What type of high-temperature air preheater is appropriate?
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Waste incinerators are divided into two combustion zones: primary combustion and secondary combustion. The secondary combustion zone requires the supply of additional high-temperature air, in relatively small quantities. To maintain a high-temperature combustion condition of around 1100°C in this zone, the temperature of the secondary air should be close to that of the hot flue gases; otherwise, it will affect the normal high-temperature combustion process in the secondary combustion zone. Therefore, it is considered to directly install a high-temperature air preheater in the high-temperature flue gas at around 1000°C emitted from the incinerator to heat the secondary air. So, at such high temperatures, what type of high-temperature air preheater is more appropriate? What material should be used for high-temperature air preheaters? Please, fellow sailors, give me some advice.
A plate-type air preheater can be used, with heat-resistant stainless steel such as 253MA or 310S. The high-temperature resistant stainless steel plates/tubes used are of the type (0Cr25Ni20), which is in accordance with national standards for high-temperature resistant stainless steel. Its characteristics include suitability for manufacturing various components for furnaces; the maximum operating temperature is 1300 ℃, while the continuous operating temperature is 1150 ℃. Current air preheaters in China find it difficult to meet the requirements for air at such temperatures. It is recommended to adopt imported technology. If you have further requests, please send an email to nm-gyf@vip.sina.com
2Cr25Ni20: An oxidation-resistant steel capable of withstanding repeated heating up to 1035°C; used for furnace components, nozzles, and combustion chambers. 1Cr16Ni35: A steel grade with good resistance to carburization and nitridation, suitable for repeated heating up to 1035°C. Furnace steel 0Cr25Ni20: can withstand heating up to 1035°C. Materials for furnaces and automotive purification devices: 2Cr25Ni – exhibits strong resistance to high-temperature corrosion; stainless steel plates below 1082°C develop an oxidized scale that is prone to flaking off.
I would like to ask these two friends: can finned tubes made of ductile iron be used as flue gas heat exchange tubes? Thank you!
Cast iron can be used in air preheaters, but its operating temperature is limited. I. Gray cast iron: Gray cast iron is suitable for media such as water, steam, air, gas, and oils at temperatures ranging from –10°C to 200°C. Common grades of gray cast iron are: HT200, HT250, HT300, HT350. II. Malleable cast iron: Suitable for water, steam, air, and oil media at temperatures ranging from –30 to 300°C. Common grades include KTH300-06, KTH330-08, and KTH350-10. III. Ductile iron: Suitable for media such as water, steam, air, and oils at temperatures ranging from –30 to 350°C. Common grades include: QT400-15, QT450-10, QT500-7.