CA1054920A - Fuel conversion apparatus and method - Google Patents

Abstract

FUEL CONVERSION APPARATUS AND METHOD

Abstract of the Disclosure Apparatus and method are described for the vapori-zation of liquid fuel oils to produce a gaseous mixture suitable for burning in a burner normally designed for operation utilizing natural gas. In the novel procedure, a carrier gas, e.g. steam, is mixed with a normally liquid fuel oil and this mixture is heated to vaporize a major amount of the fuel oil to form a gaseous mixture of oil vapors in the carrier gas. Any unvaporized oil is se-parated from the gaseous mixture and the gaseous mixture is then recovered at the operating temperature and pressure for a normally gas fired burner. The invention permits the utilization of Fuel Oil No. 2 through Fuel Oil No. 6 as an alternate source of fuel in normally gas fired equipment.

Description

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ackground of the Invention This invention relates to the utilization of liquid fuel oils, particularly Fuel Oil ~o~ 2 through Fuel Oil No~ 6l as an alternate source of fuel in normall~ gas ired equipmen.., such as boilers, g~s turbines 7 various industrial furnaces and particularly for hydrocarbon stea~ :
reformers. With increasing demands placed upon natural gas reserYes by use of natural gas in ~he production of petro-chemicals and petrochemical products, a scarcity OL natural gas has been created ~uch that it is necessar~ to find sources of alternate fuels for gas fired e~uipment. Of course, it is possible to remove burners designed for n~tural gas service and replace them with burners designed ~or burning fuel oil but such .is not always economic or advantage4us to the operation of e~uipment where natural gas ma~ be intermittently available or use as a fuel.. This is particularly true ~ith respect t~ hydrocarbon steam reform-in~- ~urnaces, as described, for example, in ~OS. Patent ~os. 3,257,172; 3,672,847 and 3,.768,980, where many such Z0 burners are in operation and a conversion to fuel oil ser-vice would require days:of do~m time with great loss of proauctivit~.
While it has previously been disclosed, in U~S~
Patent 3,393,964 for example, to atomize liquid hydrocarbons in the burner itself with a normally gaseous ~uel, such operation would require the replacement of all existing natural gas burners with a specialized burner and,. there-fore, is impractical. U.S. Patent 3t~91,191 descrlbes the . broad concept of vaporlzing a nor~ally liquid fuel to ma~e it interchangeable with natural gas in the operation o~ a .

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, natural gas burner. It has pre~iously been known to vapor-ize liquid fuel by heating. Such heating, however, xesults in heavy residue and consequent formation of coke requiring frequent shut dc~ns ror cleaning, and thus is qenerally unacceptable.
; Other metnods have bee'n described wherein a portion of the fuel oil is burned with the-gaseous products ' used to ~aporize acditional fuel oil for burning in a gas fired burner, as described in U.S. Patent 1,987,401. U.S.
I0 Patent 3,480,416 describes a'~ethod of preparing a gaseous ¦ ~uel by cracking a portion or a liquid fuel and conjointly he~ting water to form a gas stream for further use either as a feed fsr flame cracking or for fuel. Again, ther~ are many consequent disadvantages to such a method. Also, previously, naphthas and light petroleum distillates have be~n vaporized to replace natural gas as fuel but the prior art doe~ not describe such a system ~or use of suc~ heavier fuel oils.
Accordir.gly, it is the objeGt of this i~vention to ".!, 2~ pro~ide a system r~hereb~ heavier fuel oil, such as No. 2 through No. 6 grade and equivale~t, can be vaporized to form a gaseous proauct suitable for use interchangeably, and intermittently, with natural gas in a burner des~gned for ; nztural gas combus~ion. It is also an object OL thi~
invention to provide apparatus and a method whereby heavier fuel oils, such as Fuel Oil No. 2 through Fuel Oil No. 6/
can be vaporized and used as a substitute for na-tural gas in normally gas fired burners.
; It is stlll a fur'ther object of this invention to provide such a me.hod whereby heavy fuel oils can be used as

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an alternate fuel for gas ~ithout significant coking in the furnace or equipment utilized for vaporizing the oil.
. Summary of the Invention , The invention describ~d and claimed herein is for a syste~ for vaporizing- liquid fuel oils for use, either permanently or intermittently, i-. burners designed normally for operation with n~turàl gas as the fuel. Fuel oil,-preferably preheated, is mixed with a carrier gas, as here-I inafter defined, and the ~i.-.;.ure ~aporized in a suitable .~ 10 ~eater to vaporize at.least a major amount o~ the fuel oil.

