MXPA00000086A - Process for heat integration of an autothermal reformer and cogeneration power plant - Google Patents

Abstract

A process for integration of an autothermal reforming unit and a cogeneration power plant in which the reforming unit has two communicating fluid beds. The first fluid bed is a reformer reactor containing inorganic metal oxide and which is used to react oxygen and light hydrocarbons at conditions sufficient to produce a mixture of synthesis gas, hydrogen, carbon monoxide, and carbondioxide. The second fluid bed is a combustor-regenerator which receives spent inorganic metal oxide from the first fluid bed and which provides heat to heat the inorganic metal and balance the reaction endotherm, by combusting fuel gas in direct contact with the inorganic metal oxide producing hot flue gas. In preferred embodiments, steam is also fed to the reformer reactor and a catalyst may be used with the inorganic metal oxide. The cogeneration power plant has a gas turbine equipped with an air compressor and a combustor and in the integration a portion of compressed air is drawn off from the power plant gas turbine air compressor leaving remainder compressed air;the drawn off compressed air is introduced to the combustor-regenerator;the hot flue gas from the combustor-regenerator is mixed with the remainder of the compressed air to produce a recombined gas stream and this recombined gas stream is fed to the combustor of the cogeneration gas turbine power plant.

Description

PROCESS FOR THE INTEGRATION OF HEAT OF AN AUTOTERMIC REFORMER AND COGENERATION ENERGY PLANT The invention relates generally to a process for reforming hydrocarbons in a reformer unit, and more particularly, to an improved process for reforming methane and light hydrocarbons with an integrated autothermal reformer and a cogeneration power plant, resulting in production of synthesis gas, by-products of synthesis gas and energy with improved thermal efficiency.

The processes for reforming light hydrocarbons that produce various synthesis gases and synthesis gas products are well known in the art. The conventional processes for reforming light hydrocarbons use steam or oxygen in a reformer.

The steam reforming of light hydrocarbons, which produce hydrogen and carbon monoxide, as shown in (1), is a widely used commercial process.

CH4 + H20 CO + 3 H2 (1)? H = 49.3 KCAL / mol Ref. 032321 Due to the presence of excess vapor, a part of the carbon monoxide and vapor react simultaneously as indicated by the water-gas substitution reaction (2).

CO + H20 C02 + H2 (2) In the refining industry, steam reforming is an important component of most hydrogen production complexes. Approximately 90% of the hydrogen in a hydrogen plant is produced directly by steam reforming in a steam reformer reactor. The remaining 10% is produced via the water-gas substitution process, which requires CO produced in the reformer. Steam reforming is also an integral component in the production of methanol from natural gas (3), as well as Fisher-Tropsch processes (4) CO + 2H2 CH30H (3) CO + 2 H2 1 / n (CH2) "+ H20 (4) In response to growing environmental concerns, it is expected to increase the demand for hydrogen and methanol, leading to the need for additional reforming capacity. Therefore, improved integrated processes, which result in improved efficiency and, therefore, lower utility costs, are timely and attractive options.

Steam reforming is traditionally carried out in multi-tubular fixed-bed reactors, which are heated outside in an oven. The disadvantages of traditional steam reforming in multi-tubular fixed-bed reactors are described in U.S. Pat. No. 5,624,964.

An approach to eliminate some of the disadvantages of multi-tube fixed-bed reactors for steam reforming processes, for example, eliminating costly heat transfer surfaces, is through the use of two communicating fluidized beds, any of which could be a fixed bed of ascending flow or descending flow, a fast fluidized bed or a circulating fluidized bed. In such a design, the reforming catalyst is heated directly, via combustion of fuel gas, in one of the fluidized beds in a combustion-regenerator system, and then the hot catalyst is transported to the other fluidized bed in a reformer reactor, in which the steam reforming reaction is carried out. In this way, the heat gained in the bed, in which the combustion takes place, can be transferred directly to the reformer section that provides the required sensible heat and the endothermic heat of reaction for the reforming reaction (1) . The recirculation of the reforming catalyst to a combustion zone also regenerates the catalyst by burning any coke formed during the reforming reaction. Since continuous regeneration eliminates concerns about continuous coke buildup and, therefore, deactivation of the permanent catalyst, lower vapor to carbon ratios can be used resulting in additional utility savings.

A major obstacle to such design is the fact that steam reforming is normally carried out under pressure (150-400 psig) and, therefore, the air required for the combustion and, therefore, the heating of the catalyst, must be compressed to maintain the equilibrium of the pressure in the catalyst circulation loop. The energy cost required for this compression is very high and, to some degree, counteracts the improved heat transfer benefits in relation to traditional contactless heat transfer. A portion of the energy consumed to compress the external gases sent to the combustion-regenerator system can potentially be recovered by expanding the pressurized, hot gases that leave the combustion-regenerator system, after separation of the solids, to a turbine to produce Energy. The inability of conventional turbines operating at high temperatures (>1400 ° F) with entrained macroparticles, due to excessive erosion of the turbine blade, provides a second important process obstacle. Filtration of hot gases is an option only if the combustion gas is first cooled to a temperature, for which commercial catalyst filters are available. Cooling via some external means causes an additional reduction in thermal efficiency. At these low temperatures, very little net energy is gained in excess of the energy required for compression, which leads to a high investment cost and a loss in thermal efficiency.

These obstacles are overcome in U.S. Pat. No. 5,624,964, by integration of a steam reforming process, composed of two communicating fluidized beds, with a cogeneration power plant, where a fluidized bed process unit is integrated with a combined cycle power plant. In U.S. Pat. No. 5,624,964, the integration, in part, comprises extracting a portion of compressed air from a compressed air flow of a compressor of the gas turbine of the power plant and this "borrowed" compressed air is introduced into a compressed air. combustion-regenerative system of a steam reforming unit together with fuel gas. In U.S. Pat. No. 5,624,964, a small pressure booster compressor for "borrowed" air can be used to compensate for the pressure drop in the combustion system, and the "borrowed" compressed air and also some extra heat is then returned to the power plant mixing the compressed, hot free gases of the combustion-regenerator system with the compressed air flow of the power plant, which is transported to the combustion system of the power plant. The mixing of the hot combustion gases and the rest of the compressed air flow lowers the temperature of the free gases sufficiently to allow the elimination of the catalyst fines by filtration, without thermodynamic losses. At the same time, the temperature and pressure of the air flow for the combustion system of the power plant in the integrated process of U.S. Pat. 5,624,964 are increased to facilitate combustion.

