US20060021337A1

US20060021337A1 - Diesel emissions filtering system and method

Info

Publication number: US20060021337A1
Application number: US11/074,595
Authority: US
Inventors: William Brady
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-03-08
Filing date: 2005-03-08
Publication date: 2006-02-02

Abstract

The invention is embodied in an emission control system for reducing diesel particulate matter (DPM) from diesel engine exhaust gases comprising an aqueous filter apparatus constructed and arranged to form a water bath for all exhaust gas output from the engine and including in the water bath a preselected significant quantity of a low foaming wetting composition having a high affinity for hydrocarbons. The invention is further embodied in a diesel emissions filtering method including pre-filtering diesel fuel and removing DPM from exhaust gases by filtration through an aqueous solution having a low foaming wetting composition.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a non-provisional of U.S. application Ser. No. 60/551,086, filed Mar. 8, 2004, the entire disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates generally to diesel fuel control systems, and more particularly to diesel systems and methods for reducing hydrocarbon and diesel particulate matter levels in diesel exhaust emissions to assure safe environmental operation of diesel engines.
2. Description of the Prior Art
Internal combustion engines are designed to operate most efficiently on standard quality fuels, and the presence of impurities or non-combustible contaminates may result in poor engine performance or impairment as well as produce higher levels of exhaust impurities. Even small quantities of water in diesel fuel may prevent satisfactory operation of a diesel engine, and most diesel engines now have some type of water-separator in addition to filters for removing sediment or other solids that may have been introduced into the fuel tank. It is also now known that the presence of air entrained in diesel fuel delivered to a fuel injection system results in poorer engine performance since the amount of air required for optimum combustion is already precisely controlled by the fuel injection system itself. It is thus clear that the presence of these non-fuel contaminates in a diesel fuel delivery system result in poor engine performance with the extended result of less complete fuel burning and an increase in deleterious exhaust pollutants.
During operation diesel engines produce various exhaust pollutants including unburned hydrocarbons, carbon and nitrogen oxides, sulfurous gases and other particulate matter generally called “diesel particulate matter” (DPM). Aside from the environmental interests in reducing such air pollution generally, there is an absolute necessity of doing so in certain diesel operating environments. There is a prevalent use of diesel engine powered equipment in fiery gaseous mining applications where methane gas is present; and the Federal government, through the Mine Safety Health Administration (MSHA), has set rigid regulations for the design and operation of such diesel engines (particularly for class 32 machinery that operates underground in the vicinity of the mining cut—as opposed to class 24 equipment which operates outby or outdoors in fresh air). Thus the preparation or modification of diesel engines for use in class 32 gaseous applications has reference to flame paths, skin temperatures of engine and attachments, final exhaust temperatures and final exhaust gas emission analysis and shut-down systems.
A primary troublesome area has been the control of exhaust gas emissions, and the Federal government has heretofore mandated the use of “soot trap filters” to reduce DPM emissions exhaust levels by filtering hydrocarbons out of the diesel exhaust gases. However, the use of dry filter soot traps on the end of a diesel exhaust has generally posed a fire hazard problem irrespective of what the filter material (steel, fibreglass, ceramic, etc.) is made of, since the accumulation of DPM hydrocarbons at normal engine and exhaust operating temperatures may cause an explosion in a gaseous coal mine. For instance, diesel engine combustion temperatures may be 800°-1100° F., so significant engine and exhaust pipe cooling should be effected to reduce gas emissions temperatures below the ignition temperature of hydrocarbon accumulations in the soot trap. High exhaust gas temperatures are especially hazardous in the operation of class 32 diesel engines in coal mines or like closed environments where methane gas may be present since methane has an ignition temperature of 302° F. In past practice, the exhaust lines from class 32 diesel engines have been insulated with “Thermogram” or the like so that the high (800° F.) combustion temperature would be carried by diesel exhaust gases past the catalytic converter to the soot trap thus producing the probability of fires and/or explosions therein with the result that mine operators refuse to use the mandated soot traps for safety reasons and generally continue to operate under violation citations from the Mine Safety and Health Administration (MSHA), which recognizes the danger and reason for the continuing violation.
It has been reported that the mandated dry soot traps are still fire hazards even after the engine is shut off because oxygen will flow from ambient back into the hot trap and ignite the carbon/hydrocarbon DPM accumulation therein. In short, any dry soot trap per se almost always poses a fire hazard and, in addition, soot traps are labor intensive and expensive.
In the past the foregoing fire hazard problem has been approached by attempting to provide exhaust gas cooling means, generally in the form of a so-called gas scrubber consisting of a body of water into which the exhaust gases were passed and cooled. Typical of the prior art directed to such water scrubbers are the following U.S. Pat. No. 3,957,467 granted May 18, 1976 (Kim); U.S. Pat. No. 3,976,456 granted Aug. 24, 1976 (Alcock); and U.S. Pat. No. 4,190,629 granted Feb. 26, 1980 (Strachan). However, the apparatus of these patents primarily only cools the exhaust gas, but has no other major effect since only a small portion of DPM matter will be trapped in plain hard mine water, and also no significant carbon monoxide will be removed. The Kim U.S. Pat. No. 3,957,467 states that a gas purification liquid may be used and, in addition to water alone, it is suggested that aqueous solutions may include other non-specific additives such as detergent, surfactant or wetting agents, alcohol, glycol or alkalis.

