CA2667261A1 - Process and reactor for upgrading heavy hydrocarbon oils - Google Patents

Abstract

A process using supercritical water to upgrade a heavy hydrocarbon feedstock into an upgraded hydrocarbon product or syncrude with highly desirable properties (low sulfur content, low metals content, lower density (higher API) lower viscosity, lower residuum content, etc.) is described. The process does not require external supply of hydrogen nor does it use externally supplied catalysts. A reactor design to carry out the process is also described.

Description

PROCESS AND REACTOR FOR UPGRADING HEAVY HYDROCARBON
OILS

FIELD OF THE INVENTION

The present invention relates to upgrading of hydrocarbons, especially heavy hydrocarbons such as whole heavy oil, bitumen, and the like using supercritical water.

BACKGROUND OF THE INVENTION
Oil produced from a significant number of oil reserves around the world is simply too heavy to flow under ambierit conditions. This makes it challenging to bring remote, heavy oil resources closer to the markets. One typrcal example is the Namaca field in Veriezueld, In order to render sucfi heavy oils flowab!e; one of the most commasi methods known in the art is to fedr,rce the viscosity and density by mixing the heavy oil with a sEifficient diluent. T1le diluent may be naphtha, or ariy other stream with a significantly higher API
gravity (i.e., much lower density) than the heavy oil.

For a case such as Hamaca, diluted crude oil is sent from the production wellhead via pipeline to an upgrading facility. T4vo key operatiaris occur at the upgrading facility: (1) the diluent stream is recovered and recycled back to the presductinn weliliead in a separate pipeline, and (2) the heavy oil is upgraded with suitable technology knnwn in the art (coking, hydrocracking, hydrotreating, etc,) to produce higher-value psnciucts for martcet. Some typical characteristics of these higher-valu>~ products inc.lude: lower sulfur content, lower r-netals content, lower total acid nucnher {TANI; lower residuum content, higher API gravity, and lower viscosity, Most of these desirable characteristics are achieved by reacti.ng the heavy oil with hydrogen gas at high temperatures arrd pressures in the presence of a catalyst, In the case of t-iamaca, the upgraded crude is sent further to the end==users via tankers.

t These diluent addition / removal processes and hydr'ogen-addition or other r,ipgrading processes have a number of disadvar3tages;
1, The infrastructure required for the handling, recovery, and recycle of c3iluent: coEild be expensive, espocially over long distances. Diluent availability is another potential issue.

2. Hydrogon-aadit#on processes such as hydrotreating or hydrocracking requira signi#ic;ant investments iÃi capital and infrastrtÃctorp..

3. Hydrogen-artdition processes also have high operating costs, since hydrogen produc;tion costs are highly sensitive to natural gas prices. Some remate heavy oil reserves may not even have access to sufficient quantities of low-cost natural gas to support a hydrogen plant. These hydrogen-actditaorÃ
processes also generally require expensive catalysts and resource intensive catalyst handling techniques, including catalyst regenoratibr-.

4, in soÃiie cases, the refineries and/c,r upgrading facilities that are located closest to the production site rnay have neither the capacity nor the facilities to accept the heavy oil.

5. Coking is often used at refineries or upgrading facilities. Significant amounts of by-proctuct solid coke are rejected during the coking process., leading to lower liquid hydrocarbon yielr.~, In addition, the liquid products from a coking plant rafteri need further hydrotreating. Further, the volume of the product froryi the coking process is significantly less ttian the volume of the feeci crude oil.

A process according to the present invention overcomes these disadvantages by using supercritical water to upgrade a heavy hydrocarbon feedstock into an upgraded hydrocarbon product or syncrude with hiqhly desirable properties (IOW sultur content, low metals content, lower density (higlier API), lower viscosity, lower residUrrÃM conterit, etc.). The process nei:ther requires exierna;
supply of hydrc:gen nor niust it tise catalysts. Further, the process in the t,resent invention does not prcriL,ce at-i appreciable coke tsy-pÃbduc.t.
In comparison with the traditional processes for sy crride prractuctinn, advantages that Ãyicay be obtamed by the pra4tice of the pre5ent invention include a 'iigh iiquic# hydrocarbon yieid; no r-reed for extc-rnally-5upp iied hycirogen; no need to provide catalyst; significant increases in API gravity in the upgraded hydrocarbon praduct, significar-it viscosity reduction in the upgraded hydrocarbon product; and significant reduction in sulfur, metals, nitrogen, TAN, and MCR (micro-carbon residuei in the upgraded hydrocarbon product.

1larirris methods of treating heavy hydrocarbons using supercwrt:iz.al water are disclosed in the patent literature_ Examples include U.S. Patent Nc.~s.
3,948,754, 3,948 fi5, 3,960,706, 3,983,027, 3,988,238, 3,98,-~~,61t3, 4,005,005, 4,151:068;
4,55-7,820, 4,559,127, 4,594,141, 4,840;725, 555,611,915, 5;914,(}31 and 6,887.369 and EP671454.

U.S. Patent No 4.840,725 discloses a process for conversion of high boiling Iiquid orgaÃiic materials to lower boiling materials using supercritical water in a tuhular, craritiriuous reactor. The wate= and tiydrocarbtaÃ) are separately preheated and mixed in a high-}aressure feed pump just before being fed to the reactor.

U.S, Patent No. 5,914,Ã331 discloses a three zone reactor design so that the reactant activity, reactant solubility and phase separation of products can be optimized separately by controlling temperature and pressiare. However, all the examples gÃveÃf ir, the pafent were otataiÃiec.f using taat:;tt opeÃ-ation.

