A system includes an integrated reactor-syngas cooler that may gasify a feedstock. The integrated reactor-syngas cooler includes a reaction zone that may receive a first syngas and the feedstock, and that may gasify the feedstock to generate a second syngas. The second syngas has a composition different from the first syngas. The system also includes one or more feed injectors disposed in the integrated reactor-syngas cooler and that may supply the feedstock to the reaction zone and a cooling zone disposed downstream of the reaction zone and including one or more cooling tubes. The cooling zone may receive and cool the second syngas.