Target gas capture process and system using supersonic flow

Abstract

The system for capturing target condensed gas includes a supersonic condensation nozzle configured to receive a gas flow having a predetermined target condensed gas content and for accelerating the gas into a supersonic gas flow; at least one particle injection device within the supersonic nozzle for injecting particles into the supersonic gas flow, whereby target gas condensate is formed on some of the particles; an expansion device that generates an expansion wave in the flow of particles containing the target gas condensate, defining a conduit with a convex corner that separates the flow into a first flow path having particles with a high concentration of target gas condensate and a second flow path of gas with a lower target condensed gas content; and a flow divider having at least the first conduit, the flow divider configured to receive the first flow path.

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to U.S. Patent Application No. 63 / 447,743, filed February 23, 2023, the disclosure of which is incorporated herein by reference.

[0002] (Technical field) The present disclosure relates to a process for capturing a target gas, such as CO2, using supersonic flow, and related equipment. [Background technology]

[0003] The capture of carbon dioxide (CO2) from industrial processes remains a global challenge for environmental reasons. For example, a typical 500MW coal-fired power plant entails a mass flow rate of approximately 50,000 kg / h (≈440,000 tons / year) of emitted CO2 (at a CO2 concentration of 12% vol). Therefore, for industrial CO2 capture systems, the amount of gas to be processed is substantial. Various processes, technologies, and equipment have been developed to capture CO2, including storage, utilization, and sequestration. Some technologies use solid sorbents, liquid sorbents, or cryogenic CO2 separation.

[0004] In another application, when capturing CO2 directly from the atmosphere (CO2 concentration 410 ppm), a device capturing 1 ton of CO2 per hour would require a processing air flow rate of approximately 2,600,000 m3 at a capture efficiency of 50%. 3 It should be / h. Summary of the Invention [Problem to be solved by the invention]

[0005] Some gas separation systems use supersonic flow, which significantly reduces the gas temperature, allowing one vapor component to liquefy and then undergo inertial separation. Typically, such systems use vortex flow for inertial separation and are commonly used to separate water vapor and heavy hydrocarbons from natural gas during extraction. It is noteworthy that while such processes and systems are suitable for achieving separation of hydrocarbons due to their relatively high molecular weight, they may not be suitable for separating molecules such as CO2, which condense at a lower temperature than water vapor.

[0006] There are two phenomena that can initiate CO2 condensation: homogeneous nucleation and heterogeneous nucleation. Homogeneous nucleation spontaneously produces nanosized CO2 particles with a mass and size insufficient for inertial separation. Heterogeneous nucleation occurs at higher local temperatures and pressures than homogeneous nucleation due to the presence of extraneous nuclei. For example, water vapor already present in the gas mixture may freeze at a higher temperature than CO2 through homogeneous nucleation, forming nanosized particles on which heterogeneous nucleation of CO2 can occur. CO2 nucleation may then be followed by particle growth due to CO2 accumulation.

[0007] Therefore, there is a need to improve carbon dioxide capture methods by utilizing particle condensation and inertial separation. [Means for solving the problem]

[0008] In a first aspect, a method for capturing a target condensed gas is provided, the method comprising: accelerating a gas stream having a predetermined target condensed gas content into a supersonic gas stream in a nozzle; injecting particles into the supersonic gas stream so that the particles are present in the supersonic gas stream, whereby the target condensed gas condenses into some of the particles; generating an expansion wave in the target gas condensate-containing particle stream to separate the stream into a first flow path having particles with a high concentration of target gas condensate and a second flow path of gas with a reduced target condensed gas content; and physically separating the first flow path from the second flow path.

[0009] Further according to the first aspect, for example, the first flow path may be heated to separate the target gas condensate from the particles.

[0010] Further according to the first aspect, for example, the second flow path is vented to the environment.

[0011] Further according to the first aspect, for example, the gas stream having the target condensation gas is compressed prior to the accelerating step.

[0012] Further according to the first aspect, for example, a gas having a predetermined CO2 content is collected prior to the compressing step.

[0013] Further according to the first aspect, for example, injecting particles into the supersonic gas flow includes injecting the particles into a converging segment of a nozzle.

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

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

[0016] Further according to the first aspect, for example, heat can be recovered in the second flow path of the gas.

[0017] Further according to the first aspect, for example, the steps of generating an expansion wave in the flow of particles including target gas condensate and physically separating the first flow path from the second flow path are performed in a first separation stage, and the method further includes at least a second stage using the first flow path having particles with a high concentration of target gas condensate, the second stage including the steps of generating an expansion wave in the first flow path to separate the flow into a third flow path having particles with a high concentration of target gas condensate and a fourth flow path of gas with a lower content of target condensate gas, and physically separating the third flow path from the fourth flow path.

[0018] Further according to the first aspect, for example, the step of absorbing heat from a gas stream having a predetermined target condensed gas content upstream of the nozzle can be included.

[0019] According to a second aspect, there is provided a system for capturing target condensed gas, the system comprising: a supersonic condensation nozzle configured to receive a gas flow having a predetermined target condensed gas content and accelerate the gas into a supersonic gas flow; at least one particle injector within the supersonic nozzle for injecting particles into the supersonic gas flow, whereby target gas condensate is formed on some of the particles; an expansion device defining a conduit with a convex corner that generates an expansion wave in the flow of particles including the target gas condensate, separating the flow into a first flow path having particles with a high concentration of target gas condensate and a second flow path of gas with a reduced target condensed gas content; and a flow divider having at least the first conduit, the flow divider configured to receive the first flow path.

[0020] Further according to the second aspect, for example, the flow divider includes a second conduit, the second conduit configured to receive the second flow path.

[0021] Further 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.

[0022] Further according to the second aspect, for example, the flow divider has an outlet that directs the second flow path to the environment.

[0023] Further according to the second aspect, for example, the second conduit includes a heat exchanger that recovers heat from the second flow path.

[0024] Further according to the second aspect, for example, the at least one compressor may compress a gas stream having a predetermined target condensable gas content upstream of the supersonic nozzle.

[0025] Further according to the second aspect, for example, the conduit can collect a gas stream having a predetermined target condensable gas content and direct it to at least one compressor.

[0026] Further according to the second aspect, for example, the heat exchanger is within the conduit and can absorb heat from a gas stream having a predetermined target condensable gas content.

[0027] Further according to a second aspect, for example, the expansion device and flow divider form a first stage, and the system includes at least a second stage that accepts a first flow path having particles with a high concentration of target gas condensate, the second stage including a second expansion device defining a conduit with a convex corner that generates an expansion wave in the flow of particles having the target gas condensate thereon to separate the flow into a third flow path having particles with a high concentration of target gas condensate thereon and a fourth flow path of gas with a reduced content of target condensate gas; and a second flow divider having at least the first conduit, the flow divider configured to accept the third flow path.

[0028] According to a third aspect, there is provided a supersonic condensation nozzle comprising: an inlet end and an outlet end; and a conduit between the inlet end and the outlet end configured to receive a fluid flow having a predetermined target condensable gas content, the conduit having an interior geometry defining, from the inlet end to the outlet end, in order: a converging segment having a cross-sectional dimension decreasing in the direction of fluid flow for subsonic flow; a diverging segment having a cross-sectional dimension increasing in the direction of fluid flow for supersonic flow; and a throat segment between the converging and diverging segments, wherein, based on fluid flow parameters as a function of geometry, a condensation initiation region is located within the diverging segment, where initiation of condensation of the target condensable gas occurs, and the divergence gradient of the diverging segment is greater relative to the fluid flow at the condensation initiation region than downstream of the condensation initiation region.

[0029] According to a fourth aspect, there is provided an apparatus for separating particles from a supersonic particle-laden gas flow, the apparatus comprising an inlet end and an outlet end, and a conduit for gas flow between the inlet end and the outlet end, the conduit having a convex corner on a conduit surface of the conduit that causes the particle-laden gas flow to generate an expansion wave originating from the convex corner, separating the fluid flow at the outlet into a first flow path having a high concentration of particles near the conduit surface opposite the convex corner and a second flow path of gas with a reduced particle content near the conduit surface defining the convex corner.

