Heat treatment process and system for increased pitch yields

Abstract

To disclose a pitch production system using coal tar or decant oil for coal-based or petroleum-based pitch.SOLUTION: Total pitch production yields are increased by heat treating distillate fractions from a pitch production process. A heat treatment system and process are disclosed in embodiments. A heaviest distillate having a highest molecular weight is subjected to heat treatment, though other embodiments contemplate heat treating a variety of combined distillate fractions. The heat treatment system requires heat soaking distillates at elevated temperatures of 459 to 535°C at a near-constant temperature with near-uniform flow. A fraction of the heat-treated distillate may be re-introduced to the pitch production system as a part of a continuous process.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Patent Application No. 16 / 520,135, filed on July 23, 2019, which is currently pending, the content of which is hereby incorporated by reference in its entirety. The present invention relates to improvements in the production of carbonaceous pitch. More specifically, the present invention relates to the heat treatment of distillation by-products from the treatment of coal tar and petroleum to optimize the pitch yield while minimizing quinoline insolubles and mesophase formation in the pitch.

Background Art

[0002] Coal is a very important starting material in the manufacture of many useful products on which the modernized world has come to rely. Among these, in particular, bituminous coal mined from the ground can be heated in a furnace called a "coke oven" to produce coke and coal tar by the destructive distillation or carbonization of coal. Coke is widely used as a fuel and as a reagent source in steelmaking. Coal tar is a dark liquid removed from coal in the coking process and is useful as a component of seal coats used for sealing roads, asphalt, roofs, treated wood, and other construction materials. Coal tar is a complex mixture of generally about 10,000 mainly aromatic and semi-aromatic compounds that boil in the range of generally 50 °C to over 550 °C, such as, but not limited to, benzene, toluene, xylene, indene, phenol, naphthalene, benzothiophene, quinoline, methylnaphthalene, acenaphthene, fluorene, phenanthrene, anthracene, carbazole, fluoranthene, pyrene, tetracene, triphenylene, chrysene, benzo(a)pyrene ("BaP"), coronene, and benzo(ghi)perylene. Therefore, when coal tar is distilled, it becomes a series of fractions, and various components are separated and recovered, each of which may be commercially viable on its own. A significant fraction of the distilled coal tar material is coal tar pitch residue. This material is used in the manufacture of anodes for aluminum refining and electrodes for electric arc furnaces used in the steel industry. In the evaluation of the qualitative characteristics of coal tar pitch, the industry has focused on the ability of coal tar pitch materials to provide suitable binders for use in the manufacturing processes of anodes and electrodes. Softening point, specific gravity, quinoline insoluble %, and coke value all play a role in characterizing coal tar pitch with respect to its applicability to these various manufacturing processes and industries. Pitch can also be obtained from petroleum rather than coal. In such cases, oils obtained from the catalytic cracking of petroleum, such as decant oil or ethylene cracker bottoms ("ECB"), can be used as starting materials for the production of petroleum pitch. Decant oil is produced in petroleum refining from the catalytic cracking and distillation of petroleum. Decant oil has storage stability, a high boiling point, and further contains aromatic compounds and heterocyclic compounds. Since ECB has lower thermal stability than decant oil, its distillation products may explode during storage and are not very desirable. The pitch manufacturing processes of coal tar and petroleum may be similar to each other and may even use the same equipment, but the operating conditions are different. Alternatively, the pitch manufacturing systems of petroleum and coal tar may also be different from each other. Furthermore, petroleum pitch may have different properties compared to coal tar pitch with respect to softening point, quinoline insoluble ("QI")%, or coke value. In many cases, a blend of petroleum pitch and coal tar pitch in a specific ratio is used to address raw material shortages, costs, and the desired properties of the final product.

[0003] There are numerous methods for producing coal tar or petroleum pitch. For example, FIG. 1A shows one embodiment of such a process. This prior art distillation process begins with a feedstock of wet crude material 1. The wet crude material 1 may be either coal tar or a petroleum-based oil such as decanted oil or ECB. The wet crude material 1 is introduced into the first column C1 through the C1 feed line 10, which is a pipe or conduit that transfers the starting material of the wet crude material 1 to the first column C1. The C1 feed line 10 may be narrow compared to the internal volume of the first column C1, so the wet crude material 1 is under high pressure within the C1 feed line 10. When the wet crude material 1 enters the first column C1 through the orifice 11, it experiences a "flash" or sudden change in pressure, whereby the components are separated into low-boiling and high-boiling components. The first column C1 is a dehydration vessel that heats the contents to a specific temperature to remove the light fraction components. Alternatively, the C1 feed line 10 may pass through a heat exchanger to raise the temperature of the wet crude material 1 before entering the column. The first column C1 is mainly used to remove water and produce a "dry tar" or "dry oil" (depending on the starting material) at the bottom of the column that does not exceed a specific water content. For example, a heater such as a steam heater may be used to heat the first column C1 to a temperature of about 160°C to fractionate the C1 distillate 12, which includes water vapor and relatively low-boiling light molecules (such as light oil containing water, benzene, toluene, and xylene, generally referred to as "BTX"). The above C1 distillate 12 rises to the top or "overhead" region of the first column C1 and is removed through the C1 vapor line 13. The remaining, heavier molecules, including polycyclic aromatic hydrocarbons ("PAH"), descend to the bottom of the column. The "bottom" refers to a fraction having a heavy component that separates at the bottom of the distillation column as a result of mass and high boiling point. Thus, the C1 bottom contains PAH and other heavy molecules and is often referred to as "dry tar / oil" 14.

[0004] The dry tar / oil 14 from the C1 bottom is transferred to the second tower C2 through the connecting C1 - C2 transfer line 15 and further distilled. Therefore, the dry tar / oil from the first tower C1A is the feedstock for the second tower C2. The second tower C2 is a fractionating tower that provides multi - stage distillation. A distillation tower with multiple stages results in the optimal recovery and purity of useful chemicals. The distillation tower has a plurality of trays 20 that extend over at least a portion of the diameter of the tower. These trays function as stages for the formation of distillation condensates and assist in the further separation of components in the reflux of the components. The distillation tower also includes irregular or regular packings 21, and the separation is assisted by the rising of vaporized molecules through the packings. Regardless of the tower structure, the boiling vapor advances upward in the tower and the liquid flows downward by gravity. At any stage, the vapor entering from below is hotter than the liquid flowing downward. This convective contact between the vapor and the liquid transfers heat from the vapor to the liquid. This vaporizes the lighter - boiling light components in the liquid and condenses the heavy components in the vapor. The continuous occurrence of this light vaporization and heavy condensation at each stage separates and purifies the recovered chemicals. The distillation in the second tower C2 typically occurs by heating the second tower C2 with a heater at atmospheric pressure from a minimum temperature of about 250 - 270 °C to a maximum of 360 °C. The light fraction 22 may be removed at this stage, including naphthalene (which can be sold by itself or used in the manufacture of dyes and plastics), and may be further concentrated into a refined chemical oil ("RCO") that distills at 210 - 315 °C. The light fraction 22 is removed from the second tower C2 through the vapor line 23. A portion of the light fraction 22 is returned to the second tower C2 for reflux to achieve further distillation and separation. The C2 bottom obtained from the second tower C2 is generally called "topped - tar / oil" 25 (which also varies depending on the starting material), contains high - molecular - weight aromatic hydrocarbons such as PAH, and constitutes the middle fraction and the heavy fraction.

[0005] The overhead tar / oil 25 from column C2 is transferred from the second column C2 to the third column C3 through the C2-C3 transfer line 26. Additional tar and pitch, including overhead tar, intermediate pitch or soft pitch, is characterized as soft pitch 27 and has a softening point of about 40 - 125 °C, preferably about 90 °C (highly dependent on the desired final softening point of the final pitch), and may be added to the C2-C3 transfer line 26 and combined with the overhead tar / oil 25 as an additional feed to the third column C3 when additional volume is required or when adjusting the characteristics of the incoming feedstock. This third distillation column C3 may contain packing 21 and / or trays, and its contents are heated by a heater to a temperature exceeding 315 °C. However, care is needed at this stage since the mesophase begins to form at a temperature of 390 °C. The mesophase is a precursor to coke and will appear as solid particles within the produced pitch. However, the term "mesophase" as used herein refers only to the "reportable" mesophase larger than 4 μm. The "embryonic" mesophase below 4 μm is not considered a mesophase for the purposes of this disclosure. Coke in the pitch reduces the functionality of the pitch when used in the production of anodes for aluminum production and electrodes for steelmaking, limits the ability of the pitch to properly wet the coke in the mixing step for producing carbon artifacts such as anodes or electrodes, and results in a reduction in conductivity in the resulting product, and thus should be avoided in this particular manufacturing process. Therefore, a vacuum may be used in the third column C3 to lower the boiling points at which the components separate and distill.

[0006] Various fractions are obtained from the third column C3, each of which is a mixture of various components. For example, the first intermediate fraction 35 may be the first to distill and may be removed from the third column C3 through the distillate line 36. The first intermediate fraction 35 is a mixture of various carbon-based molecules, such as molecules having at least 12 carbons and thus having a high molecular weight. Such molecules may also be referred to as carbon black feedstock ("CBF") and may be sold to the carbon black industry for manufacturing raw materials for the rubber industry. A portion of the first intermediate fraction 35 may be returned to the third column C3 for reflux and further separation. The second intermediate fraction 38 can be removed from the third column C3 through the distillate line 39. The second intermediate fraction 38 may contain compounds used in the manufacture of creosote wood preservatives, and the compounds may be separated from the remaining distillate for further purification and use in other applications (such as tie treatment, utility poles, and other wood preservative applications). A portion of the second intermediate fraction 38 can be returned to the third column C3 for reflux and further separation. The heavy fraction 41 contains further higher molecular weight components. The heavy fraction can be removed from the third column C3 through the vapor line 42. The heavy fraction 41 is a by-product and may contain a carbon black feedstock. A portion of the heavy fraction 41 can be returned to the third column C3 for reflux and further separation. What remains in the C3 bottom in the third column C3 is the coal tar pitch 50. This pitch 50 is a thick black liquid containing a mixture of chemicals such as PAHs and is the desired final product of the above pitch manufacturing system. The pitch can be removed from the third column C3 through the pitch outlet line 51 and used for subsequent applications. This pitch 50 is characterized by various qualities such as softening point, specific gravity, QI%, coke value, etc. to determine its quality and applicability in various manufacturing processes and industries. The distillation process can selectively change the characteristics obtained in the manufactured pitch 50 as desired by adjusting so that the various fractions of the distillate are removed at different times and / or in different volumes. For example, a coal tar pitch 50 having a Mettler softening point of about 108 to 140 °C and a QI of 10% or less can be used as a binder in the manufacture of anodes and electrodes. Lower QI is required for impregnating pitch.

[0007] In a second embodiment of the prior art pitch production, as shown in Figure 1B, the wet crude material 1 feedstock is flashed into the first column C1 through the orifice 11 and dehydrated. The light oil and water are removed as the C1 distillate 12, and the dry tar / oil 14 is transferred to the second column C2 through the transfer line 15. The second column C2 is a multi-stage fractionation device, similar to other prior art processes, and is heated by a heater to a temperature of about 250 - 270 °C at atmospheric pressure. However, in this embodiment, the light fraction 22 is distilled off from the second column C2 through the vapor line 23, and the middle fraction 38 is distilled off through the distillate line 39. The light fraction 22 may include refined chemical oil ("RCO") and other light distillation oils. The middle fraction 38 may contain creosote, which may be further separated and purified. The light and middle fractions 22, 38 may be combined and stored together, or subsequent processing may be performed for the production of refined creosote. In this embodiment, the topped tar / oil 25 in the bottom of C2 is then moved through the C2 - C4 transfer line 26' to the fourth (third in this embodiment) column C4 and may be introduced or flashed into the fourth column C4 by an orifice 11 (which may be a sparger). This flashing separates the heavy fraction 41, such as heavy oil, from the remaining residue so that the heavy fraction 41 is removed from the fourth column C4 through the vapor line 42. The components of the heavy fraction 41 are then separated by further distillation or processing, which may yield carbon black pitch and other aromatic compounds. The residue at the bottom of the fourth column C4 is pitch 50, which may be coal tar pitch if starting from coal tar or petroleum pitch if starting from decanted oil.

