System and method of carbon capture and sequestration

(Mutual reference to related applications) This application claims priority to US Patent Application No. 12 / 247,902 filed October 8, 2008, which is hereby incorporated by reference in its entirety.

(Field of invention) The present invention relates to carbon capture and sequestration systems and methods.

(background) Carbon dioxide (CO₂) Emission capture and sequestration needs to be significantly improved if the climate change outcomes of such emissions can be controlled or reduced. CO from combustion and industrial processes, especially power plant flue gas₂Is probably the largest single greenhouse gas release. Most existing carbon capture and sequestration methods are a two-step approach. The first is CO from flue gas or other outgassing sources₂A method for separating the two is sought. These include liquid solvents, solid zeolites or CO into various membranes.₂Can be mentioned. However, the capture medium is its CO₂Must be regenerated without being released into the atmosphere, which is difficult to achieve with standard physical separation processes.

The second step is that CO₂The step of sequestering a gas or liquid by inserting it into an underground geological structure or into a layer of the deep sea. However, a very special geological structure is this CO₂Required for disposal, these are CO₂Not usually available at the release site. Therefore, the large cost and difficulty of transportation are added. Besides, CO₂It is unclear whether the can be permanently isolated underground. Often CO₂Corresponds to only a small percentage of the large amount of flue gas, processing a large flow of flow and making a small portion of it CO₂The two-step approach is also uneconomical, as it is wasteful and costly to collect.

Another CO₂Efforts for capture and quarantine include mining, crushing and transporting rock to its release site, where the crushed rock is used for CO.₂Including absorbing. But this requires a lot of heat and pressure. Mining rocks and using it as CO₂Against the source or CO₂Energy input and environmental costs to transport from the source, as well as accepting crushed rock and its CO₂The cost of energy to absorb is very high.

CO₂Other methods of capturing the substance include chemical absorption using a liquid such as an aqueous solution of amine or base, physical absorption in a suitable solution and membrane separation. All of these methods use an absorption medium, CO₂There is a problem that it is necessary to regenerate without letting go. Other capture methods such as physisorption and cryoseparation require a significant amount of energy in the form of heat or pressure.

A CO₂The capture method is CO₂(Or water and CO₂(Carbonic acid formed from and) is reacted with an aqueous solution of alkali to form a carbonate. But a major drawback of that effort is that the carbonate needs an energy-intensive process to separate the solid from the water in order to leave the process in solution with water. To do, or it requires a mechanical system to control the size, morphology, and weight of energy-intensive drying and the resulting drying products, large volumes of heavy, moist cement. Is to bring a paste like.

Some are CO from the ambient air₂We are trying techniques to capture and isolate the CO, but the CO between the ambient air and the flue gas₂Due to the large difference in concentration, they are CO from the power plant₂Not suitable for release. Ambient air generally has a CO between about 0.03% and about 0.04%.₂On the other hand, the combustion exhaust gas contains CO with a concentration of 3.0% or more.₂Contains. Very small amount of CO from very large amount of atmosphere₂To remove CO₂A large amount of CO from the flow of combustion exhaust gas, etc., which has a higher concentration₂Not feasible and unproductive like capture and quarantine.

<p> Therefore, there is a need for a commercially viable carbon capture and sequestration process that works on an industrial scale and is complete and permanent. In particular, carbon that does not use capture media that require complex and energy-intensive regeneration, and does not produce heavy, moist end products that require energy-intensive drying and other post-capture treatments. There is a need for a capture system. CO₂Permanent CO at the site of release₂There is an additional need for carbon capture and isolation processes to isolate. In summary, it is cost-effective, not energy-intensive, and CO₂There is a need for carbon capture and isolation systems that result in permanent isolation.</p>