[0030] In a fifth aspect, there is provided a system for capturing a target condensable gas that can include the supersonic condensate nozzle of the third aspect and / or the device of the fourth aspect, the system comprising: a supersonic condensate nozzle configured to receive a gas stream having a predetermined target condensable gas content and for accelerating the gas into a supersonic gas stream; at least one particle injector within the supersonic nozzle for injecting particles into the supersonic gas stream whereby target gas condensate is formed on some of the particles; an expansion device that generates an expansion wave in the stream of particles including the target gas condensate and defines a conduit with a convex corner that separates the stream into a first flow path having particles with a high concentration of the target gas condensate and a second flow path of gas with a reduced content of the target condensable gas; and a flow divider having at least the first conduit, the flow divider configured to receive the first flow path.

[0031] Reference is now made to the accompanying drawings, in which: [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a schematic diagram of a process and system for capturing a target gas, CO2, using supersonic flow, according to one embodiment of the present disclosure. [Figure 2] 1 is a graph showing a CO2 phase diagram with an isentropic expansion curve. [Figure 3] FIG. 1 is a schematic diagram of exemplary dimensions of an underlying conical converging-diverging nozzle. [Figure 4] 1 is a graph showing the effect of supersonic condensing nozzle design Mach number on the final CO2 concentration achieved. [Figure 5] 1 is an exemplary graph illustrating the effect of supersonic condensing nozzle design Mach number on gas-particle heat transfer coefficient. [Figure 6] FIG. 1 is a schematic diagram illustrating an exemplary optimized supersonic condensation nozzle and the underlying conical supersonic condensation nozzle before the start of CO condensation according to the present disclosure. [Figure 7]7 is an exemplary graph showing flow characteristics of the optimized supersonic condensing nozzle and the underlying conical supersonic condensing nozzle before the start of CO condensation of the schematic diagram of FIG. 6. [Figure 8] FIG. 7 is an exemplary graph showing a phase diagram of an optimized supersonic condensing nozzle before the start of CO condensation based on dTg / dx=3° C. / m for the conical supersonic condensing nozzle that is the basis for the schematic diagram of FIG. [Figure 9] 10 is an exemplary graph showing the mass ratio of deposited CO2 versus the reduction in total pressure of the flow. [Figure 10] FIG. 7 is an exemplary graph showing a phase diagram of an optimized supersonic condensing nozzle before the start of CO condensation based on dTg / dx=0° C. / m for the conical supersonic condensing nozzle that is the basis for the schematic diagram of FIG. [Figure 11] FIG. 7 is an exemplary graph showing a phase diagram of an optimized supersonic condensing nozzle before the start of CO condensation based on dTg / dx=−0.3° C. / m for the conical supersonic condensing nozzle on which the schematic diagram of FIG. 6 is based. [Figure 12] 10 is an exemplary graph illustrating the flow characteristics of an underlying conical supersonic condensing nozzle for particle injection at the nozzle inlet versus controlled injection in the diverging section. [Figure 13] 10 is an exemplary graph showing the total flow pressure of the underlying conical supersonic condensing nozzle for particle injection at the nozzle inlet versus controlled injection in the diverging section. [Figure 14] 1 is an exemplary graph showing a phase diagram for the 100,000 ton / year CO2 design case. [Figure 15] 1 is an exemplary graph showing axial CO2 concentration for the 100,000 tonnes / year CO2 design case. [Figure 16] 1 is an exemplary graph showing the evolution of axial particle size for the 100,000 tonnes / year CO2 design case. [Figure 17] 1 is an exemplary graph showing the total axial pressure drop for the 100,000 tonnes / year CO2 design case. [Figure 18] 1 is an exemplary schematic diagram of a basic configuration of a Prandtlmeyer expansion device. FIG. [Figure 19] FIG. 1 is an exemplary schematic diagram of the use of a Prandtlmeyer expansion device in combination with a flow diverter to remove particles from a supersonic flow. [Figure 20] FIG. 1 is an exemplary schematic diagram illustrating a possible arrangement of multiple Prandtlmeyer expansion devices. [Figure 21] 1 is an exemplary full-scale view of a CO2 capture plant according to the techniques of the present disclosure. [Figure 22] 1 is a cross section of an exemplary axisymmetric (3D) design of a supersonic condensing nozzle, Prandtlmeyer expander and flow separator assembly. [Figure 23] 1 illustrates the presence of particle-free zones in a Prandtlmeyer expansion apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0033] With respect to processes and systems designed to capture target gases such as CO2 using condensation of the target gas and subsequent inertial separation of particles, optimization challenges relate to the following aspects: The processes and related systems and apparatus taught herein may also be applied to other target gases, such that similar principles as taught herein for CO2 may also be applied to other target gases. The most common industrial gaseous pollutants are CO2, SO2, and SO4. X , H2S, NO X For simplicity, reference will be made herein to CO2, but this also includes other target gases. The terms "target gas" and "target condensed gas" are used herein to account for the fact that the process and system targets a gas to be isolated and separated / removed from the gas stream.

[0034] According to the process described herein, particles can first be injected into the stream to promote heterogeneous nucleation. The diameter and density of the selected particles must be large enough to enable efficient inertial separation, i.e., over a short distance while minimizing total pressure loss. On the other hand, for a given mass flow rate of injected particles, smaller and lighter particles provide a larger surface area available for CO2 deposition and reduce the total pressure drop of the stream due to particle entrainment. Additionally, the heat capacity of the particles must be small enough to minimize the difference with the gas temperature along the stream and accelerate the onset of condensation. However, if the particles have a large heat capacity, they will retain a low temperature while accumulating the latent heat of fusion from the solidified CO2, further promoting CO2 deposition. The injected particles can be in a solid or liquid phase, and the latter may or may not solidify before the onset of CO2 condensation.

[0035] Additionally, the geometry of the supersonic condensation nozzle through which the flow is accelerated (i.e., its length, the change in cross-sectional area along its length, and / or the shape) is optimally designed to minimize the total pressure drop due to friction and particle drag, and therefore the energy and cost required to operate the system, as well as to achieve optimal pressure-temperature conditions for CO2 condensation.

[0036] The location and conditions of particle injection can be either in the main gas stream before the supersonic condensing nozzle, or at some location within the supersonic condensing nozzle such as before CO2 condensation begins, but the temperature and velocity may be approximately equal to that of the gas at the injection point. After a sufficient amount of CO2 has condensed on the injected particles, some form of inertial separation must be performed to isolate the condensed CO2 from the CO2-removed gas stream.

[0037] This disclosure describes a process and system in which the captured gas is CO. However, the process 10 and related systems are applicable to other gases, whereby similar principles taught herein for CO apply to other gases. The most common industrial gas pollutants are CO, SO, and X, H2S, NO X etc. For simplicity, the remainder of this disclosure will use CO2 as the capture gas. The system includes a converging-diverging nozzle, or other type of supersonic condensing nozzle, where the CO2-containing gas is expanded to CO2-condensing conditions, followed by inertial separation of the solid condensed CO2 particles using a Prandtl-Meyer expansion, collection of the solid condensed CO2 particles, and then a diffuser that slows the gas flow to ambient conditions.

[0038] The injection of micrometer-sized particles is a key principle of this disclosure. This creates a well-defined surface (i.e., condensation nuclei) suitable for heterogeneous nucleation of CO2, enabling inertial separation. Referring to the drawings, and more particularly to FIG. 1, a CO2 capture process 10 using supersonic flow with particle injection is shown. The particles provide a surface for CO2 to condense. Alternatively, the particles can be solid materials, i.e., solid phases at the operating conditions of the process. By way of specific example, the particles can be spherical, tetrahedral, or irregularly shaped. Particle sizes range, but are not limited to, from 0.1 to 50 microns. Exemplary solid materials can be, but are not limited to, silica, activated silica gel, graphite, superactivated carbon, titanium dioxide, aluminum oxide, silicon carbide, barium carbonate, magnesium oxide, various coal mining wastes, ice, dry ice, or liquids such as water, hydrocarbons, or liquid nitrogen.

