(100c) Development of an Advanced Control Philosophy for Dry Gas Combined Steam Reforming, to Operate the Plant Efficiently during Feed Composition Changes
AIChE Spring Meeting and Global Congress on Process Safety
2018 Spring Meeting and 14th Global Congress on Process Safety
Process Development Division
Smart Manufacturing I
Tuesday, April 24, 2018 - 10:55am to 11:15am
The existing control philosophy of the reformers cannot cope with the feed disturbances and can be effected by big swings in the reformer temperature, methane slip, fuel gas and steam & carbon dioxide flows in case of dry gas combined steam reformer. These disturbances may also have adverse effects on the plant efficiency, capacity, safety and reliability, and the plant integrity. In order to have a stable operation and cope with these disturbances, most of the existing plants are opting for advanced process control possibilities like Aspen DMC+ etc
In the paper, a new feed forward control strategy is described that can control the dry gas combined steam reforming process efficiently and effectively for a large composition variations. The basic methodology of the new control strategy is to control the steam reforming key parameters like reformer temperature, stream flow, process air, CO2 flow, and Fuel gas flow, based on the carbon count of the natural gas in a feed forward way. Additionally, a small correction to the individual manipulators is done in a feedback control philosophy. This feed-forward & feedback control philosophy enables the operating plant to react to the disturbances quickly and efficiently. Hence, the plant performance disorder is kept minimum and huge swings in the parameters are avoided during the feed disturbances. Also, with this new control strategy, the variations in the plant parameters are reduced and stable and steady production of the hydrogen can save the energy about 0.5 GJ/ton of H2 produced from the reforming process. More than the energy, the process operates more steadily and downstream processes that depend on the reforming process operate steadily as well. This developed strategy is tested and implemented and has improved the plant reliability and integrity.