For steam tubes used in thermal power plant,the inner and outer walls were operated in high-temperature steam and flue gas environments respectively.In this study,structure,microstructure and chemical composition of o...For steam tubes used in thermal power plant,the inner and outer walls were operated in high-temperature steam and flue gas environments respectively.In this study,structure,microstructure and chemical composition of oxide films on inner and outer walls of exservice low Cr ferritic steel G102 tube and exservice high Cr ferritic steel T91 tube were analyzed.The oxide film was composed of outer oxide layer,inner oxide layer and internal oxidation zone.The outer oxide layer on the original surface of tube had a porous structure containing Fe oxides formed by diffusion and oxidation of Fe.More specially,the outer oxide layer formed in flue gas environment would mix with coal combustion products during the growth process.The inner oxide layer below the original surface of tube was made of Fe–Cr spinel.The internal oxidation zone was believed to be the precursor stage of inner oxide layer.The formation of internal oxidation zone was due to O diffusing along grain boundaries to form oxide.There were Fe–Cr–Si oxides discontinuously distributed along grain boundaries in the internal oxidation zone of G102,while there were Fe–Cr oxides continuously distributed along grain boundaries in that of T91.展开更多
An equation model for calculating the adiabatic temperature of the wet-bulb thermometer has been obtained empirical fit through a meteorological database, specificly a trough relative humidity and air temperature. A c...An equation model for calculating the adiabatic temperature of the wet-bulb thermometer has been obtained empirical fit through a meteorological database, specificly a trough relative humidity and air temperature. A comparison of the results of calculations with the use of this equation and from meteorological database was made. The model deducted of the comparison is valid for a dry bulb temperature range of 3°C to 35°C and for relative humidity percentage in a range of 7% to 97%. Normalized errors are less than 5.5%. It means a maximum variation of 0.55°C from data. However, this variation from error represents only 3.6% of the data sample. The equation model was satisfactory.展开更多
Combustion-generated hydrogen chloride （HCl） is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual...Combustion-generated hydrogen chloride （HCl） is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual-layer granular bed filter, at gas temperatures of 500℃-700℃ and n（Ca）/n（Cl）molar ratios of 1.0-5.0 using the silver nitrate titration method by dry adsorbent powders Ca（OH）2. Mainly, the adsorption efficiency of HCI and utilization efficiency of Calcium were studied, by varying relevant factors including n（Ca）/n（Cl）, tempera- ture, feeding method, water vapor and CO2. With a relatively higher HCl concentration of 1000ppm, the experimental results revealed that 600℃ may be the optimum temperature for HCl adsorption when optimum n （Ca）/n（Cl） was 2.5 in our tests. The results also demonstrated that the feeding at a constant pressure was more effective, and the HCl adsorption efficiency could rapidly reach over 90% with n（Ca）/n（Cl） = 2.5 at 600℃. Furthermore, the HCl adsorption efficiency was found to be slightly promoted by water vapor, while could be impeded by CO2, and the utilization efficiency of calcium could be up to 74.4% without CO2, while was only 36.8% with CO2 when n（Ca）/n（Cl） was 2.5 at 600℃.展开更多
基金supported by the National Natural Science Foundation of China (Nos.51901113 and 51775300)the State Key Laboratory of Tribology in Tsinghua University, and the State Key Lab of Advanced Welding and Joining in Harbin Institute of Technology (No.AWJ-21M03)。
文摘For steam tubes used in thermal power plant,the inner and outer walls were operated in high-temperature steam and flue gas environments respectively.In this study,structure,microstructure and chemical composition of oxide films on inner and outer walls of exservice low Cr ferritic steel G102 tube and exservice high Cr ferritic steel T91 tube were analyzed.The oxide film was composed of outer oxide layer,inner oxide layer and internal oxidation zone.The outer oxide layer on the original surface of tube had a porous structure containing Fe oxides formed by diffusion and oxidation of Fe.More specially,the outer oxide layer formed in flue gas environment would mix with coal combustion products during the growth process.The inner oxide layer below the original surface of tube was made of Fe–Cr spinel.The internal oxidation zone was believed to be the precursor stage of inner oxide layer.The formation of internal oxidation zone was due to O diffusing along grain boundaries to form oxide.There were Fe–Cr–Si oxides discontinuously distributed along grain boundaries in the internal oxidation zone of G102,while there were Fe–Cr oxides continuously distributed along grain boundaries in that of T91.
文摘An equation model for calculating the adiabatic temperature of the wet-bulb thermometer has been obtained empirical fit through a meteorological database, specificly a trough relative humidity and air temperature. A comparison of the results of calculations with the use of this equation and from meteorological database was made. The model deducted of the comparison is valid for a dry bulb temperature range of 3°C to 35°C and for relative humidity percentage in a range of 7% to 97%. Normalized errors are less than 5.5%. It means a maximum variation of 0.55°C from data. However, this variation from error represents only 3.6% of the data sample. The equation model was satisfactory.
文摘Combustion-generated hydrogen chloride （HCl） is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual-layer granular bed filter, at gas temperatures of 500℃-700℃ and n（Ca）/n（Cl）molar ratios of 1.0-5.0 using the silver nitrate titration method by dry adsorbent powders Ca（OH）2. Mainly, the adsorption efficiency of HCI and utilization efficiency of Calcium were studied, by varying relevant factors including n（Ca）/n（Cl）, tempera- ture, feeding method, water vapor and CO2. With a relatively higher HCl concentration of 1000ppm, the experimental results revealed that 600℃ may be the optimum temperature for HCl adsorption when optimum n （Ca）/n（Cl） was 2.5 in our tests. The results also demonstrated that the feeding at a constant pressure was more effective, and the HCl adsorption efficiency could rapidly reach over 90% with n（Ca）/n（Cl） = 2.5 at 600℃. Furthermore, the HCl adsorption efficiency was found to be slightly promoted by water vapor, while could be impeded by CO2, and the utilization efficiency of calcium could be up to 74.4% without CO2, while was only 36.8% with CO2 when n（Ca）/n（Cl） was 2.5 at 600℃.