Although the integrated process of U.S. Pat. No. 5,624,964 has many advantages, such as, for example, (a) increased efficiency by eliminating the need for a large air compressor for the combustion-regenerative system section of the steam reforming process, (b) efficient utilization Thermally from the energy of hot combustion gases by mixing with excess cold air to allow particulate filtration with no loss of thermodynamic efficiency compared to non-integrated gas turbines, (c) reducing the need to maintain the production of very low single-pass coke, since the catalyst is continuously regenerated, allowing a reduction in excess steam for the reformer, and (d) reduction in compression and combustion costs of the cycle power plant combined through the introduction of hot compressed gases from the fluidized bed regenerator, it is always desirable to increase efficiency and reduce cir the cost of plants and processes which thermally reform the hydrocarbons.

The oxygen reforming of light hydrocarbons, which produces hydrogen and carbon monoxide, as shown in the net reaction (5) is well known.

CH4 + 02 CO + H2 + H20 (5¡? H = -8.5 KCAL / mol Water in the form of steam is generated in this process and reacts with carbon monoxide as shown in (2) above, and reforming with oxygen can also be an integral component in the production of methanol as shown in (3) previously and in the Fischer-Tropsch process as shown in (4) above.

Traditionally, the autothermal reforming reaction with oxygen has been carried out by combining pure oxygen into the reactor together with methane or other hydrocarbons together with steam. Unfortunately, the use of pure oxygen requires the use of intensive cryogenic units essential for air separation. In fact, it has been estimated that 50% of the cost of an autothermal reformer is associated with the cost of air separation. Alternatively, if air is used as the source of oxygen in the traditional autothermal reforming, a nitrogen diluent is introduced into the syngas (synthesis gas). This is a significant disadvantage because the nitrogen diluents produce the products and by-products of synthesis gas, increase the size of the equipment of the plant, unfavorably produce heat yields and significantly reduce the efficiency of separation of the products and by-products of synthesis gas .

The idea of using a metal oxide to react with methane to produce syngas (synthesis gas) is described by Lewis et al. in Industrial and Engineering Chemistry, Vol. 41, No. 6, 1227-1237 (1949). In this study, Lewis et al. investigated the use of copper oxide to aid in the autothermal reforming of methane and fed the solid powder with a reservoir tube into the gas stream, which transported the powder to the reactor. An example of the overall reaction for reacting a metal oxide with methane to produce syngas (synthesis gas) is shown in (6) below: CH4 + 2M0x +? H2 + CO + 2M0X + H20 (6) where x is an integer which gives the neutral charge of the metal oxide.

Although Lewis et al. indicates that the energy is released in two stages (1) oxidation of the hydrocarbon by the metal oxide and (2) reoxidation of the metal oxide and that the metal oxide can be oxidized with air, the process and apparatus of Lewis et al. they are disadvantageous because they underutilize the process and do not make use of the economic value of heat, including compressed, hot free gas in a combustion-regenerative system.

The aforementioned disadvantages have been overcome by the integration of an autothermal reformer having two communicating fluidized beds, with a cogeneration power plant, ie, a fluidized bed autothermal reformer unit is integrated with a combined cycle power plant , where an inorganic metal oxide capable of undergoing redox cycles is used to oxidize the hydrocarbon (and syngas) in the reformer reactor. By integration of heat, singas (synthesis gas), syngas products (syngas), for example, Fischer-Tropsch products, methanol, and other oxygenates, energy, and steam, can be produced with an efficiency improved compared to the non-integrated processes or the integrated steam reforming process described above. An inorganic metal oxide capable of undergoing redox cycles is used in the process of the present invention. In the singas reactor (synthesis gas), ie the autothermal reforming reactor, the inorganic metal oxide is subjected to a reduction, whereby the hydrocarbon and syngas (synthesis gas) are oxidized. Then the reduced inorganic oxide is converted back to its oxidized form with air in the combustion-regenerative system. This avoids the need for an air separation plant, resulting in lower capital costs.

The autothermal reformer, or autothermal reformer unit, as defined and used agui, has two communicating fluidized beds, such that the inorganic metal oxide (an "oxygen" redox carrier) exits the first fluidized bed in an autothermal reformer reactor in a reduced state of oxidation, at a temperature of T and, following the separation of the reformer's gas products, enters a second fluidized bed in a combustion-regenerator system operating at a temperature of T2, such that T2 is greater that you. The autothermal reformer of the present invention does not require external sources of heat during the operation; however, as an option, the heat can be derived from external sources, such as, for example, steam, heated hydrocarbon feed gas streams, and the like. In the combustion-regenerator system, the coke burns out of the inorganic metal oxide and the redox inorganic metal oxide material (reduction-oxidation) is converted to a higher oxidation state. According to the present invention, the redox material leaving the combustion-regenerator system at temperature T2 re-enters the autothermal reformer reactor, where the heat accumulated in the combustion-regenerator system is used to heat the feed in the reformer and to supply heat to the syngas reaction (synthesis gas).

As described in U.S. Pat. No. 5,624,964, the integration, in part, comprises extracting a portion of compressed air from a flow of compressed air from a compressor of the gas turbine of the power plant. This "borrowed" compressed air is introduced into the combustion section, that is, the combustion-regenerator system, of the autothermal reforming reactor together with fuel gas. A small pressure booster compressor for "borrowed" air is optionally used to compensate for pressure drop in the booster-regenerator system. The "borrowed" compressed air and also some extra heat is then returned to the power plant by mixing the compressed, hot free gases from the combustion-regenerator system with the compressed air flow from the power plant, which is transported to the combustion system of the power plant. The mixing of the hot combustion gases and the rest of the compressed air flow lowers the temperature of the free gases sufficiently to allow the elimination of inorganic metal oxide fines by filtration, without thermodynamic losses. At the same time, the temperature and pressure of the air flow for the combustion system of the power plant are increased to facilitate combustion.

