Process for producing isotropic pitch

Abstract

A process and apparatus for making an isotropic pitch composition is disclosed. A raw isotropic pitch stream at a high pressure is reduced in pressure to form a second raw isotropic pitch stream including both liquid and vapor components. At least the liquid phase of the second raw isotropic pitch is introduced to a stripping column containing a vapor-liquid contacting element or elements at a point above the topmost point of the contacting element(s). Simultaneously, a stream including an inert gas is introduced to at a point below the topmost point of the contacting element(s). Operating conditions are such to provide an isotropic pitch composition having a softening point of no less than 100°C exiting as a liquid from the bottom of the stripper column.

Description

PROCESS FOR PRODUCING ISOTROPIC PITCHBACKGROUND

[0001] The present disclosure generally relates to methods for producing an isotropic pitch.

[0002] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure.

[0003] An isotropic pitch product composition as used herein is the result of thermally induced polymerization reaction of a hydrocarbon oil rich in high molecular weight and low volatility components as a starting material, typically greater than 200 g / gmol and / or greater than about 315°C (600°F) initial normal boiling point (IBP), that is rich in aromatic species and has a bulk hydrogen / carbon atomic ratio in the range of about 0.4 to about 1.2.

[0004] Because of the large differences in hydrocarbon molecule volatility that occur with differences in molecular structure at or nearly the same molecular weight, particularly paraffinic, aliphatic, cyclic and aromatic moieties, the volatility characterization of such hydrocarbon rich oils tends to dominate the description. For example, pure n-butyl benzene has a slightly higher MW than pure tetralin, 120 and 118, respectively, but has a substantially lower normal boiling point (NBP), 183°C and 208°C, respectively. The initial boiling point (IBP) may be measured by ASTM D-86 (physical distillation) or D-7169 (simulated distillation via gas chromatography), along with intermediate values of temperature indicating the amount of material distilled off as a vapor and subsequently condensed. Another useful value for characterizing the starting material is T10, the temperature wherein 10 wt% of a composition is distilled off, greater than about 315°C (600°F).

[0005] In classical refining and petrochemical terms, there is a wide range of starting materials that may be suitable, for example, Atmospheric Gas Oil (AGO) and Vacuum Gas Oil (VGO) obtained from distillation of virgin crude oil, and Main Column Bottoms (MCB) derived from various conversion reactions of those and other virgin crude materials and subsequent distillation of the reaction products such as Fluid Catalytic Cracking (FCC). Other possible starting materials include Steam Cracked Tar (SCT) obtained by high severity thermal treatment of almost any hydrocarbon from ethane to VGO and subsequent distillation of the treatment product, and Coal Tar which is a by-product of the production of coke and coal gas from coal, among numerous others generally having a significant aromatic content.

[0006] The thermally induced polymerization reaction of the starting material used in theproduction of a raw isotropic pitch stream typically occurs at a temperature from about 350°C to about 500°C, and a pressure of about 400 psig to about 1200 psig. The starting material is heated to such temperatures and kept there for 1 O' s of seconds to 100’s of minutes, depending on the exact process used and specific objective of that process. Such reaction methods are long familiar to the skilled artisan, for example, the thermal conversion reactor systems described in US Patents 2,768,119 and 3,140,248 involving some form of what is generally called “heat soaking.”

[0007] Isotropic pitch, in general, is mainly the result of the polymerization of aromatic species by radical chemistry to an average molecular weight of greater than about 250 g / gmol to as much as about 500 g / gmol. The resultant raw isotropic pitch stream obtained from the starting material has, as its name implies, a content of isotropic material (e.g., isophase), exhibiting the same physical and engineering properties in all directions. This is in contrast to a “mesotropic pitch” that has a content of anisotropic materials (e.g., mesophase) generally including condensed aromatics of higher average molecular weight than isotropic pitch that exhibit different properties in different directions. Mesophase can be a byproduct of raw isotropic pitch production under certain circumstances and conditions in the reaction of the starting material or handling of the raw isotropic pitch stream created from it. Depending on the intended use of the isotropic pitch composition ultimately derived from the raw isotropic pitch stream, the presence of mesotropic pitch may be undesirable.

[0008] More recently, US Patent 9,222,027 describes a thermally induced polymerization reaction method involving a particular set of heat soaking equipment and conditions for producing an isotropic pitch product composition with a low content of mesotropic pitch that may be useful as a source for a raw isotropic pitch stream in the embodiments disclosed herein. Mesotropic pitch in isotropic pitch measurement methods include those utilizing area measurements on photomicrographs of polished specimens to determine volume percent mesophase as described in “Quantitative determination of mesophase content in pitch,” Carbon, Volume 19, Issue 5, 1981, Pages 357-363, S. Chwastiak, et al., codified in ASTM D4616-95(2018). Such methods may also use micrographs taken using cross-polarized light optical microscopy.

[0009] Regardless of the specific method of treating a starting material to induce thermal polymerization, concurrent cracking and dealky lation reactions will unavoidably occur, providing a raw isotropic pitch stream with a very large range of hydrocarbon components across a very wide range of volatilities, e.g., from methane to condensed species having up to 100 carbon atoms. Thus, thermally induced polymerization reactions employed in theproduction of an isotropic pitch product composition, regardless of the specific starting material, equipment, and methods, may provide a raw isotropic pitch stream having a liquid and vapor phase, typically as produced and certainly when its pressure is reduced to create a second raw isotropic pitch as a combined liquid and vapor phase stream. The liquid and vapor phase in the second raw isotropic pitch as a combined stream must then be separated to make the isotropic pitch product composition in the desired liquid phase.

[0010] The method of conducting that separation can significantly change the character of the isotropic pitch product composition, particularly with respect to its softening point (SP). For example, the greater the quantity of higher volatility / lower MW isotropic pitch and non-isotropic pitch hydrocarbon components that reside in the isotropic pitch product composition along with the lower volatility / higher MW isotropic pitch and non-isotropic pitch hydrocarbon components, the lower the softening point of the bulk isotropic pitch product composition. Isotropic pitch product compositions of various SP of are desired (and undesired) for various applications, ranging from direct use to further conversion processing into high mesotropic pitch content compositions.

[0011] Softening point determination is one of the most important methods available to characterize pitches in view of the near impossibility of characterizing them analytically given the huge number of different molecules present. The softening point is defined as the temperature at which the pitch flows under a given load on heating. Several standard methods have been proposed to determine the softening point of pitch. One of the most common measurement techniques and the one suitable for the embodiments disclosed herein is the ‘'Mettler method’’ defined in the ISO 5940-2:2007 or ASTM D 3461-76 standards. Other methods include the Ring and Ball method in ASTM D 3461-76 or DIN ISO 4625 and the similar Kramer-Sarnow method in DIN 53 180, and the Plate-plate stress rheometer test. Each will provide a slightly different measured value for an identical material, estimated to be in the range of + / - 5°C.

[0012] Various methods to separate the liquid and vapor phases in the second raw isotropic pitch to make an isotropic pitch product composition with certain softening points have been described in the art. US 3,928,170 describes a reaction system into which is fed a ‘'pre-pitch” vapor phase and a continuous liquid phase, and a non-oxidative heat transfer medium. Very little or no suitable isotropic pitch product composition exists within the pre-pitch feed, rather, it is created within the reaction system and withdrawn as a liquid along with an attendant vapor of hydrocarbons and heat transfer medium. The heat transfer medium at a temperature within the range of 400°C to 2000°C is in direct contact with that liquid phase in a reaction zone tomaintain a temperature of 350-450°C, all at a pressure less than 3.0 kg / cm^2G (57 psia) with a liquid dwell time of 0.5 to 20 hours. The heat transfer medium may be nitrogen, argon, steam, hydrogen, or hydrocarbon gases. Any heat transfer medium must be provided, to properly conduct the poly-condensation reaction, at a feed rate to maintain the partial pressure of organics in the vapor phase within the reactor at less than a value in mm Hg defined by the formula: 1.03 x 1011 x e-(12200 / (T + 220)), wherein T is the temperature (°C) of the liquid phase within the reaction zone. Softening points of the isotropic pitch product composition ranging from about 130 to 230°C were reported, with the higher range preferred and the lower occurring at lower reactor temperatures and shorter dwell times.

[0013] US 4,497,789 discloses creating a liquid isotropic pitch obtained from a raw isotropic pitch and subjecting it to vacuum distillation at from about 0.1 to about 0.5 torr at a temperature of about 710°F (377°C) for atime in the range of from about 5 to about 15 seconds. This method is used to convert a starting isotropic pitch with a softening point of about 40°C to 130°C to an isotropic pitch product composition with a softening point of about 250°C or greater.

[0014] US 7,318,890 is directed to fractionating crude pitch by direct contact heating with molten metal at a temperature of 100°C to 600°C and a pressure of 0.01 to 1 atmospheres, correlated to sufficiently vaporize a desired amount of contaminants or volatile material from crude pitch to produce pitch product having a desired softening point. Pressures of 10 - 25 mm Hg are preferred. The crude pitch has a softening point of 180°F to 250°F (82°C -121°C) and the product pitch has a softening point of 200°F to 600°F (93°C - 315°C), preferably greater than 400°F (204°C).

[0015] US 9,222,027 defines a process wherein a combined vapor and liquid isotropic pitch containing reaction effluent is produced from a thermally induced polymerization reaction involving a specific set of starting materials, heat soaking equipment and conditions. The reactor effluent is flashed to recover a liquid residual isotropic pitch fraction and a separate vapor fraction comprising aromatic rich components boiling in the distillate range. It is noted that a single simple flash drum is used to separate distillable material from non-distillable pitch, perhaps operated under vacuum or with some steam injection to aid stripping. The target softening point of the liquid residual isotropic pitch fraction is greater than 80°C, preferably greater than 100°C.SUMMARY

[0016] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summaryof these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

[0017] In certain embodiments, a method for producing an isotropic pitch product composition includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C, reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream, where the combined liquid and vapor phase stream includes a second raw isotropic pitch liquid phase and a second raw isotropic pitch vapor phase. The method further including providing at least a portion of said second raw isotropic pitch liquid phase to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, where said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig and the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone. The method further including introducing a stream including an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part and removing from the stripper column an overhead vapor stream including inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, where said overhead vapor stream including inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C.

[0018] In certain embodiments, a method for producing an isotropic pitch product composition includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C and reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream. The method further including providing said second raw isotropic pitch as a combined liquid and vapor phase stream to a phase separator to create a second raw isotropic pitch liquid phase stream and a second raw isotropic pitch vapor phase stream and providing at least a portion of said second raw isotropic pitch liquid phase stream and at least a portion of said second raw isotropic pitch vapor phase stream to a stripper column containing a vapor-liquid contacting zone having one or morevapor-liquid contacting elements, where said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig. Further, the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone and the second raw isotropic pitch vapor stream is introduced to the vapor-liquid contacting zone at a point below the topmost vapor-liquid contacting element part. The method further includes introducing a stream including an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part and removing from the stripper column an overhead vapor stream including inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, where said overhead vapor stream including inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C.

