U.S. patent application number 11/262673 was filed with the patent office on 2006-10-05 for diesel emissions control system and method.
Invention is credited to William J. Brady.
Application Number | 20060218904 11/262673 |
Document ID | / |
Family ID | 46323061 |
Filed Date | 2006-10-05 |
United States Patent
Application |
20060218904 |
Kind Code |
A1 |
Brady; William J. |
October 5, 2006 |
Diesel emissions control system and method
Abstract
The invention is embodied in a diesel system for reducing
particulate matter emissions in off-road vehicles, coal mining and
metal/non-metal mining operations, comprising, in combination, a
supply of highly paraffinic diesel fuel having a high Cetane rating
and substantially no sulfur, aromatics and nitrogen content and
being formulated to greatly reduce PM output levels from the engine
relative to conventional diesel fuels, The invention is further
embodied in the method of reducing diesel emission contaminants
including providing a supply of highly paraffinic diesel fuel
having a negligible sulfur, aromatics or nitrogen content, and a
high Cetane number, and other apparatus useful for filtering engine
emissions before discharge to ambient.
Inventors: |
Brady; William J.; (Creve
Coeur, MO) |
Correspondence
Address: |
SENNIGER POWERS
ONE METROPOLITAN SQUARE
16TH FLOOR
ST LOUIS
MO
63102
US
|
Family ID: |
46323061 |
Appl. No.: |
11/262673 |
Filed: |
October 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11194371 |
Aug 1, 2005 |
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11262673 |
Oct 31, 2005 |
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11074595 |
Mar 8, 2005 |
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11194371 |
Aug 1, 2005 |
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Current U.S.
Class: |
60/297 |
Current CPC
Class: |
F01N 2330/10 20130101;
F01N 3/20 20130101; F01N 13/009 20140601; Y02A 50/20 20180101; C10L
1/08 20130101; F01N 3/043 20130101; B01D 47/022 20130101; F01N 3/04
20130101; F02B 3/06 20130101; F01N 3/033 20130101; Y02T 10/20
20130101; Y02A 50/2322 20180101; F01N 2230/04 20130101; F01N
2330/06 20130101; F02M 37/24 20190101; Y02T 10/12 20130101; B01D
53/92 20130101; F01N 1/10 20130101; F02M 37/54 20190101; B01D
47/021 20130101; F01N 1/083 20130101 |
Class at
Publication: |
060/297 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Claims
1. A diesel emissions control system for reducing diesel
particulate matter ("dpm") in diesel engine exhaust to meet
environmental control parameters, comprising, a supply of highly
paraffinic synthetic diesel fuel for the diesel engine, and
apparatus for receiving the emissions output from the diesel engine
and being constructed and arranged with filter means through which
all exhaust gases must pass before discharge to ambient.
2. The emissions control system of claim 1, in which said synthetic
diesel fuel has a Cetane rating in the range of about 60 to
100.
3. The emissions control system of claim 2, in which said Cetane
rating is in the range of about 65 to 80.
4. The emissions control system of claim 1, in which said synthetic
diesel fuel is characterized by having substantially no sulfur,
aromatics or nitrogen content.
5. The emissions control system of claim 4, in which the synthetic
diesel fuel has a sulfur content of less than 1.0%.
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 claim 4, in which the synthetic
diesel fuel has a nitrogen content of less than 1.0%.
8. The emissions control system of claim 1, in which the synthetic
diesel fuel is formulated to burn so as to produce a substantially
lower "dpm" content in emission gases than in conventional diesel
fuels.
9. The emissions control system of claim 8, in which the reduction
in "dpm" content is in the range of 20 to 40%.
10. The emissions control system of claim 1, in which the synthetic
diesel fuel is a linear paraffin-linear olefin fuel formulated to
have a Cetane rating over 60 and is characterized by having
negligible amounts of sulfur, aromatics and nitrogen.
11. The emissions control system of claim 1 in which said synthetic
diesel fuel comprises a hydrocarbon solvent for the reduction of
particulate emissions from diesel engines used in mining and being
formulated with a Cetane number above 60.
