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惠州炼油4200kt/a延迟焦化装置引进美国Foster Wheeler公司的工艺包,采用“两炉四塔”大型化工艺,生焦周期为18h,设计循环比为0.3,焦炭塔顶盖和底盖采用自动卸盖装置。该装置采用单井架水力除焦,冷焦水和切焦水采取一体化处理方式。切焦水补水部分采用新鲜水,净化后的含硫酸性水回用焦池作切焦水补水。由于延迟焦化装置的高压水管道和设备周期性运行,介质压力高,管件壁厚较厚,管件材质较高,运行一段时间后,出现了除焦系统管道和设备腐蚀现象,腐蚀形态主要为应力腐蚀。经分析,回用的净化水氯离子含量偏高及除焦水温相对较高是主要的影响因素。应对措施方面,通过限制不合格净化水和氯离子含量高的净化水排入焦池、降低净化后的酸性水和含油污水的回用水量等,可降低除焦水氯离子浓度。同时,应考虑工艺条件的改进,包括降低除焦水水温、限制管道流速以及设备材质的提高,加强设备检测等,降低除焦设备腐蚀对装置长周期运行的影响。
Huizhou Refining 4200kt / a delayed coking unit introduced the United States Foster Wheeler’s process package, the use of “two furnace four towers ” large-scale technology, raw coke period of 18h, design cycle ratio of 0.3, coke tower roof and bottom cover Automatic unloading device. The device uses a single derrick hydraulic decoking, cold coke water and cut coke water to take an integrated approach. Choking water replenishment part of the fresh water, purified sulfuric acid-containing water back to the coke pool for the cut coke water replenishment. Due to the periodic operation of high-pressure water pipeline and equipment of delayed coking unit, the medium pressure is high, the wall thickness of the pipe is thick, and the material of the pipe is relatively high. After running for a period of time, corrosion of the pipelines and equipment of the decoke system occurs and the corrosion forms are mainly stress corrosion. After analysis, the reuse of purified water chloride ion content is higher and in addition to coke water temperature is relatively high is the main factor. In terms of coping measures, chloride ion concentration in tap water can be reduced by limiting the discharge of purified water with unqualified purified water and high chloride ion content into the coke pool and reducing the amount of recycled water of acidified and oily wastewater after purification. At the same time, the improvement of process conditions should be considered, including reducing the water temperature of the coke water, limiting the flow rate of the pipeline, improving the material of the equipment, and strengthening the equipment testing so as to reduce the impact of the decoking equipment corrosion on the long-term operation of the equipment.