Process for the production of formaldehyde-stabilized urea

Abstract

A process for the production of formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas; (b) subjecting the synthesis gas to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (c) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (d) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (e) synthesising methanol from the carbon dioxide-depleted synthesis gas in a methanol synthesis unit and recovering the methanol and a methanol synthesis off-gas; (f) subjecting at least a portion of the recovered methanol to oxidation with air to form formaldehyde in a stabiliser production unit; (g) subjecting the methanol synthesis off-gas to methanation in a methanation reactor containing a methanation catalyst to form an ammonia synthesis gas; (h) synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia; (i) reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream; and (j) stabilising the urea by mixing the urea stream and a stabiliser prepared using the formaldehyde produced in the stabiliser production unit, wherein the carbon dioxide removal unit operates by means of absorption using a liquid absorbent and comprises an absorbent regeneration unit, wherein the process includes recovering a carbon dioxide-containing gas stream from the absorbent regeneration unit, compressing at least a portion of the recovered carbon dioxide-containing gas stream to form a compressed carbon dioxide-containing gas stream and passing the compressed carbon dioxide-containing gas stream to the methanol synthesis unit.