There has been considerable interest in the development of more efficient processes for conversion and utilization of CO2. Tri-reforming, as a new approach for the treatment of CO2 in flue stack gases, has been studied in this work. Tri-reforming process combines CO2 reforming with steam methane reforming and methane oxidation to produce syngas (H-2 and CO) at a suitable ratio. To determine the optimum operating conditions for the production of syngas with a target ratio and maximized CO2 conversion, the effects of various factors including reaction temperature, reactor pressure and CH4 flow rate on the compositions of syngas obtained from tri-reforming process are investigated. Also, the production of dimethyl ether (DME) from syngas has been rigorously simulated. An optimum heat exchange network was obtained with the objective of minimizing utility cost, which was calculated by General algebraic modeling system (GAMS). Results show that tri-reforming coupled to DME synthesis is an economically feasible approach for the treatment and utilization of CO2 in flue stack gases. (C) 2014 Elsevier B.V. All rights reserved.