OA18406A - Carbon dioxide sequestration with magnesium hydroxide and regeneration of magnesium hydroxide. - Google Patents
Carbon dioxide sequestration with magnesium hydroxide and regeneration of magnesium hydroxide. Download PDFInfo
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- OA18406A OA18406A OA1201700343 OA18406A OA 18406 A OA18406 A OA 18406A OA 1201700343 OA1201700343 OA 1201700343 OA 18406 A OA18406 A OA 18406A
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- 229910001862 magnesium hydroxide Inorganic materials 0.000 title claims abstract description 40
- VTHJTEIRLNZDEV-UHFFFAOYSA-L Magnesium hydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 title claims abstract description 35
- CURLTUGMZLYLDI-UHFFFAOYSA-N carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 239000000347 magnesium hydroxide Substances 0.000 title claims abstract description 35
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 34
- 239000001569 carbon dioxide Substances 0.000 title abstract description 6
- 230000008929 regeneration Effects 0.000 title 1
- 238000011069 regeneration method Methods 0.000 title 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxyl anion Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims abstract description 11
- 230000001172 regenerating Effects 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 57
- 239000012530 fluid Substances 0.000 claims description 49
- VEXZGXHMUGYJMC-UHFFFAOYSA-N HCl Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 41
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 41
- 238000010438 heat treatment Methods 0.000 claims description 40
- 238000010521 absorption reaction Methods 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 27
- 235000012254 magnesium hydroxide Nutrition 0.000 claims description 26
- 238000000034 method Methods 0.000 claims description 26
- 239000007787 solid Substances 0.000 claims description 22
- 102100017923 ACOT12 Human genes 0.000 claims description 21
- 101710008266 ACOT12 Proteins 0.000 claims description 21
- VEXZGXHMUGYJMC-UHFFFAOYSA-M chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 17
- 239000007791 liquid phase Substances 0.000 claims description 16
- 238000004064 recycling Methods 0.000 claims description 16
- 229910019440 Mg(OH) Inorganic materials 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 11
- QWPPOHNGKGFGJK-UHFFFAOYSA-N Hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 claims description 6
- VTYYLEPIZMXCLO-UHFFFAOYSA-L calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 6
- 150000004683 dihydrates Chemical class 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 239000007790 solid phase Substances 0.000 claims description 6
- ZLNQQNXFFQJAID-UHFFFAOYSA-L Magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims description 4
- 239000011777 magnesium Substances 0.000 claims description 4
- 239000011776 magnesium carbonate Substances 0.000 claims description 4
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims description 4
- 150000004685 tetrahydrates Chemical class 0.000 claims description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- NSNHWTBQMQIDCF-UHFFFAOYSA-M chloride;dihydrate Chemical compound O.O.[Cl-] NSNHWTBQMQIDCF-UHFFFAOYSA-M 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 235000010216 calcium carbonate Nutrition 0.000 claims 1
- 235000014380 magnesium carbonate Nutrition 0.000 claims 1
- 239000007789 gas Substances 0.000 abstract description 42
- 238000006243 chemical reaction Methods 0.000 abstract description 13
- 239000002918 waste heat Substances 0.000 abstract description 5
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L MgCl2 Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 abstract 2
- RTQCAYKHUMWCEM-UHFFFAOYSA-N [Mg].ClO Chemical compound [Mg].ClO RTQCAYKHUMWCEM-UHFFFAOYSA-N 0.000 abstract 1
- 238000000354 decomposition reaction Methods 0.000 abstract 1
- 229910001629 magnesium chloride Inorganic materials 0.000 abstract 1
- DARFZFVWKREYJJ-UHFFFAOYSA-L magnesium;dichloride;dihydrate Chemical compound O.O.[Mg+2].[Cl-].[Cl-] DARFZFVWKREYJJ-UHFFFAOYSA-L 0.000 abstract 1
- 239000000047 product Substances 0.000 description 19
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 9
- 239000007864 aqueous solution Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- UGFAIRIUMAVXCW-UHFFFAOYSA-N carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 5
- 239000003546 flue gas Substances 0.000 description 4
- 239000000376 reactant Substances 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate dianion Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 239000011343 solid material Substances 0.000 description 3
- 238000010793 Steam injection (oil industry) Methods 0.000 description 2
- 229940056345 Tums Drugs 0.000 description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L cacl2 Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 description 2
- 239000001110 calcium chloride Substances 0.000 description 2
- 229910001628 calcium chloride Inorganic materials 0.000 description 2
- 230000005611 electricity Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- -1 dihydrate salts Chemical class 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 239000012263 liquid product Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Abstract
Embodiments of the present disclosure are directed to systems and methods of removing carbon dioxide from a gaseous stream using magnésium hydroxide and then regenerating the magnesium hydroxide. In some embodiments, the systems and methods can further comprise using the waste heat from one or more gas streams to provide some or ail of the heat needed to drive the reactions. In some embodiments, magnesium chloride is primarily in the form of magnesium chloride dihydrate and is fed to a decomposition reactor to generate magnesium hydroxychloride, which is in turn fed to a second décomposition reactor to generate magnesium hydroxide.
Description
[0001] This application claims the benefit of priority to U.S. Provisional Patent
Application Serial No. 62/119,633, filed February 23, 2015, hereby incorporated by reference in its entirety.
