Energy Efficient Solids Feed System for High Pressure Processes

A new system for efficiently feeding solid fuels to high pressure processes has been developed over the course of this PhD study. The system, named the Hydraulic Lock Hopper (HLH), takes the form of a new lock hopper that utilises water as an incompressible fluid during the compression stage. It disposes of the need for inert gas or gas compressors as is required by conventional lock hopper systems, and vastly increases their operational efficiency. The HLH has demonstrated the feeding of a range of fuels including wood pellets, torrefied spruce pellets and ground anthracite grains to pressures as high as 25 barg. Two modes of operation have been developed, one whereby the energy requirement to feed is minimised (Mode 1), and another whereby the volume of high pressure gas vented to the atmosphere is reduced to near nil (Mode 2). In addition to this, the HLH has been developed to operate without the forward leakage of air in order to minimise explosive atmospheres.