Systems, apparatus and methods for managing input and output pressures of air-breathing engine reformers - Patents.com

Abstract

Systems and methods are provided for producing end products from hydrocarbon gases, such as flare gas, using partial oxidation. Methods and systems are provided for minimizing the compression work required for an air-breathing engine reformer in a gas-to-liquid system. Methods and systems are provided for minimizing the compression work required for an air-breathing engine reformer in a gas-to-liquid system and method by one or more of: (a) reducing the amount of nitrogen; (b) increasing the engine reformer back pressure from the standard 1 or 2 bar to up to 5 bar; (c) using a turbo expander to recover much of the compression work, thereby reducing, among other things, the cost of operating the plant; and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressure. In one embodiment, the end product is methanol.

Description

[Technical field]

[0001] This application (i) claims the benefit of the filing date of, and claims the benefit of priority to, U.S. Provisional Application No. 63 / 304,463, filed January 28, 2022, under 35 U.S.C. § 119(e)(1); (ii) is a continuation-in-part of U.S. Provisional Application No. 17 / 746,942, filed May 17, 2022; (iii) is a continuation-in-part of U.S. Application No. 17 / 953,056, filed September 26, 2022; and (iv) is a continuation-in-part of U.S. Application No. 17 / 984, filed November 9, 2022. No. 126, (v) claims benefit of the filing date of, and claims the benefit of priority under 35 U.S.C. § 119(e)(1) to, U.S. Provisional Application No. 63 / 304,371, filed January 28, 2022, and (vi) claims benefit of the filing date of, and claims the benefit of priority under 35 U.S.C. § 119(e)(1) to, U.S. Provisional Application No. 63 / 304,475, filed January 28, 2022, the entire disclosures of each of which are incorporated herein by reference.

[0002] The present invention relates to new and improved methods, apparatus and systems for reducing the compressor work (e.g., compression requirements, such as the number and size of compressors, the energy required to operate the compressors, etc.) required in reformer-based hydrocarbon processing systems, such as gas-to-liquid systems, including systems that recover and convert hydrocarbon gases, such as flare gas, into useful and economically viable materials. In particular, the present invention relates to new and improved methods, apparatus and systems for operating engines, particularly air-breathing reformers, used in gas liquefaction systems and processes. "Flare gas," "waste gas," and similar terms shall be given the broadest possible meaning and shall include gas generated, generated, associated with, or produced by or from oil and gas production, hydrocarbon wells (including conventional and unconventional wells), petrochemical processing, refining, landfills, wastewater treatment, dairy and livestock production, and other municipal, chemical, and industrial processes. Thus, for example, flare gas and waste gas include stranded gas, associated gas, landfill gas, vent gas, biogas, digester gas, small pocket gas, and remote gas. [Background technology]

[0003] The composition of flare gas is usually a mixture of different gases. Its composition depends on the source of the flare gas. For example, gas released during oil and gas production contains mainly natural gas. Natural gas is more than 90% methane (CH4), with ethane and small amounts of other hydrocarbons, water, N2, and CO2. Flare gas from refineries and other chemical and manufacturing operations is usually a mixture of hydrocarbons and sometimes H2. Landfill gas, biogas, and digester gas are usually a mixture of CH4 and CO2, with small amounts of other inert gases. In general, flare gas contains one or more of the following gases: methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, ethylene, propylene, 1-butene, carbon monoxide, carbon dioxide, hydrogen sulfide, hydrogen, oxygen, nitrogen, and water.

[0004] The majority of flare gas originates from smaller, individual point sources, such as multiple oil or gas wells in an oil field, landfills, or chemical plants. Prior to this invention, flare gas, particularly from hydrocarbon production wells and other small point sources, was disposed of by flaring or, in some cases, directly vented to the atmosphere. This flare gas could not be economically captured or utilized. The flaring and venting of flare gas from both hydrocarbon production and other endeavors has raised serious concerns about pollution and greenhouse gas emissions.

[0005] As used herein, unless otherwise specified, the terms "syngas," "synthetic gas," and similar terms are to be given the broadest possible meaning and include gases having a mixture of H and CO as the primary components, and may also include CO, N, and water, as well as minor amounts of other materials.

[0006] As used herein, unless otherwise indicated, "product gas" and similar terms should be given the broadest possible meaning and include gases having H, CO, and other hydrocarbons, typically containing significant amounts of other hydrocarbons such as methane.

[0007] As used herein, unless otherwise specified, the term "reprocessed gas" includes "syngas," "synthesis gas," and "product gas."

[0008] Unless otherwise indicated, as used herein, "partial oxidation," "partially oxidize," and like terms refer to a chemical reaction in which a substoichiometric mixture of fuel and air (i.e., a fuel-rich mixture) is partially reacted (e.g., combusted) to produce synthesis gas. The term partial oxidation includes both thermal partial oxidation (TPOX) and catalytic partial oxidation (CPOX), which typically occurs in non-catalytic reformers. The general equation for the partial oxidation reaction is:

[0009] TIFF2025505125000002.tif17170

[0010] Unless otherwise indicated, the recitation of ranges of values ​​used herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise stated herein, each separate value within a range is incorporated herein as if it were individually set forth herein.

[0011] In general, the term "about" as used herein, unless otherwise specified, is meant to encompass a variance or range of ±10%, or the greater of the experimental or instrumental error associated with obtaining the stated value.

[0012] Unless otherwise noted, the term "CO2e" is used herein to define the equivalence of other more potent greenhouse gases (e.g., methane and nitrous oxide) to carbon dioxide on a 20- or 100-year Global Warming Potential basis based on the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) methodology. The term "carbon intensity" refers to the life cycle CO2e generated per unit mass of product.

[0013] As used herein, unless otherwise noted, the term "crude methanol" is defined as methanol produced in a methanol synthesis loop prior to removal of water, dissolved gases, and other contaminants. Crude methanol often contains 5-20 wt% water, dissolved gases (e.g., 1-2 wt% CO2), and trace contaminants (e.g., ethanol). As used herein, unless otherwise noted, the term "stabilized methanol" is defined as crude methanol that has undergone a flash operation (e.g., single-stage flash drum) to reduce the concentration of dissolved gases and other light components. Stabilized methanol often has a CO2 concentration of less than 1%, most commonly about 0.5 wt%. As used herein, terms such as "feed methanol," "initial methanol," and the like refer to "crude methanol," "stabilized methanol," or both. As used herein, the term "grade methanol" is defined as methanol that meets purity specifications such as the ASTM AA standard (D1152) or the IMPCA Methanol Reference Standard.

[0014] As used herein, unless otherwise noted, the terms % and mol % are used interchangeably and refer to, for example, the ratio of moles of a first component to the moles of an entire formulation, mixture, material, or product.

[0015] In this specification, unless otherwise specified, the terms weight % (abbreviation: wt%) and mass % refer to the percentage of the weight of a first component relative to the total weight of, for example, a formulation, mixture, material or product.

[0016] In this specification, unless otherwise noted, room temperature is 25° C., and standard temperature and pressure are 15° C. and 1 atmosphere (1.01325 bar). Unless expressly stated otherwise, all tests, test results, physical properties, and temperature-dependent and / or pressure-dependent values ​​are provided at standard temperature and pressure.

[0017] As used herein, unless otherwise specified, the terms "fuel to air equivalence ratio", "equivalence ratio", "fuel / air equivalence ratio", "Φ" or "ER", and similar such terms shall have the same meaning and be given their broadest meaning and include the ratio of the actual fuel / air ratio to the stoichiometric fuel / air ratio. A stoichiometric air / fuel ratio is the air / fuel ratio required for ideal stoichiometric combustion to occur, where all the fuel and oxygen are consumed in the reaction and the products are carbon dioxide and water. Global warming and environmental issues

[0018] The relative environmental impact of waste gas emissions compared to carbon dioxide, which is already a serious problem, is shown in Figure 12.

[0019] The impact of methane leaks from flared gas and vents on global warming cannot be underestimated. According to a 2019 report by the International Energy Agency (IEA), approximately 200 billion cubic meters of waste and flared gas were burned or released into the atmosphere in 2018. Approximately 50 billion cubic meters of gas were released, and approximately 150 billion cubic meters of gas were burned in flares. Combustion aims to convert hydrocarbons into carbon dioxide, but its peak efficiency is 98%, and efficiency decreases in the presence of wind. The combination of low combustion efficiency and gas releases resulted in a total of approximately 1.4 billion tonnes of CO2e equivalent CO2e emissions. This is equivalent to approximately 2.7% of all annual anthropogenic CO2e sources.

[0020] This Background of the Invention section is intended to introduce various aspects of technology that may be related to embodiments of the present invention. As such, the preceding discussion in this section provides a framework for further understanding the present invention and should not be construed as admissions of prior art. Summary of the Invention [Problem to be solved by the invention]

[0021] There has been a long-standing and growing unmet need for systems, apparatus, and methods for converting uneconomical hydrocarbon fuels (e.g., stranded gas, associated gas, non-associated gas, landfill gas, flare gas, small pocket gas, remote gas, wastewater treatment gas) into value-added, transportable products (e.g., methanol, ethanol, ammonia, dimethyl ether, FT liquids, and other fuels or chemicals). There has been a continuing need for improved systems and methods for controlling engine operation, particularly inlet and outlet pressures and pressure differentials, when air-breathing engines and their operation are used as reformers in systems, apparatus, and methods for converting uneconomical hydrocarbon fuels (e.g., stranded gas, associated gas, non-associated gas, landfill gas, flare gas, small pocket gas, remote gas, wastewater treatment gas) into value-added, transportable products (e.g., methanol, ethanol, ammonia, dimethyl ether, FT liquids, and other fuels or chemicals). The present invention solves these needs by providing, among other things, the articles of manufacture, apparatus, and processes taught and disclosed herein.

[0022] In general, there are significant problems, costs, and inefficiencies associated with the compression work used in some embodiments of gas-to-liquid systems, because the pressure required in the synthesis process is typically much higher than the pressure at the engine reformer outlet. For example, in the case of methanol synthesis, the pressure required at the inlet to the methanol production unit is typically 50 bar, while the pressure at the outlet of a commercial engine is typically around 1 bar (the engine outlet or output is used, for example, to feed the intermediates of the methanol synthesis unit). Thus, prior to the present invention, this 50-fold difference had to be made up by compression work, e.g., a compressor. The embodiments of the present invention solve these problems and needs, among others, by providing the articles of manufacture, apparatus, and processes taught and disclosed herein. [Means for solving the problem]

[0023] Thus, there is provided a method and system for minimizing the compression work required in an air-breathing engine reformer based gas to liquids system having or using one or more of the following: (a) reducing the amount of nitrogen, (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar, (c) using a turbo expander to recover much of the compression work, reducing the cost required to operate the plant, among other effects, and (d) using an intensified synthesis loop to achieve acceptable methanol synthesis at lower overall pressures.

[0024] Further provided is a gas to liquefaction system and method having an engine reformer that produces an intermediate syngas at a pressure of about 2 bar to about 5 bar as a means of reducing downstream compression requirements, a syngas compressor that compresses the syngas to a desired downstream synthesis pressure to provide a high pressure syngas, and a downstream synthesis process that converts the high pressure syngas to desired products.

[0025] Further provided are gas liquefaction systems and methods having a downstream synthesis reactor that selectively removes products or by-products of the synthesis reaction from unreacted synthesis gas (syngas) to shift the equilibrium to achieve high single-pass conversions at lower synthesis pressures, with product separation being performed in-situ within the synthesis reactor, in a closely coupled manner, or both, thereby reducing or eliminating the recycle loop to the synthesis reactor and reducing the compression work for recompression of the recycle gas, and further means for separating products from reactants within the reactor, which may include one or more of adsorption, absorption, membrane separation, distillation, and the like.

[0026] Additionally, a gas liquefaction system and method is provided having a turboexpander downstream of the recuperator to recover energy from the gaseous product stream which is depressurized before being discharged from the system, the recovered energy being used to reduce the net compression work for the process, thereby enabling self-sustaining operation.

[0027] Additionally, these methods, systems and apparatus are provided having one or more of the following features: Engine reformer modifications such as inlet charge boost or valve timing changes to promote better engine volumetric efficiency and net shaft power; Various syngas conditioning steps to remove soot, sulfur, oxygen, carbonyls, and other contaminants; Means to regenerate the sorbent or sweep stream to recover products and return the sorbent / sweep material to the reactor; Using the output from the engine reformer to provide heat, electricity, shaft power, or pneumatics / hydraulics to downstream reactive separation steps; Integrated turboexpanders including a recuperative heat exchanger to transfer heat from the hot syngas stream to the turboexpander inlet stream to increase enthalpy and turboexpander work, an indirect heat transfer loop for recuperative heat exchange to decouple the process streams, heat storage in the indirect heat transfer loop to improve heat utilization, facilitate process start-up, and inhibit feedback from process disturbances, and an interstage heat exchanger in the expander of a multi-stage compressor.

