Patent Application
20250044023
The present disclosure is directed to the field of natural gas processing, liquefaction, and storage.
Reference will now be made in detail to various exemplary implementations of the disclosure. It is to be understood that the following discussion of exemplary implementations is not intended to be limiting. Rather, the following discussion is provided to give the reader a more detailed understanding of certain aspects and features of the disclosure.
Embodiments of the invention include any of the following aspects, such as Aspect 1, which is a method for natural gas liquefaction, comprising: providing a clean gas stream 1 and a recirculation gas stream 28 at a first pressure; mixing the clean gas stream 1 and the recirculation gas stream 28 to form a mixed gas stream 1A; splitting the mixed gas stream 1A into at least a first stream 2 and a second stream 3; passing the first stream 2 through a heat exchanger 100; wherein the heat exchanger 100 cools the first stream 2 to form a first liquefied stream 4 by cross exchanging with one or more refrigeration streams, wherein the one or more refrigeration streams comprise: an expander refrigeration stream 11; a secondary refrigeration stream 15; and a tertiary refrigeration stream 34; and cooling the second stream 3 by passing it through the heat exchanger 100 to form a cooled gas stream 5; passing the cooled gas stream 5 through a turbo-expander 300 to form the expander refrigeration stream 11; passing the expander refrigeration stream 11 through the heat exchanger 100 to form a first refrigeration return gas stream 12; generating a first slipstream 14 from the first liquefied stream 4 and reducing pressure of the first slipstream 14 to form secondary refrigeration stream 15; passing the secondary refrigeration stream 15 through the heat exchanger 100 to form a second refrigeration return gas stream 16; combining the first refrigeration return gas stream 12 and the second return gas stream 16 to form a first combined stream 20; generating a second slipstream 32 from the first liquefied stream 4 and reducing pressure of the second slipstream 32 to form reduced-pressure slip stream 33; combining the reduced-pressure slipstream 33 with a boil off gas stream 31 from liquid natural gas storage 1500 to form the tertiary refrigeration stream 34; passing the tertiary refrigeration stream 34 through the heat exchanger 100 to form a tertiary refrigeration return gas stream 35; compressing the tertiary refrigeration return gas stream 35 using a first compressor 700 to form a compressed tertiary refrigeration return gas stream 36; combining the compressed tertiary refrigeration return gas stream 36 with the first combined stream 20 to form a second combined stream 21; compressing and optionally cooling the second combined stream 21 using one or more additional compressor(s) (e.g., 900, 1000, 1200, and/or 1900) and optionally one or more cooler(s) (1100 and/or 1150) to form the recirculation gas stream 28 at pressure Precycle; reducing pressure of the first liquefied stream 4 to form a two-phase product stream 8; and recycling the one or more refrigeration streams through the system until a desired cryogenic liquid storage temperature is reached.
Aspect 2 is the method of Aspect 1, wherein the clean gas stream 1 is free of or reduced in impurities that tend to freeze at cryogenic temperatures.
Aspect 3 is the method of Aspects 1 or 2, wherein the first stream 2 is a product gas stream.
Aspect 4 is the method of any of Aspects 1-3, wherein the second stream 3 is an expander gas stream.
Aspect 5 is the method of any of Aspects 1-4, wherein the first stream 2 is cooled by the heat exchanger 100 to a cryogenic temperature.
Aspect 6 is the method of any of Aspects 1-5, wherein the first liquefied stream 4 is a liquefied natural gas product.
Aspect 7 is the method of any of Aspects 1-6, wherein the cooled gas stream 5 is a cooled expander gas stream.
Aspect 8 is the method of any of Aspects 1-7, wherein passing the expander refrigeration stream 11 through the heat exchanger 100 results in cooling of other gases in the heat exchanger.
Aspect 9 is the method of any of Aspects 1-8, wherein one or more of the compressing steps is performed using part of or all work extracted at the turbo-expander 300.
