Steam Methane Reforming Process Description

In some cases, traces of halides (e.g., chlorides) are also present in the NG feedstock, and these are removed by an alumina guard bed. 

Pretreated NG feedstock is mixed with steam (2.6 MPa), the resulting mixture is preheated to 500°C and introduced to the catalytic reforming reactor. In the reforming reactor, the steam-methane mixture is passed through externally heated reformer tubes filled with Ni catalyst, where it is converted to CO and H2 at 850-900°C according to the following equation  

An addition of the supplemental steam shifts the reforming reaction equilibrium away from carbon formation. 

The gaseous mixture containing H2, CO, and steam (and usually about 4% of unconverted methane) leaves the reformer at about 800-900°C. ft is cooled rapidly to about 350°C (thereby generating steam) and is fed to WGS reactors, where CO reacts with steam over a catalyst bed producing H2 and C02  

Equilibrium mole fraction of CO and C02 in C0-H20-H2-C02 mixture as a function of temperature. 0 is the initial H20/CO molar ratio. 

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A chemical company is considering the production of 1000 tons/day of high-purity anhydrous ammonia. The method selected is a high-pressure steam-methane reforming process. The process description is as follows ... 

Several processes are available for the production of the additional hydrogen that is necessary for the various heavy feedstock hydroprocessing sequences that have been outlined elsewhere (Chapters 7 and 9), and it is the purpose of the present section to present a general description of these processes. In general, most of the external hydrogen is manufactured by steam-methane reforming or by oxidation processes. Other processes such as ammonia dissociation, steam-... 

Description The gas feedstock is compressed (if required), desulfurized (1) and process steam is added. Process steam used is a combination of steam from the process condensate stripper and superheated medium pressure steam from the header. The mixture of natural gas and steam is preheated, prereformed (2) and sent to the tubular reformer (3). The prereformer uses waste heat from the flue-gas section of the tubular reformer for the reforming reaction, thus reducing the total load on the tubular reformer. Due to high outlet temperature, exit gas from the tubular reformer has a low concentration of methane, which is an inert in the synthesis. The synthesis gas obtainable with this technology typically contains surplus hydrogen, which will be used as fuel in the reformer furnace. If C02 is available, the synthesis gas composition can be adjusted, hereby minimizing the hydrogen surplus. Carbon dioxide can preferably be added downstream of the prereformer. 

Description Natural gas or another hydrocarbon feedstock is compressed (if required), desulfurized, mixed with steam and then converted into synthesis gas. The reforming section comprises a prereformer (optional, but gives particular benefits when the feedstock is higher hydrocarbons or naphtha), a fired tubular reformer and a secondary reformer, where process air is added. The amount of air is adjusted to obtain an H2/N2 ratio of 3.0 as required by the ammonia synthesis reaction. The tubular steam reformer is Topsoe s proprietary side-wall-fired design. After the reforming section, the synthesis gas undergoes high- and low-temperature shift conversion, carbon dioxide removal and methanation. 

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