<p> The present invention is known in many embodiments thereof by providing a chemical process in which carbon dioxide in the form of carbonic acid is reacted with an alkali to form water and a readily removable dry carbonate that precipitates from a solution. Greatly mitigates the disadvantages of carbon capture and isolation methods. Carbon dioxide sequestration is achieved by the above-ground disposal of the resulting carbonate. This process is an industrial scale CO at a relatively low cost₂Allows capture and quarantine. Embodiments of the present invention also require permanent on-site CO with relatively low energy consumption.₂Provides capture and quarantine.</p><p> In embodiments of the present invention, Vandor's Carbon Capture and Sequestration. A method of capturing or isolating carbon dioxide, known as Cycle) (VCCS), is provided in which a substantially non-aqueous solvent and alkali are mixed so that the solvent and alkali form a solvent suspension. .. This mixing step can be performed in any suitable mixing tank. The substantially non-aqueous solvent is preferably an alcohol and, in the most preferred embodiment, methanol. Thus, the alkali reacts with methanol to form methoxide, which can also contain solvated metal hydroxides. Combustion emissions containing water and carbon dioxide are mixed with a solvent suspension, resulting in a reaction that results in the formation of carbonates, water and heat. The terms "solvent" and "non-aqueous solvent" allow some significant amount of alkali to dissolve in it and force precipitation of any salt produced in a standard acid + base reaction. It is used interchangeably herein to mean any substantially non-aqueous solvent. The non-aqueous solvent comprises less than 50% water, and most preferably less than 10% water.</p><p> The gas is preferably flue gas from a power plant, but CO from any industrial process.₂It can be any type of exhaust gas containing. The gas is nitrogen (N₂) Is also contained. The term "combustion exhaust gas" is used herein to mean the flow of any exhaust gas containing either carbon dioxide and nitrogen or air, the exhaust gas being coal fuel, natural gas fuel, petroleum fuel. From the combustion exhaust pipes of power plants, including landfill gas (LFG) fuel or anaerobic digestive system (ADG) fuel power plants, or from cement production in kilns, glass, steel, rubber, paper, or From any industrial process, including but not limited to the production of other materials, the production of ethanol, and from any combination of combustion emissions and process gases.</p><p> In one embodiment, the ash is introduced into the solvent and the alkali is a component of the ash. As used herein, the term "ash" is meant to mean all types of alkali-containing ash from any source, including from fly ash, bottom ash and coal burning, wood burning and other biomass burning. Used for.</p><p> The carbon capture and isolation chemical process mixes water with an alkali, preferably methoxide, in which carbon dioxide-containing combustion exhaust gas is suspended in a solvent, substantially producing solid carbonate, water and heat. Includes making the reaction bring about. A small amount of carbonic acid is also formed in the reaction, and the carbonic acid reacts immediately with the alkali. These reactions can be carried out in any suitable reaction vessel. In a preferred embodiment, the carbonate precipitates from the solution and is removed from the tank. The removal of the precipitated carbonate is preferably carried out mechanically using an auger or another suitable mechanical device that allows the removal of the solid without leaving any liquid in the tank at the same location. Any methanol remaining with the carbonate evaporates when a moderate amount of low-grade heat is applied.</p><p> The water from the reaction in the reaction vessel forms a solution with the solvent, and the method further comprises removing the solution of the water with the solvent and separating the water from the solvent. .. After the water and solvent are separated, the separated solvent is remixed with the alkali, so that the solvent and alkali re-form a solvent suspension that can be used for further carbonation capture. To do. The separated water is returned to the solvent suspension in the reaction vessel, where it is added to the flue gas and methoxide to continue the reaction. In a preferred embodiment, the water is separated from the solvent by cooling the solution of the water and the solvent in a low temperature drying tank. When the solution is cooled, the water substantially settles at the bottom of the cold drying tank and the solvent rises substantially at the top of the cold drying tank. In some embodiments, a carbonate moves with a solution of its water and solvent and precipitates from that solution in the cold drying bath. A filter can be used to capture the larger solids in the reaction vessel and prevent those larger solids from moving to the low temperature drying vessel.</p><p> The residual water can be separated from the solvent by applying heat to the solution of the water and the solvent using a hot distillation vessel to at least partially evaporate the solvent. .. A partial vacuum can be used to remove the vaporized solvent from the distillation apparatus, and the vaporized solvent is condensed into a liquid by cooling to suit reuse in the carbon capture and isolation reaction. ..</p><p> Embodiments of the present invention may include methods of using nitrogen from the flue gas to provide cooling for the carbon capture and isolation process. The method involves liquefying the nitrogen and recovering cooling from the liquefied nitrogen. The cooling recovered from the nitrogen is then used to cool the solvent and provides cooling for the solvent regeneration step. The use of this nitrogen for cooling enhances the energy efficiency of embodiments of the present invention.</p><p> In a preferred embodiment, the flue gas further contains nitrogen, and the nitrogen is used in three ways. The first part of the nitrogen is used for cooling during the solvent regeneration process, the second part is used to increase the power of the power plant, and the third part is sold to customers away from the field. .. All nitrogen is initially compressed. For the parts used for cooling, the refrigerant source supplies the refrigerant to the heat exchanger, and the nitrogen is cooled in the heat exchanger so that it is substantially liquefied. Cooling can be recovered from its substantially liquefied nitrogen after being pumped and sent to the power cycle to increase the output of the power plant, which is the source of the flue gas. .. The recovered cooling is used to provide cooling for the cold solvent removal process that separates the water from the solvent as described below.</p><p> The second part of that nitrogen can be used to increase the power of the power plant. In a preferred embodiment, the first portion of this substantially liquefied nitrogen is compressed and heated. The heated and compressed nitrogen is directed to the steam cycle of the power plant to increase the power of the power plant. A second portion of this substantially liquefied nitrogen can be stored in a storage device. The second portion of the substantially liquefied nitrogen is pressurized by a pump. It is then evaporated and pointed through a hot gas expander to increase the power plant output. The third portion of this liquefied nitrogen is sold to off-site customers for a variety of applications, including as a refrigerant and as a fluid to enhance the recovery of oil and gas wells. In a preferred embodiment, the liquefied nitrogen is further purified by removing liquid argon, which is approximately 0.9% by volume of the recovered nitrogen stream and is a high value product that can also be sold on the market.</p><p> Embodiments of the invention include a carbon capture and isolation system that includes a carbon capture assembly and a solvent regeneration assembly. The carbon capture assembly may include a mixing tank and at least one reaction tank, as well as a solvent condensing device fluidly connected to the reaction tank. In the mixing tank the alkali is mixed with a substantially non-aqueous solvent to form a suspension. In one embodiment, the ash is introduced into the solvent and the alkali is a component of the ash. The non-aqueous solvent is preferably an alcohol, and in the most preferred embodiment is methanol. Thus, the alkali reacts with the methanol in the reaction vessel to form methoxide and possibly some metal hydroxide. A small amount of dimethyl carbonate (DMC) can also be formed, but it decomposes rapidly depending on its alkaline conditions.</p><p> The reaction vessel is fluidly connected to the mixing vessel, and therefore it receives a suspension of alkali and a substantially non-aqueous solvent from the mixing vessel on a first charge. The reaction vessel also receives combustion exhaust gas containing heat and carbon dioxide by the second input and water by the third input, so that carbonic acid, carbonate, water and heat are formed in the reaction vessel. Will be done. More specifically, the carbon dioxide and water and some small amount of carbonic acid resulting from the reaction in the reaction tank react with the alkali in the tank to result in the formation of carbonates, water and heat. .. The flue gas also contains nitrogen. In some embodiments, the carbon capture assembly further comprises a solvent condensing device fluidly connected to the reaction vessel, where cooling is used to condense the outflowing solvent moiety, which consists mostly of nitrogen.</p><p> The solvent regeneration assembly is fluid-connected to the reaction vessel and is fluid-connected to at least one heat exchanger, a low-temperature drying tank fluidly connected to the heat exchanger, and high-temperature distillation fluid-connected to the low-temperature drying tank. Includes tank. The solvent regeneration assembly preferably performs several intermediate heat recovery steps to warm the flow of most water arriving at the hot distillation tank and cooling the methanol vapor leaving the hot distillation tank. Has a heat exchanger.</p><p> The carbonate formed in the above reaction precipitates from the solution and is removed from the reaction vessel. The carbon capture assembly may further include an auger or other suitable device for removing the precipitated carbonate from the reaction vessel. The water derived from the reaction forms a solution with the solvent in the reaction vessel, and the solution of the water with the solvent is removed from the reaction vessel and directed to the solvent regeneration assembly. The water is separated from the solvent by a solvent regeneration assembly, and the separated solvent is returned to the mixing tank where it is remixed with the alkali to form a solvent suspension. Similarly, the separated water is returned to the reaction vessel to continue the reaction.</p><p> In some embodiments, only a small portion (eg, less than 10% by volume) of the carbonate remains in the solvent and moves with the solvent suspension in the solvent regeneration assembly. If the alkali selected is CaO, the solution of water and solvent does not contain any carbonate. If the alkali selected is KH, some carbonate will form a solution of its water + solvent. A small portion of the carbonate precipitates from the solvent suspension with the water separated from it. First, the separation process uses a low-temperature drying tank in which the solution of the water and solvent is cooled, so that the water substantially settles to the bottom of the low-temperature drying tank, and its The solvent rises substantially above the cold drying tank. Part of this separation process (or all in the more energy-intensive options) uses a hot distillation tank, in which heat is applied to the solution of the water and solvent and the partial vacuum is steamed. The solvent is removed from the hot distillation tank and the solvent in the vapor state is condensed.</p><p> Some embodiments may include a nitrogen liquefaction assembly that substantially liquefies the nitrogen contained in the flue gas and recovers cooling from the substantially liquefied nitrogen. The cooling recovered from the nitrogen can be used to cool the solvent and provide cooling for the solvent regeneration assembly. A portion of the liquid nitrogen is pumped by a cryogenic pump to the regenerated assembly under pressure. The solvent regeneration assembly heats the first portion of substantially liquefied nitrogen and directs the heated nitrogen to the steam cycle of the power plant to increase the power of the power plant. The storage device stores a second portion of the substantially liquefied nitrogen, releases a second portion of the substantially liquefied nitrogen, and directs it to a hot gas expander to generate electricity. Increase the output of the place.</p><p> Embodiments of the present invention mix a substantially non-aqueous solvent with an alkali, resulting in a chemical component (CO) of the combustion exhaust gas comprising the solvent and the alkali forming a solvent suspension.