Patent Publication Number: US-2016236149-A1

Title: High-efficiency catalytic converters for treating exhaust gases

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     The present application is a continuation application of U.S. patent application Ser. No. 14/287,867, filed May 27, 2014, which is a continuation of U.S. patent application Ser. No. 13/664,290, filed Oct. 30, 2012, now U.S. Pat. No. 8,765,084, which is a continuation of U.S. patent application Ser. No. 13/250,304, filed Sep. 30, 2011, now U.S. Pat. No. 8,298,504, which is a continuation application of U.S. patent application Ser. No. 12/888,983, filed Sep. 23, 2010, now U.S. Pat. No. 8,034,310, which is a continuation application of U.S. patent application Ser. No. 12/344,413, filed Dec. 26, 2008, now U.S. Pat. No. 7,807,120, which claims the benefit of U.S. Provisional Application No. 61/017,138, filed Dec. 27, 2007, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The technical field is related to catalytic converters for treating exhaust gases, such as exhaust gases from internal combustion engines, power generators (e.g., coal or fossil fuels), and other sources of exhaust gases. 
     BACKGROUND 
     Catalytic converters have been used to reduce emissions in exhaust gases of internal combustion engines for many years. For example, catalytic converters have been required for use in gas powered cars to remove hydrocarbons, nitrogen oxide, carbon monoxide, and other contaminants from exhaust gases. Catalytic converters have also been developed to provide auxiliary heat to the passenger compartments of hybrid cars. A typical catalytic converter includes a catalytic element, such as a catalytic core, contained in a housing. The catalytic element can be a monolithic catalyst with an open-pore structure having irregular and inter-connected flow paths for the exhaust gases, such as porous metal or ceramic materials, networks, or fiber structures. Other catalytic elements can have a honeycomb structure with regular flow channels through which the exhaust gases flow. The catalyst can be platinum, ruthenium, or another suitable catalyst that removes the undesirable elements from the exhaust gases. In general, the catalysts require a minimum temperature to react with the emissions, and higher reaction temperatures enhance the removal of emissions from the exhaust gases. Several conventional catalytic converters are relatively inefficient because the temperature at the center of the core is often much higher than at the periphery. As a result, the peripheral portions of the catalytic element typically have a lower reaction rate and lower efficiency that reduces the overall efficiency of the catalytic converter. 
     Although catalytic converters have been required in cars for many years, they have not been required in marine vessels with inboard or stern drive engines. However, in 2009, catalytic converters will also be required in new marine vessels with inboard or stern drive engines. This requirement is challenging because it has been difficult to maintain a sufficiently cooled exterior temperature for marine applications while also maintaining a sufficiently high temperature in the peripheral regions of the core to remove enough emissions to meet the standards of the Environmental Protection Agency (EPA). The core temperature of conventional catalytic converters is typically 1,000-1,400° F. In automobile applications the exterior surfaces of the catalytic converters are air cooled and have temperatures of about 600-1,000° F. Such high exterior temperatures significantly exceed the 200° F. exterior temperature limit set by the United States Coast Guard in its regulations for marine vessels. Catalytic converters for marine vessels are accordingly water cooled to reduce the exterior temperatures to within acceptable limits. Water cooling the exterior of the catalytic converters, however, further reduces the temperatures of the peripheral regions of the catalytic cores. Water cooled catalytic converters accordingly often have much lower efficiencies that result in higher hydrocarbon, nitrogen oxide, and carbon monoxide emissions. 
     One proposed solution for marine catalytic converters has a core contained in a housing, a solid insulating blanket of asbestos or other solid material around the core, and a water jacket around the insulating blanket. To offset the heat loss at the periphery of the core, marine catalytic converters may use more efficient and more expensive ruthenium catalytic elements. Although this solution is an improvement, it is still less efficient than catalytic converters for automobiles that use less expensive platinum catalytic cores. Moreover, although ruthenium or other core materials can be used to increase the efficiency, marine catalytic converters still may not meet the standards of the EPA. 
