Abstract:
An air quality control system (AQCS) ( 4 ) useful for processing a gas stream (DG), such as a flue gas stream emitted from a fossil fuel fired boiler ( 2 ), combustion process or the like, for at least partial removal of acidic and like contaminants. The air quality control system ( 4 ) includes a plurality of integrated components ( 12 ) equipped with both a dry scrubber system ( 8 ) and a fabric filter ( 10 ). The air quality control system ( 4 ) such as described possesses increased “turn down” capabilities thus increasing the efficiency thereof.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims benefit under 35 U.S.C. §119(e) of co-pending U.S. Provisional Application Ser. No. 61/158,799, filed on Mar. 10, 2009, the contents of which is incorporated herein in its entirety by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is generally directed to an air quality control system (AQCS) useful for processing a gas stream, such as a flue gas stream emitted from a fossil fuel fired boiler, a combustion process or the like. More particularly, the present invention is directed to an integrated fabric filter module and dry scrubber system for an AQCS with increased “turn down” capabilities useful for processing a gas stream. 
         [0004]    2. Description of the Related Art 
         [0005]    In the treatment of flue gases or gas streams, fabric filters and dry scrubber systems are known. For example, U.S. Pat. No. 7,189,074 invented by Ching Chiu Leung et al., describes a method and process for co-combustion in a waste to energy cement production facility. The described co-combustion process involves:
       1. Cement Process System;   2. Waste Reception/Handling System;   3. Waste Co-combustion System;   4. Dry Scrubbing System;   5. Power Generation System;   6. Secondary Scrubbing System; and   7. Flue Gas and Ash Treatment System.
 
Hence, the process utilizes two scrubbing systems, the second of which includes a baghouse filtration step, i.e., passing flue gasses through bag fabric filters to collect dust/ash. It may be noted that the co-combustion process described above requires a number of systems, each of which being indicative of significant capital, maintenance and operating expenses.
       
 
         [0013]    Likewise, U.S. Pat. No. 7,141,091 invented by Ramsay Chang describes a method and apparatus for removing particulate and vapor phase contaminants from a gas stream. The method removes particulate and vapor phase contaminants from a gas stream by using a scrubber configured to remove an absorbable form of the vapor phase contaminant, wherein the scrubber is located downstream of and is fluidly connected to the particulate collection device. The particulate collection device may include one or more electrostatic precipitators and one or more baghouse filtration systems. It may be noted that the particulate and vapor phase contaminants removal method as described above requires a number of systems, each of which being indicative of significant capital, maintenance and operating expenses. 
         [0014]    While there exist methods and equipment capable of removing both particulate and vapor phase contaminants from a gas stream, there remains a need for an improved method and equipment that enables increased “turn down” when in operation to reduce operation associated costs and to improve efficiency and effectiveness. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention provides an integrated dry scrubber system and fabric filter module. Traditionally, flue gas dry scrubber systems and fabric filter modules are separately sized and arranged. In accordance with the present invention, dry scrubber systems and fabric filter modules are integrated together into a single integrated component. Such integrated components are combined into an arrangement that enables increased “turn down” capabilities, efficiencies and effectiveness when in operation. The benefits of such an arrangement include a smaller overall air quality control system (AQCS) foot print, decreased capital cost, increased reliability, increased operating flexibility, and increased turn down capability without the need for a gas recirculation fan. 
         [0016]    The dry scrubber system portion of the subject integrated component is integrated into the inlet duct of the fabric filter module portion. A plurality of integrated components are then combined to form an AQCS. Dirty flue gas laden with, for example, SO 2 , SO 3 , HCl, HF, particulates and/or like acidic contaminants, enters the AQCS through a single inlet plenum opening and is distributed to the individual integrated components by means of a common inlet plenum. The flue gas from the common inlet plenum enters into the individual integrated components by passing through the individual dry scrubber systems located within the individual inlet ducts of each fabric filter module. As gas passes through the dry scrubber reactor portion of the dry scrubber system, hydrated recycle material and absorption material, typically lime, are dispersed within the dry scrubber reactor. The hydrated recycle/absorption material raises the relative humidity of the flue gas to an optimal level for absorption of the flue gas&#39; acidic vapor phase contaminants by the hydrated recycle/absorption material. Simultaneously, as the hydrated recycle/absorption material reacts with the acidic gases, i.e., SO 2 , HCl, SO 3  and/or HF, the reacted recycle/absorption material is dried by the flue gas to create a dry particulate byproduct. The dry particulate byproduct is then captured within the fabric filter module of the integrated component. The captured dry particulate byproduct is collected and fed to the scrubber mixer where it is combined with water and fresh hydrated absorption material (lime) before being pumped back to the dry scrubber portion of the integrated component. The “cleaned” flue gas leaves the integrated component through a common outlet plenum where it combines with cleaned flue gas leaving the other integrated components before leaving the AQCS through a single outlet plenum opening. 
