This invention relates to a reactor having reduced pressure drop across the catalytic bed of the reactor. This invention also relates to the use of the reactor in the treatment of feeds such as the conversion of organic compounds and the removal of undesired components from feeds.
The chemical and petroleum industry commonly uses single phase reactors to process fluids across a fixed catalytic bed for the hydroprocessing of feed streams. Many times the effectiveness of these reactors is limited by the amount of pressure drop across the catalytic bed because high pressure drop across the catalytic bed of the reactor reduces the throughput capacity of the reactor. Also, high pressure drop across the catalytic bed of the reactor can cause the catalyst particles to crush which results in the restriction in the flow of fluid through the reactor leading to even higher pressure drops.
The pressure drop of the reactor is often the limiting factor in throughput capacity. This can result in significant costs for expansion or de-bottlenecking of existing facilities and limit the use of existing equipment in new or retrofitted installations. Traditional techniques for controlling pressure drop include adding compressions or pumping equipment to equipment and installation of larger diameter reactors and/or piping. Another technique for controlling pressure drop, as disclosed in U.S. Pat. No. 5,837,128, involves grading the catalyst particles by pressure drop and then loading the particles into the reactor with the particles having the lowest pressure drop near the inlet and particles having the highest pressure drop near the outlet.
In accordance with the present invention, there is provided a vertical reactor having reduced pressure drop across its catalytic bed. The reactor comprises:
In one embodiment of the present invention, the vertical reactor is configured to accept feedstock through the upper and lower portions of the vessel and remove effluent through the middle portion of the vessel. In this embodiment, the reactor comprises:
In another embodiment of the present invention, the vertical reactor is configured to accept feedstock through the middle portion of the vessel and remove effluent through the upper and lower portions of the vessel. In this embodiment, the reactor comprises:
The vertical reactor of the present invention finds particular application in the treatment of feeds such as the conversion of organic compounds and the removal of undesired components from feeds, e.g., the desulfurization of hydrocarbon streams (desulfurization of streams containing containing benzene, toluene, or mixtures thereof), and the adsorption of molecular species.
The benefit of the present invention with respect to single phase flow can be shown by reference to the Ergun equation, which is set forth below.
Reference to the Ergun equation shows that reducing the mass velocity of the fluid (W) by a factor of about 2, while holding all other factors constant, results in a pressure drop reduction by a factor of about 4. Also, reducing the length of bed through which the fluid flows by a factor of about 2 results in an overall pressure drop reduction of a factor of about 8, resulting in approximately a 87.5% pressure drop reduction across the catalyst in the reactor.
Retrofitting an existing vessel with one inlet and one outlet, where the flow through the existing vessel is restricted by the pressure drop across the packing material, can reduce the pressure drop to approximately 10 to 20% of its former amount. This will allow the bed to either handle additional fresh feed, up to about 2 or 3 times the original throughput, or operate longer before regeneration is required to reduce pressure drop back to an acceptable operating level.
As used herein, the term “distributor” refers to a collection mechanism for balancing the distribution of the feed into the reactor and effluent out of the reactor. These collection mechanisms are known to persons skilled in the art and are located proximal to the middle portion of the vessel. Operation of the reactor of the present invention is not limited to any particular distributor design. The distributor shown in
An advantage of these type of distributors, e.g., concentric design distributors and circumferential wall design distributors are their ease of unloading of the catalyst, e.g., middle portion of the reactor is open to allow catalyst material to flow to the bottom of the reactor for unloading.
Examples of suitable filler material that can be included in the filler region of the reactor include inert ceramic balls or pellets, fired clay balls or pellets, and alumina balls or pellets.
The present invention finds particular applicable in reactors with flow in a single direction, said direction being oriented perpendicular to a given cross-section of the reactor. The reactor can be operated either in the liquid phase or vapor phase. The present invention can be applied to a new reactor as well as retrofitting to an existing reactor.
The vertical reactor of the present invention finds particular application in the treatment of feeds such as the conversion of organic compounds and the removal of undesired components from organic feeds.
Processes that find particular application include, as non-limiting examples, the following:
(A) Cracking of hydrocarbons with reaction conditions including a temperature of from about 300° C. to about 700° C., a pressure of from about 0.1 atmosphere (bar) to about 30 atmospheres and weight hourly space velocity of from about 0.1 hr−1 to about 20 hr−1.
(B) Dehydrogenating hydrocarbon compounds with reaction conditions including a temperature of from about 300° C. to about 700° C., a pressure of from about 0.1 atmosphere (bar) to about 10 atmospheres and weight hourly space velocity of from about 0.1 hr−1 to about 20 hr−1.
