| According to the characteristics of corrosion and salt accumulation in blast furnace gas pressure recovery turbine unit, several efficient vapor phase corrosion inhibitors were systhesized, and series of great efficient corrosion and scale inhibitors for TRT were designed by optimizing the formulation.Morpholine series, urea amines, quaternary ammonium salts series vapor phase corrosion inhibitors were synthesized respectively by suitable experimental conditions. The results showed that the optimum synthesis conditions for 4-(N,N)-diisopropylamine methylmorpholine(DIPAM) were: the molar ratio of morpholine, diisopropylamine and formaldehyde was 1:1:1.2; the reaction temperature was 40℃; the reaction time was 5h; the mole of benzoic acid and morpholino was 1.5:1; the recrystallized synthetic product were white flaky crystals and the yield was 96.35%. The optimum synthesis conditions for 4-(N,N)-di-n-butyl amine methylmorpholine(DBM) were: the molar ratio of morpholine, di-n-butylamine and formaldehyde was 1:1.2:1.2; the reaction temperature was 60℃; the reaction time was 5 h; the product were white flaky crystal and the yield was 93.95%. The optimal synthesis conditions for 4-(N,N)-dicyclohexylamine methylmorpholine(DCHAM) were: the molar ratio of morpholine, dicyclohexylamine and formaldehyde was 1:1:1.2; the reaction temperature was 50℃; the reaction time was 5 h; the mole of hydrochloric acid and morpholine was 1.4:1; the product were white powdery solid and the yield up to 75.50%. The optimal synthesis conditions for Diisopropylamine dimethylurea(DMU) were: the molar ratio of urea, diisopropylamine and formaldehyde was 1:1:1.2; the reaction temperature was 80℃; the mole of hydrochloric acid and urea was 1.2:1. The product were white powder with yield of 90.83%. Cyclohexyl alkynoxymethyl benzyl quaternary ammonium salt(CABQAS) and octyl alkynoxymethyl benzyl quaternary ammonium salt(OABQAS) were synthesized by raw materials of paraformaldehyde, propiolic alcohol, organic amine, benzyl chloride and ethanol under nitrogen protection, toluene as carrying agent, the product were brownish red liquid.Cyclohexylamine, ethanolamine, propargyl alcohol, HPMA(Hydrolysed Polymaleic Anhydride) were chosen as the base component, complex to the key component that synthesized, and the methanol as solvent. Cyclohexylamine can be dissolved in water and organic solvents, be volatile with water vapor and absorbed carbon dioxide form carbonates; Ethanolamine has a strong ability to absorb acid gases; Propynol has good volatility and forms film fast, it can inhibit the acid, phosphoric acid, sulfuric acid, hydrochloric acid and other acidic substances corrosion iron, copper, nickel and other metal, it is widely used in the steel industry for rust inhibitor; The carboxyl group in HPMA molecule can form compounds with cation-salt in water, promote lattice distortion so that precipitation change into loose-flowing water residue, it can inhibit the formation of new scale and peeling old scale effect, which is an excellent scale inhibitor. The components of the composite inhibitor are small molecules with low vapor pressure, easily gasified and diffusion, which not only maximize the protective effect, but also not easy to clog pipes and valves.Static weight-loss method and polarization curve method were used to evaluate the corrosion inhibitor formulation, the results showed that the synthesis series inhibitors all had good inhibition effect. In DIPAM corrosion inhibitor formulation, the mass fraction of DIPAM was 10%, ethanolamine 30%, cyclohexylamine 10%, propargyl alcohol 10%, inhibition rate reached 100%. In DBM corrosion inhibitor formulation, the mass fraction of each component were DBM 9%, cyclohexylamine 15%, ethanolamine 15%, propargyl alcohol 10%, the inhibition rate was 98.46%. In DCHAM formulation, the mass fraction of each component were DCHAM 12%, cyclohexylamine 15%, ethanolamine 15%, propargyl alcohol 10%, the inhibition rate was 95.67%. In DMU formulation, the mass fraction of each component were cyclohexylamine 15%, ethanolamine 15%, propargyl alcohol 10%, DMU 15%, the inhibition rate was 97.61%. In ABQAS formulation, the mass fraction of ABQAS was 20%, the inhibition rate of CABQAS was 98.47%, the inhibition rate of OABQAS was 97.87%. Polarization curve method was used to evaluate the inhibitor formulations type, the results showed that the above-mentioned types of corrosion inhibitors made the corrosion potential of A3 coupon negative shift, indicating that those types of corrosion inhibitors mainly inhibited cathodic corrosion process, which means the corrosion inhibitors belonged to the cathodic polarization type volatile corrosion inhibitor.We developed a series of corrosion and scale inhibitor formulation by optimizing the experimental formula, the composition were: cyclohexylamine 15% to 25%(mass fraction, as below), ethanolamine 15% to 30%; morpholine salt 8% to 15%, urea ammonium salts 5% to 10%; alkynyl quaternary methylamine oxygen 5% to 10%, propargyl alcohol 8% to 15%; HPMA 8% to 15%; methanol remainder. The dynamic weight-loss method was used to evaluate the corrosion and scale inhibitors in the simulated blast furnace gas, which showed a great scale and corrosion inhibition effect, the corrosion inhibition rate achieved 90%.The series corrosion and scale inhibitors we designed in this paper have been generalized application in Shandong Rizhao Iron and Steel Group, Wuhan Iron and Steel Group Co. Ltd, Qianan Zhayi Steel Group Co. and other several companies. The corrosion inhibition rate and other indicators had reached the requirements, Wherein the gas drainage effluent p H value stable in the range of 5.0 to 6.0, reached p H≥5.0 protocol requirements; the corrosion rate was 72.6%, reached protocol requirements of inhibition rate over 65%; The average loss of wall thickness was 0.08mm/a, attained the requirements of an average thickness loss protocol less than 0.1mm; Test gas pipeline network in the dust content was much higher than the range of less than 10mg/m3 of in agreement. The bearing vibration value of TRT substantially maintain in the range of 20~26μm, unit overhaul cycle be doubled, tons of iron generating capacity by nearly 30%, which creating a good economic and social benefits, laying a good foundation technology process improvement and market development for the future. |
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