Method for the simultaneous modernisation of a plant for ammonia production and a plant for urea production

摘要

PURPOSE: Disclosed is a method for simultaneously modernizing the subjects plants by a technically easily method which adds a carbamic acid synthesis and decomposition section to the existing sections, to increase production capacity of each plant and reduce energy consumption at a low investment cost. CONSTITUTION: This method is to add a carbamic acid synthesis and decomposition section to the existing sections of an ammonia and urea production plant. The added sections include means for, e.g. supplying the compressed unrefined ammonia synthesis gas flow containing carbon dioxide, hydrogen and nitrogen to the carbamic acid synthesis section; supplying part of the flow from the ammonia synthesis section, containing ammonia, hydrogen and nitrogen, to the carbamic acid synthesis section; supplying at least part of the flow from the urea recovering section, containing carbamic acid in the aqueous solution, to the carbamic acid decomposition section, and supplying the flow from the decomposition section, containing ammonia vapor and carbon dioxide gas, to the urea synthesis section.