Effective use of surplus LP steam to maximize cracker throughput and reduce energy consumption.

Steam cracking is a fundamental application of olefin production which is the building block of petrochemical complex. Continuous efforts are being made to optimize the cracker performance by process-side optimization. The cracker furnace flue gas, which has a huge quantum of low-grade energy, is getting lost from the stack; a waste heat recovery system is being employed to generate ow-pressure steam. This also helps in the reduction of induced draft fan suction temperature. However, if there are no low-pressure steam consumers, the steam requires to be vented or partial heat recovery to be done. The lower heat recovery through waste heat recovery boiler restricts the cracking furnace throughput due to a higher suction temperature of the induced draft. A detailed steam network study has been done for a petrochemical complex having various downstream plants to maximize heat recovery as well as furnace throughput. For any equipment in question, to use a lower steam, it was a challenge to switch over from relatively higher-pressure steam to lower-pressure steam due to equipment design consideration as well as operating temperature requirement of any process. Different alternatives were thought of and evaluated based on process requirement, possibility of steam venting of other level steam, and cost of modifications. The outcome of this study has helped to utilize the low-pressure steam. The study indicated that for optimization of cracker performance, in addition to process side, there is a scope to improve on flue gas side operation also. [ABSTRACT FROM AUTHOR]