A. Field of the Invention [0002] The invention generally concems devices, Systems, and methods related to
Systems and processes of carbon séquestration with magnésium hydroxide and for 10 régénération of magnésium hydroxide from magnésium halide.
B. Background [0003] Considérable domestic and international concem has been increasingly focused on the émission of CO2 into the air. In particular, attention has been focused on the effect of this gas on the rétention of solar heat in the atmosphère, producing the “greenhouse 15 effect.” Although there is some debate regarding the magnitude of the effect, ail would agréé there is a benefit to removing CO2 (and other chemicals) from point-émission sources, especially if the cost for doing so were sufficiently small.
[0004] Despite years of development, the task of creating a commercially-viable, environmentally-sensitive process for removing carbon dioxide from an émission source has 20 proven to be a difficult. The méthodologies to date hâve not been altogether satisfactory in this regard, and a sîgnificant need exists for the techniques described and claimed in this disclosure.
SUMMARY [0005] One aspect of the présent disclosure is a system configured to regenerate
Mg(OH)2 and reduce the amount of CO2 contained in a gas stream through consumption of the Mg(OH)2. In some embodiments, the system can comprise: a first décomposition reactor configured to react MgCh containing material with steam to form first reactor products comprising Mg(OH)Cl and HCl; a second décomposition reactor configured to react Mg(OH)Cl from the first décomposition reactor with steam to form HCl and magnésium containing products comprising mostly Mg(0H)2; and a first absorption reactor configured to form an admixture comprising Mg(0H)2 from the second décomposition reactor, CO2, CaCh, and steam to form products comprising MgCh and CaCCh. The MgCh containing material fed to the first décomposition reactor can comprise a molar ratio of water to MgCh of less 5 than about 2.5:1. In some embodiments, the system can further comprise a gaseous feed line configured to pass a gaseous outflow from the second décomposition reactor to the first décomposition reactor, where the gaseous outflow comprises HCl and steam. In some embodiments, the system can further comprise a second absorption reactor, wherein the first absorption reactor is configured to admix Mg(0H)2 from the second décomposition reactor 10 with CO2 contained in the gas stream and form MgCCh and H2O and wherein the second absorption reactor is configured to admix the MgCCh from the first absorption reactor with CaCh and form CaCCh and MgCh. In some embodiments, the first absorption reactor products are in a liquid phase and a solid phase, and the liquid phase is at least 50% by weight of MgC12. In some embodiments, the first absorption reactor (or the second 15 absorption reactor if présent) contains a liquid phase comprising a ratio of water to MgCh of less than about 4.5:1 or about 4 to 1. In some embodiments, a major portion of MgCh in the liquid phase that exits an absorption reactor is in the form of MgC12 tetrahydrate. In some embodiments, the system further comprises a solid liquid separator configured to separate at least a portion of the CaCCh from the liquid phase. In some embodiments, the system a dryer 20 configured to remove a portion of the water from the liquid phase so the ratio of water to
MgCh is about 2 to 1. In some embodiments, a waste heat recovery and heat transfer system is utilized to provide the necessary heat to maintain reaction conditions for each system module.
[0006] Another aspect of the disclosure is a method of regenerating Mg(OH)2 in a process that reduces the amount of CO2 contained in a gas stream. In some embodiments, the method can comprise the following steps: (a) reacting MgCh-containing material with steam in a first admixture to form step(a) products comprising Mg(OH)Cl and HCl, where the MgCh containing material comprises a water to MgCh ratio of less than about 2.5:1; (b) reacting Mg(OH)Cl from step (a) with steam in a second admixture to form step(b) products 30 comprising HCl and magnesium-containing products comprising mostly Mg(OH)2; and (c) reacting Mg(OH)2 from step (b) with CO2, CaCh, and steam to form step (c) products comprising MgCh and CaCCh. In some embodiments, the method further comprises passing a gaseous outflow from the second admixture to the first admixture, where the gaseous outflow comprises HCl and steam to react with the MgCh containing material. In some embodiments, step (c) can comprise a two stage process of admixing Mg(0H)2 from step (b) with CO2 contained in the gas stream in a third admixture to form first step (c) products comprising MgCCh and H2O and admixing the MgCCh from first step (c) products with 5 CaCh in a fourth admixture to form a second step (c) products comprising CaCCh and
MgCh. In some embodiments, the liquid phase of the first admixture is at least 50% by weight of MgCh. The method can further comprise the step or steps of separating at least a portion of the CaCCh and a portion of the water from the second step (c) products so that, in a remaining product, the ratio of water to MgCh is about 2 to 1. In some embodiments, the 10 first step (a) product comprises greater than 90% by weight of Mg(OH)Cl. In some embodiments, the first step (b) product comprises greater than 90% by weight of Mg(0H)2. In some embodiments, the method can comprise recovering waste heat from a gas stream and transferring to the first admixture, the second admixture, and/or the remaining product comprising MgCh dihydrate. In recovering and transferring the waste heat, three or more 15 heating loops can be used.
