US 5,498,827 AGranted

Hydrothermal treatment and partial oxidation of plastic materials

AssigneeTexaco Inc.

InventorsMotasimur R. Khan, Christine C. Albert, Stephen J. DeCanio

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Abstract

A process for upgrading plastic material containing inorganic filler or reinforcement material for use as feedstock in partial oxidation gas generator for the production of raw synthesis gas, fuel gas, or reducing gas. The plastic material is granulated and mixed with water to produce the plastic sludge. The plastic sludge is preheated at a temperature in the range of about 350.degree. F. to 475.degree. F. in the absence of air in a closed system. The preheated plastic sludge is then hydrothermally treated at a temperature in the range of about 450.degree. F. to 650.degree. F. at a pressure in the range of about 100 to 1200 psig and above the vapor pressure of water at that temperature. The hydrothermally treated plastic sludge is cooled, degassed, and mixed with ground solid carbonaceous fuel, e.g., coal and water, to produce a pumpable aqueous slurry having a solids content in the range of about 40 to 60 wt. %. The pumpable aqueous slurry is then reacted by partial oxidation to produce said synthesis gas, fuel gas, or reducing gas. In one embodiment, a portion of coal is mixed with the plastic sludge prior to the aforesaid preheating and hydrothermal steps.

Claims12

Dependent claims

A partial oxidation process for the environmentally safe disposal of scrap plastic material containing inorganic filler or reinforcement material, comprising:

(1) grinding the plastic material;
(2) mixing the plastic from (1) with water to produce a sludge having a solids content in the range of about 60 to 80 wt. %;
(3) heating the sludge from (2) for a period in the range of about 5 minutes to 1 hour at a temperature in the range of about 350.degree. F. to 475.degree. F. in the absence of air in a closed system;
(4) hydrothermally treating the heated sludge from (3) in a closed vessel in the absence of air for a residence time in the range of about 15 to 90 minutes, a temperature in the range of about 450.degree. F. to 680.degree. F., a pressure in the range of about 100 to 1200 psig and above the vapor pressure of water at that temperature;
(5) cooling the hydrothermally treated sludge from (4) to a temperature in the range of about 100.degree. F. to 200.degree. F., and separating the gases generated from said sludge, said gases containing at least one member selected from the group consisting of CO.sub.2, CO, H.sub.2 S, NH.sub.3, and light hydrocarbon gases;
(6) mixing the cooled sludge from (5) with ground solid carbonaceous fuel and water to produce a pumpable aqueous slurry having a solids content in the range of about 40 to 60 wt. % and a weight ratio of solid carbonaceous fuel to said sludge in the range of about 1 to 5 parts by wt. of solid carbonaceous fuel for each part by weight of said sludge;
and
(7) reacting by partial oxidation with a free-oxygen containing gas said pumpable aqueous slurry from (6) to produce a gas containing H.sub.2 and CO.

5 more elements

Dependencies are inferred from the claim text.