Waste-gas piping for a filter dust melting furnace

A waste gas piping for a melting furnace which includes a furnace vessel made of a fireproof material and thermal insulation at least in a region of a furnace top, the waste gas piping comprising:

• a central waste gas pipe;
• a first pipe surrounding said central waste gas pipe, with a first annular space between said central waste gas pipe and said first pipe;
• a second pipe surrounding said first pipe, with a second annular space between said first pipe and said second pipe;
• a third pipe surrounding said second pipe, with a third annular space between said second pipe and said third pipe;
• an annular gap disposed at a furnace-side end of said waste gas piping, said annular gap providing communication between said first annular space and an interior of said central waste gas pipe;
• means for supplying a cold quenching air to said first annular space such that said cold quenching air cools a portion of said central waste gas pipe and is fed through said first annular space to said annular gap to provide a quench location in a region of said annular gap to quench a waste gas flowing into said central waste gas pipe;
• and
• means for supplying a cooling liquid into said second annular gap and for collecting the cooling liquid from said third annular gap such that the cooling liquid flows in the second annular gap to a location adjacent the annular gap and such that the cooling liquid flows away from said location adjacent the annular gap through said third annular space.