WO2009051547A1

WO2009051547A1 - Device and method for elimination of particles from gaseous media

Info

Publication number: WO2009051547A1
Application number: PCT/SE2008/050953
Authority: WO
Inventors: Elsie Maria Hjelm; Ulf Johanson
Original assignee: Elsie Maria Hjelm; Johansson Ulf
Priority date: 2007-08-24
Filing date: 2008-08-22
Publication date: 2009-04-23
Also published as: WO2009051547A8

Abstract

The present invention relates to a device for the elimination of particles from gaseous media, characterized by comprising a first pass-way (1, 21 ) having a first inlet (2) for gaseous medium comprising minute particulate material, comprising a pass-way (3, 4) to separate the particulate material into two fractions containing larger and smaller particles, respectively, a means (5, 6, 8) compressing the said gaseous medium bringing the fraction containing said smaller particulate material, and a return pass-way (9) bringing said particles contained in the fraction of smaller particulate material into agglomeration, a collecting means (11, 12) for collecting said agglomerated particles and said fraction containing larger particles, a particle withdrawing means to eliminate said collected agglomerated and larger particles, and a particulate purified gas outlet (26), as well as a method for removing gaseous media born particles.

Description

TITLE

Device and method for elimination of particles from gaseous media.

DESCRIPTION

Technical field

The present invention relates to a device for the elimination of particles present in gases, such as smoke and exhaust gases, in particular diesel engine exhaust gases and particles related to ventilation air.

The object of the present invention is to obtain a device for elimination/reduction of the amount of solid particles in such gases in order to thereby reduce the environmental risks, in particular for those being present in the neighbourhood, i.e., are present close to a major road having a high traffic load.

Background of the invention

Soot, or particulate matter (PM), is produced in both gasoline and diesel-powered engines.

These engines create chemical and organic compounds from the combustion of hydrocarbon-based fuels (fossil fuels). These compounds then cluster together in particle form to create soot, which is released into the air as exhaust. Soot may also be produced as the indirect by product of nitrogen oxides (NOx) and sulphur dioxides (SOx) reacting in the atmosphere. Soot's composition often includes hundreds of different chemical elements, including sulphates, ammonium, nitrates, elemental carbon, condensed organic compounds, and even carcinogenic compounds and heavy metals such as arsenic, selenium, cadmium and zinc.

One of reasons conventional diesel engines release more soot than their conventional gasoline counterparts has to do with the way fuel is injected and ignited: on gas engines, fuel is injected during the intake stroke and ignited with a spark; on diesels, fuel is injected during the compression stroke, and the fuel ignites spontaneously from the pressure. As a result, gas engines have two emissions advantages: The ignition process is more carefully controlled and the air and fuel are more thoroughly mixed before ignition occurs, thereby reducing the amount of unburned fuel.

In a conventional diesel, fuel is injected late in the cycle and the air is not as well mixed as in a gasoline engine. As a result of this less homogeneously mixed fuel and air, there are fuel-dense pockets in the combustion chamber. The consequence is that diesel engine exhaust contains incompletely burned fuel (soot) known as particulate matter.

But it's not "engine-out" pollution that really matters - it's what comes out of the tailpipe. Gasoline engines have become a lot cleaner over time through the use of add-on pollution controls, like catalytic converters. The environmental Protection Agency (EPA) has passed increasingly stricter standards for gasoline engines, and as a result, catalytic converters are now standard on every new gas car.

The real reason diesels pollute more soot is that EPA has not forced them to meet the stricter standards facing gasoline engines. The soot standard for diesel cars under EPA's Tier 1 regulation is at least ten times the average emission from a gasoline car. But under the new Tier 2 regulations, which will phase in between 2004 and 2009, diesels will finally have to meet the same strict standard as gasoline cars. Diesel cleanup technology has come a long way. From diesel particulate traps to oxidation catalysts, there are now various methods of catching or converting much of diesel pollution before it escapes the tailpipe. Starting in 2009, all diesel light trucks and cars will have to meet the same tailpipe standards as gasoline vehicles.

But new engine standards alone are not enough to protect the public from diesel pollution. New standards for diesel engines will be slowly phased in over the next 10 years. Plus, the durability of diesel engines means that older, high-polluting vehicles can continue to operate for decades. Diesel soot emissions are furthered by the fuel itself, as today's conventional diesel fuel contains significantly more sulfur than does gasoline.

The exact composition of soot is difficult to characterize because different engine technologies and conditions produce different types of soot. Indeed, the smoke clouds coming from diesel engines can even have different colours. For example, blue smoke (mainly oil and unburnt fuel) can indicate a poorly serviced and/or tuned engine; black smoke (soot, oil and unburnt fuel) can indicate a mechanical fault with the engine; and white smoke (water droplets and unburnt fuel) is produced when the engine is started from cold and may disappear when the engine warms up.

