EMULSION BREAKING BY CONDENSATION

Abstract: Used Motor Oil (UMO) is reprocessed by vaporization and partial condensation. The UMO vapor fraction from the thermal reactor (10) may contain gasoline and chlorinated solvents, and will contain vaporized lubricating oil boiling range components and surfactants or other additives in an amount sufficient to form an emulsion if the UMO vapor is condensed to a temperature sufficient to produce a liquid water phase. Partial cooling of the vapor in heat exchange means (20), at a temperature above the boiling point of water, ensures that a dry, emulsion-free, liquid hydrocarbon product is produced. The vapor phase remaining, after condensation of the lube oil boiling range hydrocarbons in the hot separator (30), is then condensed to produce a liquid phase, which can be processed in conventional wastewater treatment facilities. The process permits re-refining of UMO by vaporization without venting or flaring any vapor streams directly derived from the UMO process.

Description: EMULSION BREAKING BY CONDENSATION FIELD OF THE INVENTION The invention generally relates to the reprocessing of Used Motor Oil (UMO) and specifically to selective condensation of steam and hydrocarbon vapors derived from such a process. BACKGROUND OF THE INVENTION For more than one hundred years refiners have devoted considerable energy toward creation of stable, long-lasting lubricating oils for gasoline and diesel engines. Detergents and other surfactants were added to keep in suspension dirt and other particulate matter that found its way into lubricating oil. Zinc additives imparted wear resistance and other desirable properties. Polymer was added to improve viscosity index, and other additives to prevent rust and reduce wear. Unfortunately the same additives that enabled lubricating oil to do so many things and withstand extended periods of operation in high temperature internal combustion engines effectively disabled conventional methods of heating and distilling oil. UMO was difficult to recycle. Myriad processes for the reprocessing of UMO were developed or at least proposed in the patent and other literature. Some processes take a "brute force" approach and subject the UMO to severe thermal processing by dumping it into a coker. The coker converts some of the UMO into coke having little value and most of the UMO into low value, normally liquid, hydrocarbon products that can be upgraded in a conventional refinery. Unfortunately the chloride content of most UMO, due somewhat to the presence of chlorine compounds in oil additives and predominantly to improper collection and commingling with chlorinated solvents, causes problems. These chlorides break down and form corrosive vapors that can cause much mischief in any unit that tries to process the oils. A mild thermal cracking process, relative to coking, was proposed in US 5,885,444. Thermal cracking at 600 to 725°F, at ambient pressure, produced diesel and lighter hydrocarbons as an overhead vapor which was cooled to condense a #2 diesel. Uncondensed vapors were burned in a thermal oxidizer. Many oil re-refiners use Wiped Film Evaporators (WFE) to permit high "lift" of UMO by high temperature processing of UMO without clogging up equipment. Such equipment is expensive and has low capacity. Some re-refiners used filtration and/or solvent extraction, some with pretreatment with acids or bases. The present invention deals with a troublesome, vapor product stream which can be generated by some UMO processes, i.e. a vapor phase stream comprising significant amounts of water vapor, vaporized normally liquid hydrocarbons boiling in the lube oil range and polymer and/or other surface active agents added to the virgin lubricating oil. This UMO vapor phase may also contain gasoline boiling range components and/or solvents. If the UMO processing reactor or fractionator is run at sufficient temperature to recover significant portions of the lubricating oil boiling range components present in the UMO, then large amounts of surface active materials end up in the overhead vapor phase. If this vapor is condensed, the surfactants and/or other vaporized additives and the native water or steam added during UMO processing form a stable emulsion with the lubricating oil boiling range components. Used oil and water can mix and form a stable emulsion in the presence of the robust surfactants in modern motor oils. This emulsified product of UMO processing can be as troublesome to work with as the UMO feed. It is believed that this tendency of vaporized UMO components to form intractable emulsions is a factor behind processes which resort to pre-processing to dehydrate the UMO prior to severe processing, or destroy the UMO in a severe thermal process such as a coker which destroys most additives or burn a troublesome vapor phase in an incinerator, as in US 5,885,444. We discovered a way to process UMO distillate and surfactant rich overhead vapor streams to recover significant amounts of high boiling lube components without forming an emulsion and without burning or flaring any portion of this vapor stream. BRIEF SUMMARY OF THE INVENTION Accordingly, the present invention provides a process for refining UMO feed comprising 0-50 wt.