Patent Application
20200156093
The present disclosure is directed to an exhaust treatment system and, more particularly, to a nozzle that injects a reductant solution into a fluid path within an exhaust treatment system.
Internal combustion engines, such as diesel engines, gasoline engines, gaseous fuel-powered engines, and other engines known in the art, exhaust a complex mixture of components into the environment. These components may include nitrogen oxides (NOx), such as NO and NO2. Due to an increased focus on avoiding environmental pollution, exhaust emission standards are becoming more stringent, and in some instances, the amount of NOx emitted from engines may be regulated depending on engine size, engine class, and/or engine type. To ensure compliance with the regulation of these components, as well as reduce environmental effects, some engine manufacturers implement a strategy called Selective Catalytic Reduction (SCR). SCR is a process where gaseous and/or liquid reductant, most commonly urea ((NH2)2CO), is selectively added to engine exhaust using one or more nozzles. The injected reductant decomposes into ammonia (NH3), reacts with the NOx in the exhaust, and forms water (H2O) and diatomic nitrogen (N2).
U.S. Pat. No. 8,356,473 to Blomquist, issued on Jan. 22, 2013 (hereinafter referred to as the '473 reference), describes an injection device having a first conduit for supplying compressed gas, and a second conduit arranged on the outside of the second conduit for supplying a liquid agent. At least one hole extends between the first conduit and the second conduit. As discussed in the '473 reference, liquid agent flows through the at least one hole into the compressed air. The liquid agent is atomized by the compressed gas, mixed with the compressed gas, and transported through an outlet of the injection device for dispersion into an exhaust line.
While the injection device of the '473 reference may attempt to increase the atomization of the liquid agent, the operation of the injection device may be suboptimal. For example, the injection device described in the '473 reference is relatively small in size, and due to low turbulence and mixing features, effective mixing of the liquid agent may be difficult to achieve. Further, the '473 reference describes an injection device having multiple distinct and assembled parts, and such a device configuration may increase the size, complexity, assembly time, and/or manufacturing cost of the nozzle. Such multi-part devices are also often difficult to clean and may become clogged easily.
Example embodiments of the present disclosure are directed toward overcoming one or more of the deficiencies described above.
According to one embodiment of the present disclosure, a nozzle, is described that includes a nozzle body. The nozzle body includes proximal end having a first inlet disposed in a direction along a longitudinal axis of the nozzle, and a second inlet having a first air inlet channel disposed at an angle perpendicular to the longitudinal axis of the nozzle. The nozzle includes a distal end disposed opposite the proximal end along the longitudinal axis of the nozzle, the distal end having an outlet. An interior of the nozzle is disposed between the proximal end and the distal end, and includes a fluid impingement chamber that is fluidly connected with the first inlet and the second inlet, and a mixing chamber fluidly connected with an outlet at the distal end. The nozzle also includes an impingement device fluidly connecting the fluid impingement chamber and the mixing chamber. The impingement device includes an impingement pin with a pin body and a convex surface disposed at an end of the impingement pin. The convex surface is concentric with the longitudinal axis of the nozzle.
According to another embodiment of the present disclosure, an impingement device includes an impingement pin and a device body coaxial with a longitudinal axis of the impingement pin. The device body is disposed to the impingement pin at a distal end of the impingement device. The impingement pin includes a convex surface at a proximal end of the device. The device body includes a first surface, a second surface opposite the first surface, and a plurality of inner channels connecting the first surface and the second surface. The plurality of inner channels are disposed in a first circular array at a first radial distance from a longitudinal axis of the impingement pin. The device body further includes a plurality of outer channels connecting the first surface and the second surface. The plurality of outer channels is disposed in a second circular array at a second radial distance from the longitudinal axis of the impingement pin.
According to yet another embodiment, an exhaust system is described. The exhaust system includes an exhaust pipe configured to receive exhaust from an engine, a compressed air source, a reductant source, and a nozzle fluidly connected with the exhaust pipe. The nozzle is configured to receive air from the compressed air source and reductant from the reductant source. The nozzle includes an impingement pin and a device body coaxial with a longitudinal axis of the impingement pin. The device body is disposed to the impingement pin at a distal end of the impingement device. The impingement pin includes a convex surface at a proximal end of the device. The device body includes a first surface, a second surface opposite the first surface, and a plurality of inner channels connecting the first surface and the second surface. The plurality of inner channels are disposed in a first circular array at a first radial distance from a longitudinal axis of the impingement pin. The device body further includes a plurality of outer channels connecting the first surface and the second surface. The plurality of outer channels is disposed in a second circular array at a second radial distance from the longitudinal axis of the impingement pin.
