Patent Application
20090044523
The present invention relates generally to devices and methods for servicing/cleaning diesel particulate filters or other aftertreatment devices.
To reduce air pollution, engine exhaust emissions standards have become increasingly more stringent. Aftertreatment devices have been developed to satisfy these increasingly stringent standards. For example, catalytic converters have been used to reduce the concentration of pollutant gases (e.g., hydrocarbons, carbon monoxide, nitric oxide, etc.) exhausted by engines. With respect to diesel engines, diesel particulate filters have been used to reduce the concentration of particulate matter (e.g., soot) in the exhaust stream. U.S. Pat. No. 4,851,015, which is hereby incorporated by reference, discloses an example diesel particulate filter. Other example types of aftertreatment devices include lean NOx catalyst devices, selective catalytic reduction (SCR) catalyst devices, lean NOx traps, or other device for removing for removing pollutants from engine exhaust streams.
At times, it is required to service aftertreatment devices. To facilitate servicing, aftertreatment devices are often clamped into an exhaust system as modules or separate units. For example, clamps can be provided at flange interfaces located opposite adjacent opposite ends of the aftertreatment devices. By removing the end clamps, a given aftertreatment device can be removed from its corresponding exhaust system for servicing.
In use, aftertreatment devices occasionally become overloaded with soot, ash or other materials present in or generated from engine exhaust. As aftertreatment devices become overloaded, the devices cause undesirable backpressure in their corresponding exhaust systems. When an aftertreatment device becomes plugged to the point where excessive backpressure is a concern, it is recommended to remove the device from its corresponding exhaust system for servicing. To service a device such as a diesel particulate filter, it is known to manually move a focused stream of pressurized air back and forth across the outlet side of the filter to loosen soot/ash that has collected on the filter. For example, a compressed air gun (e.g., 50-100 psi) can be used as a source of pressurized air. Simultaneously, an industrial vacuum device is coupled to the inlet side of the filter. The vacuum device is typically equipped with a high-efficiency particulate air filter or ultra-low penetration air filter for collecting the soot/ash that is blown from the filter by the pressurized air. Total time for cleaning the filter depends on the size of the filter, but is typically 30-50 minutes. However, the small volume of compressed air typically provided from a compressed air nozzle can often diffuse rapidly into the porous core of the aftertreatment device thereby limiting effectiveness.
Diesel particulate filters can also be cleaned by using a heating process to combust material captured on the filters. It is known to use ovens for heating the diesel particulate filter. When heating filters in an oven, filters have been known to crack because the combustion is uncontrolled.
What is needed is an improved device/method for servicing overloaded diesel particulate filters or other exhaust aftertreatment devices.
Certain aspects of the present disclosure relate to devices and methods for efficiently and effectively combusting diesel exhaust material present on diesel particulate filters or other aftertreatment devices.
Examples representative of a variety of inventive aspects are set forth in the description that follows. The inventive aspects relate to individual features as well as combinations of features. It is to be understood that both the forgoing general description and the following detailed description merely provide examples of how the inventive aspects may be put into practice, and are not intended to limit the broad spirit and scope of the inventive aspects.
In the following detailed description, references are made to the accompanying drawings that depict various embodiments which are examples of how certain inventive aspects may be practiced. It is to be understood that other embodiments may be utilized, and structural and functional changes may be made without departing from the broad scope of the inventive aspects.
The present disclosure relates to methods and systems for efficiently and effectively cleaning diesel particulate filters (DPF) or other exhaust aftertreatment devices. In one embodiment, a cleaner includes a cabinet in which a heating element is positioned. A compressed air outlet is provided beneath the heating element. An ash collection container is mounted beneath the compressed air outlet. A hood is provided for venting the products of combustion from the cabinet. A blower or fan can be used to force air into the cabinet for facilitating venting the products of combustion through the hood. In use, a diesel particulate filter or other aftertreatment device is mounted over the heating element and the heating element is heated to start the combustion process. To promote controlled combustion, pulses of air from the compressed air outlet are directed into the region beneath the heating element. The pulses move through the diesel particulate filter or other aftertreatment device to enhance the combustion process. Air nozzles used in generating the pulses can be aimed directly at the diesel particulate filter being serviced or away from the diesel particulate filter being serviced.
Throughout the remainder of the specification, cleaning devices and methods are described primarily with respect to cleaning diesel particulate filters. However, it will be appreciated that the same devices and methods can be used to clean other types of engine exhaust aftertreatment devices as well. Other example aftertreatment devices that may require servicing include catalytic converters, lean NOx catalyst devices, selective catalytic reduction (SCR) catalyst devices, lean NOx traps, or other devices for removing for removing pollutants from the exhaust stream. The methods and cleaners can also be used to clean other types of filters/treatment devices, and are not limited exclusively to engine exhaust aftertreatment devices.
