Patent Application
20160237874
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 (NOx), oxygen (O2), and other components in the treated exhaust gases may be difficult to obtain.
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 m2/m to 65.7:1 m2/m.
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:
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' 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
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'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
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 m2, to 0.15 to 0.6 m2, to 0.16 to 0.5 m2, and all subranges therebetween. The ratio of the cross sectional area 35 to the second diameter 41 may range from approximately 15:1 m2/m to 70:1 m2/m, to 16:1 m2/m to 65 m2/m, to 16.4:1 m2/m to 65.7:1 m2/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 NOX via multiple reactions. For example, NOX may be reduced via CO to generate N2 and CO2, NOX may be reduced via H2 to generate NH3 and water, and NOX may be reduced via a hydrocarbon (e.g., C3H6) to generate N2, CO2, and water. The catalyst assembly 30 may also oxidize CO to CO2, and oxidize unburnt HC to CO2 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., O2 sensors, NOx 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
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.
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 m2. 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 m2. 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 m2/m when an 0.46 m catalyst is utilized to about 65.7:1 m2/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 m2/m to 70:1 m2/m, to 16:1 m2/m to 65 m2/m, to 16.4:1 m2/m to 65.7:1 m2/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 m2. A 0.36 m diameter cylindrical portion 44 may have a cross sectional area of 0.1 m2. 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 m2/m to 10 m2/m. The ratio of the catalyst cross sectional area to portion 78 of the oxygen sensor 58 may range from 1 to 12 m2/m, 2 to 11 m2/m, and 3 to 10 m2/m, and all subranges therebetween.
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.