U.S. Patent No, 6,887.369 discloses a super'critÃcal water pretreatment process using hydrogen or carbon monoxide preferably carried oÃit in a deep well reactor to hydrotreat and hydrocrack carbonaceous matersal. The deep well reactor is adapted frcrM underground oil wells, and consists of multiple, concentric tubes. The deop well reactor described in the patent is operated by intrvducing feed streams ir) the core tubes and returning reactor effluent in the outer annular section.

iL CA 02667261 2009-04-22 Although ttie above--rrierrtiarrecl patents disclosed and claimed var;or,is methods and processes for heavy aii upgrading using sL,percritical Water, such as operatirig range of temperature and pro-ssure, water to oil ratio, etc, none has disclased the design of the r'eactar or design related process controls for heavy o;l upgrading tasing, supercritical water. In fact, most of the c-xamp{es disclosed in the patents were obtained through batch tp-sts using an aLÃtociave. Although there are nurnerous referenep-s to reactor design for processes inv::)lvÃrrg supercrit'ical water, most of thern are for the appiiration of wastta tre'-atmer}t and none of those references has addressed tht-, design of a reactor for both heavy oil and sLipercrltiral water, wn-eh is tLartdamentally different from processes of waste treatment using supercritical wafer, as discussed below.

It has long beeri known in the art. that sUpercritical water can be used for waste treatriient, especially for treafiirrcd wastewater ccaÃitaiÃiing organic contarninants. 1-1-ierefOre, there are Ãiurfleraus disclosures in the literature or) reactor design for waste treatrT3ent using supercritical water, tended to address the following issues:
(1) Solid handling. Waste streams typically contain both organic and inorganic rtiaferials. Although organic materials can be destroyed quickly through 5Lrperc:riticaI water oxidation, inorganic materials are insoluble in supercritical water, Several patents address this cot7cerrr.
For example, U.S. Patent Nos. 5;560;823 and 5,567,698 incorporated by reference hereiri disclose a reversible flcw reactor having two reaction zones whir:,h are alterrrately i:ised ¾csr sÃ.Ãpercritit:.al water oxidation while the remaining r~actieti zone is flushed with, subcritical efflueÃit from the active reactiori zOrie. U.S. Patent IdO. 6,264;844, incorporated by refer-ence herein, discloses a tubular reactor for sUpert;ritiGal ~J~11~~~~oXidatiC3r1. Tf=1e velocity of the recactii:>ri ITl1xtur~.' is sufficient to prevent settling of S6id, Inorganic salts in th~.= effiLierit Ã7iixture: which are insoluble at corid'Ãtioris of superC.-Ãilical temperature and pressure for water, are dissolved in a liqE? ic3 water phase durii1g cooling dowvri of the effluent mixture at an outlet end of the reactor.

(2) Oxidizer management. tJ.S: Patent Nos. 5,384,031 and 5,558: 783, incerporated by reference herein, disclose a reactor design for supercritical wastewater exidation. It contains a reaction zone inside the containment vessel and apÃ.~rmeable liner arOLÃnd the reaction zone. An oxidizer is mixed with a carrier fluid such as water. The mixtfire is heated and pressurized to supert,ritical conditions, and then introduced to the reaction zc+r?e qradr^Ãallv and uniformly by forcing it rad:ally inward through the permeable liner and toward the reaction zone. The tsernieable liner permits the continuOUs, gra'dual, untforr7i dispersion of a reactant and therefore promotes an even and efficient reaction. The liiier also isolates the pressure vessel from high temperature and oxidizing conditions found in the reaction zone, allowing a redtiction in cost of the pressure vessei, EP 1489046 discloses a deuWe-uessel design with a reaction vessel placed inside a pressÃire vessel. Reaction takes plaw, inside the reactrr vessel at high temperature, pr-essLire and corrosive envircno-nerits. The euter pressure vessel will only see water.
(3) Containment of toxic material. Snrne waste streanR eontains contaminants that are extremely harmful to humans and the environment, therefore the possibility of releasing cf srJch harmful ttiaterial has to t3e addressed in the reactor design. U.S. f'atent No.
6,168;771, incorporated by reference- herein, discloses a reactor design inCludirig an autoclave inside a pressure vessel. Ttie ~.~ressi^Ire hetweeÃl ar.rtOel~ve. and pressure vessel is essentially equal to that iriside the autoclave, therefore el:rÃ7ir?ating possible leaking of toxic Ãnaterial inside the autcclave.

Aftheugh heavy oil upgrading using su~,>ereritieal water Ãiiay be eOnsictesed similar tn some respects to waste treatriient using supercritical water, and can be implemented using various elements of reactors designed for waste 3 5 treatrnent, there are significant differences in requirerment for reactor design for 1iekivy hydrcicarbr,ri upgrading frorni that for waste treatr-F-rent.
Spee.itiL,ally;
the following are among the many issues to be addressed in rJesigr>ing a Ci reactor in which to conduct an effective process for heavy oil upgrading usincw, superesrÃtica3 water:

(1) Importance of selectivity, For waste treatment, the or31y performance target is conversion. In other words, the reaction is rrari-selective total oxidation and there. :s no need to wcrTy abosrrt selectivity, which makes the reactor design r:nurh easier. For heavy oi( upgrading, the feed is a mixture containing broad range of riiatarials; and the reactions involved are niueh more complex. We need not only to cansider conversion, brrrt a?so more irnportant[y to purstre high i5 selectivity, since non-selective reactions will lead to low-value byproducts such as solid coke or gases. Obviously, reactor design for seiectfve reactions in acoxnple.c system is very different and much more challenging than that for non-selective total oxidation.
(2) High concentration of feer.~. Typically the organic c:oriiparierit concentration in the waste stream is low, artd in many situations the c:onceritrr^ation is only in the ppm range. For oil upgrading, it is preferable to run the reaction using the lowest possible water to oil ratio to reduc;Ln capital and operating cost. 'l~'he oil conc,entration is typicaliy several orciers of magnitude hRgher iri upgrading as opposed to waste treatment.
(3) Fiigh density and viscosity, One distinguishing feature of heavy oil is high density and viscosity. ir} fact, this is one of the primar}r reasons that the oil has to be rapgraded. The density of heavy oil is very close to liquid water, and viscosity can be as high as 10,000 cp. High density and viscosity, together with higf; concentration make the dispersion of heavy oil into supercritical water an important consideration.

