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煤制天然气是我国煤炭清洁利用的重要发展方向.现有管道用于输送煤制天然气(最高氢分压为0.72 MPa)时需要考虑其中低压氢气的影响,因而需先进行氢致开裂安全性评估.本文利用高压釜环境下恒载荷实验和电化学充氢,模拟研究X-70管线钢和20#钢在不同氢含量下的氢损伤和氢致延迟开裂,并对其在煤制天然气中服役安全性进行评估.在总压12MPa(10 MPa N_2+2 MPa H_2)的高压釜中放置一个月,两种钢的金相试样均不出现氢损伤,U弯试样不开裂,加屈服强度σs的恒载荷试样不发生断裂.在含0.72 MPa的煤制天然气中长期服役时,进入两种钢的氢含量均远低于σs下发生氢致延迟开裂的门槛氢含量和出现氢损伤的门槛氢含量,因而X-70钢和20#钢在煤制天然气中长期服役均具有高的氢损伤和氢致开裂安全系数.
Coal-based natural gas is an important development direction for the clean utilization of coal in China. Existing pipelines need to consider the effect of low-pressure hydrogen when transporting natural gas (the maximum hydrogen partial pressure is 0.72 MPa), so hydrogen-induced cracking safety assessment In this paper, the hydrogen damage and hydrogen induced delayed cracking of X-70 pipeline steel and 20 # steel under different hydrogen content were simulated by constant load test and electrochemical hydrogen charging in autoclave, and their service on coal natural gas Safety evaluation was carried out.After being placed in an autoclave with a total pressure of 12 MPa (10 MPa N 2 +2 MPa H 2) for one month, no hydrogen damage was observed on the metallurgical samples of both steels and the U-bend specimens were not cracked and the yield strength σs constant load specimens are not broken.When the long-term service of natural gas containing 0.72 MPa of coal, the hydrogen content of both steels is far lower than the stenciling hydrogen content caused by delayed hydrogen cracking caused by σs and hydrogen damage Threshold hydrogen content, so X-70 steel and 20 # steel in the long-term service of natural gas in coal have high hydrogen damage and hydrogen induced cracking safety factor.