|Title of Invention
A NOVEL EXHAUST EMISSION CONTROL DEVICE FOR DIESEL PARTICULATE
|This invention relates to a novel exhaust emission control device for diesel particulate comprising a main body (9) of cordierite ceramic honeycomb filter an inlet cone (5) and a outlet cone (6) located at either end of said main body, said inlet cone and said outlet cone being designed to provide an inlet pipe (1) which accommodates a one-way valve (3), a pair of air nozzles (7 & 8) being housed within said inlet cone and said outlet cone, said inlet cone comprising of a valve (3), a soot collection chamber (11), a gate valve (13) and an electric band heater (4) and being atleast partly covered with an insulating lining (12); said main body (9) accommodates a plurality of parallel filter units and being provided with non-intumescent mat (10) for insulation, the filter unit being regenerated by air getting through the outlet cone air nozzle (8), switching on the heater (4) for few minutes, air jetting through the inlet cone air nozzle (7) and emptying the soot collection (11) through gate valve (13), thus ensuring a major part of soot being burned outside the honeycomb filter or removed through the gate (13) without burning and avoiding excessive heating of the honeycomb, filter and preventing any travel of soot or ash towards engine side during regeneration.
|FIELD OF THE INVENTION
This invention relates to a diesel particulate emission control device,
BACKGROUND OF INVENTION
Diesel engine used today in large numbers in automobile and other applications emits huge quantity of fine particulate matter emissions, which have harmful effects on human health and life. Known diesel particulate emission control devices utilising 'ceramic based diesel particulate filter elements' are complex and expensive because of the extensive arrangement required for the trapped soot burning and its control systems. This requires the use of such existing devices to the diesel vehicles in India particularly the State road transport vehicles. To solve this problem, a novel diesel particulate emission control device is invented which requires only part burning of the trapped soot, whereas the remaining part of the soot can be removed byphysically emptying from a collection container, thereby reducing the requirements of complete burning of soot inside the ceramic filter unit and associated accessories including on-board control system. The present invention provides an
innovative apparatus with novel design, construction and methods for removing these particulate matters in a simple and easy manner, which can be affordable to the large numbers of polluting diesel vehicles running on road.
India is a vast country where different cities have different climatic conditions, human population, different vehicle population density and sources of pollution. Some cities with large human population and high vehicle population require actions for vehicle pollution control ahead of the rest of the country (Reference: 'AUTO FUEL POLICY REPORT" under the Chairmanship of Dr. R.A. Mashelkar, Council of Scientific and Industrial Research (CSIR), Govt. of India, August 2002, www.autofuelpolicy.org. Chapter 12, Page No.185).
In India the vehicle population is increasing very rapidly. At the same time it was found that 90 percent of the on-road vehicles in the country are old vehicles, which causes much more pollution than that of new vehicles. It has been recommended that reduction of pollution from older vehicle is possible by either (1) replacing the old engine with new less polluting engine, or (2) by retrofitting pollution control device. However India's vast population of diesel-powered vehicles which are old and not in position to afford to incorporate either of these (1) or (2) solutions because of the high cost of new engine as well as high cost of the presently available diesel pollution control device for retrofit. (Reference: "AUTO FUEL POLICY REPORT " under the Chairmanship of Dr. R.A Mashelkar, August 2002, Chapter 14)
Diesel particulate traps are effective in removing carbon soot from the exhaust of diesel engines. The most widely used diesel trap is the wall-flow filter, which filters the diesel exhaust by capturing the soot on the porous walls of the filter body. US Patent Nos. 4,276,071, 4,290,263 and 4,364,761 describe the ceramic diesel particulate filter elements arranged to provide compact high efficiency units of high filter surface area achieved by monolithic structure. These patents suggest removing the trapped particulate matter by burning those in the monolithic structure itself. US Patent 4,404,796 describes the method for periodically oxidizing particulate matter trapped in and on an exhaust gas purifying device by fuel injection or increasing the exhaust gas temperature for burning. The said purifying device comprises a trap constituted of a microporous ceramic honeycomb material having aligned channels with alternate parallel channels thereof blocked to force flow of said exhaust gases through the micropores of said honeycomb material while trapping particulate matter. Thus in all such cases burning of the entire trapped particulates are attempted inside the filter. This practice of burning the entire particulate matter inside the ceramic filter channel requires high power and elaborate heating arrangements or exhaust gas heating arrangements or provision of expensive and durable catalyst for facilitating burning etc. Ceramic is a bad conductor of heat and the particulates trapped deep inside of the thin channels pose other problems for effective burning.