SUMMARY OF THE INVENTION

'Tlse present invention relates to a process for upgrading hydrocarbons cornprisisig: riiixinc.~ hydrocarbons with a fluid comprising water tilat has beetR
heated to a temperature higher than its critical temperature in a mixing zone under conditions that disfavor therr-nal cracking and formation of coke to form a =riixture; passing the mixture to a reaction zone; reacting the ry'rixturp-in the rpat;tion zonp- having a srabstantially uniform temperature distribution and being configLÃred to reduce the settling of solids within the reaction zone said reaction occurring under supercritical water conditions in the absence of externally added hydrogen for a residetice time controlled within determined limits to allow upgrading reactions to occur; vvithdrawing a sir3gie-phase reaction product from the reaction zane; and separating the reaction product into gas; effluent water, and upgraded tiydrocarbon phases.

BRIEF DESCRIPTION OF THE I:?F~AWiNGS

Fig, 1 is a process flow diagram of one embodfr3':ent of the present invention Fig. 2 is apr-oc;ess flow diagram ot another pr7ik.}odiment of the present invention.

Fig. 3 is a process flow diagram of another erribadirr~ent of the present invention.
t= ig. 4 is aproeess flQw diagram of another embodiment of th~.~ present inventiOrt.

Fig. 5 is a process flow diagraryt Gf another eMb0dirfleni L}f the t.<r-esent.
inLrenttOn, ClESCfiIP'TlC)N Ot= 'T"HE PREFERRED EMBODIMENTS
Reactants Water and hydrocarbons, preferably heavy hydrocarbons are the two reactants employed in a process according to the present invention.
Any hydrocarbon can t3e slritahly upgraded by a prore.ss according to the present invr`:ntinn; Preferred are heavy hydrocarbons having an API gravity of less than 20". At1iang the preferred heavy hydrocarbons are heavy crude oil, heavy hydrecancons extracted frem tar sands, commonly called tar sand bitLirrsen, such as Athabasca tar sand bitLrMen nbta?ned from Canada, heavy petrolrvzrti) crude oils such as Venezuelan Orinoco heavy oil belt crudes Boscan heavy oil, heavy hydrocarbon fractions obtained from crude petrr;leurri oils particularly heavy vacLrum gas oils, vacuum residuum as well as petroleurn tar, tar sarids and coal tar. Other exarTip#es of heavy hydrocarbon feedstocks which can be ctsed are oil shaie, shale oii, and asphaltenes.
t4'ater Any source of water may be used in the tiLrid pompt-ising water in practicir-ig the present inventiorr. Sources of water include but are not limited to drinking water, treated or untreated wastewater, river water, lake water, seawater, produced water or the like.

x1r.i(irfg In accordance with the invention, the heavy },yd=ocarbon feed and a fluid comprising water ttiat has been heateit to a ter~ipera#ure higher than its critical temperature are, contacted in a mixing zone prior to entering the reaction zone. In accordance with the :nventÃcr, mixing ttlatyr he a.^.cctlipirshed in many ways and is preferably accomplished by a~echnique that does not employ rTreihanical movirig parts. Stict) 1?nearrs of rnixing rinay include, hfat are riot limited tc, use of static mixers, spray nezzles, sonic or ultrasonic agitation.
"t'he cil and Vv-at.er si-ictffd be heate,t andmixed so that the comt,itie'=d sfrea:11 will readi supercritical water vcnditions in the reaction zone.

The oil aÃid wateÃ- should be f-Ãeated and rYiixect so ttiat the combined strearri will reach supercritical conditions in the reaction zone.

It was found that by avoiding excessive heating of ttÃe feed oil, the formation of byproduct 5uch as solid residues is redricec3 significantly. One aspect of this invention is to employ a heating sequence so ttiat the tegliperatLjre and pressure of the hydrocarbons and water will reach supercritical reaction conditions in a controlled manner. This will avoid excessive local heating of oil, which will lead to solid formation and lower ttÃjality product. In order to achieve better perfermance, the oil should only be heated iÃp with sÃrÃffÃeient am0Ãint of water present and araÃ.Ãrrct the hydrocarbon molecules. This requirement can be met by mixing aill. with water trefora heatirÃg.

1n one embodiment of the. present invention, water is heated to a temperature higher than its t;ritÃcal temperatLÃre, and then mixed with oil. The temperature of heavy oil feed sh0uÃd be kept in the range of ai;oLrt 104'C to 200"C to avoid thermal crackÃEig but still higii eriaugh to ma(ntairi a reasonable pressure drop.
The water strearn temperature should be high enough to make sure that after mixing with oil, the tcrnpGrat:are of the oi!-water iiiixtrrr-e is still higher than the water supercritical temperattÃre, In this embodiment, the oil is actually heated up by water. An abÃindance of water molecules surrounding the nydrocart;on molecules will significantly st,tapress conderisation reactions aÃld therefore reduce formation of coke and solid product.

The- required temperature of the sripercriticai water strearr=, T,c.,,v, Can be estimated based on reaction teri:ÃpPratlÃre, TR, and water to oil ratio. Since the haat capacity of water changes significantly in the range riear its T.:ritical conditions, for a given reaction t.emperatÃire, the required temperature for the supercritical water strearyi iricreases almost exponentially with decreasing w:ater-to-oil ratio. The lower the water-to-oil ratio, the higher the T; c~v,:
`T-he relat.ionship, howeve:~, is very riorilirlear 5iriurv higher T,~cw leads to a lower heat capauitR+ (far away from the critical po:nt).