Generally, in accordance with the present invention, there is provided a process for the heat integration of an autotherm reformer and a cogeneration power plant, in which the cogeneration power plant has a gas turbine equipped with an air compressor. and a combustion system. The autothermal reformer has two communicating fluidized beds; a first fluidized bed comprises a reforming reactor containing inorganic metal oxide capable of undergoing reduction-oxidation reaction cycles and which is used to oxidize the hydrocarbons at conditions sufficient to produce a mixture comprising synthesis gas hydrogen, carbon monoxide , or carbon dioxide or mixtures thereof, a second fluidized bed comprises a combustion-regenerator system which receives the inorganic metal oxide exhausted from the first fluidized bed and which provides heat to heat the inorganic metal oxide by burning combustible gas in contact Direct with the inorganic metal oxide, it also produces hot combustion gas. In addition to burning the coke out of the inorganic metal oxide and heating the inorganic metal oxide, the reoxidation of the inorganic metal oxide also releases heat by an exothermic reaction. A portion of compressed air is extracted from a stream of compressed air from the air compressor of the air compressor of the gas turbine of the power plant; the extracted compressed air is introduced to the combustion-regenerator system; The hot combustion gas from the combustion-regenerator system is mixed with the remainder of the compressed air stream of the power plant to produce a stream of recombined gas and this stream of recombined gas is fed into the combustion system of the plant of cogeneration energy with gas turbine. The inorganic metal oxide is circulated between the first fluidized bed and the second fluidized bed, wherein the inorganic metal oxide oxidizes the hydrocarbon and syngas (synthesis gas) and the reduced inorganic metal oxide in the first fluidized bed in the reforming reactor is regenerates, reoxidates, and heats in the second fluidized bed in the combustion-regenerator system and the inorganic, regenerated, reoxidized, and heated metal oxide is returned to the first fluidized bed. The circulation of the inorganic metal oxide is preferably continuous; however, in certain aspects of the present invention, the circulation of the inorganic metal oxide may be intermittent.

In certain aspects, the process of the present invention further comprises a reforming reactor containing catalyst, and the catalyst and the inorganic metal oxide are circulated together, wherein the catalyst is depleted and the inorganic metal oxide is reduced in the first fluidized bed and the spent catalyst is regenerated and the reduced inorganic metal oxide is oxidized in the second fluidized bed. In certain different aspects of the present invention, the process also includes feeding steam to the reformer reactor, that is, the process is an autothermal reaction assisted with steam, wherein the steam is added to the autothermal reformer reactor.

In addition to the advantages listed above, the process of the present invention generally has the advantages of the integrated steam reformer unit of the prior art and cogeneration power plant of U.S. Pat. Do not. ,624,964. In addition, since the autothermal process of the present invention does not indirectly make source oxygen from air, it does not introduce any nitrogen diluent to the syngas product (synthesis gas) as it should be the case if the air is added directly to the reactor reformer. This is a significant advantage in the downstream processing of syngas (synthesis gas), where the nitrogen diluent influences equipment size, heat yields, and separation efficiency.

An advantage of the process of the present invention compared to an integrated steam reformer is that the overall inorganic metal oxide circulation ratios can be dramatically reduced at a constant temperature T2. This is due to the lower heat balance requirements of the circulating material, which are diminished since the autothermal reforming is not as demanding energy as the steam reforming. At constant flow rates, the operating temperature of the combustion-regenerator system (T2) could be reduced resulting in additional savings in thermal efficiency. It is this aspect of the process of the present invention which, in certain examples, allows efficient operation of the autothermal reformer unit, even with intermittent circulation or cycling of the inorganic metal oxide from the reformer reactor to the combustion-regenerator system.

An additional advantage of the process of one aspect of the present invention, which is assisted with steam, is the ability to adjust the molar proportions of H2 / (2CO + 3C02) and C02 / CO by varying the amount of inorganic metal oxide and vapor that feeds the autothermic reformer. Preferably the molar ratio of H2 / (2CO + 3C02) is about 1, and the molar ratio of C02 / C0 is as low as possible, preferably lower than about 0.5. This flexibility in a single reactor is unique and is a considerable advantage when integrating the syngas process (synthesis gas) with downstream operations to produce methanol or Fischer-Tropsch products.

Additional features and advantages of the invention will be mentioned in the description which follows, and in part will be apparent from the description, or may be studied by practice of the invention. The objectives and other advantages of the invention will be realized and achieved by the process, apparatus and system particularly indicated in the written description and claims thereof, as well as the attached drawing.

It will be understood that both the general description mentioned above and the following detailed description are exemplary and explanatory and are intended to provide a further explanation of the invention as claimed.

The accompanying drawing which is included provides further understanding of the invention and is incorporated in and constitutes a part of this specification, illustrates one embodiment of the invention and together with the description serves to explain the principles of the invention.

The drawing is a schematic diagram of the invention.

In the process of this invention, an autothermal reformer unit and a cogeneration power plant with gas turbine are integrated. The autothermal reformer has two communicating fluidized beds, such that the inorganic metal oxide for reforming continuously or intermittently leaves the first fluidized bed, the reforming reactor, at a temperature of T and, following the separation of the reformer's gas products, enters in a second fluidized bed, the combustion-regenerator system, at T2, such that T2 > TX.

The autothermal reformer unit reforms hydrocarbons with inorganic metal oxides, which are capable of undergoing oxidation-reduction cycles to oxidize the hydrocarbons supplied to the reformer reactor and a portion of the syngas (synthesis gas) which is formed in the reformer reactor. The hydrocarbons reformed by the process of the present invention are generally referred to as light hydrocarbons or light paraffins and include, but are not limited to, for example, methane, ethane, liquid petroleum gas (LPG), naphthas, typically virgin naphtha or piezo-pyrolyzed naphthas, such as, for example, light naphthas, naphtha throughout the range or even heavy naphtha, refinery-free gas, associated gas, and the like. An advantage of the process of the present invention in those modalities, where the inorganic metal oxide is continuously regenerated, it is that the heavier feeds, ie the naphthas and the like, can easily be oxidized, that is, reformed, in the reformer reactor, thereby eliminating the need of feeding steam to the reformer reactor or reducing the amount of steam fed to the reformer reactor. The product streams resulting from the autothermic process of the present invention generally consist of hydrogen, carbon monoxide, carbon dioxide, steam, for example, steam from the reaction water when no excess steam is fed to the reformer reactor, or steam from the reactor. steam added in the steam-assisted modalities, and unreacted hydrocarbon.

