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导致焦炭塔油气出口与大油气线连接处结焦的原因较多,包括原料性质、焦炭塔顶温度、急冷油注入点位置、消泡剂的加入量等。上述结焦因素并非彼此独立,而是相互关联。如:通过提高反应温度来控制泡沫层高度,则塔顶温度也相应升高,若再通过塔顶大量注入蜡油降低塔顶温度,则循环比又相应提高,增加了生焦率。因此,综合考虑各因素的利害关系,制定最优操作方案:在生焦后期,塔内焦层较高,切换前几小时降低加工量,减小循环比,并且适当减小注水量,以及提高反应温度,减小后期塔内气速,减缓焦层的增长速率。针对抑制塔顶的结焦反应,由于蜡油比热容较大,在生焦周期前段时间,使用蜡油作为急冷油效果更佳。而在切塔前,为降低循环比,改用一中油来降低塔顶温度。最后再通过塔顶注入消泡剂,并在后期加大注入量。上述方法足以有效控制塔顶出口管线的结焦,该处的清焦频次可延长至数年一次。
There are many reasons that lead to the coke tower oil and gas outlet and large oil and gas line junction coking, including the nature of raw materials, coke overhead temperature, the location of the quench oil injection point, the amount of defoamer added. The above coke factors are not independent of each other, but interrelated. Such as: by increasing the reaction temperature to control the height of the foam layer, the temperature of the top of the tower is also increased accordingly, and then pour a large number of oil through the tower to reduce the temperature of the top of the tower, the circulation ratio and a corresponding increase in raw coke rate. Therefore, taking all the factors into consideration, we should formulate the optimal operation plan: in the late stage of green coke, the coke layer in the tower is higher, the processing volume is reduced a few hours before switching, the circulation ratio is reduced, the water injection amount is appropriately reduced, The reaction temperature, reduce the gas velocity in the late tower, slow down the growth rate of the coke layer. In order to restrain the coke reaction on the top of the tower, it is better to use the wax oil as the quench oil in the period of the raw coke cycle because the specific heat capacity of the wax oil is larger. In cut before the tower, in order to reduce the circulation ratio, switch to a medium oil to reduce the temperature of the top. Finally, through the top of the tower into the defoamers, and increase injection in the late. The above method is sufficient to effectively control the overhead outlet pipeline coking, where the coking frequency can be extended to several years.