxide, is used to increase the production of crude oil and optionally to recover a C3 hydrocarbon stream. Specifically, one embodiment of the flare recovery process without C3 hydrocarbon recovery reduces carbon emissions by 27.80 mole %, and another embodiment of the flare recovery process with C3 hydrocarbon recovery reduces carbon emissions by 36.58 mole %, both in comparison to flaring the gas fed to the disclosed process. Furthermore, it should be noted that addition of the C4+ hydrocarbon stream to the crude oil does not cause the crude oil to fail any specifications (e.g., specifications for energy content, vapor pressure, etc.). This is accomplished in part by using two multistage separation columns to remove the C3 hydrocarbon from the C4+ hydrocarbons, where the C3 hydrocarbons would cause the crude oil to fail specifications. Additionally, certain embodiments may provide other benefits such as not requiring any refrigeration, only requiring two columns (e.g., only requiring two multistage separation columns), operating at relatively low pressures (e.g., 200-500 pounds per a square inch gauge (psi)), and having a post separation expansion process that generates energy. These and other features and benefits are described in greater detail below.
The recovery column 120 is illustratively a distillation column, but can include alternative columns such as scrubbers, strippers, absorbers, adsorbers, packed columns, or a combination of column types. Such columns may employ weirs, downspouts, internal baffles, temperature control elements, and/or pressure control elements. Such columns also may employ some combination of reflux condensers and/or reboilers, including intermediate stage condensers and reboilers. The recovery column 120 generates an overhead recovery column stream 122 and a bottoms recovery column stream 124. The overhead recovery column stream 122 may comprise C1-C3 hydrocarbons, and the bottoms recovery column stream 124 may comprise C3-C8 hydrocarbons.
The bottoms recovery column stream 124 is fed to a separation column 126. Like the recovery column 120, the separation column 126 may also be a distillation column, a scrubber, a stripper, an absorber, an adsorber, a packed column, or a combination of column types. The separation column 126 generates an overhead separation column stream 128 and a bottoms separation column stream 130. The overhead separation column stream 128 may comprise C3 hydrocarbons, and the bottoms separation column stream 130 may comprise C4+ hydrocarbons (e.g., C4-C8 hydrocarbons). The bottoms separation column stream 130 is then optionally combined with the heavy hydrocarbon stream 110 in a mixer 132 to increase the amount of crude oil 134 produced. The mixer 132 may be a dynamic mixer, which contains moving parts to mix the constituent streams, or a static mixer, which may include internal baffles or may simply be a junction that combines the two constituent streams. It should be noted that the bottoms separation column stream 130 can be mixed with the heavy hydrocarbon stream 110 without causing the resulting crude oil 134 to fail any needed specifications such as, but not limited to, vapor pressure or energy content requirements.
Returning to the recovery column 120, the overhead recovery column stream 122 is fed to an expander 136. The expander 136 expands the overhead recovery column stream 122 to produce a cooled stream 138 that is at a lower pressure. The expansion optionally generates an energy stream 140 that can be used in other parts of the system 100. For instance, the energy stream 140 may be used to power the compressor 112. Then, the cooled stream 138 is mixed with the overhead separation column stream 128 in a mixer 142 to produce a residue stream 144. The mixer may be similar to mixer 132. The residue stream 144 may comprise C1-C3 hydrocarbons and may be used for energy recovery in an energy recovery unit 146. For instance, the residue stream 144 can be combusted in the energy recovery unit 146 to generate energy for the compressor 112 (e.g. residue stream 144 fay be a fuel for the compressor 112), the dryer 116 (e.g. for the regeneration gas heater for the molecular sieve unit), or the reboilers for columns 120 and 126. Finally, any remaining gas 148 from the energy recovery unit 146 may be flared in flare 150 as needed.