U Ir) another etTibndimwnt, water is riealed up to srrrpercr"Ãtical c;oriditÃorls. TherI
the supercrit;c:ai water mixed with heavy o=1 feed in a mixer. `T'he temperature of heavy oil teed should be ~ept in the range of about 100 0 to 200,,C to avoid thermal cracking but st>II high enough to maintain reasonable pressure drr3p.
After mixir3g with heavy oil, the temperature of the water-cail mixtcire worild be lower ttian critical temperatLÃre of water: therefore a second heater is needed to raise the temperature of the mixture stream to abave the critical temperature of water. In this embodiment, the heavy nil is first partially heated up by water, and then the water-oÃI mÃxttjre is heated to sr3percrrtic,al conditions by the second heater.
Other methods of mixing and heating sequences based on the above teachings may be Lrsed to accomplish these objectives as will be recognized by those skilled in the art.

.r i eaÃ: t1of? c vr-idltrvri s After the reactants have been mixed, they are passed into a reaction zatae in whit;h they are allowed to react under temperature and pressure conditions of supercritÃcai water, i.e, supercritical water conditions, in the absence of externally added hydrogen, for a residerice time sufficietit to allow r.rpgrading reactions to occur. The reactirari is preferably allowed to occur in the absence of externally added catalysts or prometers, although tiie use of such catalysts ar-id promoters is permissible in accordance with the present invention.
"Hydre:gerr" as used herein in the phrase, "in the absence of externally added hydrogen" riieans hydregeti gas. This phrase is not iritended to exelude all sources of hydrogen that are available as reactants. Other nicrlecules such as saturated hydrecarboris may act as a hydrngeti saLrrce during the reactiot) by ciurrating hydroger) to other unsaturated hydrocarbons. In addÃtioti; H2 rnay be formed in-sitif during the reaction through steam reforming of hydrocarbons and water-gaa-siiift r'eactiori, t4l 'The reaction zone preferably c=cmprises a reactor, whiah is equipped with a means for collecting the reaction products (syncrude, water, and gases), and a section, preferably at the bottom, where any metals or solids (,the "dreg stream") may accumulate:

Supercritical water conditions include a temperature from 374`C: (the critical temperature of water) to 1 0OO C, preferably from 374T to 600 G and mo5t preferably from 374`C to 400''C, apressure from 3,205 (the r,ritiral pressure of water) to 10,000 psia, preferably from 3,205 psia to 7,200 psia and most preferably from 3,205 to 4,000 psia, an oil/kvater volume ratia from 1:0. 1 to 1 : 10, preferably from `i : 0.5 to 1:3 and most preferably about 1:1 to 1:2.

The reactants are allowed to react under these conditions for a suificient time to allow upgrading reactions to occur. Preferably, the residence time will be selected to allow the upgrading reactions to occur selectively and to the fullest extent witi,Qut having undesirable side rea:,t#oris of c-oking or residue formatiori. Reactor residence times may be from 1 minute to 6 hours, preferably from 8 minrites to 2 hours and most preferably fror7i 20 to 40 minutes.

T'he f?e-at:ter-A reactor desigried for heavy oil upyracliny using supercritical water in accordance with the prtasent inventinn wÃII preferably include the following fi~atu1'es `

The reactor wi#i have means for adequate oil-water r3iÃxing and dzspersiQn.
Contrary to the conventional thermal cracking in an uncontrolled fashion that will lead to excPssi've formation of light hydrocarbon arid therefore lower liquid tiydr'ocark,en yield at the temperature and presszare i.inder supereritical water Gcinditions, heavy hydrocarbons will hydrothermally rrack irito lighter corrjponents. Furthermore, hydrac,arbore radicals formed from therma[
cracking will also recombine and polymerize and eventually beccririe coke.
Wa;er r110l=11e5, especially under super{:,ritical' conditions, can quench and stabilize hydrocarbon radicals and therefore prevent them from over cracking aÃ>d 1?aiymÃ.arizatien: To avoid over cracking into light hydrocarbons and coke formation, the heavy hydrocarbon molecules are preferably sr.rrrourlded by water molecules to the greatest practical ex#cnt. Therefore, the reactor includes means to assure adeqLrate mixing of oil with vvatef for the ptii'pose of achieving a high yield of liquid hydrocarbons. Such means should be cheseÃ3 so as to be able to haÃidle heavy oil feed which has low API gravity and h'igh viscosity at high oil to water ratio. Depending on specific applications such rrreans car: include, among others, (a) rÃozzles; (b) static mixer; (c) stirring vessel; (d) micre-uharrnel device; and sonic arid ultrasonic devic:e.
The reac;tiOri zone =r accordance with the present invention will preferably:
(1) Provide an appropriate residence time to achieve high conversion arid liquid yield. Controlling the residence time narrowly within determined lirnits is a veÃy impertant factoÃ- #or heavy oil upgrading usiny supercritical water. The desired products of heavy oil upgrading are liquid hydrocarbons. IrÃsLÃfficie.nt ÃesideÃice tiriie will lead to low conversion aÃid hence low liquid hydrocarbon yield. CJÃi the other h~.~rid, excess ccrrversican will lead to low value by proctLÃe;ts such as light hydrocarbon gas and coke. In order to achieve highly selective ~5 conversion to liqtÃid hydrocarbons, it is critical to maintain adequate residence time.
(2~ Provide suffiuieÃ'rt iieat tra#3sfer rate to maintain unrforÃii temperature distributiori. In s~:Omparing other supercritical water applications, heavy oil is a much more complicated feed and heavy oil upgradirrg is avenyeomplex precess, In addition, as indicated ahove, the desired lia id hydrocarbon is ar: intermediate product from selective, partial reaction. Therefore., it is extremely important to ccEitrol reaction temperature to achieve high liquid hydrocarbon yield.
A>r#ettuate control of reactioÃi terriperature cati be achieved by providirng enough heat trai-asfer area, uniform feed distrÃbution; or by quenching.
(3) Be able to handle ,dlid'. formed dLIring the reacticn. DfirirÃg the reaction, smal: aÃYzounts of solid byproducts, primarify inoÃ-ganic i ::`

15 rnaterials ,rrretals, sulfL#r: coke e.~tr;.), will be formed, and the reactÃcrl zone must be able to handle sLsch sc.~licl!s so they will rroi cause operating problems and will iirat contaminate the liquid hydrocarbon pÃodLfct.

