Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
l~S~6~
.
BACKGROUND 0~ THE INVEN~ION
- The pXesent invention relates to heating systems in
which a mixture of a ~uel vapor and air are burned flamelessly
on tbe surfaoe of a catalystO The invention relates par-
ticulaxly to the rapid and efficient starting o~ the
S combustion of tha fuel when both the;fuel and the ~atalyst
-; are initially aold; i.e., at a temperature near room
temperatUre or lower.
The catalytic oxidation of;hydrocarbons, alcohols, and
~ other chemicals at elevated temperatures has bèen practiced
~ ef~ioiently~for many years in i~dustrial pro~esses, and more
recently in such appli¢ations as small space heaters fueled
~by propane, A characteri~tlo of~suoh applioations is that
-they operate stsadily for xelatively long periods, and are
~ started ~rom an initially cold state o nly in~requently~ Thus
15~ the oat~lytic space heater can be ignited with a match, and
lasge ~industrial oatalytic sysbems~can be brought slowly~up
;to operating temperature by auxiliary heaters.~ Suoh systems
would~be;more convenien~ly started by a self igniting cataly~t~
o~oertain applioations whiah might be most advantageously
~20 ~ ~ served by cataly-tio heaters~ however, tha heating pexiods are
very short and the system must be heated frequently from a
~0517G9
cold start; hence very rapid and efficienk initia~ion of
combustion is mandakory, and an auxiliary heating system
for starting cGmbustion is unaccep-table. One such applica-
tion is the heating of shave foa~n or cosmetics dispensed
from an aerosol ean, where a few grams of material must
be heated about 50~ to 80~ in a period of lO to 20 seconds,
or l~ss. In this case the heating system must be small and
inexpPnsive, but capable of developing high heating intensities
very quickly~ and also capable of completely burning the fuel
without production of noxious combustion products. It is also
imperative that the system be highly efficient in converting
and transferring the heating value o the fuel into the fluid
which is to be heated.
~xp~r~ h~0 ~hgW~ h~W~v~J ~h~ 6U~blq ~ U~h
~15 a~ hydrooarbons and ~la~ho1s, whe1l vapo~z~d and mJx~d wL~Il
aix, will not s1tart to burn spontaneously when brought into
contaat with catalysts of the types commonly used, u~less
the catalyst or th0 uel, or both are preheated~
A further dif:fiaulty en~ountered in the use of conven~
tional catalyst results fxom the act that the catalytically
active metal, for example platinum black, is mosk effective
when supported upon highly porous base materials such as
- 3 ~
7~
gamma alumina or silica gel, which are highly hygroscopic~
Thus~ between heating periods when the syste~ is cool, the
catalyst support material adsorbs moisture from the ambient
air which greatly reduces the activity of the catalyst.
This will completely block the spontaneous oxidation of
preferred fuels such as methanol oll the surface of the
catalyst when both catalyst and fuel are initially coldO
Xt is also highly desirable -that catalytic heating
systems for applications such as those mentioned above usa a
fuel whose vapor pressuxe is higher than atmospherio so that a
, high velocity jet of fuel vapor can be used to aspirate the
air required for aombustion, thus avoiding the need for pumps
or other pressurizing devices~ Thus~ p~re methanol, one of
the mos-~ ~a~:Lly aataly~oally c~tld:l2~ fu~ 3 oRnnO~ be
dd wJ.thn~ ~m~3 p~ u~e s~ e:r~lng devl.o~ yd~ 3n,
another fuel which is readily oxidized catalytically, is not
as practical in these applications because of the difficulties
and cost of storing and handling this gas under high pressure.
Accordingly, objects of the present inventioD are to
provide appara1;us and a method for rapid, spontaneous ignition
of catalytic combustion with a liquid fuel~ preferably a:n
alcohol, which i5 effective at low temperature relative to
~S~7~
operating temperature and in th~ presellce of moisture in the catalyst mass.
A further object is to i)rovi.de catalytic combustion with high
; efficiency o~ fuel utilization and without production of noxious coMbustion
products.
STATEMENT OF THE INVENTION
This invention relates to ca.talytic fuel combustion apparatus
comprisirlg: a combustion chamber forming a fuel inlet and an outlet and
a combustion path therebetween, a fuel- and air-permeable mass of catalyst
in the chamber, means containing hydrogenous fuel in liquid and vapor phases,
and conduit means for supplying the fuel to the fuel inlet in both phases.
