Patent Publication Number: US-2016237874-A1

Title: Catalyst assembly with sensing adapter system

Description:
BACKGROUND 
     The subject matter disclosed herein relates to reciprocating engines and, more specifically, to aftertreatment systems coupled to reciprocating engines. 
     Engines (e.g., internal combustion engines such as gas engines) combust a mixture of fuel and air to generate combustions gases that apply a driving force to a component of the engine (e.g., to move a piston). Subsequently, the combustion gases exit the engine as an exhaust gas and may be treated in an aftertreatment system. Unfortunately, quality samples representative of the emissions of nitrogen oxides (NO x ), oxygen (O 2 ), and other components in the treated exhaust gases may be difficult to obtain. 
     BRIEF DESCRIPTION 
     Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below. 
     In accordance with a first embodiment, a catalyst assembly configured to mount along an exhaust flow path of a reciprocating combustion engine is provided. The catalyst assembly includes a housing having an inlet portion, an outlet portion, and a central portion disposed between the inlet portion and the outlet portion. The housing is configured to house one or more catalyst elements. The housing includes a flow path through the inlet portion, the central portion, and the outlet portion. The outlet portion has a first end and a second end, the first end being coupled to the central portion, and the outlet portion includes a first annular wall having a first diameter that decreases from the first end to the second end. The catalyst assembly also includes a cylindrical portion coupled to and extending from the second end of the outlet. The catalyst assembly further includes at least one oxygen sensor connection disposed on the cylindrical portion to enable an oxygen sensor coupled to the at least one oxygen sensor connection to be disposed perpendicular to a longitudinal axis of the cylindrical portion. 
     In accordance with a second embodiment, a system includes a cylindrical portion configured to be coupled to a conically-shaped outlet portion of a three-way catalyst assembly along a fluid flow path exiting the conically-shaped outlet portion, such that the cylindrical portion is configured to be coupled to a narrower end of the conically-shaped outlet portion. The system also includes at least one oxygen sensor connection disposed on the cylindrical portion to enable an oxygen sensor coupled to the at least one oxygen sensor connection to be disposed perpendicular to a longitudinal axis of the cylindrical portion. 
     In accordance with a third embodiment, a catalyst assembly configured to mount along an exhaust flow path of a reciprocating combustion engine is provided. The catalyst assembly includes a housing having an inlet portion, an outlet portion, a central portion disposed between the inlet portion and the outlet portion and configured to house one or more catalyst elements. The housing also includes a flow path through the inlet portion, the central portion, and the outlet portion. The outlet portion has a first end and a second end, and the first end is coupled to the central portion, and the outlet portion includes a conical wall having a first diameter that decreases from the first end to the second end. The catalyst assembly also includes a cylindrical portion coupled to and extending from the second end of the outlet. The catalyst assembly further includes at least one oxygen sensor connection disposed on the cylindrical portion to enable an oxygen sensor coupled to the at least one oxygen sensor connection to be disposed perpendicular to a longitudinal axis of the cylindrical portion. The central portion has a cross-sectional area adjacent the first end of the outlet portion, the at least one oxygen sensor has a second diameter, and the ratio of the cross-sectional area to the second diameter is approximately between 16.4:1 m 2 /m to 65.7:1 m 2 /m. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
         FIG. 1  is a block diagram of an embodiment of an engine driven system (e.g., engine driven power generation system) coupled to an aftertreatment system (e.g., catalyst assembly) having a plurality of sensors disposed on a cylindrical portion extending from an end of a catalyst housing outlet; 
         FIG. 2  is a cross-sectional side view of an embodiment of the aftertreatment system of  FIG. 1  having a cylindrical portion extending from an end of a catalyst housing outlet; 
         FIG. 3  is a cross-sectional view of an embodiment of a catalyst assembly having a plurality of sensors within the cylindrical portion, taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of an embodiment of an oxygen sensor connection (e.g., boss) disposed in an annular wall of the cylindrical portion, taken within line  4 - 4  of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of an embodiment of a non-oxygen sensor boss disposed in the annular wall of the cylindrical portion, taken within line  5 - 5  of  FIG. 3 ; and 
         FIG. 6  is a cross-sectional side view of an embodiment a cylindrical portion coupled to an end of an outlet portion of a catalyst assembly. 
     
    
    
     DETAILED DESCRIPTION 
     One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. 
