MXPA00010112A - Thermal apparatus to eliminate ace pollutants - Google Patents

Abstract

The used oil is treated in a reactor to remove contaminants. The reactor comprises a rotating container housed inside a heating chamber. The interior of the container is indirectly heated by the conduction through the walls of the container. The container contains a permanently resident charge of coarse / non-eroding granular solids. Inside the vessel, the oil vaporizes and pyrolyses producing hydrocarbon vapor. Coke is formed as a by-product. Pollutants, such as metals and halides, are associated with coke. The coarse granular solids are purified or washed and the coke is pulverized to form fine solids. The fine solids are separated from the coarse solids and removed from the container. The hydrocarbon vapors are separated from any fine solid and directed to a steam condensation system to produce a product oil substantially free of contaminants. Solids rich in contaminants are collected for disposal

Description

THERMAL APPLIANCE TO ELIMINATE OIL POLLUTANTS FIELD OF THE INVENTION The present invention relates to a process for removing contaminants from used oil, by subjecting the oil to vaporization and pyrolysis, thereby forming the coke. The contaminants remain with the coke, which can be separated from the oil. The invention also relates to an autoclave or reactor indirectly heated, rotating, in which the process is carried out.

BACKGROUND OF THE INVENTION Processes for recycling used contaminated oil (sometimes referred to as waste oil) are known. One such process is described in U.S. Patent No. 5,271,808 issued December 21, 1993 to Shurtleff. Shurtleff describes a process in which an inclined kettle heats the waste oil, vaporizes and removes the light hydrocarbons at temperatures of approximately 650 ° F. The heavier hydrocarbons and contaminants, which account for approximately 10% of the original oil, are collected as sludge in the part REF: 25794 bottom of the kettle. The mud is drained for disposal. The lighter hydrocarbons are condensed as a product of recycled oil. However, the Shurtleff process produces an oil waste that by itself needs to be disposed of in a specialized manner. Other methods that can produce a recycled oil and a contaminant free of dry oil typically involve subjecting the waste oil to thermal pyrolysis. For example, in the North American patent No *. 5,423,891, issued to Taylor, describes a process for the gasification of solid waste. The solid heat transporters (STC) are first heated and then fed co-current with solid waste carrying hydrocarbons through an autoclave-rotary kiln. Solid waste and STCs are co-located, transferring heat. The resulting temperatures of 1200 to 1500 ° F are suitable for thermally pyrolyzing the hydrocarbons in the waste. The resulting vapors are extracted for condensation. The solids and STCs of the autoclave are discharged from the furnace for the recovery of the solids from the autoclave and the re-heating of the STCs. In the Taylor system, the STCs are circulated continuously in a material handling cycle. STCs are coarse granular solids which are heated outside the kiln and provide their heat inside the kiln. The transport of the STCs around the cycle involves considerable equipment for the handling of materials. In U.S. Patent No. 4,473,464, issued to Boyer et. al., describes a process for treating heavy crude oil. The carbonaceous solids are ground finely for a concurrent feed with the crude oil to an indirectly heated oven. The pyrolyzed hydrocarbon vapors condense. The coke and the carbonaceous solids are sieved, milled and recycled outside the kiln. The loss of heat to the solids is minimized and the crude oil is preheated to a temperature high enough to balance any loss of temperature by the solids. U.S. Patent No. 4,303,477 issued to Schmidt et al. Discloses the co-current addition of a fine-grained reagent solid to a waste material for bonding the metal and sulfur contaminants during the treatment. Reactive solids such as lime having a grain size typically less than 1 mm, and the waste is thermally pyrolyzed as it progresses through an indirectly heated, rotary furnace. The solids pass once through the furnace, the reactive solids are consumed in the process. Some of the prior art processes described above involve significant challenges in the handling of the material and the recycling and transportation of large masses of hot coarse solids. Other processes, which do not recycle hot solids, involve the rejection of a portion of the oil waste or the irreversible consumption of a catalyst. There is a need, therefore, for a simplified process to separate contaminants from used oil. The object of the present invention is to provide such a process.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a simple apparatus and process for recycling oil from a contaminated, used oil feed. In general, the process comprises feeding the used oil through a feed line to a rotating thermal reactor where the oil is pyrolysed to produce hydrocarbon vapor and coke. The pollutants are associated with coke. Steam and solids in the form of coke are removed from the reactor. The steam condenses to produce an oil product free of contaminants and the coke-shaped solids, rich in contaminants, are collected for disposal, possibly as feed for a cement kiln. The equipment used includes a reactor comprising a rotating vessel housed in a heating chamber, means for feeding the oil used in the rotating vessel, and an oil recovery system, comprising a steam extraction tube, a cyclone for the Solids removal and steam condensation equipment. More particularly, the rotating container is indirectly heated so that its internal surfaces are heated sufficiently to vaporize and pyrolyze the used oil. The used oil is introduced into the chamber of the vessel where it is vaporized and pyrolysed, forming hydrocarbon vapor and coke. Metals and other pollutants are associated with coke. A load of coarse granular solids is provided within the container chamber. As the container gilts, the granular solids clean the internal surface of the container and pulverize the coke into fine solids. The fine solids may include solids introduced with the feed oil. The steam is extracted from the chamber of the vessel through an axial pipe. The fine solids are separated within the container chamber from the coarse granular solids for the removal of the container, preferably using a gutter or spiral conduit. The duct has a spiral shape from an entrance of the classifier or screen on the circumference of the container to a discharge outlet on the container axis. The duct classifier excludes coarse solids and collects only fine solids. The fine solids are transported out of the container to be discarded. Fine solids can also be elutriated with vapors. Any of the fine solids associated with the vapors are separated. The free solids vapors are then condensed to produce an oil product. The fine solids rich in contaminants are collected for disposal. Only a small portion of the feed oil is converted to coke, the rest is recovered as an oil product substantially free of contaminants.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic flow chart of a polluted oil thermal treatment reactor system, heating chamber and hydrocarbon vapor condensation system, according to one embodiment of the present invention; Figure 2 is a cross section of the heating chamber, reactor, support and rotary drive equipment according to the present invention; Fig. 3 is a cross-sectional view of the reactor vessel along the line III-III of Fig. 2, showing in particular the gutter or conduit for removing fine solids; and Fig. 4 is a sectional view. cross section of the second end of the reactor vessel, which characterizes the fine solids removal conduit and the screw conveyor.

