Numerical simulation of multi-phase flows studying a proposed method for the prevention of adhesion on inner surfaces of combustion system exhaust ducts

摘要

A numerical simulation was made to study a proposed method for preventing the adhesion of exhaust gas constituents on the inner walls of combustion system (incinerator, melting furnace, waste recovery reactor, etc.) exhaust ducts, caused by phase changes of molten salts. The proposed method features the injection of air for constituting a layer of air inside a duct for the prevention of adhesion. Analyses were made on exhaust gases which contained molten salt mist and vapor. The distribution of flow velocity, concentration and distribution of molten salt vapor as well as the behavior of mist inside exhaust ducts were analyzed and the results used for devising optimal conditions for maintaining a layer of air for the prevention of the said adhesion. It was revealed that injecting air without any swirling components was effective for adhesion prevention. An optimal flow rate of air for maintaining a maximum length of the prevention layer was also found. Another finding was that making the air supplying slit as wide as permissible was effective for adhesion prevention.