SUMMARY OF THE INVENTION

The invention is embodied in an emission control system for cleaning diesel particulate matter (DPM) from diesel engine exhaust gases and comprising an aqueous filter apparatus forming a water bath having a major water portion with a minor portion of super-wetting agent (“wetting composition”) having a high affinity for hydrocarbons. The invention is further embodied in a diesel emissions filtering method including the features of pre-filtering diesel fuel, and removing DPM from diesel exhaust gases comprising filtering such gases through an aqueous solution having a minor portion of a low foam super-wetting agent, and finally filtering the exhaust gases.
A principal object of the invention is to provide systems, apparatus and methods for removing significant amounts of diesel particulate matter from diesel exhaust gases prior to final discharge thereof to ambient.
Another object is to substantially reduce carbon monoxide levels in the final emission gases prior to discharge to ambient.
An object of the invention is to provide a diesel filtering method comprising pre-filtering diesel fuel to remove non-combustible matter upstream of the engine, removing DPM and carbon monoxide from diesel exhaust gases downstream of the engine, and final filtering the exhaust gases before discharge to ambient.
Another object of the invention is to provide more effective ways of removing DPM and carbon monoxide matter from diesel exhaust gases using low cost systems and equipment and labor saving methods.
It is another objective to greatly improve the working environment around diesel powered equipment, particularly in coal mines and like underground sites with potential methane gas or other hazardous gas presence.
Another object is to provide exhaust gas scrubber systems and methods that are effective in removing DPM matter and carbon monoxide from diesel exhaust gases prior to passing to a final filter, as presently mandated by MSHA, and which will thereby prolong the useable life and reduce the costs of using such final filters. It is a still further object to provide such systems, apparatus and methods whereby the present requirements for final exhaust filters may be changed in recognition that such final filters are no longer needed.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings wherein like numerals refer to like parts wherever they occur:
FIG. 1 is a diagrammatic view showing a diesel engine fuel system embodying one aspect of the invention from fuel tank to emissions exhaust;
FIG. 2 is an enlarged diagrammatic view of the emissions exhaust filtering section of the system.
FIG. 3 is a diagrammatic view illustrating another embodiment of an emissions exhaust filtering section of the invention;
FIG. 4 is another diagrammatic view showing a further embodiment of the exhaust filtering section; and
FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the diagrammatic overview of a diesel fuel system of the invention as shown in FIG. 1, this system includes a fuel delivery section FD between the fuel tank 10 and the diesel engine 12 and an emissions exhaust section EE from the engine 12 to ambient.
One feature of the invention is to deliver a substantially pure diesel fuel to the engine, i.e., fuel that is free from air, water and other unwanted gases or non-combustible contaminates. Thus, in the preferred embodiment, the fuel delivery section FD of the diesel system includes fuel pre-filtration means including a water filtration or separator unit 14 connected by fuel line 15 to the fuel tank 10, and a particle filtration unit 18 connected in line 17 through fuel pump 20 to the water filter 14. In this preferred embodiment the water filter unit 14 and particle filter unit 18 form a primary or initial fuel filter means 21, and a secondary fuel filter means 22 is connected through a flow rate regulator valve 24 in line 23 to the primary filtration means 14, 18.
The secondary fuel filter 22 includes a vessel 26 having an interior separation chamber 27 constructed and arranged to fluidically connect through delivery line 28 to the fuel injection system (not shown) for the engine 12, and also has a return line 29 connecting back to the fuel tank 10. An air purge means (not shown) can be provided at the top of the vessel 26 to bleed air out of the fuel delivery system. U.S. Pat. Nos. 5,746,184 and 5,355,860 are incorporated by reference as disclosing features of one suitable pre-filtration means of the fuel delivery section FD in greater detail.
In operation, the fuel delivery section FD provides for the positive delivery of diesel fuel from the fuel tank 10 to the injection system (not shown) of diesel engine 12. Pump 20 assures positive flow through both the primary and secondary fuel filter means 21, 22 in which air, water and other non-fuel impurities are removed. Thus, optimum engine performance can be achieved through pre-filtration of diesel fuels with the result that maximum burning of diesel fuel will result in lower levels of diesel particulate matter (DPM) in the emission exhaust gases from the engine 12. Nonetheless, the unburned hydrocarbon content of engine exhaust gases has, in the past, continued to be a major safety and health concern in the operation of diesel engines—particularly in closed, poorly ventilated areas such as underground mines.
The major feature of the invention is to deliver diesel engine discharge gases (with inherent hydrocarbon DPM content) through the emission exhaust section EE, which includes exhaust gas scrubber means for safely removing such DPM content, reducing carbon monoxide levels and discharging cleaned exhaust gases to ambient. The effectiveness of this feature of the invention is achieved primarily by providing an aqueous solution in the gas scrubber section EE that includes a super-wetting agent (“wetting composition”), and the following definitions will be instructive in the disclosure and claiming of this feature of the invention:
DPM (diesel particulate matter) as used herein shall generally mean all forms of hydrocarbon and other carbonaceous matter, carbon or nitrogen oxides, sulfurous gases and related particulate matter. DPM may also be referred to as “particulate carbonaceous matter”.
Referring now again to FIG. 2 of the drawings, the exhaust scrubber portion EE of the system includes an aqueous filter apparatus positioned in the exhaust output passageway from the diesel engine 12 to ambient. More specifically, the aqueous filter apparatus forms a water bath WB through which all DPM laden exhaust gases are passed and cleaned before being discharged to ambient. In a preferred form of the invention, the water bath WB of filtering apparatus is contained in a scrubber tank 33 that has an exhaust intake 34 connected by exhaust pipe 35 to the exhaust manifold (not shown) of the engine 12. The exhaust pipe 35 is covered by a suitable insulation covering 36, such as “Thermogram”, to shield the high discharge gas temperatures (i.e., 800° to 1100° F.) from the surrounding ambient. In FIG. 2 it will be seen that the tank 33 has an internal extension pipe 37 connected to the exhaust pipe 35 and extending into the tank 33 below the level 38 of the water bath WB. A gas discharge diffuser 39 is provided at the exit end of the exhaust extension pipe 37 to break up and disperse the exhaust gas stream as it is discharged from the extension 37 into the water bath WB in the tank 33. For illustration purposes the diffuser 39 is simply shown as an elongate pipe having a series of discharge openings 40, but it will be understood that a wide variety of gas diffusing means, such as in the form of perforations, screens and turbulence producing means, may be employed. The openings 40 are preferably arrayed along the length and around the circumference of the diffuser 39. The diffuser means (39) of the invention should act to disperse or spread out the gas stream for mixture into or percolation through the water bath WB and it may act to partially decelerate the entering gas stream to a lower velocity. However, it is important that any retardant effect should be controlled to a minimum so as to not create undue back pressure on the diesel engine 12.
