A pressure control system is provided. The pressure control system includes a first pressure sensing device configured to obtain a first pressure measurement including at least one of a first differential pressure and a first pressure, the first pressure measurement obtained from at least one of within and downstream from a solids supply system, a second pressure sensing device configured to obtain a second pressure measurement including at least one of a second differential pressure and a second pressure within the solids supply system, and a pressure controller configured to use the first pressure measurement and the second pressure measurement to control a pressure within the solids supply system.

A system includes a syngas cooler and a compatible seal gas system. The syngas cooler may be configured to cool a syngas. The compatible seal gas system may be configured to supply a compatible seal gas to a seal of the syngas cooler. The seal may be configured to block the syngas from a passage between an outer wall of the syngas cooler and a tube cage of the syngas cooler.

Methods and systems are provided for the conversion of waste plastics into various useful downstream recycle-content products. More particularly, the present system and method involves pyrolyzing one or more waste plastics into various pyrolysis products, including a carbon solids-containing pyrolysis residue, and then subjecting the pyrolysis residue to partial oxidation gasification to thereby form a syngas composition.