Patent Application
20140174057
This patent disclosure relates generally to an aftertreatment system for reducing emissions in exhaust gasses produced by a power source such as a large internal combustion engine and, more particularly, to a reverse-flow system for efficient treatment and packaging.
Power systems may include internal combustion engines that burn a hydrocarbon-based fuel to convert the potential or chemical energy stored therein to mechanical power that can be used to power other applications. The applications may be mobile such as vehicles or locomotives, stationary such as power generators, or both. The exhaust gasses that result from combusting fuel in the power system may include byproducts such as carbon oxides (CO and CO2), nitrogen oxides (NO and NO2), and particulate matter. The amount of these byproducts that may be discharged by the power system are often subject to government regulation and emissions laws. Accordingly, manufacturers of power systems have undertaken efforts to reduce or remove the regulated byproducts from the exhaust gasses. One methodology for reducing these byproducts is to employ aftertreatment systems disposed in the exhaust system downstream of the internal combustion engine that can receive the discharged exhaust gasses. For example, the aftertreatment system may include catalytic materials that convert the regulated byproducts to more benign constituents. Other systems might operate by filtering the byproducts out of the exhaust gasses.
Certain considerations may apply to the design of an aftertreatment system such as the effective exposure of the exhaust gasses to the catalytic or filtration materials. Another consideration may be the size and/or shape of the aftertreatment system so that the aftertreatment system is efficiently accommodated in the power system. One example of an aftertreatment system designed to address some of these considerations is described in U.S. Pat. No. 6,824,743 (“the '743 patent”), which describes a cylindrical housing that is closed-off at one end. The housing accommodates an annular filter element disposed around a central return pipe. Exhaust gasses may enter the housing, pass through the annular filter element toward the closed end and return through the central return pipe. The present disclosure is directed to addressing similar efficiency considerations described in the '743 patent.
In an aspect of the disclosure, there is described an aftertreatment module for treating exhaust gasses. The module includes a housing having a front wall and an opposing rear wall. A first channel extends between the front wall and the rear wall and includes a first aftertreatment brick disposed therein. Similarly, a second channel extends between the rear wall and the front wall and includes a second aftertreatment brick disposed therein. The first channel and the second channel are arranged in parallel with each other. A traverse channel is disposed along the rear wall traversing the first channel and the second channel in order to communicate exhaust gasses between the first channel and the second channel.
In another aspect, the disclosure describes a method of treating exhaust gasses. According to the method, the exhaust gasses are channeled in a first direction and passed through a first aftertreatment brick. The exhaust gasses are redirected and channeled in a second direction where the exhaust gasses are passed through a second aftertreatment brick.
In a further aspect, the disclosure describes a method of assembling an aftertreatment module for treating exhaust gasses. According to the method, a cradle is provided including a first sleeve and a second sleeve disposed in a side-by-side relationship. A first aftertreatment brick is inserted into the first sleeve and a second aftertreatment brick is inserted into the second sleeve. The method provides a module housing including an interior region accessible by a front opening and a rear opening. According to the method, the cradle is inserted through one of the front opening and the rear opening. The front opening is enclosed with a front plate having disposed therein a first port and a second port. The rear opening is also enclosed with a rear plate that may lack ports.
In yet another aspect, the disclosure describes a power system including an internal combustion engine combusting fuel into exhaust gasses to generate a mechanical force. The power system also includes an exhaust system in communication with the internal combustion engine and an aftertreatment module. The aftertreatment module includes a first channel, a second channel parallel and adjacent to the first channel, and a traverse channel communicating between the first channel and the second channel. The exhaust gasses from the internal combustion engine can pass first through a first aftertreatment brick disposed in the first channel and can pass second through a second aftertreatment brick disposed in the second channel.
