A system for the production of synthesis gas, the system including a mixing apparatus configured for combining steam with at least one carbonaceous material to produce a reformer feedstock; and a reformer comprising a cylindrical vessel containing a plurality of coiled tubes, wherein each of the plurality of coiled tubes has a vertical height in the range of from about 40 feet 12.2 m) to about 100 feet (30.5 m) and a coil length that is at least four times the vertical height; at least one burner configured to combust a fuel and provide heat to maintain the reformer at a reformer temperature; at least one outlet for reformer product comprising synthesis gas; and at least one outlet for flue gas produced via combustion of fuel in the burners. A suitable mixing apparatus is also provided.