     Additionally, even though current catalytic converters reduce the emissions from cars and other sources, the sheer number of vehicles in operation have greatly contributed to the amount of hydrocarbons, nitrogen oxide, and carbon monoxide in the atmosphere. According to many studies and models, the rapidly increasing levels of hydrocarbons, nitrogen oxide, and carbon monoxide emissions are contributing to an unprecedented rate of global warming that will likely have many repercussions. The rapid increase in the average temperatures being reported have led many scientists to predict disastrous consequences unless emissions are reduced significantly. Therefore, providing a high-efficiency catalytic converter that removes more emissions from exhaust gases will protect the environment and mitigate the potential consequences of global warming. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a high-efficiency catalytic converter in accordance with an embodiment of the disclosure. 
         FIG. 2  is a schematic view of a catalytic converter in accordance with another embodiment of the disclosure. 
         FIG. 3  is a schematic view of a catalytic converter in accordance with yet another embodiment of the disclosure. 
         FIG. 4  is a schematic view of a catalytic converter in accordance with still another embodiment of the disclosure. 
         FIG. 5  is a cross-sectional view of a catalytic converter in accordance with another embodiment of the disclosure. 
         FIG. 6  is a cross-sectional view of a catalytic converter in accordance with yet another embodiment of the disclosure. 
         FIG. 7  is a cross-sectional view of an alternative embodiment of the catalytic converter of  FIG. 6  in accordance with another embodiment of the disclosure. 
         FIG. 8  is a schematic diagram of a gas treatment system having a catalytic converter in accordance with another embodiment of the disclosure. 
         FIGS. 9A-B  are schematic diagrams of power generating systems having a catalytic converter in accordance with embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     A. Overview 
     The following disclosure describes several embodiments of catalytic converters in the context of marine vessels for use with inboard or stern drive internal combustion engines. For example, the described embodiments of the catalytic converters are well suited for use in pleasure craft (e.g., ski-boats, yachts, fishing boats, etc.) and personal water crafts (e.g., “jet-skis” and “water bikes”). Although the embodiments of catalytic converters described below are well suited for marine vessels, they can also be used in industrial, automotive, or other applications in which it is desirable to remove emissions from exhaust gases. Several embodiments of the catalytic converter may accordingly be used to remove hydrocarbons, nitrogen oxide, carbon monoxide, and other emissions from coal fired generators, other types of internal combustion engines used in marine or other applications, or other applications that can benefit from highly efficient removal of emissions from gases. Additionally, several other embodiments of the catalytic converter can have different configurations, components, or procedures than those described in this section. A person of ordinary skill in the art, therefore, will accordingly understand that the catalytic converter and associated gas treatment and/or power generating systems may have other embodiments with additional elements, or the invention may have other embodiments without several of the features shown and described below with reference to  FIGS. 1-9B . 
     One embodiment of a catalytic converter for treating a flow of exhaust gas comprises a reaction chamber, a heating enclosure enclosing at least a portion of the reaction chamber, and an optional coolant channel encasing the heating enclosure. The reaction chamber can have a first end section through which the exhaust gas flows into the reaction chamber and a second end section from which the exhaust gas exits the reaction chamber. The heating enclosure is configured to contain heated gas along the exterior of the reaction chamber, and the optional coolant channel is configured to contain a flow of coolant around the heating enclosure. The catalytic converter can further include a catalytic element in the reaction chamber. 
     Another embodiment of a catalytic converter for treating a flow of exhaust gas comprises a reaction chamber having an inlet section and an outlet section configured such that a primary flow of the exhaust gas passes through the reaction chamber from the inlet section to the outlet section. The catalytic converter further includes a plenum surrounding the reaction chamber, a first passageway between the reaction chamber and the plenum at the outlet section, and a second passageway between the reaction chamber and the plenum at the inlet section. A portion of the primary flow of the exhaust gas passes through the plenum from the first port to the second port to generate a counter-flow of heated gas through the plenum. The catalytic converter can further include an optional coolant channel surrounding the plenum, and a catalytic core in the reaction chamber. 
     A method for reducing emissions from a flow of exhaust gas in accordance with one embodiment comprises passing a primary flow of exhaust gas in a first direction through a catalytic core in a reaction chamber and passing a secondary flow of exhaust gas through a heating enclosure around the reaction chamber. The method can further include passing a flow of cooling fluid through a coolant channel surrounding the heating enclosure. Several specific examples of the foregoing embodiments of catalytic converters, gas treatment systems, power generation systems, and associated methods for reducing emissions and/or generating power from a flow of exhaust gas are described below with reference to  FIGS. 1-9B . 