% water, 0-15 wt.% gasoline and lighter, normally liquid hydrocarbon components, at least 50 wt.% lube oil boiling range components, and a sufficient amount of vaporizable detergents and/or surface active agents (surfactants) to form an oil/water emulsion when vaporized lube oil boiling range components are condensed in the presence of steam or water comprising heating and partially vaporizing said UMO feed to produce a UMO overhead vapor phase comprising essentially all of the gasoline boiling range components which may be present, at least a majority of the lubricating oil boiling range components in the UMO feed, and a sufficient amount of detergents and/or surfactants to produce an overhead vapor fraction which can be condensed to form an emulsion of oil and water; cooling to a temperature above the boiling point of water and partially condensing from said UMO 75 overhead vapor at least a majority of said gasoline boiling range components, if present, at least a majority of said lubricating oil boiling range components, and at least a portion of said surfactants to produce a two phase mixture, a liquid hydrocarbon phase which is essentially free of a separate liquid water phase, and a vapor phase stream deficient in gasoline and lubricating oil; separating in a hot separator, 80 maintained at a temperature above the boiling point of water, said two phase mixture into a liquid hydrocarbon phase which is removed as a product and a vapor phase; and cooling and condensing said vapor phase from said hot separator to produce a liquid product. In another embodiment the present invention provides a process for reprocessing a UMO and water emulsion comprising surface active agents, gasoline boiling range components, lube oil boiling range components, and surfactant additives comprising heating said UMO at least in part by the direct injection of steam in an 5 amount, and at a temperature, sufficient to vaporize essentially all of said gasoline, essentially all of said water, at least a majority of said lube boiling range components, and at least sufficient surfactants to produce a UMO reactor overhead vapor stream which will form an oil/water emulsion if cooled to the dew point to produce liquid water; cooling, partially condensing and separating said UMO reactor overhead vapor 10 steam in a hot separator at a temperature and pressure sufficient to condense essentially all of said gasoline and lubricating oil boiling range components, without producing a separate liquid water phase, to produce a liquid hydrocarbon product which is essentially free of liquid water phase and a vapor product consisting essentially of steam and a minor amount of vaporized hydrocarbons; and condensing said vapor 15 product to form liquid water as a product. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a simplified process flow diagram of a preferred embodiment of the invention. UMO in line 1 is charged to thermal reactor or vaporizer 10. The UMO is heated by direct injection of superheated steam from line 5. The UMO is typically preheated by one or more indirect heat exchange means not shown with various hot effluent streams created by the UMO plant or that may be found in a refinery or other nearby process unit. Thermal reactor 10 may be insulated but need not be heated and preferably does not have a fired heater associated therewith. UMO overhead (OH) vapors are removed via line 17, pass through heat exchange means 20 and charged to hot separator 30. Hot separator 30 operates at a temperature low enough to condense essentially all of the diesel and/or lubricating oil boiling range components, all or almost all of the gasoline boiling range components, but essentially no liquid water. The condensed liquid hydrocarbon phase will contain significant amounts of volatile surface active materials, polymer, and the like present in the UMO charge. The surfactants will be present in an amount sufficient to form an emulsion if the UMO vapor stream was cooled enough to produce liquid water. The careful, partial, condensation