This invention also relates to a catalytic combustion method com-
prising: supplying a hydrogenous fuel in both liquid and vapor phase,
directing fuel in one of said phases on a fuel- and air-permeable mass of
platinum family catalyst in a concentration effective to initiate spontaneous
catalytic combustion, and flowing fuel in the other phase through a further
catalyst mass of concentration effective to extend fuel combustion initiated
in the first said mass.
According to one aspect of the invention catalytic fuel combustion
apparatus comprises a combustion chamber forming a fuel inlet and an outlet
and a combustion path therebetween, and a fuel- and air-permeable mass of
catalyst in the chamber the mass including a relatively high catalytic
concentration at the inlet and a relatively lower catalyzer concentration
toward the outlet.
Further according to the invention the apparatus comprises a
container of hydrogenous fuel connected by conduit means to the inlet to the
combustion chambe:r. Preferably the container holds fuels in both liquid and
vapor phases supplied to the chamber in both phases.
Still further according to the invention the fuel is supplied in
one phase for spontaneous ignition and in the other phase for ex~ended
combustion.
DRAWINGS
~IG. 1 is a schematic showing fluid heating àpparatus
with catalyst pellets according to -the invention;
FIG, 2 is a table of catalyst pellet symbols as used
in the figures;
~IG. 3 is a cross-section of a highly concentrated
catalyst pellet;
~IG5 4 is an elevation shown partly in section o
apparatus for rapid heating of a personal care fl~id;
FIG, 5 is a schematic showing of a heating plate
combustion system using air pressurized fuel;
FI~o 6 is a Heating Intensity versus a Fuel Mass
Flow Rate Diagram; ~nd
,
nFIG. 7 is an eleva~ion like FIG. 4 showing a
modifi.cation ~her~of~ and
FIGo 8 ls an elevation showing catalyst pellets
strung on wire,
DESCR I PrI ON
Two-Ph~se 1~ uel ~, .
F~lels
..
Catalysts - FIGS, 2 ~x~x 3 and 8
.,
Fuel low Rate - FIG, 6
Lather Heater - FIG~ 4
Stovs - FIG. 5
___ _ __ _, _ _ _ _ . _
Multi le Fuel Containers - FIG. 7
, P~
* * * * * *
The catalytic combustion apparatus of FIG, 1 comprises
a tubular metal casing 1 having an upper fuel inlet Z and a
lower combustion product outlet 3 covered by screens 4.
Surrou~ding the aombustion chamber within the casing 1 is a
:5coil of metal tube 6 with an entrance 7 and exit 8 for a fluid
to be heateci, 'rl~H r~ g v~:l.u~ 3 w:L l;h:l n the clhalllb~r 18
f.Lal~d wl~h a be~ of aatalyst pellet~ 10 of thxee types lOA,
lOB, lOC as shown in FIGSo 2 and 3.
~Fuel is supplied to the combustio~ ahamber 1 from a
.Opressurized container 11 holding a hydrogenous fuel in liquid
phase volume 12 and vapor phase volume 13 as described more
fully under the caption Fuels, Fuel from the liquid vslume
is fed to a conduit 14 through a metering valve 16 whose
rotatin~3 plug 17 has a space 18 or holding a predet~rmined
amount of fuel which is released into the conduit upon 45
counter clockwise rotation of the plug from the position
shown in ~IG. l~ The metering valve plug 17 is cooxdinated
wi th the plug 22 of a vapor valve 21 by a mechanical coupling
l9. The vapor valve plug 22, upon 90 rotation from the
position shown~ connects the vapor volume 13 with a vapor
conduit 24~
The liquid fuel conduit 14 leads to an atomizing nozzle 26
within an air aspirator 277 the nozzle spraying the metered
amount of liquid fuel in fine droplets toward the fuel lnlet 2
to the combustion chamber lo rmmediately lnside t~e inlet is
a mas~ o;f ~t~l.y~ p~ t~ lO~ wi.th ~ hi.~h con~en-~r~.i.nrl o
aatalyst in the platinum family described more ~ully hereinafteI
L~ und~ UAp ~.~l C~ ~ h~c~g~ H~ uh ~YJ
methanol will spontaneously ignite in flameless combus tlon on
contact with a high platinum family concentration. Simultaneously
with, or shortly aftex iynition fuel in vapor phase is supplied
through conduit: 24 to a nozzle 20 with an orifice 25 whi.ch
meters the co~tinuous flow of vapor and directs it in a jet
28 through the convergence 29~ throat 31 and diver~ence 32 of
the aspirator toward -the ~uel inlet 2 to the combustion ehamber~
- f3 -
The vapor-jet entxains ~ir and draws it thro~gh openin~s 32
adjacent the metering no~zle 20, mixing the fuel and air as
they approach the combustion chamber so that :flameless catalytic
combustion is sustained by continued flow of t-he fuel i.n its
S vapor phase,
Heat from the combustion is excha~ged with fluid flowing
through the coil 6, which fluid may be a gas such as air or
a li~uid such as water, either of which can be circulated
through radiators or othex apparatus.
