Recently, the 200,000 t/y ethylene cracking furnace, jointly developed by SEI, Beijing Chemical Industry Research Institute and Tianhua Institute of Chemical Machinery & Automation Co., Ltd. (Tianhua Institute), has been successfully put into operation at Zhenhai Petrochemical and passed the performance evaluation, another improvement of China’s indigenous technology to manufacture ethylene complete sets.
This is China’s first ethylene cracking furnace and also one of the world’s biggest cracking furnaces. Tianhua Institute was responsible for the development and design of its quench boiler system and combustion system. The rapid cooling heat exchanger is one of the key equipment of the ethylene cracking furnace and is of the most advanced linear structure made of large-diameter heat exchange tubes, with low mass flow rate, little resistance, low outlet temperature, and produces much steam. It’s thus energy efficient, without the need of mechanical decoking, and its operational cycle is long. Another key equipment is the combustion system which is heating from sides and the bottom, with fuel grading, smoke recirculation and low-oxygen multiple-point combustion techniques adopted, and the bottom heater also uses the automatic control system for boiler damper.
The actual operation shows that the quench boiler system and the combustion system developed by Tianhua Institute have met or surpassed the requirements. The automatic control system for boiler damper used in the bottom heater allows the furnace to run at the optimal oxygen level, improves the thermal efficiency of the furnace and reduces the operator’s workload. In particular, the Low NOx combustor provided by Tianhua Institute has an NOx emission of about 80mg/Nm^3, lower than the national standard 100 mg/Nm^3.