[0019] In certain embodiments, a method for producing an isotropic pitch product composition includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C and reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream. The method further including providing at least a portion of said second raw isotropic pitch liquid phase to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, where said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig and the second raw- isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone. The method further including introducing a stream including an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part and removing from the stripper column an overhead vapor stream including inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, where said overhead vapor stream including inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C. The method further including providing, to a rectification column including a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partialcondenser, a vapor-liquid phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream including inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone. The method further including removing, from said rectification column, at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

[0020] The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0022] FIG. 1 is a schematic illustration of a process for producing an isotropic pitch product composition, in accordance with embodiments described herein;

[0023] FIG. 2 is a schematic illustration of a process for producing an isotropic pitch product composition, in accordance with embodiments described herein;

[0024] FIG. 3 is a schematic illustration of a process for producing an isotropic pitch product composition, in accordance with embodiments described herein;

[0025] FIG. 4 is a graphical representation of the results of the simulated distillation (SIMDIST) measurements for three streams, in accordance with embodiments described herein;

[0026] FIG. 5 is a graphical representation of a correlation of the softening point of an isotropic pitch product composition with its values of initial boiling point (IBP), the temperature where 10% of the composition is distilled off (T10), the temperature where 20% of the composition is distilled off (T20), and the temperature where 50% of the composition is distilled off (T50), in accordance with embodiments described herein; and

[0027] FIG. 6 is a schematic illustration of a comparative process for producing isotropic pitch product composition.DETAILED DESCRIPTION

[0028] Certain embodiments commensurate in scope with the present disclosure aresummarized below. These embodiments are not intended to limit the scope of the disclosure, but rather these embodiments are intended only to provide a brief summary of certain disclosed embodiments. Indeed, the present disclosure may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

[0029] As used herein, the term “coupled” or “coupled to” may indicate establishing either a direct or indirect connection (e.g, where the connection may not include or include intermediate or intervening components between those coupled), and is not limited to either unless expressly referenced as such. The term “set” may refer to one or more items. Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification.

[0030] As used herein, the terms “inner” and “outer”; “up” and “down”; “upper” and “lower”; “upward” and “downward”; “above” and “below”; “inward” and “outward”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.”

[0031] Furthermore, when introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment,” “an embodiment,” or “some embodiments” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Furthermore, the phrase A “based on” B is intended to mean that A is at least partially based on B. Moreover, unless expressly stated otherwise, the term “or” is intended to be inclusive (e.g., logical OR) and not exclusive (e.g., logical XOR). In other words, the phrase A “or” B is intended to mean A, B, or both A and B.

[0032] Current embodiments are directed to the use of countercurrent, stage wise vaporliquid contacting elements in processing isotropic pitch compositions with an inert gas, substantially increases the efficacy of a given quantity of inert gas in removing volatile components to obtain an isotropic pitch product composition with a softening point of no less than 100°C than can be achieved by previously disclosed methods. Further, present embodiments are directed providing more than one theoretical equilibrium stage (e.g., themaximum separation that can be obtained in a single stage flash) one achieves the additional benefit of significantly reducing the temperature of the isotropic pitch exiting the stage wise contacting elements to prevent potentially deleterious additional reaction of the isotropic pitch product composition (e.g., fouling, coking).

[0033] In an embodiment as shown in Figure 1, a process 100 includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C in line 102. The pressure of the raw isotropic pitch stream in line 102 may be no less than 400 psig and no greater than 1500 psig, or no less than 600 psig, or no less than 900 psig and no greater than 1200 psig. The temperature of the raw isotropic pitch stream in line 102 may be no less than 350°C and no greater than 520°C, or no less than 400°C, or no less than 400°C and no greater than 480°C. In some cases, the raw isotropic pitch stream may include the recycle of byproducts made from the thermally induced polymerization reaction described above, often in a mixture with the aforementioned Gas Oils, main column bottom (MCB), steam cracked tar (SCT) and Coal Tar “fresh feeds.” A recycled byproduct typically also has an initial boiling point greater than about 500°F and conveniently similar to those fresh feeds at greater than about 315°C (600°F).

[0034] Those conditions are correlated to a significant extent to the isotropic pitch content in the raw isotropic pitch stream, further depending on the character of the starting material from which it is made, and the flow regime and the residence time of that starting material exposed to those conditions. As used herein, isotropic pitch content is defined as the proportion of material within a stream having a normal boiling point of 315°C and higher, as determined by ASTM D-86 or D-7169. Accordingly, the isotropic pitch content of the raw isotropic pitch stream may be at least 2 wt%, or at least 2 wt% and no more than 50 wt%, or at least 5 wt%, or at least 5 wt% and no greater than 35 wt%. For example, US Patent 9,222,027 speaks of a raw isotropic pitch stream from a thermally induced polymerization wherein the time and temperature in the reactor create thermal conditions sufficient to convert at least 20 wt% of fresh feed and any recycle material which may be present to isotropic pitch.

[0035] Continuing with Figure 1, the pressure of the raw isotropic pitch stream in line 102 is reduced by passing through a pressure letdown valve 104 to produce a second raw isotropic pitch stream as a combined liquid and vapor phase in line 106 having a pressure of no less than 5 and no more than 100 psig and a temperature of no less than 10°C lower than the raw isotropic pitch stream. The pressure of the second raw isotropic pitch stream as a combined liquid and vapor phase in line 106 may be no less than 10 psig and no more than 70 psig, or no less than 15 psig and no more than 50 psig. The temperature of the second raw isotropic pitch stream asa combined liquid and vapor phase in line 106 may be no less than 10°C and no more than 150°C lower, or no less than 25°C lower, or no less than 25°C and no more than 130°C lower, or no less than 50°C lower, or no less than 50°C and no more than 110°C lower than the raw isotropic pitch stream. In certain embodiments, a controller (e.g., a processor-based controller having a processor, memory, and instructions stored on the memory and executable by the processor) may be programmed to control a flow rate, a temperature, a pressure, and a composition of the raw isotropic pitch streams in lines 102 and 106. For example, the controller may be configured to control a source of the raw isotropic pitch stream supplied to line 102 and adjust the pressure letdown valve 104 to control the second raw isotropic pitch stream supplied to the stripper column 108. However, in some embodiments, the raw isotropic pitch stream may be supplied to the stripper column 108 without control by the controller.

[0036] Pressure letdown valve 104 may be a type of high pressure / pressure differential letdown valve common in the industry, comprising a type of globe valve or preferentially an angle valve, such as, a Masoneilan Anti-Cavitation valve sold by Baker-Hughes. There are other means to reduce the pressure, for example, serial letdown valves of the globe valve type or one or more orifice plates (e.g., in series). However, the embodiments disclosed herein may use any suitable pressure reduction valves or equipment.

[0037] Returning to Figure 1, the second raw isotropic pitch stream as a combined liquid phase and vapor phase in line 106 is directed to a stripper column 108. In certain embodiments, the stripper column 108 may be a cylindrical or annular vessel defining an interior chamber that provides counter fluid flows. The pressure at all points within the stripper column 108 is no less than 0 and no more than 100 psig, or no less than 10 psig and no more than 65 psig, or no less than 15 psig and no more than 45 psig. The stripper column 108 contains a vapor-liquid contacting zone 110 (shaded) having one or more vapor-liquid contacting elements (e.g., 1, 2, 3, 4. 5, 6, 7. 8, 9, 10, or more vapor-liquid contacting elements) defining a plurality of vapor-liquid contacting stages. In certain embodiments, the vapor-liquid contacting elements may include crossflow trays (e.g., crossflow trays 112A, 112B, 112C). However, the embodiments disclosed herein are intended to cover any number, ty pe, and configuration of vapor-liquid contacting elements, including but not limited to crossflow trays. In this case of Figure 1, vaporliquid contacting elements are indicated as three discrete crossflow trays 112A, 112B and 112C from topmost to bottommost, thus defining a topmost element part of the vapor-liquid contacting zone as just above crossflow tray 112A at point 114 and a bottommost element part as just below crossflow tray 112C at point 116, more particularly just above and just below the liquid layers that will exist on the horizontal dashed line of those trays to facilitate vapor-liquidcontacting, respectively (the horizontal line represents what may be called the ‘‘tray deck,” while the vertical lines on those trays represent liquid downcomers). Note that both a vapor and a liquid may be provided to a vapor-liquid contacting element or section thereof (discrete if trays or sheds and analog if packing or grids, discussed below) for it to be considered as within a vapor-liquid contacting zone. In certain embodiments, the vapor-liquid contacting elements may be spaced uniformly and / or non- uniformly in the vertical direction.

[0038] The selection of vapor-liquid contacting element(s) used in the embodiments disclosed herein consider the high viscosity and especially the potential high fouling characteristics of pitch materials as an unavoidable attribute of pitch chemistry, typically manifested as thick sticky layers or agglomerations of solids or both. This may be balanced with the separation efficiency of the various vapor-liquid contacting element(s), as fouling tolerance and separation efficiency tend to be opposing features, i.e., the greater the one the lesser the other. As a derivative practical matter, the higher the separation efficiency, the smaller the elements can be (e.g., number of crossflow trays or height of packing) and / or the shortest vertical height of those elements are required in the stripper column to achieve the targeted separation objective; and the greater the fouling tolerance the longer the equipment may be used before it becomes so fouled the stripper column must be shut down and the elements cleaned.

[0039] In embodiments employing distillation trays as a form of vapor-liquid contacting element, they may be of any suitable type of “crossflow tray”, such as valve trays or sieve trays. In one embodiment, a type of large diameter fixed valve, directional flow tray is utilized, sometimes called a “jet tray,” such as a Superflux® VG-10 from Koch-Glitsch as one example. These valves have directional components that utilize energy from the vapor entering the valves from below the tray to provide forward-lateral push to the liquid on the tray deck. This action is important to maintain proper tray activity and reduce residence time of solids on the tray deck. Attention is also paid to the peripheral areas of the tray deck where stagnation may lead to solids creation with time at temperature and subsequent deposition. Directional valves are placed in this area to both increase activity as well as promote a uniform flow profile. These components combine to reduce the residence time distribution and enhance the fouling resistance of the trays.

[0040] While not represented in Figure 1, another option for vapor-liquid contacting elements is some form of packing frequently considered by the skilled artisan, such as rings and saddles, often installed as random packing, and more finely engineered systems of structured packing. A more convenient form of structured packing is termed “grids,” a form oflarge opening area structured packing that again produce higher fouling tolerance. Examples of grids packing include Kock-Glitsch PROFLUX® Severe Service Grid and Sulzer Mellagrid® or Snapgrid®.

[0041] Yet another option for vapor-liquid contacting elements not represented in Figure 1 is a form of “baffle” arrangement. These devices operate differently than trays, grids or packing. In baffle sections, the liquid cascades down from baffle to baffle in the form of liquid curtains. As the vapor flows up through these curtains, the liquid is broken up into droplets and mass and heat transfer occurs. It is generally viewed that there are two different types of baffles, the first being a “disc and donut” configuration with a horizontal ring / annulus whose outer perimeter is attached to the column inner diameter (the “donut”) at one elevation, and a solid horizontal circle whose center on the axis of the column is supported in the center of the column (the “disc”). The disc diameter is slightly larger than the inner perimeter of the donut and it is located at a different elevation. These two units are repeated as desired along the axial elevation of the column. The other type is called “sheds,” which include multiple units of various geometries repeating across the across the diameter of the column rather than just one (one disc or one donut). One type of interest is called angle iron trays or angle iron decks, which are angle iron beams of various sizes having the angle vertex pointing upward that are placed in rows spaced at certain distances radially across the column to enable vapor to flow upward through them. The trays are rotated 90° from tray to tray at different axial elevations in the column. Among other reputable vendors and engineering firms, Raschig USA can design and supply “Side-to-side Baffles” and disc and donut equipment.

