공정 설계 및 최적화에 대한 위험성 기반 내재적 안전성 접근법

학위논문(박사)--서울대학교 대학원 :공과대학 화학생물공학부,2020. 2. 이종민.The role of process safety is to prevent potential disasters in the chemical process. While a variety of techniques are commonly used in the field, accurate risk assessment and analysis require quantitative methods to allow direct comparisons between different alternatives or designs, among other benefits. However, there are various processes with different characteristics and complexities, and not all methods can be equally applied. It is essential to consider safety according to the characteristic of each process and to establish a design method which considers safety from the initial design stage to the operation stage. However, most process safety approaches, such as Quantitative Risk Assessment (QRA) or Hazard and Operability (HAZOP) studies, are conducted at the end of the design process and often have expansive and time-consuming drawbacks due to their repetitive nature. Therefore this thesis proposed a risk-based design method and modeling for designing an inherently safe process to consider the economic feasibility and process safety simultaneously. The thesis deals with elements such as process knowledge management, process safety information, inherently safe design, process hazard analysis for the system configuration required to analyze, and understand the potential risk during the process design and operation. As for the process to apply this, natural gas-related processes, which are recently attracting attention due to the development of shale gas and small and medium-sized gas reservoirs were selected, to determine the optimal design of natural gas liquefaction process. In Chapter 2 of this thesis, the accident models used in the chemical process were analyzed, and the development and validation of the necessary indoor release model were addressed. Chapter 3 covered interactive simulation that uses process data during accident modeling. Finally, Chapter 4 presented a multi-objective optimization methodology to design a safer process by introducing risk modeling and inherent safety. The method is applied to the preliminary design stage of the natural gas liquefaction process and found the result that considers process safety as well as economic feasibility. The limitations of conventional designs using the concept of inherent safety were overcome by implementing the quantitative risk assessment procedure directly in the optimization sequence.화학 공정 안전은 공정의 위험을 평가하기 위해 수행된다. 여러 기법들 중 일반적으로 공정 관리 단계에서는 다양한 기법이 사용되지만, 특히 공정 안전성과 위험성을 정확하게 평가하고 분석하려면 서로 다른 설계나 대안 등과 직접적인 비교를 가능하게 하는 정량적 방법이 필요하게 된다. 하지만 특성과 복잡성이 다른 다양한 공정들이 존재하기 때문에 각 공정의 특성에 따라 안전을 고려해야 하고, 초기 설계 단계부터 운영 단계까지 안전을 고려한 화학 공정 설계 방법을 확립하는 것이 중요하다. 그러나 QRA (Quantitative Risk Assessment) 또는 HAZOP (Hazard and Operability study) 연구와 같은 대부분의 공정 안전 접근 방식은 설계 절차 마지막에 고려되고, 종종 반복적이거나 시간 소모적인 특성으로 인해 긴 시간과 많은 비용이 드는 단점이 존재한다. 따라서 본 연구는 공정의 경제적 타당성과 안전성을 동시에 고려하기 위해 본질적으로 안전한 공정을 설계하는 것을 목표로 하여 위험 기반 설계 방법과 설계에 필요한 모델링을 제안하였다. 따라서 본 논문에서는 공정 설계 및 운영 중에 발생할 수 있는 위험을 분석하고 이해하는 데 필요한 시스템 구성을 위해 공정 지식 관리, 공정 안전 정보, 내재적으로 안전한 설계, 공정 위험 분석, 프로젝트 경제성 검토 등의 요소들을 다루었다. 이를 적용할 공정으로는 최근 셰일 가스 및 중소규모 가스전 등의 개발로 주목 받고 있는 천연가스 관련 공정을 선정하여 최종적으로 다목적 최적화를 통한 LNG 액화 공정의 최적 설계를 결정하는 것을 목표로 하였다. 본 논문의 2장에서는 화학사고 결과 모델링에 대해 다루어 화학 공정에서 사용되는 모델들에 대한 분석이 행해졌으며 추가로 필요하다고 고려되는 실내 유출 모델에 대한 개발 및 검증이 제시되었다. 3장에서는 공정 정보를 사고 모델링에 사용하는 인터랙티브 시뮬레이션에 대해서 다루었다. 최종적으로 4장에서 이상의 결과물들을 적용하여 보다 안전한 공정을 설계하기 위한 목적으로 내재적 안전성의 개념을 도입한 다목적 최적화 방법론을 제시하였으며, 이를 천연가스 액화공정의 예비 설계단계에 적용하여 경제성과 안전성을 동시에 고려한 결과를 찾아냈다. 이 과정에서 기존 내재적 안전성을 고려한 설계들이 가지고 있던 한계를 정량적 위험성 평가 절차를 최적화 과정에 직접 구현하는 것을 통해 보완하였다.CHAPTER 1. Introduction 1 1.1. Research motivation 1 1.2. Research objective 5 1.3. Outline 6 CHAPTER 2. Accident models in Chemical Process Industries 7 2.1. Introduction 7 2.2. Analysis of conventional accident models for chemical processes 9 2.3. Development of indoor release model 12 2.4. Mitigation effect analysis 35 2.5. Concluding remarks 43 CHAPTER 3. Interactive Process-Accident Simulation 45 3.1. Introduction 45 3.2. Gas pressure regulation station case study 46 3.3. Concluding remarks 53 CHAPTER 4. Process Design with Inherent Safety 54 4.1. Introduction 54 4.2. Process description 61 4.3. Design optimization 68 4.4. Concluding remarks 86 CHAPTER 5. Conclusion 88 Nomenclature 89 References 92 Abstract in Korean (국문초록) 99Docto

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