A baffle for a fluid collection portion of a thermal transfer device can include a body having an inner perimeter, an outer perimeter, and an asymmetric feature, where the asymmetric feature is configured to create a pressure drop within the fluid collection portion of the thermal transfer device. The inner perimeter can be configured to be at least as large as an inner surface of a first wall that forms the fluid collection portion of the thermal transfer device. The outer perimeter can be configured to be no larger than an outer surface of a second wall that forms the fluid collection portion of the thermal transfer device.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A baffle for a thermal transfer device can include a body having a multiple first apertures that traverse therethrough, where each first aperture has a first outer perimeter that includes a first base shape and at least one first protrusion extending from the first base shape. Each of the first apertures is configured to receive a tube. The first base shape of each first aperture has a first shape and a first size that is configured to be substantially the same as the first shape and the first size of an end of a tube.

A gas-fired atmospheric pressure steam humidifier having high efficiency and ultra-low NOx(3) emissions is disclosed. In some examples, the gas-fired humidifier can have an efficiency of greater than 90 percent and a NOx(3) output of less than 20 parts per million (ppm). In one aspect, the humidifier includes a secondary heat exchanger having a first heat exchange section for pre-heating combustion air and a separate second heat exchange section for pre-heating make-up water, wherein the first and second heat exchange sections are in heat transfer communication with exhaust gases generated by the gas-fired burner and combustion blower assembly. In some examples, the first heat exchange section includes orifices for enabling flue gas recirculation.

A gas-fired atmospheric pressure steam humidifier having high efficiency and ultra-low NOx(3) emissions is disclosed. In some examples, the gas-fired humidifier can have an efficiency of greater than 90 percent and a NOx(3) output of less than 20 parts per million (ppm). In one aspect, the humidifier includes a secondary heat exchanger having a first heat exchange section for pre-heating combustion air and a separate second heat exchange section for pre-heating make-up water, wherein the first and second heat exchange sections are in heat transfer communication with exhaust gases generated by the gas-fired burner and combustion blower assembly. In some examples, the first heat exchange section includes orifices for enabling flue gas recirculation.

Disclosed is a heat exchange tube of waste heat boiler, which includes a tube body. The outer surface of the tube body is sprayed with a layer of anti-corrosion coating. The components of the anti-corrosion coating are Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2. On the surface of nano anti-corrosion coating, HF reacts with Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2 to form AlF.sub.3 and Ca.sub.5(PO.sub.4).sub.3F, which are tightly wrapped on the surface of the coating, thereby effectively preventing HF from corroding the interior of the coating and the heat exchange tube. Meanwhile, due to the anti-corrosion coating with the specific composition of the present disclosure, the heat exchange tube of the present disclosure can be resistant to fluorine corrosion at a high temperature of 600° C. or more, and can be used at a rather high temperature of 1000° C. or more.

Disclosed is a heat exchange tube of waste heat boiler, which includes a tube body. The outer surface of the tube body is sprayed with a layer of anti-corrosion coating. The components of the anti-corrosion coating are Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2. On the surface of nano anti-corrosion coating, HF reacts with Al.sub.2O.sub.3, CaAl.sub.2O.sub.4 and Ca.sub.3(PO.sub.4).sub.2 to form AlF.sub.3 and Ca.sub.5(PO.sub.4).sub.3F, which are tightly wrapped on the surface of the coating, thereby effectively preventing HF from corroding the interior of the coating and the heat exchange tube. Meanwhile, due to the anti-corrosion coating with the specific composition of the present disclosure, the heat exchange tube of the present disclosure can be resistant to fluorine corrosion at a high temperature of 600° C. or more, and can be used at a rather high temperature of 1000° C. or more.

Boiler systems having convection sections containing a set of boiler tubes having boiler tube inserts, boiler tubes for use in the convection section of a boiler system, and boiler tube inserts for boiler tubes for use in the convection section of a boiler system are provided herein. The boiler tube inserts are positioned in a first section of each boiler tube, where the first section extends from a front tube end the receives combustion gases from a furnace. The first section of the boiler tubes can be a plain tube section, and the boiler tubes can have a second section that includes a finned structure. The boiler tube inserts can be helical and can be made of a ceramic material.