Hydrocarbon distillation
11585597 · 2023-02-21
Assignee
Inventors
Cpc classification
F25J2200/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0284
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0296
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0235
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J3/0233
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0238
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/023
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J2220/64
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J3/0209
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J2230/04
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J2200/40
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0052
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0242
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0212
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J1/0022
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J3/0247
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
F25J1/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
F25J3/02
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Abstract
Systems and methods are provided for increasing the efficiency of liquefied natural gas production and heavy hydrocarbon distillation. Air within an LNG production facility can be utilized as a heat source to provide heat to HHC liquid for distillation in a HHC distillation system. The mechanism of heat transfer from the air can be natural convection. Heat provided by natural gas, or compressed natural gas, can be also used for HHC distillation. Various other liquids can further be used to transfer heat to HHC liquid for distillation.
Claims
1. A system for producing liquefied natural gas (LNG) and electrical power, comprising: a LNG production facility configured to receive a natural gas feedstock and to form liquefied natural gas from the natural gas feedstock, wherein the LNG production facility receives electrical power from an external power source; and a power generation facility configured to create electrical power using the natural gas feedstock or an additional fuel source and to provide a first portion of the electrical power to the LNG production facility, wherein waste heat generated at the power generation facility is provided to the LNG production facility, the waste heat captured within natural gas by heating the natural gas prior to the natural gas being provided to the LNG production facility, and wherein the waste heat, captured within the natural gas, is used as a heat source to remove heavy hydrocarbon components from the natural gas feedstock in a heavy hydrocarbon component distillation system configured within the LNG production facility.
2. The system of claim 1, wherein the external power source includes one of a local power grid and a battery bank.
3. The system of claim 1, wherein the additional fuel source includes a fuel vapor received from the LNG production facility, the fuel vapor collected while reducing a pressure of the liquefied natural gas within the LNG production facility.
4. The system of claim 1, wherein the additional fuel source includes one of petroleum fuel, diesel fuel, propane, and kerosene.
5. The system of claim 1, wherein the power generation facility is further configured to provide a second portion of the electrical power for storage in batteries or to a local power grid.
6. The system of claim 1, where in the waste heat is used in a reboiler of an acid gas removal system or a dehydration dryer system.
7. The system of claim 6, wherein the acid gas removal system removes carbon dioxide and hydrogen sulfide from the natural gas feedstock.
8. The system of claim 6, wherein the dehydration dryer system removes water from the natural gas feedstock.
9. The system of claim 1, wherein the heavy hydrocarbon distillation system includes a first heat exchanger coupled to a distillation column containing the natural gas feedstock, the first heat exchanger configured to receive a fluid and to transfer heat from the fluid to the natural gas feedstock, such that the natural gas feedstock boils to form a vapor containing heavy hydrocarbon components.
10. The system of claim 9, wherein the hydrocarbon distillation system is further configured to extract heat from the vapor such that desired heavy hydrocarbons condense to form a distilled heavy hydrocarbon liquid.
11. The system of claim 9, wherein the fluid is ambient air.
12. The system of claim 11, wherein the heat is transferred from the air via natural convection.
13. The system of claim 11, wherein the heat is transferred from the air via forced convection.
14. The system of claim 11, wherein the heat is transferred from air in the LNG production facility to the fluid via a second heat exchanger that is thermally coupled to the first heat exchanger.
15. The system of claim 10, wherein the heat is transferred from the NG feedstock to the fluid via a second heat exchanger that is thermally coupled to the first heat exchanger.
16. The system of claim 10, wherein the heat is transferred from a refrigerant to the fluid, the refrigerant having received heat from the NG feedstock.
17. The system of claim 10, wherein a refrigerant is heated during compression and the heat is transferred from the refrigerant to the fluid after compression.
Description
DESCRIPTION OF DRAWINGS
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DETAILED DESCRIPTION
(8) Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the systems, devices, and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems, devices, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. Further, in the present disclosure, like-named components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-named component is not necessarily fully elaborated upon.