₂, Relatively most N₂, And contains a much smaller portion of argon). Water and combustion exhaust gas containing carbon dioxide and nitrogen are introduced into the solvent suspension. The alkali in the solvent suspension comes into contact with water and carbon dioxide in the flue gas, resulting in a series of rapid chemical reactions. The reaction results in the formation of carbonates, water and heat, with the mostly unreacted nitrogen portion remaining in the reaction vessel as a gas, accompanied by a small amount of evaporated solvent.</p><p> Most of it cools the nitrogen stream in a solvent condenser to liquefy the small amount of solvent that is returned to the methanol + alkali mixture. The residual mostly nitrogen gas stream is liquefied by compressing and cooling the nitrogen. In a preferred embodiment, the cooling portion of the substantially liquefied nitrogen is recovered and used to provide cooling for separating the water from the solvent. The nitrogen moiety used for its cooling is first compressed and pressurized by a pump using a low temperature liquid pump, and then heated by the heat recovered in the solvent regeneration assembly. .. The nitrogen is then directed to the steam cycle of the power plant, or a hot gas expander equipped with a generator, to increase the power of the power plant. A second portion of that substantially liquefied nitrogen can be preserved and then evaporated and directed through a hot gas expander to increase the power plant output. The third portion of the substantially liquefied nitrogen is sold to customers away from the field.</p><p> Therefore, a large-scale, safe and cost-effective chemical process is provided in the field where carbon dioxide in the form of carbonic acid reacts with alkali in solution to carbonate, water. And it can be seen that it forms heat. These and other features of the invention will be understood from the discussion of the detailed description of the invention below, along with the accompanying drawings in which the same reference numbers refer to the same parts throughout.</p><p> The aforementioned or other object of the present invention will become apparent by considering the following detailed description associated with the accompanying drawings.<u style="single">The present invention provides, for example, the following items.</u><u style="single">(Item 1)</u><u style="single"> A method of capturing or isolating carbon dioxide</u><u style="single"> A step of mixing a substantially non-aqueous solvent and alkali, resulting in the solvent and alkali forming a solvent suspension.</u><u style="single"> With the step of mixing the combustion exhaust gas containing water and carbon dioxide with the solvent suspension, a reaction occurs as a result of the reaction resulting in the formation of carbonates, water and heat.</u><u style="single">How to include.</u><u style="single">(Item 2)</u><u style="single"> The water from the reaction forms a solution with the solvent.</u><u style="single"> The step of removing the solution of water and solvent,</u><u style="single"> The step of separating the water from the solvent and</u><u style="single"> A step of remixing the separated solvent with the alkali, resulting in the solvent and alkali forming a solvent suspension.</u><u style="single"> With the step of returning the separated water to the solvent suspension and continuing the reaction.</u><u style="single">The method according to item 1, further comprising.</u><u style="single">(Item 3)</u><u style="single"> The method of item 1, wherein the carbonate precipitates from the solution.</u><u style="single">(Item 4)</u><u style="single"> The method according to item 3, wherein the precipitated carbonate is mechanically removed.</u><u style="single">(Item 5)</u><u style="single"> The method according to item 1, wherein the solvent is alcohol.</u><u style="single">(Item 6)</u><u style="single"> 5. The method of item 5, wherein the alcohol is methanol.</u><u style="single">(Item 7)</u><u style="single"> The method of item 6, wherein the alkali reacts with the methanol to form methoxide.</u><u style="single">(Item 8)</u><u style="single"> The method of item 7, further comprising the step of introducing ash into the solvent, wherein the alkali is a component of the ash.</u><u style="single">(Item 9)</u><u style="single"> The step of separating the water from the solvent cools the solution of the water and the solvent, so that the water substantially settles at the bottom of the cold drying tank and the solvent is at the top of the cold drying tank. The method according to item 2, which comprises a step of substantially ascending to.</u><u style="single">(Item 10)</u><u style="single"> The step of separating the water from the solvent is a step of applying heat to the solution of water and the solvent, a step of removing the vapor state solvent from the high temperature distillation tank using a partial vacuum, and a step of condensing the steam state solvent. The method according to item 2, including the step of making the solvent.</u><u style="single">(Item 11)</u><u style="single"> The combustion exhaust gas further contains nitrogen,</u><u style="single"> The step of compressing nitrogen and</u><u style="single"> The step of supplying the refrigerant to the heat exchanger and</u><u style="single"> A step of cooling the nitrogen in the heat exchanger, resulting in a substantial liquefaction of the nitrogen.</u><u style="single">The method according to item 1, further comprising.</u><u style="single">(Item 12)</u><u style="single"> The step of recovering the cooling from the substantially liquefied nitrogen,</u><u style="single"> With the step of providing cooling to separate the water from the solvent using the recovered cooling.</u><u style="single">The method of item 11, further comprising.</u><u style="single">(Item 13)</u><u style="single"> The step of compressing the first portion of the substantially liquefied nitrogen,</u><u style="single"> The step of heating the first portion of the substantially liquefied nitrogen,</u><u style="single"> The step of directing the heated and compressed nitrogen to the steam cycle of the power plant to increase the output of the power plant,</u><u style="single">The method of item 11, further comprising.</u><u style="single">(Item 14)</u><u style="single"> The step of preserving the second portion of the nitrogen, which is substantially liquefied,</u><u style="single"> The step of pressurizing the substantially liquefied nitrogen and</u><u style="single"> A step of evaporating the pressurized, substantially liquefied nitrogen,</u><u style="single"> The step of increasing the output of the power plant by pointing the pressurized and evaporated nitrogen through a high-temperature gas expander.</u><u style="single">The method of item 11, further comprising.</u><u style="single">(Item 15)</u><u style="single"> A carbon capture and isolation system</u><u style="single"> A carbon capture assembly comprising a mixing tank in which an alkali is mixed with a substantially non-aqueous solvent to form a suspension and at least one reaction tank, wherein the reaction tank is fluid-connected to the mixing tank. As a result, the reaction tank receives the suspension of alkali and solvent from the mixing tank by the first charge, receives the combustion exhaust gas containing carbon dioxide by the second charge, and receives the third charge. A carbon capture assembly, and a carbon capture assembly, and as a result, carbon dioxide, carbonates, water and heat are formed in the reaction vessel.</u><u style="single"> A solvent regeneration assembly fluidly connected to the reaction vessel, wherein the solvent regeneration assembly includes at least one heat exchanger, a low temperature drying tank fluidly connected to the heat exchanger, and the low temperature drying tank and fluid. Solvent regeneration assembly containing connected hot distillation tank</u><u style="single">System including.</u><u style="single">(Item 16)</u><u style="single"> 15. The system of item 15, wherein the carbon capture assembly further comprises a solvent condensing device fluidly connected to the reaction vessel.</u><u style="single">(Item 17)</u><u style="single"> The system of item 15, wherein the carbonate precipitates from the solution.</u><u style="single">(Item 18)</u><u style="single"> 17. The system of item 17, wherein the carbon capture assembly further comprises a mechanical device for removing the precipitated carbonate from the reaction vessel.</u><u style="single">(Item 19)</u><u style="single"> The system of item 15, wherein the solvent is methanol and the alkali reacts with the methanol to form methoxide.</u><u style="single">(Item 20)</u><u style="single"> The water forms a solution with the solvent in the reaction vessel.</u><u style="single"> The solution of water and solvent is removed from the reaction vessel and directed to the solvent regeneration assembly.</u><u style="single"> The water is separated from the solvent by the solvent regeneration assembly.</u><u style="single"> The separated solvent and the separated water are returned to the mixing tank and</u><u style="single"> The separated water is returned to the reaction vessel and the reaction is continued.</u><u style="single">The system described in item 15.</u><u style="single">(Item 21)</u><u style="single"> The solvent regeneration assembly separates the water from the solvent by cooling the solution of the water to the solvent, so that the water substantially settles to the bottom of the cold drying tank and the solvent is deposited. The system according to item 20, wherein the temperature rises substantially above the low temperature drying tank.</u><u style="single">(Item 22)</u><u style="single"> The solvent regeneration assembly heats the solution of water and solvent, removes the vaporized solvent from the hot distillation tank using partial vacuum, and condenses the vaporized solvent from the solvent. The system according to item 20, which separates water.</u><u style="single">(Item 23)</u><u style="single"> The system of item 15, wherein the ash is introduced into the solvent and the alkali is a component of the ash.</u><u style="single">(Item 24)</u><u style="single"> The system according to item 15, wherein the combustion exhaust gas further contains nitrogen.</u><u style="single"> Nitrogen liquefaction assembly that substantially liquefies the nitrogen and recovers cooling from the substantially liquefied nitrogen.</u><u style="single">Including</u><u style="single"> The recovered cooling is used to provide cooling for the solvent regeneration assembly.</u><u style="single">system.</u><u style="single">(Item 25)</u><u style="single"> The solvent regeneration assembly heats the first portion of the substantially liquefied nitrogen and directs the heated nitrogen towards the steam cycle of the power plant to increase the power of the power plant.</u><u style="single"> A storage device stores the second portion of the substantially liquefied nitrogen, releases the second portion of the substantially liquefied nitrogen, and releases the second portion of the substantially liquefied nitrogen. Point through a hot gas expander to increase the power plant's output,</u><u style="single">The system described in item 24.</u><u style="single">(Item 26)</u><u style="single"> It is a method of separating the chemical components of combustion exhaust gas.</u><u style="single"> A step of mixing a substantially non-aqueous solvent and an alkali, and as a result, the solvent and the alkali forming a solvent suspension.</u><u style="single"> A step of introducing water and combustion exhaust gas containing carbon dioxide and nitrogen into the solvent suspension,</u><u style="single"> The step of contacting the alkali in the solvent suspension with the water and the carbon dioxide in the combustion exhaust gas, resulting in a reaction that results in the formation of carbonates, water and heat.</u><u style="single"> A step of substantially liquefying a portion of the nitrogen by compressing and cooling the nitrogen.</u><u style="single">How to include.</u><u style="single">(Item 27)</u><u style="single"> The step of recovering the cooling from the substantially liquefied nitrogen,</u><u style="single"> With the step of providing cooling to separate the water from the solvent using the recovered cooling.</u><u style="single">26. The method of item 26, further comprising.</u><u style="single">(Item 28)</u><u style="single"> The step of compressing the first portion of the substantially liquefied nitrogen,</u><u style="single"> The step of heating the first portion of the substantially liquefied nitrogen,</u><u style="single"> The step of directing the heated and compressed nitrogen to the steam cycle of the power plant to increase the output of the power plant,</u><u style="single"> The step of preserving the second portion of the nitrogen, which is substantially liquefied,</u><u style="single"> The step of evaporating the second portion of the substantially liquefied nitrogen,</u><u style="single"> With the step of increasing the output of the power plant by pointing the second portion of the substantially liquefied nitrogen through a high temperature gas expander.</u><u style="single">26. The method of item 26, further comprising.</u></p>