12. The emissions control system of claim 1, in which said
synthetic diesel fuel comprises a hydrocarbon solvent formulated
for reducing the amount of particulate emissions from diesel
engines used in metal and non-metal underground mining.
13. The emissions control system of claim 1, in which said
synthetic diesel fuel comprises a hydrocarbon solvent formulated
for reducing the amount of particulate emissions from diesel
engines used in off-highway, metal and non-metal mining, and coal
mining operations.
14. The emission control system of claim 1, in which said synthetic
diesel fuel comprises a hydrocarbon solvent formulated in the
boiling range of crude oil and useful for the reduction of
particulate emissions from diesel engines used in off-highway
applications, and said apparatus being from a class including
diesel particulate traps, exhaust catalytic converters, or diesel
particulate scrubbers.
15. A synthetic diesel fuel for low emissions control in diesel
engine equipment/machinery, said fuel having a Cetane rating in the
range of 60 to 100 and the following properties: (1) a sulfur
content of less than 1.0% (2) an aromatics content of less than
1.0% (3) a nitrogen content of less than 1.0%.
16. The synthetic diesel fuel of claim 15, wherein said fuel is
formulated to burn so as to produce a substantially lower "dpm"
content in the range of 20% to 40% in emission gases relative to
conventional diesel fuels.
17. The synthetic diesel fuel of claim 15, wherein said fuel is a
linear paraffin-linear olefin composition with a minor percentage
of branch paraffins and branch olefins.
18. The synthetic diesel fuel of claim 17, wherein said fuel has
less than 5.0% of petroleum-based diesel fuel additive to enhance
lubricity.
19. 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;
providing a supply of the fuel for operating the diesel engine to
thereby effect a substantial reduction of DPM content in the
emissions gasses therefrom; and passing the engine exhaust
emissions through discharge filtering means or directly to
ambient.
20. The method according to claim 19, including formulating the
synthetic diesel fuel to have a Cetane rating in the range of 60 to
100.
21. The method according to claim 19, in which the synthetic diesel
fuel is formulated to reduce particulate matter in discharged
engine emissions by 20% to 40%.
22. The method of claim 19 in which said discharge filtering means
comprises one of a class including particulate traps, particulate
scrubbers and catalytic convertors.
23. The method of claim 19 including the step of using the diesel
engine to run equipment/machinery in off-highway, metal/non-metal
mining and coal mining operations.
24. The method according to claim 19, including the further step of
pre-filtering the synthetic diesel fuel upstream of the diesel
engine to remove non-combustibles therefrom.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation-in-part of U.S. application Ser. No.
11/194,371 filed Aug. 1, 2005 which was a continuation-in-part of
application Ser. No. 11/074,595 filed Mar. 8, 2005, the entire
disclosures of both earlier applications being incorporated herein
by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to diesel fuel systems, and
more particularly to diesel systems and methods for substantially
reducing hydrocarbon and diesel particulate matter levels in diesel
exhaust emissions to safe environmental levels particularly in
underground mining.
[0004] 2. Description of the Prior Art
[0005] 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
catalytic converters 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.
[0006] 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) or just "particulate matter" (PM). Aside from the
environmental interests and governmental regulations for 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
classes of diesel engines operating underground mining
machinery.
[0007] 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.degree.-1100.degree. 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.degree. 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.degree. F.) combustion temperature of diesel
exhaust gases would be carried to the soot trap thus producing the
probability of fires and/or explosions therein. The result is that
many 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.
[0008] 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.
[0009] 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. patents:
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 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
have additives such as detergent, surfactant or wetting agents,
alcohol, glycol or alkalis, but no specific example or function is
taught.
[0010] In addition to the rigid regulations set by MSHA for diesel
equipment operating in fiery gaseous underground mining operations
there is another class of underground mining referred to as
"metal/non-metal" such as ore mining and hard rock tunneling and
construction in general. Diesel equipment in such closed operations
may be subject to regulation by the MSHA because of the
environmental health hazards caused by particulate matter (PM)
emissions therein.
SUMMARY OF THE INVENTION
[0011] The invention is embodied in systems for reducing diesel
particulate matter (DPM) in diesel engine emissions by providing a
high 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 high paraffinic 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.
