A boiler system having a series of boilers. Each boiler includes a shell having an upstream end, a downstream end, and a hollow interior. The boilers also have an oxidizer inlet entering the hollow interior adjacent the upstream end of the shell and a fuel nozzle positioned adjacent the upstream end of the shell for introducing fuel into the hollow interior of the shell. Each boiler includes a flue duct connected to the shell adjacent the downstream end for transporting flue gas from the hollow interior. Oxygen is delivered to the oxidizer inlet of the first boiler in the series. Flue gas from the immediately preceding boiler in the series is delivered through the oxidizer inlet of each boiler subsequent to the first boiler in the series.

The invention provides a hydrogen boiler based on coal gasification and water decomposition, including a steam boiler which includes an upper furnace and a lower furnace; water and steam in the upper furnace are respectively communicated with water and steam in the lower furnace; and the steam boiler is provided with a casing which has a narrow gap for containing water and a wide wall for heating to generate gas. The steam boiler contains multistage reactors. A coal modification and gasification device is provided at an outer side of the steam boiler and is provided with two chambers. The steam and gasified gas of coal are mixed and enter the reactors for direct burning to promote respective reactions. After several stages of modification and decomposition, the steam and the gasified gas of coal are completely converted to hydrogen.

The invention provides a hydrogen boiler based on coal gasification and water decomposition, including a steam boiler which includes an upper furnace and a lower furnace; water and steam in the upper furnace are respectively communicated with water and steam in the lower furnace; and the steam boiler is provided with a casing which has a narrow gap for containing water and a wide wall for heating to generate gas. The steam boiler contains multistage reactors. A coal modification and gasification device is provided at an outer side of the steam boiler and is provided with two chambers. The steam and gasified gas of coal are mixed and enter the reactors for direct burning to promote respective reactions. After several stages of modification and decomposition, the steam and the gasified gas of coal are completely converted to hydrogen.

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.

A boiler is disclosed in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. A transition section is present between the lower furnace and the upper furnace. The boiler is a high temperature sub-critical natural circulation boiler which is completely top supported. The lower furnace is supported through the transition section by the upper furnace.

A boiler is disclosed in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. A transition section is present between the lower furnace and the upper furnace. The boiler is a high temperature sub-critical natural circulation boiler which is completely top supported. The lower furnace is supported through the transition section by the upper furnace.

A boiler is disclosed in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. The upper furnace and the convection pass are also located next to each other, so that they share a common steam-cooled wall. There is no open pass between the furnace and the convection pass.

A boiler is disclosed in which the furnace is divided into a lower furnace and an upper furnace. The lower furnace uses water-cooled membrane walls, while the upper furnace uses steam-cooled membrane walls that act as superheating surfaces. The upper furnace and the convection pass are also located next to each other, so that they share a common steam-cooled wall. There is no open pass between the furnace and the convection pass.