[0007] Another aspect of the présent disclosure is a method for producing magnésium hydroxide from magnésium chloride-containing material comprising: a first stage comprising the steps of introducing said material into a first reactor, passing a steam mixture into the first reactor with the magnésium chloride-containing material at the approximate température of 20 250 to 400 C, to form magnésium hydroxychloride and HCl, a second stage of conveying the magnésium hydroxychloride into a second reactor, introducing therewith steam to form magnésium hydroxide and HCl, where the magnésium chloride-containing material comprises a water to magnésium chloride ratio of about 2:1. In some embodiments, a portion of a steam mixture exiting the second reactor is the steam mixture introduced into the first 25 reactor. At least a portion of the HCl exits the second reactor in the steam mixture that then passes through the first reactor. In some embodiments, the magnésium chloride-containing material substantially comprises magnésium chloride dihydrate. In some embodiments, waste heat is utilized to provide the heat necessary to form the Mg(OH)2.
[0008] The terms “a” and “an” are defined as one or more unless this disclosure explicitly requires otherwise.
[0009] The terms “substantially,” “approximately” and “about” are defined as being largely but not necessarily wholly what is specified (and include wholly what is specified) as understood by one of ordinary skill in the art. In any disclosed embodiment, the term >· “substantially,” “approximately,” or “about” may be substituted with “within [a percentage] of ’ what is specified, where the percentage includes 0.1,1, 5, and 10 percent.
[0010] The terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “hâve” (and any form of hâve, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”) and “contain” (and any form of contain, such as “contains” and “containing”) are open-ended linking verbs. As a resuit, any of the présent devices, Systems, and methods that “comprises,” “has,” “includes” or “contains” one or more éléments possesses those one or more éléments, but is not limited to possessing only those one or more éléments. Likewise, an element of a device, system, or method that “comprises,” “has,” “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features. Additionally, terms such as “first” and “second” are used only to differentiate structures or features, and not to limit the different structures or features to a particular order.
[0011] Furthermore, a structure that is capable performing a function or that is configured in a certain way is capable or configured in at least that way, but may also be capable or configured in ways that are not listed.
[0012] The feature or features of one embodiment may be applied to other embodiments, even though not described or illustrated, unless expressly prohibited by this disclosure or the nature of the embodiments.
[0013] Any of the présent devices, Systems, and methods can consist of or consist essentîally of—rather than comprise/include/contain/have—any of the described éléments and/or features and/or steps. Thus, in any of the claims, the term “consisting of’ or “consisting essentîally of ’ can be substituted for any of the open-ended linking verbs recited above, in order to change the scope of a given claim from what it would otherwise be using the open-ended linking verb.
[0014] Details associated with the embodiments described above and others are presented below.
BRIEF DESCRIPTION OF THE DRAWINGS [0015] The following drawings illustrate by way of example and not limitation. For the sake of brevity and clarity, every feature of a given structure may not be labeled in every figure in which that structure appears. Identical reference numbers do not necessarily indicate an identical structure. Rather, the same reference number may be used to indicate a similar feature or a feature with similar functionality, as may non-identical reference numbers.
[0016] FIG. 1 is a simplified process flow diagram according to some embodiments of the processes provided herein.
[0017] FIG. 2 is a simplified process flow diagram according to some embodiments of the processes provided herein.
[0018] FIG. 3 is a simplified process flow diagram according to some embodiments of the processes provided herein.
DETAILED DESCRIPTION [0019] Referring to FIG. 1, shown therein and designated by the reference numéral
100 is a first embodiment of a system configured to remove from a gaseous stream using Mg(OH)2 and to regenerate the Mg(OH)2. . System 100 is configured to absorb carbon dioxide from a gas stream 2 and regenerate at least one of the reactants, e.g., magnésium hydroxide, used in the absorption process. System 100 comprises an absorption reactor 10 15 configured to absorb CO2 from a gaseous stream; a solid-liquid separator 20 configured to separate carbonate solids from aqueous magnésium chloride; a dryer 30 configured to remove a portion of water from the aqueous magnésium chloride forming magnésium chloride solids; a first décomposition reactor 40 configured to convert the magnésium chloride to magnésium hydroxychloride, and a second décomposition reactor 45 configured 20 to convert the magnésium hydroxychloride to magnésium hydroxide. Also illustrated in system 100 is a pluralîty of heaters and heating fluid Systems to elevate the températures of the different reactants.
[0020] Prior to treating the carbon dioxide containing gas stream 2, the température of gas stream 2 may be lowered. In the instance of a hot gas stream, (e.g., gas turbine exhaust), 25 gas stream 2 can provide process heat that is transferred to different units in the system. In some embodiments, the process heat can be transferred to one or more of boilers, pre-heaters, reactors, or dryers 30 in the system. For example, in the embodiment shown, process heat can be transferred to a recycling heating fluid such as a hot oil system configured to provide indirect heating to the décomposition reactor. In some embodiments, process heat can be 30 used to heat a boiler configured to generate superheated steam for direct steam injection into the décomposition reactor. In some embodiments, a second recycling heating fluid, such as a second hot oil system, is configured to provide indirect heating to dryer 30 to remove water from the MgCh contaîning starting material.