In certain preferred aspects of the present invention, the inorganic metal oxide, which must be capable of undergoing reduction-oxidation cycles according to the present invention, ie, cycles wherein the metal oxide is first reduced and subsequently oxidized or vice versa, it is used without the help of other additives. In many preferred embodiments of the present invention, the inorganic metal oxide is used with a conventional support material as is well known in the art.

Preferred inorganic metal oxides used in the present invention may be binary or ternary oxides or mixtures thereof. The binary metal oxides include, but are not limited to, for example, chromium oxide, cobalt oxide, niguel oxide, titania, copper oxide, manganese oxide, iron oxide, or mixtures thereof, and the like . The ternary metal oxides include, but are not limited to, for example, praseodymium-cesium oxide, SrCO0.5FeOx, or mixtures thereof, and the like, where x is an integer which gives the neutral charge of the metal oxide. Mixtures of the binary and ternary metal oxides can also be used in the process of the present invention. The support materials include, but are not limited to, for example, alpha-alumina, kaolin, zirconia, magnesium oxide, cerium (IV) oxide, silica or mixtures thereof, and the like.

The form or forms of oxygen, that is, the oxidant (s), which are generated by the inorganic metal oxide that reacts with the hydrocarbons and syngas (synthesis gas), that is, that oxidizes hydrocarbons and syngas (gas from synthesis), in the autothermal reformer reactor are not definitely known. However, as a result of the reaction (oxidation), the inorganic metal oxide is reduced by oxidizing the hydrocarbon and syngas (synthesis gas), and the reduced form of the inorganic metal oxide, defined herein as spent inorganic metal oxide, is circulated to the combustion-regenerator system for reoxidation.

The proportions of inorganic metal oxide to hydrocarbon are not critical in the process of the present invention, since there is a sufficient amount of the inorganic metal oxide to react with (oxidize) the hydrocarbon, that is, to react with the hydrocarbon to produce syngas (synthesis gas), by-products of syngas (syngas) and the like as described above. However, in certain embodiments, the ratio of inorganic metal oxide to hydrocarbon in the autothermal reforming reactor is 5 to 280 percent by weight (% by weight), preferably 10 to 140% by weight, and most preferably, 15 to 40% by weight. 100% by weight. These weights are calculated based on the inorganic metal oxide circulation ratios (tons per minute) and the hydrocarbon feed rate (tons per minute).

The process of the present invention can be operated without an additional steam feed. However, the steam reforming activity always occurs in the process of the present invention because even without the additional steam feed, the steam is generated in the autothermal reactor from the reaction water resulting from the oxidation of the hydrocarbon. However, in certain preferred embodiments, it is desirable to supply additional steam to the reformer to provide an enhanced or "additional" steam reforming activity present with the oxidation reforming activity. (from the inorganic metal oxide) in the process of the present invention. In accordance with the process of the present invention, this additional steam reforming activity is defined as a steam assisted process.

The inorganic metal oxide may or may not be active to catalyze the reforming reactions with steam and C02. Yes an inorganic metal oxide used in the process of the present invention is not active for the steam reforming reaction, a second catalytic component can be added, for example, a nickel catalyst, which is active in that function. This second component can be placed in the same carrier particle as the inorganic metal oxide or in a separate carrier particle. Other conventional catalyst materials can also be used with the inorganic metal oxides in the present invention, including, but not limited to, for example, palladium, platinum, ruthenium, iridium, rhodium, cobalt, or mixtures thereof. Various metal combinations also known in the art can also be used as catalyst materials with the inorganic metal oxides, including, but not limited to, for example, nickel / cobalt, nickel / platinum, and the like. Thus, if the inorganic metal oxide does not provide catalytic activity for the steam reforming or C02 reforming reactions, or if there is insufficient catalytic activity by the inorganic metal oxide for these reactions, the conventional steam reforming catalysts can be used to complement the catalytic activity, if any, provided by the inorganic metal oxide.

The particle sizes of the inorganic metal oxide and / or catalyst, including the inorganic metal oxide and catalyst, in the same support material, used in the autothermal reformer unit, with or without a support material is not critical, since the particles can be circulated from the reformer reactor to the combustion-regenerator system and since the particles can be fluidized in the respective beds. For use in the fluidized beds of the present invention, the particle sizes are generally in the range of 10 to 150 microns, preferably with a greater part of particles of 40 to 120 microns. The inorganic metal oxide particles and / or catalyst, including any of the support materials, are preferably resistant to friction.

The circulation of the inorganic metal oxide particles or the inorganic metal oxide particles and catalyst particles from the reformer reactor to the combustion-regenerator system and / or from the combustion-regenerator system to the reformer reactor in its reduced forms ( spent) or oxidized (regenerated) respectively, can be continuous or intermittent. Generally, continuous circulation is preferred; however, the intermittent circulation of the particles can be used where a sufficient amount of oxygen or an oxygen form can be maintained in the reforming reactor to react with the hydrocarbon without jeopardizing the continuous production of syngas (synthesis gas).

Since one purpose of the circulating fluidized beds in the process of the present invention is to facilitate heat transfer, a rule of the combustion-regenerator system is to heat the inorganic metal oxide particles to a temperature above the temperature of the particles in the reforming reactor, thereby a portion of the heat of reaction is supplied. Therefore, in one embodiment of the present invention, the separated heat transfer particles, the sole purpose of which is heat transfer, can be added to the fluidized beds. The particle sizes of such heat transfer particles should be similar to those described above for the inorganic metal oxide and the catalyst Examples of such heat transfer particles include, but are not limited to, for example, alpha- alumina, kaolin, cerium oxide (Ce203), La203, Zr02, and the like.

Referring to the drawing, the heat transfer particles are heated in the combustion-regenerator system 5 and passed through the conduit 6 to the reformer reactor 2, where the heat in the heat transfer particles is transferred to the bed fluidized in the reformer reactor to provide the complementary heat for the hydrocarbon reforming reaction. In this way, the heat is exhausted from the heat transfer particle and the transfer particle depleted in heat is returned through line 4 to the combustion-regenerator system 5 where it is reheated.