Aspect 10 is the method of any of Aspects 1-9, further comprising monitoring one or more of flow rate, flow volume, gas temperature, gas composition, or gas pressure.
Aspect 11 is the method of any of Aspects 1-10, further comprising adjusting one or more of flow rate, flow volume, and/or flow ratio of one or more of the clean gas stream 1, the first stream 2, the second stream 3, the expander refrigeration stream 11, the secondary refrigeration stream 15, and/or the tertiary refrigeration stream 34 based on the monitoring.
Aspect 12 is the method of any of Aspects 1-11, further comprising expanding, decreasing the pressure of, and/or cooling one or more stream by way of one or more pressure-reducing valves.
Aspect 13 is the method of any of Aspects 1-12, wherein one or more of the pressure-reducing valves is a Joule-Thompson valve(s) 1600.
Aspect 14 is the method of any of Aspects 1-13, wherein the one or more stream is the first liquefied stream 4 and is passed through one or more Joule-Thompson valve(s) 1600 to provide any one or more of: the two-phase product stream 8 that is an LNG to storage stream; and/or the first slipstream 14 which forms the secondary refrigeration stream 15; and/or the second slipstream 32 which mixes with the boil off gas stream 31 to form the tertiary refrigeration stream 34.
Aspect 15 is the method of any of Aspects 1-14, further comprising delivering the two-phase product stream 8 to a storage container once the desired cryogenic liquid storage temperature is reached.
Aspect 16 is the method of any of Aspects 1-15, wherein the turbo-expander 300, and one or more compressor are part of a single system coupled via a bull gear and pinions
Aspect 17 is the method of any of Aspects 1-16, further comprising serially compressing the second combined stream 21 by compression with: i) a first compressor or compression stage 900, then ii) a second compressor or compression stage 1000, and then iii) a third compressor or compression stage 1200 or 1900 to form the recirculation gas stream 28.
Aspect 18 is the method of any of Aspects 1-17, wherein the compressing of the second combined stream 21 is performed using a compander.
Aspect 19 is the method of any of Aspects 1-18, wherein the compressing of the second combined stream 21 is performed using a recycle compressor package and the compression side of an expander package.
Aspect 20 is the method of any of Aspects 1-19, wherein the expander package comprises a compressor and expander, wherein the expander package is separate and independent from the recycle compressor package.
Aspect 21 is the method of any of Aspects 1-20, wherein the recycle compressor package comprises a multi-stage compressor, such as two or more stages, with a single prime mover and a single shaft.
Aspect 22 is the method of any of Aspects 1-21, wherein the compressing of the second combined stream 21 is performed using a multi-stage compressor system with: i) a compression system with at least three compression stages (
Aspect 23 is the method of any of Aspects 1-22, wherein a single motor provides all external power required to perform the method.
Aspect 24 is the method of any of Aspects 1-23, wherein part of or all work extracted at expander 300 is used in compressing the second combined stream 21.
Aspect 25 is the method of any of Aspects 1-24, wherein the tertiary refrigeration return gas stream 35 is boosted in pressure by way of a low-pressure compressor.
Aspect 26 is the method of any of Aspects 1-25, wherein the secondary refrigeration stream 15 passes through the heat exchanger 100 to provide cooling for the process.
Aspect 27 is the method of any of Aspects 1-26, wherein the tertiary refrigeration stream 34 passes through the heat exchanger 100 to provide cooling for the process.