The scrubber tank 33 may be any suitable shape, such as cubicle or cylindrical, and holds a pre-determined volume of liquid in the range of 35 to 50 gallons. The exhaust intake 34 is located at one end of this tank, and the tank also has a gas discharge or outlet 42 located at the other tank end and positioned above the water bath level 38 in such manner that the exhaust gases must traverse through the water bath the length of the scrubber tank 33 from the diffuser (40) at the intake end to the outlet port 42 at the exit end. A final filter 43 of ceramic or fiberglass is shown connected at the gas discharge outlet (as currently mandated by MSHA for class 32 diesel operations). It is believed that the present invention will minimize any need for a final filter 43, as will be shown.
In addition to the diffusing means (39, 40) for dispersing or breaking up the exhaust gas stream as it enters the water bath WB, the tank 34 is provided with baffle means (44, 45) projecting vertically into the body of water in the tank and extending across the tank from side to side. The baffle means (44, 45) are constructed and arranged to create tortuous or circuitous gasflow pathways to increase the turbulence and mixing contact of DPM laden gas molecules with the water bath WB. In the form of the invention shown in FIG. 2, first baffles 44 are arranged to extend upwardly from the floor 46 of the tank or just above the floor, and have upper ends 44 a below the water level 38. Second baffles 45 are arranged to extend downwardly from the top 47 of the tank and have lower end margins 45 a within the water bath and spaced above the floor 46. The first and second baffle means are alternately arranged to create major tortuous pathways having primary vertical channels therebetween and being connected around the baffle end margins (44 a, 45 a), as shown by the curved arrows. The baffles 44, 45 are also shown with minor secondary through-ports 49 to provide for small portions of exhaust gases to flow directly through these baffles and impinge on the major gas portions flowing in a vertical direction in the primary vertical passageways whereby to cause further turbulence and scrubbing action between the gases and the water bath WB. It should be noted that the baffles 45 extend across the tank from the top (47) downwardly into the water bath thereby forming a vapor barrier or seal above the waterline so that exhaust gases must flow through the water bath in the major passageways to reach the final exit port 42 from the tank 33. The tank 33 also has a water fill pipe 50 and water level float 51, and the bottom of the tank may have an outlet 74 or like drain provision for periodic flushing of the tank as may be required.
Super-wetting agent or wetting composition as used herein shall generally mean an aqueous mixture comprising a combination of a chemical hydrocarbon cleaner and a defoaming agent, the composition typically in the form of a colloid, suspension, emulsion or solution.
A colloid (i.e., colloidal system) as used herein shall generally mean a dispersion of finely divided particles in a continuous liquid medium—the particles being in a mid-size range between a true solution (1 millimicron or nanometer) and a coarse dispersion or suspension (1 micron or micrometer). Emulsion as used herein shall generally mean a stable mixture of two or more immiscible liquids held in suspension by a surface-active “emulsifier” that is either (1) a protein or carbohydrate polymer which coats the surfaces of dispersed fat (oil) particles to prevent coalescing (called a protective colloid) or (2) a long-chain alcohol and fatty acid which reduces surface tension at the interface of suspended soluble particles. Emulsions consist of a continuous phase and a disperse phase in which small globules of one liquid are suspended in a second liquid by a wetting or deterging agent.
An important aspect of the invention resides in the selection of suitable combination of chemical hydrocarbon cleaner and defoaming agent to formulate an acceptable wetting composition for use in the aqueous mixture of the water bath WB. In the past water scrubbers have been placed in diesel exhaust lines to cool exhaust gases and, of course, some amount of particulate soot materials will be removed from these gases. However, it is known that the carbonaceous matter or DPM is basically immiscible in water and that only a very small portion of DPM will be suspended in the water of these prior art traps; and that no carbon monoxide will be removed therein. Thus, it is presently mandated that all scrubbers (soot traps) of any kind used on class 32 diesel equipment in coal mines be equipped with a “stop work float device” to ensure that hydrocarbon sludge in the tank does not reach kindling temperature and catch fire. It is also known that various natural and chemical surfactants, detergents and/or wetting agents in aqueous solution can attract hydrocarbons from exhaust gases and hold them in the water of a scrubber, but the resulting foaming action of such additives often creates unacceptable conditions and environmental problems.
It will be understood that the wetting composition of the invention should preferably be able to function effectively in hot environments (e.g., about 800° to 1100° F.), which is the typical temperature range of exhaust gases entering the aqueous solution of the scrubber (33). Furthermore, the wetting composition should desirably be able to react very fast and bond with hydrocarbons and carbon compounds and pull them from the exhaust gases. It is believed that the high gas temperature may act to accelerate this bonding reaction of the chemical hydrocarbon cleaner (e.g., surfactant) with the DPM and also the removal of carbon monoxide (CO) from the exhaust stream. The turbulence generated by the rapid flowing exhaust gases entering the scrubber and being dispersed by the diffuser through the water bath produces greater surface area contact and more complete removal of DPM and CO from the exhaust.
The chemical hydrocarbon cleaner is preferably selected so as to be able to reduce the amount of DPM and CO present in the exhaust gas entering the scrubber. In addition, a suitable wetting composition of the present invention has a fast reaction in attracting and holding DPM due to the high velocity of the exhaust gas stream entering the scrubber tank (33), even though the diffuser means (39) may have a retardant effect on the dispersed gas. In one embodiment, the present invention attracts and holds the DPM 3 to 5 times or even faster than previous scrubbing methods.
In accordance with one embodiment of the present invention, various wetting compositions have been devised for use in conjunction with a diffusing means for dispersing exhaust gases throughout the water bath of a scrubber, thereby obviating prior art shortcomings and achieving superior diesel exhaust gas cleansing of DPM and reduction of carbon monoxide levels.
The chemical hydrocarbon cleaner may be suitably selected from various detergents, soaps, surfactants and mixtures thereof. Detergent as used herein generally means any deterging or cleaning agent produced from synthetic organic compounds (rather than natural fats or oils and alkali as in soaps). Detergents are soluble in water, and highly foamable and act as a wetting agent and emulsifier.
In one embodiment, the chemical hydrocarbon cleaner used in the present invention may include a soap. Soap as used herein shall generally mean a deterging or cleaning agent made by reacting a natural fatty acid (e.g., tall oil fatty acid) or oil with an alkali or caustic (such as sodium or potassium hydroxide or an alkanolamine such as monoethanolamine) to produce the corresponding soap with glycerol as a by-product. Soaps, like detergents, exhibit surface-active properties, such as foaming, detergency and lowering of surface tension.
Surfactant as used herein shall mean any of the class of surface-active agents including (or are included in) detergents, soaps, colloids and emulsifiers. Surfactants are surface-active agents that reduce the surface tension of water and cause it (1) to penetrate more easily into, or spread over the surface of, another material or (2) be penetrated by or become a dispersion of another material. Surfactants are wetting agents that orient themselves at the molecular interface of water with other surfaces and modify the liquid properties at the interface. A surfactant typically consists of two parts: a hydrophobic portion (e.g., a long hydrocarbon chain) and a hydrophilic portion that makes the entire compound soluble or dispensable or dispersable in water and these hydrophobic and hydrophilic moieties render the compound surface-active. Surfactants suitable for use in the practice of the present invention are generally classified as anionic, cationic, nonionic, or amphoteric.
