What material is suitable for the air preheater in a heating furnace?

Could the experts from Beijing Jialongpu plate-type air preheaters please explain the characteristics of your products?； For the low-temperature section, glass air preheaters are used – could you share your experience with their performance? ； Someone who has used Liyang Special Steel air preheaters in the low-temperature section, please share the results; someone from Gansu Lanke who has used them in the high-temperature section, please share as well. Other people too, please share their experiences, and let’s discuss together measures to improve the efficiency of use of these heating furnaces.

Corrosion needs to be taken into account for air preheating; corten steel should be used

Cordovan steel is used in the high-temperature section, while enamel tubes are used in the low-temperature section

We specialize in the production of air preheaters, in various types; QQ461157901 Zhang

May I ask: What are the compositional elements of Corden steel? Ceramic is used in the low-temperature section; is the heat transfer efficiency of ceramic higher than that of cast iron fins?

Coten steel, also known as weathering steel, is a term used abroad to refer to this type of material. It is primarily used in economizers, air preheaters, heat exchangers, and evaporators that operate in flue gases with high sulfur content; it offers excellent resistance to corrosion caused by sulfur ions due to its ability to prevent dew formation in such flue gases. ND steel, also known as steel of the 09CrCuSb material type (that is, 09 chromium copper antimony). Product features: It is primarily used in economizers, air preheaters, heat exchangers, and evaporators that operate in flue gases with high sulfur content; it offers excellent resistance to sulfur ions and corrosion, thereby preventing corrosion caused by dew formation in such flue gases. The products include steel plates, seamless steel pipes, fin strips, and tubes. Steel plates: 3mm–20mm. Tubes: Φ10–89mm, either seamless or welded tubes, as well as spiral finned tubes. Steel strips with fins: b12–164mm, with a thickness of 1–2mm. Main chemical components: C – carbon; Si – silicon; Mn – manganese; Cr – chromium; Ni – nickel. Limits: ≤0.12, 0.2–0.4, 0.35–0.65, 0.5–1.25 respectively; ≤0.35 for Cu – copper; Sb – antimony; P – phosphorus; S – sulfur. Limits: 0.25–0.45 for Cu, ≤0.12 for Sb, ≤0.035 for P. Yield strength: ≥310. Tensile strength: ≥450. Elongation: ≥25 (actual value can reach ≥38)

Enameled tubes are primarily used for corrosion protection; they can effectively resist corrosion caused by low-temperature dew points. Other materials rely solely on their thickness to provide an additional layer of protection against corrosion. The heat transfer coefficient of enamel tubes is also good

The heat transfer coefficient of cast iron is higher than that of enamel-coated tubes, but cast iron heat exchangers are heavier and require more material.

It is the year 2018, and after several years of observation, I would like to offer the original poster a few suggestions: calculate properly the areas affected by high and low temperatures, control the transition temperatures carefully, and avoid letting them get close to the dew point temperature of the flue gases； 1. Kautengang and ND steel are both weather-resistant steels; they are not resistant to acids. In simple terms, they prevent rusting but do not provide corrosion protection ； 2. 304 is even less resistant to acids than carbon steel; 316 is resistant to naphthenic acids but not to inorganic acids present in flue gases ； 3. If you have enough money, you can buy steel of nickel-based 825 or higher grade, which is resistant to acids ； So for normal high-temperature applications, carbon steel is sufficient; once the temperature exceeds 340°C, switching to 304 is appropriate. Low-temperature section: 1. Enameled tubes – those without pores are acceptable, but at present in China, even the best manufacturers such as Hengtao cannot produce tubes without pores ； 2. Cast iron: It can be considered if the desulfurization effect throughout the plant is good and the flue gas temperature remains above 130 degrees, though it tends to accumulate dust easily ； 3. Glass: resistant to corrosion and dust accumulation, but there are few manufacturers in China