[0008] A third embodiment of the prior art pitch production uses four columns to distill and / or separate oil from the residue in pitch generation, as shown in Figure 1C. Specifically, the wet crude material 1 is first dehydrated in the first column C1, and the C1 distillate 12 containing water and light oil is removed. Then, the dry tar / oil 14 is distilled in the second column C2 of the distillation apparatus, and the light fraction 22 is removed. The resulting topped tar / oil 25 is then transferred to the third column C3 of another distillation apparatus, where the middle fraction 38 is removed. In this embodiment, the residue from the third column C3 is transferred to the fourth column C4, which is a flash column, where the heavy fraction 41 is separated by a sharp differential pressure. The remainder is the desired pitch 50.

[0009] The above-mentioned prior art pitch manufacturing process can produce a pitch yield of 15 - 60% depending on process parameters, calculated from one of the starting materials, coal tar and decant oil. Optimization of the process and increase in product yield are important but difficult to determine, and it has been found that it is even more difficult to produce commercially viable products on an industrial scale. One way to optimize the yield involves heat treatment (also called warm heat treatment or heat soaking (scorching treatment)) of distillates and by-products used as feedstock in pitch manufacturing. It is recognized that the heat treatment process has three main parameters: temperature, pressure, and residence time. Numerous attempts have been made to identify ways to improve pitch yield (and other properties) through the use of heat treatment, but their capabilities vary widely, and few have been commercially successful at the industrial production levels required for commercial development. Each cited reference discloses a wide range of times and temperatures, the mechanisms leading to increased yield are poorly understood, and the disclosure of actual times and temperatures associated with specific yields is inadequate.

[0010] U.S. Patent No. 3,140,248 discloses the preparation of binder pitch using a soaking step. A petroleum fraction having a boiling point of 200 - 650°C is catalytically cracked and then pyrolyzed. The hot residue obtained from pyrolysis is treated in a pyrolysis zone (soaking zone) at a temperature of 480 - 590°C for 4 - 20 minutes at 2.1 - 27.6 bar (30 - 400 psi). To minimize coking, short residence times and high linear velocities are preferred. The use of a soaking coil is disclosed but not described in detail. U.S. Patent No. 3,318,801 discloses a heat soaking drum and a short tube heater. The heat soaking drum is used at a temperature of 340 - 425°C and 0 - 2.1 bar(g) (0 - 30 psi(g)) for 3 - 90 minutes. The heating tube induces rapid heating to 425 - 510°C for 2 - 30 minutes at 1.7 - 17.2 bar(g) (25 - 250 psi(g)). U.S. Patent No. 3,673,077 discloses heat soaking for binder pitch production to increase toluene-insoluble content (「TI」). The conditions are 350 - 450 °C, a pressure of about 5.2 bar(g) (75 psi(g)), and a residence time of 15 minutes to 25 hours. Optionally, air passing through the reactor is also disclosed. U.S. Patent No. 4,039,423 discloses the heat treatment of decanted oil to form petroleum pitch. The conditions include 413 - 524 °C, 15.2 - 30.3 bar(g) (220 - 440 psi(g)), and a residence time of 3 - 300 minutes. Turbulent continuous flow conditions rather than laminar flow are preferred to minimize coke formation and maintain QI in the suspension. This also increases the efficient mixing of the materials and shortens the reaction time. The softening point of the product is in the range of 79 - 135 °C. European Patent Application Publication No. 1739153 discloses the use of thermal treatment of coal tar and distillates under an inert atmosphere. The conditions are 340 - 400 °C, less than 10.0 bar(g) (145 psi(g)), and a residence time of 3 - 10 hours. Preferred embodiments are 370 - 400 °C, 1.0 bar(g) (14 psi(g)), and 4 - 6 hours. Thermal treatment under inert conditions is presumed to increase the planarity of the molecules and the stability of the reaction products and limit side reactions. This improves wettability, graphitization, and reaction yield. The starting material includes anthracene oil. U.S. Patent No. 8,757,651 discloses the use of heat treatment of coal tar distillates at 350 - 440 °C and a pressure of 3.5 - 8.3 bar(g) (50 - 120 psi(g)) for pitch production. The residence time ranges from 1 - 7 hours. The starting material is low-QI creosote oil. Heat treatment is presumed to polymerize relatively low molecular weight components into larger molecules. Downstream distillation of the product is intended to separate different species. The final product can have a coke value of 55 - 70% and a softening point of 90 - 140 °C. A QI of less than 15% is also the goal. Batch and continuous heat treatments are contemplated, but details of the reactor are not shown. U.S. Patent No. 9,222,027 discloses heat treatment using an electrically heated tubular reactor operating at high speed and high pressure. Salt and molten metal baths are also disclosed. The conditions are 450 - 560 °C, 34.5 - 62.1 bar(g) (500 - 900 psi(g)), and a residence time of 1 - 2 minutes. Laminar and turbulent flows inside the pipes of the reactor are addressed, and turbulent flow is preferred. The Reynolds number for turbulent flow is generally accepted to be over 4000. A Reynolds number over 10,000 is preferred, and the best experimental results are obtained at 25,000. Although speculation about the use of a Reynolds number over 50,000 is shown, there is no empirical or experimental data. U.S. Patent Application Publication No. 2017 / 0121834 discloses the production of petroleum pitch using heat treatment. The soaker reactor is used at a range of 360 - 460 °C, 14.8 - 18.3 bar (215 - 265 psi) for 15 minutes to 5 hours. An inert environment, or at least free of oxygen, is required. The starting materials include decanted oil, lubricant extract, and gasoline. Despite these efforts, the prior art solutions have not achieved commercial success, so there is still room for improvement. Therefore, what is still unknown in the art is a heat treatment method and apparatus applicable to coal tar and petroleum by-products that can produce predictable and reproducible results in commercial-scale operation. Significant limitations to the application of the prior art include the generation of excessive coke or mesophase after heat treatment, which hinders the continuous processing of the starting materials. This typically results from excessive application of the treatment, or excessive variation in the time and temperature of the treatment. From the prior art teachings that utilize recirculation of the contents of batch reactors, recirculation is identified as harmful to the quality of the pitch.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] To minimize coking and mesophase formation, a heat treatment process is disclosed in which a distillation by-product from coal tar or petroleum production is subjected to a heat treatment with particular attention paid to parameters related to time, temperature, and pressure. A corresponding coal tar or petroleum pitch production process using the heat treatment process is disclosed.

Means for Solving the Problems

[0013] Specifically, the heat treatment process of the present invention utilizes the heavy fraction distilled out in the subsequent pitch production and the decanted oil from petroleum production as starting materials. The heat treatment process of the present invention subjects these starting materials to heat treatment at specific temperatures, pressures, and residence times to recover additional pitch and increase the overall pitch yield. Thus, the heat treatment process of the present invention makes beneficial by-products that are economically less viable by other methods while enhancing the efficiency of the overall pitch production. Controlling the variables of temperature, pressure, and residence time related to the heat treatment process is extremely important to keep the QI level to a minimum and avoid mesophase formation. The present invention utilizes a high temperature range that can exceed 510 °C and a pressure range that exceeds 4.1 - 20.7 bar(g) (60 - 300 psi(g)) to keep the starting raw materials and reactants in the liquid phase, so that the starting raw materials and reactants are constantly moving throughout the heat treatment system. However, since the mesophase is known to form at about 390 °C, the present invention aims to minimize the residence time in the corresponding process to minimize the possibility of mesophase formation and the resulting coking. The present invention also attempts to achieve turbulent heating of the feedstock and subsequent plug flow in the reactor section of the heat treatment apparatus as much as physically possible in real-world conditions, with the goal of maintaining a continuous and consistent flow within the system such that the starting materials are exposed to heat almost equally, and this flow is uniquely identified as "near-uniform flow". In this specification, references to plug flow should be understood as near-uniform flow. The longer the time within the system, the higher the possibility of mesophase formation and coking, and this can be countered by lowering the temperature, but this is not preferred. The yield can be increased by returning the heat-treated starting materials as additional feedstock to the pitch production process as part of a continuous process.

[0014] In addition, it has been pointed out that the softening points of commercially used pitches tend to increase in the future. Currently, the softening points of most commercial pitches and pitch blends are in the range of 90 - 150 °C. The decrease in the softening point of pitch is a result of a high PAH content, and reducing this content causes the softening point to increase. Many of the PAH compounds are potentially carcinogenic, and some states and countries are becoming increasingly sensitive to the exposure of people and the environment to these substances. Therefore, by removing more of these high PAH compounds, potentially carcinogenic compounds are removed, but as a result, the softening point also increases, so the softening point of pitch may increase in the future. Heavy fractions contain a large number of highly aromatic compounds, and it is known that increasing the amount of heavy fraction removed during pitch production results in a higher softening point of the resulting pitch. A method of utilizing this additional removed heavy fraction is beneficial, especially when it can be used for further pitch generation. The systems and processes disclosed herein provide such benefits. By referring to the following embodiments for carrying out the invention and the accompanying drawings, the systems and processes for heat treatment and pitch production will become clearer along with their features and advantages.

Brief Description of the Drawings

[0015]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3A

Figure 3B

Figure 3C

Figure 3D

Figure 3E

Figure 3F

Figure 4A

Figure 4B

Embodiments for Carrying Out the Invention

[0016] Throughout the several drawings, like reference numerals refer to like parts.

[0017] As shown in the accompanying drawings, the present invention relates to heat treatment systems 300, 300', and pitch manufacturing systems 100, 100', 100'' (from coal tar) and 200, 200', 200'' (from petroleum) that utilize such systems. For example, FIGS. 2A-2C illustrate various embodiments for manufacturing coal tar pitch 150 from coal tar 102, and FIGS. 3A-3C show various embodiments for manufacturing petroleum pitch 250 from decanted oil 203. FIGS. 4A-4B show various heat treatment systems 300, 300' that can be used with any of the pitch manufacturing systems.

[0018] Coal tar First, turning attention to the coal tar pitch manufacturing system, a first embodiment of the pitch manufacturing system 100 (schematically shown in FIG. 2A) begins with the dehydration of coal tar 102. The crude coal tar 102 is likely to have some water or moisture from the initial coking process, but the moisture should be less than about 4 mass% so as not to slow down the tar treatment. The coal tar 102 is transferred via a C1 supply line 110 to a first column C1 for dehydration. The C1 supply line 110 passes through at least one heat exchanger (not shown), where heat from other elements of the system is applied to the C1 supply line 110 to preheat the tar 102 in the C1 supply line 110 while cooling other components. The heat exchangers disclosed herein and the heat exchangers in the figures are in a sufficient contact state that allows heat transfer from a high-temperature component to a low-temperature component without mixing the components. Thereby, the heat generated within the system is used efficiently. The cost of heating the components of the system can be very high, and this is particularly important in industrial-scale manufacturing that may require a large amount of fuel. Multiple heat exchangers may be arranged throughout the system to use heat effectively. In at least one embodiment, the heat exchanger may include paths of various distillate lines such that it cools the corresponding distillate for storage while heating other components such as the tar 102 feedstock. In other embodiments, heat exchange oil may be used in the heat exchanger to heat the lower-temperature components.

