In an exhaust duct and a boiler, there are provided: a flue gas duct through which flue gases pass; a first hopper provided to the flue gas duct, the first hopper collecting PA in the flue gases; a low-repulsion section provided to the upstream side or the downstream side of the first hopper in the direction of flow of the flue gases, the low-repulsion section having a lower coefficient of repulsion than the inner wall surface of the flue gas duct; and a popcorn-ash-trapping section for trapping PA in the flue gases, the popcorn-ash-trapping section provided to the downstream side of the first hopper and the low-repulsion section in the direction of flow of the flue gases, whereby it is possible for solid particles in the flue gases to be properly trapped.

A lean burn combustion source includes a first side stream comprising an inlet and an outlet, both positioned downstream of a furnace and upstream of a particulate control device, and a second side stream comprising: an inlet positioned downstream of the particulate control device and upstream of the catalyst, a heat exchanger section passing through the first side stream, whereby heat from hot exhaust gas flowing through the first side stream is transferred to hot exhaust gas flowing through the second side stream, an injector positioned in the second side stream injecting aqueous based reagent into the hot exhaust gas flowing through the second side stream such that the aqueous based reagent decomposes to ammonia gas, and an outlet in fluid communication with a reagent distribution device positioned in the primary exhaust gas stream downstream of the particulate control device and upstream of the catalyst.

An atmospheric gas water heater includes a burner assembly. The burner assembly includes a burner having a body, and a screen member coupled to the body. A conduit is fluidly connected to the body. The conduit has an open end configured to receive gas and air. The flow of gas and air from the open end through the conduit to the body and past the screen member is defined as a downstream direction. The screen member defines a zone of combustion. The gas and the air is 100% premixed together upstream of the zone of combustion. The body of the burner has a first segment extending between a first end and a second end, and second and third segments extending from the first segment. The second segment and the third segment extend parallel to and spaced apart from each other to form a U-shape.

Provided is a duct wall surface structure which, in a flue of an iron-sheet duct with a hopper through which a solid-gas two-phase stream flows, can enhance the solid particle trapping efficiency of the hopper and reduce the outflow of the solid particles to the duct downstream side. The duct wall surface structure of a flue (10) through which a solid-gas two-phase stream containing large-diameter ash (50) flows includes a first hopper (20A) installed at the lower end of a first vertical flue section (12), installed in such a direction that the stream has a vertical component of velocity, to collect the large-diameter ash (50) from the stream, wherein a low-rebound part (60) having a lower coefficient of restitution than an iron sheet is provided on an inclined surface (21), with which the large-diameter ash (50) collides, on the upstream side in the flow direction from the first hopper (20A).

In an exhaust duct and a boiler, there are provided: a flue gas duct through which flue gases pass; a first hopper provided to the flue gas duct, the first hopper collecting PA in the flue gases; a low-repulsion section provided to the upstream side or the downstream side of the first hopper in the direction of flow of the flue gases, the low-repulsion section having a lower coefficient of repulsion than the inner wall surface of the flue gas duct; and a popcorn-ash-trapping section for trapping PA in the flue gases, the popcorn-ash-trapping section provided to the downstream side of the first hopper and the low-repulsion section in the direction of flow of the flue gases, whereby it is possible for solid particles in the flue gases to be properly trapped.

A method is provided for separating offgas from solid and/or liquid reaction products in the combustion of a metal M selected from alkali metals, alkaline earth metals, Al and Zn, and mixtures thereof, with a combustion gas. In a reaction step, the combustion gas is combusted with the metal M, forming offgas and further solid and/or liquid reaction products, and, in a separation step, the offgas is separated from the solid and/or liquid reaction products. In the separation step, a carrier gas is additionally added and the carrier gas is removed as a mixture with the offgas.