Solution Provided | Delivered a Pre-Feasibility Study (PFS) to reduce GHG emissions by improving energy efficiency in the Refinery.
Discipline | Process Engineering, Civil and Structural Engineering, Mechanical Engineering, Design, Estimation
In June 2018, Carnac - Carnac Project Delivery Services (Carnac) conducted a concept level validation of 5 opportunities to reduce GHG emissions in an Alumina Refinery via energy improvements. Three of these opportunities were identified for a PFS. The 3 options were:
Evaporator heater upgrades: Live steam savings diminished rapidly beyond the replacement of the 3rd stage flash heater with plate heat exchanger. The recommendation was to replace the first 3 cold end shell and tube heaters with plate heat exchangers with improved heat transfer capability reducing live steam usage in the area;
Heating of spent liquor to mills: Two options were considered for heating spent liquor. Option 1 considered using hot green liquor and Option 2 considered modification of the plate heat exchangers. During the course of the study an Option 3 was identified which relied on debottlenecking the spent liquor circuit. Option 3 maximised the GHG reduction with the smallest capital investment; and
Using hot spent liquor for making caustic cleaning brews: Steam savings came from reduced steam required to heat the caustic brew. This option involved installation of new piping, instrumentation and control to direct the hot spent liquor.