US 12,240,800 B2
Multiproduct low biuret urea production
Branislav Manic, Maastricht (NL); and Rahul Patil, Maastricht (NL)
Assigned to Stamicarbon B.V., Sittard (NL)
Appl. No. 18/692,124
Filed by Stamicarbon B.V., Sittard (NL)
PCT Filed Nov. 22, 2023, PCT No. PCT/NL2023/050611
§ 371(c)(1), (2) Date Mar. 14, 2024,
PCT Pub. No. WO2024/112197, PCT Pub. Date May 30, 2024.
Claims priority of application No. 22208916 (EP), filed on Nov. 22, 2022.
Prior Publication US 2024/0262789 A1, Aug. 8, 2024
Int. Cl. B01D 1/00 (2006.01); C07C 273/12 (2006.01); C07C 273/16 (2006.01); C07D 251/60 (2006.01)
CPC C07C 273/12 (2013.01) [B01D 1/0088 (2013.01); C07C 273/16 (2013.01); C07D 251/60 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method of operating a urea plant in a reduced load mode, the method comprising:
operating a high pressure urea synthesis section of a urea plant in a reduced load mode;
subjecting a urea solution stream from the urea synthesis section to purification in a recovery section to give purified urea solution;
subjecting the purified urea solution to evaporation of water in a first vacuum evaporation stage, to give a first concentrated urea solution;
subjecting a first part of the first concentrated urea solution to evaporation of water in a first evaporator of a second vacuum evaporation stage to form a first urea melt;
subjecting a second part of the first concentrated urea solution to evaporation of water in a second evaporator of the second vacuum evaporation stage to form second urea melt;
wherein the first evaporator is operated at a first operating capacity ratio, as percentage of a design capacity of the first evaporator, and wherein the second evaporator is operated at a second operating capacity ratio, as percentage of a design capacity of the second evaporator, wherein the second operating capacity ratio is lower than the first operating capacity ratio, and wherein the second evaporator has an outlet for the second urea melt connected with an inlet of a melamine plant.