Target gas capture process and system using supersonic flow

Abstract

A system for trapping a target condensable gas may include a supersonic condensation nozzle configured to receive a gas stream containing a target condensable gas component and accelerate the gas into a supersonic gas stream; at least one particle injector in the supersonic nozzle for injecting particles such that the particles are in the supersonic gas stream, whereby a target gas condensate is formed on a portion of the particles; an expansion device defining a channel having a lobe, causing the flow of particles containing the target gas condensate to generate an expansion wave to separate the flow into a first flow path in which a concentration of particles containing the target gas condensate increases and a second flow path in which a target condensable gas content of the gas decreases; and a diverter having at least a first channel, the diverter configured to collect the first flow path.

Description

[0001] Cross-citation to related applications

[0002] This application claims priority to U.S. patent application No. 63 / 447,743, filed on February 23, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a capture process of a target gas (such as CO2) using a supersonic flow, and to related equipment. Background Art

[0004] For environmental reasons, capturing carbon dioxide (CO2) from industrial processes remains a global challenge. For example, a typical 500 MW coal-fired power plant has a CO2 emission mass flow of approximately 50,000 kg / h (≈ 440,000 tons / year) (at a CO2 concentration of 12%). vol Industrial CO2 capture systems require processing of substantial volumes of gas. Various processes, technologies, and equipment have been developed to capture CO2 for storage, utilization, or sequestration. Some technologies utilize solid or liquid adsorbents or cryogenic CO2 separation.

[0005] In another application, for direct capture of CO2 from atmospheric air (CO2 concentration of 410 ppm), a plant capturing one ton of CO2 per hour at a capture rate of 50% would require a processing air flow of approximately 2,600,000 m³ / h.

[0006] Some gas separation systems utilize supersonic flow, where the gas temperature is significantly reduced, allowing one vapor component to liquefy and subsequently undergo inertial separation. Such systems typically employ eddy currents for inertial separation and are commonly used to separate water vapor and heavy hydrocarbons from natural gas during natural gas extraction. It is important to note that while such processes and systems are well suited for separating hydrocarbons due to their relatively high molecular weight, they may not be suitable for molecules such as CO2, which condenses at a lower temperature than water vapor.

[0007] Two phenomena occur at the onset of CO2 condensation: homogeneous nucleation and heterogeneous nucleation. Homogeneous nucleation spontaneously forms nanometer-sized CO2 particles that are not massive or large enough to undergo inertial separation. Heterogeneous nucleation occurs at local temperatures and pressures above those for homogeneous nucleation due to the presence of foreign nuclei. For example, water vapor already present in the gas mixture can solidify at temperatures above those for CO2 through homogeneous nucleation, forming nanometer-sized particles on which CO2 can nucleate heterogeneously. This CO2 nucleation process can then lead to further particle growth as CO2 accumulates.

[0008] Therefore, there is a need for improved CO2 capture methods, which are achieved by exploiting condensation and inertial separation of particles. Summary of the Invention

[0009] In a first aspect, a method for capturing a target condensable gas is provided, the method comprising: accelerating a gas flow containing a target condensable gas component into a supersonic gas flow in a nozzle; injecting particles so that the particles are in the supersonic gas flow, whereby the target condensable gas condenses on a portion of the particles; causing an expansion wave in the particle flow containing the target gas condensate to separate the flow into a first flow path in which the concentration of particles containing the target gas condensate is increased and a second flow path in which the target condensable gas content of the gas is reduced; and physically separating the first flow path and the second flow path.

[0010] Further, according to the first aspect, for example, the first flow path may be heated to separate the target gas condensate from the particles.

[0011] Furthermore, according to the first aspect, for example, the second flow path is discharged to the environment.

[0012] Still further, according to the first aspect, for example, the gas stream containing the target condensable gas is compressed prior to acceleration.

[0013] Furthermore, according to the first aspect, for example, the gas containing the CO2 content is collected before compression.

[0014] Further according to the first aspect, for example, injecting particles into the supersonic gas flow includes injecting particles into a converging section of a nozzle.

[0015] Further according to the first aspect, for example, injecting particles into the supersonic gas flow includes injecting particles into a throat section of a nozzle.

[0016] Further according to the first aspect, for example, injecting particles into the supersonic gas flow includes injecting particles into a diverging section of a nozzle.

[0017] Furthermore, according to the first aspect, for example, heat can be recovered from the second flow path of the gas.

[0018] Further, according to the first aspect, for example, causing the particle flow containing the target gas condensate to generate an expansion wave and physically separating the first flow path from the second flow path are performed in a first separation stage, and wherein the method also includes at least one second stage of utilizing the first flow path in which the concentration of particles containing the target gas condensate is increased, the second stage including: causing the first flow path to generate an expansion wave to separate the flow into a third flow path in which the concentration of particles containing the target gas condensate is increased and a fourth flow path in which the target condensable gas content of the gas is reduced; and physically separating the third flow path from the fourth flow path.

[0019] Still further, according to the first aspect, heat may be absorbed from the gas flow containing the target condensable gas component upstream of the nozzle, for example.

[0020] According to a second aspect, a system for capturing a target condensable gas is provided, the system comprising: a supersonic condensation nozzle configured to receive a gas flow containing a target condensable gas component and accelerate the gas into a supersonic gas flow; at least one particle injector located in the supersonic nozzle, for injecting particles so that the particles are in the supersonic gas flow, whereby target gas condensate is formed on a portion of the particles; an expansion device defining a channel having a convex angle, so that the particle flow containing the target gas condensate generates an expansion wave to separate the flow into a first flow path in which the concentration of particles containing the target gas condensate is increased and a second flow path in which the target condensable gas content of the gas is reduced; and a splitter having at least a first channel, the splitter being configured to collect the first flow path.

[0021] Further, according to the second aspect, for example, the flow splitter includes a second channel configured to collect the second flow path.

[0022] Furthermore, according to the second aspect, for example, the heating unit may be configured to heat the first flow path to separate the target gas condensate from the particles.

[0023] Furthermore, according to the second aspect, for example, the flow divider has an exhaust port for directing the second flow path to the environment.

[0024] Furthermore, according to the second aspect, for example, the second channel includes a heat exchanger for recovering heat from the second flow path.

[0025] Still further, according to the second aspect, for example, at least one compressor may compress a gas flow containing a target condensable gas component upstream of the supersonic nozzle.

[0026] Still further, according to the second aspect, for example, the passageway can collect a gas stream containing a target condensable gas component and direct it to at least one compressor.

[0027] Still further, according to the second aspect, for example, a heat exchanger may be positioned in the passage to absorb heat from the gas stream containing the target condensable gas component.

[0028] Still further, according to the second aspect, for example, the expansion device and the splitter form a first stage, the system includes at least one second stage receiving a first flow path in which the particle concentration of the target gas condensate is increased, the second stage including: a second expansion device defining a channel having a convex angle so as to generate an expansion wave in the particle flow containing the target gas condensate to separate the flow into a third flow path in which the particle concentration of the target gas condensate is increased and a fourth flow path in which the target condensable gas content of the gas is reduced; and a second splitter having at least a first channel, the splitter being configured to collect the third flow path.

[0029] According to a third aspect, a supersonic condensing nozzle is provided, comprising: an inlet end and an outlet end; a channel located between the inlet end and the outlet end, configured to receive a fluid flow containing a target condensable gas component, the geometry of the interior of the channel being defined, from the inlet end to the outlet end, by: a contraction section, wherein the cross-sectional dimension decreases in the direction of the fluid flow, for subsonic flow, an expansion section, wherein the cross-sectional dimension increases in the direction of the fluid flow, for supersonic flow; and a throat section located between the contraction section and the expansion section; wherein, based on fluid flow parameters that change according to the geometry, a condensation initiation region exists in the expansion section, in which the target condensable gas begins to condense; and wherein, relative to the direction of the fluid flow, the expansion gradient of the expansion section at the condensation initiation region is greater than the expansion gradient downstream of the condensation initiation region.

[0030] According to a fourth aspect, a device for separating particles from a supersonic particle-laden gas flow is provided, comprising: an inlet end and an outlet end; a channel for the gas flow located between the inlet end and the outlet end, the channel having a convex corner on its channel surface, so that the particle-laden gas flow generates an expansion wave from the convex corner to separate the fluid flow at the outlet into: a first flow path, located near the channel surface opposite to the convex corner and with an increased particle concentration; and a second flow path, located near the channel surface having the convex corner and with a reduced particle content of the gas.

