Patent Application
20160136604
The invention relates to contact-type devices that are used for oxidative conversion of hydrocarbonaceous gases through processes of steam-oxygen reforming to obtain hydrogen or synthesis gas for the chemical industry.
Catalytic partial oxidation of hydrocarbonaceous feedstock in the presence of oxygen and water steam (steam-oxygen reforming) is found to be a promising process because it allows to obtain synthesis gas at lower temperatures than partial oxidation by free oxygen does and, provided its feedstock has a definite composition, in the case of autothermal reforming requires no heat input to a reaction zone as steam reforming does.
Steam-oxygen reforming of hydrocarbonaceous feedstock is carried out as follows. The heated components—hydrocarbonaceous feedstock, water steam, and oxygen or oxygen-containing gas (usually air or oxygen-enriched air) are being mixed up and fed to a reactor with a catalyst placed in it. The zone of contact of the feedstock with the catalyst forms the reaction zone. In the upper part of the reaction zone fast exothermic reactions of oxidation of methane and other hydrocarbons alongside with endothermic reactions of steam reforming of hydrocarbons occur with the share of the latter growing up downstream lowering the bed outlet temperature. The temperature profile across the height of the catalyst layer has a distinct hump in the front layer of the catalyst (10-15% of the catalyst total height). In theory, a heating-up temperature of a gaseous mixture in the front layer of a catalyst of partial oxidation exceeds 1200° C. and is only limited by the beginning of the highly endothermic reaction of water steam molecule dissociation. The reaction product—a mixture of hydrogen, carbon oxides and water steam—is removed from the reaction zone at a temperature of not more than 1000° C., cooled down, separated from water, and flowed to further processing, for example, to the synthesis of hydrocarbons via the Fischer-Tropsch process. In some cases, cooling of products includes quenching by direct heat exchange with water or in a special device, or in a quenching zone downstream the reaction zone in the reactor (U.S. Pat. No. 5,358,696, U.S. Pat. No. 6,797,022).
A catalyst used for conversion of hydrocarbonaceous feedstock to synthesis gas may be prepared in the form of bulk material or in the form of blocks (consisting of plates, tapes, foamed materials) of heat-conducting elements made of ceramics or metal alloys with a developed external surface, which has a layer of a catalytically-active substance deposited on it. The temperature increase in the catalyst layer accelerates its structural degradation and lowering of catalytic activity.
The problem of catalyst overheating is more or less successfully being solved in an isothermic reactor. In order to create close to isothermic conditions in the reaction zone there are used reactors of tubular heat exchanger type (for example, a tubular reactor (in patent U.S. Pat. No. 8,216,531), heat-conducting elements (for example, heat-conducting plates in a catalyst layer within a reactor in patent RU2175799), as well as specifically arranged conditions of mass- and heat-transfer in the reaction zone (a fluidized bed in U.S. Pat. No. 4,888,131, turbulent regime of reactor flows in application WO2013008020).
Provided a catalyst of steam-oxygen reforming possesses sufficient heat resistance and the raise of temperature in its front layer till 1200° C. does not incur its quick deactivation, and complication of reactor design and its operating systems is undesirable (for example, in case of package units for synthesis gas production to be used in remote fields), an utilization of a heat-conducting catalyst support and specific heat-conducting elements in the catalyst layer seems to be sufficient for temperature equalization throughout the reaction zone. A catalyst in the form of gas-permeable blocks can be placed in a metal sleeve (cup), which outer diameter is less than the inner diameter of the reactor pressure vessel, with the gap between the pressure vessel and the sleeve filled in with a heat-insulating material. A reactor with such elements is disclosed in application for an invention RU2012107731 taken as a prototype. But a metal alloy, which the sleeve is made from, should be enough heat- and corrosion-resistant under conditions of the working temperatures in the reaction zone, i.e. at temperatures of 1200° C. and higher. Such alloys are of high cost. Decreasing the temperature of the catalyst sleeve wall till 1000° C. and lower allows to make it from a relatively inexpensive heat-resistant alloy, for example, of XH45I-O grade, which is corrosion-resistant till the temperature of 1200° C.
A technical task this invention is addressed to—decreasing of the temperature of the catalyst sleeve wall till 1000° C. and lower and reduction of corrosion of catalyst sleeve material. A technical decision is cooling of the catalyst sleeve by a cooling agent—water steam and/or an inert under the reaction conditions gas or an admixture of such gases, for example, nitrogen, synthesis gas. Supplied to the jacket a cooling agent cools the catalyst sleeve wall and enters through open-end holes in the catalyst sleeve wall into the catalyst sleeve into the catalyst layer.
