A plant for concentrating a tartaric acid solution includes a first and a second evaporation unit arranged in series, a pump for feeding a diluted tartaric acid solution into the first evaporation unit, a barometric condenser placed downstream of the second evaporation unit, and a system for feeding a first low-temperature vapor into the first evaporation unit. A process for concentrating tartaric acid includes providing a plant according to the above description, performing a first concentration, by evaporation, of the diluted tartaric acid solution, inside the first evaporation unit, and performing a second concentration, by evaporation, of the partially concentrated tartaric acid solution from the first evaporation unit, inside the second evaporation unit. The plant and process have the advantages of ensuring low energy consumption, allowing concentration of solutions tending to crystallization, and allowing the continuous measurement of the tartaric acid concentration to be concentrated.