<figref num="1">FIG. 1 is a process diagram of an embodiment of a carbon capture and isolation system according to the present invention.</figref><figref num="2">FIG. 2 is a process diagram of an embodiment of a solvent regeneration assembly according to the present invention.</figref><figref num="3">FIG. 3 is a process diagram of an embodiment of a carbon capture and isolation system according to the invention integrated with a power plant.</figref><figref num="4">FIG. 4 is a process diagram of an embodiment of a nitrogen liquefaction assembly according to the present invention.</figref>

(Detailed explanation) In the following paragraphs, embodiments of the present invention are described in detail as examples with reference to the accompanying drawings which are not drawn to scale and the components described are not necessarily drawn in proportion to each other. To do. Throughout this description, the embodiments and examples presented should be considered as an example rather than as a limitation for the present invention. As used herein, "invention" refers to any one and any equivalent of any embodiment of the invention described herein. Moreover, reference to various aspects of the invention throughout this document does not imply that all claimed embodiments or methods must include the mentioned aspects. References to temperature, pressure, density and other parameters should be considered as representatives and examples of the capabilities of embodiments of the invention, and embodiments can be manipulated by a wide variety of such parameters. It should be noted that the figure does not show the pressure, temperature and flow velocity of all equipment or different flows.

The examples of gas, liquid, and solid products produced by the various embodiments of the invention are not intended to be comprehensive. Some trace products of embodiments of the invention, including those that occur temporarily and then disappear, are understood to be within the scope of the invention, although not discussed in detail below. All aspects of heat generation are not mentioned below, but all valuable heat generated in embodiments of the present invention has potential and potential applications for heat recovery and is required by the process as a whole. It is understood to reduce the energy input of.

FIG. 1 shows two major subsystems of an embodiment of the invention, a carbon capture assembly 100 and a solvent regeneration assembly 200. The carbon capture assembly 100 includes a reaction vessel 101 and a mixing vessel 102, preferably a solvent condensing device 103. The solvent regeneration assembly 200 is described in detail herein in connection with FIG. The system shown can be used with any power plant and any type of exhaust gas and is particularly suitable for capturing and isolating carbon dioxide from combustion emissions from coal-fired power plants. Combustion exhaust gas from engines at LFG work sites produces exhaust gas close to 900 ° F. Most such engine drive systems do not have a heat recovery attachment, but the low heat content of their combustion emissions is an important energy source for embodiments of this system and method.

The carbon capture and isolation chemical process is such that there is a reaction that results in the formation of carbonate 6, water-methanol solution 10 and heat to precipitate.₂+ Includes contacting water and some temporarily formed (small amount) of carbonate 14 with alkali 2 suspended in methoxide 5. First, CO₂Combustion flue gas 1 and water 4 containing methoxide are introduced into methoxide 5, and both streams enter the reaction vessel 101 separately and simultaneously. By entering them separately, it is possible to have complete control over the flow velocities of both streams, allowing the water stream 4 to be adjusted for any small amount of water vapor contained in the flue gas. Become. The reaction vessel 101 receives a methoxide suspension 5 composed of an alkali 2 and a substantially non-aqueous solvent 12 from the mixing vessel 102 through a first inlet 113, which is preferably an inlet valve. The reaction vessel 101 receives the combustion exhaust gas 1 through the second inlet 111 and the water through the third inlet 112, both of which are preferably inlet valves. The CO₂+ The reaction between water (and a small amount of temporary carbonic acid 14) and the alkali 2 contained in the methoxide 5 occurs rapidly (sometimes in less than 1 second) and the CO of the gas.₂Is completely converted to solid carbonate and by-products water and heat.

In a preferred embodiment, the carbonate 6 precipitates from the solution and mechanically from the reaction vessel 101 using any other device or system suitable for mechanically removing the auger 104 or carbonate precipitate. Remove. In some embodiments, up to about 10% volume of water-methanol solution 10 remaining in the reaction vessel 101 is a suspension that does not settle to the bottom of the reaction vessel but does settle out of the solution during the methanol regeneration process. Contains carbonated carbonate. Water derived from the acid + base reaction forms a solution with the solvent. The water-solvent solution 10 is removed by a filter 114, which prevents larger solids from leaving the reaction vessel, which settles to the bottom of the vessel, where they are mechanically removed. The method further comprises removing the water-solvent solution 10 from the reaction vessel 101 and separating the water from the solvent. In those embodiments in which the carbonate is carried in the water-solvent solution 10, the carbonate precipitates with the water. The water-methanol solution 10 is drawn near the top of the reaction vessel 101 at a warm temperature that reflects the optimum temperature for the reaction, which minimizes the time required for the reaction.

As a preliminary step, the alkali 2 is mixed with the solvent 12 in the mixing tank 102 to form the suspension 5. Any number of alkalis known in the art can be used in CO₂Can be selected to neutralize and produce their respective carbonates. The alkali can be a strong base or a weak base, a normal base such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) in powder form, or magnesium hydride, potassium hydride or hydride is sodium ( Hydroxide such as MgH, KH, NaH), or anhydrous ammonia, or calcium oxide (CaO), or calcium oxide (CaO) found in fly ash (and bottom ash), another by-product of coal-fired or biomass power plants and boilers. CO₂Any other natural or synthetic suitable alkali that reacts with can be mentioned.

One advantage of embodiments of the present invention is that they can be used to perform carbon capture and sequestration on a large industrial scale. By adopting the systems and methods described herein in facilities of all sizes, it is possible to use multiple alkalis to result in their respective carbonates. Each alkali and its chemical symbol and CO that follow₂Here is a descriptive list of the carbonates produced when reacting with and the chemical symbols of each carbonate: Ammonia (anhydrous), NH₃ Ammonium carbonate, (NH₄)₂CO₃ Lithium hydride, LiH Lithium carbonate, Li₂CO₃ Lithium hydroxide, LiOH Lithium carbonate Li₂CO₃ Magnesium hydride, MgH₂ Magnesium carbonate, MgCO₃ Magnesium hydroxide, Mg (OH)₂ Magnesium carbonate, MgCO₃ Potassium hydride, KH Potassium carbonate, K₂CO₃ Potassium hydroxide, KOH Potassium carbonate, K₂CO₃ Sodium hydride, NaH Sodium carbonate, Na₂CO₃ Sodium hydroxide, NaOH Sodium carbonate, Na₂CO₃ One embodiment uses potassium hydride (KH), optionally in combination with other alkalis. MgH₂And ashes, CO₂It can be used in combination with the KH to increase the capture rate. Hydride of potassium, sodium and magnesium (KH, NaH and MgH, respectively) are their hydroxide equivalents (KOH, NaOH, Mg (OH)).₂) It is cheaper and produces more carbonates per hydride unit than those hydrides, making those hydrides more economical. Such a combination of alkalis requires multiple mixing tanks and multiple reaction tanks. Some hydrogen can also be produced as a by-product of the use of certain hydrides. For example, for every two pounds of hydride dissolved in methanol, NaH produces about 930 L of hydrogen and KH produces about 560 L of hydrogen. Such H₂The stream is not released and is used as fuel in one of several possible locations in the embodiments of the present invention. For example, that H₂The flow can be sent directly to the combustion chamber of the power plant, or it is used to increase power N₂It can be burned in an auxiliary heater that provides additional heat to the flow. The choice of the alkali and the carbonates obtained depends on the market for those carbonates and the relative cost of the alkali when compared to the value of the carbonate.

