MXPA01010723A - Condensation and recovery of oil from pyrolysis gas - Google Patents

Abstract

A system and process for the recovery of oil from the pyrolysis of material containing hydrocarbons such as shredded vehicle tires. The system utilizes a pair of sequentially positioned packed towers to recover at least 95%of the oil contained in the pyrolysis gases. The first packed tower operates above the dew point of the water vapor in the pyrolysis gases to insure that no water is condensed and obtain a primary oil fraction having oil with a high flash point of about 60°C or greater and a primary vapor fraction containing additional oils, fuelgases and water vapor. The primary vapor fraction is fed to the second packed tower which operates below the dew point of the water vapor to condense the water and oil having a low flash point of 34°C or below, and provide a secondary vapor fraction containing valuable fuel gases.

Description

CONDENSATION AND RECOVERY OF PETROLEUM FROM PIROLYSIS GAS BACKGROUND OF THE INVENTION The present invention relates in general to the recovery of useful products from the pyrolysis of hydrocarbon-containing material. More specifically, the present invention relates to the recovery of petroleum or liquid fuel from gases formed when pneumatic tires are pyrolyzed. As the supply of fill space or available storage areas decreases, the environmentally safe disposal of used vehicle tires detects a growing problem. Only in the U.S. More than 280 million vehicle tires are discarded and shipped to landfills every year. Although some of the used tires are recycled for use in pavement and others are burned as boiler fuel, more than 80% of used vehicle tires end up being deposited in landfills. Tires from discarded vehicles in landfills have been recognized as a significant waste of a recyclable source. For many years, it has been known that used vehicle tires can be recycled by pyrolysis to obtain valuable by-products that can be sold and reused. Pyrolysis, generally speaking, is a thermal decomposition or distillation of a substance, especially one that contains hydrocarbons. In the case of used vehicle tires, this process is carried out in the absence of oxygen and at temperatures generally between 500 and 800 ° C.

The process of decomposing used tires by pyrolysis allows the recovery of substantial quantities of oil, gas, carbon black and steel. Many different processes have been designed to recover these valuable products produced by pyrolysis, and each of the various known techniques for recovering these products has its own unique and difficult problems.