'This foxms a gaseous mixture containing, in most instances, when oils heavier than No. 3 are used, some unvaporized oilO
The gaseous mixture is then separated from the unvaporized oi~ at conditions such that it can be burned in a hurner designed for nar~al operation with natural gas as the fuel.
Descri~tion of the Drawin~s ~ ig. 1 is a schematic flowsheet showin the system of this i~vention in its broa~est application with common ~ittings, valves, flow meters and controls omitted Fig. 2 is a schematic Plowsheet, showing a pxe-ferred embodim~n' of this invention, particularly adapted to the practice of the i~vention using a skid mounted unit, with the same co~on parts omitted~

~ ig. 3.is a schemati~ flowsheet showing the especially preLerred embodiment of this inventio~, omitti.ng common fittings, valves, flow meters and controls.
Detailed Description The practice of this invention is particularly adapted to the use of heavier fuel oils, such as Fuel Oil No. 2 throu~h Fuel Oil No. 6 and other oils having similar ~ -3-~5~

characteristics, as an alternate fuel for burners normall~
designed for operation using natural ~as. Since many hydro-carbon processing plants require large quantities of natural gas for use as fuel and such gas is becoming in short supply it has ~een n~cessary to provide for the operation of many processing units with more available liquid fuels. The composition of fuel oils` falling into these grades is wel'-~nown and these oils are often used to fire furnaces de-signed for such use but have hereto~ore not been used as fuel for hydrocarbon process.ng units designed for natural ¦ gas operation without significant changes in equipment. Itis well-known that .he heavi~. grades of ft~el oil contain I mo~e undesirable co~.pounds, such as sulphur ~nd ash, and - l req~ire more heat to vaporize. However, the system hereindescribed is eminently suitable to provide such duty.
In view of emmissioll limitations placed upon pro-cessing plants, many tail gas s.reams are burned in con-- junction with natural gas, both to take advantage of fuel values and to render such gases innocuous. It is to be -~ understood that when the term '~burner designed for natural gas", or equivalent, is used, it includes a burner which uses na~ural gas and such combustible tail gases on a fuel ; since such tail gases must still be burned when the sys.em of this invention is in operation.
The broadest concept of this invention is shown on Fig~ 1 wherein fuel oil, preferably preheated, enters the system through line 10 and is contacted by a carrier gas, ~ preferably superheated steam, entering through line 12 where i they are mixed in a mixing means 14 which can suitably be a ;, 30 "Tee" in the lines 10, 12. The steam can be supplied from a : ~ .
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plant u~ilities stream, fr~m a package boiler or generated-by equipment mounted with the unit itself. It is preferred that the steam be superheated so that a sufficient amount of latent heat would be available to prevent condensation of the steam when it comes in contact with the lower temper~-ture fuel oil and thereby heat the fuel oil to some extent.
This possible condensation can be partially alleviated by preheating the fuel oil through a suitable heai exchan~Jer or the like.
iO In the practice of this invention, w~ile the carrier gas is preferably steam/ it is- to be understood that com-¦ bustible tail gases, rich in hydrogen, such as for exampie, ¦ the purge gas from an ammonia plant which ~enerally inclu~des j hydrogen, ammonia, nitrogen and argon, can either be usea .
alone, if a su ficient qu~ntity is available-, or in admix~

