Abstract:
A method includes transferring at least one feed stream including calcium oxide calcium carbonate, water, and a fluidizing gas into a fluidized bed; contacting the calcium oxide with the water; based on contacting the calcium oxide with the water, initiating a hydrating reaction; producing, from the hydrating reaction, calcium hydroxide and heat; transferring a portion of the heat of the hydrating reaction to the calcium carbonate; and fluidizing the calcium oxide, calcium hydroxide, and the calcium carbonate into a first fluidization regime and a second fluidization regime. The first fluidization regime includes at least a portion of the calcium carbonate and at least a portion of the calcium oxide, and the second fluidization regime includes at least a portion of the calcium hydroxide and at least another portion of the calcium oxide. The first fluidization regime being different than the second fluidization regime.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application Ser. No. 62/334,225, entitled “High Temperature Hydrator,” and filed on May 10, 2016, the entire contents of which are incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure describes systems, apparatus, and methods for converting calcium oxide to calcium hydroxide. 
       BACKGROUND 
       [0003]    Calcium oxide conversion to calcium hydroxide has been described, in which calcium oxide is reacted with water to produce either a fine, dry powder of calcium hydroxide or a slurry of calcium hydroxide in water. The resulting calcium hydroxide is used in calcium based caustic recovery processes such as the Kraft caustic recovery process employed by the pulp and paper industry. 
       SUMMARY 
       [0004]    In an example implementation, a method includes transferring at least one feed stream including calcium oxide calcium carbonate, water, and a fluidizing gas into a fluidized bed; contacting the calcium oxide with the water; based on contacting the calcium oxide with the water, initiating a hydrating reaction; producing, from the hydrating reaction, calcium hydroxide and heat; transferring a portion of the heat of the hydrating reaction to the calcium carbonate; and fluidizing the calcium oxide, calcium hydroxide, and the calcium carbonate into a first fluidization regime and a second fluidization regime. The first fluidization regime includes at least a portion of the calcium carbonate and at least a portion of the calcium oxide, and the second fluidization regime includes at least a portion of the calcium hydroxide and at least another portion of the calcium oxide. The first fluidization regime being different than the second fluidization regime. 
         [0005]    In an aspect combinable with the example implementation, the second fluidization regime includes another portion of the calcium carbonate. 
         [0006]    In another aspect combinable with any of the previous aspects, fluidization takes place using at least one fluidization velocity, the at least one fluidization velocity sufficient to cause the at least a portion of one of the calcium carbonate, calcium hydroxide or calcium oxide to separate from the at least a portion of the other calcium carbonate, calcium hydroxide or calcium oxide into the first and second fluidization regime. 
         [0007]    In another aspect combinable with any of the previous aspects, the first and second fluidization regimes include a bubbling bed regime and at least one of a transport or turbulent regime. 
         [0008]    Another aspect combinable with any of the previous aspects further includes transferring at least a portion of the heat to the calcium carbonate. 
         [0009]    Another aspect combinable with any of the previous aspects further includes fluidizing at least a portion of the calcium carbonate in the bubbling bed regime; and fluidizing at least a portion of the calcium hydroxide in the transport or turbulent fluidization regime. 
         [0010]    In another aspect combinable with any of the previous aspects, the fluidizing gas includes steam. 
         [0011]    Another aspect combinable with any of the previous aspects further includes recirculating a portion of at least one of the calcium oxide or the calcium hydroxide in the transport or turbulent fluid regime back into the fluidized bed; and based on the recirculating, increasing a residence time of at least one of the calcium oxide or calcium hydroxide in the fluidized bed. 
         [0012]    Another aspect combinable with any of the previous aspects further includes generating steam from excess heat; and circulating the generated steam to provide heat or power to the at least one of a downstream heat consumer or power producers. 
         [0013]    Another aspect combinable with any of the previous aspects further includes providing the water from at least one of a steam feed, a liquid water feed, or water from a wet calcium carbonate feed. 
         [0014]    Another aspect combinable with any of the previous aspects further includes recirculating the fluidization gas that exits a fluidized gas outlet of the fluidized bed to a fluidization gas inlet of the fluidized bed. 
         [0015]    In another aspect combinable with any of the previous aspects, the method is part of a caustic recovery process. 
         [0016]    In another aspect combinable with any of the previous aspects, the caustic recovery process is part of at least one of a direct air capture process, a carbon dioxide capture process, or a pulp and paper process. 
         [0017]    In another aspect combinable with any of the previous aspects, at least a portion of one of calcium carbonate, calcium oxide or calcium hydroxide are separated into at least two different fluidization regimes based on one or more of physical properties of the calcium carbonate, calcium oxide, or calcium hydroxide. 
         [0018]    In another aspect combinable with any of the previous aspects, the one or more physical properties includes at least one of density, particle size or shape. 
         [0019]    Another aspect combinable with any of the previous aspects further includes at least one of heating or drying the calcium carbonate with at least one of a sensible heat of the calcium oxide or the produced heat of the hydrating reaction. 
         [0020]    In another aspect combinable with any of the previous aspects, each of the calcium oxide, the calcium carbonate, the water, and the fluidizing gas are transferred into the fluidized bed in a separate feed stream. 
         [0021]    In another aspect combinable with any of the previous aspects, the calcium oxide and at least a portion of at least one of the water or the fluidizing gas are transferred into the fluidized bed in a first fluid stream, and the calcium carbonate and at least a portion of at least one of the water or the fluidizing gas are transferred into the fluidized bed in a second fluid stream that is separate from the first fluid stream. 
         [0022]    In another example implementation, an apparatus includes a fluidized bed vessel that includes one or more inlet ports arranged to receive at least one feed stream including calcium oxide, calcium carbonate, water, and a fluidizing gas into a volume of the fluidized bed vessel, the fluidized bed vessel including a zone where the calcium oxide contacts the water to initiate a hydrating reaction to produce calcium hydroxide and heat, the fluidized bed vessel configured to operate with a fluidization velocity that fluidizes and separates at least a portion of the calcium carbonate and at least a portion of the calcium oxide into a first fluidization regime, and at least a portion of the calcium hydroxide and at least another portion of the calcium oxide into a second fluidization regime, the first fluidization regime different than the second fluidization regime; a heat transfer assembly thermally coupled to the fluidized bed vessel and configured to transfer a portion of the heat of the hydrating reaction to the calcium carbonate; a cyclone fluidly coupled to the fluidized bed vessel and configured to separate a portion of the fluidization gas from a portion of at least one of the calcium hydroxide, calcium carbonate or calcium oxide; and an outlet port configured to separate the fluidization gas from a portion of at least one of the calcium hydroxide, calcium carbonate or calcium oxide, and to discharge a portion of at least one of the calcium hydroxide, calcium carbonate or calcium oxide. 
         [0023]    In an aspect combinable with the example implementation, the fluidized bed vessel is configured to contain a bubbling bed regime and allows for at least one of a circulating turbulent or transport regime. 
         [0024]    Another aspect combinable with any of the previous aspects further includes a solids classifier fluidly coupled to the fluidized bed vessel and the outlet port, the solids classifier configured to separate a portion of at least one of the calcium carbonate, calcium hydroxide or calcium oxide from another portion of at least one of the calcium carbonate, calcium hydroxide or calcium oxide. 
         [0025]    In another aspect combinable with any of the previous aspects, the heat transfer assembly is configured to transfer a portion of a heat contained in the calcium oxide feed stream to the calcium carbonate. 
         [0026]    In another aspect combinable with any of the previous aspects, the bubbling bed regime includes calcium carbonate and at least one of a transport or turbulent regime including calcium hydroxide. 
         [0027]    In another aspect combinable with any of the previous aspects, the fluidized bed vessel is configured to operate with a fluidizing gas including steam. 
         [0028]    In another aspect combinable with any of the previous aspects, the cyclone further includes a port fluidly coupled to a non-mechanical seal, the non-mechanical seal fluidly coupled to the fluidized bed vessel and configured to recirculate at least a portion of one of calcium carbonate, calcium hydroxide or calcium oxide in the transport or turbulent fluid regime back into the fluidized bed vessel. 