of hot UMO reactor vapors ensures that a dry, liquid hydrocarbon stream is produced, which is removed via line 35. Hot separator overhead vapors, essentially steam or other injected superheated vapors, are removed via line 37 and cooled in cooling means 40 to be discharged into receiver 50. Preferably conditions upstream in the UMO vaporizer 10 and in hot separator 30 are adjusted so that only a water phase forms in receiver 50. This water phase will contain a modest amount of dissolved hydrocarbons and may be discharged via line 55 into sewer means 64 for further conventional wastewater treatment. Figure 2 is a more detailed process flow diagram of a steam heated UMO process using emulsion breaking by condensation. UMO feed in line 101 is heat exchanged in heat exchanger 1-99-E-4 and 1-99- E-l to produce a pre-heated feed which is discharged into pre-flash drum 1-99-F-l. A pre-flash drum overhead vapor stream is removed via line 2 and charged into the hot- flash separator. The flashed feed is removed from the pre-flash drum and pumped via line 3 into one of four thermal swing reactors, 1-99-D-l, 1-99-D-2, 1-99-D-3, or 1-99- D-4. For purposes of illustration presume that 1-99-D-l is in the fill cycle, while 1- 99-D-2 is on a heat cycle with superheated steam added via line 9. Thermal reactor 1- 99-D-3 is on a drain cycle and discharges a residue product via line 5, through a surge drum 1-99-F-4 for heat exchange against boiler feed water makeup. Hot UMO OH vapors are removed from the #2 thermal reactor, 1-99-D-2, and quenched by heat exchange with boiler feed water, then heat exchanged against UMO feed and then charged to hot flash separator 1-99-F-2. A hot vapor phase is removed at 300°F, cooled in fin-fan cooler 1-99-E-5 and charged via line 6 to wastewater treatment. A liquid hydrocarbon, gas oil product phase is removed from the hot flash separator and charged via line 7 as a gas oil product phase. Typically, as used herein, the term "gasoline boiling range" means hydrocarbons having the boiling range of conventional gasoline fuels. Although some C4's and C5's may be present, most of the gasoline boiling range component in UMO will be in the C6-C10 range. Expressed as boiling points in UMO, these components will boil in the range of 100-350°F and more likely 150-300°F. The term "distillate" or lube oil boiling range hydrocarbons means normally liquid hydrocarbons boiling above the gasoline boiling range, above 300°F, typically above 350 or even 400°F. Most distillates present will boil in the range of 400-650°F. OPERATING CONDITIONS PREHEAT Preferably, the UMO is preheated by heat exchange with process streams or steam so it has a temperature of at least 300°F. Mild preheating in a fired heater is also possible. Preheating above 400°F should be avoided because at such temperatures fouling of heat exchange surfaces can occur. Fouling will occur rapidly above 500°F. If a refiner does not mind frequent shutdowns for removal of heat exchange deposits, it is possible to have even higher preheat temperatures. More heat exchange is thermally beneficial, though in commercial practice it is believed that the benefits of more preheat will not be offset by the aggravation of more downtime for maintenance. OPTIONAL PRE-FLASH It may be beneficial to subject the UMO to a pre-flash step to remove some of the light ends, water, solvents and the like that may be present. This can partially, or completely, dehydrate UMO feed to the thermal reactors. Removal of the gasoline boiling range hydrocarbons and a minor amount, say the lightest 2-20 wt.%, of the distillate boiling range oil present in a UMO feed allows water, solvent, gasoline and some distillate to be removed using low grade energy. This increases the effective capacity of the thermal reactors. Such pre-flash stripping, if practiced, can occur at vacuum or under a few atmospheres pressure at temperatures from roughly 200°F- 400°F or even higher. Preferably, the pre-flash vapors are eventually commingled with the vapor phase from the hot separator so that only a single vapor handling means is necessary for the plant. GOLDILOCKS HEAT EXCHANGE In a preferred embodiment, a heat exchange method is used which simultaneously ensures: no water phase forms during condensation of distillates in UMO OH vapor, and no portion of the UMO feed is exposed to unduly high temperatures during preheating. This approach ensures that the UMO feed does not get too hot (which causes coking/deposit formation) and that the UMO vapors from the thermal reactor or UMO vaporizer do not get too cold (which could cause liquid water and an emulsion to form). The "Goldilocks" heat