Cooling device with coolant jets having a hollow cross section

A treatment line for a flat, elongate hot metal rolling stock, comprising:

• a finishing train for rolling the rolling stock;
• and
• a cooling device,
• wherein the cooling device is arranged upstream of the finishing train, is arranged downstream of the finishing train, or is arranged within the finishing train,
• wherein the cooling device comprises a first cooling bar which extends, as seen in a width direction (y) of the rolling stock, completely over the rolling stock,
• wherein the first cooling bar comprises a plurality of first coolant outlets facing the rolling stock, by means of which water is applied to the rolling stock,
• wherein the first coolant outlets are arranged in the first cooling bar so as to be positionally fixed in at least one row extending in the width direction (y) of the rolling stock, and have, within the respective row, a respective predetermined spacing (a1) from one another,
• wherein the first coolant outlets are full-jet nozzles, from which a full jet having a respective intrinsically continuous cross section exits during operation,
• wherein a jet opening angle of the full jet exiting from the full-jet nozzles is at most 5°,
• wherein the cross sections of the full jets each have a convex envelope, and
• the respective convex envelope contains at least one region, which is not contained in the respective full jet itself.