i ~ure with steam. Since these tail gases will generally be .
at an elevated temperature, the lateI~t hea~ is valu-ble i ~ ai~ing in the vaporization of the fuel oil. Tail gases :-~
suitable for use will preferably have a molecular weight ~ closely approYimating that or steam so that the partial 4 pressure of the vaporized oil is reduced.
The mixture of carrier gas an~ fuel oil exits the mixing means through line 16 where it enters a vaporizer 18.
The vaporizer 18 is a suitably designed heater wherein the materials to be heated entering through line 16 will course through tubes~ shown schematically, in a radiant and/or ii convection ~one of such vaporiæer 18 wherein a major amount, preferàbly at least about 75 wt.~l of the fuel oil feed is vapori7ed to form a gaseous mixture of steam and vaporized -~ fuel oil in admixture with any unvaporized fuel oil. Equip~

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ment suitable for use as vaporizer 18 can be deslgned by ~he skilled engineer once the disclosure of this system of this in~ention is known.
While many forms of heating can be used, Yaporizer 18 is suit~hly-~iE~d ~lith fuel and air entering through lines 20 and 22, respectively. The fuel used for the Yapar-~ izer may well be some of the very same fuel oil which is ~eing vaporized using the system of t:is invention. Pro~
the vaporizer 18 ~he gaseous mixture and any unvaporized . lO- ~uel oil exits through line 24 and is conducted.to separator ; 26 which may be any suitable gas/liquid separation.. device, , .s.u.h as a flash tank or dr~m wherein the gaseous mixture i5 separatea and exlts the separator 26 through line 28. The ;ll unvaporized oil exits the separator 26 through line 30 and may be recovered and used as :fuel for the vaporizer ~8, :or example.
The gas~ous mixture is heated in the vaporizer }8 ., to such temperatu_e and pressure conditions that the gaseous ~ ¦!
~ mixture exiting the separator 26 through line 28 will have j l '. 20 temperature and pressure conditions suitable for the parti-l ..
~ culax burner desisn. These temperatures will generally be .l within the ranse of from about 550F. to about l,000F.
.l Usually, for a hydrocarbon steam reformer, these condi~ions ..
.l involve temperatures from about 600F. to about 800F. and a pressure of from about 20 to about 65 psig, and preferabl~
¦ 25 to 45 psig. Normall~, the burnex 32 is fired with natu-ral gas, sometimes including a combustible tail gas,entering through line 34 supplied through line 36. The gaseous mixture is introduced into line 36 and enters the burner i 30 through line 34. This mode of operation is preferable in ,' .
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order to allow the quantity of natural gas being burned in the burner 32 to be gradually reduced while the amount of gaseous mixture being burned is gradually increased until vaporized fuel oil provides the sole fuel for the burner 32.
As an alternative, preferably for start up of the unit employing the system of this invention, fuel fox the burner 32 can be intrsduced through line 3~ into linP 10 ~o aid in bringing the unit or streams ~y acting as a supple-ment to the carrier gas to provide sufficient velocity through the unit to prevent operational problems. As a steady operational state is being achieved, the gaseous burner fuel is reduced and vaporized oil replaces it.
SpeaXing in general terms, natural gas has a heating value of approximat:ely 1000 BTUIs per s~andard cubic foot while a vaporized fuel oil normally has a hea~i~g value of fro~ about 2000 to about: 5000 BTU/SCF. Thus, it is important to dilute the vaporize~ fuel oil. In the practice o~ this invention, the carrier gast pre,erably steam, and most preferably superheated steam, is employed, not only as ~he diluent but to take advantage of the other benef.its the carrier gas pxovides. One such advantage is that -the car-rier gas, particularly steam, hel~s to prevent coking, both ln the. vaporizer 18 and in the burner 32. Steam also pro-motes a cleaner combustion gas when the vaporized fuel oil produced from operation of this invention is burned. Of particular advantaye is that the carrier gas reduces the.
partial pressure-of the fuel oil, aiding in the ~aporization of the latter. To achieve such adva~tages, the carrier g~5 is mixed with the fuel oil in the mixing means 14 in the proportions of about 0.1 to about 1~0 pounds o~ steam per ~ . '' ~15~