This disclosure generally relates to nozzles useful for injecting a mixture of reductant and air into an exhaust stream. Wherever possible, the same reference number(s) will be used through the drawings to refer to the same or like features. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears.
Selective Catalytic Reduction (SCR) is an active emissions control technology system that injects a liquid reductant agent through a catalyst into the exhaust stream of a diesel engine. The reductant source is usually automotive-grade urea, otherwise known as Diesel Exhaust Fluid (DEF). In some embodiments, the reductant may include DEF, an ammonia gas, liquefied anhydrous ammonia, ammonium carbonate, an ammine salt solution, a hydrocarbon such as diesel fuel, or another solution. In DEF reactions, the DEF sets off a chemical reaction that converts nitrogen oxides into nitrogen, water and tiny amounts of carbon dioxide (CO2), natural components of the air we breathe, which is then expelled through the vehicle tailpipe. Embodiments of the present disclosure may reduce emissions increasing the effectiveness of SCR systems in the emission control of diesel combustion engines.
An engine (not shown in
In some embodiments, the nozzle 100 may be manufactured using 3D printing techniques or other types of additive manufacturing (e.g., cast molding) and comprise a single piece of material. However, it is contemplated that one more of the components of the nozzle 100 discussed above and herein may be alternatively manufactured from other processes including manual machining, computer numeric controlled (CNC) machining, or with other methods. Additionally, the nozzle 100 may be manufactured from a plurality of materials, including chromium, nickel, stainless steel, alloys, ceramics, etc. The materials may also be anti-corrosive and anti-stick to prevent a build-up of the reductant on and/or within the nozzle 100.
At the proximal end 104 of the nozzle 100, the nozzle 100 may include one or more inlets configured to receive reductant and/or air from the first air inlet channel 142. For example, the nozzle 100 may include a first inlet 108 for supplying the reductant solution 114 to the nozzle 100, and a second inlet 110 for supplying compressed air 116 to the nozzle 100.
In some examples, at the distal end 106 of the nozzle 100, the nozzle 100 can include one or more spray channel outlet(s) 112. According to embodiments described herein, a reductant/air solution 120 may enter the exhaust stream 102 through the one or more spray channel outlet(s) 112.
As discussed in detail herein, the nozzle 100 may facilitate mixing of reductant solution 114 and compressed air 116 to mix, aerate, separate, and/or atomize the reductant solution 114. According to an embodiment, an interior 118 of the nozzle 100 comprises a structure of the nozzle 100, where the structure comprises various passages and channels formed at least partly by the body of the nozzle 100. More particularly, within the nozzle interior 118 of the nozzle 100, air and reductant may mix together to form the reductant/air solution 120. This process may cause the reductant solution 114 to break up into fine particles or droplets at the interior first end 122 of the nozzle interior 118, and mix with the compressed air 116 at an interior second end 124 of the nozzle interior 118. As noted above, the nozzle 100 may disperse and/or otherwise direct the reductant/air solution 120 into the exhaust stream 102 through the one or more spray channel outlet(s) 112 disposed at the distal end 106 of the nozzle 100. Accordingly, as the reductant/air solution 120 disperses into the exhaust stream 102, the reductant/air solution 120 may react with NOx (e.g., NO and/or NO2) to form water (H2O) and elemental nitrogen (N2).
According to an embodiment, the nozzle interior 118 may be bifurcated into two or more main chambers (e.g., the fluid impingement chamber 426 and the mixing chamber 128) by an impingement device 130. In some aspects, the impingement device 130 may fluidly connect the fluid impingement chamber 426 and the mixing chamber 128 via a plurality of orifices 138 that provide channels for the reductant/air solution 120 to pass from the fluid impingement chamber 426 to the mixing chamber 128. More particularly, an impingement device body 132 may be configured as a substantially flat disk or plate having an impingement pin 134 at a center of the impingement device body 132, where the impingement device body 132 seals against one or more mating surfaces such that reductant solution 114, compressed air 116, and/or reductant/air solution 120 may not pass through the impingement device 130 from the fluid impingement chamber 426 to the mixing chamber 128 except for through the plurality of orifices 138.
