MXPA98000600A - Production of synthesis gas through steam reform using hardware catalyz - Google Patents

Abstract

A process for the preparation of hydrogen rich carbon monoxide gas by steam reforming a hydrocarbon feed supply in the presence of a steam reforming catalyst supported as a thin film on a tubular reactor, which comprises the steps of (a) optionally passing a process gas from the pre-reformed hydrocarbon feed supply through a first tubular reactor with a thin film of steam reforming catalyst supported on the walls of the reactor in a heat conduction relationship, with gas from hot combustion from a second reforming reactor with subsequent tubular steam, (b) passing the effluent from the first tubular reactor to the second subsequent tubular reactor which is provided with a thin film of the steam reforming catalyst, and which is heated by burning fuel, obtaining in this way a gas effluent partially ref steam and hot combustion gas, (c) passing the effluent from the second reactor to a fixed-bed steam reforming catalyst, and (d) removing from the fixed bed a product of gas, hydrogen and rich gas in carbon monoxide

Description

SYNTHESIS GAS PRODUCTION BY STEAM REFORM USING CATALYZED HARDWARE TECHNICAL FIELD "The present invention relates to the production of synthesis gas by steam reforming a hydrocarbon feed supply in contact with catalyzed hardware." BACKGROUND OF THE INVENTION The term "catalyzed hardware" is used for a catalyst system where a catalyst layer is fixed on a surface of another material, for example, metal surfaces The other material serves as the support structure that gives resistance to the system. designing catalyst shapes that would not have sufficient mechanical strength on their own The system here consists of tubes where a thin layer of reforming catalyst is placed on the inner wall The synthesis gas is produced from hydrocarbons by reforming with steam, through the reactions (l) - (3): CJln + n H20? n CO + (n + m) H2 (-? H ° 298 < 0) (1) 2 CO + H20 «t C02 + H2 (-? H ° 298 = 41 J / mole) (2) CH4 + H20 3f ± CO / + 3 H2 (-? H ° 298 = -206 kJ / mole) (3) The steam reforming technology of the state of the art makes use of a reforming catalyst in the form of granules of different sizes and shapes. The catalyst granules are placed in fixed bed reactors (reformer tubes). The reforming reaction is endothermic. In conventional reformers, the heat necessary for the reaction is supplied from the environment outside the tubes, usually by a combination of radiation and convection to the outer side of the reformer tube. The heat is transferred to the inner side of the tube by conduction of heat through the wall of the tube, and is transferred to the gas phase by convection. Finally, the heat is transferred from the gas phase to the convection catalyst granule. The temperature of the catalyst can be more than 100 ° C lower than the temperature of the inner wall of the tube in the same axial position of the reformer tube. It has been found that heat transport is more efficient when using catalyzed hardware in the steam reforming process. The heat transport to the catalyst is presented by conduction from the inner wall of the tube. This is a much more efficient transport mechanism than convection transport by means of the gas phase. The result is that the temperatures of the internal wall of the tube and the catalyst are almost identical (the difference is less than 5 ° C). In addition, the thickness of the tube can be reduced, see below, which makes the difference in temperature between the inner and outer side of the reformer tube smaller. Accordingly, it is possible to have both a higher catalyst temperature and a lower tube temperature, the other conditions being the same when conventional reformer tubes are replaced with catalyzed hardware tubes. A low temperature of the outer wall of the tube is desirable, since it prolongs the life time of the tube. A high catalyst temperature is desirable, because the speed in the reaction increases with temperature, and because the equilibrium of the reaction (3) changes to the right side, resulting in better utilization of the feed. SUMMARY OF THE INVENTION In accordance with the foregoing, this invention provides a process for the preparation of hydrogen gas rich in carbon monoxide by steam reforming a hydrocarbon feed supply in the presence of a steam reforming catalyst supported as a thin film on a tubular reactor, which comprises the steps of: (a) optionally passing a process gas from the pre-reformed hydrocarbon feed supply through a first tubular reactor with a thin film of steam reforming catalyst supported on the walls of the reactor in a heat conduction relationship, with hot combustion gas from a second reforming reactor with subsequent tubular steam; (b) passing the effluent from the first tubular reactor to the second subsequent tubular reactor which is provided with a thin film of the steam reforming catalyst, and which is heated by burning fuel, thereby obtaining a gas effluent partially reformed with steam and the hot combustion gas; (c) passing the effluent from the second reactor to a fixed bed steam reforming catalyst; and (d) removing from the fixed bed a product of gas, hydrogen and gas rich in carbon monoxide. The pressure drop in the catalytic reformer tube is much lower than in the conventional case for the same tube diameter. This makes it possible to use reactor tubes with a smaller diameter, and an acceptable pressure drop is still maintained. The smaller diameter of the tube results in a longer tube life, tolerates higher temperatures, and reduces the consumption of tube material. Finally, the amount of catalyst is reduced when reformed catalytic hardware tubes are used, compared to the conventional reformer with a fixed bed of reforming catalyst. DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows the front end of a plant that produces syngas. The feed 2 is preheated, desulfurized in unit 4, mixed with the steam of process 6, and further heated before entering an adiabatic pre-reformer 8. The effluent stream from the pre-reformer 8 is further heated in a cycle configured in the combustion gas channel 12, and is sent to the tubular reformer 14, where the conversion of methane into hydrogen, carbon monoxide, and carbon dioxide is presented. The processing of the effluent gas downstream from the tubular reformer depends on the use of the product. The catalysed hardware can be used in two of the units shown in Figure 1. 1. In the preheater coil 10 to heat the effluent gas from the pre-reformer before entering the tubular reformer 14. 2. In the tubular reformer 14. Further on present the results obtained for the plant of Figure 1, when the catalyzed hardware is used in the two previous units. The catalyst used for the catalyzed hardware is the R-67R nickel vapor reforming catalyst available from Haldor Topsoe A / S. The results are compared with the conventional case. The purpose of the preheater coil is to use the heat content of the combustion gas to preheat the process gas before it enters the tubular reformer. The combustion gas is used to preheat the process gas, and to preheat the combustion air for the tubular reformer (not shown in Figure 1). However, the heat content of the combustion gas is greater than what can be used for these purposes, and the remaining heat is used for steam production. It will be an advantage if a greater amount of the heat content of the combustion gas can be transferred to the process gas. This will reduce the amount of fuel needed in the tubular reformer, and reduce the size of the reformer, since a smaller amount of heat will be transferred into the unit. The conventional preheater is limited by the risk of the formation of carbon by the decomposition of methane. This establishes an upper limit for the temperature of the tube wall, which can be accepted. Attaching a catalyzed hardware layer on the inner wall 6 of the tube of the preheater coil 10 (as shown in Figure 2) results in a decrease in both the temperature of the tube wall and the temperature of the gas of process. This makes it possible to transfer a higher work in the coil without having a higher tube temperature. The preheating coil used in the calculation consists of 8 tubes, where the process gas flows into the tubes. The combustion gas flows on the external side. The flow pattern is cross flow / co-current. Figure 2 shows the deployment for a tube. The two cases with and without catalyzed hardware, are summarized in Table 1. It can be seen that the transferred work (heat energy) is 49 percent higher in the case of the catalyzed hardware, compared with the conventional case. The thickness of the catalyst layer in the case of the catalysed hardware is 1.0 millimeters. Table 1 The effective length of the tube is the length of the tube inside the flue gas channel. The conventional tubular reformer consists of a number of tubes that are filled with catalyst granules. The process gas flows inside the tubes. The tubes are placed in an oven that is heated by the combustion of a fuel. In the case of catalyzed hardware, tubes filled with catalyst pellets are replaced with a number of tubes with a catalyzed hardware layer on the inner wall of the tube. The thickness of the catalyst layer is 0.25 millimeters. A further adiabatic reforming fixed bed reactor is placed downstream from the tubular reactor, since the conversion of methane to the catalytic hardware tubular reformer is inferior to the conventional case. This reactor is called rear reformer.