Preferably, in order to alleviate environmental concerns, the wetting composition is formulated to be phosphate and nitrate-free. Furthermore, the chemical hydrocarbon cleaner is preferably low-foaming to mitigate production of foam during use. Nonionic surfactants generally have lower sudsing or foaming characteristic than anionic surfactants (cationic surfactants are primarily used in industrial chemical processing). Accordingly, in view of these concerns, in a preferred embodiment described in greater detail below, the chemical hydrocarbon cleaner utilized in the wetting composition comprises a nonionic surfactant.
Examples of suitable nonionic surfactants for use in the chemical hydrocarbon cleaner component of the wetting composition include ethoxylated alcohols, alkanolamines, and mixtures thereof. In accordance with a preferred embodiment, the chemical hydrocarbon cleaner includes an ethoxylated nonylphenol nonionic surfactant, for example, n-molar ethoxylated nonylphenols or mixtures thereof, sometimes denoted as nonoxynol-n, where n is a rational number between about 2.5 and about 15. Such nonionic surfactants are available from Huntsman Chemical (Salt Lake City, Utah). In an especially preferred embodiment, the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10 either alone or in combination with an alkanolamine nonionic surfactant such as monoethanolamine.
Even in embodiments where a low-foaming nonionic surfactant is employed as the hydrocarbon cleaning agent, the wetting composition of the present invention advantageously further includes a defoaming agent. Indeed, the use of a defoaming agent is an important aspect of the invention in that it provides a wetting composition that does not foam excessively, in short, that it maintain a substantially liquid state at all times. Known defoaming agents have a variable range of effectiveness. Accordingly, the concentration of the defoaming agent in the wetting composition may vary considerably in order to attain suitable mitigation of foam production during use, but generally is at least about 1% by weight, more typically at least about 5% by weight and preferably from about 5% to about 15% by weight. The concentration of the defoaming agent in the wetting composition necessary to obtain the desired results under applicable operating conditions can be readily determined through routine experimentation.
The defoaming agent typically is dispersable in the other components of the wetting composition. Examples of suitable defoaming agents include petroleum-based antifoams (e.g., 2-octanol, sulfonated oils, organic phosphates) and silicone-based antifoams. However, it has been found that petroleum-based antifoams may be susceptible to degradation in the wetting compositions disclosed herein and may not provide the desired level of foam mitigation during use after prolonged periods (e.g., 1 to 2 days) following formulation. Accordingly, in such embodiments, the wetting compositions can be prepared for use in aqueous solution as a single or one part product; or the remainder of the composition can be packaged separately from the petroleum-based antifoam to be combined with the remainder of the composition just prior to use at the diesel operating site. In order to provide a wetting composition capable of sufficient foam mitigation and longer effective shelf-life, it is preferred that a silicone-based antifoam be utilized as the defoaming agent. Specific examples of silicone-based antifoams include silicone fluids and organosiloxanes. In accordance with an especially preferred embodiment, the defoaming agent comprises a polydimethylsiloxane. Non-limiting examples of suitable polydimethylsiloxane antifoams include those available from General Electric (Waterford, N.Y.), such as those sold under the product designations AF9000, AF9010, AF9020 and AF9030.
In one preferred embodiment wherein the chemical hydrocarbon cleaner component comprises a nonionic surfactant comprising an ethoxylated nonylphenol in combination with monoethanolamine or other alkanolamine, the wetting composition may advantageously be formulated with a tall oil fatty acid. In such an embodiment, the tall oil fatty acid is saponified at least to some extent with the alkanolamine caustic to form a soap.
The wetting composition of the present invention may include a variety of optional components in addition to the chemical hydrocarbon cleaner and the defoaming agent. For example, the composition, particularly when a surfactant (e.g., a nonionic surfactant) is utilized as the chemical hydrocarbon cleaner, may further include an organic solvent. In such embodiments, the organic solvent may provide composition thinning or fluidity, for example, in the form of a colloid. Suitable non-limiting examples of organic solvents include alkylene glycol ethers such as dipropylene glycol methyl ether.
It may also be advantageous to include in the wetting composition a coupling agent such as tetrasodium ethylenediaminetetraacetate (EDTA) as a formulation aid.
One representative preferred wetting composition useful in treating diesel exhaust emission gases in accordance with the present invention comprises water; a chemical hydrocarbon cleaner comprising ethoxylated nonylphenol nonionic surfactant and a soap formed by saponifying a tall oil fatty acid with monoethanolamine; an organic solvent comprising dipropylene glycol methyl ether; a coupling agent comprising tetrasodium EDTA; and a defoaming agent comprising a silicone-based antifoam. Preferably, the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10 and the silicone-based antifoam comprises a polydimethylsiloxane.
Another more representative preferred wetting composition in accordance with the present invention comprises at least about 35% by weight water; a chemical hydrocarbon cleaner comprising an ethoxylated nonylphenol nonionic surfactant and a soap formed by saponifying a tall oil fatty acid with monoethanolamine, wherein the composition comprises from about 10% to about 30% by weight ethoxylated nonylphenol nonionic surfactant, from about 2% to about 8% by weight tall oil fatty acid and from about 1% to about 5% by weight monoethanolamine; an organic solvent comprising dipropylene glycol methyl ether, wherein the composition comprises from about 5% to about 15% by weight dipropylene glycol methyl ether; a coupling agent comprising tetrasodium EDTA, wherein the composition comprises at least about 0.5% by weight tetrasodium EDTA; and a defoaming agent comprising a silicon-based antifoam, wherein the composition comprises at least about 1% by weight silicon-based antifoam. Preferably, the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10 and the silicone-based antifoam comprises a polydimethylsiloxane.
Examples of wetting compositions in accordance with the present invention include the products designated Aqua Filter Nos. 195D, 942D and 735D available from Brady's Mining and Construction Supply Co. (St. Louis, Mo.). These wetting compositions each have a multiple surfactant base of low foaming surfactants plus a silicone-based antifoam.
Methods and techniques for formulating wetting compositions in accordance with the present invention will be readily apparent to those skilled in the art. Generally, water, the chemical hydrocarbon cleaner and the defoaming agent along with any other components of the wetting composition are blended in a suitable vessel equipped with an agitation device (e.g., a stirred tank). Typically, it may be necessary to heat the mixture or the individual components thereof in order to produce the desired composition in the form of a colloid, suspension, emulsion or solution.
