CA1051769A

CA1051769A - Catalytic fuel combustion apparatus and method and catalyst therefor

Info

Publication number: CA1051769A
Application number: CA248,583A
Authority: CA
Inventors: Richard E. Rice
Original assignee: Comstock and Wescott Inc
Current assignee: Comstock and Wescott Inc
Priority date: 1975-03-24
Filing date: 1976-03-23
Publication date: 1979-04-03
Also published as: FR2329345A1; FR2329937A1; GB1547810A; FR2305690A1; FR2329739A1; DE2612560A1; JPS51131928A

Abstract

ABSTRACT

A flameless catalytic combustion apparatus includes a combustion chamber with a hydrogenous fuel inlet and a mass of catalyst in the chamber between the inlet and an outlet. Preferably the catalyst mass comprises porous pellet bodies supporting varying high and low concentrations of platinum family metals dispersed therein. For spontaneous starting of combustion the fuel is one of the lower alcohols and the high catalyst concentration is at the fuel inlet.
The fuel may be in a container pressurized by air, or a lower ether or lower hydrocarbon which is also a fuel. Preferably separate, valved conduits from the fuel container first supply either atomized fuel droplets or air and fuel vapor to the high catalyst concentration for spontaneous ignition of com-bustion and vaporized fuel for continued combustion throughout the catalyst mass. The catalytic combustion apparatus may include a heat exchanger for fluids such as air, water or personal care foams and creams, or may be used in heating and cooking apparatus.

Description

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.

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 ~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 ~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*

~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 -

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Catalytic fuel combustion apparatus comprising: 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.

2. Apparatus according to claim 1 wherein the conduit means includes means for forming droplets of the fuel in liquid phase and directing the droplets on the catalyst mass.

3. Apparatus according to claim 1 wherein the liquid and vapor phases are in equilibrium.

4. Apparatus according to claim 1 wherein the fuel is selected from the lower alcohol group consisting of methanol, ethanol and isopropanol.

5. Apparatus according to claim 1 wherein the fuel includes a pressurizer.

6. Apparatus according to claim 5 wherein the pressurizer is a fuel selected from the lower hydrocarbon group consisting of dimethyl ether and methyl ethyl ether.

7. Apparatus according to claim 6 wherein the fuel comprises approxi-mately 5% to 25% methanol by volume.

8. Apparatus according to claim 7 wherein the fuel comprises approxi-mately 10% methanol.

9. Apparatus according to claim 1 wherein the fuel container comprises separate volumes for the liquid and vapor phases of the fuel, and said conduit means include separate connections from the liquid and vapor volumes to the combustion chamber fuel inlet.

10. Apparatus according to claim 9 wherein the separate vapor conduit means includes an orifice directing a vapor jet toward the combustion chamber fuel inlet.

11. Apparatus according to claim 9 wherein the separate liquid phase conduit means includes a nozzle dispersing liquid droplets toward the combustion chamber fuel inlet.

12. Apparatus according to claim 9 wherein the container comprises two outlet valves respectively communicating with the liquid and vapor phase volumes.

13. Apparatus according to claim 12 including a single means for actuating both outlet valves.

14. Apparatus according to claim 12 wherein the liquid outlet valve opens momentarily, and the vapor outlet valve opens continuously, with each actuation of the single means.

15. Apparatus according to claim 1 including a fluid conduit in heat exchange relation with the catalyst mass.

16. Apparatus according to claim 1 wherein the conduit means is in heat exchange relation with the combustion chamber.

17. Apparatus according to claim 9 wherein the conduit means connecting the liquid volume to the combustion chamber is in heat exchange relation with the combustion chamber.

18. Apparatus according to claim 1 wherein said mass includes a relatively high catalytic concentration at the inlet and a relatively lower catalytic concentration toward the outlet and wherein the mass of high catalytic concentration is capable of spontaneous self-ignition in the presence of a hydrogenous fuel selected from the group of hydrogen, methanol, ethanol and isopropanol.

19. Apparatus according to claim 18 wherein the high concentration is in thermal radiation juxtaposition to the lower concentration.

