Abstract: An apparatus and process are provided for concentrating oil and gas production brine. The apparatus comprises a brine feed system, a hot air generation system, a concentrated brine collection and recirculation system, and an evaporation tower. The evaporation tower includes a brine inlet coupled to the brine feed system, a hot air inlet coupled to the hot air generation system and positioned below the brine inlet, a steam discharge, a concentrated brine outlet, a plurality of distillation trays, and a concentrated brine reservoir in the lower portion of the tower. The evaporation tower also has a distributor at the brine inlet adapted to distribute brine onto the trays and may have a plurality of spray nozzles disposed above the hot air inlet to distribute a spray of recirculated concentrated brine. Water evaporates from the brine and the entering hot air temperature is modulated by evaporation.