The present rnvefitr,n also esiiploys a separation zone for product recevery.
The effluent strearra from the reaction zone c:oÃitairis liqLsid hy:.irc:cark.on, product, gas, water under supercritical conditions and solids. The liquid hydrocarbons are generally separated from other cUri-iponents to achieve high yield. The preferred way is to rc-rrÃave the solid first, and then bring the fluid phase containit?g hydrocarbon products, supercritica= water and gas byprodur=ts out ef supercritical condition by laxvving temperature, pressure or both so that liydrocarbon product and water will condense into liquid phase.
The solids are pr'imarily inorgariic materials iorrned during the reactions and õant<e separ-ated from the superr,ritical f1cÃid phase using sr;:parat=ori techniques kr3evura in the art, which could hea. disengaging zorie in the reactor or a separate device such as settling vessel, filter, cyclone ete;.

Another optÃon for separating the solids is to bring the prodt:ict stream out of supercritical regisiie by lowing temperature or pressure or bath. Then the solid will precipitate, A potential disadvantage of this optiori is that some of the inorganic components in the solid may dissolve in water, which may coritaÃi7ir3ate ttre liquid hyldroc;arbon pÃ-ottuct. It should Eae noted that depending on the specific applications, a reactor for heavy oil upgrading using supercritical water it} accordance with the present iriventieri Ãiiayf have rilere than one of each of the three components listed above.

t=;gure 1shows an erTita:.}diryient of the present invention, which has been used in a ;aboratary. An iniirie mixer is used for r'nixing heavy oil with water.
For th'ss specific errÃbodÃrÃier-Ãt it is a static mixer. The reaction zoÃie compr:sesa 3 5 spiral tube react-or with large length to diarreter rat;o to attain high velocity iriside t.he reactor, which is he;ipful to m aintain oi:-water dispersion.
This design also makes the fluid flow irrside the reer.tor elose to plug flow and .!:.~

tl-teÃ-efoÃe acttieves narrow residence tiriie dÃstribLÃtiOÃl for selective coÃivers-cÃ-s to desired. Eiquid hydrocarbons. Inorganic solids in the feed and forrrred during the reaction will not dissolve in supercritical water. Ã-tigh velocity insidc:~ the reactor also prevents settling of those inorganic solids. The smai: diameter of the reactor body also provides large spec,ific sur-face area for heat transfer to maintain uniform temperature cfistrit;utien iÃiside the reactor. The length of the re.aetor can be designed based on residence tinie needed for specific conversion. A second vessel is added to sett?e the salid5: The temperature a.rÃd pressure is maintained at the same values as those in the spiral tube so that the fluid in the second vessel is still at supercritical water conditions. Due to the larger cross-sectional area of the second vessel the flLÃid velocity is riiuch iower. As a result, inorganic materials separated from the fluid will settle down in the vessel, and can be remaver.~ from the systerti. Thc- fluid caritaining hydrocarbon products, si.rpercritical water and gas t?yprodÃicta is cooled while maintaining at the same pressure as in the reactor, and fiydtOcarborr procitacfs and water are condensed in the liigti pressure separator.

A spiral tube with. a high length to diarneter, ratio, which may be frorn 50 to 10,000, preferably frcÃii 100 to 4,000 may be used as reactor body. Use of such a reactor lias the advantages of high velocity, nLirraw residence time ;.tistribLÃtivn, and large surtace for heat transfer. The length to diamet=er ratio is a useful paranieter to determine preferred reactor LonttqÃar=atinr3s. The diarYie=ter may be cteterrriiraed by velocity needed to avoid solids ptecipitation and then the length can be seIected to provit;t~~ the desired residence time.
Otlier reactor carrfiguratirans knnwri to those m the art can be used to achieve similar effects, sÃ.rch as a serpentine reactor.

i;n the errat.~odiments strow=t irà Figure 1 the separation zarir for rernovir:q solid and recovering hydrocarbon products is a vessel with a dip tube. Ut--rer fluid -solid separation devices known in tho- art can be used to achieve the separation effect, which includes, but not limited to, cyclone, filter, ceramic membrane, settling tank, etc.

Iri the emk,o,iitnerit shown iri t"ic~~re- 1. as well as ir) other embodiments described herein, the mixer, reaction and separation zones are separated.
Such arrangement is conver?ient for (ataoratory research, and is cased as an illustrative example. It is within the scope of the prp-sent invent;ort and in serne applications will be beneficial to integrate these three functions into one vessel.

As mentioned above, the reaetor may include more than one piece of each furiction devices. Figure 2 shows an exaxmple. In order to avoid over cracking of the feed to form uridesired byproducts such as light hydrocarbon gases and coke, heaT/ hydrocarbvr-1 molecules are preferably surrounded by sufficient water mOler,ules. Generally speaking, a higher water to oil ratio wil( be helpful to riiaiiitaiii ttie desired environment. However, high water to oil ratio also zrieans higti equiprr3er3t and s~peratir3g cost. The emlaadi~ient shown in Figure 2 can achieve tiigh water to oil ratio locally withcatit iÃicreasina, overafl water to 2~.~ feed i-:atio. Instead of mixing all the feed oil with water at reactor inlet, this embodiment uses multiple injections of oil to tnaititain a desired water to oil ratio. Such a desigri is also helpful to control reactioti ternperature. By dÃstributirig feed oil more uniformly through the reactor length, reaction temperature will tiot increase too much clue to the exotherrRic.nature of the reactions.

