Method and apparatus for reclaiming oil from waste plastic
First Claim
1. A method for reclaiming oil by pyrolysis from waste plastic including vinyl chloride and any other type of plastic containing chlorine compounds, comprising:
- a dechlorination process comprising heating said waste plastic to temperature of 250-350°
C. by mixing with heated sand or optionally an additive agent while said waste plastic is conveyed forward in a continuous stream, resulting in an admixture of substantially dechlorinated waste plastic and sand; and
a pyrolysis process comprising directly heating said admixture of substantially dechlorinated waste plastic and sand by itself or by mixing with heated sand or an additive agent, and maintaining said dechlorinated waste plastic at a temperature of 350-500°
C. resulting in pyrolyzed products.
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Abstract
This invention provides a method for reclaiming oil from waste plastic in such a way that thermosetting resins and solid foreign matter in the plastic will not pose a problem. This method greatly reduces the burden of presorting the garbage or industrial waste. To achieve this objective when oil is to be reclaimed from a waste plastic containing chlorine compounds, such as vinyl chloride, the plastic must first be stripped of chlorine. Prior to pyrolysis, while being conveyed forward in a continuous stream, the plastic is mixed with heated sand and/or an additive agent to raise its temperature to 250-350° C. This creates a product which is comprised of a mixture of sand and substantially dechlorinated plastic. The product is mixed with heated sand to heat it directly to a temperature of 350-500° C. It is maintained at this temperature until pyrolysis occurs. In order to obtain high-quality oil with a low boiling point, a first gas/liquid separation process separates the product obtained from the aforesaid pyrolysis into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gases, and recirculates the liquid high-boiling point oil to the pyrolysis process, and a second gas/liquid separation process separates the gaseous low-boiling point oil and low molecular-weight gases into liquid low-boiling point oil and low molecular-weight gases. The first and second gas/liquid separation process are connected in sequence.
55 Citations
5 Claims
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1. A method for reclaiming oil by pyrolysis from waste plastic including vinyl chloride and any other type of plastic containing chlorine compounds, comprising:
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a dechlorination process comprising heating said waste plastic to temperature of 250-350°
C. by mixing with heated sand or optionally an additive agent while said waste plastic is conveyed forward in a continuous stream, resulting in an admixture of substantially dechlorinated waste plastic and sand; and
a pyrolysis process comprising directly heating said admixture of substantially dechlorinated waste plastic and sand by itself or by mixing with heated sand or an additive agent, and maintaining said dechlorinated waste plastic at a temperature of 350-500°
C. resulting in pyrolyzed products.- View Dependent Claims (2, 3, 4)
separating products obtained by said pyrolysis into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas, and recirculating said liquid high-boiling point oil to a preceding pyrolysis process in a first gas/liquid separation process; and
separating said gaseous low-boiling point oil and low molecular-weight gas into liquid low-point oil and low molecular-weight gas in a second gas/liquid separation process which is connected in sequence to said first gas/liquid separation process.
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3. A method for reclaiming oil from waste plastic by pyrolysis according to claim 1, comprising:
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conducting gaseous pyrolysis mixture products obtained by said pyrolysis process to a gas/liquid separation process in which a cooling process is located above a gas/liquid interfacial process;
separating said gaseous pyrolysis mixture products into liquid high-boiling point oil, gaseous low-boiling point oil and low molecular-weight gas; and
recirculating said liquid high-boiling point oil to said pyrolysis process.
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4. A method for reclaiming oil from waste plastic by pyrolysis according to claim 1, wherein said dechlorination process and said pyrolysis process are carried out in separate vessels.
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5. A method for reclaiming oil from waste plastic by pyrolysis, comprising:
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a dechlorination process to heat said waste plastic to a temperature of approximately 250-350°
C. by mixing with heated sand, 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 heated sand alone or by mixing with heated sand and a synthetic or natural zeolite to a temperature of approximately 350-500°
C., resulting in gaseous pyrolysis mixture products of gaseous high and low-boiling point oils and low molecular-weight gas, and a residue 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 residue 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.
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Specification