US 20060201145 A1
The invention is embodied in a diesel system for reducing diesel particulate matter (DPM) emissions particularly in underground diesel engine operations, comprising, in combination, a supply of synthetic paraffinic diesel fuel having substantially no sulfur, aromatics and nitrogen content and formulated to greatly reduce DPM levels in the engine exhaust emissions relative to conventional diesel fuels, and other exhaust emissions processing apparatus preferably forming an aqueous filter 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 the method of reducing diesel emission contaminants including providing a supply of synthetic diesel fuel having a negligible sulfur, aromatics or nitrogen content, pre-filtering the diesel fuel, and removing DPM from exhaust gases by filtration.
1. A diesel emissions control system for removing diesel particulate matter (“dpm”) from diesel engine exhaust comprising, in combination, a supply of paraffinic-type synthetic diesel fuel for the diesel engine, an aqueous filter apparatus in the emissions output from the diesel engine and being constructed and arranged to form a water bath through which all “dpm” laden exhaust gases must pass before discharge to ambient, the water bath of said aqueous filter apparatus having a major water constituent and a minor constituent amount of a super-wetting agent having a relatively high affinity for hydrocarbons.
2. The emissions control system of
3. The emissions control system of
4. The emissions control system of
5. The emissions control system of
6. The emissions control system of class 4, in which the synthetic diesel fuel has an aromatics content less than 1.0%.
7. The emissions control system of
8. The emissions control system of
9. The emissions control system of
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11. The emissions control system of
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20. The emissions control system of
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22. The emissions control system of
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24. The emissions control system of
25. The emissions control system of
a chemical hydrocarbon cleaner comprises 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.
26. A synthetic diesel fuel for low emissions control in Class 32 diesel engine machinery, said fuel having a Cetane rating in the range of 60 to 80 and the following properties:
(1) a sulfur content of less than 1.0%
(2) an aromatics content of leas than 1.0%
(3) a nitrogen content of less than 1.0%.
27. The synthetic diesel fuel of
28. The synthetic diesel fuel of
29. The synthetic diesel fuel of
30. A method for achieving optimum diesel engine performance and maximum removal of DPM and CO from diesel emission gases, comprising the steps of:
formulating a paraffinic-type synthetic diesel fuel characterized by having a high cetane number over 60 and a negligible amount of sulfur, aromatics and nitrogen content, and providing a supply thereof for the diesel engine; and
dispersing emission gases from the diesel engine through another emission processing device or directly to ambient.
31. The method according to
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36. The method according to
37. A diesel emissions control system for removing diesel particulate matter (“dpm”) from diesel engine exhaust comprising, in combination, a supply of linear paraffinic-type synthetic diesel fuel having a Cetane rating of over 60 for the diesel engine; a diesel fuel pre-filter constructed and arranged between the supply of synthetic diesel fuel and the diesel engine for filtering non-combustible contaminates from the synthetic diesel fuel to thereby provide it substantially totally-combustible fuel to the engine, and an aqueous filter apparatus in the emissions output from the diesel engine and being constructed and arranged to form a water bath through which all “dpm” laden exhaust gases must pass before discharge to ambient, the water bath of said aqueous filter apparatus having a major water constituent and a minor constituent amount of a super-wetting agent having a relatively high affinity for hydrocarbons.
38. The emissions control system of
39. The emissions control system of
40. The method of
This is a continuation-in-part of U.S. application Ser. No. 11/074,595, filed Mar. 8, 2005, the entire disclosure of which is incorporated herein by reference.
1. Field of the Invention
This invention relates generally to diesel fuel 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 particularly in underground mining.
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. In addition, the sulfur content in petroleum-based diesel fuels, including No. 2 diesel products, is one of the major reasons the fuel injectors fail. 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 even state-of-the-art diesel engines using conventional petroleum-based and so-called low sulfur (No. 2) diesel fuels 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 all such class 32 diesel engines operating underground machinery (in the vicinity of the mining cut) as well as class 24 equipment which operates outby.
The control of exhaust gas emissions has been a primary troublesome concern for health and safety reasons, and the Federal government has heretofore mandated the use of “soot trap filters” to reduce DPM emissions 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 any buildup 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. Methane has an ignition temperature of 302° F. and, 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 of diesel exhaust gases would be carried past the catalytic converter to the soot trap thus producing the probability of fires and/or explosions therein. The result is 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 has promulgated a low—and heretofore unachievable—DPM emissions level of 2.5 gr/bhp-hr.
It has been reported that 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 prior art 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 or sulfur will be removed. The Kim patent 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 have additives such as detergent, surfactant or wetting agents, alcohol, glycol or alkalis, but no specific example or function is taught.