A preferred embodiment uses fine powders that are recovered from the flue gas in the alkali, coal-fired and biomass power plants or coal-fired and biomass boilers present in fly ash before releasing the flue gas into the atmosphere. Similarly, bottom ash from coal or biomass debris that does not move up the flue is a product that has been sought for use but remains a significant waste stream. The following discussion of ash includes both fly ash and bottom ash with similar chemical composition and all alkaline ash from any source.

Much of the ash produced by coal-fired power plants has no use. Most of them are taken to landfills for disposal or directed to other low-value applications. Ash from lignite, a widely used type of coal, has 15-45% SiO, along with up to 5% unburned carbon.₂(Sand), 20-25% AlO₃(Aluminum oxide), 4-15% Fe₂O₃Contains (iron oxide) and 15-40% CaO (calcium oxide). Subbituminous coal produces fly ash with a lower percentage of CaO (5-30%) that can also be used as an alkaline source, but requires more ash to achieve the same result. Removal of the iron oxide by magnetic means, preferably when the ash is suspended in methanol, helps to concentrate the amount of CaO in the methoxide and is another beneficial by-product (iron oxide). ), And the removal of relatively heavy iron reduces the weight and transportation costs of the final carbonate-containing solid-state logistics. CaO contained in fly ash is the same alkali that is commonly available as lime, but in this context it is a by-product of burning coal containing calcium carbonate. Therefore, the CaO is an additional CO that exceeds what the power plant normally emits.₂Obtained from non-emission ash. On the contrary, purchasing the manufactured CaO is because the production of CaO is a large amount of CO.₂Will result in the release of carbon, which will increase the carbon footprint of this process.

One embodiment of the carbon capture and isolation method is ash and CO in methanol 12.₂The contained combustion exhaust gas 1 is hosted to significantly limit the amount of water in the reaction vessel 101. This allows the reaction to produce a drier and more controllable final product (in terms of size and arrangement). In this preferred embodiment, the final product yields a suitable agricultural lime substitute while minimizing the amount of input energy required by the process with little or no post-dryer grinding. , Uniform size granules.

The glassy ash benefits from a rapid cooling process that crushes microscopic ash particles, thus delivering the alkali in the ash and the CO delivered by flows 1 and 4 to the reaction vessel.₂And can promote the reaction with water. The rapid cooling preferably first warms the ash and then rapidly cools it in thoroughly chilled methanol, thus producing each microscopic ash glass-like bead. Including crushing. If the reaction occurs in warm methanol (as is possible), quench the ash flow in one tank, followed by warming the methanol + ash solution in another reaction tank. Can be mixed with methanol. The heat required to warm the ash prior to rapid cooling can be delivered from one of the many heat recovery points in this process.

The acid + base reaction occurs in a host solution containing the alkali or base in the solution, and CO₂And its base and CO formed when water is introduced into a solvent containing alkali₂It is preferable to allow easy contact with + water (+ a small amount of temporary carbonic acid). Therefore, a preferred embodiment uses a substantially non-aqueous solvent to host the reaction. This draws the water-methanol solution 10 from the top of the reaction vessel 101 at the same rate as the reaction produces water, and the water-methanol solution 10 is equal volume concentrated (ie, substantially water). Achieved by replacing with methoxide 5 (not included). The amount of water flowing into the reaction vessel depends on the water content of the combustion exhaust gas and the amount of water that may remain in the methanol in a solution state before the inflow of the combustion exhaust gas.

In addition, water, which is the product of the acid + base reaction, needs to be withdrawn from the reaction vessel 101 at a sufficient speed in order to prevent methoxide 5 from being hydrolyzed. The almost dry combustion exhaust gas 1 is whipped through methoxide 5 together with an appropriate amount of water (flow 4), and its CO₂Reacts with the alkali, allowing a small amount of carbonic acid 14 to be temporarily formed, as well as reacting with the alkali 2 retained in solution 5 by the solvent 12. The flue gas 1 enters the reaction vessel 101 at sufficient pressure, eg, about 16.5 psia, so that the flue gas 1 rises through the host methoxide 5 and the unreacted portion of the flue gas (1). Almost N₂), But most are N₂And preferably it is possible to leave the reaction vessel 101 as an evaporated methanol stream 8 recovered by condensation in the solvent condensing apparatus 103. Due to the pressure drop along the pre-cooling path of the flue gas, the present invention seeks to receive the flue gas at about 17 psia.

In a preferred embodiment, the non-aqueous solvent is an alcohol, most preferably methanol. However, any suitable non-aqueous solvent can be used that allows some sufficient amount of alkali to dissolve in it and also precipitates any salt produced in a standard acid + base reaction. Ethanol is, for example, the CO produced by the process at an ethanol plant.₂It is a somewhat expensive alternative that can be selected when used to capture and quarantine. In that sense, the ethanol can be used at a wholesale price, and supplemental ethanol does not need to be shipped. The purpose of the solvent is to cause the acid + base reaction in a substantially dry liquid, thus avoiding the formation of carbonates suspended in salt water or water and a high percentage that must be driven away. To avoid the final product containing water.

The alkali 2 mixes with the methanol solvent 12 to form a solution of methoxide 5, methanol and any suitable hydride or hydroxide base, where the base is suspended. The following is an example of a common chemical equation for mixing alkali (KH, or potassium hydride) with methanol: 2KH + MeOH 2MeOK + H₂.. This methoxide can be cooled to recover and counteract the heat of the reaction that occurs when some alkali is introduced into methanol. The choice of how cold the methoxide should be depends on which alkali is selected and which carbonate is the final product of the reaction and therefore controls the temperature of the reaction vessel 101. , According to the method selected to reduce the evaporation loss of methanol from the reaction vessel.

By mixing the alkali 2 with methanol 12 at ambient temperature in the mixing tank 102, the two compounds interact to generate heat and the ionicity of methoxide 5, which may contain a solvated metal hydroxide. Produce a solution. The heat of reaction in the resulting solution, generally in the range of about 225 ° F to about 300 ° F, can be recovered and used to warm the rest of the process. Of note, some dimethyl carbonate (DMC) also occurs in the mixing tank 102 but then decomposes. After heat recovery, the methoxide 5 is sent to the reaction vessel 101 to host the flow of incoming water 4 and the almost dry flue gas 1 that foams through the methoxide 5. The methoxide 5 flows into the reaction vessel 101, and the water-methanol solution 10 flows out from the reaction vessel 101 to the low temperature drying chamber 202 (via the first heat exchanger 201) and to the high temperature distillation column 205. First, the flow velocity of the combustion exhaust gas 1 and the CO of the combustion exhaust gas₂Depends on the content. Second, its flow rate is tightly controlled so that the methoxide medium with the higher water content never allows more than about 10% water in its reaction vessel so that the carbonate does not easily precipitate. Will be done.

