Process and apparatus for preparing acetylene and synthesis gas

A process for preparing acetylene and synthesis gas by partial oxidation of at least one hydrocarbon with oxygen, by first separately preheating the starting gases comprising a hydrocarbon-comprising stream and an oxygen-comprising stream and then mixing them in a mixing zone and, after they have flowed through a burner block, reacting them in a firing space and then cooling the products rapidly, wherein the firing space interior wall is blanketed with a purge gas stream, this purge gas stream is introduced by means of a plurality of feed lines and each of these feed lines is configured in the interior of the firing space such that the alignment of the direction vector of the main flow of the purge gas stream introduced deviates from the alignment of the direction vector of the main flow direction of the gas stream supplied through the burner block by an angle of not more than 10°, and the feed lines at the exit orifice thereof have an opening width of 1/1000 to 3/100, of the firing space diameter, there being a multi-level supply of the purge gas stream at successive points viewed in relation to the main flow direction of the gas stream supplied through the burner block, and the free cross section of the firing space which is available to the gas stream leaving the burner block for flow through the firing space at the height of the feed lines of the purge gas stream being approximately constant.