Steam reforming reactors

Steam reforming reactors are conveniently divided into  

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Traditionally, the steam reforming reactor has a tubular design in which vertical tubes, loaded with catalyst, are surrounded by furnaces to supply the heat required for the strongly endothermic process, see Fig. 8.2. Combustion of natural gas supplies the heat to the tubes. 

Ereeman, H. D., Marco, J. L., Roberts, G. L., VanderWiel, D. P., A compact steam reforming reactor for use in an automotive fuel processor, in Proceedings of the 4th International Conference on Microreaction Technology, IMRET 4, pp. 358-363 (5-9 March 2000), AIChE Topical Conf. Proc., Atlanta, USA. 

An intrinsic, exothermic water-gas shift reaction occurs in the steam reformer reactor. The combined reaction, steam reforming and water gas shift, is endothermic. As such, an indirect high temperature heat source is needed to operate the reactor. This heat source usually takes the shape of an immediately adjacent high temperature furnace that combusts a small portion of the raw fuel or the fuel effluent from the fuel cell. Efficiency improves by using rejected heat from other parts of the system. Note that the intrinsic water-gas shift in the reactor may not lower the... 

The CH4 in the natural gas is usually converted to H2 and CO in a SR reactor. Steam reforming reactors yield the highest percentage of hydrogen of any reformer type. The basic SR reactions for methane and a generic hydrocarbon are ... 

The next step in the processor development will be to integrate the palladium alloy membrane with the methanol steam reformer reactor. The researchers anticipate that the addition of the palladium membrane will improve the reactor performance due to in-situ hydrogen removal. 

Table 5. Methanol Steam Reforming Reactor Performance ...

Carbonaceous compounds can also form in the absence of a catalyst by free-radical, gas-phase condensation reactions. The formation of this pyrolytic carbon is known in steam-reforming reactors where it can be controlled to some extent by minimizing the free volume within the reactor chamber. This type of carbon does not form readily with methane but can be severe with larger hydrocarbons. The compounds formed by free-radical reactions tend to be quite different from the graphitic carbon formed by metal catalysts. For example, Lee et al. showed that the compounds formed by passing pure, undi-... 

Steam reforming reactors have the supported nickel catalyst packed in tubes and the endothermic heat of reaction supplied from a... 

Recently, Comas et al.219 performed the thermodynamic analysis of the SRE reaction in the presence of CaO as a C02 sorbent. The equilibrium calculations indicate that the presence of CaO in the ethanol steam reforming reactor enhances the H2 yield while reducing the CO concentrations in the outlet of the reformer. Furthermore, the temperature range at which maximum H2 yield could be obtained also shifts from above 700 °C for the conventional steam reforming reaction without CaO to below 700 °C, typically around 500 °C in the presence of CaO. It appears that the presence of CaO along with ethanol reforming catalyst shift the WGS equilibrium in the forward direction and converts more CO into C02 that will be simultaneously removed by CaO by adsorption. 

In general, the gas leaving a steam-reforming reactor is close to chemical equilibrium for Reaction (1) in Table 2. In industry, the approach to equilibrium at the outlet of the reformer tubes is expressed by a temperature difference defined by ... 

Another type of steam-reforming reactor that is attracting increasing attention is known as gas heated reformers or heat exchange reformers. In such reformers, heat is transferred by convection and the heat source is a hot process gas from another reformer or a partial oxidation reactor. A number of different installations of heat exchange reformers can be envisaged. In Fig. 5, the installation of a heat exchange reformer either in series or in parallel to an auto-thermal reformer (ATR) is illustrated. 

Figure 4. Catalytic Fluid Bed Steam Reforming Reactor...

A schematic and photograph of the pilot-scale catalytic fluid bed reformer are shown in Figure 4. The 30-cm catalytic steam reforming reactor was successfully operated on peanut pyrolysis vapor at a feed rate of 7 kg/hour of vapors. The results are in agreement with those obtained from the 5-cm bench-scale reactor used for the reforming of the aqueous fraction of pyrolysis oil. Typical gas compositions at the outlet of the reformer are shown in Figure 5. These data show that the yield of hydrogen is approximately 90% of maximum. 

The 30-cm catalytic steam reforming reactor was successfully operated on peanut shell pyrolysis vapor at a feed rate of 7 kg/hour of vapors. 

Through improvements in gas flow eharacteristics and engineered catalyst performance, the volumetric productivity of the steam reforming reactor was improved by approximately a factor of three eompared to our previous efforts. The catalyst... 

Various fuel components and fuels have been tested with various 0/C and S/C ratios in partial oxidation/steam reforming reactors. The addition of aromatics slows the overall reaction rate for catalytic oxidation. Real fuels have similar oxidation rates at high 0/C compared with iso-octane, but lower oxidation rates at 0/C < 1.0. 

The reduction of operating temperature drives the plant designers to find new and better solutions to supply heat duty to steam reforming reactors, exploiting, for example, heat streams from other parts of industrial plants. 

The milder condition makes it possible to locate membrane assisted reformer downstream of a gas turbine with a consequent reduction in energy saving. An interesting application of membrane steam reforming reactor to co-generative systems was reported by laquaniello et The process layout is shown in... 

In this process the hydrogen conversion is carried out in two reactors in series. The first one, the steam reform reactor converts steam and a hydrocarbon (naphtha or natural gas) into syngas. In the sequence, a reactor known as water gas shift reactor (WGSR) converts the carbon monoxide present in syngas into carbon dioxide and more hydrogen is generated. 

First, sulfur is removed from the hydrocarbon stream (usually natural gas), in order to prevent catalyst poisoning and deactivation with the use of a guard bed. Steam is mixed in the main stream in a fixed steam to carbon molar basis. The steam reform reactor (SRR) is a multitubular catalyst filled furnace reactor where the hydrocarbon plus steam are converted into syngas at high temperatures (700°C - 850 C) according to the following reaction ... 

The aim of the project was to assess the industrial feasibility of the integration of a steam reformer reactor with a membrane for hydrogen separation. The plant was successfully running continuously for up to 1000 h, with no catalyst or membrane deterioration (De Falco et ai, 2011). 

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