[0028] Thus, there is provided a method for converting gas to an end product, the method comprising the steps of receiving a stream of a hydrocarbonaceous fuel source from a source, the stream having a composition consisting primarily of gaseous hydrocarbons and inert gases, partially oxidizing the fuel source in an air-breathing reciprocating engine to produce a synthesis gas mixture having a H2 / CO ratio suitable for the synthesis of liquids, and reducing the compressor workload.

[0029] Further provided are these methods and systems having one or more of the following features: The step of reducing the compressor work includes reducing the amount of nitrogen. The step of reducing the compressor work includes increasing the back pressure of the air-breathing reciprocating engine. The back pressure is increased to 5 bar. The back pressure is greater than 2 bar. The step of reducing the compressor work includes using a turbo expander and heat exchanger system. The air-breathing reciprocating engine is a rich burn engine. The air-breathing reciprocating engine is a variable compression ratio engine. The air-breathing reciprocating engine is a compression ignition engine. The air-breathing reciprocating engine is a spark ignition engine.

[0030] Further provided is a system for converting gas to an end product, the system comprising an inlet port for receiving a flow of a hydrocarbon-based fuel source having a composition primarily of gaseous hydrocarbons and inert gases from a source, the inlet port in fluid communication with an air-breathing reciprocating engine adapted to partially oxidize the fuel source to produce a synthesis gas mixture having a H2 / CO ratio suitable for synthesis of liquids, and a means for reducing compressor work.

[0031] Further provided are these methods and systems having one or more of the following features: The means for reducing the compressor work includes a means for reducing the amount of nitrogen. The means for reducing the amount of nitrogen includes an oxygen enrichment unit. The means for reducing the amount of nitrogen includes a nitrogen removal unit. The means for reducing the compressor work includes an increased back pressure of the air-breathing reciprocating engine. The increased back pressure is up to 5 bar. The increased back pressure is greater than 2 bar. The increased back pressure is greater than 2 bar. The means for reducing the compressor work includes using a turboexpander-compressor-heat exchanger. The turboexpander-compressor-heat exchanger system includes three stages. The turboexpander-compressor-heat exchanger system includes a compressor-turbine assembly. The turboexpander-compressor-heat exchanger system is configured with two stages, each stage having a compressor, a turbine and a heat exchanger. The turboexpander-compressor-heat exchanger system includes three stages, each stage having a compressor, a turbine and a heat exchanger. The means for reducing the compressor work includes a reaction separation synthesis loop. The air-breathing reciprocating engine is a rich burn engine. The air-breathing reciprocating engine is a variable compression ratio engine. The air-breathing reciprocating engine is a compression ignition engine. The air-breathing reciprocating engine is a spark ignition engine. The fuel source is flare gas. The engine is a compression ignition engine, including a Diesel cycle engine, or a homogeneous charge compression ignition engine. The engine is a spark ignition engine, including an Otto cycle. The engine is an opposed piston, free piston, linear internal combustion engine. The engine is a crankshaft driven opposed piston internal combustion engine with a crankshaft phaser to rotate the phase of one piston relative to the phase of the other piston to change the overall compression ratio.

[0032] Further provided is a system for converting flare gas to methanol with reduced compressor work, the system including a first line for receiving a flow of air and a second line for receiving a flow of flare gas, the first and second lines being in fluid communication with an air-breathing engine reformer assembly, a turbo expander assembly in fluid communication with a third line, the engine reformer assembly being in fluid communication with the third line, the third line connecting the engine reformer assembly and the turbo expander assembly to allow an intermediate product from the engine reformer to flow to the turbo expander assembly, the turbo expander assembly being in fluid communication with a fourth line, a fifth line, and a sixth line. a turboexpander assembly in fluid communication with the fourth line, the fifth line, and the sixth line; and a methanol synthesis assembly in fluid communication with the fourth line, the fifth line, and the sixth line, wherein the fourth line connects the turboexpander to the methanol synthesis assembly to provide a first flow from the turboexpander to the methanol synthesis assembly, the fifth line connects the turboexpander to the methanol synthesis assembly to provide a second flow from the turboexpander assembly to the methanol synthesis assembly, and the sixth line connects the turboexpander to the methanol synthesis assembly to provide a third flow from the methanol synthesis assembly to the turboexpander.

[0033] Additionally, these methods and systems are provided having one or more of the following features: The intermediate product is synthesis gas. The first flow from the turboexpander to the methanol synthesis assembly is synthesis gas. The engine is a conventional spark ignition reciprocating engine utilizing a camshaft phaser that rotates the intake and exhaust camshafts to affect valve opening and closing to achieve a variable "effective" compression ratio. The engine is a conventional spark ignition reciprocating engine utilizing a variable lift and / or variable duration valve train to achieve a variable "effective" compression ratio and affect valve opening and closing. The engine includes a multi-link system in place of a conventional connecting rod that rotates the crankshaft, and an actuator motor varies the end points of the multi-link system. The engine is a two-stroke engine. The engine is a four-stroke engine. The engine speed is varied with the engine compression ratio to achieve the desired combustion and the desired exhaust gas composition. The inlet manifold air temperature is varied with the engine compression ratio to achieve the desired combustion and the desired exhaust gas composition. Inlet manifold air pressure (e.g., boost level) is varied with the engine compression ratio to achieve the desired combustion and desired exhaust gas composition.aSteam or hydrogen is added to the incoming air or fuel and the amount added is varied with the engine compression ratio to achieve the desired combustion and desired exhaust gas composition.

[0034] Further provided are these methods and systems having one or more of the following features: The engine is operated under an ER of at least 1.5; The engine is operated under an ER of at least about 2; The engine is operated under an ER of at least about 2.5; The engine is operated under an ER of at least about 3; The engine is operated under an ER of at least about 3; The compression ratio is controlled between 8:1 and 14:1; Downstream of the engine, an integrated heat exchanger, compression system components, and a heat exchanger are combined to prepare synthesis gas for a downstream synthesis reactor; Downstream of the engine is a downstream synthesis reactor system for producing useful liquid products; A cloud-based remote monitoring system including AI-trained anomaly detection dynamically monitors the changes in variable valve timing and evaluates and responds to fuel delivery anomalies. From a CO2e life cycle assessment perspective, the system provides negative CO2e emissions of about 40 kg CO2e per kg of final product (in this case, liquid methanol) when produced from flare gas compared to baseline liquid methanol production from pipeline natural gas. When produced from the flare gas and displacing an equivalent kg of baseline methanol from pipeline natural gas, the resulting negative CO2e emissions are about 70 kg CO2e per kg of final product (methanol). When produced from the flare gas and displacing an equivalent kg of baseline methanol from coal gasification, the resulting negative CO2e emissions are about 130 kg CO2e per kg of final product (methanol). The final product comprises methanol. The final product has a material selected from the group consisting of ethanol, ammonia, dimethyl ether, and FT liquids. The fuel source is flare gas from a hydrocarbon well. The fuel source is flare gas from an oil well. The fuel source is flare gas from an unconventional oil well. The fuel source is flare gas, the flare gas being selected from the group consisting of petrochemical processing, refining, landfills, wastewater treatment, and animal production. The fuel gas flow rate is about 50,000 scfd to about 30,000,000 scfd. The fuel gas flow rate is from about 500,000 scfd to about 20,000,000 scfd.The fuel gas flow rate is from about 600,000 scfd to about 15,000,000 scfd.The fuel gas flow rate is from about 700,000 scfd to about 10,000,000 scfd. [Brief description of the drawings]

[0035] [Figure 1] 1 is a chart showing the equilibrium constants for the methanol synthesis reaction used in accordance with the present invention, where K1 is the equilibrium constant for the CO hydrogenation reaction (R1) in atm-2, K2 is the equilibrium constant for the CO2 hydrogenation reaction (R2) in atm-2, and K3 is the equilibrium constant for the reverse water-gas shift reaction (R3) in unitless.

[0036] [Diagram 2] 1 is a chart showing a surface plot of equilibrium-limited carbon (CO+CO2) conversion to methanol as a function of reactor temperature and pressure in accordance with the present invention. The percentages on the left side of the chart indicate the carbon conversion for each region of the chart that corresponds to a particular temperature and pressure.

[0037] [Diagram 3] FIG. 1 is a schematic flow diagram of one embodiment of a system and process according to the present invention.

[0038] [Figure 4] FIG. 1 is a schematic flow diagram of one embodiment of a system and process according to the present invention, highlighting differences in methanol synthesis pressures.

[0039] [Diagram 5] 1 is a table showing compressor output as a function of engine back pressure to achieve a downstream combined pressure of 50 bar for use in accordance with the present invention.

[0040] [Figure 6] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having a reaction product separator according to the present invention.

[0041] [Figure 7] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having reactive by-product separation in accordance with the present invention.

[0042] [Figure 8] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having a recuperator and turboexpander in accordance with the present invention.

[0043] [Figure 9] 1 is a table showing compressor power (gross and net power) in a gas to methanol conversion process using a turboexpander according to the present invention (engine back pressure 3 bar, methanol synthesis pressure 50 bar).

[0044] [Figure 10] FIG. 1 is a schematic flow diagram of an embodiment of a system and process illustrating an embodiment of an integrated turboexpander system and method (including temperature and pressure operating profiles) for use in an embodiment of a gas-to-methanol conversion system in accordance with the present invention.

[0045] [Figure 11] FIG. 2 is a TS diagram of thermodynamic state points of one embodiment of an air inhalation process according to the present invention, for example, converting flare gas to synthesis gas and then to value-added products.

[0046] [Figure 12] 1 is a table showing global warming potential values.

[0047] [Figure 13] FIG. 9 is a TS diagram illustrating one embodiment, operating conditions, and thermodynamic state points of a process for converting flag gas to synthesis gas and then to methanol using the system of FIG. 8 with a spark ignition reciprocating engine according to the present invention.

[0048] [Figure 14]FIG. 9 is a TS diagram illustrating an embodiment of the process, operating conditions, and thermodynamic state points for converting flag gas to synthesis gas and then to methanol using the system of FIG. 8 having a compression ignition reciprocating engine according to the present invention.

[0049] [Figure 15] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having a flow-matched turboexpander and compressor in accordance with the present invention. [Figure 15A] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having a flow-matched turboexpander and compressor in accordance with the present invention. [Figure 15B] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having a flow-matched turboexpander and compressor in accordance with the present invention. [Figure 15C] FIG. 1 is a schematic flow diagram of one embodiment of a system and process having a flow-matched turboexpander and compressor in accordance with the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The present invention relates generally to systems, apparatus and methods for economically recovering usable fuels from hydrocarbon gases, and in particular, in embodiments, to achieve such recovery in smaller, isolated or remote locations or positions for flare gases.

[0051] Generally, embodiments of the present invention include devices and systems that reduce the compressor work required (e.g., compression requirements, such as the number and size of compressors, the energy required to operate the compressors, etc.) in reformer-based hydrocarbon processing systems, such as gas to liquefaction systems.

[0052] Generally, embodiments of the present invention include an apparatus and system that reduces the amount of compressor work required in reciprocating engine reformer-based hydrocarbon processing systems, such as gas to liquid systems.

[0053] In general, embodiments of the present invention relate to systems and methods having gas liquefaction systems and processes, such as those for processing flare gas into methanol, in which an air-breathing engine reformer produces a synthesis gas intermediate that is further converted to methanol in a downstream synthesis step. Examples of such gas liquefaction systems are disclosed in U.S. Patent Publication No. 2022 / 0388930 and U.S. Patent Application Nos. 17 / 953,056 (filed September 26, 2022) and 17 / 984,126 (filed November 9, 2022), the entire disclosures of which are incorporated herein by reference.) In particular, embodiments of the present invention relate to apparatus, systems, and methods for improving and enhancing the pressure differentials associated with air-breathing engine reformers in these gas liquefaction systems and processes, thereby reducing the amount of compressor work required to operate these systems. Thus, embodiments of the present apparatus and system that reduce the amount of compressor work required in reciprocating engine reformer-based hydrocarbon processing systems are utilized in conjunction with or as part of these gas liquefaction systems.

[0054] Figure 1 shows the equilibrium constants for three typical reactions in methanol synthesis. Note that any two of these reactions (e.g., R1 and R2) are linearly independent, and the third (e.g., R3) is a combination of the other two. Achieving ideal synthesis gas stoichiometry represents a straightforward method to produce methanol in downstream synthesis steps according to reactions (1)-(3). (R1) CO+2H2⇔CH3OH ΔHr = -90.7kJ / mol (CO hydrogenation) (R2) CO2+3H2⇔CH3OH+H2O ΔHr = -49.5kJ / mol (CO2 hydrogenation) (R3) CO2+H2⇔CO+H2O ΔHr = 41.2kJ / mol (reverse water-gas conversion)

[0055] The hydrogenation reactions (R1 and R2) to produce methanol from CO and CO2 are exothermic, while the RWGS reaction (R3) is endothermic. Therefore, the overall equilibrium reaction to methanol is favored at low temperatures. However, catalyst activity (and associated reaction rate) decreases with temperature, so there is a practical minimum reactor temperature.