     B. Description of Specific Embodiments of Catalytic Converters 
       FIG. 1  is a schematic illustration of a high-efficiency catalytic converter  100  that is well suited for applications that require limited external temperatures and/or higher efficiencies. In this embodiment, the catalytic converter  100  includes a reaction chamber  110 , a heating enclosure  120  enclosing at least a portion of the reaction chamber  110 , and a cooling channel  130  encasing at least a portion of the heating enclosure  120 . The reaction chamber  110  has a first end section  112  through which a primary flow F p  of exhaust gas flows into the reaction chamber  110  and a second end section  114  from which the primary flow F p  of exhaust gas exits the reaction chamber  110 . The first end section  112  can accordingly be an inlet section, and the second end section  114  can be an outlet section. The heating enclosure  120  can be a plenum configured to contain a flow of heated gas F h  along the exterior of the reaction chamber  110 , and the coolant channel  130  can be a cooling jacket configured to contain a coolant flow F c  around the heating enclosure  120 . In the embodiment illustrated in  FIG. 1 , the heating enclosure  120  is an interior annular plenum concentrically adjacent to a medial section of the reaction chamber  110 , and the coolant channel  130  is an outer annular jacket concentrically adjacent to the heating enclosure  120 . The catalytic converter  100  further includes a catalytic element  140  in the reaction chamber  110 . Suitable catalytic elements  140  include an open-pore matrix, such as porous metals or ceramics, networks, or fiber structures, and a catalyst, such as platinum, ruthenium, or other suitable catalysts depending upon the type of exhaust gas. The catalytic element  140  can alternatively be a honeycomb matrix or other matrix structures with the desired catalyst(s). The reaction chamber  110 , heating enclosure  120 , and cooling channel  130  operate together to enhance the efficiency of the catalytic element  140  while also providing a much lower temperature at the exterior of the catalytic converter. 
     In this embodiment, the reaction chamber  110  further includes one or more first ports  115  toward the outlet section  114  and one or more second ports  116  toward the inlet section  112 . The first ports  115  and the second ports  116  can operate together to generate a counter-flow F h  of high temperature exhaust gas through the heating enclosure  120 . The heated flow F h  enters the heating enclosure  120  through the first ports  115  and exits from the heating enclosure  120  through the second ports  116  so that a recirculation flow F r  enters back into the primary flow F p  of exhaust gas. The counter-flow F h  through the heating enclosure  120  is extremely hot because it enters the heating chamber  120  after it has been processed by the catalytic element  140 . More specifically, the thermal reaction of the catalytic process heats the primary flow F p  of exhaust gases from an inlet temperature T i  of about 300-600° F. to an outlet temperature T o  of about 1,000-1,400° F. As a result, the heated flow F h  provides an extremely hot barrier with a low thermal conductivity between the catalytic element  140  in the reaction chamber  110  and the coolant flow F c  in the coolant channel  130 . The heated flow F h  actively heats the exterior of the reaction chamber and accordingly mitigates heat loss from the reaction chamber  110  such that the peripheral regions of the catalytic element  140  also have a very high temperature that is near the central core temperature. In contrast to conventional water-cooled catalytic converters that do not actively heat the exterior of the reaction chamber, the catalytic converter  100  is highly efficient and removes a very significant percentage of carbon monoxide, nitrogen oxide, hydrocarbons and/or other undesirable constituents from the primary flow F p  of exhaust gas. 
     The coolant channel  130  contains a sufficient flow of coolant, such as water or another suitable fluid, to cool an exterior surface  150  around the heating enclosure  120  and/or the end sections of the reaction chamber  110 . When the catalytic converter  100  is used in marine applications for inboard or stern drive vessels, the coolant flow F c  can be a flow of raw water from the body of water supporting the vessel or a closed-loop system incorporating a heat exchanger. The coolant flow F c  removes the heat radially outwardly from the heating enclosure  120  such that the exterior surface  150  is within a suitable operating range for the particular application. In the case of marine vessels, the coolant flow F c  is sufficient such that the temperature of the exterior surface  150  is less than 200° F., and generally less than about 160° F., during normal operation. For example, a specific prototype of the catalytic converter  100  tested in 45-60° F. ambient water has an exterior surface temperature of 80-120° F. and a core temperature in the catalytic element  140  of about 1,100-1,400° F. 
