DK177575B1

DK177575B1 - Process for cleaning a particle filter

Info

Publication number: DK177575B1
Application number: DKPA201000335A
Authority: DK
Inventors: Bo Munch Jakobsen; Kaj Munch Jakobsen
Original assignee: Munch Miljoe Teknik I S
Priority date: 2010-04-21
Filing date: 2010-04-21
Publication date: 2013-10-28
Also published as: DK201000335A

Abstract

There is provided a method of cleaning a diesel particle filter, in particular for combustion engines. The method involves positioning the diesel particle filter within a cleaning cabinet. In order to remove soot particles from the particle filter a flow of hot air is blown into the interior of the particle filter from the outlet side. The flow of hot air is regulated in a way that ensures efficient removal of burnt particles.

Description

i DK 177575 B1

METHOD OF CLEANING A PARTICLE FILTER

FIELD OF THE INVENTION

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The present invention relates to a method and system for cleaning filters, and in particular filters for exhaust particles from combustion engines, such as diesel particle filters.

10 BACKGROUND OF THE INVENTION

There is an increasing demand on the environmental aspects of pollution to decrease the negative effects and thus the amount of pollution. One source of pollution of the environment is exhaust gases from combustion engines in vehicles such as cars, buses and 15 the like.

The exhaust gases have become less harmful during the last two decades thanks to more advanced emission control and catalysts. Also diesel engines have become cleaner thanks to catalysts. During recent years, many diesel powered engines have also been equipped 20 with particle filters, for further reducing the amount of pollutants in the exhaust gases.

The particle filters are very efficient in collecting particles and many vehicles have a certain cleaning procedure at certain intervals, wherein the filter is heated in order to try and remove the collected particles. However, even if some of the particles are burnt off during this 25 procedure it is not so efficient as to completely clean the filters, and thus after a certain time the filter has to be replaced. The replacement of the filter is rather costly for the vehicle owner and the filter should be able to be used further if cleaned because the material of the filter, stainless steel and ceramics, have not been degraded during use, if the filter has not been exposed to physical damage, and thus the filter could be reconditioned. This would in 30 turn mean cheaper spare parts for the owners as well as reduced use of material resources.

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 dry air gun (e.g., 50-100 psi) can be 35 used as a source of pressurized air.

2 DK 177575 B1 W02008091218A1 discloses a method of cleaning a particle filter, in particular for combustion engines, comprising the steps of: - a) applying heat to the interior of the particle filter during a certain time period for burning the trapped particles, - b) removing the burnt 5 particles from the particle filter, - c) measuring the particle filter, wherein the measurements are compared to values of an unused filter of the particular type, and if the measured values deviate from the values of the unused filter by a predetermined amount, steps a) to c) are repeated until the measured values are within an approval range. It is mentioned that the removal of burnt particles is performed by blowing air into the particle filter.

10 WO06096244A1 discloses an apparatus for combusting soot from a diesel engine exhaust aftertreatment device. The apparatus includes a cabinet having a housing, a heating element positioned within the housing of the cabinet, and a mounting arrangement for securing the diesel engine exhaust aftertreatment device above the heating element. The 15 apparatus also includes an ash collection container mounted beneath a floor of the housing for collecting ash that falls from the diesel engine exhaust aftertreatment device during heating.

EP1698765A1 discloses a pulse cleaner for cleaning a diesel exhaust treatment device. The 20 pulse cleaner includes a cabinet, a diesel exhaust treatment device positioned within the cabinet, and a collection filter positioned within the cabinet for collecting material displaced from the diesel exhaust treatment device during cleaning. The pulse cleaner also includes a pulse generator for generating pulses that are each directed at a majority of a face of the diesel exhaust treatment device when the diesel exhaust treatment device is mounted at the 25 diesel exhaust treatment device mount. The pulse generator includes a pressure tank for accumulating pressurized air, and a valve arrangement that flushes the pressurized air from the tank. A pulse of air for cleaning the diesel exhaust treatment device is generated each time the tank is flushed.