[0039] Process 10 can collect gas from an industrial process, such as that shown at A. The collected gas contains CO2 and can be compressed at B using any suitable compressor(s). The compressors can be adiabatic, isothermal, or other polytrol processes where compressor cooling is performed. In the isothermal case, the work of compression can be reduced by approximately 40% compared to the adiabatic case. The heat recovered from compressor cooling can be reused as a waste heat source for various purposes, allowing the operating energy demand of the CO2 capture system to approach net zero. For example, the recovered heat can be used in industrial process A or in other processes or equipment requiring heat (e.g., space heating, water heating, process heating, etc.).

[0040] Referring to FIG. 1 , process 10 is shown schematically and includes at least three consecutive steps, which may also be considered two steps: generating a supersonic flow (step 20); performing inertial separation using a convex corner to generate an expansion wave in a Prandtlmeyer expansion (step 30); and collecting CO2-coated particles and slowing the flow to ambient conditions (step 40). Step 40 may also include separating the output from Prandtlmeyer expansion device 31 into solid condensed CO2 particles (e.g., in duct 41A) and a CO2-lean gas (e.g., in duct 41B). While the term "step" is used herein, a step may be considered a substep and / or may include various steps or substeps. For example, as described below, generating a supersonic flow (step 20) may include a particle injection step or substep and / or a CO2-laden gas compression step or substep. Additionally, optionally, process 10 may include collecting industrial gases of the industrial process as shown at A and / or compressing the collected gases using compressor(s) at B.

[0041] In step 20, CO2 contained in a gas, such as air or combustion products, is condensed to agglomerate into small particles in a solid state. This can be achieved by accelerating a pressurized gas stream containing CO2 to supersonic speeds. Step 20 can also include injecting solid particles, such as micrometer particles, into the stream. These particles can be injected at any point before conditions permitting condensation are reached, including, but not limited to, the upstream plenum, the converging section of a supersonic condensing nozzle, the throat of a supersonic condensing nozzle, and / or the diverging section of a supersonic condensing nozzle upstream of condensation. Note that exhaust gas from industrial process A may already contain a significant amount of small particles in the desired size range. As the gas accelerates, it expands and cools. Under these conditions, CO2 contained in the stream changes phase and condenses into a solid when the appropriate temperature is reached; for example, the sublimation temperature of CO2 is approximately -80°C (193 Kelvin) at atmospheric pressure. As an example, as shown in the phase diagram of Figure 2, the sublimation temperature of CO2 is a function of pressure, with the sublimation curve at approximately -80°C (193 Kelvin) at a pressure of 101 kPa. This pressure is specifically the partial pressure of CO2 in the main gas stream, which is a function of the CO2 concentration level. Condensation of CO2 into the solid state occurs on the surfaces of the microparticles previously injected into the stream in step 20. As a result, at the exit of this step 20, a supersonic stream of gas from which gaseous CO2 has been removed is obtained, carrying particles coated with solid CO2.

[0042] In step 30, inertial particle separation occurs. This occurs according to a Prandtl-Meyer expansion wave, where the supersonic gas flow is subjected to a convex corner, generating an essentially stationary, steady, two- or three-dimensional expansion wave. While the supersonic gas flow is displaced by the expansion wave, the small particles maintain their trajectory due to their inertia. Particles can be efficiently separated using this technique if the product of density and diameter squared is sufficiently large. Thus, CO2-coated particles collect in the path outside the convex corner. To enhance separation efficiency, a magnetic field can be applied along with particles having appropriate magnetic properties. Alternatively, to aid in particle separation from the gas flow, the particles can be charged prior to injection or by interaction with the flow, and an electric field can apply an electrostatic force, or a transverse magnetic field can apply a Lorentz force. The number of Prandtl-Meyer expansion devices, either in series or parallel, can be optimized to reduce overall system losses and increase separation efficiency, with the goal of increasing final CO2 purity.

[0043] As part of step 30, inertial separation, in contrast to known processes, uses Prandtlmeyer expansion waves instead of shock waves or vortices. While shock waves and vortices generally increase the gas temperature, the use of Prandtlmeyer expansion waves results in cooling of the gas. Cooling the gas reduces the risk of CO2 vaporization on the surface of the microparticles.

[0044] In step 40, a portion of the CO2-coated particles are removed from the gas stream. One approach taken in step 40 to accomplish this separation is to split the flow into two or more trajectories, for example, via two conduits, as shown in FIG. 1 as flow divider 41. Divider 41, sometimes referred to as a splitter or separator, can be a pair of conduits branching off from a single conduit. Alternatively, flow divider 41 can be a pair of separate ducts, conduits, or the like, into which the output from one or more Prandtlmeyer expansion devices 31 is directed. The first conduit is intended for the gas stream with most of the CO2 removed, while the second conduit is intended for the gas stream enriched with solid CO2-coated particles. The two conduits may have the form of a supersonic diffuser to gradually slow the supersonic flow until a stagnation condition is achieved, restoring the full pressure of the flow. This slowing process may involve a shock wave. In a variant, the supersonic diffuser may have the shape of a converging-diverging nozzle but with an adjustable throat to allow for efficient supersonic flow initiation. The supersonic diffuser is carefully designed to minimize total pressure loss, including minimizing the amplitude of the shock wave described above. Thus, the exit of process 10 may result in gas containing a high content of particles coated with solid CO2. The CO2-depleted gas may be vented to the environment or otherwise treated. In another embodiment of the present disclosure, a turbine, for example, in duct 41B, may be used to recover work that can be used to drive the compressor of B, particularly as an example of energy recovery.

[0045] Process 10 can include other steps for storing, using, or separating the CO2 in a solid state on the particles. Alternatively, process 10 can perform a separation step in which solid CO2 is separated from the particles by sublimating the CO2 from the solid state to a gaseous state. One possible approach to inducing sublimation is to raise the temperature of the particles above the sublimation temperature of CO2, which is approximately −80° C. (193 Kelvin) at atmospheric pressure. This is essentially done during pressure recovery, where the particle-rich gas is slowed down and its temperature increases. The heat of sublimation can be recovered from the compressor, resulting in compressor cooling and reduced compressor work (i.e., approaching isothermal compression). The same can be done, for example, to cool compressed gas exiting the compressor before step 20, to cool exhaust gas from an industrial process, or to directly cool particles before reinjection into the process. The particles can also be exposed to ambient conditions to sublimate the CO2 in another way. The particles can then be recovered for reinjection in step 20 of process 10. This is one possible result of solid state CO2 on the particles exiting step 40.

[0046] Still referring to FIG. 1 , as part of step 20, a supersonic condensing nozzle 21 is used in conjunction with one or more injectors 22. The supersonic condensing nozzle 21 has a specific geometry and dimensions as a function of the incoming total pressure, temperature, gas flow rate, CO2 concentration, injected microparticle size, density, mass fraction, and heat capacity. The supersonic condensing nozzle geometry, in this context, refers to the axial profile, cross-sectional variation, and length. This is optimized, as shown below, to maximize CO2 capture relative to the total pressure drop across the system, which represents the system's work output. The optimization of the supersonic condensing nozzle geometry and injection parameters is based on a mathematical model that simultaneously integrates nucleation and growth models, cross-sectional variation, wall friction and heat transfer, microparticle injection, particle drag, and heat transfer. The supersonic condensing nozzle also has a geometry aimed at avoiding expansion wave reflection and / or compression wave reflection and / or shock wave formation.

[0047] The total pressure drop in a supersonic condensing nozzle can be attributed to particle entrainment, wall friction and heat transfer, and the latent heat released from CO2 condensation. For a target amount of captured CO2, the latent heat is a fixed value. The effect of wall friction can be reduced by increasing the size of the supersonic condensing nozzle, i.e., by passing the entire gas flow through one large supersonic condensing nozzle instead of splitting the flow into several smaller supersonic condensing nozzles. The remaining loss factor to minimize is particle entrainment. For a given particle size and mass fraction, this can be done by modifying the geometry of the supersonic condensing nozzle shortly after condensation begins to reduce the velocity and / or temperature difference between the particles and the gas, or by injecting the particles just before condensation begins, but at a temperature and velocity roughly equal to that of the gas phase.