[0042] The selection of the specific vapor-liquid contacting element(s) in the embodiments disclosed herein is a balance between fouling tolerance and separation efficiency as determined by the user for the specific application. Among the three types of vapor-liquid contacting elements discussed herein, the crossflow trays will have the greatest separation efficiency and the least fouling tolerance. Packing including grids will have a modest separation efficiency (in terms of HETP - Height of a Theoretical Plate) and good fouling tolerance. Sheds will have the lowest separation efficiency and the greatest fouling tolerance.

[0043] The presence of any vapor-liquid contacting element(s) in a vapor-liquid contacting zone 110 operated according to the method of the embodiments disclosed herein will provide a more efficient use of the stream comprising an inert gas than would be obtained without them. For example, it will require a lower amount of the stream comprising an inert gas to obtain a desired softening point of the isotropic pitch product composition than to obtain that same softening point in a single stage flash of the second raw isotropic pitch stream as a combinedliquid and vapor phase stream, further combined with the same amount and conditions of the stream comprising an inert gas. Alternatively, or in combination, the rate of the stream comprising an inert gas may be the same as that used in a single stage flash to obtain a desired softening point and provided at a lower cost by using a lower temperature.

[0044] The theoretical maximum vapor-liquid separation a single stage flash can achieve is one theoretical plate, that is, perfect vapor-liquid phase equilibrium, and although one may get close to that theoretical value, it is never quite achieved, since achievement requires infinite contacting time to do so. The same is true when one uses a tray or a shed as a vapor-liquid contacting element, and one may quantitatively determine a tray efficiency less than 100% of a theoretical stage by means well understood in the art, typically requiring knowledge of the phase equilibrium and the physical properties of the component system of interest, particularly density, viscosity, surface tension, and of the contacting characteristics of the specific element. It is a bit more complicated with packing and grids, as they are defined by HETP determined in a similar manner as a tray or shed, but if one provides a height lower than the HETP, one gets less than 100% of a theoretical stage. Conveniently, the contacting element(s) in the vaporliquid contacting zone provide no less than 0.2 of theoretical plate, or no less than 0.2 and no more than 10, or no less than 0.5, or no less than 0.5 and no more than 7.0, or no less than 1.0, or no less than 1.0 and no more than 6.0, or no less than 2.0, or no less than 2.0 and no more than 5.0 theoretical plates.

[0045] With attention to Figure 1, the second raw isotropic pitch stream as a combined liquid phase and vapor phase in line 106 is provided to the upper volume 118 of stripper column 108 above the vapor-liquid contacting zone topmost element part point 114. This will result in a phase separation of those liquid and vapor phases such that the liquid phase falls onto topmost vapor-liquid contacting element crossflow tray 112A while the vapor phase rises and for all practical purposes bypasses vapor-liquid contacting zone 110 and is not a factor in the vaporliquid separation that occurs therein. Simultaneously, a stream comprising an inert gas having a temperature of no less than 100°C in line 122 is provided to a point below the vapor-liquid contacting zone topmost element part point 114, in this case to the lower volume 120 of stripper column 108 below vapor-liquid contacting zone bottommost element part 116.

[0046] The inert gas may be one or more molecules selected from steam, hydrogen, nitrogen, argon, and hydrocarbons that are at least partially in the vapor phase at the pressure and temperature conditions within stripper column 108. Conveniently, all of the stream comprising an inert gas is completely in the vapor phase at the pressure and temperature conditions within stripper column 108, as any liquid will leave with the isotropic pitch productcomposition in line 126 and may require additional processing of that stream to remove it from the isotropic pitch product composition. This is of particular pertinence if steam or hydrocarbon are selected as an inert gas. If a hydrocarbon is chosen as an inert gas, it is conveniently selected to contain lower molecular weight paraffins and / or aliphatics ranging from 1 to 6 carbon atoms.

[0047] The stream comprising an inert gas in line 122 may be no less than 100°C and no more than 500°C, or no less than 150°C, or no less than 150°C and no more than 475°C, or no less than 200°C, or no less than 200°C and no more than 450°C. Of course, the pressure of the stream comprising an inert gas in line 122 may be at a pressure higher than that within stripper column 108. In some embodiments, the stream comprising an inert gas in line 122 may be no more than 500°C, or no more than 475°C, or no more than 450°C, or no more than 250°C. In certain embodiments, the controller may be programmed to control a flow rate, a temperature, a pressure, and a composition of the inert gas supplied to the stripper column 108 via the line 122. For example, the controller may be configured to control the temperature of the inert gas to be within the foregoing temperature ranges, such as between upper and lower temperature thresholds. However, in some embodiments, the inert gas may be supplied to the stripper column 108 without control by the controller.

[0048] In the case of Figure 1, the stream comprising an inert gas is provided directly in line 122, although there are alternate means of doing so within the scope of the embodiments disclosed herein. While not shown in Figure 1, it may be convenient to supply, say, liquid or mixed liquid and vapor water or hydrocarbon at a high pressure and temperature to a pressure letdown valve enabling the extent of pressure reduction to form a vapor or additional vapor from that liquid (similar to the configuration shown for the raw' isotropic pitch stream to the second line 102 through pressure letdown valve 104 to create the raw isotropic pitch as a combined liquid and vapor phase stream in line 106). Such a letdown valve configuration may also be used, say, to reduce high pressure and temperature, fully vapor steam to the conditions appropriate in stripper column 108. Regardless of the specific means utilized, the inert gas provided to the lower volume 120 of stripper column 108 will rise into bottommost vaporliquid contacting element crossflow' tray 112C and through vapor-liquid contacting zone 110, participating in the vapor-liquid separation that occurs therein.

[0049] Also not shown in Figure 1, the stream comprising an inert gas may be directed to more than one location of contacting zone 110. For example, the stream comprising an inert gas in line 122 may be split in two parts in some proportion, with one part provided to lower volume 120 of stripper column 108 and the other part provided to, say, a point in between bottommost vapor-liquid contacting element 112C and central vapor-liquid contacting element112B. This may be of value in controlling the softening point of the isotropic pitch product composition as the bottoms liquid stream in line 126, depending on the specific circumstances and conditions of the streams and equipment applied in the embodiments disclosed herein.

[0050] Further considering Figure 1, the rising inert gas will contact the falling second raw isotropic pitch liquid in vapor-liquid contacting zone 110 causing vapor-liquid separation to occur, with the main outcome being the removal of higher volatility molecules from the liquid phase into the vapor phase. The highest concentration of higher volatility components that were once in the liquid phase of the second raw isotropic pitch stream as a combined liquid and vapor phase stream in line 106 will then be in the vapor exiting the vapor-liquid contacting zone topmost element part point 114. Those higher volatility vapor components that were once in the liquid phase of the second raw isotropic pitch stream as a combined liquid and vapor phase stream in line 106 now rise into the upper volume 118 of stripper column 108. and along with the vapor phase that was once in the second raw isotropic pitch stream as a combined liquid and vapor phase stream in line 106 and all or almost all of the inert gas ultimately leave stripper column 108 as an overhead vapor stream comprising inert gas and hy drocarbons in line 124. Accordingly, the lowest concentration of higher volatility components in the liquid phase will be in that liquid exiting vapor-liquid contacting zone bottommost element part point 116, which falls into the lower volume 120 of stripper column 108 and ultimately leaves stripper column 108 as the isotropic pitch product composition as the bottoms liquid stream in line 126.

[0051] The isotropic pitch product composition as the bottoms liquid stream in line 126 will have a softening point of no less than 100°C. The isotropic pitch product composition as the bottoms liquid stream in line 126 may have a softening point of no less than 100°C and no more than 260°C, or no less than 120°C, or no less than 120°C and no more than 240°C, or no less than 140°C, or no less than 140°C and no more than 220°C, or no less than 160°C, or no less than 160°C and no more than 200°C. In some embodiments, the isotropic pitch product composition as the bottoms liquid stream in line 126 may have a softening point of no more than 320°C, or no more than 260°C, or no more than 220°C. In the embodiments disclosed herein, the desired softening point of the isotropic pitch product composition is obtained by selecting the appropriate composition and conditions of the stream comprising an inert gas in line 122 and its mass flow rate relative to that of the raw isotropic pitch stream in line 102, in consideration of the composition and conditions of the raw isotropic pitch stream in line 102 and the conditions within stripper column 108, to remove an adequate amount of higher volatility hydrocarbon components from the raw isotropic pitch stream. Additionalconsideration may include the exact point or points of introduction of a stream comprising an inert gas to the contacting zone 110 as discussed above. Regardless of the specific locations to which the stream comprising an inert gas is provided to the stripper column 108, the total amount / rate thereof is best viewed in terms of its ratio to the amount / rate of the raw isotropic pitch stream provided to the stripper column 108. This stream comprising an inert gas to raw isotropic pitch stream ratio (mass flow ratio) on a mass basis may be no less than 0.1, or no less than 0.1 and no more than 2.0, or no less than 0.2, or no less than 0.2 and no more than 1.0. For a given raw isotropic pitch stream composition and conditions, the higher the temperature and / or the higher the stream comprising an inert gas to raw isotropic pitch stream ratio, the higher the resulting softening point of the isotropic pitch product composition. In certain embodiments, the controller may be programmed to control a flow rate, a temperature, a pressure, and a composition of the isotropic pitch product composition as the bottoms liquid stream in line 126 as described herein. For example, the controller may be configured to control the softening point to be within a temperature range, such as between upper and lower temperature thresholds as described herein. However, in some embodiments, the isotropic pitch product composition as the bottoms liquid stream in line 126 may be generated by the stripper column 108 without control by the controller.

[0052] The temperature of the overhead vapor stream comprising inert gas and hydrocarbons in line 124 will be greater than the temperature of the isotropic pitch product composition as the bottoms liquid stream in line 126. Due to the unusual vapor-liquid equilibrium established in the embodiments disclosed herein by the contacting of hydrocarbons and inert gas in contacting zone 110 having one or more vapor-liquid contacting elements, the isotropic pitch product composition as the bottoms liquid stream in line 126 will have a lower temperature than the overhead vapor stream comprising inert gas and hydrocarbons in line 124. In certain embodiments, the highest temperature in contacting zone 110 will be at vapor-liquid contacting zone topmost element part point 114 and the lowest temperature will be at vaporliquid contacting zone bottommost element part 116 with a continual reduction in temperature moving downward in between. Given the relatively low time of liquid exposure overall in contacting zone 110 having one or more contacting elements, and the even lower time of liquid exposure at any given place within contacting zone 110, this unusual ^inverse temperature gradient” (the great majority of phase equilibrium exhibited in columns will cause the bottoms liquid product to have the highest temperature) is a valuable attribute in minimizing deleterious reaction of the isotropic product composition at high temperature outside the thermally induced polymerization reaction system. It will be recognized by those familiar with the art that as apractical matter, the isotropic product composition will have a fairly long residence time at the temperature of the bottoms liquid product in line 126 to accommodate its journey to the next equipment item. As an example, this may be to a pump which requires at least five minutes in such a line to provide appropriate suction head for the pump (height of the liquid filled pipe above the pump) and time to respond to an operating issue where flow is disrupted without damaging the pump (volume of the line above the pump). Thus, for example, the need to introduce a relatively expensive intermediate cooling step for the isotropic pitch product composition in line 126 to avoid such deleterious reactions is no longer needed.

[0053] The temperature of the overhead vapor stream comprising inert gas and hydrocarbons in line 124 may be no less than 20°C, or no less than 20°C and no more than 250°C, or no less than 50°C, or no less than 50°C and no more than 220°C. or no less than 100°C, or no less than 100°C and no more than 200°C above that of the temperature of the isotropic pitch product composition as the bottoms liquid stream in line 126.