[0012] 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 in coal mining operations.
[0013] Another object is to substantially reduce carbon monoxide
levels in the final emission gases prior to discharge to ambient in
all types of mining.
[0014] Another object is to provide synthetic paraffinic diesel
fuels to thereby achieve substantial reductions in particulate
emissions from the engine.
[0015] Still another object is to provide a synthetic high
paraffinic diesel fuel formulated to produce substantially lower
particulate emissions from diesel engines, and also being useful
alone or 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.
[0016] 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.
[0017] 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 fuels and low cost
filtration systems and equipment and labor saving methods.
[0018] It is another objective to greatly improve the working
environment around diesel powered equipment in all types of mining,
especially in metal/non-metal mines.
[0019] 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.
[0020] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] In the accompanying drawings wherein like numerals refer to
like parts wherever they occur:
[0022] FIG. 1A is a diagrammatic view showing a diesel fuel system
embodying one aspect of the invention from fuel tank to emissions
exhaust;
[0023] FIG. 1B is a more detailed diagram of the diesel fuel system
embodiment of Figure A;
[0024] FIG. 2A is a diagrammatic view showing another aspect of the
invention;
[0025] FIG. 2B is a more detailed diagram of the FIG. 2A
embodiment;
[0026] FIG. 3 is an enlarged cross-sectional view of the emissions
exhaust filtering section of the FIG. 1A system;
[0027] FIG. 4 is an enlarged cross-sectional view of another
embodiment of the exhaust filtering section of the FIG. 1A
system;
[0028] FIG. 5 is a sectional plan view taken along line 5-5 of FIG.
4;
[0029] FIG. 6 is a diagrammatic view illustrating another
embodiment of an emissions exhaust filtering section of the
invention;
[0030] FIG. 7 is another diagrammatic view showing a further
embodiment of the exhaust filtering section; and
[0031] FIG. 8 is a cross-sectional view taken along line 8-8 of
FIG. 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] Emission control systems of the prior invention will be more
clearly understood with reference to the following definitions.
DEFINITIONS:
[0033] "Synthetic Fuel" is used herein as a generic term
identifying a class of diesel engine fuels that encompasses
synthetic fuel blends and specified solvent fuels. Synthetic fuels
are produced by processes, such as Fischer-Tropsch (F-T), for
converting gas-to-liquid (GTL) or coal-to-liquid (CTL). The
synthetic fuels of this invention are further characterized by a
high Cetane number, and low sulfur(S), aromatics (A) and nitrogen
(N) constituents resulting in a clean burning fuel having low PM
emissions.
[0034] "Synthetic fuel blends" is used to identify a form of
synthetic diesel fuel having a preponderance of synthesized
components combined with a minor portion of a petroleum-derived
constituent.
[0035] "Solvent fuels" is used herein to identify a group of
products synthesized by F-T processes or the like and having the
characteristics of synthetic fuel and can substitute therefor as
low PM emission fuels.
[0036] "Fischer-Tropsch" also called "F-T" is used generically
herein to identify chemical processes for the conversion of natural
gas into liquid fuel (the GTL process) or the conversion of coal
into liquid fuel (the CTL process).
[0037] "Off highway" (or "off road") as used herein shall mean any
diesel equipment not registered for or meeting emissions and
vehicular standards for highway and street operation
[0038] "Non-road" as used herein shall encompass off highway diesel
equipment and more specifically apply to mobile vehicles and
equipment in the following categories:
[0039] airport ground support
[0040] agricultural equipment
[0041] construction equipment
[0042] forestry and logging equipment
[0043] industrial and commercial equipment
[0044] recreational off road vehicles
[0045] recreational marine vessels
[0046] residential and commercial lawn and garden equipment
[0047] underground mining and oil field equipment
[0048] "Coal mine" or "coal mining" is used herein as a
comprehensive term that includes any fiery gaseous underground
mining operation wherever class 32 and/or class 24 diesel
equipment/machinery is designated.