As explained in greater detail hereafter, the impingement pin 134 includes a convex surface 136 at a proximal end of the impingement device 130. In operation, the reductant solution 114 may be pumped or otherwise conveyed into the first inlet 108. Accordingly, when pumped into the nozzle 100, the reductant solution 114 travels through first inlet 108 and strikes the convex surface 136, where an approximate center of a laminar flow of the reductant solution 114 (the reductant solution 114 and the laminar flow of the reductant solution 114 depicted as an arrow in
The shape and position of the convex surface 136 is such that upon impinging the convex surface 136, the reductant solution 114 is dispersed into a mixture of ambient air and reductant solution. In some aspects, the orifices 138, which connect the fluid impingement chamber (where the fluid is broken up by the impingement pin 134) and the mixing chamber 128, are configured to further disperse the reductant and compressed air solution into smaller discrete droplets. For example, the orifices 138 can be configured to break the reductant/air mixture into droplets, atomize the reductant and air solution in part, or otherwise reduce the reductant and solution into an aerosol/droplet mixture. As explained in detail hereafter, the orifices 138 may also be configured to create turbulence in the mixing chamber 128 to further combine the compressed air 116 and the reductant solution 114, and form the reductant/air solution 120.
When the reductant solution is urea or contains urea, in some instances, the urea may react with heat such that crystallization of the reductant solution can occur above certain temperatures. Because the nozzle 100 may be operable as part of an exhaust system of a combustion engine, the nozzle 100 can reach temperatures ranging between approximately 200° C. to approximately 500° C. In some examples, the urea-water solution of reductant solution may crystalize at these high temperatures (e.g., between approximately 200° C. and approximately 500° C.), as water evaporates from the solution. When the urea crystalizes at high temperatures, deposits of the urea may form that can hinder the performance of the exhaust system. For example, the selective-catalytic reaction that removes particulates from the exhaust stream may be hindered by the urea crystal deposits, the nozzle outlet or other fluid ports may become clogged, etc.
To prevent crystallization of the reductant solution 114, according to an embodiment, the nozzle 100 may channel the compressed air 116 through a first air inlet channel 142. The compressed air 116, when mixed with the reductant solution 114, may cool the system and prevent crystallization of the urea in the reductant solution 114. Accordingly, the first air inlet channel 142 fluidly connects the second inlet 110 to the fluid impingement chamber 426. The second inlet channel 110 may direct the compressed air 116 into the fluid impingement chamber 426 at a predetermined angle with respect to the longitudinal axis 140. The predetermined angle of incidence of the compressed air 116 with respect to the impingement pin 134 may create a turbulent airflow within the fluid impingement chamber 126. For example, the predetermined angle between an axis of the first air inlet channel 142 and the longitudinal axis 140 may be about 90° (substantially perpendicular). As depicted in
In some aspects, the nozzle 100 may include two or more air inlet channels. For example, the nozzle 100 may include a second air inlet channel 144 disposed opposite to the pin body 135 of the impingement pin 134 such that a longitudinal center of the second air inlet channel may be substantially perpendicular to the outer surface of the pin body 135 of the impingement pin 134, and substantially perpendicular to the longitudinal axis 140. In yet another embodiment, more than two air inlet channels may be included at substantially perpendicular angles to the longitudinal axis 140, such that they are configured to be opposite to the pin body 135. As used herein, the phrase “opposite to the pin body 135” means that the pin body 135 may be configured to be directly in the laminar and/or turbulent flow of a fluid interacting with the pin body 135.
By injecting the compressed air 116 at a perpendicular angle to the longitudinal axis 140, the stream of compressed air 116 may interact with the curved exterior surface of the impingement pin 134 such that the compressed air 116 disperses at reflective angles within the fluid impingement chamber 426. For example, the angle of incidence of the linearly-flowing stream of compressed air 116 equals the angle of reflection of the stream of compressed air 116 as the air stream interacts with the impingement pin 134. Accordingly, when the radially curved pin body 135 interacts with the laminar flow of the stream of compressed air 116, the angle of reflection of the compressed air 116 is spread throughout the fluid impingement chamber 126. The turbulence caused by the compressed air 116 interacting with the curved pin body 135f mixes the compressed air 116 with the reductant solution 114 within the fluid impingement chamber 426. In combination with the dispersed reductant solution 114 (dispersed after hitting the convex surface 136), the reductant solution 114 may be cooled by the compressed air 116, which may be more turbulent and evenly mixed with the reductant solution 114. Because of the turbulence created by the combination/configuration of the first air inlet channel 142 and the reductant solution 114 interacting with the convex surface 136, the interior surfaces of the nozzle interior 118 may also be cooled to a temperature below the threshold for urea crystallization.