[0054] The upper volume 118 and lower volume 120 of stripper column 108 may contain devices, not show n in Figure 1, that promote an optimal distribution of the material and phases leaving those volumes and entering the pertinent vapor-liquid contacting elements in contacting zone 110. For example (among many other possible devices), the second raw isotropic pitch stream as a combined liquid and vapor phase in line 106 may be directed into a vertical wall within upper volume 118 situated close to the exit of line 106 from which the liquid will drop onto the side of the topmost vapor-liquid contacting element crossflow- tray 112A opposite the downcomer, increasing the amount of liquid that will pass over the top of crossflow tray 112A that is exposed to the vapors rising through the bottom of crossflow tray 112A. However, if packing or grids were employed as vapor-liquid contacting elements, the second raw isotropic pitch stream as a combined liquid and vapor phase in line 106 may be directed into a perforated pipe distributor that provides a more even liquid flow radially over the top of the packing or grid assembly, minimizing area where the rising vapor may bypass the liquid on the vaporliquid contacting element. While vapor distribution is not nearly as important as liquid distribution in upper volume 118, similar features for vapor distribution may also be introduced or may be inherent to achieving good liquid distribution. On the other hand, vapor distribution may be important in lower volume 120 (or elsewhere in stripper column 108) and, for example, the stream comprising an inert gas in line 122 may be directed into a perforated pipe distributor or other device, e.g., a “vane” assembly among many alternatives, that provides a more even vapor flow radially into bottommost vapor-liquid contacting element crossflow tray 112C, or into the bottom of packing, grids, and / or sheds.

[0055] In an embodiment as shown in Figure 2, a process 200 builds on that described by Figure 1. The features, functions and options of Figure 2 designated by the 10’s digits in the 200 series numbers are the same as those described for Figure 1 with the same 10's digits in the 100 series numbers from 102 through 126. For example, a raw isotropic pitch stream at a pressure of no less than 400psig and a temperature of no less than 350°C in line 202 of Figure 2 is the same as the raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C in line 102 of Figure 1, and so on.

[0056] Figure 2 differs from Figure 1 only in providing a phase separator, in the form of flash drum 228, as a means for phase separation of the second raw isotropic pitch as a combined liquid and vapor phase stream in line 206 that is outside of the stripper column 208, versus that same stream undergoing phase separation in upper volume 218 of stripper column 208 in Figure 1 (described as 118 and 108, respectively). Thus, flash drum 228 creates a second raw isotropic pitch liquid phase stream in line 230 and a second raw isotropic pitch vapor phase stream in line 232.

[0057] Remaining with Figure 2, flash drum 228 is situated at a particular location relative to stripper column 208, more particularly relative to the elevation of the topmost vapor-liquid contacting element crossflow tray 212A within vapor-liquid contacting zone 210. Along with the appropriate construction of line 230 in which flows second raw- isotropic pitch liquid phase stream, and of line 232 in which flows the second raw isotropic pitch vapor phase stream, a convenient means of directing the second raw isotropic pitch vapor phase stream in line 232 to a specific point below vapor-liquid contacting zone topmost element part 214 is enabled. It is desirable for lines 230 and 232 to be essentially open with no restrictions causing appreciable additional pressure drop through them, e.g., no flow meter orifices or flow control valves.

[0058] In the case of Figure 2, the second raw isotropic pitch vapor phase stream in line 232 is directed to a point below topmost vapor-liquid contacting element crossflow tray 212A and above central vapor-liquid contacting element crossflow tray 212B. In certain embodiments, the second raw isotropic pitch vapor phase stream in line 232 may be directed to a point below any one or more upper vapor-liquid contacting element crossflow trays and any one or more lower vapor-liquid contacting element crossflow trays. In this manner, unlike the situation in Figure 1 where the separated vapor portion of the second raw isotropic pitch as a combined liquid and vapor phase stream in line 106 bypasses vapor-liquid contacting zone 110 and is not a factor in the vapor-liquid separation that occurs therein, the second raw isotropic pitch vapor phase stream now in line 232 will participate in vapor-liquid contacting in vapor-liquid contacting zone 210 and will be a factor in the vapor-liquid separation thatoccurs therein. Specifically, the second raw isotropic pitch vapor phase stream in line 232 will rise through the bottom of topmost vapor-liquid contacting element crossflow tray 212A along with vapors emanating from central vapor-liquid contacting element crossflow tray 212B.Those vapors will interact with the second raw isotropic pitch liquid phase stream in line 230 that will fall onto the top of topmost vapor-liquid contacting element crossflow tray 212A.Derivatively, those vapors will change the composition of the liquid emanating from topmost vapor-liquid contacting element crossflow tray 212A that is provided to central vapor-liquid contacting element crossflow tray 212B.

[0059] Flash drum 228 in Figure 2 will be positioned such that the liquid level established therein will be slightly higher than the exit of line 230 containing the second raw isotropic pitch liquid phase stream that enters stripper column 208 above vapor-liquid contacting zone topmost element part 214. Line 230 is constructed in the fashion of what is termed a “P-trap.” also called a ‘'seal leg,’’ as frequently employed in household plumbing to move a liquid through a line while preventing vapor flow and back-flow in it. Line 230 will extend downward from the bottom of flash drum 228 for a modest distance, then run tow ards and up to the desired exit location (forming a shape like the letter P " rotated 90° to the right, with the straight line off the curve pointing either right or left). As noted earlier, when properly designed by methods well understood in the art, the liquid height established in flash drum 228 is higher than the exit of line 230, self-adjusting to provide just the head needed to overcome the pressure drop through the line 230 “P” en route to stripper column 208. Further, the pressure of the vapor above the liquid level in flash drum 228 will be slightly higher than that at the exit of line 232 containing the second raw- isotropic pitch vapor phase stream and entering stripper column 208, self-adjusting to just that needed to overcome the pressure drop from flash drum 228 through line 232 en route to stripper column 208.

[0060] Thus, the flash drum 228 of Figure 2 will operate at a pressure that is slightly higher than at the exit of line 232 containing the second raw isotropic pitch vapor phase stream that enters the point below- topmost vapor-liquid contacting element crossflow tray 212A and above central vapor-liquid contacting element crossflow7tray 212B. In the operation of stripper column 208 and particularly within vapor-liquid contacting zone 210, the pressure will increase slightly going from the highest elevation to the lowest per force of the static head imposed by the prevailing heights of liquid and vapor within stripper column 208. This results in the pressure at a point below topmost vapor-liquid contacting element crossflow tray 212A being slightly higher than at a point above it (this is the reason why in Figure 1 the vapor portion of the second raw isotropic pitch as a combined liquid and vapor phase stream in line 106 createdin upper volume 118 of stripper column 108 rises and does not participate in vapor-liquid contact zone 110). The flash drum 228 and P-trap line 230 configuration may overcome this hydraulic phenomenon to enable the vapor portion of the second raw isotropic pitch stream as a combined liquid and vapor phase stream in line 206 to participate in vapor-liquid contacting zone 210 while still providing the liquid portion of second raw isotropic pitch as a combined liquid and vapor phase stream in line 206 to a point above the vapor-liquid contacting zone 210. It is a static, inherently self-adjusting system that requires little to no instrumentation and is an efficacious alternative to, for example, employing a gas compressor to achieve the same end.

[0061] The pressure differential from the highest to the lowest elevation in a stripper column will typically be no more than about 5 psi and usually no more than about 3 psi. For example, the pressure drop through one crossflow tray is rarely more than about 0.1 psi and that of any reasonable open volume rarely more than about 0.01 to 0.5 psi, the high end of that range accounting for the potential presence of any internals such as distributors discussed earlier. In accordance, the difference in the pressure of the vapor space in flash drum 228 and the disposition of the second raw isotropic pitch vapor phase stream in line 232 (e.g., somewhere in vapor-liquid contacting zone 210) will be in that range of 0.1 to 10 psi. The high end of that range accounts for the potential additional pressure drop exhibited in line 232 containing the second raw isotropic pitch vapor phase stream, for example, should the disposition of the second raw isotropic pitch vapor phase stream in line 232 include a vapor distribution system within vapor-liquid contacting zone 210 discussed earlier (not shown in Figure 2), to promote an optimal distribution of the material vapor entering the bottom of vapor-liquid contacting element crossflow tray 212A.

[0062] In an embodiment as shown in Figure 3, a process 300 builds on that described by Figure 1. The features, functions, and options of Figure 3 designated by the 10's digits in the 300 series numbers are the same as those described for Figure 1 with the same 10’s digits in the 100 series numbers from 102 through 126. For example, a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C in line 302 of Figure 2 is the same as the raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C in line 102 of Figure 1, and so on. Further, all of the discussion in Figure 1 surrounding the types and attributes of vapor-liquid contacting elements and options within upper and lower volumes for the stripper column apply to the same features of the rectification column 336 of Figure 3, particularly within shell 338.

[0063] In producing an isotropic pitch product composition having a softening point noless than 100°C according to the embodiments disclosed herein, higher volatility hydrocarbons are removed from the liquid phase into the vapor phase, more particularly removed from the isotropic pitch product composition in an amount that is directly proportional to its softening point value. That is, obtaining higher softening points require removing a greater the quantity of higher volatility hydrocarbons in the overhead vapor stream comprising inert gas and hydrocarbons. Thus, “higher volatility” is a relative term. Given the wide range of hydrocarbons exhibiting a wide spectrum of volatilities in the raw isotropic pitch stream, the hydrocarbons in the overhead vapor stream comprising inert gas and hydrocarbons will similarly exhibit a wide spectrum of volatilities, ranging from that of methane with a normal boiling point of about -161°C (-259°F) to higher MW species with a normal boiling point of up to about 537°C (l,000°F). The higher the softening point of the isotropic pitch product composition, the greater the content of higher normal boiling point hydrocarbon components in that range.

[0064] Various narrower ranges of hydrocarbon volatility, or fractions, may be created from the overhead vapor stream comprising inert gas and hydrocarbons, conveniently through the embodiment as described in Figure 3. Each fraction is more suitable for different uses than the aggregate hydrocarbon composition in the overhead vapor stream comprising inert gas and hydrocarbons. These fractions include, from highest to lowest volatility, fuel gas, and liquid fuel blendstocks such as naphtha, kerosene, diesel, heating oil and fuel oil (including Bunker fuels) whose properties are well understood in the petrochemical industry, and potentially mixtures thereof. A fraction of particular value is a liquid hydrocarbon stream having a relatively low volatility characterized by a T10 of no less than 315°C (600°F) that is especially useful as a starting material (or recycle material in a greater process) for the thermally induced polymerization reaction used in the production of a raw isotropic pitch stream. That relatively low volatility liquid hydrocarbon product may also be sold, for example, as a fuel oil blendstock.