pound of fuel oil. The upper limits of this ratio will normally be used for the vaporization of the heavier fuel oils with a range of from about 0.1 to about 0.7 normaI~y being used.. The optimum ratio can be determined by the degree of v.apori.zation desired and the normal operating ; conditi.ons of the ~urner. ~or No. 2 grade fuel oil,.. for example, the pre erred ratio is from about 0.3 to about 0~
. pounds per pound of fuel oil. Of course, this ratio would . be ad~usted within the above limi-ts to provide for a proper bal~nce dependi~g upon the grade of fuel oil being used.
Turning to Fig. 2, a schematic diagram of a pr~erred embodiment of this invention is shown, without detailing the co~mon valves, ~ittings, controls and flow gauges known to .hose of ord:inary skill in the art.,. w~ rein . it is possible to both superheat.the steam and the resulting gaseous mixture rrom the vaporization and to maintain some degree of portability of the equipment. ~hilé *he process described in ~i.g. 2 is primarily designed for erection on a . porta~le platform, such as a skid, it is well a~aptable to be used as a permanent fixtureO
. . ln this embodiment of the invention, the fuel oil , enters through line 110. For purposes o~ ~his discussion, the carrier gas will be considered to be steam which enters through line 112 and is mixed in a mixing means 114 which ! can be some suitable vessel or an ordinary pipeline "Tee"~
The mixed fuel oil and steam exit the mixing means 114 through line 116.
. The stear entering through line 112 has passed through a superheater 118 which superheater is suitably fired with fuel and air entering through lines 120 and 122, ~os~
: respectively. Such superheater 118 is designed to give the duty necessary to produce the temperature to pressure condi~
. tions desired for contacting and mixing the stea~ ~rlith the . fuel oil entering the mixing means 114 through line 110.
The steam.enter.s the superheater 118 through.line 124 froM
any suitable plant source or package boiler also o~ standard design.
If mounted on a skid or mo~able platform, lines ' 110 and 124 would be fitted with suitable connecting mean~
1 o to attach t~.e vaporizer of this inven~ion to a source of - steam ana fuel oil. To compensate for differ~nces in steam . qualit~ due to dif~erent locations, a bypass, not s~o~Jn, with appropriate valves can be used to connect iines 124 and 112..
T~e mi~ed st~am and fuel oil beiny carried by line 116 is passed through a vaporizer 126 which is of a stand~xd , design as aforementioned in discl.lssion with the embodiLent.
of Fig. 1. Thoug~ other means o~ heating may be used, the 1 vaporizer 126 is suitably fired by fuel which enters through .' 2:0 line 128 and burns in the presence of air entering through.
~:: line 130 creating radiant and/or convection zo~es in.such ~aporizer 126. The gases will suitably pass khrough tubes 132 in the vaporizer 126, such tubes 132 shown schematically on Fig. 2.
¦ In the vaporiæer 126 a major proportion of the l fuel oil is vapori~ed, preferably at least about 75 wt.~, I and, mosk preferably, from about 80 to about 98 wt.~. ~hen No. 2 oil is used, su~stantially all of the liquid fuel oil can be vaporized. This vaporization in the tubes 132 of the

3~ vaporizer 126 results in the production of a yaseous mixture _9_ f.

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of steam and va~orized fuel oil. This gaseous mixture exits the vapoxizer 126 thxough line 134 and enters separ~tox 136 wherein the gaseous mixture is separated fro~ any unvapor~
ized liquid fuel oil, which exits through line 138 and can be suitably used for as fuel or the superheatel- 118 or the vaporizer 126. Other~ise, during use as a portable unit, line 138 may be provided with a suitable connecting means such that the residual liquid oil may be collected or dis-posed of in a proper manner.