         [0017]    Like most traditional fabric filters, the present AQCS is sectioned into multiple integrated components. By having multiple integrated components, an operator may isolate one or more individual integrated components for maintenance while keeping the remaining integrated components in operation. Likewise, one or more individual integrated components may undergo “turn down” during periods of low demand/low gas flow/low contaminant output, so as to limit or avoid needless equipment wear, energy consumption and like operation associated costs. The AQCS as described herein may be operated with a turn down to approximately 10 percent of its total capacity. To the contrary, the prior art AQCS described in U.S. Pat. No. 7,141,091 may be operated with a turn down to only approximately 50 percent of its total capacity, based on its traditional system configuration. Traditionally, the dry scrubber portion of an AQCS is a separate independently configured piece of equipment up stream of the fabric filter or filter baghouse. The present integrated component comprising both a dry scrubber system and a fabric filter module, and the arrangement of multiple integrated components in an AQCS as described in greater detail below, combines a plurality of dry scrubbers and fabric filters in a particular orientation to achieve a smaller overall AQCS foot print, decreased capital cost, increased reliability, increased operating flexibility, and increased turn down capability without the need for a gas recirculation fan. 
         [0018]    Traditional AQCSs are constructed by designing, sizing and arranging the dry scrubber systems so as to be independent and apart from the fabric filter modules. The dry scrubber systems and fabric filter modules are typically arranged and designed for positioning in a linear series. By arranging the dry scrubber systems and fabric filter modules in a linear series, it is difficult to add components to the AQCS for increased capacity or improved contaminant absorption/collection due to space limitations. Likewise, AQCS issues such as reliability, maintainability, and turn down are approached and addressed as independent considerations. 
         [0019]    In general, the maintainability/reliability of AQCSs with integrated components are superior to those having dry scrubber systems in a linear series due to the compartmentalization capabilities of the AQCSs&#39; integrated components. A single fabric filter module, may have as few as 4 or as many as 16 or more individual fabric filter compartments. Such compartmentalization within fabric filter modules allows individual fabric filter compartments to be isolated for maintenance while the remaining fabric filter compartments may still be in active service. Accordingly, fabric filter modules have superior maintainability/reliability. Such is likewise true for the subject AQCSs. 
         [0020]    To the contrary, dry scrubber systems are typically sized larger to reduce overall cost at the expense of maintainability, reliability and turn down capabilities. Also, in the traditional AQCS linear series arrangement, increasing the number of parallel dry scrubber systems significantly increases the amount of necessary ductwork and the number of large isolation dampers required, resulting in a much larger footprint for the overall AQCS system. By having fewer, larger dry scrubber systems, the turn down capability of AQCSs that utilize high recirculation of the solid byproduct generated through the dry scrubber reaction process is significantly decreased. Another consideration when working with dry scrubber systems is that stringent flue gas velocity requirements are necessary in order to maintain solids entrainment in the dry scrubber reactors. Accordingly, during periods of low operating loads/low flue gas generation/low contaminant output, large gas recirculation fans are required for each dry scrubber system to maintain solids entrainment during system turn down. Gas recirculation fans significantly increase the auxiliary power demand of the AQCS during such periods of low capacity utilization and are often associated with increased equipment corrosion and increased maintenance costs. 
