In Hydrogen plant steam flow is fixed at 30-70 % plant load in Haldor Topsoe unit, while in Linde hydrogen plant steam flow is fixed in between 30-50%. What are the reasons for this difference?
Rajesh Nandanwar, Bharat Oman Refineries Limited, Bina, email@example.com
Different plant licensor have slight changes in operating procedures and flows at lower throughput. Hydrogen reformer tubes are designed for certain hydralic flow for max throughput level. Outside the tubes, firing is provided to get the heat to the catalyst and further to the process fluid. If total flow is reduced, there are chances of channeling in the tubes. Channeling would cause overheating in tubes and coking tendency would increase. Once coking is started, active catalyst surfaces are covered and reaction in tubes would reduce. This would result in less absorption in tubes and higher tube skin temperatures.
Basically at throughput level below 50%, sufficient flow through tubes is required which is maintained by maintaining constant steam flow equivalent to 50% or as calculated by individual licensor to avoid channeling and coking. Whether it is 50,60 or 70% equivalent is based on individual licensors design and operating phelosophy.