In system 200, components 202, 204, 206, 208, 210, 212, 214, 216, 218, 220, 222, 224, 226, 228, 230, 232, 234, 238, 246, 248, and 250 are the same as or are similar to components 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, 130, 132, 134, 138, 146, 148, and 150 in system 100 and need not be described again. System 200 differs from system 100 in that the overhead separation column stream 228 containing C3 hydrocarbons is not mixed with the cooled stream 238. Instead, the overhead separation column stream 228 (i.e., the C3 hydrocarbon stream) is recovered by itself. The overhead separation column stream 228 is then used for energy recovery and/or is used as a saleable product and is transported away by truck, rail, pipeline, or by any other means. Additionally, the system 200 may optionally include a hydrogen sulfide removal unit 296 to remove hydrogen sulfide if necessary. For instance, the system 200 may use iron sponge, sulfanol, or iron chelate processing to remove hydrogen sulfide. The hydrogen sulfide removal unit 296 generates a sweetened propane product stream 298.
The first compressed stream 306 is fed to a second compressor 308 to generate a second compressed stream 310. The second compressor 308 may include any of the types of compressors listed for first compressor 304. Additionally, a second compressor energy stream 312 is supplied to the second compressor 308 to power the second compressor 308.
The second compressed stream 310 is fed to a first cooler 314 (e.g., an air cooler) that generates a first cooled stream 316. The first cooled stream 316 may then optionally be processed through a dehydrator 318 (e.g., a molecular sieve, etc.) to remove any water from the stream if needed. Following the first cooler 314 and/or the dehydrator 318, the first cooled stream 316 is processed through a first heat exchanger 320 to produce a cooled recovery column inlet stream 322. The recovery column inlet stream 322 is fed to a recovery column 324. Recovery column 324 may include any of the types of columns listed for recovery column 104 in
The recovery column 324 generates a recovery column overhead stream 330 and a recovery column bottoms stream 332. The recovery column overhead stream 330 may comprise C1-C2 hydrocarbons, C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, the recovery column overhead stream 330 may comprise about 80-about 90 mole % C1-C2 hydrocarbons, about 10-about 20 mole % C3 hydrocarbons, about 0-about 2 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 2 mole % nitrogen. The recovery column bottoms stream 332 may comprise small amounts of C1-C2 hydrocarbons, C3-C8 hydrocarbons, trace amounts of carbon dioxide, and no nitrogen. For instance, the recovery column bottoms stream 332 may comprise about 5-about 15 mole % C1-C2 hydrocarbons, about 85-about 95 mole % C3-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and 0 mole % nitrogen. However, the precise compositions of streams 330 and 332 may vary, and they may contain other components in various amounts.
The recovery column bottoms stream 332 is then cooled through a second cooler 334 (e.g., an air cooler) to produce a separation column inlet stream 336. The separation column inlet stream 336 is fed to the separation column 338. Separation column 338 may include any of the types of columns listed for recovery column 120 in
Separation column 338 generates an overhead separation column stream 348 and a bottoms separation column stream 350. The overhead separation column stream 348 may comprise C1-C2 hydrocarbons, C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, and trace amounts of carbon dioxide. For instance, the overhead separation column stream 348 may comprise about 30-about 40 mole % C1-C2 hydrocarbons, about 60-about 70 mole % C3 hydrocarbons, about 0-about 2 mole % C4-C8 hydrocarbons, and about 0-about 2 mole % carbon dioxide. The bottoms separation column stream 350 may comprise no C1-C2 hydrocarbons, trace amounts of C3 hydrocarbons, C4+ hydrocarbons (e.g., C4-C8 hydrocarbons), and no carbon dioxide. For instance, the bottoms separation column stream 350 may comprise about 0 mole % C1-C2 hydrocarbons, about 0-about 2 mole % C3 hydrocarbons, about 98-about 100 mole % C4+ hydrocarbons, and about 0 mole % carbon dioxide. The bottoms separation column stream 350 may then be combined with crude oil (e.g., C9− hydrocarbons) to increase the amount of oil produced, and the overhead separation column stream 348 is fed to a mixer 352.