The soot in your neighbourhood may be different than the soot in someone else's hometown, but no matter the source and type, soot can present a grave health threat. As previously mentioned, soot particles either come directly from the tailpipe, or can be formed when tailpipe emissions of NOx and SOx react with atmospheric agents. Once formed, soot comes in many sizes, though all just a fraction of the width of a human hair, from coarse PM (less than 10 microns in diameter) to fine PM (less than 2.5 microns) to ultra fine PM (less than 0.1 microns). Most soot is in the fine and ultra fine categories, with ultra fine particles making up 80-95% of soot. Ultra fine particles are the most dangerous, however, as they are small enough to penetrate the cells of the lungs. Soot particles can have an environmental lifetime of one to three weeks, and they can travel long distances, journeying to communities in far regions. Soot particles have even been found at the South Pole, where no major emission source exists for thousands of miles.

But in general, soot tends to fall out of the atmosphere close to the source of the pollution. The further you are away from diesel exhaust sources, the better for your health, and vice- versa. In California, the home of the nation's largest fleet of diesel vehicles, roughly 80 percent of the state's diesel pollution sources are found in 5 of the 15 air basins. Showing that the effects of diesel soot are, mostly close to the source, about 87% of California's over $21.5 billion yearly diesel exhaust-related health care costs come from the same 5 air basins.

Premature deaths are a result of exposure to diesel particulate matter, both direct from the tailpipe and from the conversion of NOx emissions to particulates in the atmosphere. Estimates for indirect particulate exposure for each air basin are based on a conversion of NOx emissions to particulates.

As soot travels through the air in your community, you breathe it in, and so it starts the next phase of its journey: a trip through your body's respiratory system. Large soot particles (>10 microns) deposit in your nose, throat, and lungs, causing coughing and sore throat, and are ejected from your body through sneezing, coughing, and nose blowing. Coarse particles (10 microns) are inhaled into your windpipe and settle there, causing irritation and more coughing. Fine and ultra fine particles (less than 2.5 microns) are the most successful in invading your body, small enough to travel all the way down deep into your lungs.

Once there, these soot particles can irritate and mutate the most sensitive tissues in your lungs: your alveoli. These air sacs line your lung's alveolar ducts and are the primary gas exchange units of the lungs. Surrounded by networks of blood capillaries, alveoli exchange oxygen and carbon dioxide from the air you breathe in with blood in your capillaries, thus allowing your circulatory system to carry oxygen to the rest of your body. Soot particles, however, make this task more difficult as they cause inflammation and scarring of these alveoli. Scar tissue builds up and slows oxygen flow to your capillaries, straining your heart because it must work harder to compensate for oxygen loss.

Soot also finds other ways to harm your body, including causing chronic bronchitis and asthma. These conditions occur when the linings of your lung's bronchioles (air passageways) become irritated and swollen, in turn causing your lungs to create mucus to soothe the irritation. These conditions prevent your bronchioles from moving oxygen to the rest of your body. Symptoms can range from coughing and shortness of breath to severe and fatal attacks of oxygen loss. In addition, soot particles also reduce your respiratory system's ability to fight infections and remove other foreign particles.

Soot particles can also act as carriers of carcinogenic compounds into your body. Compounds in soot such as polycyclic aromatic hydrocarbons (PAHs) are carcinogenic, and diesel soot itself is classified by many government agencies as either a probable or known cancer-causing agent. For example, the California Air Resources Board has concluded that diesel soot is responsible for 70 percent of the state's risk of cancer from airborne toxics. Lastly, diesel pollution can be deadly, causing premature mortality through cancer or heart and respiratory illnesses. In the population as a whole, studies have shown a 26% increase in mortality in people living in soot-polluted cities.

Although all human beings are susceptible to soot's journey through their body, individuals with pre-existing respiratory conditions, children, and the elderly are the most vulnerable to soot's lasting and deadly effects. People with heart disease, emphysema, asthma, and chronic bronchitis suffer from increased hospital admissions and emergency room visits as a result of exposure to soot.

Children - and their developing lungs - may also suffer more acutely from breathing in diesel soot. Outdoors more often and breathing in more air per body weight than adults do, children suffer disproportionately from asthma and other respiratory conditions. Asthma is the most common chronic disease of childhood and a leading cause of disability among children; today about one in thirteen children have asthma. Elderly persons also bear a large burden when coming in contact with soot. Studies estimate that tens of thousands of elderly people die prematurely each year from exposure to ambient levels of fine PM.

In the end, soot travels far and wide to affect thousands of communities and millions of people, including you and your family. It begins in the combustion of an engine and ends up in the innermost reaches of individuals' lungs. Society pays a heavy price for soot's journey. Billions of dollars in health care costs, the loss of work and school days, and the loss of human lives create an enormous burden for society to shoulder. This burden is not a necessary one, however, as it can be lifted from off our backs with the help of stricter air regulations and cleaner engine technology.

The diesel industry is constantly innovating new solutions to clean up existing diesel engines that run for millions of miles. Employing emissions control systems and devices, owners of diesel products are able to make the most out of their investment in diesel technology. See the image to the right to view a white handkerchief test in action, a demonstration where a white handkerchief remains clean even when held in front of an exhaust pipe.

High Efficiency Diesel Particulate Filters (DPFs)

High efficiency diesel particulate filter (DPF) removes PM in diesel exhaust by filtering exhaust from the engine. The filter systems can reduce PM emissions by 80 to greater than 90 percent.

Wall-Flow Diesel Particulate Filter

High efficiency filters are effective in controlling the carbon fraction of the particulate, the portion that some health experts believe may be the PM component of the greatest concern.