[0019] In at least one embodiment, the coal tar 102 has an initial temperature of about 50°C. The coal tar 102 is heated to about 160°C when the C1 supply line 110 passes through at least one, or in some cases two or more, heat exchangers. Thus, the coal tar 102 has a temperature of at least 160°C when it enters the first column C1. Since the coal tar 102 is pumped through the C1 supply line 110, it is under a pressure of, for example, about 6.9 bar (100 psi). The first column C1 is an atmospheric column at a pressure of about 1 atm (about 14.7 psia). When the coal tar 102 enters the first column C1 through the orifice 111, a sudden pressure drop flashes the coal tar 102 and initiates the separation of its components. Preferably, since there is no reboiler or other heater to heat the first column C1, the heat of the first column C1 is generally the heat of the incoming wet coal tar 102, which is at least 160°C. Steam and distilled light oil (such as BTX) move upward in the first column C1 and may be condensed by a cooling water condenser at a maximum temperature of about 75°C before being removed by the C1 vapor line 113 and recovered as the C1 distillate 112. Water distills at a temperature of approximately 100°C. Light oil also distills at approximately the same temperature: benzene (80°C), toluene (110°C), and optionally xylene (144°C). Therefore, these light oils and water are distilled and recovered together. The light oil accounts for about 1% of the coal tar feedstock, is immiscible with water, is decanted as the top layer of the C1 distillate 112, and is pumped for storage. The specific gravity of the light oil needs to be monitored and should not be too high, for example, about 0.92 or less at 15.5°C. Exceeding the above value may result in insufficient separation from the condensed water. This can occur when the wet coal tar 102 for the first column C1 is too high. The distillation in the first column C1 is continued until the dry tar 114 recovered at the bottom of C1 has a water content reduced to about 2.5 mass% or less, preferably less than 0.5%, and further has a specific gravity of at least 1.15 at 15.5 °C. The dry tar 114 may then be removed from the first column C1 through the transfer line 115, which can raise the temperature of the dry tar 114 to about 250 - 270 °C before entering the second column C2 for tar topping through at least one heat exchanger.

[0020] In the second column C2, in the process called "tar topping" where the lowest boiling fraction of the dry tar 114, i.e., the top distillate, is removed, the dry tar 114 is further distilled to recover the light fraction 122. This fraction may contain crude naphthalene as RCO. The incoming dry tar 114 is already at a temperature of about 250 - 270 °C when it enters the second column C2 and can be pumped under flow control at a C2 feed flow rate based on the heater, vacuum, and condenser system associated with the second column C2. The second column C is an atmospheric column at a pressure of 1 atm and has distillation trays 120 below the dry tar 114 feed point. In at least one embodiment, there are 20 - 30 trays in the second column C2. Further, there may be at least one packed column section or packing 121 above the dry tar 114 feed point to increase the purity when the light fraction 122 distills. A heater, for example, a fired process heater boiler or other suitable heat source, is attached to the second column C2 to heat the bottom contents to a temperature of about 350 - 360 °C and further light fraction 122 may distill. The light fraction 122 vapor moves upward through the second column C2 and is typically removed through the distillate line 123 at a rate of about 15 - 22% of the C2 feed rate. The light fraction 122 is then condensed in a condenser and converted to a liquid form. This may contain RCO along with naphthalene and may further be water cooled in a heat exchanger. Preferably, the light fraction 122 may have a naphthalene content of 55 - 65% and may be further processed in a purification device to separate and purify the naphthalene. The light fraction 122 also preferably has a maximum specific gravity of 1.03 at 70 °C. The characteristics of the light fraction 122 are also shown in Tables 1 and 2 below. At least a portion of the light fraction 122 is returned to the top of the second column C2 and refluxed to limit the amount of high-boiling compounds in the light fraction 122 and increase the naphtha content of the light fraction 122. Throughout this disclosure, as is well known to those skilled in the art, it should be noted that all distillation and vapor streams may alternatively be removed and stored for future further use and inserted at an appropriate point in these processes. This liquid C2 reflux condenses high-boiling compounds in the vapor above the feed point and improves the separation efficiency of the top rectification section of the second column C2.The light fraction 122 can be refluxed at at least 10% of the C2 feed rate to increase the naphthalene content in the light fraction 122. Approximately 15 - 22% of the initial coal tar 102 can be removed as the light fraction 122. The C2 bottoms contain the overhead tar 125 and are transferred through transfer line 126 to the third column C3 to produce pitch at the desired softening point. Since heat is maintained along transfer line 126, the overhead tar 125 entering the third column C3 is at approximately the same temperature as the C2 bottoms. Optionally, soft pitch 127 can be added to transfer line 126 before the third column C3 and combined with the overhead tar 125 to form the C3 feedstock, and temperature adjustment, increasing the feedstock, or removing residual oil from the added soft pitch can be performed. The third column C3 is preferably a vacuum column operating at an absolute pressure of about 40 - 100 millibars (absolute pressure of about 0.77 - 1.9 psia). The third column can also have a combination of trays 120 for multi-stage distillation and a packed column top section 121. A heater (such as, but not limited to, a fired process heater boiler) can be used to heat the C3 column bottoms to a temperature of about 350 - 360 °C to boil off heavy oil distillate from the overhead tar 125 by recirculation of the C3 bottoms liquid. When the overhead tar 125 is distilled in the third column C3, the vapor of the distillate rises in the column and is condensed by recirculation of various distillates. Specifically, the first intermediate fraction 135 is extracted through the distillate line 136 and can be externally cooled and condensed with other processes, a heat transfer oil stream, or water. This fraction has the characteristics described in Tables 1 and 2 below. The first intermediate fraction 135 is an intermediate carbon black feedstock produced as a blend oil, mainly to support the quality of other products. A portion of it may be refluxed back to the third column C3 or sent for storage and sale. Less than about 5% of the initial coal tar 102 is distilled as the first intermediate fraction 135.

[0021] The second product from the third column C3 is the second intermediate fraction 138, which may contain components used as creosote, such as WEI-C or AWPA creosote base oil. The second intermediate fraction 138 is removed from the distillate line 139 and can be condensed by being externally cooled with other processes, a heat transfer oil stream, or water. Approximately 13 - 22% of the total crude tar 102 is distilled as the second intermediate fraction 138. The second intermediate fraction 138 has the characteristics described in Tables 1 and 2 below, and / or features a maximum of 10% distillation up to 300°C, a maximum of 65 - 90% distillation up to 355°C, and in certain cases (especially in Europe), a maximum of 10 ppm of benzo(a)pyrene. At least a portion of the distilled second intermediate fraction 138 can be returned or recycled to the third column C3 for reflux. The creosote contained in the second intermediate fraction 138 is very useful in other industries, such as wood preservatives. Therefore, monitoring for quality control may be carried out by monitoring the distillation range and the content of benzo(a)pyrene. The quality of the second intermediate fraction 138 is controlled by its production rate (preferably in the range of 14 - 20% of the total crude coal tar 102) and the temperature (preferably in the range of 100 - 115°C) when recycled to the third column C3 for reflux. The third product obtained from the distillation of the topped tar 125 in the third column C3 is the heavy fraction 141, which is removed from the distillate line 142 and can be condensed by being externally cooled with other processes, a heat transfer oil stream, or water. This heavy fraction 141 is also a mixture of components that mainly contain a carbon black feedstock but have additional components not found in the first intermediate fraction 135, and these components increase the PAH level and boiling point of the heavy fraction 141. Furthermore, the heavy fraction 141 has extremely low concentrations of QI and toluene-insoluble matter, which are substantially zero. This fraction may also be characterized by a maximum of 10% distillation up to 355°C. At least a portion of the heavy fraction 141 can be returned to the third column C3 for further distillation and separation by reflux. Approximately 14% of the total crude tar 102 can be distilled off as the heavy fraction 141.

[0022] The various distillates related to the first embodiment of the coal tar manufacturing system 100 generally have the characteristics shown in Tables 1 and 2 below, and the amounts of their components can vary according to the target softening point of the pitch to be manufactured.

Table 1

[0023]

Table 2

[0024] The residue remaining in the C3 bottom is the desired coal tar pitch 150, and its quality is determined by, but not limited to, its softening point, the percentage of distillate up to 355 °C, QI, and toluene insoluble matter. All of the above three parameters are controlled by the C3 bottom liquid temperature and the heavy fraction 141 production rate. Preferably, the softening point of the resulting pitch 150 is in the range of 100 - 140 °C, and QI is 20% or less. Further, the ash content of the final pitch 150 is preferably 0.4% or less, and the distillate up to 355 °C is preferably 4% or less. This system 100 and process can produce a pitch yield of at least about 40%. This pitch 150 is removed from the third column C3 via the pitch outlet line 151 and stored, transported, used, or sold.

[0025] The pitch manufacturing system 100 also includes a heat treatment system 300. Although the details of the heat treatment system 300 are shown more fully below with reference to FIGS. 4A and 4B, it should be noted that the heat treatment process 300 can increase the total pitch 150 yield by 2 - 10% and can result in a total yield of about 42 - 50%. In a particular embodiment, the pitch yield can be increased to a preferred target of 44% total pitch yield. This additional pitch 150 is obtained by heat-treating the distilled heavy fraction 141 at a specific pre-selected temperature and residence time, and then introducing the heat treatment product into the third column C3 to further distill and separate the pitch in the pitch manufacturing system 100, as shown in FIG. 2A.

[0026] The present invention also includes a second embodiment of a coal tar pitch manufacturing system 100' schematically shown in FIG. 2B. The coal tar 102 is heated to about 160 - 170 °C under a pressure of about 6.9 bar (100 psi) when passing through at least one heat exchanger (not shown) in the C1 supply line 110. The coal tar 102 is flashed into the first column C1 through the orifice 111, where the C1 supply line 110 and the first column C1 meet in fluid communication. The first column C1 is a dehydration device under an atmospheric pressure of about 900 mmHg (17.4 psia) in this embodiment. The pressure difference between the C1 supply line 110 and the first column C1 flashes the wet coal tar 102 to separate water vapor and light oil (such as benzene, toluene, and xylene) as the C1 distillate 112. As described above, the residue remaining at the bottom of the first column C1 is the dry tar 114, which remains in the first column C1 until the water content of the dry tar 114 is about 2.5% or less, preferably 0.5% or less. This has the same characteristics as the above dry tar 114. The dry tar 114 is transferred to the second column C2 through the C1 - C2 transfer line 115, and the second column is a fractionating device or a multi - stage distillation column as described above. Here, the second column C2 may be under a vacuum at a pressure of about 120 - 180 mmHg (2.3 - 3.48 psia) and may be heated to an internal temperature of about 182 - 230 °C. In the second embodiment of this manufacturing system 100', a light fraction 122' distills out and is recovered by the distillate line 123. The light fraction 122' may have the composition and characteristics shown in Table 3 below. The middle fraction 138' is also distilled and removed from the second column C2. The middle fraction 138' may have the composition and characteristics shown in Table 3 below. The C2 bottom is heated by a heater (not shown) to a temperature of about 350 - 365 °C to circulate the residue and assist in distillation. The distilled light and middle fractions 122', 138' may be combined and stored together, or stored separately and later processed, for example, for the production of refined creosote that can be used for sale or other purposes. The C2 bottom contains the topped tar 125', which has the same characteristics as those described above and may be at a temperature of about 350 - 365 °C and a pressure of about 180 - 220 mmHg (3.48 - 4.25 psia). However, in this second embodiment of the pitch manufacturing process 100', the topped tar 125' is transferred from the second tower C2 to the fourth tower C4 through the C2 - C4 transfer line 126'. The fourth tower C4 is a flash column instead of the above-mentioned fractionation device, the third tower C3. The topped tar 125' can be flashed into the fourth tower C4' through an orifice 111 (such as a sparger or other suitable introduction opening). The fourth tower C4 may be under a vacuum with a pressure of about 40 - 70 mmHg (0.77 - 1.35 psia). When the topped tar 125 is flashed into the fourth tower C4, the heavy fraction 141' separates at a temperature of about 290 - 365 °C and can be removed through the distillate line 142. This heavy fraction 141' has the composition and characteristics shown in Table 3 below. Then, the heavy fraction 141' is transferred to the following heat treatment system 300 for heat treatment to increase pitch production. After passing through the heat treatment system 300, the heat treatment product is introduced into the C1 - C2 transfer line 115 and added to the C2 feedstock for additional fractionation and distillation. The yield of the pitch 150' produced through this process is 20 - 40% higher than the initial yield without heat treatment of the heavy fraction 141'.