       FIG. 2  is a schematic view of a catalytic converter  200  in accordance with another embodiment of the disclosure. Like reference symbols refer to like components in  FIGS. 1 and 2 . In this embodiment, the reaction chamber  110  of the catalytic converter  200  includes one or more ports  201  through which the exhaust gases flow both in and out of the heating enclosure  120 . The ports  201  can have a scoop  202  that directs an in-flow F i  from the primary flow F p  into the heating enclosure  120 . An outflow F o  from the heating enclosure also occurs through the port  201 . More specifically, when the pressure in the heating enclosure  120  exceeds the pressure at the ports  201 , the outflow F o  will pass through the ports  201 . The catalytic converter  200  is similar to the catalytic converter  100 , but the catalytic converter  200  does not produce the same counter flow through the heating enclosure  120 . 
       FIG. 3  is a schematic view of a catalytic converter  300  in accordance with yet another embodiment of the disclosure, and like reference symbols refer to like components in  FIGS. 1-3 . The catalytic converter  300  has a heating channel or enclosure  320  that is completely distinct from the reaction chamber  110 . In this embodiment, the heated flow F h  can comprise exhaust gases removed from the primary flow F p  upstream from the catalytic converter  300  and then reintroduced to the primary flow F p  downstream from the catalytic converter  300 . As such, the heated flow F h  through the heating enclosure  320  is not processed through the catalytic element  140 . The heated flow F h  in the catalytic converter  300 , therefore, is not as hot as the heated flow F h  in the catalytic converter  100 . In another example of this embodiment, the heated flow F h  can be raw air that is passed over the exterior of the exhaust manifold, the exterior of the exhaust pipe, or other heated portions of the engine to reach a reasonably high temperature that still mitigates heat transfer away from the reaction chamber  110 . 
       FIG. 4  is a schematic view of a catalytic converter  400  in accordance with another embodiment of the disclosure, and like reference numbers refer to like components throughout  FIGS. 1-4 . In this embodiment, the catalytic converter  400  includes a reaction chamber  410  having a closed end  412  and a plurality of outlet ports  414 . The catalytic converter  400  further includes a heating enclosure  420  around the reaction chamber  410  that includes a plurality of outlets  422 , and a catalytic element  440  in the reaction chamber  410 . In this embodiment, the catalytic element  440  has a matrix  442  that carries the catalyst and a central bore  444  through the matrix  442 . The coolant channel  130  surrounds the heating enclosure  420  as explained above. In operation, the primary flow F p  flows in through the central bore  444  and then through the matrix  442  of the catalytic element  440 . The primary flow F p  exits the reaction chamber  410  through the outlets  414  such that the heated flow F h  in the heating enclosure  420  is the treated portion of the primary flow F p  exiting the reaction chamber  410 . The primary flow F p  then exits the heating enclosure  420  through the outlet ports  422  and is directed out of the vessel. The catalytic converter  400  accordingly uses the catalytic element  440  to heat the exhaust gas in the heating enclosure  420 . 
       FIG. 5  is a cross-sectional view of a catalytic converter  500  in accordance with another embodiment of the disclosure. In this embodiment, the catalytic converter  500  includes a reaction chamber  510 , a heating enclosure  520  around at least a portion of the reaction chamber  510 , and a coolant channel  530  around the heating enclosure  520  and portions of the reaction chamber  510 . The heating enclosure  520  is a plenum, and the coolant channel  530  is a jacket for containing a flow of coolant (e.g., water or another suitable liquid). In this embodiment, the catalytic element  540  has a matrix and a suitable catalyst as explained above. 
     The reaction chamber  510  includes a first end section  511 , a second end section  512 , and a central conduit  513  between the first end section  511  and the second end section  512  in which the catalytic element  540  is positioned. The first end section  511  includes a main inlet  514  through which the primary flow F p  of exhaust gas enters the reaction chamber  510 . The first end section  511  further includes a diverging wall  515  that has an increasing cross-sectional dimension from the end of the main inlet  514  to the central conduit  513 . The second end section  512  has a main outlet  516  through which the primary flow F p  of exhaust gas exits the reaction chamber  510 . The second end section  512  further includes a converging wall  517  with a decreasing cross-sectional dimension in a direction away from the central conduit  513  toward the main outlet  516 . As explained below, the configuration of the diverging wall  515  and converging wall  517  contribute to generating a consistent heated counter-flow F h  through the heating enclosure  520 . For example, without being bound by theory, the diverging wall  515  is believed to contribute to creating an expansion zone upstream from the catalytic element  540 , and the converging wall  517  is believed to contribute to creating a high pressure zone downstream from the catalytic element  540 . 