         [0029]    In another aspect combinable with any of the previous aspects, the non-mechanical seal includes a loop seal. 
         [0030]    In another aspect combinable with any of the previous aspects, the at least one feed stream includes liquid water, the heat transfer assembly configured to transfer heat from the fluidized bed vessel to the liquid water to generate a steam stream. 
         [0031]    In another aspect combinable with any of the previous aspects, in the heat exchange assembly includes a heat tubing system thermally coupled to the fluidization bed vessel, the heat tubing system configured to transfer a portion of a heat from the fluidization bed vessel to a fluid stream within the heat tubing system. 
         [0032]    In another aspect combinable with any of the previous aspects, the apparatus is thermally and fluidly coupled to a dense fluidized bed heat exchanger. 
         [0033]    In another aspect combinable with any of the previous aspects, the cyclone further includes a fluidly coupled port that is configured to enable the fluidization gas to recirculate back to the fluidization gas inlet port. 
         [0034]    In another aspect combinable with any of the previous aspects, the solid classifier is configured to separate at least a portion of the calcium carbonate from a portion of at least one of the calcium hydroxide or the calcium oxide based on at least one of particle size or particle density. 
         [0035]    In another aspect combinable with any of the previous aspects, the solid classifier is configured to allow the at least one of calcium hydroxide or calcium oxide to return to the fluidized bed vessel. 
         [0036]    In another aspect combinable with any of the previous aspects, the solid classifier includes a cone and cap sloped stripper or a sieve. 
         [0037]    In another aspect combinable with any of the previous aspects, the apparatus is fluidly coupled to a caustic recovery process. 
         [0038]    In another aspect combinable with any of the previous aspects, the caustic recovery process includes a direct air capture process, a carbon dioxide capture process or a pulp and paper process. 
         [0039]    In another aspect combinable with any of the previous aspects, the at least one feed stream including calcium oxide, calcium carbonate, water, or a fluidizing gas further includes sensible heat, and the heat transfer assembly is configured to transfer at least a portion of the sensible heat to the calcium carbonate to enable at least one of heating or drying of the calcium carbonate. 
         [0040]    In another aspect combinable with any of the previous aspects, each of the calcium oxide, the calcium carbonate, the water, and the fluidizing gas are transferred into the fluidized bed in a separate inlet port. 
         [0041]    In another aspect combinable with any of the previous aspects, the calcium oxide and at least one of at least a portion of the water or a portion of the fluidizing gas are transferred into the fluidized bed in a first inlet port, and the calcium carbonate and at least one of at least a portion of the water or a portion of the fluidizing gas are transferred into the fluidized bed in a second inlet port that is separate from the first inlet port. 
         [0042]    Implementations according to the present disclosure may include one or more of the following features. For example, this system includes multiple components, for example dryer, hydrators and heat exchange componentry, in a single unit. In some aspects, conventional components for hydrating processes, such as a dryer, hydrator and heat exchange equipment, are replaced by one fluidized bed reactor. The fluidized bed reactor unit has no moving parts, and as such has lower maintenance than systems with separate hydrator, dryer and heat exchanger units, which can require for example transport and/or conveying equipment (with moving parts). The high temperature fluidized bed hydrator unit has higher thermal efficiency than the previously separated equipment, due to having the process streams in direct contact with heat sources (for example, other process streams, fluidizing gases). By using process streams in this manner, the multiple approach temperatures associated with separate heat exchangers can be reduced, for example, from multiple approaches to a single approach. Furthermore, the steam produced within the high temperature hydrator unit can be used in other areas of a plant, for example to provide heat or steam for power generation. This aids in improving overall energy efficiencies of the systems within which a high temperature hydrator may operate. 
         [0043]    The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]      FIG. 1  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed. 
           [0045]      FIG. 2  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed and an optional water injection system. 
           [0046]      FIG. 3A  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed, where circulating material may be recirculated. 
           [0047]      FIG. 3B  depicts another illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed, where circulating material may be recirculated. 
           [0048]      FIG. 4A  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed, where material discharged from the bed is further processed. 
           [0049]      FIG. 4B  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed, where material may be separated before being discharged. 
           [0050]      FIG. 5A  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed and a system for indirectly transferring heat. 
           [0051]      FIG. 5B  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed and a system for indirectly transferring heat. 
           [0052]      FIG. 6  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed and a system for indirectly transferring heat. 
           [0053]      FIG. 7  depicts an illustrative system for converting calcium oxide to calcium hydroxide including a fluidized bed connected with another system. 
       
    
    
     DETAILED DESCRIPTION 
       [0054]    The present disclosure describes example implementations of a high temperature hydrator system that may enable two or more solid feedstocks and any resulting solid reaction products to separate into two distinctly different fluidization regimes, based on the different solid physical properties, such as density, particle size distribution and shape. For example, a portion of the feedstocks and a portion of the resulting reaction products, consisting of, for example, more dense particles, larger particles and/or particles of a geometry, which, in the given fluidization environment, favor a bubbling bed regime, while another portion of the feedstocks and reaction products, consisting for example of less dense particles, smaller particles, and/or particles of a geometry, which, in the given fluidization environment, favor a turbulent or transport regime. Regimes of fluidization may result from the fact that fluidized solid beds behave differently as gas properties, velocity, and solid properties are varied. For example, when a solid bed (having a defined set of solid properties) is exposed to an upward flowing fluid, such as a gas (having a defined set of fluid properties), a pressure drop develops across the bed. As the upward flow rate of the fluid increases, there are a range of fluidization regimes that may develop. 
         [0055]    One example of a distinct fluidization regime is the bubbling bed regime. A bubbling bed regime is one where the solid material is fluidized above the material&#39;s incipient fluidization point but below the point where the material becomes entrained in the gas and capable of leaving the reactor with the gas flow. Another example of a distinct fluidization regime is a turbulent, or transport regime. The turbulent or transport regime is one where the solid material is fluidized to the point where the material becomes entrained in the gas and is transported out of the reactor with the gas. Other examples of distinct fluidization regimes seen in fluidized bed reactors may include homogeneous, dense suspension upflow, slugging, spouted bed, turbulent, fast fluidizing, and pneumatic transport. 
         [0056]    In addition to fluidizing the solids, this system provides a desirable environment to allow for the hydrating reaction to occur, whereby incoming calcium oxide mixes with water, in the form of liquid and/or steam, to produce calcium hydroxide. The sensible heat from some of the hot solid feed material, as well as the heat generated from the hydrating reaction itself are used to dry and preheat the other cooler, moist solid materials. Both the hydrating reaction and the heat transfer processes take place in a fluidized bed reactor vessel wherein solid calcium carbonate, solid calcium oxide, steam and liquid water come into contact. 
         [0057]    This system includes multiple components, for example dryer, hydrators and heat exchange componentry, in a single unit. In some aspects, conventional components for hydrating processes, such as a dryer, hydrator and heat exchange equipment, are replaced by one fluidized bed reactor. This resulting high temperature fluidized bed hydrator unit has higher thermal efficiency than the previously separated equipment, due to having the process streams in direct contact with heat sources (for example, other process streams, fluidizing gases). By using process streams in this manner, the desired multiple approach temperatures associated with separate heat exchangers are also reduced, for example, from multiple approaches to a single approach. The fluidized bed reactor unit has no moving parts, unlike conventional hydrator and dryer units, and as such, has lower maintenance than such conventional units. 
         [0058]    Each of the configurations described later may include process streams (also called “streams”) within a system for converting calcium oxide to calcium hydroxide including a fluidized bed. The process streams can be flowed using one or more flow control systems implemented throughout the system. A flow control system can include one or more flow pumps to pump the process streams, one or more flow pipes through which the process streams are flowed and one or more valves to regulate the flow of streams through the pipes. 