[0056] In Figure 2, the predicted one-step carbon (CO+CO2) conversion at equilibrium is shown as a function of reactor temperature and pressure. Lower temperatures and higher pressures are preferred for high conversions. These results were generated using measured equilibrium data for R1-R3 at ideal syngas stoichiometry (S=2) from an air-breathing reformer. Figures 1 and 2 reveal the fundamental chemical and physical limitations that have previously been associated with the relatively high synthesis pressures and associated compression work in commercial methanol synthesis processes. This is addressed and improved by embodiments of the present invention by reducing the compressor work.

[0057] Further referring to FIG. 5, the predicted compressor work (total syngas compression only) is shown as a function of engine exhaust back pressure at 50 bar syngas pressure downstream. These data are generated using a chemical process simulation performing mass and energy balances for an embodiment of a gas liquefaction system and method of the type shown in FIG. 4, for example. The syngas compressor is treated as a three-stage compressor with intercooling. The isentropic efficiency of this compressor is assumed to be 75%, which is representative of industrial centrifugal and reciprocating compressors. The syngas ratio adjustment recycle stream enters the compressor at the second stage inlet. Increasing the engine exhaust back pressure from 2 bar to 3 bar reduces the compression work by 20.4%. Further increasing the back pressure from 2 bar to 4 bar reduces the compression work by 28.0%. Therefore, the diminishing returns and optimum value of engine exhaust back pressure in the embodiment of FIG. 4 would be in the 2-5 bar range to balance reduced compression work with reduced engine reformer intake and performance.

[0058] Referring now to FIG. 9, the compressor power (gross and net) of an example implementation of a gas-to-methanol conversion process using a turboexpander is shown assuming an engine back pressure of 3 bar and a methanol synthesis pressure of 50 bar. These data were generated using a chemical process simulation with mass and energy balances performed for an example of a gas liquefaction system and method of the type shown in FIG. 8 for example. The total compressor work, consisting of the syngas compressor, the primary recycle compressor and the inlet air compressor, is dominated by the syngas compressor. The total compressor power is 1055.7 kW, which is usually too high for stand-alone operation without energy recovery. The turboexpander recovers 292.5 kW of power, reducing the compressor power requirement to 763.2 kW. It is preferable to use the brake power generated by the engine reformer in an stand-alone operation scenario.

[0059] Advantages of the present method, apparatus and system include, among others: 1) lower capital and operating costs compared to conventional technologies; 2) suitable for remote and distributed applications with the advantage that the process is self-sustaining in terms of power; and improves upon conventional commercial methanol synthesis technology, enabling small-scale, distributed and self-sustaining applications utilizing virgin gas.

[0060] Although methanol synthesis is taken as an example herein, it is understood that the method and system are applicable to other similar downstream synthesis processes. Thus, in general, the method and system embodiments described herein can be utilized with or in conjunction with systems and methods for converting uneconomical hydrocarbon fuels (e.g., stranded gas, associated gas, landfill gas, flare gas, small pocket gas, remote gas) into value-added, easily transportable products (e.g., methanol, ethanol, ammonia, dimethyl ether, FT liquids, and other fuels or chemicals).

[0061] In one embodiment of the present invention, the system and method reduce the gas compression requirements for the synthesis of methanol (or other downstream products such as ammonia or FT liquids) in a small-scale, modular, distributed conversion of strand gas to products (preferably high-value, easily transportable products such as methanol, ethanol, ammonia, dimethyl ether, FT liquids, other fuels or chemicals) in an integrated system with an engine-based reformer. The gas compression requirements impact the overall capital and operating costs of the process and thus the overall profitability of the modular plant. The compressor to increase the pressure of the synthesis gas leaving the engine reformer to a value suitable for downstream methanol synthesis can account for almost half of the capital investment of the entire plant. Furthermore, in practical applications, a self-sustaining plant with little external power supply is desirable. The amount of work done by the compressor is linked to the operating costs and autonomy of the plant, since the majority of the power requirements are accounted for by the power required to drive the compressor.

[0062] Improvements to, e.g., reduction in the amount of compression work in gas-to-methanol plants that use engine-based reformers to produce a synthesis gas intermediate are provided in embodiments of the present invention. Reduction in compressor work can be achieved by several devices and processes, for example, through the use of one or more of the following: (a) reducing the amount of nitrogen; (b) increasing the engine back pressure from the standard 1 or 2 bar up to 5 bar; (c) using a turbo expander to recover most of the compression work and reduce plant operating costs; and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressures.

[0063] Monetization of strand gas resources, such as associated gas from oil production, typically involves converting the gas to products or intermediates that are liquids (e.g., methanol, FT liquids) or easily condensable gases (e.g., ammonia) at ambient temperatures. Both ammonia and methanol synthesis are highly exothermic and equilibrium limited, with an overall reduction in the number of moles in the reaction. Being exothermic, low temperatures provide good conversion rates. However, lower temperatures reduce catalyst activity, necessitating larger reactors and higher catalyst loadings, which dictate the lowest practical reactor temperatures. Increasing reactor pressure shifts the equilibrium to higher conversion rates. In an embodiment, the methanol plant performs methanol synthesis under a nominal 50 bar boost pressure, much higher than the nominal exhaust pressure from engine-based reformers, especially air-breathing engine-based reformers. This high pressure requires significant compression work and associated high capital and operating costs. Despite the high pressure, single-pass conversion is still low, so a recycle loop can be used to increase the overall conversion, but this requires a larger reactor and more complex and expensive downstream separation steps.

[0064] In a preferred embodiment, one or more of the compressor work reduction devices and processes are used as part of a small, modular, decentralized, self-sufficient plant to convert strand gas into easily transportable fungible products using an engine-based reformer and a syngas intermediate.

[0065] Embodiments of the present invention include a reciprocating engine for producing reprocessed gas, preferably synthesis gas, and may be advantageous under certain circumstances, including one or more of the apparatus and processes for reducing compressor work associated with or used with the gas liquefaction systems and methods.Embodiments of the system are preferably modular and can be easily deployed in difficult to access locations where flare gas is generated, where the system footprint is limited, and combinations and variations thereof.

[0066] An object of embodiments of the present invention is, among other things, to reduce the amount of compressor work required in converting otherwise uneconomical hydrocarbon fuels (e.g., strand gas, associated gas, landfill gas, flare gas, small gas field gas, remote gas) into value-added, easily transportable products (e.g., methanol, ethanol, ammonia, dimethyl ether, FT liquids, other fuels or chemicals) using an autonomous modular system.

[0067] The present embodiments focus on a reciprocating engine and method of operating the engine that accommodates the varying combustion characteristics of fuel sources, including fuel sources originating from oil fields and landfills (e.g., flare gas). One of the reasons these gases are uneconomical is that the fuel composition varies widely. The composition variations affect combustion characteristics such as heating value, cetane number (the fuel's ignition timing retardation), and octane number (resistance to pre-ignition due to compression). These variations occur from source to source, from day to day (temporary), from season to season (especially biogas), and even as the source changes over time. The present embodiments address and solve these problems.

[0068] Conventional air-breathing reciprocating engines are typically designed to use fuels with narrow fuel specifications. For example, the compression ratio of an automotive gasoline engine is selected to match the quality of the fuel to be used. In the United States, "regular" gasoline has an octane rating of 86-87. Higher performance engines (e.g., higher compression ratios) may require premium gasoline with an octane rating of 91-94.

[0069] One embodiment of the present invention is the construction, operation, and / or operation of a commercial reciprocating engine (e.g., a commercial engine) operating at rich fuel-to-air ratio conditions to produce synthesis gas. To operate the engine outside of its intended design point and to operate well with fuels with wide variations in octane and cetane numbers, the present invention modifies engine operating parameters such as compression ratio, intake manifold air temperature, intake manifold air pressure, and engine speed. This embodiment applies to both compression ignition engines (Diesel cycle) and spark ignition engines (Otto cycle). In spark ignition engines, ignition timing can also be used to adapt engine operation to fuel variations. Desirably, this embodiment is used in a system having one or more of the present apparatus and processes to reduce compressor work.

[0070] Embodiments of the invention can be used to convert uneconomical hydrocarbon fuels, primarily gaseous hydrocarbons, taken from oil wells or remote locations and converted into more valuable, easily condensable gas or liquid compounds, such as methanol. Fuel sources can also include associated gas or flare gas produced as a by-product in oil fields. Fuel sources can also include flare gas from industrial processes, such as refinery flare gas. Fuel sources can also include biogas from landfills or anaerobic digesters.

[0071] Embodiments of the invention are particularly useful in small plants using one or more syngas engines and targeting inlet gas flows of 600,000 scfd (standard cubic feet per day). The size of such plants can vary from 80,000 scfd to 3,000,000 scfd, or from 20,000 scfd to 100,000 scfd.

[0072] Embodiments of the invention can be incorporated into one or more modular, interconnected skids or containers that are fabricated at a central manufacturer facility and then installed on-site. The system is comprised of a small number of modules that, when connected on-site, form an integrated system. This modularity of assembly allows for application in remote locations with a wide range of inlet gas feed rates while minimizing on-site labor.

[0073] Referring to FIG. 3, a general embodiment of a system and method for converting waste gas, e.g., flare gas, into value-added products, e.g., methanol, is shown. The system 100 has a reforming stage 101 and a synthesis stage 102. The system 100 has an air intake 110, which feeds air to a compressor 111, which compresses the air. The compressed air is fed through a heat exchanger 120a to a mixer 113. The system has an intake 110 for waste gas, e.g., flare gas. The waste gas flows through a heat exchanger 120b to the mixer 113. The mixer 113 feeds a predetermined mixture of air and waste gas to a reformer 114, as taught and disclosed herein.

[0074] The fuel-air mixture formed in the mixer 113 is preferably rich, and more preferably has an overall fuel-to-air equivalence ratio (Φ or ER) greater than 1, greater than 1.5, greater than 2, greater than 3, from about 1.5 to about 4.0, from about 1.1 to about 3.5, from about 2 to about 4.5, from about 1.1 to about 3, and greater.

[0075] It is understood that oxygen can be added to the air. Also, water or steam can be injected into the air-fuel mixture or into the air or fuel alone. About 1% to about 20% (molar) water can be injected, about 10% to about 15% (molar), about 5% to about 17% (molar), more than 5% (molar), more than 10% (molar), more than 15% (molar), less than 25% (molar). After oxygen enrichment, the combustion air can contain about 21% to about 90% oxygen. As used herein, "air-breathing" reformers and air-breathing engines also include engines that use air that has been reformed with the addition of water, oxygen, or both.

[0076] The reformer 114 combusts a predetermined mixture of waste gas and air (e.g., flare gas and air) to form reprocessed gas (e.g., synthesis gas), which passes through heat exchangers 120a, 120b and into a filter 115, e.g., a particulate filter.

[0077] After passing through the filter 115, the reprocessed gas (e.g., syngas) flows to a guard bed reactor assembly 116 that includes two guard bed reactors 116a, 116b. The guard bed reactors 116 contain materials, e.g., catalysts, that remove contaminants and other substances from the syngas that may adversely affect, inhibit, or contaminate subsequent equipment or processes in the system. For example, the guard bed reactors 116 may contain catalysts, adsorbents, or other materials to remove sulfur (e.g., iron sponge, zinc oxide, or the like) and halogenated compounds.

[0078] After exiting the guard bed reactor 116, the reprocessed gas (e.g., syngas) flows to a deoxygenation ("deoxo") reactor 117. The deoxo reactor 117 removes excess oxygen from the reprocessed gas (e.g., syngas) by oxidizing the combustible compounds of the mixture (e.g., methane, carbon monoxide, hydrogen). The oxygen is converted to water. The catalyst for the deoxygenation reaction is platinum, palladium, and other active materials supported on alumina or other catalyst support materials.

[0079] System 100 includes a cooling system 150 in which a cooling fluid, e.g., cooling water, flows through cooling lines, e.g., 151. Other cooling means, e.g., direct air cooling, are also contemplated.

[0080] After exiting the deoxo reactor 117, the reprocessed gas (e.g., synthesis gas) flows to a heat exchanger 120c. The reprocessed gas (e.g., synthesis gas) then flows from the heat exchanger 120c to a moisture removal unit 118, such as a water knockout drum, demister, dryer, membrane, cyclone, desiccant, or similar device, where moisture is removed from the reprocessed gas (e.g., synthesis gas). Typically, the reprocessed gas (e.g., synthesis gas) exiting unit 118 should contain less than about 5%, less than about 2%, less than about 1%, or less than about 0.1% moisture by weight.

[0081] The overall (schematic) reaction for the partial oxidation of a rich fuel-air mixture to synthesis gas is given by: ФCH4+ 2[O2+ 3.76N2] → aCO + bH2+ cCO2+ dH2O + 7.52N2 The stoichiometric coefficients a, b, c, and d are determined by chemical reaction kinetics, conservation of atomic species, and reaction conditions.