     The heating enclosure  520  has an inner housing  522  with a first portion  523  attached to the first end section  511  of the reaction chamber  510 , a second portion  524  attached to the second end section  512  of the reaction chamber  510 , and a medial portion  525  between the first portion  523  and the second portion  524 . The medial portion  525  is spaced outwardly apart from the central conduit  513  of the reaction chamber  510  such that the heating enclosure  520  comprises an enclosed space between the inner housing  522  and the combination of exterior surfaces of the diverging wall  515 , central conduit  513  and converging wall  517 . The catalytic converter  500  in this embodiment also includes a plurality of first ports  541  through the converging wall  517  and a plurality of second ports  542  through the diverging wall  515 . The first ports  541  and the second ports  542  can further include flaps  543  that extend into the heating enclosure  520 . 
     The reaction chamber  510 , the heating enclosure  520 , and the catalytic element  540  operate together to generate a consistent counter flow of hot gases around the exterior of the central conduit  513  of the reaction chamber  510  to mitigate heat losses that would otherwise reduce the efficiency of the catalytic element  540 . More specifically, the converging wall  517  and the flaps cause a portion of the exhaust gases from the primary flow F p  to flow through the first ports  541  and into the heating enclosure  520 . Conversely, the diverging wall  515  upstream from the catalytic element  540  and the flaps cause the gases to flow out of the heating enclosure  520  such that a heated counter-flow F h  flows through the heating enclosure  520  in a direction opposite that of the primary flow F p  through the reaction chamber  510 . The heated counter-flow F h  is particularly advantageous because the catalytic element  540  heats the exhaust gases from a temperature of approximately 300-600° F. at the first end section  511  to approximately 1,000-1,400° F. at the second end section  512 . As a result, the gases entering the heating enclosure  520  are near the temperature of the catalytic element  540  itself. This high temperature gas flow through the heating enclosure  520  accordingly mitigates heat losses at the periphery of the catalytic element  540  so that the temperature gradient from the center of the catalytic element  540  to its periphery is relatively low. Additionally, because the heated counter-flow F h  of gasses through the heating enclosure  520  is introduced as a recirculation flow F r  upstream from the catalytic element  540 , this portion of the exhaust gasses is reprocessed through the catalytic element  540  to further reduce the level of emissions in the primary flow F p  that exits through the main outlet  516  of second end section  512 . 
     The coolant channel  530  can include an outer housing  532  spaced apart from an exterior surface of the inner housing  522  and a flow channel  533  defined, at least in part, by the space between the inner housing  522  and the outer housing  532 . In this embodiment, the outer housing  532  has a first end  534  with an inlet  535  and a second end  536  with an inlet  537 . The first end  534  can surround a portion of the first end section  511  of the reaction chamber  510  upstream from the first portion  523  of the heating enclosure  520 , and the second end  536  can surround a portion of the second end section  512  of the reaction chamber  510  downstream from the second portion  524  of the heating enclosure  520 . This configuration of the coolant channel  530  accordingly cools the catalytic converter  500  both upstream and downstream from the very hot heating enclosure  520  to ensure that the exterior temperature of the catalytic converter  500  is low enough for marine applications. In other applications, however, it may not be necessary to have a low exterior temperature such that the coolant channel  530  does not necessarily need to extend over the reaction chamber  510  outside of the heating enclosure  520 . 