         [0059]    In some implementations, a flow control system can be operated manually. For example, an operator can set a flow rate for each pump and set valve open or close positions to regulate the flow of the process streams through the pipes in the flow control system. Once the operator has set the flow rates and the valve open or close positions for all flow control systems distributed across the system for converting calcium oxide to calcium hydroxide, the flow control system can flow the streams under constant flow conditions, for example, constant volumetric rate or other flow conditions. To change the flow conditions, the operator can manually operate the flow control system, for example, by changing the pump flow rate or the valve open or close position. 
         [0060]    In some implementations, a flow control system can be operated automatically. For example, the flow control system can be connected to a computer or control system (e.g., control system  999 ) to operate the flow control system. The control system can include a computer-readable medium storing instructions (such as flow control instructions and other instructions) executable by one or more processors to perform operations (such as flow control operations). An operator can set the flow rates and the valve open or close positions for all flow control systems distributed across the facility using the control system. In such implementations, the operator can manually change the flow conditions by providing inputs through the control system. Also, in such implementations, the control system can automatically (that is, without manual intervention) control one or more of the flow control systems, for example, using feedback systems connected to the control system. For example, a sensor (such as a pressure sensor, temperature sensor or other sensor) can be connected to a pipe through which a process stream flows. The sensor can monitor and provide a flow condition (such as a pressure, temperature, or other flow condition) of the process stream to the control system. In response to the flow condition exceeding a threshold (such as a threshold pressure value, a threshold temperature value, or other threshold value), the control system can automatically perform operations. For example, if the pressure or temperature in the pipe exceeds the threshold pressure value or the threshold temperature value, respectively, the control system can provide a signal to the pump to decrease a flow rate, a signal to open a valve to relieve the pressure, a signal to shut down process stream flow, or other signals. 
         [0061]    Referring to  FIG. 1 , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  100 . In some implementations, system  100  may include feed ports for streams  101 ,  102  and  105  fluidly coupled to the main system  100 , and a discharge port for stream  104  fluidly coupled to the main system  100 . In some aspects a gas distribution plate  106  may be fluidly coupled to the main vessel body of system  100 . In some aspects system  100  may include a cyclone  111  fluidly coupled to feed ports for stream  109  and discharge ports for streams  112 ,  110 . In some aspects system  100  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0062]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 1 , gaseous stream  102  including one or more fluidization gases is provided to the hydrator system  100  through the bottom entry zone  113 , also known as the plenum chamber, which is below the fluidization distribution plate  106 . Gaseous stream  102  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  101  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  106  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  100  and as such it remains in the bubbling bed zone  107 , unless discharged as stream  104 . Stream  101  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  105  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  106 . Stream  105  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  106  is designed to prevent backflow of any solids into the fluidization gas entry zone  113 . Solid material  105 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  107  and transported through the reactor freeboard zone  108 . The resulting mixed stream of fluidization gases and solids is mixed-stream  109 , and after leaving the reactor freeboard zone  108 , the stream  109  is sent to a cyclone  111 , to separate the solids  112 , from the gases  110 . The fluidization gas  102 , is blown into the fluidization gas entry zone  113 , of the fluidized bed reactor  100 . This fluidizing gas  102 , could be partially recycled from the gas stream  110  leaving the cyclone  111 . 
         [0063]    The hydrating reaction, where calcium oxide is converted to calcium hydroxide, takes place within the fluidized bed reactor system  100 : 
         [0000]      CaO(s)+H 2 O(l)→Ca(OH) 2 (s) hydrating reaction using liquid water.
 
         [0000]      CaO(s)+H 2 O(g)→Ca(OH) 2 (s) hydrating reaction using steam.
 
         [0064]    In some cases the water required for the hydrating reaction can be supplied into system  100  through excess steam brought in with stream  102 , or it could also be brought into the system  100  as part of the solids material requiring heating/drying, via stream  101  or  105 . In some cases, the stream requiring heat transfer (and that may contain liquid water) could be either stream  101  or  105 , depending on the application. For example, in a Kraft caustic recovery system, the calcium carbonate material may be introduced as smaller particles, which may be more comparable to lime mud in particle size, while the calcium oxide material may be introduced as larger particles or clumps, and could have sizes closer to approximately one (1) centimeter in diameter. 
         [0065]    In some implementations, a portion of the material normally fluidized within the turbulent/transport regime may leave with the material in the bubbling bed regime. In these implementations, it can be separated based on the difference in physical properties and re-introduced into the reactor system  100  or combined with the finished circulating solids stream  112 . 
         [0066]    In some implementations, the system  100  could be heat insulated with, for example insulation material. In these cases, care would need to be taken in selecting both the insulation material for heat economy, as well as the vessel material of construction. In some aspects, metal compositions that are capable of maintaining structural integrity under operating pressures and temperatures of around 300° C. would be selected, for example stainless steel or other metal compositions. 
         [0067]    In another implementation, system  100  could instead be insulated with refractory lining, allowing for more economical options for vessel material of construction, for example carbon steel. 
         [0068]    Referring to  FIG. 2 , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  200 . In some implementations, system  200  may include feed ports for streams  201 ,  202 ,  205  and  214  fluidly coupled to the main system  200 , and a discharge port for stream  204  fluidly coupled to the main system  200 . In some aspects a gas distribution plate  206  may be fluidly coupled to the main vessel body of system  200 . In some aspects system  200  may include a cyclone  211  fluidly coupled to feed ports for stream  209  and discharge ports for streams  212 ,  210 . In some aspects system  200  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0069]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 2 , gaseous stream  202  including one or more fluidization gases is provided to the hydrator system  200  through the bottom entry zone  213 , also known as the plenum chamber, which is below the fluidization distribution plate  206 . Gaseous stream  202  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  201  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  206  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  200  and as such it remains in the bubbling bed zone  207 , unless discharged as stream  204 . Stream  201  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  205  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  206 . Stream  205  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  206  is designed to prevent backflow of any solids into the fluidization gas entry zone  213 . Solid material  205 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  207  and transported through the reactor freeboard zone  208 . The resulting mixed stream of fluidization gases and solids is mixed-stream  209 , and after leaving the reactor freeboard zone  208 , the stream  209  is sent to a cyclone  211 , to separate the solids  212 , from the gases  210 . The fluidization gas  202 , is blown into the fluidization gas entry zone,  213 , of the fluidized bed reactor,  200 . This fluidizing gas  202 , could be partially recycled from the gas stream  210  leaving the cyclone  211 . A portion of the water required for the hydrating reaction can be supplied into system  200  through a variety of feed methods including excess steam brought in with stream  202 , as a direct, separate spray of liquid water,  214 , which could be fed into either the bubbling bed  207  or freeboard zone  208 , or a combination of these methods. 
         [0070]    Referring to  FIG. 3A , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  300 . In some implementations, system  300  may include feed ports for streams  301 ,  302 , and  305  fluidly coupled to the main system  300 , and a discharge port for stream  304  fluidly coupled to the main system  300 . In some aspects a gas distribution plate  306  may be fluidly coupled to the main vessel body of system  300 . In some aspects system  300  may include a cyclone  311  fluidly coupled to feed ports for stream  309  and discharge ports for streams  312 ,  310 . In some aspects the cyclone discharge port for stream  312  is fluidly coupled back to the main body of system  300 , and may include a non-mechanical valve and feed port on the main body for recirculation of stream  315  back into the main body and a discharge port for stream  316 . In some aspects system  300  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0071]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 3A , gaseous stream  302  including one or more fluidization gases is provided to the hydrator system  300  through the bottom entry zone  313 , also known as the plenum chamber, which is below the fluidization distribution plate  306 . Gaseous stream  302  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  301  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  306  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  300  and as such it remains in the bubbling bed zone  307 , unless discharged as stream  304 . Stream  301  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  305  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  306 . Stream  305  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  306  is designed to prevent backflow of any solids into the fluidization gas entry zone  313 . Solid material  305 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  307  and transported through the reactor freeboard zone  308 . The resulting mixed stream of fluidization gases and solids is mixed-stream  309 , and after leaving the reactor freeboard zone  308 , the stream  309  is sent to a cyclone  311 , to separate the solids  312 , from the gases  310 . The fluidization gas  302 , is blown into the fluidization gas entry zone,  313 , of the fluidized bed reactor,  300 . This fluidizing gas  302 , could be partially recycled from the gas stream  310  leaving the cyclone  311 . A portion of the solid stream  312  leaving the cyclone  311  is recycled back into system  300  as stream  315 . If additional residence time is required for the solids being discharged from the cyclone  311 , these solids can be fully or partially re-introduced back into the fluidization vessel of system  300 , via stream  315 , for example, in a similar fashion to that of a circulating fluidized bed reactor. In some aspects, stream  315  can be re-introduced into the fluidization vessel of system  300  by means of a non-mechanical valve. Some examples of non-mechanical valves are L-valves, J-valves, V-valves, loop seals, seal pots, reverse seals and the like. Stream  316  can be used to withdraw a portion of the circulating solid material from system  300 . 