In formulating these preferred wetting compositions of the present invention it may be useful to start with the colloidal surfactant blend designated B/F100P, available from Foresight Chemical (Troy, Ill.) and Brady's Mining and Construction Supply Co. (St. Louis, Mo.). This product comprises a colloid containing nonoxynol 10, dipropylene glycol methyl ether, monoethanolamine, tall oil fatty acid and tetrasodium EDTA. Accordingly, B/F100P can be used as a suitable base for formulating the wetting composition described herein. In one embodiment, a suitable quantity of defoaming agent (e.g., polydimethylsiloxane) may be added to produce the wetting composition. However, in order to provide a more effective wetting composition having desirable fluidity characteristics, it is preferred to add additional quantities of nonoxynol 10 and tall oil fatty acid as necessary to obtain the desired composition as set forth above along with the defoaming agent. Preferably the B/F100P base composition is heated to a temperature of from about 125° to about 175° F. during addition of these ingredients. Typically, additional dipropylene glycol methyl ether is added in order to thin the composition and ensure sufficient fluidity in the final wetting composition. For example, in one embodiment, a suitable wetting composition may be prepared by mixing approximately 70 parts by weight of B/F100P with approximately 30 parts by weight of a low foaming surfactant including approximately 10 parts by weight of a silicone-based defoaming agent.
Although a preferred wetting composition as described above includes an ethoxylated nonylphenol nonionic surfactant as the chemical hydrocarbon cleaner, those skilled in the art will be able to identify other surfactants, detergents, soaps and mixtures thereof for use in combination with a defoaming agent. Examples of such chemical hydrocarbon cleaners include the surfactants found in JOY brand dishwashing liquid (Procter and Gamble, Cincinnati, Ohio) and PALMOLIVE brand dishwashing liquid (Colgate-Palmolive, New York, N.Y.). Suitable anionic surfactants include alkylether sulfates, alkyl sulfates and mixtures thereof.
In accordance with the present invention, the DPM level of the exhaust gas entering the scrubber can be reduced by at least about 30% and the carbon monoxide loading reduced to an acceptable level (e.g., 13 ppm). In one preferred embodiment, the DPM level can be reduced in the range of from about 40% to about 80%. In an even more preferred embodiment, the DPM level can be reduced by from about 60% to about 80% or even higher levels of reduction. In addition, up to about 99% of DPM can be removed when the water bath scrubber (33) is used in conjunction with a final filter (43).
The scrubber tank 33 of the FIG. 2 embodiment holds a water bath having a major water constituent (e.g., typically from about 25 to about 50 gal.) and a minor constituent amount (e.g., typically from about 1 to about 2 qts.) of the wetting composition disclosed herein (e.g., a solution of about 0.5% to 2%). Clearly, higher concentrations of the wetting composition in the water bath will perform to attract and hold more DPM over longer operating periods. It should be noted that flushing of the tank (33) and replacement of the aqueous solution periodically (e.g., in the range of about 4 to 6 hours) will be required for optimum performance to achieve “clean air” objectives. This is a low cost, high satisfaction result as compared with the high cost of present prior art systems.
Referring now to FIG. 3, another form of the invention is shown diagrammatically as an exhaust scrubber EE having a scrubber apparatus constructed and arranged to provide a continuous water bath replacement process. In the FIG. 3 embodiment the scrubber tank 133 is relatively small and has a capacity for holding about 4 gallons of the aqueous solution. Similar to the FIG. 2 embodiment, in FIG. 3 the insulated diesel exhaust pipe 135 connects from the engine (12) to the tank 133 at a gas intake 134, and an internal extension pipe 137 extends below the tank's water level 138 and has a perforated gas discharge diffuser 139 for dispersing the DPM laden exhaust gas as it is discharged into the water bath WB. The diffuser 139 is shown as discharging exhaust gas radially, outwardly through the water bath, but other gas dispersing means may be arranged in the water bath. The tank 133 also has a gas discharge outlet 142 located above the water level 138. The feature of the FIG. 3 embodiment is that the aqueous solution of the water bath WB has a continuous feed and is constantly flowing into and through the tank 133 to intimately mix with exhaust gases and remove DPM and carbon monoxide from such exhaust gases.
FIG. 3 shows that the aqueous solution can be prepared by admixing a minor portion of super-wetting agent with a major quantity of water as in a blending tank or mixer 170 constructed to hold a large amount of solution, such as 45 to 55 gal. and from which the flow rate of the water bath solution into tank 133 can be regulated, as at 171. The super-wetting aqueous solution is delivered into the tank through a delivery tube or pipe 172 and discharged through a perforated distributor 173 outwardly in radial directions to maintain level of the water bath WB, in such manner that the exhaust gases as a first medium, are dispersed into or throughout the water bath even as the incoming aqueous solution, as a second medium, is being dispersed therein to achieve the desired intimate turbulence and intermixing whereby the super-wetting agent removes the DPM and cleans the exhaust gases. Thus, the water bath WB of FIG. 3 is not static as the tank 133 has an outlet 174 for regulating the out flow drainage of the aqueous solution from the tank 133 at the predetermined rate so that the solution is constantly flowing into and replacing the water bath content as it is discharged from the tank.
Still referring to FIG. 3, the small volume tank 133 is provided with the baffle means 144 extending upwardly from adjacent the floor 146 and baffle means 145 extending down from the top of the tank 133 to enhance circuitous gas flow paths. Through-ports 149 may also be provided in these baffles 144 to increase turbulence and intermixing of the exhaust gases with the aqueous solution. The baffles 145 form vapor seals above the level of the water bath in the tank 133 to force the exhaust gas to pass through the water bath to the exhaust.
It should be noted that the effluent solution from outlet drain 174 can be piped off for remote disposal. However, in most underground mining operations, as in coal mining, water is widely used for different purposes by different equipment, and it is usually discharged as wastewater onto the mining floor where it will be absorbed or from which it may or may not be removed by gravity run-off or through sump action. For instance, water is used in drilling and cutting operations as a coolant for rotary drill bits, long-wall cutting teeth and the like—as well as to remove and flush cuttings away from the drilling or cutting site. Respirable dust is a health threat even as DPM environmental air pollution is a concern addressed by the present invention. Therefore, water is used as a dust suppressant and the disposal methods for effluent mine water from the various diesel systems or other mining equipment are a general concern, but outside the scope of the invention.
Referring to FIGS. 4 and 5, the invention can be carried out in an exhaust scrubber apparatus (EE) having a sealed scrubber tank jacket or housing 233 with an exhaust gas inlet 234 from diesel exhaust pipe 235 at one side and clean gas outlet 242 at the other side. In this embodiment the aqueous solution is discharged in a plurality of adjacent vertical streams (280) as a continuous water bath curtain from the top wall 247 across the width of the scrubber tank 233 to the floor 246 from which the effluent is removed through an outlet drain 274 for disposal. The aqueous solution formed by mixing a super-wetting agent of the invention with water, as in blending tank or mixer 270, is delivered through a flow regulator 271 to a distributor manifold 281 or the like from which it is piped to one or more horizontal perforated pipes 282. The diffuser 239 for spreading out the discharge of exhaust gases in the scrubber tank chamber is constructed and arranged to have a maximum gas discharge area to provide the widest gas dispersion through and intimate contact with the aqueous solution as it passes through the vertical curtain wall of the water bath WB.
The aqueous solutions used in the FIG. 3 and FIG. 4 embodiments will be the same as previously discussed, and only the respective delivery and mixing of exhaust gases therewith is different.
It is now apparent that the objects and advantages of the present invention have been fully met. Changes and modifications of the disclosed forms and combinations of the invention will become apparent to those skilled in the mining field and the providers and operators of diesel equipment in general, and the invention is only to be limited by the scope of the appended claims.