The catalyst used in the subsequent reformer is the RKS-2 nickel vapor reforming catalyst available from Haldor Topsoe A / S. The two cases are summarized later in Table 2.

It is seen that the catalyst consumption decreases by a factor of 11. 5, and that the material consumption for the tubes in the tubular reformer decreases 24 percent in the case of the catalyzed hardware, compared with the conventional case.

Table 2 In Figure 3 a flow diagram of a process according to the invention is shown. The numbers of the triangles refer to the following table, where the global figures for the process are compared. Fuel consumption decreases by 7.4 percent in the case of catalyzed hardware, compared to the conventional case. a a

Claims (4)

1. NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS 1. A process for the preparation of gas hydrogen rich in carbon monoxide by means of steam reforming a hydrocarbon feedstock in the presence of a steam reforming catalyst supported as a thin film on a tubular reactor, which comprises the steps of (a) optionally passing a gas from the feed feed process pre-reformed hydrocarbon through a first tubular reactor with a thin film of steam reforming catalyst supported on the walls of the reactor in a heat conduction relationship, with hot combustion gas from a second reforming reactor with subsequent tubular steam; (b) passing the effluent from the first tubular reactor to the second subsequent tubular reactor which is provided with a thin film of the steam reforming catalyst, and which is heated by burning fuel, thereby obtaining a gas effluent partially reformed with steam and the hot combustion gas; (c) passing the effluent from the second reactor to a fixed bed steam reforming catalyst; and (d) removing from the fixed bed a product of gas, hydrogen and gas rich in carbon monoxide.
2. 2. A process according to claim 1, characterized in that the fixed bed steam reforming catalyst is operated in an adiabatic condition.
3. 3. A process according to claim 1, characterized in that the fixed bed steam reforming catalyst is configured inside the second tubular reactor.
4. 4. A process according to claim 1, characterized in that the steam reforming catalyst comprises nickel and / or ruthenium.