延迟焦化加热炉存在问题分析与整改

惠州炼油420×104t/a延迟焦化装置加热炉采用美国FW公司双面辐射斜面阶梯炉,每台加热炉由6个辐射室、1个对流室组成。每个辐射管程设置单独的一个炉膛。共用的对流室安装在辐射室上,用于原料预热和蒸汽过热。该加热炉运行16月后,出现对流炉管结焦、排烟温度上升、部分炉管堵塞等问题。造成对流段结焦的主要影响因素,是回炼催化油浆以及注水温度相对偏低,导致渣油中沥青质析出;排烟温度高的主要影响因素是炉管结焦与对流段取热不足。对此,增加两排对流管、一排注水管、一排低低压蒸汽过热管。操作方面,主要优化措施有:停止催化油浆进焦化回炼,提高注水温度,注水方式从单点注水改为两点注水;同时平稳操作,减少焦粉携带。通过技术改造与操作优化,加热炉运行平稳,排烟温度显著降低,基本消除了加热炉对流段的结焦因素,加热炉在线清焦周期明显延长。

Problems Analysis and Improvements for Delayed Coking Furnace

CNOOC Huizhou Refinery＇s 420x104t/a delayed coking unit uses FW＇s double-fired sloped terrace-wall boilers as heating furnaces,each of the boilers comprises six radiant chambers and one convection chamber.Each tube pass is equipped with an independent combustion chamber.The shared convection chamber is installed on the radiant chambers,used for material preheating and steam superheating.Some problems arose 16 months after the heating furnaces went into operation ,including coke deposition in the tubes of the convection furnace ,elevated flue gas temperature and clogging of some furnace tubes.The main contributing factor to the coke deposition in the convection section is the low temperature of the recycled catalytic slurry oil and injected water,which resulted in precipitation of asphaltene in residual oil.The main contributing factors to high temperature of flue gas are coke deposition in furnace tubes and insufficient heat removal in the convection section.To resolve those problems,two rows of convection tubes ,one row of water filling pipes and one row of low low-pressure steam superheating tubes were added.Main operation optimizing measures included：stopping recycling catalytic oil slurry into the coking u- nit,raising the temperature of water injected,switching from single-point water injection to two-point injection,sta- bilizing operation and reducing the amount of coke powder entrapped.After the technical upgrade and operational optimization,the heating furnaces have been operating stably,flue gas temperature dropped considerably,the con- tributing factors to coke deposition in the convection sections of the heating furnaces were basically eliminated and the interval between two inline decoking operations for the heating furnaces has increased significantly.