(9) Natural gas can often contain heavy hydrocarbon (HHC) components such as, butanes, pentanes, hexanes, benzene, toluene, ethylbenzene, and xylenes. In order to prevent HHCs from freezing during the production of LNG, a liquid containing at least a portion of the HHCs (HHC liquid) can be removed from the natural gas. The HHC liquid can be distilled, for example to produce essentially pure components, fuels, liquefied petroleum gas (LPG) or natural gas liquids (NGLs). Current practices for distilling HHC liquid use oil or steam to provide heat to the distillation system. While oil or steam can be effective, the use of current heat sources present in an LNG production system can be less costly and more efficient. In certain exemplary embodiments, a natural gas feedstock, a refrigerant, and/or air present in an LNG production system can be utilized to heat a distillation system.
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(11) NG feedstock 114 can often contain heavy hydrocarbon components (HHCs) such as butanes, pentanes, hexanes, benzene, toluene, ethylbenzene, and xylenes. It can be desirable to remove HHCs during production to prevent them from freezing at typical LNG production temperatures. As illustrated in
(12) Separation and/or purification of heavy hydrocarbon components can be achieved through flash separation and/or distillation. For example, in some cases, the HHC liquid can be put through a multistage distillation process to separate it into its constituent components (distilled HHC liquid). As a result, essentially pure components, fuels, liquefied petroleum gas (LPG) or natural gas liquids (NGLs), and/or other hydrocarbon components can be coproduced with LNG.
(13) A HHC distillation column can include a reboiler, and may include one or more condensers to selectively condense heavy hydrocarbon components. An exemplary HHC distillation column can operate at temperatures between about −150° F. and about 0° F., and at pressures between about 100 psia and about 1000 psia. In certain exemplary embodiments, the HHC distillation column can operate at temperatures between about −120° F. and about −50° F., and at pressures between about 400 psia and about 800 psia.
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(15) The heating system 206 can be used to provide heat to a number of systems and devices that can be used in an LNG production facility. For example, the heating system can provide heat to an amine system stripper reboiler, temperature swing adsorption drier beds for dehydration (for regeneration), as well as the HHC distillation reboiler 204 and other systems and devices. Depending on the configuration of a given LNG production facility, it can be desirable to implement a multipurpose heating system that can provide heat to multiple systems and devices within the LNG production facility. However, in some situations it can be desirable to implement purpose-specific heating systems. Purpose-specific heating systems can reduce capital cost and operating cost of the LNG production facility, simplify the design of the facility, reduce environmental emissions, and/or increase the energy efficiency of the facility.
(16) As described above, an exemplary HHC distillation column can operate at temperatures between about −120° F. and about −50° F. Therefore, in one embodiment ambient air within an LNG production facility can be used as a heat source for a HHC distillation processes.
(17) Heat can be transferred from the air to the refrigerant via the heat exchanger 306, where the mechanism of heat transfer from the air can be natural convection. As heat is transferred to the refrigerant, the temperature of the refrigerant can increase, and at least a portion of the refrigerant can boil to form a vapor. The vapor can travel to the reboiler 304 via the riser 310, where it can transfer heat sufficient to boil a portion of the HHC liquid to form HHC vapor which can rise through distillation column. As the HHC vapor rises, it can be condensed and separated as described with regard to distillation system 200. As the refrigerant travels through the reboiler 304 it can cool and condense, and the condensed refrigerant liquid can travel back to the heat exchanger 306 via the downcomer 308. In certain aspects, the rate of heat transfer to the reboiler 304 can be controlled by a control valve on the downcomer 308 and/or on the riser 310. For example, the control valve can be used to control one or more temperatures and pressures within the distillation system 300.
(18) In the distillation system 300 shown in
(19) The distillation systems 300, 400 illustrated in
(20) The distillation systems 300, 400 shown in
(21) In another embodiment, rather than using a heat exchanger such as heat exchangers 306, 406 described above, a forced convection boiler arrangement can be implemented to provide heat to HHC liquid within a distillation column.
(22) In another embodiment, NG feedstock can be used as a heat source for HHC distillation. For example, rather than air, NG feedstock can be used as a heat source in a distillation system that can generally be similar to distillation systems 300, 400, 500 illustrated in
(23) Typically, during LNG production, NG feedstock can be compressed prior to being converted to LNG. The compression process can increase the temperature of the NG feed stock to about 149° C. (about 300 F°). During or after compression, the compressed NG feedstock can be passed through intercoolers or aftercoolers to cool the NG feedstock prior to delivering it to a liquefaction system (see
(24) The increased temperature of compressed NG feedstock means that it can be suitable to provide heat for other applications that require higher heating temperatures. For example, compressed NG feedstock can provide heat to an amine system stripper reboiler, temperature swing adsorption drier beds for dehydration (for regeneration), water distillation systems, as well as a HHC distillation systems.