Since the volume of particulate matter generated by a diesel engine is sufficient to fill up and plug a reasonably sized filter over time, some means of disposing of this trapped particulate must be provided. The most promising means of disposal is to burn or oxidize the particulate in the filter, thus regenerating, or cleansing, the filter. This is accomplished through the use of a catalyst placed either in front of the filter or applied directly on the filter, a fuel-borne catalyst, or burners which are used to oxidize or combust the collected particulate.

Flow-Through Filters

Flow-through filter technology is a relatively new method of reducing diesel PM emissions that unlike a high efficiency DPF, does not physically "trap" and accumulate PM. Instead, exhaust flows typically through a catalyzed wire mesh or a sintered metal sheet that includes a torturous flow path, giving rise to turbulent flow conditions. Any particles that are not oxidized within the flow-through filter flow out with the rest of the exhaust. So far, there have been limited commercial use of the flow-through filters but there is an increasing interest in this technology due to its ability to significantly reduce PM emissions from older, "dirtier" diesel engines.

Flow-through systems are capable of achieving PM reduction of about 30 to 70 percent.

Diesel Oxidation Catalysts (DOCs)

Like catalytic converters already used on all new gasoline vehicles, diesel oxidation catalysts (DOCs) cause chemical reactions to reduce emissions without being consumed and without any moving parts.

Internal combustion engines have been used in cars, trucks, locomotives and other motorized machinery for about 100 years. Engine exhausts contain thousands of gaseous and particulate substances. The major gaseous products of both diesel- and gasoline- fuelled engines are carbon dioxide and water, but lower percentages of carbon monoxide, sulfur dioxide and nitrogen oxides as well as low molecular weight hydrocarbons and their derivatives are also formed. Submicron-size particles are present in the exhaust emissions of internal combustion engines. The particles present in diesel engine exhaust are composed mainly of elemental carbon, adsorbed organic material and traces of metallic compounds. The particles emitted from gasoline engines are composed primarily of metallic compounds (especially lead, if present in the fuel), elemental carbon and adsorbed organic material. Soluble organic fractions of the particles contain primarily polycyclic aromatic hydrocarbons, heterocyclic compounds, phenols, nitroarenes and other oxygen- and nitrogen-containing derivatives.

The composition and quantity of the emissions from an engine depend mainly on the type and condition of the engine, fuel composition and additives, operating conditions and emission control devices. Particles emitted from engines operating with gasoline are different from diesel engine exhaust particles in terms of their size distribution and surface properties. Emissions of organic compounds from gasoline (leaded and unleaded) and diesel engines are qualitatively similar, but there are quantitative differences: diesel engines produce two to 40 times more particulate emissions and 20-30 times more nitroarenes than gasoline engines with a catalytic converter in the exhaust system when the engines have similar power output. Gasoline engines without catalytic converters and diesel engines of similar power output produce similar quantities of polycyclic aromatic hydrocarbons per kilometre; catalytic converters of the type used with gasoline vehicles reduce emissions of polycyclic aromatic hydrocarbons by more than ten times. Lead and halogenated compounds are also typically found in emissions from engines using leaded gasoline.

In urban areas, exposures to low levels and short-term peak levels of engine exhausts are ubiquitous. Higher exposures to engine exhausts may occur in some occupations, such as transportation and garage work, underground mining, vehicle maintenance and examination, traffic control, logging, firefighting and heavy equipment operation. The components of exhaust most often quantified in an occupational setting are particles, carbon monoxide and oxides of nitrogen; polycyclic aromatic compounds and aldehydes from engine exhausts have also been measured in work environments.

The exhausts of engines share similar physical and chemical characteristics with airborne materials from many sources. This makes it difficult to quantify the portion of an individual's exposure from the general environment that derives directly from engine exhausts and also complicates assessment of occupational exposures to engine exhausts.

Diesel engine exhaust particles or extracts of diesel engine exhaust particles

In other studies, organic extracts of diesel engine exhaust particles were used to evaluate the effects of concentrates of the organic compounds associated with carbonaceous soot particles. These extracts were applied to the skin or administered by intratracheal instillation or intrapulmonary implantation to mice, rats or Syrian hamsters. An excess of skin tumours was observed in mice in one study by skin painting and in one series of studies on tumour initiation using extracts of particles from several different diesel engines. An excess of lung tumours was observed in one study in rats following intrapulmonary implantation of beeswax pellets containing extracts of diesel engine exhaust particles.

In one study, an excess of tumours at the injection site was observed following subcutaneous administration of diesel engine exhaust particles to mice.

Studies of workers whose predominant engine exhaust exposure is that from diesel engines

In the two most informative cohort studies (of railroad workers), one in the USA and one in Canada, the risk for lung cancer in those exposed to diesel engine exhaust increased significantly with duration of exposure in the first study and with increased likelihood of exposure in the second (in which smoking was not considered). Three further studies of cohorts with less certain exposure to diesel engine exhaust were also considered; two studies of London bus company employees showed elevated lung cancer rates that were not statistically significant, but a third, of Swedish dockers, showed a significantly increased risk for lung cancer.