A catalytic heater of th~ type described above and
having a double helical coil as shown in ~IG. 4 was tested
to determine its characteristics as a water heater/ ~or
thi.s purpos0~ the inlet was connected to a water source whioh
l~rovlded a eonstant water 10w ra-te o~ 1.38 yrams p~r seoon~l~
1~ The m~asura~ t~mp~A~UrH ~ o-~ ~h~ wa~e:~ w~ B ~, Th~
total volume o~ the catalytic heater, iOe~ the catalyst bed,
was 8,05 cubic centimetersO l'he heating intensity o this
sys~0m was thus 202 calories per second per cubic aentimeter
or in other uni.ts 890,000 BTU pex hour, per cubic footO The
importance of this high heating i~tensity can be visualized
in terms of a familiar application such as a house heater
which might typically have a capacity of' 150,000 BTU per hour,
'6~
The catalytic heater described above scaled to a capacity
oi~ 150,000 BTU per hour wou:Ld occupy a volume of only
0~169 cubic foot7 Along with -this remarkable heat intensity
the heater operatcs with high efficiency and fuel economy,
and low pollution in its combust:ion products.
L~ _
5~76~
Fuels
.. _
Of the many available fuels only four are known to ignlte
spontaneously and safely in the presence of a sl~itable catalyst
at normal ambient temperature, that is 40 to 100 F. Other
fuels such as for~aldehyde, foxmic acid and hydrazine hydrate
will oxidize spontaneously but are toxio9 inconvenient and
dangerous to handle. These safe spontaneously igniting f~lels
are hydrogen and the three lower alcohols, methanol, ethanol
and isopropanol, methanol being preerxed While other hydro-
carbons such as natural gas or the lower alkanes may be used
as a primary fuel after ignition they will not start catalytic
combustion spontaneously. Th~s either in industrial processes
using primary fuels after ignition or in intermittently started
oatalyl~lo oolllbl~xtion n~paxa~lls ns~rl~ ~he ~t~rt~ng ~uel a~ an
~p~r~t.lng .r~ , khe l~wer ~la~h~ls ~r~ u~ePul,
Whereas pr:imary fuels are delivered frorn a pressurized
system, smallex apparatus ru~ on the starting fuel requires
fuel p~essuriza1;ion by air or a sel~ press~ri2ing fuel. ~ox
catalytic combustion the lower ethersJ dimethyl and methyl
and
ethyl ether,hower alkanes and alkenes have been ~ound to be most
suitable as a pressurizer when mixed with the lower alcohols~ The
mix~ure of methanol and dimethyl ether as a catalytic uel is men-
tioned generally in United States patent 2,764,969 to Weiss. Such
I
~C~53~7~
a fuel mixture has, however, been found to have a rather
critical range of alcohol ether proportion, p~rticu].axly i.n
small fuel containers used in portable or compact self~
igniting combustion units such as are described herein5 While
S the ether is a fuel, the alcohol which is essential to start
combustion has a substantially lower vapor pressure~ so that as
fuel is withdrawn from the vapor space of a fuel container
the concentration of ether in the liquid phase drops resu].ting
in a drop of vapor pressure, When the pressure is reduced to
the point that the heating rate is below the useful limit a
residue of unusable fuel remains in the container. When the
pressure drops to atmospheric the liquid residue is sub-
. stantially all alcoholO I have found that if the alcohol
is in excess of 25% by vol~me of the initial al~ohol~qth~x
tur~ ~n ~rlu~abl~ :r~l.du~ u~l ~n ~XQ~1913 o~
35% of the ori~inal ~uel ~olume will result in substantial
economic waste~ On t~e other hand a proportion of approximately
5% alcDhol by volume is required to lnsure spontaneous ignition~
Within the range of 5% to 25% alcohol (e,g. methanol~ to 95%
to 75% etller (e,g, dimethyl ether) lO~o alcohol and 90% ether
is pre:eerredO
; Although the loss of pressure and waste of alcohol could
be avoided by withdrawing fuel from the liquid volume 12 of
~5~6'~
the contalner 11, the liquid fuel wo~lld be evaporated in the
c~sl)irator 27 or in the mass 10 o:f catalyst pellets~ Such fuel
evaporation produces a refrigeration effect which will reduce
or inhibit ignitlon or continued combustion~ Howeverg acc~rding
to one aspect of the invention, metering only ~ small amount
of alcohol-rich liquid fuel does not inhibit spontaneous
i~nition, and subsequently supplying fuel pre-evaporated in
the fuel container 11 is~lates the co~bustion chamber 27 from
-the refrigeration effectO The fuel container can absorb and
dissipate the .refrigeration remotely from the combustion
chamber. Further the fuel container has sufficient mass and
external heat transfer surface to prevent excessive chilling
of -the fuel therein.
While t]l~ alcohol-ether pressurizer mixturq desaxibed
lS ~bova h~s been fv~lnd to ~o a rel:Lab.l.~ staxtir)g arld rullr~
~uel~ particularly in ~ single fuel oontainer delivering tha
f~el i~ liquid and vapor phaseg several advantages have been
fou~d in the use of lower Alkane ~ alkene and cyclo hydrocarbons
with less than ~ive carbon atoms as a pressuri~er for the
alcohols and as a primary, separately supplied fuel fox con
tinued catalytic combustion aftex spontaneous ignition wi.th
a lower alcohol-fuel mixture AS described under the heading
Multiple ~uel ContainersO Thus the preferred fue].s for
1~,
~C~5~
use in the present apparatus and method comprise not onl~
ethers with less than four carbon atoms incl~ding dimethyl
and methyl ethyl ether, but also the lower alkane and allcene
hydrocarbons with a boiling point below nominal room temperature
S including methane, ethane, propane including cyclo propane,
butane including n~butane and isobutane, ethylene, propylene,
butene-l and -2, butadiene and butylene including isobutylene.
As a pressurizing constituent of the lower alcohol starting
mixture the lower hydrocaxbons mentioned ~ay comprise as little
ZO as 5% of the fuel mixture with 95% of the mixture rich in
alcohol. As previously noted the alcohol may be as low as 5%
by ~olume, but higher concentrations approaching 95% by volume
are preferred because catalytic combustion will.start spon-
taneously more rapidly and reliably, particularly in humid
.5 wsat.hQr~ :L~ ~It~ ~nrtln~ uel 1~ Xl~h ln a.t~o~lo].. ~ mlxtllr~ o~
60~o Illath~llo~. nnd ~0% :lso~ul~n~, ~or ~x~l1l[3J.~, ~f~ords r~l.3.~bJ.e
starting in amb;ents of 90% relative humidity, and at tempera~
tures below 40 ~.
Other adval~tages of usiny the lower hydrocaxbons as a
O pressuxizer for the alcohol are that they are readily available
at low cost and are accepted as safe for personal use for
example in cigarette lighters, The lower hydrocarbons are
1~
~ _ 13a -
~5~ ~7~
quite compatible with the plasiic lin;ng material comnJonly
used in pressurized dispensing containers. They do not form
formaldehyde on combustion, have a low latent heat of
vaporization relative to the lower ethers, and a substantially
higher heat valueO
When the ignition starting alcohol mixture and a
prinary fuel supplied simultaneously with or after ignition
are in separate containers the s~arting mixture can be
rioher in alcohol and quickex and moxe reliable for spon-
taneous catalytic ignition if one of the lower hydrocarbons is
used as a pressurizer, and the primaxy fuel for continued
combustion aftex ignition need contain no alcohol and there~
~oxe will maintain its pressure until all liquid is expended.
Catalytic combustion appaxatus using lower hydrocarbons
aB a p~: 0s3~ cl ~ t)~ .m~r~ e9~ r~ t~
und,~ p-ti~n ~= ~.
.
_ ~3b -
c~
s~
Catalysts w ~T~S, 2 a ~ ~ 3 ~n(3 ~
A platinum family catalyst is necessary for spontaneous
ignition of a hydrogenous fuel. The platinum family includes
the platinum group of metals platinum, iridium and osmium,
and the palladium group of palladium~ ruthenium and rhodium~
Preferably the platinum amily catalyst is supported on a
catalytically active porous body composed of one or more of
,.
the porous for~s of alumina. The porous catalytic suppor-ts are
'~ relatively inexpensive ~Nhereas platinum family metals are
very e~pensive~ Therefore, prior catalytic bodies have very
LO little platinum ~amily metal. Porous catalytic pellets wîth a
platinum content of approximately 0.05 to 0.2% by volume are
used in industrial processes which are brought to combustion
~` tempcrcltur~ ~u~ whicll c~nllo-l ~ ltl~e ~pon~an~ous L~lltLon.S:lmilar~y ~he flbove na~led porou~ bodl~s oalln~ e :Inltl~-t~
L5 spontaneous combustion, and are, moreover, powerful adsorbers o~
atmospheric moisture ànd ~uel at ordinary temperaturesO ~or
example, a bed o~ 0.1% platinum blac~ supported on the surface
o small (1/8 inoh~ spherical pellets of highly porous gamma
alumina, after sevexal ho~lrs o~ exposure in a combustion chamber
'O to air of normal humidity, will not catalyse the oxidization of
an ~ir~methanol fuel at room temperature. Nor will such a
catalytic body initiate spontaneous combustion o~ liquid or vapor
phase fuel mixture o~ 5% to 25% meth~nol in dimethyl ether.
._ IL¦.,
'
I have found that the ignition inhibiting effect
oE adsorbed moisture is overcome by substantially increasing
the platinum family content of the porous catalytic body to
at least approximately 2% and in a range up to 60% of the
initial weight of the porous body.
Below approximately 2% spontaneous ignition does not
occur and an undesirably high amount of formaldehyde is
produced. Above 60% the time for combustion to start increases
markedly. Within the range of 2% to 60% platinum, a platinum
content of over 16% to 40% of the initial porous body weight
with which the platinum is integrated assures the fastest
starting of spontaneous ignition even in extreme, naturally
expectable humidity.
Catalytic bodies with such a high platinum family
content are9 of course, relatively costly but I have further
found that only a small proportion of the catalyst bed 10
within the combustion chamber 27 need consist of the enriched
or highly concentrated 2% to 60% platinum family bodies lOA,
symbolized by cross hatched areas in FIG. 2, and that less
costly platinized porous bodies lOB with under 2% platinum
family concentration symbolized by shaded areas in FIG. 2,
and unplatinized porous bodies symbolized by unshaded areas
in FIG. 2, may be used as the major portion of the catalytic
mass 10.
c~
~5~76~D
/ ~he preferxed orm of enriched catalytic pellet is a
-I porous suppor-t o~ gamma alumina with over 16% to 60% platinum
/ blacls or palladium superficlally dispersed in the alumina as
shown in FI:~ 3. Alumina and silica with less than 16% platinum
will start catalytic combust.ion in a limited range of humidity
` ~ and is not reliable for starting under unfavorably high hum:idity
which will normally occur under natural conditions. Gamma
alumina with over 16% and preferably 40% or less platinum
j family metal will reliably start spontaneous ignition under
natural hyper humidity and even extremely artificial hypex
humidity within 1 to 8 seconds~
rn special applications where starting is desired in all
; cases in one or two seconds, it is preferable to use enriched
(16~a ~ ~i pla~nu~n ~aml,ly m~ta~ mm~ ~lum.lnfl p~:Llqts ~tr~n~
.9 b~ dg ~ o~h~wl~ ~uppo~ ct ln~
with a resistively hea~ed ~vire 40 of nichrome stainless steel
or the lik~. . .
~ he lower tunder 2%) platinum ~amily concentration bodies
lOB may consist of platinum applied to the surfac~ o-f gamma
alumina pelletsc Herewith the catalytic activity of the metal
is augmen-ted by the catalytic activity o the gamma alumina,
which together cause complete ox.idization o~ methanol with little
or.no formaldehyde production~
~ 1.6 -
~5~7~
The unplatinized catalytic ~pellets lOC are also
preferably porous gamma alumina~
The bodies lOA of high catalytic concentration
are disposed at the fuel inlet 22 to the combustion chamber
1 where they will initiate spontaneous combustion despite
tlle fuel refrigeration effect and the presence of adsorbed
moisture 9
Starter pellets lOA, although exposed to humid air
for days will ignite catalytic combustion within a few seconds
when exposed to methanol. Combustion will then dry the less
enrichecl pellets and spread through the bed.