[0048] As shown in FIG. 2, an exemplary phase diagram for CO2 is presented, including flow pressure and temperature, showing zones where CO2 is a solid, liquid, and gas. At ambient temperature and pressure, CO2 is in a gaseous state. When accelerated to supersonic flow, as in step 20 of process 10, the pressure and temperature decrease. As shown in FIG. 2, the gas undergoes a near-isentropic expansion as a function of the flow Mach number, based on the pressure and temperature conditions. CO2 condensation occurs when the gas expands and reaches the solid phase zone of the phase diagram. In practical terms, the onset of condensation of CO2 to a solid occurs when the CO2 characteristic crosses the extrapolated line 505 of the liquid / vapor curve (VL line) in FIG. 2.

[0049] Step 20 of process 10 relies on solid condensation to aid in CO2 capture. Nucleation and growth rates must be considered when designing the components of the system used in process 10. Heterogeneous nucleation rates may be affected by temperature, free energy of droplet formation, particle size, surface tension, and / or saturation level. Growth rates are affected by particle size, CO2 partial pressure, stream and particle temperatures, CO2 molar volume, and sticking coefficient. Because CO2 condensation is an exothermic process, gaseous CO2 must release latent heat to the surrounding gas in order to undergo a phase change and condense into a solid. This heat transfer results in a temperature increase in both the gas and the particles, which may slow or prevent condensation.

[0050] To achieve adequate CO2 condensation, the condensation rate must exceed a predetermined threshold. In contrast to conventional systems that do not consider condensation control, process 10 and related systems require condensation control to efficiently capture CO2. It is possible to control condensation and promote the initiation of nucleation by varying the cross-sectional dimensions and / or area along the length of the supersonic condensing nozzle. Process 10 and related systems can enable CO2 condensation control more suited to CO2 capture, namely, CO2 condensation control by injecting micrometer particles into the gas stream. In fact, the particles injected into the stream act as nucleation sites, increasing the available surface for condensation. To significantly increase the available size, the injected particles must be small, preferably on the micrometer scale. Particle injection can increase drag because the gas must entrain the injected particles at a velocity slower than the gas velocity. Due to the use of a supersonic condensing nozzle in step 20, the gas is continuously accelerated within the supersonic condensing nozzle. The drag associated with particle injection results in a pressure drop and a decrease in Mach number. Additionally, friction can lead to increased temperatures, which can adversely affect condensation. Therefore, particle injection must take these factors into consideration to maintain proper condensation in step 20.

[0051] Particle injection also enhances inertial separation because particles are denser and have greater inertia than gases, and the particles are separated using expansion waves in step 30. However, larger particles, which may promote inertial separation, require more energy to accelerate and may have less surface area available for condensation, so an optimal particle size must be used. Therefore, injection parameters such as particle number, injection velocity, and injection uniformity must be controlled, as well as particle properties such as particle size, density, temperature, and surface tension.

[0052] The first aspect of a supersonic condensing nozzle is its design Mach number. Considering a simple convergent-divergent nozzle with a specific length 301, as shown in Figure 3, the design Mach number indicates the ratio between the exit area 302 and the throat area 304 (i.e., the nozzle area ratio). Supersonic condensing nozzles can be axisymmetric or two-dimensional rectangular, or a combination of axisymmetric to two-dimensional rectangular shapes or vice versa. From a gas dynamics perspective, as the design Mach number increases, the area ratio increases, resulting in decreased exit temperature, pressure, and density. A decrease in gas temperature should seemingly promote CO2 condensation. However, a decrease in gas-phase density reduces the heat transfer coefficient between the particles and the gas. Therefore, as the gas cools, the particle temperature at which CO2 condensation occurs no longer matches the gas temperature.

[0053] Figure 4 shows the effect of design Mach number on the exit CO2 concentration and, therefore, capture efficiency. For a given supersonic condensing nozzle length and particle characteristics, starting with a 15% CO2 concentration in this example, the exit CO2 concentration first decreases at 401 and reaches a minimum at a design Mach number of 6, 402. Further increases in design Mach number no longer improve performance as the particles become less sensitive to the surrounding gas. At the extreme design Mach number of 15, CO2 condensation is not predicted. Note that as the design Mach number increases, particle velocity increases, shortening particle residence time within the supersonic condensing nozzle. This also contributes to a reduction in the amount of CO2 captured. Figure 5 shows a comparison of heat transfer coefficients between design Mach numbers of 6 (point 402) and 10 (point 404). The heat transfer coefficient 410 for Mach 10 is 10 to 40 times lower than the heat transfer coefficient 406 for Mach 6 along the diverging section of the supersonic condensing nozzle due to the reduced gas density. It is noted that design space considerations may reveal that the optimum design Mach number may range from 2 to 10, preferably 3 to 8.

[0054] The reduction of particle drag effects can be achieved by optimally designing the geometry of the supersonic condensing nozzle. The goal is to reduce the mismatch between particle and gas velocities. Modifications to the geometry of the supersonic condensing nozzle can be applied before condensation begins, for example, from the beginning or throat of the supersonic condensing nozzle. However, this can delay the onset of condensation while minimizing drag effects. Another example is optimizing the geometry of the supersonic condensing nozzle after condensation begins. In this case, the geometry of the supersonic condensing nozzle is not changed from its unoptimized base configuration until condensation onset is reached as soon as possible. The geometry of the supersonic condensing nozzle is then gradually modified to reduce the rate at which the gas is accelerated downstream of the supersonic condensing nozzle, thereby reducing the mismatch between particle and gas velocities. However, this is done without excessively affecting the particle temperature, since the particles are cooled by the surrounding gas. If the particle temperature were to increase excessively, the CO2 condensation rate would be adversely affected. Figure 6 previews a first example. A simple basic conical 4.5 m long convergent-divergent nozzle 501 is compared to an optimized 4.64 m long supersonic condensing nozzle 502. In this case, the throat position 550 of the supersonic condensing nozzle is at 0.5 m, and the onset of condensation 503 is observed approximately 1.75 m downstream from the supersonic condensing nozzle inlet, as predicted by the flow characteristics in Figure 7. The optimization 502 of the supersonic condensing nozzle geometry can be performed starting at 2.2 m 504 from the supersonic condensing nozzle inlet (i.e., 0.45 m after condensation onset). The condition for optimizing the supersonic condensing nozzle geometry in this case is to reduce the gas axial temperature gradient dT g / dx = 3 °C / m, where Tg is the gas phase temperature. The gas axial temperature gradient defines the rate at which the gas temperature can be increased (i.e., controlled) along the length of the supersonic condensing nozzle, and is given by dT in the above example. gA dx = 3°C / m represents a 3°C increase in gas temperature per meter. Figure 8 shows the phase diagram for this case. The starting state is located at 520, and the nozzle geometry change start state is located at 525. An increase in gas temperature 512 for the optimized supersonic condensing nozzle (e.g., 502 in Figure 6) can be observed when compared to the base case 511 for a simple conical supersonic condensing nozzle (e.g., 501 in Figure 6). As the gas state approaches the VL line extrapolation 515, this can lead to the cessation of CO2 condensation. Figure 9 shows the CO2 condensation velocity versus increasing total pressure (dm / dP0) change. The velocity value 900 begins at 1.75 m, the condensation start position 503 (Figure 6). The same result exists immediately before the supersonic condensing nozzle geometry optimization at 2.2 m 504 (Figure 6). A gain due to a beneficial reduction in particle drag losses is then observed (901). Note that the supersonic condensing nozzle 502 (FIG. 6) optimized according to this value of gas axial temperature gradient is slightly longer to achieve the same final amount of captured CO2. In this case, the recovery pressure ratio across the optimized supersonic condensing nozzle 502 (FIG. 6) is 18.3% better than the recovery pressure ratio across the simple conical supersonic condensing nozzle 501 (FIG. 6). The recovery pressure ratio here is defined as the ratio of the final total pressure to the initial total pressure. This results in a 7.3% reduction in the associated compression cost of the optimized supersonic condensing nozzle 502 (FIG. 6) when compared to the supersonic condensing nozzle 501 (FIG. 6).

