The present invention relates generally to the converting of organic waste materials into clean fuels and other useful products, and more particularly to a novel method and apparatus for obtaining liquid and gaseous hydrocarbons and a solid carbonaceous material from used rubber tires, from industrial waste containing relatively large amounts of plastic material, and from residential trash or waste.
At the present time, there is considerable concern in all highly industrialized countries regarding the disposal problems occasioned by the accumulation of large quantities of used automobile tires, industrial waste and residential trash . . . the latter two containing appreciable amounts of nondegradable plastic materials. In previous years, such waste materials were disposed of primarily by burning, but the enactment of air-pollution laws in most major countries now prohibit this method of disposal.
Also, at the present time, many of the so-called oil-consuming countries are concerned about the increased cost an unavailability of imported petroleum, and the dwindling supplies of natural gas.
Because of the aforementioned problems, there has been and now is an increased interest in the converting of used rubber tires, industrial plastic waste, and residential trash (including ordinary garbage) into products which can be used to produce heat or as the feed stock for various industrial processes.
The extraction of hydrocarbon materials from organic waste by the use of high temperatures has been known for many years. However, the known processes and apparatus have serious disadvantages. For example, gradual heating of the waste materials to the desired temperature results in cross-chemical reactions of the reactants and products, and the loss of useful products.
Also, the use of atmospheric and above-atmospheric pressures in the heating vessel causes the gases and vapors to slowly diffuse through the solid mass of materials and to thereby cause side reactions and cross-reactions among product species, which results in a very inefficient conversion process.
And, the prolonged heating of the gases and vapor products in the heating vessel causes recombinations, repolymerizations, and condensation of some of the products, which results in the formation of high molecular weight tars and hydrocarbons and thereby reduces the yield of the useful products. In addition, some of these high molecular weight tars and hydrocarbons form surface coatings on the feed materials and thereby block the release of new gases and vapors from the unreacted feed materials.
With the aforementioned problems and the limitations and deficiencies of known apparatus and methods in mind, it is a general object of the present invention to provide a novel method and apparatus for converting organic waste materials into clean fuels and other useful hydrocarbon products. More particularly, one of the primary objects is to provide a novel method and apparatus for obtaining useful hydrocarbon products from used rubber tires, from industrial plastic waste, and from residential trash.
Another object is to provide a novel method and apparatus for obtaining a hydrocarbon feed stock for petrochemical plants, from used rubber tires and from waste plastic materials.
Yet another object of the present invention is to provide a simple, continuous, and relatively inexpensive process for obtaining pipeline quality gas and oil from used rubber tires, from waste plastic materials, and from residential trash.
A further object is to provide a novel method and apparatus for obtaining from used rubber tires and waste plastic materials, a carbonaceous char which can be readily converted to activated carbon, or used as a smokeless fuel, or used as an asphalt and chemical filler.
I have discovered that the above objects and advantages are achieved by continuously moving a mass of shredded rubber tires, waste plastic materials, or residential trash (including ordinary garbage) through an elongated tubular member maintained at a temperature of between about 800.degree. F. and 1500.degree. F. throughout its length, in the absence of air and/or oxygen, with the material being turned or stirred as it passes through the tubular member, and with the gases and vapors being removed from adjacent the outlet end of said member by means of a vacuum of from about four inches to about six inches of mercury. To increase the production rate, a plurality of such tubular members can be provided in the same heating vessel in a side-by-side relationship, and/or the diameter of the tubular members can be increased in size with accompanying provisions for maintaining a substantially constant temperature throughout the mass of material being processed.
Based upon present information, it appears that the relatively high temperature adjacent the inlet of the tubular member (and throughout its length) and the constant stirring or turning of the material so as to continuously expose it to the heated surface or surfaces of the tubular member, causes the gases and vapors to literally "explode" from the material, and the relatively high vacuum throughout the length of the tubular member causes the vapors and gases to be quickly withdrawn before they can repolymerize or condense onto the feed material.