         [0072]    Referring to  FIG. 3B , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  300 . In some implementations, system  300  may include feed ports for streams  301 ,  302 , and  305  fluidly coupled to the main system  300 , and a discharge port for stream  304  fluidly coupled to the main system  300 . In some aspects a gas distribution plate  306  may be fluidly coupled to the main vessel body of system  300 . In some aspects system  300  may include a cyclone  311  fluidly coupled to feed ports for stream  309  and discharge ports for streams  312 ,  310 . In some aspects the cyclone discharge port for stream  312  is fluidly coupled back to the main body of system  300 , and may include a non-mechanical valve such as a loop seal  317  fluidly coupled to a feed port on the main body for recirculation of stream  315  back into the main body and a discharge port for stream  316 . In some aspects system  300  may include a control system  999  coupled to the components (illustrated or otherwise). In some aspects the loop seal  317  is fluidly coupled to a distribution plate  319  and feed port for stream  318 . 
         [0073]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 3A , gaseous stream  302  including one or more fluidization gases is provided to the hydrator system  300  through the bottom entry zone  313 , also known as the plenum chamber, which is below the fluidization distribution plate  306 . Gaseous stream  302  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  301  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  306  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  300  and as such it remains in the bubbling bed zone  307 , unless discharged as stream  304 . Stream  301  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  305  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  306 . Stream  305  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  306  is designed to prevent backflow of any solids into the fluidization gas entry zone  313 . Solid material  305 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  307  and transported through the reactor freeboard zone  308 . The resulting mixed stream of fluidization gases and solids is mixed-stream  309 , and after leaving the reactor freeboard zone  308 , the stream  309  is sent to a cyclone  311 , to separate the solids  312 , from the gases  310 . The fluidization gas  302 , is blown into the fluidization gas entry zone,  313 , of the fluidized bed reactor  300 . This fluidizing gas  302 , could be partially recycled from the gas stream  310  leaving the cyclone  311 . 
         [0074]    A portion of the solid stream  312  leaving the cyclone  311  is recycled back into system  300  as stream  315 . If additional residence time is required for the solids being discharged from the cyclone  311 , these solids can be fully or partially re-introduced back into the fluidization vessel of system  300 , via stream  315 , for example, in a similar fashion to that of a circulating fluidized bed reactor. In some aspects, stream  315  can be re-introduced into the fluidization vessel of system  300  by means of a non-mechanical valve. 
         [0075]    Some examples of non-mechanical valves are L-valves, J-valves, V-valves, loop seals, seal pots, reverse seals and the like. Stream  316  can be used to withdraw a portion of the circulating solid material from system  300 . All components in the system  300  are substantially the same as in the embodiment of the system  300  illustrated in  FIG. 3A , with the exception being that more detail is shown on how the system  300  could be built to accommodate the recirculation of solid stream  312 . In this implementation, solid stream  312  is shown moving down a vertical length of pipe that connects the cyclone  311  back to the main vessel body of system  300 . In some example aspects, this pipe may include a non-mechanical valve, such as a loop seal  317  complete with a gas stream  318  being fed through a distribution plate  319 . In some aspects the distribution plate  319  may instead be nozzles. In some aspects the gas stream  318  may for example include air, steam or the like. Stream  318  provides sufficient backpressure through the loop seal  317  so that fluidizing gases from the main vessel system  300  do not divert backwards through the loop seal  317 . 
         [0076]    Referring to  FIG. 4A , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  400 . In some implementations, system  400  may include feed ports for streams  401 ,  402 , and  405  fluidly coupled to the main system  400 , and a discharge port for stream  404  fluidly coupled to the main system  400 . In some aspects the discharge port  404  is fluidly coupled to a solids classifier unit, for example an external sieve unit  420 . The external sieve unit  420  is fluidly coupled to discharge ports for streams  422  and  421 . In some aspects a gas distribution plate  406  may be fluidly coupled to the main vessel body of system  400 . In some aspects system  400  may include a cyclone  411  fluidly coupled to feed ports for stream  409  and discharge ports for streams  412 ,  410 . In some aspects system  400  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0077]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 4A , gaseous stream  402  including one or more fluidization gases is provided to the hydrator system  400  through the bottom entry zone  413 , also known as the plenum chamber, which is below the fluidization distribution plate  406 . Gaseous stream  402  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  401  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  406  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  400  and as such it remains in the bubbling bed zone  407 , unless discharged as stream  404 . Stream  401  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  405  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  406 . Stream  405  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  406  is designed to prevent backflow of any solids into the fluidization gas entry zone  413 . Solid material  405 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  407  and transported through the reactor freeboard zone  408 . The resulting mixed stream of fluidization gases and solids is mixed-stream  409 , and after leaving the reactor freeboard zone  408 , the stream  409  is sent to a cyclone  411 , to separate the solids  412 , from the gases  410 . The fluidization gas  402 , is blown into the fluidization gas entry zone  413 , of the fluidized bed reactor  400 . This fluidizing gas  402 , could be partially recycled from the gas stream  410  leaving the cyclone  411 . An external sieve unit  420  is used to segregate material withdrawn from the bubbling bed zone  407  based on physical properties, for example particle size. A portion of the material normally fluidized within the turbulent/transport regime may leave with the material in the bubbling bed regime in stream  404 . 
         [0078]    In this implementation, the turbulent or transport regime material can be separated from the bubbling regime material based on the difference in physical properties, using sieve unit  420  such that the smaller material drops through the sieve  420  and leaves as stream  421 , and the larger material remains above the sieve holes and leaves as stream  422 . Stream  421  can be re-introduced into the reactor system  400  for further reaction, or combined with the finished circulating solids stream  412  and sent to downstream processing, for example to cooling and/or lime slurry systems that can be used in carbon dioxide capture facilities such as industrial (point source) facilities and facilities that capture more dilute carbon dioxide sources such as direct air capture facilities, as well as waste water treatment facilities or Kraft caustic recover processes. Stream  422  could also be sent to downstream processing, for example to heat exchangers and fluid bed calciner systems sometimes used in direct air capture facilities. 
         [0079]    In some aspects, stream  421  may include for example calcium oxide and calcium hydroxide particles, and stream  422  may include for example calcium carbonate pellets. 
         [0080]    Referring to  FIG. 4B , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  400 . In some implementations, system  400  may include feed ports for streams  401 ,  402 , and  405  fluidly coupled to the main system  400 , and a discharge port for stream  404  fluidly coupled to the main system  400 . In some aspects the discharge port  404  is fluidly coupled to an internal solids classifier unit  430 , which is internal to system  100 . In some aspects, the internal solids classifier unit  430  can be a cone and cap sloped stripper. In some aspects the internal solids classifier unit  430  is fluidly coupled to a feed port for stream  431  and a discharge port for stream  404 . In some aspects a gas distribution plate  406  may be fluidly coupled to the main vessel body of system  400 . In some aspects system  400  may include a cyclone  411  fluidly coupled to feed ports for stream  409  and discharge ports for streams  412 ,  410 . In some aspects system  400  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0081]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 4B , gaseous stream  402  including one or more fluidization gases is provided to the hydrator system  400  through the bottom entry zone  413 , also known as the plenum chamber, which is below the fluidization distribution plate  406 . Gaseous stream  402  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  401  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  406  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  400  and as such it remains in the bubbling bed zone  407 , unless discharged as stream  404 . Stream  401  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  405  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  406 . Stream  405  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  406  is designed to prevent backflow of any solids into the fluidization gas entry zone  413 . Solid material  405 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  407  and transported through the reactor freeboard zone  408 . The resulting mixed stream of fluidization gases and solids is mixed-stream  409 , and after leaving the reactor freeboard zone  408 , the stream  409  is sent to a cyclone  411 , to separate the solids  412 , from the gases  410 . The fluidization gas  402 , is blown into the fluidization gas entry zone  413 , of the fluidized bed reactor,  400 . This fluidizing gas  402 , could be partially recycled from the gas stream  410  leaving the cyclone  411 . Componentry internal to system  400  is used to segregate material withdrawn from the bubbling bed zone  407  based on physical properties, for example particle size and/or density. 
