EP4179042A1 - Pitch process and products - Google Patents
Pitch process and productsInfo
- Publication number
- EP4179042A1 EP4179042A1 EP20945287.9A EP20945287A EP4179042A1 EP 4179042 A1 EP4179042 A1 EP 4179042A1 EP 20945287 A EP20945287 A EP 20945287A EP 4179042 A1 EP4179042 A1 EP 4179042A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- reactor
- stage reactor
- stage
- pressure
- mesophase
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 52
- 230000008569 process Effects 0.000 title claims abstract description 51
- 239000007788 liquid Substances 0.000 claims abstract description 61
- 239000011295 pitch Substances 0.000 claims abstract description 59
- 239000011302 mesophase pitch Substances 0.000 claims abstract description 55
- 125000003118 aryl group Chemical group 0.000 claims abstract description 24
- 238000012719 thermal polymerization Methods 0.000 claims abstract description 18
- 239000000835 fiber Substances 0.000 claims abstract description 8
- 239000006260 foam Substances 0.000 claims abstract description 6
- 239000007791 liquid phase Substances 0.000 claims description 27
- 229930195733 hydrocarbon Natural products 0.000 claims description 14
- 150000002430 hydrocarbons Chemical class 0.000 claims description 14
- 239000012808 vapor phase Substances 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 4
- 230000000379 polymerizing effect Effects 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
- 239000000047 product Substances 0.000 description 28
- 238000006243 chemical reaction Methods 0.000 description 27
- 150000001491 aromatic compounds Chemical class 0.000 description 13
- 238000013459 approach Methods 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 10
- 230000009286 beneficial effect Effects 0.000 description 9
- 239000012530 fluid Substances 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 6
- 239000000571 coke Substances 0.000 description 6
- 238000004939 coking Methods 0.000 description 6
- 238000001816 cooling Methods 0.000 description 6
- 238000013461 design Methods 0.000 description 6
- 239000006227 byproduct Substances 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000004215 Carbon black (E152) Substances 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000376 reactant Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 238000009834 vaporization Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- 241000251468 Actinopterygii Species 0.000 description 1
- 239000004902 Softening Agent Substances 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000010692 aromatic oil Substances 0.000 description 1
- 238000011956 best available technology Methods 0.000 description 1
- 238000004581 coalescence Methods 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000020335 dealkylation Effects 0.000 description 1
- 238000006900 dealkylation reaction Methods 0.000 description 1
- 238000005235 decoking Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000013213 extrapolation Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000005206 flow analysis Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000011027 product recovery Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 230000005514 two-phase flow Effects 0.000 description 1
- 238000002604 ultrasonography Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
- C10C3/00—Working-up pitch, asphalt, bitumen
- C10C3/002—Working-up pitch, asphalt, bitumen by thermal means
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
- C10C3/00—Working-up pitch, asphalt, bitumen
- C10C3/02—Working-up pitch, asphalt, bitumen by chemical means reaction
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10C—WORKING-UP PITCH, ASPHALT, BITUMEN, TAR; PYROLIGNEOUS ACID
- C10C3/00—Working-up pitch, asphalt, bitumen
- C10C3/02—Working-up pitch, asphalt, bitumen by chemical means reaction
- C10C3/026—Working-up pitch, asphalt, bitumen by chemical means reaction with organic compounds
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G9/14—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils in pipes or coils with or without auxiliary means, e.g. digesters, soaking drums, expansion means
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G9/00—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils
- C10G9/40—Thermal non-catalytic cracking, in the absence of hydrogen, of hydrocarbon oils by indirect contact with preheated fluid other than hot combustion gases
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
- D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
- D01F9/145—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from pitch or distillation residues
Definitions
- the present invention provides a two stage process for producing mesophase pitch from an aromatic liquid comprising thermally polymerizing an aromatic liquid feed comprising at least a portion of 2 and 3 ring aromatics by charging said feed to a first stage reactor operating at thermal polymerization conditions including a temperature high enough to induce thermal polymerization and a pressure high enough to maintain at least a portion of said 2 and 3 ring aromatics in the liquid phase to convert at least 20 wt % of said 2 and 3 ring aromatics into isotropic pitch and into light, normally gaseous hydrocarbons and discharging a first stage reactor effluent, flashing said first stage reactor effluent to remove at least a majority of said light normally gaseous hydrocarbons in a flash zone having an absolute pressure no more than half the absolute pressure in said first stage thermal polymerization reactor to produce a flash effluent liquid stream, forming mesophase pitch from said flash effluent liquid stream in a second stage reactor at meso
- the invention provides a carbon fiber, graphite fiber or carbon foam made from mesophase pitch by thermally polymerizing an aromatic liquid feed comprising at least a portion of 2 and 3 ring aromatics by charging said feed to a first stage reactor operating at thermal polymerization conditions including a temperature high enough to induce thermal polymerization and a pressure high enough to maintain at least a portion of said 2 and 3 ring aromatics in the liquid phase to convert at least 20 wt % of said 2 and 3 ring aromatics into isotropic pitch and into light, normally gaseous hydrocarbons and discharging a first stage reactor effluent, flashing said first stage reactor effluent to remove at least a majority of said light normally gaseous hydrocarbons in a flash zone having an absolute pressure no more than 1 ⁇ 2 the absolute pressure in said first stage thermal polymerization reactor to produce a flash effluent liquid stream, forming mesophase pitch from said flash effluent liquid stream in a second stage reactor at mesophase forming conditions including a pressure
- FIG. 1 is a simplified view of an embodiment of a two-stage process for producing mesophase pitch from an aromatic liquid.