(25) In another embodiment, refrigerant that flows through an LNG liquefaction system can be used as a heat source within a HHC distillation system.
(26) As described above, NG feedstock 614 can often contain heavy hydrocarbon components (HHCs), and it can be desirable to remove HHCs during liquefaction to prevent them from freezing at typical LNG production temperatures. As illustrated in
(27) The HHC distillation system 622 can generally be similar to the distillation facilities 300, 400, 500 described with regard to
(28) Alternatively, the MR can be directly delivered to the HHC distillation system 622 prior to being delivered to the compression system 606. The utilization of the MR as a heat source can increase the efficiency of the compression process since the MR will be pre-cool prior to entering the compression system 606. Additionally, the load on the intercoolers, condensers, aftercoolers, or other heat exchangers, can be reduced, thereby allowing for smaller components to be used. As describe above, the compression system 606 can be, e.g., a multistage compression system having multiple compressors, where condensers, intercools, or air coolers can be located between stages of the compressors of the compression system 606. Rather than delivering the MR to the HHC distillation system 622 prior to compression, the MR can be delivered to the distillation system 622 between stages of compression. For example, the MR can travel through a first compressor, and can then be delivered to a distillation system to be used as a heat source for HHC distillation. The MR can then be delivered to a second compressor, and can continue through the system. In another embodiment, the MR can be delivered to a HHC distillation system once compression has been completed. Such configurations can reduce or eliminate the need for condensers, intercoolers, or aftercoolers that facilitate condensation of the compressed MR during or after compression.
(29) Although the examples provided in
(30) Other fluids within an LNG production facility can also be used to provide heat for HHC distillation. For example, heat that can be produced during generation of electric power can be used for HHC distillation, as illustrated in
(31) The power generation facility 708 can use NG feedstock 702, fuel vapor 710, or other fuels 712, e.g., petrol, diesel, propane, or kerosene, to create electric power. For example, NG feedstock 202, fuel vapor 210, and other fuels 212, can be used as fuel in gas turbines such as simple cycle gas turbines (SCGT) and combined cycle gas turbines (CCGT), as well as steam boilers and steam turbines, to produce mechanical power. A portion of the mechanical power can be used to drive an electric generator to generate electric power. In the illustrated example, some electric power 714 that can be generated in the power generation facility 708 can be delivered to the LNG production facility 704 to supplement or replace the electric power 705 from the external source. Another quantity of electric power 706 can be, for example, stored in batteries, diverted to a local power grid, or consumed elsewhere. In some embodiments, NG feedstock 702 is the only fuel that is used for the production of LNG 706 and electric power 714, 716.
(32) During electric power generation, a significant amount of waste heat can be produced. As shown in
(33) The heat sources described herein for use within HHC distillation system can reduce environmental emissions by eliminating the need to fire fuel to provide heat to HHC liquid for distillation in a HHC distillation system. Although MR is used in the embodiments described herein, alternate refrigerants can be used within refrigeration systems and within the methods, systems, and devices described herein. Examples of alternate refrigerants include ammonia, propane, nitrogen, methane, ethane, ethylene, or other industrial gas or hydrocarbon based refrigerants.
(34) Exemplary technical effects of the methods, systems, and devices described herein include, by way of non-limiting example, the ability to increase the efficiency of HHC distillation, and simplify HHC distillation systems within LNG production facilities. Exemplary technical effects also include the ability to distill HHC liquid using air, natural gas, MR, or a heated fluid from a power generation facility, as a heat source. The aforementioned methods, systems, and devices, can function to increase the efficiency of HHC distillation and LNG production, simplify HHC distillation systems within an LNG production facility, and reduce environmental emissions associated with LNG production and HHC distillation.
(35) One skilled in the art will appreciate further features and advantages of the subject matter described herein based on the above-described embodiments. Accordingly, the present application is not to be limited specifically by what has been particularly shown and described.