         [0082]    In this implementation, material is segregated based on physical properties such as size, and/or mass, through use of a baffled channel or annulus solids classifier component  430 . Material from the bubbling bed zone  407  enters this component  430 , and the baffles and upward flowing gases from stream  431  prevent smaller or lighter particles from making it to the bottom discharge section and instead act to push the smaller and/or lighter material back into the main vessel body of system  400 . The larger or heavier material moves down through component  430  to the bottom discharge portion where it can then be discharged as stream  404 . In some aspects, stream  431  includes gases such as air or steam and the like. In some aspects, component  430  may for example be a cone and cap sloped stripper. In other aspects, component  430  could be similar to the mechanisms of discharging spent catalyst material from gas-solid fluidized beds, such as those found in fluidized beds used for catalytic cracking of hydrocarbons. In catalytic cracking fluidized beds, the spent catalyst solids are discharged, for example, from a fluidized bubbling (non-circulating) bed via a baffled annulus such that larger catalyst moves downward and out into a discharge channel, and finer material and gases move upward back into fluidization vessel. 
         [0083]    Referring to  FIG. 5A , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  500 . In some implementations, system  500  may include feed ports for streams  501 ,  502 , and  505  and fluidly coupled to the main system  500 , and a discharge port for stream  504  fluidly coupled to the main system  500 . In some aspects a gas distribution plate  506  may be fluidly coupled to the main vessel body of system  500 . In some aspects system  500  may include a cyclone  511  fluidly coupled to feed ports for stream  509  and discharge ports for streams  512 ,  510 . In some aspects system  500  may include heat tubing componentry  544  fluidly coupled to system  500 , including a feed port for stream  549  and a discharge port for stream  550  fluidly coupled to the heat tubing componentry  544 . In some aspects system  500  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0084]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 5A , gaseous stream  502  including one or more fluidization gases is provided to the hydrator system  500  through the bottom entry zone  513 , also known as the plenum chamber, which is below the fluidization distribution plate  506 . Gaseous stream  502  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  501  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  506  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  500  and as such it remains in the bubbling bed zone  507 , unless discharged as stream  504 . Stream  501  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  505  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  506 . Stream  505  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  506  is designed to prevent backflow of any solids into the fluidization gas entry zone  513 . Solid material  505 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  507  and transported through the reactor freeboard zone  508 . The resulting mixed stream of fluidization gases and solids is mixed-stream  509 , and after leaving the reactor freeboard zone  508 , the stream  509  is sent to a cyclone  511 , to separate the solids  512 , from the gases  510 . The fluidization gas  502 , is blown into the fluidization gas entry zone  513 , of the fluidized bed reactor  500 . This fluidizing gas  502 , could be partially recycled from the gas stream  510  leaving the cyclone  511 . heating tube componentry  544 , has been added to the vessel walls of system  500  in the bubbling bed zone  507 . 
         [0085]    In this implementation, any portions of either the sensible heat or heat from the hydrating reaction, which is not consumed to heat the pellets and supply the enthalpy to bring the pellets to the operating temperature of the fluid bed, is used instead to make saturated steam for subsequent superheat and power generation. In this implementation, The high temperature hydrator system  500  is built with heat tubing componentry  544  which lines the inner wall of the unit, within the bubbling bed zone  507 . During operation of system  500 , a stream  549  which could be for example, boiler feed water another appropriate heat exchange fluid, or another process fluid stream, is fed into the tube componentry  544 , where the heat from the fluidized bed zone  507  moves through the tubes and into the contents of stream  549  as they move through the tubes. In some aspects, stream  549  is boiler feed water and this indirect heating converts the boiler feed water into saturated steam that leaves the tube componentry as stream  550 . In some aspects, the saturated steam from these tubes is sent as stream  550  to downstream heat consumers or power producers, for example other process heat exchangers or a steam superheater unit and/or steam turbine. 
         [0086]    Referring to  FIG. 5B , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  500 . In some implementations, system  500  may include feed ports for streams  501 ,  502 , and  505  and fluidly coupled to the main system  500 , and a discharge port for stream  504  fluidly coupled to the main system  500 . In some aspects a gas distribution plate  506  may be fluidly coupled to the main vessel body of system  500 . In some aspects system  500  may include a cyclone  511  fluidly coupled to feed ports for stream  509  and discharge ports for streams  512 ,  510 . In some aspects system  500  may include heat tubing componentry  554  fluidly coupled to system  500 , including a feed port for stream  555  and a discharge port for stream  556  fluidly coupled to the heat tubing componentry  554 . In some aspects system  500  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0087]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 5B , gaseous stream  502  including one or more fluidization gases is provided to the hydrator system  500  through the bottom entry zone  513 , also known as the plenum chamber, which is below the fluidization distribution plate  506 . Gaseous stream  502  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  501  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  506  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  500  and as such it remains in the bubbling bed zone  507 , unless discharged as stream  504 . Stream  501  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  505  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  506 . Stream  505  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  506  is designed to prevent backflow of any solids into the fluidization gas entry zone  513 . Solid material  505 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  507  and transported through the reactor freeboard zone  508 . The resulting mixed stream of fluidization gases and solids is mixed-stream  509 , and after leaving the reactor freeboard zone  508 , the stream  509  is sent to a cyclone  511 , to separate the solids  512 , from the gases  510 . The fluidization gas  502 , is blown into the fluidization gas entry zone  513 , of the fluidized bed reactor  500 . This fluidizing gas  502 , could be partially recycled from the gas stream  510  leaving the cyclone  511 . The heat tube componentry  554  is positioned away from the vessel wall of system  500 , and instead is protruding across a substantial portion of the cross section of the bubbling bed zone  507 . In this implementation, any portions of either the sensible heat or heat from the hydrating reaction, which is not consumed to heat the pellets and supply the enthalpy to bring the pellets to the operating temperature of the fluid bed, is used instead to make saturated steam for subsequent superheat and power generation. In this implementation, The high temperature hydrator system  500  is built with heat tubing componentry  554  which protrudes across a substantial portion of the cross section of the bubbling bed zone  507 . During operation of system  500 , a stream  555  which could be for example, boiler feed water another appropriate heat exchange fluid, or another process fluid stream, is fed into the tube componentry  554 , where the heat from the fluidized bed zone  507  moves through the tubes and into the contents of stream  555  as they move through the tubes. In some aspects, stream  555  is boiler feed water and this indirect heating converts the boiler feed water into saturated steam that leaves the tube componentry as stream  556 . In some aspects, the saturated steam from these tubes is sent as stream  556  to downstream heat consumers or power producers, for example other process heat exchangers or a steam superheater unit and/or steam turbine. 