The invention is embodied in systems for reducing diesel particulate matter (DPM) in diesel engine emissions by providing a synthetic paraffinic diesel fuel having a Cetane rating greater than 60 and substantially no sulfur, aromatics or nitrogen content, and using such fuel alone or in combination with filtration means comprising an aqueous filter apparatus forming a water bath having a major water portion and a minor portion of super-wetting agent with a high affinity for hydrocarbons. The invention is further embodied in a diesel emissions control methods including the features of synthetic diesel fuel selection, pre-filtering diesel fuel, and removing DPM from diesel emissions through an aqueous solution having a minor portion of a low foam super-wetting agent.
A principal object of the invention is to provide systems, apparatus and methods for removing significant amounts of diesel particulate matter (DPM) from diesel engine gas emissions 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.
Another object is to provide synthetic paraffinic diesel fuels to thereby achieve substantial reductions in particulate emissions from the engine.
Still another object is to provide a synthetic high paraffinic diesel fuel formulated to produce substantially lower particulate emissions from diesel engines, and being used in combination with pre-filtration to remove non-combustible matter upstream of the engine and DPM filtration of emission gases downstream of the engine to thereby comply with the Federal Regulation levels prescribed for underground diesel.
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, and 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 economically priced synthetic fuel and low cost filtration 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 a linear paraffinic-type synthetic diesel fuel for use with exhaust gas scrubber systems and methods that together are effective in removing DPM matter and carbon monoxide from diesel emissions prior to passing to any final filter 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 fuels, systems, apparatus and methods whereby the present requirements for final exhaust filters may be ameliorated.
In the accompanying drawings wherein like numerals refer to like parts wherever they occur:
Referring to the diagrammatic overview of a diesel fuel system of the invention as shown in
The fuel tank 10 of the fuel delivery section FD according to the present invention provides a supply of synthetic diesel fuel formulated to result in engine exhaust emissions having a reduced particulate matter content of about 20%-40% relative to conventional petroleum diesel fuels inclusive of No. 2 or like low sulfur diesels. Such performance pre-supposes the use of a electronic state-of-the-art diesel engine, such as a Deutz 1013C engine, appropriately derated for the atmospheric levels of operation. It should also be noted at the outset that the present invention is particularly beneficial for diesel machinery operating in underground mines wherein expensive additional equipment and/or increased labor have heretofore been required to remove particulate soot traps for regeneration (cleaning) outside the mine.
Synthetic diesel fuels of the present invention are primarily identified as linear paraffinic types of synthetic hydrocarbon solvents or diesel fuels with properties that meet the standards prescribed for compression ignition engines. Such synthetic fuels are within a range of linear paraffin and isoparaffin hydrocarbons alone or in combinations with cycloparaffins (naphthenic paraffins), and sometimes called linear paraffinic-linear ofefinic diesels. The synthetic fuels may include a small part of a petroleum based product for lubricity.
The synthetic diesel fuel of the invention has substantially no sulfur, nitrogen or aromatics, i.e., less than 1.0%. It has a high Centane number in the range of about 60 to 80 and preferably in the range of about 60 to 75. In one example, the synthetic diesel fuel is a high purity mixture of hydrotreated isoparaffins, naphthenics and linear saturated paraffins with low or negligible levels of aromatics, sulfur and nitrogen (less than 1.0 ppm each) and has a Cetane number of 75. This synthetic diesel fuel is designated as UGD-S200 and is available from Brady's Mining and Construction Supply Co. (St. Louis, Mo.) and from Lancer Industries (Dallas, Tex.).
In another example, the synthetic diesel fuel—designated as UGD grade 175—is a high purity mixture of about 75% linear paraffins and 13% linear olefins with less than 12% of branch paraffin/olefins and it has a Cetane number less than 70. Its sulfur content is less than 1.0, its nitrogen content is less than 1.0 and its aromatics content is less than 0.5.
A third example designated as UGD Grade 70 is available from Lancer Industries (Dallas, Tex.) and Brady's Mining and Construction Supply Co. (St. Louis, Mo.). It has a Cetane number of 68 and has 0.0001 sulfur content and 0.5 aromatics (by Cetane Index).
Another feature of the invention is to deliver a substantially pure supply of the synthetic diesel fuel to the engine, i.e., fuel that is free from air, water and other unwanted gases or non-combustible contaminates. Thus, with reference to
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 electronic 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. As stated, with the use of linear paraffinic-type diesel fuels of this invention, potential DPM emission levels can be reduced by as much as 40% in the engine 12. It should also be noted that some characteristics of the present synthetic diesel fuel are the substantial absence of any sulfur, aromatics and nitrogen content (less than 1%). Nonetheless, the unburned hydrocarbon content of engine emission gases, as in the past, continues to be a major safety and health concern in the operation of diesel engines—particularly in closed, poorly ventilated areas such as underground mines.
