| Recently,the polymer sealant for using in fir type leaf root of blast furnace gas pressure recovery unit(TRT)exist some problems in the operation,including poor high temperature resistance,acid gas corrosion,and unconvenience in repairing and replacing the blade.Solving the problems above can avoid wasting a lot of energy and improve corporate earnings.In order to study the cause of sealant failure,firstly,we analyzed the physical and chemical properties,aging resistance and corrosion resistance of the sealant.The results show that the main reasons of sealing failure are poor temperature resistance and low bonding strength between the sealant and the substrate,which lead to acid condensate infiltration into the tongueand-groove.At present,there are a variety of high performance sealing materials on sale,however,only part of the conventional performance test results are announced by the sealant manufacturers on the market,which limits its coverage of application.Addressing these issues,this paper studied the heat resistance and corrosion resistance of TRT by analyzing the working conditions and simulating the use environment of TRT,aiming to screen out high-performance sealants that can meet the requirements of complex working conditions of TRT.TG-DSC and infrared analyzer were used to test the physical and chemical properties,corrosion resistance and aging resistance of epoxy and silicone sealants,and to analyze their applicability in fir-tree tenon grooves of TRT.Based on the experimental results,the following main conclusions are drawn.For epoxy resin sealant,the higher hardness after curing is the main reason,and it is not suitable for longterm operating at 200℃;for organic silicon sealant,it has good temperature resistance,while,its surface energy and solid content are too low.According to these results,we chose organosilicone coating with high solid content as TRT leaf root sealing material to research.The experimental results show that the fluidity,room temperature curing,surface drying time and actual dry time of the high solid silicone coating meet the requirements of operation.Surface drying time and actual dry time are 110 min,260 min,curing non-volatile content is 95.7%(mass fraction)and 67.7%(volume fraction),and the solid content after curing is higher in the same sealing products,to ensure the full sealing effect after curing.After 60 days of aging test and 30 days of corrosion test,little change of tensile shear strength proves that the high solid silicone coating has good performance and can be used for a long time under TRT service conditions.Combined with TG-DSC curve and infrared analysis of group changes before and after aging,the main reason for the high temperature resistance of the coating is the existence of Si-O-Si bond,and the addition of high temperature resistance filler in the high solid silicone coating.The disassembly results of the simulated parts before and after heat treatment show that the maximum disassembly force value decreases from 39 k N(before heat treatment)to11k N(after heat treatment).The heat treatment process provides a reasonable reference basis for the convenience of disassembly.Therefore,the high-solid silicone sealant overcomes the disadvantages of traditional sealants and meet the requirement of fir tree blade root. |
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