The nozzle 100 may be installed directly in the exhaust stream 102 of an exhaust system (e.g., as shown in
With reference to
As shown in
In another aspect, the orifices 138 may be configured as two radial groupings such that one grouping of channels may be at a first radial distance 154 and the second grouping may be organized at a second radial distance 158. For example, a plurality of inner channels 152 may be disposed in circular array at the first radial distance 154 from the second longitudinal axis 150, and a plurality of outer channels 156 are disposed in a circular array at the second radial distance 158 from the second longitudinal axis 150 of the impingement pin 134. In one aspect, the first radial distance may be approximately ⅓ of the radial distance of the impingement device body 132 from the second longitudinal axis 150 to an outer edge of the impingement device body 132. In another aspect, the second radial distance may be approximately ⅔ of the radial distance of the impingement device body 132 from the second longitudinal axis 150 to an outer edge of the impingement device body 132. In other examples, the distance may be greater than or less than the radial distance of the impingement device body 132, such as, for example, ½ of the radial distance, 11/16 of the radial distance, etc.
With reference to the front view of the impingement pin 134 in
Another benefit of the convex surface 136 may be ease of manufacture of the impingement device 130. In some embodiments, the impingement pin 134 may be machined from or otherwise manufactured as a unitary piece with respect to the impingement device body 132. In another embodiment, the impingement pin 134 may be a separate part from the impingement device body 132, and removably disposed to the impingement device body 132 using a mechanical fastener (not shown). In either case, the convex surface 136 may provide an optimal dispersing affect without introduction of multiple machining steps or extraneous parts to assemble.
With continued reference to
The inner channel 160 may be configured to direct fluid (e.g., the reductant solution 114, the compressed air 116, and/or the reductant/air solution 120) in a direction generally consistent with a channel direction 164. The outer channel 162 may be configured to direct fluid (e.g., the reductant solution 114, the compressed air 116, and/or the reductant/air solution 120) in a direction generally consistent with a directional arrow showing a channel direction 166. The inner channel 160 may be representative of the channel direction for all of the inner channels of the plurality of orifices 138 circumferentially disposed around the second longitudinal axis 150. The inner channel 160 fluidly connects the first surface 147 and the second surface 149.
According to another embodiment, the channel direction 164 and the channel direction 166 may be configured in another pattern such that the direction changes at every two channels, every three channels, etc. within the same radial distance. Other configurations are contemplated.
In some embodiments, an amount of compressed air 116 and/or an amount of reductant solution 114 supplied to the system may be associated with a flow rate of the exhaust stream 102, an operational state of the engine 188 (e.g., rpm), a temperature of the exhaust stream 102, a concentration of a particular gas in the exhaust stream 102, and/or one or more other operating conditions of the exhaust system 180. For example, as the flow rate of the exhaust stream 102 decreases, a controller or other control component (not shown) operably connected to an air compressor and/or reductant pump may control the pump to commensurately decrease the amount of reductant solution 114 and/or compressed air 116 supplied to the nozzle 100 (and thereby introduced into the exhaust stream 102). Alternatively, as the flow rate of the exhaust stream 102 increases, a controller or other control component (not shown) may increase and/or decrease the amount of reductant solution 114 and/or compressed air 116 supplied to the nozzle 100. Consequently, the amount of reductant/air solution 120 introduced into the exhaust stream 102 may be controllable by a controller.
In some embodiments, the nozzle 100 may be located downstream from a SCR system, or be operable as part of a SCR system within an exhaust pipe 192 and/or other treatment systems. The exhaust system 180 may also include one or more oxidation catalysts, mixing features, particulate filters (e.g., diesel particulate filter (DPF)), SCR substrates, ammonia reduction catalysts, and other devices configured to further enhance the effectiveness of reducing NOx (devices not shown). Additionally, while only one nozzle 100 is shown, in some embodiments, the exhaust system 180 may include more than one nozzle 100. Moreover, the exhaust system 180 may include any number of exhaust pipes 192 having one or more nozzles 100 positioned therein.
The nozzle 100, impingement device 130, and exhaust system 180 may increase exhaust system efficiency and operability by decreasing and/or eliminating crystallization of urea compounds or other reactants due to adverse response to exhaust system heat. The embodiments described herein may increase turbulence and mixing within the nozzle 100 such that reductant solution 114 may be maintained at operable temperatures while treating the exhaust stream 102 in an exhaust system of a combustion engine.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof
