Embodiments provide a combustion structure that can achieve stable combustion by addressing the aforementioned drawbacks in the prior art such as low flame stability, backfire, deflagration, blockage and/or any other drawbacks. The combustion chamber structure in accordance with the disclosure can include: a grate structure including a first set of elongated components, a fire retention structure including a second set of elongated components. The first set of first elongated components can be arranged along an axial direction within the combustion chamber structure. The second set of elongated components can be arranged along the axial direction in a same direction as the first elongated components. The second set of elongated components can be configured to generate a negative pressure zone within the combustion chamber. The first set of elongated components can form apertures that can be aligned with apertures formed by the second set of elongated components.

A package multiple pass flexible water tube boiler for converting water to steam. The boiler having an enclosure and diagonally offset upper and lower drums. The drums are connected by a series of staggered or offset water tubes. The water tubes comprise two sets of repeating tubes that are bent to substantially similar but not identical designs. The staggered tube arrangement optimizes heat transfer and minimizes the footprint of the unit.

An object of the present disclosure is to appropriately reduce NOx and CO. A boiler includes: a can body having water pipe; a burner for supplying primary fuel and air into the can body; a secondary fuel supply unit for supplying secondary fuel into the can body downstream of the burner in a flow direction of combustion gas; a cooling line for introducing a cooling fluid for reducing temperature of a predetermined space in the can body downstream of the burner in the flow direction of the combustion gas; a flow rate adjusting unit capable of adjusting a flow rate of the cooling fluid introduced into the can body from the cooling line; and a control unit for controlling the flow rate adjusting unit to control the flow rate of the cooling fluid such that the temperature of the predetermined space is 800 C. or more and 1200 C. or less.

An object of the present disclosure is to appropriately reduce NOx and CO. A boiler includes: a can body having water pipe; a burner for supplying primary fuel and air into the can body; a secondary fuel supply unit for supplying secondary fuel into the can body downstream of the burner in a flow direction of combustion gas; a cooling line for introducing a cooling fluid for reducing temperature of a predetermined space in the can body downstream of the burner in the flow direction of the combustion gas; a flow rate adjusting unit capable of adjusting a flow rate of the cooling fluid introduced into the can body from the cooling line; and a control unit for controlling the flow rate adjusting unit to control the flow rate of the cooling fluid such that the temperature of the predetermined space is 800 C. or more and 1200 C. or less.

Embodiments provide a combustion structure that can achieve stable combustion by addressing the aforementioned drawbacks in the prior art such as low flame stability, backfire, deflagration, blockage and/or any other drawbacks. The combustion chamber structure in accordance with the disclosure can include: a grate structure including a first set of elongated components, a fire retention structure including a second set of elongated components. The first set of first elongated components can be arranged along an axial direction within the combustion chamber structure. The second set of elongated components can be arranged along the axial direction in a same direction as the first elongated components. The second set of elongated components can be configured to generate a negative pressure zone within the combustion chamber. The first set of elongated components can form apertures that can be aligned with apertures formed by the second set of elongated components.

In an externally integrated steam generator type small modular reactor, a steam generator is arranged along the circumference of a reactor vessel cylindrical shell, and a steam drum is arranged along the circumference of the steam generator. The small modular reactor includes: a nuclear reactor including a hemispherical upper head, the reactor vessel cylindrical shell coupled to the upper head and extending downward from the upper head in a cylindrical shape, and a hemispherical lower head provided on a lower portion of the reactor vessel cylindrical shell, wherein a core is placed in the nuclear reactor; the steam generator surrounding all around the reactor vessel cylindrical shell and including a first penetration hole communicating with an inside of the nuclear reactor; and the steam drum surrounding the circumference of the steam generator and including a second penetration hole communicating with an inside of the steam generator.

In an externally integrated steam generator type small modular reactor, a steam generator is arranged along the circumference of a reactor vessel cylindrical shell, and a steam drum is arranged along the circumference of the steam generator. The small modular reactor includes: a nuclear reactor including a hemispherical upper head, the reactor vessel cylindrical shell coupled to the upper head and extending downward from the upper head in a cylindrical shape, and a hemispherical lower head provided on a lower portion of the reactor vessel cylindrical shell, wherein a core is placed in the nuclear reactor; the steam generator surrounding all around the reactor vessel cylindrical shell and including a first penetration hole communicating with an inside of the nuclear reactor; and the steam drum surrounding the circumference of the steam generator and including a second penetration hole communicating with an inside of the steam generator.

A boiler system and methods for heating a fluid are disclosed, in particular for heating water for producing steam. The boiler comprises an economizer module integrated on the top of a furnace, and is in communication with the furnace to receive heat and/or hot combustion gases therefrom. The economizer comprises tubes receiving the fluid, such as feedwater, to be pre-heated and providing it to the furnace comprising a combustion chamber producing heat and hot combustion gases. The fluid is pre-heated by circulating first through the pre-heating tube assembly of the economizer module before entering the furnace module where the fluid is further heated by the combustion chamber. Since the economizer is located on the furnace module, the boiler does not have a large footprint compared to a regular boiler system without an economizer. Due to the total integration of the economizer with the furnace, the boiler system has improved energy efficiency.

In an externally integrated steam generator type small modular reactor, a steam generator is arranged along the circumference of a reactor vessel cylindrical shell, and a steam drum is arranged along the circumference of the steam generator. The small modular reactor includes: a nuclear reactor including a hemispherical upper head, the reactor vessel cylindrical shell coupled to the upper head and extending downward from the upper head in a cylindrical shape, and a hemispherical lower head provided on a lower portion of the reactor vessel cylindrical shell, wherein a core is placed in the nuclear reactor; the steam generator surrounding all around the reactor vessel cylindrical shell and including a first penetration hole communicating with an inside of the nuclear reactor; and the steam drum surrounding the circumference of the steam generator and including a second penetration hole communicating with an inside of the steam generator.

In an externally integrated steam generator type small modular reactor, a steam generator is arranged along the circumference of a reactor vessel cylindrical shell, and a steam drum is arranged along the circumference of the steam generator. The small modular reactor includes: a nuclear reactor including a hemispherical upper head, the reactor vessel cylindrical shell coupled to the upper head and extending downward from the upper head in a cylindrical shape, and a hemispherical lower head provided on a lower portion of the reactor vessel cylindrical shell, wherein a core is placed in the nuclear reactor; the steam generator surrounding all around the reactor vessel cylindrical shell and including a first penetration hole communicating with an inside of the nuclear reactor; and the steam drum surrounding the circumference of the steam generator and including a second penetration hole communicating with an inside of the steam generator.