The gaseous mixture, now substantially free of unvaporized fuel oil, exits the separat4r 136 through line 140 and thence through lin~ 2 to the superheater 118 passiny throush tubes 1~4, schematically represented. The gaseous mixture is raised to temperature and pressure con-ditions as hereinbefore stated suitable for fuel for a burner designed to normally operate on natural gas. The gaseous mixture exits at these conditions through line 146 which i~ joined by bypass line 148 connecting the effluent .:
of the separator 136 through line 140 providing a bypass for the superheater 118 or the gaseous mixture should such ¦ operation be desired.
- j The combustible gaseous mixture to be ch~rged to the burner passes through line 150 where it is preferably connected to line 152, the natural gas feed line for t~e burner 154~ The operation of the burner and the mix of gas - feed and natural sas feed is as has been described for the broad embodiment of this invention and line 153 for intro-duclng burner fuel into line 110 is provided for puxpsses previously aiscussed.
3' In the design of the portable unit line 150 would ( i.

- -be provided with a ~itting located in line 152 to provide for the change-over of the burner 154 to the ~aporized fuel oil prepared through the practice of this invention. Of course, burner 154 may represent a single burner or a plural-ity of burners.
With respect to ~n e~ample of ~ specific operation of the embodiment shown in Fig. 2, from which ~ scale-up can be made, and discussed above/ Fuel Oil No. 2~ previously heated in an exchang~r, not shown, flowing at from 0.1 to ' 10 about 0.5 gallons per minute, is mixed with steam at SC~F.
supplied at the rate of 20 to about 150 pounds per hour.
This mixture enters the vaporizer 126 at 300~F. and ~0 psig pressure and exits as a gaseous mixture through line 134 at 1l ahout 30 psig pressure and 600F. The gaseous effluent from ! the sepaxator 136, any liquid material having been rem~ved, i is at 30 pounds and 600F. alsc. In the superheater 118 the gaseous mixture is heated to 750F. and 20 psig and was s~ccessfully used to operate a burner designed for u~e in natural gas service.
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In the practice of this preferred embodiment of the invention, of course, the apparatus would also be provided with control means to vaporize the different fuel oils to the needed conaitions.
The embodiment shown in Fig. 3 is especially ¦ preferred providing an operating system havin~ outstanding flexibility and reliability. This ~mbodiment is substanti-! ally the same as previously described with respect to Fig. 2 with the exception that separate vessels are preferably used for superheating the steam and gaseous mixture rather than one vessel as set forth above. The reasons for this will ~35~92~
become app~rent from the following discussion. For purposes of simplifica~ion, the discussion of Fig. 3 will assu~e that a No. 2 fuel oil is used~ it being understood that it is within the scope of this invention to use fuel oils heavier than No. 2, i . e., Fuel Oil No. 2 through Fuel Oil No. 6. It will be further understood, knowing the described process, that with respect to Fuel Oil No. 2, the skilled process `~ engineer can make such adjustments in temperatures, pres-sures and flow rates tha-t the system becomes easily adapt-; 10 able to operating on heavier, more difficulty vaporized Luel oils. Steam ~ill again be the carrier gas of choice for pur-¦ poses o~ this discussion, it being understood that steam ora tail gas, as previously descxibed, or mixtures thereo~ are within the scope o this discussion.
Fuel Oil No. 2 enters the apparatus throu~h line 210 and is preferably heated in exchanger 220 ~hich can be ` used to consume energy available at the operating plant I location. While this heat exchanger 220 is optional, it is preferred so that it eases the mixing of the steam with the fuel oil in later operation of the method of this invention.
When the heat exchanger 220 is used, ~he No. 2 fuel oil will exi* the exchanger at approximately 3C0F. through line Z22, thence through valve 224 and à mixing means 226 which may, as has been described previously, be a mixing vessel or nothing more than an ordinary pipeline "Tee". Steam enters `¦ the system, preferably at 440F. and 185 psig, through line228 into a steam superheater 230 which is operated by burn-ing a fuel in air which enters the superheater 230 through lines 232 and 234, respectively. O course, the fuel entering t~rough line 232 to be burned may also be Fuel Oil ( ~ C3`5~
No. 2, such as is bei~g vaporized in the practice of this invention. While ~he conditions of the carrier gas are ~lexible, depending upon availability and condition at a particular plant site, in the dlscussion stea~ exiting the superheater 230 through line 236 will be at a~out 800F. and about 180 psig pressure. ..
As is seen on ~ig. 3, line 236 branches into lines 238 and 240. The steam travels through branch 238 and I proceeds throush valve 242, which i5 open in nor~al opera--~ lO - tion o~ the system of this invention, and continues into the mixing means 226 to be mixed with the fuel oil. The mi. -ure - of steam and liquid fuel oil, in this example, 0.5 pound-:
steam per pound.o: oil, then passes through line 244 to the ~ i vaporizer 246 ~hich, as discussed above, burns a fuel in the :`! presence of air en.ering through lines 243 and 250, re-~l spe~tively. In the preferred embodiment of this ir .~ntion, ` the vaporizer 246 is designed to have suffi~ient heating .
capacity to not only fully vaporize the fuel oil into a gaseous mixture but also provide some superheat to attain the conditions set ror the burner in which the gaseous . mixture is to be used. The purpose of this will become .
apparent from subsequent discussions herein.
Substantially all o~ the No. 2 fuel oil charged under these condl.ions is va~orized to a gaseous mixture containing the va~ors of the fuel oil and steam. Of course, when the heaviex ~lael oils are used in the system o~ this invention, there will likely be somewhat more unvaporized material but conditions of the carrier gas, proportions thereo~ and heat in the vaporizer can be adjusted to opti-.3~ ~ize the conditions. The gaseous mixture leaves the vapor - ( ~