30 WO 93/03262 A1 discloses a method of cleaning a diesel particle filter comprising the steps of positioning the filter within a housing, applying a flow of hot air to the interior of the filter from the outlet side. The flow of hot air is generated by blowing air through a heating element to increase the temperature of the air to 500 °C. Then continuing the flow of hot air, where the flow of hot air is briefly increased by the repeated short pulses of air. Meanwhile, 35 WO 93/03262 A1 does not disclose that the particle filter is orientated in an upright position 3 DK 177575 B1 and does not provide a solution of how to overcome the thermal buoyancy, which inevitably arises when a particle filter is to be cleaned in an upright position.

What is needed is an improved method for servicing overloaded diesel particle filters or 5 other exhaust after treatment devices.

SUMMARY OF THE INVENTION

10 The present invention solves the above mentioned problems associated with prior art methods of cleaning diesel particle filters. Specifically the present invention provides a method for cleaning a diesel particle filter, in particular for combustion engines, comprising the steps of: • positioning the diesel particle filter within a cleaning cabinet, said particle filter 15 positioned upright with the outlet side upwards and the inlet side downwards; • applying a flow of hot air to the interior of the particle filter from the outlet side, wherein o the flow of hot air is generated by blowing ambient air at a flow between 10 and 100 m3/hour through a heating element with an effect of 6-24 kW to 20 increase the temperature of the air to 600 C-700 C; and o the pressure of the flowing air is increased to compensate for thermal buoyancy resulting from heating the particle filter; • continuing the flow of hot air for 30 to 90 minutes, preferably 30 to 60 minutes, wherein the flow of hot air is briefly increased with 50 to 100% for at least 10 25 seconds at least every 15 minutes; • applying a flow of ambient air at a temperature of between 10 and 40 C for less than an hour; • removing the diesel particle filter from the cleaning cabinet after cleaning.

30 The flow of hot air is generated by blowing ambient air at a flow between 30 and 70 m3/hour through a heating element with an effect of 9-18 kW.

In a particularly preferred embodiment of the present invention the flow of hot air is generated by blowing ambient air at a flow between 40 and 60 m3/hour through a heating 35 element with an effect of 10-14 kW.

4 DK 177575 B1

Preferably the diesel particle filter includes a ceramic substrate having a honey-comb configuration of plugged passages. More preferably the diesel particle filter includes silicon carbide or cordierite. In one embodiment of the present invention the diesel particle filter 5 includes a wire mesh. In a preferred embodiment the diesel particle filter includes corrugated metal foil.

In order to establish the flow of hot and cold air a blower is used to blow air through the diesel particle filter.

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BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a flow chart of the method according to the invention.

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Fig. 2 shows schematically a setup for cleaning particle filters for vehicles according to the present invention.

20 DETAILED DESCRIPTION OF THE INVENTION

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 25 and functional changes may be made without departing from the broad scope of the inventive aspects.

The present disclosure relates to a method for efficiently and effectively cleaning diesel particle filters (DPF) or other exhaust aftertreatment devices. In one embodiment 30 compressed air is used to back flush collected material (e.g., soot, ash or other material captured from engine exhaust) from DPF.

Throughout the specification, cleaning devices and methods are described primarily with respect to cleaning diesel particulate filters. However, it will be appreciated that the same 35 methods can be used to clean other types of engine exhaust aftertreatment devices as well.

5 DK 177575 B1

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 pollutants from the exhaust stream. The methods and cleaners can also be used to clean other types of filters/treatment devices, and 5 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. Patent no. 4,851,015. This type of filter can be 10 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.

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As described herein, DPF or 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 20 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.

Figure 1 shows a schematic flowchart of the method according to the present invention. The 25 particles filter to be cleaned is first visually inspected for visual defects such as cracks, damaged fittings and the like.