         [0088]    Referring to  FIG. 6 , calcium oxide conversion to calcium hydroxide in the presence of a fluid bed is described with respect to illustrative system  600 . In some implementations, system  600  may include feed ports for streams  601 ,  602 , and  605  and fluidly coupled to the main system  600 , and a discharge port for stream  604  fluidly coupled to the main system  600 . In some aspects a gas distribution plate  606  may be fluidly coupled to the main vessel body of system  600 . In some aspects system  600  may include a cyclone  611  fluidly coupled to feed ports for stream  609  and discharge ports for streams  612 ,  610 . In some aspects system  600  may be fluidly coupled to an external fluidized bed system  660 , including discharge ports fluidly coupled to the external fluidized bed system  660  for streams  621 ,  665  and feed ports for stream  620  and  663 . In some aspects system  600  may be fluidly coupled to a feed port for stream  665 . In some aspects, the external fluidized bed system  660  may be fluidly coupled to heat tubing componentry  668  and system  660  and heat tubing componentry  668  may also be fluidly coupled to a feed port for stream  661  and a discharge port for stream  664 . In some aspects system  600  may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0089]    In some implementations, fluidization gases include, for example, air, steam, and the like. As depicted in  FIG. 6 , gaseous stream  602  including one or more fluidization gases is provided to the hydrator system  600  through the bottom entry zone  613 , also known as the plenum chamber, which is below the fluidization distribution plate  606 . Gaseous stream  602  may be, for example, air, steam or a combination of these gases and their sub-components. Stream  601  is one of the solid feedstocks, which enters the system above the fluidization distribution plate  606  and becomes fluidized in the bed or bubbling bed regimes within the fluidized bed system  600  and as such it remains in the bubbling bed zone  607 , unless discharged as stream  604 . Stream  201  may, for example, consist mostly of calcium carbonate or calcium oxide, and may also consist in part of aqueous solutions such as liquid water. Stream  605  is the solid feedstock which becomes fluidized in the turbulent or transport fluidization regime and it also enters the system above the distribution plate  606 . Stream  605  may, for example, consist mostly of calcium oxide or calcium carbonate and may also consist in part of liquid or gaseous water. The distribution plate  606  is designed to prevent backflow of any solids into the fluidization gas entry zone  613 . Solid material  605 , any associated reaction products and any steam generated from liquid water content present in the system are carried out of the bubbling bed  607  and transported through the reactor freeboard zone  608 . The resulting mixed stream of fluidization gases and solids is mixed-stream  609 , and after leaving the reactor freeboard zone  608 , the stream  609  is sent to a cyclone  611 , to separate the solids  612 , from the gases  610 . The fluidization gas  602 , is blown into the fluidization gas entry zone  613 , of the fluidized bed reactor  600 . This fluidizing gas  602 , could be partially recycled from the gas stream  610  leaving the cyclone  611 . An indirectly heated external fluidized bed system  660  is connected to system  600  such that material from the bubbling bed  607  can be discharged to the external fluidized bed system  660  and after being processed in  660 , the material can be sent back to system  600 . The separate fluidized bed vessel  660  may include componentry such as heat tubing  668 , heat exchange medium entering the heat tubing  668  as stream  661  and leaving as stream  664 , a densely fluidized bed  667 , and a fluidization gas stream  663 . 
         [0090]    In some implementations, system  660  is operated under significantly higher density bed conditions so that heat tubing  668  can be densely packed within the vessel  660  and come in close contact with the fluidized pellet bed  667 . 
         [0091]    In some implementations, the pellets from the bubbling bed zone  607  of the main high temperature hydrator vessel  600  may be moved back and forth between vessel  660  and vessel  600  in order to exchange heat from vessel  600  to vessel  660  and its componentry, for example the heat tubing system  668 . 
         [0092]    In some implementations, steam generation may be split between the high temperature hydrator system  600  and the external dense fluidized bed vessel  660 . In this implementation, a portion of the discharged stream  604  would feed into system  660  as stream  620 . Both boiler feed water heating and steam generation could occur within the tubing  668 , and the resultant cooled pellet material is transferred back to system  600  via stream  665 . In some aspects, the heat exchange occurring within system  660  is such that stream  665  is cooled to below 300° C. and is recycled to the bubbling bed zone  607 . In some aspects, sending the cooler stream  665  back to system  600  allows for control of temperature within system  600 . 
         [0093]    In some aspects, there is another portion of stream  604  that does not feed into system  660 , but instead leaves as stream  621 . This stream  621  could be sent to downstream processing, for example to a fluidized calciner unit as part of a direct air capture system. 
         [0094]    In some implementations, system  600  might be configured such that it produces a low bed-side heat transfer film coefficient. This, combined with heat transfer surface mechanical limitations, for example, a low heat tube surface area to bed surface area ratio, might not allow for full heat extraction from the bubbling bed zone  607  in system  600 . 
         [0095]    In some aspects heat coils are used inside system  600 , where the heat coils are as illustrated in  FIGS. 5A and 5B . In some of these cases, the fluid in the streams feeding the heat coils is boiler feed water and the temperature of the boiler feed water, may not provide enough of a differential temperature drive to overcome the above mentioned mechanical surface area limitations (that result in a low approach temperature requirement). In these cases, the use of an external densely fluidized bed system such as  660  as illustrated in  FIG. 6 , would utilize a lower fluidization velocity (resulting in a denser bubbling bed, for example) in comparison to the bubbling bed in system  600 , and as such should have both a higher surface area ratio and bed-side coefficient to overcome the low boiler feed water approach temperature requirements. 
         [0096]      FIG. 7  illustrates how a high temperature hydrator may, for example, be connected to other processes such as a direct air capture process. In some implementations, the direct air capture (DAC) process is configured to capture dilute concentrations of carbon dioxide from the atmosphere and produce a concentrated liquid or gaseous stream of carbon dioxide which can be utilized in applications such as Enhanced Oil Recovery (EOR), as feedstock for the production of synthetic hydrocarbons. In some cases, the concentrated liquid or gaseous carbon dioxide can instead be sequestered in a subsurface saline aquifer, reservoirs or aging oil fields as part of the previously mentioned EOR process. In some cases, the concentrated liquid or gaseous stream of carbon dioxide may instead be combined with other chemical feedstock, for example hydrogen, and further processed into a synthetic hydrocarbon such as diesel, gasoline and waxes. 
         [0097]    In some implementations, the DAC process operates as a continuous, closed-loop system that inputs water, energy and small material make-up streams, and delivers highly concentrated, pressurized carbon dioxide. 
         [0098]    Some examples of major process equipment involved in an implementation of this type of direct air capture commercial process include air contactors, fluidized bed reactive crystallizers also known as pellet reactors, oxy-fired circulating fluidized bed calciners, and some types of lime slakers or hydrators. Auxiliary equipment also involved in this type of direct air capture process may include, for example, compressors, turbines, boilers, heat exchangers, steam systems and oxygen production units such as Air Separation Units (ASU) or a variety of water electrolyzer units. 
         [0099]    In some implementations, the DAC process draws air through an air contactor, where it contacts a strong aqueous hydroxide solution, such as potassium hydroxide (KOH). The carbon dioxide in the air reacts with the potassium hydroxide to form a solution of potassium carbonate (K 2 CO 3 ) and water, absorbing about three-quarters of the available carbon dioxide. 
         [0100]    In some implementations, the DAC process potassium carbonate solution is transferred to a fluidize bed reactive crystallizer or pellet reactor. In some aspects the fluidized bed reactive crystallizer or pellet reactor is a liquid-solid fluidized bed, where the potassium carbonate solution can contact calcium hydroxide (Ca(OH) 2 ), also known as hydrated lime, and precipitate calcium carbonate pellets through a process known as causticization. 
         [0101]    In some implementations, the DAC process calcium carbonate pellets from the fluidized bed reactive crystallizer pass through a slaker to absorb heat before being fed into a circulating fluidized bed calciner, which is essentially a type of high-temperature kiln or furnace. The heat releases the carbon dioxide as a highly concentrated, gaseous stream, leaving calcium oxide (CaO) as by-product, through a process known as calcination. In some aspects, heat for the calciner is provided by combusting natural gas with oxygen (known as “oxy-firing”), so that the combustion exhaust may contain mostly carbon dioxide with some water, and can be combined with the carbon dioxide stream leaving the calciner. In some aspects the oxygen used for oxy-firing is separated from air using an air separator. 
         [0102]    In some implementations of the DAC process, the calcium oxide is fed into the slaker, where it may combine with steam to regenerate hydrated lime, which can then be fed into the fluidized bed reactive crystallizer or pellet reactor for reuse. In some aspects, the slaker may be configured as a high temperature hydrator. 