The types of fluidized bed processes contemplated for use herein include fast fluidized beds, fixed fluidized beds and circulating fluidized beds. All of these applications can be used in either upflow or downflow modes. A fixed fluidized bed is a fluidized bed in which the velocity of the gas is greater than that required for minimum fluidization, but lower than that necessary to achieve pneumatic transport. The surface of the bed, although it could be highly irregular, is clearly well defined. Examples of the fixed fluidized beds include bubbling and turbulent fluidized beds. A circulating fluidized bed is a fluidized bed process whereby the inorganic metal oxide is continuously removed from the bed (if in upflow or downflow orientation) and then re-introduced into the bed to fill the supply of solids . At high speeds (eg,> 50 feet / second), the density of the solid in the reactors is low, ie, less than 2 pounds / ft 3, and, in upflow, one calls this type of fluidized bed a chimney reactor. At lower speeds, while the inorganic metal oxide still creeps into the gas stream, a relatively dense bed is formed in the reactor. This type of bed is often called a fast fluidized bed. There is no clear dividing line between these types of reactors and, for the purposes of the invention, it is sufficient that we treat with inorganic metal oxide particles (or inorganic metal oxide and catalyst), in such a way that they can be easily flowed between the combustion-regenerator system and the reaction zones.

In the invention, the inorganic metal oxide leaving the combustion-regenerator system at temperature T2 enters the autothermal reforming reactor, once again, where the heat accumulated in the combustion-regenerator system is used to provide heat to the reaction of reformed. Since the reforming reaction is generally operated at high pressures, the combustion-regenerator system requires a supply of combustion air at a pressure equal to the operating pressure of the reformer plus any additional pressure that is necessary to overcome the Pressure drop in the communicating bed loop. The compressed air for the combustion-regenerator system is provided by the integration with a cogeneration power plant with gas turbine.

At the cogeneration power plant, energy is generated by burning fuel gas at moderate pressures (eg, 200-400 psig) to produce pressurized, hot gases, which then expand and cool to produce energy and steam, respectively. An amount of air in excess of that stoichiometrically required (150-200%) for combustion of fuel in the combustion system of the power plant, is initially compressed up to the inlet pressure of the desired gas turbine (for example, 200-400 psig). This large excess of air is necessary to serve as a heat sink in the combustion system of the power plant to moderate the combustion exotherm and maintain the temperature of the combustion system within the limitations set by the associated physical components. Since the compressed air is available in excess, a portion of the compressed air leaving the compressor of the gas turbine of the cogeneration power plant is borrowed for use in the combustion-regenerator system. The diluent air, previously used to control the temperature in the combustion system of the power plant, is replaced by the pressurized, hot free gases of the combustion-regenerator system, which are fed back to the combined cycle power plant and they are mixed with the remaining air flow as gas flow for the combustion system of the power plant. Such integration reduces operating and capital costs otherwise associated with a fluidized bed autothermal reforming process.

The solids entrained in the hot free gases of the combustion-regenerator system can damage the blades of the gas turbine of the power plant as a result of erosion. Therefore, the hot free gases of the combustion-regenerator system are filtered to remove entrained particulates. The temperature tolerance of commercially available filters for this purpose is limited to, for example, 1450 ° F, and the temperature of the hot free gas leaving the combustion-regenerator system is generally satisfactory above this limit. The hot free gases can be sufficiently cooled by mixing with the remainder of the compressor air flow from the gas turbine of the colder power plant. The mixture of hot combustion gas and the air flow of the colder compressed energy plant is brought into equilibrium to an acceptable temperature, such that the stream of mixed gas can be passed through a filter and then sent to the combustion-regenerator system.

Using the integrated autothermal fluidized bed reformer has additional advantages over conventionally used multitubular reactors which use steam. Reforming with ordinary steam requires a large amount of excess steam, which is necessary to limit the formation of coke to prolong cycle life in fixed bed steam reforming operations. In the fluidized bed, the need to maintain low single-pass coke production is reduced, since the inorganic metal oxide is regenerated (and re-oxidized), preferably continuously, in the combustion-regenerator system.

The contemplated autothermal reforming processes used herein are those which require a pressure greater than 20 psig. The preferred pressure range is from 20 psig to 1000 psig; preferably 150 psig up to 600 psig; and more preferably 150 psig up to 450 psig. The preferred temperature range of the autothermal reformer reactor is from 1350 ° F to 2000 ° F, more preferably 1600 ° F to '1850 ° F.

The feed for reforming is generally a light paraffin, preferably methane or ethane; however, other conventional hydrocarbons which can be reformed in a reformer reactor, such as the hydrocarbons discussed above, can be fed to the reformer reactor in one or more feed streams. The product stream consists of hydrogen, carbon monoxide and carbon dioxide, as well as steam and unreacted hydrocarbon.

The integration of a power plant unit with an autothermal reforming process unit is exemplified in the drawing.

In a preferred embodiment of the process of the present invention, the inorganic metal oxide is copper oxide in an alumina support. In another preferred embodiment of the present invention, the steam is injected into the reformer reactor to provide steam assisted reforming of the hydrocarbon, for example, methane, while the copper oxide particles in an alumina support and nickel catalyst in the same alumina support they are fluidized in the reformer reactor. The amount of catalyst generally provided when the combinations of inorganic metal oxide and catalyst are used in the process of the present invention is not critical, since there is sufficient reforming of the hydrocarbon to produce syngas (synthesis gas.) In certain embodiments, the proportion of inorganic metal oxide to catalyst is 50:50, preferably 60 parts by weight of inorganic metal oxide up to 40 parts by weight of catalyst and more preferably, 75 parts by weight of inorganic metal oxide up to 25 parts by weight of catalyst.

Referring to the manufacturing diagram in the drawing, section A shows an autothermal reforming process unit. A gaseous feed stream, pressurized for the autothermal reforming, containing methane, and optionally steam in the steam assisted autothermal reforming modes at a vapor / carbon (V / C) ratio, for example, 0: 1 to 4: 1, preferably 0: 1 to 1.5: 1 and more preferably 0: 1 to 1: 1, is introduced via line 1 into the reformer reactor 2, which in this example is a fixed fluidized bed. The feed inlet temperature may vary between 300 ° F and 1400 ° F, preferably 500 ° F to 1000 ° F, and more preferably 600 ° F to 800 ° F. The reformer reactor 2 contains a solid, fluidized particulate inorganic metal oxide bed. (not shown), which is at a sufficient temperature to produce the autothermal reforming, in this example, 1650 ° F. This temperature can be in the range of 1350 ° F to 2000 ° F, preferably 1600 ° F to 1850 ° F. The pressurized feed stream is introduced into the reformer reactor 2 at a pressure of 300 psig. The reformed fluidized beds can operate at a pressure of 20 psig up to 1000 psig and preferably 150 psig up to 450 psig.

