A hydrothermal liquefaction (HTL) system has a biomass slurry flow path with a first pump and a first heat exchanger network downstream of the first pump. The first heat exchanger network includes plurality of heat exchangers in a parallel, series, and/or series-parallel flow arrangement. The biomass slurry flow path extends through cold flow sides of the heat exchangers of the first heat exchanger network. The biomass slurry flow path includes a second pump downstream of the first heat exchanger network, and a second heat exchanger network downstream of the second pump. The biomass slurry flow path extends through cold flow sides of the heat exchangers of the second heat exchanger network. A hydrothermal liquefaction (HTL) reactor is downstream of the second heat exchanger network. Heat transfer liquid in a heat transfer liquid circuit flows through hot flow sides of the heat exchangers of the second heat exchanger network.

There is described a pyrolysis system for converting carboneous materials into biochar including a kiln, a retort, and a gas recovery system including a combustor supplying hot air to the kiln, a conduit fluidly connected between the retort and the combustor, the conduit conveying the pyrolysis gas and residues from a chamber of the retort to the combustor, and a filter cartridge fluidly connecting the chamber of the retort to the conduit for filtering the pyrolysis gas and the residues conveyed from the chamber of the retort to the combustor, the filter cartridge removably located inside the conduit and extending at least partially inside the chamber of the retort. Methods for operating the pyrolysis system are also described. The pyrolysis system and methods described herein produce biochar with improved resistance to self-heating.

There is described a pyrolysis system for converting carboneous materials into biochar including a kiln, a retort, and a gas recovery system including a combustor supplying hot air to the kiln, a conduit fluidly connected between the retort and the combustor, the conduit conveying the pyrolysis gas and residues from a chamber of the retort to the combustor, and a filter cartridge fluidly connecting the chamber of the retort to the conduit for filtering the pyrolysis gas and the residues conveyed from the chamber of the retort to the combustor, the filter cartridge removably located inside the conduit and extending at least partially inside the chamber of the retort. Methods for operating the pyrolysis system are also described. The pyrolysis system and methods described herein produce biochar with improved resistance to self-heating.