Claims

1. An emission control system for reducing diesel particulate matter (DPM) from the exhaust gas output from a diesel engine, comprising an aqueous filter apparatus positioned in the exhaust output passageway from the diesel engine and being constructed and arranged to form a water bath in said passageway through which all DPM laden exhaust gases from said engine must pass before being discharged to ambient, the water bath of said aqueous filter apparatus comprising water as a major constituent and a wetting composition as a minor constituent, said wetting composition comprising a chemical hydrocarbon cleaner including at least one component selected from the group consisting of detergents, soaps, surfactants and mixtures thereof, and a defoaming agent.

2. The emission control system of claim 1, in which said aqueous filter apparatus comprises a gas scrubber tank filled to a predetermined level with said water bath, said exhaust output passageway having a discharge end positioned below the level of said water bath, and gas diffusing means in said tank for dispersing exhaust outflow gases throughout the water bath.

3. The emission control system of claim 2, wherein said gas diffusing means comprises a perforated gas discharge pipe at the discharge end of said passageway whereby to effect percolation of exhaust gases through the water bath.

4. The emission control system of claim 2, in which said gas scrubber tank has an exhaust discharge outlet to ambient, and wherein said gas diffusing means comprises vertical baffle means disposed in said gas scrubber tank between the discharge end of said exhaust output passageway into the water bath and said exhaust discharge outlet to thereby produce circuitous flow paths of exhaust gases through the water bath in said tank.

5. The emission control system of claim 4, wherein said vertical baffle means includes plural horizontal ports extending therethrough to provide limited by-pass flow of exhaust gases across said circuitous gases flow paths.

6. The emission control system of claim 2, in which said gas scrubber tank has an exhaust gas inlet end receiving the exhaust output passageway from the engine, and having an exhaust gas outlet end above the level of the water bath and forming a gas discharge outlet to ambient, said gas diffusing means for dispersing including at least two mixing means for creating circuitous and turbulent flow of exhaust gases through said water bath.

7. The emission control system of claim 6, wherein one of said mixing means comprises a perforated gas discharge pipe on the inlet side of said scrubber tank for discharging of exhaust gases from said exhaust output passageway through the water bath.

8. The emission control system of claim 6, wherein one of said mixing means comprises a plurality of baffles between the inlet and outlet ends of said scrubber tank to circulate exhaust gases intimately throughout the water in serpentine flow paths around and between the baffles.

9. The emission control system of claim 8, including another mixing means in the form of ports through the baffles to accommodate minor limited direct flow of a portion of exhaust gases through the baffles in a direction substantially perpendicular to the serpentine flow direction of exhaust gases around and between the baffles.

10. The emission control system of claim 1, including water level sensing means for assuring safe operating water levels of said water bath.

11. The emission control system of claim 1, in which said aqueous filter apparatus comprises water curtain means for discharging an aqueous water wall formed of a solution of said major body of water and minor amount of super-wetting agent.