     The flow channel  533  can further include a flow guide  538  that guides and/or divides the flow through the flow channel  533  to distribute the cooling fluid around the heating enclosure  520 . In this embodiment, the flow guide  538  is a continuous, helical wall between the inner housing  522  and the outer housing  532  that creates a helical channel along the exterior surface of the heating enclosure  520 . The coolant flow F c  accordingly enters the inlet  535  and flows helically around the exterior of the heating enclosure  520  until it exits the coolant channel  530  at the outlet  537 . The flow guide  538  is configured to distribute the coolant flow F c  around the exterior surface of the heating enclosure  520  so that air pockets are less likely to form in the coolant channel  530  and/or the flow over the heating enclosure  520  is generally consistent. The flow guide  538  accordingly reduces the temperature gradients from one portion of the heating enclosure  520  to another. The flow guide  538  is optional depending upon the particular application. Additionally, in other embodiments, the flow guide  538  can be a plurality of individual walls extending lengthwise longditunally along the length, or at least a portion of the length, of the flow channel  533 . 
       FIG. 6  is a schematic view of a catalytic converter  600  in accordance with another embodiment of the disclosure, and  FIG. 7  is a schematic view of an alternative arrangement of the catalytic converter  600  in  FIG. 6 . Like reference symbols refer to like components in  FIGS. 5-7 . In this embodiment, the reaction chamber  510  of the catalytic converter  600  can include features generally similar to the catalytic converter  500  shown in  FIG. 5 . However, as shown in  FIG. 6 , instead of having the first ports  541  through the converging wall  517  and a plurality of second ports  542  through the diverging wall  515 , the catalytic converter  600  includes a first collar  602   a  having the first ports  541  and a second collar  602   b  having the second ports  542 . The first and second collars  602   a  and  602   b  can carry the flaps  543  of the first and the second ports  541  and  542 , respectively. The first and second collars  602   a  and  602   b  can have a generally ring shape, a rectangular shape, and/or other suitable shapes. 
     Even though the catalytic converter  600  is shown in  FIG. 6  as having the flaps  543  of the first ports  541  generally aligned with those of the second ports  542 , in other embodiments, the flaps  543  of the first ports  541  and those of the second ports  542  may be offset from one another. For example, as shown in  FIG. 7 , the flaps  543  of the first ports  541  can be offset from those of the second ports  542  by about 90°. In other examples, the flaps  543  of the first ports  541  can be offset from those of the second ports  542  by about 10°, 20°, 30°, 45°, and/or other suitable offset angles. The offset flaps  543  of the first and second ports  541  and  542  may help to reduce bypass of the heated counter-flow F h  of gasses through the heating enclosure  520  and the recirculation flow F r  through the reaction chamber  510 . 
     In  FIGS. 6 and 7 , several embodiments of the catalytic converter  600  are shown to have the first and second collars  602   a  and  602   b . In other embodiments, one of the first and second collars  602   a  and  602   b  may be omitted. In further embodiments, the catalytic converter  600  may include at least one of the first and second collars  602   a  and  602   b  that individually having a single flap  543 , three flaps  543 , or any other desired number of flaps  543 . In yet further embodiments, at least one of the first and second collars  602   a  may include a flap (not shown) with a completely circular opening. 
       FIG. 8  is a schematic diagram of a gas treatment system  800  in accordance with another embodiment of the disclosure. As shown in  FIG. 8 , the gas treatment system  800  can include a catalytic converter  801  coupled to a flow restrictor  802  downstream from the catalytic converter  801 . The catalytic converter  801  can include a reaction chamber  803  carrying a catalytic element  805  and a cooling channel  804  surrounding the reaction chamber  803 . The cooling channel  804  can have a coolant inlet  835  and a coolant outlet  837 . In certain embodiments, the catalytic converter  801  can be generally similar in structure and function as several embodiments of the catalytic converter described above with reference to  FIGS. 1-7 . In other embodiments, the catalytic converter  801  can also have other configurations and/or features. For example, the catalytic converter  801  can be generally similar to the catalytic converter  100  in  FIG. 1  except the catalytic converter  800  does not include the heating enclosure  120 . 
     In the illustrated embodiment, the flow restrictor  802  includes a check valve in fluid communication with the coolant outlet  837  of the cooling channel  804 . In other embodiments, the flow restrictor  802  can also include an orifice, a venturi, a nozzle, and/or other types of flow element suitable for at least reducing a coolant flow from the catalytic converter  801  or increasing a pressure drop of the coolant flowing through the cooling channel  804 . 