exchange, like the porridge of Goldilocks and the three bears, is not too hot and not too cold. Goldilocks heat exchange is just right for our UMO process. To achieve this, and improve the thermal efficiency of the plant, the approach shown in Figure 3 is used. A UMO feed is charged via line 301 to optional conventional indirect heat exchange means 305 to heat exchanger 310. The UMO feed is heated to any desired temperature by heat exchange with condensing steam, in this case 150 psig steam. This condensing steam heats the UMO to a temperature approaching, but never exceeding, the temperature of the condensing steam. It is possible to have very high preheat temperatures by using high pressure or superheated steam, but allowing the steam to condense in the heat exchanger to form liquid water sets an upper limit on temperature in the condensing side of the heat exchanger, arbitrarily shown as the shell side in the Figure. This tempered preheat step is essential, but only l A of the Goldilocks process. The preheated UMO is then charged via line 315 to thermal reactor 330 wherein the preheated UMO is vaporized by direct injection of steam. The UMO is heated to a temperature sufficient to vaporize the desired amount of distillate boiling range material and surfactants. The UMO overhead vapor is usually above 500°F, hot enough to cause additive decomposition of UMO feed. Such UMO OH vapor is a somewhat dangerous stream to use for preheating the feed as decomposition or fouling may start in one portion of a heat exchanger and eventually foul the exchanger. To avoid this, the UMO overhead (OH) vapor may be quenched or heat exchanged against a non-coking substance, which could be water or some other refinery stream, in optional heat exchange means 340 to produce a quenched UMO OH vapor which is charged via line 341 to heat exchanger means 350. In exchanger 350, a cooled fraction, preferably condensate water from exchanger 310, is heated by indirect heat exchange against hot UMO vapors exiting thermal reactor 330. The temperature of the "cooling" liquid, condensate in line 313, will be, in this example, close to that of the temperature at which 150 psig steam condenses, or 366°F. The condensate will be vaporized and superheated to a temperature approaching that of the UMO vapor, or typically 10-50°F cooler to provide ample delta T to reduce the amount of surface area needed for heat exchange. The UMO OH vapor is cooled by the heat exchange, but not below the temperature of the incoming condensate water, which will have a temperature near that of condensing 150 psig steam. As thermal reactor 330 operates at near atmospheric pressure, no water phase can form in the cooled UMO OH vapor. There will be essentially complete condensation of normally liquid distillate hydrocarbons in heat exchanger 350, but no water phase will form. The cooled UMO OH vapor then passes through optional heat exchange means 355 into receiver 360 via line 356. A condensed distillate product which is essentially free of liquid water is withdrawn via line 361. A vapor phase stream, essentially steam, perhaps with a minor amount of vaporized, normally gasoline boiling range components or solvent, if present, is cooled in either conventional heat exchanger 370 or fin-fan cooler 380 to produce condensate which is discharged via line 381 into condensate receiver 390. An oily water stream is withdrawn via line 391 and will usually be sent to conventional water treatment facilities. The heat input to vessel 330 will usually be supplemented by additional superheated steam which may be added via line 315. An alternative, or supplement, is to rely entirely on steam added via line 314 and add more heat to this steam, using, e.g., a fired heater or other high grade heat source not shown to superheat the steam in line 314 to any desired temperature. Vessel 330 may be batch or continuous. If a batch process is used, multiple swing reactors or vaporizers should be used to ensure the process operates reasonably continuously overall. Depending on the local cost of energy and capital, it may be desirable to limit the number and/or size of heat exchangers. If capital costs are high and energy readily available, as by burning some of the UMO product, the optimum plant design may require only exchangers 310 and 350. If maximum energy savings is desired, then additional heat exchangers, such as 305, 355 and 370, may be used. THERMAL REACTOR/VAPORIZER The process of the present invention does not require any special type of reactor, per se. Conventional techniques can be used to heat/vaporize the UMO, e.g. use of a fired heater to supply some or all of the heat input to the vaporization vessel holding the UMO. As an example, a UMO fraction containing a large amount, e.g. 10- 15 wt.