[0031] In a fifth aspect, a system is provided, which may include the supersonic condensation nozzle of the third aspect and / or the device of the fourth aspect for capturing target condensable gas, the system comprising: a supersonic condensation nozzle, configured to receive a gas flow containing a target condensable gas component and accelerate the gas into a supersonic gas flow; at least one particle injector, located in the supersonic nozzle, for injecting particles so that the particles are in the supersonic gas flow, thereby forming target gas condensate on part of the particles; an expansion device, defining a channel with a convex angle, so that the particle flow containing the target gas condensate generates an expansion wave to separate the flow into a first flow path in which the concentration of particles containing the target gas condensate is increased and a second flow path in which the target condensable gas content of the gas is reduced; and a splitter, having at least a first channel, the splitter configured to collect the first flow path. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Reference is now made to the accompanying drawings, in which:

[0033] Figure 1 FIG. 1 is a schematic diagram of a process and system for capturing target gas CO 2 using a supersonic flow according to an embodiment of the present disclosure.

[0034] Figure 2 is a graph showing a CO2 phase diagram with an isentropic expansion curve.

[0035] Figure 3 is a schematic diagram of exemplary dimensions for a basic conical converging-diverging nozzle.

[0036] Figure 4 is a graph showing the effect of supersonic condensing nozzle design Mach number on the final achieved CO2 concentration.

[0037] Figure 5 is an exemplary graph showing the effect of supersonic condensing nozzle design Mach number on the gas-particle heat transfer coefficient.

[0038] Figure 6 is a schematic diagram illustrating an exemplary optimized supersonic condensing nozzle according to the present disclosure before the CO 2 condensation starting point in comparison with a basic conical supersonic condensing nozzle.

[0039] Figure 7 It shows Figure 6 An exemplary diagram showing the flow characteristics of the optimized supersonic condensing nozzle before the CO2 condensation starting point in the schematic diagram of FIG. 1 compared with the basic conical supersonic condensing nozzle.

[0040] Figure 8 It shows Figure 6 An exemplary diagram of the optimized supersonic condensation nozzle in the schematic diagram of FIG. 1 , before the CO2 condensation starting point, compared with the basic conical supersonic condensation nozzle based on the phase diagram of dTg / dx=3°C / m.

[0041] Figure 9 is an exemplary graph showing the mass flow rate of deposited CO2 versus the total pressure drop of the flow.

[0042] Figure 10 It shows Figure 6 An exemplary diagram of the optimized supersonic condensation nozzle in the schematic diagram of FIG. 1 , before the CO2 condensation starting point, compared with the basic conical supersonic condensation nozzle based on the phase diagram of dTg / dx=0°C / m.

[0043] Figure 11 It shows Figure 6An exemplary diagram of the optimized supersonic condensation nozzle in the schematic diagram of FIG. 1 , before the CO2 condensation starting point, compared with the basic conical supersonic condensation nozzle based on the phase diagram of dTg / dx=-0.3°C / m.

[0044] Figure 12 is an exemplary graph showing the flow characteristics of a basic conical supersonic condensing nozzle comparing particles injected at the nozzle inlet to particles injected in a controlled manner within the diverging section.

[0045] Figure 13 is an exemplary graph showing the comparison between the total pressure of the flow of a basic conical supersonic condensing nozzle injecting particles at the nozzle inlet and injecting particles in a controlled manner within the diverging section.

[0046] Figure 14 is an exemplary graph showing a phase diagram for a 100,000 tonne / year CO2 design scenario.

[0047] Figure 15 is an exemplary graph showing axial CO 2 concentration for a 100,000 ton / year CO 2 design case.

[0048] Figure 16 is an exemplary graph showing the evolution of axial particle diameter for a 100,000 t / y CO2 design case.

[0049] Figure 17 is an exemplary graph showing the total axial pressure drop for a 100,000 tonnes / year CO2 design case.

[0050] Figure 18 is an exemplary schematic diagram of the basic form of a Prandt1-Meyer expansion device.

[0051] Figure 19 is an exemplary schematic diagram of using a Prandt1-Meyer expansion device in combination with a flow splitter to remove particles from a supersonic flow.

[0052] Figure 20 is an exemplary schematic diagram showing a possible arrangement of multiple Prandtl-Meyer expansion devices.

[0053] Figure 21 is an exemplary full-scale overview of a CO2 capture facility based on the technology of the present disclosure.

[0054] Figure 22 is a cross section of an exemplary axisymmetric (3D) design of a supersonic condensing nozzle, Prandtl-Meyer expansion device, and flow splitter assembly.

[0055] Figure 23Shows the presence of particle-free regions in a Prandtl-Meyer expansion device. DETAILED DESCRIPTION

[0056] The optimization challenges for a process and system designed to capture a target gas such as CO2 by condensing the target gas and then subjecting the particles to inertial separation involve the following aspects. The process and related systems and apparatus taught herein are also applicable to other target gases, and thus similar principles taught herein for CO2 are also applicable to other target gases. The most common industrial gaseous pollutants include CO2, SO X 、H2S、NO X For simplicity, this article refers to CO2, but this also includes other target gases. The expressions "target gas" and "target condensable gas" are used herein to describe the fact that the goal of the process and system is to isolate and separate / remove this gas from the gas stream.

[0057] According to the process described herein, first, particles can be injected into the gas stream to promote heterogeneous nucleation. The diameter and density of the selected particles should be large enough to achieve efficient inertial separation, that is, to complete within a shorter distance while minimizing the total pressure loss. On the other hand, for injected particles with the same mass flow rate, the smaller and lighter the particles are, the larger the surface area available for CO2 deposition, and the smaller the total pressure drop of the gas stream caused by particle entrainment. In addition, the heat capacity of the particles should be small enough to minimize the temperature difference between the particles and the gas in the flow direction and to accelerate the start of condensation. However, if the particles have a larger heat capacity, they accumulate the latent heat of fusion from the solidified CO2 while still maintaining their lower temperature, which further promotes the deposition of CO2. The injected particles can be in a solid phase or a liquid phase, the latter of which may solidify or not solidify before the CO2 condensation begins.

[0058] Furthermore, the geometry of the supersonic condensing nozzle used to accelerate the gas flow (i.e., its length, cross-sectional area variation along its length, and / or shape) should be optimally designed to minimize the overall pressure drop and, therefore, the energy and cost required to operate the system due to friction and particle drag, while achieving the optimal pressure-temperature conditions required for CO2 condensation.

[0059] The location and conditions for particle injection can be: in the main gas stream before the supersonic condensation nozzle; or anywhere within the supersonic condensation nozzle, such as before CO2 condensation begins, but the temperature and velocity at the injection point should be roughly equal to the temperature and velocity of the gas. After a sufficient amount of CO2 condenses on the injected particles, some form of inertial separation must then be performed to separate the condensed CO2 from the gas stream that has been de-CO2ized.

[0060] This disclosure will describe a process and system for capturing CO2 as the gas to be captured. However, the process 10 and the associated system are also applicable to other gases, and thus similar principles taught herein for CO2 are also applicable to other gases. The most common industrial gaseous pollutants include CO2, SO X 、H2S、NO X For simplicity, CO2 will be used as the capture gas in the remainder of this disclosure. The system includes a convergent-divergent nozzle, or other type of supersonic condensing nozzle, which expands the CO2-containing gas to CO2 condensing conditions, then uses Prandtl-Meyer expansion to inertially separate the solid condensed CO2 particles, collects the solid condensed CO2 particles, and then decelerates the gas flow to ambient conditions through a diffuser.

[0061] The injection of micron-sized particles is a key principle of the present disclosure. This creates a suitable well-defined surface (i.e., condensation nuclei) for heterogeneous nucleation of CO2 and for achieving inertial separation. Figure 1 , shows a CO2 capture process 10 using a supersonic flow of injected particles. The particles provide the surface required for the condensation of the CO2. In one variation, the particles can be a solid material, that is, in a solid phase under the operating conditions of the process. The particles can be spherical, tetrahedral, or irregular in shape, among other examples. The diameter of the particles can range from, but is not limited to, 0.1 microns to 50 microns. Exemplary solid materials can be, but are not limited to: silicon dioxide, activated silica gel, graphite, super activated carbon, titanium dioxide, aluminum oxide, silicon carbide, barium carbonate, magnesium oxide, various types of mining waste, ice, dry ice, or liquids such as water, hydrocarbons, liquid nitrogen.

