A heat recovery unit for generating a heated fluid by a hot exhaust gas includes a housing having an inlet for introducing hot exhaust gas and an outlet for discharging treated exhaust gas, and arranged in the housing at least one heat exchanger for heat exchange between the hot exhaust gas and a fluid, and an auxiliary combustor for combusting fuel with hot exhaust gas. The auxiliary combustor is provided with a fuel supply, which auxiliary combustor is arranged downstream of the at least one heat exchanger in the housing. An exhaust gas bypass for a part of the hot exhaust gas is provided, having an inlet for exhaust gas, and being positioned upstream of the at least one heat exchanger, and having an outlet in direct fluid communication with the auxiliary combustor.

A heat recovery unit for generating a heated fluid by a hot exhaust gas includes a housing having an inlet for introducing hot exhaust gas and an outlet for discharging treated exhaust gas, and arranged in the housing at least one heat exchanger for heat exchange between the hot exhaust gas and a fluid, and an auxiliary combustor for combusting fuel with hot exhaust gas. The auxiliary combustor is provided with a fuel supply, which auxiliary combustor is arranged downstream of the at least one heat exchanger in the housing. An exhaust gas bypass for a part of the hot exhaust gas is provided, having an inlet for exhaust gas, and being positioned upstream of the at least one heat exchanger, and having an outlet in direct fluid communication with the auxiliary combustor.

An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct including vertical flue gas channels, at least some of which are provided with heat recovery units for recovering heat from flue gases. The first flue gas channel downstream of the furnace is provided with a reheater and one of the following heat recovery units: an economizer or a boiler bank. The reheater and the second heat recovery unit are located one after the other in the horizontal incoming direction of the flue gas, so that in a flue gas channel the flue gas flows in a vertical direction from above downwards and heats the reheater and the second heat recovery unit simultaneously. The heat recovery elements of the reheater and the second heat recovery unit may be positioned side by side in a direction that is crosswise with respect to the horizontal incoming direction of the flue gas.

An arrangement in a recovery boiler having a furnace for combusting waste liquor and a flue gas duct including vertical flue gas channels, at least some of which are provided with heat recovery units for recovering heat from flue gases. The first flue gas channel downstream of the furnace is provided with a reheater and one of the following heat recovery units: an economizer or a boiler bank. The reheater and the second heat recovery unit are located one after the other in the horizontal incoming direction of the flue gas, so that in a flue gas channel the flue gas flows in a vertical direction from above downwards and heats the reheater and the second heat recovery unit simultaneously. The heat recovery elements of the reheater and the second heat recovery unit may be positioned side by side in a direction that is crosswise with respect to the horizontal incoming direction of the flue gas.

Disclosed herein is a once-through heat exchanger that includes a tube stack including a plurality of tubes, a plurality of heads connected to the tube stack via a connection module and configured to accommodate heated steam, the connector module comprising a plurality of tube connectors and configured to connect the tubes and the heads, and a manifold connected to the heads via a plurality of link pipes and configured to accommodate heated steam, wherein the connector module comprises a first tube connector and a second tube connector having different shapes.

Disclosed herein is a once-through heat exchanger that includes a tube stack including a plurality of tubes, a plurality of heads connected to the tube stack via a connection module and configured to accommodate heated steam, the connector module comprising a plurality of tube connectors and configured to connect the tubes and the heads, and a manifold connected to the heads via a plurality of link pipes and configured to accommodate heated steam, wherein the connector module comprises a first tube connector and a second tube connector having different shapes.

A segmented watertube boiler system allows for rapidly expanding the capacity of a boiler. The system joins boiler segments to form a boiler. The segments have portions of the boiler so that the storage capacity for water and heat are increased with the number of segments uses. Any openings in the segments on the ends are capped off and heat and water sources are attached. The boiler can be cleaned and maintained by simply disassembling the segments to provide access to the whole boiler.

A vertical heat recovery steam generator, the low-pressure stages of which are designed as a once-through system, having a condensate preheater with at least one condensate preheater heating surface, through which a flow medium flows and which is disposed in a hot gas channel through which hot gas flows, a low-pressure preheater with at least one low-pressure preheater heating surface through which the flow medium flows and which is disposed in the hot gas channel, and a low-pressure evaporator with at least one low-pressure evaporator heating surface through which the flow medium flows and which is disposed in the hot gas channel. The flow medium flows successively through the at least one low-pressure preheater heating surface and the at least one low-pressure evaporator heating surface in one pass and without additional pressure compensation.

In the case of a method for the heat treatment of erected, preferably large-area tube wall regions or tube wall segments, in particular of a diaphragm wall, of a steam generator, in particular of a power plant, in the installed state, it is sought to provide a solution which permits the use of steel types which are more problematic with regard to power plant operation with elevated steam parameters, in particular the steels T23 and T24, in the erection of steam generators. This is achieved in that the tube wall regions or tube wall segments for heat treatment are subjected, in the installed state in the steam generator, and in particular over a large area, to a stress-relief annealing process.

In the case of a method for the heat treatment of erected, preferably large-area tube wall regions or tube wall segments, in particular of a diaphragm wall, of a steam generator, in particular of a power plant, in the installed state, it is sought to provide a solution which permits the use of steel types which are more problematic with regard to power plant operation with elevated steam parameters, in particular the steels T23 and T24, in the erection of steam generators. This is achieved in that the tube wall regions or tube wall segments for heat treatment are subjected, in the installed state in the steam generator, and in particular over a large area, to a stress-relief annealing process.