Process for working up municipal plastic waste materials by gasification

A process for gasifying municipal plastic waste material comprising the steps of:

• a) compressing and heating a plurality of plastic waste material pieces of about 20 mm piece size in a screw extruder at a pressure of from 40 to 80 bar until at a temperature of from 230.degree. to 300.degree. C. to produce an HCl-containing gas and a heated and compressed plastic waste material containing less than 3000 mg of HCl per kg of said plastic waste materials pieces, said plastic waste material pieces being purified and freed of metallic components prior to said compressing and heating;
• b) washing the HCl-containing gas produced during the compressing and heating step a) in a counterflow with water in an absorber to produce a hydrochloric acid solution;
• c) further heating the heated and compressed plastic waste material containing less than 3000 mg of HCl per kg of said plastic waste materials pieces in a heating vessel until at a temperature of from 400.degree. to 500.degree. C. to form a plastic melt having a viscosity of less than 300 cSt;
• d) gasifying the plastic melt formed in step c) in a gasification reactor at a pressure of 4 bar with oxygen in a flame reaction to form a crude gas in a gasification chamber having a central temperature of about 1600.degree. C., a carbon content of the plastic melt being substantially converted to CO in the crude gas;
• e) withdrawing said crude gas from said gasification reactor at a temperature of from 1300.degree. to 1600.degree. C. and directly cooling until at a temperature of said crude gas is from 700.degree. to 900.degree. C. by quenching;
• f) after performing step e), further cooling said crude gas by indirect heat transfer in a heat exchanger producing steam until at a temperature of from 220.degree. to 300.degree. C.;
• g) dry dedusting the crude gas cooled in step f) until said crude gas has a dust content of less than 20 mg/Nm.sup.3 of the crude gas;
• h) after the dry dedusting of step g), subsequently performing a water wash of said crude gas to remove gaseous impurities and residual dust from said crude gas;
• and
• i) after performing the water wash of step h), desulfurizing the crude gas to form a purified gas.