20. Apparatus according to claim 18 wherein the concentrations extend substantially entirely across the combustion path.

21. Apparatus according to claim 18 wherein the catalyst mass is fuel absorbent.

22. Apparatus according to claim 18 wherein the high concentration is in an amount effective to self ignite a hydrogenous fuel.

23. Apparatus according to claim 18 wherein the high concentration comprises one or more metals of the platinum family.

24. Apparatus according to claim 18 wherein the lower concentration comprises one or more porous bodies selected from the group consisting of alumina, silica, zirconia, thoria, zeolites and molecular sieves.

25. Apparatus according to claim 24 wherein the porous body comprises gamma alumina.

26. Apparatus according to claim 18 wherein the catalyst mass comprises one or more metals of the platinum family dispersed in a porous body selected from the group consisting of alumina, silica, zirconia, thoria, zeolites and molecular sieves.

27. Apparatus according to claim 18 wherein the highly concentrated mass comprises a body supporting a platinum family metal added in the amount of at least 2% of the initial weight of the body.

28. Apparatus according to claim 27 wherein the metal is added in the amount of 2% to 60% of the initial weight of the supporting body.

29. Apparatus according to claim 27 wherein the metal is added in the amount of at least 18% of the initial weight of the supporting body.

30. Apparatus according to claim 27 wherein the metal is added in the amount of 18% to 40% of the initial weight of the supporting body.

31. Apparatus according to claim 18 wherein the catalytic mass com-prises a plurality of discrete porous bodies.

32. Apparatus according to claim 31 wherein the high catalytic con-centration comprises a dispersion of one or more of the platinum family metals in the porous bodies.

33. Apparatus according to claim 31 wherein the lower catalytic con-centration comprises a dispersion of one or more of platinum family metals in the porous bodies.

34. Apparatus according to claim 31 wherein the lower catalytic con-centration comprises bodies of gamma alumina.

35. Apparatus according to claim 31 wherein the high catalytic con-centration comprises a plurality of porous combustion starter bodies with a platinum family metal added in the amount of 2% to 60% of the initial weight of the porous bodies, the bodies of high concentration being distributed across the fuel inlet to the combustion chamber, and the lower catalytic concentration comprises a plurality of gamma alumina bodies with less than 2% by weight of one or more of the platinum metals disposed in contact with the starter bodies and extending toward the combustion chamber outlet.

36. Apparatus according to claim 35 wherein at least some of the gamma alumina bodies contain substantially no platinum family metal.

37. Apparatus according to claim 18 including a container of a hydro-genous fuel and a fuel conduit connected between the container and the fuel inlet to the combustion chamber.

38. Apparatus according to claim 18 including a fluid conduit in heat exchange relation with the catalyst mass.

39. Apparatus according to claim 18 wherein there is a relatively high concentration of catalyst at the outlet of the combustion chamber.

40. Apparatus according to claim 18 wherein the mass of high catalytic concentration is capable of spontaneous self-ignition in the presence of a lower alcohol selected from the group consisting of methanol, ethanol and isopropanol, the apparatus comprising means containing at least one of said lower alcohols and a pressurizer, and including means to form and direct droplets of said alcohol on said high catalyst concentration.

41. Apparatus according to claim 40 wherein the fuel containing means includes conduit means separately supplying a vaporized fuel to extend combustion initiated spontaneously by the droplets.

42. Apparatus according to claim 40 wherein the pressurizer comprises a fuel selected from the lower hydrocarbon group consisting of dimethyl ether, methyl ethyl ether, methane, ethane, propane including cyclo propane, butane including n-butane and isobutane, ethylene, propylene, butene-1 and -2, butadiene and butylene including isobutylene.

43. Apparatus according to claim 40 including valving means for separately controlling supply of the alcohol fuel and vaporized fuel.

44. Apparatus according to claim 41 wherein the conduit means includes means to meter the supply of vaporized fuel.

45. Apparatus according to claim 43 including means to coordinate open-ing of the separate valving means.

46. Apparatus according to claim 44 wherein the metering means includes an orifice for metering a continuous flow of fuel.

47. Apparatus according to claim 46 including an aspirator tube around and between the conduit means and the combustion chamber fuel inlet, said aspirator means having air inlets adjacent the orifice.