[0021] After heat has been removed from gas stream 2, gas stream 2 enters absorption reactor 10 configured to react the CO2 with CaCh and Mg(OH)2 via the following overall 5 reactions:
CaCh + Mg(OH)2 + CO2 CaCO3 + MgCh+ H2O (1) [0022] Reactor 10 can be configured to receive CaCh feed 3, gas stream 2, and a
Mg(OH)2 feed. In some embodiments, absorption reactor 10 is configured to operate at températures greater than 165 °C, such as between about 170 to 250 °C. In some 10 embodiments, the operation température of reactor 10 can be at least 170,175,180,185,190,
195, 200, 210, 220, 230, or 240°C. In some embodiments, the operation température of reactor 10 is between 175 and 185 °C. To maintain a température above the operation température, reactor 10 can be configured similar to a distillation column, with a water reflux entering the top of the column and a heat input at the bottom of the column to maintain a 15 bottom liquid product at the operation température, such as about 175 °C.
[0023] In some embodiments, the reactants can be preheated to the operation température prior to introducing into absorption reactor 10. For example, a calcium chloride feed 3 is preheated in heater 60 prior to being added to absorption reactor 10. In some embodiments, a water feed 4 may also be preheated in heater 61. As the reaction of CO2 with 20 hydroxide is exothermic, heat can be removed from reactor 10 to maintain operation température. In some embodiments, a circulating heating fluid loop (not shown) can be configured to transfer heat from reactor 10 to CaCh feed 5, such as through heater 60. Similarly, a separate circulating heating fluid loop (not shown) can be configured to transfer heat from reactor 10 to water feed 4, such as through heater 61. By way of example, 25 approximately 63 MMBtu/hr of process heat (such as from reactor 10) can be needed to heat 1,679 lb*mol/hr of CaCh*2H2O solids from 25°C to 175°C and melt the solids at its melting point of 175°C, and to heat 1,679 lb*mol/hr of water from 25°C to 100°C, vaporize the water, and superheat the steam to 175°C.
[0024] Calcium chloride can be added to reactor 10 in one of three forms to absorption reactor 10: anhydrous CaCh, CaCh*2H2O, or CaCh*4H2O. In some embodiments, a molar ratio of water to CaCh of about 3:1 or less can be added to the absorption column for every mole of CO2 that is captured. In some embodiments,
CaCh*2H2O and water are fed to absorption reactor 10 to create an équivalent mixture of
CaCh*3H2O (67.2 wt% aqueous CaCh). In some embodiments, CaCh feed 3 in dihydrate form can be converted from a solid phase to a liquid phase prior to entering reactor 10.
[0025] Reactor 10 is configured to comprise an outlet for aqueous slurry of CaCOs solids in aqueous MgCh and an outlet for gas stream 2 that contains a reduced amount of
CO2 than that inputted into reactor 10. In some embodiments, gas stream 2 with the reduced
CO2 concentration exits absorption reactor 10 and can then pass through gas cooler 72 where heat can be further recovered before gas stream 2 is exhausted to the atmosphère or further processed downstream. The heat can be used to pre-heat the reactants, such as CaCh and 10 optionally water. As a resuit of the absorption column, the amount of CO2 in gas stream 2 can be reduced by at least 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, or 99%.
[0026] In some embodiments, at least 50 wt% aqueous MgCh exits absorption reactor and enters solid-liquid separator 20, which séparâtes the CaCCh solids from the aqueous solution. In some embodiments, a weight percent of aqueous MgCh between 50 to 60% exits 15 absorption reactor 10 and enters solid-liquid separator 20, such as 51%, 53%, 55%, 57%, or
59% wt MgCh. In some embodiments, a ratio of water to MgCh in the aqueous solution is less than about 5 to 1, about 4.5 to 1, or about 4 to 1. In some embodiments, a major portion of MgCh in the aqueous solution is in the form of MgCh tetrahydrate.
[0027] In some embodiments, water may be added to solid-liquid separator 20 to facilitate the séparation of the carbonate solids. In such embodiments, the amount of water to be added can dilute the solution by less than 30%, 25%, 20%, 15%, 10%, or 5%. Once separated, in some embodiments, the hot CaCCh solids can be passed through a cooler 70 for energy recovery before being sent to storage.
[0028] After separating the carbonate solids from the aqueous MgCh, the aqueous solution is transferred to dryer 30 to remove water from the solution. In some embodiments, a sufficient amount of water is evaporated from the solution so that the ratio of water to MgCh is less than about 3:1, about 2.5:1, or less than about 2 to 1. In some embodiments, a major portion of the water in the magnésium chloride-containing material exiting dryer 30 is in the form of MgCh dihydrate. For example, the magnésium chloride containing material 30 comprises at least 55%, 60%, 65% 70%, 75% 80%, 85% 90%, 95%, or 98% of MgCh*2H2O (s). The primary reaction in dryer 30 is provided below:
MgCh*4H2O (1) -» MgCh*2H2O (s) + 2 H2O (g) (2) [0029] In some embodiments, to supply the needed energy to remove a portion of the water, heat can be supplied to the vessel to keep the operation température at between 150 to 250°C, such as 160, 170,180, 190, 200, 210, 220, 230, or 240°C. In some embodiments, the température can be kept between 195 and 205°C or 198 and 202°C. Dryer 30 is configured 5 such that superheated steam (and potentially some HCl) exits the top of the vessel, while magnésium chloride containing material comprising dihydrate salts moves to first décomposition reactor 40. In some embodiments, operation pressures are at atmospheric pressure. In some embodiments, the superheated steam produced from dryer 30 can supply at least a portion of the steam required for décomposition reactors 40 and/or 45.
