Method and apparatus for removing coarse unentrained char particles from the second stage of a two-stage coal gasifier

A process for the two stage gasification of coal comprising:

• passing recycled char upwardly through a first zone and reacting said char therein with superheated steam and oxygen to yield a first stage synthesis gas comprising hydrogen and oxides of carbon,
• passing the first stage synthesis gas from the first zone through a mixing zone having a cross sectional area substantially less than the cross sectional area of the first zone,
• injecting coal and superheated steam into said mixing zone and mixing said coal and superheated steam with the first stage synthesis gas passing therethrough,
• passing the mixture of steam, coal and first stage synthesis gas from the mixing zone into a second gasification zone,
• passing the mixture of coal, steam and first stage synthesis gas upwardly through the second zone while reacting the mixture to yield a second zone product comprising agglomerated char, and char entrained in a second zone product gas comprising methane, hydrogen and oxides of carbon,
• withdrawing the second zone product entrained char and second zone product gas together;
• separately withdrawing the second zone product aggolomerated char through an exit passageway which opens into the bottom of said mixing zone against a counter-current of steam,
• controlling the velocity and direction of flow of said counter-current of steam to prevent the exit of non-agglomerated char particles and to cool the said agglomerated char as it leaves the second stage through said exit passage, and
• recycling the separated agglomerated char to the first gasification zone.