Method for preparation of ammonia gas and co2 for a urea synthesis process

Abstract

The invention relates to a process for preparing ammonia gas and CO 2 for urea synthesis. In the process of the invention, a process gas containing nitrogen, hydrogen and carbon dioxide as main components is produced from a metallurgical gas. The metallurgical gas consists of blast furnace gas, or contains blast furnace gas at least as a mixing component. The process gas is fractionated to give a gas stream containing the CO 2 component and a gas mixture consisting primarily of N 2 and H 2 . An ammonia gas suitable for the urea synthesis is produced from the gas mixture by means of ammonia synthesis. CO 2 is branched off from the CO 2 -containing gas stream in a purity and amount suitable for the urea synthesis.

1 . A process for preparing urea, where ammonium carbamate is produced from ammonia gas and CO 2  using an excess of ammonia and the ammonium carbamate is converted into urea in subsequent decomposition stages at low pressure, wherein the ammonia gas required for the synthesis of urea and the CO 2  which is likewise required for the synthesis of urea are produced from a metallurgical gas which contains blast furnace gas at least as mixing component or consists of blast furnace gas.