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The steam-methane reaction is an essential step for many processing plants. Hydrogen, ammonia and methanol are mostly produced by means of methane steam reforming. Since hydrogen is essential for any refinery employing hydrotreating, the performance monitoring of the hydrogen plant is highly desirable. The use of models or simulation is now a standard practice in most chemical plants and refineries. However, reliable models are still lacking for speciality reactors like the methane steam reformer. This paper describes steady-state and dynamic models for the reactions involved in reforming methane and higher hydrocarbon gases. The performance of the reformer is then illustrated by sensitivity analysis to various input disturbances like inlet pressure, temperature, feed concentration and rate, fuel rate and density and steam to carbon ratio. The effect of these disturbances on exit temperature and conversion is studied and analyzed. Catalyst deactivation effects are also discussed and it is shown by sample calculations that the simulator can give insight into catalyst performance and assist in monitoring catalyst deactivation. The transient effects are also reported and dynamic elements like gains and response time are discussed. Such information should give insight into controller design and effects of various parameters. |