- a fresh feedstock consisting of a filtered aromatic liquid 1 is fed into feed tank 2, then charged via pump 3 into line 103, mixed with a recycled heavy aromatic stream in line 4 and discharged into mixed feed drum 5.
- the mixed feed is withdrawn via line 106 and pump 7 increases the pressure for discharge into fired heater 8.
- Heated mixed feed is then charged via line 108 into a first stage tubular reactor 9, wherein the feed is partially converted into a mixture of isotropic and mesophase pitch.
- the reactor effluent is discharged via line 10 from the first stage reactor and passed through a pressure letdown valve 11, reducing the pressure.
- the flashed partially converted mixture is then mixed with superheated steam added via line 12, produced by passing boiler feed water in line 113 through steam boiler/superheater 13.
- the steam to hydrocarbon molar ratio is usually more than 1:1, e.g., 3:1.
- the resulting mixture in line 14 is fed to the second stage tubular reactor 15 where additional mesophase is formed.
- the second stage reactor effluent is discharged via line 16 into vapor/liquid separator 17.
- the liquid stream 18 leaving this separator contains 85-90 wt % mesophase pitch (with the balance being primarily isotropic pitch) and represents an 88 wt % yield on the fresh feedstock.
- Stream 18 is recovered for storage and distribution by feeding it to pitch cooling and solidification system 19.
- the vapor 20 from vapor/liquid separator 17 is cooled to 155 °C in shell and tube heat exchanger 21 using glycol/water cooling stream 22 from glycol cooling system 23. Any other conventional cooling means may be used, such as feed/product exchange, air cooling via fin-fan coolers, or cooling water from a cooling tower.
- the cooled vapor stream 24 passes into vapor/liquid separator 25, where a heavy aromatic stream 26 is drawn off the bottom and briefly stored in heavy aromatic tank 27.
- This heavy aromatic material is then withdrawn via line 127 and pump 28 and either recycled via line 29 to feed drum 5 or cooled with air cooler 30, sent via line 131 to heavy aromatic tank 31 for storage and pumped out via line 133, pump 32, and line 132 for sale as a valuable byproduct, e.g., an aromatic rich solvent.
- the overhead vapor removed via 33 from vapor/liquid separator 25 is cooled to 49 °C in air cooler 34 and discharged via line 134 into three-phase separator 35.
- a vapor phase is removed overhead via line 36.
- Water from steam condensate is removed from the bottom of the separator via line 37.
- a light hydrocarbon stream is removed via line 38 and discharged into light hydrocarbon storage tank 39, where it is pumped out via line 140, pump 40 and line 141.
- isotropic pitch which is “contaminated” with more than 1 wt % mesophase, preferably more than 2 - 5 wt % mesophase, and ideally more than 10 - 25 wt % mesophase or even more.
- This contaminated product from the first stage is neither “fish nor fowl” and has little or no value as an isotropic pitch product, but it is an ideal charge stock to the second reaction stage, where additional thermal polymerization will make a saleable mesophase product. Flashing the first stage removes light gasses formed as a byproduct of thermal polymerization and thermal dealkylation and also preferably removes 2 and 3 ring aromatic compounds.
- the thermal reactions forming isotropic pitch and to a limited extent mesophase pitch are the same but the reactants are somewhat different and the amount of mesophase which can be tolerated is often significantly reduced.
- the reactants in a CSTR can be different because the CSTR typically consists of a stirred vessel with stirred liquid in the bottom and vapor space above.
