US 11,912,649 B2
Ammonia removal from urea finishing
Rahul Patil, Maastricht (NL); Branislav Manic, Maastricht (NL); and Petrus Anna Maria Robertus Simons, Schimmert (NL)
Assigned to Stamicarbon B.V., Sittard (NL)
Appl. No. 17/424,948
Filed by STAMICARBON B.V., Sittard (NL)
PCT Filed Dec. 30, 2020, PCT No. PCT/NL2020/050825
§ 371(c)(1), (2) Date Jul. 22, 2021,
PCT Pub. No. WO2021/137700, PCT Pub. Date Jul. 8, 2021.
Claims priority of application No. 19220059 (EP), filed on Dec. 30, 2019.
Prior Publication US 2022/0089527 A1, Mar. 24, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. C07C 273/14 (2006.01); C07C 273/04 (2006.01); B01D 53/00 (2006.01); B01D 53/58 (2006.01)
CPC C07C 273/14 (2013.01) [B01D 53/002 (2013.01); B01D 53/58 (2013.01); B01D 2251/504 (2013.01); B01D 2251/506 (2013.01); B01D 2257/406 (2013.01); B01D 2257/80 (2013.01); C07C 273/04 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method for the removal of ammonia from an off-gas of a finishing section of a urea production plant, wherein the finishing section operates a conversion of a urea melt into solid urea products, thereby generating an ammonia-containing off-gas, the method comprising: obtaining said urea melt by evaporating water from an aqueous urea solution in a first stage evaporation section, so as to form a first water vapour and a concentrated urea solution; further evaporating water from said concentrated urea solution in at least one second stage evaporation section so as to form a second water vapour and the urea melt; subjecting the off-gas to contact with an acidic scrubbing liquid in a scrubbing system so as to provide a scrubbed off-gas and a utilized scrubbing liquid comprising one or more ammonium salts and water; and sending the utilized scrubbing liquid to the second stage evaporation section, thereby subjecting it to evaporation of water together with the concentrated urea solution; and sending said urea melt to the finishing section for conversion of the urea melt into the solid urea products and the ammonia-containing off-gas, wherein all of the urea melt sent to the finishing section comprises the one or more ammonium salts.
 
2. A method for the production of a solid urea product, comprising producing an aqueous urea solution, evaporating water from said aqueous urea solution in a first stage evaporation section so as to form a first water vapour and a concentrated urea solution, providing all of the concentrated urea solution to a second stage evaporation section and further evaporating water from the concentrated urea solution in the second stage evaporation section to form a second water vapour and a urea melt, and conversion of the urea melt into the solid urea product thereby generating an ammonia-containing off-gas; subjecting said ammonia-containing off-gas to contact with an acidic scrubbing liquid in a scrubbing system so as to provide a scrubbed off-gas and a utilized scrubbing liquid comprising an ammonium salt and water; the method further comprising sending the utilized scrubbing liquid to said second stage evaporation section, thereby subjecting it to evaporation of water together with the concentrated urea solution.