[0030] In some embodiments, the aqueous MgCb solution is pumped through a heater before entering dryer 30 to raise the température of the solution to substantially equal to the operation températures of dryer 30. In some embodiments, heat can be transferred to the solution at heater 62 by a circulating heating fluid loop 83 configured to transfer heat from gas stream 2 to the aqueous solution.
[0031] In some embodiments, system 100 comprises an evaporator 30 that is configured to reduce the water content so that MgCh tums to solid and the solid material can be transferred to first décomposition reactor 40. For example, evaporator 30 can comprise a flash drum having a scraper or other agitator configured to facilitate conveyance to solid material. In some embodiments, in evaporator 30, a pressurized MgCh solution at the 20 operation température is flashed to atmospheric pressure to remove water from the aqueous solution and produce MgC12*2H2O solids. In some embodiments, a portion of the heating fluid in circulating loop 83 may be directed to evaporator 30 to maintain the operation températures of evaporator 30.
[0032] In some embodiments, system 100 comprises a dryer 30 that is configured to reduce the water content so that aqueous MgCh tums to solid and the solid material can be transferred to first décomposition reactor 40. Dryer 30 can be configured to apply indirect contact heating or direct contact heating using a medium such as air to maintain operation températures. For example, dryer 30 can be a rotary dryer, a flash dryer, or a spray dryer. In some embodiments, a portion of the heating fluid in circulating loop 83 may be directed to 30 dryer 30 to maintain the operation températures of dryer 30 and may also be directed to blower to heat the drying medium such as air. Other embodiments, in lieu of dryer 30, system 100 can comprise a flaker, a crystallizer, or a priller configured to reduce the water content so that the molar ratio is about 2:1 and/or the MgCh is mostly in a dihydrate form and can be transferred to first décomposition reactor 40.
[0033] By way of example, the heat input needed to raise the température of the aqueous solution to an operation température of 200°C is approximately 7 MMBtu/hr. Further, also by way of example, the heat input needed to reduce the water content of an aqueous solution where the molar ratio of water is 4:1 is approximately 71 MMBtu/hr. For circulating heating fluid loop 83, the fluid retum température can be about 5 to 15°C above the operation température, e.g., 210°C, for the fluid leaving dryer 30 or heater 62. In addition, the fluid supply température (e.g., the température of the fluid approaching dryer 30 or heater 62) can be about 20 to 30°C above the operation température or 10 to 20°C above the retum température, e.g., 225°C. At the intercept of loop 83 with gas stream 2, the température of gas stream 2 can be a température that is at least 30 to 40 above the operation température of décomposition reactor 40. In some embodiments, the température of gas stream 2 after transferring heat to loop 83 can be at least 235 °C.
[0034] System 100 comprises reactors configured for a two stage, counter-current flow décomposition reactor to convert MgCh to Mg(OH)2. Within the first stage, reactor 40 is configured for the following reaction to occur:
MgCh*2H2O (s) -> Mg(OH)Cl (s) + HCl (g) + H2O (g) (3)
Within the second stage, reactor 45 is configured for the following reaction to occur:
Mg(OH)Cl (s) + H2O (g) -> Mg(OH)2 (s) + HCl (g) (4) [0035] In second reactor 45, steam can be counter-currently contacted with MgOHCl solids fed from first reactor 40. In some embodiments, steam can be generated by a boiler 90 that is heated by gas stream 2. Also, steam recycled from the exhaust of reactors 40 and 45 can be mixed with the steam from boiler 90 to feed reactor 45. Recycled steam may be heated by a heater 65 to obtain the desired final steam température to feed reactor 45. Steam is introduced into reactor 45 at a température that is substantially the same as the operation température of reactor 45 as described below. For example, steam can be introduced into reactor 45 at a température between 385°C and 395°C, such as about 390°C.
[0036] The Mg(OH)2 solids exiting reactor 45 are in equilibrium with the vapor leaving reactor 45. In some embodiments, the exiting vapor leaving reactor 45 will comprise at least 0.8 mole of HCl for every mole of Mg(OH)2 produced. For example, the exiting vapor leaving reactor 45 can comprise 0.85 mole of HCl, 0.9 mole of HCl, 0.95 mole of HCl, 0.98 mole HCl for ever mole of Mg(OH)2 produced. The rate of counter-flow through reactor 45 is sufficient to keep the partial pressure of HCl low enough so that reaction (5) equilibrium is shifted to the right. In some embodiments, the counter flow is 100% superheated steam. In other embodiments, the counter flow comprises superheated steam and an inert carrier gas. In some embodiment, the partial pressure of HCl can be maintained at a sufficiently low amount by operating the décomposition reaction 45 under vacuum conditions.
