Method and apparatus for cooling solid particles under high temperature and pressure

An apparatus for cooling hot ash particles discharged from a fluidized bed reactor, wherein the ash particles are under pressure, the apparatus comprising:

• a vessel having a housing;
• a solids inlet;
• a plurality of cooling pipes housed inside the vessel, wherein the cooling pipe comprises an inner pipe and an outer pipe connected via an annular region between the inner pipe and the outer pipe, wherein the cooling liquid from outside of the vessel flows through an inlet of the inner pipe via the annular region and then the outer pipe before exiting the vessel, or through an inlet of the outer pipe via the annular region and then the inner pipe before exits the vessel;
• a solids outlet, and
• a header which is located outside the housing of the vessel, is connected to a source of cooling fluid, and is connected to the cooling pipes via a flow path;
• wherein the cooling pipes are connected to the header, and are arranged such that the ash particles can flow between the cooling pipes under gravity without being blocked by the header;
• and
• wherein the cooling fluid flows from the header via the flow path through the cooling pipes, and exchanges heat with the hot ash particles through walls of the cooling pipes.