Patent ID: 8767794

Claim:
A low temperature melting furnace using an external cooling passage, the low temperature melting furnace comprising: a wall comprising a plurality of side-by-side metal sectors, each metal sector having an upper end portion, a lower end portion and a cooling passage formed therein, the cooling passage extending straight between the upper end portion and the lower end portion of the metal sector; a plurality of first extension tubes placed outside the wall, each first extension tube corresponding to a different one of the metal sectors and including a first connection portion extending outwardly from the upper end portion of the corresponding metal sector, a first parallel portion extending in parallel to the corresponding metal sector from the first connection portion towards the lower end portion of the corresponding metal sector, and an inlet extending from an end of the first parallel portion; and a plurality of second extension tubes, each second extension tube corresponding to a different one of the metal sectors and including a second connection portion extending outwardly from the lower end portion of the corresponding metal sector, a second parallel portion extending in parallel to the corresponding metal sector from an end of the second connection portion towards an opposite direction of the upper end portion of the corresponding metal sector, and an outlet extending from the second parallel portion.