(C) Converting paraffins to aromatics with reaction conditions including from about 300° C. to about 700° C., a pressure of from about 0.1 atmosphere (bar) to about 60 atmospheres and weight hourly space velocity of from about 0.5 hr−1 to about 400 hr−1 and a hydrogen/hydrocarbon mole ratio of from about 0 to about 20.
(D) Converting olefins to aromatics, e.g., benzene, toluene and xylene, with reaction conditions including a temperature from about 100° C. to about 700° C., a pressure of from about 0.1 atmosphere (bar) to about 60 atmospheres, weight hourly space velocity of from about 0.5 hr−1 to about 400 hr−1, and a hydrogen/hydrocarbon mole ratio of from about 0 to about 20.
(E) Converting alcohols, e.g., methanol, or ethers, e.g., dimethylether, or mixtures thereof to hydrocarbons, including olefins and/or aromatics with reaction conditions including a temperature from about 275° C. to about 600° C., a pressure of from about 0.5 atmosphere (bar) to about 50 atmospheres, weight hourly space velocity of from about 0.5 hr−1 to about 100 hr−1.
(F) Isomerization of dialkyl substituted benzenes, e.g., xylenes. Typical reaction conditions including a temperature from about 230° C. to about 510° C., a pressure of from about 1 atmosphere to about 50 atmospheres, a weight hourly space velocity of from about 0.1 hr−1 to about 200 hr−1 and a hydrogen/hydrocarbon mole ratio of from 0 (no added hydrogen) to about 100.
(G) Alkylating aromatic hydrocarbons, e.g., benzene and alkylbenzenes in the presence of an alkylating agent, e.g., olefins, formaldehyde, alkyl halides and alcohols, with reaction conditions including a temperature from about 250° C. to about 500° C., a pressure of from about atmospheric to about 200 atmospheres, weight hourly space velocity of from about 2 hr−1 to about 2000 hr−1 and an aromatic hydrocarbon/alkylating agent mole ratio of from about 1/1 to about 20/1.
(H) Transalkylating aromatic hydrocarbons in the presence of polyalkylaromatic hydrocarbons with reaction conditions including a temperature from about 340° C. to about 500° C., a pressure of from about atmospheric to about 200 atmospheres, weight hourly space velocity of from about 10 hr−1 to about 1000 hr−1, and an aromatic hydrocarbon/polyalkylaromatic hydrocarbon mole ratio of from about 1/1 to about 16/1.
(I) Dewaxing of hydrocarbons by selectively removing straight chain paraffins. The reaction conditions are dependent in large measure on the feed used and upon the desired pour point. Typical reaction conditions include a temperature between about 200° C. and 450° C., a pressure up to 3,000 psig and a liquid hourly space velocity from about 0.1 to about 20.
(J) Alkylation of a reformate containing substantial quantities of benzene and toluene with fuel gas containing short chain olefins (e.g., ethylene and propylene) to produce mono- and dialkylates. Preferred reaction conditions include temperatures from about 100° C. to about 250° C., a pressure of from about 100 to about 800 psig, a WHSV-olefin from about 0.4 hr−1 to about 0.8 hr−1, a WHSV-reformate of from about 1 hr−1 to about 2 hr−1 and, optionally, a gas recycle from about 1.5 to 2.5 vol/vol fuel gas feed.
(K) Alkylation of phenols with olefins or equivalent alcohols to provide long chain alkyl phenols. Typical reaction conditions include temperatures from about 100° C. to about 250° C., pressures from about 1 to 300 psig and total WHSV of from about 2 hr−1 to about 10 hr−1.
(L) Reaction of alcohols with olefins to produce mixed ethers, e.g., the reaction of methanol with isobutene and/or isopentene to provide methyl-t-butyl ether (MTBE) and/or t-amyl methyl ether (TAME). Typical conversion conditions include temperatures from about 20° C. to about 200° C., pressures from 2 to about 200 atm, WHSV (gram-olefin per hour gram-catalyst) from about 0.1 hr−1 to about 200 hr−1 and an alcohol to olefin molar feed ratio from about 0.1/1 to about 5/1.
(M) Disproportionation of alkyl aromatics, e.g., the disproportionation of toluene to make benzene and paraxylene and the disproportionation of cumene to make benzene and diisopropylbenzene. Typical reaction conditions include a temperature of from about 200° C. to about 760° C., a pressure of from about atmospheric to about 60 atmosphere (bar), and a WHSV of from about 0.1 hr−1 to about 30 hr−1.