Only two Ãr~~ections were shown in Figure 2. This is not intended as a ;ii'riitatÃon, A reactor with multiple injections may also be used, In addition, one or more settiiÃiq vessels can be added to a reactor witf-i a mLlitiple injection configÃarat:on to achieve solid se:paratioE; under supercriticai conditions.
Figure 3 shows yet another embodiment with more than one mixing and reaction zones. A second mixer, which may or may not be the same as the first mixer, is added beh-veer~ reaction zone to enhance the cilisupercriticai ~5 water s-iiixiria. Agairs, nnultiplG mixc-rs arid reaction zonfes cari be used.
The upgradiriy rea ctior, is exotherrriic. A reactor with ~.~ iaraesurface area W'ps to mainta;n uniform temperature distribution inside the reactor, Deperictirrg on feed pÃ-apertisws, heat exchange tf3rouyti the surface area provided by the reactor may or may not be enough. Water can be used to quench the reaction stream and thereby control the reaction temperature.
Figure 4 shows an embodiment of us:ing water to quench the reaction stream between two reactiori zones. The amount of water used for quenching should be enough to bring down the reaction temperature while the reaction stream after q,LÃenching still maintain sUpercriticai conc:i#tions. NiuI ip:e reaction zones and water rtÃtenching may t.t-, necessary for some feerts The quenching water can also be used to for product r=ero5.rery, as shown iÃz Figure 5. After reaction the product stream is qLjenched by liquid water.
'f'he solid wiil be washed out by the water, and due to the temperature reduction caused by quenching water and the hydrocarbons will condense as liquid.
Reactior: Prodt_tcf Separatior) After the reaction has progressed sufÃicir/ntÃy, a sitig6'e phase reactÃoti product is withdrawn from the reaction zone, cooled, and separated Frito gas, effluent wat:er arid upgraded hydrocarbon phases.. I'his separation is preferably done by cooling the stream and using one or riiore tvvo-phase separators, threa-phase separators, or other gas-oil-vvater separation device known in the art However, any met}iod of separation uari be used ir7 accordarice with the ;nver,tion.

Thirr comt,ositian of gaseous product obtained by treatment of the heavy hydrocarbons ir, accordance with the process of the prasc-nt invention will depend on feed properties and typically comprises light hydrocarbons, water vapor, acid gas (CQ; and H28), methane and hydrogen. The effluent water may be used: reused or dis{:arded. It may be recycled to e.g. the fQed water tarik, the feed water treatment system or to the reaction zone.
Ttie upgraded hydrocarbon product, which is sometimes referred to as synurÃade" herein may be Ãipgrac3ed fr,irther or processed into other hydrocarboFi products using methods that are knoWr) Ãn the i'lydroMa;-t;rrn proce.ssir7g art.

'T'ha process of the present invention may be, carried out either as a continuous or semi..=ItinuO4fs process or a batch process or as acontinLious praGess. In the continuous process th~:~ entire system operates with a feed stream of oil and a separate feed stream of s-upere;ritica= water and reac"hes a steady state; whereby a(1 the flow rates, temperatrires; presswres, and compositicÃ3 of the iiilet, outlet, and recycle streams do riot vary appreciably with tÃme;
While not being bound to any theory of operation, it is believed that r.a number of upgrading reactions are accurrina simuitapeotisly at the supercritica( water conditions used in the present process. In apreferrsd embodiment of the invention the rnajor chemical/upgrading reactions are believed to be:
Thermal Crackang: CrH, --~ lighter hydrocarbons Stear73 Refarrriing: C,H,, + 2xH,,,O = xCt.~r + t2x~y~~lHz Water-Gas-5t1rf#: CO + H1O = CO2 + H2 ner~netaFizatiori: Cxf-iL;Ni,+ Ã~~~O/i==i~ ..-=~ NiOr'Ni(011+ + lighter hydrocarbons 26 DesulfuriratiaÃi:: C:<Hy5, + HzOfH> H2S + lighter hydrocarbons The exact pathway may ~eper3d on the reactor operating conditions {temperature, prassure, OlVd volume ratica), reactor desigrt (mode of 4=cntactfmixrng, sequence of heating), and the hydrocarhan ieedstocK.
The fo;iavving Examples are i:lustr ative ntthe prc-sai#t invention, but are not intended to liÃtiit the invention in any way beyond what is contained ir) the claims which foilovv.

EXAMPLE I -- Process Conditions.

Oil and superc;ritie:al water are contacted in a mixer prior tc, entering the reactor. The reactor is equipped with an inner tube for caliactirig the preoclucts (syncrude, excess water, and gas), and a b(3ttG+rTl section where ctflsj Ã?letclls Vr solids comprising a ><dreg stream" of ineteterliiÃnate properties or composition may accumulate. The sheiE-s;de of the reactor is kept isothermal during the reaction with a clamshell furnace and tc3'riperature oontroller: Preferred reactor residence tirnes are 2040 miÃiutes, with preferred oil/water volume ratios on the order of 1:3. Preferred temperatures are around :.~74'.. 440`C:
with the pressure at 3200-4000 psig: The reactor product stream :eaves as a single phase, and is cooled and separated intc:z gas, syncrude, and effiLrent water. The eft:fJent thfater is recycled back to the reactor. Sulfur fror-n the orig;raal feedstock accumulates in the dreg strearn for the riicst part, with lesser amounts prirnariiy in the form of H,,4 fcrunrt in the gas phase and water phase.