[0049] "Metal/non-metal mine" or "metal/non-metal mining" is used
herein as a generic or comprehensive term to mean any type of
underground mining that does not have a fiery gaseous environment
requiring diesel equipment/machinery in compliance with class 32 or
class 24 MSHA regulations, such as ore mining and hard rock
construction operations.
[0050] Referring to the diagrammatic overview of a diesel fuel
system of the invention as shown in FIGS. 1A and 1B, this system
includes a fuel delivery section FD including tank 10 and an
emissions exhaust section EE between the diesel engine 12 and
ambient.
[0051] The fuel tank 10 of the fuel delivery section FD according
to the present invention provides a supply of synthetic 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
so-called 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 of all types especially wherein expensive
additional equipment and/or increased labor may have heretofore
been required such as to remove particulate soot traps for
regeneration (cleaning) outside the mine.
[0052] 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 olefinic diesels. The synthetic fuels may include
a small part of a petroleum based product for lubricity.
[0053] The synthetic diesel fuel of the invention has substantially
no sulfur, nitrogen or aromatics, i.e., less than 1.0%. It has a
high Cetane number above 60, in the range of about 60 to 100 and
preferably in the range of about 65 to 80. 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% 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.).
[0054] In another example, 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%.
[0055] 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).
[0056] 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 substantially free from air, water and
other unwanted gases or non-combustible contaminates. Thus, with
reference to FIG. 2 in the preferred embodiment, the fuel delivery
section FD of the diesel system includes a source of pure highly
paraffinic fuel 10, 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.
[0057] 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.
[0058] 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%). Accordingly, it is now recognized that the use of
certain selected synthetic diesel fuels to power diesel equipment
in various mining operations such as metal/non-metal mines will
result in a substantial reduction in PM emissions, thereby
improving environmental conditions and meeting MSHA objectives.
Nonetheless, for the most part the unburned hydrocarbon or PM
content of engine emission gases, as in the past, may continue to
be a major safety and health concern in the operation of diesel
engines in many environments--particularly in closed, poorly
ventilated areas such as underground mines.
[0059] 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").
[0060] Referring to FIGS. 1A, 1B and 3 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
emission 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.degree. to
1100.degree. F.) from the surrounding ambient. In FIG. 3 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 arranged
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.
[0061] 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 for off
road diesel applications. 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 predetermined
volume of 20 to 90 gallons.
[0062] 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.
[0063] 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. 3, first baffles 44 are arranged to extend upwardly
from the floor 46 of the tank or just above the floor, and have
upper ends 44a 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 45a 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 there between and being connected around the baffle end
margins (44a, 45a), 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 an imperforate section of
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. Because of the MSHA regulation limiting exhaust gas
backpressure to about 34 inches mercury, it may be necessary to
limit the number of baffles to two--one upward baffle 44 and one
downward baffle 45. In the FIG. 1B embodiment in which the tank 33
may hold a water bath depth of about 12 to 14 inches, the two
baffles (44, 45) would result in an exhaust gas flow path of about
28 to 34 inches. Thus other dispersion means for exhaust gases in
the tank have been found beneficial and will accommodate a water
bath depth up to 18 to 20 inches mercury.
[0064] Referring now to FIGS. 4 and 5, in another embodiment of the
invention the vertical baffles (44, 45) of FIGS. 2 and 3 may be
eliminated. In FIGS. 4 and 5, the scrubber tank has an exhaust
intake 334 connected by exhaust pipe 335 to the exhaust manifold
(not shown) of the engine 12 and being covered by "Thermogram"
insulation 336 or the like. The tank has an internal extension pipe
337 of larger size connected to the exhaust pipe 335 and extending
below the level 338 of the water bath WB. Gas discharge diffuser
means 339 are provided at the exit end of the exhaust extension
pipe 337 to break up and disperse the emission gases discharged
into the water bath WB. For illustration purposes, in this
embodiment the diffuser 339 is bifurcated to form a pair of
parallel elongate pipes 339a and 339b extending near the bottom 346
of the tank 333. These discharge pipes 339 may be round or flat or
are otherwise constructed and arranged to enlarge the volume
capacity of the diffuser (339) to reduce flow resistance at the
point of gas discharge downwardly and outwardly through a series of
ports 340 into the water bath WB. It will be understood that a wide
variety of gas diffusing means may be employed. The openings 40 are
preferably arranged along the bottom and lower sides around the
diffuser 339. 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. In addition, it may be
desirable and even beneficial to provide an optional horizontal
baffle plate 341 across the tank 33 above the diffuser branches
339a and 339b to thereby increase the percolation effect through
holes 341a and provide a more turbulent intermixture of the
emission gases in the super-wetting solution.