[0062] Process 10 can collect gas from an industrial process as shown at A. The collected gas having a CO2 content is compressed at B using any suitable compressor. The compressor can be adiabatic, or isothermal, or any other variable process for compression cooling. In the case of isothermal compression, the compression work may be reduced by about 40% compared to adiabatic compression. The heat recovered by cooling the compressor can be recovered as a waste heat source for various purposes, allowing the CO2 capture system to operate at near net zero energy consumption. For example, the recovered heat can be used in industrial process A, or in any other process or equipment that requires heat, such as space heating, water heating, process heating, etc.

[0063] refer to Figure 1, schematically illustrates a process 10 that includes at least three sequential steps, such as: step 20, generating a supersonic flow; step 30, performing inertial separation using a convex corner that generates an expansion wave in a Prandtl-Meyer expansion; and step 40, collecting particles covered with CO2 and decelerating the flow to ambient conditions, which can also be considered as two steps. Step 40 can also include dividing the output from the Prandtl-Meyer expansion device 31 into two parts: one part is solid condensed CO2 particles (for example, in channel 41A) and the other part is a gas with a low CO2 content (for example, in channel 41B). Although the term "step" is used herein, a step can be a sub-step, and / or a step can include multiple steps or sub-steps. For example, as described below, step 20 of generating a supersonic flow can include a step or sub-step of performing particle injection and / or a step or sub-step of compressing the CO2-containing gas. Furthermore, process 10 may optionally include the step of collecting industrial gas from the industrial process as shown at A, and / or the step of compressing the collected gas at B using one or more compressors.

[0064] In step 20, CO2 contained in a gas (such as atmospheric air or combustion products) is, for example, condensed and concentrated in a solid state on micron-sized particles. This can be achieved by accelerating the pressurized gas stream containing CO2 to supersonic speeds. Step 20 can also include injecting solid particles (such as micron-sized particles) into the gas stream. These particles can be injected at any point before condensation conditions are reached, including but not limited to: the upstream chamber, the contraction section of the supersonic condensation nozzle, the throat of the supersonic condensation nozzle, and / or the expansion section of the supersonic condensation nozzle upstream of condensation. It should be noted that the exhaust gas from industrial process A may also contain sufficient micron-sized particles in the desired size range. When the gas is accelerated, it expands and cools. Under these conditions, if the CO2 contained in the gas stream reaches the appropriate temperature, it will undergo a phase change and condense into a solid; for example, the sublimation temperature of CO2 at atmospheric pressure is about -80 degrees Celsius (193 Kelvin). For example, if Figure 2 As shown in the phase diagram, the sublimation temperature of CO2 is a function of pressure; at a pressure of 101 kPa, the sublimation curve is approximately -80 degrees Celsius (193 Kelvin). This pressure is specifically the partial pressure of CO2 in the main gas stream and is a function of the CO2 concentration level. The condensation of CO2 into a solid state occurs on the surfaces of the micron-sized particles previously injected into the gas stream in step 20. As a result, at the outlet of step 20, a supersonic gas stream is obtained, depleted of gaseous CO2 and laden with particles coated with solid CO2.

[0065] In step 30, inertial separation of the particles occurs. Inertial separation occurs based on Prandtl-Meyer expansion waves, where a supersonic gas stream is exposed to a lobed corner, generating a substantially stationary and stable two-dimensional or three-dimensional expansion wave. The supersonic gas stream is deflected by the expansion wave, while the micron-sized particles maintain their trajectory due to inertia. This technique can achieve efficient separation if the product of the particle density and the square of the diameter is sufficiently large. Consequently, particles covered with CO2 accumulate in the path outside the lobed corner. To improve separation efficiency, a magnetic field can be applied, and particles with appropriate magnetic properties can be used. Alternatively, the particles can be charged before injection or through interaction with the gas stream, and an electric field can be applied to exert electrostatic forces, or a transverse magnetic field can be applied to exert Lorenz forces to assist in separating the particles from the gas stream. The number of Prandtl-Meyer expansion devices can be optimized, either in series or in parallel, to reduce overall system losses and improve separation efficiency, thereby increasing final CO2 purity.

[0066] As part of step 30, inertial separation uses Prandtl-Meyer expansion waves, rather than the shock waves or vortices of known processes. Prandtl-Meyer expansion cools the gas, whereas shock waves and vortices typically heat it. By cooling the gas, the risk of CO2 evaporation from the surface of the micron-sized particles is reduced.

[0067] In step 40, the particulates covered by CO2 are removed from the gas stream. One separation method employed in step 40 is to split the gas stream into two or more trajectories, such as by Figure 1Schematically shown in the two channels, this is achieved by a diverter 41. Diverter 41 can also be called a diverter, a separation device, and can be a pair of channels separated from a single channel. In a variation, diverter 41 is a pair of independent channels, pipelines, etc., and the output from one or more Prandt1-Meyer expansion devices 31 is directed to the diverter. The first channel can be used for gas that has been substantially decarbonized, and the second channel is used for a gas stream rich in particles covered by solid CO2. These two channels will take the form of a supersonic diffuser to gradually decelerate the supersonic gas flow to a stagnant state and restore the total pressure of the gas flow. The deceleration process may be accompanied by a shock wave. In a variation, the supersonic diffuser can take the form of a convergence-divergence nozzle with an adjustable throat to achieve efficient supersonic flow startup. The supersonic diffuser needs to be carefully designed to minimize the total pressure loss, such as by minimizing the amplitude of the above-mentioned shock wave. Therefore, at the outlet of process 10, a gas rich in particles covered by solid CO2 can be obtained. The CO2-free gas may be discharged to the environment or may be otherwise processed. In another embodiment of the present disclosure, a turbine may be used (eg, in channel 41B) to recover work that may be used to drive the compressor at B, which is an example of energy recovery.

[0068] Process 10 may include additional steps for storing, using, or sequestering the solid CO2 on the particles. In one variation, process 10 may include a separation step, where the CO2 is separated from the particles by sublimating it from the solid state to a gaseous state. One possible method of sublimation is to raise the temperature of the particles above the sublimation temperature of CO2 at atmospheric pressure (approximately -80 degrees Celsius (193 Kelvin)). This is typically performed during a pressure recovery process, when the gas, which is high in particles, slows down and its temperature rises. The heat required for sublimation can be drawn from the compressor, thereby cooling the compressor and reducing the compression work (i.e., approaching isothermal compression). For example, the heat can also be used to cool the compressed gas exiting the compressor (before step 20), cool flue gases from an industrial process, or directly cool the particles for use prior to the reinjection step. The particles can also be exposed to ambient conditions to allow the CO2 to sublime. The particles can then be recovered for reinjection in step 20 of process 10. This is one possible outcome for the solid CO2 on the particles exiting in step 40.

[0069] Still refer to Figure 1As part of step 20, a supersonic condensation nozzle 21 is used together with one or more injection devices 22. The specific geometry and size of the supersonic condensation nozzle 21 depend on the total input pressure, temperature, gas flow rate, CO2 concentration, diameter, density, mass fraction and heat capacity of the injected micron-sized particles. The geometry of the supersonic condensation nozzle here refers to the axial profile, cross-sectional variation and length. This is optimized as described below to maximize the ratio between the CO2 capture amount and the total pressure drop of the system, which ratio represents the work required by the system. The optimization of the supersonic condensation nozzle geometry and the injection parameters are based on a mathematical model that simultaneously integrates nucleation and growth models, cross-sectional variation, wall friction and heat conduction, micron-sized particle injection, particle resistance and heat conduction. The geometry of the supersonic condensation nozzle is also used to avoid expansion wave reflection, and / or compression wave reflection and / or shock wave formation.

[0070] The total pressure drop within the supersonic condensation nozzle can be due to: particle entrainment, wall friction and heat conduction, and the latent heat released by the condensation of CO2. For the target CO2 capture rate, the latent heat will be a fixed value. By increasing the size of the supersonic condensation nozzle (i.e., passing the entire gas flow through a large supersonic condensation nozzle rather than splitting it into several small supersonic condensation nozzles), the wall friction effect can be reduced. The remaining loss factor to be minimized is particle entrainment. For a specific particle size and mass fraction, this can be achieved by adjusting the geometry of the supersonic condensation nozzle after condensation begins to reduce the velocity and / or temperature difference between the particles and the gas, or by injecting the particles before condensation begins, but at a temperature and velocity roughly the same as that of the gas phase.