(N) Selectively separating hydrocarbons by adsorption of the hydrocarbons. Examples of hydrocarbon separation include xylene isomer separation and separating olefins from a feed stream containing olefins and paraffins.
(O) Oligomerization of straight and branched chain olefins having from about 2 to about 5 carbon atoms. The oligomers which are the products of the process are medium to heavy olefins which are useful for both fuels, i.e., gasoline or a gasoline blending stock, and chemicals. The oligomerization process is generally carried out by contacting the olefin feedstock in a gaseous state phase with a catalyst at a temperature in the range of from about 250° C. to about 800° C., a LHSV of from about 0.2 to about 50 and a hydrocarbon partial pressure of from about 0.1 to about 50 atmospheres. Temperatures below about 250° C. may be used to oligomerize the feedstock when the feedstock is in the liquid phase when contacting the catalyst. Thus, when the olefin feedstock contacts the catalyst in the liquid phase, temperatures of from about 10° C. to about 250° C. may be used.
(P) Dealkylation of alkylaromatic compounds. In the case of ethylbenzene, the ethylbenzene can be converted to benzene and ethane. Typical reaction conditions including a temperature from about 230° C. to about 510° C., a pressure of from about 1 atmosphere to about 50 atmospheres, a weight hourly space velocity of from about 0.1 hr−1 to about 200 hr−1 and a hydrogen/hydrocarbon mole ratio of from 0 (no added hydrogen) to about 100.
(Q) Isomerization of ethylbenzene to form xylenes. Exemplary conditions include a temperature from about 300° C. to about 550° C., a pressure of from about 50 to 500 psig, and a LHSV of from about 1 to about 20.
(R) Isomerization of dialkylnaphthalene, e.g., dimethylnaphthalene, to form a mixture of isomers. Of the dimethylnapthalene isomers, 2,6-dimethylnapthalene is a key intermediate in the production of 2,6-napthalenedicarboxylic acid, a valuable monomer for specialty polyester manufacture. Typical reaction conditions including a temperature from about 230° C. to about 510° C., a pressure of from about 1 atmosphere to about 50 atmospheres, a weight hourly space velocity of from about 0.1 hr−1 to about 200 hr−1 and a hydrogen/hydrocarbon mole ratio of from 0 (no added hydrogen) to about 100.
(S) Disproportionation of mono-alkyl substituted naphthalenes, e.g., disproportionation of mono-methyl naphthalene to dimethyl-naphthalene and naphthalene. Typical reaction conditions including a temperature of from about 200° C. to about 760° C., a pressure of from about atmospheric to about 60 atmospheres and a weight hourly space velocity of from about 0.08 hr−1 to about 20 hr−1.
(T) Oxidation of alkyl substituted aromatic compounds, e.g., conversion of para-xylene to para-terephthalic acid and the conversion of cumene to phenol and acetone and the conversion of 2,6-dimethylnapthalene to 2,6-napthalenedicarboxylic acid.
(U) Desulfurization of an organic feed, e.g., desulfurization of a hydrocarbon stream, such as a stream containing benzene, toluene, or mixtures thereof.
(V) Denitrogenation of an organic feed such as the denitrogenation of a hydrocarbon feed comprising a petroluem fraction.
In general, the conversion conditions include a temperature from about 100° C. to about 760° C., a pressure of from about 0.1 atmosphere (bar) to about 200 atmospheres (bar), weight hourly space velocity of from about 0.08 hr−1 to about 2000 hr−1, and a hydrogen/organic, e.g., hydrocarbon compound, molar ratio of from about 0 to about 100.
The catalyst used in the reactor will depend on the process carried out in the reactor. Such catalysts will usually include amorphous metal oxides, such as alumina and silica, or crystalline molecular sieves.