Returning to the recovery column 324, the recovery column overhead stream 330 is cooled through second heat exchanger 354 to produce a separator inlet stream 356 that is fed to a reflux separator 358. Reflux separator 358 may be a phase separator, which is a vessel that separates an inlet stream into a substantially vapor stream and a substantially liquid stream, such as a knock-out drum, flash drum, reboiler, condenser, or other heat exchanger. Such vessels also may have some internal baffles, temperature control elements, and/or pressure control elements, but generally lack any trays or other type of complex internal structure commonly found in columns.
Reflux separator 358 produces a reflux separator bottoms stream 360 and a reflux separator overhead stream 366. Reflux separator bottoms stream 360 comprises C1 hydrocarbons, C2-C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, reflux separator bottoms stream 360 may comprise about 20-about 30 mole % C1 hydrocarbons, about 70-about 80 mole % C2-C3 hydrocarbons, about 0-about 1 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 1 mole % nitrogen. Reflux separator overhead stream 366 comprises C1 hydrocarbons, C2-C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, reflux separator overhead stream 366 may comprise about 80-about 90 mole % C1 hydrocarbons, about 10-about 20 mole % C2-C3 hydrocarbons, about 0-about 1 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 5 mole % nitrogen. Reflux separator bottom stream 360 is processed through a reflux pump 362 to produce a recovery column reflux stream 364 that is fed back to the recovery column 324. Reflux pump 362 receives energy through a reflux pump energy stream 363.
Reflux separator overhead stream 366 is then fed to an expander 368. Expander 368 may be an expansion turbine, which reduces the temperature and/or pressure of expander outlet stream 372 and produces an expander energy stream 370 (e.g. mechanical or electrical energy). The expander 368 may be coupled to the first compressor 304 such that the expander energy stream 370 created by the expansion process is used to run the first compressor 304.
From the expander 368, the expander outlet stream 372 is passed through the second heat exchanger 354 to cool the recovery column overhead stream 330 and to produce a heated expander outlet stream 374. Heated expander outlet stream 374 is then combined with overhead separation column stream 348 in mixer 352 to produce a mixer outlet stream 376. Mixer outlet stream 376 comprises C1 hydrocarbons, C2-C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, mixer outlet stream 376 may comprise about 75-about 85 mole % C1 hydrocarbons, about 10-about 20 mole % C2-C3 hydrocarbons, about 0-about 1 mole % C4-C8 hydrocarbons, about 0-about 1 mole % carbon dioxide, and about 0-about 5 mole % nitrogen. Mixer outlet stream 376 is passed through first heat exchanger 320 to cool the first cooled stream 316 and to produce a cold residue stream 378. The cold residue stream 378 may be used to generate energy and/or the cold residue stream 378 may be combusted as flare gas. It should be noted that no compressors are included in system 300 after the mixer 352 to increase the pressure and/or the temperature of the cold residue stream 378 as may be required in other systems.
The first compressed stream 406 is fed to a second compressor 408 to generate a second compressed stream 410. The second compressor 408 may include any of the types of compressors listed for first compressor 404. Additionally, a second compressor energy stream 412 is supplied to the second compressor 408 to power the second compressor 408.