12. The emission control system of claim 11, in which said water curtain means comprises closed scrubber tank means having a gas inlet side connecting to the engine and a gas discharge side connecting to ambient, a supply source of blended water and wetting composition, and water spray means for discharging a continuously flowing curtain wall of such solution across the tank means, and said gas inlet side having gas dispersing means for discharging exhaust gases from the engine throughout the upstream inlet side for passage therefrom through the curtain wall to the downstream outlet side.

13. The emission control system of claim 12, in which said supply source hold a relatively large amount of blended water and wetting composition and said scrubber tank means is relatively small, and said scrubber tank means including discharge means for outflowing used solution from the bottom thereof.

14. The emission control system of claim 13, in which said scrubber tank means has a volumetric capacity in the range of 4 to 10 gal. and said supply source of solution comprises a solution blending tank having a volumetric capacity in the range of 25 to 60 gal.

15. The emission control system of claim 12, including means for regulating the flow of solution to said water spray means.

16. The emission control system of claim 2, in which said aqueous filter apparatus comprises a gas scrubber tank of relatively large size holding a water bath in the volumetric range of 25 to 55 gal.

17. The emission control system of claim 2, in which said gas scrubber tank has a relatively small size holding a water bath in the volumetric range of 3 to 10 gal., and a supply source of blended water and wetting composition solution constructed and arranged for maintaining the water bath level in said scrubber tank.

18. The emission control system of claim 1, in combination with a diesel fuel pre-filter constructed and arranged upstream of the diesel engine for removing non-fuel contaminates from the diesel fuel to thereby improve engine performance.

19. The emission control system of claim 18, in which said fuel pre-filter is interposed in the fuel supply line to the diesel engine, and is constructed for filtering non-combustible contaminates of the diesel fuel whereby to provide a substantially totally-combustible diesel fuel supply to the engine.

20. The emission control system of claim 19, in which said fuel pre-filter includes a first filter for filtering water out of the diesel fuel, and a second filter for filtering air out of the diesel fuel.

21. The emission control system of claim 1, in which the wetting composition is phosphate-free.

22. The emission control system of claim 21, in which the wetting composition is nitrate-free.

23. The emission control system of claim 1, in which the chemical hydrocarbon cleaner is low-foaming.

24. The emission control system of claim 23, wherein the chemical hydrocarbon cleaner comprises at least one surfactant selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants and mixtures thereof.

25. The emission control system of claim 23, wherein the wetting composition further comprises an organic solvent.

26. The emission control system of claim 25 wherein the chemical hydrocarbon cleaner comprises an anionic surfactant.

27. The emission control system of claim 26 wherein the anionic surfactant is selected from alkylether sulfates, alkyl sulfates and mixtures thereof.

28. The emission control system of claim 25 wherein the chemical hydrocarbon cleaner comprises an amphoteric surfactant.

29. The emission control system of claim 25 wherein the chemical hydrocarbon cleaner comprises a nonionic surfactant.

30. The emission control system of claim 29 wherein the nonionic surfactant is selected from the group consisting of ethoxylated alcohol, alkanolamines and mixtures thereof.

31. The emission control system of claim 30 wherein the nonionic surfactant comprises an ethoxylated nonylphenol.

32. The emission control system of claim 31 wherein the nonionic surfactant comprises a mixture of an ethoxylated nonylphenol and an alkanolamine.

33. The emission control system of claim 32 wherein the nonionic surfactant comprises a mixture of an nonoxynol 10 and monoethanolamine.

34. The emission control system of claim 31 wherein the organic solvent comprises an alkylene glycol ether.

35. The emission control system of claim 34 wherein the organic solvent comprises dipropylene glycol methyl ether.

36. The emission control system of claim 31 wherein the defoaming agent is selected from petroleum-based antifoams, silicone-based antifoams and mixtures thereof.

37. The emission control system of claim 36 wherein the defoaming agent comprises a silicon-based antifoam.

38. The emission control system of claim 37 wherein the silicon-based anti-foam comprises an organosiloxane.

39. The emission control system of claim 38 wherein the silicon-based anti-foam comprises polydimethylsiloxane.

40. The emission control system of claim 31 wherein the wetting composition further comprises a coupling agent.

41. The emission control system of claim 40 wherein the coupling agent comprises tetrasodium EDTA.

42. The emission control system as set forth 41 wherein the chemical hydrocarbon cleaner comprises a soap formed by saponifying a tall oil fatty acid with a caustic comprising an alkanolamine.

43. The emission control system as set forth in claim 1 wherein the wetting composition comprises:

water;

a chemical hydrocarbon cleaner comprising ethoxylated nonylphenol nonionic surfactant and a soap formed by saponifying a tall oil fatty acid with monoethanolamine;

an organic solvent comprising dipropylene glycol methyl ether;

a coupling agent comprising tetrasodium EDTA; and

a defoaming agent comprising a silicone-based antifoam.

44. The emission control system of claim 43 wherein the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10.

45. The emission control system of claim 44 wherein the silicone-based antifoam comprises a polydimethylsiloxane.

46. The emission control system of claim 1 wherein the wetting composition comprises:

at least about 35% by weight water;

a chemical hydrocarbon cleaner comprising an ethoxylated nonylphenol nonionic surfactant and a soap formed by saponifying a tall oil fatty acid with monoethanolamine, wherein the composition comprises from about 10% to about 30% by weight ethoxylated nonylphenol nonionic surfactant, from about 2% to about 8% by weight tall oil fatty acid and from about 1% to about 5% by weight monoethanolamine;

an organic solvent comprising dipropylene glycol methyl ether, wherein the composition comprises from about 5% to about 15% by weight dipropylene glycol methyl ether;

a coupling agent comprising tetrasodium EDTA, wherein the composition comprises at least about 0.5% by weight tetrasodium EDTA; and

a defoaming agent comprising a silicon-based antifoam, wherein the composition comprises at least about 1% by weight silicon-based antifoam.

47. The emission control system of claim 46 wherein the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10.

48. The emission control system of claim 46 wherein the silicone-based antifoam comprises a polydimethylsiloxane.

49. The emission control system of claim 2, in which said gas scrubber tank has an exhaust discharge outlet leading to ambient and, in combination therewith, a final gas filter constructed and arranged to filter substantially all residual DPM material from the cooled and cleaned exhaust gases passing from the gas scrubber tank.