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izer 246 through line 252 at conditions of fro~ about 500F.
to ~bout 900~. and from about 75 to a~out 130 ps:ig preG-sure. For fuel oil No. 2 the preferred conditions are abou~
640F. and 77 psig pressure. The gaseous mixture'and any unvaporized fuel oil passes through valve 254, open during normal operation, through line 256, 258 and thence to sepa-rator 2~0 which can be àny appropriate liquid/gas`separation device, such as a drum separator. As stated, subs~antially all liquid is vaporized when N~. 2 o:l, or equivalent, is l~ used but with the heavier oils some'liquid will generally ~' exit the vaporizer~
, The unvaporized fuel oil exits the separator 260 `' throug~'line 262 where it can be recovered and used to provide fuel for other use at the plant site, including possibly to fire the vaporizer 246 or superheater 230~ The ~ ~ .
' gaseous stream exits the separator 260 through li~e 264 whieh branches into lines 266 and 268. Line 266 leads into valve 270, closed during normal operation, and line 272 which acts as a conduit for the vaporized oil to the gas ired burner.

Mean-~hile, branch 268 proceeds through valve 274, open in normal operation, through line 276 to the vaporized oil superheater 278. The vaporized oil superheater 278 is , fired by fuel burned in air entering through lines 280 and 282, respectively. The gaseous mixture, now free of un-vaporized fuel oil, is heated in the gas superheater 278 to the conditions at which it will be introduced into the natural gas burner; i.e., about 750F. at about 45 psig, and exits the gas superheater 278 through line 284 which bran-ches into line 286 and 288. Line 288 leads to valve 290, ~5~

closed in normal operat-~on, which communicates with line 258, as previously described. The heated gaseous ~ixture is conducted through line 284 to line 286, proceeds through valve 292, open in normal operation, and line 294 which conducts the gas~oùs mixture to line 272 where it is further transmitted to the natural gas burner indicated on FlgO 3 as 296. As mentioned beforè, the burner 296 represents either a single burner or a plurality thereof and is not, of it-self, an element of this invention.
It is preferable in the desisn and operation o~
the apparatus of this invention using the method of this invention that the oil superheater have the same heat duty a~ the vaporizer previously described so that either of these two vessels may be used to independently vaporize the -fuel oil in the presence of steam to create conditions wherein the gaseous mixture can be used in a buxner normally designed to burn natural gas. T~is allows the vaporizer to be shut down for decoking or maintenance without disturbing the operation of the e~uipment utilizing the vaporized gaseous mixtures. For equipment, such as hydrocarbon re-formers, this is very important since much economy is lost .
when it must be shut down~ Accordingly, Fiy~ 3 shows a bypass operation- of the system wherein the vaporizer 246 can be taken-out o ser~ice and the gas superheater 278 be used in its place to act as bo*h the vaporizer and ~he super-.
heater supplying all the heat necessary to prepare the gaseous mixture for burning. Of course, this is not a preferable way of operating over an extended period of time, but it aoes allow for maintenance or decoking without forc-ing the equipment burning the gaseous mixture to shut down.