- the materials in the vapor phase have a harder time reacting with materials in the liquid phase since there is greatly reduced contact as compared to the intense contact of vapor and liquid in a tubular reactor.
- the amount of mesophase in the first stage product which can be tolerated will usually be less than can be tolerated in a tubular reactor.
- a tubular reactor keeps everything moving and the walls thereof are wiped clean, to a great extent, by the fluid flowing through.
- the pressure in the second stage should be reduced at least 50 %, in absolute terms, as compared to the pressure in the first stage.
- the pressure is sufficiently low, and temperature sufficiently high, to vaporize at least a molar majority of 2 and 3 ring aromatic compounds. These 2 and 3 ring aromatics tend to interfere with mesophase formation so they are best removed.
- a CSTR reactor is used, even greater care is required in design and operation to avoid plugging the thermal reactor.
- the mesophase content will be generally above 50 wt
- CSTR operation can be prolonged to some extent by using higher impeller speeds and/or swing reactors.
- One advantage that CSTRs have over tubular reactors is that they are cheaper to build and require only a small footprint.
- HEAT BALANCE The heat requirements of the second stage of the process are preferably and largely supplied by the feed.
- the feed to and the product from the first stage reactor can tolerate significant conventional heating, e.g., in a fired heater or immersion in a molten metal or molten salt bath.
- the thermal reactions occurring in the first reactor are largely governed by time and temperature. Reaction rates roughly double for every 10 °C temperature increase so running the first reactor hotter can permit reduction in the reactor size.
- the first stage reactor effluent will cool significantly when flashed to remove light ends and 2 and 3 ring aromatic compounds. The residual liquid from this flash will still be very hot, in many cases sufficiently hot to induce thermal polymerization in the second stage reactor. Additional heat may be added to the second stage reactor in the form of a superheated fluid, preferably superheated steam.
- the second stage reactor operates at much lower pressure than the first stage, so construction costs can be reduced significantly due to the lower pressure operation.
- the reactor residence time may be increased by using a larger inside diameter and/or longer length tube reactor or by using a larger CSTR. Additional residence time may be achieved by using multiple reactors in series or recycling some of the second reactor effluent back to the first reactor. Normally once through operation is preferred, both to reduce capital and operating costs and because the liquid effluent from the second reactor is mesophase rich and cokes readily.
- heat may also be added by mixing or mechanical energy. Energy can be added by a conventional mixing impeller. There is no free energy, rather the electrical or steam driven pump transfers energy into the second reactor by intense mixing.
- a relatively pure isotropic pitch may be recovered as an intermediate product when conversion in the first tubular reactor is limited by the amount of mesophase which can be tolerated in the product.
- operating the first stage reactor to convert most of the feed to isotropic pitch but limiting conversion so that the intermediate pitch product has less than 2 wt % mesophase, or 1 wt % mesophase, or 0.5 wt % mesophase or less.
- This will not maximize production of mesophase overall, but it will allow recovery of some isotropic pitch product from the intermediate separator and some mesophase pitch product downstream of the second thermal reactor. It will also be possible to obtain a relatively pure isotropic pitch product as a product from the second thermal reactor.
- the first thermal reactor converts a desired amount of aromatic feed to isotropic pitch, usually 10 - 60 wt %, preferably less than 50 wt % conversion to isotropic pitch, with conversion to the desired isotropic pitch content, typically about 70 wt %, or 80 wt %, or 90 wt % in the second thermal reactor. It will usually be necessary to flash intermediate the two thermal reactors, as usually the second thermal reactor will be designed for lower pressure operation than the first thermal reactor, but it is beneficial to keep more of the 2 and 3 ring aromatic compounds in the liquid phase, to facilitate their conversion in the second thermal reactor.
- a good flash approach is to reduce the pressure sufficiently to remove most of the lighter byproducts and most of the 2 ring aromatics while keeping at least a molar majority of the 3 ring aromatics in the residual liquid phase removed from the flash.
- This residual liquid phase may then be charged to the second thermal reactor, preferably with superheated fluid injection after the flash.
- CASE 2 - TUBULAR REACTOR TO CSTR This approach can be similar to the Case 1 approach.
- the first thermal reactor is a tubular reactor while the second is a CSTR.
- the pressure will be lower in the CSTR which favors vaporization of 2 and 3 ring aromatics and which favors mesophase formation.
- CASE 3 - CSTR TO TUBULAR REACTOR The first thermal reactor is a stirred tank reactor.