For example, the recovery of oil formed when tires are pyrolyzed, has always been a challenge. Petroleum is typically produced by the condensation of pyrolysis gases produced in the pyrolysis reactor, but these gases typically also use particulate matter, primarily carbon dust and glass fibers, which are also displaced from waste tires when pyrolysed. . This particulate matter accumulates in the fixtures, vents and flame controllers, which eventually obstruct the passages. In the past, particulate matter in the pyrolysis exhaust gas has been removed in a cyclone. However, if the oil is cooled prematurely and begins to condense in the cyclone, the condensed oil will provide a surface that will adhere to the particulate matter. Not only can this result in clogging in the cyclone, but it can also result in poor separation performance for the cyclone, as it causes undesirable changes to inherent cyclone design parameters. In addition, if a packed bed condenser is used in the system, particulate matter can embed the packing, thereby blocking the open area and causing an intolerable increase in pressure drop across the bed. Another difficulty when recovering oil is caused by the fact that in addition to the oil vapors generated in the pyrolysis reactor, steam is also dragged with the petroleum vapor. It is often the case with pyrolysis oil, which has a specific gravity close to that of water. As a result, if water and this oil are condensed together, they can form an emulsion that is difficult to separate. COMPENDIUM OF THE INVENTION The present invention is a process for the recovery of petroleum, from the pyrolysis of hydrocarbon-containing material such as tires of shredded vehicles. The process of the present invention not only recovers substantial amounts of pyrolysis oil, but also solves the previously noted problems that occur in the prior art. The distribution of carbon black, petroleum and gases recovered from the pyrolysis of waste tires is influenced by the temperature at which pyrolysis occurs. It is well known that at higher temperatures of pyrolysis, the generation of gases against the generation of oil is favored. The present description considers a tire decomposition in 32.4% carbon black, 12% steel and 55.6% petroleum and non-condensable gases. Of the non-condensable gases and oil, approximately 50% goes to liquid petroleum, and the remaining 50% are non-condensable gases. Of the liquid petroleum, approximately 80% is collected in the first capacitor or primary capacitor and approximately 20% in the second capacitor or secondary capacitor. Hot gases from a pyrolysis process, for example a rotary kiln processing of used tires, are taken to a first petroleum condenser. The first oil condenser comprises a packed tower with countercurrent gas / liquid flow. Various types of packaging material are used, but the preferred packaging is the Pall ring type which has a high surface area and high void fraction. The condensed oil is sprayed onto the packed bed and used to cool, condense and coalesce the vapor in the incoming gas stream. By controlling the temperature and flow rate of the cooled oil, and the size of the packed tower, the temperature of the gas leaving the tower can be controlled. Preferably, the temperature of the gas leaving the tower should be above the dew point of the water vapor in the gas stream. A temperature of 100 to 105 ° C is used to ensure that water does not condense on the first petroleum condenser. By preventing condensation of water in the first condenser, an sirable oil / water emulsion which is difficult to separate is not obtained. To avoid embedding the packing in the first oil condenser, a cold oil spray is also directed on the rside of the package. In this way, the particulate matter in the incoming gas stream will adhere to the lower surface of the gasket coated with the oil spray directed upwards. In addition, the spray on the rside of the package prevents the particulate matter from remaining in the packaging because it is washed with drag as the spray from the top of the package passes through the packing and is collected with the oil in the collector of the first capacitor. The oil recovered in the collector of the first condenser is directed from the collector through a wire mesh duplex filter. The filter collects the largest particulate matter contained in the oil and removes it from the process. This prevents particulate matter from clogging the oil spray nozzles. After the filter, a pump moves the oil through a water-cooled liquid-to-liquid heat exchanger. The coldest oil returns to the first condenser where it is used to spray on the upper side and lower side of the packed bed as previously described. A portion of oil, equal to that of the condenser in the tower, is removed and the petroleum product from the process. The spray nozzles used in the condenser are single fluid atomization nozzles that contain relatively large nozzle openings, ie .476 cm (3/16") or larger to help prevent nozzle clogging. of oil, the gases pass to a second oil condenser.This second condenser operates in a similar fashion to the first condenser except that the gases are cooled below the dew point of the water contained in the incoming gas stream. Both water and oil are collected in the collector of this condenser., the oil collected in the collector of the second condenser typically has a specific gravity of .90 to .95. Since oil is significantly less dense than the water collected there, the separation of oil and water phases can be easily achieved. The second condenser also only requires an oil spray on the upper side of the package and does not require a directed oil spray on the underside of the package since a large majority of the particulate matter is removed in the first stage. Again, a portion of the oil equal to the condensate in the tower is removed as an oil product from the process. As a result, the process of the present invention allows the recovery of more than 95% of oil trapped in the initial hot exhaust stream of the pyrolysis reactor. This petroleum can be constituted as much by a petroleum of pyrolysis of high point of boiling (point of inflammation of 60 ° C or greater) as well as a petroleum of pyrolysis of low boiling point (point of inflammation of 34 ° C or lower). In addition, a gas from the second condenser is produced which is readily usable as a combustion gas having minimal amounts of condensable vapors. BRIEF DESCRIPTION OF THE DIVERSE VIEWS OF THE DRAWING The drawings illustrate the best mode currently contemplated for carrying out the invention. In the drawings: Figure 1 is a schematic illustration of a typical pyrolysis system, to produce suitable materials such as oil, gas, lower quality coke, and steel wire, from shredded vehicle tires; and Figure 2 is a schematic illustration of the oil recovery system of the present invention indicated for condensing and collecting oil from the severe pyrolysis escape produced in the system of Figure 1. DETAILED DESCRIPTION OF THE INVENTION Figure 1 generally illustrates the system of pyrolysis 10 that provides a source of pyrolysis gas used in the present invention. The pyrolysis system 10 operates to receive a supply of shredded vehicle tires, and through pyrolysis, converts shredded vehicle tires into suitable materials, such as oil, gas, steel wire and lower quality coke containing carbon black. . The pyrolysis system 10 generally includes a feed section 12, a pyrolysis section or reactor 14 and a separation section 16. The vehicle tire parts are initially fed into the feed section 12 which in turn feeds the tire parts of the vehicle to the pyrolysis section 14. As the vehicle tire parts move through the pyrolysis section 14 hydrocarbons contained in the vehicle tire parts move as exhaust gases. Specifically, the gases are removed from the pyrolysis section 14 by a gas discharge pipe 18 having an inlet gate 20 positioned within the pyrolysis section. 14. The remaining portions of the vehicle tires after pyrolysis are suitable materials such as lower quality coke and steel wire. Upon leaving the pyrolysis section 14, the lower quality coke and steel wire are fed into the separation section 16, where they are separated into different final products. After separation, these convenient final products can then be processed downstream of the pyrolysis system 10, according to known practices and eventually sold or reused. Now with reference to Figure 1, the vehicle tire parts are initially fed into a hopper 22 as illustrated by arrow 24. Vehicle tire parts can be formed upstream of the hopper 22 by conventional shredding techniques (not shown) or can be shipped from a remote tire shredding facility.