The second compressed stream 410 is fed to a first cooler 414 (e.g., an air cooler) that generates a first cooled stream 416. The first cooled stream 416 may then optionally be processed through a dehydrator 418 (e.g., a molecular sieve, etc.) to remove any water from the stream if needed. Following the first cooler 414 and/or the dehydrator 418, the first cooled stream 416 is processed through a first heat exchanger 420 to produce a cooled recovery column inlet stream 422. The recovery column inlet stream 422 is fed to a recovery column 424. Recovery column 424 may include any of the types of columns listed for recovery column 120 in
The recovery column 424 generates a recovery column overhead stream 430 and a recovery column bottoms stream 432. The recovery column overhead stream 430 may comprise C1-C2 hydrocarbons, C3 hydrocarbons, trace amounts of carbon dioxide, trace amounts of nitrogen, and no C4-C8 hydrocarbons. For instance, the recovery column overhead stream 430 may comprise about 80-about 90 mole % C1-C2 hydrocarbons, about 10-about 20 mole % C3 hydrocarbons, about 0-about 2 mole % carbon dioxide, about 0-about 2 mole % nitrogen, and about 0 mole % C4-C8 hydrocarbons. The recovery column bottoms stream 432 may comprise C3-C8 hydrocarbons, trace amounts of C1-C2 hydrocarbons, no carbon dioxide, and no nitrogen. For instance, the recovery column bottoms stream 432 may comprise about 90-about 100 mole % C3-C8 hydrocarbons, about 0-about 10 mole % C1-C2 hydrocarbons, about 0 mole % carbon dioxide, and about 0 mole % nitrogen. However, the precise compositions of streams 430 and 432 may vary, and they may contain other components in various amounts.
The recovery column bottoms stream 432 is then cooled through a second cooler 434 (e.g., an air cooler) to produce a separation column inlet stream 436. The separation column inlet stream 436 is fed to the separation column 438. Separation column 438 may include any of the types of columns listed for recovery column 120 in
Separation column 438 generates a vapor stream 447, a propane product stream 448, and a bottoms separation column stream 450. The vapor stream 447 may comprise C1-C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and no nitrogen. For instance, the vapor stream 447 may comprise about 90-about 100 mole % C1-C3 hydrocarbons, about 0-about 10 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0 mole % nitrogen. The propane product stream 448 may comprise small amounts of C1-C2 hydrocarbons, C3 hydrocarbons, small amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and no nitrogen. For instance, the propane product stream 448 may comprise about 10-about 20 mole % C1-C2 hydrocarbons, about 70-about 90 mole % C3 hydrocarbons, about 0-about 10 mole % C4-C8 hydrocarbons, about 0-about 1 mole % carbon dioxide, and about 0 mole % nitrogen. The bottoms separation column stream 450 may comprise trace amounts of C1-C3 hydrocarbons, C4+ hydrocarbons (e.g., C4-C8 hydrocarbons), no carbon dioxide, and no nitrogen. For instance, the bottoms separation column stream 450 may comprise about 0-about 5 mole % C1-C3 hydrocarbons, about 95-about 100 mole % C4+ hydrocarbons, about 0 mole % carbon dioxide, and about 0 mole % nitrogen. The bottoms separation column stream 450 may then be combined with crude oil to increase the amount of oil produced, and the propane product stream 448 may be recovered as saleable C3 product. Additionally, the system 400 may optionally include a hydrogen sulfide removal unit 496 to remove hydrogen sulfide if necessary. For instance, the system 400 may use iron sponge, sulfanol, or iron chelate processing to remove hydrogen sulfide. The hydrogen sulfide removal unit 496 generates a sweetened propane product stream 498.
Returning to the recovery column 424, the recovery column overhead stream 430 is cooled through second heat exchanger 454 to produce a separator inlet stream 456 that is fed to a reflux separator 458. Reflux separator 458 may be a phase separator, which is a vessel that separates an inlet stream into a substantially vapor stream and a substantially liquid stream, such as a knock-out drum, flash drum, reboiler, condenser, or other heat exchanger. Such vessels also may have some internal baffles, temperature control elements, and/or pressure control elements, but generally lack any trays or other type of complex internal structure commonly found in columns.