[0037] In reactor 40, the vapor mixture of superheated steam and HCl leaving reactor is counter-currently contacted with the magnésium chloride material fed from dryer or evaporator 30 comprising MgC12*2H2O solids. In some embodiments, only a portion of the steam exiting reactor 45 is fed to reactor 40. For example, a majority of the vapor exiting reactor 45 can bypass reactor 40 so that additional heat can be recovered in the HCl condenser 76. In some embodiments, the Mg(OH)Cl solids exiting reactor 40 are in equilibrium with the vapor leaving reactor 40. In some embodiments, the exiting vapor leaving reactor 40 will comprise at least an additional 0.8 mole of HCl for every mole of MgOHCl produced. For example, the exiting vapor leaving reactor 40 can comprise an additional 0.85 mole of HCl, 0.9 mole of HCl, 0.95 mole of HCl, 0.98 mole HCl for ever mole of MgOHCl produced. The rate of counter-flow through reactor 40 is sufficient to keep the partial pressure of HCl low enough to maintain a shift of reaction (4) to the right.
[0038] The operation température for reactor 45 can be between 380°C and 500°C, such as about 390, 400, 410, 420, 430,440, 450, 460, 470, or 490°C. In some embodiments, the operation température for reactor 45 is between about 385°C and 395°C, such as about 390°C. The operation température for reactor 40 can be between 250°C and 400°C, such as 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, or 390°C. In some embodiments, the operation température of reactor 40 is between about 275°C and 285°C, such as about 280°C. By way of example, the steam requirements for the two-stage countercurrent configuration can be approximately 8.6 lb/hr of steam per lb/hr HCl at 390°C for second reactor 45 and 280°C for first reactor 40.
[0039] An output of reactor 40 comprises solid MgOHCl. In some embodiments, the solid phase output of reactor 40 is at least 55%, 60%, 65% 70%, 75% 80%, 85% 90%, 95%, 98%, or 99% of MgOHCl. An output of reactor 45 comprises solid Mg(OH)2. In some embodiments, the solid phase output of reactor 45 is at least 55%, 60%, 65% 70%, 75% 80%,
85% 90%, 95%, 98%, or 99% of Mg(OH)2.
[0040] In some embodiments, to maintain operation températures of reactors 40 and
45, heat can be supplied to the décomposition reactors 40, 45 indirectly through a circulating heating fluid loop to keep the décomposition reactor at the desired température. For example, heating fluid jackets about each reactor 40 and 45 can facilitate maintenance of the operation température. In the embodiment shown, circulating heating fluid loop 84 is configured to transfer heat from gas stream 2 to reactor 40 and circulating heating fluid loop 85 is configured to transfer heat from gas stream 2 to reactor 45.
[0041] In some embodiments, the MgCh containing material exiting dryer 30 can be conveyed through a heater 64 before entering reactor 40 to raise the température of the solution to substantially equal to the operation températures of reactor 40. In some embodiments, while not shown in the one illustrated, a portion of the heating fluid in circulating loop 84 may be directed to heater 64 to heat the MgCh containing material fed to reactor 40.
[0042] In some embodiments, for circulating heating fluid loop 85, the fluid retum température (e.g., for the heating fluid leaving reactor 45 and heater 65) can be about 5 to 15°C above the operation température of reactor 40; e.g., the fluid retum température can be about 400°C. In addition, the fluid supply température (e.g., the température of the fluid approaching reactor 45 and heater 65) can be about 10 to 45°C above the operation température or 5 to 25°C above the retum température; e.g., the fluid supply température can be about 415°C. At the intercept of loop 85 with gas stream 2, the température of gas stream 2 can be greater than 500°C or greater than 600°C, e.g., the température of a flue gas exhaust stream. In some embodiments, the température of gas stream 2 after transferring heat to loop 85 can be at least 10°C higher than the température of the heating fluid approaching reactor 45.
[0043] In some embodiments, for circulating heating fluid loop 84, the fluid retum température (e.g., the température of the heating fluid leaving reactor 40 or heater 64) can be about 5 to 15°C above the operation température of reactor 45; e.g., the fluid retum température can be about 290°C. In addition, the fluid supply température (e.g., the température of the fluid approaching reactor 40 or heater 64) can be about 5 to 20°C above the operation température or 60 to 100°C above the retum température; e.g., the fluid supply température can be about 355°C. At the intercept of loop 84 with gas stream 2, the température of gas stream 2 can be greater than 500°C or greater than 600°C, e.g., the température of a flue gas exhaust stream. In some embodiments, the température of gas stream 2 after transferring heat to loop 85 can be at least 10 degrees higher than the température of the heating fluid approaching reactor 40.
[0044] The hot Mg(OH)2 solids exiting reactor 45 can be passed through a solids product cooler 74 before entering absorption reactor 10, while the vapor product exiting reactor 40 is combined with the vapor bypass 6 around reactor 40. The combined vapor stream passes through HCl condenser 76 before being pumped to an HCl product tank.
[0045] As évident from the operation températures of the décomposition reactor, there are significant enthalpy requirements for the décomposition reactor, namely, the reaction enthalpy for the décomposition of MgCh*2H2O to Mg(OH)2 and HCl and the superheated steam requirements for direct steam injection into the décomposition reactor. In some embodiments, system 100 can comprise a gas turbine or be configured to receive gas stream 2 produced from a gas turbine, such as a 60MW gas turbine 95 in the embodiment shown. In some embodiments, the overall CO2 capture rate can be greater than 70%, 80%, 90%, 95%, or greater than 99%.
