Plantwide control of a coupled reformer/ammonia process

Ammonia is one of the most important chemicals from a humanitarian perspective because of its vital use in fertilizer production to maintain food supplies for an ever growing world population. An earlier study explored the design and control of the ammonia process given a fresh feed of hydrogen and nitrogen. The importance of having the correct feed composition to satisfy the reaction stoichiometry was highlighted. The purpose of this paper is to study both the design and the control of a combined reformer/ammonia process in which steam-methane reforming, autothermal reforming and water-gas shift reactors are used to produce the hydrogen/nitrogen feed to the ammonia plant from fresh feeds of methane, water and air.