Device for treating, in particular cooling, bulk material using a gas

A device for treating bulk material with a gas, the device comprising a grate through which gas can flow from an under-grate space to an upper side and which is configured to convey the bulk material in a conveying direction from a loading end to a discharge end, wherein the grate comprises a plurality of mutually adjacent rows, each row comprising at least one bar that is elongate in the conveying direction and is configured to be moved alternately back and forth in the conveying direction, wherein the grate is configured to be controlled such that the forward stroke of the at least one bar of two adjacent rows takes place at the same time and the rearward stroke of the at least one bar of two adjacent rows takes place at different times, wherein the grate includes, in the conveying direction on at least one side, a row of at least one unmoving adapter for increasing the grate width, and wherein gas can flow through the at least one adapter from the under-grate space to the upper side.