Effect of Reaction Temperature on Pickling of 430 Stainless Steel
stainless steel is used as raw material and pickling in HCl-based electrolytes is adopted, and the effect of pickling temperature on removal behavior of the oxide layer on stainless steel is systematically studied, study found that the oxide layer of stainless steel after heat treatment in the lab is composed of Fe2O3 and Cr2O3, at different temperatures, with the increasing of duration, corrosion potential of stainless steel after heat treatment shows fall followed by rise, and corrosion potential of stainless steel in 60°C is obvious higher than in 50 °C; with temperature increasing, the weight loss of stainless steel after pickling increase with large range, and the weight loss of the oxide layer of stainless steel increases as the duration increases.
A Study of the Scale Structure of Hot-Rolled Steel Strip by Simulated Coiling and Cooling
The morphological development of oxide scale on hot-rolled steel strip under various simulated coiling and cooling conditions was investigated. Oxide-scale structures developed were classified into several categories, and the conditions under which each category formed were identified and mapped. It was found that oxide scale formed under normal coiling and cooling conditions had a structure that was difficult to pickle. Increased cooling rate after coiling, or coiling at a temperature below 350°C, improved this structure. The conditions under which a magnetite layer at the wüstite–steel interface was formed during continuous cooling were also identified and the mechanisms of its formation discussed.
Full-scale measurements of SO2 gas phase concentrations and slurry compositions in a wet flue gas desulphurisation spray absorber
Abstract Two measurement campaigns were carried out at ENERGI E2's Asnaes Power plant, unit 5. The unit has a capacity of 620 MW e and is equipped with a wet flue gas desulphurisation (FGD) plant employing a counter-current spray absorber with five spray levels. In the first campaign, the power plant was firing Orimulsion ® with 2.85 wt% S resulting in a flue gas concentration of SO 2 exceeding 2000 ppmv. In the second campaign, the fuel applied was a low-S blended coal and the SO 2 concentration in the raw gas was around 400 ppmv. A novel probe for in situ sampling of gas phase concentrations in wet FGD spray absorbers was developed and applied for measuring axial profiles of the SO 2 gas phase concentrations in the absorber. The expected decrease in SO 2 concentrations along the height of the absorber was found in the spray section (from height 26.5 to 36.2 m) whereas the SO 2 concentration above the holding tank and below the gas inlet was quite low probably due to long local residence times in the region. Horizontal variations, due to somewhat different flow conditions near the column wall were investigated and the SO 2 concentrations were found to be higher near the wall. Measurements at different gross loads showed that the SO 2 gas phase concentration at a given position inside the absorber was roughly linearly related to the L/G ratio in the measuring interval. Turning off one of the lower spray levels, while burning coal with low S content, did not lower the overall removal efficiency of the absorber. However, the SO 2 gas phase concentration inside the lower part of the absorber was increased by a factor of 2–3. Measurements of slurry pH at different positions showed a decrease of approximately 0.5 units from the upper to the lower part of the absorber. The full-scale measurements provide a detailed set of experimental data for validation of mathematical models of a wet FGD spray absorber.