Diesel particulate filter substrates can have a variety of known configurations. An exemplary configuration includes a monolith ceramic substrate having a “honey-comb” configuration of plugged passages as described in U.S. Pat. No. 4,851,015 that is hereby incorporated by reference in its entirety. This type of filter can be referred to as a wall-flow trap or filter. Common materials used for wall-flow filters include silicon carbide and cordierite. Wire mesh, corrugated metal foil and other flow-through type filter configurations can also be used. In certain embodiments, the filter substrate can include a catalyst. Exemplary catalysts include precious metals such as platinum, palladium and rhodium, and other types of components such as base metals or zeolites.
As described herein, aftertreatment devices are described as having inlet sides or faces and outlet sides or faces. The inlet side or face of an aftertreatment device is the side that faces the incoming flow of exhaust when installed in an exhaust system. The inlet side can be referred to as the “dirty” side since it is the side at which material filtered from the exhaust stream collects. The outlet side or face of an aftertreatment device is the side that faces away from the incoming flow of exhaust when installed in an exhaust system. The outlet side can be referred to as the “clean” side.
Referring to
Referring to
The heating element 50 and the reflector 52 are mounted within a cylindrical first pipe section 100 having flanged upper and lower ends. The flanged upper end allows an aftertreatment device to be clamped in place (e.g., with v-band clamp 102) over the heating element 50. The lower flanged end of the first pipe section 100 is clamped to the upper flanged end of a second pipe section 104 (e.g., with v-band clamp 106). The second pipe section 104 includes an enlarged diameter portion 108 connected to a reduced diameter portion 110 by a conical diameter transition portion 112. The second pipe section 104 is secured (e.g., welded or fastened) to a rim 114 secured to the bottom wall 24 of the cabinet 21. The reduced diameter portion 110 of the second pipe section 104 projects downwardly below the bottom wall 24 and has a flanged lower end.
The ash collection container 42 is clamped (e.g., with v-band clamp 116) to the lower flanged end of the second pipe section 104. The ash collection container 42 includes a main bin 43 having an open top end covered by a lid 45. A pipe section 47 is mounted at the center of the lid 45. The pipe section 47 extends though the lid 45 and has a flanged upper end that can be clamped to the lower flanged end of the second pipe section 104. The lid 45 is removable from the bin 43 to allow ash to be emptied from the bin 43.
A compressed air outlet 45 (e.g., a nozzle, hose, pipe, of other structure) is positioned between the reflector 52 and the container 42. For example, in
It is preferred of the outlet 45 to be in fluid communication with a source of compressed air 124 via the line 122. A controller 126 controls the amount of air provided to the outlet 45. The flow can be controlled/metered to control the rate of combustion at the aftertreatment device being serviced. In one embodiment, the controller interfaces with a solenoid 128 that opens and closes to provide pulses of air to the outlet 45. In one embodiment, the source of compressed air has a pressure of at least 60 pounds per square inch (psi), or in the range of 60-100 psi, or preferably about 90 psi. In another embodiment, flow rates preferably in the range of 0.5-2.0 standard cubic feet per minute (SCFM) are provided beneath the heating element during regeneration. In still another embodiment, pulses having durations in the range of 0.25-1 s, a pulse frequency of about 2-15 or 2-8 pulses per minute, and a flow rate in the range of 0.5-2.5 SCFM or 0.75-1.25 SCFM are provided beneath the heating element. It will be appreciated that the above numerical information is provided for illustration purposes only, and is not intended to limit the broad inventive aspects of the present disclosure.
The pulses of air provide a number of functions. For example, the air pulses impinge on the aftertreatment device causing soot and ash packed on the device to be dislodged and to fall into the container 42. The upward flow of air also carries and distributes heat evenly through the aftertreatment device. By controlling the air flow rate, the amount of oxygen supplied to the aftertreatment device can also be controlled to control the core temperature and combustion rate. In a preferred embodiment, the high pressure air pulse can penetrate soot built-up on the diesel particulate filter.
A blower 70 or fan is also mounted in the housing 22. A wall 52 (see
In use of the system, the front door 40 of the cabinet is opened to provide access to the chamber 23. With the door open 40, a diesel particulate filter (DPF) can be mounted (e.g., clamped or otherwise secured) on top of the heating element. Preferably, the DPF is mounted with the inlet side facing downwardly and the outlet side facing upwardly. Once the DPF is in place, the door 40 is closed and the heating element is activated to heat the core of the DPF to a temperature suitable for combusting ash on the DPF (e.g., 900-1500 F). During an initial warm-up period (e.g., about 20 minutes), the heating element is activated. During this warm up period, it is preferred to not provide air pulses to the system so that more uniform radiant heating is provided across the entire face of the core being serviced. Uniform heating prevents preferential air flow paths from developing in the DPF that may interfere with the ability to uniformly regenerate the entire DPF. After the warm-up period, the air outlet 45 begins to direct pulses of air downwardly into the container 42 (e.g., at a pulse rate of 0.5 seconds on and 15 seconds off). The pulses of air reflect off the container 42 and migrate upwardly through the heat reflector 52, the heating element 50 and the DPF mounted on the heating element 50. The pulses of air assist in providing uniform combustion temperatures across the entire volume of the DPF while maintaining a controlled combustion. The pulses of air also assist is dislodging ash from the DPF during the combustion process. The ash falls downwardly from the DPF through the heating element 50 and the heat reflector 52 and is collected in the container 42. The container 42 is preferably periodically disconnected from the cabinet to be emptied.
