This application claims priority from U.S. patent application Serial No.

61/453,769, filed on March 17, 2011, the disclosure of which is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention is directed to a system and method of analyzing particulate mass emissions from an emission source and, in particular, to such a system and method utilizing a filter to capture a representative sample of particulate matter produced by the emission source. The invention may be used to measure the particulate mass (PM) emissions from vehicles, such as heavy-duty diesel-fueled engines, but may be used with other engines, as well as stationary emission sources, such as gas turbines, industrial stacks, and the like.

Details of particulate mass emission filter system analyzers are specified by regulation, such as is in the Code of Federal Regulations. These criteria may be too restrictive for all PM sampling applications. For example, equipment compliant with these requirements that were developed for high-power systems may make application to compact, low power uses, such as on vehicle measurements, difficult.

SUMMARY OF THE INVENTION

The present invention facilitates using equipment that is compliant with existing regulations while allowing the equipment to be adapted to a wide range of applications that have heretofore been incompatible with such equipment.

A particle mass filter system and method of analyzing particulate mass emissions from an emission source, according to an aspect of the invention, includes at least one filter holder that is adapted to hold at least one particle filter of a particular surface area in order to remove or collect particles from a flow of gas. A gas manifold is adapted to direct the flow of gas to a stain area of a filter in the at least one filter holder. The gas manifold is adapted to direct the flow of gas to a stain area that is less than the entire surface area of the filter. The gas manifold may include an inlet cone that is adapted to direct the flow of gas toward the at least one filter holder and an outlet cone that is adapted to direct the flow of gas away from the at least one filter holder. The size of the inlet and outlet cones may be selected to direct the flow of gas to the stain area of a filter in the at least one filter holder that is less than the entire surface area of the filter.

Gas may flow at a flow rate that is less than the flow rate that would be required for a stain area that is substantially the entire surface area of a filter in the at least one filter holder. The gas manifold may include a gas inlet supplying gas to a particle filter in the at least one filter holder and a gas outlet receiving the flow of gas from the filter in the at least one filter holder. The gas inlet and gas outlet may face the same general direction.

The filter holder(s) may include a first portion on one side of a particle filter and a second portion on the other side of the particle filter and an electromagnet for selectively holding the first and second portions in contact using electromagnet energy.

A plurality of filter holders may be provided, each adapted to hold a particle filter of a particular surface area in order to remove particles from a flow of gas. The gas manifold may be adapted to direct the flow of gas to a stain area of a filter in one of the filter holders by configuring the gas manifold to direct the flow of gas to a stain area that is less than the entire surface area of the filter in that one of the filter holders. The gas manifold may include a plurality of solenoid-operated flow valves, each for directing the flow of gas to one of said filter holders. A bypass solenoid-operated flow valve may be provided to bypass the at least one filter holder. A control, such as a microprocessor-based control, may be provided to selectively operate said solenoid- operated flow valves.

These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a perspective view of a particulate mass filter system, according to an embodiment of the invention, with certain components removed to review internal details thereof;

Fig. 2 is a sectional view taken along the lines II-II in Fig. 1; Fig. 3 is a perspective view of a filter;

Fig. 4 is a perspective view of an outlet cone;

Fig. 5 is a perspective view of an inlet cone;

Fig. 6 is a sectional view taken along the lines VI- VI in Fig. 1; and

Fig. 7 is the same view as Fig. 1 showing additional components.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings and the illustrative embodiments depicted therein, a particulate mass emission analyzer 10 includes a filter assembly 11 having one or more filter holders 12 that are adapted to hold at least one particle filter 14 of a particular surface area A in order to remove or collect particles from a flow of gas and a gas manifold 16. Gas manifold 16 is adapted to direct the flow of gas to a stain area S of filter 14 in filter holder 12. As will be described in more detail below, gas manifold 16 is configured to direct the flow of gas to a stain area S that is less than the entire surface area A of filter 14. Analyzer 10 may be used to measure the particulate mass (PM) emissions from vehicles, such as heavy-duty diesel-fueled engines using known measurement principles, but may be used with other engines, as well as stationary emission sources, such as gas turbines, industrial stacks, and the like. Although the invention is illustrated with a particle mass emission analyzer having multiple filter holders, it should be understood that it may also be applied to a single filter holder.