- 16A -
7'~9
Fuel ~low Rate - ~IG, 6
A precaution should be t~ken with catalytic apparatus
to avoid unwanted and toxic products of combustion such as
the aldehydes corresponding to the alcohols and ethers in
the fuel, for example formaldehyde~ ~ormaldehyde can be
detected by its odor when present in non toxic quantities of
a few parts per million and therefore detection by odor is
a practical and safe test. Above a baxely discernable odor
fo~maldehyde is very irritating to the eyes and noseO If
ormaldehyde formation is avoided other toxic or irritating
oxidization products such as carbon monoxide, ethers or organio
acids are also avoided,
~ have found that sueh uIlwaDted pxoducts o combustion
are avo:i.(led i~ tl~e d:i.mensions o:~ the ~ppar~tu~ are ~ oted
h i;h~t one ox both c~:e two parall~el~Qrs oalled H~a~ g
L5 ~r~tensity and ~uel Mass ~low Rate are kept withill cri tical
limitsO These parameters axe defined as follows:
l ~ is the heating power absorbed
by the heat exchanger, divided by the volume of
the space occupied by the catalyst. Convenient
~0 units in which to express Heating rntensity are
~calories/(sec x cm3)]0
17 -
~5~7~
;
~`uel Mass low R~te is flow rate of the fuel vapor,
divided by the cross section of the catalyst becl
through which it flows~ Convenient units are
i ~grams/(sec x cm2)~0
- In ~IG, 6 ~uel Mass ~low Rate is compared to Heating
Tntensity with respect to formaldehyde foxmation during
catalytic combustion. Outside the shaded area substantial
amounts of formaldehyde can be detected by odor when Heating
Intensity exceeds 4.5 cal/(sec x cm3) or when ~uel Mass flow
LO rate exceeds 0~0025 gms/~sec x cm2). ~ithin the shaded area
ormaldehyde is not formed in detectable amount.
It is~ of course, necessaxy to provide suficient hsat
t~ansfer surface such that eonventio~al surface heat transfer
~oa~ n~ n~t ~oQ~ n ~ h~ ~h~ oa~l.y~ 8~ n~
1~ ~h~ ~Iuld 6l~ kh~ h~ xa~n~ ~d ~tbJ~
i~ ~IG. 1~ 9 a~d that the correct xatio of uel vapor and
air is maintained for~optimum oxidiæation. Typical dimensio~s
afording the two parameters 9 are given in the description
o Lather Heater - F~G. 4 and Stove - FIG. 5. F~x complete
combustion of methanol - dimethyl ether fuel from the vapor
phase of the container 11 of FIG. 1 the aspirator 27 should
entrain about fifteen volumes of air to one volume of fuel
vaporO An e~cess of air may produce foxmaldehyde and results
in excessive heat loss in -the exhaust.
35~76~
Lather Heater ~ FIG, 4
The present catalytic combustion apparatus being
compact and requiring a small fuel supply is particularly
practical for heating9 at daily intervals for example, of
personal care media or products such as shaving lather and
skin creams which have enhanced ef~ect when hotO Such
devices must necessarily be reliable, sae and quick to
heat -the fluid product, l~eO in a ew seconds. The fuel
should be easily replaceableO
Shown in ~IG. 4 is a hot shaving lather dispensex 40
1~ embodying the fuel supply and combustion chamber of the
fluid heater of ~IG. 1. ~ housing 41 of transparent plastie
material enoloses and supports a mctal oombustion chamber 1,
fuel container 11 and aspirator 27 like those dascribed with
respect to ~IG~ 1 except that the heat exchange aoil 6~ is a
double concentxic helix. The coil 6~ has an entrance at 7
outer turns winding downwardly toward the sereen 4 chamber
outlet 3, whence its inner turns wind upwaxd to the outlet 8.
The eoil may be aluminum tubing with an outside diameter of
':
033175 cmO and an inside diameter of 0~254 cm., the outer turns
-20 being 2.857 cm~ and the inner -turns being 1.588 cm~ in outer
diameterO The double helix coil is tiglltly wound and with the
turns close to or in oo~tact with each o-ther3 Closely wound
~S~7~j9
turns, preferably bonded together will serve to confine
the catalyst mass lO between the i~let and outlet scxeens 4
w~-thout the external chamber wall lo
Spacers 42 extending inwardly from the housing 41
slidingly conf1ne and insulate the combustion chamber 1
which rests on a leaf spring 43 yieldingly holding the
chamber in the upper position shown, The aspirator 27 is
rigidly attached to the chamber by a 1ange 44 crimped over
