Method and apparatus for reclaiming oil from waste plastic

A method for reclaiming oil from waste plastic by means of pyrolysis, comprising:

• a dechlorination process to heat said waste plastic to a temperature of approximately 250-350.degree. C. by mixing with heated sand and optionally an additive agent, resulting in an admixture of substantially dechlorinated waste plastic and sand;
• a pyrolysis process to heat said admixture of substantially dechlorinated waste plastic and sand by mixing with said heated sand and optionally an additive agent to a temperature of approximately 350-500.degree. C., resulting in gaseous pyrolysis mixture products of gaseous high and low-boiling point oils and low molecular-weight gas, and a residual mixture product of solid residue and sand;
• a first gas/liquid separation process to separate said gaseous pyrolysis mixture products obtained by said pyrolysis process into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas, and to recirculate said liquid high-boiling point oil to said pyrolysis process;
• a second gas/liquid separation process to separate said gaseous low-boiling point oil and low molecular-weight gas into liquid low-point oil and low molecular-weight gas;
• and
• an incineration process to incinerate said residual mixture products of solid residue and sand obtained by said pyrolysis process, and said low molecular-weight gas obtained by said second gas/liquid separation process on a fluidized bed using pneumatically circulated sand as a medium, or on a high-speed circulation fluidized bed resulting in a heated sand, and to recirculate a portion of said heated sand to said dechlorination process and said pyrolysis process.

A method for reclaiming oil from waste plastic by means of pyrolysis which comprises a pyrolysis process in which said waste plastic is mixed with heated sand and optionally an additive agent, directly heated to a temperature of 350-500.degree. C. and maintained at said temperature until said pyrolysis occurs, further comprising a separation process, said separation process comprising:

• a first gas/liquid separation process to separate gaseous pyrolysis mixture products obtained by said pyrolysis process into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas, and to recirculate said liquid high-boiling point oil to said pyrolysis process;
• and
• a second gas/liquid separation process to separate said gaseous low-boiling point oil and low molecular-weight gas into liquid low-boiling point oil and low molecular-weight gas, which is connected in series with said first gas/liquid separation process;
• wherein said first gas/liquid separation process comprises a gas/liquid interfacial unit and a liquid dispersion unit for dispersing a liquid, said liquid dispersion unit being located above said gas/liquid interfacial unit, and said liquid supplied to said liquid dispersion unit is the liquid low-boiling point oil separated in said second gas/liquid separation process which has been cooled.

An apparatus for reclaiming oil from waste plastic, which comprises a pyrolysis device for mixing waste plastic which is substantially free of chlorine compounds, either as a result of preprocessing or because of the original composition of said waste plastic, with heated sand and optionally an additive agent, and heating to a temperature of 350-500.degree. C., resulting in formation of pyrolysis products comprising gaseous high and low-boiling point oils and low molecular-weight gas and a solid residue, further comprising:

• a first gas/liquid separation device to separate said pyrolysis products obtained by said pyrolysis device into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas, and to recirculate said liquid high-boiling point oil to said pyrolysis process;
• and
• a second gas/liquid separation device to separate said gaseous low-boiling point oil and low molecular-weight gas into liquid low-boiling point oil and low molecular-weight gas, which is connected in sequence to said first gas/liquid separation device;
• wherein said second gas/liquid separation device comprises a tower with a plurality of gas/liquid interfacial units arranged in said tower, and conducts said gaseous low-boiling point oil and low molecular-weight gas obtained in said first gas/liquid separation device between said plurality of gas/liquid interfacial units.

An apparatus for reclaiming oil from waste plastic, comprising:

• a dechlorination device to heat said waste plastic to a temperature of approximately 250-350.degree. C., resulting in an admixture of substantially dechlorinated waste plastic;
• a pyrolysis device to heat said admixture of substantially dechlorinated waste plastic by mixing with heated sand and optionally an additive agent to a temperature of approximately 350-500.degree. C., resulting in gaseous pyrolysis mixture products of gaseous high and low-boiling point oils and low molecular-weight gas, and a residual mixture product of solid residue and sand;
• a first gas/liquid separation device to separate said gaseous pyrolysis mixture products obtained by said pyrolysis process into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas, and to recirculate said liquid high-boiling point oil to said pyrolysis device;
• and
• a second gas/liquid separation device to separate said gaseous low-boiling point oil and low molecular-weight gas into liquid low-boiling point oil and low molecular-weight gas which is connected in series with the first gas/liquid separation device;
• wherein chlorine-rich gas exhausted from said dechlorination device or a residue of said chlorine-rich gas from which chlorine compounds have been removed is conducted to an entry port of said second gas/liquid separation device.

An apparatus for reclaiming oil from waste plastic, comprising:

• a pyrolysis device comprising a mechanical agitation device for agitating and conveying said waste plastic and heated sand from an upstream portion to a downstream portion of said pyrolysis device, whereby a gaseous pyrolysis mixture products of gaseous high and low-boiling point oils and low molecular-weight gas, and a solid residue of pyrolysis are formed;
• and
• a gas/liquid separation device to separate said gaseous pyrolysis mixture products obtained by said pyrolysis device into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas, and to recirculate said liquid high-boiling point oil to said pyrolysis device;
• wherein at least one line which conducts said gaseous pyrolysis mixture products to said gas/liquid separation device is connected to said downstream portion of said pyrolysis device, and a line which circulates said high-boiling point oil to said pyrolysis device is connected to said upstream portion of said pyrolysis device.

An apparatus for reclaiming oil from waste plastic, comprising:

• a mechanical agitation device which mixes said waste plastic with heated sand and conveys the resulting admixture horizontally from an upstream portion of said apparatus to a downstream portion of said apparatus while allowing a top region of said upstream and downstream portions to remain free to contain gaseous products,
• wherein said top region of said mechanical agitation device is partitioned between upstream and downstream regions, and said upstream region is provided with a first exhaust path, and said downstream region is provided with a second exhaust path;
• said upstream portion of said mechanical agitation device is kept between 250 and 350.degree. C., and said downstream portion is kept between 350 and 500.degree. C.;
• and said upstream portion of said mechanical agitation device dechlorinates said admixture, and said downstream portion pyrolyzes the dechlorinated admixture, resulting in gaseous pyrolysis mixture products of gaseous high and low-boiling point oils and low molecular-weight gas, and a solid pyrolysis residue.