The next step is then to clean the interior of the particle filter. According to the present invention this is performed by burning off the soot and carbon compounds that have been 30 deposited on the filter surfaces.

Finally the particle filter is cooled with a flow of ambient air and ultimately mounted in an exhaust system of a vehicle.

35 The particle filter is connected to a flow of heated air. A mass flow controller is arranged to DK 177575 B1 6 control the air flow. Then the air is preheated before entering the particle filter. The particle filter is heated to temperatures above the exothermic reaction of the soot when it is burnt off, but not too high, thereby avoiding damaging the ceramic filter surfaces. Temperature sensors are arranged to monitor the temperatures. During this step the carbon compounds 5 are burnt off the filter surfaces during which the flow is increased to compensate for thermal buoyancy resulting from heating the particle filter. Typically the temperature of the hot air is increased in accordance with a predetermined heating curve, which curve dictates the applied temperature at a given time.

10 The end of the process could be performed in a few different ways. The most simple is to end the heating after a predetermined time period, which time period is based on empiric studies of different types of particle filter. Another way is to measure the amount of burnt particles during the heating process. In that aspect, the particle filter may be subjected to bursts of air injection through it with certain time intervals. The air bursts cause the burnt 15 particles to be ejected from the filter. The amount of particles could then be used as a measurement of when the burning process can be terminated.

Figure 2 shows an apparatus (1) for cleaning a particle filter (2) according to the present invention. The outlet (clean) side of the particle filter is releasibly attached to a pipe (3) 20 comprising a heating element (6). The pipe (3) is connected to an air source (5) and a fan (4), where incoming air is heated by the heating element (6) before entering the particle filter (2). The air (containing burnt particles) leaving the inlet (dirty) side of the particle filter (2) enters a mixing chamber (7), wherein the air is mixed with (cold) ambient air (9) blown into the apparatus through a second fan (8). The mixed air is then forced through a filter (10) 25 before leaving the apparatus (1) as clean air (11).

Even though some examples have been mentioned above, it is to be understood that other types of equipment, systems and principles can be utilized for performing the method according to the present invention. Therefore the embodiments described and shown in the 30 figures are to be regarded as only non-limiting examples of the present invention and that it may be modified within the scope of the patent claims.

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Claims

A method of cleaning a diesel particulate filter, especially for internal combustion engines, comprising the steps of: • placing the diesel particle filter in a purification booth, with the drain side up and the intake side down; Supplying a stream of hot air to the interior of the particle filter via the drain side, wherein o the stream of hot air is generated by blowing surrounding air in an amount of between 30 and 70 m3 / hour through a heating element with a power of 9-18 kW to increase the air temperature to 600 C-700 C; and o the flow pressure is increased to compensate for thermal fluctuations caused by the heating of the filter; • the flow of hot air is continued for 30 to 90 minutes, preferably for 30 to 60 minutes, with the flow of hot air briefly increasing by 50 to 100% for at least 10 seconds at least every 15 minutes; Supplying a stream of ambient air at a temperature of between 10 and 40 ° C for less than one hour; • removal of the diesel particulate filter from the cleaning cabin after cleaning.

The method of claim 1, wherein a stream of hot air is generated by blowing ambient air in an amount between 40 and 60 m 3 / hr through a heating element having a power of 10-14 kW.

The method of claim 1 or 2, wherein the temperature of the hot air is increased in accordance with a predetermined heat curve which determines the temperature used at a given time.

The method according to any one of the preceding claims, wherein the diesel particulate filter contains a ceramic substrate in honeycomb form with blocked passages.

The process according to any one of the preceding claims, wherein the diesel particulate filter contains silicone carbide or cordierite.

The method of any one of the preceding claims, wherein the diesel particulate filter contains wire mesh. DK 177575 B1

The method of any one of the preceding claims, wherein the diesel particle filter contains corrugated metal foil.

The method of any one of the preceding claims, wherein a fan is used to blow hot air through the diesel particulate filter.