Typically, used vehicle tires are shredded into individual pieces each having an approximate maximum size of 10.16 cm (4"). The vehicle tire parts are fed by conventional transportation techniques to the feed end of the hopper 22. A pair of discharge valves 26 are placed inside the hopper 22 and function as an air lock, since the pyrolysis reaction is carried out within the pyrolysis section 14 must occur in the absence of air. through discharge valves 26, the pieces of waste tires fall into the supply chamber 28. Subsequently, the tire parts are fed by a rotating cylinder 30 which contains an inner blade type screw 32 which acts as an Archimedes screw for transporting the supply of vehicle tire parts from chamber 28 to the pyrolysis section 14. The pyrolysis section 14 gene it includes a rotary kiln 34 that extends through an insulated furnace 36. The rotary furnace 34 is rotatable with respect to its longitudinal axis and is inclined in such a way that the feed end is on the discharge end, resulting in a flow by gravity of the vehicle tire parts between its feed end and its discharge end, as is conventional. The furnace 36 surrounds the rotary kiln 34 and includes a plurality of individual burner structures (not shown), which operate to heat the rotary kiln 34 as is conventional. Furnace 34 is generally heated to temperatures between 500 ° C and 800 ° C. The high operating temperature of the furnace 34 causes the vehicle tire parts to heat up rapidly, which promotes cracking and evaporates the light hydrocarbon fractions contained in the vehicle tire parts. The evaporated hydrocarbon fractions are released as exhaust gases into the open interior of the rotary kiln 34 and then out through the gas discharge pipe 18. The discharge end of the rotary kiln 34 extends from the furnace 36 and enters to the separation section 16 as illustrated in Figure 1. The discharge end of the furnace 34 includes a rotating screen 38 operating to separate the lower quality coke material from the steel wire leaving the section pyrolysis 14. Thromel 38 includes grooves (not shown) sized to allow lower quality coke to pass, while they are small enough to prevent a santial amount of this steel wire from passing. The lower quality coke separated from the product stream by the trommel 38 passes through the slots in the trommel 38 and in the lower quality coke channel 40 and then in the collection hopper 42. The lower quality coke separated within of the hopper 42 can then be processed downstream by conventional techniques to produce a commercial grade carbon black that can be used for various known functions. The steel wire remaining in the product stream of the trommel 38 then passes through the wire channel 44 and into a wire collection hopper 46. The steel wire collected in the hopper 46 is then processed downstream by conventional techniques to produce convenient products. Now with reference to Figure 2, the gas discharge pipe 18 extends from the interior of the rotary kiln 34, and is typically connected to a source of negative pressure (not shown). The source of negative pressure acts to direct the exhaust gases expelled out of the interior of the furnace 33. These exhausted gases contain valuable gases of hydrocarbon fuels, condensable oil, small amounts of vapor (water vapor) and trapped solid particulate matter. The gases removed by the discharge pipe 18 are then subjected to downstream processing by the recovery system illustrated in FIG.