[0065] In view of Figure 3, the overhead vapor stream comprising inert gas and hydrocarbons 324 is directed to a rectification column, the entirety of which is within the bracket with the designation 336. comprising shell 338 containing a second vapor-liquid contacting zone 340 having one or more second vapor-liquid contacting elements 342A, 342B and 342C, a partial condenser 350, a vapor-liquid separator 354 (shown as a three-phase, vaporliquid-liquid separator) and a reflux pump 362. Shell 338 of rectification column 336 is in oneway fluid communication with stripper column 308 using a chimney tray 334 which simultaneously forms the top of upper volume 318 of stripper column 308 and the bottom ofsecond lower volume 344 of shell 338. Chimney trays may include one or more conduits through and of some height above a solid flat plate, with the open area at the very top of each conduit covered, typically by some form of cone placed at some elevation above the very top to create a gap for vapor flow. The overhead vapor stream comprising inert gas and hydrocarbons 324 flows through the plurality of chimneys on chimney tray 334, up the conduits and around their conical covers into second lower volume 344 below second vapor-liquid contacting zone 340. All liquid falling down from the second contacting zone 340 and exiting vapor-liquid contacting element 342C will be diverted away from the conduits and onto the very bottom of second lower volume 344 by the conical covers of chimney tray 334 and the force of the overhead vapor stream comprising inert gas and hydrocarbons flowing out of the gaps. This configuration is often economical in enabling the stripper column 308 and the shell 338 to be constructed as a single large shell for both, with the chimney tray as the line of demarcation between the two columns. Further, the overhead vapor stream comprising inert gas and hydrocarbons 324 rising from the chimney tray gaps into second lower volume 344 passes through the liquid exiting vapor-liquid contacting element 342C, enabling chimney tray 334 to also act as an additional vapor-liquid contacting element after the fashion of sheds described earlier in service of the separation objectives of rectification column 336. Of course, similar results could be achieved in separate columns using a pipe conveying the overhead vapor stream comprising inert gas and hydrocarbons from the appropriate place in the stripper column to the appropriate place in the fractionation column.

[0066] Remaining on Figure 3, the overhead vapor stream comprising inert gas and hydrocarbons 324 within the second lower volume 344 may continue to rise into the second contacting zone 340 through the bottom of vapor-liquid contacting element 342C, and portions of the overhead vapor stream comprising inert gas and hydrocarbons may continue up through second contacting zone 340 as dictated by the vapor-liquid established on each of the second vapor-liquid contacting elements 342A, 342B and 342C. Typically, the vapor rising from the top of each second vapor-liquid contacting element 342A, 342B and 342C will be richer in inert gas and leaner in hydrocarbon (e.g., greater than 50% weight inert gas). A liquid hydrocarbon reflux stream in line 366 enters second upper volume 346 in shell 338 and falls into the second contacting zone 340 onto the top of vapor-liquid contacting element 342A, establishing the liquid traffic falling through the second vapor-liquid contacting zone 340 again dictated by the vapor-liquid established on each of the second vapor-liquid contacting elements 342A, 342B and 342C. The liquid falling onto the very' bottom of second lower volume 344 is the bottoms liquid hydrocarbon stream having a T10 of no less than 315°C (600°F) in line 370that is removed from the rectification column 336.

[0067] Continuing with Figure 3, the vapor exiting second upper volume 346 in line 348 are enriched in inert gas and in hydrocarbons of higher volatility relative to the overhead vapor stream comprising inert gas and hydrocarbons 324 provided to rectification column 336. The vapor exiting second upper volume 346 in line 348 may be directed to an indirect heat exchanger, partial condenser 350, where heat is removed from that material to form a partially condensed hydrocarbon stream in line 352 that is directed to vapor-liquid separator 354 (shown as a three-phase, vapor-liquid-liquid separator). Though not exclusively, conveniently the temperature of the partially condensed hydrocarbon stream in line 352 will be that afforded by using an inexpensive source of cooling such as environmental air or cooling water near the local dry bulb temperature. Regardless of the source of cooling, conveniently the temperature of the partially condensed hydrocarbon stream in line 352 may be no less 10°C than and no more than 80°C, or no less than 30°C and no more than 60°C, as may be adequate to provide such partial condensation without the need for expensive refrigeration.

[0068] With Figure 3 still forefront, if the stream comprising an inert gas in line 322 contains only hydrogen, nitrogen, argon or some combination of them, essentially all the inert gas will remain in the vapor phase of the partially condensed hydrocarbon stream in line 352 and in vapor-liquid separator 354 (shown as a three-phase, vapor-liquid-liquid separator) at the conditions therein, but for perhaps a tiny amount dissolved in the condensed liquid hydrocarbon. If the stream comprising an inert gas in line 322 contains hydrocarbons that are at least partially in the vapor phase at the pressure and temperature conditions within rectification column 336, the phase in which they exist in the partially condensed hydrocarbon stream in line 352 and vapor-liquid separator 354 (shown as a three-phase, vapor-liquid-liquid separator) is dependent on the specific hydrocarbon components utilized. For example, an inert gas of methane or ethane will exist almost exclusively in the vapor phase, again perhaps with tiny amounts dissolved in the condensed liquid hydrocarbon. However, an inert gas of propane, butanes or pentanes will exist mainly in the vapor phase but with appreciable amounts condensed to become part of the condensed liquid hydrocarbon along with hydrocarbon components therein from the raw isotropic pitch stream in line 302; their presence in the condensed liquid hydrocarbon increases proportional to their normal boiling point. In that vein, an inert gas of hexanes may exist mainly in the condensed liquid hydrocarbon with only minor amounts in the vapor phase. Finally, if the stream comprising an inert gas in line 322 contains steam, an appreciable amount will condense to form a second liquid water (aqueous) phase along with the partially condensed hydrocarbon stream of both vapor and liquid phase in line352 and in vapor-liquid separator 354 (shown as a three-phase, vapor-liquid-liquid separator) at the conditions therein; the lower the temperature, the more liquid w ater will be formed and at temperatures in the lower half of the range no less 10°C than and no more than 80°C only a minor amount of water will be in the vapor phase.

[0069] In embodiments where the inert gas in line 322 is steam, the partially condensed hydrocarbon stream in line 352 is directed to vapor-liquid separator 354 (shown as a three-phase. vapor-liquid-liquid separator) which creates three separate streams, an overhead product gas stream in line 356, an overhead product liquid water stream in line 358 and an overhead intermediate liquid hydrocarbon stream in line 360. The overhead product gas stream in line 356 and the overhead product liquid water stream in line 358 are removed from rectification column 336. The overhead product gas stream in line 356 will contain mainly Cl to C7 hydrocarbons present in the raw isotropic pitch stream in line 302 along with a minor amount of vapor water provided in the stream comprising an inert gas in line 322. The overhead product gas stream in line 356 may, for example, be further processed to separate and recover those hydrocarbons or various fractions thereof, or used directly as a fuel gas for combustion in a process furnace or a steam production boiler. The overhead product liquid water stream in line 358 will be mainly water with small amounts of dissolved hydrocarbons; it may, for example, be further processed to remove the dissolved hydrocarbons and provide suitable boiler feed water for steam generation, w ith that steam recycled as part of the stream comprising an inert gas in line 322. In embodiments not employing water as the inert gas in line 322. no separate liquid phase would be formed, and there would be no need for vapor-liquid separator 354 to be a three-phase separator, it could be just a simple vapor-liquid separator.

[0070] Completing our view of Figure 3, the overhead intermediate liquid hydrocarbon stream in line 360 is provided to a reflux pump 362. Reflux pump 362 creates a pressurized intermediate liquid hydrocarbon stream in line 364 having a pressure of at least that which enables return of a portion of it to the second upper volume 346 above the second vapor-liquid contacting zone 340. The pressurized intermediate liquid hydrocarbon stream in line 364 may be split into the liquid hydrocarbon reflux stream in line 366 that is directed to the second upper volume 346 above the second vapor-liquid contacting zone 340, and the overhead product liquid hydrocarbon stream in line 368 that is removed from rectification column 336. The overhead product liquid hydrocarbon stream in line 368 contains the balance of the hydrocarbons present in the raw' isotropic pitch stream in line 302 that were not removed from rectification column 336 as the overhead product gas stream in line 356 and the bottoms liquid hydrocarbon stream having aT10 of no less than 315°C (600°F) in line 370. The compositionof overhead product liquid hydrocarbon stream in line 368 w ill typically be components with volatilities ranging from butanes to those with a normal boiling point of about 371°C (700°F), a mixture of classical naphtha, kerosene, diesel and heating oil fractions, perhaps with a minor amount in the fuel oil range; it may, for example, be subjected to further processing to make naphtha, kerosene, diesel and heating oil blendstocks for sale.EXAMPLES

[0071] A Fluid Catalytic Cracking Unit (FCCU) Main Column Bottoms (MCB) material was obtained from the ExxonMobil Baytown Refinery and hydrotreated to remove sulfur. The hydrotreated MCB had a residual sulfur content of about 0.4 wt%. a hydrogen / carbon atomic ratio of 0.88 and a T10 of about 315°C (600°F). The MCB was subjected to a continuous process and pilot plant apparatus for making isotropic pitch as described in U. S. Patent 9,222,027, in a tubular reactor at 490°C and 1000 psig for about 10 minutes, to produce a raw' isotropic pitch stream. The raw isotropic pitch stream was separated into four products: a vent gas containing methane, ethane, propane, butane, a light distillate (LD), a heavy distillate (HD), and an isotropic pitch product composition (Isotropic pitch).

[0072] The mass proportions of the four aforementioned products obtained from the raw' isotropic pitch streams were measured. The composition of the vent gas w as measured by gas chromatography. ASTM D-7169 (simulated distillation via gas chromatography, aka ’SIMDIST ) volatility measurements and density measurements were conducted on the two liquid distillates and the isotropic pitch product composition. The results of the SIMDIST measurements for those three streams are provided in Figure 4.

[0073] From this information, a functional representation of the composition of the raw isotropic pitch stream was developed as a combined set of real components (methane, ethane, propane, and butane) and ‘’pseudo-components.” Pseudo-components are a well understood means of characterizing complex mixtures of hydrocarbon components whose specific composition is extremely difficult to determine analytically.

[0074] The means of characterizing pseudo-components and using them in process simulations of unit operations to create heat and material balances w'ould be understood to one skilled in the art. Any of the classical methods to generate the pseudo-components from density' and distillation (volatility) curves can be used. Such methods can be found in classical references, e.g.. Riazi M., Characterization and properties of petroleum fractions, Vol 50: ASTM international; 2005 and Wauquier J-P. Petroleum Refining: Crude oil, petroleum products, process flowsheets, Vol 1: Editions Technip; 1995. Most pseudo-component generation methods use the same general procedure as follows: 1) A probability distributionfunction is fit to the True Boiling Point (TBP) distillation curve to provide a continuous distribution of normal boiling points. The most common probability' distribution function is the Gamma function, 2) The probability distribution model is discretized into a given number of slices each representing a pseudo-component having a normal boiling point that corresponds to some sort of an average between the minimum and maximum boiling points of the discretization slice, 3) The densities of each of the generated pseudo-components are assigned such that the experimentally measured bulk density is satisfied and assuming, e.g., that the 1(1Watson characterization factor Kw= —— — ) is constant for all fractions, where Tb is the normal boiling point in units of K and SG is the specific gravity, 4) The other physical properties of pseudo-components (e.g. molecular weight, aromaticity, heat capacity, heat of vaporization) are calculated using empirical correlations.

[0075] Commercial process simulation tools such as ASPEN Plus, ASPEN HYSYS, and AVEVA PRO / II can generate pseudo-components and their associated thermophysical properties automatically from density and true boiling point (TBP) curve following said procedure according to either a default cut-set of pseudo-components or a user-defined cut-set. In the approach used herein, the simulated distillation curve is assumed to represent the TBP curve. For the two distillate streams the default cut-set available in PRO / II was used to discretize each into pseudo-components.