[0055] Thus, a supersonic condensation nozzle can be described as having an inlet end and an outlet end. Between the inlet and outlet ends is a conduit. The conduit is configured to receive a fluid flow having a predetermined target condensable gas content (e.g., CO2). The internal geometry of the conduit sequentially defines, from the inlet end to the outlet end, a converging segment whose cross-sectional dimension decreases in the direction of fluid flow for subsonic flow, a diverging segment whose cross-sectional dimension increases in the direction of fluid flow for supersonic flow, and a throat segment between the converging and diverging segments. Based on fluid flow parameters as a function of geometry, a condensation initiation region (e.g., beginning at 503) is located in the diverging segment, where initiation of condensation of the target condensable gas occurs. The divergence slope of the diverging segment is greater at the condensation initiation region relative to the fluid flow than downstream of the condensation initiation region (as shown at 504). The divergence slope at the condensation initiation region can be said to differ from the divergence slope downstream of the condensation initiation region by a step in the value of the divergence slope; i.e., it is not gradual, although in some variations it can be. The diverging gradient described above can be two successively arranged truncated cones. In one embodiment, the transition has an edge. The particle injection can be at any of the converging, throat, or diverging segments to promote heterogeneous nucleation. In a variant, the injection occurs downstream of the condensation initiation region.

[0056] Exemplary dimensions for supersonic condensing nozzles are provided. The supersonic condensing nozzle can be, for example, an axisymmetric nozzle or a two-dimensional nozzle; FIG. 21 shows an example of an axisymmetric nozzle at 806. In an alternative embodiment, the minimum size (e.g., diameter) of the throat segment can vary between 0.01 m and 0.50 m, depending on the initial conditions, although other dimensions are contemplated. In such an embodiment, the Mach number at the exit end can be between 2 and 10, inclusive, although other Mach numbers are possible. In an alternative embodiment, for a two-dimensional nozzle, the divergence slope can be a half-cone angle between 3 and 70 degrees, inclusive. In an alternative embodiment, for an axisymmetric nozzle, the divergence slope can be a half-cone angle between 1 and 48 degrees, inclusive. The half-cone angle of the modified, optimized supersonic condensing nozzle can vary from zero (i.e., a constant area duct) to an angle less than or equal to the cone angle or divergence angle defined above for the basic, unmodified supersonic condensing nozzle. The half-cone angle may be defined as the angle from the central axis of the cone (i.e., right-angled cone) to the sidewall. In a variation, the exit area (e.g., cross-sectional dimension) is 1.7 to 536 times the minimum throat area (e.g., cross-sectional dimension). The inlet area (e.g., cross-sectional dimension) may range from 2 to 10 times the minimum throat area (e.g., cross-sectional dimension), depending on the system piping. The length of the converging section of the supersonic condensing nozzle may vary between 1% and 10% of the total nozzle length, inclusive. When modifying the geometry of an optimized supersonic condensing nozzle at or after the onset, i.e., in the condensation onset region, the distance between the throat section and the nozzle contour modification onset may be between 10% and 60% of the length of the diverging segment, inclusive. The diverging portion of the modified supersonic condensing nozzle may be a right cone or may be a cone that is shaped to meet the required design conditions (i.e., dT g The modified profile may have a dA / dx that varies (i.e., a gradual, non-linear increase) from one position to another depending on the starting point (e.g., / dx, du / dx, etc.). The transition from the underlying supersonic condensing nozzle profile to the modified profile at or after the starting point may be abrupt or gradual.

[0057] Another possibility is shown in FIG. 10 at 506 for a 10 m long supersonic condensing nozzle. In this case at 506, the design condition after the start of condensation is dT g The gas axial temperature gradient is set to dT / dx = 0 °C / m. Compared to the basic conical supersonic condensing nozzle, a 30.1% improvement in recovery pressure ratio is realized, and an 8% reduction in compression cost is achieved. Figure 11 presents the final example 507 of a 6 m long supersonic condensing nozzle. Here, the gas axial temperature gradient is set to dT g Despite setting / dx=-0.3°C / m, a theoretical risk of reaching the extension of the VL extrapolation line 505 is observed. In this case, the gas temperature decreases after the supersonic condensing nozzle optimization position 525, but at a smaller rate than in the case of the underlying conical supersonic condensing nozzle 511. In fact, the operating line of the underlying supersonic condensing nozzle 511 in this case is closer to the VL extrapolation line 505 due to the smaller particles used. This increases the surface area for heat transfer between the particles and the gas, leading to a relatively higher gas temperature. In this case, the expected increase in recovery pressure ratio is 20.6%, resulting in a 5.6% reduction in compression cost.

[0058] The parameters for the above example are outlined in Table 1 below. Note that the above example is scaled for a flue gas source of 100,000 tonnes CO2 / year with a CO2 concentration of 15% by volume. Therefore, the effectiveness of a supersonic condensing nozzle to promote CO2 condensation while minimizing pressure drop is a function of the gas temperature axial gradient, dT g It has been shown that / dx can be improved by properly matching the supersonic condensation nozzle geometry (outline and length), the existing suspension of liquid-solid-gas composition, gas total pressure and temperature, humidity, particle size, density, specific heat, mass ratio, and CO2 concentration in the inlet gas. Optimizing the geometry of the supersonic condensation nozzle to achieve a specific target gas temperature axial gradient leads to a significant improvement in the total pressure drop for the same amount of condensed CO2.

[0059] Similarly, in another embodiment, the gas axial temperature gradient dT gThe geometry of the supersonic condensing nozzle can be further optimized by adjusting / dx as a function of axial position instead of having a constant value. g / dx from one axial position to another.

[0060] In another embodiment, optimization of the supersonic condensing nozzle can be achieved by controlling other parameters, such as the gas velocity u axial change, the gas axial velocity gradient du / dx, the gas axial pressure gradient dP / dx, or the gas axial density gradient dρ / dx, or combinations thereof, along the length of the supersonic condensing nozzle. Table 1: Summary of operating parameters for cases 1, 2, and 3 using graphite particles with a mass fraction of 0.3. JPEG2026507057000002.jpg243162

[0061] Reducing losses due to the acceleration of injected microparticles can be achieved by injecting the particles somewhere within the supersonic condensing nozzle rather than before the nozzle. However, the particle temperature and velocity must be as close as possible to that of the gas. Particles can be injected into the converging section of the supersonic condensing nozzle (i.e., before the throat) or into the diverging section either before or after the theoretical onset of condensation.

[0062] Recalling Case 1 in Table 1, Figure 12 shows a comparison of flow characteristics for Case 521, which injects conventional particles into an inlet gas suspension, and Case 601, which injects particles into the diverging section of a supersonic condensation nozzle. For comparison, in this case, the injection location 600 is set 3 m downstream from the supersonic condensation nozzle inlet (i.e., approximately 1.5 m downstream from the theoretical condensation start location 513) to produce the same final CO2 concentration as the conventional scenario 521. As can be seen from Figure 12, the gas stream expands at 601 and initially cools without friction losses due to particle drag, although friction losses with the wall remain. Next, at 600, in the diverging section of the supersonic condensation nozzle, particles are injected to provide a surface for CO2 to condense and solidify. To avoid rapid gas heating, drag losses, and the formation of localized shock waves that may delay or prevent CO2 condensation, the temperature and velocity of the injected particles must be equal to the temperature and velocity of the gas phase at injection location 600. It is also observed that the theoretical condensation onset location 513 is approximately 0.5 m earlier for the particle injection location controlled scenario than for the normal scenario onset location 503 (FIG. 6) due to reduced particle drag losses. FIG. 13 shows the full pressure profiles for the normal scenario 602 and the controlled particle injection location scenario 603, which result in a 120% increase in recovery pressure ratio and a 35% reduction in associated costs, respectively. Table 2 provides a further comparison of both particle injection scenarios, Case 2 and Case 3. Note that the supersonic condensation nozzle geometry optimization (based on gas temperature axial gradient or other parameters, or a combination thereof) 502 (FIG. 6) and the particle injection location controlled scenario 601 (FIG. 12) can be performed simultaneously prior to condensation onset to benefit from both techniques. Table 2: Comparison of normal particle injection at the supersonic condensing nozzle inlet and controlled particle injection in the diverging section of the nozzle (Cases 1, 2, and 3). JPEG2026507057000003.jpg105168