Figure 2. As shown, the gas discharge pipe 18 feeds the hot gases into a first oil or primary condenser 48. The oil condenser 48 is in the form of a cylindrical tower having an upper end 50, a collector or lower end 52 and a central portion filled with conventional packing 54. The packing 54 is in the form of discrete particles, and in particular they are in the form of Pall rings, which have a high surface area and high void fraction. The package 54 is held within the condenser 48 by a sieve 56 as is conventional. The discharge pipe 18 feeds the hot pyrolysis gases into the lower section of the condenser 48 below the sieve 56 and over the collector 52. These hot gases enter the condenser 48 at a temperature between about 400 ° C to 800 ° C. they rise through the package 54, are cooled and then exit with the upper end 50 of the condenser 48 at a temperature between about 100 and 105 ° C on the line 58. Relatively cold oil is used to cool the hot gases passing through the packing 54. This is achieved by spraying cooled oil on top of the package 54 by line 60 and nozzle 62. In this way it is used to cool a countercurrent gas / liquid stream, to condense and coalesce the vapor into the incoming gas stream passing up through the packing 54. The tower 48 separates the incoming pyrolysis gases into a primary oil fraction containing condensed oil and mate particle gas, and a primary steam fraction containing petroleum, hydrocarbon fuel gases and water vapor. By controlling the temperature and flow rate of cooled oil and the size of the packed tower 48, the temperature of the gas leaving the condenser 48 can be controlled. Preferably, it is desired to control this temperature so that it is above the dew point of water vapor in the gas stream. In this way, a temperature of about 100 ° C to 105 ° C is preferred to ensure that no water condenses in the condenser 48. By preventing condensation of water in the first condenser 48, a petroleum / water mixture is not obtained. undesirable in the material collected in the collector 52. Since the condenser 48 operates at a temperature above the dew point of water vapor in the gas stream in the pipe 18, the oil that is collected in the collector 52 has a point of relatively high inflammation and can be considered as a high-boiling pyrolysis oil, i.e. having a flash point of about 60 ° C to 80 ° C or higher and typically being between about 60 ° C and about 90 ° C , and preferably approximately 60 ° C. To avoid packing fouling 54, a cold oil spray is also directed upwards to the underside of the gasket 54 by line 64 and nozzle 66. As the particulate matter in the hot gas will adhere to the first contacting surface , the oil spray from the lower side causes this material to adhere to the sieve 56 and / or the lower layer of the pack 54. Then, the oil spray from the upper side prevents this particulate matter from remaining in or permanently adhering to the packing 54 and / or sieve 56. In contrast, the particulate matter is stripped off as the oil sprayed on top of the package 54 circulates through the package 54 and is collected in the collector 52. In this way, the The oil in the collector 52 includes material particles as well as the high boiling pyrolysis oil having a flash point above 60 ° C. The oil collected in the collector 52 of the condenser 48 is withdrawn from the collector 52 via line 57 by the pump 68 through a filter 70, which collects larger particulate matter contained in the oil and removes them from the system in order to avoid that the particulate matter seals the oil spray nozzles 62 and 66. Preferably, the filter 70 is a large mesh duplex filter. After the filter 70, the pump 68 moves the oil through a water-cooled liquid-to-liquid heat exchanger 72. The cooled oil is then recycled or returned to the condenser 48 by lines 60 and 64 where it is again sprayed on the upper side and lower side of packing 54. A portion of the oil, equal to the condensate in condenser 48, is removed by line 74, and is a usable final product of the process. The oil line 58 emerging from the upper end 50 of the condenser 48 contains oil having a flash point of about 60 ° C or higher as noted above. Gases leaving condenser 48 on line 58 are then fed to a second condenser or secondary condenser 76. Condenser 76 is similar to condenser 48, and is a packed tower that is cylindrical in shape having an upper end 78 and one end bottom or collector 80.

The condenser 76 is also filled with ring gaskets 82 in its central section supported by a screen 84. The condenser 76 operates in a similar fashion to the condenser 48 except that the gases entering its lower section at about 105 ° C below the packing 82, they cool below the point of water spray. In this way, both water and oil are collected in the collector 80 of the condenser 76 as a secondary oil fraction. However, the oil collected in the collector 80 is of the low boiling point type, ie it has a flash point of about 34 ° C or lower and is typically between about 34 ° C to about 24 ° C and preferably about 30 ° C. In this way, this oil typically has a specific gravity of 0.90 to 0.95. Since this oil is significantly less dense than water, the separation of the oil and water phases and the material collected in the collector 80 can be easily achieved.