%) water, can be charged to a fractionator vessel with a fired heater reboiler. The reboiler will coke up quickly and have to be shut down frequently to have deposits removed from inside the heater tubes, but the vapor produced will contain more steam than distillate (on a molar basis) and enough surfactants to form an emulsion. As another example, a WFE may be used to heat a water containing UMO feed, or steam may be added to the WFE to aid in removal of distillable distillate from the UMO, and produce a UMO vapor phase with sufficient surfactant and steam to form an emulsion upon cooling. Using these conventional approaches to heating and vaporizing the UMO will still require removal of enough distillate fraction to ensure that the gasoline boiling range material will be condensed with the distillate, leaving a steam fraction which can be condensed to form an oily waste water stream. Phrased another way, conventional UMO vaporization means may be used, but are not preferred, to form a hot UMO vapor fraction which the process of the present invention can treat to avoid the formation of an emulsion. The process of the present invention is especially beneficial when the preferred, direct steam heating method is used for vaporization of the UMO. A preferred embodiment includes the batch, steam heating method disclosed in Figure 2, which is reviewed next. BATCH STEAM PROCESS The use of multiple thermal reactors is preferred for the practice of the present invention. A plurality of thermal reactors, each operating in batch mode, work together so that the feed rate to the plant is constant, the product production rate is constant and the only changes in operation are internal as reactors fill and empty. The essence of a thermal batch reactor is thermal processing of UMO by direct contact heat exchange with a heating vapor. The feed can be preheated or not. Lack of pre-heat means that more heating vapor is required to reach the desired end temperature. The UMO feed can be dry or contain large amounts of water. The heating vapor is preferably steam, but any high heat capacity, condensable or recyclable vapor can be used. In a typical cycle, which can take from a few minutes to many hours, and preferably takes around 20-60 minutes, UMO is charged to a vessel during a fill cycle until a desired liquid level is obtained, typically half-full. Usually a modest amount of superheated steam is added continuously during filling to ensure the steam line remains open, but this is not essential from a process point of view. By the time the vessel has the desired amount of oil, superheated vapor injection, preferably steam, is started, preferably via a distributor means such as a slotted pipe, tuyere, open pipe, or the like, immersed beneath the surface of the UMO. A stirring means may be present, but usually the energy of the entering hot vapors is sufficient to agitate the UMO liquid. Hot vapor injection continues until the desired degree of lift is achieved. Usually more than 30%) of the lube oil boiling range components will be vaporized. In many units, more than 50 wt.% of the lube oil boiling range components will be vaporized, or even more, such as 70-80%> "lift". There really is no upper limit on removal and it is possible to get up to 90-95%> removal of lubricating oil boiling range fractions, but such high removals leave a difficult to process residue in the bottom of the vessel. Usually it is desirable to leave some of the vaporizable heavy components in the residue fraction permitting easy removal of this material. At this point thermal processing or UMO vaporization is complete and the thermal reactor would go into a drain cycle where no steam or UMO would be added, save for minor amounts of steam to ensure that the steam inlets do not clog. In terms of temperature and pressure, the thermal reactors can operate under vacuum or modest pressure, e.g. from 14 atmosphere to 5 or 10 atmospheres absolute. In practice, atmospheric pressure operation works well with the only additional pressure being that required to move fluids through the system. Typically the product receivers will operate at about atmospheric pressure while the thermal reactor will operate at this pressure plus the pressure drop needed to pass the UMO OH vapor through various heat exchangers, vessels and piping. The process lends itself to operation under a mild vacuum, especially as it can be run to condense in the hot separator 90 + %>, and preferably essentially all, of the gasoline boiling