SCI和EI收录∣中国化工学会会刊

›› 2016, Vol. 24 ›› Issue (8): 1007-1012.DOI: 10.1016/j.cjche.2016.04.042

• Process Systems Engineering and Process Safety • 上一篇    下一篇

A method to refine the start-up scheme of compression and refrigeration systems in ethylene plants via dynamic simulation

Shengfu Zhang1, Yongchen Zhao2, Tong Qiu1, Guang Song1, Jinsong Zhao1   

  1. 1 Department of Chemical Engineering, Tsinghua University, Beijing 100084, China;
    2 China Huanqiu Contracting & Engineering Corporation, Beijing 100012, China
  • 收稿日期:2015-07-05 修回日期:2015-07-28 出版日期:2016-08-28 发布日期:2016-09-21
  • 通讯作者: Tong Qiu
  • 基金资助:
    Supported by the National Basic Research Program of China (2012CB720500) and the National Natural Science Foundation of China (U1462206).

A method to refine the start-up scheme of compression and refrigeration systems in ethylene plants via dynamic simulation

Shengfu Zhang1, Yongchen Zhao2, Tong Qiu1, Guang Song1, Jinsong Zhao1   

  1. 1 Department of Chemical Engineering, Tsinghua University, Beijing 100084, China;
    2 China Huanqiu Contracting & Engineering Corporation, Beijing 100012, China
  • Received:2015-07-05 Revised:2015-07-28 Online:2016-08-28 Published:2016-09-21
  • Supported by:
    Supported by the National Basic Research Program of China (2012CB720500) and the National Natural Science Foundation of China (U1462206).

摘要: Starting the cracking gas compressor and precooling the refrigeration system are keys to start-up of an ethylene plant and accounts for up to 50% of the total start-up time and plant flare emissions. Premature feeding of cracking furnaces can be avoided if the cracking gas compressor is started and the refrigeration system is precooled in advance using mixed gas as the start-up working medium (SWM). Start-up scenario with mixed gas as SWM could significantly reduce the emission loss and shorten the precooling time. Research shows that making appropriate start-up scheme is important not only to ensure operational safety and feasibility, but also to reduce energy consumption. In this paper, a method is proposed to select suitable start-up operational parameters of compression and refrigeration system with sufficient safe operating ranges and short precooling time. The complex interrelation among key parameters of start-up is analyzed. It is found that higher energy consumption, especially for super high-pressure steam (SS), can promote operational safety and shorten the precooling time during start-up. Based on steady-state and dynamic simulation, appropriate operating parameter ranges are determined with reasonable SS consumption. A real case study demonstrates that an appropriate start-up scheme will optimize the operation.

关键词: Start-up, Ethylene plant, Start-up working medium, Mixed gas run, Compression system

Abstract: Starting the cracking gas compressor and precooling the refrigeration system are keys to start-up of an ethylene plant and accounts for up to 50% of the total start-up time and plant flare emissions. Premature feeding of cracking furnaces can be avoided if the cracking gas compressor is started and the refrigeration system is precooled in advance using mixed gas as the start-up working medium (SWM). Start-up scenario with mixed gas as SWM could significantly reduce the emission loss and shorten the precooling time. Research shows that making appropriate start-up scheme is important not only to ensure operational safety and feasibility, but also to reduce energy consumption. In this paper, a method is proposed to select suitable start-up operational parameters of compression and refrigeration system with sufficient safe operating ranges and short precooling time. The complex interrelation among key parameters of start-up is analyzed. It is found that higher energy consumption, especially for super high-pressure steam (SS), can promote operational safety and shorten the precooling time during start-up. Based on steady-state and dynamic simulation, appropriate operating parameter ranges are determined with reasonable SS consumption. A real case study demonstrates that an appropriate start-up scheme will optimize the operation.

Key words: Start-up, Ethylene plant, Start-up working medium, Mixed gas run, Compression system