Reflux separator 458 produces a reflux separator bottoms stream 460 and a reflux separator overhead stream 466. The reflux separator bottoms stream 460 comprises C1 hydrocarbons, C2-C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, the reflux separator bottoms stream 460 may comprise about 25-about 35 mole % C1 hydrocarbons, about 65-about 75 mole % C3 hydrocarbons, about 0-about 2 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 2 mole % nitrogen. The reflux separator overhead stream 466 comprises C1 hydrocarbons, C2-C3 hydrocarbons, about 0 mole % C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, the reflux separator overhead stream may comprise about 80-about 90 mole % C1 hydrocarbons, about 10-about 20 mole % C2-C3 hydrocarbons, about 0 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 2 mole % nitrogen. The reflux separator bottom stream 460 is processed through a reflux pump 462 to produce a recovery column reflux stream 464 that is fed back to the recovery column 424. Reflux pump 462 receives energy through a reflux pump energy stream 463.
Reflux separator overhead stream 466 is then fed to an expander 468. Expander 468 may be an expansion turbine, which reduces the temperature and/or pressure of expander outlet stream 472 and produces an expander energy stream 470 (e.g. mechanical or electrical energy). The expander 468 may be coupled to the first compressor 404 such that the expander energy stream 470 created by the expansion process is used to run the first compressor 404.
From the expander 468, the expander outlet stream 472 is passed through the second heat exchanger 454 to cool the recovery column overhead stream 430 and to produce a heated expander outlet stream 474. Heated expander outlet stream 474 is then passed through first heat exchanger 420 to cool the first cooled stream 416 and to produce a cold residue stream 478. The cold residue stream 478 may be used to generate energy and/or the cold residue stream 478 may be combusted as flare gas. It should be noted that no compressors are included in system 400 after the reflux separator 458 to increase the pressure and/or the temperature of the cold residue stream 478 as may be required in other systems.
The system 500 begins with an inlet stream 502 being fed to a first compressor 504. The inlet stream 502 may comprise C1-C8 hydrocarbons, carbon dioxide, nitrogen, water, and other components included in flare gas. For instance, the inlet stream 502 may comprise about 96-about 100 mole % C1-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 2 mole % nitrogen. The first compressor 504 increases the pressure of the inlet stream 502 to generate a first compressed stream 506. The first compressor 504, as well as any of the other compressors in system 500, may include compressors and/or pumps, which may be driven by electrical, mechanical, hydraulic, or pneumatic means. Specific examples of a first compressor 504 include centrifugal, axial, positive displacement, turbine, rotary, and reciprocating compressors and pumps. Additionally, a first compressor energy stream 508 is supplied to the first compressor 504 to power the first compressor 504.
The first compressed stream 506 is fed to a second compressor 510. The second compressor 510 generates a second compressed stream 512 and is supplied with a second compressor energy stream 514. The second compressed stream 512 is fed to a first cooler 516 that generates a first cooled stream 518. The first cooler 516, as well as any of the other coolers in system 500, may comprise a cooler such as an air cooler or may comprise any other type of heat exchanger.
The first cooled stream 518 is fed to a first separator 520. In one embodiment, the first separator 520, as well as other separators in system 500, comprise a two-phase scrubber. However, embodiments of separators in system 500 are not limited to any particular kind of separator and can include any separator such as, but not limited to, a phase separator, a knock-out drum, a flash drum, a reboiler, a condenser, or a heat exchanger. The first separator 520 generates a first separator top stream 522.
The first separator top stream 522 is fed to a third compressor 524. The third compressor 524 generates a third compressed stream 526 and is supplied with a third compressor energy stream 528. The third compressed stream 526 is fed to a second cooler 530 that generates a second cooled stream 532. The second cooled stream 532 is fed to a second separator 534. The second separator 534 generates a second separator top stream 536 and a second separator bottom stream 538.
The second separator top stream 536 is fed to a fourth compressor 540. The fourth compressor 540 generates a fourth compressed stream 542 and is supplied with a fourth compressor energy stream 544. The fourth compressed stream 542 is fed to a third cooler 546 that generates a third cooled stream 548. The third cooled stream 548 is fed to a third separator 550 that generates a third separator top stream 552 and a third separator bottom stream 554. The third separator top stream 552 is cooled through a first heat exchanger 555 to generate a cooled recovery column inlet stream 556 that is fed to the recovery column 558. Returning to the second separator bottom stream 538, the second separator bottom stream 538 is transferred from the second separator 534 by a material transfer device 560 such as, but not limited to, a pump. The material transfer device 560 receives a material transfer device energy stream 562 and generates a material transfer device stream 564. The material transfer device stream 564 and the third separator bottom stream 554 are mixed together in a mixer 566 to generate a mixed recovery column inlet stream 568 that is fed to the recovery column 558.