DESCRIPTION OF THE PREFERRED MODALITY Referring to Figure 1, the process is described in a general form. The reactor 1 is provided to thermally treat the contaminated oil 2 used. The reactor 1 is housed inside a heating chamber 3 formed by a housing 3a. The heat is generated in chamber 3 to heat reactor 1. Feeding oil 2, contaminated with metals and one or both of water and solids, is fed to reactor 1 for the separation of the contaminant from the oil component. Inside the reactor 1: the feed oil is vaporized and pyrolysed, producing a stream 4 of hydrocarbon vapor, which may contain steam: the coke 5 is formed as a by-product; Metals and solid contaminants are associated with coke 5; and the coke 5 is separated from the vapors 4 of the hydrocarbons. The hydrocarbon vapors 4 leave the chamber 3 and are transported to a steam condensation system 6. Here the hydrocarbon vapor 4 is condensed as a product 7 of oil substantially free of contaminants, which is suitable for providing feed charges in refineries. The coke 5 is removed from the chamber 3 of the reactor and accumulated or stored for use as fuel. In more detail, the steam condensation system 6 comprises a cyclone 10 for separating the fine solids 11, including coke, from the vapors 4 of the hot reaction zone. The separated solids 11 are discharged to be discarded. The separated steam 12 proceeds to a steam treatment tower 13 (purification tower), a direct contact cooling tower 14 (cooling tower), a heat exchanger 15 and inside a drum 16 of vapors projecting from the upper part. In the scrubber tower 13, the reflux 17 of light oil from the cooling tower 14 and the recirculated scrubbing oil 18 causes a heavy fraction of the hydrocarbon vapor 12 to condense (forming the oil 18 of the scrubber tower), capturing any solid not removed from the cyclone 10. The heavy oil 18 from the scrubber tower is recirculated to the reactor 1 by co-mixing with the feed oil 2 prior to treatment. Steam 19 not condensed from the scrubber tower 13 is directed towards the cooling tower 14 where the light oil 20 condensed from the drum 16 of light vapors and the oil 17 from the scrubber tower, recirculated are reflowed for the condensation of most of the vapors 19. The oil 17 of the treatment tower is passed through a heat exchanger 21 to preheat the feed oil 2. A non-condensed vapor 22 is directed towards the drum 16 of light vapors for the separation of water from the lighter fraction of the condensed oil 20 and from the non-condensable exit gases 23. An outlet gas compressor 24 provides the force necessary to extract steam 4 from the reactor 1. Any separated water is discharged as an aqueous product. The oil 20 of the drum of light exhaust gas vapors and the oil 17 of the scrubber tower are combined to form the oil 7 of the product. More specifically, and referring to Figures 2 to 4, the reactor 1 comprises a cylindrical container 30 having a first end 31 and a second end 32. The cylinders 33, 34 are structurally connected to the container 30 with sections 35, 36 of conical transition and extend axially from the first and second ends 31 and 32 respectively. The container 30 is rotatably supported inside the heating chamber 3. An annular space 37 is formed between the housing 3a of the chamber and the container 30. Returning briefly to the scheme shown in figure 1, the burner 38 discharges the combustion gas 39 heated for circulation through the annular space 37. The gases 40 of combustion of the chimney in the upper part of the chamber 3 causes spent combustion gases 39 to exit. The first and second end cylinders 33, 34 extend through rotary seals 41 formed in the side walls 42 of the housing 3 of the chamber. The clamping rings 43 are circumferentially mounted to the cylinders 33, 34 positioned outside the side walls 42 of the chamber housing. The clamping rings and the container are supported on rolls 44. The inner part of the container 30 is sealed at its first and second ends 31, 32 by first and second panels 45, 46 respectively forming a reaction zone 50. A tube of steam 53 extends through the axis of the second panel 46. The steam pipe 53 