The inorganic metal oxide particles of manufacture and the catalyst particles of manufacture or both can be added to the autothermal reformer unit as required by conventional techniques by feeding these into the existing feed lines, whether heated or unheated, with hydrocarbon gas, steam, air, and the like, for example, on line 1, or feeding the particles driven by the hydrocarbon gas, air or steam in a separate feed line (not shown) to one or more components or ducts in the autothermal reformer unit. The manufacturing particles can be added "continuously, if required, or intermittently, as required, for example, since the inorganic metal oxide particles and / or catalyst become depleted. feeding to any part of the reforming unit, for example, in a feeding line ' (not shown) to the first fluidized bed in the reformer reactor 2, in a feed line (not shown) to the second fluidized bed in the combustion-regenerator system 5, in a feed line (not shown) to a transfer line (duct 4) used to circulate the spent inorganic metal oxide from the first fluidized bed to the second fluidized bed, or in a feed line (not shown) to a transfer line (duct 6) used to circulate the metal oxide inorganic regenerated from the second fluidized bed to the first fluidized bed. For the fabricated inorganic metal oxide fed to the reforming unit, the inorganic metal oxide may be in a reduced state or in an oxidized state and may be fed to the autothermal reformer unit at room temperature or may be heated.

An effluent of gaseous product containing H2, CO, C02, H20, and CH4, leaves the reformer reactor 2 through line 3 at a temperature of from 1350 ° F to 2000 ° F, most preferably 1600 ° F to 1850 ° F and a pressure of 20 psig up to 1000 psig, preferably 150 psig up to 600 psig, and more preferably 150 psig up to 450 psig.

The spent inorganic metal oxide (and spent catalyst when present) from the reformer reactor 2 is passed through line 4 to the combustion-regenerator system 5 for reheating. The combustion-regenerator system generally operates at a higher temperature than the reformer reactor with a heat differential provided by combustion in the combustion-regenerator system of light hydrocarbons, such as fuel gas, and coke which may have been deposited in the inorganic metal oxide (and in the catalyst when it is present) and by the reoxidation of the inorganic metal oxide during the step of autothermal reforming. In this example, the methane is chosen as the fuel for the combustion-regenerator system and the copper oxide is chosen as the inorganic metal oxide. The temperature differential of the combustion-regenerator system on the reformer reactor in this example is 150 ° F, but may preferably be 20 ° F to 1000 ° F,; more preferably 50 ° F to 400 ° F; and more preferably 150 ° F to 200 ° F. The temperature is related to the restrictions of the team. For a given heat requirement in the reformer reactor, the ratio of temperature and circulation are related according to the formula: Q = μCp? T Q = heat transferred to the reforming reactor (Btu / minute) μ = solid flow rate (Btu / minute) Cp = heat capacity (Btu / lbm- ° F) T = temperature difference (° F) In the combustion-regenerator system 5, a fuel stream comprising fuel mixed with air, in this example containing methane, and 20% stoichiometric excess air, and at 300 psig or in the range of 100 to 1000 psig and to a temperature of 260 ° F or in a range of 200 ° F to 900 ° F, it is introduced into the combustion-regenerator system through lines 7 and 16 and the fuel and coke are burned in the combustion-regenerator system to generate heat. The metal oxide (and catalyst when present) is heated in the combustion-regenerator system to a temperature of 1800 ° F or in a range of 1500 ° F to 2200 ° F. The regenerated inorganic metal oxide (and regenerated catalyst as it occurs) passes out of the combustion-regenerator system 5 through the conduit 6 and is transported back to the reformer reactor 2 driven by a pressure difference between the reformer reactor and the reformer system. combustion-regenerator, Combustion-regenerative psyche > Preactor reformer /? P ~ 3 - 100 psl.

An effluent of gaseous product which leaves the reformer reactor 2 through line 3 is passed to other downstream components, such as a substitution reactor. (optional), steam generator 44, and recovery boiler or feed preheater 45, followed by passage through a rotary pressure absorber (PSA) 47 (optional) to separate the hydrogen product. These other downstream components are further discussed below.

In section C of the drawing, the steam reforming process is integrated with a cogeneration power plant with gas turbine. A cogeneration power plant unit is shown in the drawing in section B.

Referring again to the drawing, in the power plant unit in section B, air is conveyed through line 10 into the compressor of the gas turbine 11. The flow of compressed air at a pressure of 150 psig already 252 ° F leaves the main compressor through line 12. As shown in the drawing, section C, a portion of the compressed air flow in line 12 is diverted at junction 13 to line 14 for the purpose of " borrow "air and pressure for integration into the autothermal reforming process unit. The extracted portion of air may have a pressure of 50 to 1000 psig, preferably 150 to 400 psig and a temperature of 300 ° F to 900 ° F, preferably 400 ° F to 700 ° F. The compressed air diverted in line 14 is transported to a pressure riser compressor 15, which is optional, and the compressed air pressure biased in this case is increased to 300 psig and a temperature of 307 ° F before it leaves the compressed air. Optional pressure booster compressor through line 16. The air in line 16 is introduced into the gaseous fuel stream 7 for the combustion-regenerator system 5. In this way, the air and pressure for the process unit of Reformed autothermal are obtained from the power plant. Therefore, a separate main compressor is not necessary for the autothermal reforming process unit. Optionally, a small booster compressor can be used.