' It is also possible, through the alternate piping shown in Fig. 3, to carry the entire heat load through the oil Yapor-izer and shut down the superheater for decoking, or repair, i~ necessary~
In order to bypass the vaporizer 246 ~ranch 240 of line 236 would carry the superheated steam through valve 298, closed in normal operation previously described, to communicate wi~h line 276. It is at that point that the superheated steam and fuel oil would be mixed in an appro- -priate mixing m~a~s.
The heated fuel oil would bypass the vaporizer 246 1 by clo$ing valve 224 and divexting the flow in line 222 ;l through line 300, valve 302, closed in normal operation, i line 304 to the ~ixing means :in line 276 wherein the oil would be mixed with the steam entering through line 298.
'` During normal operat:ion of the abo~e-described process to provide vaporized NQ. 2 fuel oil to a steam re-former ~equiring approximateiy 600 million btu's per hour, approximately 0~5 pounds of steam are used per pound of No.
2 fuel oil. As was described in previous modifications of the above-describPd invention, natural gas would be used to fire the burner 296 entering through line 306 and, alter-natively, for purposes previously dis~ussed, into line 21~
through line 308 The gaseous mixture entering through 272 ; would gradually replace the natural gas as fuel for the burner 296 until all the fuel to the burner is vaporizea fuel oil prepared in the pxactice of this invention.
As has been previously stated, the process of this invention operates equally well with the oil vaporizer 246 shut down or with the oil superheater 278 shut do~n. Table I

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illustrates the position of the valves shown in Fi~ 3 and described above in these two alternative systems of operation as compared with normal operation, described in detail above.
TABLE I

_ . . . , Valve 224 242 254 270 274 290 292 298 302 . . ~
Normal o o o c o c o c c Vaporizer c c c o c o c o o Down Superheater o o o o c c c c c Down . .

o = open c = closed As can now be readily seen, the most preferred embodiment as described above and shown in Fig. 3 offers great flexibility of design and operation with respect to the vaporization of not only Fue:l Oil No. 2 but Fuel Oil No. 2 through Fuel Oil No. 6, and substantially equi-valent hydrocarbon mixtures, for use in not only hydrocarbon 2û steam reformers utilizing natural gas burners, as pre- ;
viously discussed, but in substantially any equipment where-in such burners are used.
Throughout this Specification discussion has been made of Fuel Oil No. 2 through Fuel Oil No. 6. The boiling ranges and composition of these fuel oils have long been well known to those of ordinary skill in the art and are specifically described in the Annual Book of ASTM Standards, 1975 Edition, pages 217 through 222, as designated standard D-396-75, "Standard Specification for Fuel Oils". The specification of these fuel oils are also set forth as American National Standard Z-11.203.

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The skilled engineer with the information given above would have no difficulty in making the calculation and modifications necessary to adapt the afore-described invention to the many other uses to which it may pertain.
Accordingly, such modifications and changes may be made without departing from the scope of the above-described invention and the following claims.

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Claims (17)

CLAIMS:

1. Apparatus for vaporizing a normally liquid fuel oil such as Fuel Oil No. 2 through Fuel Oil No. 6 for use in a normally gas fired burner, which comprises:
(a) means for mixing a carrier gas with a normally liquid fuel oil;
(b) means for vaporizing at least a major amount of the fuel oil in the mixture to produce a gaseous mixture;
(c) means for separating unvaporized fuel oil from the gaseous mixture; and (d) means for superheating the gaseous mix-ture whereby such gaseous mixture is suitable for use in a normally gas fired burner without interrupting burner operation.