[0027] The various distillates produced by the second preferred embodiment of the pitch manufacturing system may have the characteristics of Table 3.

[0028]

Table 3

[0029] In the third embodiment of the pitch manufacturing system 100” shown in FIG. 2C, the coal tar 102 is heated to about 124 - 184 °C under a pressure of about 10.9 - 11.1 bar (158 - 161 psi) when passing through at least one heat exchanger (not shown) in the C1 supply line 110. The coal tar 102 is flashed into the first column C1 through the orifice 111, where the C1 supply line 110 and the first column C1 meet in fluid communication. The first column C1 is, in this embodiment, a dehydration device under an atmospheric pressure of about 51.7 mmHg (15.6 psia). The pressure difference between the C1 supply line 110 and the first column C1 flushes the wet coal tar 102 and separates water vapor and light oil (such as BTX) as the C1 distillate 112 having a temperature of about 115 °C. As described above, the residue remaining at the bottom of the first column C1 is the dry tar 114, which remains in the first column C1 until the water content of the dry tar 114 becomes 2.5% or less, preferably about 0.5% or less, and the temperature becomes about 230 °C. This may have characteristics similar to the above dry tar 114.

[0030] The third embodiment of this system 100” is different from the foregoing embodiments in that four columns are used for the distillation and separation of oil in pitch generation. Specifically, the dry tar 114 is transferred to the second column C2, which is a fractionating device through the C1 - C2 transfer line 115 and can be heated to a temperature of about 262 °C by a heater (not shown). The light fraction 122” is distilled off from this second column C2 and can be refluxed for further separation. The light fraction 122” has the characteristics shown in Table 4 below and may contain RCO and other light oils. The resulting topped tar 125” is generated at the bottom of the second column C2 and is transferred to the third column C3 through the C2 - C3 transfer line 126 for further distillation. In the third column C3, the tar can be heated to a temperature of about 330 °C with a heater (not shown) to distill the middle fraction 138". The middle fraction 138" may have the characteristics shown in Table 4 and may contain creosote and certain carbon black feed compounds. The middle fraction 138" may also be refluxed to the third column C3 for further distillation and decomposition. The resulting soft pitch 127" is produced at the bottom of the third column C3 and may be close to the desired pitch, but may also have too low a softening point (such as in the range of about 90 °C). To raise the softening point of the pitch, more oil must be removed. Therefore, the soft pitch 127" is transferred to the fourth column C4 through the C3-C4 transfer line, and the column may be a flash column that uses differential pressure to remove oil from solids. For example, the fourth column C4 may be under a vacuum of about 806.8 mmHg (1 psia). The differential pressure causes the removal of the heavy fraction 141", leaving the desired coal tar pitch 150" at the bottom of the fourth column, which can be removed for further use or sale. The heavy fraction 141" may be at a temperature of about 310 °C and a pressure of about 7.6 mbar (g) (0.11 psi (g)) and may further have the characteristics shown in Table 4 below. As detailed below, process 100" continues the heat treatment of the distilled heavy fraction 141" through the heat treatment system 300. After heat treatment, the heavy fraction 141" is combined with the topped tar 125" as a C3 feedstock, or is separately introduced into the third column C3 for the distillation of the middle fraction 138" and then the distillation of the heavy fraction 141" from the newly formed additional pitch.

[0031] The distillate produced by the third preferred embodiment of the coal tar pitch production system 100" may have the characteristics of Table 4.

[0032]

Table 4

[0033] Petroleum pitch Petroleum products can be used as starting materials for the production of petroleum pitch 250, as shown in FIGS. 3A to 3C. For example, as shown in FIG. 3A, petroleum fractions such as decanted oil are generally identified as oil 203 and used as starting products for pitch production. Decanted oil 203 is a mixture of heavy oils obtained from the catalytic cracking of petroleum. Decanted oil is similar to coal tar 102 in many respects, but differs in that it contains more aliphatic hydrocarbons derived from petroleum, which makes the chemistry of decanted oil 203 treatment more complex. However, many of the steps are similar. In certain embodiments, ECB can be used as oil 203 for pitch production 200, either independently or in combination with decanted oil. However, ECB is particularly difficult to handle reliably as a starting reagent because of its low stability as a vapor and its tendency to explode. ECB is generally not suitable for the production of impregnating pitch either. Decanted oil has very high storage stability and is easy to handle, and can therefore be preferred in at least one embodiment. Although petroleum pitch production systems 200, 200', 200" are described with respect to the use of decanted oil 203 as a starting material, it should be understood that heavy oils or compositions thereof obtained from the cracking (such as catalytic cracking) of petroleum with appropriate sulfur, carbon, or coke value characteristics can be used as starting materials.

[0034] The dehydration and distillation characteristics of the petroleum pitch production systems 200, 200', 200" shown in FIGS. 3A to 3C and FIGS. 3D to 3F may be similar to those of the corresponding characteristics of the coal tar production systems s100, 100', 100" in FIGS. 2A to 2C. However, the operating parameters in each step of the petroleum pitch production systems 200, 200', 200" may be different. Those skilled in the art should note that the operating parameters of coal tar can be equally applied to petroleum unless they are clearly identified as different. Further, as shown in FIGS. 3A to 3C, the heat treatment processes 300, 300' can be carried out before the dehydration and distillation of the starting material as the first step of the process in the case of the production of petroleum pitch 250, whereas in the case of the production of coal tar pitch 150, it is carried out after the dehydration and distillation. This is mainly because the chemical composition of the decanted oil has no heavy components compared with coal tar and generally has a low water content at the time of delivery. Therefore, the decanted oil distillation by-products are generally not suitable for independent heat treatment. Therefore, the input of the heat treatment systems 300, 300' in the petroleum pitch production systems 200, 200', 200" is the decanted oil 203. The heat treatment systems 300, 300' will be described in more detail below with reference to FIGS. 4A and 4B. The system may be the same as the system used in the production of coal tar pitch 150, 150', 150".

[0035] Referring to FIG. 3A, in the first embodiment of the pitch manufacturing system 200, the decanted oil 203 is first processed through the heat treatment system 300 and then sent to the remaining distillation system. The specific processing route is determined by whether it is a batch process or a continuous process and the water content. As long as the decanted oil 203 does not require dehydration, the C1 dehydration device may be omitted as described below with respect to FIGS. 3A - 3C, and as is known to those skilled in the art, the streams 326' and 215 may be merged. As long as the C1 dehydration device is necessary or potentially as part of a continuous process, the decanted oil 203 or the combined light fraction 222, the first intermediate fraction 235, the second intermediate fraction 238, the heavy fraction 241, or any combination or partial combination thereof may be reintroduced into the heat treatment system 300 or the C1 dehydration device as described in more detail below. In that case, as shown in FIGS. 3D - 3F, the decanted oil 203 may alternatively be sent to the C1 dehydration device through the input stream 310A. As described below, after dehydration, the decanted oil may be returned to heat treatment through the product stream 215A for introduction into the heat treatment system 300. Further, as part of a continuous system, the distillate stream 243 may be returned through the input stream 310A for reintroduction into the first column C1 dehydration device. In embodiments using the dehydration device C1, the material is introduced and flashed into the first column C1 dehydration device. Due to the differential pressure between the incoming heat-treated oil and the first column C1, light oils such as naphtha or BTX (benzene, toluene, and xylene) are separated from the remainder of the decanted oil 203, which is removed as the C1 distillate 212 through the distillate line 213. As described in more detail below, the BTX and other light oils may be extracted from the reactor 320. The remaining dry oil 214 is transferred through the C1 - C2 transfer line 215 to the second column C2 of the fractionation device or returned to the heat treatment as described above. This second column C2 is pre-heated to a temperature of about 350 - 365 °C with a heater in order to distill off the light fraction 222 from the oil (which may include RCO and creosote). The light fraction 222 may also be sent to recycle through the system 200 for further heat treatment and through the light fraction stream 224 for further distillation. The residue of the C2 bottom contains the topping heat treatment oil 225, and the treatment oil is transferred to a heat exchanger to raise the temperature of the topping oil 225 to about 375 - 415 °C before entering the third tower C3 (where it is further distilled). As the topping oil 225 is distilled, various distillates can be removed from the petroleum pitch 250. Specifically, the first intermediate fraction 235 corresponding to the carbon black feedstock and other components can be distilled off first. The second intermediate fraction 238 is extracted and may contain slightly heavier molecules. The heavy fraction 241 is distilled off last and may have the heaviest oils and components. Each of these distillates can be combined in various combinations and recycled through the system 200 for further heat treatment and distillation through the first intermediate fraction stream 237, the second intermediate fraction stream 240, and the heavy fraction stream 243, respectively. It should be noted that, as will be described later, the pitch 250 must be removed before recycling through the heat treatment. As can be seen from Figure 3A, all of the various distillate streams 224, 237, 240, and 243 can be combined in any combination or partial combination to form a single input for combining with the fresh decanted oil 203 that enters the heat treatment system 300 at the beginning of the pitch manufacturing process 200, or introduced into the C1 dehydrator as required. However, the various distillate streams 224, 237, 240, and 243 may be applied separately to the heat treatment system 300 for recycling.

[0036] The second embodiment of the pitch manufacturing system 200' is very similar as shown in Figure 3B, but the distillation procedure is different. Specifically, both the light fraction 222' and the middle fraction 238' may be distilled in the second column C2 heated to 350 - 415 °C. The obtained overhead 225' is then transferred to the fourth column C4, which is a flash column as described above. The heavy fraction 241' is distilled in this fourth column C4, resulting in the production of petroleum pitch 250'. Each of the light fraction 222', the middle fraction 238', and the heavy fraction 241' may be sent through the system 200' for recycling for further heat treatment and distillation of the light fraction stream 224, the middle fraction stream 240, and the heavy fraction stream 243, respectively, and may be combined or separately fed for reintroduction into the heat treatment system 300.

[0037] The third embodiment of the pitch manufacturing system 200”, shown in Figure 3C, is similar, but differs in that four columns are used in the dehydration and distillation process. In this case, the light fraction 222” is removed in the second column C2 fractionator during the production of the overhead 225”, the middle fraction 238” is removed from the third column C3 fractionator during the production of the soft pitch 227', and the heavy fraction 241” is removed from the fourth column C4 flash column during the production of the final petroleum pitch 250”. Each of the light fraction 222”, the middle fraction 238”, and the heavy fraction 241” may be sent through the system 200” for recycling for further heat treatment and distillation through the light fraction stream 224, the middle fraction stream 240, and the heavy fraction stream 243, respectively, and may be combined or separately fed for reintroduction into the heat treatment system 300. In a preferred embodiment, the light fraction 222', the middle fraction 238', and the heavy fraction 241' may have the characteristics shown in Table 5 below in a state derived from the second embodiment of the petroleum pitch manufacturing system 200', but distillates derived from other embodiments may be similar.

[0038]

Table 5

[0039] Heat treatment The present invention also includes heat treatment systems 300, 300' for heating the decanted oil of the starting material from coal tar pitch production 100, 100', 100" or petroleum pitch production 200, 200', 200". Each of the heat treatment systems 300, 300' uses a specific temperature and holding time to concentrate the material that has been heat treated to produce additional pitch that would not otherwise occur, thereby increasing the overall pitch production yield. These systems are intentionally interchangeable and it should be noted that they constitute alternative embodiments that are substitutable in any of the systems described herein.