     Several embodiments of the gas treatment system  800  can at least reduce the risk of overheating the catalytic converter  801  when a supply pressure of the coolant is insufficient. For example, in certain embodiments, the gas treatment system  800  may be used in a marine vessel that has an on-board water supply. When in water, the on-board water supply can provide sufficient pressure to force water through the cooling channel  804  of the catalytic converter  801 . When the marine vessel is on land (e.g., towed on a trailer), the water in the catalytic converter  801  tends to drain out from the cooling channel  804  via the coolant outlet  837 . Without the water, the catalytic element  805  may overheat and fail because the catalytic reaction may still be active due to residual gases in the reaction chamber  803  and/or the thermal inertia of the catalytic element  805 . Accordingly, by incorporating the flow restrictor  802 , at least some water would remain when the marine vessel is out of the water to at least reduce the risk of overheating the catalytic converter  801 . 
     Even though the coolant outlet  837  is shown in  FIG. 8  is at a bottom portion of the catalytic converter  801 , in other embodiments, the coolant outlet  837  may be at a top portion of the catalytic converter  801 , as shown in phantom lines in  FIG. 8 . In further embodiment, the catalytic converter  801  may include both a first coolant outlet (not shown) at a top portion and a second coolant outlet (not shown) at a bottom portion of the catalytic converter  801 . At least one flow restrictor  802  may be in fluid communication with the first and second coolant outlets. 
       FIGS. 9A-B  are schematic diagrams of a power generating system  900  in accordance with embodiments of the disclosure. As shown in  FIG. 9A , the power generating system  900  can include an engine  901 , a catalytic converter  902 , a steam turbine  911 , and an optional heat exchanger  914  interconnected with one another. The engine  901  can include a gasoline engine, a diesel engine, a gas turbine, and/or other gas-burning equipment. Alternatively, as shown in  FIG. 9B , the power generating system  900  can include an industrial gas source  903  (e.g., a power plant, a synthetic gas reactor, etc.) instead of the engine  901 . In further embodiments, the power generating system  900  may include a combination of at least one engine  901  and industrial gas source  903 . 
     As shown in  FIG. 9A , the catalytic converter  902  can include a gas inlet  904  coupled to the engine  901  and a gas outlet  906  open to vent. The catalytic converter  902  can also include a fluid inlet  908  and a fluid outlet  910 . The fluid outlet  910  can be coupled to the steam turbine  911 . In certain embodiments, the catalytic converter  902  can be generally similar in structure and function as several embodiments of the catalytic converter described above with reference to  FIGS. 1-7 . In other embodiments, the catalytic converter  902  can also have other configurations and/or features. In the illustrated embodiment, the steam turbine  911  can be coupled to an electrical generator  912 . In other embodiments, the steam turbine  911  can also be coupled to a gas compressor, a pump, a drive shaft, and/or other suitable power equipment. 
     In operation, the engine  901  produces an exhaust gas with impurities (e.g., carbon monoxide, nitrogen oxides, etc.). The catalytic converter  902  receives the exhaust gas and reacts the impurities with air, oxygen, and/or other suitable composition to produce heat. The catalytic converter  902  then receives a fluid (e.g., water) at the fluid inlet  908  and raises the energy content of the fluid with the produced heat from reacting the impurities. In the illustrated embodiment, the catalytic converter  902  converts the received fluid (e.g., water) into steam and supplies the steam to the steam turbine  911 , which drives the electrical generator  912  for producing electricity. The optional heat exchanger  914  can then condense and/or cool the steam and/or condensate from the steam turbine  911 . The condensate may be returned to the catalytic converter  902 , discharged to drain, and/or otherwise disposed of. 
     A specific embodiment of the catalytic converter  500  was tested in an in-board marine vessel using a raw water flow through the coolant channel  530 . The raw water had a temperature of approximately 45-60° F. The catalytic element  540  exhibited a small temperature drop from the center of the core to the peripheral regions such that the temperature of the core from the center to the perimeter was approximately 1100-1400° F. at operating speeds. The temperature at the exterior surface of the coolant channel  530 , however, was generally in the range of 70-120° F., and generally less than 100° F. even at high operating speeds. The catalytic converter removed a significant percentage of hydrocarbons (HC), nitrogen oxides (NOx), and carbon monoxide (CO). The extremely low emissions from the catalytic converter  500  were a significant improvement over conventional water cooled catalytic converters and an even more surprising improvement over existing air-cooled catalytic converters used in cars. More specifically, the emissions tests for an embodiment of the catalytic converter  500  used on a Ramjet EFI, 6.3 L, 530 hp engine, are set forth in Table 1 below. 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 2600 rpm 
                   