[0082] In addition to synthesis gas, trace components in the gas exiting the reformer may include water vapor, carbon dioxide, and various unburned hydrocarbons.

[0083] After leaving unit 118, the dry reprocessed gas (e.g., synthesis gas) is sent to synthesis stage 102. In stage 102, the dry reprocessed gas (e.g., synthesis gas) flows to assembly 130. Assembly 130 adds hydrogen to the dry reprocessed gas (e.g., synthesis gas) in a controlled manner from line 131. In this way, the ratio of the components of the synthesis gas is adjusted and controlled to a predetermined ratio. Hydrogen is provided from hydrogen separation unit 139. The ratio-adjusted dry reprocessed gas (e.g., synthesis gas) leaves assembly 130 and flows to compressor 132. Compressor 132 compresses the regenerated gas (e.g., synthesis gas) to an optimal pressure for use in synthesis unit 133 as taught and disclosed herein. The optional synthesis unit 133 is a two-stage unit with a first reactor unit 133a and a second reactor unit 133b. Each reactor is a pressure vessel in which process gas flows through a catalyst bed in an exothermic reaction. The catalyst bed tubes are typically submerged in a pool of cooling water at controlled temperature and pressure. The synthesis unit 133 also includes a heat exchanger 120e.

[0084] The synthesis unit 133 converts the ratio-adjusted dry reprocessed gas (e.g., synthesis gas) into value-added products (e.g., methanol, ethanol, mixed alcohols, ammonia, dimethyl ether, FT liquids, and other fuels or chemicals). The value-added products (e.g., methanol, etc.) enter heat exchanger 120d. The value-added products (e.g., methanol, etc.) enter recovery unit 140. Recovery unit 140 recovers the value-added products (e.g., methanol, etc.) and passes them in line 141 for sale, storage, or further processing.

[0085] Typically, the synthesis gas is compressed to a pressure of about 15 to about 100 bar, preferably 30 to 50 bar, about 25 to about 80 bar, at least about 10 bar, at least about 25 bar, at least about 50 bar, and above and below. The temperature of the compressed synthesis gas is about 150° C. to about 350° C., preferably 250° C., about 200° C. to about 300° C., about 250° C. to about 375° C., above 125° C., above 150° C., above 200° C., above 250° C., above 350° C., above 400° C., and above and below. The pressure and temperature controlled synthesis gas is fed to a reactor for converting the synthesis gas into more useful, easily transportable, and economically viable products such as methanol, ethanol, mixed alcohols, ammonia, dimethyl ether, FT liquids, and other fuels and chemicals. In a preferred embodiment, an actively cooled reactor, such as a heat exchanger reactor or a boiling water reactor, and a copper-containing catalyst, such as Cu / ZnO / Al2O3, is used to produce methanol from synthesis gas via carbon monoxide hydrogenation, carbon dioxide hydrogenation, and reverse steam shift reaction.

[0086] In general, in preferred embodiments, the characteristic length scales of the reactors used in this system are small enough (e.g., micro- or mini-channels) that they can be molded into unconventional shapes and topologies using novel 3D printing techniques for metals and other high-temperature materials, allowing compact packaging and tight control of reaction conditions. Other strategies for intensification of downstream synthesis reactions can also be explored, such as selective removal of products from the reactor in situ or in a tightly coupled manner, which can shift equilibrium-limited reactions to higher conversions. This process intensification can minimize the need for large recycle streams or allow reactions to proceed under milder conditions (e.g., lower pressures), improving the margin of safety of the process and providing other benefits.

[0087] Typically, when syngas is reacted to form higher value products, unreacted hydrogen is also produced, which can be captured and sold or used to power a gas turbine or second generator to produce additional electricity.

[0088] In general, the H2 / CO ratio of the engine-generated syngas can be tailored to the downstream conversion process. For example, for methanol synthesis and Fischer-Tropsch (FT) synthesis, the ideal H2 / CO ratio is 2-3. For ammonia synthesis and hydrogen production, the highest possible H2 / CO ratio is desired, which can be increased, for example, by adding steam to promote the water-gas shift reaction. In ammonia and hydrogen production, no CO is required in the downstream synthesis steps. Therefore, the CO and CO2 by-products can be captured, sequestered, stored, or used for other purposes.

[0089] The recovery unit 140 also has a line that passes gas separated from the value-added products (e.g., methanol) to a valve 135 for passage to a hydrogen separation unit 139, a recycle loop 136, or both. The recycle loop includes a compressor 134 and a valve 138 for returning unreacted synthesis gas to the synthesis unit 133. Hydrogen separation can be accomplished by, for example, membrane separation or pressure swing adsorption (PSA) in the hydrogen separation unit 139.

[0090] Preferably, the system and process of Figure 3 includes one or more devices and processes for reducing the compressor work. Thus, the system and process of Figure 3 can include or use one or more of: (a) reducing the amount of nitrogen; (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar; (c) using a turbo expander to recover much of the compression work, thereby reducing the cost, among other efficiencies, of operating the plant; and (d) utilizing an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressure. These devices and processes for reducing the compressor work can be used in conjunction with the system and process of Figure 3, portions of the system and process of Figure 3 (e.g., modular, integrated, and combinations thereof), and combinations and variations of this embodiment.

[0091] The overall conversion process from fuel to useful products can be explained using a TS diagram with the properties of air in the air standard approximation of the process. In FIG. 11, a temperature-entropy (TS) diagram is shown for the general operation and thermodynamics of a flare gas to methanol conversion system of the type shown in FIG. 3. The overall conversion process from waste gas, e.g. flare gas, to useful products, e.g. methanol, is explained using the TS diagram of FIG. 11. This diagram uses the properties of air in the air standard approximation of the process. FIG. 11 shows an overview of the general solution and operation of a system such as shown in FIG. 3 in terms of thermodynamics, temperature and pressure. The diagram shows the start of the process at ambient conditions, high temperature and pressure conditions for rich partial oxidation in the reformer, and high pressure and low temperature reactions for methanol synthesis. Thus, the temperature vs. entropy is shown for dashed line 201 at 60 atm, dashed line 202 at 30 atm, dashed line 203 at 8 atm, and dashed line 204 at 1 atm. (One atmosphere is equivalent to 1.013 bar.) The temperature and pressure of the inlet air (e.g., 110 in FIG. 3) and waste gas (e.g., flare gas) are at point 206 (FIG. 11). The operating conditions of the reforming stage (e.g., 101 in FIG. 3) are shown in zone 210 (FIG. 11). Zone 210 has a temperature of 900° C. or higher. Zone 210 has two subzones, 210a and 210b. Subzone 210a is a low pressure zone (below 1 bar to about 25 bar). Subzone 210b is a high pressure zone (about 20 bar to about 100 bar), especially for rich partial oxidation conditions in the reformer (e.g., 114 in FIG. 3), which are preferred conditions for embodiments of the present invention. The optimal operation of the synthesis stage (e.g., 131 in FIG. 3) is shown in zone 211 for methanol synthesis. Zone 211 has a temperature of 200-300° C. and a pressure of about 20 bar-100 bar. The preferred zone for methanol production is 200-300° C. and a pressure of 30-100 bar.

[0092] Thus, Figure 11 diagrams the conditions that might be commonly used in a system that converts flare gas to an end product (methanol in this case), preferably with a neutral (i.e., providing all the energy required to operate the system and process, or providing a positive surplus) energy balance. The specific entropy axis (horizontal axis) is in kJ / kg °C and represents the entropy per unit mass of air. This type of diagram is a convenient way to show physical processes such as compression and expansion (near-vertical lines between pressure levels) and heat exchange (usually at near-constant pressure). Ideal compression and expansion are isotropic, meaning there is no change in entropy between two pressure levels. Compression by real equipment is anisotropic, as shown by the non-vertical lines. The temperature axis (vertical axis) is in °C and represents the temperature of a fluid assumed to have similar properties to air. The relationship between the temperature and constant pressure lines is governed by the physical properties of the fluid. One advantage of the TS diagram is that it allows a visual representation of physical processes and the relationships between components.

[0093] The partial oxidation window 210 defines the temperature and pressure region where the critical partial oxidation (POX) reactions to produce synthesis gas occur. This region defines the reaction conditions that result in reaction times (typically 5-50 milliseconds) that are commensurate with the combustion residence time in the reformer (e.g., gas turbine). Typically, the POX reactions occur at much higher temperatures than the downstream synthesis (e.g., methanol) reactions, and therefore require a heat exchanger to reduce the temperature prior to the methanol reactor.

[0094] The methanol synthesis window 211 defines the temperature and pressure region where the methanol synthesis reaction occurs. This region defines the reaction conditions that result in reasonable equilibrium conversion for an equilibrium-limited reaction. In this exothermic process, low temperatures are desirable to increase equilibrium conversion, but the low temperature side is limited by sufficient catalyst activity. Higher pressures result in higher equilibrium concentrations due to a net reduction in the number of moles in the reaction, but require compression costs and design for higher pressures. Figure 11 specifically illustrates the methanol synthesis window, but it can be understood that similar conditions are required for other possible downstream synthesis reactions, such as Fischer-Tropsch synthesis.

[0095] FIG. 4 shows an embodiment of a system and method for converting flare gas to a value-added product, such as methanol. The system 1600 has a reforming stage 1601 and a synthesis stage 1602. The system 1600 has an air intake that supplies air to a compressor 1611, which compresses the air. The compressed air is supplied to a mixer through a heat exchanger. The system has a flare gas inlet. The flare gas flows to the mixer through a heat exchanger. The mixer supplies a predetermined mixture of air and waste gas to a reformer 1614, which is a reciprocating engine, as taught and disclosed herein.

[0096] The fuel-air mixture formed in the mixer is preferably rich, more preferably having an overall fuel-to-air equivalence ratio (Φ or ER) greater than 1, greater than 1.5, greater than 2, greater than 3, from about 1.5 to about 4.0, from about 1.1 to about 3.5, from about 2 to about 4.5, from about 1.1 to about 3, and greater.

[0097] It is understood that oxygen can be added to the air. Water or steam can also be injected into the air-fuel mixture or into the air or fuel alone. About 1 to about 20% (molar) water can be injected, about 10 to about 15% (molar) water, about 5 to about 17% (molar) water, more than 5% (molar) water, more than 10% (molar) water, more than 15% (molar) water, less than 25% (molar) water can be injected. After oxygen enrichment, the combustion air can contain about 21% (molar) to about 90% (molar) oxygen. As used herein, "air-breathing" reformers and air-breathing engines also include engines that use air that has been reformed with the addition of water, oxygen, or both.

[0098] The reciprocating engine 1614 partially combusts a predetermined mixture of flare gas and air to produce syngas, which passes through a heat exchanger and into a filter, such as a particulate matter filter.

[0099] After passing through the filter, the syngas flows to a guard bed reactor assembly, which optionally has two guard bed reactors. After leaving the guard bed reactors, the syngas flows to a deoxo reactor, which removes excess oxygen from the reprocessed gas (e.g., syngas).

[0100] The system includes a cooling system that uses a cooling fluid, such as cooling water, which is passed through cooling lines, although other cooling means, such as direct air cooling, are also contemplated.

[0101] After exiting the deoxo reactor, the syngas flows to a heat exchanger where the gas is cooled. The reprocessed gas (e.g., syngas) flows from the heat exchanger to a moisture removal unit (e.g., water knockout drum, demister, dryer, membrane, cyclone, desiccant, etc.) where moisture is removed from the syngas. Typically, the syngas leaving the moisture removal unit should contain less than about 5%, less than about 2%, less than about 1%, or less than about 0.1% moisture by weight.

[0102] After leaving the moisture removal unit, the dried syngas enters the synthesis stage 1602. In stage 1602, the dried syngas flows into an assembly that controls the addition of hydrogen-rich gas to the dried syngas. In this way, the ratio of the components of the syngas is adjusted and controlled to a predetermined ratio. Hydrogen is provided from the hydrogen separation unit 1639. The ratio-adjusted dry syngas leaves the assembly and flows into a compressor 1632. The compressor 1632 compresses the syngas to an optimal pressure for use in the synthesis unit 1633 (which is an optional two-stage unit and includes a first reactor unit 1633a and a second reactor unit 1633b) as taught and disclosed herein. The synthesis unit 1633 also includes a regenerative heat exchanger.

[0103] The synthesis unit 1633 converts the regulated dry syngas into value-added products, such as methanol, which flows into a heat exchanger (i.e., a cooler) and then flows into a recovery unit 1640, which recovers the condensed methanol and passes it through a line for sale, storage, or further processing.

[0104] The recovery unit 1640 also has a line through which the unreacted gases separated from the methanol flow to a T-connector from which they can be sent to the hydrogen separation unit 1639, to a recycle loop, or both, which includes a compressor and valves to return the methanol to the synthesis unit 1633.