- the first reactor can leave most of the feed unconverted so the fluids are fairly easy to stir.
- the coking tendency of the material increases as the percent pitch, especially the percent mesophase pitch increases.
- the second thermal reactor which is a tube operating in fully developed turbulent flow.
- the first reactor should operate at a relatively high pressure sufficient to maintain at least a majority of the 3 ring aromatics in the liquid phase, preferably with most of the 2 ring aromatics in the liquid phase. These aromatics can be converted to pitch, but liquid phase operation is preferred.
- Flashing or some means of pressure reduction will usually be necessary intermediate the first and second reactors, to remove at least a majority of any remaining unconverted 2 and 3 ring aromatic compounds.
- This approach CSTR to tubular reactor, allows for a relatively compact and simple first reactor, with increased fluidity largely offsetting coking risks, and the tubular reactor can rely on turbulent flow to reduce coking.
- CASE 4 - 2 CSTRs In this approach, stirred tank reactors are used for both the first and second thermal reactors. Pressures are relatively high in the first reactor, to keep 2 and 3 ring aromatics in the liquid phase. The flashing step removes most of the 2 and 3 ring aromatics which favors thermal conversion to mesophase in the second thermal reactor.
- a CSTR reactor will have a range of liquid residence times, but a tubular reactor does not.
- the process of the present invention provides what is believed to be the most cost-effective method of producing mesophase pitch from aromatic liquids. Much of the benefit is achieved by close coupling of the first and second reactor stages. There is no need to cool down the isotropic pitch material, and little or no preheating of it is needed upstream of the second stage of the reactor.
- the process is flexible, and may be used to recover isotropic pitch from the flash vessel intermediate the two stages.
- the process provides a way to produce pure isotropic pitch in a single stage or even from two thermal reactors from an aromatic rich liquid.
- the process may also be used to produce a mesophase pitch from an isotropic pitch feed when desired.
- Tubular reactors with their excellent mixing characteristics, their ability to resist fouling and their ability to add some heat via heating of the tube walls with electricity have been proven to work well in our laboratory.
- the relatively large footprint and relatively low capacity and the careful fabrication required when some types of electrical heating are used may be significant enough concerns to merit the use of CSTRs in either the first or second reactor or both.
- CSTRs are probably slightly less chemically efficient than a tube reactor when used for the first stage reactor.
- the 2 and 3 ring aromatic compounds will concentrate in the vapor phase above the liquid in the CSTR.
- the first thermal reactor with sufficient pressure to maintain 3 ring aromatic compounds primarily in the liquid phase, preferably 60, 70, 80, 90% or more of these in the liquid phase.
- the process will still work if the 2 rings aromatics are in the vapor phase at times or continuously.
- a refiner might focus on keeping at least a majority, preferably 60, 70, 80, 90% or more of the 2 rings aromatics in the liquid phase, trusting to vapor/liquid equilibrium to keep the 3 ring aromatics in the liquid phase to an even greater extent.
- the aromatic liquid feeds contemplated for use herein will contain significant amounts of 2 and 3 ring aromatics, which have relatively low value/price. The economics of the process are better if this low-cost feed can be converted to higher value mesophase pitch.
- Conditions in the first thermal reaction zone will preferably include a temperature of 455 to 540 °C, preferably 480 to 510 °C, and ideally 495 to 500 °C. Pressure should be enough to maintain the desired amount of 2 or 3 ring aromatics in the liquid phase and preferably from 7 to 210 bar, more preferably 35 to 170 bar, ideally 70 to 140 bar. Residence time is primarily dependent on temperature and conversion desired, but it will typically range from 10 seconds to 10 minutes, preferably 0.5 to 5 minutes, and ideally 2 - 3 minutes. Conditions in the second thermal reaction zone will typically involve a significantly lower pressure and shorter residence time.
- Pressure should be less than 1 ⁇ 2 the absolute overall pressure in the first thermal reactor, and typically will be 7 bar or less, preferably less than 3.5 bar and ideally 2 bar or less or even atmospheric or sub-atmospheric pressure. Residence time required to achieve the desired conversion of feed to mesophase will typically be under a minute, preferably 0.1 to 10 seconds, ideally 0.2 to 2 seconds.
- the pressure and temperature in the first and second zones lend themselves to a relatively simple commercial process design with all or essentially all of the heat and pressure energy added at the inlet of the first reactor. There will be plenty of pressure to get reactants through the first stage reactor and into the flash or second thermal reactor.
