CONTROL

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] None.

FIELD OF THE INVENTION

[0002] The present invention generally relates to air pollution control. Specifically, the invention relates to vehicular devices to mitigate particulate air pollution.

DESCRIPTION OF THE RELATED ART

[0003] Particulate matter (PM) owing to their chemical composition and size are a health and environmental hazard. Particulates less than 2.5 microns in size are also known to be carcinogenic. The emission laws for diesel engines are also becoming more stringent from time to time. Emission standard currently in place for light duty diesel vehicles is Bharat Stage IV which will be revised to Bharat Stage VI by 2020. Thus, very effective control of diesel PM is necessary. To cope up with the new stricter regulations new diesel vehicles can be fitted with advanced catalytic converters, diesel oxidation catalysts or other control devices. The procedure of making an old vehicle on the road to comply with the new standards is also not an easy process. There is therefore a need for pollution control devices for both new and existing vehicles.

[0004] Cyclone separators such as that disclosed in US3953184A are known in the art. Chinese utility model CN202438419ET further discloses a cyclone separator with a spiral shaped baffle. However, the dust capture efficiency of existing devices is not known. SUMMARY OF THE INVENTION

[0005] In various embodiments a spiral baffled cyclone separator for particulate emission control is disclosed herein. The device comprises an inlet (120), an upper cylindrical part (110), and a lower conical part (115). The inlet (120) comprises a venturi portion (122) configured to provide tangential entry of the air stream into the upper cylindrical part. The upper cylindrical part (110) is configured with a spiral baffle (112) placed therewithin, and further comprises an outlet (130) in the middle extending downward from a top surface (113) thereof. The device is configured to receive the air stream tangentially at the cylindrical part, the air stream configured to pass through a spiral passage (119) formed by the baffle (112) and pass through the outlet (130), and trap particles of size less than 10 micrometers. The particles are captured in the lower conical part (115).

[0006] In some embodiments the baffle (112) is coated with a catalyst comprising nickel, palladium or titanium dioxide. In various embodiments, the particle removal efficiency of the device for particles less than 7.5 microns is 54% or better. In some embodiments the device is configured to provide a pressure drop of 5 kPa or lower when fitted to a diesel-fueled vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The invention has other advantages and features which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:

[0008] FIG. 1A shows front view of the cyclone separator.

[0009] FIG. 1B is a horizontal section A-A illustrating internal parts of the cyclone separator including the spiral baffle.

[0010] FIG. 1C shows longitudinal section of the cyclone separator.

[0011] FIG. 2A shows velocity contours through the horizontal section corresponding to A-A.

[0012] FIG. 2B shows velocity contours in vertical section.

[0013] Like numbers indicate like parts throughout the views.

DET AILED DESCRIPTION

[0014] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.

[0015] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.

[0016] The invention in its various embodiments relates to a spiral baffled cyclone separator 100 as illustrated in FIG. 1A to 1C. 1 configured to remove particulate matter from vehicle exhaust streams. As illustrated in FIG. 1A, the cyclone separator device for removal of particulate matter from air streams, has an inlet 120, an upper cylindrical part 110, and a lower conical part 115. The inlet 120 is configured to provide tangential entry of the air stream into the upper cylindrical part.

[0017] The upper cylindrical part 110 is configured with a spiral baffle 112 placed therewithin. The spiral baffle is intended in various embodiments to provide a convoluted path to the air stream containing particulates, and to cause impacting of the surface of the baffle by the particulates, causing agglomeration and removal of the particulates. The device further comprises an outlet 130 in the middle extending downward from a top surface 113 thereof. [0018] A horizontal section corresponding to AA in FIG. 1A is illustrated in FIG. 1B, which further illustrates the device of the invention. The inlet tube 120 is provided with an intake portion 125, followed by a venturi 127. In various embodiments, the venturi 127 is configured to provide increase in velocity of the air stream along with particles present therein, while entering the cylindrical part 110. The accelerated air stream is then configured to pass through a spiral passage 119 formed by the baffle 112 and pass through the outlet 130. Outlet tube 130 has a downward portion 132 as illustrated in FIG. 1C, configured to ensure a convoluted path for the exiting air stream.

[0019] In some embodiments the venturi inlet 127 is configured to provide a natural mechanism for dilution by sucking in the atmospheric air. This dilution improves the nuclearization of particles thereby increasing the particle sizes and promoting entrapment. The venturi 127 may further provide equalisation of flow by smoothing the intermittent pressure surges in vehicle exhaust.

[0020] In various embodiments the device 100 is configured to trap particles of size less than 10 micrometers from the air stream. In various embodiments the particles present in the air stream are configured to fall and be captured in the lower conical part 115. In some embodiments, the lower conical part may be provided with a removable cap 140 for cleaning the device.

[0021] In some embodiments the baffle 112 of the device 100 may be provided with one or more coatings to enhance entrapment of the particles from the air stream. In some embodiments the coatings may include a metal catalyst. In some embodiments the metal catalyst may contain nickel, palladium or titanium dioxide as active agent. In some embodiments the coating may increase the roughness of the surface thereby improving particle capture. In some embodiments the surface may be roughened to capture or adsorb any toxic gases in the exhaust stream. [0022] In operation, the device 100 may provide particle removal efficiency of 54% or better for particles less than 7.5 microns. In some embodiments the device 100 is configured to provide a pressure drop of 5 kPa or lower when fitted to a diesel-fueled vehicle.

[0023] The invention is further explained in the following examples, which however, are not to be construed to limit the scope of the invention which is as delineated in the claims.

EXAMPLES

[0024] EXAMPLE 1: Fabrication of Cyclone Separator

[0025] A modified cyclone separator was fabricated. Conventional cyclone separators cannot remove particles less than 10 microns efficiently. Thus, a spiral baffle was used inside the body of the cyclone separator. The idea behind the baffle is that the small particles having a smaller radius of rotation inside the cyclone will strike the inner side of the baffle and thus their momentum will be removed. The material used was mild steel. Table. 1 shows the dimensions of the cyclone separator.

Table 1: Dimensions of Cyclone Separator Fabricated and Tested

[0026] EXAMPLE 2: Test Results

[0027] Pressure Drop: Pressure measurements were carried out to determine pressure drop across the cyclone device for diesel vehicle exhaust emissions. The pressure at the inlet of the cyclone was 105470 Pa while at the outlet it was 101330 Pa. Thus, the pressure drop is 4.14 kPa. The pressure drop is well within the range of the maximum recommended exhaust back pressure of 10 kPa allowed for vehicles 500 kW and above.

[0028] Particle Removal Efficiency: The cascade impactor was used to analyse the particle size distribution of diesel exhaust particulates and it was found that the mean size of PM was 1.6+0.1 microns. Particle removal efficiency was measured by measuring the initial weight and final weight of the filters at each particle size and % removal is provided in Table 2. The average particle removal efficiency for <7.5 microns was estimated as 54%.

[0029] Simulation Results: Simulation results of velocity distribution within the fabricated device in horizontal section AA is shown in FIG. 2A and longitudinal section is shown in FIG. 2B. The figures show dark portions where the flow velocity is relatively higher, such as the venturi portion 127 and outlet 130.

Table 2: Experimental Particle Removal Efficiency Measured for Cyclone Separator