[0105] Preferably, the system and process of FIG. 4 operates as described above under the conditions shown in FIG. 5. In an embodiment, the system and process of FIG. 4 can include one or more devices and processes for reducing the compressor work. Thus, the system and process of FIG. 4 can have or use one or more of: (a) reducing the amount of nitrogen; (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar; (c) using a turbo expander to recover most of the compression work and reduce the cost to run the plant along with other efficiencies; and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressures. These compressor work reduction devices and processes can be used with the system and process of FIG. 4, e.g., modular, integrated, and combinations thereof, and combinations and variations of this combination method are also possible.

[0106] Referring to Figure 6, an embodiment of a system and method for converting flare gas to a value-added product, such as methanol, is shown. The system 1800 is configured to reduce the required compression work by increasing the engine back pressure above ambient pressure, up to about 5 bar.

[0107] The system 1800 includes a reforming stage 1801 and a synthesis stage 1802. The system 1800 includes an air intake that feeds air into a compressor 1811 that compresses the air. The compressed air is fed to a mixer through a heat exchanger. The system includes a flare gas intake. The flare gas flows through a heat exchanger 1820b to a mixer 1813. The mixer 1813 feeds a predetermined mixture of air and waste gas to a reformer 1814, which is a reciprocating engine, as taught and disclosed herein.

[0108] The fuel-air mixture formed in the mixer is preferably rich, more preferably having an overall fuel-to-air equivalence ratio (Φ or ER) greater than 1, greater than 1.5, greater than 2, greater than 3, from about 1.5 to about 4.0, from about 1.1 to about 3.5, from about 2 to about 4.5, from about 1.1 to about 3, and greater.

[0109] It is understood that oxygen can be added to the air. Water or steam can also be injected into the air-fuel mixture or into the air or fuel alone. About 1 to about 20% (molar) water can be injected, about 10 to about 15% (molar), about 5 to about 17% (molar), more than 5% (molar), more than 10% (molar), more than 15% (molar), or less than 25% (molar). After oxygen enrichment, the combustion air can contain about 21% (molar) to about 90% (molar) oxygen. As used herein, "air-breathing" reformers and air-breathing engines also include engines that use air that has been reformed with the addition of water, oxygen, or both.

[0110] The reciprocating engine 1814 partially combusts a predetermined mixture of flare gas and air to produce syngas, which passes through a heat exchanger and into a filter, such as a particulate filter.

[0111] After passing through the filter, the syngas flows to a guard bed reactor assembly, which optionally has two guard bed reactors. After exiting the guard bed reactors, the syngas flows to a deoxo reactor, which removes excess oxygen from the reprocessed gas (e.g., syngas).

[0112] The system includes a cooling system that uses a cooling fluid, such as cooling water, which is passed through cooling lines, although other cooling means, such as direct air cooling, are also contemplated.

[0113] After exiting the deoxo reactor, the syngas flows to a heat exchanger for cooling. The reprocessed gas (e.g., syngas) flows from the heat exchanger to a moisture removal unit (e.g., water knockout drum, demister, dryer, membrane, cyclone, desiccant, etc.) where moisture is removed from the syngas. Typically, the syngas leaving the moisture removal unit should contain less than about 5%, less than about 2%, less than about 1%, or less than about 0.1% moisture by weight.

[0114] After leaving the moisture removal unit, the dried syngas enters the synthesis stage 1802. In stage 1802, the dried syngas flows to an assembly that controls the addition of hydrogen-rich gas to the dried syngas. In this way, the ratio of the components of the syngas is adjusted and controlled to a predetermined ratio. Hydrogen is provided from a hydrogen separation unit 1839. The ratio-adjusted dry syngas leaves the assembly and flows to a compressor 1832. The compressor 1832 compresses the syngas to an optimal pressure for use in the synthesis unit 1833 (which is an optional two-stage unit and includes a first reactor unit 1833a and a second reactor unit 1833b) as taught and disclosed herein. The synthesis unit 1833 also includes a regenerative heat exchanger.

[0115] The synthesis unit 1833 converts the regulated dry syngas into value-added products, such as methanol, which flows into a heat exchanger (i.e., a chiller) and then flows into a recovery unit 1840, which recovers the condensed methanol and routes it to a line for sale, storage, or further processing.

[0116] The recovery unit 1840 also has a line that carries the unreacted gases separated from the methanol to a T-connector from which they are sent to the hydrogen separation unit 1839, the recycle loop, or both. The recycle loop has a compressor and valves to return the methanol to the synthesis unit 1833.

[0117] Stage 1802 includes a line 1883 for recovering spent methanol from unit 1833b and sending it to heat exchanger 1820d. Stage 1802 includes a methanol desorber 1880 with a pump 1881. A line 1882 for the desorber 1880 passes the methanol-rich product to heat exchanger 1820g.

[0118] In operation of the system 1800, the preferred process uses a two-stage methanol synthesis reactor with reactive separation only in the second stage (Rxtr2) 1833b. The first stage (Rxtr1) 1833a is generally far from equilibrium and reactive separation is not guaranteed. The examples shown in this diagram are reactive absorption with liquid sweep or membrane separation. Methanol is selectively removed from the reactor, producing a methanol-depleted gas stream containing mostly unreacted syngas and a methanol-rich absorbent stream. Compared to other embodiments, the main recycle loop is not used due to the improved single-pass conversion. The methane-rich absorbent liquid is passed through a valve to reduce pressure and desorb the methanol. The desorbed methanol is condensed and sent to the product stream. The regenerated absorbent liquid is pumped back to the synthesis reactor pressure and recycled to the reactor. Because the absorbent liquid is nearly incompressible, the pumping work for the absorbent liquid is minimized compared to the work of the compressor for the syngas. The reactor can be a trickle bed or membrane reactor (permeate side) with the absorbent. Methanol that does not partition into the absorbent is condensed from the gas phase in a downstream separation step and mixed with the methanol product stream.

[0119] In an embodiment, the system and process of FIG. 6 may include one or more of the devices and processes for reducing the compressor work. Thus, the system and process of FIG. 6 may include or use one or more of the following: (a) reducing the amount of nitrogen, (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar, (c) using a turbo expander to recover most of the compression work, thereby reducing the cost to operate the plant along with other efficiencies, and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressures. These compressor work reduction devices and processes may be used with the system and process of FIG. 6 as part of the system and process of FIG. 6, e.g., modular, integrated, and combinations thereof, and in combinations and variations of this association.

[0120] In an embodiment, the system and process utilizes reactive separation. The system and process generally uses a two-stage methanol synthesis reactor with reactive separation only in the second stage (Rxtr2). The first stage (Rxtr1) is generally far from equilibrium and reactive separation is not guaranteed. The system performs reactive absorption with liquid sweep or membrane separation. Methanol is selectively removed from the reactor to produce a methanol-depleted gas stream containing primarily unreacted synthesis gas and a methanol-rich absorbent stream. Due to the improved single-pass conversion compared to other systems such as that shown in FIG. 3, a main recycle loop may not be, and preferably is not, required. The methane-rich absorbent passes through a valve to reduce pressure and desorb the methanol. The desorbed methanol is condensed and sent to the product stream. The regenerated absorbent is pumped back to the synthesis reactor pressure and recycled to the reactor. Because the absorbent is nearly incompressible, pumping work for the absorbent is minimized compared to the work of the compressor for the synthesis gas. The reactor may be of the trickle bed type or a membrane reactor with an absorbent liquid (sweep) on the permeate side of the membrane. Methanol that does not partition to the absorbent liquid is condensed from the vapor phase in a downstream separation step and mixed with the methanol product stream. The system and process may also include one or more devices and processes to reduce the compressor work load.

[0121] Referring to FIG. 7, an embodiment of a system and method for converting flare gas to a value-added product, such as methanol, is shown. The system 1900 includes a reforming stage 1901 and a synthesis stage 1902. The system 1900 includes an air intake that provides intake air to a compressor 1911, which compresses the air. The compressed air is provided to a mixer through a heat exchanger. The system includes a flare gas inlet. The flare gas flows through a heat exchanger 1920b to a mixer 1913. The mixer 1913 provides a predetermined mixture of air and waste gas to a reformer 1914, which is a reciprocating engine, as taught and disclosed herein.

[0122] The fuel-air mixture formed in the mixer is preferably rich, more preferably having an overall fuel-to-air equivalence ratio (Φ or ER) greater than 1, greater than 1.5, greater than 2, greater than 3, from about 1.5 to about 4.0, from about 1.1 to about 3.5, from about 2 to about 4.5, from about 1.1 to about 3, and greater.

[0123] It is understood that oxygen can be added to the air. Water or steam can also be injected into the air-fuel mixture or into the air or fuel alone. About 1 to about 20% (molar) water can be injected, about 10 to about 15% (molar), about 5 to about 17% (molar), more than 5% (molar), more than 10% (molar), more than 15% (molar), less than 25% (molar), water can be injected. After oxygen enrichment, the combustion air can contain about 21% (molar) to about 90% (molar) oxygen. As used herein, "air-breathing" reformers and air-breathing engines also include engines that use air that has been reformed with the addition of water, oxygen, or both.

[0124] The reciprocating engine 1914 partially combusts a predetermined mixture of flare gas and air to produce syngas, which passes through a heat exchanger and into a filter, such as a particulate filter.

[0125] After passing through the filter, the syngas flows to a guard bed reactor assembly, which optionally includes two guard bed reactors. After exiting the guard bed reactors, the syngas flows to a deoxo reactor, which removes excess oxygen from the reprocessed gas (e.g., syngas).

[0126] The system includes a cooling system that uses a cooling fluid, such as cooling water, which is passed through the cooling lines. Other cooling means, such as direct air cooling, are also contemplated.

[0127] After exiting the deoxo reactor, the syngas flows to a heat exchanger where the gas is cooled. The treated gas (e.g., syngas) then flows from the heat exchanger to a moisture removal unit (e.g., water knockout drum, demister, dryer, membrane, cyclone, desiccant, etc.) where moisture is removed from the syngas. Typically, the syngas leaving the moisture removal unit should contain less than about 5%, less than about 2%, less than about 1%, or less than about 0.1% moisture by weight.

[0128] After leaving the moisture removal unit, the dried syngas enters the synthesis stage 1902. In stage 1902, the dried syngas flows from a line to an assembly that controls the addition of hydrogen-rich gas to the dried syngas. In this way, the ratio of the components of the syngas can be adjusted and controlled to a predetermined ratio. Hydrogen is provided from a hydrogen separation unit 1939. The ratio-adjusted dried syngas leaves the assembly and flows to a compressor 1932. The compressor 1932 compresses the syngas to an optimal pressure for use in the synthesis unit 1933 (an optional two-stage unit, comprising a first reactor unit 1933a and a second reactor unit 1933b) as taught and disclosed herein. The synthesis unit 1933 also comprises a regenerative heat exchanger 1920e.

[0129] The synthesis unit 1933 converts the regulated dry syngas into value-added products, such as methanol, which flows into a heat exchanger (i.e., a cooler) and then flows into a recovery unit 1940, which recovers the condensed methanol and routes it to a line for sale, storage, or further processing.

[0130] The recovery unit 1940 also has a line that carries the unreacted gases separated from the methanol to a T-connector from which they are sent to the hydrogen separation unit 1939, the recycle loop, or both. The recycle loop has a compressor and valves to return the methanol to the synthesis unit 1933.

[0131] Stage 1902 includes a line 1983 for removing lean methanol from unit 1933b and sending it to heat exchanger 1920d. Stage 1902 includes a line 1987 for removing wet product from unit 1833b.

[0132] System 1900 is for a by-product gas liquefaction process with reactive separation. The process uses a two-stage methanol synthesis reactor with reactive separation only in the second stage (Rxtr2) 1933b. The first stage (Rxtr1) 1833a is generally far from equilibrium and reactive separation is not guaranteed. The example shown in this diagram is membrane separation with gas scrubbing. Water (a by-product of methanol production by CO2 hydrogenation) is selectively removed in situ from reactor 1833b (via line 1987), resulting in a water-depleted gas stream containing primarily unreacted synthesis gas and water-rich scrubbing gas. In this embodiment, a primary recycle loop is not used due to the improved single-pass conversion. Additionally, in this embodiment, no regeneration of a sweep stream (e.g., air in this embodiment) is performed. The membrane reactor can use a polymeric or ceramic membrane material that is permselective to water and the scrubbing gas (e.g., air) on the permeate side of the membrane. Removal of water shifts the equilibrium towards the products. Because the reverse water-gas shift reaction converts CO2 to CO, this approach also helps convert CO2 to the more reactive CO. Therefore, this approach is particularly attractive for CO2-rich synthesis gas streams, such as those produced by partial oxidation. Methanol is condensed from the gas phase in a downstream separation step and combined with the methanol product stream.