[0063] The above examples demonstrate the potential for enhanced supersonic CO2 capture by employing the presented approach. However, optimization will depend on the specific application or situation to provide the most efficient full-scale CO2 capture and separation system. As an example, Table 3 shows a design example using 3-micron graphite particles in a 4.5-m long conical supersonic condensation nozzle. Figures 14, 15, 16, and 17 show the phase diagram, axial CO2 concentration, particle size, and total flow pressure, respectively. As can be seen from Figure 16, in this case, CO2 deposition significantly increases the particle size to 4.4 microns, which can be useful in the design of the separation section. Table 3: 100,000 ton / year design examples JPEG2026507057000004.jpg210152 JPEG2026507057000005.jpg76152

[0064] Referring to FIG. 1, the inertial separation step 30 relies on the expansion of a supersonic gas stream containing solid CO2-coated particles to accelerate the gas stream and deflect it using Prandtlmeyer expansion waves. Thus, particle streamlines diverge from the gas streamlines and converge toward the opposite side of the duct, where a flow divider is inserted at a specific height to separate the particle-rich stream. This is accomplished with an expansion device 31 featuring a convex corner 31A, referred to as a Prandtlmeyer expansion device 31. The corners of the expansion device can be stepped, smooth, or sharp, as opposed to rounded. The sharpness of the convex corner 31a can generate standing expansion waves radiating from the sharp convex corner. This device is shown in detail in FIG. 18. Opposite the convex corner 31A is an upper wall 31B, and adjacent to the convex corner 31A on the downstream side is a lower wall 31C. The upper wall 31B can be designed to avoid reflection of the expansion wave 601 and reduce the risk of shock waves before, during, and / or after separation. Due to its inertia, the solid CO2-covered particle 602 follows a different path 603 than the path of the gas 604 and impacts the upper wall 31B at location 605. The particle 602 represents at least one particle in the flow suspended within the gas stream. The particle can then be captured using various methods, including, but not limited to, a porous medium through which the particle can pass, an electric field, a magnetic field, a moving belt, a suction wall, and / or a liquid film along the upper wall 31B, and / or combinations thereof. Note that top and bottom refer to the orientation of the device 31 in FIG. 18. The top wall is the wall opposite the convex corner, and the bottom wall is the wall adjacent to the convex corner. However, in use, the top and bottom may not coincide with gravity, and the top wall may instead be referred to as the distal or contralateral wall, and the bottom wall may be referred to as the proximal or adjacent wall, for example.

[0065] One possible separation method, shown in FIG. 19, is a flow divider 606 positioned relative to the impingement zone 610 to split the duct into two separate ducts 41A and 41B, with different particle concentrations between the two ducts. Ideally, duct 41A contains a higher concentration of particles than duct 41B. The trajectories of the separated particles and their entrainment in the process gas affect the final CO2 purity. The location and shape of the flow divider 606 are optimized to maximize particle capture efficiency and / or CO2 purity of the captured gas. This depends on the impingement zone 610 or the trajectories (i.e., impingement location) of the surviving particles 611. The flow divider 606 can be positioned before the impingement location 605, at the impingement location, or after the impingement location 605. This is a compromise between the purity of the CO2 captured from the particle-rich gas stream and the overall proportion of particles separated (i.e., captured CO2). A shock wave 607 may exist on one side of the flow divider 606 without affecting the particle trajectories before separation. This shock wave may be primarily an associated or separate oblique shock wave, and depending on the shape and flow characteristics of the flow dividers, this shock wave may appear in one or both of the flow dividers, but preferably not in duct 41A, which contains the higher concentration of particles.

[0066] 19, the use of the flow divider can be combined with other separation technology implementations, such as, but not limited to, electric fields, magnetic fields, moving belts, suction walls, and / or liquid films along the upper wall 31B, or any combination thereof. The liquid film injection along the upper wall 31B can be performed before and / or after the impingement location 605 and / or downstream within the separation duct 41A. This reduces particle rebound by creating a damping surface. This technique can also prevent process gas from being sucked in with the particles, as they may penetrate the liquid film. This can increase the final purity of the CO2. The liquid film can be implemented elsewhere in the overall system, such as in the supersonic condensation nozzle and / or the impingement zone 610 and / or the ducts 41A and 41B and / or downstream diffusers, to reduce the abrasive effects on the walls caused by particle impacts.

[0067] The Prandtlmeyer expansion device 31 (FIG. 1) allows for the creation of a generally particle-free zone 1101 along the lower straight wall of the duct following the convex corner 31A, as shown in FIG. 23. The height H of this particle-free zone 1101 from the lower wall 31C depends on both the flow characteristics (pressure, inlet Mach number, outlet Mach number) and the particles (size, shape, density). For example, larger, denser particles will produce a larger particle-free zone, as will lower pressure flows. As a result, the upper wall 31B of the Prandtlmeyer expansion device 31 and the flow diverter device 41 can be positioned relative to the particle-free zone to optimize CO2 purity and / or capture efficiency. In one embodiment, where particle bounce from the upper wall 31B is minimized, e.g., by a liquid film, the upper wall 31B can be positioned so that all or part of it coincides with the boundary of the particle-free zone. In another embodiment, where particle bounce is not negligible, the upper wall 31B can be positioned significantly within the particle-free zone to account for particle bounce.

[0068] Additionally, the dimensions of the Prandtlmeyer expansion device 31 (FIG. 1) depend on the Mach number and cross-sectional area of ​​the supersonic condensation nozzle exit. However, the design of the supersonic condensation nozzle depends on the size of the particle-free zone. Specifically, the height of the supersonic condensation nozzle exit or the height of the Prandtlmeyer expansion device 31 inlet cannot be significantly changed for a given flow condition without degrading the performance of the Prandtlmeyer expansion device 31. Therefore, in one embodiment of a system using a rectangular cross-section, the width of the Prandtlmeyer expansion device 31 (out-of-plane dimension in FIG. 18) must be adjusted so that the cross-sectional area matches that of the supersonic condensation nozzle exit. Because friction effects increase with surface area, it is advantageous to select flow conditions and particle types that allow the inlet to the Prandtlmeyer expansion device 31 to approximate a square cross-section. However, given that these parameters also affect the performance of the condensation subsystem, they must be optimized together.

[0069] Table 4 shows specific calculated examples of Prandtlmeier expansion device 31 configurations for different particle types. These are calculated for a flow rate of 14.6 kg / s and a total pressure at the Prandtlmeier expansion device 31 inlet of 1.5 bar. These cases are calculated with spherical graphite particles, but other particle types can maintain the same aerodynamic characteristics. Cases 1, 2, and 3 use the same particles and enter the Prandtlmeier expansion device 31 at the same Mach number. Comparing Cases 1 and 2, it is clear that increasing the final Mach number results in less process gas being entrapped with the particles. Cases 2 and 3 have the same final Mach number but different heights. Thus, Case 2 minimizes the proportion of process gas entrapped with the particles and increases the final CO2 purity, while Case 3 uses a higher Prandtlmeier expansion device 31 inlet height, resulting in a more square cross-section and minimizing frictional effects at the expense of entrapped process gas. Cases 4 and 5 are performed with 10 micron graphite, which requires a reduced inlet height for the Prandtlmeyer expansion device 31 to match the particle-free zone height. Case 6, with 50 micron graphite, results in an optimal square inlet cross section for the Prandtlmeyer expansion device 31, while Case 7, with 3 micron graphite, is close to the limit of particle size that can be conveniently separated, and requires a Prandtlmeyer expansion device 31 inlet height of 5 mm. Table 4: Separator parameters for the 100'000 ton / year design case JPEG2026507057000006.jpg135165

[0070] In the Prandtlmeyer expansion device 31 as described above, particles of sizes varying between 1 and 100 microns can be used, and material densities up to 500 kg / m 3 and 19,200 kg / m 3The particle-gas flow enters the Prandtlmeier expansion device 31 at a Mach number between 2 and 5 and may reach a Mach number between 3 and 6 after passing through the convex corner 31A. For a Prandtlmeier expansion device 31 with a rectangular cross section, the flow deflection angle α at the convex corner 31A may vary between 2 and 85 degrees. For a flow entering the Prandtlmeier expansion device 31 at a total pressure of 1.5 bar, the inlet height to the Prandtlmeier expansion device 31 may be between 5 mm and 0.5 m.

[0071] The dimensions of the Prandtlmeyer expansion device 31, such as the width and the flow deflection angle α of the convex corner 31a, may depend on the exit Mach number and height 706 (i.e., area) of the supersonic condensing nozzle exit. As discussed above, the height 706 depends on the mass flow rate per nozzle and should be maximized to minimize friction effects. However, there exists a relaxation distance where particle trajectories 603 follow the gas streamlines 604 (i.e., the particles are no longer inertially separated). The relaxation distance depends on the difference between particle velocity and gas velocity, as well as particle size and density.

[0072] The Prandtlmeyer expansion device 31 can be described as a device for separating particles from a supersonic particle-laden gas stream, i.e., a device not necessarily for use with a supersonic condensation nozzle. It can be said to have an inlet end and an outlet end and a conduit for gas flow between the inlet end and the outlet end, the conduit having a convex corner on a conduit surface of the conduit that causes the particle-laden gas stream to generate an expansion wave originating from the convex corner, causing the fluid flow at the outlet to separate into a first flow path having a high particle concentration near the conduit surface opposite the convex corner and a second flow path of gas with a low particle content near the conduit surface defining the convex corner.

[0073] The particle concentration in the impingement zone 610 is primarily affected by the relaxation distance of particles in the flow. If the length of the Prandtlmeier expansion device 31 is short relative to the relaxation distance, the particle concentration in the impingement zone 610 will be sufficiently high, resulting in acceptable separation efficiency. However, for longer Prandtlmeier expansion devices 31, the upper wall 31B and the flow divider 606 may be geometrically positioned after the relaxation distance. Therefore, the particle concentration in the impingement zone 610, and therefore the separation efficiency, will be significantly reduced. A possible solution to this problem is to divide the Prandtlmeier expansion device 31 into two or more shorter Prandtlmeier expansion devices. A larger number of Prandtlmeier expansion devices 31 with smaller inlet heights (and correspondingly larger lateral widths to accommodate the required flow rates) will increase the ability to separate finer particles, but will result in a higher inherent pressure drop.

[0074] In another embodiment of the present disclosure, two or more Prandtlmeier expansion devices 31 are arranged in a parallel cascade configuration, as shown in FIG. 20. For illustrative purposes, a Prandtlmeier expansion device 31 similar to the device depicted in FIG. 19 is shown; however, other Prandtlmeier expansion devices 31 with associated flow dividers can be used in a similar parallel cascade configuration. While three Prandtlmeier expansion devices 701, 702, and 703 are shown in FIG. 20 for illustrative purposes, any number of Prandtlmeier expansion devices can be used depending on the overall size of the system. The partitions between the ducts are positioned so that the leading edge 704 is on the first Mach wave 705 of each Prandtlmeier expansion device 701, 702, and 703, allowing each Prandtlmeier expansion device to function independently of the others. Depending on its thickness, the leading edge 704 may be accompanied by a weak shock wave without affecting the overall flow. In such an embodiment, the ducts 701A, 702A, 703A from which particles have been removed may be connected downstream of the separation devices, as may the ducts 701B, 702B, 703B containing concentrated CO. These ducts may be offset out of plane from the two-dimensional plane shown in FIG. 20 to achieve this. This embodiment allows for optimization of capture efficiency by allowing the dimensions of each Prandtlmeyer expansion device to be selected according to the particle relaxation distance and / or particle-free zone height, independent of the dimensions of the exit duct 706 from the supersonic condensing nozzle.

[0075] In another embodiment of the present disclosure, the final cross section of the supersonic condensing nozzle can be flattened into a rectangular cross section to match the aspect ratio of the cross section of the inlet of the Prandtlmeyer expansion device. Thus, the in-plane dimensions of the outlet of the supersonic condensing nozzle, such as that shown in Figure 19, can be adjusted depending on the relaxation distance and / or particle-free zone height of particles in the flow, while the out-of-plane dimensions can be adjusted to allow for the required flow rate of the system. This embodiment can also be combined with other proposed embodiments described herein, such as those described in the previous paragraph.

[0076] As a result of the above condensation and separation process, the CO2 remains largely in a solid state, carried by the particles, and is concentrated in the flow path, while the particle- and CO2-depleted stream is rerouted for subsequent physical separation in step 40, for example, by a stream separator 41, which may have a first conduit 41A and a second conduit 41B. A filter can be installed further downstream of the particle-rich separated stream to complete the particle separation process. Another scenario is to use a cyclone separator or similar device to separate the solid particles from the CO2-rich gas.

[0077] Although the various devices of the system operating process 10 are shown as separate components in Figure 1, the components may be arranged to form a continuous conduit that separates into one or more pairs of conduits within flow divider 41. Thus, supersonic condensing nozzle 21, Prandtlmeyer expansion device 31, and flow divider 41 may be said to be segments or sections of a conduit system.

[0078] Thus, process 10 can be generally described as for capturing gaseous contaminants such as CO2 and can include accelerating a gas having a predetermined CO2 content into a supersonic gas stream in a nozzle; injecting particles into the supersonic gas stream, thereby condensing solid CO2 on the particles; causing the stream of particles with solid CO2 to generate an expansion wave, separating the stream into a first flow path having a high concentration of particles containing 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.

[0079] The process 10 can operate using a system that can be generally described as having: a supersonic condensation nozzle configured to receive a gas having a predetermined CO content and for accelerating the gas into a supersonic gas stream; at least one particle injector within the supersonic condensation nozzle that injects particles into the gas stream, whereby solid CO condenses into the particles; a Prandtlmeyer expansion device that generates an expansion wave in the stream of particles including solid CO and defines a conduit with a convex corner that separates the stream into a first flow path having a high concentration of particles including solid CO and a second flow path of gas having a reduced CO content; and a stream separator having a first conduit and a second conduit, the stream separator configured to receive the first flow path and the second flow path and physically separate them with the first conduit and the second conduit.

[0080] A conceptual full-scale schematic of an exemplary CO2 capture plant using the process and system of the present disclosure is shown in Figure 21. The CO2-containing gas entering 801 can be at a temperature higher than ambient. The CO2-containing gas is cooled as needed through a first heat exchanger 802 designed to manage gas flow rate and cooling capacity. The CO2-containing gas can be cooled to ambient temperature or to a temperature between ambient and the original gas temperature. The first heat exchanger 802 can be water-cooled or air-cooled, preferably with an appropriate heat exchange coil. Outside air can optionally be used on cooler days, especially during cooler months. Heat can be recovered from the heat exchanger 802 for any appropriate heat load. A compressor stage 803, with one or more compressors 803 in an appropriate configuration (parallel, cascade), compresses the CO2-containing gas to the required pressure level before supersonic expansion. The compressed gas is then increased in temperature and can be cooled again via a second heat exchanger 804. Again, heat can be recovered from heat exchanger 804 for any suitable heat load. Compressor 803 and second heat exchanger 804 can be a series and / or parallel compressor and heat exchanger arrangement to handle and / or control a wide range of flow rates and / or achieve isothermal compression with minimal compression work. Captured heat from heat exchangers 802 and / or 804 and / or others can be directed to heat recovery applications. Injector 805 can be positioned to inject small particles. Injector 805 can be positioned within the intake plenum or any segment or section of supersonic condensing nozzle 806. Supersonic condensing nozzle 806 can be a single nozzle or multiple nozzles in parallel to handle and / or control a wide range of flow rates. Particles, including solid CO2, are separated through expansion device 807, which can include a flow divider. Prandtlmeyer expansion device 807 with flow divider can consist of a single and / or a series of Prandtlmeyer expansion devices. The particle-rich stream exits the 2D plane through an outlet shown as duct 808. Duct 808 can be designed to decelerate the particle-rich stream to near ambient pressure.Another possibility is for the separated particles to be collected in a reservoir 809. The reservoir 809 can allow CO2 sublimation and / or provide the heat of this sublimation for cooling purposes. The reservoir 809 can precede and / or replace a cyclone device to separate solid particles and / or possible liquid water from the CO2-rich gas stream 810. The recovered particles 811 can be returned to the particle injector 805. The recovered particles in 811 can be dried from humidity using a heater. The CO2-rich gas stream 810 can undergo further purification processes. The particle-lean gas stream 813 exiting the Prandtlmeyer expansion device with flow divider 807 can be slowed down to ambient pressure using a diffuser duct 812.

