A radiant heat chemical reactor is configured to generate chemical products including synthesis gas products. Two or more tubes in the radiant heat chemical reactor separate an exothermic heat source, such as flames and gas from a regenerative burner, from the endothermic reaction of the reactant gas occurring within the cavity of the refractory vessel. The exothermic heat source heats a space inside the tubes. One or more feed lines supply chemical reactants to the cavity area between an inner wall of the cavity of the refractory vessel of the chemical reactor and the two or more tubes that are internally heated located with the cavity.