         [0021]    The present integrated component integrates both a dry scrubber system and fabric filter module into one AQCS component. In doing so, an individual fabric filter module is matched to the capacity of a single dry scrubber reaction vessel. Hence, the two functions, i.e., at least partial vapor phase contaminant removal and at least partial particulate contaminant removal, are thereby combined within a single integrated component. A plurality of such single integrated components may then be arranged much like a conventional compartmentalized fabric filter, as described in more detail below. In general, benefits of such an arrangement include substantial capital cost savings and significantly smaller overall AQCS footprint. More particularly, the amount of structural steel used to support the equipment and to fabricate the system may be reduced and isolation dampers typically measuring approximately 20 feet by 30 feet required to isolate each fabric filter module, now also serve to isolate each dry scrubber reactor vessel. Accordingly, the number of required isolation dampers is cut in half. Likewise, the necessary amount of AQCS inlet/outlet ductwork is significantly reduced as compared to that needed for multiple dry scrubber systems and multiple baghouses arranged in the traditional linear series. 
         [0022]    As an added benefit, the present integrated components also enable relatively easy, rapid and increased AQCS turn down while maintaining adequate flue gas velocity through the operating integrated components during periods of low boiler/source output. The mobile inlet and outlet isolation dampers on individual integrated components may be correspondingly opened, i.e., non-blocking of fluid flow, or closed, i.e., blocking of fluid flow, as needed based on flue gas/contaminant loads from the boiler. Thus, the stringent gas velocity requirements in the operating dry scrubber reaction vessels are maintained. As boiler/source operating load decreases, individual integrated component inlet and outlet isolation dampers are closed to block flue gas flow and the associated dry scrubber system and fabric filter module are thus inactivated or non-operational. For example, if a boiler is operating at full capacity, all AQCS integrated components&#39; mobile isolation dampers are in the open, non-blocking position, except for possibly one integrated component having both its inlet isolation damper and its outlet isolation damper in the closed, blocking position for purposes of maintenance. In this case, all integrated components, except for possibly the one, are active or operating. If a boiler is operating at mid-range capacity, approximately half of the integrated components have both their inlet isolation dampers and their outlet isolation dampers in the closed, blocking position and such integrated components are inactive or non-operational. If a boiler is operating at low capacity, all but only the needed integrated components, possibly only one, have both their inlet isolation dampers and their outlet isolation dampers in the closed, blocking position. In this case, only the needed integrated components, which may possibly be only one integrated component, remain active or operating. The mobile inlet and outlet isolation dampers are used in an opposite manner as boiler/source capacity increases. Hence, as boiler/source capacity increases, additional corresponding mobile inlet and outlet isolation dampers on integrated components are opened and such integrated components are then activated and operating. Through the use of individual integrated components with independently operating mobile inlet and outlet isolation dampers, the need for a gas recirculation fans is eliminated. Additionally, the present AQCS with individual integrated components has similar maintainability and reliability characteristics as the traditional fabric filters or filter baghouses, which are quite good. 
         [0023]    Additional features of the present invention will appear from the following description from which the preferred embodiments are set forth in detail in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a process schematic diagram depicting one embodiment of the present invention; 
           [0025]      FIG. 2  is a top view of one embodiment of the air quality control system of the present invention; and 
           [0026]      FIG. 3  is a side view of the air quality control system of  FIG. 2  taken along line  3 - 3 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0027]    One embodiment, generally depicted in FIGURE ( FIG. 1  as a process schematic diagram, includes a boiler  2 , an air quality control system (AQCS)  4  and an optional tower  6 . It is noted that many additional and varied process steps using additional equipment may be positioned/take place between boiler  2  and AQCS  4 , as is known to those skilled in the art. Likewise, many additional and varied process steps using additional equipment may be positioned/take place following AQCS  4  and prior to environmental release of a “cleaned” flue gas, CG, from optional tower  6 , as is known to those skilled in the art. Such additional process steps and/or equipment are not described in further detail herein for purposes of clarity and simplicity. 