[0133] In an embodiment, the system and process of FIG. 7 may include one or more of the devices and processes for reducing the compressor work. Thus, the system and process of FIG. 7 may include or use one or more of the following: (a) reducing the amount of nitrogen; (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar; (c) using a turbo expander to recover most of the compression work, thereby reducing the cost to operate the plant along with other efficiencies; and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressures. These compressor work reduction devices and processes may be used as part of the system and process of FIG. 7, e.g., modular, integrated, and combinations thereof, and in combinations and variations of this association, with the system and process of FIG. 7.

[0134] In an embodiment, the system and process utilize reactive separation of the by-products. In this process, a two-stage methanol synthesis reactor is used, with reactive separation occurring only in the second stage (Rxtr2). The first stage (Rxtr1) is generally far from equilibrium and reactive separation is not guaranteed. The example shown in this figure is membrane separation with gas scrubbing. Water (a by-product of the hydrogenation of CO2 to produce methanol) is selectively removed in situ from the reactor, resulting in a water-depleted gas stream that contains primarily unreacted synthesis gas and water-rich sweep gas. Compared to other systems, such as that shown in Figure 3, a primary recycle loop is not, and preferably is not, required due to the improved single-pass conversion. Furthermore, compared to other embodiments, such as that shown in Figure 6, regeneration of the sweep stream (e.g., air in this embodiment) may not, and preferably is not, required. The membrane reactor can use polymeric or ceramic membrane materials that are permselective to water and permselective to the sweep gas (e.g., air) on the permeate side of the membrane. Removal of water shifts the equilibrium to the product side. This approach also serves to convert CO2 to the more reactive CO, since the reverse water-gas shift reaction converts CO2 to CO. Therefore, this approach is particularly attractive for CO2-rich synthesis gas streams, such as those produced by partial oxidation. Methanol is condensed from the gas phase in a downstream separation step and combined with the methanol product stream. The system and process may include one or more devices and processes to reduce the compressor work load.

[0135] Referring to FIG. 8, an embodiment of a system and method for converting flare gas to value-added products is shown. The system 800 includes a reforming stage 801 and a synthesis stage 802. The system 800 includes an air intake 810 that feeds air to a compressor 811 that compresses the air. The compressed air is fed to a mixer 813 through a heat exchanger 820a. The system has a flare gas intake 884. The flare gas flows to the mixer 813 through a heat exchanger 820b. The mixer 813 feeds a predetermined mixture of air and flare gas to a reciprocating engine, the reformer 814, as disclosed and described in more detail herein.

[0136] The fuel-air mixture formed in mixer 813 is preferably rich, more preferably having an overall fuel-to-air equivalence ratio (Φ or ER) greater than 1, greater than 1.5, greater than 2, 3, about 1.5 to about 4.0, about 1.1 to about 3.5, about 2 to about 4.5, about 1.1 to about 3, and higher.

[0137] It is understood that oxygen can be added to the air. Water or steam can also be injected into the air-fuel mixture or into the air or fuel alone. About 1 to about 20% (molar) water can be injected, about 10 to about 15% (molar), about 5 to about 17% (molar), more than 5% (molar), more than 10% (molar), more than 15% (molar), and less than 25% (molar). After oxygen enrichment, the combustion air can contain about 21% (molar) to about 90% (molar) oxygen. As used herein, "air-breathing" reformers and air-breathing engines also include engines that use air that has been reformed with the addition of water, oxygen, or both.

[0138] The reciprocating engine 814 partially combusts a predetermined mixture of flare gas and air to form syngas, which passes through heat exchangers 820a, 820b and into filter 815, which may be, for example, a particulate filter.

[0139] After passing through filter 815, the syngas flows to a guard bed reactor assembly 816, which optionally comprises two guard bed reactors 816a, 816b. The guard bed reactors 816 contain materials, such as catalysts, to remove contaminants and other substances from the syngas that may adversely affect, inhibit, or poison subsequent equipment or processes in the system. For example, the guard bed reactors 816 may contain catalysts or other materials to remove sulfur (e.g., iron sponge, zinc oxide, or the like) and halogenated compounds.

[0140] After exiting guard bed reactor 816, the syngas flows to deoxo reactor 817. In deoxo reactor 817, excess oxygen is removed from the reprocess gas (e.g., syngas) by oxidizing combustible compounds in the mixture, such as methane, carbon monoxide, and hydrogen, and the oxygen is converted to water. Catalysts for the deoxo reaction are platinum, palladium, and other active materials supported on alumina or other catalyst support materials.

[0141] System 800 includes a cooling system 850 that uses a cooling fluid, such as cooling water, which is passed through cooling lines, such as 851. Other cooling means are also contemplated, such as direct air cooling.

[0142] After exiting the deoxo reactor 817, the syngas flows to heat exchanger 820c, where the gas is cooled. The treated gas (e.g., syngas) then flows from heat exchangers 820f and 820c to a moisture removal unit 818, such as a water knockout drum, demister, dryer, membrane, cyclone, desiccant, or the like, where moisture is removed from the syngas. Typically, the syngas exiting unit 818 should contain less than about 5%, less than about 2%, less than about 1%, or less than about 0.1% moisture by weight.

[0143] After leaving unit 818, the dry syngas enters synthesis stage 802. In stage 802, the dry syngas flows to assembly 830, which adds hydrogen-rich gas from line 831 in a controlled manner to the dry syngas. In this way, the ratio of the syngas components can be adjusted and controlled to a predetermined ratio. Hydrogen is provided from hydrogen separation unit 839. The ratio-adjusted dry syngas leaves assembly 830 and flows to compressor 832, which compresses the syngas to an optimal pressure for use in synthesis unit 833, as taught and disclosed herein. Desirably, synthesis unit 833 is a two-stage unit with optional first reactor unit 833a and second reactor unit 833b. Synthesis unit 833 also includes a regenerative heat exchanger 820e.

[0144] Synthesis unit 833 converts the regulated dry syngas to a value-added product, methanol. The methanol flows to heat exchanger (i.e., cooler) 820d. The methanol flows to recovery unit 840. Recovery unit 840 recovers the condensed methanol and passes it in line 841 for sale, storage, or further processing.

[0145] Typically, the synthesis gas is compressed to a pressure of about 15 to about 100 bar, preferably about 30 to 50 bar, about 25 to about 80 bar, at least about 10 bar, at least about 25 bar, at least about 50 bar, and above and below. The temperature of the compressed synthesis gas is adjusted to about 150°C to about 350°C, preferably about 250°C, about 200°C to about 300°C, about 250°C to about 375°C, above 125°C, above 150°C, above 200°C, above 250°C, above 350°C, below 400°C, and above and below. The pressure and temperature controlled synthesis gas is fed to a reactor for converting the synthesis gas into more useful, easily transportable and economically exploitable products such as methanol, ethanol, ammonia, dimethyl ether, FT liquids, and other fuels and chemicals. In a preferred embodiment, an actively cooled reactor, such as a heat exchange reactor or a boiling water reactor, and a copper-containing catalyst, such as Cu / ZnO / Al2O3, is used to produce methanol from synthesis gas via CO hydrogenation, CO2 hydrogenation, and reverse steam shift reaction.

[0146] In general, in preferred embodiments, the characteristic length scales of the reactors used in this system are small enough (e.g., micro- or mini-channels) that they can be molded into unconventional shapes and topologies using novel 3D printing techniques for metals and other high-temperature materials, allowing compact packaging and tight control of reaction conditions. Other strategies for intensification of downstream synthesis reactions can also be explored, such as selectively removing products from the reactor in situ or in tightly bound form to shift equilibrium-limited reactions to higher conversions. This process intensification can minimize the need for large recycle streams or allow reactions to proceed under milder conditions (e.g., lower pressures), thereby expanding the margin of process safety and providing other benefits.

[0147] In general, the H2 / CO ratio of the syngas produced by the engine can be tailored to the downstream conversion process. For example, for methanol synthesis or Fischer-Tropsch (FT) synthesis, the ideal H2 / CO ratio is 2-3. For ammonia synthesis or hydrogen production, the highest possible H2 / CO ratio is desirable and can be increased, for example, by adding water steam to promote the water-gas shift reaction. In ammonia and hydrogen production, CO is not required for downstream synthesis. Therefore, the CO and CO2 by-products can be captured, sequestered, stored, or used for other purposes.

[0148] The recovery unit 840 also has a line that carries the gas separated from the methanol to a T-connector 835, from where it is sent to a hydrogen separation unit 839, a recycle loop, or both. The recycle loop includes a compressor 834 and a valve 838 to return the methanol to the synthesis unit 833. Hydrogen separation can be accomplished by, for example, membrane separation or pressure swing adsorption (PSA) in the hydrogen separation unit 839.

[0149] The remaining gas after hydrogen separation is sent through loop 890 and heat exchanger 820f to turboexpander 891 where the gas is exhausted. The turboexpander generates power to offset a portion of the compressor power requirements.

[0150] In one embodiment of the system of FIG. 8, the reformer 814 is a spark ignition (Otto cycle) reciprocating engine. The system may be suitably operated as shown in the TS diagram of FIG. 13. The reference points (numbered 81, 82, 83, 84, 85, 86, 87, 88, 89 in FIG. 8) correspond to process conditions, or state points, at those locations in the system of FIG. 8, which are indicated by corresponding reference points in FIG. 13. The line from state point 84a' to 84b' represents the reduction in compression ratio that occurs in response to the more reactive flare gas fuel. State point 85b is associated with the syngas leaving the syngas reformer after expansion of the turbocharger. The expansion from 85 to 85b occurs within the turbocharger. The specific entropy at the start of this process is at points 81, 82 (6.9 kJ / kg°C) and the final specific entropy point of this process is at point 89 (6.95 kJ / kg°C). Therefore, the difference between the initial and final specific entropy is 0.05 kJ / kg°C.

[0151] In one embodiment of the system of FIG. 8, the reformer 814 is a compression ignition (Diesel cycle) reciprocating engine. The system may be suitably operated as shown in the TS diagram of FIG. 14. The reference points (numbered 81, 82, 83, 84, 85, 86, 87, 88, 89 in FIG. 8) correspond to process conditions, or state points, at those locations in the system of FIG. 8, which are indicated by the corresponding reference points in FIG. 14. The line from state point 84a' to 84b' represents the reduction in compression ratio that occurs in response to the more reactive flare gas fuel. State point 85b is associated with the syngas leaving the syngas reformer after turbocharger expansion. The expansion from 85 to 85b occurs within the turbocharger. The specific entropy at the start of this process is at points 81, 82 (6.9 kJ / kg°C) and the final specific entropy point of this process is at point 89 (6.95 kJ / kg°C). Therefore, the difference between the initial and final specific entropy is 0.05 kJ / kg°C.

[0152] Preferably, the spark ignition (Otto cycle) and compression ignition (Diesel cycle) reciprocating engine embodiments of the system and process of FIG. 8 include one or more of the compressor reduction devices and processes. Thus, the system and process of FIG. 8 can include or use one or more of the following: (a) reducing the amount of nitrogen, (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar, (c) using a turbo expander to recover most of the compression work, thereby reducing the cost to operate the plant along with other efficiencies, and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressures. These compressor work reduction devices and processes can be used with the system and process of FIG. 8 as part of the system and process of FIG. 8, e.g., modular, integrated, and combinations thereof, and in combinations and variations of this association. Working Example

[0153] Below are provided examples illustrating various embodiments of waste fuel, e.g., flare gas, conversion systems, apparatus, and processes. These examples are illustrative and may be prophetic, and should not be construed as limiting the scope of the invention, nor are they otherwise limiting.

[0154] Example 1

[0155] Referring to FIG. 10, an embodiment of a turboexpander and heat exchanger system for reducing the compressor work required in a reformer-based hydrocarbon processing system such as a gas to liquefaction system is shown. The system 1000 has three stages 1100, 1200, 1300. Each stage has a compressor and turbine assembly, and a heat exchanger. Stage 1100 has a compressor 1101 driven by a turbine 1102 and a heat exchanger 1103. Stage 1200 has a compressor 1201 driven by a turbine 1202 and a heat exchanger 1203. Stage 1300 has a compressor 1301 driven by a turbine 1302 and a heat exchanger 1303. In operation, a product 600, which is typically a flue gas separated by a gas to liquefaction system, is fed to stage 1300. The product 600 can have a pressure of 50 bar or more and a temperature of less than 250° C. Product 600 flows through stages 1300, 1200, 1100 as shown. Reactant 500, which is material provided by the output of the reformer, e.g., synthesis gas, is fed to stage 1100 and flows through stages 1200 and 1300 as shown, exiting at approximately 250°C and 50 bar. Graph 1000b shows the pressure and pressure change of product 600b and reactant 500b as they pass through stages 1100a, 1200a, 1300a. Graph 1000c shows the temperature and temperature change of product 600c and reactant 500c as they pass through stages 1100a, 1200a, 1300a. The 1 and 5 on the axis of graph 1000b indicate pressure in bar.