[0040] Figure 4A shows a first embodiment of the heat treatment system 300. The input to the system 300 is from a pitch manufacturing system, for example, the heavy fraction 141 from the coal tar pitch manufacturing 100, the decanted oil 203 or the light fraction 222 from the petroleum pitch manufacturing 200, and a combination with the middle fraction 238 (or the first and second middle fractions 235, 238) and the heavy fraction 241. Regardless of the type, the input enters the heat treatment system 300 through the heat treatment input stream 310. This input material moves at a temperature in the range of 265 - 300 °C, a flow rate of about 4 - 9 MT / h, and a pressure of about 3.3 - 7.5 bar(g) (47.86 - 108.78 psi(g)); more preferably at a temperature in the range of 273 - 293 °C, a flow rate of about 5.5 - 9 MT / h, and a pressure of about 3.5 - 6.5 bar(g) (50.76 - 94.27 psi(g)); even more preferably at a temperature of about 278 - 288 °C, a flow rate of about 6.5 - 9 MT / h, and a pressure of about 3.8 - 5.5 bar(g) (55.11 - 79.77 psi(g)); most preferably at a temperature of about 283 °C, a flow rate of about 7 MT / h, and a pressure of about 4.5 bar(g) (65.27 psi(g)). It should be noted that the disclosed flow rates are not intended to be process limitations. For flow rates exceeding the above ranges, it is only necessary to recalculate the remaining variables according to this specification. The heat treatment input stream 310 may be a pipe or other conduit with a diameter of 50.8 mm (about 2 inches). The pump 311, for example, but not limited to, a pressure pump, is used in the heat treatment input stream 310 to move the input material passing through it and pressurize it to a pressure of about 6.2 - 11.7 bar(g) (89.92 - 169.69 psi(g)), more preferably a pressure of about 7.2 - 9.7 bar(g) (104.42 - 140.69 psi(g)), even more preferably a pressure of about 7.5 - 8.7 bar(g) (108.78 - 126.18 psi(g)), most preferably a pressure of about 8.8 bar(g) (127.63 psi(g)). The heat treatment input stream 310 sends the input material to the heat exchanger 312, and the heat exchanger raises the temperature of the input material to about 455 - 490 °C, more preferably about 470 - 490 °C, even more preferably about 475 - 490 °C, most preferably about 480 °C.The input material is moved from the heat exchanger 312 through line 313 (which may be heated) to the process heater 314, and preferably has a turbulent flow inside. This process heater 314 may be any type of heat reactor, such as, for example, but not limited to, induction heating. For example, in at least one embodiment, the process heater 314 may include a soaking coil 315 made of a thermally conductive material that promotes heat transfer, and the soaking coil 315 is in fluid communication with line 313. It should be understood that "thermally conductive" is intended to mean a material that transfers heat or promotes heat transfer, and is not intended to refer to a specific heating mechanism or regime. Although not essential, a turbulent flow of the input material stream is highly desirable within the process heater 314. There may be at least one power source 316 that provides, for example, alternating current (AC), direct current (DC), or other types of work, output, or energy to the process heater 314 to heat the heating coil 315. It should be noted that the application of energy may be of any known type, such as induction heating, flame, molten materials such as salts or metals, electric coils, etc. The only constraint is to apply heat in a specified amount. When the input material passes through the coil 315 and the process heater 314, it reaches a temperature of about 475 - 510 °C and a pressure of about 4.2 - 11.7 bar(g) (60.92 - 169.69 psi(g)), more preferably about 490 - 510 °C at about 5.2 - 9.7 bar(g) (75.42 - 140.69 psi(g)), even more preferably about 495 - 510 °C at about 5.5 - 8.7 bar(g) (79.77 - 126.18 psi(g)), and most preferably about 500 °C at about 6.8 bar(g) (98.63 psi(g)). The heated material exits the process heater 314 through the reactor product line 317 and moves to the reactor 320. The reactor product line 317 may have a smaller diameter than the previous input stream 310, for example 31.75 mm (about 5 / 4 inches) in the case of high-speed or turbulent flow. The reactor 320 may include a plurality of vessels, pipes or conduits through which the heated material passes to achieve a desired holding or residence time within the system 300 for heat treatment. Thus, the reactor 320 may have various lengths, shapes, dimensions and arrangements known to those skilled in the art to achieve the desired holding time. Without being bound by theory, the heated material is introduced into the reactor 320 and passes through it as a continuous stream, which generally moves with a uniform or substantially uniform plug flow and velocity within the limits of conventional piping or reservoir flow characteristics. However, preferably, in an elongated vessel, the length-to-diameter ratio is about 10:1.

[0041] For example, at least in this first embodiment, the reactor product line 317 is in fluid communication with the first vessel 321 and delivers the heated material to the first vessel 321. Since the heated material is at a high temperature, the internal volume of the first vessel 321 is under an inert gas 318 such as, but not limited to, nitrogen or argon gas so as to keep oxygen out of the first vessel 321. The first vessel 321 may have various shapes and / or diameters as described above and, in at least one embodiment, may have a length of about 16 m and a diameter of 0.3 m (about 14 inches). The vessel may also be insulated to retain the heat of the heated material and maintain the temperature at about 500°C. The first vessel 321 is also under a pressure of about 6 - 7 bar(g) (87 - 101.5 psi(g)), which, together with the above temperature, acts to keep the heated material in the liquid phase so that the material moves easily within the system 300. Although a truly adiabatic state is not practically possible, the temperature of the first vessel 321 (and, in particular, the corresponding segment of any other embodiment, including the contemplated single-vessel embodiment) is intended to have a substantial portion of the cross-section of the heated material passing through it maintained at a substantially constant level, which is appropriately identified as "substantially constant temperature". For the purposes of this preferred embodiment, plus or minus 30°C, more preferably plus or minus 10°C, and most preferably plus or minus 5°C are considered to be substantially uniform. Further, within practical limits, the heated material is intended to pass through the vessel as uniformly as possible in approximate plug flow.

[0042] The heated material enters the first vessel 321 from the bottom, and as additional heated material is delivered to the first vessel 321, the liquid level rises. The heated material moves through the first vessel 321 essentially in plug flow, such that as a result, all the molecules of the heated material move through the first vessel 321 at approximately the same speed as much as possible. Considering the mechanics of the fluid interaction with the inner surface of the vessel, achieving overall plug flow is unlikely, but it should be understood that the design of the vessel and the reactor 320 should, as a whole, achieve approximate plug flow as much as possible. Changes in the flow or flow rate within the first vessel 321 should be avoided. This is to enable the determination of the residence time of the molecules by keeping the movement of the molecules of the heated material within the reactor 320 at as uniform a speed as possible. The longer the residence time, the more the molecules of the heated material are exposed to a given reaction temperature, and the higher the risk of mesophase formation, which can cause coke formation. Thus, turbulent flow is useful for generating approximately uniform plug flow, but not to the extent that some molecules move rapidly while some are caught in vortices or local recirculation. This non-uniformity caused by excessive turbulent flow leads to non-uniformity in the heat treatment process 300 and is thus considered detrimental to the quality of the additional pitches 150, 250 formed by the process. As the heated material rises in the first vessel 321, vapor containing light chains 322 is generated ahead of the liquid. These light chains 322 may contain short carbon chain molecules that were unable to bond with other molecules or were broken as by-products during pitch generation. These light chains 322 can be removed from and recovered from the first vessel 321 by scrubbing or any other non-condensable gas recovery method for further processing. Without being bound by theory, this vapor material aids in the uniformity of the flow through the vessel. When the liquid level of the heated material rises to a predetermined outlet point of the first vessel 321, the material enters an intermediate reactor line 323 that is in fluid communication with the first vessel 321 and the second vessel 324. The intermediate reactor line 323 may be smaller than or approximately the same size as the first or second vessel 321, 323. In at least one embodiment, the intermediate reactor line 323 is 76.2 mm (about 3 inches) in diameter and preferably at most one-fifth the diameter of the first vessel 321. The line transfers the heated material from the first vessel 321 to the second vessel 324 for further retention.

[0043] In at least one embodiment, the second vessel 324 may be a vertical tube or other similar elongated structure having a diameter of 0.15 m (about 6 inches) and a length of about 5 m. The vessel is desirably sized to a minimum to suppress further reactions and insulated to conserve the heat of the material and maintain a temperature of about 500 °C. The heated material also moves through the second vessel 324 by pseudo-plug flow or plug flow (used interchangeably herein) as described above. The reactor product line 325 is in fluid communication with the second vessel 324 and transfers the heated material from the second vessel 324 to the heat exchanger 312. This may be the same heat exchanger 312 as described above or a different heat exchanger, but preferably the same. The reactor product line 325 may have a diameter similar to the reactor product line 317, for example 31.75 mm (about 1.25 inches), for high-speed transfer. The heated material exiting the reactor 320 and returning to the heat exchanger 312 may lose some heat while moving through the reactor 320 and at this point may have a temperature of about 465 - 510 °C, more preferably about 480 - 510 °C, even more preferably about 485 - 510 °C, and most preferably about 490 °C. The material heated at this point is cooled in the heat exchanger 312 to a temperature of about 275 - 325 °C and a pressure of about 3.7 - 11.7 bar(g) (53.66 - 169.69 psi(g)), more preferably about 280 - 315 °C and 5.2 - 9.7 bar(g) (75.42 - 140.69 psi(g)), even more preferably about 288 - 305 °C and 5.0 - 8.7 bar(g) (72.52 - 126.18 psi(g)), and most preferably about 300 °C and 6.5 bar(g) (94.27 psi(g)), and the pressure drops slightly. This heat-treated material contains additional pitch generated by exposure to the heat treatment. To obtain this additional pitch, the heat-treated material is carried away from the heat exchanger 312 by the product line 326 that intersects at various locations (varying depending on the embodiment and type of system) of the pitch production systems 100, 100’, 100”, 200’, 200’, 200” and delivered for additional pitch extraction by distillation and oil removal of the heat treatment product.Specifically, the production line 326 intersects the C2-C3 transfer lines 126 of the coal tar pitch production systems 100 and 100”, and may serve as an additional C3 feedstock as shown in FIGS. 2A and 2C respectively; it may enter the C1-C2 transfer line 115 of the coal tar pitch production system 100’ and serve as an additional C2 feedstock as shown in FIG. 2B; in the petroleum pitch production systems 200, 200’, 200” as shown in FIGS. 3A - 3C, it may enter directly into the first tower C1 where dehydration and subsequent distillation may be performed. In other embodiments, the heat-treated product may be introduced at different points along the pitch production system. In the coal tar embodiments, when the heat-treated material is combined with the topped tar 125, 125” or the dry tar 114, the temperature, flow rate, and pressure further decrease, and as a result, the C3 feedstock or C2 feedstock may be at approximately 358 - 375 °C, a flow rate of approximately 98 - 130 m. 3 / h, and a pressure of approximately 2.3 - 5.5 bar(g) (33.35 - 79.77 psi(g)), more preferably approximately 362 - 373 °C, approximately 99 - 120 m 3 / h, and approximately 2.5 - 4.9 bar(g) (36.26 - 71.07 psi(g)), even more preferably approximately 364 - 370 °C, approximately 99 - 110 m 3 / h and approximately 2.8 - 4.5 bar(g) (40.61 - 65.27 psi(g)), most preferably approximately 367 °C, approximately 99 m 3 / h and approximately 3.5 bar(g) (50.76 psi(g)). In any continuous process, it should be noted that other oils contained in the heat-treated material need to be separated from the pitch produced by the heat treatment before reintroducing these remaining other oils into the heat treatment system for further processing and additional pitch production. Without being bound by theory, it is generally understood that since there is a high likelihood of mesophase or coke formation during additional heat treatment, when heat-treating pitch materials, the pitch should be separated by distillation before reintroducing it into the heat treatment.

[0044] In the heat treatment system 300, the residence time of the heated material may be interchangeably referred to as "residence time" or "holding time". This is the duration of the heat treatment process and can be defined as the time required for the heated material to form a circuit from the heat exchanger 312 through the reactor 320 and back to the heat exchanger 312 for cooling. This circuit defines the time during which the heated material is exposed to a high temperature of about 500 °C, i.e., the time during which care must be taken to avoid mesophase formation. The residence time may vary depending on the exact temperature and pressure of the system, and the higher the temperature or pressure, the shorter the corresponding residence time. In at least one embodiment, the heat treatment system 300 includes the step of heating the input material at a temperature of about 500 °C and a pressure of about 6.0 - 7.0 bar(g) (87 - 101.5 psi(g)) for about 3 - 7 minutes, preferably 7 minutes. The various distillation fractions from the pitch production systems 100, 100’, 100” are fairly well defined and characterized as described above. Thus, the consistency of the coal tar starting material, the heavy fraction 141, means that although the inherent relationships between the various parameters are somewhat complex, the holding time and reaction temperature are relatively predictable. The following are some representative ranges of the operating parameters of the heat treatment process for the heavy fraction.