[0065] Due to the high velocity of exhaust gases flow into the
water bath and the desire to obtain optimum intermixture as surface
contact there between, the internal extension pipe 337 may be twice
the size of the exhaust pipe 335 and open into diffuser pipes 339a
and 339b 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 and the 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 (at 327A). 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 341a) 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.
[0066] Referring now to FIGS. 2A and 2B, it will be seen that
synthetic diesel fuels of the present invention may be used in
systems not requiring any final hydrocarbon clean-up or other PM
filtration of emission gases. Thus, the exhaust 435 from diesel
equipment operating in metal/non-metal mining may be connected to a
catalytic converter CC having a casing 488 with sound absorbing
materials 490 and/or baffle members 491 constructed and arranged
interiorly to provide circuitous exhaust gas flow paths as well as
muffle diesel engine 412 operating noises. It will be apparent that
the metal/non-metal mining of ores and rock do usually not involve
gaseous atmospheres where the PM/DPM problems with potentially
explosive hydrocarbon build-up may exist.
[0067] The following further 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".
[0068] "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.
[0069] 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).
[0070] "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.
[0071] "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.
[0072] "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.
[0073] "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.
[0074] 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.
[0075] 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.degree. to 1100.degree. 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.
[0076] 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 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 scrubber
attracts and holds the DPM at least 3 to 5 times faster than
previous scrubbing methods.
[0077] 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.
[0078] 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, and the chemical hydrocarbon cleaner
utilized in the wetting composition preferably comprises a nonionic
surfactant.
[0079] 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).
[0080] 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.
[0081] 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
available from General Electric (Waterford, N.Y.), such as those
sold under the product designations AF900, AF9010, AF9020 and
AF9030.
[0082] 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.
[0083] 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, 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 in the form of a colloid.
Suitable non-limiting examples of organic solvents include alkylene
glycol ethers such as dipropylene glycol methyl ether.
[0084] One representative preferred aqueous wetting composition
useful in treating diesel emission gases comprises a chemical
hydrocarbon cleaner in the form of 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.
[0085] 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.
[0086] 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.degree. to about 175.degree. 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.
[0087] 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.
[0088] From the foregoing, it will now be apparent that the
selection and use of linear paraffinic-type synthetic diesel fuels
alone or in combination with an emission gas scrubber produces
remarkable results in clean-emission performance of underground
diesel equipment in both metal/non-metal and coal mining
operations. The particulate toxins normally found in diesel fuels
and diesel emissions can be reduced by 20% to 40% at the engine
performance level alone, 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).
[0089] 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 100, and preferably in
the range of about 65 to 80. The scrubber tank 33 of the FIGS. 3
and 4 embodiments holds a water bath having a major water
constituent (e.g., typically from about 20 to about 90 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 and inefficiency of present prior art systems.
[0090] Referring now to FIG. 6, 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. 6 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. 3 embodiment,
in FIG. 6 the insulated diesel exhaust pipe 135 connects from the
engine (12) to the tank 133 at 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
such as the FIGS. 4, 5 embodiment and for a modified and baffle
system (144, 145) 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. 6 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.
[0091] FIG. 6 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 90 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. 6 is not static as the tank 133 has an outlet 174 for
regulating the outflow 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.
[0092] Still referring to FIG. 6, the small volume tank 133 is
shown with at least one baffle means 144 extending upwardly from
adjacent the floor 146 and at least one 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.
[0093] 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.
[0094] Referring to FIGS. 7 and 8, 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.
[0095] The aqueous solutions used in the FIG. 6 and FIG. 7
embodiments will be the same as previously discussed, and only the
respective delivery and mixing of exhaust gases therewith is
different.
[0096] 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.
* * * * *