After the combustion process has been completed (e.g., about 3-5 hours), the heating element 50 turned off and the air flow is increased during the cool-down. In one embodiment, the flow rate is increased to at least 1.5 times the regeneration air flow rate. For example, the pulse rate can be increased to 0.5 second on and 4-10 s or 7.5 to 10 seconds off). The cool-down period can often extend for 2-3 hours. After the heating element and cabinet interior cool to a predetermined temperature (e.g., 140 F), the front door 40 can be opened to remove the clean DPF. Thereafter, another DPF can be mounted on the heating element 50 and the process can be repeated.
During heating, if the heating element fails (e.g., a heating controller does not modulate), the solenoid fails (e.g., sticks open or closed), or the cabinet temperature exceeds a predetermined temperature, the system can be programmed to abort the regeneration cycle.
To make the process more efficient, the DPF, the pipe sections 100, 104 and the ash container 42 can be covered with insulating layers (e.g., heat shields, blankets, sheaths, etc.) For example,
To improve cleaning, the combustion type cleaner disclosed herein can be used in combination with a pulse cleaner of the type disclosed at U.S. patent application Ser. No. not yet assigned, having attorney docket number 758.1913USU1, entitled APPARATUS FOR CLEANING EXHAUST AFTERTREATMENT DEVICES AND METHODS, filed on a date concurrent herewith, which is hereby incorporated by reference in its entirety. For example, after soot has been combusted from an aftertreatment device with the heat cleaner of the present disclosure, the aftertreatment device can then be placed in a pulse cleaner to remove any residual ash.
Referring to still to
The controller interfaces with a temperature sensor 405 (e.g., a thermocouple or thermometer) provided at the heating element 350 to access temperature readings corresponding to the temperature of the heating element 350. The controller 326 uses the temperature readings to control the temperature gage 402. If the temperature of the heating element 350 exceeds a predetermined limit, the controller 326 can terminate heating operations by disconnecting the heating element 350 from its power supply 412 (e.g., via power switch 414).
The controller 326 further interfaces with an electronic latch 416 (e.g., a solenoid of other structure), a door sensor 418 (e.g., a push switch or other structure), a fan 420, an aftertreatment device sensor 422 (e.g., a proximity sensor or other device for detecting the presence of an aftertreatment device above the heating element) and a cabinet temperature sensor 224 (e.g., a thermometer, temperature switch or other structure for providing feedback regarding temperature). The electronic latch 416 prevents the cabinet door from being opened during heating operations. If it is necessary to open the cabinet door during heating operations, the emergency stop button 410 can be pressed to stop heating operations and override the latch 416. The door sensor 418 senses whether the cabinet door is opened or closed. The controller 326 will not begin a heating operation unless the cabinet door is closed. The fan 420 provides air for exhausting/ventilating the cabinet 321. The sensor 422 senses whether a DPF is in position over the heating element 350. If the sensor 422 does not detect the presence of a DPF, the controller will not allow a heating operation to take place. The controller also will terminate heating operations if the cabinet temperature exceeds a predetermined limit as indicated by the cabinet temperature sensor 424.
The controller 326 also interfaces with a solenoid 426 and an air pressure sensor 428. The solenoid 426 receives compressed air from a source of compressed air 430, and is used by the controller 326 to control the pulses (e.g., duration and timing) of air provided to the compressed air outlet 345. The pressure sensor 428 reads whether sufficient pressure is being provided to the solenoid. If sufficient pressure is not present, the controller will either terminate heating operations if heating operations are ongoing, or will prevent heating operations from being started.
Referring still to
Referring again to
As shown at
It will be appreciated that the same types of heating and cooling cycles/processes described with respect to the embodiment of
The above specification provides examples of how certain inventive aspects may be put into practice. It will be appreciated that the inventive aspects can be practiced in other ways than those specifically shown and described herein without departing from the spirit and scope of the inventive aspects.
This application is being filed on 18 Jan. 2006 as a PCT International Patent application in the name of Donaldson Company, Inc., a U.S. national corporation, applicant for the designation of all countries except the US, and Wayne M. Wagner, Mary Joanne Lorenzen, and John T. Herman, all citizens of the U.S., applicants for the designation of the US only, and claims priority to U.S. Provisional Application Ser. No. 60/658,612, filed Mar. 4, 2005.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US06/01850 | 1/18/2006 | WO | 00 | 6/16/2008 |
| Number | Date | Country | |
|---|---|---|---|
| 60658612 | Mar 2005 | US |
