Studies of multitubular reactors with internal heat recovery. Experiments with SO2 oxidation

This paper presents results of investigations of a multitubular reactor with internal heat recuperation. The multitubular reactor with both the tube-side and the shell-side spaces packed with catalyst pellets or, alternatively, with an inert material and catalyst, enables one to heat up a relatively cold inlet reaction medium by internal heat recovery. The reaction heat transferred to the inlet reaction gas allows the gas temperature to be raised above the so-called “ignition” temperature. Considerably higher conversion than that in conventional solid-bed reactors is achieved owing to the temperature profile being much closer to the optimal one (decreasing when the gas approaches the outlet of the reactor), while in the conventional reactors there is a monotonic rise in temperature along the reactor pass. The results obtained were similar to those occurring in the reverse flow reactors of Matros, but without the necessity of inconvenient switching of the gas flow, and with none of its drawbacks. Comparing the types of reactors discussed, the idea of internal heat regeneration of Matrosʹ reactor was replaced by internal heat recuperation. During laboratory experiments of SO2 oxidation, for inlet concentrations of 2.3–3.3 % and inlet gas temperatures between 150 and 250 °C, a stable conversion of 95–98% was achieved. Later in the paper the pilot plant investigations are described. The construction of the reactor improves autothermal conditions of the reaction for low reactant concentrations. It seems to be advantageous not only for low-concentration SO2 oxidation but for catalytic oxidation of toxic organic compounds or for any other reaction where problems with autothermal operation can occur.