Methoxide 5 enters the reaction vessel 101 into which the combustion exhaust gas flow 1 and water 4 are introduced. Depending on the embodiment, a plurality of continuous reaction tanks that enable a constant flow of combustion exhaust gas can be used. The preferred reaction vessel has a height of about 40 feet and is made of stainless steel or properly coated carbon steel, or any other that can withstand acids, bases, water and heat without corrosion. Can be made from material. The reaction vessel 101 is fluidly connected to the mixing vessel 102 so that the alkali-solvent suspension, here methoxide, enters the reaction vessel by the first charge. As discussed in more detail herein, the flue gas stream 1 reaches the reactor 101 by a second charge in which some of its heat content has been released in the hot distillation step associated with the regeneration of the methanol. .. The chemical process in the reaction vessel can be summarized by the following equation: (1) CO₂^gas CO₂^solution+ HO^- HCO₃^- H₂CO₃Or CO₃^2- The first step in (1) above is the physical dissolution of carbon dioxide gas in a substantially non-aqueous solvent. This dissolution is reversible as indicated by the double-headed arrow. The second step in (1) is in the free form (carbonic acid, H) with water or a base that forms a small amount of carbonate.₂CO₃) And CO in bicarbonate₂Is the capture of. Ion formation depends on the alkalinity of the solution. The reaction is quick and almost instantaneous. The carbonate ion is removed from the tank as a metal salt (eg, calcium carbonate or potassium carbonate) that precipitates at the bottom, thus allowing the reaction to continue. The alkalinity of the solution and the solubility of the metal carbonate in the solvent determine the rate of formation and precipitation of the carbonate. Therefore, the actual operation of the reaction is optimized by controlling the temperature, pressure and flow rate of the various streams associated with the alkalinity of the solvent and the solubility of the selected carbonate product.

Preferably, the water produced from the acid-base reaction should not exceed about 10% by volume of the amount of methanol in the reaction vessel. Water control is achieved by constantly removing the water-solvent solution 10 from the reaction vessel and replacing it with pure regenerated methanol. This solvent regeneration process will be discussed in detail below.

The reaction of alkali 2 with carbonate 14 produces a carbonate 6 that precipitates at the bottom of the reaction vessel 101, where it can mechanically remove the auger 104 or the precipitated carbonate or any other device or Removed by the system. If KH is used as its alkali, some portion of carbonate 6 will probably remain in solution in methanol, remain with water-methanol solution 10, and settle during subsequent cold drying. Become. The removed material can be dried by heat recovered from elsewhere in the process, producing fine powders or pellets. The carbonate 6 that settles at the bottom of the reaction vessel 101 can carry a small amount of methanol with it, but preferably does not carry water. The reaction causes the water-methanol solution product 10 to rise in the reaction vessel 101, while the precipitated carbonate 6 precipitates towards the bottom.

Therefore, the reaction vessel design makes good use of rising liquids and flue gas and settling carbonates. For example, methoxide 5 and cold flue gas 1 enter near the bottom of reaction vessel 101, while warmer water-methanol solution 10 is near the top, shown in FIG. 3 and in more detail in FIG. Inert gas (N) to proceed to further process steps in nitrogen liquefaction assembly 300₂, And in some cases O₂) Is pulled out. Any methanol (in the form of water-methanol solution 10) that leaves the reaction vessel 101 with carbonate may be evaporated. The dry carbonate is sent to the end user for use as a substitute for lime in fertilizers, mine landfills, road landfills, or other industrial applications. A significant proportion of the acid oxides of nitrogen contained in the stream of combustion emissions react with the alkalis in the methoxide to produce a variety of nitrogen-containing salts, including but not limited to nitrides. Occurs, thus reducing emissions from the power plant.

The carbonate 6 resulting from the reaction of carbonate 14 with alkali 2 depends on the alkali selected. One possibility is calcium carbonate, which can be used in agricultural fertilizers or as a substitute for lime in steelmaking, oil drilling, diapers, and glassmaking. Another potential product is magnesium carbonate, which can be used as a fertilizer as a substitute for dolomite limestone, allowing avoidance of calcification and the CO released during lime formation.₂By reducing CO₂Brings the avoidance of release. Potassium carbonate is another potential product that can be used as a fertilizer and also avoids calcification. Another possible final product of the embodiments of the present invention is silicon nitride (Si) if the metal is baked in pure nitrogen.₃N₄), Calcium nitride (Ca₃N₂), Or magnesium nitride (Mg)₃N₂) Can be mentioned. Separation of argon (as liquid argon) from the liquid nitrogen product stream has an argon content of nearly 1% in the flue gas, and a cold distillation column LN.₂When included in the production loop, it is particularly attractive because it produces a high value liquid argon stream.

CO removed from the combustion exhaust gas 1 and chemically converted to carbonate 6₂Therefore, the residual portion of the combustion exhaust gas is mostly nitrogen. The stream 8 containing nitrogen and some methanol leaves the top of the reaction vessel 101. The hotter the reaction, the more evaporated methanol N₂Will leave with gas. At reaction temperatures above 150 ° F, excess methanol will cause the tank to N.₂Will cause you to leave with. Therefore, the heat of reaction needs to be controlled. For example, the methoxide stream 5 at the inlet to the reaction vessel 101 can be pre-cooled. Alternatively, the reaction vessel 101 is provided with, for example, a cold N by a heat exchanger suspended near the top of the vessel.₂Cool internally using stream 9, cool the liquid in the reaction vessel to maintain its methanol content in a condensed (liquid) state, and residual N₂The gas can be advanced towards the nitrogen liquefaction assembly 300 for liquefaction. Preferably, the reaction allows some methanol to evaporate, leaving it to reach close to 150 ° F, but the methanol is recovered in the solvent condensing apparatus 103 immediately after it leaves the reaction vessel 101.

Methods of controlling the temperature in the reaction vessel include cooling the flow of the inlet (methoxide, water, etc.) and / or cooling the liquid in the reaction vessel with an internal heat exchanger and / or them. The combination of technologies can be mentioned. Those options are not shown in Figure 1. Anyone familiar with the technology of such thermal control systems will choose the best method. To what extent the reaction vessel needs to be below 150 ° F is determined by thermodynamic calculations to optimize the rate of the reaction without causing excess methanol to evaporate from the reaction vessel. It is determined.

Most of the flow leaving the solvent condensing device 103 is N₂Although there are 7 combustion emissions, it is also argon, and a small amount of O, depending on the source of the combustion emissions.₂May include. Trace amount of water or CO₂(One millionth unit) is N as described below₂Removed with molecular sieves 305 (shown in FIG. 4) prior to liquefaction of stream 7. Most of the N₂Is cost-effectively compressed and cooled, and thus liquefied by a technically known process to achieve relatively high purity liquid nitrogen (LN).₂) Can be produced at a much lower cost than can be manufactured with a standard air separation device. This process can be performed by the nitrogen liquefaction assembly 300 shown in FIGS. 3 and 4.

Next, looking at FIG. 2, the solvent regeneration assembly 200 is shown in more detail. The solvent regeneration assembly 200 is fluid-connected to the reaction vessel 101 and is fluid-connected to the first heat exchanger 201, the low-temperature drying chamber 202 fluid-connected to the first heat exchanger, and the first heat exchanger. Includes a hot distillation tank 205. Additional heat exchangers can be used and are described below. The water-methanol solution 10 is pumped to a first heat exchanger 201, where it is pumped to a high pressure, eg, about 800 psia, or any other pressure suitable for the power-enhancing properties described below (low temperature). Pump, liquid N (not shown)₂Using 9, cool thoroughly by heat exchange. The thoroughly chilled water-methanol solution 10 is then sent to the cold drying tank 202, where the freshly frozen water ("semi-melted" water containing a small amount of methanol) it contains is the cold drying tank. It falls to the bottom of 202, most of which allows the water stream 11 to be removed from the bottom 212 of the cold drying tank 202, leaving most of the methanol flow to be removed from the top 211 of the tank. When KH is used as an alkali, some carbonate will come out in its low temperature drying tank 202.

In some embodiments, the water-methanol stream 10 has a carbonate in solution with methanol. The solids settle towards the bottom 212 of the cold drying tank 202 and are removed from the bottom of the tank by mechanical means, and the water-methanol stream 11 is removed from a higher point in the tank 212, mostly as water. Will be done. Neither flow 11 nor 12 carries any solid with them as they go through the cycle.