In only two case-control studies of lung cancer (one of US railroad workers and one in Canada) could exposure to diesel engine exhaust be distinguished satisfactorily from exposures to other exhausts; modest increases in risk for lung cancer were seen in both, and in the first the increase was significant. In three further case-control studies, in which exposure to diesel engine exhaust in professional drivers and lung cancer risks were addressed, the Working Group considered that the possibility of mixed exposure to engine exhausts could not be excluded. None of these studies showed a significant increase in risk for lung cancer, although the risk was elevated in two.

In the three cohort studies (on railroad workers, bus company workers and 'dockers', respectively) in which bladder cancer rates were reported, the risk was elevated, although not significantly so. Four of the case-control studies of bladder cancer were designed to examine groups whose predominant engine exhaust exposure was assumed to be to that from diesel engines. Three showed a significantly increased risk for bladder cancer. In one of these, the large US study, a significant trend was also seen with duration of exposure; and in an analysis of one subset of self-reported diesel truck drivers, a substantial, significant relative risk was seen for bladder cancer.

A '"diesel particulate filter'", sometimes called a "¹DPF'", is device designed to remove diesel particulate matter or soot from the exhaust gas of a diesel engine, most of which are rated at 85% efficiency, but often attaining efficiencies of over 90%. A diesel-powered vehicle with a filter installed will emit no visible smoke from its exhaust pipe, as >99% have a particle size of less than 1 μm (visible particles have a size of more than 30 μm).

In addition to collecting the particulate, a method must be designed to get rid of it. Some filters are single use (disposable), while others are designed to burn off the accumulated particulate, either through the use of a catalyst (passive), or through an active technology, such as a fuel burner which heats the filter to soot combustion temperatures, or through engine modifications (the engine is set to run a certain specific way when the filter load reachs a pre-determined level, either to heat the exhaust gasses, or to produce high amounts of nitrogen oxide|NO₂, which will oxidize the particulates at relatively low temperatures). This procedure is known as "filter regeneration." Fuel sulphur interferes with many "Regeneration" strategies, so almost all jurisdictions that are interested in the reduction of particulate emissions, are also passing regulations governing fuel sulphur levels. Particulate filters have been in use on non-road machines since 1980, and in automobiles since 1996. Diesel engines during combustion of the fuel/air mix produce a variety of particles generically classified as diesel particulate matter due to incomplete combustion. The composition of the particles varies widely dependent upon engine type, age, and the emissions specification that the engine was designed to meet, two-stroke diesel engines produce more particulate per horsepower output than do four-stroke diesel engines, as they less completely combust the fuel-air mix.

Historically diesel engine emissions were not regulated until 1987 when the first California Heavy Truck rule was introduced capping particulate emissions at 0.60 G/BHP Hour. Since then progressively tighter standards have been introduced for diesel engines.

While particulate emissions from diesel engines was first regulated in the United States, similar regulations have also been adopted by the European Union, most Asian countries, and the rest of North and South America.

While no jurisdiction has made filters mandatory, the increasingly stringent emissions regulations that engine manufactures must meet mean that eventually all on-road diesel engines will be fitted with them. Neither the American 2007 heavy truck engine emissions regulations or the European Union 2007 automobile regulations can be met without filters. PSA Peugeot was the first company to make them standard fit on passenger cars, in anticipation of the future Euro V regulations.

It is expected that non-road diesel engines will be regulated in a similar manner.

As of July 2006 the California Air Resources Board is looking at introducing regulations that will require retrofit of all diesel engines operating in the state by the year 2013. Other jurisdictions may also do this. A variety of retrofit programs have been done:

2002 - In Japan the Prefecture of Tokyo passed a law banning trucks without filters from entering the city limits.

2003 - Mexico City started a program to retrofit trucks 2001 - Hong Kong retrofit program 2004 - New York City retrofit program (non-road) Variants of DPFs

Unlike a catalytic converter which is a flow-through device, a DPF cleans exhaust gas by forcing the gas to flow through the filter. There are a variety of diesel particulate filter technologies on the market. Each is designed around similar requirements:

# Fine filtration

# Minimum pressure drop

# Low cost

# Mass production suitability # Product durability

Cordierite wall flow filters

The most common filter is made of cordierite (a ceramic material that is also used as catalytic converter supports (= cores)). Cordierite filters provide excellent filtration efficiency, are (relatively) inexpensive, and have thermal properties that make packaging them for installation in the vehicle simple. The major drawback is that cordierite has a relatively low melting point (about 1200⁰C) and cordierite substrates have been known to melt down during filter regeneration. This is mostly an issue if the filter has become loaded more heavily than usual, and is more of an issue with passive systems than with active systems, unless there is systems break down.

Cordierite filter cores look like catalytic converter cores that have had alternate channels plugged - the plugs force the exhaust gas flow through the wall and the particulate collects on the inlet face.

Silicon carbide wall flow filters

The second most popular filter material is silicon carbide, or SiC. It has a higher (1700⁰C) melting point than cordierite, however it is not as stable thermally, making packaging an issue. Small SiC cores are made of single pieces, while larger cores are made in segments, which are separated by special cement so that heat expansion of the core will be taken up by the cement, and not the package. SiC cores are usually more expensive than cordierite cores, however they are manufactured in similar sizes, and one can often be used to replace the other.

