A gasifier system includes a gasifier chamber, a plurality of nozzles or burners injecting and combusting a mixture including coal and oxygen within the gasifier chamber, and an ash bed disposed proximate a bottom of the gasifier chamber. Concurrent flow is generated within the gasifier such that gas and bi-products generated by the combustion of the mixture flow through the ash bed. The ash bed serves as a filter and reducing volume for the trace carbon not gasified during the combustion process. The hot gases exit the gasifier and enter a gas cooler and then a hot gas filter. Ash is unloaded from the gasifier chamber and is transferred into a quench tank, where ash settles and is removed to atmospheric conditions by a progressive pitched dewatering screw press. The dewatering screw press also serves as a seal to prevent excessive water escaping from the high pressure of gasifier operation.