延迟焦化装置并炉过程典型问题分析及措施

An Analysis of Typical Issues Identified during Combination of Furnaces of Delayed Cokers and Countermeasures

2010年,沧州石化延迟焦化装置在原有500kt/a的基础上新增一炉两塔,改造后规模达到1.2Mt/a,主要产品为焦化干气、液化气、稳定汽油、柴油、蜡油、焦炭和少量污油。根据生产需要,可采用两炉四塔或一炉两塔的生产方式。由于常减压装置和催化裂化装置未能进行扩能改造,造成焦化装置规模与其不匹配,一炉两塔运行时原料过剩,两炉四塔长期运行时原料不足。因此,延迟焦化装置以一炉两塔生产为主,原料库存过多时,通过并炉操作并调整生焦周期和装置循环比,进行两炉四塔生产,以平衡库存。装置扩能改造至今的并炉过程中,出现了油气线至分馏塔塔壁阀卡涩、加热炉进料泵抽空、油气线至分馏塔塔壁阀法兰处冒烟和瓦斯至长明灯支线堵塞等问题。对并炉过程出现的这些典型问题,提出了增加汽封、增上预热线、蒸汽保护和改变吹扫方式等相应措施,使问题得到解决和缓解。

Sinopec Cangzhou Company added a furnace and two columns for its 500kt/a delayed coking unit in 2010.After the expansion,the unit＇s production capacity reached 1.2Mt/a.The unit primarily produces dry coker gas,LPG,stabilized gasoline,diesel fuel,wax oil,coke and a small amount of oil sludge.Depending on production needs ,the company can use a configuration of two furnaces plus four col two columns.As the atmospheric and vacuum distillation unit and the catalytic crack ed ,the capacity of the eoking unit did not match the capacities of these two units. umns or one furnace plus ing unit were not upgrad- When the configuration of one furnace plus two columns was used,there was a surplus in feedstock ,and when the configuration of two furnaces plus four columns was used for a long time,feedstock was short.For this reason,the first configura- tion was used for the delayed coking unit most of the time.When there was too much inventory feedstock, the furnaces were combined and the coke formation cycle and unit cycle ratio were adjusted to allow opera- tion of two furnaces and four columns to balance inventory.During furnace combination since the expansion of capacity of the delayed coking unit,a series of issues have arisen,such as jamming along the oil and gas lines until the wall valves of the fractionating columns, depletion of feed pumps of the heating furnace, smoke production at the flanges from the oil and gas lines to the wall valves of the fractionating columns, and clog- ging of the gas and nightlight branch lines.To overcome these typical issues arising from combination of fur- naces ,technicians put forth countermeasures ,including adding vapor locks and preheating lines ,introducing va- por protection and changing the way of purging, and the above issues were either resolved or alleviated.