[0071] like Figure 2 As shown in , an exemplary phase diagram of CO2 is provided, including gas flow pressure and temperature, and showing the regions where CO2 is in solid, liquid, and gaseous states. At ambient temperature and pressure, CO2 is in the gaseous state. When accelerated into a supersonic flow as in step 20 of process 10, the pressure and temperature drop. Figure 2 As shown in , the gas expands approximately isentropically based on the pressure and temperature conditions according to the gas flow Mach number. When the gas expands and enters the solid region of the phase diagram, CO2 condensation occurs. In fact, the starting point of CO2 condensation into a solid state occurs when its characteristic curve is in line with the Figure 2 The extrapolated line 505 of the liquid / gas curve (VL line) in FIG.

[0072] Step 20 of process 10 relies on solid-state condensation to assist in capturing CO2. When designing system components for process 10, nucleation and growth rates must be considered. The heterogeneous nucleation rate may be affected by temperature, free energy of droplet formation, particle size, surface tension, and / or saturation level. The growth rate may be affected by particle size, partial pressure of CO2, flow rate, and particle temperature, molar volume of CO2, and adhesion coefficient. CO2 condensation is an exothermic process, so the gaseous CO2 at the starting point must release its latent heat to the surrounding gas in order to phase change into a solid state. This heat transfer causes the temperature of both the gas and the particles to increase, and this temperature increase may slow or hinder condensation.

[0073] To achieve suitable CO2 condensation, the condensation rate must be above a given threshold. Compared to existing systems that do not consider condensation control, process 10 and related systems must control condensation to achieve efficient CO2 capture. Controlling condensation and promoting the onset of nucleation can be achieved by varying the cross-sectional dimensions and / or cross-sectional area of ​​the supersonic condensation nozzle along its length. Process 10 and related systems can allow for more suitable CO2 condensation control for CO2 capture by injecting micron-sized particles into the gas stream. In effect, the particles injected into the gas stream act as nucleation sites, increasing the effective surface area for condensation. To significantly increase the effective size, the injected particles must be small, preferably micron-sized. Particle injection can increase drag, as the gas must entrain these particles, which are injected at a slower velocity than the gas. Because a supersonic condensation nozzle is used in step 20, the gas is continuously accelerated within the nozzle. The drag associated with particle injection causes a pressure drop and a reduction in the Mach number. Furthermore, friction causes a temperature increase, which negatively impacts condensation. Therefore, these factors must be considered when injecting particles in step 20 to maintain suitable condensation.

[0074] Because particles have a higher density than the gas and therefore greater inertia, particle injection also enhances inertial separation, thereby utilizing the expansion wave to separate the particles in step 30. However, while larger particles may facilitate inertial separation, they may require more energy to accelerate and may have a smaller effective surface area for condensation, so an optimal particle size must be used. Therefore, injection parameters (such as the number of particles, injection rate, and injection uniformity) as well as particle characteristics (such as particle size, density, temperature, and surface tension) must be controlled.

[0075] The first aspect of a supersonic condensing nozzle is its design Mach number. Figure 3As shown in , consider a simple converging-diverging nozzle of a specific length 301. Its design Mach number represents the ratio of the outlet area 302 to the throat area 304 (i.e., the nozzle area ratio). Supersonic condensing nozzles can be axisymmetric or 2D rectangular, or can transition from axisymmetric to 2D rectangular, or vice versa. From a gas dynamics perspective, as the design Mach number increases, the area ratio increases, while the outlet temperature, pressure, and density decrease. At first glance, decreasing gas temperature should promote CO2 condensation. However, decreasing gas phase density reduces the heat transfer coefficient between the particle and the gas. Therefore, as the gas temperature decreases, the particle temperature where CO2 condensation occurs no longer matches the gas temperature.

[0076] Figure 4 The effect of the design Mach number on the outlet CO2 concentration (capture efficiency) is shown. For a specific supersonic condensation nozzle length and particle characteristics (in this example, an initial CO2 concentration of 15%), the outlet CO2 concentration initially decreases at 401 and reaches a minimum value 402 at a design Mach number of 6. Further increases in the design Mach number lead to a decrease in performance 403 due to reduced influence of the surrounding gas on the particles. At the limit of 15, CO2 condensation is predicted to cease. Note that at higher design Mach numbers, the particle residence time within the supersonic condensation nozzle decreases due to increased particle velocity. This also results in a decrease in CO2 capture. Figure 5 A comparison of the heat transfer coefficients for the aforementioned designs at a Mach number of 6 (point 402) and a Mach number of 10 (point 404) is shown. Along the diverging section of the supersonic condensing nozzle, the heat transfer coefficient 410 at a Mach number of 10 decreases by a factor of 10 to 40 compared to the heat transfer coefficient 406 at a Mach number of 6 due to the decrease in gas density. It should be noted that after exploring the design space, the optimal design Mach number range can be 2 to 10, preferably 3 to 8.

[0077] The particle drag effect can be reduced by optimizing the design of the supersonic condensation nozzle profile. The goal is to reduce the mismatch between the particle and gas velocities. Changes to the supersonic condensation nozzle geometry can be made before condensation begins, for example, starting at the supersonic condensation nozzle's starting point or at the throat. However, this may delay the onset of condensation while minimizing the drag effect. Another scenario is to optimize the supersonic condensation nozzle geometry after condensation begins. In this case, the supersonic condensation nozzle geometry remains unchanged from a basically unoptimized configuration until condensation begins as quickly as possible. The supersonic condensation nozzle geometry is then gradually modified to reduce the acceleration of the gas downstream of the supersonic condensation nozzle, thereby reducing the mismatch between the particle and gas velocities. However, this is done without excessively affecting the particle temperature, as the particles are cooled by the surrounding gas. If the particle temperature increases erratically, this will negatively impact the CO2 condensation rate. Figure 6 A first example is shown: a simple, essentially conical, convergent-divergent nozzle 501 with a length of 4.5 m is compared to an optimized supersonic condensation nozzle 502 with a length of 4.64 m. In this case, the throat 550 of the supersonic condensation nozzle is located 0.5 m downstream from the supersonic condensation nozzle inlet, while the condensation start point 503 is located approximately 1.75 m downstream from the supersonic condensation nozzle inlet, as shown in FIG. Figure 7 The flow characteristics in Figure 5 are shown. The supersonic condensation nozzle profile optimization 502 can be performed starting at a position 504 2.2 m from the supersonic condensation nozzle inlet (i.e., 0.45 m after the condensation start point). In this case, the supersonic condensation nozzle geometry optimization condition is to set the gas axial temperature gradient to dTg / dx = 3°C / m, where Tg is the gas phase temperature. The gas axial temperature gradient defines the rate at which the gas temperature is allowed (i.e., controlled) to gradually increase over the length of the supersonic condensation nozzle. In the above example, dTg / dx = 3°C / m means that the gas temperature increases by 3°C per meter. Figure 8 The phase diagram for this situation is shown. The condition for the onset of condensation is located at 520, while the condition for the onset of nozzle geometry modification is located at 525. If compared with a simple conical supersonic condensing nozzle (e.g. Figure 6 Compared with the basic case 511 of 501 in , it can be observed that the optimized supersonic condensation nozzle (e.g. Figure 6 The gas temperature of the gas in the reactor 502 increases by 512. When the gas state approaches the VL extrapolation line 515, CO2 condensation may stop. Figure 9 The CO2 condensation rate is shown relative to the total pressure increase rate (dm / dP0). The rate value 900 is at the condensation start position 503 at 1.75 m ( Figure 6 ). Before the supersonic condensation nozzle profile optimization begins, that is, at position 504 ( Figure 6), the same result is also found. Subsequently, a gain 901 is observed due to the effective reduction of particle drag loss. It should be noted that in order to achieve the same final CO2 capture amount, the supersonic condensing nozzle 502 ( Figure 6 ) is slightly longer. In this case, the optimized supersonic condensation nozzle 502 ( Figure 6 ) recovery pressure ratio compared to the simple conical supersonic condensing nozzle 501 ( Figure 6 ) increased by 18.3%. The recovery pressure ratio is defined as the ratio between the final total pressure and the initial total pressure. This makes it possible to compare with the supersonic condensing nozzle 501 ( Figure 6 ) compared to the optimized supersonic condensation nozzle 502 ( Figure 6 ) reduced related compression costs by 7.3%.

