A gasification system for the oxidation of a carbonaceous feedstock to provide a synthesis gas comprising: a reactor chamber for oxidizing the carbonaceous feedstock; a quench section for holding a bath of liquid coolant; an intermediate section having a reactor outlet opening through which the synthesis gas is conducted from the reactor chamber into the bath of the quench section; at least one layer of refractory bricks arranged on the reactor chamber floor, the lower end section of the refractory bricks enclosing the reactor outlet opening and defining the inner diameter thereof; the intermediate section including a number of halved tubes for liquid coolant arranged onto at least part of the reactor chamber floor on a side thereof opposite to the lower end section of the refractory bricks; and a pump system for circulating the liquid coolant through the halved tubes on the reactor chamber floor.