Molecular sieves finding application include any of the naturally occurring or synthetic crystalline molecular sieves. Examples of these molecular sieves include large pore molecular sieves, intermediate pore size molecular sieves, and small pore molecular sieves. These materials are described in “Atlas of Zeolite Structure Types”, eds. Ch. Baerlocher, W. H. Meier, and D. H. Olson, Elsevier, Fifth Revised Edition, 2001, which is hereby incorporated by reference. A large pore molecular sieves generally has a pore size of at least about 7 Å and includes LTL, VFI, MAZ, MEI, FAU, EMT, OFF, *BEA, and MOR structure type molecular sieves (IUPAC Commission of Zeolite Nomenclature). Examples of large pore molecular sieves include mazzite, offretite, zeolite L, VPI-5, zeolite Y, zeolite X, omega, Beta, ZSM-3, ZSM-4, ZSM-18, ZSM-20, SAPO-37, and MCM-22. An intermediate pore size molecular sieves generally has a pore size from about 5 Å to about 7 Å and includes, for example, MFI, MEL, MTW, EUO, MTT, MFS, AEL, AFO, HEU, FER, and TON structure type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of intermediate pore size molecular sieves include ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-385, ZSM-48, ZSM-50, ZSM-57, silicalite 1, and silicalite 2. A small pore size molecular sieves has a pore size from about 3 Å to about 5.0 Å and includes, for example, CHA, ERI, KFI, LEV, SOD, and LTA structure type zeolites (IUPAC Commission of Zeolite Nomenclature). Examples of small pore molecular sieves include ZK-4, ZSM-2, SAPO-34, SAPO-35, ZK-14, SAPO-42, ZK-21, ZK-22, ZK-5, ZK-20, zeolite A, hydroxysodalite, erionite, chabazite, zeolite T, gemlinite, ALPO-17, and clinoptilolite.
When the molecular sieve produced is a crystalline metallosilicate, the chemical formula of anhydrous crystalline metallosilicate can be expressed in terms of moles as represented by the formula: M2/nO:W2O3:ZSiO2, wherein M is selected from the group consisting of hydrogen, hydrogen precursors, monovalent, divalent, and trivalent cations and mixtures thereof; n is the valence of the cation and Z is a number of at least 2, preferably at least 3, said value being dependent upon the particular type of molecular sieve, and W is a metal in the anionic framework structure of the molecular sieve such as aluminum, gallium, boron, or iron.
When the molecular sieve produced has an intermediate pore size, the molecular sieve preferably comprises a composition having the following molar relationship:
X2O3:(n)YO2,
When the molecular sieve is a gallosilicate intermediate pore size molecular sieve, the molecular sieve preferably comprises a composition having the following molar relationship:
Ga2O3:ySiO2
The molecular sieve may be employed in combination with a binder material resistant to the temperature and other conditions employed in aromatic conversion processes. Such binder materials include synthetic or naturally occurring substances as well as inorganic materials such as clay, silica, alumina, and/or metal oxides. The latter may be either naturally occurring or in the form of gelatinous precipitates or gels including mixtures of silica and metal oxides. Naturally occurring clays include those of the montmorillonite and kaolin families, which families include the sub-bentonites and the kaolins commonly known as Dixie, McNamee-Georgia and Florida clays or others in which the main mineral constituent is halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid, treatment or chemical modification.
In addition to the foregoing materials, the molecular sieve may be composited with a porous matrix material, such as active carbon, carbon fiber, alumina, silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, and silica-titania, as well as ternary compositions, such as silica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesia and silica-magnesia-zirconia. Further, the molecular sieve may be composited with crystalline microporous molecular sieve material. Examples of such materials are disclosed in PCT Publication 96/16004, which is hereby incorporated by reference.
The relative proportions of molecular sieve and binder material will vary widely with the molecular sieve content ranging from between about 1 to about 99 percent by weight, more preferably in the range of about 10 to about 70 percent by weight of molecular sieve, and still more preferably from about 20 to about 50 percent.
The catalyst can include at least one hydrogenation/dehydrogenation metal. Examples of suitable hydrogenation/dehydrogenation metals include Group VIII metals (i.e., Pt, Pd, Ir, Rh, Os, Ru, Ni, Co and Fe), Group IVA metals (i.e., Sn and Pb), Group VA metals (i.e., Sb and Bi), and Group VIIB metals (i.e., Mn, Tc and Re). Noble metals (i.e., Pt, Pd, Ir, Rh, Os and Ru) are sometimes preferred. Reference to the metal or metals is intended to encompass such metal or metals in the elemental state (i.e. zero valent) or in some other catalytically active form such as an oxide, sulfide, halide, carboxylate and the like.
The reactor of the present invention finds particular application in sulfur removal and/or the saturation of olefins in a feed containing organic compounds, e.g., hydrocarbon feed containing benzene heartcut and hydrogen. A preferred catalyst for use in this process comprises an amorphous metal oxide support material, e.g., silica, alumina, or mixtures thereof and a hydrogenation/dehydrogenation metal such as nickel, molybdenum, or mixtures thereof.
Exemplary operating conditions for sulfur removal include a temperature of from about 200° C. to about 350° C., a pressure of from about atmospheric to about 60 atmospheres and a weight hourly space velocity of from about 0.08 hr−1 to about 20 hr−1.