Silicon carbide filter cores also look like catalytic converter cores that have alternate channels plugged - again the plugs force the exhaust gas flow through the wall and the particulate collects on the inlet face. Metal fibre flow through filters

Some cores are made from metal fibres - generally the fibres are "woven" into a monolith. Such cores have the advantage that a current can be passed through the monolith to heat the core for regeneration purposes. Metal fibre cores tend to be more expensive than cordierite or silicon carbide cores, and generally not interchangeable with them.

Partial filters

There are a variety of devices that produce over 50% particulate matter filtration, but less than 85%. Partial filters come in a variety of materials. The only commonality between them is that they produce more back pressure than a catalytic converter, and less than a diesel particulate filter. Partial filter technology is popular for retrofit.

Filter usage A properly designed filter will have little effect on fuel usage, however improper installation can be catastrophic, which is why automobile and truck engine manufacturers have avoided the use of filter technology until now. It was first offered as standard by the French manufacturer PSA Peugeot Citroen in early 2000, and has been a huge success.

Maintenance

Filters require more maintenance than catalytic converters. Engine oil ash builds up on the surface of the inlet face of the filter, and will eventually clog the pores. This increases the pressure drop over the filter, which when it reaches 100 inches of water or higher is capable of causing engine damage. Regular filter maintenance is a necessity.

Regeneration

Regeneration is the process of removing the accumulated soot from the filter. This is done either passively (by adding a catalyst to the filter) or actively. On-board active filter management can use a variety of strategies, such as engine management to increase exhaust temperature, fuel burner to increase the exhaust temperature, catalytic oxidizer to increase the exhaust temperature, resistive heating coils to increase the exhaust temperature, microwave energy to increase the exhaust temperature

All on-board active systems use extra fuel, whether through burning to heat the DPF, or providing extra power to the DPF's electrical system. Typically a computer monitors one or more sensors that measure back pressure and/or temperature, and based on preprogrammed set points the computer makes decisions on when to activate the regeneration cycle. The additional fuel can be supplied by a metering pump. Running the cycle too often while keeping the back pressure in the exhaust system low, will use extra fuel. The reverse runs risk of engine damage and/or uncontrolled regeneration and possible DPF failure. Quality regeneration software is a necessity for longevity of the active DPF system.

Diesel particulate matter combusts at when temperaures above 600 degrees celsius are attained. The start of combustion causes a further increase in temperature. In some cases the combustion of the particulate matter can raise temperatures above the structural integrity threshold of the filter material, which can cause catastophic failure of the substrate. Various strategies have been developed to limit this possibility. Note that unlike a spark- ignited engine, which typically has less that 0.5% oxygen in the exhaust gas stream before the emission control device(s), many diesel engines run above 15% oxygen pre-filter. While the amount of available oxygen makes fast regeneration of a filter possible, it also contributes to run away regeneration issues.

SE-C-513 391 discloses a device for complete combustion of solid fuels and comprises two combustion chambers joined together, of which one is a combustion chamber for drying and gasification of the fuel and the second one is a final combustion chamber for combustion of the gasified fuel and whereby a ceramic filter is arranged as a partition wall between the chambers, which filter allows the gasified fuel to pass through but blocks remaining solid substance to pass into the final combustion chamber and whereby the combustion gas is forced to pass the ceramic filter whereby the combustion temperature is raised to a suitable combustion temperature. This device is meant to replace a conventional furnace.

NO-C-131 ,325 relates to a device for separating solid particles from a gas stream by direct the gas from a source to a mixing chamber where a mixture of steam and atomized liquid droplets are introduced under such conditions that the liquid droplets are accelerated to a speed of at least 60 m/s over the inlet speed, whereby solid particles are caught by the liquid droplets, whereby a subpressure is obtained in the mixing chamber. The invention is thereby related to a ration between steam and atomized droplets.

US-A-6,019,819 relates to a device catching a condensate, which condensate contains oil and other hydrocarbons from food processing, such as French frying potatoes. WO 99/56854 relates to a process for separating particles from a flow of hot gas whereby the relative humidity is primarily increased to almost saturation, then gas and particles are cooled adiabatically so that water condenses upon the particles whereupon the particle containing water is separated off.

EP-A-O 1 10 438 relates to a process and a device for purification of particle containing gas by means of condensation of water onto the particles in the gas and a separation of water droplets comprising particles.

As evident from the attached FIG. A the distribution of particles derived from a diesel engine is quite wide. Thus they range all the way from nuclei mode (10 nm) to coarse mode 10000 nm), whereby the large mass of particles is concentrated around 100 nm.

However, there is a great demand for a completion of existing particles removing systems to reduce emissions of toxic particulates from in particular diesel engines, either mobile or stationary, as well as a complete cleansing of ventilation air.

Nothing in the prior art discussed above can provide this.

Summary of the present invention

The present invention relates to a device for the elimination of particles from gaseous media, characterized by comprising a first pass-way having a first inlet for gaseous medium comprising minute particulate material, a means compressing the said gaseous medium bringing the fraction containing said particulate material to a return pass-way bringing said particles contained in the fraction of particulate material into agglomeration, a collecting means for collecting said agglomerated particles, a particle withdrawing means to eliminate said collected agglomerated particles, as well as those already being large, and a particulate purified gas outlet.