range components with the condensed, dry, distillate fraction. This means that the vapor charge from the hot separator is essentially all steam and may be condensed. If the hot flash separator UMO OH receiver is somewhat elevated, it is possible to use a barometric leg to remove the water phase without a pump and a small steam jet ejector or other vacuum means to remove the small amount of non- condensibles that may be present in the UMO feed or leak into the plant. PRODUCT QUENCHING/COOLING Thermal reactor vapors are removed and preferably quenched or rapidly cooled by heat exchange with a non-reactive medium such as water. Heat exchange of UMO feed against hot thermal reactor vapor effluent is likely to cause fouling. If a refiner has a lot of spare heat exchanger capacity, or does not mind frequent shutdowns, there is no problem with using UMO reactor feed to quench or cool, by indirect heat exchange, UMO thermal reactor vapors. Preferably, boiler feed water, or other non- coking fluid, is used in the quench exchanger. The quenched thermal reactor vapors are preferably further heat exchanged against boiler feed water and/or UMO feed to produce partially condensed vapors that are charged to the hot separator. The partially cooled vapors will typically be at a temperature of 250-350°F, depending on pressure, UMO feed properties and % vaporization. This partially condensed vapor/liquid stream, consisting essentially of large amounts of steam and condensed, normally liquid, hydrocarbon product, is charged to a hot separator from which a gas oil product is recovered. Hot separator vapors may then be subjected to further heat exchange or simply cooled in a fin-fan cooler, or by heat exchange against cooling water, to produce an oily wastewater stream which may be sent to a conventional wastewater treatment plant. When steam is used as the heating fluid in the thermal reactors, and sufficient lube oil boiling range components are vaporized or lifted during thermal processing, it is possible to ensure essentially complete condensation of gasoline boiling range components along with the lube oil components. This means that the hot separator, even though running at a temperature above that of the boiling point of some gasoline components, can recover a combined, gasoline/distillate boiling range liquid hydrocarbon, which contains essentially all of the hydrocarbon in the vapor from the UMO thermal reactor. Condensing distillate product absorbs gasoline boiling range product. The hot steam fraction which is removed from the hot flash separator will, after condensation, produce only oily water with no separate hydrocarbon phase and no vapor phase. This means that it is possible to run the plant without producing any vapor stream to be treated. There will be some hydrocarbons, chlorides, sulfates, etc. in the water stream, but no more than can be tolerated by existing conventional wastewater treatment facilities. DETAILED DESCRIPTION UMO and its physical properties are well-known as the United States alone produces well over one billion gallons a year of this material. Any conventional or hereafter developed UMO process can be used ranging from the simple to the complex. Common to any system used will be the following features: • Heating the UMO sufficiently to vaporize essentially all of the water present in the UMO or added in the form of super heated steam. • Vaporizing enough detergents, surfactants or other additives so that an emulsion will form when an oil vapor/steam mixture is condensed. • Vaporizing at least 10 mole %>, preferably at least 20%, more preferably at least 30%, and most preferably at least a majority of the lubricating oil boiling range materials in the UMO. • Vaporizing enough distillate or heavy lube oil components to absorb most or all of the gasoline boiling range components during partial condensation and a majority, preferably essentially all, of lighter products produced by any thermal cracking which may occur. The condensation step will condense most, and preferably at least 90 + %, and most preferably, essentially all of the lubricating oil boiling range fractions, but without condensing any water. By this is meant that the overhead (OH) vapor from the UMO reactor is cooled sufficiently to condense most, or all, of the lube boiling range hydrocarbons but never cooled sufficiently to form liquid water. Some water may be dissolved in the liquid hydrocarbon, but no liquid water condenses. The vapor from partial condensation is then further cooled to condense most, or preferably all, of the water. Pressure is not narrowly critical. The UMO process preferably operates