[0078] Therefore, a supersonic condensation nozzle can be described as having an inlet end and an outlet end. A channel is defined between the inlet and outlet ends. The channel is configured to receive a fluid flow containing a target condensable gas component (e.g., CO2). The internal geometry of the channel, from the inlet end to the outlet end, defines: a converging section, wherein the cross-sectional dimensions decrease in the direction of fluid flow, for subsonic flow; a diverging section, wherein the cross-sectional dimensions increase in the direction of fluid flow, for supersonic flow; and a throat section located between the converging and diverging sections. Based on the relationship between fluid flow parameters and the geometry, the condensation initiation region (e.g., starting at 503) is located in the diverging section, where the condensation of the target condensable gas begins. Relative to the direction of fluid flow, the diverging section has a greater expansion gradient at the condensation initiation region than at a point downstream of the condensation initiation region, such as indicated by 504. The expansion gradient at the condensation initiation region can be said to differ from the expansion gradient downstream of the condensation initiation region, with a step-like value, i.e., it is not a gradual change, but in some variations, it can be a gradual change. The above-mentioned expansion gradient can be formed by two sequentially arranged frustums. In an embodiment, there is an edge at the transition. Particle injection can occur in any section (i.e., the contraction section, the throat section, the expansion section) to promote heterogeneous nucleation. In one variation, injection is performed downstream of the condensation initiation zone.

[0079] Exemplary dimensions for a supersonic condensation nozzle are provided. The supersonic condensation nozzle may be an axisymmetric or 2-D nozzle, e.g., Figure 21806 shown in FIG. 1 is an example of an axisymmetric nozzle. In one variation, the minimum dimension (e.g., diameter) of the throat section can vary between 0.01 m and 0.50 m, depending on initial conditions, although other dimensions are also contemplated. In this embodiment, the Mach number at the outlet can be between 2 and 10 (inclusive), although other Mach numbers are also possible. In one variation, for a 2D nozzle, the divergence gradient can be a half-cone angle between 3 degrees and 70 degrees (inclusive). In another variation, for an axisymmetric nozzle, the divergence gradient can be a half-cone angle between 1 degree and 48 degrees (inclusive). The half-cone angle of the modified and optimized supersonic condensation nozzle can vary from zero (i.e., a constant channel area) to a cone angle or divergence angle less than or equal to that of the substantially unmodified supersonic condensation nozzle described above. The half-cone angle can be defined as the angle from the central axis of the cone (i.e., a right-angle cone) to the sidewall. In one variation, the outlet area (e.g., cross-sectional dimension) is between 1.7 and 536 times the minimum throat area (e.g., cross-sectional dimension). The inlet area (e.g., cross-sectional dimensions) can be determined based on the system piping and can vary between 2 and 10 times the minimum throat area (e.g., cross-sectional dimensions). The length of the supersonic condensation nozzle's convergent section can vary between 1% and 10% of the total nozzle length (inclusive). For supersonic condensation nozzle geometries modified and optimized at or after the starting point (i.e., the condensation start region), the distance between the throat section and the start of the nozzle profile modification can be between 10% and 60% of the divergent section length (inclusive). The modified supersonic condensation nozzle divergent section can be a straight cone, or dA / dx can vary with position (i.e., a progressive nonlinear increase), depending on the desired design conditions (i.e., dTg / dx, du / dx, etc.). The transition from the basic supersonic condensation nozzle profile to the modified supersonic condensation nozzle profile occurs at or after the starting point and can be abrupt or gradual.

[0080] Another possibility is Figure 10 Figure 506 shows a supersonic condensing nozzle with a length of 10 m. In this case, the design condition after the condensation start point is set to an axial gas temperature gradient of dTg / dx = 0°C / m. Compared to a basic conical supersonic condensing nozzle, this design achieves a 30.1% improvement in the recovery pressure ratio and an 8% reduction in compression cost. Figure 11The final scenario 507 is shown, which features a supersonic condensation nozzle with a length of 6 m. Even with an axial gas temperature gradient of dTg / dx = -0.3°C / m, the risk of reaching the theoretical extension of the VL extrapolation line 505 is observed. In this scenario, the gas temperature decreases after the supersonic condensation nozzle optimized position 525, but at a slower rate than for the basic conical supersonic condensation nozzle 511. In fact, due to the use of smaller particles, the operating line for the basic conical supersonic condensation nozzle 511 in this scenario is closer to the VL extrapolation line 505. This increases the heat transfer surface area between the particles and the gas, resulting in relatively hotter gas. In this scenario, the recovery pressure ratio is expected to increase by 20.6%, and the compression cost is expected to decrease by 5.6%.

[0081] The parameters for each of the aforementioned scenarios are summarized in Table 1 below. It should be noted that the aforementioned scenarios are estimated based on a flue gas source of 100,000 tons / year of CO2 and a CO2 concentration of 15% by volume. Therefore, it is shown that by adapting the axial gas temperature gradient dTg / dx to other process parameters, such as the supersonic condensation nozzle geometry (profile and length), the pre-existing suspension of the liquid-solid-gas mixture, the total gas pressure and temperature, humidity, particle size, density, specific heat, mass ratio, and the CO2 concentration in the incoming gas, the efficiency of the supersonic condensation nozzle in promoting CO2 condensation while minimizing pressure loss can be improved. Optimizing the supersonic condensation nozzle geometry to achieve a specific target axial gas temperature gradient can significantly improve the total pressure loss while condensing the same amount of CO2.

[0082] Similarly, in another embodiment, the geometry of the supersonic condensing nozzle can be further optimized by adjusting the gas axial temperature gradient dTg / dx as a function of the axial position (rather than a constant value). This means that dTg / dx changes from one axial position to another.

[0083] In another embodiment, optimization of the supersonic condensation nozzle can be achieved by controlling other parameters in the length direction of the supersonic condensation nozzle, such as: axial change of gas velocity u, gas axial velocity gradient du / dx, gas axial pressure gradient dP / dx or gas axial density gradient dρ / dx, or a combination thereof.

[0084] Table 1: Summary of operating parameters for Cases 1, 2 and 3 using a mass fraction of 0.3 graphite particles.

[0085]

[0086] By injecting micron-sized particles inside the supersonic condensation nozzle, rather than before the nozzle, it is possible to reduce losses caused by having to accelerate the injected particles. However, the temperature and velocity of the particles should be as close as possible to that of the gas. The particles can be injected into the converging portion of the supersonic condensation nozzle (i.e., before the throat) or into the diverging portion (i.e., before or after the theoretical onset of condensation).

[0087] Looking back at Case 1 in Table 1, Figure 12 FIG2 shows a comparison of flow characteristics, which shows the results of the conventional case 521 of injecting particles into the incoming gas suspension and the case 601 of injecting particles into the expansion portion of the supersonic condensation nozzle. In this case, the injection position 600 is set to 3 m downstream from the inlet of the supersonic condensation nozzle (i.e., about 1.5 m downstream of the theoretical condensation starting position 513) to produce the same final CO2 concentration as the conventional case 521 for comparison. Figure 12 As can be seen in FIG, the gas flow expands at 601 and first cools without any friction losses due to particle drag (but wall friction losses still exist). Particles are then injected at position 600 of the diverging portion of the supersonic condensation nozzle to provide a surface for CO2 condensation and solidification. To avoid transient heating of the gas, drag losses, and the possible formation of local shock waves (which may delay or hinder CO2 condensation), the temperature and velocity of the injected particles should be the same as those of the gas phase at injection position 600. It is also observed that due to the reduced particle drag losses, the theoretical condensation starting position 513 is larger in the particle injection position controlled scenario than the starting position 503 in the normal scenario ( Figure 6 ) about 0.5 m in advance. Figure 13 The total pressure distribution of the normal scenario 602 and the scenario 603 with controlled particle injection position is shown. This can achieve a 120% increase in the recovery pressure ratio and a 35% reduction in the associated compression cost. Table 2 further compares the two particle injection schemes for Case 2 and Case 3. It should be noted that at position 502 ( Figure 6 Optimization of supersonic condensation nozzle profile and particle injection position control scenario 601 (based on gas temperature axial gradient or other parameters or their combination) Figure 12 ) can be performed simultaneously, thus benefiting from both techniques.

[0088] Table 2: Comparison of normal particle injection at the supersonic condensation nozzle inlet and controlled particle injection in the nozzle divergence for Cases 1, 2 and 3.

