Reduced Waste Production
Waste material is generated at all stages of pulping. One of the waste-products produced is paper sludge, which tends to be dried and then disposed of at a landfill, or burnt as a fuel source. However the former creates waste-disposal costs while the latter is inefficient as a fuel source, requiring coal or other fossil fuels to be burnt along-side it which leads to creating climate change emissions. One solution to this problem is to convert paper sludge into hydrogen gas through super-critical water gasification, in order to use it as an environmentally-friendly fuel source for a pulp mill.
Introduction
Components
Reactor – creates extreme temperatures and pressures to put the moisture in pulp/paper sludge in its ‘super- critical’ state.
Heat exchange – prepares reactor output for gas/liquid separation and reactor input for gasification by transferring heat from the former to the latter.
Liquid/Gas separator – uses gravity and filters to split the gas/liquid mixture into separate products.
The SCWG process places sludge under extreme temperature and pressure conditions, at and above the ‘critical’ temperature/pressure of water. This transforms the moisture present in the sludge into a state which reacts with the sludge’s biological components, producing hydrogen gas and miscellaneous chemicals, which are then placed in separate storage, either of which can be used to produce heat/electricity in other parts of the mill. This allows the mill to use less fossil fuels and send less waste to landfills, improving its environmental impact.
Written by: Christie O'Conner