Case Study: Safety Assessment of Plant Layout between Ethylene Storage Tanks and Process Equipment According to Capacity and Weather Conditions.

Jae-Young Choi,Sang-Hoon Byeon

doi:10.3390/ijerph17082849

Jae-Young Choi, Sang-Hoon Byeon

Open Access

https://doi.org/10.3390/ijerph17082849

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Abstract

In a chemical plant, even if an explosion occurs in a storage tank that handles flammable materials, the minimum separation distance is applied in a way to prevent chain explosion. This is because when an explosion occurs in a storage tank, thermal radiation affects nearby process equipment and causes a chain explosion. The separation distance between storage tanks and process equipment in a chemical plant depends on the global engineering guidelines PIP (Process Industry Practice) PNE00003 and GAPS (Global Asset Protection Services) GAP.2.5.2. However, there is a limitation in the global engineering guidelines that provide only a consistent separation distance according to the item types without considering the storage capacity and climatic conditions around the storage tank. This study analyzed the distance of thermal radiation (up to 37.5 kW/m2) according to the capacity of ethylene storage tank and climatic conditions by utilizing the Phast (DNV GL), which is widely used as a tool for quantitative risk analysis. The accident scenario was applied using the U.S. EPA (Environment Protection Agency)’s worst leakage accident scenario, considering climate variables, air temperature, wind speed, and atmospheric stability. In the simulation, atmospheric stability did not affect the radius of thermal radiation. Moreover, the thermal radiation tended to increase with increase in wind speed in the ambient condition and winter, but not in summer. Because both PIP PNE00003 and GAP.2.5.2 yield consistent separation distances without considering storage capacity and weather conditions, quantitative risk analysis of the results of thermal radiation is necessary to ensure safety.

Highlights

Ethylene is a representative chemical raw material used in polyethylene, ethylene glycol, PVC, etc.and can be considered the most basic material in the petrochemical industry manufactured at an NCC (Naphtha Cracking Center) or ECC (Ethane Cracking Center) [1]
Ethylene is one of the basic constituents of a chemical plant as the scale of ethylene production is considered a measure of the chemical-industry development of a country
Ethylene occurs in the gaseous phase at ambient temperature but may be converted to the liquid phase under conditions of high pressure and low temperature, which is convenient for storage and transportation

Summary

Introduction

Ethylene is a representative chemical raw material used in polyethylene, ethylene glycol, PVC, etc.and can be considered the most basic material in the petrochemical industry manufactured at an NCC (Naphtha Cracking Center) or ECC (Ethane Cracking Center) [1]. When constructing a chemical plant for ethylene-related processes, the location of the plant facility must be determined by conducting a safety-distance review via a plot plan. The location of the storage tank, which handles a large amount of ethylene should be the most important when conducting a safety-distance review [2]. The locations of facilities included in the plot plan of a chemical plant are set at an early stage of designing and must be carefully reviewed because they can significantly affect the economy (the quantity of pipes and land use) [3]. This study aims to analyze the safety distance between ethylene storage tanks and process equipment. The effect of 37.5 kW/m2 of thermal radiation on process-plant facilities is considered fatal, as summarized in Table 1 [14].

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