Aspect 28 is a method for natural gas liquefaction, comprising: providing a gas stream 1 and a recirculation gas stream 28; mixing the gas stream 1 and the recirculation gas stream 28 to form a mixed gas stream 1A; splitting the mixed gas stream 1A into at least a first stream 2 and a second stream 3; passing the first stream 2 and the second stream 3 through a heat exchanger 100 comprising: an expander refrigeration stream 11; a secondary refrigeration stream 15; and a tertiary refrigeration stream 34; wherein the heat exchanger 100 cools the first stream 2 to form a first liquefied stream 4, which is split to form i) a two-phase stream of natural gas 8, and i) optionally a first slipstream 14, and ii) optionally a second slipstream 32, and iii) optionally the first slipstream 14 is reduced in pressure to provide the secondary refrigeration stream 15, and optionally the second slipstream 32 is reduced in pressure to provide reduced-pressure slipstream 33 which is optionally combined with boil-off gas stream 31 to form the tertiary refrigeration stream 34; wherein the heat exchanger 100 cools the second stream 3 by passing it through the heat exchanger 100 to form a cooled gas stream 5: wherein the cooled gas stream 5 is passed through a turbo-expander 300 to provide the expander refrigeration stream 11; wherein one or more of the expander refrigeration stream 11, the secondary refrigeration stream 15, and/or the tertiary refrigeration stream 34 are optionally passed through a heat exchanger 100 and are compressed one or more times, individually or together, to provide a portion or all of the recirculation gas stream 28.
Aspect 29 is a system for natural gas liquefaction, comprising: one or more heat exchanger 100 comprising: an expander refrigeration stream 11; a secondary refrigeration stream 15; and a tertiary refrigeration stream 34; wherein one or more of the heat exchangers 100 comprise one or more inputs to receive one or more mixed gas streams 1A from a natural gas stream and a recirculation gas stream; wherein one or more of the heat exchangers is configured to cool the mixed gas streams and provide a first liquefied stream 4 and a cooled gas stream 5 therefrom; at least one turbo-expander 300 configured to receive the cooled gas stream 5 and to provide the expander refrigeration stream 11 for input into one or more of the heat exchangers 100; storage 1500 configured to receive all or a portion of a two-phase product stream 8 which has been reduced in pressure from the first liquefied stream 4, wherein optionally the first liquefied stream 4 is split and reduced in pressure to provide for the secondary refrigeration stream 15 and/or the tertiary refrigeration stream 34; wherein one or more of the heat exchangers 100 comprises one or more inputs to receive one or more or all of the expander refrigeration stream 11, the secondary refrigeration stream 15 and/or the tertiary refrigeration stream 34; one or more compressors with one or more inputs for receiving one or more or all of the expander refrigeration stream 11, the secondary refrigeration stream 15 and/or the tertiary refrigeration stream 34, which compressor(s) provide the recirculation gas stream 28 as an output.
Aspect 30 is a system configured to be capable of performing any one or more of the method steps described herein and/or shown in the methods of
The accompanying drawings illustrate certain aspects of implementations of the present disclosure and should not be construed as limiting. Together with the written description, the drawings serve to explain certain principles of the disclosure.
Methods, which can be performed using such a system, are provided below. The component and stream numbering provided in the claims is made in reference to
The following terms are used throughout the disclosure. Other terms should be construed as having their ordinary meaning within the oil and gas engineering arts.
Gas Inlet Options—Clean incoming natural gas is fed into the appropriate location in the process based on inlet gas pressure. Clean gas is substantially free of H2O, CO2, heavy hydrocarbons (C6+), BTEX, Mercaptans, H2S and Hg.
Recycle Compressor—A single prime mover, single shaft, multi-stage compressor. Gas from various points in the process, at different pressures, is fed into a single compressor at the suction of each stage. The inlet to the first stage is designated as low pressure (Plow). The gas entering the second stage is designated as intermediate pressure (Pint). The gas entering the third stage is designated as high pressure (Phigh). Gas exiting the compressor is designated as Recycle pressure (Precycle). Other implementations can include 2 stages, or more than 3 stages. The recycle compressor can also be implemented as a system of individual compressors each with its own prime mover or any combination thereof.
Heat Exchanger—The main heat exchanger of the refrigeration system whose function it is to cool natural gas to cryogenic temperatures. Refrigeration comes from the primary, secondary and tertiary flow paths/refrigeration streams and can be provided by a primary heat exchanger, such as a single heat exchanger (e.g., a braised aluminum heat exchanger (BAHX)), or multiple heat exchangers, such as one or more multiple passage braised aluminum heat exchanger.