[0045]

Table 6

[0046] Regarding the heat treatment of the coal tar heavy fraction, additional calculations of the parameters for predicting the pitch yield at various flow rates are shown in Table 7 below. This is based on the same complex relationships as above.

Table 7

[0047] A second embodiment of the heat treatment system 300’ is shown in FIG. 4B. This can also be used in connection with any of the pitch manufacturing systems. Without such heat treatment, the pitch can be produced in an amount of about 15-25% of the initial decanted oil 203. When the heat treatment described herein is used in system 300’, the yield increases by about 25-30%, and the total pitch yield is about 40-50%. If the distillate is recycled and further heat treated, the total pitch yield can increase to about 60-80%, depending on the quality levels of the starting materials and the distillate. In this embodiment of the heat treatment system 300’, the components of the reactor 320’ may be slightly different from those described above so that some of the operating parameters of the entire heat treatment system 300’ can be different. As a non-limiting example of a pre-test plan, the feedstock can be at a temperature of about 49-104 °C, a flow rate of about 7.2-13.1 MT / h, and a pressure of about 1.4-4.8 bar(g) (20-70 psi(g)) when entering the heat treatment system 300’. The pressure pump 311 can be a high-pressure supply pump operating at about 2 gpm at 20.7 bar(g) (300 psi(g)), although other speeds and pressures are contemplated. The pressure pump 311 can increase the flow rate of the feedstock to about 20.3 MT / h and the pressure to about 13.8-18.0 bar(g) (200-260 psi(g)) before the feedstock enters the heat exchanger 312. The heat exchanger 312 raises the temperature of the feedstock to about 413-430 °C by passing a hotter component (e.g., the heated product from downstream in system 300’) through the heat exchanger 312. From there, the material is transferred to the process heater 314, where it is further heated to a temperature of about 465-500 °C depending on the characteristics of the feedstock.

[0048] As in the foregoing embodiments, the process heater 314 may be an induction heater or a soaking coil, and may be driven by any suitable power source 316, such as a display converter operating at an output of 1 MW, but is not limited thereto. There are a plurality of connections from the power source 316 to the process heater 314 and / or the coil 315 therein, which may be at regular intervals, such as every three turns of the coil 315. However, any configuration that provides sufficient power to the process heater 314 is contemplated. The process heater 314 may have a coil 315 of sufficient length therein to maintain and heat the input material to a desired target temperature before the input material leaves the process heater 314 through the reactor outlet line 317. The reactor outlet line 317 is in fluid communication with the first vessel 321' of the reactor 320'. This first vessel 321' may be a plug flow reactor, as described above. The heated material enters the first vessel 321' from the bottom and rises at a substantially uniform rate to avoid turbulent flow and maintain the same flow rate for all molecules of the heated material. The first vessel 321' may be in the range of about 6.9 - 13.8 bar(g) (100 - 200 psi(g)), preferably 6.9 - 12.1 bar(g) (100 - 175 psi(g)), and further may be under an inert gas 318 such as nitrogen or argon to limit the oxygen present in the first vessel 321' in view of the high temperature. The heated material may preferably be about 482.2 - 496 °C when it enters the first vessel 321'. The material may lose some heat, for example about 20 - 30 °C, as it moves upward in the first vessel 321'.

[0049] In an embodiment, the first vessel 321’ may include a disengagement zone 328 defined along a part thereof, preferably near the top of the vessel 321’. The disengagement zone 328 has a larger diameter (and thus a larger internal volume) than the rest of the first vessel 321’. In an embodiment, this additional space may separate the vapor containing small hydrocarbon molecules that did not produce pitches 150, 250 in the pitch manufacturing process from the liquid and remove it as LC1 322’. This extraction may also limit foaming (which is undesirable as it generates turbulent flow). These LC1 322’ rise to the top of the first vessel 321’. The LC1 322’ may be at a temperature of about 437.8 - 443.3 °C and is preferably removed from the first vessel 321’ at a point above the disengagement zone 328. The removed LC1 322’ may be sent to a condenser where it is condensed and / or pyrolyzed in an anti-contamination device. LC2 333 may be generated as foam and / or vapor in the disengagement zone 328. LC2 333 contains non-condensable gas and can be removed from the disengagement zone 328 of the first vessel 321’ and transferred to the second vessel 324’. In a preferred embodiment, the additional light chain LC2 333 enters the second vessel at the longitudinal center point of the second vessel 324’. As the liquid level of the heated material in the first vessel 321’ rises to a certain level, the heated material of the liquid exiting the first vessel 321’ is also transferred through the intermediate reactor line 323’ to the second vessel 324’. The heated material from the first vessel 321’ is combined with the LC2 333 of the second vessel 324’ for additional plug flow through the second vessel 324’. The second vessel 324’ is also under an inert gas 318, and the inert gas may be the same as or different from the gas in the first vessel 321’. The heated material is at substantially the same temperature and pressure inside the second vessel 324’ as inside the first vessel 321’, although some loss may occur as the heated material passes through the reactor 320’. The vapor that accumulates at the top of the second container 324' may be removed as the light chain LC3 340, and then merged with the LC1 322' and returned to the liquid by condensation. The above-mentioned merged LC1 322' and LC3 340 may contain naphtha, and the naphtha may be purified and separated by a naphtha purification device for sale or further use. The remainder of the LC1 322' and LC3 340 may be pyrolyzed as described above. The bottom of the second container 324' contains the heat-treated material, which is then returned to the heat exchanger 312 through the reactor product line 325 for cooling. After cooling, depending on the embodiment and the type of system, the heat-treated material returns to the pitch manufacturing systems 100, 100', 100", 200', 200', 200" and has the same intersections as described above. Alternatively, the heat-treated material may be returned from the reactor 320' to the column C1 and the temperature may be reduced by conventional means. The residence time of the heat treatment process using the second embodiment of the system 300' varies at least according to the use temperature. For example, a heated coal tar material at a temperature of about 482.2 - 500 °C passes through the heat treatment process 200' with a holding time of about 10 - 20 minutes, whereas in the case of a temperature of about 537.8 °C, it may only last for a holding time of about 5 minutes. In the case of even lower reaction temperatures, a holding time of up to 60 minutes is possible. These are merely a few non-limiting examples.

[0050] It has been clarified that by passing the input material once through the heat treatment system 300' of the present invention, the pitch yield increases 2.5 times, and a total pitch yield of about 40% is obtained compared to a pitch yield of about 15% without heat treatment. Additional pitches 150, 250 may occur even not multiple times by recycling the input material and passing it through the heat treatment system 300' at least once. However, there is a risk of mesophase accumulation as the pitch load increases. Therefore, in some embodiments, it may be beneficial or even necessary to remove the pitches 150, 250 obtained by passing the heat treatment product through distillation and not recycle it back to the heat treatment system 300'. This limits or prevents the formation of mesophase in the pitches 150, 250.

[0051] Compared with the starting materials of the coal tar 102, the decanted oil 203 has large variations in composition and concentration between batches. This causes complexity in the relationship between temperature, holding time, and pressure. However, the desired pitch parameters of >47% coke value and <0.7% mesophase control the upper and lower limits of the acceptable increase in pitch yield. If the increase is too large or too small, it will produce either a pitch with insufficient coke value or too much mesophase. From the above limits, the relationship between the holding time and temperature in the heat-treated decanted oil can be described by the following equation. 25 = 0.1((1.8×T r + 32) - T c ) + 0.1(R t ) In the formula, 25 is the percentage increase in yield relative to the yield obtained without heat treatment (determined by the desired pitch parameters of at least 47% coke value and 0.7% or less mesophase); T r is the reaction temperature in degrees Celsius; T c is 653, and R t is the holding time in minutes. The first 0.1 indicates the increase in yield (%) per degree Fahrenheit, and the second 0.1 indicates the increase in yield (%) for each additional minute. Depending on the constraints of a specific system, the above formula can also be expressed as follows for the holding time R t or the reaction temperature T r respectively. R t = 250 - (1.8×T r + 32) + T c

Equation

[0052] In the preferred embodiment described in the present invention, in the case of heat treatment of the decanted oil 203, T r the reaction temperature is in the range of 454 to 483 °C, and R tThe holding time ranges from 3 to 25 minutes. Interestingly, a 25% increase in yield (corresponding to "25" and "250" in the above formula) applies equally well to the decanted oil 203 starting material having an API gravity of -5 to 0. Yields higher or lower than the above tend to result in either an unacceptable level of mesophase or an insufficient coke value. As generally understood in the petroleum industry, the relationship between API gravity and specific gravity (SG) is as follows: [Number]

[0053] Therefore, the specific gravity of the decanted oil 203 in the petroleum pitch production 200" may vary depending on the operating parameters of the system 200", but the above formula applies equally well to various specific gravities of the decanted oil 203 starting material. The above formula for predicting the reaction temperature and reaction time provides the following representative ranges for the operating parameters of the heat treatment process of petroleum distillates using the heat treatment system 300' disclosed herein for an average reactor gradient.

[0054] [Table 8]

[0055] The above features and other features of the preferred embodiments of the present specification can be illustrated by the following non-limiting examples. [Examples]

[0056] The following examples provide experimental data derived in the determination and / or testing of specific parameters of the pitch production system and / or heat treatment system described herein. References to specific embodiments are indicated as appropriate.

[0057] Example 1 Determination of Heavy Fraction Removal Rate In order to determine the maximum flow rate at which heavy fraction 141 can be removed from the third column C3 of the above-described coal tar pitch production system 100 without impairing the overall performance of the pitch production system 100, an experiment was conducted. The heat treatment of the heavy fraction 141 is important for the separation of B(a)P and for maintaining the high softening point (e.g., about 130 °C, according to the Mettler method) of the resulting pitch 150. Assuming the goal of increasing the pitch yield by 5%, the flow rate required for the heat treatment system 300 was calculated as follows. Assuming an annual tar production of about 300,000 MT / year, 5% of this figure is about 15,000 MT / year, which is the additional pitch required. Dividing this rate of 15,000 MT / year by the predicted yield of 30% gives about 50,000 MT / year, and dividing by 300 operating days / year, the flow rate of the heat treatment system 300 to achieve an additional 5% pitch yield is 166 MT / day or 7 MT / hour. The coal tar pitch production system 100 can typically be operated at a rate of about 31.5 MT / hour for pitch production. For the heavy fraction 141 to pass through the heat treatment process 300 at a rate of about 7 MT / hour, it is necessary to similarly reduce the pitch production rate. From this, a test was conducted to determine whether an additional pitch yield can be achieved without disturbing the existing pitch production process if a sufficient reduction in the pitch production rate is achieved. To test this, the heat treatment draw of the heavy fraction 141 was experimentally simulated by partially closing the valve from the third column C3 to the distillate line 142 in various amounts. This restricted the flow rate of the oil draw. Starting from 55% closed (normal position), four valve positions with different closing rates were tested, namely 35% closed, 30% and 25% closed. For each valve position, the flow rate was measured and the simulated draw of the heavy fraction 141 was monitored. The heat load was also measured to monitor the effect of the system, and the softening point (Mettler) of the resulting pitch was measured as part of the quality control of the pitch production process. Other items were also measured as controls. The B(a)P and distillation interval were also measured to deepen the understanding of the separation effect. The results of these tests are summarized in Table 9 below.