[0089]

[0090] The above scenarios show the potential for improving supersonic CO2 capture by using the proposed method. However, optimization depends on the specific application or scenario to provide the most efficient full-scale CO2 capture and separation system. For example, Table 3 shows a design scenario that uses a simple conical supersonic condensing nozzle with a length of 4.5 m and 3 μm graphite particles. The phase diagram, axial CO2 concentration, particle diameter, and total gas flow pressure are respectively Figure 14 、 Figure 15 、 Figure 16 and Figure 17 It should be noted that Figure 16 It can be seen that due to CO2 deposition, the particle diameter increases significantly in this case, reaching 4.4 μm, which may be beneficial for the design of the separation section.

[0091] Table 3: Example of a design scenario for 100,000 t / yr.

[0092]

[0093] Still refer to Figure 1 , the inertial separation step 30 relies on the expansion of a supersonic gas stream comprising particles covered with solid CO2 to accelerate and deflect the gas stream using a Prandt1-Meyer expansion wave. As a result, the particle streamlines deviate from the gas streamlines and converge towards the other side of the channel where a diverter is inserted at a specific height to separate the gas stream with a high particle content. This is done in an expansion device 31 having a convex corner 31A, which is called a Prandt1-Meyer expansion device 31. The corners of the expansion device can be gradual, smooth or sharp, rather than rounded. When the convex corner 31A is sharp, a centered and stable expansion wave can be generated from the sharp convex corner. The device is Figure 18 31A is shown in more detail in . Opposite the cam 31A is an upper wall 31B and adjacent to and downstream of the cam 31A is a lower wall 31C. The upper wall 31B can be designed to avoid reflections of the expansion wave 601 and attempt to reduce the risk of generating shock waves before, during and / or after separation. Due to inertia, the particle 602 covered with solid CO2 travels along a path 603 different from the gas 604 and hits the upper wall 31B at position 605. Particle 602 represents at least one particle suspended in the gas flow. These particles can then be captured using various methods including but not limited to porous media (through which the particles can pass), electric fields, magnetic fields, moving belts, suction walls and / or liquid films along the upper wall 31B and / or combinations thereof. It should be noted that "upper" and "lower" are relative to Figure 18The upper wall is the wall opposite the convex corner, while the lower wall is adjacent to the convex corner. However, in use, "upper" and "lower" may not coincide with the direction of gravity. For example, the upper wall may alternatively be referred to as the "distal wall" or "opposite wall," while the lower wall may be referred to as the "proximal wall" or "adjacent wall."

[0094] Figure 19 A possible separation method is shown. A splitter 606 is positioned relative to the impact zone 610 to separate the channel into two separate channels 41A and 41B, each with different particle concentrations. Ideally, channel 41A contains a higher concentration of particles than channel 41B. The trajectory of the separated particles and their accompanying process gas influences the resulting CO2 purity. The position and shape of the splitter 606 are optimized to maximize particle collection efficiency and / or the CO2 purity of the collected gas. This depends on the impact zone 610 or the trajectory of the last particle 611 (i.e., the impact location). The splitter 606 can be located before, at, or after the impact location 605. This trade-off is made between the purity of the CO2 captured from the high-particle gas stream and the total percentage of separated particles (i.e., captured CO2). A shock wave 607 may be present on one side of the splitter 606, but it does not affect the trajectory prior to separation. This shock wave can be primarily an oblique shock wave of either the attachment or separation type. Depending on the shape of the splitter and the flow characteristics, this shock wave may occur on either or both sides of the splitter, but preferably does not occur in the channel 41A containing the high concentration of particles.

[0095] Still refer to Figure 19 , the splitter can be used in combination with other separation technology embodiments, such as but not limited to: an electric field, a magnetic field, a moving belt, a suction wall and / or a liquid film along the upper wall 31B, or any combination thereof. The injection of the liquid film along the upper wall 31B can be performed before and / or after the impact location 605, and / or downstream of the separation channel 41A. This reduces the rebound of the particles by forming a surface with damping properties. Since particles may penetrate the liquid film, this technology can also prevent process gas from being sucked in with the particles. This can increase the final CO2 purity. The liquid film can be implemented at other locations within the entire system, such as the supersonic condensing nozzle, and / or the impact area 610, and / or channels 41A and 41B, and / or the downstream diffuser to reduce the abrasive effect of particle impact on the wall.

[0096] Prandt1-Meyer expansion device 31 ( Figure 1 ) allows the formation of a substantially particle-free region 1101 along the lower straight wall of the channel after the convex corner 31A, as Figure 23As shown in . The height H of the particle-free area 1101 from the lower wall 31C depends on the gas flow characteristics (pressure, inlet Mach number, outlet Mach number) and the particle characteristics (size, shape, density). For example, larger and denser particles and lower pressure gas flow will cause the particle-free area to become larger. The upper wall 31B and the diverter device 41 of the Prandt1-Meyer expansion device 31 can then be placed relative to the particle-free area to optimize the CO2 purity and / or capture efficiency. In an embodiment in which, for example, a liquid film is used to minimize the rebound of particles on the upper wall 31B, the upper wall 31B can be arranged so that all or a portion of the upper wall can be aligned with the boundary of the particle-free area. In another embodiment in which the rebound of particles cannot be ignored, the upper wall 31B can be placed prominently in the particle-free area to be able to cope with the rebound of particles.

[0097] Prandt1-Meyer expansion device 31 ( Figure 1 ) also depends on the Mach number and cross-sectional area at the supersonic condensation nozzle outlet. However, the design of the supersonic condensation nozzle depends on the size of the particle-free zone. Specifically, under given flow conditions, the outlet height of the supersonic condensation nozzle or the inlet height of the Prandt1-Meyer expansion device 31 cannot be significantly changed, otherwise the performance of the Prandt1-Meyer expansion device 31 will be reduced. Therefore, in the embodiment of the system using a rectangular cross-section, the width of the Prandt1-Meyer expansion device 31 must be adjusted ( Figure 18 The out-of-plane dimension in the plane is chosen so that the cross-sectional area matches the exit cross-sectional area of ​​the supersonic condensation nozzle. Since friction effects increase with increasing surface area, it is advantageous to select flow conditions and particle types that allow the inlet of the Prandtl-Meyer expansion device 31 to approach a square cross-section. However, given that these parameters also affect the performance of the condensation subsystem, they must be optimized as a whole.

[0098] Table 4 shows some examples of calculations for different particle types in the Prandtl-Meyer expander 31 configuration. These calculations are based on a flow rate of 14.6 kg / s and a total pressure of 1.5 bar at the Prandtl-Meyer expander 31 inlet. Although these cases utilize spherical graphite particles, other particle types that maintain the same aerodynamic properties are also applicable. The same particles are used in Cases 1, 2, and 3, and they enter the Prandtl-Meyer expander 31 at the same Mach number. Comparing Cases 1 and 2, it is clear that increasing the final Mach number allows for a reduction in the amount of process gas trapped with the particles. Cases 2 and 3 have the same final Mach number but different heights. Therefore, Case 2 minimizes the proportion of process gas trapped with the particles, thereby improving the final CO2 purity. Case 3, however, has a higher inlet height of the Prandtl-Meyer expander 31, allowing for a more square cross-section. This minimizes friction effects, but at the expense of greater process gas capture. Cases 4 and 5 used 10 μm graphite particles, requiring a reduction in the inlet height of the Prandtl-Meyer expansion device 31 to match the height of the particle-free region. Case 6 used 50 μm graphite particles, allowing the inlet of the Prandtl-Meyer expansion device 31 to have an optimal square cross-section, while Case 7 used 3 μm graphite particles, which is close to the limit of the particle size that can be effectively separated, with the inlet height of the Prandtl-Meyer expansion device 31 being 5 mm.

[0099] Table 4: Separator parameters for the 100'000 t / y design case.

[0100]

[0101] For the Prandt1-Meyer expansion device 31 as described above, particles with a size ranging from 1 micron to 100 microns and a material density ranging from 500 kg / m³ to 19,200 kg / m³ can be used. The particle gas flow can enter the Prandt1-Meyer expansion device 31 at a Mach number between 2 and 5, and can reach a Mach number of 3 to 6 after passing through the cam 31A. In a Prandt1-Meyer expansion device 31 with a rectangular cross-section, the cam 31A flow deflection angle α can vary between 2 degrees and 85 degrees. For a gas flow entering the Prandt1-Meyer expansion device 31 at a total pressure of 1.5 bar, the inlet height of the Prandt1-Meyer expansion device 31 can be between 5 mm and 0.5 m.