Further, the DPF system known today all are very expensive because of the complexities in their construction and operations. With either on-line or off-line
regeneration system known today the DPF system becomes complex and large size. There are various novel regeneration system suggested e.g. Japanese Patent nos. JP-A-10-33923, JP-A-11-210440 etc. However, it is a problem for the technology disclosed in JP-A-10-3 3923 that the overall system becomes complex and large size as in the backwash component regeneration method due to forced peeling of the ceramic particles on which ash components have been adhered. The technology disclosed in JP-A-11-210440 involves such a problem that it is difficult to permit only the ash component to pass through the outlet side mesh member selectively from the participate and the ash component having different particle size distribution with each other, thereby either trap efficiency of the particulate or discharge efficiency of the ash component is forced to be sacrificed.
US patent application no. 20020157358 (Noda Naomi et al.) suggested the use of some anchor materials for preventing the accumulated ash component from reacting with the DPF construction material causing melting, fusing and other damages of the filter wall. The anchor substance is suggested to be incorporated as a pre-filter or as coating inside the ceramic filter wall. However this requires additional facilities and still removal of ash from such facilities are not provided.
OBJECTS OF THE INVENTION
An object of this invention is to propose a diesel pollution control device which is simple, economical and easy to operate.
Another object of this invention is to propose a diesel pollution control device wherein a majority of the non-combustible ash components of the particulate material do not react or fuse with the walls of the ceramic filter unit.
Still another object of this invention is to propose a diesei pollution control device wherein the ceramic filter unit is subjected to less heat and less severe thermal cycling in comparison to that of the prior art.
Further objects and advantages of this invention will be more apparentfrom the ensuing description.
At the outset of the description which follows, it is to be understood that the ensuing description only illustrates a particular form of this invention. However, such a particular form is only intended as an exemplary embodiment and teaching of the invention and not intended to be taken restrictively.
BRIEF DESCRIPTION OF INVENTION
The preferred embodiment of the invention will now be described with reference to the accompanying drawings in which:
FIGURE 1 shows a schematic perspective end view showing an embodiment of the invented apparatus for diesel particulate emission control.
The canned honeycomb based particulate filter apparatus has an inlet and outlet exhause pipe (1 and 2, respectively), the dimensions of those are suiting to the existing exhaust pipe of the particular diesel engine or vehicle for which the diesel particulate emission control device is designed. The inlet pipe 1 of the canned particulate filter, which is attached to the exhauset pipe from the engine, is provided with a. simple one-way valve 3. This valve is normally closed and only opens due to the exhaust gas pressure when the engine is started. Inside of the inlet cone of the canned particulate filter, a suitable electric band heater 4 is attached near to the inlet face of the honeycomb filter units. The capacity of the electric heater could be from 0.5 to 56 kw depending on the diesel engine size but more preferably for a typical state transport bus with a 6 liter diesel engine displacement Is 2 to 5 kw. Both the inlet and the
outlet cones (5 and 6, respectively) of the canned particulate filters are provided with the distributed air nozzles 7 and 8, respectively. The ceramic monolithic honeycomb based particulate filter unit 9 is canned inside the metal housing by suitable intumescent or non-intumescent mat 10, made out of ceramic, wool or f ibers etc.
