The invention provides a two-stage upflow process for coal gasification. An oxygen-containing gas and a first increment of a coal-in-water slurry are ignited in a horizontal fired sagging reactor by means of horizontal coaxial juxtaposed burner nozzles mounted in the reactor, thereby converting the oxygen, the coal, and the water into steam and gaseous combustion products. The discharge from the fired reactor is contacted overhead with a second increment of coal-water slurry in a vertical unfired heat-recovery unit connected to the upper end of the reactor. The heat evolved in the reactor is used in the heat recovery unit to convert the second increment of coal-water slurry into more steam, char and synthesis gas. The gas effluent is separated from the solid char, and synthesis gas is recovered as the desired fuel-rich product. The solid char is reslurried and recycled to the fired reactor for further combustion. |