     The present disclosure is directed to systems that enable improved sensor readings of emissions from a catalyst assembly. In particular, embodiments of the present disclosure include a catalyst assembly (e.g., three-way catalyst (TWC)) configured to couple to and receive exhaust from an internal combustion engine (e.g., a reciprocating engine such as a gas engine). The catalyst assembly includes a housing and one or more catalyst elements. The housing of the catalyst assembly includes an inlet portion, an outlet portion, and a central portion disposed between the inlet and outlet portion. A cylindrical portion is coupled to and extends from the outlet portion (e.g., the cylindrical portion and the outlet portion may form a single piece). Alternatively, the cylindrical portion may be a separate piece permanently or removably coupled to the outlet portion. One or more sensors are disposed perpendicular to a longitudinal axis of the cylindrical portion. For example, the sensors may include sensors configured to measure an oxygen concentration or a nitrogen oxide composition or other compositions within a sample (e.g., of exhaust flow or treated exhaust flow). By orienting the sensors perpendicular to the longitudinal axis of the cylindrical portion, more accurate readings of emissions may be gathered due to the turbulent but homogeneous flow at the wall through the cylindrical portion. In other words, the treated exhaust flow experiences turbulent albeit more consistent flow as it flows through cylindrical portion. Absent the cylindrical portion, readings taken from sensors disposed on the conical wall of the catalyst assembly cause the readings to fluctuate or be less accurate largely due to the converging turbulent flows causing voids and non-homogenous flow the sensors experience as the treated exhaust flow flows along the angled or conical wall section of the outlet portion. Accordingly, adding a cylindrical portion enables better quality (e.g., more accurate) measurements of constituents within the flow exiting the catalyst assembly. 
     Turning now to the drawings and referring first to  FIG. 1 , a block diagram of an embodiment of an engine driven system  10  (e.g., engine driven power generation system) coupled to an aftertreatment (e.g., catalyst assembly) having a plurality of sensors disposed on a cylindrical portion extending from an end of a catalyst housing outlet. The engine  14  may include a reciprocating or piston engine (e.g., internal combustion engine). The engine  14  may include a spark-ignition engine or a compression-ignition engine. The engine  14  may include a natural gas engine, gasoline engine, diesel engine, or dual fuel engine. The engine  14  may be a two-stroke engine, three-stroke engine, four-stroke engine, five-stroke engine, or six-stroke engine. The engine  14  may also include any number of cylinders (e.g., 1-24 cylinders or any other number of cylinders) and associated piston and liners. In some such cases, the cylinders and/or the pistons may have a diameter of between approximately 13.5-34 centimeters (cm). In some embodiments, the cylinders and/or the pistons may have a diameter of between approximately 10-40 cm, 15-25 cm, or about 15 cm. The system  10  may generate power ranging from 10 kW to 10 MW. In some embodiments, the engine  14  may operate at less than approximately 1800 revolutions per minute (RPM). In some embodiments, the engine  14  may operate at less than approximately 2000 RPM, 1900 RPM, 1700 RPM, 1600 RPM, 1500 RPM, 1400 RPM, 1300 RPM, 1200 RPM, 1000 RPM, 900 RPM, or 750 RPM. In some embodiments, the engine  14  may operate between approximately 750-2000 RPM, 900-1800 RPM, or 1000-1600 RPM. In some embodiments, the engine  14  may operate at approximately 1800 RPM, 1500 RPM, 1200 RPM, 1000 RPM, or 900 RPM. Exemplary engines  14  may include General Electric Company&#39;s Jenbacher Engines (e.g., Jenbacher Type 2, Type 3, Type 4, Type 6 or J920 FleXtra) or Waukesha Engines (e.g., Waukesha VGF, VHP, APG, 275GL), for example. The engine  14  is coupled to a controller  15  that controls the operation of the engine  14  (e.g., fuel/air ratio, fuel injection timing, ignition timing, etc.). In certain embodiments, the controller  15  may also be coupled to the aftertreatment system  12 . 