This disclosure relates to an aftertreatment system for treating exhaust gasses from a power system before they are released to the atmosphere. Referring to
Due to the large power requirements necessary to run the pump 106 at the required pressures for fracturing, the internal combustion engine can be sized to produce power on the order of 750 horsepower or greater. Accordingly, the internal combustion engine 102 may combust a large volume of fuel and, as a result, may produce a large volume of exhaust gasses. To treat those exhaust gasses, an aftertreatment system 114 is disposed over the internal combustion engine 102 and in fluid communication with the exhaust system 116 of the engine. The term “aftertreatment” refers to the concept that the system treats exhaust gasses after they have been produced and is therefore distinguishable from fuel additives and the like that affect the combustion process. The aftertreatment system 114 can receive the exhaust gasses from a turbocharger in the exhaust system 116 and direct them through one or more aftertreatment modules before release. Although the disclosed embodiment treats exhaust gasses from a diesel-burning internal combustion engine 102, in other embodiments the aftertreatment system 114 can be used with other engines such as a gasoline-burning engine, a natural gas turbine, coal-burning applications and the like. Further, while the particular aftertreatment system 114 is described with respect to a power system 100 used for geological fracturing, in other embodiments, the aftertreatment system and associated power system can be utilized in other applications such as stationary electrical power generation. In addition, the disclosure can be utilized in mobile applications such as locomotives and marine engines.
Referring to
The first exhaust unit 124 of the aftertreatment system 114 can include an aftertreatment module 130 coupled to a cylindrical, tank-like muffler 132 that terminates in a discharge port 134 where the exhaust gasses may be released to the environment. To couple to and receive the untreated exhaust gasses from the exhaust system of the engine, the aftertreatment module 130 includes or is attached to an inlet flange 136. To couple to and communicate the treated exhaust gasses to the muffler 132, the aftertreatment system also includes an outlet flange 138. The inlet and outlet flanges 136, 138 may be circular and may be coupled to mating flanges on the other components by bolts, welding or other suitable coupling techniques. For reasons described below, the inlet flange 136 and the outlet flange 138 may be generally adjacent to each other and may be oriented in the same direction.
Referring to
Referring to
CO+1/2O2=CO2 (1)
[HC]+O2=CO2+H2O
To expose the catalytic material to the exhaust gasses, as shown in the detailed view, the first and second aftertreatment bricks can include an internal substrate matrix 164 such as a triangle lattice, honeycomb lattice, metal mesh or similar thin-walled support structure or screen surrounded by and supported inside of a tubular or cylindrical mantel 166. The opened-lattice structure can permit the exhaust gasses to flow through the aftertreatment brick from one side to the other. The catalytic material 168 can be deposited on the substrate matrix 164 by any suitable method including, for example, chemical vapor deposition, adsorption, powder coating, spraying, etc. While the present embodiment utilizes DOCs, different aftertreatment methods can be implemented in other embodiments including the use of selective catalytic reduction (SCR) aftertreatment bricks, diesel particulate filters (DPFs), ammonia oxidation catalysts, and any other suitable aftertreatment system.
To accommodate the aftertreatment bricks 160, 162 in the housing 140, the aftertreatment bricks can be generally cylindrical in shape and can be received in a correspondingly shaped cradle 170. The cradle 170 can be disposed in the housing 140 approximately mid-way between the front wall 142 and the rear wall 144 and can secure the first and second aftertreatment bricks in an adjacent or side-by-side relationship with the first aftertreatment brick oriented toward the first arcuate sidewall 152 and the second aftertreatment brick oriented toward the second arcuate sidewall 154. The first and second flow-through aftertreatment bricks can be oriented in the cradle 170 so that the exhaust gasses can traverse across the cradle.
To receive the exhaust gasses inside the aftertreatment module 130, the inlet flange 136 can define a circular-shaped first port 172 disposed through the front wall 142, which in certain embodiments can function as an inlet port. The first port 172 can access an entry region 174 disposed in the front of the housing 140 between the front wall 142 and the cradle 170. To distribute and decelerate the incoming exhaust gasses and possibly to act as a spark arrester extinguishing any sparks, the entry region 174 can include a perforated diffuser plate 176 or screen. The first port 172, the entry region 174 and the first flow-through catalyst 160 can therefore define a first flow channel 178 extending from the front wall 142 toward the rear wall 144 of the aftertreatment module. As depicted in
To redirect the exhaust gasses to the second aftertreatment brick after passing through the first aftertreatment brick, the housing 140 can include a traverse channel 180 located between the rear wall 144 and the cradle 170. The traverse channel 180 extends along the rear wall 144 from the first arcuate sidewall 152 to the second arcuate sidewall 154. The traverse channel 180 thereby delineates a traverse flow axis 181 that is generally perpendicular to the first flow channel 178 and the first principal flow axis 179. The second aftertreatment brick 162 situated in the cradle 170 proximate the second arcuate sidewall 154 can be exposed to the traverse channel 180 on one side and can access an exit region 184 disposed between the front wall 142 and the cradle on the other side. The exit region 184 and the entry region 174 are thus disposed in an adjacent or side-by-side relationship and can be separated from each other by an internal wall 186 extending between the front wall 142 and the cradle 170.