50. A diesel cleaning system for achieving optimum diesel engine performance and maximum removal of DPM and CO from diesel exhaust emission gases, comprising the steps of:

pre-filtering diesel fuel upstream of a diesel engine to remove non-combustibles and enhance more complete fuel burning to minimize residual hydrocarbon content in exhaust gases;

dispersing diesel exhaust emission gases through a water bath having water as a major constituent and as a minor constituent a wetting composition comprising a chemical hydrocarbon cleaner comprising at least one component selected from the group consisting of detergents, soaps, surfactants and mixtures thereof, and a defoaming agent, to thereby remove the majority of DPM matter from such gases.

51. A method of improving diesel engine performance and removing deleterious materials from diesel fuel and diesel exhaust gases, comprising the steps of:

pre-filtering diesel fuel upstream of the engine to remove non-combustible contaminates therefrom;

filtering diesel exhaust gases downstream of the engine to remove DPM and carbon monoxide therefrom including the step of passing such exhaust gases through an aqueous water bath having water as a major constituent and as a minor constituent a wetting composition comprising a chemical hydrocarbon cleaner comprising at least one component selected from the group consisting of detergents, soaps, surfactants and mixtures thereof, and a defoaming agent.

52. A DPM removal method for removing diesel particulate matter (DPM) from the exhaust gas emission of diesel engines used in class 32 gaseous environment applications, including the steps of:

providing water scrubber means downstream of the diesel engine to receive exhaust gas outflow therefrom,

providing an aqueous solution for the water scrubber means comprising a water bath having water as a major constituent and as a minor constituent a wetting composition comprising a chemical hydrocarbon cleaner comprising at least one component selected from the group consisting of detergents, soaps, surfactants and mixtures thereof, and a defoaming agent, and

creating an intimate dispersion of the exhaust gas emission through the aqueous solution of the water scrubber means.

53. The method of cleaning carbonaceous matter from a first medium, comprising the steps of:

selecting a chemical hydrocarbon cleaner including at least one component selected from the group consisting of detergents, soaps, surfactants and mixtures thereof;

selecting a defoaming agent as a secondary constituent;

formulating a wetting composition by combining the primary and secondary constituents in pre-determined proportion;

admixing a major portion of water with a minor portion of the wetting composition to constitute an aqueous solution as a second medium; and

dispersing one of said first and second mediums intimately with the other of said mediums to effectively remove carbonaceous matter from the first medium to the second medium.

54. A wetting composition useful in treating diesel exhaust emission gases to reduce the concentration of particulate matter and/or carbon monoxide, the composition comprising:

water;

a chemical hydrocarbon cleaner comprising at least one component selected from the group consisting of detergents, soaps, surfactants and mixtures thereof; and

a defoaming agent.

55. The wetting composition of claim 54 wherein the composition is phosphate-free.

56. The wetting composition of claim 54 wherein the composition is nitrate-free.

57. The wetting composition of claim 54 wherein the chemical hydrocarbon cleaner is low-foaming.

58. The wetting composition of claim 54 wherein the chemical hydrocarbon cleaner comprises at least one surfactant selected from the group consisting of anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants and mixtures thereof.

59. The wetting composition of claim 58 further comprising an organic solvent.

60. The wetting composition of claim 59 wherein the chemical hydrocarbon cleaner comprises an anionic surfactant.

61. The wetting composition of claim 60 wherein the anionic surfactant is selected from alkylether sulfates, alkyl sulfates and mixtures thereof.

62. The wetting composition of claim 59 wherein the chemical hydrocarbon cleaner comprises an amphoteric surfactant.

63. The wetting composition of claim 59 wherein the chemical hydrocarbon cleaner comprises a nonionic surfactant.

64. The wetting composition of claim 63 wherein the nonionic surfactant is selected from the group consisting of ethoxylated alcohol, alkanolamines and mixtures thereof.

65. The wetting composition of claim 64 wherein the nonionic surfactant comprises an ethoxylated nonylphenol.

66. The wetting composition of claim 65 wherein the nonionic surfactant comprises a mixture of an ethoxylated nonylphenol and an alkanolamine.

67. The wetting composition of claim 66 wherein the nonionic surfactant comprises a mixture of an nonoxynol 10 and monoethanolamine.

68. The wetting composition of claim 65 wherein the organic solvent comprises an alkylene glycol ether.

69. The wetting composition of claim 68 wherein the organic solvent comprises dipropylene glycol methyl ether.

70. The wetting composition of claim 65 wherein the defoaming agent is selected from petroleum-based antifoams, silicone-based antifoams and mixtures thereof.

71. The wetting composition of claim 70 wherein the defoaming agent comprises a silicon-based antifoam.

72. The wetting composition of claim 71 wherein the silicon-based anti-foam comprises an organosiloxane.

73. The wetting composition of claim 72 wherein the silicon-based anti-foam comprises polydimethylsiloxane.

74. The wetting composition of claim 65 further comprises a coupling agent.

75. The wetting composition of claim 74 wherein the coupling agent comprises tetrasodium EDTA.

76. The wetting composition of 65 wherein the chemical hydrocarbon cleaner comprises a soap formed by saponifying a tall oil fatty acid with a caustic comprising an alkanolamine.

77. A wetting composition useful in treating diesel exhaust emission gases to reduce the concentration of particulate matter and/or carbon monoxide, the composition comprising:

water;

an organic solvent comprising dipropylene glycol methyl ether;

a coupling agent comprising tetrasodium EDTA; and

a defoaming agent comprising a silicone-based antifoam.

78. The wetting composition of claim 77 wherein the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10.

79. The wetting composition of claim 78 wherein the silicone-based antifoam comprises a polydimethylsiloxane.

80. A wetting composition useful in treating diesel exhaust emission gases to reduce the concentration of particulate matter and/or carbon monoxide, the composition comprising:

at least about 35% by weight water;

81. The wetting composition of claim 80 wherein the ethoxylated nonylphenol nonionic surfactant comprises nonoxynol 10.

82. The wetting composition of claim 80 wherein the silicone-based antifoam comprises a polydimethylsiloxane.