[0102] The dimensions of the Prandtl-Meyer expansion device 31 (such as width and convex angle 31A, flow deflection angle α) can be determined based on the Mach number and height 706 (i.e., area) of the supersonic condensing nozzle outlet. As described above, the height 706 depends on the mass flow rate of each nozzle, and in order to minimize the friction effect, this mass flow rate should be maximized. However, there is a relaxation length after which the particle trajectory 603 follows the gas streamline 604 (i.e., the particles no longer separate by inertia). The relaxation length depends on the velocity difference between the particle and the gas, as well as the size and density of the particle.

[0103] The Prandtl-Meyer expansion device 31 can be described as a device for separating particles from a supersonic, particle-laden gas flow, i.e., it need not be used in conjunction with a supersonic condensing nozzle. The device can be described as having: an inlet end and an outlet end; a channel for the gas flow located between the inlet end and the outlet end, wherein the channel surface of the channel has a convex corner, causing the particle-laden gas flow to generate an expansion wave from the convex corner, thereby separating the fluid flow at the outlet into: a first flow path, in which the particle concentration increases near the channel surface opposite the convex corner, and a second flow path, in which the particle content of the gas decreases near the channel surface having the convex corner.

[0104] The particle concentration at the impact region 610 is primarily influenced by the relaxation length of the particles within the flow. If the length of the Prandtl-Meyer expansion device 31 is less than the relaxation length, the particle concentration at the impact region 610 will be sufficiently high, and the separation efficiency will be acceptable. However, for longer Prandtl-Meyer expansion devices 31, there is a possibility that the geometric position of the upper wall 31B and the flow divider 606 may be after the relaxation length. Therefore, the particle concentration at the impact region 610 and the separation efficiency will be significantly reduced. One possible solution to this problem is to split the Prandtl-Meyer expansion device 31 into two or more shorter Prandtl-Meyer expansion devices. A smaller inlet height and a greater number of Prandtl-Meyer expansion devices 31 (and correspondingly, a larger lateral width to accommodate the required flow rate) will provide a stronger separation capability for fine particles, but will also result in a greater inherent pressure drop.

[0105] In another embodiment of the present disclosure, two or more Prandt1-Meyer expansion devices 31 are arranged in a parallel cascade manner, such as Figure 20 For illustrative purposes, the Figure 19 The Prandtl-Meyer expansion device 31 is similar to the Prandtl-Meyer expansion device shown in FIG, but other Prandtl-Meyer expansion devices 31 with associated flow splitters may also be used in a similar parallel cascade arrangement. Figure 20 In the figure, three Prandt1-Meyer expansion devices 701, 702 and 703 are shown for illustrative purposes, but any number of Prandt1-Meyer expansion devices may be used depending on the overall size of the system. The partition walls between the channels are arranged so that the leading edge 704 is located on the first Mach wave 705 of each Prandt1-Meyer expansion device 701, 702, 703, so that each Prandt1-Meyer expansion device operates independently of each other. Depending on the thickness of the leading edge 704, a weak shock wave may be attached to it without affecting the overall flow. In this embodiment, the channels 701A, 702A and 703A from which the particles have been removed may be connected together downstream of the separation device, and similarly, the channels 701B, 702B, 703B containing the aggregated CO2 are also connected together. These channels may deviate from Figure 20 This is achieved by allowing the size of each Prandt1-Meyer expansion device to be selected based on the relaxation length of the particles and / or the height of the particle-free zone, thereby optimizing the capture efficiency without being limited by the size of the supersonic condensation nozzle outlet channel 706.

[0106] In another embodiment of the present disclosure, the final cross-section of the supersonic condensing nozzle can be flattened into a rectangular cross-section, thereby allowing the aspect ratio to match the inlet cross-section of the Prandtl-Meyer expansion device. Figure 19 As shown in , the in-plane dimension of the outlet of the supersonic condensation nozzle can be adjusted according to the relaxation length of the particles in the flow and / or the height of the particle-free zone, while the out-of-plane dimension can be adjusted according to the required mass flow rate of the system. This embodiment can also be used in combination with other embodiments described herein (such as the embodiments described in the preceding paragraphs).

[0107] After the condensation and separation process described above, the CO2 remains mostly solid and carried by the particles, but it is concentrated in one flow path, while the other flow path is a flow free of particles and CO2, ready for subsequent physical separation in step 40, for example, by a flow splitter 41 having a first channel 41A and a second channel 41B. A filter can be further installed downstream of the separated flow with a high particle content to complete the particle separation process. Alternatively, a cyclone splitter or similar device can be used to separate solid particles from the gas with a high CO2 content.

[0108] Although Figure 1The various devices of the system for operating process 10 shown in FIG are shown as discrete components, but these components can also be arranged as a continuous channel and separated into a pair of channels or more channels at the splitter 41. Therefore, it can be said that the supersonic condensing nozzle 21, the Prandtl-Meyer expansion device 31 and the splitter 41 are various segments or parts of the channel system.

[0109] Thus, process 10 can generally be described as being for capturing gaseous pollutants (such as CO2) and can include the following steps: accelerating a gas containing a CO2 component into a supersonic gas flow in a nozzle; injecting particles into the supersonic gas flow, whereby solid CO2 condenses on the surfaces of the particles; causing an expansion wave in the particle flow with solid CO2 to separate the flow into a first flow path having an increased concentration of particles with solid CO2 and a second flow path of gas with a reduced CO2 content; and physically separating the first flow path from the second flow path.

[0110] Process 10 can employ a system that can be generally described as having the following components: a supersonic condensation nozzle configured to receive a gas containing a CO2 component and accelerate the gas into a supersonic gas flow; at least one particle injector located in the supersonic condensation nozzle for injecting particles into the gas flow, thereby condensing solid CO2 on the particles; a Prandt1-Meyer expansion device defining a channel having a convex angle so that the particle flow containing solid CO2 produces an expansion wave to separate the flow into a first flow path with an increased concentration of particles containing solid CO2 and a second flow path of gas with a reduced CO2 content; and a flow separation device having a first channel and a second channel, the flow separation device being configured to receive the first flow path and the second flow path and physically separate them in the first channel and the second channel.

[0111] Figure 21A conceptual, full-scale overview of an exemplary CO2 capture facility using the methods and systems of the present disclosure is shown. CO2-containing gas enters at 801, potentially at a temperature above ambient. If necessary, the CO2-containing gas can be cooled by a first heat exchanger 802, which is designed to handle the gas flow rate and has cooling capacity. The CO2-containing gas can be cooled to ambient temperature, or to a temperature between ambient and the initial gas temperature. The first heat exchanger 802 can be water-cooled or air-cooled, particularly with appropriate heat exchange coils. In cooler weather during cooler months, outdoor air can optionally be used. Heat can be recovered from the heat exchanger 802 for use in any suitable heat load. The compressor stage 803 comprises one or more compressors 803, arranged in any suitable arrangement (parallel, cascaded), to pressurize the CO2-containing gas to the pressure level required for supersonic expansion. The temperature of the pressurized gas can then be increased and cooled again by a second heat exchanger 804. Heat can again be recovered from the heat exchanger 804 for use in any suitable heat load. The compressor 803 and the second heat exchanger 804 can be a series of compressors and heat exchangers connected in series and / or in parallel to handle and / or control a wide range of flow rates and / or achieve isothermal compression with minimum compression work. Heat recovered from the heat exchangers 802 and / or 804 and / or other heat exchangers can be directed to waste heat recovery applications. The injector 805 can be arranged to inject micron-sized particles. The injector 805 can be arranged in any section or portion of the inlet chamber or the supersonic condensation nozzle 806. The supersonic condensation nozzle 806 can be a single nozzle or multiple parallel nozzles to handle and / or control a wide range of flow rates. The particles with solid CO2 are separated by an expansion device 807, which can include a splitter. The Prandtl-Meyer expansion device 807 with a splitter can be composed of a single and / or a series of Prandtl-Meyer expansion devices. The flow with a high particle content exits the 2D plane through an outlet (shown as channel 808). Passage 808 can be designed to decelerate the flow with high particle content to near ambient pressure. Among other possibilities, the separated particles are collected inside storage tank 809. Storage tank 809 can allow CO2 to sublime and / or utilize the heat of sublimation for cooling purposes. Storage tank 809 can be placed before and / or replaced by the cyclone device, to separate solid particles and / or possible liquid water from the gas stream 810 with high CO2 content. The recovered particles 811 can be directed back to the particle injector 805. The recovered particles 811 can utilize a heater for dehumidification. The gas stream 810 with high CO2 content can undergo further purification. The gas stream 813 with low particle content that leaves from the Prandtl-Meyer expansion device 807 with a splitter can be decelerated to ambient pressure level using a diffuser passage 812.