         [0028]    As best illustrated in  FIG. 2 , one embodiment of the present AQCS  4  comprises a plurality of integrated dry scrubber systems  8  and fabric filter modules  10 , referred to hereinafter as integrated components  12 . In general, dry scrubber system  8  comprises lime hydration chamber  14 , dry scrubber mixer  16 , dry scrubber reactor  18  and dry scrubber reaction vessel  20 . Fabric filter module  10  comprises particulate/contaminant chamber  22 , a plurality of fabric filter bags  24 , chamber barrier  26  and particulate/contaminant collection bin  28 . AQCS  4  is configured to include a common inlet plenum  30  with inlet plenum opening  32 . Common inlet plenum  30  is common to and fluidly connected to each integrated component  12 . AQCS  4  is also configured to include a common outlet plenum  34  with outlet plenum opening  36 . Common outlet plenum  34  is common to and fluidly connected to each integrated component  12 . Common inlet plenum  30  and common outlet plenum  34  are preferably aligned substantially parallel to each other with common inlet plenum  30  located along a plane, P 1 , below and parallel plane, P 2 , on which common outlet plenum  34  is located. Inlet plenum opening  32  and outlet plenum opening  36  may both be located on side  4   a  of AQCS  4 , or alternatively may be located on opposed sides  4   a  and  4   b  of AQCS  4 . 
         [0029]    At least two, but more preferably a plurality of integrated components  12  are individually, fluidly attached to common inlet plenum  30  by means of individual inlet plenums  38  each having an inlet opening  40 . As illustrated in  FIG. 2 , a total of ten integrated components  12  ( 12   a,    12   b,    12   c,    12   d,    12   e,    12   f,    12   g,    12   h,    12   i  and  12   j ) are individually, fluidly attached via individual inlet openings  40  ( 40   a,    40   b,    40   c,    40   d,    40   e,    40   f,    40   g,    40   h,    40   i  and  40   j , respectively) to opposed, parallel, elongated sides  42  and  44  of common inlet plenum  30 . More particularly, five integrated components  12  ( 12   a,    12   b,    12   c,    12   d  and  12   e ) are fluidly attached to elongated side  42  of common inlet plenum  30 , while five other integrated components  12  ( 12   f,    12   g,    12   h,    12   i  and  12   j ) are fluidly attached to elongated side  44  of common inlet plenum  30 . Of course, it will be recognized that a greater or a lesser number of integrated components  12  may be fluidly attached to an appropriately sized common inlet plenum  30  and still be within the scope and spirit of the present invention. 
         [0030]    As further illustrated in  FIG. 2 , a total of ten integrated components  12  ( 12   a ,  12   b,    12   c,    12   d,    12   e,    12   f,    12   g,    12   h,    12   i  and  12   j ) are individually, fluidly attached via individual outlet openings  46  ( 46   a,    46   b,    46   c,    46   d,    46   e,    46   f,    46   g,    46   h,    46   i  and  46   j,  respectively) to opposed, parallel, elongated sides  48  and  50  of common outlet plenum  34 . More particularly, five integrated components  12  ( 12   a,    12   b,    12   c,    12   d  and  12   e ) are fluidly attached to elongated side  48  of common outlet plenum  34 , while five other integrated components  12  ( 12   f,    12   g,    12   h,    12   i  and  12   j ) are fluidly attached to elongated side  50  of common outlet plenum  34 . Of course, it will be recognized that a greater or a lesser number of integrated components  12  may be fluidly attached to an appropriately sized common outlet plenum  34  and still be within the scope and spirit of the present invention. 
         [0031]    As best illustrated in  FIG. 2 , integrated components  12  are arranged in pairs on opposed elongated sides  42  and  44  of common inlet plenum  30  and on opposed elongated sides  48  and  50  of common outlet plenum  34 . Hence, integrated components  12   a  and  12   f  are a pair,  12   b  and  12   g  are a pair,  12   c  and  12   h  are a pair,  12   d  and  12   i  are a pair and  12   e  and  12   j  are a pair. As illustrated, multiple pairs of integrated components  12  are arranged side-by-side along appropriately sized common inlet plenum  30  and common outlet plenum  34 . Such an arrangement allows for relative ease in the addition of additional integrated components  12  for purposes of meeting boiler  2  capacity increases and/or increasing AQCS efficiency and/or effectiveness. 
         [0032]    Each inlet opening  40  as described above, is equipped with an individually controlled mobile inlet isolation damper  52 . Likewise, each outlet opening  46  is equipped with an individually controlled mobile outlet isolation damper  54 . The individually controlled inlet isolation dampers  52  and outlet isolation dampers  54  may be individually opened and closed to allow for individual component  12  cleaning/repair, maintenance, turn down and the like as explained in more detail below. 