To direct exhaust gasses out of the exit region 184 and thus the aftertreatment module 130, the outlet flange 138 can define a circular-shaped second port 182 disposed through the front wall 142. The second flow-through aftertreatment brick 162, the exit region 184 and the second port 182 thereby define a second flow channel 188 from the traverse channel 180 to the front wall 142. The first flow channel 178 and the second flow channel 188 are thus arranged in a parallel and adjacent or side-by-side relationship. The second flow channel 188 can further delineate a second principal flow axis 189 that is parallel to the first principal flow axis 179 and perpendicular to the traverse flow axis 181.
In a further embodiment, to reduce or muffle the sound of the internal combustion engine carried by the exhaust gasses, the aftertreatment module 130 can include a sound attenuation device 190. The sound attenuation device 190 can include a hollow, sound attenuation chamber 192 disposed in the cradle 170 generally between the first and second aftertreatment bricks 160, 162 and generally enclosed from the rest of the housing 140. The sound attenuation device can further include a tubular sound attenuation pipe 194 protruding into the sound attenuation chamber 192 from the rear of the cradle 170 and that establishes fluid communication between the chamber and the traverse channel 180. The sound attenuation pipe 194 can have any suitable length or diameter as will be explained in further detail below. In some embodiments, the sound attenuation pipe can be dimensioned to assist in canceling undesirable sounds, for example, in a manner that could assist a muffler. In some other embodiments, the sound attenuation device may just include an orifice establishing communication between the sound attenuation chamber and the traverse channel.
To manufacture the aftertreatment module, a multi-step assembly process such as the one illustrated in
In the second step 210, the housing 140 including the flat top and bottom surfaces and the arcuate first and second sidewalls is manufactured from, for example, sheet steel or aluminum. The front 212 and the rear 214 of the partially complete housing 140 may remain opened so that the interior 216 of the housing is generally accessible. The cradle 170 including the first and second aftertreatment bricks can be inserted into the interior of the housing 140 though either the opened front 212 or rear 214. The cradle 170 may be situated approximately mid-length between the front 212 and rear 214 and welded or otherwise secured in place. In the third step 220, the other internal components of the aftertreatment module such as the diffuser plate 176 can be inserted through the opened front 212 or rear 214 and secured in place. In the fourth step 230, the oval-shaped front plate 142 is attached by welding or the like to the opened front 212 of the housing 140 and the correspondingly shaped rear plate 144 is attached to the opened rear 214 so that housing is substantially closed.
Referring to fifth step 240, tubes 242 and gussets 244 can be secured to the front plate 142 proximate to the first port 172 and the second port 182. In the sixth and final step 250, the inlet flange 136 and the outlet flange 138 can be respectively secured to the tubes 242 to form the finished aftertreatment module 130. One possible advantage of the described manufacturing process is the improved adaptability and interchangeability of the components within the streamlined workflow. For example, cradles 170 including cradles accommodating various different types of aftertreatment bricks such as DOCs, SCRs, etc. can be made separately from the housing 140. Both components can be made available to the assembler at the second step 210. The assembler can select cradles with different aftertreatment bricks having different operational characteristics for insertion into the same style of housing. Thus, the aftertreatment modules can be customized for various applications.
Referring to
To reduce the byproducts in the exhaust gasses, the aftertreatment module 300 can include a first aftertreatment brick 320 and a second aftertreatment brick 322 accommodated in the housing 301. The first and second aftertreatment bricks 320, 322 can be any of the aforementioned types including DOCs, SCRs and DPFs. To install the first aftertreatment brick 320 in the housing 301, it can be annular in shape with an outer diameter corresponding to the inside diameter of the housing and an inner diameter corresponding to the outer diameter of the inner pipe 310. The first aftertreatment brick 320 can be axially inserted through the opened front end 302 around the inner pipe 310 and can be axially positioned between the front end and the internal wall 312. To install the second catalyst 322 inside the inner tube 310, the second catalyst can have a solid cylindrical or puck-like shape with a diameter corresponding to the inner diameter of the inner tube. The second catalyst 322 can be inserted between the front end 302 and the inner wall 310 coextensively along the length 308 with the first catalyst 320.