[0058]

Table 9

[0059] This result indicates that while maintaining the normal operation of the pitch manufacturing system 100, the heat treatment flow rate of the heavy fraction 141 can be reduced. This is demonstrated by the impact of the flow rate reduction on the heat load. The process conditions at 55% show a part of the normal fluctuations while being standard operating conditions. This can be seen from the fact that the temperature of the second intermediate fraction tray is different from the normal temperature of 210°C. Although the normal operation is maintained, it should be noted that the second intermediate fraction cooling loop exceeds the maximum. For this reason, the temperature of the second intermediate fraction tray increases as the experiment progresses, which leads to an increase in the yield of the first intermediate fraction. The fact that the second intermediate fraction cooling reaches the maximum is a problem, especially when additional cooling load is removed due to the reduction of the heavy fraction rate. Generally, both the temperature control and the experimental results indicate that the cooling of the tower is insufficient. This effect increases when additional flow is removed from the control loop. Therefore, additional cooling may be required to overcome the loss of cooling load or to reduce the energy input. The above results together indicate that heat treatment using a flow rate of 7 MT / h is possible, but additional cooling may be required for the production of low-PAH creosote.

[0060] Example 2 Determination of Reactor Temperature To further design the full-scale application of the heat treatment system 300, several basic cases were evaluated, particularly regarding the temperature of the process heater 314. Here, temperatures of 420, 445, 471, 497, and 522 °C were evaluated. The lower limit of this evaluation is based on the results of preliminary autoclave tests showing the limit of reactivity. The upper limit is based on the autoignition temperature of the heavy fraction (measured value 542 °C). For safety reasons, the final reactor temperature is limited to 522 °C. Previous experiments have shown that the heavy fraction can be processed at a temperature of 550 °C for 5.2 minutes without forming mesophase or coke. Furthermore, from past experiments on long holding times, the data shown in Table 10 below were obtained.

[0061]

Table 10

[0062] Based on these past data, a kinetics-based simulation was determined using a heavy fraction flow rate of 7 MT / h and a desired pitch yield of 30% overall, as identified in Example 1. These kinetic calculations provide the data shown in Table 11 below.

[0063]

Table 11

[0064] The maximum holding time used in the laboratory was 5.2 minutes. As can be seen from Table 11, most of the calculated results far exceeded this time. Therefore, these kinetic calculations may overestimate the reaction rate.

[0065] Example 3 Tests at Various Temperatures and Holding Times - Coal Tar Tests were conducted to evaluate the feasibility of heat treating the heavy fraction to convert it to pitch. These initial experiments were carried out at various temperatures from 365 to 510 °C and holding times in the range of 4.5 minutes to 2 hours. Reaction constants were derived from these results. To measure whether the reaction is endothermic, two additional adiabatic experiments were carried out to ensure that the measured reactor temperature was due to the internal heavy fraction and not the oven temperature by insulating the reactor well. The experiments were carried out using a plug flow reactor. All experiments were conducted in the same general manner. The heavy fraction was placed in a feed tank and pumped through a reactor. The reactor was housed in an oven with a preheater, and reactors of different sizes in the range of 299 - 330 mL were also used. The heavy fraction was pumped through the reactor to obtain a given temperature for a predetermined holding time. After the oven, the heavy fraction was passed through a cooling coil to lower the temperature and then advanced to a waste tank or a sample tank. After the temperature of the reactor had stabilized, sample recovery was carried out. In most experiments, 1000 g of samples were recovered. To ensure that the heavy fraction was liquid throughout the experiment, heat tracing was added to all pipes. The feed tank was maintained at 100 °C, the cooling coil at 180 °C, and the sample and waste tanks at 150 °C. Temperature sensors were installed at multiple locations on the preheater and the reactor to track the temperature profile of the heavy fraction. During the experiment, a nitrogen purge flow was used to create an inert atmosphere. The experiments were carried out at high pressure to overcome the vapor pressure of the heavy fraction. The experiments were generally carried out at about 6.9 bar(g) (100 psi(g)). The resulting heat-treated oil needed to be distilled to confirm the pitch yield of the samples. For distillation, a vacuum distillation setup was prepared. Each distillation was carried out with approximately 400 g of sample in a round-bottom flask. The distillation column used was a Vigreux column 1 m in length. All samples were distilled under a full vacuum. The bottom temperature was set at 250 °C at the start of the distillation and then gradually increased until sufficient oil had been distilled to obtain the expected yield. When the pitch was not within the appropriate melting point range of 105 - 130 °C, the distillation was carried out again from the beginning. During the second distillation, the bottom temperature was increased or decreased so that more or less distillate was removed, respectively, to produce a pitch with a higher or lower melting point. Several types of analyses were performed on the heat treatment oil, pitch, and distillate. The heat treatment oil was measured by Fourier transform infrared spectroscopy (FTIR) to calculate the aromaticity. The melting point of the pitch was measured. The melting point needed to be 105 - 130 °C to be acceptable. The QI of the pitch was measured. It was desirable for the QI to be as low as possible. The pitch was also analyzed for B(a)P. Gas chromatography (GC) was performed on the distillate to calculate the conversion rate of the compounds in the heavy fraction and to calculate the reaction constant. A portion of the oil was also measured by gas chromatography - mass spectrometry (GCMS) and compared with the results of GC. The data of various tests are summarized in Table 12 below.

[0066]

Table 12 - 1

[0067]

Table 12 - 2

[0068] These data show the increase in the pitch yield (%) with respect to the tested temperature and holding time, suggesting that the heat treatment of the heavy fraction can increase the pitch yield. The results of the adiabatic experiment for testing whether the reaction is endothermic are shown in Table 13 below.

Table 13

[0069] Example 4 Tests at Various Temperatures and Holding Times - Petroleum For the heat treatment of petroleum-derived decanted oil, various laboratory-scale tests were carried out at various temperatures and holding times. The raw decanted oil was subjected to heat soaking in a constant autoclave at 13.8 bar(g) (200 psi(g)). As the decanted oil was heated to the desired temperature, a slight lag time occurred. After heat treatment at the desired temperature, the product was quenched to stop the heat soaking and limit mesophase formation. The pitch produced during the heat treatment process was isolated by distillation to remove the unreacted decanted oil, and the resulting pitch was characterized by coke value and mesophase. The results of these experiments are summarized in Table 14 below.

[0070]

Table 14

[0071] In each of the above experiments, an acceptable pitch was produced, characterized by a coke value of >47% and a mesophase of <0.7%. In the described preferred embodiments, since numerous changes, modifications and variations can be made in the details, it is intended that the above description and the matters described in the accompanying drawings be construed in an illustrative rather than a limiting sense. Accordingly, the scope of the present invention should be determined by the appended claims and their legal equivalents. The present invention has been described above.

Claims

Claim 1 A method for inducing pitch from a preselected starting material, comprising: selecting a starting material from the group consisting of (i) petroleum decanted oil and (ii) coal tar heavy distillate oil; introducing the starting material into a conduit at least partially constructed of a conductive material that promotes heat transfer in a flowable liquid phase; applying heat in a controlled manner to the thermally conductive portion of the conduit containing the starting material to raise the temperature of the starting material to 459 - 535 °C at a pressure of about 3.2 - 20.7 bar(g) (46 - 300 psi(g)); maintaining the approximate isothermal flow of the starting material through at least a portion of the thermally conductive portion of the conduit at a substantially constant temperature for a time sufficient to convert a portion of the starting material to pitch while limiting the mesophase formation in the combined stream to 0.7% or less; lowering the temperature of the combined stream to 275 - 385 °C; separating the pitch from the combined stream to obtain a pitch yield of at least 25% with respect to (i) the petroleum decanted oil and at least 15% with respect to (ii) the coal tar heavy distillate oil; A method comprising the above steps. Claim 2 The method according to claim 1, wherein the starting material is a coal tar heavy distillate oil heated to a temperature in the range of 475 - 510 °C at a pressure in the range of about 3.2 - 10.7 bar(g) (46 - 155 psi(g)). Claim 3 The method according to claim 2, wherein the approximate isothermal flow occurs at the substantially constant temperature for a time in the range of 3.0 - 49.2 minutes. Claim 4 The method according to claim 2, wherein the pitch yield is in the range of 15 - 45%. Claim 5 The method according to claim 2, wherein the temperature is about 475 °C, the pressure is about 3.2 bar(g) (about 46.2 psi(g)), the approximate isothermal flow occurs at the substantially constant temperature for about 49.2 minutes, resulting in about 45% pitch. Claim 6 The method according to claim 2, wherein the temperature is about 510 °C, the pressure is about 10.7 bar(g) (about 155 psi(g)), the approximate isothermal flow occurs at the substantially constant temperature for about 3 minutes, resulting in about 15% pitch. Claim 7 The method according to claim 1, wherein the starting material is a coal tar-based heavy distillate oil heated to a temperature in the range of 490 to 510 °C at a pressure in the range of about 4.2 to 8.7 bar(g) (60.7 to 126 psi(g)).

8. The method according to claim 7, wherein the quasi-isothermal flow occurs over a time in the range of 4.3 to 23.6 minutes at the substantially constant temperature.

9. The method according to claim 7, wherein the pitch yield is 20 to 40%.

10. The method according to claim 7, wherein the temperature is about 490 °C, the pressure is about 4.2 bar(g) (about 60.7 psi(g)), the quasi-isothermal flow occurs for about 23.6 minutes at the substantially constant temperature, and about 40% pitch is produced.

11. The method according to claim 7, wherein the temperature is about 510 °C, the pressure is about 8.7 bar(g) (about 126 psi(g)), the quasi-isothermal flow occurs for about 4.3 minutes at the substantially constant temperature, and about 20% pitch is produced.

12. The method according to claim 1, wherein the starting material is a coal tar-based heavy distillate oil heated to a temperature in the range of 495 to 510 °C at a pressure in the range of about 4.5 to 7.7 bar(g) (65.1 to 111.5 psi(g)).

13. The method according to claim 12, wherein the quasi-isothermal flow occurs over a time in the range of 5.7 to 16.3 minutes at the substantially constant temperature.

14. The method according to claim 12, wherein the pitch yield is in the range of 25 to 35%.

15. The method according to claim 12, wherein the temperature is about 495 °C, the pressure is about 4.5 bar(g) (about 65.1 psi(g)), the quasi-isothermal flow occurs for about 16.3 minutes at the substantially constant temperature, and about 35% pitch is produced.

16. The method according to claim 12, wherein the temperature is about 510 °C, the pressure is about 7.7 bar(g) (about 111.5 psi(g)), the quasi-isothermal flow occurs for about 5.7 minutes at the substantially constant temperature, and about 25% pitch is produced.

17. The method according to claim 1, wherein the starting material is a coal tar-based heavy distillate oil heated to a temperature of about 500 °C at a pressure of about 5.8 bar(g) (about 83.9 psi(g)).

18. The method according to claim 17, wherein the quasi-isothermal flow occurs for about 7.4 minutes at the substantially constant temperature, and about 30% pitch is produced.

19. The starting material is a petroleum decanted oil having an API gravity in the range of -5 to 0, and the starting material is subjected to a pressure in the range of about 5.5 to 20.7 bar(g) (80 to 300 psi(g)) at a substantially constant temperature over a time according to the following equation: 25 = 0.1((1.8×T r + 32) - T c ) + 0.1(R t ) [wherein, T r is the reaction temperature in degrees Celsius, T c is 653, R t is the retention time in minutes], which results in an increase in pitch yield of at least 25%, and the pitch has a coke value of at least 47% by mass, the method according to claim 1.

20. The method according to claim 1, wherein the starting material is a petroleum decanted oil heated to a temperature in the range of 459 to 496 °C at a pressure in the range of about 5.5 to 20.7 bar(g) (80 to 300 psi(g)).

21. The method according to claim 20, wherein the pseudo-isothermal flow occurs over a time in the range of 1 to 25 minutes at the substantially constant temperature.

22. The method according to claim 20, wherein the pitch yield is in the range of 40 to 54.3%, and the coke value is in the range of 47.3 to 50.5% by mass.

23. The method according to claim 20, wherein the temperature is about 496 °C, and the pseudo-isothermal flow occurs for about 1 minute at the substantially constant temperature to produce about 54% pitch having a coke value of about 47.3% by mass.

24. The method according to claim 20, wherein the temperature is in the range of 468 to 482 °C, and the pseudo-isothermal flow occurs for about 10 minutes at the substantially constant temperature to produce pitch having a coke value in the range of 47.3 to 50.5% by mass in the range of about 43 to 54.3%.

