Abstract: An apparatus for flamelessly reconcentrating liquid desiccant including vertically disposed upper and lower enclosed reboiler chambers having an enclosed heating section interposed therebetween. Water-rich liquid desiccant is continuously recirculated between the upper and lower reboiler drums through riser conduits disposed within the heating section and return conduits exterior thereof. Simultaneously with the recirculation of the water-rich liquid desiccant an exhaust gas stream from a prime mover is passed through the heating section to convectionally heat the liquid desiccant within the riser conduits causing disengagement of water vapors therefrom. The upper drum includes an outlet for the disengaged water vapors and also an outlet for the resultant water-lean liquid desiccant.