A novel regeneration method and apparatus is provided by the
present invention. As described above the embodiments of the
invention provide a simple affordable way to regenerate the
particulate filter unit by which one can continuously use the particulate filter system without removing it from the diesel vehicle. Using this method of regeneration, the bus can run not less than 300 kms on its route and after that the filter can be regnerated in regular depot or roadside garages whereby existing 220 or 440 volt electricity connection and low powered air compressor is used only for less than 20 minutes to regenerate the apparatus depending on the capacity of the electric heater used. On adopting this novel periodic and less than 20 minutes regeneration schedule at any of the normal depot or garage, the filter unit of the bus is again become ready for not less than 300 kms of run. The novel regneration apparatus comprises of air (jetting through the outlet cone air nozzles 8, switching ont— he
heater 4 for few minutes, air Jetting through the inlet cone air nozzles 7 and emptying the soot collection container 11 in a predetermined sequential fashion. The advantage of this method is that a major part of the collection soot is burnt outside the honeycomb filter avoiding excessive heating up of the honeycomb filter thereby protecting it from thermal shock crack and other thermal damages which normally be found with honeycomb based diesel particulate filter. Further it reduces the energy requirement for the regeneration or incineration of the soot and avoids elaborate arrangements for burning of entire trapped particulates, since the soot comes near to the heater and self-ignited by the sequential operation devised in this invention. The collection container is provided with a insulating lining 12, which is either lined with refractory, ceramic fiber, wool or other types of insulation or it could be insulated by air-gap insulation between the two or more walls of the container. A gate of valve 13 is provided at the bottom of the collection container to facilitate emptying the container whenever required. The main advantage of the invented method is the removal of the non-combustible diesel impurities and metals present in the exhaust soot, which normally causes fusing and other damages to the walls of the honeycomb filter if accumulated and present for long period of time inside the channels of the honeycomb filter. As a
whole the invented regeneration method requires less energy, much economical operation and impart long durable life of the honeycomb filter units. The particulate filter unit also need not require elaborate heating arrangement of the ceramic filter elements and expensive components or gadgets. The appratus and the method of regernation are found simple and easy to operate while normally operating the transport vehicles.
1. A novel exhaust emission control device for diesel paniculate comprising a main body (9) of cordierite ceramic honeycomb filter an inlet cone (5) and a outlet cone (6) located at either end of said main body, said inlet cone and said outlet cone being designed to provide an inlet pipe (1) which accommodates a one-way valve (3), a pair of air nozzles (7 & 8) being housed within said inlet cone and said outlet cone, said inlet cone comprising of a valve (3), a soot collection chamber (11), a gate valve (13) and an electric band heater (4) and being atleast partly covered with an insulating lining (12); said main body (9) accommodates a plurality of parallel filter units and being provided with non-intumescent mat (10) for insulation, the filter unit being regenerated by air getting through the outlet cone air nozzle (8), switching on the heater (4) for few minutes, air jetting through the inlet cone air nozzle (7) and emptying the soot collection (11) through gate valve (13), thus ensuring a major part of soot being burned outside the honeycomb filter or removed through the gate (13) without burning and avoiding excessive heating of the honeycomb filter and preventing any travel of soot or ash towards engine side during regeneration.
2. A novel exhaust emission control device as claimed hi claim 1, wherein through a predetermined sequence of operations, the said air jet nozzles dislodge some of the particulate collection from the ceramic walls of the filter element channels and then blow off the dislodged particulate agglomerates (typically in the form of thin sticks) out of the channels into a collection container.
3. A novel exhaust emission control device for Diesel Particulate substantially as herein described and as illustrated in the accompanying drawings.
|Indian Patent Application Number
|PG Journal Number
|Date of Filing
|Name of Patentee
|BHARAT HEAVY ELECTRICALS LTD.
|BHEL HOUSE, SIRI FORT, NEW DELHI-110049, INDIA.
|PCT International Classification Number
|PCT International Application Number
|PCT International Filing date