In order to direct the flow of gas to a stain area S that is less than surface area A of filter 14, gas manifold 16 includes an inlet cone 22 that is adapted to direct the flow of gas toward filter holder 12 and an outlet cone 24 that is adapted to direct the flow of gas away from filter holder 12. Inlet and outlet cones 22, 24 are sized to direct the flow of gas to stain area S of filter 14 in filter holder 12 that is less than the entire surface area A of the filter. This is accomplished by the largest inner diameter of inlet and outlet cones 22, 24 being less than the diameter of filter 14 in filter holder 12. The size of stain area S is generally governed by the outlet size of inlet cone 22. The angle of cone 22 is chosen to minimize particle losses during expansion. In the illustrated embodiment, filter holder 12 may be a standard 47 millimeter (mm) filter holder and cones 22, 24 producing a stain area S that is smaller than 47 mm. The stain area is selected by the skilled artisan to meet the filter face velocity desired for a given total flow rate using the following formula:

Filter Face Velocity (m/s) = Flow Rate (m ³ /s)/Stain Area (m ² )

By reducing the stain area, a lower flow rate can be used to achieve the same filter face velocity as would be understood by the skilled artisan. By reducing total flow rate, a smaller gas pump may be used. Analyzer 10 includes a gas pump 26 that is adapted to establish the flow of gas in gas manifold 16. Gas pump 26 pumps gas at a flow rate that is less than the flow rate that would be required for a stain area that is substantially the entire surface area A of filter 14 in filter holder 12.

Gas manifold 16 includes a gas inlet 18 supplying gas to a particle filter 14 in filter holder 12 and a gas outlet 20 receiving the flow of gas from filter 14 in filter holder 12. In the illustrated embodiment, gas inlet 18 and gas outlet 20 are facing the same general direction, to the right as illustrated in Fig. 2. Also, in the illustrated embodiment, filter holder 12 includes a first portion 28 on one side of particle filter 14 and a second portion 29 on the other side of the particle filter. First and second portions 28, 29 may be selectively held in contact with each other by at least one electromagnet 30. Electromagnet 30 includes a primary winding 31 on one portion 29, 30 and a secondary plate 32 on the other portion 29, 30. This allows portions 28, 29 to be easily separated by removing any current supplied to primary 31 in order to replace filter 14. Portions 28, 29 can be reconnected by bringing them into juxtaposition and applying a current to primary 31. Of course, a more conventional clamp arrangement could alternatively be used to keep portions 28, 29 removeably together.

In the illustrated embodiment, particulate mass emission analyzer 10 includes a plurality of filter holders 12, each configured to hold a particle filter 14 of a particular surface area A in order to remove particles from a flow of gas. Gas manifold 16 is configured to direct the flow of gas to a stain area S of a filter 14 in one of the filter holders 12 that is less than the entire surface area of the filter in that one of the filter holders. By selecting the dimensions of the inlet and outlet cones 22, 24 associated with each filter holder 12, the stain area S for each filter 14 may be selected. The stain area S may be the same for all filters or may be different. Gas manifold 16 includes a plurality of solenoid-operated flow valves 34, each for directing the flow of gas to one of the filter holders 12. Gas manifold 16 includes an inlet manifold 36 having an inlet fitting 42 connected with inlet 18 of each filter holder 14 and an outlet manifold 38 connected with an outlet of each filter holder 14 through one of the solenoid-operated flow valves 34. By selective activation of valves 34, all of the gas can be directed to one filter holder, then subsequently to another and the like. This allows analyzer 10 to be used to capture particles for different portions of a test protocol. A bypass solenoid- operated flow valve 40 may be provided to bypass the filter holders 12 when no collection of particles is desired.

Particulate mass emission analyzer 10 may further include a control, such as a microprocessor-based control 44, that is adapted to selectively operate solenoid- operated flow valves 34, 40, electromagnets 30, and the like.

By allowing the stain area of a filter to be selected, by selecting from different sized inlet and outlet cones 22, 24, a standard filter holder, such as a 47 mm filter cassette, can be used to accommodate a wide range of operating variables, such as filter face velocity, stain area, gas flow rate, and the like. Also, system weight and cost can be managed by making gas manifold 16 out of materials, such as aluminum, while cones 22, 24 are made from stainless steel. Temperature-controlled internal cartridge heaters and temperature sensors can be uses as desired. Microprocessor-based control 44 may be used to obtain filter temperature and pressure drops in order to measure particulate mass, such as using the principles disclosed in commonly assigned U.S. Pat. No. 7,174,767 entitled Particulate Matter Analyzer and Method of Analysis, the disclosure of which is hereby incorporated herein by reference. Other techniques known in the art may also be used to measure PM from the particles collected on each filter.

While the foregoing description describes several embodiments of the present invention, it will be understood by those skilled in the art that variations and modifications to these embodiments may be made without departing from the spirit and scope of the invention, as defined in the claims below. The present invention encompasses all combinations of various embodiments or aspects of the invention described herein. It is understood that any and all embodiments of the present invention may be taken in conjunction with any other embodiment to describe additional embodiments of the present invention. Furthermore, any elements of an embodiment may be combined with any and all other elements of any of the embodiments to describe additional embodiments.