Meanwhile, the rest of the compressed air in line 12 after junction 13 is transported through line 17 to intersection 18 where the hot combustion gas in line 19 to 1800 ° F or in a range of 1500 ° F up to 2200 ° F, preferably 1650 ° F up to 1850 ° F, and 300 psig or in a range of 150 up to 450 psig, in this example containing C02, H20, 02, N2 and also containing inorganic metal oxide fines ( and catalyst when presented) of the combustion-regenerative system 5 is mixed with the compressed air in line 17 to form a stream of recombined, mixed gas 20. The hot combustion gas in line 19 of the combustion-regenerator system 5 it contains fine particles, which can result from the friction of the inorganic metal oxide of the fluidized bed (and catalyst and / or heat transfer particles when they occur). Friction usually results from degradation and mechanical breakdown of the particle in a fluidized bed. The compressed air in line 17, in this case before mixing is at a temperature of 252 ° F and 150 psig. Mixing which occurs at intersection 18 adjusts the temperature of the recombined gas stream, mixed resulting to 1200 ° F, or in the range of 700 ° F to 1600 ° F, preferably 1000 ° F to 1400 ° F. In this way, the mixture of hot combustion gas from the combustion-regenerator system and the compressed air of the power plant has a sufficiently low temperature to allow passage through conventionally available filters to eliminate circulating solids, i.e. , for example, inorganic metal oxide fines, catalyst fines when the catalyst is presented, and heat transfer fines when the heat transfer particles are presented. Conventionally available filters are generally limited to temperatures below 1400 ° F. In the absence of additional heating or cooling of 17 and 19, adjustment of a maximum mix temperature dictates the relative sizes of the power plant (i.e., energy generated) and the autothermal reformer (i.e., hydrogen produced).

After mixing the gas streams at intersection 18, the mixed gas stream is transported through the filter 21 via line 20. The mixed gas stream leaves the filter with removed inorganic metal oxide fines and the mixed stream at a pressure of 150 psig and a temperature of 1190 ° F is transported through line 22 to the combustion system of the power plant 23. Before the mixed gas enters the combustion system, fuel for combustion, for example , methane, at 250 ° F and 150 psig is introduced through line 22a on line 22 to intermix with the mixed gas stream. The combustion fuel and gas stream intermixed in line 22b at a temperature of 1168 ° F and a pressure of 150 psig and containing, for example, CH4, C02, 02, N2, H20 and preferably containing, for example, 150-200% excess air is burned in combustion system 23 at a temperature of 2000 ° F or in the range of 1700 ° F to 2800 ° F, preferably 2000 ° F to 2300 ° F, producing combustion gas containing, for example, C02, 02, N2 and H20 at 2000 ° F and 150 psig, which is transported via line 24 from the combustion system to the turbine 25. The inlet temperature of the gas turbine can be in the range of 1700 ° F to 2800 ° F, preferably 2000 ° F to 2400 ° F. The pressure reduction drives the impeller of the turbine. The pressure energy is converted to speed energy and used to generate energy, which exits through line 26. Part of the energy is diverted through line 27 to drive the compressor of gas turbine 11. The rest of the energy from line 27 at 27a is used elsewhere, for example, to supplement a refinery.

The hot gas leaving the turbine 25 through line 28, in this case, C02, 02, N2 and H20, at 1350 ° F and 10 psig, is used to produce steam in a steam generator 29. The gases leaving the steam generator 29 (for example, C02, 02, N2 and H20 at 500 ° F and 10 psig) are transported through line 30 to the recovery boiler 31. The gases leaving the recovery boiler in line 32 is transported to an extractor drum, which separates, for example, water on line 35 and C02, 02 and N2 on line 34, which are transported to a chimney.

In an optional embodiment, in the autothermal reforming process unit in section A, after the gaseous product effluent leaves the reformer reactor 2 through line 3, the effluent is optionally circulated to a substitution reactor. The water can be introduced in line 3 to produce steam and in this way cool the effluent to an acceptable level for filtration. The effluent is cooled to 700 ° F for the high temperature gas replacement reaction. The effluent from the reformer reactor can also be cooled by passing it through the steam generator 41 to produce steam energy and the temperature of the effluent in the line 41a is reduced to 700 ° F. The positions of the steam generator 41 and the filter 40 are reversed if an initial pre-filter cooling mechanism is not employed.

The replacement of high temperature gas in the substitution reactor 42 is carried out adiabatically at an inlet temperature of 700 ° F and 300 psig. Approximately 75% of the carbon monoxide becomes the substitution reactor, as dictated by the equilibrium limitations, such that the effluent of the substitution reactor 43 contains, for example, H2, methane, CO 2, CO, and H20 to 812 ° F and 300 psig. The effluent from the substitution reactor in line 43 can be used to produce steam in the steam generator 44, due to which the reactor effluent is cooled. substitution up to 500 ° F on line 44a. The effluent from line 44a is further cooled to 100 ° F in the recovery kettle 45 and the water is removed in the extractor drum 46 before the pressure treatment in the rotary pressure absorber (PSA) 47 for hydrogen purification. The hydrogen product is collected through line 48.

In a preferred embodiment, the substitution reactor is removed and the byproducts of CO, C02 and methane from the PSA complex containing, for example, methane, are fed directly into the combustion-regenerator system to serve as additional fuel (not shown) . In another embodiment, the substitution reactor remains in the design of the hydrogen plant and, similarly to the preferred embodiment, PSA byproducts, for example, CO, C02 and methane from PSA 47 at 100 ° F are sent to the system. of combustion-regenerator following the compression, to the combustion-regenerative system following the compression, to the compression-regeneration system that operates under pressure (not shown). In both cases, if the autothermal reformer process unit is operated in the steam assisted mode, it facilitates the reduction of the proportion of steam to the reformer, and therefore reduces utility costs, the steam can be added to the reformer's effluent. 3 before entering the replacement reactor 42. In this way, the steam can serve the dual purpose of cooling the reactor effluent and supplementing any steam from the autothermal reforming reactor that is in the reformer effluent to maximize the conversion to the reactor. substitution, also reduce utility costs.

In this integrated heat design shown in the drawing, hydrogen selectivity is not as important as in a conventional hydrogen plant, since hydrogen is a co-product with energy from the combined cycle power plant, steam generators and the recovery kettles.

It is the improvement of the overall efficiency and savings of the invention of capital associated with the production of energy, steam and hydrogen that determines the overall originality of this plant when inorganic metal oxide is used to oxidize the hydrocarbon and syngas (synthesis gas in the reformer reactor.

