History:
Customer operates one of the largest integrated Ammonia-Urea Fertilizer plant in India, comprising 900TPD Ammonia & 1500TPD Urea facility.

Process Overview:
Ammonia and Urea production units generate the required H2, N2 & CO2 feeds through a common reformer.

Outlet gases from the reformer are passed thru the absorber, where Hydrogen along with other light gases are separated while the CO2 is removed through absorption in the solution. Hydrogen & other light gases along with slipped CO2 from the top of the absorber are passed to the methanation section. The methanator converts the residual CO2 to methane to increase the catalyst life of the ammonia reactor.

The rich solution from the absorber is then stripped in the regenerator and the CO2 gas used to produce Urea. The lean solution from the regenerator bottom is sent back to the absorber.

Customer Requirements:
Customer was facing serious problem of liquid carry over in the CO2 stream from the regenerator top which was following the downstream heat exchangers.

Problem analysis:
After studying the system for operation at an increased capacity it was noted that
- Absorber was functioning normally.
- Regenerator column was experiencing severe liquid carryover along with the CO2.
- Feed inlet nozzle was directing the inlet mixed phase feed onto the clear liquid residing on the Flash Feed Gallery (FFG) deck thereby creating turbulence and liquid carryover problem.

Solutions provided:
After studying entire equipments in CO2 removal section & further detail hydraulic check at increased capacity, following was recommended
- Option1 - Increase the FFG vertical wall height (that would entail hot work).
- Option 2 - decrease the open area thereby increasing the FFC deck area. Modify the inlet feed arrangement to facilitate lateral release of liquid along the column peripheryl & then onto the FFG.

Customer accepted option 2 along with modification of inlet feed arrangement.

Accordingly the equipment was mechanically designed, manufactured and installed without involving any hot work to the column.

Results achieved:
The problem of carryover is solved. The CO2 removal section now runs at increased load of 1350 MTPD.