         [0103]    In some implementations, at least a portion of the electrical power for the DAC process derives from on-site generation. In some aspects, the on-site power generation uses natural gas as fuel, or from external, grid-supplied renewable electricity sources. In some aspects, some of the DAC process electrical power is generated on-site using waste or excess steam, for example from the calciner or high temperature hydrator. 
         [0104]      FIG. 7  does not show all the major equipment involved in a direct air capture process, rather, it illustrates one embodiment of how the key interfaces, for example heat and material stream exchanges, could be set up between a high temperature hydrator system and the immediate upstream and downstream process and heat exchange equipment of a direct air capture process. In the implementation illustrated in  FIG. 7 , calcium carbonate pellets, which may have been processed upstream to remove process solution, are fed, slightly wet, via stream  700  to the high temperature hydrator unit  740 . In some aspects the direct air capture process may include a control system  999  coupled to the components (illustrated or otherwise). 
         [0105]    The wet calcium carbonate pellets in stream  700 , and hot calcium oxide (quicklime) in stream  710  that originated from the calciner system  800 , are both fed into the high temperature hydrator unit  740  and mixed. The high temperature hydrator  740  is fluidized by recirculating steam, as stream  705 . In some aspects, a portion of the steam stream  705  takes part in the slaking reaction that converts the feed stream of calcium oxide material in stream  710  into calcium hydroxide material. 
         [0106]    The calcium carbonate pellets in stream  700  that are fed into the high temperature hydrator unit  740  do not participate in the slaking reaction; instead, they are dried and heated using the process heat within the high temperature hydrator unit  740 . The calcium oxide in stream  710  is delivered at a temperature of approximately 694° C. The calcium oxide stream  710  may include, for example, approximately 94.5% reactive calcium oxide, 3.4% unreactive calcium oxide, and 2.1% impurities. 
         [0107]    A stream of mostly preheated and dried pellets are drawn out of the bubbling bed zone of the high temperature hydrator unit  740  and sent as stream  708  to the solid sieve unit  760  to separate the solids into a stream of larger pellets, stream  719 , and any smaller particles, such as calcium oxide and calcium hydroxide, as stream  709 . The larger solids in stream  719  can be fed to the calciner preheat cyclone system  790  at an approximate temperature of 300° C. 
         [0108]    The calcium hydroxide solid particles can be separated from the calcium carbonate pellets due to a substantial size difference between the small, micron sized calcium hydroxide particles and the larger, millimeter sized calcium carbonate pellets. The calcium hydroxide will therefore pass through the solid sieve unit  760 , which may for example have a mesh with 0.8 mm diameter holes, while the pellets, being larger, will not pass through the holes in the mesh and will instead move along the top of the mesh and out a separate exit. Any unreacted calcium oxide present in the feed stream to the solid sieve unit  760  will, depending on size, either recycle back to the calciner unit  800  with stream  719  or continue onto the cooler unit  750  in stream  711 , where it has another opportunity to react with water, in a hydration reaction, to form calcium hydroxide. 
         [0109]    After passing through the high temperature hydrator unit  740 , the steam stream  701  may be further cleaned of solids using for example a cyclone unit  765  and a baghouse unit  770 , then recirculated back to the inlet gas distributor, or “windbox,” of the high temperature hydrator unit  740  using a high temperature blower  820 . 
         [0110]    Any solid material that passes the primary cyclone of the high temperature hydrator unit  740  will be fine particles that may be captured further downstream by a cyclone unit  765 , leaving this unit as stream  706  or even further downstream in a baghouse unit  770 , leaving this unit as stream  707 . 
         [0111]    In some implementations, a portion of the calcium carbonate pellets may be small enough to transport along with the circulating material and as such, wind up in any one or a combination of streams  706 ,  707 , and  709 . Depending on the amount of calcium carbonate pellet material present in these streams, this may introduce a form of dead load propagating forward into downstream processes within the system. This dead load can be mitigated by including, for example, one or more hot sieve screens to process at least a portion of one or both of streams  706  and  707  to capture the calcium carbonate material and direct it over to the calciner system  800 . 
         [0112]    In some implementations, all three streams  706 ,  707 , and  709 , could be combined into stream  711  and sent to a cooler unit  750 , where they are cooled using water from streams  715  and  718 . In some aspects, cooling unit  750  is built with a cooled screw, where stream  718  is boiler feed water from a steam condenser unit  745  that flows through an internal cavity in the screw, allowing for indirect cooling of the contents of the cooling unit  750 . This screw may mix stream  711  with a water stream  715 . In some aspects, stream  711  may include for example unreacted calcium oxide, which as a result of mixing in cooling unit  750  with stream  715 , could react via the hydrating reaction to produce calcium hydroxide. In some aspects, unit  750  also allows some heat from stream  711  and some heat resulting from any hydrating reaction to transfer indirectly to the boiler feed water stream  718 , providing a further preheated stream  712  of boiler feed water that can then be sent to the high temperature hydrator unit  740  for conversion into saturated steam stream  703 . 
         [0113]    In some implementations, the cooler unit  750  carries out two functions: a) it cools exiting stream  716  to below 100° C. so that it can be safely mixed with water in mixing tank  755  to form the required Ca(OH) 2  slurry and b) it provides for a small amount of water (stream  715 ) to be sprayed onto the solid Ca(OH) 2  to complete the remaining slaking reaction. 
         [0114]    In some implementations, after leaving the cooler unit  750 , the Ca(OH) 2  stream  716  is sent to the mixing tank  755 , where it is formed into a slurry mix using a water source (stream  714 ). This slurry mix could be, for example, diluted with water to a slurry having a consistency of between 20 wt % to 40 wt % solids. In some aspects, the water source may be for example potable, non-potable, process water knocked out from on-site compressor units, recovered from washing systems or other process units. 
         [0115]    In some implementations, the cooled Ca(OH) 2  that is now retained within unit  755  can be sent further downstream to other processes that require the use of hydrated lime in either solid Ca(OH) 2  form or a wetter slurry form. Examples of some types of downstream processes that may be fed from stream  717  include the pellet reactor units found within some types of carbon dioxide capture processes such as direct air capture, water treatment facilities, and caustic recovery units within the Kraft pulp and paper process. 
         [0116]    In some implementations, the heat generated in the high temperature hydrator  740  may not be fully consumed in the process of drying and preheating the pellets. The excess heat could be used to generate steam, which could then be use for example for other process heat requirements or for power production via stream  703 , which in the implementation shown in  FIG. 7 , feeds into a steam superheater unit  785 . In other aspects, the excess heat from the high temperature hydrator  740  could be removed from unit  740  by means of direct exchange with internal fluids within unit  740  that then leave the unit and are fed through downstream heat exchangers (not shown). In other aspects, the excess heat from the high temperature hydrator unit  740  could be removed by means of indirect exchange with heating tubes or coils located either within the vessel walls of  740  as shown in  FIG. 7 , or for example by heat tubes or coils located further into the bubbling bed zone of unit  740  as illustrated in  FIG. 5B , or via a separate external fluidizing vessel as illustrated in  FIG. 6 . 
         [0117]    In some aspects, the oxy-fired calciner  800  is a circulating fluidized bed, which is fluidized with a flow of pure oxygen shown in the process flow diagram of  FIG. 7  as stream  723 . 
         [0118]    The calciner  800  is used to decompose the calcium carbonate (CaCO 3 ) pellets from stream  719  into calcium oxide (CaO) and carbon dioxide at a temperature of approximately 900° C. High temperature is required to drive the endothermic calcination reaction to the desired 98% conversion of calcium carbonate to calcium oxide. 
         [0119]    The hot pellets from the high temperature hydrator  740  are sent to the calcination system via stream  719  by way of two consecutive cyclone preheat stages ( 790  followed by  795 ) to raise the temperature of the pellets further before entering the calciner unit  800  via stream  721 . 
