Technology

Synthesis

ACES21^® Process Synthesis Section consists of a Reactor, a Stripper and a Carbamate Condenser (Fig. 1). Liquid Ammonia is fed to the Reactor via the HP Carbamate Ejector which provides the driving force for Circulation in the Synthesis Loop instead of the Gravity System of the original ACES Technology.

Figure 1 - ACES21 Synthetic Loop

The Reactor is operated at an N/C ratio of 3.7, 182 °C and 152 bar. The CO₂ Conversion to Urea is as high as 63% at the Exit of the Reactor. Urea Synthesis Solution leaving the Reactor is fed to the Stripper where unconverted Carbamate is thermally decomposed and excess Ammonia and CO₂ are efficiently separated by CO₂ Stripping. The stripped off Gas from the Stripper is fed to the Vertical Submerged Carbamate Condenser (VSCC), operated at an N/C ratio of 3.0, 180°C and 152 bar. Ammonia and CO₂ Gas condense to form Ammonium Carbamate and subsequently Urea is formed by Dehydration of the Carbamate in the Shell Side. Reaction heat of Carbamate Formation is recovered to generate 5 bar Steam in the Tube Side. A Packed Bed is provided at the Top of the VSCC to absorb uncondensed Ammonia and CO₂ Gas into a Recycle Carbamate Solution from the MP Absorption Stage. Inert Gas from the Top of the Packed Bed is sent to the MP Absorption Stage.

Figure 2 - Chemical Conversion Steps of the ACES21 Technology

Process Performance

Source: Toyo Engineering, Energy-saving Urea Synthesis Technology: ACES21®, toyo-eng.com