[0156] The embodiment of Figure 10 has three stages, although one, two, four, five or more stages are contemplated. System 1000 can be an integral part of a gas liquefaction system, such as the systems of Figures 3, 4, 6, 7, or 8. It can also be a separate module (e.g., skid mounted) operatively connected (e.g., pipes, valves, control system) to the gas liquefaction system.

[0157] Example 2

[0158] In one embodiment, system 100 of Figure 3 includes a turboexpander-compressor-heat exchanger system, such as that shown in Figure 10 as compressor 132. In this embodiment, product 600 of Figure 10 is the tail gas from hydrogen separation unit 139, and reactant 500 of Figure 10 is the ratio-adjusted dry reprocessed gas (e.g., synthesis gas) exiting assembly 830.

[0159] Example 2

[0160] In one embodiment of the system 100 of Figure 3, the high pressure liquid and gas product streams are expanded through valves (or back pressure regulators) in a Joule-Thomson (substantially isothermal isobaric) expansion process. In this configuration, auxiliary power is required for compression as there is not enough power to be self-sufficient.

[0161] Example 4

[0162] In one embodiment, system 1600 of Figure 4 includes a turboexpander-compressor-heat exchanger system, such as that shown in Figure 10 as compressor 1632. In this embodiment, product 600 of Figure 10 is tail gas from hydrogen separation unit 1639, and reactant 500 of Figure 10 is ratio adjusted dry reprocessed gas (e.g., synthesis gas) that is fed to compressor 1632.

[0163] Example 5

[0164] In one embodiment, system 800 of Figure 8 includes a turboexpander-compressor-heat exchanger system, such as that shown in Figure 10 as compressor 832. In this embodiment, product 600 in Figure 10 is tail gas from hydrogen separation unit 839, and reactant 500 in Figure 10 is the ratio adjusted dry reprocessed gas (e.g., synthesis gas) exiting assembly 830. In this embodiment, turboexpander 891 may not be used, but may still be used for excess tail gas that is not used to operate the turboexpander-compressor-heat exchanger of Figure 10.

[0165] Example 6

[0166] In embodiments of the modular systems and methods of the type shown in Figures 3, 4, 6, 7, 8, or 15, the systems and methods utilize a nominal air-breathing engine operating under rich conditions and having a means for producing pressurized syngas that may be at a pressure greater than 1 bar, greater than 2 bar, greater than 3 bar, greater than 4 bar, greater than 5 bar, about 2 bar to about 5 bar, about 3 bar to about 5 bar when it leaves the engine reformer, for example, at a temperature of 40°C to 60°C, or higher or lower, with the syngas leaving the water-cooled knockout entering the compressor at about 50°C.

[0167] Example 7

[0168] In embodiments of modular systems and methods of the type shown in Figures 3, 4, 6, 7, 8, or 15, the systems and methods utilize a nominal air-breathing engine operating under rich conditions and having a means for producing pressurized syngas. Additionally, the system has a means for reducing the amount of nitrogen, such as an oxygen enrichment unit, an air separation unit, or a nitrogen removal unit that removes nitrogen from the syngas. The system may, for example, reduce the nitrogen by 10% or 20% or more.

[0169] Example 8

[0170] In an embodiment of a modular system and method of the type shown in Figures 3, 4, 6, 7, 8, or 15, the system and method utilizes a nominal air-breathing engine operating under rich conditions and having a means for producing pressurized synthesis gas. The system further includes a turboexpander or expansion turbine, such as a turbine drive shaft, that uses the excess high pressure gas to expand and produce work. In this system, for example, the turbine inlet is about 50 bar and the turbine outlet is about 3 bar.

[0171] Example 9

[0172] In embodiments of modular systems and methods of the type shown in Figures 3, 4, 6, 7, 8, or 15, the systems and methods utilize a nominal air-breathing engine operating under rich conditions and having a means for generating pressurized synthesis gas. Additionally, the system includes an enhanced synthesis loop for methanol synthesis at lower pressures, including reactive separation of products or by-products. In this system, for example, the conversion rate of single pass methanol synthesis is increased by 5% or 10%, or more or less.

[0173] Example 10

[0174] In one embodiment, the exhaust back pressure of the engine reformer is increased to reduce the downstream synthesis gas compression requirements. It is expected that the exhaust pressure can be reasonably increased from a typical value near atmospheric pressure (about 1 bar) to 5 bar or more. Considering that the downstream synthesis pressure is typically set at 50 bar, increasing the exhaust back pressure of the engine reformer reduces the overall pressure ratio required to compress the synthesis gas, reducing the compressor work (kJ / kg) or power (kW). Since the engine reformer is self-supporting, increasing the exhaust back pressure does not directly affect the upstream compression work. However, increasing the back pressure affects the engine volumetric efficiency and the engine net pulling power. Considering these trade-offs, an optimal back pressure of an intermediate value is suggested. The back pressure is determined by the flow resistance of the downstream process. Various improvements in the engine reformer (e.g., turbocharging the engine reformer inlet air, modifying the engine valve timing to reduce or eliminate valve overlap) are expected to maintain acceptable engine performance with increasing exhaust back pressure.

[0175] Example 11

[0176] In one embodiment, reactive separation is used to selectively remove the reaction product (or by-product) to shift the equilibrium towards the product according to Le Chatelier's principle. The product (e.g., methanol) or by-product (e.g., water) is removed from the synthesis reactor in situ or in a tightly coupled manner. Tightly coupled means separation in the loop without expensive and energy intensive downstream separation. Separation can be done by adsorption, absorption, membrane separation, distillation, etc. Reactive separation allows good single pass conversion and reduces or eliminates the need for energy intensive and capital intensive separation and recycle loops. More importantly, in this solution aspect, reactive separation eliminates the need to increase the reactor pressure, which results in a reduction in the compression work required for the process. Adsorption separation can use various adsorbents (e.g., silica alumina) that are selective for methanol or water, and various adsorption devices (e.g., packed bed, moving bed, moving bed simulator). Absorption separation can use a variety of absorbents (e.g., tetraethylene glycol dimethyl ether, commonly TGDE or tetraglyme, or squalane) in a variety of absorption devices (e.g., trickling bed, bubble column). Membrane separation can use a variety of polymeric materials (e.g., sulfonated tetrafluoroethylene-based fluoropolymer copolymers such as Nafion®) or ceramic materials (e.g., zeolites) to separate and remove methanol or water in a variety of membrane module configurations (e.g., hollow fiber bundles, spiral type, plate type). Optionally, membrane separation can be performed using a sweep stream of gas (e.g., air) or liquid (e.g., TGDE) on the permeate side. Reactive distillation (RD) can also be used to selectively remove methanol from reactants based on differences in volatility. Optional RD can use a variety of modified (e.g., divided wall column distillation) or hybrid (e.g., extractive distillation with TGDE, etc.) distillation approaches.

[0177] Example 12

[0178] In one embodiment, reactive separation is used to selectively remove the reaction product (or by-product) to shift the equilibrium towards the product according to Le Chatelier's principle. The product (e.g., methanol) or by-product (e.g., water) is removed from the synthesis reactor in situ or in a tightly coupled manner. Tightly coupled means separation in the loop without expensive and energy intensive downstream separation. Separation can be done by adsorption, absorption, membrane separation, distillation, etc. Reactive separation allows good single pass conversion and reduces or eliminates the need for energy intensive and capital intensive separation and recycle loops. More importantly, in this solution aspect, reactive separation eliminates the need to increase the reactor pressure, which results in a reduction in the compression work required for the process. Adsorption separation can use various adsorbents (e.g., silica alumina) that are selective for methanol or water, and various adsorption devices (e.g., packed bed, moving bed, moving bed simulator). Absorption separation can use a variety of absorbents (e.g., tetraethylene glycol dimethyl ether, commonly TGDE or tetraglyme, or squalane) in a variety of absorption devices (e.g., trickling bed, bubble column). Membrane separation can use a variety of polymeric materials (e.g., sulfonated tetrafluoroethylene-based fluoropolymer copolymers such as Nafion®) or ceramic materials (e.g., zeolites) to separate and remove methanol or water in a variety of membrane module configurations (e.g., hollow fiber bundles, spiral type, plate type). Optionally, membrane separation can be performed using a sweep stream of gas (e.g., air) or liquid (e.g., TGDE) on the permeate side. Reactive distillation (RD) can also be used to selectively remove methanol from reactants based on differences in volatility. Optional RD can use a variety of modified (e.g., divided wall column distillation) or hybrid (e.g., extractive distillation with TGDE, etc.) distillation approaches.

[0179] Example 13

[0180] A small scale plant targets an inlet gas flow rate of 3,000,000 standard cubic feet per day (scfd). Such plants can range in size from 50,000 scfd to 15,000,000 scfd. The plants are built on one or more modular, interconnected skids or containers that are assembled in a central fabrication facility and then installed on-site. The system is comprised of a small number of modules that, when connected on-site, become an integrated system. The modular assembly allows for a range of inlet gas supply volumes and allows for application in remote locations with minimal on-site labor. The modular nature allows for greater flexibility in the deployment and redeployment of these assets, reduces initial capital expenditures and project financial risk, allows for matching process throughput to flare gas supply volumes, and accelerates time to market by parallel module fabrication and site preparation. The plant has one or more of the following features: (a) reducing the amount of nitrogen; (b) increasing the engine back pressure from the standard 1 or 2 bar to up to 5 bar; (c) using a turbo expander to recover most of the compression work, reducing the plant's operating costs; and (d) using an enhanced synthesis loop to achieve acceptable methanol synthesis at lower overall pressures.

[0181] Example 14

[0182] In an embodiment of the system including the components described in Examples 10 and 12, a complete system that is balanced in terms of mass flow and energy is shown in FIG.

[0183] Referring to FIG. 15 and FIGS. 15A-15C, a schematic of a system and process utilizing the embodiments of Examples 10 and 13 in a gas to liquefaction system 1400 is shown. The system and process 1400 has a reformer subsystem 1440, a methanol subsystem 1460, and a turboexpander (e.g., turbocompressor) subsystem 1480. A close-up of the reformer subsystem 1440 (and other components) is shown in FIG. 15A. A close-up of the methanol subsystem 1460 is shown in FIG. 15B. A close-up of the turboexpander subsystem 1480 is shown in FIG. 15C. (Lines or pipes A, B, C, D provide fluid flow and fluid communication between the three subsystems.)

[0184] 15A, the reformer subsystem 1440 has an air intake 1445 for receiving a flow of air and a hydrocarbon gas intake 1446 (e.g., a flare gas intake) for receiving a flow of hydrocarbon gas (e.g., a flare gas). The reformer subsection includes a supercharger 1441, an air preheater 1442, an air-breathing reformer 1449, a mixer 1444, and a desulfurization unit 1447. Additionally, a deoxo unit 1433 is shown on the line from the reformer subsystem 1440 to the turboexpander subsystem 1480. The arrows indicate the direction of flow in the system and process.

[0185] Referring to FIG. 15B, the methanol synthesis subsystem 1460 includes a compressor 1461, a mixer 1462, a CO2 membrane unit 1463, and a hydrogen membrane unit 1464. The subsystem 1460 includes a reactor unit 1469, a heat exchanger 1474. The subsystem 1460 further includes heat exchangers 1471, 1472, a methanol condenser 1465, and a methanol degasser 1466. The system includes a tail gas oxidation unit 1467 with supply air 1468 and associated heat exchanger 1475. The system 1460 includes a compressor 1473, a heat exchanger 1474, and a mixer 1470. The system includes arrows indicating the flow direction of the system and process.

[0186] Referring to FIG. 15C, the turbo expander subsystem 1480 includes a heat exchanger 1481, a heat exchanger 1481, and a knock out drum 1483. The subsystem 1480 further includes a compressor 1484 and a turbine 1485. The turbine (turbo expander) 1485 also includes a balance valve 1486 and a mixer 1487. The subsystem 1480 includes a heat exchanger 1488 and a water knock out drum 1439. The subsystem 1480 includes a compressor 1490 and a turbine (turbo extractor) 1493 with associated balance valve 1491 and heat exchanger 1492. The subsystem 1480 also has a splitter 1494, a heat exchanger 1495, a heat exchanger 1496, and a water knock out drum 1497. The system includes arrows indicating the direction of flow in the system and process.

[0187] The system uses high pressure streams from the chemical process and the thermal energy (heat) available in the process to produce shaft work through a turbo expander. This shaft work drives the first compression system for the incoming process fluid. Additional turbine work is produced by adding reheat between stages on the turbine side. Compression work is reduced by intercooling between the compression stages. A separate bypass (wastegate) control valve is used to control the turbo compressor. The outlet pressure of the first compression system is matched to the outlet pressure of the retentate gas (exhaust gas) from the hydrogen separation unit, allowing the streams to be combined in one compressor to boost the pressure up to the pressure required for the methanol process. The turbo compressor system requires an external shaft power of 98 kW, for example from an electric motor, for a system that typically processes 58 kg / h of hydrocarbon gas. e from 60kW e The condensing temperature of the process fluid is increased from 30°C to 60°C, resulting in a chiller load of 258kW. th from 20kW th is reduced to.

