Steam hydrocarbon reforming operation

The steam-hydrocarbon reforming process is highly developed and will operate for months or even years without interruption, except for normal outages scheduled for boiler inspection, routine maintenance, and other attention which is placed on a definable schedule. The heat balance and utilization are well engineered ordinarily so that there is little waste, and what heat is unused on the furnace side of the reformer is subsequently recovered for use to generate steam. 

High-Temperature Nonregenerative Processes. For many years zinc oxide has been the preferred sorbent for removing traces of hydrogen sulfide from natural gas feed to steam-hydrocarbon reformers producing synthesis gas for the production of ammonia and other petrochemicals. The zinc oxide is typically in the fotm of cylindrical extiudates 3-4 nun in diameter and 4-8 mm in length. Several forms are available for operation at temperatures from about 400° to 750°F. 

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

Hydrocarbon Research Inc., elected partial oxidation for the Carthage Hydrocol plant at Brownsville. After initial experiments that Hydrocarbon Research conducted at Olean, New York, The Texas Company assumed responsibility for further development of partial oxidation at its Montebello, California, laboratory, under duBois ( Dubie ) Eastman. For conversion of natural gas to gasoline by Fischer-Tropsch synthesis, partial oxidation s advantage over steam-methane reforming lay in its ability to operate at a pressure approximating that of the synthesis, thereby essentially eliminating need for compression of synthesis gas. 

Damon and White (4) proposed the production of reducer gas by Reaction 4 using natural gas or propane as a hydrocarbon source. The proposed process for steam-methane reforming would operate at a tem-... 

A pre-reformer is incorporated prior to the reformer unit. Since the pre-reformer operates at a much lower temperature (770 K) than in SMR, the steam produced within the reformer provides some of the heat of the endothermic reaction. Pre-reforming has a dramatic effect on the gas stream to be fed into the SMR unit. Co and Cs hydrocarbons are completely removed, while a certain proportion of CH4 is also converted. A recent review summarises the output of a typical pre-reformer. The catalyst used in pre-reforming contains higher Ni-loadings (above 25% Ni) than conventional SMR catalysts. 

Many refiners are still operating hydrogen plants that were designed and built 20 or more years ago. These older plants were generally designed with the best available technology of the time. These typical plants consist of a steam-methane reformer (SMR) to convert the hydrocarbon feed to a S5mgas... 

The hydrocarbon reforming reaction gives a mixture of carbon monoxide and water which is close to eqnihbrinm at the usnal operating conditions. The reaction between steam and the hydrocarbon gives a mixture of carbon monoxide and hydrogen that is close to thermodynamic eqnilibrium at the temperature and pressure of the reactor. 

Phosphoric Acid Fuel Cell. Concentrated phosphoric acid is used for the electrolyte ia PAFC, which operates at 150 to 220°C. At lower temperatures, phosphoric acid is a poor ionic conductor (see Phosphoric acid and the phosphates), and CO poisoning of the Pt electrocatalyst ia the anode becomes more severe when steam-reformed hydrocarbons (qv) are used as the hydrogen-rich fuel. The relative stabiUty of concentrated phosphoric acid is high compared to other common inorganic acids consequentiy, the PAFC is capable of operating at elevated temperatures. In addition, the use of concentrated (- 100%) acid minimizes the water-vapor pressure so water management ia the cell is not difficult. The porous matrix used to retain the acid is usually sihcon carbide SiC, and the electrocatalyst ia both the anode and cathode is mainly Pt. 

Steam Reforming. In steam reforming, light hydrocarbon feeds ranging from natural gas to straight mn naphthas are converted to synthesis gas (H2, CO, CO2) by reaction with steam (qv) over a catalyst in a primary reformer furnace. This process is usually operated at 800—870°C and 2.17—2.86... 

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