[0112] By further processing the outlet gas 810 with a high CO2 content, the purity of the final CO2 can be controlled and / or improved. This can be achieved by connecting two or more such Figure 21 Further purification can be performed using cryogenic CO2 purification and / or other gas separation technologies.

[0113] Still refer to Figure 21 The supersonic condensing nozzle 806, the Prandt1-Meyer expansion channel 807, the outlet channels 808 and 812 can be axisymmetric (3D), and / or have a 2-D form, and / or transition from one form to another. The supersonic condensing nozzle 806 and / or the Prandt1-Meyer expansion device 807 with a splitter can be repeated in series with or without intermediate particle injection to separate other gaseous components besides CO2, such as but not limited to water vapor, SO x , H 2 S, etc. In the case of separating other gaseous components, the temperature of the storage tank 809 can be controlled to sublime each gaseous component in turn according to its sublimation temperature.

[0114] Figure 22 A possible axisymmetric (3D) design is shown, incorporating a supersonic condensing nozzle 1001 (with a throat 1002), a Prandtl-Meyer expansion device 1003 (with lobes 1004 and flow splitters 1005), a diffuser passage 1006 (with a throat 1008) for gases with low CO2 content 1007, and a diffuser passage 1009 (with a throat 1011) for gases with high CO2 content. This axisymmetric design with a central body can be advantageous because it provides the Prandtl-Meyer expansion device 1003 with a large circumference and a small height.

[0115] Off-design operation of the system may occur when one or more design conditions are changed, such as, but not limited to, gas flow rate, compressed gas pressure, compressed gas temperature, initial CO2 concentration, particle diameter, particle density, and particle mass loading or ratio. Control of mass flow rate can be achieved by employing an adjustable supersonic condensation nozzle throat and / or varying the inlet pressure prior to compression. During supersonic flow startup and / or to control flow characteristics (particularly Mach number) at different points throughout the system, it may be necessary to vary the geometric area ratio (i.e., the ratio between the local area of ​​the supersonic condensation nozzle and the throat area). Variation of the geometric area ratio can be achieved by adjusting the supersonic condensation nozzle throat area, by moving the supersonic condensation nozzle wall using an actuator, and / or by providing suction holes at different points in the system.

[0116] The above description is exemplary only, and those skilled in the art will recognize that changes may be made to the described embodiments without departing from the scope of the invention disclosed. Other modifications falling within the scope of the invention will be apparent to those skilled in the art, and in view of a review of this disclosure, these modifications are intended to fall within the appended claims.

Claims

1. A method for capturing a target condensable gas, comprising: Accelerate the gas flow containing the target condensable gas component into a supersonic gas flow in the nozzle, injecting particles so that the particles are in the supersonic gas flow, whereby the target condensable gas condenses on a portion of the particles, generating an expansion wave in a particle flow containing target gas condensate to separate the particle flow into a first flow path in which the concentration of particles containing target gas condensate is increased and a second flow path in which the target condensable gas content of the gas is reduced, and The first flow path is physically separated from the second flow path. 2 . The method of claim 1 , further comprising heating the first flow path to separate the target gas condensate from the particles.

3. The method of any one of claims 1 to 2, further comprising discharging the second flow path to the environment.

4. The method of any one of claims 1 to 3, further comprising compressing the gas stream containing the target condensable gas prior to said accelerating.

5. The method of claim 4, further comprising collecting said gas containing target condensable gas components prior to said compressing.

6. The method according to any one of claims 1 to 5, wherein Injecting particles into the supersonic gas flow includes injecting the particles into a converging section of the nozzle.

7. The method according to any one of claims 1 to 5, wherein Injecting particles into the supersonic gas flow includes injecting the particles into a throat section of the nozzle.

8. The method according to any one of claims 1 to 5, wherein Injecting particles into the supersonic gas flow includes injecting the particles into a diverging section of the nozzle.

9. A method according to any one of claims 1 to 8, comprising recovering heat from the second flow path of gas.

10. The method according to any one of claims 1 to 9, wherein Generating an expansion wave in the particle flow containing target gas condensate and physically separating the first flow path from the second flow path are performed in a first separation stage, and wherein the method further comprises utilizing at least one second stage of the first flow path in which the concentration of particles containing target gas condensate is increased, the second stage comprising: generating an expansion wave in the first flow path to separate the flow into a third flow path having an increased concentration of particles containing target gas condensate and a fourth flow path having a reduced target condensable gas content, and The third flow path is physically separated from the fourth flow path.

11. The method of any one of claims 1 to 10, comprising absorbing heat from the gas stream containing target condensable gas components upstream of the nozzle.

12. A system for capturing a target condensable gas, comprising: a supersonic condensing nozzle configured to receive a gas stream containing a target condensable gas component and accelerate the gas stream into a supersonic gas stream, at least one particle injector, located in the supersonic nozzle, for injecting particles so that the particles are positioned within the supersonic gas flow, whereby target gas condensate forms on a portion of the particles, an expansion device defining a passage having a convex angle to generate an expansion wave in a particle flow containing target gas condensate to separate the particle flow into a first flow path in which the concentration of particles containing target gas condensate is increased and a second flow path in which the target condensable gas content of the gas is reduced, and A flow splitter has at least a first channel, and the flow splitter is configured to collect the first flow path.

13. The system according to claim 12, wherein: The flow splitter includes a second channel configured to collect the second flow path. 14 . The system according to claim 12 , further comprising a heating unit configured to heat the first flow path to separate the target gas condensate from the particles.

15. The system according to claim 13, wherein: The flow diverter has an exhaust port for directing the second flow path to the environment.

16. The system of claim 13, wherein: The second channel includes a heat exchanger for recovering heat from the second flow path.

17. The system of any one of claims 12 to 16, further comprising at least one compressor for compressing the gas stream containing the target condensable gas component upstream of the supersonic nozzle.

18. The system of claim 17, further comprising a passage for collecting the gas stream containing the target condensable gas components and directing the gas stream to the at least one compressor.

19. The system of claim 18, further comprising a heat exchanger located in the channel for absorbing heat from the gas stream containing the target condensable gas component.

20. The system according to any one of claims 12 to 19, wherein The expansion device and the flow splitter form a first stage, the system comprising at least one second stage receiving the first flow path having an increased concentration of particles containing target gas condensate, the second stage comprising: a second expansion device defining a passage having a convex angle to generate an expansion wave in a particle flow containing target gas condensate to separate the particle flow into a third flow path in which the concentration of particles containing target gas condensate is increased and a fourth flow path in which the target condensable gas content of the gas is reduced, and The second flow splitter has at least a first channel, and the flow splitter is configured to collect the third flow path.

21. A supersonic condensation nozzle, comprising: Inlet and outlet ports; A channel located between the inlet end and the outlet end is configured to receive a fluid flow containing a target condensable gas component, wherein the internal geometry of the channel is defined sequentially from the inlet end to the outlet end: a converging section, in which the cross-sectional dimensions decrease in the direction of the fluid flow, for subsonic flows, a diverging section, wherein the cross-sectional dimension increases in the direction of the fluid flow, for supersonic flow, and a throat section located between the contracting section and the diverging section; wherein, based on a fluid flow parameter that varies according to the geometric shape, a condensation initiation region exists in the expansion section, in which the target condensable gas begins to condense; and Wherein, relative to the direction of fluid flow, the expansion gradient of the expansion section at the condensation initiation area is greater than the expansion gradient downstream of the condensation initiation area.

22. An apparatus for separating particles from a supersonic particle-laden gas flow, comprising: Inlet and outlet ports; A channel for gas flow located between the inlet end and the outlet end, the channel having convex corners on its channel surface, so that the gas flow containing particles generates expansion waves from the convex corners to separate the fluid flow into a first flow path located near a channel surface opposite the convex corner and having an increased particle concentration, and The second flow path is located near the channel surface having the convex corners and has a reduced particle content in the gas.

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