An evaporator system for an industrial boiler, containing a heat transfer system for generating a water-steam mixture, means for separating water and steam from the water-steam mixture and means for drying the separated wet steam, - wherein at least one horizontal vessel contains a required minimum amount of water, a relatively small steam volume and internals for the separation of water and wet-steam, - and wherein at least one vertical vessel contains internals for drying the wet steam to predetermined values by separating liquid from the wet-steam, - and wherein the at least one horizontal vessel and the at least one vertical vessel is connected to each other by at least one wet-steam piping through which separated wet-steam is transported from horizontal vessel to vertical vessel, - and wherein the at least one horizontal vessel has a connection to outlet conduits of an at least one evaporator heat transfer section of the heat transfer system for transporting a water-steam mixture from the at least one evaporator heat transfer section to the horizontal vessel, - and wherein the at least one horizontal vessel further has a connection to at least one downcomer conduit for transporting water from the at least one horizontal vessel back to inlet conduits of the at least one evaporator heat transfer section, - and wherein the at least one vertical vessel has a connection to at least one dry-steam piping for discharging dried steam out the vertical vessel, characterized in that the at least one vertical vessel has a connection to a liquid drain piping for transporting liquid from the at least one vertical vessel back to the inlet conduits of the at least one evaporator heat transfer section. - wherein at least one horizontal vessel contains a required minimum amount of water, a relatively small steam volume and internals for the separation of water and wet-steam, - and wherein at least one vertical vessel contains internals for drying the wet steam to predetermined values by separating liquid from the wet-steam, - and wherein the at least one horizontal vessel and the at least one vertical vessel is connected to each other by at least one wet-steam piping through which separated wet-steam is transported from horizontal vessel to vertical vessel, - and wherein the at least one horizontal vessel has a connection to outlet conduits of an at least one evaporator heat transfer section of the heat transfer system for transporting a water-steam mixture from the at least one evaporator heat transfer section to the horizontal vessel, - and wherein the at least one horizontal vessel further has a connection to at least one downcomer conduit for transporting water from the at least one horizontal vessel back to inlet conduits of the at least one evaporator heat transfer section, - and wherein the at least one vertical vessel has a connection to at least one dry-steam piping for discharging dried steam out the vertical vessel, characterized in that the at least one vertical vessel has a connection to a liquid drain piping for transporting liquid from the at least one vertical vessel back to the inlet conduits of the at least one evaporator heat transfer section.