at a pressure ranging from 14 to 10 atmospheres, absolute, more preferably 1 to 3 atmospheres, absolute. Preferably, the UMO process operates at essentially atmospheric pressure or slightly above to permit venting of vapor streams to the atmosphere, or to a flare, if either venting or flaring is desired. The UMO recovery process preferably operates with the addition of steam, preferably more steam than UMO is present, on a molar basis. Preferably there is more steam than UMO on a weight basis. COMPUTER SIMULATION The examples that follow are based upon computer simulations, using computer programs that have proven reliable for predicting the performance of various refinery units in the past. The computer simulations are consistent with, but not directly comparable to, a limited amount of laboratory test work done with steam. As an example of the difference between the two approaches, the computer simulation predicts an end of run thermal reactor temperature a few degrees different than an actual test result. The difference is not believed significant and probably is due to the difficulty of maintaining relatively small pilot plant size equipment at a high temperature in a cold room. This computer simulation is reliable and is used to design refinery fractionation towers, etc. and a commercial scale UMO plant. The computer simulations that follow are side-by-side comparisons of different working fluids and different approaches (recycling a vapor by compressing it versus once through operation or pumped recycle vapor). In all cases, the same general process flow sequence was followed, i.e. pre-flash to remove light ends and water from UMO followed by batch vaporization in a vessel. In all cases, hot UMO vaporizer overhead vapors were heat exchanged against the vapor charged to the reactor. This reduced the temperature of the UMO vapor from 584-675°F (depending on the working fluid and other process conditions) to a temperature below 500°F. This cooled, but still essentially vapor phase, UMO overhead material was then heat exchanged against the UMO feed to the pre-flash. Fin-fan coolers then cooled and condensed the lubricating oil boiling range components in the UMO vaporizer overhead vapors, leaving most, and preferably essentially all, of the injected vapor in the vapor phase. Condensed hydrocarbon liquid was recovered in a hot separator operating at a temperature of 300°F for this exercise. Hot separator liquid was then heat exchanged against incoming, ambient temperature UMO feed to provide a measure of preheat of the UMO feed prior to heat exchange of UMO feed with hot UMO vaporizer vapors. This approach to, and amount of, heat exchange was considered a reasonable compromise for a commercial plant. Further heat savings could be achieved by adding more heat exchanger capacity, but this increased the cost and complexity of the plant. This approach did allow a fair comparison of different working fluids. In the table that follows, the following abbreviations have been used and are listed below with their accompanying definitions: ULO (or UMO) Cold Feed is the filtered, raw used motor oil feed to the plant. Pre-flash Drum Vapor refers to the overhead vapors from the pre-flash. The pre- flash preferably removes at least 80% of the water, chlorinated solvents, and gasoline boiling range components from the UMO feed. Hot ULO Charge to Reactors refers to the pre-heated feed to each vaporizing vessel. Thermal Reactor Vapor refers to the overhead vapors from each vaporizing reactor. The numbers reported are averaged over the entire heat cycle. Residue Product refers to the bottoms fraction remaining in each vaporization reactor after completion of a heat cycle. Gas Oil Rec.Napor refers to the overhead vapor fraction from the hot separator or gas oil receiver. This operates at roughly 300°F in these examples. Gas Oil Product refers to the liquid fraction removed from the hot separator. It contains essentially all of the lubricating oil boiling range components and is similar to, and may be substituted for or blended with, gas oil charge to an FCC unit. Oily Wastewater Product is the liquid water phase resulting when pre-flash overhead vapors and injected steam in the gas oil rec. vapor are cooled and condensed. S.H. Steam-to-Reactors refers to the amount of SuperHeated steam (or other working fluid as the case may be) charged to each vaporization reactor during a heat cycle. V