     The power generation system  10  includes the engine  14 , a turbocharger  16 , and a generator  18  (e.g., electrical generator). In certain embodiments, instead of the generator  18 , the engine  14  is coupled to a mechanical drive or machinery. Depending on the type of engine  14 , the engine  14  receives fuel  20  (e.g., diesel, natural gas, coal seam gases, associated petroleum gas, etc.) or a mixture of both the fuel  20  and a pressurized oxidant  22 , such as air, oxygen, oxygen-enriched air, or any combination thereof. Although the following discussion refers to the oxidant as the air  22 , any suitable oxidant may be utilized with the disclosed embodiments. The fuel  20  or mixture of fuel  20  and pressurized air  22  is fed into the engine  14 . The engine  14  combusts the mixture of fuel  20  and air  22  to generate hot combustion gases, which in turn drive a piston (e.g., reciprocating piston) within a cylinder liner. In particular, the hot combustion gases expand and exert a pressure against the piston that linearly moves the piston from a top portion to a bottom portion of the cylinder liner during an expansion stroke. The piston converts the pressure exerted by the combustion gases (and the piston&#39;s linear motion) into a rotating motion (e.g., via a connecting rod and a crank shaft coupled to the piston). The rotation of the crank shaft drives the electrical generator  18  to generate power. Alternatively, the crank shaft drives a mechanical drive or machinery. In certain embodiments, exhaust  24  from the engine  14  may be provided to the turbocharger  16  and utilized in a turbine portion of the turbocharger  16 , thereby driving a compressor of the turbocharger  16  to pressurize the air  22  as indicated by reference numeral  26 . As mentioned above, exhaust  28  from the engine  14  is provided to the aftertreatment system  12  for treatment (e.g., the reduction of emissions within the exhaust  28 ). In some embodiments, the power generation system  10  may not include all of the components illustrated in  FIG. 1 . In addition, the power generation system  10  may include additional components such as an exhaust stack, silencer, control components, and/or heat recovery components. In certain embodiments, the turbocharger  16  may be utilized as part of the heat recovery components. The system  10  may generate power ranging from 10 kW to 10 MW or greater. Besides power generation, the system  10  may be utilized in other applications such as those that recover heat and utilize the heat (e.g., combined heat and power applications), combined heat, power, and cooling applications, applications that also recover exhaust components (e.g., carbon dioxide) for further utilization, gas compression applications, and mechanical drive applications. Embodiments of the present disclosure include a catalyst assembly configured to couple to and receive exhaust from an engine  14 . The catalyst assembly includes a housing and one or more catalyst elements. The housing of the catalyst assembly includes an inlet portion, an outlet portion, and a central portion disposed between the inlet and outlet portion. A cylindrical portion is coupled to and extends from the outlet portion enabling emissions to be sampled through a plurality of one or more sensors disposed perpendicular to a longitudinal axis of the cylindrical portion. 
       FIG. 2  is a cross-sectional side view of an embodiment of the aftertreatment system  12  of  FIG. 1  having a cylindrical portion  44  extending from an end of a catalyst housing outlet. In the following discussion, reference may be made to a longitudinal or axial direction  60 , a radial direction  62 , and/or a circumferential direction  64  of the catalyst assembly  30 . The aftertreatment system  12  may include a catalytic converter or catalyst assembly (e.g., TWC assembly or SCR assembly) to treat or reduce emissions within the exhaust generated by the engine  14 . The catalyst assembly  30  includes a catalyst housing  32  having an inlet portion  34 , and outlet portion  36 , and central portion  38  disposed between the inlet portion  34  and the outlet portion  36 . The outlet portion  36  has a first end  40  and a second end  42 . A cylindrical portion  44  is coupled to and extends from the second end  42  of the outlet portion  36 . One or more sensors  45  (e.g., emissions sensors, such as oxygen sensors, NO x  sensors, or other types of sensors) are coupled to the cylindrical portion  44  of the catalyst housing  32  of the catalyst assembly  30 . The sensors  45  may be disposed perpendicular to a longitudinal axis  57  of the cylindrical portion  44 . For example, the sensors  45  are disposed along an upper half  48  of the annular wall  49 . The sensors  45  