25. The method according to claim 20, wherein the temperature is in the range of 459 to 471 °C, and the pseudo-isothermal flow occurs for about 20 minutes at the substantially constant temperature to produce pitch having a coke value in the range of 47.7 to 50.1% by mass in the range of about 40 to 47.5%.

26. The method according to claim 1, wherein the conduit further comprises a heat conduction section through which the starting material flows in turbulent flow and a reactor section through which the starting material flows in pseudo-isothermal flow.

27. The method according to claim 26, wherein the temperature of the starting material is increased in the heat conduction section and maintained at a substantially uniform level in the reactor section.

28. The method according to claim 1, further comprising an additional step of heating the starting material before introduction into the conduit.

29. The method according to claim 28, wherein the heating step and the temperature reduction step are achieved simultaneously in a common heat exchanger.

30. A pitch product having a mesophase content of less than 0.7%, derived from a starting material selected from the group consisting of (i) petroleum-based decanted oil and (ii) coal tar-based heavy distillate oil, introducing the starting material into a conduit at least partially constructed of a conductive material that promotes heat transfer in a flowable liquid phase; applying heat in a controlled manner to the thermally conductive portion of the conduit containing the starting material to raise the temperature of the starting material to 459 - 535 °C at a pressure of about 3.2 - 20.7 bar(g) (46 - 300 psi(g)); maintaining an approximate isothermal flow of the starting material through at least a portion of the thermally conductive portion of the conduit at a substantially constant temperature for a time sufficient to convert a portion of the starting material to pitch; lowering the temperature of the combined stream to 275 - 385 °C; separating the pitch portion from the combined stream; A pitch product derived by a method comprising. **Claim 31** The method according to claim 30, wherein the starting material is a coal tar-based heavy distillate oil heated to a temperature in the range of 475 - 510 °C at a pressure in the range of about 43.2 - 10.7 bar(g) (46 - 155 psi(g)). **Claim 32** The method according to claim 31, wherein the approximate isothermal flow occurs at the substantially constant temperature for a time in the range of 3.0 - 49.2 minutes. **Claim 33** The method according to claim 31, wherein the yield of the pitch is in the range of 15 - 45%. **Claim 34** The method according to claim 31, wherein the temperature is about 475 °C, the pressure is about 3.2 bar(g) (about 46.2 psi(g)), the approximate isothermal flow occurs at the substantially constant temperature for about 49.2 minutes, and produces about 45% pitch. **Claim 35** The method according to claim 31, wherein the temperature is about 510 °C, the pressure is about 10.7 bar(g) (about 155 psi(g)), the approximate isothermal flow occurs at the substantially constant temperature for about 3 minutes, and produces about 15% pitch. **Claim 36** The method according to claim 30, wherein the starting material is a coal tar-based heavy distillate oil heated to a temperature in the range of 490 - 510 °C at a pressure in the range of about 4.2 - 8.7 bar(g) (60.7 - 126 psi(g)). **Claim 37** The approximate isothermal flow occurs at the substantially constant temperature over a time range of 4.3 to 23.6 minutes, according to the method of claim 36. **Claim 38** The pitch yield is 20 to 40%, according to the method of claim 36. **Claim 39** The temperature is about 490 °C, the pressure is about 4.2 bar(g) (about 60.7 psi(g)), and the approximate isothermal flow occurs at the substantially constant temperature for about 23.6 minutes to produce a pitch of about 40%, according to the method of claim 36. **Claim 40** The temperature is about 510 °C, the pressure is about 8.7 bar(g) (about 126 psi(g)), and the approximate isothermal flow occurs at the substantially constant temperature for about 4.3 minutes to produce a pitch of about 20%, according to the method of claim 36. **Claim 41** The starting material is a coal tar-based heavy distillate oil heated to a temperature in the range of 495 to 510 °C at a pressure in the range of about 4.5 to 7.7 bar(g) (65.1 to 111.5 psi(g)), according to the method of claim 30. **Claim 42** The approximate isothermal flow occurs at the substantially constant temperature over a time range of 5.7 to 16.3 minutes, according to the method of claim 41. **Claim 43** The pitch yield is in the range of 25 to 35%, according to the method of claim 41. **Claim 44** The temperature is about 495 °C, the pressure is about 4.5 bar(g) (about 65.1 psi(g)), and the approximate isothermal flow occurs at the substantially constant temperature for about 16.3 minutes to produce a pitch of about 35%, according to the method of claim 41. **Claim 45** The temperature is about 510 °C, the pressure is about 7.7 bar(g) (about 111.5 psi(g)), and the approximate isothermal flow occurs at the substantially constant temperature for about 5.7 minutes to produce a pitch of about 25%, according to the method of claim 41. **Claim 46** The starting material is a coal tar-based heavy distillate oil heated to a temperature of about 500 °C at a pressure of about 5.8 bar(g) (about 83.9 psi(g)), according to the method of claim 30. **Claim 47** The approximate isothermal flow occurs at the substantially constant temperature for about 7.4 minutes to produce a pitch of about 30%, according to the method of claim 46. **Claim 48** The starting material is a petroleum-based decanted oil having an API gravity in the range of -5 to 0, and the starting material is subjected to a pressure in the range of about 5.5 to 20.7 bar(g) (80 to 300 psi(g)) at a substantially constant temperature over a time according to the following formula: 25 = 0.1((1.8×T r + 32) - T c ) + 0.1(R t ) [wherein, T r is the reaction temperature in degrees Celsius, T c is 653, R t is the retention time in minutes], which results in an increase in pitch yield of at least 25%, and the pitch has a coke value of at least 47% by mass, the method according to claim 30.

49. The method according to claim 30, wherein the starting material is a petroleum decanted oil heated to a temperature in the range of 459 to 496 °C at a pressure in the range of about 5.5 to 20.7 bar (g) (80 to 300 psi (g)).

50. The method according to claim 49, wherein the quasi-isothermal flow occurs over a time in the range of 1 to 25 minutes at said substantially constant temperature.

51. The method according to claim 49, wherein the pitch yield is in the range of 40 to 54.3% and the coke value is 47.3 to 50.5% by mass.

52. The method according to claim 49, wherein the temperature is about 496 °C, the quasi-isothermal flow occurs for about 1 minute at said substantially constant temperature, and about 54% of the pitch having a coke value of about 47.3% by mass is produced.

53. The method according to claim 49, wherein the temperature is in the range of 468 to 482 °C, the quasi-isothermal flow occurs for about 10 minutes at said substantially constant temperature, and the pitch having a coke value in the range of 47.3 to 50.5% by mass is produced in the range of about 43 to 54.3%.

54. The method according to claim 49, wherein the temperature is in the range of 459 to 471 °C, the quasi-isothermal flow occurs for about 20 minutes at said substantially constant temperature, and the pitch having a coke value in the range of 47.7 to 50.1% by mass is produced in the range of about 40 to 47.5%.

55. The method according to claim 30, wherein the conduit further comprises a heat conduction section through which the starting material flows in a turbulent flow and a reactor section through which the starting material flows in a quasi-isothermal flow.

56. The method according to claim 55, wherein the temperature of the starting material is increased in the heat conduction section and maintained at a substantially uniform level in the reactor section.

57. The method according to claim 30, further comprising an additional step of heating the starting material before introducing it into the conduit.

58. The method according to claim 57, wherein the heating step and the temperature reduction step are achieved simultaneously in a common heat exchanger.

59. The method according to claim 1, wherein the separation of the pitch portion from the combined stream is achieved by distillation.

60. A continuous method for deriving pitch from a preselected starting material, comprising the step of recycling the combined stream according to claim 1 after separating the pitch portion as the starting material.

61. A heat treatment system for inducing pitch from a starting material selected from the group consisting of (i) petroleum decanted oil and (ii) coal tar heavy distillate oil, wherein the heat treatment system comprises a conduit having at least one component section, said at least one component section being at least partially composed of a conductive material that promotes heat transfer, said conduit having a first end that may selectively include at least a portion of said conductive material portion of said conduit, a second end, and an intermediate portion therebetween, said conductive portion of said conduit having a maximum temperature of 459 - 535 °C and a maximum pressure of about 3.2 - 20.7 bar(g) (46 - 300 psi(g)), said intermediate portion of said conduit being sized and shaped to maintain a substantially constant temperature of a continuous approximate equal flow of said starting material for a time sufficient to convert at least a portion of said starting material to pitch while limiting mesophase formation in the combined stream to 0.7% or less, and obtaining a pitch yield of (i) at least 25% with respect to said petroleum decanted oil and (ii) at least 15% with respect to said coal tar heavy distillate oil, a heat treatment system.

62. The heat treatment system according to claim 61, wherein said intermediate portion of said conduit further includes a reactor section.

63. The heat treatment system according to claim 61, wherein said conductive section further includes a heating section.

64. The heat treatment system according to claim 63, wherein said heating section is induction heated.

65. The heat treatment system according to claim 63, wherein said heating section is an elongated coil conduit.

66. The heat treatment system according to claim 63, wherein said heating section is sized to induce turbulent flow of said starting material therethrough.

67. The heat treatment system according to claim 62, wherein said reactor section further includes at least one holding vessel for maintaining said starting material at a substantially constant temperature.

68. The heat treatment system according to claim 62, wherein said reactor section further includes at least one holding vessel for maintaining an approximate equal flow of said starting material therethrough.

69. The heat treatment system according to claim 62, wherein said reactor section further includes a plurality of vessels.

70. The heat treatment system according to claim 62, wherein the reactor section further includes at least one elongated cylindrical container.

71. The heat treatment system according to claim 62, wherein the reactor section further includes an inert atmosphere.

72. The heat treatment system according to claim 62, further including a space for recovering non-condensable gas.

73. The heat treatment system according to claim 61, further including a heat exchanger for exchanging thermal energy from the combined stream to the starting material before introduction into the conduit.

74. The heat treatment system according to claim 69, wherein the plurality of containers further includes a first and a second container, and the first container is larger in volume than the second container.

75. The heat treatment system according to claim 74, wherein the second container is of a minimum size.

76. The heat treatment system according to claim 68, wherein the container is elongated and has a length-to-diameter ratio of 10:1 or more.

77. The heat treatment system according to claim 61, wherein the substantially constant temperature is within a range of plus or minus 30 °C.

78. The heat treatment system according to claim 76, wherein the substantially constant temperature is within a range of plus or minus 10 °C.

79. The heat treatment system according to claim 76, wherein the substantially constant temperature is plus or minus 5 °C.

80. A distillation system for inducing pitch having a mesophase content of 0.7% or less from petroleum decant oil to increase the pitch yield by at least 25%, the heat treatment system according to claim 61 for recovering and treating the petroleum decant oil to induce pitch therefrom, and at least one distillation column in fluid communication with the heat treatment system for receiving the heat-treated petroleum decant oil and fractionating it into component fractions containing pitch. The distillation system includes.

81. The distillation system according to claim 80, further including a plurality of distillation columns.

82. The distillation system according to claim 81, wherein at least one of the distillation columns further includes flash distillation.

83. The distillation system according to claim 80, wherein the decant oil is recycled to the heat treatment system after removal of the pitch in the distillation column.

84. A distillation system for inducing pitch having a mesophase content of 0.7% or less from coal tar heavy distillate oil to obtain a pitch yield of at least 15%, At least one distillation column for receiving coal tar and fractionating it into component fractions including pitch and a coal tar-based heavy distillate oil, The heat treatment system according to claim 61, which receives the coal tar-based heavy distillate oil, processes it, and is in fluid communication with the at least one distillation column system for deriving pitch therefrom, A distillation system comprising:

85. The distillation system according to claim 84, further comprising a plurality of distillation columns.

86. The distillation system according to claim 85, wherein at least one of the distillation columns further includes flash distillation.

87. The distillation system according to claim 85, wherein at least one of the distillation columns further includes a dehydrator.

88. The distillation system according to claim 84, wherein the coal tar-based heavy distillate oil is recycled to the heat treatment system after removal of the pitch in the distillation column.

Images