[0076] The isotropic product composition is different in that it contains very heavy molecules that boil above 732°C (l,350°F), the typical maximum that can be measured by the GC instruments used in ASTM D-7169. However, by virtue of the mass balance available from the instrument data, it was determined that 24.1 wt% of the isotropic pitch composition had a normal boiling point above 732°C (1.350°F). enabling a customized cut-set to properly capture a full boiling range of the pseudo-components for the isotropic product composition assuming a maximum of 1,648°C (3,000°F). The section of the TBP curve from 732°C (l,350°F) to 1,648°C (3,000°F) was constructed by extrapolation of the measured probability distribution curve which was optimized to fit the first 75.9 wt% of the distillation curve and predict the remainder of the curve. The full real and pseudo-component slate for the raw isotropic pitch stream as 132 discrete “species” used to represent the raw isotropic pitch stream in the example of the embodiments disclosed herein is given in Table 1. Table 1 further provides the liquid density and normal boiling point assigned to each real and pseudo-component, the measured and estimated mass proportion of each, and the calculated molecular weight of each. The component names indicate the product obtained from the raw isotropic pitch stream that theyrepresent, LD being the light distillate, HD the heavy distillate and Isotropic pitch the isotropic pitch product composition; the vent stream is given as the specific (real) molecules.Table 1: Real and Pseudo-component Representation of Raw Isotropic pitch Stream - - i i Liquid _T, „... Composition Molecular _. Normal Boiling Componentn / , Density*, „., „TT,„1Xwt% Weightg / cm3 Point (NBP), °F METHANE 1.274 16.0 0.3 -258.7 ETHANE 0.722 30.1 0.355 -127.5 PROPANE 0.780 44.1 0.506 -43.7 BUTANE 2.069 58.1 0.585 31.1 LD PC1 0.043 55.3 0.693 15.9 LD PC2 0.072 59.4 0.701 39.6 LD PC3 0.156 63.4 0.715 61.1 LD PC4 0.284 67.5 0.726 82.5 LD PC5 0.210 70.9 0.734 99.8 LD PC6 0.086 76.1 0.745 125.0 LD PC7 0.088 80.9 0.754 147.5 LD PC8 0.151 85.5 0.762 167.9 LD PC9 0.104 90.7 0.771 189.9 LD PC10 0.171 96.5 0.780 213.4 LD PC11 0.206 101.7 0.788 233.8 LD PC12 0.235 107.9 0.797 257.4 LD PC13 0.258 113.4 0.804 277.4 LD PC14 0.294 120.1 0.813 300.8 LD PC15 0.281 125.9 0.820 320.3 LD PC16 0.276 133.2 0.828 343.9 LD PC17 0.244 139.5 0.835 363.7LD PC18 0.220 147.0 0.842 386.5 LD PC19 0.192 154.2 0.849 407.3 LD PC20 0.155 162.1 0.856 429.5 LD PC21 0.125 169.9 0.863 450.9 LD PC22 0.096 178.3 0.870 472.9 LD PC23 0.081 186.8 0.877 494.7LD PC24 0.064 195.7 0.883 516.4 LD PC25 0.055 204.8 0.890 538.2 LD PC26 0.069 214.0 0.896 559.6 LD PC27 0.038 223.5 0.903 580.8 LD PC28 0.024 230.9 0.908 597.4 HD PC 1 0.640 137.3 1.020 427.8 HD PC2 0.327 139.9 1.024 437.7 HD PC3 0.296 144.1 1.030 453.1 HD PC4 0.346 147.7 1.035 466.4 HD PC5 0.353 151.5 1.040 480.3 HD PC6 0.419 155.3 1.046 493.9 HD PC7 0.499 159.3 1.050 507.5 HD PC8 0.745 163.3 1.056 521.5 HD PC9 0.646 167.1 1.060 534.1 HD PC10 0.989 171.7 1.066 549.3 HD PC11 1.737 175.5 1.070 561.7 HD PC12 0.988 180.0 1.075 576.0 HD PC13 2.871 184.9 1.080 591.2 HD PC14 1.629 188.3 1.084 601.8 HD PC15 2.232 193.4 1.089 617.2 HD PC 16 3.289 197.5 1.093 629.4 HD PC 17 3.541 201.8 1.097 642.1 HD PC18 2.470 207.2 1.102 657.6 HD PC 19 5.455 211.8 1.107 670.5 HD PC20 2.134 217.0 1.1 11 685.0 HD PC21 4.651 221.6 1.115 697.8 HD PC22 3.444 227.0 1.120 712.3 HD PC23 3.21 1 231.6 1.124 724.4 HD PC24 4.851 237.3 1.129 739.4 HD PC25 2.773 242.4 1.133 752.6 HD PC26 3.667 247.4 1.137 765.2 HD PC27 2.999 253.1 1.141 779.5HD PC28 2.856 258.9 1.145 793.7 HD PC29 7.310 271.1 1.154 822.5 HD PC30 3.692 294.7 1.169 871.3 HD PC31 1.786 323.6 1.183 922.4 HD PC32 1.114 357.1 1.198 973.3 HD PC33 0.748 394.8 1.212 1023.1 HD PC34 0.446 437.4 1.225 1071.9 HD PC35 0.361 495.8 1.241 1130.1 HD PC36 0.249 525.5 1.254 1160.4 HD PC37 0.001 582.8 1.259 1202.9 HD PC38 0.000 594.7 1.259 1210.5 HD PC39 0.000 606.9 1.259 1218.2 HD PC40 0.000 625.7 1.259 1229.6 Isotropic pitch PC 1 0.000 201.7 1.080 631.3 Isotropic pitch_PC2 0.001 204.8 1.080 638.6 Isotropic pitch_PC3 0.008 208.1 1.081 646.5 Isotropic pitch_PC4 0.051 210.5 1.086 655.0 Isotropic pitch_PC5 0.022 211.8 1.092 661.7 Isotropic pitch_PC6 0.021 215.5 1.095 671.7 Isotropic pitch_PC7 0.025 218.8 1.098 680.5 Isotropic pitch PC 8 0.030 221.9 1.101 689.3 Isotropic pitch_PC9 0.031 225.3 1.104 698.2 Isotropic pitch PC 10 0.036 228.7 1.106 707.1 Isotropic pitch PC 11 0.042 232.1 1.109 715.9 Isotropic pitch PC 12 0.048 235.4 1.112 724.7 Isotropic pitch PC 13 0.052 238.8 1.115 733.6 Isotropic pitch PC 14 0.059 242.3 1.118 742.5 Isotropic pitch PC 15 0.065 245.8 1.121 751.3 Isotropic pitch PC 16 0.071 249.4 1.123 760.2 Isotropic pitch PC 17 0.077 252.9 1.126 769.0 Isotropic pitch PC 18 0.084 256.6 1.129 777.9 Isotropic pitch PC 19 0.103 260.3 1.132 787.0Isotropic pitch_PC20 0.109 263.8 1.134 795.3 Isotropic pitch_PC21 0.131 268.6 1.137 806.4 Isotropic pitch_PC22 0.171 274.0 1.141 818.8 Isotropic pitch_PC23 0.165 279.7 1.145 831.1 Isotropic pitch_PC24 0.158 285.9 1.149 844.0 Isotropic pitch_PC25 0.171 291.9 1.152 855.9 Isotropic pitch_PC26 0.160 298.6 1.156 868.9 Isotropic pitch_PC27 0.166 305.3 1.159 881.2 Isotropic pitch_PC28 0.155 312.3 1.163 893.6 Isotropic pitch_PC29 0.168 319.8 1.167 906.5 Isotropic pitch_PC30 0.163 327.2 1.170 918.6 Isotropic pitch_PC31 0.158 335.1 1.174 931.3 Isotropic pitch_PC32 0.179 343.4 1.177 943.9 Isotropic pitch_PC33 0.188 351.9 1.181 956.3 Isotropic pitch_PC34 0.199 360.7 1.184 968.8 Isotropic pitch_PC35 0.208 369.8 1.188 981.3 Isotropic pitch_PC36 0.226 379.4 1.191 993.9 Isotropic pitch_PC37 0.248 389.1 1.194 1006.3 Isotropic pitch_PC38 0.274 399.3 1.198 1018.8 Isotropic pitch_PC39 0.302 409.9 1.201 1031.5 Isotropic pitch PC40 0.351 420.8 1.205 1043.9 Isotropic pitch_PC41 0.383 431.9 1.208 1056.3 Isotropic pitch_PC42 0.403 443.6 1.211 1068.8 Isotropic pitch PC43 0.412 455.6 1.214 1081.3 Isotropic pitch_PC44 0.431 468.2 1.218 1093.9 Isotropic pitch_PC45 0.425 480.9 1.221 1106.2 Isotropic pitch_PC46 0.425 494.2 1.224 1118.7 Isotropic pitch_PC47 0.427 508.1 1.228 1131.3 Isotropic pitch_PC48 0.415 522.2 1.231 1143.7 Isotropic pitch_PC49 0.378 536.8 1.234 1156.2 Isotropic pitch_PC50 0.366 552.0 1.237 1168.7 Isotropic pitch_PC51 0.347 567.6 1.240 1181.2Isotropic pitch_PC52 0.312 583.7 1.243 1193.7 Isotropic pitch_PC53 2.211 701.7 1.263 1274.8 Isotropic pitch_PC54 1.030 1184.8 1.320 1506.2 Isotropic pitch_PC55 0.797 1866.1 1.363 1712.1 Isotropic pitch_PC56 0.575 2835.9 1.406 1918.0 Isotropic pitch_PC57 0.385 4192.6 1.438 2123.9 Isotropic pitch_PC58 0.239 6011.3 1.458 2329.8 Isotropic pitch_PC59 0.138 8286.3 1.470 2535.8 Isotropic pitch_PC60 0.140 11074.5 1.479 2757.0 * at NBP for NBP <60°F; at 60°F for NBP ≥60°F

[0077] Once the pseudo-components are determined along with their physical properties, an equation of state model can be used to predict the vapor-liquid equilibrium due to the mixing of the raw isotropic pitch product with an inert gas such as steam to study the impact of vapor liquid contacting elements operating in a stage-wise fashion on the extent of stripping of isotropic pitch and the resulting softening point of an isotropic pitch product composition. To implement an equation of state for a mixture of pseudo-components, the physical properties of the pseudo-components need to be translated into a suitable set of simulation parameters and installed in a process simulation computer tool. In this example, we use the polar Perturbed Chain Statistical Association Theory (Polar PC-SAFT) of Marshall et al., A PC-SAFT model for hydrocarbons I: Mapping aromatic π-π interactions onto a dipolar free energy, Fluid Phase Equilibria. 2019;489:83-89, and the EMPETRO parameterization methodology of Marshall et al., A PC-SAFT model for heavy hydrocarbon thermodynamics in downstream separation processes. AIChE Journal. 2020;66(12):el6997 to obtain the simulation parameters from physical properties. This PC-SAFT thermodynamic property model of the raw isotropic pitch stream was implemented in the AVEVA PRO / II process simulation computer tool to provide the prediction results of this example.

[0078] As discussed above, there are a number of accepted means of generating pseudocomponents. Further, various individuals having common skill in the art can make different choices on the number of cuts to employ on a stream, and there are several accepted correlations for estimating other physical properties for those pseudo-components and several different thermodynamic methods that may be appropriately selected. The specific choices may provide different absolute values of the results coming from their implementation in a given process simulation tool, but within modest bounds that will provide similar conclusions about theimpact of various stripper column configurations employing vapor-liquid contacting elements and provide adequate information for a reliable design of such equipment. It should be noted that the temperature and pressure limitations of the embodiments disclosed herein pertain to absolute, physical measurements and are not based on model calculations as described for the purpose of characterizing the general behavior and benefits of using the embodiments in the example.

