Anti-corrosion for desulfurization chimney flues
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May I ask: What is an economical and durable method for anti-corrosion of the flue gas ducts in coal powder boilers? The original flue is made of Q235-A material with a thickness of 5 mm; it was put into use in April 2007. The new desulfurization system was installed in March 2010. The flue gas contains a high level of moisture; under normal operating conditions, the temperature of the flue gas is 50 degrees, while under abnormal conditions it rises to around 150 degrees. The main components of the flue gas are SO2 and nitrogen oxides, and the pH of the exhaust gases is around 5. The flue has been suffering from corrosion and perforations since June 2010; about 3 square meters have already been repaired. The wall thickness there has decreased significantly, and the flue is scheduled to be replaced. Dear sea friends, what material is best for flue ducts? In terms of carbon steel, what material should be used for corrosion protection in the flue? (There are support pipes in the horizontal flue, spaced 70 centimeters apart)
Currently, carbon steel coated with glass flake is widely used in domestic power plants, while Hastelloy lining is more common abroad.
After curing, glass flake materials tend to be brittle, and they have poor temperature resistance properties (including resistance to high temperatures and temperature shocks). As a result, the flake lining is prone to cracking and delamination under high-temperature conditions or exposure to temperature shocks. The temperature in the flue of our facility varies greatly, and we are concerned that the glass flake coating may crack or delaminate. Can cast stone coating be sprayed inside?
The poster’s question is the same as ours; I’m asking the same thing
This post was last edited by yuchenchf on 2011-11-8 08:01. Thermal spray anti-corrosion and wear-resistant alloy coatings can solve the aforementioned problems. Feel free to contact me if needed. . QQ504279846。
This post was last edited by Litaotao1314 on 2011-5-1 at 13:48. A lining made of glass flake resin mortar should still be used; taking accident scenarios into account, the original flue can also be covered with high-temperature flakes. Considering vibrations in the flue, the flakes should not be too thick – 1.5–1.8 mm is sufficient. The flue should be equipped with additional supports and reinforcing ribs. Imported scales resin is selected. Our company, Jiangsu Kaiyuan Environmental Protection Technology Engineering Co., Ltd., produces the raw materials for scale mortar: scales from Nippon Glass, and resin from Showa in Japan. The construction team has gone to Japan for further training. Many desulfurization projects have been carried out, and they are operating well.
This post was last edited by Litaotao1314 on 2011-5-1 at 13:48. Our company provides Bohu coatings made from polymer composite materials. It has good performance and a long lifespan. Good value for money.
This post was last edited by Litaotao1314 on 2011-5-1 at 13:48. Glass scales are brittle materials that are sensitive to changes in temperature; you can consider using vitrified ceramic tiles for anti-corrosion purposes, as they can effectively resist the thermal stresses caused by temperature changes
The last edit to this post was made by Litaotao1314 on 2011-5-1 at 13:48. Considering cost-effectiveness and overall performance, it is recommended to use scale mortar lining for protection; however, the areas of the flue that are subject to vibration should be reinforced with FRP composites； If the chimney has a concrete structural base, a layer of acid- and heat-resistant mortar should be placed between the scale mortar and the base, serving to repair, level the surface, and act as a transition layer ； There are now also integral fiberglass chimneys; although their cost is 20%-30% higher, they offer better timing and performance.
This post was last edited by Litaotao1314 on 2011-5-1 at 13:49. There are many materials available for anti-corrosion of flues. Traditional methods usually involve the use of glass flakes, which are relatively inexpensive; however, the lifespan of these flakes is a concern. Ceramic coatings are recommended, with pure ceramic coatings being the best option. But this raises another issue: the ceramic coating cannot be too thick. If wear in the flue is not severe, ceramic coatings are a good choice for protection. Their price is slightly higher than that of glass flakes, but their resistance to aging is much greater. If pure ceramic coatings are not sufficient, composite ceramic coatings can be used, as they allow for a thicker coating layer. The requirements for anti-corrosion in chimneys are similar to those in flues. If wear is a concern, composite ceramic coatings are the best choice. I work at the Power Research Institute of Huadian Group, specializing in this field. If you’re interested, feel free to contact me so we can work together to make progress
Our company has also developed anti-corrosion solutions using ceramic powder for flue systems; however, to address cracking at the base layer, it is necessary to use phenolic resin flakes of our brand KF-A81 as a primer, followed by applying a layer of ceramic powder of grade KF-B83 on top of A81. The effect is pretty good. This solution generally requires such reinforcement at the flue gas inlet, the outlet of the booster fan, and the spray section of the absorption tower. Ceramic powder coatings primarily provide wear resistance and impact resistance. The rigid reinforcement of the flue, the scale material, and the quality of the primer applied before phosphating all determine the quality of the final anti-corrosion treatment.