As the next examples wil; show, very little gas is produced in most cases.
With suitable choice of operating conditions, it is also possible to reduce or nearly eiiniiriato the "dreg streani." Elimination of the dreg strearii Ãneans that a greatei- degree of hydrocarboÃi is recovered as syncrude, but it also rrieans that metals and sulftsr will accumulate elsPwhore, such as in the water and gas streams.

EXAMPLE 2 -Properties of the, Product Syncrude.

A Ha,iiaca CrLide oil was di1uted with a diluent hydrocarbon at. a ratio of 5:1 (20 vQl":'0 of diluerif). The diluted FtaÃ-Ãiaca crude oil propeit;es were measured before reacting it with the supercritical water process as referred to i.n Exariiple 1 and Fig. 2. The properties of the crude were as fo;lows: 12,8 API
gravity at 60/6ir.~, 1329 CST viscosity @400C; 7.66 wt% C/H ratio; 13.04 wt%
MCRT; 3.54 ~rd"zo sulfur; 0.56 wtfio nitrogen; 3.05 mg KOH/gm acid number;
1.41 wt% water; 371 ppm tr'anadium, and 86 ppm Nrokel. The diluted Harnaca crude oil after the s+.tper critical water treatment was converted into a 36 syncrude witxt the following properties: 24.1 API gravity at 60,160> 5.75 CST
viscosity @40 C; 7.40 wt% CfH ratio; 2.25 wl% MCRT; 2.83,wt% sulfur; 0.28 wt`!~, n,1troqean1; 1 .54 mg KOH/gÃ~n acid nur73bErt 0,96 wt% water; 24 pprtl ~~t Var3adir.uii; and ~ppr~i Nir;ieel. Suhstaritial reduct30ris ir) riletals and resic3L#es were observed, with s<mu,"tanear_Ãs irrtorease in the API gravity and a significant decrease in the viscosity of the original crude oil feedstock. There were modest reductions in the Tntal Acid number, sulfur concentratior?, and riitrOgeri concentration w}iic-h cOr.rld be improved with further optinlization of the reaction conditions.

When the c3ilErtecf Harnaca crude was sent directly to the reactor Mfl<?Or.rt beirig first heated with supercr'iti; al water, the procfrÃt:t syncrude had tht-!,' following propert:ies: 14.0 API gravity at 60/60: 188 CST viscosity @40'-G; 8.7 wt%
MCRT: 3.11 wt% sulfur, 267 ppm Vanadiurr3, and 59 ppm Nickel. This comparison demonstrates the importance of the heating seqLjance of the present invention.

Apart froai the occasional, sr~rall acc;umulatiOri of a dreg strearÃi, ttiere is very little caking or solid byproducts formed in the super.riticas water reactior).
Ttle material balance was perfarrried for two separate experrr-neritaf runs.

In the experimental rtÃn with no dreg stream forriiÃ:d, the startingfeedstOGk of dilr.ited Harnae,a crude at 60 grams produced a syricrude produc.t of 59.25 grams which corresponds to a high overall recovery of 99 percerrt. It v+ras thought that due to the absence of a dreg stream, the experimental mass balance was impacted in the determination of the sulfur and metals. 'f'he gas phase did not contain rnetafs species and had little sLtlfur ceÃxipOur;ds_ It was hypothesized that a pcrfion of the metal and sulfur may have accurnulated on the walls of the reactor or ~ownstrearii plumbing.

In the experimer.tal rur:: with a dreg stream fOrrriert: the starting teedstOck cf' diluted Hamaca crude at 30 grarns produced a syncrude product of 22.73 grams. The dreg stream that was formed accounted for 5.5 grams. The overall recovery with the dreg strea:rt, was 96.7 percerit. In Ifie c.ireg strearrt, sulfur accounted for 31% of the total sulfur with the remainirag sulfur in the oil, product, water phase; and gas phase. The mc~tals content of the dreg streaÃii = CA 02667261 2009-04-22 accuLfrÃted for 82 'o of ti`{e total rrs~.~taIs with the remaining metals in the oil prcdÃ.rct. For commercial operations, it may be preferable to miriirÃ-Ãize ttle formation of a dreg strearn, since it represents a 18% reduction in syncrÃ.ade prodtÃcf, arid generates a lower value product stream that impacts the process in terh-is of economics and disposal concerns.
1C}
Undiluted Boscan crude oil prcperties were measured before reacting it with thp sUperC ritical water process of the~ prese,nt invention. 'rhe fsropt~rties of the crude were as follows: 9 API gravity at 60/60, 1,140 CST viscosity @40 C:
8.0 vA% C/H ratie; 16 wt% MCRT; 5.8 wt% SÃi{fur; arar? 1,280 ppm Vanadium;.
The undiluted Boscan crude oil after the super critical water treatment was converted into a syncrude with the following properties: 22 API gravity at 60160; 9 CST viscosity @40 C; 7.6 wt% C/H ratio; 2.5 wt:'u MCRT: 4.6%
sulfur; and 130 ppm Vanadium.

A simulated clFstillatio>i aÃialysis of the original crr.Ãde oil vs, the syncrude products from different experimental runs shows that the syncrude prepared in accordance with the present invention clearly has superior properties than the original crude. Specifically: the syncrudes caritain a higher fraction of IOwer-boiiirÃg fractions. 511~,; of the diluted Hamaca crtide bo3is across a range of temperatures of less than 1000'F, while emplaying a process accOrdir}g to the present invention usirig supercritical water depending on process c;onfiguratiorss, between 79 to 94% of the syricrude boils across a range Of ter-raperatures of less than 1000 i". 40% of the uradilr,rted Bascan crÃide boils across a range of ternperatures of less thar= 1000''F, while employing a process accord:ng to the present invention iusing superÃ;riticaf water, 939/1<
of the syncrude boils across a range of temperatures of less than 10001-.
There are riLÃmerous variations on the present invention which are possible in light of the teach;Ã7gs arÃd sup:pGrting exarrsples described hereiÃi. It is therefore understood that wit:hin, the scope of the following claims, the invention may be practiced otheNvise thari as specificaify described or exemplified here:n.
"it

