煤焦油的腐蚀性评价试验研究

Experimental study on corrosion evaluation of coal tar

煤焦油中的杂质含量较高,容易对后续加氢处理装置中的设备和管线造成腐蚀。通过腐蚀挂片试验,开展针对煤焦油的腐蚀性评价试验研究,试验结果表明:当温度为180~240℃时,煤焦油中Q245R钢的腐蚀速率不大于0.16 mm/a,当温度高于240℃后,腐蚀速率急剧增大,260℃时腐蚀速率已超过0.5 mm/a;对于304,304L,316L和317L来说,在180~320℃的煤焦油中材料腐蚀轻微,腐蚀速率均低于0.005 mm/a。Q245R钢的腐蚀速率和煤焦油的酸值均在240℃和300℃出现拐点,其腐蚀速率与酸值存在明确的关联,即与酸值存在正相关性。根据腐蚀评价试验结果,在180~240℃范围内加工煤焦油时,可以使用Q245R钢;温度高于240℃,为避免由于材料腐蚀速率较大引起相关管道或设备的失效造成事故而影响正常的安全生产,原则上不推荐使用Q245R钢,建议使用304或内衬304以上材质。

The high content of impurities in coal tar leads to the corrosion of equipment and pipelines in the subsequent hydrotreating unit.So corrosion evaluation test of coal tar was carried out through coupon test in laboratory.The results showed the corrosion rate of 20 R was less than 0.16 mm/a in the range of 180~240℃;when the temperature was higher than 240℃,the corrosion rate increased sharply and exceeded 0.5 mm/a at 260℃;for 304,304 L,316 L and 317 L,the corrosion rates were lower than 0.005 mm/a in the range of 180~320℃.Moreover,both the corrosion rates of 20 R steel and the acid value of coal tar showed inflection points at 240℃and 300℃,and there was a clear corresponding relationship between the change of corrosion rate and acid value,that is,a positive correlation.According to the results of corrosion evaluation test,in order to avoid accidents caused by the failure of relevant pipelines or equipment due to the high corrosion rate of materials,20 R carbon steel could be used when processing coal tar in the range of 180~240℃;in principle,20 R steel was not suggested when the temperature was higher than 240℃,thus 304 or above lining material was recommended.