are disposed in a sensor boss  50 , such that at least a portion of the sensor boss  50  and/or sensor  45  protrude through the cylindrical portion  44  into the treated exhaust flow  52  to enable collection and/or analysis of a sample of the treated exhaust flow  52  (e.g., treated via one or more catalyst elements  56  within the housing of the catalyst assembly). The sensors  45  may be coupled to a controller  46  which may adjust the air/fuel ratio, fuel injection timing, or other control measures. The catalyst assembly  30  includes an inlet portion  34  to receive the exhaust flow  66  generated by the engine  14 , one or more catalyst elements  56  (e.g., to promote the treatment and reduction of emissions such as O 2 , NO X , SO X , hydrocarbons, and CO), and an outlet portion  36  to discharge the treated exhaust flow  52 . One or more of the sensors  45  are disposed on the cylindrical portion  44  positioned at the outlet portion  36  of the catalyst housing  32 . In some embodiments, one or more sensors  45  on the upper half  48  of the annular wall  49  of the cylindrical portion  44 . The positioning of the sensors  45  may be placed on the upper half  48  of the annular wall  49  keeps moisture (e.g., condensation) from collecting and damaging the sensors  45 . As with the cylindrical portion  44 , the sensors  45  may be removably coupled (e.g., bolted or screwed) to the annular wall  49  of the cylindrical portion  44 . As such, the sensors  45  may be disposed within the sensor bosses  50  into the annular wall  49  via a removable fitting, such as a compression fitting, a threaded fitting, seals or gaskets, clamps, or a combination thereof. Providing the sensors  45  as part of the catalyst assembly  30  disposed in the cylindrical portion  44  enables consistent emissions readings within the treated exhaust flow  52 . The cylindrical portion  44  may be coupled to second end  42  of the outlet portion  36  of the catalyst housing  32 . The cylindrical portion  44  may be permanently or removably (e.g, bolts, nuts, screws) coupled to the outlet portion  36 . The cylindrical portion  44  may be permanently coupled (e.g. welded) to the outlet portion  36  such that the cylindrical portion  44  and the outlet portion  36  form a single piece. Absent a cylindrical portion  44 , readings taken from sensors  45  disposed on the conical wall of the catalyst assembly  30  cause the readings to fluctuate largely due to the voids and non-homogenous flow the sensors experience as the treated exhaust flow  52  flows through the outlet portion  36 . Accordingly, disposing the cylindrical portion  44  to the outlet portion  36  enables better quality samples to be taken because the treated exhaust flow  52  experiences more consistent (e.g., turbulent and homogeneous) flows as it flows through the cylindrical portion  44  of the catalyst assembly  30 . As such, the turbulent and homogeneous flows enable better (i.e., more accurate) measurement of emissions in the treated exhaust flow  52 . 
     The outlet portion  36  includes an annular wall  47  (e.g., conical wall) that includes a diameter  33  that decreases from the first end  40  to the second end  42 . The central portion  38  has a cross sectional area  35  adjacent the first end  40  of the outlet portion  36 , defined in part by a top wall  37  and a bottom wall  39  of the central portion  38 . In certain embodiments, the central portion  38  may include a single annular wall. The at least one oxygen sensor  58  has a diameter  41  where the sensor interfaces with the treated exhaust flow  52 . In one example, the portion  78  of the sensor  45  has may have a diameter of approximately 1.03 centimeters (cm). The diameter  41  range from approximately 0.25 to 2.54 cm, 0.64 to 1.91 cm, or 0.84 to 1.27 cm, and all subranges therebetween. The cross sectional area  35  may have a range from approximately 0.14 to 0.7 m 2 , to 0.15 to 0.6 m 2 , to 0.16 to 0.5 m 2 , and all subranges therebetween. The ratio of the cross sectional area  35  to the second diameter  41  may range from approximately 15:1 m 2 /m to 70:1 m 2 /m, to 16:1 m 2 /m to 65 m 2 /m, to 16.4:1 m 2 /m to 65.7:1 m 2 /m, and all subranges therebetween. The outlet portion  36  of the catalyst assembly  30  includes a first end  40  and a second end  42 . A cylindrical portion  44  is coupled to and extends from the second end  42  of the outlet and includes an annular wall  49 . The diameter  43  of the cylindrical portion  44  may range from approximately 20.3 to 35.6 cm, 22.3 to 30.5 cm, 25.4 to 27.9 cm, and all subranges therebetween. The ratio of the diameter  43  to the second diameter  41  may be approximately 18:1 to 40:1, 20.1:1 to 36:1, 19.7:1 to 34.5:1, and all subranges therebetween. 