Claims (20)

1. WHAT IS CLAIMED IS:
   
   A process for upgrading hydrocarbons comprising:
   
   (a) mixing hydrocarbons with a fluid comprising water that has been heated to a temperature higher than its critical temperature in a mixing zone under conditions that disfavor thermal cracking and formation of coke to form a mixture, (b) passing the mixture to a reaction zone;
   
   (c) reacting the mixture in the reaction zone having a substantially uniform temperature distribution and being configured to reduce the settling of solids within the reaction zone said reaction occurring under supercritical water conditions in the absence of externally added hydrogen for a residence time controlled within determined limits to allow upgrading reactions to occur;
   
   (d) withdrawing a single-phase reaction product from the reaction zone; and (e) separating the reaction product into gas, effluent water, and upgraded hydrocarbon phases.
2. 2. A process according to claim 1 wherein the hydrocarbons are heavy hydrocarbons selected from the group consisting of whole heavy petroleum crude oil, tar sand bitumen, heavy hydrocarbon fractions obtained from crude petroleum oils, heavy vacuum gas oils, vacuum residuum, petroleum tar, coal tar and their mixtures.
3. 3. A process according to claim 1, wherein the fluid comprising water enters the mixing zone at a temperature sufficiently higher than the critical temperature of water so as to cause the resulting mixture to have a temperature higher than the supercritical temperature of water.
4. 4. A process according to claim 1, wherein the heavy hydrocarbons in step (a) are at a temperature of from 10O°C to 200°C.
5. 5. A process according to claim 1, wherein the supercritical water conditions include a temperature from 374°C to 1000°C, a pressure, from 3,205 psia to 10.000 psia an oil/water volume ratio from 1:0.1 to 1:5 and where the residence time is from 1 minute to 6 hours.
6. 6. A process according to claim 1, wherein the supercritical water conditions include a temperature from 374°C to 600°C, a pressure from 3,205 psia to 7,200 psia, an oil/water volume ratio from 1:0.5 to 1:3 and where the residence time is from 8 minutes to 2 hours.
7. 7. A process according to claim 1, wherein the supercritical water conditions include a temperature from 374°C to 400°C , a pressure from 3,205 psia to 4,000 psia, an oil/water volume ratio from 1:1 to 1:2 and where the residence time is from 20 to 40 minutes.
8. 8. A process according to claim 1, wherein the mixture in the reaction zone is reacted in the absence of any externally supplied catalyst or, promoter.
9. 9. A process according to claim 1, further comprising the step of heating the mixture formed in step (a) to a temperature higher than the critical temperature of water before passing the mixture to the reaction zone.
10. 10. A process according to claim 1, wherein the uniform temperature distribution is obtained by controlling the heat transfer area in the reaction zone, by uniformly distributing the hydrocarbon feed or by quenching.
11. 11. A process for upgrading heavy hydrocarbons comprising:
    
    (a) mixing heavy hydrocarbons with a fluid comprising supercritical water having a temperature higher than the critical temperature of water in a mixing zone under conditions that disfavor thermal cracking and formation of coke to form a mixture having a temperature higher than the critical temperature of water;
    
    (b) passing the mixture to a reaction zone;
    
    (c) reacting the mixture in the reaction zone having a substantially uniform temperature distribution and being configured to reduce the settling of solids within the reaction zone said reaction occurring under supercritical water conditions in the absence of externally added hydrogen and catalyst for a residence time controlled within determined limits to allow upgrading reactions to occur;
    
    (d) withdrawing a single-phase reaction product from the reaction zone; and (e) separating the reaction product into gas, effluent water, and upgraded hydrocarbon phases.
12. 12. A process according to claim 11, wherein the hydrocarbons are heavy hydrocarbons selected from the group consisting of whole heavy petroleum crude oil, tar sand bitumen, heavy hydrocarbon fractions obtained from crude petroleum oils, heavy vacuum gas oils, vacuum residuum, petroleum tar, coal tar and their mixtures.
13. 13. A process according to claim 11, wherein the fluid comprising water enters the mixing zone at a temperature sufficiently greater than the supercritical temperature of water so as to cause the resulting mixture to have a temperature higher than the critical temperature of water.
14. 14. A process according to claim 11, wherein the heavy hydrocarbons in step (a) are at a temperature of from 1 100°C to 200°C.
15. 15. A process according to claim 11, wherein the supercritical water conditions include a temperature from 374°C to 1000°C , a pressure from 3,205 psia to 10,000 psia an oil/water volume ratio from 1:0.1 to 1:5 and where the residence time is from 1 minute to 6 hours.
16. 16. A process according to claim 11, wherein the supercritical water conditions include a temperature from 374°C to 600°C , a pressure from 3,205 psia to 7,200 psia, an oil/water volume ratio from 1:0.5 to 1.3 and where the residence time is from 8 minutes to 2 hours.
17. 17. A process according to claim 11, wherein the supercritical water conditions include a temperature from 374°C to 400°C , a pressure from 3,205 psia to 4,000 psia, an oil/water volume ratio from 1:1 to 1:2 and where the residence time is from 20 to 40 minutes.
18. 18. A process according to claim 11, wherein the mixture in the, reaction zone is reacted in the absence of any externally supplied catalyst or promoter.
19. 19. A process according to claim 11, further comprising the step of heating the mixture formed in step (a) to a temperature higher than the critical temperature of water before passing the mixture to the reaction zone,
20. 20. A process according to claim 11, wherein the uniform temperature.
    distribution is obtained by controlling the heat transfer area in the reaction zone, by uniformly distributing the hydrocarbon feed or by quenching.