a flAnge at the top of the chamber. The noæzle 20 fixed
to the top of the aspirator comprises a plunger sliding in
a collar 46 formed by the housing 41. Depressing the nozzle-
plunger 20 slides the aspirator - chamber assembly downward
ag~inst the spring 43. The entrance tube 7 of the coil 6*
e~tends downwardly to a flare 47 receiving the stem valve 48
of an aerosol dispenser 49 of shàving lather or other personal
care ¢xeamy ~luid. ~he downward extension of the entrance
tuba 7 is suf~iciently xigid to open the stem valve 48 when
the aspirator - chamber assembly is depressed by the plunyer
20*, thereby r,~leasing shave or other cream through the hea~
exchange coil 6* to its outlet 8 and then th~ough a spout
laading out o~ the housing 41. During flow through the heat
exchange coil the cream is heated to a sui-table degree by
- 20 -
~s~
flameless catalytio combustion of fuel in the chamberg
Fuel is supplied to the chamber from a pressuri~ed
container ll, The fuel comprises 10% of a low~r alcohol,
preferably methanol, and 90% of a lower ether pressurizer-
S ~uel, prefer~bly dimethyl ether, the fuel mixture having
a lower liquid phase volume and an upper vapor phase
volume at approximately 3.5 Kg/cm2 pressure above
atmospheric. A predetermined amount of liquid fuel~
e.g. 0.050 ml,, is released by a metering stem valve 16~
functionally equivalent to valve 16 of ~IG. l. A c~ntinuous
flow of fuel in vapor phase is released by an upper valve
21* ~unctionally equivalent to valve 21 of ~IGJ 1~ The lower
stem valve 16~ communicates with the atomizer nozzle 26
through a passage 52 in t~e bottom wall of the housing 41
lS and a flexible plastie tube 53. The upper stem valve 21*
communicates through a passage 54 in a button 56 telescoping
over the stem valve 2,1*, and thenoe through a flexible plastio
tube 57 to a filter 58 within the nozzle 20*~ The pressurized
fuel containex ll is replaceably and slidi~gly confined in a
socket 59. Dep:ressing the button 56 actuates both stem valves
16* and 21* approximately simultaneously~ the container
itself comprising a mechanical link between the two. However,
the internal spring of the upper stem valve may be stronger
~5~6~
than ~hat of the lower to delay ope~ing of the ~lpper valve
21* a fraction of a second after opening of the lower stem
valve 16*.
In use the button 56 is depxessed opening the t-wo
S ~alves 16* and 21*9 Valve 16* delivers the methanol xich
starting fuel droplets to the enriched pellets lOA at the
inlet 2 to the combustion chamber causing spontaneous
catalytic ignition~ The button is held depressed for a
few, e.gO 6, seconds until delivery of fuel vapor through
the upper stem valve 21*9 nozzle 20* and aspira~or 27
spreads combustion through the catalyst bed lOo At the end
of the combustion period a glow in the comb~lstion chamber
can be seen throu~h the transparent housing 41, and the
. aspirator which may be made o~ heat resistant transparent
plastic or may :include a light pipe 30 transmitting the
glow of the oatalyst bed~ The nozzle - plunger 20* is then
depressed or about 6 seconds to deliver about 3 grams o~ hot
oream to the spout 51 at about 80C, tha button being r21eased
about 2 seconds later.
In a lather heater o~ the type described the space
occupied by catalyst pellets was 4~97 ~m3 with a section
across the path of fuel ~low o 2.61 cm2~ The s~arter
- catalyst 10~ at and near the fuel inlet 2 oonsisted of 25
_ ~2 -
7~i~
pellets of gamma alumina, each approxlmately 00318 cm.
in diameter, and superficially fillecl with p~atinum
adding 40% to the initial weight of the gamma alu~inaO The
ba].ance of the catalyst space was fllled with pellets lOB
s;milar except that they had a low concentration of approxi~
mately 0~1% platinum by weight.
The aspirator 27 comprised a converging section 29
blending smoothly with a throat 31 of 0.318 cm. diameter~
which in turn blended with a dive.rgence 32 whose total angle
of diverge~ce was 10 and whose widest diameter was 2~22 cm~
The ~uel Mass ~low Rate was 0,0023 grams/(sec x ~m2)
and the Heating Inte~sity was 3,8 cal~/(sec x cm3~0 The
com~ustion products contained no formaldehyde detectable by
odor.
7~
Stove - Fl~. 5
~ _ , ~ . .