[0188] It is not necessary to provide or explain the theory underlying any new and innovative production rates, performance, or other beneficial features or characteristics that are the subject of or related to the embodiments of the present invention. However, various theories are presented herein to further advance the art in this important field, particularly in the field of hydrocarbon exploration, production, and downstream conversion. These theories, although presented herein, do not limit, restrict, or narrow the scope of protection afforded to the invention as claimed, unless expressly stated otherwise. These theories are not required or practiced in order to utilize the present invention. It is further understood that the present invention may lead to new, previously unknown theories that explain the operation, activities, resource generation, chemistry, and functional characteristics of the embodiments of the methods, articles, materials, apparatus, and systems of the present invention. Also, such subsequently developed theories shall not limit the scope of protection afforded to the present invention.

[0189] Various embodiments of the apparatus, systems, activities, methods, and operations described herein may be used in, with, within, or by various processes, industries, and operations, in addition to the embodiments of the figures and those disclosed herein. Various embodiments of the apparatus, systems, methods, activities, and operations described herein may be used with other processes, industries, and operations that may be developed in the future. They may also be used with existing processes, industries, and operations that may be modified based on the teachings herein. They may also be used with other types of gas recovery and value stabilization systems and methods. Furthermore, various embodiments of the apparatus, systems, activities, methods, and operations described herein may be used with each other in different combinations. Thus, for example, the configurations described in various embodiments herein may be used with each other. For example, the components of an embodiment having A, A', and B and the components of an embodiment having A', C, and D may be used alone or with each other in various combinations according to the teachings herein, such as A, C, D, and A, A', C, D, and A', B, and D. Therefore, the scope of protection given to the present invention should not be limited to the specific embodiments, configurations, or arrangements described in the specific embodiments, examples, or embodiments in the specific figures.

[0190] The present invention may be embodied in forms other than those specifically disclosed herein without departing from its spirit or substantial characteristics, and the embodiments described herein are to be considered in all respects only as illustrative and not restrictive.

Claims

1. 1. A method for converting a gas into an end product, comprising: a. receiving a stream of a hydrocarbon-based fuel source having a composition primarily of gaseous hydrocarbons and inert gases from a source; b. Partially oxidizing the fuel source in an air-breathing reciprocating engine to produce liquid synthetic H ２ generating a synthesis gas mixture having a CO / H2 ratio; c. performing a step of reducing the work of the compressor; A method comprising:

2. The method of claim 1 , wherein the step of reducing the compressor work comprises reducing the amount of nitrogen.

3. 2. The method of claim 1, wherein the step of reducing compressor work includes increasing back pressure in the air-breathing reciprocating engine.

4. 4. The method of claim 3, wherein the back pressure is increased to 5 bar.

5. The method of claim 3, wherein the back pressure is greater than 2 bar.

6. The method of claim 1 , wherein reducing the compressor work comprises using a turboexpander and heat exchanger system.

7. The method of claim 1 , wherein the step of reducing compressor work comprises reactive separation synthesis.

8. 8. A method according to any one of claims 1 to 7, wherein the air-breathing reciprocating engine is a rich-burn engine.

9. 8. A method according to any one of claims 1 to 7, wherein the air-breathing reciprocating engine is a variable compression ratio engine.

10. 8. A method according to any one of claims 1 to 7, wherein the air-breathing reciprocating engine is a compression ignition engine.

11. 8. A method according to any one of claims 1 to 7, wherein the air-breathing reciprocating engine is a spark ignition engine.

12. 1. A system for converting a gas into an end product, comprising: a. an inlet port for receiving a flow of a hydrocarbon-based fuel source having a composition primarily of gaseous hydrocarbons and inert gases from a source; b. Partially oxidizing the fuel source to produce H suitable for synthesis of liquids ２ an inlet port in fluid communication with an air-breathing reciprocating engine adapted to produce a synthesis gas mixture having a 1:1 ratio of H2O to CO; c) a means for reducing the work of the compressor; A system comprising:

13. 13. The system of claim 12, wherein the means for reducing the compressor work comprises means for reducing the amount of nitrogen.

14. 14. The system of claim 13, wherein the means for reducing the amount of nitrogen comprises an oxygen enrichment unit.

15. The system of claim 13 , wherein the means for reducing the amount of nitrogen comprises a nitrogen removal unit.

16. 13. The system of claim 12, wherein the means for reducing compressor work comprises increased back pressure on the air-breathing reciprocating engine.

17. 17. The system of claim 16, wherein the increased back pressure is up to 5 bar.

18. 17. The system of claim 16, wherein the increased backpressure is greater than 2 bar.

19. 13. The system of claim 12, wherein the means for reducing compressor work includes using a turboexpander-compressor-heat exchanger system.

20. 20. The system of claim 19, wherein the turboexpander-compressor-heat exchanger system is configured in three stages.

21. The system of claim 19 , wherein the turboexpander-compressor-heat exchanger system comprises a compressor-turbine assembly.

22. 20. The system of claim 19, wherein the turboexpander-compressor-heat exchanger system is configured in two stages, each stage including a compressor, a turbine, and a heat exchanger.

23. 23. The system of claim 22, wherein the turboexpander-compressor-heat exchanger system is configured in three stages, each stage including a compressor, a turbine, and a heat exchanger.

24. The system of claim 12 , wherein the means for reducing compressor work comprises a reaction separation synthesis loop.

25. 25. A system as claimed in any one of claims 12 to 24, wherein the air-breathing reciprocating engine is a rich-burn engine.

26. 25. A system as claimed in any one of claims 12 to 24, wherein the air-breathing reciprocating engine is a variable compression ratio engine.

27. 25. A system as claimed in any one of claims 12 to 24, wherein the air-breathing reciprocating engine is a compression ignition engine.

28. 25. A system as claimed in any one of claims 12 to 24, wherein the air-breathing reciprocating engine is a spark ignition engine.

29. 12. The method of any one of claims 1 to 11, wherein the fuel source is flare gas.

30. 29. The system of any one of claims 12 to 28, wherein the fuel source is flare gas.

31. 13. The system of claim 12, wherein the engine is a compression ignition engine, including a diesel cycle engine, or a homogeneous charge compression ignition engine.

32. 13. The system of claim 12, wherein the engine is a spark ignition engine including an Otto cycle.

33. 13. The system of claim 12, wherein the engine is an opposed piston, free piston, linear internal combustion engine.

34. 13. The system of claim 12, wherein the engine is a crankshaft driven opposed piston internal combustion engine including a crankshaft phaser for rotating the phase of one piston relative to the phase of the other piston to vary the overall compression ratio.

35. 1. A system for converting flare gas to methanol with reduced compressor work, comprising: a. a first line for receiving a flow of air and a second line for receiving a flow of flare gas; b. first and second lines in fluid communication with the air-breathing engine reformer assembly; c. a turboexpander assembly in fluid communication with the third line, d. the engine reformer assembly is in fluid communication with the third line; e. the third line connects the engine reformer assembly with the turboexpander assembly for allowing an intermediate product from the engine reformer to flow to the turboexpander assembly; f. a turboexpander assembly in fluid communication with the fourth line, the fifth line, and the sixth line; g. a methanol synthesis assembly in fluid communication with the fourth line, the fifth line, and the sixth line; h. the fourth line connects the turboexpander to the methanol synthesis assembly for providing a first flow from the turboexpander to the methanol synthesis assembly; i. the fifth line connects the turboexpander to the methanol synthesis assembly for providing a second flow from the turboexpander assembly to the methanol synthesis assembly; j) said sixth line connects said turboexpander to said methanol synthesis assembly for providing a third flow from said methanol synthesis assembly to said turboexpander.

36. 36. The system of claim 35, wherein the intermediate product is synthesis gas.

37. 36. The system of claim 35, wherein the first stream from the turboexpander to the methanol synthesis assembly is a synthesis gas.

38. 38. The system and method of any one of claims 1 to 37, wherein the engine is a conventional spark ignition reciprocating engine that achieves a variable "effective" compression ratio by utilizing camshaft phasers that rotate intake and exhaust camshafts to affect the opening and closing of valves.

39. 38. The system and method of any one of claims 1 to 37, wherein the engine is a conventional spark ignition reciprocating engine utilizing a variable lift and / or variable duration valve train to affect the opening and closing of the valves to achieve a variable "effective" compression ratio.

40. 38. The system and method of any one of claims 1 to 37, wherein the engine includes a multi-link system in place of traditional connecting rods that rotate the crankshaft, and an actuator motor varies the endpoints of the multi-link system.

41. 36. The system and method of any one of claims 1 to 35, wherein the engine is a two-stroke engine.

42. 38. The system and method of any one of claims 1 to 37, wherein the engine is a four-stroke engine.

43. 38. The system and method of any one of claims 1 to 37, wherein engine speed is varied with engine compression ratio to achieve desired combustion and desired exhaust gas composition.

44. 38. The system and method of any one of claims 1 to 37, wherein the inlet manifold air temperature is varied with engine compression ratio to achieve desired combustion and a desired exhaust gas composition.

45. 38. The system and method of any one of claims 1 to 37, wherein the inlet manifold air pressure (e.g. boost level) is varied with engine compression ratio to achieve desired combustion and desired exhaust gas composition.

46. 38. The system and method of any one of claims 1 to 37, wherein steam or hydrogen is added to the incoming air or fuel in an amount that varies with engine compression ratio to achieve a desired combustion and a desired exhaust gas composition.

47. 47. The system and method of any one of claims 1 to 46, wherein the engine is operated under an ER of at least 1.

5.

48. 48. The system and method of any one of claims 1 to 47, wherein the engine is operated under an ER of at least about 2.

49. 49. The system and method of any one of claims 1 to 48, wherein the engine is operated under an ER of at least about 2.

5.

50. 50. The system and method of any one of claims 1 to 49, wherein the engine is operated under an ER of at least about 3.

51. 51. The system and method of any one of claims 1 to 50, wherein the engine is operated under an ER of at least about 2.

5.

52. 52. The system and method of any one of claims 1 to 51, wherein the compression ratio is controlled between 8:1 and 14:

1.

53. 53. The system and method of any one of claims 1 to 52, comprising a combination of an integrated heat exchanger, compression system components, and a heat exchanger downstream of the engine to prepare synthesis gas for the downstream synthesis reactor.

54. 54. The system and method of any one of claims 1 to 53, having a downstream synthesis reactor system downstream of the engine for producing useful liquid products.

55. 55. The system and method of any one of claims 1 to 54, wherein a cloud-based remote monitoring system including AI-trained anomaly detection dynamically monitors changes in variable valve timing to assess and respond to fuel delivery anomalies.

56. CO ２ From an e-Life Cycle Assessment perspective, approximately 40 kg CO2 is reduced per kg of final product (in this case, liquid methanol) when produced from flare gas compared to baseline liquid methanol production from pipeline natural gas. ２ e negative CO ２ 56. The system and method of any one of claims 1 to 55, resulting in e-emissions.

57. The resulting negative CO2 emissions when produced from flare gas and displacing an equivalent kg of methanol from pipeline natural gas baseline methanol. ２ The emission is about 70 kg CO per 1 kg of final product (methanol). ２ 57. The system and method of any one of claims 1 to 56, wherein:

58. The resulting negative CO2 produced from flare gas when replacing the equivalent kg of baseline methanol from coal gasification. ２ The emission is about 130 kg CO per kg of final product (methanol). ２ 58. The system and method of any one of claims 1 to 57, wherein:

59. 59. The system and method of any one of claims 1 to 58, wherein the end product comprises methanol.

60. 60. The system and method of any one of claims 1 to 59, wherein the end product comprises a material selected from the group consisting of ethanol, ammonia, dimethyl ether, and F-T liquid.

61. 61. The system and method of any one of claims 1 to 60, wherein the fuel source is flare gas from a hydrocarbon well.

62. 62. The system and method of any one of claims 1 to 61, wherein the fuel source is flare gas from an oil well.

63. 63. The system and method of any one of claims 1 to 62, wherein the fuel source is flare gas from an unconventional oil well.

64. 64. The system and method of any one of claims 1 to 63, wherein the fuel source is flare gas, the flare gas being selected from the group consisting of petrochemical processing, refining, landfills, wastewater treatment, and animal production.

65. 65. The system and method of any one of claims 1 to 64, wherein the fuel gas flow rate is from about 50,000 scfd to about 30,000,000 scfd.

66. 66. The system and method of any one of the preceding claims, wherein the fuel gas flow rate is from about 500,000 scfd to about 20,000,000 scfd.

67. 67. The system and method of any one of the preceding claims, wherein the fuel gas flow rate is from about 600,000 scfd to about 15,000,000 scfd.

68. 68. The system and method of any one of the preceding claims, wherein the fuel gas flow rate is from about 700,000 scfd to about 10,000,000 scfd.

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