Another embodiment includes a subsequent integration with a methanol plant (not shown). The synthesis gas of the reformer is transported to the methanol unit and reacted to produce methanol. The reaction for the production of methanol requires synthesis gas as the feed. The reaction generally uses a zinc-chromium oxide catalyst, at a temperature of 300 ° F to 700 ° F, a pressure of 500 to 5000 psig. A portion of the energy required in the syngas conversion plant (synthesis gas), for example, a methanol plant or a Fischer-Tropsch plant, can be supplied from the energy generated in the cogeneration power plant with gas turbine.

While it has been described what current preferred embodiments are believed to be, those skilled in the art will make changes and modifications thereto without departing from the spirit of the invention, and intend to claim all the changes and modifications that are made therein. fall within the real scope of the invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (15)

1. A process for the heat integration of an autstermal reformer and a cogeneration power plant, where: the cogeneration power plant comprises a gas turbine equipped with an air compressor and a combustion system; the autothermal reformer comprises "two communicating fluidized beds, a first fluidized bed comprising a reforming reactor containing inorganic metal oxide capable of undergoing oxidation-reduction reaction cycles and which is used to oxidize hydrocarbons at conditions sufficient to produce a mixture comprising synthesis gas hydrogen, carbon monoxide, or carbon dioxide or mixtures thereof, a second fluidized bed comprises a combustion-regenerator system, which receives the inorganic metal oxide exhausted from the first fluidized bed and which provides heat for heating the inorganic metal oxide by burning combustible gas in direct contact with the inorganic metal oxide, it also produces hot combustion gas; and wherein a portion of compressed air is drawn from a stream of compressed air from the air compressor of the air compressor of the gas turbine of the power plant; the extracted compressed air is introduced to the combustion-regenerator system; the hot combustion gas from the combustion-regenerator system is mixed with the rest of the compressed air stream from the power plant to produce a stream of recombined gas and this stream of recombined gas is fed to the combustion system of the power plant. cogeneration energy with gas turbine, - the process characterized in that the inorganic metal oxide circulates between the first fluidized bed and the second fluidized bed, wherein the inorganic metal oxide oxidizes the hydrocarbons and forms reduced inorganic metal oxide in the first bed fluidized in the reformer reactor and the inorganic metal oxide is regenerated, re-oxidized and heated in the second fluidized bed in the combustion-regenerator system and the regenerated, oxidized inorganic metal oxide and heated is returned to the first fluidized bed.

2. The process according to claim 1, characterized in that it also comprises feeding inorganic metal oxide of manufacture to the reforming unit.

3. The process according to claim 2, characterized in that the inorganic metal oxide is fed to the first fluidized bed in the reforming reactor.

4. The process according to claim 2, characterized in that the inorganic metal oxide is fed to the second fluidized bed in the combustion-regenerator system.

5. The process according to claim 2, characterized in that the inorganic metal oxide is fed to a transfer line used to circulate the spent inorganic metal oxide from the first fluidized bed to the second fluidized bed or to a transfer line used for circulating the inorganic metal oxide regenerated from the second fluidized bed to the first fluidized bed.

6. The process according to claim 2, characterized in that the inorganic metal oxide fed to the reforming unit is an inorganic metal oxide in a reduced or oxidized state.

7. The process according to claim 1, characterized in that the inorganic metal oxide is a binary or ternary metal oxide.

8. The process according to claim 7, characterized in that the binary metal oxide comprises chromium oxide, cobalt oxide, nickel oxide, titania, copper oxide, manganese oxide, iron oxide, or mixtures thereof.

9. The process according to claim 7, characterized in that the ternary metal oxide comprises praseodymium-cesium oxide, SrCO0.5FeOx, or mixtures thereof.

10. The process according to claim 8 or 9, characterized in that the metal oxide also comprises a support material.

11. The process according to claim 10, characterized in that the support material is alpha-alumina, kaolin, zirconia, magnesium oxide, cerium (IV) oxide, silica or mixtures thereof.

12. The process according to claim 1, characterized in that it also comprises a reforming reactor containing catalyst and the process comprises circulating catalyst and inorganic metal oxide, wherein the catalyst is exhausted in the first fluidized bed and regenerated in the second fluidized bed .

13. The process according to claim 12, characterized in that the catalyst is nickel, palladium, platinum, ruthenium, iridium, rhodium, cobalt, nickel-cobalt, nickel-platinum, or mixtures thereof.

14. The process according to claim 1, characterized in that it comprises a reformer reactor and a combustion-regenerator system containing heat transfer particles and the process comprises circulating heat transfer particles, which are heated in the combustion system. regenerator for the reformer reactor, where the heat is transferred from the particles to the fluidized bed and the heat transfer particles exhausted in heat are returned to the combustion-regenerator system for reheating.

15. The process according to claim 1, characterized in that the integrated autothermal reformer and co-regeneration power plant are further integrated with a synthesis gas conversion plant, so that the synthesis gas produced in the reformer is reacted and a The amount of energy required in the synthesis gas conversion plant is supplied from the energy generated in the gas turbine cogeneration power plant. SUMMARY OF THE INVENTION The invention relates to a process for the integration of an autothermal reforming unit and a cogeneration power plant, in which the reforming unit has two communicating fluidized beds. The first fluidized bed is a reforming reactor containing inorganic metal oxide and which is used to react oxygen and light hydrocarbons to conditions sufficient to produce a mixture of synthesis gas, hydrogen, carbon monoxide, and carbon dioxide. The second fluidized bed is a combustion-regenerator system, which receives the spent inorganic metal oxide from the first fluidized bed and which provides heat to heat the inorganic metal and balance the reaction endotherm, burning combustible gas in direct contact with the oxide Inorganic metallic, producing hot combustion gas. In preferred embodiments, the steam is also fed to the reformer reactor and a catalyst can be used with the inorganic metal oxide. The cogeneration power plant has a gas turbine equipped with an air compressor and a combustion system and in the integration, a portion of compressed air is extracted from the compressor of the gas turbine of the cogeneration power plant that carries the rest of compressed air; the extracted compressed air is introduced to the combustion-regenerator system; The hot combustion gas from the combustion-regenerator system is mixed with the rest of the compressed air to produce a stream of recombined gas and this stream of recombined gas is fed to the combustion system of the cogeneration power plant with gas turbine.