White Papers

Forget Direct Scaleup Vent Sizing and Master Kinetic Modeling Instead

Direct scale-up methods have been used to develop relief requirements and vent sizing for runaway reactions since the early 1990s. Direct scale-up methods have been popular because one is able to measure in a laboratory test the required relief size in equivalent vent area per unit mass of a reacting mixture, in 2/kg, and then scale it up to plant scale equipment sizes. Read more

HAZard & OPerability (HAZOP) Guidelines

This paper provides concise and structured documentation to be used as a “guideline” when conducting Hazard & Operability (HAZOP) studies. It collects and summarizes key tables, figures, and checklists placed in chronological order according to the sequential phases that define the HAZOP Management System (HMS). Read more

How to Conduct a Dust Hazards Analysis

The 2016 Edition of NFPA 652 (NFPA, 2016) requires a dust hazards analysis (DHA) of existing processes by September 7, 2018. (DHAs are also needed for material modifications that exceed 25% of the original cost.) A dust hazards analysis is defined by NFPA as “A systematic review to identify and evaluate the potential fire, flash fire, or explosion hazards…” where combustible particulate solids are processed or handled. Read more

InterScience Reactivity Screening Made Easy

During the past decade, large efforts were made by the US chemical and petrochemical industries to implement and maintain effective process safety management (PSM) and responsible care programs. Despite these large investments, incidents continue to occur at an alarming frequency. Many executives of leading companies are trying to understand why. Read more

Key Safety Issues for Combustible Dust Handling

As part of a Combustible Dust National Emphasis Program (NEP), OSHA conducted focused inspections of facilities that generate or handle combustible dusts. Some of these facilities were not even aware that they were handling combustible dusts and may not have been familiar with the necessary safeguards to safely handle these materials. Read more

Laminar Flame Speeds Data Collection

Regarding vessels and tubes containing combustible gases or dusts, it is important to acquire knowledge on the conditions under which a fuel and oxidizer could undergo explosive reactions. These conditions are strongly dependent on the pressure and temperature. Given a premixed fuel-oxidizer system at room temperature and ambient pressure, the mixture is essentially unreactive. However, if an ignition source is applied locally and the composition of the mixture is within certain limits (the so-called flammability limits), a region of explosive reaction can propagate through the gaseous mixture due to mainly two phenomena: (1) Temperature rises substantially, (2) High concentration of radicals to form. Characterizing potential explosive reactions is one of the main objectives of hazard assessment. Safeguards to be implemented in process equipment, best process conditions, appropriate prevention and/or mitigation measures, are some of the key purposes to be clarified when handling flammable mixtures. This characterization requires knowledge of several parameters that directly influence on the explosive reaction behavior. One of these parameters is the Laminar Flame Speed, which is one of the key factors that define the kinetics of the reaction. The present paper addresses how to characterize fuel-oxidizer explosive reactions, and highlights the importance of the laminar flame speed concept. The main purpose of this study is to provide reliable data regarding laminar flame speeds with the aim to ensure accurate calculations for hazard assessment purposes. Read more