Claims: CLAIMS 1. A process for refining Used Motor Oil (UMO) feed comprising 0-50 wt.%> water, 0-15 wt.% gasoline and lighter, normally liquid hydrocarbon components, at least 50 wt.%> lube oil boiling range components, and a sufficient amount of vaporizable detergents and/or surface active agents (surfactants) to form an oil/water emulsion when vaporized lube oil boiling range components are condensed in the presence of steam or water comprising: a. heating and partially vaporizing said UMO feed to produce a UMO overhead vapor phase comprising essentially all of the gasoline boiling range components which may be present, at least a majority of the lubricating oil boiling range components in the UMO feed, and a sufficient amount of detergents and/or surfactants to produce an overhead vapor fraction which can be condensed to form an emulsion of oil and water; b. cooling to a temperature above the boiling point of water and partially condensing from said UMO overhead vapor at least a majority of said gasoline boiling range components, if present, at least a majority of said lubricating oil boiling range components, and at least a portion of said surfactants to produce a two phase mixture, a liquid hydrocarbon phase which is essentially free of a separate liquid water phase, and a vapor phase stream deficient in gasoline and lubricating oil; c. separating in a hot separator, maintained at a temperature above the boiling point of water, said two phase mixture into a liquid hydrocarbon phase which is removed as a product and a vapor phase; and d. cooling and condensing said vapor phase from said hot separator to produce a liquid product. 2. The process of Claim 1 wherein direct steam injection heats said UMO. 3. The process of Claim 1 wherein at least 99 mole % of said lubricating oil boiling range components in said UMO vapor phase are condensed during partial condensation and sufficient lubricating oil boiling range components are condensed to absorb at least 90 mole % of said gasoline boiling range components in said UMO vapor phase. 4. The process of Claim 3 wherein essentially all of said gasoline and diesel boiling range components are condensed into the hydrocarbon liquid phase during said partial condensation step and said vapor from said hot separator, when condensed, produces a liquid water product which contains less than 2 wt.%> hydrocarbons and at least 98 wt. % liquid water. 5. The process of Claim 4 wherein said liquid water product contains less than 1 wt.% hydrocarbons. 6. The process of Claim 1 wherein, prior to the heating step (a), said UMO feed is preheated in a pre-flash drum to a temperature above the boiling point of water to produce a pre-flash vapor comprising at least one of steam, gasoline boiling range components and chlorinated solvent dumped in said UMO, which is commingled with a vapor stream derived from overhead vapors from said UMO reactors, and a pre-flash liquid, which is charged to step (a) of the process. 7. The process of Claim 1 wherein said UMO overhead vapor is above 500°F and is quenched to a temperature below 500°F, then cooled by indirect heat exchange to a temperature of 250 to 500°F in step (b). 8. The process of Claim 1 operating at a pressure of 0.1 to 10 atmospheres, absolute. 9. The process of Claim 1 operating at 1 to 3 atmospheres, absolute. 10. A process for reprocessing a UMO and water emulsion comprising surface active agents, gasoline boiling range components, lube oil boiling range components, and surfactant additives comprising: a. heating said UMO at least in part by the direct injection of steam in an amount, and at a temperature, sufficient to vaporize essentially all of said gasoline, essentially all of said water, at least a majority of said lube boiling range components, and at least sufficient surfactants to produce a UMO reactor overhead vapor stream which will form an oil/water emulsion if cooled to the dew point to produce liquid water; b. cooling, partially condensing and separating said UMO reactor overhead vapor steam in a hot separator at a temperature and pressure sufficient to condense essentially all of said gasoline and lubricating oil boiling range components, without producing a separate liquid water phase, to produce a liquid hydrocarbon product which is essentially free of liquid water phase and a vapor product consisting essentially of steam and a minor amount of vaporized hydrocarbons; and c. condensing said vapor product to form liquid water as a product. 11. The process of Claim 10 wherein said water has less than 1 wt.% liquid hydrocarbon.

Inventors: MALONE DONALD P, MOORE HOWARD F, MALONE, DONALD, P., MOORE, HOWARD, F.
Applicants: MALONE DONALD P, MARATHON ASHLAND PETROLEUM LLC, MOORE HOWARD F, MALONE, DONALD, P., MOORE, HOWARD, F.
Application year: 2000
Main classification: C10M175
IPC codes: C10G31, C10G33, C10M175