     The inlet portion  34  of the catalyst assembly  30  receives an exhaust flow  66  from the engine  14  (e.g., gas engine). The exhaust flow  66  flows along the exhaust flow  66  path in an axial direction  60  from the inlet portion  34  towards the outlet portion  36 . The one or more catalyst elements  56  promote the reduction of emissions within the exhaust flow  66  path to generate a treated exhaust flow  52  that flows downstream from the catalyst elements  56  to the outlet in the axial direction  60 , where the treated exhaust flow  52  is discharged from the catalyst assembly  30  (e.g., to a silencer and/or exhaust stack). The catalyst assembly  30  may include an oxidation catalyst, a carbon monoxide reduction catalyst, a nitrogen oxides reduction catalyst, or any other type of catalyst. In certain embodiments, the catalyst assembly  30  may be a three-way catalyst (TWC) assembly. For example, the catalyst assembly  30 , via the catalyst elements  56  and their catalytic activity, reduces NO X  via multiple reactions. For example, NO X  may be reduced via CO to generate N 2  and CO 2 , NO X  may be reduced via H 2  to generate NH 3  and water, and NO X  may be reduced via a hydrocarbon (e.g., C 3 H 6 ) to generate N 2 , CO 2 , and water. The catalyst assembly  30  may also oxidize CO to CO 2 , and oxidize unburnt HC to CO 2  and water. The catalyst elements  56  may include one or more of aluminum oxide, zirconium oxide, silicone oxide, titanium oxide, platinum oxide, palladium oxide, cobalt oxide, mixed metal oxide, or any other type catalytic material. 
     The cylindrical portion  44  of the catalyst assembly  30  includes one or more sensors  45  (e.g., O 2  sensors, NO x  sensors) disposed on the annular wall  49  of the cylindrical portion  44 . Each sensor  45  samples the treated exhaust flow  52  to provide more accurate readings of the treated exhaust flow  52  emissions compared to sensors  45  disposed on the conical wall of the catalyst assembly  30 . The cylindrical portion  44  provides better quality samples to be taken because the treated exhaust flow  52  experiences more turbulent and homogeneous flows as it flows through the cylindrical portion  44  of the catalyst assembly  30 . As such, the turbulent and homogeneous flows enable the sample to provide a better sample that is representative of the emissions remaining in the treated exhaust flow  52 , compared to the treated exhaust flow  52  flowing through the conical (e.g., inclined, angular) wall. The sensors  45  may be disposed at different circumferential and/or radial  36  positions about and along the cylindrical portion  44  with respect to each other. In one embodiment, the sensors  45  may be disposed perpendicular to a longitudinal axis  57  of the cylindrical portion  44 . An upper half  48  of the cylindrical portion  44  may be defined as the portion above a plane (see  FIG. 3 ) positioned in the axial direction  60  and extending from the plane through the diameter  43  of the cylindrical portion  44  in the radial direction  62 . For example, the sensors  45  may be disposed at an angle  55  of approximately −90 degrees to 0 degrees and from approximately 0 degrees to 90 degrees on an upper half  48  of the cylindrical portion  44 . The upper half  48  of the cylindrical portion  44  is defined as the portion above a plane positioned in the axial direction  60  and extending through the diameter  43  of the cylindrical portion  44 . In certain embodiments, the desired sensor  45  placement with respect to the upper half  48  may range from approximately −90 to 90 degrees, −60 to 60 degrees, −30 to 30 degrees, and all subranges therebetween. Positioning the sensors  45  on the upper half  48  of the annular wall  49  enables the sensors  45  to avoid collecting undue moisture content accumulating when the equipment of the engine drive system  10 , including the exhaust treatment system  12 , is started up or shut down. As depicted, the sensors  45  may be connected to the cylindrical portion  44  of the catalyst assembly  30  downstream of the catalyst elements  56 . 
     Each sensor  45  includes a portion  78  that extends into fluid flow (e.g., treated exhaust flow) within the annular wall  49  of the catalyst assembly  30 . The portion  78  may be disposed within the treated exhaust flow  52  to enable the collection of a sample of the treated exhaust flow  52  within the cylindrical portion  44 . Sampling the treated exhaust flow  52  from the cylindrical portion  44  of the catalyst assembly  30  provides a better location within the catalyst assembly  30  to dispose the sensors  45  to obtain more accurate measurements. Installing the sensors  45  on the conical or angled wall of the catalyst assembly  30  causes the readings to fluctuate largely due to the turbulent and non-homogeneous flows the treated exhaust flow  52  experiences as it exits the catalyst elements  56 . As will be appreciated, the treated exhaust flow  52  experiences more turbulent and homogeneous flows as it flows through the cylindrical portion  44  of the catalyst assembly  30 . As such, the turbulent and homogeneous flows enable the sample to provide a better sample that is representative of the emissions remaining in the treated exhaust flow  52 , compared to the treated exhaust flow  52  flowing through the conical (e.g., inclined, angular) wall. 