connects the reaction zone 50 and the condensation system 6. A line 51 of feed oil extends through the second end panel 46. The line 51 distributes and discharges the feed oil 2 into the reaction zone 50. The container 30 contains surfaces for improving the internal heat transfer in the form of rings or fins 54 extending radially and inwardly. Referring now to figures 3 and 4, the reaction zone 50 is charged with coarse granular solids which are not • eroded and are permanent residents within the container 30. The coarse granular solids form a bed 55 in the lower part of the chamber 50 of the container. At the second end of the container 30 there is a gutter or conduit 56 for removing fines. The conduit 56 has a first portion 57 extending circumferentially towards a second spiral portion 58. The conduit 56 forms a passage 59 for the transport of fine solids towards the steam pipe 53. The duct extends in a manner opposite to the direction of rotation, from the first portion 57 to the second portion 58. Thus, the fine solids enter the first portion 57 of the duct 56 and advance through the second portion 58 according to the container 30 tour. The first portion 57 of the duct rests against the inner circumference of the container 30 and extends circumferentially by approximately 120 °. The first portion 57 of the duct comprises side walls 60 conveniently formed by adjacent fins 54, and a lower portion formed by the wall of the container 30 at its outer radius. The inner radius or upper part of the first portion 57 is fitted with a screen 61. The openings 61 of the screens are small enough to exclude the coarse granular solids to thereby allow the passage of the finer solids. The second portion 58 of the conduit or gutter is connected to the end of the first portion 57 and comprises a spiral tube 62, which has a spiral shape inwardly from the circumference of the container towards the central line of the container. The spiral tube 62 rotates through approximately 180 ° to direct the fine solids toward the end of the steam tube 53. A screw conveyor 63 remains along the bottom of the steam tube and extends through it. up to a point outside of the heating chamber 3. An actuator 64 rotates the screw conveyor 63. Referring again to Figure 1, in operation, the container 30 is rotated about its axis. The radiant and conductive heat from the burner gases 39 of the burner heat the annular part 37 and the walls of the container 30. The rotary seals 41 are cooled by a flow of combustion air (not shown). The heat is transferred indirectly by conduction through the walls of the vessel 30 to the reaction zone 50. The heat is transferred from the walls and fins of the vessel 54 to the granular solids to maintain its temperature at approximately 800-1300 ° F, which is high enough for the feed oil to vaporize and pyrolize. Typically, the corresponding range of temperatures of the heating chamber is approximately 1025-1450 ° F. The contaminated oil 2 is fed through line 51 to the container 30. If liquid water is fed into the reaction zone 50, it will evaporate instantaneously and can alter the balance of the sub-atmospheric pressure. The preheating of the oil 2 via the exchanger 21 vaporizes the water to steam and helps to conserve the heat. Small amounts of water (say less than about 1% by weight) present in the feed oil 2 may not require heating. As the container 30 rotates, the granular solids form a bed 55 that continuously carries the contents of the bed to contact it with the walls 30 and the fins 54 of the container, washing the surfaces that come into contact. The granular solids absorb the heat as they come into contact with the container 30. In a first embodiment, the feed oil 2 is directed to the contact with the cylindrical wall of the reactor vessel just before it turns under the bed "-55. The thermal mass of the container 30 provides sufficient heating load to vaporize and instantaneously pyrolize the oil in a substantial manner The hydrocarbon vapor 4 is produced and a by-product 5 of solid coke is formed on the surfaces of the cylindrical walls of the container 30 and the fins 54.