[0081] The final CO2 purity achieved can be controlled and / or improved by further processing the exit CO2-rich gas 810. This can be done by connecting two or more CO2 capture systems in series as shown in Figure 21. Further purification can be achieved using cryogenic CO2 purification and / or other gas separation techniques.

[0082] 21, the supersonic condensing nozzle 806, Prandtlmeyer expansion duct 807, and outlet ducts 808 and 812 can be axisymmetric (3D) and / or 2D in configuration and / or transitions from one to the other. The supersonic condensing nozzle 806 and / or Prandtlmeyer expansion device 807 with flow divider can be used to separate gaseous components other than CO, such as water vapor, SO x The process can be repeated in series with or without intermediate particle injection to separate CO, H2S, etc. When separating gas components other than CO2, the temperature of reservoir 809 can be controlled to sequentially sublimate each gas component at its corresponding sublimation temperature.

[0083] 22 shows one possible axisymmetric (3D) design combining a supersonic condensing nozzle 1001 with a throat 1002, a Prandtlmeyer expansion device 1003 with a convex corner 1004 and a flow separator 1005, a diffuser duct 1006 for CO2-lean gas 1007 with its throat at 1008, and a diffuser duct 1009 for CO2-rich gas with particles 1010 with its throat at 1011. Such an axisymmetric design with a central body can be advantageous as it provides a small height over the large circumference of the Prandtlmeyer expansion device 1003.

[0084] Off-design system operation may occur when one and / or more of the following design conditions are changed: gas flow rate, compressed gas pressure, compressed gas temperature, initial CO2 concentration, particle diameter, particle density, and particle mass loading or fraction. Control of mass flow rate can be achieved by using an adjustable supersonic condensing nozzle throat and / or by varying the inlet gas pressure before compression. Varying the geometric area ratio (i.e., supersonic condensing nozzle local area to throat area) may be necessary to control the flow characteristics, particularly the Mach number, during supersonic flow startup and / or at different stations throughout the system. This variation can be achieved by adjusting the supersonic condensing nozzle throat area, displacing the supersonic condensing nozzle wall using an actuator, and / or introducing bleed ports at different stations in the system.

[0085] The foregoing description is merely exemplary, and those skilled in the art will appreciate that modifications can be made to the described embodiments without departing from the scope of the invention as disclosed. Still other modifications that fall within the scope of the invention will be apparent to those skilled in the art in light of a review of the present disclosure, and such modifications are intended to fall within the scope of the appended claims.

Claims

1. 1. A method for capturing a target condensed gas, comprising: accelerating a gas stream having a predetermined target condensed gas content in a nozzle into a supersonic gas stream; injecting particles such that the particles are in the supersonic gas stream, whereby a target condensation gas condenses onto a portion of the particles; generating an expansion wave in the flow of particles containing target gas condensate to separate the flow into a first flow path having particles with a high concentration of target gas condensate and a second flow path of gas with a low content of target condensate gas; physically separating the first flow path from the second flow path; A method comprising:

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 claim 1 or 2, further comprising venting the second flow path to the environment.

4. 4. The method of claim 1, further comprising compressing the gas stream having the target condensed gas prior to the accelerating step.

5. 5. The method of claim 4, further comprising the step of collecting a gas having a predetermined target condensed gas content prior to said compressing step.

6. The method of claim 1 , wherein injecting particles into the supersonic gas flow comprises injecting the particles into a converging segment of the nozzle.

7. The method of claim 1 , wherein injecting particles into the supersonic gas flow comprises injecting the particles into a throat segment of the nozzle.

8. The method of claim 1 , wherein injecting particles into the supersonic gas flow comprises injecting the particles into a diverging segment of the nozzle.

9. 9. The method of claim 1, further comprising recovering heat from the second flow path of the gas.

10. The steps of generating an expansion wave in the flow of particles containing the target gas condensate and physically separating the first flow path from the second flow path are performed in a first separation stage, and the method further includes at least a second stage using the first flow path of particles containing the high concentration of target gas condensate, the second stage comprising: generating an expansion wave in the first flow path to separate the flow into a third flow path having particles with a high concentration of target gas condensate and a fourth flow path of gas with a low content of target condensate gas; physically separating the third flow path from the fourth flow path; 10. The method of claim 1, comprising:

11. 11. A method according to any one of claims 1 to 10, comprising absorbing heat from the gas stream having a predetermined target condensed gas content upstream of the nozzle.

12. 1. A system for capturing a target condensed gas, comprising: a supersonic condensing nozzle configured to receive a gas stream having a predetermined target condensable gas content and accelerate the gas into a supersonic gas stream; at least one particle injector within the supersonic nozzle for injecting particles such that the particles are in a supersonic gas stream, whereby target gas condensates form on some of the particles; an expansion device defining a conduit with a convex corner that generates an expansion wave in the flow of particles containing target gas condensate to separate the flow into a first flow path having particles with a high concentration of target gas condensate and a second flow path of gas with a low content of target condensate gas; a flow divider having at least a first conduit, the flow divider configured to receive the first flow path; A system comprising:

13. The system of claim 12 , wherein the flow divider includes a second conduit, the second conduit configured to receive the second flow path.

14. 14. The system of claim 12 or 13, further comprising a heating unit configured to heat the first flow path to separate the target gas condensate from the particles.

15. 14. The system of claim 13, wherein the flow divider has an outlet that directs the second flow path to the environment.

16. The system of claim 13 , wherein the second conduit includes a heat exchanger that recovers heat from the second flow path.

17. 17. The system of any one of claims 12 to 16, further comprising at least one compressor upstream of the supersonic nozzle to compress the gas flow having a predetermined target condensable gas content.

18. 20. The system of claim 17, further comprising a conduit for collecting the gas stream having a predetermined target condensable gas content and directing the gas stream to the at least one compressor.

19. 20. The system of claim 18, further comprising a heat exchanger within the conduit for absorbing heat from the gas stream having a predetermined target condensable gas content.

20. The expansion device and the flow divider form a first stage, and the system includes at least a second stage that receives the first flow path having particles with a high concentration of target gas condensate, the second stage comprising: a second expansion device defining a conduit with a convex corner for generating an expansion wave in the flow of particles having target gas condensate thereon and separating the flow into a third flow path having particles having a high concentration of target gas condensate thereon and a fourth flow path of gas having a lower content of target condensate gas; a second flow diverter having at least a first conduit, the second flow diverter configured to receive the third flow path; 20. The system of any one of claims 12 to 19, comprising:

21. an inlet end and an outlet end; a conduit between the inlet end and the outlet end configured to receive a fluid flow having a predetermined target condensable gas content, the conduit having an interior geometry comprising, in order from the inlet end to the outlet end: a converging segment having a cross-sectional dimension that decreases in the direction of said fluid flow for subsonic flow; a diverging segment whose cross-sectional dimension increases in the direction of said fluid flow due to supersonic flow; the conduit defining a throat segment between the converging segment and the diverging segment; A supersonic condensation nozzle comprising: a condensation initiation region is located in the diverging segment based on fluid flow parameters as a function of the geometry, and initiation of condensation of the target condensable gas occurs in the condensation initiation region; 10. A supersonic condensing nozzle, wherein a divergence slope of the diverging segment is greater at the condensation initiation region relative to fluid flow than downstream of the condensation initiation region.

22. 1. An apparatus for separating particles from a gas stream containing supersonic particles, comprising: an inlet end and an outlet end; a conduit for gas flow between the inlet end and the outlet end; Equipped with The conduit has a convex corner on a conduit surface of the conduit, and the convex corner causes the gas flow containing the particles to generate an expansion wave originating from the convex corner, and the fluid flow at the outlet is a first flow path having a high concentration of particles adjacent a surface of the conduit opposite the convex corner; a second flow path for the particle-depleted gas adjacent the conduit surface defining the convex corner; Device.

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