The mostly water stream 11 then moves to a second heat exchanger 203, which is preferably an ambient air heat exchanger for warming. Other heat sources include flows that carry various heats, such as the flow 7 after leaving the solvent condensing device 103 in FIG. The choice is N₂Helps to pre-cool the stream before it arrives at the nitrogen liquefaction assembly 300 for liquefaction. Most of the water flow 11 goes from the second heat exchanger 203 to the third heat exchanger 204, where it is further warmed by the methanol steam 3 coming out of the hot distillation tank 205. For clarity, the third heat exchanger 204 is shown directly between the second heat exchanger 203 and the distillation column 205. A well-designed form of this process is probably that a third heat exchanger 204 is placed on the distillation column 205 and the reflux solvent flow moving through the control valve 207 falls into the column by gravity. Will be possible. Alternatively, a small pump moves the reflux flow from 204 to 205.

The methanol vapor 3 used in the third heat exchanger 204 is preferably about 150 ° F. and higher, and is substantially pure methanol vapor. Water is recovered from the hot distillation tank 205, as well as N₂When the flow leaves the first heat exchanger 201 during its power boosting function at the power plant 400, i.e. the power cycle that first produces the flue gas and powers the nitrogen liquefaction assembly 300. Can be used to warm up. The methanol stream 3, which is now a gas, is mostly condensed into a liquid by the stream 11 of water, allowing the recovered methanol 12 to be sent back to the mixing tank 102 for further methoxide production. The resulting methoxide suspension may contain some water.

Stream 12 (having a very low water content) is removed as dry methanol from the top of the cold drying tank 202 and returned via a first heat exchanger 201 (recovering its coldness) and then a second. The return reflux exiting the heat exchanger 204 of 3 and most of the integration sent back to the mixing tank 102 participates in the return reflux containing the methanol flow 12. The reducing stream flow 12 (mostly dry methanol) travels through the first heat exchanger 201 and is liquid N.₂Helps cool the water-methanol stream 10 from the reactor 101.

Most of the water stream 11 leaving the low temperature drying tank 202 and heated in the second heat exchanger 203 and the third heat exchanger 204 is heated in the high temperature distillation tank 205 to produce its limited content of methanol vapor. Drive away and allow pure water to move away from the bottom of its hot distillation tank 205. The heat source for this distillation is the hot combustion exhaust gas 41 moving through the reboiler 206 at the bottom of the hot distillation tank 205. The hot flue gas yields much of its heat at this stage, but still has sufficient residual heat that can be recovered for use elsewhere. Most of the recovered water 4 leaving the high temperature distillation tank 205 is CO in the combustion exhaust gas, as shown in FIG.₂Is sent back to the reaction vessel 101 so that carbonic acid 14 can be formed. The excess water that may be produced can be sent through one or more layers of activated carbon filtration after it has left the hot distillation tank 205 to make the water suitable for drinking. Alternatively, excess recovered water can be sent to the steam cycle of the power plant as a source of make-up water to replace the water lost in that steam cycle. The flue gas from the natural gas-fired power plant has a higher water content and is returned to the reaction tank 101 for CO in the flue gas.₂The amount of water 4 recovered from the high temperature distillation tank 205 required to form carbonic acid is small.

The low pressure methanol vapor 3 separates from the top of the distillation column 205 (also known as the distillation column). The heat of the steam is used to preheat the cold (mostly water) stream 11 sent to the hot distillation tank 205. The heat exchange causes the methanol vapor 3 to condense. A portion of the condensed methanol stream is sent back to the top of the hot distillation tank 205 as a kind of reflux stream, which helps to evaporate most of the methanol in the water mixture below. Preferably, the portion of the condensed methanol stream sent back to the top of the hot distillation tank 205 is about 10% of that stream. Valve 207 is shown on the reflux line in front of the inlet of the flow to its tank.

Liquid N₂The stream 9 travels through the first heat exchanger 201, thoroughly cooling the water-methanol stream 10 (between about -50 ° F and -80 ° F). That liquid N₂The flow velocity through the first heat exchanger 201 of 9 is the evaporated liquid N₂(Now N₂) Outlet temperature is controlled. In a preferred embodiment, the evaporated N₂Leaves reaction tank 101 mostly N₂It serves well as a coolant in the solvent condensing device 103 that condenses the methanol contained in the stream (as seen in FIG. 1). N of its side loops that helped condense methanol in the outflow 8 from reaction vessel 101₂Is a high pressure N leaving the first heat exchanger 201₂It rejoins the stream and is transferred to act as an output boost in the basic generation cycle. Solvent condensing device 103 leaves warm reaction vessel 101 N₂+ Recover the heat content of the methanol stream 8 and transfer that heat to the cold N leaving the first heat exchanger 201₂Moved to sidestream 9 and it was N on the way to the power cycle₂Join the mainstream 7 again. This allows the acid + base reaction in the tank to occur under the hottest conditions, leaving N away from the heat exchanger 201.₂N shown to rejoin the mainstream₂Generates significant low heat transferred to stream 7. Its N moving from 201 to subsystem 400₂Flow warming leaves solvent cooling device 103 N₂Achieved by cooling in the middle of its liquefaction in stream 7 subsystem 300.

Of note, the distillation of the water-methanol solution 10 removed from the reaction vessel 101 is by heat (eg, from the thermal content of the combustion exhaust gas) or by incomplete vacuum removing the methanol vapor from the hot distillation vessel 205. It can occur in a variety of ways, including by increased heat or by steam recompression. However, all of these methods require more heat than can be obtained in the flue gas. The invention instead "" wet methanol stream so that denser water moves to the bottom of the vessel and the saturated methanol stream is further distilled by any one or combination of the above methods. "Pre-distill" and thoroughly cool the water-methanol solution 10.

The preferred embodiment shown in FIG. 2 is a liquid N to accomplish the distillation (regeneration) of the water-methanol solution 10.₂It relies on the off-peak power stored in the form of. The cryogenic distillation step produces a stream of water, mostly of which residual methanol is distilled by heat. A preferred two-step (low temperature and high temperature) regeneration process is when the proportion of water is very high compared to the proportion of methanol, such as when reaching the almost water stream 11 sent to the hot distillation tank 205. Very little heat is required to distill the water-methanol solution 10. The net energy required to regenerate the methanol, if cooling is included in the embodiments of the present invention, is due to its wider temperature range (temperature between the hot and cold sides), which results in a significant amount of heat and cooling recovery. Because of the effect of, it will be less. In addition, liquid N₂Manufacture results in quite a lot of low cost cooling. It should be noted that FIG. 2 does not show all possible heat recovery steps that can optimize the efficiency of the process, only one control valve. Other valves, gauges, sensors, equipment and pumps are not shown.

Figure 3 shows an embodiment of a system that integrates several subsystems, including carbon capture and isolation processes and flows inflowing into and out of the power plant, as well as flows between the subsystems. These include carbon capture assembly 100, solvent regeneration assembly 200, nitrogen liquefaction assembly 300 and power generation assembly 400. This last part is a coal combustion and biomass steam cycle, a natural gas fuel composite cycle, a landfill gas combustion or anaerobic digester combustion plant, and any other hydrocarbon fueled CO.₂The emission power generation system can be mentioned.

LN₂Most of the generation is N₂It occurs in the nitrogen liquefaction assembly 300 using the supply gas of. In one example, LN in a 500 MW coal-fueled thermal power plant₂The flow of production is about 30,000 tons per day. Its 30,000 tonnes per day contains about 0.9% argon, which is also beneficial, which is LN₂Used to generate income by being separated from. In a preferred embodiment, the LN₂Is divided into three parts. The first part is as a product of high value to end users away from the field, as a product used for cooling applications and to move such resources to the well side (and above) in oil and gas fields. Will be sold.

The second part is used to regenerate methanol by low temperature drying as shown in FIG. That same N₂However, after it is vaporized by heat exchange, it is sent as a high-pressure stream during the steam cycle of the power plant to increase the mass flow through the steam turbine or send it to another hot gas expander equipped with a generator. Increases power by roughly 6.5% without the use of additional fuel. High pressure N₂First of all, the flow is the LN₂Is obtained by pumping the heat, the heat of which is shown in FIG. 2 and is absorbed in its high pressure stream by the various heat recovery steps described herein.