A proposed reactor for partial oxidation of carbonaceous feedstock comprises a pressure vessel with the means for reaction products outlet and with at least one means for feedstock, or components of feedstock, inlet into the placed within the reactor with a gap between the pressure vessel catalyst sleeve filled in with a catalyst and comprising the means of products outlet in its lower part, and differs in that the catalyst sleeve is furnished with a jacket adjacent to at least a part of the cylindrical wall of the catalyst sleeve that has open-end holes in the adjacency zone and the reactor is furnished with a means of inlet into the jacket of the cooling agent that cools the catalyst sleeve and then enters the catalyst sleeve through the open-end holes in the cylindrical wall.
The jacket cooling the catalyst sleeve is located at the outer side of its cylindrical wall and is adjacent to at least a part of its surface. The jacket may wrap the cylindrical wall of the catalyst sleeve in whole or its upper, most hot part. The catalyst sleeve wall being cooled by the direct contact with a cooling agent is made with open-end holes along the full height or only an upper part—the zone where the temperature of a catalyst exceeds 1000° C. The hole sizes, their amount, the distance between the holes and the amount of a cooling agent supplied to the jacket of the catalyst sleeve are chosen out of necessity to guarantee the temperature of the catalyst sleeve wall is not above a defined limit. For example, with decreasing the temperature of the catalyst sleeve wall at least till 1000° C. it would become possible to make it from the steel of grade XH45I-O, which is corrosion-resistant till the temperature of 1200° C. The cooling agent inflow into the catalyst layer through the open-end holes in the catalyst sleeve wall may prevent the catalyst sleeve wall from the contact in this zone with the oxygen of the reaction mixture thus inhibiting material corrosion. Steam layer forming during exhaust of cooling agent (steam) through these holes in the area of contact between catalyst and catalyst sleeve protects catalyst sleeve material against contact with oxygen contained in reaction mixture, which reduces the speed of catalyst sleeve material corrosion.
As a cooling agent there may be used water steam or synthesis gas obtained in the reactor and cooled down at later stages of reactor products treatment. It is preferable to utilize water steam, which, entering the catalyst sleeve contacts with the catalyst it is filled with and takes part in the reaction of partial oxidation of hydrocarbonaceous feedstock. The jacket is furnished with at least one means of a cooling agent inlet.
Hydrocarbonaceous feedstock and necessary for its partial oxidation components—oxygen or oxygen-containing gas, water and, sometimes, carbon dioxide—are fed to the reactor as a single mixed flow or it is used a distributed inlet of a feedstock mixture or its components. The way of feedstock supply does not relate to the substance of the present invention.
The invention will be described in greater detail with reference to the accompanying drawings which represent preferred embodiments thereof, wherein:
While the present teachings are described in conjunction with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments. On the contrary, the present teachings encompass various alternatives and equivalents, as will be appreciated by those of skill in the art.
The scheme of shaft type adiabatic reactor for partial oxidation of hydrocarbonaceous gases with a cooling jacket along the full height of the catalyst sleeve is represented on
The reactor operates as follows. Heated feedstock mixture through a means of feedstock inlet enters the catalyst sleeve, contacts with the catalyst placed in it to form reaction products. A cooling agent through a means of inlet enters the catalyst sleeve jacket, cools it and through the holes in the catalyst sleeve wall enters inwards and is mixed up with the reaction medium. The product containing the cooling agent or products of its conversion when in contact with the catalyst is flowed out from the catalyst sleeve via the means of product outlet from the catalyst sleeve and via the means of product outlet from the reactor and then directed to further treatment including cooling.
The scheme of shaft type reactor for partial oxidation of hydrocarbonaceous gases with a cooling jacket in an upper zone of the catalyst sleeve and a cooling chamber for reaction products is represented on
The reactor operates as follows. Heated feedstock mixture through a means of feedstock inlet enters the catalyst sleeve, contacts with the catalyst placed in it to form reaction products. A cooling agent through a means of inlet enters the catalyst sleeve jacket, cools it and through the holes in the catalyst sleeve wall enters inwards and is mixed up with the reaction medium. The product containing the cooling agent or products of its conversion when in contact with the catalyst is flowed out from the catalyst sleeve via the means of product outlet from the catalyst sleeve and then directed to the product cooling chamber fed with water and spraying gas. The cooled down products mixed up with water vapors and spraying gas are flowed out via the means of product outlet from the reactor and then directed to further treatment.
A design of the reactor and a cooling agent amount for cooling the catalyst sleeve wall is determined on the basis of requirements as to its temperature, productive capacity of the reactor, an area of the cooling surface and cooling agent specifications. A temperature of the catalyst sleeve wall should preferably not exceed 1000° C. though other choices are possible including utilization of a cooling jacket for cooling the most thermally loaded zone of the catalyst sleeve.
The foregoing description of one or more embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014100683 | Jan 2014 | RU | national |
This application is the national stage entry of International Appl. No. PCT/RU2014/000134, filed Feb. 28, 2014, which claims priority to Russian Patent Application No. 2014100683, filed Jan. 13, 2014. All claims of priority to that application are hereby made, and that application is hereby incorporated in its entirety by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/RU2014/000134 | 2/28/2014 | WO | 00 |