In a preferred embodiment of the invention the means comprises a series of open truncated cones of subsequently smaller diameters ending in a a return pass-way bringing said particles contained in the fraction of particulate material into agglomeration. In a preferred embodiment of the invention it comprises a first pass-way having a first iniet for gaseous medium comprising minute particulate material, comprising a pass-way to separate the particulate material into two fractions containing larger and smaller particles, respectively, a means compressing the said gaseous medium bringing the fraction containing said smaller particulate material, and a return pass-way bringing said particles contained in the fraction of smaller particulate material into agglomeration, a collecting means for collecting said agglomerated particles and said fraction containing larger particles, a particle withdrawing means to eliminate said collected agglomerated and larger particles, and a particulate purified gas outlet.

In a preferred embodiment it comprises a first pass-way having a first inlet for incoming gaseous medium, said pass-way ending at a first open cone like means, the first open cone like means opening into a second open truncated cone oppositely turned and spaced from the first truncated cone, said first cone and second truncated cone forming a separation means for forming two fractions, one first fraction containing larger particulate material, and one second fraction containing smaller particulate material, respectively, the second truncated open cone opening into a compressing means being provided in the vicinity of the said opening, allowing non-agglomerated particles of said second fraction to be returned via a tube forming a return pass-way, whereby said return tube is arranged to bring particles of the fraction containing smaller particles in a renewed contact for agglomeration, whereby agglomerated particles are arranged to become withdrawn from a collecting space at said first truncated cone after separation into said two fractions and particulate purified gases with regard to particulate material are arranged to become withdrawn from the device in an outlet.

In a preferred embodiment it comprises a first pass-way having a first inlet for incoming gaseous medium, said pass-way ending at a first open cone like means, the first open cone like means opening into a second open truncated cone oppositely turned and spaced from the first truncated cone, said first cone and second truncated cone forming a separation means for forming two fractions, one first fraction containing larger particulate material, and one second fraction containing smaller particulate material, respectively, the second truncated open cone opening into a tubular means optionally provided with a helical pathway forcing any gases passing said helix to change direction thereby providing for removing said non-agglomerated particles from said end of said collecting wall and returning those particles via a tube forming a return pass-way, whereby said return tube is arranged to bring particles of the fraction containing smaller particles in a renewed contact for renewed agglomeration, whereby agglomerated particles are arranged to become withdrawn from a collecting space at said first truncated cone after separation into said two fractions and particulate purified gases with regard to particulate material are arranged to become withdrawn from the device in an outlet.

In a preferred embodiment the perforated wall is arranged at the outer periphery of the helix and is forming an outer perforated wall, said outer wall being connected to said return tube being arranged to bring particles of the fraction containing remaining smaller particles in a renewed contact for agglomeration, whereby agglomerated particles are arranged to become withdrawn from a collecting space at said first truncated cone after separation into said two fractions and particulate purified gases with regard to particulate material are arranged to become withdrawn from the device in an outlet.

In a preferred embodiment the perforated wall is centrally arranged onto a tubular means, optionally provided with a helical means, said tubular means being connected to said return tube being arranged to bring particles of the fraction containing smaller particles in a renewed contact for renewed agglomeration, whereby agglomerated particles are arranged to become withdrawn from a collecting space at said first truncated cone after separation into said two fractions and particulate purified gases with regard to particulate material are arranged to become withdrawn from the device in an outlet.

In a preferred embodiment said particulate material is returned via the pass-way by means of a particulate suction means driven by the gaseous medium.

In a preferred embodiment said particulate material is returned via the pass-way by means of a particulate suction means driven by the induction air of an engine.

In a preferred embodiment it is arranged for agglomeration and collection of particles having a particle size less than 1 μm, preferably less than 0,5 μm, more preferably less than 0,3 μm, further more preferably less than 0,2 μm, which particles after agglomeration have a particle size of at least 15 μm, preferably 10 μm, more preferably 6 μm, whereby that the device further catches and makes the agglomerated particles subject to an elimination. In a preferred embodiment said first fraction containing larger particles contains particles having a particle size of at least 6 μm, preferably 10 μm, more preferably 15 μm, and wherein said second fraction containing smaller particles having a particle size less than 1 μm, preferably less than 0,5 μm, more preferably less than 0,3 μm, further more preferably less than 0,2 μm.

In a further aspect of the invention it relates to a method for the elimination of particles from gaseous media, characterized by passing said gaseous media into a first pass-way having a first inlet for gaseous medium comprising minute particulate material, separating the particulate material into two fractions containing larger and smaller particles, respectively, in a second pass-way, compressing the said gaseous medium bringing the fraction containing said smaller particulate material in a means, and bringing said particles contained in the fraction of smaller particulate material into agglomeration a return pass-way, collecting said agglomerated particles in a collecting means, withdrawing the particles contained in said fraction containing larger particles, and passing the purified gas to an outlet.

The term minute particle refers to particles having a size of less than 2 μm.

