Study Of High Temperature Anti-corrosion Coating On Heat Exchanger

The fouling caused by flue gas in the air preheater and dew point temperature of fume is a major problem in the actual project. How to prevent fouling and corrosion effectively is a problem worthy of study. Although using the corrosion-resistant stainless steel can prevent tubes of heat exchanger from corrosion, we have to pay a high cost of stainless steel and large investment of heat exchanger. If we spread a layer of coating which is corrosion-resistant and not stained ash on the tudes of the heat exchanger, we can not only solve the problem of fouling and corrosion but also cut down the cost of heat exchanger substantially.First of all, we use PTFE and PPS to create composite coating and the coating we have can meet the requirements of experiment in the area of adhesion, non-stick and heat resistance. However, the composite coating has poor corrosion resistance and can't prevent the erosion of sulfuric acid completely, because the melting PTFE has high viscosity and it will form microporous when it is solidified.As a result, we use silicone modified epoxy resin as raw material to make coatings. From the research we find that the epoxy resin which pluged in Silicone can keep its performance of corrosion resistance and at the same time, its heat resistance improved. There is no doubt that this new epoxy resin we have expand the scope of its use. This experiment selected a kind of orginicsilicon resin with reactive group as modifier of epoxy resin and studied in detail the synthesis of modified epoxy resin. We use IR to judge the situation of grafting reaction and determine the proportion of orginicsilicon resin and epoxy resin by the way of TGA and adhesion. Finally, we determine that unde appropriate temperature for several hours, when the proportion of orginicsilicon resin and epoxy resin is 8 to 2 and the amount ofcoupling agent is 1.5%, the synthesis of modified epoxy resin can be better.Through using the modified epoxy resin as raw material we can get the modified epoxy resin coating. The experiment pluses fluoro silicone to cut down the coating's surface tension, increase static contact angle and improve the coating's non-stick performance. In order to improve the coating's heat resistance, thermal conductivity and abrasion resistance, we add talcum, Graphite and PVDF in it. According to the comprehensive requirements about heat resistance and corrosion resistance of coating, we determine the amount of modified epoxy resin, fluoro silicone resin and filler. The coating's adhesion is 0, temperature capabilities is 250~300℃and the static contact angle with water is 103.3°. We can even keep the coating integral if we put it in the 8% sulfuric acid at room temperature with 20 days. The test of coating in the heat exchange shows that the heat transfer coefficient didn't decrease but increase.