[0046] In addition to a first gas turbine, system 100 can comprise a fumace (not shown) to bum supplémentai naturel gas, and use heat recovered from the flue gas at the flame température to provide additional heat for steam génération within system 100. In some embodiments, for a two-stage counter-current reactor, the total enthalpy requirement for the process can be about 175 MMBtu/hr. The heat available from 60 MW turbine exhaust gas is about 146 MMBtu/hr, leaving an overall deficiency of about 29 MMBtu/hr that would be required to achieve 100% CO2 capture. Buming 1.4 MMSCFD of supplémentai naturel gas in a fumace can provide heat recovery from the flue gas of 44.9 MMBtu/hr. In some embodiments, an additional 16-17 MMBtu/hr of enthalpy would be required within system 100 to capture this additional CO2. This results in a net enthalpy surplus that could be used to achieve 100% CO2 capture. If this 1.4 MMSCFD of naturel gas were instead fired in a turbine, 5.6 MW of additional electricity could be produced (relative to the 60 MW of electricity produced in the existing turbine).
[0047] Referring now to FIG. 2, shown therein and designated by the reference numéral 200 is a second embodiment of a system configured to remove from a gaseous stream using Mg(OH)2 and regenerate the Mg(OH)2. Embodiment 200 is substantially similar to embodiment 100 described above, except that the décomposition process comprises only a single stage counter flow reactor 48 and circulating heating fluid loop 86 instead of loops 84 and 85. In some embodiments, the operation température of reactor 48 can be between 340°C -360°C, such as 350 °C. The superheated steam can be introduced at a température substantially the same as the operation température.
[0048] Referring now to FIG. 3, shown therein and designated by reference numéral
300 is an embodiment of a two-stage CO2 absorption process that can be substituted for the one stage absorption process described above in connection with reactor 10. The two-stage process is substantially similar to the conditions described for the one-stage process except that two reactors are used instead of one and a slightly higher molar ratio of water to MgCh is required. Within the first stage, reactor 12 is configured for the following reaction to occur:
Mg(OH)2 (s) + CO2 (g) ·» MgCO3 (aq) + H2O (1) (5)
Within the second stage, reactor 14 is configured for the following reaction to occur:
CaCh (aq) + MgCO3 (aq) ·» CaCO3 (s) + MgCh (aq) (6) [0049] In some embodiments, in reactor 12, the molar ratio of water to MgCO3 can be about 3.5:1 or about 3:1. In some embodiments, in reactor 14, the molar ratio of water to MgCh can be about 5.5:1 or about 5:1.
[0050] The above spécification and examples provide a complété description of the structure and use of exemplary embodiments. Although certain embodiments hâve been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the scope of this invention. As such, the illustrative embodiments of the présent Systems and processes for removing carbon dioxide from a gaseous stream and regenerating magnésium hydroxide are not intended to be limiting. Rather, the présent devices, Systems, and methods include ail modifications and alternatives falling within the scope of the claims, and embodiments other than those shown may include some or ail of the features of the depicted embodiments. For example, components may be combined as a unitary structure and/or connections may be substituted. Further, where appropriate, aspects of any of the examples described above may be combined with aspects of any of the other examples described to form further examples having comparable or different properties and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments.
[0051] The claims are not to be interpreted as including means-plus- or step-plusfunction limitations, unless such a limitation is explicitly recited in a given claim using the 5 phrase(s) “means for” or “step for,” respectively.
Claims (43)
1. A method for producing magnésium hydroxide from magnésium chloride-containing material comprising:
a first stage comprising the steps of introducing said material into a first reactor, passing a steam mixture into the first reactor with the magnésium chloridecontaining material at the approximate température of 250 to 400°C, to form magnésium hydroxychloride and HCl, and a second stage of conveying the magnésium hydroxychloride into a second reactor, introducing therewith steam to form magnésium hydroxide and HCl, where the magnésium chloride-containing material comprises a water to magnésium chloride ratio of about 2:1.
2. The method of claim 1, where a portion of a steam mixture exiting the second reactor is the steam mixture introduced into the first reactor.
3. The method of claim 1, where at least a portion of the HCl exits the second reactor in the steam mixture that then passes through the first reactor.
4. The method of claim 1, where the magnésium chloride-containing material substantially comprises magnésium chloride dihydrate.
5. The method of claim 1, where a portion of HCl formed in the first reactor exits the first reactor with the steam mixture.
6. The method of claim 1, where the first reactor is at a température of 250-350°C.
7. The method of claim 6, transferring heat from a hot gas stream to the first recycling heating fluid and transferring heat from the first recycling heating fluid to the first reactor.
8. The method of claim 1, where the second reactor is at a température of 300-500°C.
9. The method of claim 5, transferring heat from the hot gas stream to a second recycling heating fluid and transferring heat from the second recycling heating fluid to the second reactor.
10. The method of claim 1, where the steam introduced into the second reactor is at a température between 350-450°C.
11. The method of claim 1, where no MgCh is conveyed to the second reactor separate from that in product conveyed from the first reactor.
12. A method of regenerating Mg(OH)2 in a process that reduces the amount of CO2 contained in a gas stream, comprising:
(a) reacting MgCh containing material with steam in a first admixture to form step(a) products comprising Mg(OH)Cl and HCl, where the MgCh containing material comprises a water to MgCh ratio of less than about 2.5:1;
(b) reacting Mg(OH)Cl with steam in a second admixture to form step(b) products comprising HCl and magnesium-containing products comprising mostly Mg(OH)2;
(c) reacting Mg(OH)2 with CO2, CaCh, and steam to form step (c) products comprising MgCh and CaCÛ3.