48. Apparatus according to claim 40 including means in heat exchange relation to the combustion chamber for conducting a lower alcohol to the combustion chamber.

49. Apparatus according to claim 18 wherein the combustion chamber comprises a heat exchanger.

50. Apparatus according to claim 49 wherein the heating power capable of being absorbed by the heat exchanger, divided by the volume of catalyst mass does not exceed approximately four calories per second per cubic centi-meter of catalyst mass.

51. Apparatus according to claim 49 wherein the conduit means includes valve means limiting the fuel mass flow rate to not more than approximately twenty five ten thousandths of a gram per second of flow through a square centimeter of cross section of the catalyst mass in the combustion chamber.

52. Apparatus according to claim 49 wherein the conduit means includes valve means limiting the fuel mass flow rate to not more than approximately twenty five ten thousandths of a gram per second of flow through a square centimeter of cross section of the catalyst mass in the combustion chamber.

53. Apparatus according to claim 40 wherein the combustion chamber comprises a heat exchanger.

54. Apparatus according to claim 40 wherein the heating power capable of being absorbed by the heat exchanger, divided by the volume of catalyst mass does not exceed approximately four calories per second per cubic centi-meter of catalyst mass.

55. Apparatus according to claim 40 wherein the conduit means includes valve means limiting the fuel mass flow rate to not more than approximately twenty five ten thousandths of a gram per second of flow through a square centimeter of cross section of the catalyst mass in the combustion chamber.

56. Apparatus according to claim 40 wherein the conduit means includes valve means limiting the fuel mass flow rate to not more than approximately twenty five ten thousandths of a gram per second of flow through a square centimeter of cross section of the catalyst mass in the combustion chamber.

57. Apparatus according to claim 41 wherein the pressurizer comprises air.

58. Apparatus according to claim 45 wherein the valving means supplies one fuel phase at the beginning of the fuel supply.

59. Apparatus according to claim 58 wherein the fuel comprises a liquid alcohol and a pressurizer, and the valving means supplies the liquid phase at the beginning of fuel supply.

60. Apparatus according to claim 58 wherein the fuel comprises sub-stantially only an alcohol, and the valving means supplies the vapor phase at the beginning of fuel supply.

61. Apparatus according to claim 58 including timing means controlling the valve means so as to supply fuel in a second fuel phase after supply of the first phase.

62. Catalytic combustion apparatus according to claim 18 including a fluid conduit in heat exchange relation with the catalyst mass.

63. Apparatus according to claim 62 wherein the fluid conduit comprises means for attachment to the discharge valve of a pressurized fluid medium container so that the fluid medium is heated on discharge through the conduit.

64. Apparatus according to claim 63 including a container of hydrogenous fuel in liquid and vapor phase and conduit means for supplying the fuel to the fuel inlet in both phases.

65. Apparatus according to claim 64 wherein the fuel comprises 5% to 25% of a lower alcohol selected from the group of methanol, ethanol and isopropanol, and 75% to 95% of a lower ether pressurizer selected from the group of dimethyl ether and methyl ethyl ether.

66. Apparatus according to claim 64 including first means for valving a predetermined quantity of fuel in the liquid phase and second means for valving a continuous flow of fuel in the vapor phase.

67. Apparatus according to claim 66 including means coordinating the valving means such that the first valving means is actuated at least as early as the second valving means.

68. Apparatus according to claim 67 wherein the container comprises the first and second valving means and the coordinating means.

69. Apparatus according to claim 66 including a manually operable member for actuating the first and second valving means.

70. Apparatus according to claim 69 including a second manually oper-able member for operating the fluid medium discharge valve.

71. Apparatus according to claim 70 including an air aspirator attached to the combustion chamber and a nozzle on the aspirator constituting the second manually operable member.

72. Apparatus according to claim 18 wherein the combustion chamber comprises a thermally conductive wall folding the combustion path so that the inlet and outlet are in heat exchange relation through said wall.

73. A catalytic combustion method comprising: 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 concen-tration 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.

74. The method according to claim 73 wherein the fuel in liquid phase is atomized into liquid droplets.

75. The method according to claim 73 wherein the fuel in said other phase is flowed through a further catalyst mass of substantially lower concentration.