As illustrated in Figure 2, the oil-water mixture collected in the manifold 80, is extracted from the manifold 80 by a pump 86 and the line 88 through a water-cooled liquid-liquid heat exchanger 90. The cooled oil returns or is recycled to condenser 76 by line 92, where it is sprayed on top of package 82 by nozzle 94. This oil is used to cool incoming gases from about 105 ° C to about 49 ° C, so such that the gases leaving the upper end 78 of the condenser 76 in the line 96, contain less than 5% vapors of condensable gases. In other words, 95% or greater of the oil contained in the gas discharge pipe 18, has been removed and recovered by the system illustrated in Figure 2. The gases exiting the upper end 78 of the tower 76, are referred to herein as the secondary vapor fraction and contain primarily hydrocarbon combustion gases and some condensed petroleum nebulization trapped there. A mist separator 100 located on line 96, will remove most of the condensed oil mist trapped in the gas stream passing through the discharge line 102. The gas in line 104 leaving the mist separator 100, then It can be transported for storage or burned as fuel. Finally, a portion of the oil that is circulated between the collector 80 and in packing 82 equal to that condensed in the tower 76, is removed by line 98 and recovered as a final oil product of the process. As noted above, the material in line 98 contains both water and oil, which are then processed downstream by conventional techniques to separate water and oil. This oil, however, is what is considered low-boiling oil, that is, one that has a flash point of about 34 ° C or less. In this way, a system has been illustrated and described, which allows the recovery of usable products from the pyrolysis of used vehicle tires. In particular, a system has been described that avoids the disadvantages of previous systems. By controlling the temperature and size of capacitors 48 and 76, and the costs of cooling oil flow, the temperature of the gas leaving the condensers can be controlled, as well as the composition of final products of oil and gas obtained from this process. EXAMPLE 1 The following are sample data that can be used to size a pyrolysis plant of 100 tons per day of tires, constructed in accordance with Figure 2.

EXAMPLE 2 The following is a table showing the oil composition collected in a pilot plant study, from a system constructed as illustrated in Figure 2 for two different sources of tires, ie source 1 was from used cars, and source 2 was from OEM car tires rejected or out of specification. fifteen EXAMPLE 3 The following is a table showing a typical non-condensable gas analysis for the product obtained from line 104 in a pilot tire pyrolysis plant constructed as shown in Figure 2. Gas Analysis

Claims (27)