         [0033]      FIG. 3  illustrates a cross section of the AQCS of  FIG. 2  taken along line  3 - 3 . In plane P 1  denoted by line P 1 -P 1  is common inlet plenum  30 . In plane P 2  denoted by line P 2 -P 2  is common outlet plenum  34 . Common inlet plenum  30  and common outlet plenum  34  are fluidly separated by barrier  56 . Barrier  56  is attached between elongated sides  42  and  44  of common inlet plenum  30  so as to form top side  58  and attached between elongated sides  48  and  50  of common outlet plenum  34  so as to form base side  60 . Spaced apart from and parallel to top side  58  of common inlet plenum  30  is inlet base wall  62 . Inlet base wall  62  is attached between elongated sides  42  and  44  opposite top side  58 . Spaced apart from and parallel to base side  60  of common outlet plenum  34  is outlet top wall  64 . Outlet top wall  64  is attached between elongated sides  48  and  50  opposite base side  60 . 
         [0034]    In elongated sides  42  and  44  of common inlet plenum  30  are inlet openings  40  ( 40   a  and  40   f ) for integrated components  12  ( 12   a  and  12   f,  respectively), as was described in greater detail previously. Inlet openings  40  are fluidly connected to opposed common inlet plenum  30  and fabric filter duct  66 . By means of fabric filter duct  66 , common inlet plenum  30  and dry scrubber system  8  are fluidly connected. Dry scrubber system  8  comprises an absorption material  70   b,  typically lime, supplied within hydration chamber  14 . The hydration chamber  14  is fluidly connected to a solvent or water source (not shown), an absorption material or lime source (not shown) and optionally a recycled material source, i.e., the collection bin  28  of fabric filter module  10 , as described in more detail below. The hydration chamber  14  is fluidly connected to dry scrubber mixer  16 . Fluidly connected to dry scrubber mixer  16  is dry scrubber reactor  18  housed within dry scrubber reaction vessel  20 . Dry scrubber reaction vessel  20  is equipped with scrubber opening  68  to which fabric filter module  10  is fluidly connected. 
         [0035]    Hydration chamber  14  is generally a chamber of any commercially useful configuration. Within hydration chamber  14 , an absorption material  70   a  such as lime from an absorption material source and optionally a recycled material  70   b  such as recycled lime from collection bin  28  are combined to form reaction material  70 . As needed for efficient operation of dry scrubber reactor  18 , reaction material  70  is mechanically and/or gravity fed into dry scrubber mixer  16  via mixer opening  72 . Mixer opening  72  fluidly connects hydration chamber  14  and dry scrubber mixer  16 . Prior to the fed reaction material  70  passing through mixer opening  72  and into dry scrubber mixer  16 , reaction material  70  is sprayed with a predetermined amount of a solvent such as water from a solvent source so as to hydrate reaction material  70 . 
         [0036]    Dry scrubber mixer  16  is generally a mixer of any commercially useful configuration. Within dry scrubber mixer  16 , hydrated reaction material  70  is mixed for approximately 15 to 20 seconds to achieve a moisture content throughout of approximately 5%. Once the reaction material  70  is thoroughly mixed within dry scrubber mixer  16  to achieve the desired moisture content throughout reaction material  70 , reaction material  70  is mechanically and/or gravity fed out of dry scrubber mixer  16  and into dry scrubber reaction vessel  20  through exit opening  74 . Exit opening  74  fluidly connects dry scrubber mixer  16  and dry scrubber reaction vessel  20 . 
         [0037]    As noted previously, dry scrubber reaction vessel  20  houses dry scrubber reactor  18 . Dry scrubber reactor  18  is that portion of dry scrubber reaction vessel  20  where reaction material  70  enters dry scrubber reaction vessel  20  passing through exit opening  74  to be dispersed from dispersal ring or plate  82 . Dispersal ring or plate  82  is located within dry scrubber reactor  18  and disperses reaction material  70  therein by mechanical means (not shown). It is in dry scrubber reactor  18  where reaction material  70  contacts, commingles and reacts with dirty flue gas, DG, laden with, for example, vapor phase SO 2 , SO 3 , HCl and/or HF, particulates and/or like acidic contaminants. Thus, it is within dry scrubber reactor  18  where one or more of the following exemplificative reaction(s) occur to form dry particulates, DP. 