Detailed description of the present invention

The present invention will now be described in more detail with reference to the accompanying drawing, however, without being restricted to this or the embodiment being related thereto, in which drawing

FIG. A shows the distribution of particles derived from a diesel engine

FIG. B shows an EDX picture of a particle found in air of combustion

FIG. 1 shows a schematic longitudinal cross-sectional view of a device according to a first preferred embodiment of the invention, FIG. 2 shows a schematic longitudinal cross-sectional view of a device according to a second preferred embodiment of the invention,

FIG. 3 shows a general application of the invention when treating off-gases from a car, FIG. 4 shows a general application of the invention when treating off-gases from a truck, FIG. 5 shows a general application of the invention when treating off-gases from a combustion plant via chimney, and

FIG. 6 shows a general application of the invention when treating ventilation gases. In the device according to FIG. 1 the first embodiment shows first inlet 1 , preferably in the form of a tube having any suitable cross-section from a combustion plant, or ventilation system. In the inlet 1 there is provided a series of open truncated cones 5, whereby the cones have subsequently smaller diameters and ending up in a particle pass-way 9. The cones 5 are arranged with a distance between each of them to form pass-ways in between the cones. The particle pass-way 9 is connected to a suction source for withdrawing the minute particles carried by the gaseous medium stream introduced into said inlet 1. When the gaseous medium is compressed into the smaller cones the superfluous amount of gaseous medium will pass out between the cones while the particles due to their weight will end up in the opening of the particle pass-way 9. The particles in the pass-way 9 will then, due to the velocity, agglomerate into larger particles, and the agglomerated particles together with a size already of considerably size, will be withdrawn from the pass-way and optionally be destroyed or otherwise eliminated. The tube ends with an outlet 16.

The suction source 9 may consist of a pump 31 as well, which sucks particle containing gas to either a combustion source, or a deposit source A 32, or when a more complete agglomeration is at hand, for direct disposal depending on the situation. Thus combustion is not to be recommended when it comes to air ventilation as the risk for back fire is at hand.

In the device according to FIG. 2 there is a first inlet 1 preferably in the form of a tube having any suitable cross-section from a combustion plant, such as an internal combustion engine, in particular a diesel engine. In the inlet there is provided conical part 2 having its point facing the inlet opening 1 and having an open interior, which cone reduces the cross- section of the inlet 1. Inside the conical part 2 there is first conical part 3 arranged which truncated part opens into the conical interior part of part 2. The conical part 2 and the first truncated conical part 3 are placed at some distance from each other to provide for a through going flow. The first truncated cone 3 having its point facing the interior of the conical part 2 is preferably provided with a second truncated open cone 4 facing the opposite way to the first part 2. The second truncated cone 4 opens into a funnel 5 at some distance from the mouth of the second truncated cone 4 whereby the funnel 5 ends into a pass-way 9. This pass-way 9 allows for an agglomeration, but will also allow for remaining small particles to become sucked back into the inlet 1 as the pass-way 9 is connected as a return tube. The agglomerated particles will become separated off as mentioned below, while the fraction of smaller particles will travel through for a renewed agglomeration action. The first and second truncated conical parts 2 and 3 are attached to the walls of the inlet tube 1 , whereby the walls of the first truncated cone 3 closes towards the wall of the inlet 1. In the vicinity of the said walls of the said truncated cone 3 there is a collecting rim 21 into which particles of larger dimension and forming a first fraction of larger particles are separated off and are withdrawn from the collecting rim 21 by means of a suction force, such as created by a vacuum pump. This withdrawal may take place continuously or intermittently via a valve 22.

In operation exhaust gases are passed into the first inlet 1 and are represented by the arrows pointing rightwards. During the compression of the cross section at the conical parts as well as in the pass-way 9 minute particles will become agglomerated into particles having a size of 10 microns or more. The particles being relatively heavy are collected onto the first truncated conical part 2, while the gases proceed through the second truncated cone 4.

The exhaust gases being freed of particles are disposed of in an outlet 16, such as an exhaust manifold.

To remove the agglomerated particles collected at the rim of the first truncated conical part 2, suction is applied onto the suction chamber 11 , the valve 22 is turned open and the particles are sucked off from the rim into the outlet tube 10 and into the sack filter. Hereby particles having a particle size of greater than 5 microns are collected.

In this way an efficient agglomeration and removal of minute particles in smoke and exhausts gas is removed.

In stead of the particle deposit sack filter the suction chamber may connected directly to the inlet manifold of an internal combustion engine, such as a diesel engine. Quite often the inlet manifold and the exhaust pipe are localized close to each other on the rear of a truck compartment and thus it can be quite easily done to connect these parts.

As evident from above the particles, after combustion and agglomeration have a particle distribution exceeding 5 μm, which can be simple separated off.

The present invention is used for eliminating particles from gaseous media including smoke and exhaust gases as well as air, such as ventilation air, whereby in the latter case microscopic particles, such as allergens, bacteria and virus can be eliminated, and air of combustion comprising a lot of ground and soil derived particles (cf. FIG. B). The analysis of the particle shown in the EDX picture shows that it contains substantial amounts of sulphur (S) and silicon (Si), whereby the amounts of magnesium (Mg), titanium (Ti), copper (Cu), and zinc (Zn) are low.

In FIGs 3 to 6 some different general applications are shown. In these general embodiments the detail of the particle catcher shown in FG. 1 and/or FIG. 2 are not shown, but as a box 100 only.