     The sensors  45  may be disposed within and coupled to the annular wall  49  via a variety of mounts. For example, the sensors  45  may be disposed or removably mounted within annular wall  49  via a compression fitting, a threaded fitting, clamps or any combination thereof. Alternatively, the sensors  45  may be fixedly coupled (e.g., welded) to the annular wall  49 . The sensors  45  are configured to couple to the controller  46 . The controller  46  may adjust fuel/air ratio, fuel injection timing, ignition timing, and/or other control measures. Some of these functions may include analyzing emissions emitted by the engine  14  prior to treatment and/or analyzing emissions after treatment. This information may be utilized to access the performance of the engine  14 , fuel utilized with the engine  14 , the performance of the catalyst assembly  30  (e.g., for aging or deactivation), emissions compliance, control purposes, and as well as other purposes. As mentioned above, providing the sensors  45  as part of the catalyst assembly  30  enables consistent readings within the treated exhaust flow  52 . 
       FIG. 3  is a cross-sectional view of an embodiment of a catalyst assembly  30  having a plurality of sensors  45  within the cylindrical portion  44 , taken along line  3 - 3  of  FIG. 2 . The sensors  45  can be exposed to the treated exhaust flow  52  to measure emissions in the treated exhaust flow  52 . In some embodiments, the portion  78  of the sensor  45  includes a round shape, such as a circle, oval, ellipse, and so forth. The portion  78  that interfaces with the flow of the sensor  45  can have a diameter  41  range from approximately 0.25 to 2.54 cm, 0.64 to 1.91 cm, or 0.84 to 1.27 cm, and all subranges therebetween. In one example, the portion  78  of the sensor  45  may have a diameter of approximately 1.03 centimeters. As described above, the cylindrical portion  44  extends from and is coupled to the second end  42  of the outlet portion  36  of the catalyst housing  32 . As described herein, the diameter of the outlet portion  36  of the catalyst housing  32 , and in turn the diameter  43  of the cylindrical portion  44  may range from approximately 20.3 to 35.6 cm, 22.3 to 30.5 cm, 25.4 to 27.9 cm, and all subranges therebetween. The ratio of the diameter  43  to the diameter  41  may be approximately 18:1 to 40:1, 20.1:1 to 36:1, 19.7:1 to 34.5:1, and all subranges therebetween. In some embodiments, the cylindrical portion  44  may include a circular cylinder shape, an ovular cylinder shape, an elliptical cylinder shape, and so forth. In some embodiments, the cylindrical portion  44  may be replaced with a portion having any other polygonal shape, such as a square, rectangular, other quadrilateral, hexagon, octagon, and so forth. The polygonal shape may include equilateral or non-equilateral sides. 
     In one embodiment, a system comprises a cylindrical portion  44  configured to be coupled to a conically-shaped outlet portion  36  of a three-way catalyst assembly  30  along the treated exhaust flow  52  exiting the conically-shaped outlet portion  36 , such that the cylindrical portion  44  is configured to be coupled to the second end  42  of the conically-shaped outlet portion  36 , and at least one oxygen sensor  58  connection is disposed on the cylindrical portion  44  to enable an oxygen sensor  58  to be coupled to at least one oxygen sensor  58  connection. The oxygen sensor  58  can be disposed perpendicular to the longitudinal axis  57  of the cylindrical portion  44 . In some embodiments, the three-way catalyst includes an inlet portion  34  and a central portion  38  disposed between the inlet portion  34  and the conically-shaped outlet portion  36 , such that the central portion  36  has a first diameter  33  adjacent a wider end of the conically-shaped outlet portion  36 , and the at least one oxygen sensor  58  has a second diameter  41 . 