Contaminants, such as metals and solids, remain substantially associated with coke. In a second embodiment, the oil is directed to contact the bed 55 which is maintained at pyrolysis temperatures through the transfer of conductive heat to the wall. The bed 55 is required to provide the thermal load for pyrolyzing the oil. The wall of the container 30 is maintained at higher temperatures than in the first mode as required to maintain sufficient temperature of the granular solids in the bed 55. In both embodiments, the bed of granular solids washes the walls and fins of the container. The contaminant-rich solids and coke, which have been associated with the feed oil, are washed and pulverized into fine solids that are free from the walls and coarse granular solids. The steam 4 produced is extracted through the steam pipe 53. The velocity of the steam leaving the reactor vessel will elutriate some of the fine solids 5. The elutriated fine solids 5 leave the steam pipe 53 and are passed through the steam. cyclone 10 for the separation of solids 5 from steam stream 4.

As described above, the steam stream 4 is passed through the condensation system 6, resulting in a liquid product 7 and a stream 23 of non-condensable exhaust gas. The liquid product 7 is sufficiently free of contaminants to be acceptable as a refinery feed. The exhaust gases 23 can be burned or recycled as fuel for the burners 38 of the heating chamber. The operation of the system is illustrated in the following example: EXAMPLE 1 A cylindrical reactor vessel 30 feet in diameter and 8 feet in length was constructed of 1/2 inch thick stainless steel. A plurality of fins 54 of 4 inches in height and 1/2 inches in thickness were installed with a spacing of 8 inches. Two cylinders of 4 feet in diameter form the first and second ends 31, 32. A clamping ring 43 was located at each cylindrical end and supported or rotatably supported on solid rubber rollers mounted on moveable beams. A toothed wheel at the end furthest from the first end cylinder and the chain actuator allowed the container to rotate.

The chute 56 comprised a first portion 57 of rectangular section of 8 by 4 inches and a second portion 58 of spiral tube of diameter of 4 inches. The channel reached a rotation of approximately 330 °. In a first test, the container was loaded with 8500 pounds of inert ceramic spheres available under the trademark Denstone 2000, from Norton Chemical Process Products Corp., Akron, OH. As can be seen from figure 3, this produced a deep bed, the rope of which was approximately 120 °. The container was rotated at 3 to 4 rpm. The feed oil was directed to be distributed along the moving bed. Two burners 38 provided approximately 2 million BTU / hr to maintain the heating chamber 3 at approximately 1380 ° F. The resulting heat transfer through the vessel wall raised the temperature of the ceramic spheres to approximately 805 ° F. 185 barrels per day of contaminated lubricating oil API 28 ° was preheated to 480 ° F before being discharged into reactor 1. The oil contained approximately 0.6% water. The reactor was maintained with a slight vacuum of -1 to -2 inches from a column of water.