In FIG. 3 the off-gases of a car are treated in the box 100, whereby the particles caught are eliminated via a particle suction device 101 from a particle container 102 connected to the box 100. The purified off-gases are then removed via two silencer 103a and 103b.

In FIG. 4 the off-gases from a truck, bus or other heavy vehicle is treated in the box 100, the purified off-gases are disposed off in the silencer 104, the particles are collected in the particle container 105 to which they been brought via particle outlet 106 from the box 100. The return gases from the particle container 105 are disposed off in the air inlet tube 1 16 of the motor 107.

FIG. 5 shows a chimney inlet 108 leading up to the box 100, first agglomerated particles are returned to a burning unit 109, while non-agglomerated particles are caught and agglomerated in an upper agglomerator 1 10, and transferring gas is returned via return tube 1 11 for further agglomeration and burning in the burning unit 109. Purified gases are disposed off in the chimney 117.

FIG. 6 shows a purifier of ventilation air where the air containing particles are brought to the unit via an inlet 112, are treated in the box 100, the particles caught are brought to the particle container 1 13, and the purified air is brought back to the space 1 18 from which was transferred, such as an airplane cockpit and passenger space, clean room, a work shop, such as a welding station, or any other room such as in contaminated places. An auxiliary air to the particle container may lead off from the outlet area 114 via a tube 115.

Claims

1. Device for the elimination of particles from gaseous media, characterized by comprising a first pass-way (1) having a first inlet (2) for gaseous medium comprising minute particulate material, a means (2, 3, 4, 5) compressing the said gaseous medium bringing the fraction containing said particulate material to a return pass-way (9) bringing said particles contained in the fraction of particulate material into agglomeration, a collecting means (21 ) for collecting said agglomerated particles, a particle withdrawing means to eliminate said collected agglomerated particles including those already being large, and a particulate purified gas outlet (16).

2. Device according to claim 1 , wherein the means (5) comprises a series of open truncated cones of subsequently smaller diameters ending in a a return pass-way

(9) bringing said particles contained in the fraction of particulate material into agglomeration.

3. Device according to claim 1 for the elimination of particles from gaseous media, characterized by comprising a first pass-way (1 ) having a first inlet (2) for gaseous medium comprising minute particulate material, comprising a pass-way (3, 4) to separate the particulate material into two fractions containing larger and smaller particles, respectively, a means (5) compressing the said gaseous medium bringing the fraction containing said smaller particulate material, and a return pass-way (9) bringing said particles contained in the fraction of smaller particulate material into agglomeration, a collecting means (21 ) for collecting said agglomerated particles and said fraction containing larger particles, a particle withdrawing means to eliminate said collected agglomerated and larger particles, and a particulate purified gas outlet (16).

4. Device according to claim 1 , wherein it comprises a first pass-way (1 ) having a first inlet for incoming gaseous medium, said pass-way ending at a first open cone (2) like means, the first open cone like means (2) opening into a second open truncated cone (5) oppositely turned and spaced from the first truncated cone (2), said first cone (2) and second truncated cone (5) forming a separation means for forming two fractions, one first fraction containing larger particulate material, and one second fraction containing smaller particulate material, respectively, the second truncated open cone (5) opening into a compressing means (9) being provided in the vicinity of the said opening, allowing non-agglomerated particles of said second fraction to be returned via a tube (9) forming a return pass-way, whereby said return tube (9) is arranged to bring particles of the fraction containing smaller particles in a renewed contact for agglomeration, whereby agglomerated particles are arranged to become withdrawn from a collecting space (21 ) at said first truncated cone (2) after separation into said two fractions and particulate purified gases with regard to particulate material are arranged to become withdrawn from the device in an outlet (16).

5. Device according to claim 2, wherein said particulate material is returned via the pass-way (9) by means of a particulate suction means driven by the gaseous medium.

6. Device according to claim 3, wherein said particulate material is returned via the pass-way (9) by means of a particulate suction means driven by the induction air of an engine.

7. Device according to one or more of claims 1-6, wherein it is arranged for agglomeration and collection of particles having a particle size less than 1 μm, preferably less than 0,5 μm, more preferably less than 0,3 μm, further more preferably less than 0,2 μm, which particles after agglomeration have a particle size of at least 6 μm, preferably 10 μm, more preferably 15 μm, whereby that the device further catches and makes the agglomerated particles subject to an elimination.

8. Device according to claim 1 , wherein said first fraction containing larger particles contains particles having a particle size of at least 6 μm, preferably 10 μm, more preferably 15 μm, and wherein said second fraction containing smaller particles having a particle size less than 1 μm, preferably less than 0,5 μm, more preferably less than 0,3 μm, further more preferably less than 0,2 μm.

9. Method for the elimination of particles from gaseous media, characterized by passing said gaseous media into a first pass-way (1 , 21 ) having a first inlet (2) for gaseous medium comprising minute particulate material, separating the particulate material into two fractions containing larger and smaller particles, respectively, in a second pass-way (3, 4), compressing the said gaseous medium bringing the fraction containing said smaller particulate material in a means (2, 3, 4, 5), and bringing said particles contained in the fraction of smaller particulate material into agglomeration a return pass-way (9), collecting said agglomerated particles in a collecting means (21), withdrawing the particles contained in said fraction containing larger particles, and passing the purified gas to an outlet (16).