[0079] Referring now to the correlation of the T20 value of the isotropic pitch product composition predicted by the PC-SAFT pseudo-component process simulation model to the softening point of the isotropic pitch product composition. The aforementioned pilot plant was operated on the same raw isotropic pitch stream to produce a series of isotropic pitch product compositions of various softening points as actually measured by the Mettler method. As indicated in U. S. Patent 9,222,027, the raw isotropic pitch stream was mixed with varying amounts and temperatures of steam and introduced to a flash drum operating at about 5 psig to produce the isotropic pitch product compositions of varying softening points. Further, actual SIMDIST measurements were conducted on each of those isotropic pitch product compositions of varying softening point. The results are plotted in Figure 5.

[0080] Figure 5 shows the correlation of the softening point of an isotropic pitch product composition with its values of initial boiling point (IBP), the temperature where 10% of the composition is distilled off (T10), the temperature where 20% of the composition is distilled off (T20) and the temperature where 50% of the composition is distilled off (T50). Among those SIMDIST values, T20 has an appreciably better linear correlation with isotropic pitch product composition softening point as indicated by the high value of the statistical parameter R2, the coefficient of determination, associated with each, represented by the formula: SP[°C] = 0.4656*T20[°F] - 296.27 where the isotropic pitch product composition softening point is SP in degrees Celsius and its weight percent T20 value is in degrees Fahrenheit.

[0081] The PC-SAFT thermodynamic property model of the raw isotropic pitch stream was implemented in the AVEVA PRO / II process simulation computer tool and used to investigate three different methods of obtaining an isotropic pitch product composition from a raw isotropic pitch stream, one using comparative means and two using configurations of the embodiments disclosed herein.

[0082] The first method, example Case A, is that described above for making the real isotropic pitch product compositions of varying softening points according to U. S. Patent 9,222,027, the means as described for Figure 6.

[0083] In Figure 6, a raw isotropic pitch stream in line 602, of the composition in Table 1at 482.2°C and 1050 psig, is provided to pressure letdown valve 604 to produce a second raw isotropic pitch stream as a combined liquid and vapor phase in line 606. The second raw- isotropic pitch stream in line 606 is blended with a stream comprising an inert gas, in this example Case A pure steam at 130.6°C and 25.2 psig in line 622. The inert gas to raw isotropic pitch stream ratio on a mass basis, more specifically the steam to raw isotropic pitch stream ratio on a mass basis (S / F), is 0.3 (e.g., 3 lb / hr of steam in line 622 and 10 lb / hr of raw isotropic pitch stream in line 602). The resultant second raw isotropic pitch and steam blend in line 680 is provided to a simple flash drum 682, operating at 25 psig, serving to create a flash vapor stream in line 684 and an isotropic pitch product composition in line 626. It is assumed that simple flash drum 682 provides one theoretical equilibrium stage of separation of the entire contents of all phases of the second raw- isotropic pitch and steam blend in line 680.

[0084] The second method, example Case B, is that of the process described above according to Figure 1. A raw isotropic pitch stream of the composition in Table 1 at 482.2°C and 1050 psig is provided in line 102 to pressure letdown valve 104 to produce a second raw isotropic pitch stream as a combined liquid and vapor phase in line 106 that is directed to the upper volume 118 of stripper column 108. The pressure in upper volume 118 is 25.0 psig. Vapor-liquid contacting zone 110 is assumed to provide three theoretical equilibrium stages (100% tray efficiency each for vapor-liquid contacting elements 112A, 112B and 112C). A stream comprising an inert gas, in this example Case B pure steam at 130.6°C and 25.2 psig in line 122, is provided to lower volume 120 of stripper column 108. The pressure in lower volume 120 is 25.2 psig. The inert gas to raw isotropic pitch stream ratio on a mass basis, in this example the steam to raw isotropic pitch stream ratio on a mass basis (S / F), is 0.3 (e.g, 3 Ib / hr of steam in line 122 and 10 Ib / hr of raw isotropic pitch stream in line 102).

[0085] The third method, example Case C, is that of the process described above according to Figure 2. A raw isotropic pitch stream of the composition in Table 1 at 482.2°C and 1050 psig is provided in line 202 to pressure letdown valve 204 to produce a second raw isotropic pitch stream as a combined liquid and vapor phase in line 206 that is directed to flash drum 228. Flash drum 228 operates at 25.1 psig. The resultant second raw' isotropic pitch vapor phase stream in line 232 is directed to a point below topmost vapor-liquid contacting element crossflow tray 212A and above central vapor-liquid contacting element crossflow tray 212B of stripper column 208, while the second raw isotropic pitch liquid phase stream in line 230 is directed to the upper volume 218 of stripper column 208. The pressure in upper volume 218 is 25.0 psig. Vapor-liquid contacting zone 210 is assumed to provide three theoretical equilibrium stages (100% tray efficiency each for vapor-liquid contacting element crossflow trays 212A,212B and 212C). A stream comprising an inert gas, in this example Case C pure steam at 130.6 °C and 25.2 psig in line 222, is provided to lower volume 220 of stripper column 208. The pressure in lower volume 220 is 25.2 psig. The inert gas to raw isotropic pitch stream ratio on a mass basis, in this example the steam to raw isotropic pitch stream ratio on a mass basis (S / F), is 0.3 (e.g., 3 lb / hr of steam in line 222 and 10 lb / hr of raw isotropic pitch stream in line 202).

[0086] Key results from the process simulations of example Cases A, B and C, along with the correlated softening point temperature of the resultant isotropic pitch product compositions in lines 626. 126 and 226, respectively, are provided in Table 2.Table 2: Results of Isotropic pitch Process Simulations for Example Cases A, B and C Case A B C Configuration Fig. 6 Fig. 1 Fig. 2 Comparative Embodiment Embodiment Second raw isotropic pitch stream T (°F) 806 806 806 Theoretical stages in vapor-liquid contacting1 3 3 zoneOverhead vapor stream T (°F) 705 743 731 Topmost vapor-liquid contacting element TN / A 635 731 (°F)Central vapor-liquid contacting element TN / A 516 556 (°F)Bottommost vapor-liquid contacting element705 437 448 = isotropic pitch product composition T (°F)Isotropic pitch product composition yield,21.0 17.5 15.1 wt% (of raw isotropic pitch stream)Isotropic pitch product composition T20 (°F) 821 927 994Isotropic pitch product composition SP (°C) 86 135 167

[0087] Table 2 shows the increased efficiency of a stream including inert gas, in these example cases specifically steam, in increasing the isotropic pitch product softening point when employing vapor-liquid contacting devices in a stripping column according to the embodiments disclosed herein. Across all the cases at identical raw isotropic pitch stream and steam compositions and conditions, identical steam to feed mass ratios, and identical operating pressures, the isotropic pitch product composition softening point is increased substantially with only a few theoretical stages relative to conventional methods. The staging enables the same amount and conditions of steam to remove a greater amount of higher volatility hydrocarbon components from the raw isotropic pitch stream, as evidenced by the lower yield and higher T20 value of the isotropic pitch product composition.

[0088] Further considering Table 2, the unusual "‘inverse temperature gradient" will beseen in the significant temperature drop occurring from the topmost to the central to the bottommost vapor-liquid contacting elements. Thus, according to embodiments disclosed herein, the process provides the increase in the efficiency of the steam while decreasing the isotropic pitch product composition temperature substantially and minimizing the potential for deleterious reaction of the isotropic product composition at high temperature outside the thermally induced polymerization reaction system.

[0089] As will be appreciated, any of the features discussed above as relating to FIGS. 1-5 may be used in any combination with one another. Further, any of the above features discussed above as relating to FIGS. 1-5 may include a controller configured to control various flows (e.g., stream flows) and / or operating parameters of components included in any of the above-mentioned processes to achieve the desired properties of the generated pitch.

[0090] Technical effects of the disclosed embodiments include increased efficiency of a stream comprising inert gas in increasing the isotropic pitch product softening point when employing vapor-liquid contacting devices in a stripping column. For example, present embodiments employing multiple stages enable utilization of equal or decreased inert gas temperatures, compared to traditional systems, to produce higher isotropic pitch product softening point. In this way, embodiments of the present disclosure may provide increased energy efficiency in producing desired properties of the generated pitch. Further, technical effects of the disclosed embodiments include a decreased isotropic pitch product composition temperature, compared to traditional processes. In this way, embodiments of the present disclosure reduce undesirable reactions of the isotropic product composition due to the high temperature outside the thermally induced polymerization reaction system.

[0091] The subject matter described in detail above may be defined by one or more clauses, as set forth below.

[0092] A method for producing an isotropic pitch product composition includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C, reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream, where the combined liquid and vapor phase stream includes a second raw isotropic pitch liquid phase and a second raw isotropic pitch vapor phase. The method further including providing at least a portion of said second raw isotropic pitch liquid phase to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, where said vapor-liquid contacting zone has a topmost element part anda botommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig and the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone. The method further including introducing a stream including an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part and removing from the stripper column an overhead vapor stream including inert gas and hydrocarbons and the isotropic pitch product composition as a botoms liquid stream, where said overhead vapor stream including inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a botoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C.

[0093] The method of any preceding clause, where said overhead vapor stream including inert gas and hydrocarbons is provided to a rectification column including a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a vapor-liquid phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream including inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone. The method further including removing from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, and a botoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

[0094] The method of any preceding clause, where the rectification column is in one-way fluid communication with the stripper column.

[0095] The method of any preceding clause, where a chimney tray is disposed between the stripper column and the rectification column, where the chimney tray is configured to place the stripper column in one-way fluid communication with the rectification column.

[0096] The method of any preceding clause, where said stream including an inert gas includes at least some steam and where said overhead vapor stream including inert gas and hy drocarbons is provided to a rectification column including a shell containing a second vaporliquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a three-phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and three-phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream including inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone. The method further includes removing from said rectification column at least an overhead product gas stream, anoverhead product liquid hydrocarbon stream, an overhead product liquid water stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

[0097] The method of any preceding clause, where the vapor-liquid contacting elements includes at least one of a valve tray, a sieve tray, or a directional flow tray.

[0098] The method of any preceding clause, where the vapor-liquid contacting elements include packing.

[0099] The method of any preceding clause, where providing the said second raw isotropic pitch liquid phase to the stripper column containing the vapor-liquid contacting zone having one or more vapor-liquid contacting elements includes providing the second raw isotropic pitch liquid phase to a perforated pipe distributor of the stripper column.

[0100] The method of any preceding clause, where the vapor-liquid contacting elements includes one or more baffles.

[0101] The method of any preceding clause, where the point below the topmost vaporliquid contacting element part is a first point, and the method includes introducing a second stream including the inert gas having a temperature no less than 100°C to the stripper column at a second point below the topmost vapor-liquid contacting element part and above the first point.

[0102] The method of any preceding clause, where a mass flow ratio of the stream including inert gas to the raw isotropic pitch stream is no less than 0.1 and no more than 2.0.

[0103] The method of any preceding clause, where the inert gas includes methane, ethane, propane, butane, pentane, hexane, steam, or a combination thereof.

[0104] The method of any preceding clause further including providing the raw isotropic pitch stream at the pressure of no less than 400 psig and no greater than 1500 psig and the temperature of no less than 350°C.

[0105] The method of any preceding clause further including providing the raw isotropic pitch stream at the pressure of no less than 400 psig and the temperature of no less than 350°C and no greater than 520°C.

[0106] The method of any preceding clause, where reducing the pressure includes reducing the pressure of said raw isotropic pitch stream to create the second raw isotropic pitch as the combined liquid and vapor phase stream having the pressure of no less than 10 and no more than 70 psig and the temperature no less than 10°C lower than the raw isotropic pitch stream.