To direct the exhaust gasses through the aftertreatment module 300, the outer housing 301 and the inner tube 310 can define an annular first flow channel 330 and the inner tube can define a circular second flow channel 332. The first and second flow channels 330, 332 can extend parallel to the axis line 306. To establish fluid communication between the first flow channel 330 and the second flow channel 332, the space between the inner wall 312 and the axially spaced apart first and second aftertreatment bricks 320, 322 can delineate a traverse flow channel 336. Gas flow within the traverse channel 336 will be generally normal or perpendicular to the axis line 306. To attenuate sound, a sound attenuation device 340 can include an enclosed sound attenuation chamber 342 disposed between the inner wall 310 and the closed rear end 304. To communicate between the sound attenuation chamber 342 and the traverse channel 336, a sound attenuation pipe 344 can be disposed through the inner wall 312 and axially aligned with respect to the axis line 306. The sound attenuation pipe 344 can terminate and be spaced-apart from the rear end 304 a short distance indicated by bracket 346. In other embodiments, a plurality of sound attenuation tubes can be disposed in the inner wall 312 and arranged generally in a circle around the axis line 306.
The present disclosure is applicable to treating exhaust gasses from a power source by directing the exhaust gasses through a reverse or redirected flow aftertreatment module. Referring to
In an embodiment, the traverse channel can direct the exhaust gasses past the sound attenuation device 190 disposed between the first and second flow channels 178, 188. The exhaust gasses may carry sounds from the internal combustion engine such as the opening or closing of valves or the combustion event explosions in the cylinders. To reduce or muffle these noises, the sound attenuation pipe 194 communicating with the traverse channel 180 can receive at least some portion of the sound waves responsible for the noises and can channel them to the sound attenuation chamber 192. In specific embodiments, the dimensions such as the length and diameter of the sound attenuation pipe 194 can be tuned to cancel specific frequencies of sounds from the engine. For example, the sound attenuation pipe 194 can be designed to acoustically resonate with certain frequencies while canceling others such that the resulting sound emitted from the aftertreatment module is reduced or better tuned for further reduction in the muffler. Additionally, the sound attenuation pipe can be tuned by adjusting its dimensions to cancel loud or high pitched sounds such as when the engine is accelerating. For example, the sound chamber and frequency can be tuned to target specific frequencies at the within the range of human hearing, for example, to minimize the effect of undesirable sounds. In other embodiments, the sound attenuation pipe can be tuned to specific sizes of engines or engines with certain numbers of cylinders.
To direct the exhaust gasses through the second aftertreatment brick 162, the intersection of the traverse channel 180 and the second flow channel 188 can redirect the exhaust gasses 90° to align them with the second principal flow axis 189. The second flow channel 188 directs the exhaust gasses from the traverse channel 180 forward through the second aftertreatment brick 162 toward the front wall 142. The treated exhaust gasses can be discharged from the aftertreatment module 130 through the second port 182. The first principal flow axis 179, the traverse flow axis 181, and the second principal flow axis 189 redirect the exhaust gasses approximately 180° such that the exhaust gas flow is redirected by the first flow channel 178, the traverse flow channel 180, and the second flow channel 188. Although the illustrated embodiment describes the exhaust gasses flowing from the first port to the second port, it should be appreciated that in other embodiments the direction of flow can be reversed, i.e., from the second port to the first port. The aftertreatment module can thus be a reversible module simplifying its installation.
Referring to
Accordingly, the disclosed aftertreatment module directs exhaust gasses through both a first aftertreatment brick and a second aftertreatment brick by redirecting or reversing the flow of the exhaust gasses 180°. One advantage of the disclosure is that the reversal of flow and arrangement of the first and second aftertreatment bricks side-by-side permits considerable space reduction and results in a more compact and efficient aftertreatment module. The compact design also allows the aftertreatment module to be contoured or streamlined to have an aerodynamic shape. These advantages facilitate use of the aftertreatment module in mobile applications such as the power system of
It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context.
Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.