         [0120]    Hot gas from the calciner unit  800  output stream  725  (primarily carbon dioxide), is fed to preheating cyclone stage  795  at approximately 900° C., and then via stream  726  to preheat cyclone stage  790  at approximately 650° C. The gas stream  727  is then extracted from the calciner unit  800  and may be sent through coolers such as unit  785  before being sent to clean-up units such as  775  and compression unit  815 . 
         [0121]    The gas leaving the calciner  800  in stream  727  contains all the carbon dioxide from the calcination of the pellets. In some implementations where for example natural gas combustion is used as the heat to drive the endothermic calcination reaction, stream  727  would also contain the carbon dioxide from the combustion of natural gas. In some aspects, the composition of this gas stream  727  is 82.8 wt % CO 2 , 14.6 wt % H 2 O, 1.13 wt % O 2 , and 1.43 wt % N 2 . 
         [0122]    In some aspects, a small amount of the calciner  800  off-gas (primarily carbon dioxide) is re-circulated back into the system through stream  734  after passing the last cooling unit  785 , but before the water vapor has been removed. This stream can be used as a supply for various minor fluid bed requirements such as instrument purges, and to aid the circulation of the solids from the primary cyclone  795  back into the main calciner bed. This can be done with air but recycled carbon dioxide is used in this implementation instead to prevent dilution of the calciner off-gases with nitrogen. 
         [0123]    The stream  739  of remaining hot solid reaction product leaving calciner unit  800 —which includes for example mostly quicklime or calcium oxide (CaO)—may be used to preheat the incoming oxygen feed stream  722  via a heat exchange unit  805  before being sent to downstream cooling and/or processing units. This solid calcium oxide product from the calcination reaction is shown as stream  739  in  FIG. 7 . In some implementations, the very hot material in stream  739  may be close-coupled to the high temperature hydrator unit  740  to avoid an expensive transport device. This may also require, for example, a grade level high temperature hydrator pellet screen with a vertical 300° C. pellet pneumatic transport to carry the pellet feed (stream  719 ) to the calciner pre-heat cyclone  790 . In some aspects it is desirable to minimize, for example, capital expense and operational difficulties of this configuration; in this case, a portion of the supplemental (in addition to feed pellet water) reactive steam (stream  729 ), could be diverted as a slipstream and used for the pneumatic transport of stream  719  to the pre-heat cyclone  790 , before being returned to the recirculation stream  704  (not shown). 
         [0124]    In some aspects, unit  805  could be a bubbling fluidized bed. In some aspects where unit  805  is a bubbling fluidized bed, the hot calcium oxide in stream  739  from the calciner unit  800  is fluidized by the oxygen stream  722 , which could transfer heat directly from the calcium oxide stream  739  to the oxygen stream  722 . This could raise the temperature of the oxygen stream  722  from ambient to approximately 700° C. in stream  723 . In some aspects this bubbling fluid bed  805  may be refractory lined, suitable for service with high temperature oxygen, and completely gas-tight to prevent release of oxygen from the system. 
         [0125]    In some aspects, the heat for the calciner unit  800  is supplied by combustion of natural gas fed from stream  724 . 
         [0126]    The heat for the calcination endothermic reaction could be provided from a variety of sources, depending on the economics and resources associated with the location of a particular commercial plant. In an example aspect, the heat source is electric. In another example aspect, the heat source is combustion of a hydrocarbon such as natural gas. In another example aspect, the heat source is solar or solar thermal. In another example aspect, the heat source is combustion of biomass. In yet another example aspect the heat source is combustion of hydrogen. 
         [0127]    Oxygen for the calciner unit  800  is provided via stream  722 . In some aspects, the oxygen stream  722  is supplied by an air separation unit (ASU) which may for example operate at a pressure of approximately 20 kPa g . In other aspects the oxygen source for stream  722  may be a by-product of water electrolysis. 
         [0128]    In some implementations, the high temperature hydrator unit  740  may be built as a refractory lined circulating fluidized bed, or CFB. In some aspects, the fluidization velocity in the high temperature hydrator is chosen such that the calcium carbonate pellets remain as a fluidized bed in the bottom of the device while smaller calcium oxide particles recirculate through the primary cyclone and loop seal that are shown as being integral to unit  740  in  FIG. 7  and which are called out in more detail in  FIG. 3B . As the calcium oxide particles are transported around the high temperature hydrator  740 , they may react with the steam and slake to form Ca(OH) 2  and, as a result of this reaction, heat may be released. The sensible heat of the circulating calcium oxide material, fluidization gases, and the heat from the hydrating reaction contribute to heating the calcium carbonate pellets in the bubbling bed zone up to 300° C. The heated and dried pellets ( 708 ) are drawn out of the bubbling zone of the high temperature hydrator unit  740  and sent to downstream processes. Any fine material which passes the primary cyclone of the high temperature hydrator unit  740  may be, for example, Ca(OH) 2  and could be captured by the cyclone ( 765 ) and/or baghouse ( 770 ) units. These units may be used If the downstream high temperature fluidization fan ( 820 ) is not able to withstand the small amount of solids in the recirculating steam stream  704 . All three streams of hydrated lime ( 706 ,  707 ,  709 ) may be combined as stream  711  and sent to another unit in the process, for example a cooling unit  750  as illustrated in  FIG. 7 . 
         [0129]    In one aspect, heat generated in the high temperature hydrator unit  740  shown in  FIG. 7  may not be fully consumed in drying and preheating the calcium carbonate pellets; in this case, the excess or waste heat could be used to generate steam for other heat or power requirements. One example of how this could be done is illustrated in  FIG. 7 , where superheated steam stream  703  is produced indirectly by flowing boiler feedwater as part of stream  712  through a set of heating coils imbedded in the high temperature hydrator unit  740 . This steam leaves the high temperature hydrator  740  as stream  703 , is sent to a steam superheater unit  785  where it is further heated and then used to feed a steam turbine  780 . 
         [0130]    In another implementation, the high temperature hydrator unit  740  as illustrated in  FIG. 7  may be operated such that the fluidization velocity within this unit  740  is set as high as possible while keeping the calcium carbonate pellets in a bubbling fluidized bed mode. In an example aspect, this fluidization velocity is set to 0.75 m/s. At This velocity, the calcium oxide will be elutriated out of the bed, captured by the primary cyclone and re-introduced back into the bed via the recirculation leg. In some aspects this recirculation leg may be as shown in  FIG. 4B  and may include for example a loop seal. In this implementation the calcium oxide material could behave as a circulating fluid bed while the calcium carbonate pellets behave as a back mixed bubbling fluid bed. There is a recirculating flow of steam, stream  705 , which is used to fluidize the bed. Upon leaving the high temperature hydrator unit  740 , the steam stream  701  goes through a dust collection system, which may include for example a baghouse unit  770  and/or cyclone unit  765  to remove any calcium oxide and calcium hydroxide particles from the steam stream before being sent to a high temperature fan  820  which then boosts the stream pressure for reintroduction into the fluidized bed. 
         [0131]    In some implementations, in addition to any water carried into the high temperature hydrator unit  740  along with the pellet stream  700 , some additional steam is necessary to convert 85% of the quicklime to hydrated lime via the hydrating reaction, 
         [0000]      CaO (s) +H 2 O (g) →Ca(OH) 2(s) +105.2 kJ
 
         [0132]    In some aspects of this implementation, the additional steam can be provided by pulling a low pressure steam stream  729  off of a turbine  780  (as shown in  FIG. 7 ) and injecting this stream  729  into the fluidizing steam flow after it has passed through the high temperature baghouse unit  770 . In some other aspects, the additional water needed to complete the above hydrating reaction could be directly injected into streams  704  or  705  as liquid water (not shown). 
         [0133]    The choice between feeding water into the recirculating steam loop and using low pressure steam from the steam turbine  780  is determined by the economic trade-off between the additional energy generated by having the extra steam flow through the steam turbine  780 , and the additional capital and operating costs of generating extra boiler feed water and processing the extra steam. 
         [0134]    A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims. Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only. It is to be understood that the forms shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described herein without departing from the spirit and scope as described in the following claims.