         [0000]      SO 2 : SO 2 +Ca(OH) 2 =CaSO 3 +H 2 O 
         [0000]      SO 3 : SO 3 +Ca(OH) 2 =CaSO 4 +H 2 O 
         [0000]      HCl: 2HCl+Ca(OH) 2 =CaCl 2 +H 2 O 
         [0000]      HF: 2HF+Ca(OH) 2 =CaF 2 +H 2 O 
         [0000]    Such reactions and those like them are known to those skilled in the art. The DG continues through dry scrubber reaction vessel  20  and into fluidly connected fabric filter inlet  76  by means of inlet opening  78 . As DG flows into fabric filter inlet  76 , it carries with it DP and like particulates. From fabric filter inlet  76 , DG flows into the fluidly connected particulate chamber  22 . Within particulate chamber  22 , a plurality of fabric filter bags  24  is supported by chamber barrier  26 . Hence, DG flows into particulate chamber  22 , passes through fabric filter bags  24  whereupon DP and like particulates are blocked by fabric filter bags  24 , thus allowing only “clean” flue gas, CG, to pass beyond chamber barrier  26 . After passing chamber barrier  26 , CG exits fabric filter module  10  by means of outlet opening  46  to enter fluidly connected common outlet plenum  34 . CG passes from each integrated component  12  into fluidly connected common outlet plenum  34  prior to exiting AQCS  4  through single outlet plenum opening  36 . 
         [0038]    DP and like particulates blocked by fabric filter bags  24  fall into or are collected upon fabric filter  24  cleaning in collection bin  28  located beneath fabric filter bags  24  in the bottom of particulate chamber  22 . Collection bin  28  is fluidly connected to hydration chamber  14 . DP and like particulates, i.e., recycled material  70   b,  are mechanically fed and/or gravity fed through exit portal  80  of collection bin  28  and into hydration chamber  14 . Within hydration chamber  14 , recycled material  70   b  from collection bin  28  and absorption material  70   a  are combined to form reaction material  70 , as described above. 
         [0039]    An exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase acidic contaminants and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet opening  40  and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase acidic contaminants within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet opening  46 , into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has a vapor phase contaminant removal efficacy of approximately 99 percent. 
         [0040]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase acidic contaminants and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (nine of the ten inlet isolation dampers  52  open—one closed, e.g.,  52   j ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase acidic contaminants within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (nine of the ten outlet isolation dampers  54  open—one closed, e.g.,  54   j ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 90 percent of full capacity. 
         [0041]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase acidic contaminants and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (four of the ten inlet isolation dampers  52  open—six closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h  and  52   c ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase acidic contaminants within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (four of the ten outlet isolation dampers  54  open—six closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h  and  54   c ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 40 percent of full capacity. 
         [0042]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase acidic contaminants and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (three of the ten inlet isolation dampers  52  open—seven closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c  and  52   g ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase acidic contaminants within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (three of the ten outlet isolation dampers  54  open—seven closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c  and  54   g ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 30 percent of full capacity. 
         [0043]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase acidic contaminants and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (two of the ten inlet isolation dampers  52  open—eight closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c,    52   g  and  52   b ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase acidic contaminants within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (two of the ten outlet isolation dampers  54  open—eight closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c,    54   g  and  54   b ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 20 percent of full capacity. 
         [0044]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase acidic contaminants and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (one of the ten inlet isolation dampers  52  open—nine closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c,    52   g,    52   b  and  52   f ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase acidic contaminants within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (one of the ten outlet isolation dampers  54  open—nine closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c,    54   g,    54   b  and  54   f , into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 10 percent of full capacity. 
         [0045]    An exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2  and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet opening  40  and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2  within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet opening  46 , into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has SO 2  removal efficacy of approximately 99 percent. 
         [0046]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2  and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (nine of the ten inlet isolation dampers  52  open—one closed, e.g.,  52   j ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2  within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (nine of the ten outlet isolation dampers  54  open—one closed, e.g.,  54   j ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 90 percent of full capacity. 