     The present disclosure utilizes catalysts ranging in size from approximately 0.36 m to approximately 0.91 m. In some embodiments, the catalysts may be utilized in a portion having another any other polygonal shape, such as a square, rectangular, other quadrilateral, hexagon, octagon, and so forth. The polygonal shape may include equilateral or non-equilateral sides. The non-cylindrical portion is coupled to and extends from the second end  42  of the outlet portion  36  of the catalyst housing  32 . In one embodiment, a non-cylindrical portion used to accommodate a 0.45 m catalyst section may have a catalyst cross sectional area  35  of approximately 0.16 m 2 . A non-cylindrical portion used to accommodate a 0.91 m catalyst section may have a catalyst cross sectional area  35  of approximately 0.66 m 2 . Utilizing an oxygen sensor  58  with the portion  78  of approximately 0.01 m, the catalyst cross sectional area to portion  78  of the oxygen sensor  58  diameter can be about 16.4:1 m 2 /m when an 0.46 m catalyst is utilized to about 65.7:1 m 2 /m when a 0.91 m catalyst is utilized. The catalyst cross sectional area  35  to portion  78  of the oxygen sensor  58  diameter may range from approximately 15:1 m 2 /m to 70:1 m 2 /m, to 16:1 m 2 /m to 65 m 2 /m, to 16.4:1 m 2 /m to 65.7:1 m 2 /m, and all subranges therebetween. 
     Utilizing the cylindrical portion  44  rather than other shaped portions can reduce the above ratios. In one embodiment, a 0.20 m diameter cylindrical portion  44  may have a cross sectional area of 0.03 m 2 . A 0.36 m diameter cylindrical portion  44  may have a cross sectional area of 0.1 m 2 . Utilizing an oxygen sensor  58  with the portion  78  of approximately 0.01 m, the catalyst cross-sectional area may have a ratio of approximately 3 m 2 /m to 10 m 2 /m. The ratio of the catalyst cross sectional area to portion  78  of the oxygen sensor  58  may range from 1 to 12 m 2 /m, 2 to 11 m 2 /m, and 3 to 10 m 2 /m, and all subranges therebetween. 
       FIG. 4  is a cross-sectional side view of an embodiment of an oxygen sensor connection (e.g., boss) disposed in the annular wall  49  of the cylindrical portion  44 , taken within line  4 - 4  of  FIG. 3 . As described above, one or more sensors  45  may be utilized in the cylindrical portion  44  of the catalyst assembly  30 . The sensors  45  may include one or more oxygen sensors  58 . The oxygen sensor  58  may be coupled to the cylindrical portion  44  via an oxygen sensor boss  59 . The one or more oxygen sensors  58  and oxygen sensor bosses  59  may be disposed along the upper half  48  of the cylindrical portion, as described above with respect to the sensors  45 . The upper half  48  of the cylindrical portion  44  may be defined as the portion above a plane  74  positioned in the axial direction  60  and extending from the plane  74  through the diameter  43  of the cylindrical portion  44  in the radial direction  62 . For example, the oxygen sensors  58  may be disposed at an angle  55  of approximately −90 degrees to 0 degrees and from approximately 0 degrees to 90 degrees on the upper half  48  of the cylindrical portion  44 . In certain embodiments, the desired oxygen sensor  58  placement with respect to the upper half  48  may range from approximately −90 to 90 degrees, −60 to 60 degrees, −30 to 30 degrees, and all subranges therebetween. Positioning the oxygen sensors  58  on the upper half  48  of the annular wall  49  enables the oxygen sensors  58  to avoid collecting undue moisture content accumulating when the equipment of the engine drive system  10 , including the exhaust treatment system  12 , is started up or shut down. In certain embodiments, the oxygen sensor boss  59  may extend beyond an inner surface  61  of the annular wall  49 , such that the oxygen sensor boss  59  is exposed to the treated exhaust flow  52 . As such, the oxygen sensor  58  may also be exposed to the treated exhaust flow  52 . The oxygen sensor boss  59  may include a threaded surface to enable to the oxygen sensor boss  59  to extend further into the annular wall  49  such that a greater portion  68  of the oxygen sensor boss  59  or oxygen sensor  58  may be exposed to the treated exhaust flow  52 . The oxygen sensor  58  and oxygen sensor boss  59  may be able to extend a further into the treated exhaust flow  52  (e.g., in the radial direction  62 ) by utilizing threads, channels, screws, and so forth on the oxygen sensor boss  59 . 