In addition to the heat exchange systems of FIGS, 1
and 4 the present combustion apparatus is quite useful
and efficient in the form of the stove plate or space
heater shown in ~IG, 5,~ particularly in a confined
space ~uch as a boat cabin where extxa precautions against
fire and noxious fumes must be taken~
To reduce fire ha~ard a container 11* of alcohol
(e,g, methanol) alone without a self-pressurizing additional
fuel is pressurized as needed with air supplied by a hand
pump 61, The container has a lîquid phase volume 12 connected
by a pipe 62 to a valve 64, and a vapor phase volu~e 13
connected by a pipe 63 to the valve~ The valve body 66 has
~ h~l~iiny SpAo~ ~7 ~or a pr0det~rm~ ed amoullt o~ u~. vapo~a
In this case an alcohol rich vapor is effective to ignite
spontaneous combustion when the valve body is turned 45 counter
¢lockwise delivering the predetermlned amount of alcohol vapor
through a pipe 58 to an atomizer 69 also capable of converting
liguid fuel into droplets, The valve body 66 also has an
elbow shaped pa'ssage 71 which upon rotation of the body 90
more o~ less connects the liquid volume 12 and pipe 62 with a
pipe 72 leading through a catalyst bed 73 and a second va:Lve
82 to a jet no~zle 76 like nozæle 20 of FIG, L. The liqu:id
- 2~ _
~L/D 51 d~
fuel is vaporized in p~ssing throu~h the ignited catalyst
bed ~nd entrains air ;n an ~pixator 77. The aspira-tor leads
to a folded combustion chamber formed by an upper, circular,
metal hot pla~e 78, bottom and side insulating walls 79 and
a metal partition wall 81~ The plate and walls de~ine a
combustion path with a fuel inlet 2* thence running first
outwardly then inwardly to an outlet 3*9 Here the combusti.on
path is folded over-and-under in a vertical plane, although
it may be folded side-by-side in a horizontal plane~ In
either case the outlet is in thermal conductive relation
through the metal partitio~ wall 81 with the inlet where high
heating intensity due to the high catalyst concentration pellets
10~ provides heat txanser to the pellets at the outlet and
afords more complete combustion and avoidan~e o formaldehyde
.15 formationO These advantages may be further promoted by
disposing a few high eatalyst concentration pellets lOA at
the outlet 3* :filling the xemainder ~f the combustion path
with low catalyst concentration pellets lOB and with
platini~ed yamma alu~ina pellets lOC.
While the lower ~lcoho.ls, parti~ularlym~thanoll axe
safe and efic:ient fuels or portable or mobile stoves and
heaters, the stove of ~IG. 5 may be run on hydroca~bon uels
sueh as propane or natural gas i they are available~ In
-- 2~ _
~5~7~
~IG~ 5 a gas main 83 also leads to the second valve B2.
Af-ter ignition by alcohol from the contairler 11.* the valve
B2 may switch fuel supply from the container 11* to the
gas main 83.
It should be understood that the present disclosure is
for the purpose of illustration only and that this invention
includes all modifications and equlvalents which fall within
the scope of the appended claimsO
_ 2~ -
~cisl~ 1 C~n'ainers - FIG 7
___
The hot shaving lather dispenser 40* of FIG, 7 is
identical in construction and operation with the dispenser
40 of FIG. 4 excep~ that the socket 59* of ~IG, ? is
adapted to receiva two fuel contai.ners llA and 11~ in place
of the single container 11 of ~IG. 4~
The lower fuel container llA oontains an ignition
starting fuel mixture of a lower aleohol preferably with one
or more lower alkanes or alkenes as pressurizer as described
at the end of the section caption2d Fuels, As much as g5% of
the mixture may be alcohol which is supplied from the liquid
mix~ure 12A oocupying all but the top gaseous volume 13A
within the container llA, A predetermined arnount of liquid
a:l.aohol :~ioh ~u~ el~ d ~y ~ stem valve ~ ke thAt of
: FIG, 4 and conducted through the tube 53 to an atomizing nozzle
which forms and directs aloohol ricb droplets on the starter
-: catalyst pellet~ lOA at the ~uel inlat 2 of the combustion
chamber 1 thereby spontaneously initiating catalytic oombustion~
The upper container llB holds a press~rized uel, preferably
one of the lower ethers, alXanes ox alkenes previously described~
Its stem valve 21* engaged by the button 56 is opened eontinuously
m while the button is depressed whereas the stem valve 16* of the
lower container llA opens only momentarily. The upper valve 21*
- 27 -
~ay operl .simultaneou~ly with or shor~ly after the lower
valve 16*~ and is held open a few seconds or until a glow
can be seen in the catalyst bed lO, The upper valve 21*
releases vaporized fuel through a tube 57 to a metering
n~zle 20* which directs a je-t of fuel vapor,
Whereas a two-phase alcohol-ether fuel is advantageous
in -the single fuel container of FIG, l, the alcohol hydrocarbon
s~ar~ing mixture in lower container llA and a hydrocarbon
primary fuel in the separate upper con~ainer llB of ~IG~ 7
have the advantages in the low cost and ready availability
of accepted hydrocarbon fuels compatiblP with conventional
plastic container linings. The lower alkane and alkene
hydrocaxbons do not form ormaldehyde and as pressurizers
allow a higher percentage o~ alcohol in the starting mixture
and have high heatin~ value both as a pressurizer in the
lower container llA and as a primary fuel in the upper con-
tainer llBo
It should be ~nderstood that the present disclo~ure is
for th~ purpose o illustration only and that this invention
includes all modifications and equivalents which fall within
the scope of th~ appended claims.
_ 28 -
