Application of i-SDT for safer flare management operation

Abstract

Utilizing unburn flare streams in a safe way represents one of the key challenges during flare alternatives implementation. Most of the time, process safety is considered on a supplemental basis after accomplishing a detailed plant design and economic analysis. The prime reason is the lack of a systematic design tool that facilitates the incorporation of inherently safer design principles into the early stage of process synthesis and in the absence of an adequate amount of data. It would be therefore advantageous for designers if they were able to assess safety aspects in a continuous manner for retrofitting design purposes as well as appraising innovative alternatives. In this work, a newly developed Inherently Safer Design Tool (i-SDT) has been applied to identify reliable and safer operating conditions while implementing a cogeneration (COGEN) unit as a flare utilization alternative. In the illustrative case study, the COGEN unit has been accompanied by an ethylene process to act as an additional utility provider by using some portion of the unburn hydrocarbon streams. These streams were available from several flaring locations of the plant during different routine/abnormal cases. The objective of this work is to conduct a comprehensive techno-economic and environmental performance analysis by utilizing a multi-objective optimization framework along with the necessary set of process constraints derived from the safety perspective offered by i-SDT. The illustrative case study considered here showed that the proposed i-SDT tool could estimate the limits associated with key safety parameters (flammability, toxicity, explosiveness, and reactivity) by explicitly considering operating conditions. Later, these operating limits are explicitly embedded as safety constraints into the optimization algorithm to assess the techno-economic, environmental and safety performance profiles of the process system under consideration. © 2019 The Institution of Chemical Engineers