The steam was withdrawn from the reaction zone 50 and condensed to produce 175 barrels / day of the 32 ° API product oil. The product oil was mainly cooling oil (95 to 98%) with a small contribution (2 to 5%) from the output steam drum oil. The oil from the bottom of the steam treatment tower was recycled to the reactor 1 to approximately 18.5 barrels / day (note that the fraction of solids for this test was approximately 0.5% and is expected to be higher in other tests). The total output of the non-condensable exhaust gases was 1912 kg / day. An additional amount of 147 kg / day was separated and produced from the condensation system. Coke was produced that contained contaminants at a rate of 445 kg / day. In summary: TABLE 1 Feeding speed 185 bbl / day 28 ° API Recycling of the treatment tower 18.5bbl / day (<0.5% solids) Product oil 175 bbl / day 32 ° API Exit gas 1912 kg / day Water 147 kg / day Coke 445 kg / day An analysis of the feed oil and the product oil confirmed a 99.84% elimination of metals This was achieved with only a 5.4% reduction in the original volume of the feed oil, showing little degradation of the feed oil. The resulting oil was a slightly lighter product, reducing its severity from 28 to 32 API. Total halides were also reduced by 80%. A more detailed analysis is shown in Table 2.

TABLE 2 Parameter Aceite de Aceite de Aceite Coque Aliment: ation Enninuration Depurador μg / g μg / g μg / g μg / g Aluminum 9.4 0 4.1 1100 Barium 5.6 0 2.1 230 Beryllium 0 0 0 0 Calcium 870 0 95 51700 Cadmium 0.7 0 0.2 41 Cobalt 0.04 0 0.04 26 Chrome 1.8 0 0.29 130 Copper 46 0.02 5.7 2400 TABLE 2 (continued) Parameter Aceite de Aceite de Aceite Coque Aliment: ation E nnnumbering Scrubber μg / g μg / g μg / g μq / q Iron 120 0.12 21 8400 Lead 61 0 27 3000 Magnesium 390 0 45 23700 Manganese 68 0.02 8.8 4000 Molybdenum 12 0 1.5 720 Nickel 0.95 0 0.34 110.

Potassium 130 0 14 4000 Silver 0 0 0 0 Sodium 380 1.9 51 21000 Strontium 1.6 0 0.23 97 Titanium 0.72 0 0.32 69 Vanadium 0 0 0 0 Zinc 880 0.27 170 51400 Zirconium 0.02 0 0 3 Boron 11 1.1 0.78 130 Phosphorus 820 2.8 160 50800 Total Metals 3808.8 6.2 Halides 490 98.5 Assuming no metals were reported in the oil at the top of the tower, the reduction of the metals from the feed oil to the product oil was determined as (3808.8 - 6.2) /3808.8 = 99.8 %. The metals were reported substantially in the coke. It was found that the halide reduction was: (490-98.5) / 490 = 80%. The ceramic spheres were not entirely successful in washing all the coke from the walls of the reactor vessel. Thus, the majority of the fine coke was produced via elutriation and not through the gutter or spiral duct whose screen is covered by the accumulation of coke.

EXAMPLE II In a second test run performed on the same equipment, the ceramic spheres were replaced with a packing load or spring-shaped steel particles, with a thickness of 1/2 inch, with a diameter of 1 to 2 inches . Also shown in Figure 3, about 3300 pounds of particles or packing formed a level of surface bed in the vessel having a bed string angle of about 75 °.