       FIG. 5  is a cross-sectional side view of a non-oxygen sensor boss  77  disposed within an annular wall  49  of the cylindrical portion  44 , taken within line  5 - 5  of  FIG. 3 . As described above, one or more sensors  45  may be utilized in the cylindrical portion  44  of the catalyst assembly  30 . The sensors  45  may include one or more non-oxygen sensors  76 . The non-oxygen sensor  76  may be coupled to the cylindrical portion  44  via a non-oxygen sensor boss  77 . The one or more non-oxygen sensors  76  and non-oxygen sensor bosses  77  may be disposed along the upper half  48  of the cylindrical portion  44 , as described above with respect to the sensors  45 . The upper half  48  of the cylindrical portion  44  may be defined as the portion above the plane  74  positioned in the axial direction  60  and extending from the plane  74  through the diameter  43  of the cylindrical portion  44  in the radial direction  62 . For example, the non-oxygen sensors  76  may be disposed at an angle  55  of approximately −90 degrees to 0 degrees and from approximately 0 degrees to 90 degrees on an upper half  48  of the cylindrical portion  44 . In certain embodiments, the desired non-oxygen sensor  76  placement with respect to the upper half  48  may range from approximately −90 to 90 degrees, −60 to 60 degrees, −30 to 30 degrees, and all subranges therebetween. Positioning the non-oxygen sensors  76  on the upper half  48  of the annular wall  49  enables the non-oxygen sensors  76  to avoid collecting undue moisture content accumulating when the equipment of the engine drive system  10 , including the exhaust treatment system  12 , is started up or shut down. In certain embodiments, the non-oxygen sensor boss  77  may extend beyond an inner surface  61  of the annular wall  49 , such that the non-oxygen sensor boss  77  is exposed to the treated exhaust flow  52 . As such, the non-oxygen sensor  76  may also be exposed to the treated exhaust flow  52 . The non-oxygen sensor boss  77  may include a threaded surface to enable to the non-oxygen sensor boss  77  to extend further into the annular wall  49  such that a greater portion  68  of the non-oxygen sensor boss  77  or non-oxygen sensor  76  may be exposed to the treated exhaust flow  52 . The non-oxygen sensor  76  and non-oxygen sensor boss  77  may be able to extend further into the treated exhaust flow  52  (e.g, a greater distance in the radial direction  62 ) by utilizing threads, channels, screws, and so forth on the non-oxygen sensor boss  77 . 
       FIG. 6  is a cross-sectional side view of an embodiment a cylindrical portion  44  coupled to an end  42  of an outlet portion  36  of a catalyst assembly  30 . The cylindrical portion  44  may be removably coupled to the second end  42  of the catalyst housing  32  by utilizing epoxies or adhesives or mechanically assembling the cylindrical portion  44  to the second end  42  of the catalyst housing via bolts  80 , nuts, screws, and so forth. In other embodiments, the cylindrical portion  44  may be permanently coupled to the second end  42  of the catalyst housing  32  by welding the cylindrical portion  44  to the outlet portion  36 . In other embodiments, the cylindrical portion  44  may be permanently coupled to the second end  42  of the outlet portion  36  by spot welding, utilizing rivets, and soldering the pieces together, and so forth. 
     Technical effects of the disclosed embodiments include systems that enable improved sensor readings of emissions from a catalyst assembly. In particular, embodiments of the present disclosure include a catalyst assembly (e.g., three-way catalyst (TWC)) configured to couple to and receive exhaust from an internal combustion engine (e.g., a reciprocating engine such as a gas engine). The catalyst assembly includes a housing and one or more catalyst elements. The housing of the catalyst assembly includes an inlet portion, an outlet portion, and a central portion disposed between the inlet and outlet portion. A cylindrical portion is coupled to and extends from the outlet portion. One or more sensors are disposed perpendicular to a longitudinal axis of the cylindrical portion. The sensors may include sensors configured to measure an oxygen concentration or a nitrogen oxide composition or other compositions within a sample (e.g., of exhaust flow or treated exhaust flow). By orienting the sensors perpendicular to the longitudinal axis of the cylindrical portion, more accurate readings of emissions may be gathered due to the turbulent and homogeneous flow through the cylindrical portion. Absent the cylindrical portion, readings taken from sensors disposed on the conical wall of the catalyst assembly cause the readings to fluctuate or be less accurate largely due to the the converging turbulent flows causing voids and non-homogenous flow the sensors experience as the treated exhaust flow flows along the angled or conical wall section of the outlet portion. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.