- the temperature in the first reactor can be selected to be high enough so that after flashing, the liquid phase is at or near the temperature required in the second stage reactor. In this way, all the heat required can be added to the feed to the first reactor. All the pressure required to get reactants through the process can be added upstream of the first reactor.
- the flash zone is an essential concept to permit vaporization of 2 and 3 rings aromatics from the isotropic pitch "product", but a flash vessel is not, per se, a requirement. It is possible to flash the isotropic pitch liquid relying solely on fluid dynamics in a tubular reactor, preferably with an enlarged inside diameter tube in the second reactor section.
- the isotropic pitch rich liquid discharged into the tube forming the second thermal reactor will flash in the tube so that the liquid phase will be depleted in 2 and 3 rings aromatics. It is possible to have a flash drum at relatively high pressure, sufficiently low to permit removal of most of the 2 and 3 rings aromatics from the isotropic pitch discharged into this high-pressure flash. Then the liquid phase from the high-pressure flash may be charged into the second thermal reactor. It is possible to have a flash drum at relatively low pressure to facilitate removal of an increased amount of 2 and 3 rings aromatics.
- DIRECT CONTACT HEATING/STRIPPING A superheated fluid, preferably superheated steam, can be added to supply any heating or stripping needs of the process.
- Superheated steam can be added in minor amounts, say 1 to 10 wt % of the liquid, when little heating is required and modest stripping or removal of 2 and/or 3 rings aromatics is required. There is no upper limit on superheated steam addition, with amounts up to 50 wt %, 100 wt %, 200 wt % or more being contemplated when some heating of liquid is required. Although steam is preferred, other superheated fluids may be used when desired, e.g., hydrogen, normally gaseous hydrocarbons and the like. Our process has multiple applications.
- the process can be used to make mesophase pitch from an aromatic oil feed using 2 plug flow reactors in series, preferably with pressure reduction intermediate the two reactors sufficient to vaporize at least a majority of 2 ring aromatic compounds in the feed or produced by thermal polymerization in the first stage reactor.
- the process may be used to produce an isotropic pitch and a mesophase pitch using two thermal reactors in series.
- the first thermal reactor should operate at a pressure sufficient to maintain at least a majority of 3 ring aromatic compounds in the feed in the liquid phase in the first reactor and a temperature sufficient to thermally polymerize at least a majority of 3 ring and heavier aromatics to isotropic pitch to produce a first reactor effluent comprising isotropic pitch and no more than a predetermined amount of mesophase pitch, typically less than 1 wt %.
- the first reactor effluent is flashed into a flash drum operating at a pressure sufficiently low to vaporize at least a majority of 2 ring aromatic compounds present in the first reactor effluent.
- a portion of flash drum liquid is withdrawn as an isotropic pitch product of the process and the remainder charged to a second thermal reactor operating at a pressure low enough to vaporize at least a majority of 2 ring aromatic compounds present and for a time and temperature sufficient to convert at least a majority by weight of liquid feed to said second reactor to mesophase pitch.
- a superheated fluid such as steam or a hydrocarbon is charged to the second reactor for heating.
- the first thermal reactor may be either a continuous stirred tank reactor or a tubular reactor.
- the second thermal reactor may be either a continuous stirred tank reactor or a tubular reactor.
- the pressure in the first stage reactor is from 14 to 210 bar, more preferably 35 to 140 bar, ideally about 68 to 70 bar.
- the pressure in the second stage reactor is one tenth or less that of the first stage reactor, more preferably from 7 bar to sub-atmospheric, ideally from atmospheric to 5 bar.
- the first stage reactor is preferably run at thermal polymerization conditions sufficient to make a first stage reactor isotropic pitch intermediate product contaminated with a sufficient amount of mesophase pitch to make said intermediate unsuitable for use as isotropic pitch.
- the first stage reactor effluent isotropic pitch intermediate product contains more than 1.0, 1.5, 2, 5, 10, 15, 20, 25, or 30 wt % mesophase pitch.
- the “flash zone” is merely a pressure let down valve without any removal of the vapor.
- the two-phase flow would be fed to the second stage reactor.
- a vapor/liquid separator may be used to remove the vapor and then only the liquid is sent to the second stage reactor.
- the overhead vapor from the first or flash vapor/liquid separator and vapors recovered from the second stage reactor effluent will be combined for use as fuel or other product recovery. Recycling of heavy liquid will frequently be beneficial. If conversion in the first stage reactor is relatively low, e.g., 20 to 50 wt %, it will usually be beneficial to recycle some of the first stage reactor effluent to mix with the reactor feed.