The feed oil was directed to directly impregnate the wall of the reactor vessel. Load ^^^ j ^^^^ l & ^^^ thermal to vaporize the oil was provided by the wall itself and not by the steel packing. Thus, the wall did not need to conduct a large amount of heat to the particles through the conduction and the temperature of the wall was correspondingly lower. The steel particles successfully washed the coke from the walls of the vessel, sufficient to prevent plugging of the duct screen or channel and allow a sustainable extraction of the coke from the reaction zone as it is produced. A comparison of the temperature conditions of the process in runs in both the ceramic spheres and in the steel packaging or particles are as shown in Table 3 (rounded to the nearest 5 ° F).

TABLE 3 (° F) EXAMPLE I EXAMPLE II Spheres Particles Reactor bed 805 840 Wall of reactor vessel 1290 930 Heating chamber 1380 1020 Feeding oil 480 480 Steam scrubber 700 700 Cooler 465 465 Drum of light vapors partly sup. 85 85 The previous process encompasses the following advantages: * -. it is a continuous process with a continuous elimination of contaminants that contain coke; ß eliminates contaminants with minimal degradation of the feed oil; * There is a minimum requirement for material handling equipment, which comprises only a rotating container, a screw conveyor and a cyclone; B avoids the use of consumables; and ß simplicity of operation.

It is noted that in relation to this date, the best method described by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following: ^^ a ^

Claims (7)

1. An apparatus for removing contaminants from the oil, characterized in that it comprises: a rotating container having a circumferential wall and side walls forming an internal reaction zone; a load of coarse solids that do not wear out, forming a bed within the reaction zone; means for heating the exterior of the container to indirectly heat the reaction zone and the bed of coarse granular solids by conduction through the walls of the container; means to feed the contaminated oil to the reaction zone so that the oil vaporizes and pyrolyzes, forming hydrocarbon vapors and depositing coke, so that substantially all pollutants are associated with coke, the bed of coarse granular solids it acts to purify the coke deposits and grinds the coke and forms fine solids; ^^ medium to remove hydrocarbon vapors from the reaction zone; and means for separating the fine solids from the bed of coarse solids and removing the fine solids from the reaction zone separately from the hydrocarbon vapors to produce a solid product rich in contaminants; and condensation medium to condense the hydrocarbon vapors and produce a product oil substantially free of contaminants.

2. The apparatus in accordance with the claim 1, characterized in that the means for indirectly heating the reaction zone comprises: a housing forming a heating chamber surrounding the container and forming an annular space between them; burner means for circulating the combustion gases in the annular space to transfer heat to the container; and a column of exhaust gases to conduct the combustion gases from the heating chamber.

3. The apparatus in accordance with the claim 2, characterized in that: the means for feeding the polluting oil in the reaction zone comprises a conduit extending through an end wall of the container and having a means for distributing the oil within the zone; and means for removing hydrocarbon vapors from the reaction zone, comprising a vapor tube extending along the axis of the container and projecting through an end wall of the container.

4. The apparatus according to claim 3, characterized in that it also comprises a cyclone placed in line with the steam tube to separate the fine solids that accompany the hydrocarbon vapors.

5. The apparatus according to claim 1, characterized in that the means for separating the fine solids from the coarse granular solids and eliminating them from the reaction zone comprises: a conduit having an entrance of solids adjacent to the periphery of the container wall, output of solids adjacent to the axis of the container and at least two portions of transportation of solids that extend between them; the first portion of solid transport of the conduit having first and second ends, both ends lying adjacent to the circumference of the container, wherein the inner radius of the conduit contains a sieve to exclude coarse granular solids and admit only fine solids in the conduit; the second portion of transportation of the conduit having first and second ends, the first end is connected to the second end of the first transportation portion, the second transportation portion forms a spiral radially inward to be discharged at its second end toward the tube of the Steam; and means associated with the vapor tube to transport the fine solids out of the reaction zone.

6. The apparatus according to claim 5, characterized in that the means associated with the steam pipe-for transporting fine solids out of the reaction zone comprises a screw conveyor extending along the bottom of the steam pipe. and a discharge separator is located external to the heating chamber.

7. The apparatus according to claim 1, characterized in that the bed of coarse granular solids comprises a plurality of steel packing articles.