2. The apparatus of Claim 1 which includes a steam superheater.

3. The apparatus of Claim 1 wherein the means for vaporizing and the means for superheating the gaseous mixture have sufficient heating capacity to both vaporize and superheat the mixture so that, upon separation of un-vaporized fuel, the resultant gaseous mixture will be at conditions suitable for use in the burner.

4. The apparatus of Claim 3 wherein it includes means for operating either the vaporizing means or the means for superheating the gaseous mixture while bypassing the other means.

5. The apparatus for vaporizing a No. 2 fuel oil for use as a fuel in a burner normally designed for opera-tion with natural gas which comprises:
(a) a steam superheater;
(b) a means for mixing superheated steam with a stream of fuel oil;
(c) a means communicating such mixing means with a source of superheated steam and Fuel Oil No. 2;
(d) a heater for vaporizing the mixture to produce a gaseous mixture of steam and vaporized fuel oil;
(e) a line connecting the mixing means and the heater;
(f) a means for separating unvaporized oil from the gaseous mixture;
(g) a means connecting the heater with the separating means;
(h) a means for heating the gaseous mixture recovered from the separator to a temperature and pressure suitable for use as an alternate fuel in a burner designed for burning natural gas;
(i) a line cor.necting the separation to the superheating means; and (j) a connector means for conAucting the gaseous mixture to the burner.

6. The apparatus of Claim 5 mounted on a skid for portability.

7. Method for vaporizing a fuel oil of Grade No.
2 or heavier for use in a normally gas fired burner com-prising the steps of:
(a) mixing a carrier gas with a normally liquid fuel oil in the proportions of about 0.1 to about 1.0 pounds of carrier gas per pound of fuel oil depending upon the fuel oils to be vaporized;
(b) heating the mixture to vaporize at least a major amount of the fuel oil to form a gaseous mixture of oil vapors in the carrier gas;
(c) separating any unvaporized oil from the gaseous mixture; and (d) recovering the gaseous mixture at opera-ting temperature and pressure for the normally gas fired burner.

8. The method of Claim 7 wherein the carrier gas is steam.

9. The method of Claim 8 wherein the steam is superheated steam.

10. The method of Claim 7 wherein at least about 75 wt.% of the fuel oil is vaporized in the heating step.

11. The method of Claim 10 wherein from about 80 wt.% to about 98 wt.% of the fuel oil is vaporized in the heating step.

12. The method of Claim 7 wherein the gaseous mixture is heated to operating temperature and pressure of the burner after separating the unvaporized oil.

13. The method of Claim 7 wherein the carrier gas is a mixture of superheated steam and a tail gas rich in hydrogen.

14. A method for vaporizing fuel oils such as Fuel Oil No. 2 through fuel Oil No. 6 for use in a burner normally used for natural gas, which comprises the steps of:
(a) superheating steam to a temperature of from about 600°F. to about 900°F. at a pressure of from about 150 to about 200 psig;
(b) mixing the superheated steam with a fuel oil of grade No. 2 through No. 6 in proportions of from about 0.1 to about 1.0 pounds of steam per pound of fuel oil;
(c) heating the mixture to vaporize at least about 75 wt.% of the fuel oil to produce a gaseous mixture at a temperature of from about 500°F. to about 900°F. and a pressure of from about 75 to about 130 psig;
(d) separating unvaporized fuel oil from the gaseous mixture; and (e) heating the gaseous mixture, being sub-stantially free of liquid fuel oil, to a temperature of from about 600°F. to about 800°F. at a pressure of from about 25 to about 45 psig whereby the gaseous mixture can be burned in a burner normally designed for burning natural gas.

15. The method of Claim 14 wherein the fuel oil is Fuel Oil No. 2.

16. The method of Claim 15 wherein from about 0.3 to about 0.5 pounds of superheated steam is mixed per pound of fuel oil.

17. The method of Claim 14 wherein from about 80 wt.% to about 98 wt.% of the fuel oil is vaporized in the heating step.