Methods and systems for a gasifier solids removal system are provided. The system includes a down flow combustor including an inlet and an outlet and a combustion zone extending therebetween, the combustor configured to direct a flow of process material including syngas, flowable slag, and particulates in a first downward direction, a plurality of flow passages in serial flow communication including a first flow passage and a second flow passage, wherein the process material flow reverses direction flowing from the first passage to the second passage, and a plurality of entrainment separation stages in serial flow communication with at least one of the plurality of flow passages.