1. CLAIMS 1. A system for recovering oil from the pyrolysis of the hydrocarbon-containing material, characterized in that it comprises: a pyrolysis gas source containing water vapor, hydrocarbon fuel gas, condensable oil and particulate matter; a primary oil condenser to separate the source of pyrolysis gases into a primary oil fraction containing petroleum and particulate matter, and a primary vapor fraction containing petroleum, hydrocarbon combustion gases and water vapor, the condenser of Primary oil operates at a temperature above the dew point of the water vapor in the pyrolysis gas source, the primary oil condenser includes an inlet to receive the pyrolysis gases, a first outlet to collect the primary oil fraction and a second exit to collect the primary vapor fraction; and a secondary oil condenser to separate the primary vapor fraction in a secondary petroleum fraction containing oil and water, and a secondary vapor fraction containing hydrocarbon combustion gases, the secondary oil condenser operates at a temperature below From the dew point of the water vapor in the primary steam fraction, the secondary oil condenser includes an inlet to receive the primary vapor fraction, a first outlet to collect the secondary oil fraction and a second outlet to collect the fraction of secondary vapor.
2. 2. The system according to claim 1, characterized in that the primary oil fraction has a flash point of about 60 ° C or higher.
3. 3. - The system according to claim 1, characterized in that the secondary petroleum fraction has a flash point of about 34 ° C or less.
4. 4. The system according to claim 1, characterized in that the secondary petroleum fraction has a specific gravity of about 0.90 to about 0.95.
5. 5. The system according to claim 1, characterized in that it also includes a tertiary oil separator, to remove nebulization of a condensate oil trapped in the secondary vapor fraction, to provide a tertiary petroleum fraction and a tertiary vapor fraction .
6. 6. The system according to claim 5, characterized in that the tertiary oil separator is a mist separator.
7. 7. The system according to claim 1, characterized in that the primary oil condenser is a packed tower having an upper end, a lower end and a central portion filled with gaskets.
8. 8. The system according to claim 7, characterized in that it also includes means to recycle a portion of the primary oil fraction to the packed tower to avoid embedding of the packages.
9. 9. The system according to claim 7, characterized in that it also includes at least one upper spray nozzle disposed on the package and directed to spray oil downwardly on the package, at least one lower spray nozzle is placed below of the packing and directed to spray oil upwards towards the packing, and a pump for a portion of the primary oil fraction from the first outlet of the primary oil condenser to the upper and lower spray nozzles.
10. 10. - The system according to claim 9, characterized in that it also includes a filter placed between the pump and the first outlet of the primary oil condenser to remove particulate matter from the primary oil fraction.
11. 11. The system according to claim 9, characterized in that it also includes a heat exchanger placed between the pump and the nozzles to cool the primary oil fraction before spraying into the package.
12. 12. The system according to claim 1, characterized in that the secondary oil condenser is a packed tower having an upper end, a lower end and a central portion filled with gaskets.
13. 13. The system according to claim 12, characterized in that it also includes means for recycling a portion of the secondary petroleum fraction to the packed tower to condense the oil and water in the primary steam fraction.
14. 14. The system according to claim 12, characterized in that it also includes at least one upper spray nozzle placed on the package and directed to spray oil downwardly on the package, and a pump for a portion of the oil fraction secondary from the first outlet of the secondary oil condenser to the upper spray nozzle.
15. 15. The system according to claim 14, characterized in that it also includes a heat exchanger placed between the pump and the upper nozzle to cool the secondary oil fraction before spraying onto the package.
16. 16. Method for recovering pyrolysis oil from hydrocarbon-containing material, characterized in that it comprises the steps of: providing a source of pyrolysis gases containing water vapor, hydrocarbon fuel gases, condensable oil and particulate matter; separating the pyrolysis gases into a primary petroleum fraction containing petroleum with a flash point of about 60 ° C or higher and particulate matter, and a primary vapor fraction containing petroleum with a flash point of less than about 60 ° C, water vapor and hydrocarbon fuel gases; and separating the primary steam fraction or primary vapors in a secondary petroleum fraction containing water and petroleum having a flash point of about 24 ° C or lower and a secondary vapor pressure containing hydrocarbon fuel gases.
17. 17. Method according to claim 16, characterized in that it also includes the step of removing nebulization of condensed oil trapped in the secondary vapor fraction to provide a tertiary petroleum fraction and a tertiary vapor fraction.
18. 18. Method according to claim 17, characterized in that the step of separating the pyrolysis gases into primary oil and vapor fractions comprises feeding the pyrolysis gases in a packed form having a central portion filled with packing and operating at a temperature above the dew point of water vapor in the pyrolysis gases.
19. 19. Method according to claim 18, characterized in that it also includes the step of recycling a portion of the primary oil fraction to the packed tower to avoid embedding of the packages.
20. 20. Method according to claim 19, characterized in that the step of recycling includes spraying the primary oil fraction in descending manner on the packages.
21. 21. Method according to claim 19, characterized in that the step of recycling includes spraying the primary oil fraction upwards towards the packages.
22. 22. Method according to claim 19, characterized in that it also includes the step of removing particulate matter from the primary oil fraction before recycling the primary oil fraction to the packed tower.
23. 23. Method according to claim 19, characterized in that it also includes the step of cooling the primary oil fraction before recycling the primary oil fraction to the packed tower.
24. 24. Method according to claim 16, characterized in that the step of separating the primary rotor fraction into secondary oil and steam fractions, comprising feeding the primary steam fraction in a packed tower having a central portion filled with gaskets. and operate at a temperature below the dew point of the water vapor in the primary vapor fraction.
25. 25. Method according to claim 24, characterized in that it also includes the step of recycling a portion of the petroleum fraction secondary to the packed tower to condense the water and oil in the primary vapor fraction.
26. 26. - Method according to claim 25, characterized in that it includes the step of recycling including spraying the secondary oil fraction in descending manner on the packages.
27. 27. Method according to claim 24, characterized in that it also includes the step of cooling the secondary oil fraction before recycling the fraction of secondary oil to the packed tower.