Incorporating inherent safety during the conceptual process design stage: A literature review

Advanced Modeling and Optimization Strategies for Process Synthesis

This article provides a systematic review of recent progress in optimization-based process synthesis. First, we discuss multiscale modeling frameworks featuring targeting approaches, phenomena-based modeling, unit operation-based modeling, and hybrid modeling. Next, we present the expanded scope of process synthesis objectives, highlighting the considerations of sustainability and operability to assure cost-competitive production in an increasingly dynamic market with growing environmental awareness. Then, we review advances in optimization algorithms and tools, including emerging machine learning-and quantum computing-assisted approaches. We conclude by summarizing the advances in and perspectives for process synthesis strategies.

Prioritization of control measures in leakage scenario using Hendershot theory and FBWM-TOPSIS

Currently, there is increasing concern about the safety and leakage of process industries. Therefore, the present study aims to prioritize control measures before and after the leakage scenario by using the Hendershot theory and MCDM techniques. In this study, two proactive and reactive layers were selected before and after leakage of tanks, respectively. Then, criteria and alternatives were selected to perform fuzzy TOPSIS (FTOPSIS) and find the best alternative based on the literature review and Hendershot approach. The linear model of the fuzzy Best-Worst method (FBWM) was constructed and resolved using Lingo 17 software. Subsequently, criteria were assigned weights based on thorough calculations of the inconsistency rate. The weight of study experts was equal to 0.25. The results of FBWM showed that the reliability index with a weight of 0.3727 was ranked first and the inconsistency rate ([Formula: see text]) was calculated to be equal to 0.040. Inherent Safety Design (ISD) (0.899) and passive safety (0.767) also ranked first before and after tank leaks, respectively. Using the FBWM method leads to fewer pairwise comparisons and at the same time more stability. Although ISD and passive strategies are more valid and strict, elements of all strategies are necessary for a comprehensive process safety management program.

A framework for integrating safety and environmental impact in the conceptual design of chemical processes

Multiple factors influence chemical process design and technology selection, including technical, economic, environmental, and safety considerations. Traditionally, a techno-economic analysis has been used to select a base case design, while safety and environmental impact have been subsequently assessed. This may leave out designs that exhibit better environmental and safety performance than the selected base case at a very early stage of design, where abundant opportunities for incorporating these objectives are present. Furthermore, although safety is an integral part of the overall sustainability of a chemical plant, historically it has been addressed separately from sustainability. Thus, there is a growing awareness for simultaneous consideration of these objectives during the conceptual process design phase of a project in order to select the most sustainable process route. The key to an effective sustainability assessment method for selecting the most sustainable process route involves the parsimonious selection of adequate metrics which define the sustainability profile of the process and an integrated multi-criteria decision-making (MCDM) framework. In this context, this work investigates gaps in conceptual process design and existing sustainability assessment methods through a review of existing environmental impact and safety assessment methodologies/tools. A possible workflow that incorporates both safety and environmental impact in a holistic multi-criterion decision-making framework (MCDM) has been proposed to select the most sustainable process route. The use of this framework is illustrated through a simple case study involving assessing solvent alternatives for palm oil recovery to highlight the scope and significance of the proposed framework.

Inherent Safety Assessment of Industrial-Scale Production of Chitosan Microbeads Modified with TiO2 Nanoparticles

In this study, the inherent safety analysis of large-scale production of chitosan microbeads modified with TiO₂ nanoparticles was developed using the Inherent Safety Index (ISI) methodology. This topology was structured based on two main stages: (i) Green-based synthesis of TiO₂ nanoparticles based on lemongrass oil extraction and titanium isopropoxide (TTIP) hydrolysis, and (ii) Chitosan gelation and modification with nanoparticles. Stage (i) is divided into two subprocesses for accomplishing TiO₂ synthesis, lemongrass oil extraction and TiO₂ production. The plant was designed to produce 2033 t/year of chitosan microbeads, taking crude chitosan, lemongrass, and TTIP as the primary raw materials. The process was evaluated through the ISI methodology to identify improvement opportunity areas based on a diagnosis of process risks. This work used industrial-scale process inventory data of the analyzed production process from mass and energy balances and the process operating conditions. The ISI method comprises the Chemical Inherent Safety Index (CSI) and Process Inherent Safety Index (PSI) to assess a whole chemical process from a holistic perspective, and for this process, it reflected a global score of 28. Specifically, CSI and PSI delivered scores of 16 and 12, respectively. The analysis showed that the most significant risks are related to TTIP handling and its physical-chemical properties due to its toxicity and flammability. Insights about this process's safety performance were obtained, indicating higher risks than those from recommended standards.

An Integrated Approach to the Design of Centralized and Decentralized Biorefineries with Environmental, Safety, and Economic Objectives

Biorefineries provide economic, environmental, and social benefits towards sustainable development. Because of the relatively small size of typical biorefineries compared to oil and gas processes, it is necessary to evaluate the options of decentralized (or distributed) plants that are constructed near the biomass resources and product markets versus centralized (or consolidated) facilities that collect biomass from different regions and distribute the products to the markets, benefiting from the economy of scale but suffering from the additional transportation costs. The problem is further compounded when, in addition to the economic factors, environmental and safety aspects are considered. This work presents an integrated approach to the design of biorefining facilities while considering the centralized and decentralized options and the economic, environmental, and safety objectives. A superstructure representation is constructed to embed the various options of interest. A mathematical programming formulation is developed to transform the problem into an optimization problem. A new correlation is developed to estimate the capital cost of biorefineries and to facilitate the inclusion of the economic functions in the optimization program without committing to the type of technology or the size of the plant. A new metric called Total Process Risk is also introduced to evaluate the relative risk of the process. Life cycle analysis is applied to evaluate environmental emissions. The environmental and safety objectives are used to establish tradeoffs with the economic objectives. A case study is solved to illustrate the value and applicability of the proposed approach.