         [0047]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2  and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (four of the ten inlet isolation dampers  52  open—six closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h  and  52   c ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2  within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (four of the ten outlet isolation dampers  54  open—six closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h  and  54   c ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 40 percent of full capacity. 
         [0048]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2  and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (three of the ten inlet isolation dampers  52  open—seven closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c  and  52   g ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2  within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (three of the ten outlet isolation dampers  54  open—seven closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c  and  54   g ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 30 percent of full capacity. 
         [0049]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2  and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (two of the ten inlet isolation dampers  52  open—eight closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c,    52   g  and  52   b ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2  within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (two of the ten outlet isolation dampers  54  open—eight closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c,    54   g  and  54   b ), into common outlet plenum  34   and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 20 percent of full capacity. 
         [0050]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2  and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (one of the ten inlet isolation dampers  52  open—nine closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c,    52   g,    52   b  and  52   f ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2  within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (one of the ten outlet isolation dampers  54  open—nine closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c,    54   g,    54   b  and  54   f ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 10 percent of full capacity. 
         [0051]    An exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet opening  40  and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet opening  46 , into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has SO 2 , SO 3 , HCl and/or HF removal efficacy of approximately 99 percent. 
         [0052]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (nine of the ten inlet isolation dampers  52  open—one closed, e.g.,  52   j ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (nine of the ten outlet isolation dampers  54  open—one closed, e.g.,  54   j ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has a AQCS  4  turn down to approximately 90 percent of full capacity. 
         [0053]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (four of the ten inlet isolation dampers  52  open—six closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h  and  52   c ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (four of the ten outlet isolation dampers  54  open—six closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h  and  54   c ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 40 percent of full capacity. 
         [0054]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (three of the ten inlet isolation dampers  52  open—seven closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c  and  52   g ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (three of the ten outlet isolation dampers  54  open—seven closed, e.g.,  54   j,    54   e,    54   i,    54   d ,  54   h,    54   c  and  54   g ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 30 percent of full capacity. 
         [0055]    Another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (two of the ten inlet isolation dampers  52  open—eight closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c,    52   g  and  52   b ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (two of the ten outlet isolation dampers  54  open—eight closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h ,  54   c,    54   g  and  54   b ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 20 percent of full capacity. 
         [0056]    Still another exemplicative method of using AQCS  4  as described in detail above to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF and to at least partially remove particulate contaminants from DG is now provided. The subject method comprises passing DG through inlet plenum opening  32 , into common inlet plenum  30 , through inlet openings  40  with open, non-blocking inlet isolation dampers  52  (one of the ten inlet isolation dampers  52  open—nine closed, e.g.,  52   j,    52   e,    52   i,    52   d,    52   h,    52   c,    52   g,    52   b  and  52   f ), and into dry scrubber reaction vessel  20 . Within dry scrubber reaction vessel  20 , DG contacts hydrated lime reaction material  70  in dry scrubber reactor  18  and reacts therewith to at least partially remove vapor phase SO 2 , SO 3 , HCl and/or HF within DG prior to passage through inlet opening  78  and fabric filter inlet  76 . DG then passes from fabric filter inlet  76  into particulate chamber  22  to be filtered by fabric filter bags  24  to at least partially remove particulate contaminants within DG prior to flowing beyond chamber barrier  26  as CG. CG then passes through outlet openings  46  with open, non-blocking outlet isolation dampers  54  (one of the ten outlet isolation dampers  54  open—nine closed, e.g.,  54   j,    54   e,    54   i,    54   d,    54   h,    54   c,    54   g,    54   b  and  54   f ), into common outlet plenum  34  and out of AQCS  4  through outlet plenum opening  36 . The subject method has an AQCS  4  turn down to approximately 10 percent of full capacity. 
         [0057]    Various embodiments of the present invention have been described herein. The descriptions are intended to be illustrative of the present invention. It will be apparent to one of skill in the art that modifications may be made to the invention as described without departing from the scope of the claims set forth below. For example, it is to be understood that although some of the embodiments of the present invention have been described in the context of an AQCS of a particular arrangement, it should be appreciated that other arrangements may be used without deviation from the spirit and scope of the claims below.