- the heavy distillate from the second reactor may be recycled.
- Preferably all liquid recycle is to the first reactor, though in some instances it may be preferred to have reactor 1 effluent liquid recycled to reactor 1 and reactor 2 effluent liquid recycled to mix with feed to the second reactor.
- Recycle may be necessary to improve the economics of the process, especially when the conversions per pass are relatively low. It may be essential that steam or some other vapor, preferably a superheated vapor, be added to the feed entering the second stage reactor. Presence of this vapor reduces partial pressure, provides added thermal inertia, creates high velocities, and provides better dispersion of the pitch droplets.
- vapor While any vapor could be used, we prefer a low molecular weight, condensable gas that is non-reactive and has very low solubility in the mesophase pitch. Steam is the most preferred.
- the amount of vapor as a percentage of the weight of the liquid feed, could vary from 10 - 1000%, preferably 150 - 400%, more preferred 250 - 350%.
- outlet pressures are about 2.75 bar plus downstream equipment pressure drop. It would be possible to pull a vacuum on the final vent gas to reduce the outlet pressure further if desired.
- Recommended inlet pressures for the second reactor may range from 3.5 to 70 bar, preferably under 35 bar, more preferably 7 to 14 bar.
- Suitable operating temperatures for both the first and second stage reactors may range from 400 - 595 °C, preferably 425 to 525 °C and more preferably 482 - 510 °C.
- the gas phase is continuous and the liquid phase is discontinuous. At the high specific flowrate in a tubular reactor forming mesophase, the shear rate in the reactor is very high.
- the pressure drop in the 9.5 mm (3/8”) reactor tube was 4 to 6 bar (60 to 90 psi).
- this flow regime may be described as mist annular.
- This relatively small spherical size combined with very turbulent flow allows for very rapid mass and heat transfer between the liquid and steam phases. While there may be some collision of these spheres with other spheres resulting in coalescence, they are rapidly disintegrated into smaller spheres again as a result of the high shear.
- the vapor fraction is greater than 99% by volume.
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Abstract
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PCT/US2020/041811 WO2022015281A1 (en) | 2020-07-13 | 2020-07-13 | Pitch process and products |
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EP4179042A1 true EP4179042A1 (en) | 2023-05-17 |
EP4179042A4 EP4179042A4 (en) | 2024-04-03 |
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EP (1) | EP4179042A4 (en) |
JP (1) | JP7502552B2 (en) |
KR (1) | KR20230037591A (en) |
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WO (1) | WO2022015281A1 (en) |
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CN114410332B (en) * | 2022-02-18 | 2024-03-15 | 宝武碳业科技股份有限公司 | Mesophase pitch and preparation method thereof |
CN114405433A (en) * | 2022-02-18 | 2022-04-29 | 宝武碳业科技股份有限公司 | Multi-stage reaction device and preparation method of mesophase pitch for high-purity spinning |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US4026788A (en) * | 1973-12-11 | 1977-05-31 | Union Carbide Corporation | Process for producing mesophase pitch |
JPS61163991A (en) * | 1985-01-16 | 1986-07-24 | Fuji Standard Res Kk | Continuously producing pitch suitable as raw material of carbon fiber |
JP2529167B2 (en) * | 1987-07-20 | 1996-08-28 | 出光興産株式会社 | Method for manufacturing pitch for carbon material |
US9376626B1 (en) * | 2011-04-28 | 2016-06-28 | Advanced Carbon Products, LLC | Turbulent mesophase pitch process and products |
US9222027B1 (en) * | 2012-04-10 | 2015-12-29 | Advanced Carbon Products, LLC | Single stage pitch process and product |
PL3469026T3 (en) | 2016-06-14 | 2021-02-22 | Acp Technologies, Llc | Turbulent mesophase pitch process and products |
-
2020
- 2020-07-13 JP JP2023501203A patent/JP7502552B2/en active Active
- 2020-07-13 CN CN202080102798.4A patent/CN116134115A/en active Pending
- 2020-07-13 WO PCT/US2020/041811 patent/WO2022015281A1/en unknown
- 2020-07-13 KR KR1020237004072A patent/KR20230037591A/en unknown
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JP2023536798A (en) | 2023-08-30 |
CN116134115A (en) | 2023-05-16 |
EP4179042A4 (en) | 2024-04-03 |
JP7502552B2 (en) | 2024-06-18 |
KR20230037591A (en) | 2023-03-16 |
WO2022015281A1 (en) | 2022-01-20 |
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