Processes for converting waste plastics and waste plastic conversion plants

A process for converting waste plastic to hydrocarbons, the process comprising:

• heating, under dissolution conditions and in a dissolution unit, a waste plastic feed with a dissolution medium to form a dissolution product, the dissolution conditions comprising a temperature in a range from about 100° C. to about 200° C.;
• performing a solid-liquid separation on the dissolution product to separate a soluble component of the dissolution product from an insoluble component of the dissolution product;
• contacting, under depolymerization conditions, hydrocarbon polymers present in the soluble component with a depolymerization catalyst to form a depolymerization product effluent;
• separating the depolymerization product effluent into at least three fractions comprising:
• a first fraction comprising a C2-C4 hydrocarbon;
• a second fraction comprising a C5-11 hydrocarbon;
• and
• a third fraction comprising a C12+ hydrocarbon;
• and
• combining the third fraction with the waste plastic feed in the dissolution unit.

A plant for converting waste plastic, the plant comprising:

• a dissolution unit configured to heat a feed comprising waste plastic to provide a mixture comprising an insoluble component and a soluble component;
• a first separation unit configured to receive the mixture from the dissolution unit and to separate the mixture;
• a depolymerization reactor configured to receive the soluble component from the first separation unit and to contact the soluble component with a depolymerization catalyst under depolymerization conditions to form a depolymerization product effluent;
• a second separation unit configured to receive the depolymerization product effluent from the depolymerization reactor and to separate the depolymerization product effluent into a plurality of output streams;
• and
• a line configured to transfer a first output stream of the plurality of output streams to the dissolution unit, the first output stream comprising a C12+ hydrocarbon.