High pressure N₂The heat sources provided by the embodiments of the present invention for warming the gas include: warm water-solvent solution 10, which leaves the reaction vessel 101 during regeneration, as shown in FIG. 1, in which case heat. Replacement is N in heat exchanger 201₂Occurs between stream 9 and water-solvent solution stream 10; warm N leaving reactor 101, shown in Figure 1.₂, In that case N₂Stream 9 contains methanol in the solvent condensing apparatus 103.₂Warmed by stream 8; heat remaining in combustion effluent 1 after it has provided some of its heat in hot distillation column 205; heat contained in water 4 recovered from hot distillation column 205; mixing Heat generated by the ionic reaction between alkali 2 and methanol 12 selected during the production of methoxyd 5 in tank 102; cold N₂Steam condensation in a power cycle, usually done in a cooling tower, replaced by a stream; and in a natural gas combustion combined cycle power plant, cold N as the cooling stream to cool the outside air to the gas turbine.₂The heat absorbed by using is mentioned.

Everyday LN₂The third part of the production is stored in one or more cold storage tanks 307 and released to further enhance the power generation cycle during peak hours of electricity demand. The release of that stored energy is first preferably the LN using a cryogenic pump.₂Pumped it, then evaporates it with waste heat from elsewhere in the process, then its high pressure, high temperature N₂The stream is sent through a hot gas expander equipped with a generator. That output increases the peak hour output by another about 5% combined with the 6.5% output increase that occurs at other times of the day, and during the peak power generation time when that output is most valuable, It produces a total output increase of about 11%. LN used for its power enhancement embodiment₂Is preferably manufactured using off-peak power at night, and its storage for later power release constitutes a practical scale power storage mode without a battery, flywheel or compressed air rock cavity storage system.

This storage and release mode, in which electricity demand flows out during peak hours, is CO.₂It constitutes a power storage strategy that converts low-cost liquid nitrogen produced as a by-product of the capture process and converts the recovered nitrogen flow into high-value peak power. A hot gas expander equipped with a generator that converts hot pressurized nitrogen gas into electricity can be the same expander that converts the first portion of warmed nitrogen in the methanol regeneration process.

Nitrogen stream 7 is the first air used to burn the fuel used in power plant 400 (the air used to burn that fuel is O).₂Is already separated from) and is contained in the flue gas from the combustion of that fuel in the air.₂It is also separated from. Trace amounts of water and CO remaining in nitrogen stream 8 leaving reactor 101₂Can be removed preferably with molecular sieves 305 containing zeolite. That N₂Stream water and CO₂The content is substantially lower than that of ambient air and requires a small molar number of sieve absorbers, or one that is regenerated infrequently.

Reference to FIG. 4 shows the nitrogen liquefaction assembly 300 in more detail. Figure 4 shows N leaving carbon capture assembly 100 in cold heat exchanger 306.₂Another N as a refrigerant to cool the flow₂N using a loop₂Shows liquefaction. N₂The stream 7 is first compressed to a medium pressure, eg, about 80 pisa, in several steps, as shown by the multi-stage compressor 302 driven by a motor 301 connected by a drive shaft 309. Compressed N after heat recovery in one or more intermediate and rear coolers 303₂Moves through molecular sieves 305. Figure 4 shows several locations where the heat of compression is recovered in the heat exchangers (intermediate and rear coolers) and used to supply heat to the rest of the carbon capture and isolation process. There is. Compressed N₂The stream is sent to the cold heat exchanger 306, where it is N of the refrigerant shown as 9.₂It is cooled to about -280 ° F by heat exchange with the flow. Its cooling causes the flow to form an almost liquid phase, which is preferably sent to a cold liquid storage tank through a pressure reduction / control valve 207 between the cold heat exchanger 306 and the storage device 307, where it is obtained. LN₂Is stored.

The pressure reduction through valve 204 is more than 90% thoroughly chilled N, with less than 10% flowing vigorously as a dense, cold (about -280 ° F) gas 35.₂Allows 9 to enter the storage tank as a liquid. The gas part (flash gas) is left in the storage tank as it is, and the N at the entrance₂It is used as a small part of the cooling source in this heat exchanger that cools the flow. After giving that cold to the inlet stream, the flush stream 35 is further warmed by heat exchange with other streams (not shown in Figure 4), and the water and CO trapped in the sieve.₂Is sent to the molecular sieve 305 as sweep gas to remove the gas, and then discharged into the atmosphere through the discharge port 308. The outlet flow is of good quality. Because it contains almost N₂(Main component of air), water and CO₂Is a small amount.

N₂The main cooling loop that liquefies the stream is dry as a refrigerant N₂(Or dry air, or any other suitable fluid) is also used, but its refrigerant flow should be liquefied.₂Do not mix with the stream. Its independent cooling loop consists of several stages of compression and several stages of expansion (all on a single axis 309 or on two or more separate axes), with the electric motor 301 The 302, and the expansion stage 304, are driven to serve to provide cooling as described below. The single-axis construction shown for the various stages of compressors and expanders is just one example of such a low temperature cooling system. Other layouts with variations on multiple axes as well as compression and extension position may be designed by one of ordinary skill in the art.

The compression stage is low temperature heat exchanger 306 (N₂To take the low pressure "warmed" refrigerant away from (thoroughly cooled the inlet flow) and use it elsewhere, the flow of the refrigerant is used in several stages of compression in the middle and rear coolers 303. The heat of compression recovered inside brings it to a high pressure (for example, about 800 pisa). The high pressure refrigerant close to its ambient temperature is then expanded in the multistage expander 304. Their expansion cools the refrigerant to about -300 ° F, but reduces its pressure to about 80 pisa. The refrigerant at about -300 ° F is N at about 50 ° F in the heat exchanger 306.₂Cool the flow to about -280 ° F. Sequentially, the incoming N₂Stream 7 requires that the refrigerant be warmed to about 40 ° F and it is in a continuous loop, recompressed and cooled by expansion, as described above. The cycle described here can have variations other than the possible variations mentioned above. For example, N at the entrance₂Is compressed to higher pressure at various stages and the LN₂It can produce different proportions of flowing liquid that enter the storage tank and produce different amounts of retrievable heat of compression. Absorption chillers with waste heat from compression and other waste heat sources from embodiments of the present invention are N₂Pre-cooling of the stream can be provided.

Similar power enhancements are possible at natural gas-fired combined cycle power plants, with the following differences. That is, it is the N₂Flow is CO with less natural gas-fired power plants₂The combustion exhaust gas flow is CO to generate₂Greater proportion to the flow, and cold N₂Can be sent first to cool the air at the inlet of the gas turbine, then its N₂However, when warmed up, it is possible to obtain more heat from the waste heat source in the embodiments of the present invention and then send it to the steam portion of the composite cycle.

This liquefaction cycle is N₂It requires a power input to the motor 301 in the flow compressor and refrigerant flow compressor, as well as a small amount of power input to various pumps, equipment and valves. However, that power requirement is substantially offset by the power enhancements described herein, and more than that, the sale and recovery of carbonates, liquid nitrogen and liquid argon H.₂, And possible recovery of iron oxide from ash and separated from combustion emissions N₂Compensated by the overall value of any other by-product that can be produced from the stream. In some embodiments, the LN₂Liquefaction should be done only during off-peak power demand hours and sufficient LN for use in methanol regeneration and power enhancement sequences with low value power.₂, As well as an additional LN for off-site sales₂It is appropriate to manufacture. If a cold distillation column is included (not shown in Figure 4), liquid argon is added to its LN.₂Can be removed from, creating another revenue stream.

In this way, it can be seen that carbon capture and sequestration systems and methods are provided. Of course, any of the aforementioned structures and special components or compounds can be used interchangeably with any system of the preceding embodiments. Preferred embodiments have been described above that are useful in describing the invention, but it will be apparent to those skilled in the art that various modifications and modifications can be made to it without departing from the scope of the invention. The appended claims are intended to cover all those modifications and modifications contained within the true spirit and scope of the invention.