Production of synthesis gas from ash-rich hydrocarbons

Synthesis gas produced by partial oxidation (1) of high-ash hydrocarbons with the formation of from about 0.1 to about 0.3% by weight of soot (based on the carbon employed as hydrocarbon) is cooled first in a radiation cooler (2) and then in a convection cooler (3). The crude gas is then scrubbed in a wet-dust separator (6), and the scrubber water after filtration (10), optionally combined with the water phase of the radiation cooler (2), is returned to the gasification plant. Tbe water which has precipitated from the crude gas saturated with water vapour contains only traces of metals and metal compounds and can be fed directly to a water purification plant.