13. The method of claim 12, passing a gaseous outflow from the second admixture to the first admixture, where the gaseous outflow comprises HCl and steam to react with the MgCh containing material.
14. The method of claim 12, where step (c) comprises admixing Mg(OH)2 from step (b) with CO2 contained in the gas stream in a third admixture to form first step (c) products comprising MgCCh and H2O, and admixing the MgCCh from first step (c) products with CaCh in a fourth admixture to form a second step (c) products comprising CaCCh and MgCh.
15. The method according to claim 12, wherein the step (c) product are in a liquid phase and a solid phase and where the liquid phase is at least 50% by weight of MgCh.
16. The method of claim 12, where a ratio of water to MgCh in the fourth admixture is about 4 to 1.
17. The method of claim 12, where a major portion of MgCh formed in step (c) is in the form of Mg.Ch tetrahydrate.
18. The method of claim 16, further comprising separating at least a portion of the CaCO.3 from the second step (c) products and removing a portion of the water from the remaining second step (c) products so the ratio of water to MgCh is about 2 to 1.
19. The method of claim 18, wherein a major portion of the water in the remaining second step (c) products is présent in the form of MgCh dihydrate.
20. The method according to claim 18, wherein the remaining step (c) product is at least 50% by weight of aqueous MgCh.
21. The method according to claim 12, wherein the molar ratio of water to MgCh in the step (c) products is 5 or less.
t
22. The method of claim 21, wherein the MgCh hydrate of step (c) is MgC12.4H2O.
23. The method according to claim 22, wherein the MgCh of step (c) is greater than 90% by weight MgCh.4(H2O).
24. The method of claim 12, wherein the first step (a) product comprises greater than 90% by weight Mg(OH)Cl.
25. The method of claim 18, further comprising transferring heat from the gas stream to a first recycling heating fluid and transferring heat from the first recycling heating fluid to the first admixture.
26. The method of claim 25, further comprising transferring heat from the gas stream to a second recycling heating fluid and transferring heat from the second recycling heating fluid to the second admixture.
27. The method of claim 26, further comprising transferring heat from the gas stream to a third recycling heating fluid and transferring heat from the third recycling heating fluid to the remaining step (c) product to facilitate the removal of water.
28. The method of claim 27, where a température of the third recycling heating fluid is less than the second recycling heating fluid and the second recycling heating fluid is less than the first recycling heating fluid
29. The method of claim 12, wherein suitable reacting conditions of step (a) comprise a température from about 250°C. to about 350°C.
30. The method of claim 12, wherein reacting conditions of step (a) comprise a température from about 260°C. to about 300°C.
31. The method of claim 12, wherein reacting conditions of step (b) comprise a température from about 350°C. to about 500°C.
32. The method of claim 12, wherein reacting conditions of step (b) comprise a température from about 370°C. to about 430°C.
33. The method of claim 12, wherein the reacting conditions of step (c) comprise a température from about 140°C to about 220°C.
34. The method of claim 12, wherein the reacting conditions of step (c) comprise a température from about 150°C to about 200°C.
35. A system for regenerating Mg(OH)2 in a process that reduces the amount of CO2 contained in a gas stream, comprising:
a first décomposition reactor configured to react MgCh containing material with steam to form first reactor products comprising Mg(OH)Cl and HCl, where the MgCh containing material comprises a water to MgCh ratio of less than about 2.5:1;
a second décomposition reactor configured to react Mg(OH)Cl from the first décomposition reactor with steam to form HCl and magnesium-containing products comprising mostly Mg(OH)2;
a first absorption reactor configured to react Mg(OH)2 from the second décomposition reactor with CO2, CaCb, and steam to form products comprising MgCb and CaCO3.
36. The system of claim 35, further comprising a gaseous feed line configured to pass a gaseous outflow from the second décomposition reactor to the first décomposition reactor, where the gaseous outflow comprises HCl and steam to react with the MgCb containing material.
37. The system of claim 35, further comprising a second absorption reactor, wherein the first absorption reactor is configured to admix Mg(OH)2 from the second décomposition reactor with CO2 contained in the gas stream and form MgCCb and H2O, and the second absorption reactor is configured to admix the MgCO3 from the first absorption reactor with CaCb and form CaCCh and MgCb.
38. The system according to claim 35, wherein the first absorption reactor products are in a liquid phase and a solid phase and where the liquid phase is at least 50% by weight ofMgCb.
39. The system of claim 35, where the first absorption reactor contains a liquid phase comprising a ratio of water to MgCb of about 4 to 1.
40. The system of claim 39, where a major portion of MgCb in the liquid phase that exits the first absorption reactor is in the form of MgCb tetrahydrate.
41. The system of claim 39, further comprising solid liquid separator configured to separate at least a portion of the CaCCh from the liquid phase.
42. The system of claim 41, further comprising a dryer configured to remove a portion of the water from the liquid phase so the ratio of water to MgCb is about 2 to 1.
43. The system of claim 41, wherein the dryer configured to form MgCb dihydrate.
Applications Claiming Priority (1)
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US62/119,633 | 2015-02-23 |
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OA18406A true OA18406A (en) | 2018-11-02 |
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