Pipeline temperatures exceeding design limits aggravate pipeline corrosion
Thread Content
After investigation, it was determined that the "1·14" deflagration accident of Changlian Petrochemical Company was a general production safety accident. Direct cause of the accident 1. Direct cause of deflagration: The 90° elbow of the pressure pipe (250P2019CS-H) between the prehydrogenation reaction feed/product heat exchanger E202A-F of the catalytic reforming unit and the prehydrogenation product/dehydration tower feed heat exchanger E204AB is thinned due to corrosion After rupture (the burst opening is about 950mm × 620mm), the naphtha and hydrogen mixture under pressure inside (2.0MPa) is ejected and forms an explosive mixture with air. The friction between the ejected medium and the pipeline generates static sparks and triggers deflagration. 2. Reasons for the intensification and continuation of deflagration: Some nearby towers, pipelines and other equipment and facilities were damaged or ruptured to varying degrees under the continuous baking of high-temperature flames. The leaked combustible materials intensified the combustion and spread of the fire, causing two subsequent deflagrations. 3. The main cause of pressure pipeline rupture is abnormal corrosion of pipelines: (1) The accident pipeline continues to be in an acidic environment, aggravating pipeline corrosion ； (2) The pipeline temperature exceeds the design limit, aggravating pipeline corrosion.
After receiving the instruction to monitor whether the temperature of the pressure pipeline continued to rise, there was no organization to take effective measures to deal with the over-temperature operation of the accident pipeline in a timely manner. It also failed to report the relevant situation to Qin Jiazhong, the new deputy general manager and director of the Production Technology Department, to remind him to pay attention to the relevant situation and take effective measures to eliminate the hidden dangers of the accident. At the same time, they did not urge the laboratory team to implement the operating procedures, take effective preventive measures, and conduct acid and alkalinity testing and analysis on the water quality of the pre-hydrogenation high-mixing tank V202. As a result, the accident pipeline operated at excessive temperatures for a long time, which aggravated pipeline corrosion and became the main reason for the rupture of the accident pressure pipeline.
Was the original production director alert or just lucky? Resigned~ The deputy minister didn't understand the situation, didn't report it, and took the responsibility on his own, and something happened.~
Another important reason is that the technology for acidic water reuse is not up to standard and there is no online analysis.
3. The main cause of pressure pipeline rupture is abnormal corrosion of pipelines: (1) The accident pipeline continued to be in an acidic environment, aggravating pipeline corrosion. Changlian Petrochemical Company did not conduct continuous monitoring and analysis of the V202 acidic water in the pre-hydrogenated high-dividing tank (containing H2S, HCl, and NH3 produced by the pre-hydrogenation reaction) and continued to recycle the acidic water, which resulted in the continuous increase in the concentration of H2S, HCl, NH3 and other media in the accident pipeline, aggravating pipeline corrosion. (2) The pipeline temperature exceeds the design limit, aggravating pipeline corrosion. The original operating temperature of the accident pipeline was 150°C and the design temperature was 170°C. However, the actual operating temperature of the pipeline at the time of the incident was about 180°C, which exceeded the design operating temperature of the pipeline. In the compound acidic environment of wet H2S, HCl, and NH3, the over-temperature operation of pipelines aggravates pipeline corrosion.
This is a problem. I just noticed the reuse and did not control the reuse conditions.
This clearly shows that it is not a design problem, but caused by improper use and maintenance.
As the saying goes, high incense is burned and the end of the year happens to be the season for resigning.