The recovery column 558 may include any of the types of columns listed for recovery column 120 in
The recovery column 558 generates a recovery column overhead stream 574 and a recovery column bottoms stream 576. The recovery column overhead stream 574 may comprise C1-C2 hydrocarbons, C3 hydrocarbons, trace amounts of carbon dioxide, trace amounts of nitrogen, and no C4-C8 hydrocarbons. For instance, the recovery column overhead stream 574 may comprise about 75-about 85 mole % C1-C2 hydrocarbons, about 15-about 25 mole % C3 hydrocarbons, about 0-about 3 mole % carbon dioxide, about 0-about 1 mole % nitrogen, and about 0-about 1 mole % C4-C8 hydrocarbons. The recovery column bottoms stream 576 may comprise C3-C8 hydrocarbons, trace amounts of C1-C2 hydrocarbons, no carbon dioxide, and no nitrogen. For instance, the recovery column bottoms stream 576 may comprise about 90-about 100 mole % C3-C8 hydrocarbons, about 0-about 10 mole % C1-C2 hydrocarbons, about 0 mole % carbon dioxide, and about 0 mole % nitrogen. However, the precise compositions of streams 574 and 576 may vary, and they may contain other components in various amounts.
The recovery column bottoms stream 576 is then cooled through a fourth cooler 578 (e.g., an air cooler) to produce a separation column inlet stream 580. The separation column inlet stream 580 is fed to the separation column 582. The separation column 582 may include any of the types of columns listed for recovery column 120 in
The separation column 582 generates a propane product stream 592 and a bottoms separation column stream 594. The propane product stream 592 may comprise small amounts of C1-C2 hydrocarbons, C3 hydrocarbons, small amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and no nitrogen. For instance, the propane product stream 592 may comprise about 10-about 20 mole % C1-C2 hydrocarbons, about 70-about 90 mole % C3 hydrocarbons, about 0-about 10 mole % C4-C8 hydrocarbons, about 0-about 1 mole % carbon dioxide, and about 0 mole % nitrogen. The bottoms separation column stream 594 may comprise trace amounts of C1-C3 hydrocarbons, C4+ hydrocarbons (e.g., C4-C8 hydrocarbons), no carbon dioxide, and no nitrogen. For instance, the bottoms separation column stream 594 may comprise about 0-about 5 mole % C1-C3 hydrocarbons, about 95-about 100 mole % C4+ hydrocarbons, about 0 mole % carbon dioxide, and about 0 mole % nitrogen. The bottoms separation column stream 594 may then be combined with crude oil to increase the amount of oil produced, and the propane product stream 592 may be recovered as saleable C3 product. Additionally, the system 500 may optionally include a hydrogen sulfide removal unit 596 to remove hydrogen sulfide if necessary. For instance, the system 500 may use iron sponge, sulfanol, or iron chelate processing to remove hydrogen sulfide. The hydrogen sulfide removal unit 596 generates a sweetened propane product stream 598.
Returning to the recovery column 558, the recovery column overhead stream 574 is cooled through a second heat exchanger 600 to produce a separator inlet stream 602 that is fed to a reflux separator 604. The reflux separator 604 may be a phase separator, which is a vessel that separates an inlet stream into a substantially vapor stream and a substantially liquid stream, such as a knock-out drum, flash drum, reboiler, condenser, or other heat exchanger. Such vessels also may have some internal baffles, temperature control elements, and/or pressure control elements, but generally lack any trays or other type of complex internal structure commonly found in columns.
