method for hydrothermal carbonization of sludge in chemical pulp mills

摘要

A method and system for the treatment of sludge in a chemical pulp mill including a step of hydrothermal carbonization (HTC) of a sludge stream, wherein said sludge stream is fed into a HTC arrangement and subjected to elevated temperature and pressure, producing at least one solids fraction, at least one liquid fraction, and at least one gaseous fraction; wherein said solids fraction is fed to a power boiler of said pulp mill and burned to generate steam; said liquid fraction is combined with weak black liquor from the pulp mill and fed to a black liquor evaporator of said pulp mill, and the resulting concentrated black liquor is burned in a recovery boiler of said pulp mill.