               
               
                   
                 Stabilized readings 
               
               
                   
                 Stabilized Velocity (GPS) 26 mph 
                 Units 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 HC 
                 34 
                 ppm 
               
               
                   
                 CO 
                 0.01 
                 % 
               
               
                   
                 CO2 
                 13.7 
                 % 
               
               
                   
                   
               
            
           
         
       
     
     The catalytic converter  500  also provided significant noise abatement compared to systems without the catalytic converter. Without being bound by a theory, the heating enclosure  520  and coolant channel  530  appear to significantly dissipate acoustic energy in a manner that reduces the decibel level of the primary flow of F p  of exhaust downstream from the catalytic converter  500 . As a result, the catalytic converter  500  is further useful in marine applications and other applications in which noise pollution is a factor. 
     A specific embodiment of the catalytic converter  500  was further tested in an in-board marine vessel using a raw water flow through the coolant channel  530  under various engine conditions. An atmospheric analyzer provided by Speedtech (Model No. SM-28) was used to measure wind speed (both high and low), relative humidity, air temperature, and barometric pressure, as listed below: 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Wind Speed - high 
                 0 
                 mph 
               
               
                   
                 Wind Speed - low 
                 0 
                 mph 
               
               
                   
                 Relative Humidity 
                 63 
                 % 
               
               
                   
                 Air Temp 
                 44 
                 ° F. 
               
               
                   
                 Barometric Pressure 
                 1024 
                 mbar 
               
               
                   
                   
               
            
           
         
       
     
     A gas analyzer provided by Snap-On Equipment of Conway, Ark. (Model No. EEEA305A) was used to measure hydrocarbon (HC), carbon dioxide (CO 2 ), carbon monoxide (CO), oxygen (O 2 ), nitrogen oxides (NO x ), and air-to-fuel ratio (NF). A GPS meter provided by II Morrow (Model No. 430-0265-41) was used to measure a speed in miles per hour (MPH) of the marine vessel. The collected data are presented in the tables below. 
     
       
         
           
               
               
               
               
               
               
             
               
                   
               
               
                 RPM 
                 650 Neutral 
                 650 Load 
                 1000 Load 
                 1500 Load 
                 2000 Load 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 HC ppm 
                 91 
                 30 
                 11 
                 14 
                 15 
               
               
                 CO 2  % 
                 14.36 
                 14.52 
                 14.42 
                 14.78 
                 14.84 
               
               
                 O 2  % 
                 0.17 
                 0.04 
                 0 
                 0.03 
                 0.01 
               
               
                 CO % 
                 0.055 
                 0.02 
                 0.197 
                 0.255 
                 0.132 
               
               
                 A/F 
                 15.33 
                 15.3 
                 15.2 
                 15.2 
                 15.24 
               
               
                 NO x  ppm 
                 11 
                 22 
                 15 
                 17 
                 31 
               
               
                 MPH 
                 0 
                 7 
                 8 
                 13 
                 24 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
               
               
               
             
               
                   
               
               
                 RPM 
                 2500 Load 
                 3000 Load 
                 3500 Load 
                 4000 Load 
                 4500 Load 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 HC ppm 
                 23 
                 44 
                 47 
                 82 
                 81 
               
               
                 CO 2  % 
                 14.82 
                 14.52 
                 14.33 
                 13.41 
                 13.11 
               
               
                 O 2  % 
                 0.02 
                 0 
                 0.03 
                 0.02 
                 0.02 
               
               
                 CO % 
                 0.202 
                 0.357 
                 0.698 
                 2.042 
                 2.886 
               
               
                 A/F 
                 15.21 
                 15.12 
                 14.99 
                 14.39 
                 14.07 
               
               
                 NO x  ppm 
                 47 
                 134 
                 138 
                 474 
                 358 
               
               
                 MPH 
                 32 
                 38 
                 43 
                 50 
                 57 
               
               
                   
               
            
           
         
       
     
     From the foregoing, it will be appreciated that specific embodiments of the disclosure have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the disclosure. For example, in certain embodiments, several embodiments of the catalytic reactors shown in  FIGS. 1-7  may not include the cooling channel for automotive and/or other suitable uses. Accordingly, the disclosure is not limited except as by the appended claims.