The reflux separator 604 produces a reflux separator bottoms stream 606 and a reflux separator overhead stream 608. The reflux separator bottoms stream 606 comprises C1 hydrocarbons, C2-C3 hydrocarbons, trace amounts of C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, the reflux separator bottoms stream 606 may comprise about 15-about 20 mole % C1 hydrocarbons, about 75-about 80 mole % C2-C3 hydrocarbons, about 3-about 5 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 2 mole % nitrogen. The reflux separator overhead stream 608 comprises C1 hydrocarbons, C2-C3 hydrocarbons, about 0 mole % C4-C8 hydrocarbons, trace amounts of carbon dioxide, and trace amounts of nitrogen. For instance, the reflux separator overhead stream may comprise about 60-about 70 mole % C1 hydrocarbons, about 30-about 40 mole % C2-C3 hydrocarbons, about 0 mole % C4-C8 hydrocarbons, about 0-about 2 mole % carbon dioxide, and about 0-about 2 mole % nitrogen. The reflux separator bottom stream 606 is processed through a reflux pump 610 to produce a recovery column reflux stream 612 that is fed back to the recovery column 558. The reflux pump 610 receives energy through a reflux pump energy stream 614.
The reflux separator overhead stream 608 is then fed to an expander 615. The expander 615 may be an expansion turbine, which reduces the temperature and/or pressure of expander outlet stream 616 and produces an expander energy stream 618 (e.g. mechanical or electrical energy). The expander 615 may be coupled to the first compressor 504 such that the expander energy stream 618 created by the expansion process is used to run the first compressor 504.
From the expander 615, the expander outlet stream 616 is passed through the second heat exchanger 600 to cool the recovery column overhead stream 574 and to produce a heated expander outlet stream 620. The heated expander outlet stream 620 is then passed through first heat exchanger 555 to cool the third separator top stream 552 and to produce a cold residue stream 622. The cold residue stream 622 may be used to generate energy and/or the cold residue stream 622 may be combusted as flare gas. It should be noted that no compressors are included in system 500 after the reflux separator 604 to increase the pressure and/or the temperature of the cold residue stream 622 as may be required in other systems.
Furthermore, it should be noted that the systems 100, 200, 300, 400, and 500 shown in
In one example, a process simulation was performed using the flare recovery system 300 shown in
In another example, a process simulation was performed using the flare recovery system 400 shown in
In another example, a process simulation was performed using the flare recovery system 500 shown in
In another example, calculations were performed to determine the carbon reduction for a flare recovery process without C3 recovery and with C3 recovery. Table 10 shows the composition of a 10 MMSCFD inlet flow stream used for the calculations. Table 11 shows the composition of a resulting 9.1 MMSCFD residue flow stream without C3 recovery, and Table 12 shows the composition of a resulting 8.55 MMSCFD residue flow stream with C3 recovery. Based on the calculations, it was determined that the flare recovery process without C3 recovery reduces carbon emissions by about 27.80 mole %. The flare recovery process with C3 recovery reduces carbon emissions by about 36.58 mole %. Both processes recovery 750 barrels per a day of C4+ hydrocarbons that are blended with crude oil. Additionally, the flare recovery process with C3 recovery recovers about 54 mole % of the C3 hydrocarbons and produces 240 barrels per a day of C3 hydrocarbons.
In another example, actual inlet stream compositions for a flare recovery process were determined. Table 13 shows the composition of four different inlet streams that can be used in a flare recovery process.
At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from 1 to 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R1, and an upper limit, Ru, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R1+k*(Ru−R1), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, e.g., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. The use of the term “about” means ±10% of the subsequent number, with the exception that about 0% means ≤0.1%. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. The discussion of a reference in the disclosure is not an admission that it is prior art, especially any reference that has a publication date after the priority date of this application. The disclosure of all patents, patent applications, and publications cited in the disclosure are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to the disclosure.
While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.
In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/021022 | 3/4/2016 | WO | 00 |