Another 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”).
It is important that any retardant effect of exhaust gas dispersion should be controlled to a minimum so as to not create undue backpressure on the diesel engine 12. Recent MSHA regulations have set 34 inches of mercury as a backpressure maximum. Thus, the size and exhaust discharge rate of the diesel engine and the water bath capacity of the scrubber tank are important factors in designing an emissions flow path that will meet this requirement. For instance, sizes of diesel engines for underground mining equipment (or off-road machinery in general) vary widely—from a 90 Hp 4-cylinder Deutz engine having a 340 cfm output to a 150 Hp 6-cylinder Deutz engine with a 1275 cfm output. An inclusive range of up to 1500 to 2000 cfm must be accommodated and correlated to water bath capacity in the scrubber tank. Thus, the 1275 cfm exhaust output of the 6-cylinder engine will require a water bath capacity of about 84 gal. to absorb about 30% or more of the DPM from the emission gases. Therefore, the water bath capacity may vary between 20 to 90 gal. to accommodate different sizes of diesel-engines and meet the DPM removal requirements from exhaust gases. The scrubber tank 33 may be any suitable shape, such as cubicle or cylindrical, and constructed to hold the pre-determined volume of 20 to 90 gallons.
The exhaust intake 34 is located at one end of the tank 33, 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
Referring now to
Due to the high velocity of exhaust gases flow into the water bath and the desire to obtain optimum intermixture as surface contact therebetween, the internal extension pipe 337 may be twice the size of the exhaust pipe 334 and open into diffuser pipes 339 a and 339 b that also double the delivery capacity for exhaust gases. Thus an added feature of the invention is to enhance the circulation and intermixture of the water bath liquid with the incoming exhaust gas flow by providing an aspirator inlet opening 337A in the extension pipe 337 below the water level 338 of the water bath WB. A simple port 337A is shown whereby a venturi affect will be created andthe water bath will be aspirated into the downward gas stream and thoroughly intermixed therewith before being discharged out into the bottom of the tank 333. A Y-connection (not shown) or T-joint (not shown) may be used to function as a feed tube for the water bath solution to be drawn into the extension pipe. Thus, a circulating current of liquid is created at the gas inlet end of the tank, and the further turbulent gas/liquid discharge outwardly through diffuser ports 340 (and upwardly through the baffle plate ports 341 a) will assure excellent mixing and DPM removal by the super-wetting solution. It will be readily apparent that a liquid aspirating inlet (337A) may be provided in other embodiments of the invention. Any retardant effect on gas flow through this water bath should be minimized to reduce undue backpressure on the diesel engine 12.
The following definitions will be instructive in the further disclosure and claiming 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”.
“Super-wetting agent” or wetting solution 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.
“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.
“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.
An important aspect of the invention resides in the selection of a suitable combination of chemical hydrocarbon cleaner and defoaming agent to formulate an acceptable wetting solution 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 matter may become suspended in the water. 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 actually be removed in 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 underground class 32 and/or class 24 outby diesel equipment in coal mines be equipped with a “stop work float device” to ensure that hydrocarbon sludge accumulation 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 a limited amount of them in the water of a scrubber, but the resulting foaming action of such additives often creates other 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 substantially 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 should have a fast reaction time 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 some flow retardant effect on the dispersed gas. In one embodiment, the present invention attracts and holds the DPM at least 3 to 5 times faster than previous scrubbing methods.
In accordance with one aspect of the present invention, suitable wetting compositions have been formulated 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. Preferably, in order to alleviate environmental concerns, the super-wetting composition is formulated to be phosphate and nitrate-free. In addition, the chemical hydrocarbon cleaner is 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 an additional defoaming agent to provide a wetting composition that maintains a substantially liquid state at all times. The concentration of the defoaming agent in the wetting composition generally is at least about 1% by weight, more typically in the range of about 5% to 15% by weight. The defoaming agent 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 super-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 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 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 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.
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 along with the defoaming agent to obtain the desired composition. 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.
From the foregoing, it will now be apparent that the use of linear paraffinic-type synthetic diesel fuels in combination with an emission gas scrubber produces remarkable results in clean-emission performance of underground diesel equipment. The particulate toxins normally found in diesel fuels and diesel emissions can be reduced by 20% to 40% at the engine performance level, and the DPM level of emission gases can be further reduced by an additional 80% in the exhaust scrubber EE for a total reduction of 88%. 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 synthetic diesel fuel of the invention has substantially no sulfur, nitrogen or aromatics, i.e., less than 1.0% and a high Cetane rating in the range of about 60 to 80, and preferably in the range of about 65 to 75. The scrubber tank 33 of the
Referring now to
Still referring to
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.
The aqueous solutions used in the
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.