Patent ID: 8088336

Claim:
A reducing gas generator for generating reducing gas including ammonia from a solid reductant formed in a columnar shape having a generally constant cross-section perpendicular to a central axis along an axial length of the solid reductant, the generator comprising: a heat-generating portion that includes a heat-generating surface opposed to a lower surface of the solid reductant in a vertical direction thereof and in contact with an entire region of the lower surface; and a heating element that heats the heat-generating surface when energized, so that the solid reductant is heated and decomposed to generate the reducing gas; a solid reductant receiving portion, which receives the solid reductant such that an axial direction of the solid reductant is perpendicular to the heat-generating surface and that a contact position between the solid reductant and the heat-generating surface is maintained, wherein: the solid reductant receiving portion is formed in a cylindrical shape; the solid reductant receiving portion having a side wall and a bottom wall which are formed at least in part from a porous body, through which the reducing gas permeates; an air-tight pressure vessel container disposed around the solid reductant receiving portion, wherein the reducing gas, which is generated when the solid reductant is heated by the heat-generating portion, is stored in the container; a reducing gas lead-out hole formed at an upper portion of the container and conducting reducing gas out of the container; a ventilation passage formed between the solid reductant receiving portion and an inner wall of the container for conducting reducing gas into the reducing gas lead-out hole; and ventilation means allowing reducing gas generated at a contact surface between the solid reductant and the heat-generating surface to flow into the ventilation passage through the side and bottom walls of the solid reductant receiving portion.