[0107] The method of any preceding clause, where reducing the pressure includes reducing the pressure of said raw isotropic pitch stream to create the second raw isotropic pitch as the combined liquid and vapor phase stream having the pressure of no less than 15 and no morethan 50 psig and the temperature no less than 10°C lower than the raw isotropic pitch stream.

[0108] The method of any preceding clause, where the pressure at all points within the stripper column is no less than 10 and no more than 65 psig.

[0109] The method of any preceding clause, where the pressure at all points within the stripper column is no less than 15 and no more than 45 psig.

[0110] The method of any preceding clause, where the stream including the inert gas includes a temperature no greater than 500°C.

[0111] A method for producing an isotropic pitch product composition includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C and reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream. The method further including providing said second raw isotropic pitch as a combined liquid and vapor phase stream to a phase separator to create a second raw isotropic pitch liquid phase stream and a second raw isotropic pitch vapor phase stream and providing at least a portion of said second raw isotropic pitch liquid phase stream and at least a portion of said second raw isotropic pitch vapor phase stream to a stripper column containing a vaporliquid contacting zone having one or more vapor-liquid contacting elements, where said vaporliquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig. Further, the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone and the second raw isotropic pitch vapor stream is introduced to the vaporliquid contacting zone at a point below the topmost vapor-liquid contacting element part. The method further includes introducing a stream including an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part and removing from the stripper column an overhead vapor stream including inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, where said overhead vapor stream including inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C.

[0112] The method of any preceding clause, where said overhead vapor stream including inert gas and hydrocarbons is provided to a rectification column including a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a vapor-liquid phase separator and a reflux pump, the pressureat all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream including inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone. The method further including removing from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

[0113] The method of any preceding clause, where said stream including an inert gas includes at least some steam and said overhead vapor stream including inert gas and hydrocarbons is provided to a rectification column including a shell containing a second vaporliquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a three-phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and three-phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream including inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone. The method further including removing from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, an overhead product liquid water stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

[0114] The method of any preceding clause, where the phase separator includes a flash drum.

[0115] The method of any preceding clause, where the second raw isotropic pitch liquid phase stream is provided to the stripper column at an inlet below a liquid level in the phase separator.

[0116] A method for producing an isotropic pitch product composition includes providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C and reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream. The method further including providing at least a portion of said second raw isotropic pitch liquid phase to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, where said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig and the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone. The method further including introducing a stream including an inert gas having a temperature no less than 100°Cto the stripper column at a point below the topmost vapor-liquid contacting element part and removing from the stripper column an overhead vapor stream including inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, where said overhead vapor stream including inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C. The method further including providing, to a rectification column including a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a vapor-liquid phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream including inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone. The method further including removing, from said rectification column, at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

[0117] The method of any preceding clause including removing from said rectification column an overhead product liquid water stream.

[0118] The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. Moreover, the order in which the elements of the methods described herein are illustrated and described may be re-arranged, and / or two or more elements may occur simultaneously. The embodiments were chosen and described in order to best explain the principals of the disclosure and its practical applications, to thereby enable others skilled in the art to best utilize the disclosure and various embodiments with various modifications as are suited to the particular use contemplated.

[0119] Finally, the techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible or purely theoretical. Further, if any claims appended to the end of this specification contain one or more elements designated as “means for [perform]ing [a function]... ” or “step for [perform]ing [a function]... ”, it is intended that such elements are to be interpreted under 35 U. S. C. 112(f). However, for any claims containing elements designated in any other manner, it is intended that such elements are not to be interpreted under 35 U. S. C. 112(f).

Claims

CLAIMS1. A method for producing an isotropic pitch product composition, the method comprising:providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C;reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream, wherein the combined liquid and vapor phase stream comprises a second raw isotropic pitch liquid phase and a second raw isotropic pitch vapor phase;providing at least a portion of said second raw isotropic pitch liquid phase to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, wherein said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig and the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone;introducing a stream comprising an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part; and removing from the stripper column an overhead vapor stream comprising inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, wherein said overhead vapor stream comprising inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C.

2. The method for producing an isotropic pitch product composition of claim 1, wherein:said overhead vapor stream comprising inert gas and hydrocarbons is provided to a rectification column comprising a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a vaporliquid phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream comprising inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone; andremoving from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, and a bottoms product liquid hydrocarbon streamhaving a T10 of no less than 315°C (600°F).

3. The method for producing an isotropic pitch product composition of claim 2, wherein the rectification column is in one-way fluid communication with the stripper column.

4. The method for producing an isotropic pitch product composition of claim 3, wherein a chimney tray is disposed between the stripper column and the rectification column, wherein the chimney tray is configured to place the stripper column in one-way fluid communication with the rectification column.

5. The method for producing an isotropic pitch product composition of claim 1, wherein:said stream comprising an inert gas includes at least some steam;said overhead vapor stream comprising inert gas and hydrocarbons is provided to a rectification column comprising a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a three-phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and three-phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream comprising inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone; andremoving from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, an overhead product liquid water stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

6. The method for producing an isotropic pitch product composition of claim 1, wherein the vapor-liquid contacting elements comprise at least one of a valve tray, a sieve tray, or a directional flow tray.

7. The method for producing an isotropic pitch product composition of claim 1, wherein the vapor-liquid contacting elements comprise packing.

8. The method for producing an isotropic pitch product composition of claim 7, wherein providing the said second raw isotropic pitch liquid phase to the stripper column containing the vapor-liquid contacting zone having one or more vapor-liquid contacting elements comprises providing the second raw isotropic pitch liquid phase to a perforated pipe distributor of the stripper column.

9. The method for producing an isotropic pitch product composition of claim 1, wherein the vapor-liquid contacting elements comprise one or more baffles.

10. The method for producing an isotropic pitch product composition of claim 1, wherein the point below the topmost vapor-liquid contacting element part is a first point, and the method comprises:introducing a second stream comprising the inert gas having a temperature no less than 100°C to the stripper column at a second point below the topmost vapor-liquid contacting element part and above the first point.

11. The method for producing an isotropic pitch product composition of claim 1, wherein a mass flow ratio of the stream comprising inert gas to the raw isotropic pitch stream is no less than 0.1 and no more than 2.0.

12. The method for producing an isotropic pitch product composition of claim 1, wherein the inert gas comprises methane, ethane, propane, butane, pentane, hexane, steam, or a combination thereof.

13. The method for producing an isotropic pitch product composition of claim 1, the method comprising:providing the raw isotropic pitch stream at the pressure of no less than 400 psig and no greater than 1500 psig and the temperature of no less than 350°C.

14. The method for producing an isotropic pitch product composition of claim 1, the method comprising:providing the raw isotropic pitch stream at the pressure of no less than 400 psig and the temperature of no less than 350°C and no greater than 520°C.

15. The method for producing an isotropic pitch product composition of claim 1, wherein reducing the pressure comprises:reducing the pressure of said raw isotropic pitch stream to create the second raw isotropic pitch as the combined liquid and vapor phase stream having the pressure of no less than 10 and no more than 70 psig and the temperature no less than 10°C lower than the raw isotropic pitch stream.

16. The method for producing an isotropic pitch product composition of claim 1, wherein reducing the pressure comprises:reducing the pressure of said raw isotropic pitch stream to create the second raw isotropic pitch as the combined liquid and vapor phase stream having the pressure of no less than 15 and no more than 50 psig and the temperature no less than 10°C lower than the raw isotropic pitch stream.

17. The method for producing an isotropic pitch product composition of claim 1, wherein the pressure at all points within the stripper column is no less than 10 and no more than 65 psig.

18. The method for producing an isotropic pitch product composition of claim 1, wherein the pressure at all points within the stripper column is no less than 15 and no more than 45 psig.

19. The method for producing an isotropic pitch product composition of claim 1, wherein the stream comprising the inert gas comprises a temperature no greater than 500°C.

20. A method for producing an isotropic pitch product composition, the method comprising:providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C;reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream;providing said second raw isotropic pitch as a combined liquid and vapor phase stream to a phase separator to create a second raw isotropic pitch liquid phase stream and a second raw isotropic pitch vapor phase stream;providing at least a portion of said second raw isotropic pitch liquid phase stream and at least a portion of said second raw isotropic pitch vapor phase stream to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, wherein said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig, the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone and the second raw isotropic pitch vapor stream is introduced to the vapor-liquid contacting zone at a point below the topmost vapor-liquidcontacting element part;introducing a stream comprising an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part; and removing from the stripper column an overhead vapor stream comprising inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, wherein said overhead vapor stream comprising inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C.

21. The method for producing an isotropic pitch product composition of claim 20, wherein:said overhead vapor stream comprising inert gas and hydrocarbons is provided to a rectification column comprising a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a vaporliquid phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream comprising inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone; andremoving from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

22. The method for producing an isotropic pitch product composition of claim 20, wherein:said stream comprising an inert gas includes at least some steam;said overhead vapor stream comprising inert gas and hydrocarbons is provided to a rectification column comprising a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a three-phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and three-phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream comprising inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone; andremoving from said rectification column at least an overhead product gas stream, an overhead product liquid hydrocarbon stream, an overhead product liquid water stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

23. The method for producing an isotropic pitch product composition of claim 20, wherein the phase separator comprises a flash drum.

24. The method for producing an isotropic pitch product composition of claim 20, wherein the second raw isotropic pitch liquid phase stream is provided to the stripper column at an inlet below a liquid level in the phase separator.

25. A method for producing an isotropic pitch product composition, the method comprising:providing a raw isotropic pitch stream at a pressure of no less than 400 psig and a temperature of no less than 350°C;reducing the pressure of said raw isotropic pitch stream to create a second raw isotropic pitch as a combined liquid and vapor phase stream having a pressure of no less than 5 and no more than 100 psig and a temperature no less than 10°C lower than the raw isotropic pitch stream;providing at least a portion of said second raw isotropic pitch liquid phase to a stripper column containing a vapor-liquid contacting zone having one or more vapor-liquid contacting elements, wherein said vapor-liquid contacting zone has a topmost element part and a bottommost element part, the pressure at all points within the stripper column is no less than 0 and no more than 100 psig and the second raw isotropic pitch liquid phase is introduced at a point above the vapor-liquid contacting zone;introducing a stream comprising an inert gas having a temperature no less than 100°C to the stripper column at a point below the topmost vapor-liquid contacting element part; removing from the stripper column an overhead vapor stream comprising inert gas and hydrocarbons and the isotropic pitch product composition as a bottoms liquid stream, wherein said overhead vapor stream comprising inert gas and hydrocarbons has a temperature that is above that of said isotropic pitch product composition as a bottoms liquid stream and the isotropic pitch product composition has a softening point of no less than 100°C;providing, to a rectification column comprising a shell containing a second vapor-liquid contacting zone having one or more second vapor-liquid contacting elements, a partial condenser, a vapor-liquid phase separator and a reflux pump, the pressure at all points in the shell, partial condenser and vapor-liquid phase separator is less than the lowest pressure at any point in the stripper column, and the overhead vapor stream comprising inert gas and hydrocarbons is introduced at a point below the second vapor-liquid contacting zone; and removing, from said rectification column, at least an overhead product gas stream, anoverhead product liquid hydrocarbon stream, and a bottoms product liquid hydrocarbon stream having a T10 of no less than 315°C (600°F).

26. The method for producing an isotropic pitch product composition of claim 25, comprising removing from said rectification column an overhead product liquid water stream.

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