Turbo Expander/Compressor (also referred to as a Turbo-Expander)—Common Shaft, high speed turbines where the turbo expander rapidly lets down gas pressure and the turbo compressor (driven by the Turbo Expander) increases gas pressure.
Mixer—A single point in the gas liquefaction systems and processes where gas streams are combined at a common pressure
Joule Thompson (JT) Valve—A special flow control valve used to rapidly expand gas (let down pressure) to provide cooling.
Liquefied Natural Gas (LNG) Storage Tank—Specialized cryogenic storage tank. LNG Storage tank can be an Isometric Container, LNG Trailer, or Stationary Tank. Storage can also be implemented as a plurality of vessels. In embodiments, the liquefied natural gas (LNG) can be stored in a buffer storage vessel before loading the LNG into subsequent storage or onto a transport truck. For example, after processing and while waiting for a transport truck to arrive, the LNG can be placed in a buffer storage for temporary storage until the truck arrives where the LNG can be loaded to the transport truck from the buffer storage, if desired.
Boil off Gas (BOG)—Natural gas in vapor phase near cryogenic liquid temperatures. Heat is always being added to the system/storage so BOG is generated as the LNG boils off to vapor. Additionally, the portion of the product stream that contains the LNG intended for storage is a two-phase stream with up to 15% vapor. The process inherently generates vapor going to the storage (e.g., buffer storage and/or an LNG transportation vehicle) which can be returned to the heat exchanger as BOG in any embodiment.
Refrigeration Streams—Provides the necessary cooling to lower the inlet natural gas temperature from close to ambient temperature to cryogenic temperatures low enough to liquefy natural gas.
The term “about” in association with a numerical value means that the numerical value can vary plus or minus 10% or less of the numerical value.
The inventive methane-based refrigeration system and method that optionally also uses a slip stream of LNG (liquid natural gas) for additional cooling, is shown in
Clean gas stream 1 comprises a clean feed gas free of impurities that have freezing potential at cryogenic temperatures. Clean gas stream 1 is combined with recirculation gas stream 28 to form mixed gas stream 1A. Mixed gas stream 1A is split into two streams: first stream 2, which is a warm product stream, and second stream 3, which is a warm expander gas.
First stream 2 is passed through a heat exchanger 100 which cools the gas stream to cryogenic temperatures by cross exchanging with one or more refrigeration streams, resulting in the formation of a first liquefied stream 4. The first liquefied stream 4 is at a high pressure after leaving the heat exchanger 100. The pressure of first liquefied stream 4 is reduced to the LNG storage tank pressure, resulting in two-phase product stream 8. The two-phase product stream 8 is stored in LNG storage 1500.
The refrigeration streams comprise an expander refrigeration stream 11, a secondary refrigeration stream 15, and a tertiary refrigeration stream 34.
Second stream 3 is also passed through a heat exchanger 100 which cools the gas stream to about −20° F. to form a cooled gas stream 5. Cooled gas stream 5 is passed through an expander inlet knock-out vessel 200, which removes any liquids, resulting in a first gas-only stream 10. First gas-only stream 10 passes through a turbo-expander 300, which expands the stream to a lower pressure, resulting in expander refrigeration stream 11, which has been cooled to cryogenic temperatures through the expansion.
In embodiments, the liquid removed by knock-out vessel 200 is combined with expander refrigeration stream 11. Expander refrigeration stream 11 is then passed through the heat exchanger 100, providing refrigeration by cross-exchanging with one or more other gas streams, and resulting in first refrigeration return gas stream 12.
Secondary refrigeration stream 15 is passed through the heat exchanger 100, thereby providing refrigeration by cross-exchanging with one or more other gas streams and resulting in second refrigeration return gas stream 16.
The first refrigeration return gas stream 12 and the second refrigeration return gas stream 16 are combined to form a first combined stream 20.
A second slip stream 32 is created from two-phase product stream 8 to be routed back toward the heat exchanger. The pressure of slip stream 32 is reduced forming reduced-pressure slip stream 33, which is mixed with boil-off gas stream 31 (from the liquefied natural gas storage 1500), forming tertiary refrigeration stream 34. Tertiary refrigeration stream 34 is passed through heat exchanger 100 to form a tertiary refrigeration return gas stream 35.
The tertiary refrigeration return gas stream 35 is passed through a compressor 700 and cooler 800, forming compressed tertiary refrigeration return gas stream 36. The compressed tertiary refrigeration return gas stream 36 is then combined with first combined stream 20 to form second combined stream 21.
In a first embodiment,
In a second embodiment (
In embodiments, the system further comprises one or more valve(s) 1600. In embodiments, one or more of the valve(s) 1600 are Joule-Thomson valve(s).
In embodiments, a single motor 1700 provides all external power required to perform the method. In other embodiments, multiple motors 1700 may be used to provide required external power.
The system and process implementations shown in
Components and features used in system and process implementations shown in the drawings and their physical implementation and arrangement can be chosen according to the judgement of an oil and gas engineer or similar artisan. Natural gas compressors can be implemented through selection of those known in the art such as those that operate by positive displacement; these include lobe, screw, liquid ring, scroll and vane type gas compressors all of which are rotary-type gas compressors, and diaphragm, double acting and single acting gas compressors all of which are reciprocating type gas compressors. Dynamic type gas compressors such as centrifugal gas compressors and axial flow gas compressors are also known. Further, compressors can be constant speed compressors or variable speed compressors. Similarly, heat exchangers such as countercurrent flow heat exchangers composed of aluminum plates and fins as well as turboexpanders/compressors useful for gas liquefaction are known and need not be detailed here. Flow processes can be implemented through any suitable pipe, such as metal piping, used for transferring natural gas such as black steel, galvanized steel, copper, brass or corrugated stainless steel tubing. Polyvinyl chloride (PVC) and polyethylene (PE) can be used for pipes buried outside a plant, which may be useful for implementing transfer to plant inlets and outlets.
Operations and processes described or depicted herein can be implemented or assisted through one or more computer processor. Implementations can include a non-transitory computer readable storage medium comprising one or more computer files comprising a set of computer-executable instructions for performing one or more of the processes and operations described herein and/or depicted in the drawings. In exemplary implementations, the files may be stored contiguously or non-contiguously on the computer-readable medium. Further, implementations include a computer program product comprising the computer files, either in the form of the computer-readable medium comprising the computer files and, optionally, made available to a consumer through packaging, or alternatively stored on cloud computing storage on one or more server and made available to a consumer through electronic distribution. As used herein, a “computer-readable medium” includes any kind of computer memory such as floppy disks, conventional hard disks, CD-ROMS, Flash ROMS, non-volatile ROM, electrically erasable programmable read-only memory (EEPROM), and RAM.
As used herein, the terms “computer-executable instructions”, “code”, “software”, “program”, “application”, “software code”, “computer readable code”, “software module”, “module” and “software program” are used interchangeably to mean software instructions that are executable by a processor. The computer-executable instructions may be organized into routines, subroutines, procedures, objects, methods, functions, or any other organization of computer-executable instructions that is known or becomes known to a skilled artisan in light of this disclosure, where the computer-executable instructions are configured to direct a computer or other data processing device to perform one or more of the specified processes and operations described herein. The computer-executable instructions may be written in any suitable programming language, non-limiting examples of which include C, C++, C#, Objective C, Swift, Ruby/Ruby on Rails, Visual Basic, Java, Python, Perl, PHP, and JavaScript.
In other implementations, files comprising the set of computer-executable instructions may be stored in computer-readable memory on a single computer or distributed across multiple computers. A skilled artisan will further appreciate, in light of this disclosure, how various implementations can include, in addition to software, using hardware or firmware. As such, as used herein, the operations can be implemented in a system comprising any combination of software, hardware, or firmware.
Implementations can include one or more computers or devices loaded with a set of the computer-executable instructions described herein. The computers or devices may be a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a particular machine, such that the one or more computers or devices are instructed and configured to carry out the processes and operations described herein. The computer or device performing the specified processes and operations may comprise at least one processing element such as a central processing unit (i.e. processor) and a form of computer-readable memory which may include random-access memory (RAM) or read-only memory (ROM). The computer-executable instructions can be embedded in computer hardware or stored in the computer-readable memory such that the computer or device may be directed to perform one or more of the processes and operations depicted in the drawings and/or described herein.
An exemplary implementation includes a single computer or device (e.g. desktop, laptop, tablet, smartphone) that may be configured at a stationary gas liquefaction plant or mobile gas liquefaction system to serve as a controller. The controller may comprise at least one processor, a form of computer-readable memory, and a set of computer-executable instructions for performing one or more of the processes and operations described and/or depicted herein. The single computer or device may be configured at a gas liquefaction plant or mobile system to serve as a controller which sends commands to motors controlling one or more Control Valves to direct or control the flow of gas including rate, volume, and direction in accordance with one or more processes and operations described herein. For example, motors controlling the Control Valves may be connected to the controller by any suitable network protocol, including TCP, IP, UDP, or ICMP, as well any suitable wired or wireless network including any local area network, Internet network, telecommunications network, Wi-Fi enabled network, or Bluetooth enabled network. The controller may be configured at the gas liquefaction plant or mobile system to control opening and closing of the Control Valves based on inputs received from one or more sensors installed within the plant or mobile system. The one or more sensors are capable of measuring or monitoring one or more gas characteristics selected from a gas pressure, temperature, flow rate, and flow volume, and can be installed in various inlets, outlets, or other conduits within the stationary plant or mobile system, or within plant or system equipment. The one or more sensors can send data to the controller through a wired or wireless connection. The controller may also allow an operator to directly control processes at the gas liquefaction plant or mobile system through opening and closing of the Control Valves through an operator interface which may be a graphical user interface (GUI) which may be presented as an HTTP webpage that may be accessed by the operator at a remote general purpose computer with a processor, computer-readable memory, and standard I/O interfaces such as a universal serial bus (USB) port and a serial port, a disk drive, a CD-ROM drive, and/or one or more user interface devices including a display, keyboard, keypad, mouse, control panel, touch screen display, microphone, etc. for interacting with the controller through the GUI.
The present invention has been described with reference to particular embodiments having various features. In light of the disclosure provided above, it will be apparent to those skilled in the art that various modifications and variations can be made in the practice of the present invention without departing from the scope or spirit of the invention. One skilled in the art will recognize that the disclosed features may be used singularly, in any combination, or omitted based on the requirements and specifications of a given application or design. When an embodiment refers to “comprising” certain features, it is to be understood that the embodiments can alternatively “consist of” or “consist essentially of” any one or more of the features. Any of the methods disclosed herein can be used with any of the systems disclosed herein or with any other systems. Likewise, any of the disclosed systems can be used with any of the methods disclosed herein or with any other methods. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention.
It is noted in particular that where a range of values is provided in this specification, each value between the upper and lower limits of that range is also specifically disclosed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range as well. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. It is intended that the specification and examples be considered as exemplary in nature and that variations that do not depart from the essence of the invention fall within the scope of the invention. Further, all of the references cited in this disclosure are each individually incorporated by reference herein in their entireties and as such are intended to provide an efficient way of supplementing the enabling disclosure of this invention as well as provide background detailing the level of ordinary skill in the art.
This application relies on the disclosure of and claims priority to and the benefit of the filing date of U.S. Provisional Application No. 63/517,013, filed on Aug. 1, 2023, the disclosure of which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63517013 | Aug 2023 | US |
