117,282 research outputs found
Sensitivity analysis of a dynamic model for gas producing reactions under runway conditions
No full textA dynamic model to simulate the behaviour of a purely gassy system during venting is proposed. A sensitivity study of the model predictions (temperature, pressure and mass inventory) to the following parameters is performed: initial vessel fill level, vessel volume, external heat input, relief vent area and vessel aspect ratio
Training Future Engineers to be Committed to Safety
No full textHistory has shown at multiple occasions that major incidents in the process industry have the potential to affect the world in different aspects: loss of life and economic losses and environmental disasters. Can the occurrence of major preventable incidents be seriously decreased by investing in better education and research in process safety? This paper will share ideas on how to convey safety as a value to engineering students. Emphasis with be put on making them participants and actors of Process Safety related activities at early stages of their education in order to work at the development of their safety culture well before the start of their professional life. These activities include their involvement in current research, laboratory activities using specific equipment, long term projects on the study of incident that defined Process Safety. The integration of Process Safety principles in other regular engineering courses will also be discussed
Modelling of the venting of an untempered system under runaway conditions
No full textRunaway reactions are statistically one of the major concerns for the chemical industry. Historically, they have been the cause for many severe incidents, as in the well-known cases of Seveso (Italy, 1976), Bhopal (India, 1984) and more recently the T2 Laboratories (USA, 2007).
The prediction of the consequences of a runaway reaction in term of temperature and pressure evolution in a reactor vessel requires the knowledge of the reaction kinetics, thermodynamics and fluid dynamics inside the vessel during venting. Such phenomena and their interaction are complex and still to be fully understood, especially for those reactions in which the pressure generation is totally or partially due to the production of permanent gases (gassy or hybrid systems). Moreover, they cannot be easily determined by laboratory scale experiments.
The work described in this paper presents a dynamic model developed to simulate the behavior of an untempered reacting mixture during venting. The model provides the temperature, pressure and inventory profiles before and during venting. A sensitivity study of the model was performed. This modeling work provides some insight regarding the interpretation of the data obtained from untempered system venting experiments. The outcomes of this work finds an application in the improvement of emergency relief systems design for hybrid and gassy systems, where significant progress is still to be made both in the experimental and modeling areas
Experimental sensitivity analysis of the runaway severity of Dicumyl peroxide decomposition using adiabatic calorimetry
No full textThe behavior of Dicumyl peroxide (DCP) under runaway conditions was studied using low and high phi factor (φ) calorimeters. Solutions of 20, 30 and 40%, by weight, of DCP in 2,2,4-trimethyl-1,3-pentanediol diisobutyrate and cumene were run at different phi factors experiments(1.8 > φ > 1.1). The results depicted that cumene reduces the severity of the runaway decomposition of DCP, while the phi factor of the experiments showed to have a high influence on the rise of temperature and pressure. Values up to 18 and 27 times higher, respectively, were obtained at same concentration when reducing the phi factor from 1.8 to 1.1. Temperatures and self-heating rates obtained at different phi factor experiments were scaled up to a phi factor equal to 1.0 using the correction method recommended by the Design Institute for Emergency Relief System (DIERS) and developed by Fisher [1]. The results showed that this method works well at low concentrations. However, at the highest concentration, fast heating rates (up to 600 °C/min) were observed in the low phi factor equipment. These fast heating rates, most probably caused the equipment to loss its adiabaticity, and the scale up of the temperatures and self-heating rates did not longer give reliable results. This means that the estimation of experimental variables such temperature and rate of temperature rise (used for vent sizing calculations), directly from the data obtained at lab scale, even when using an advance low phi factor equipment, can result in under-conservative design calculations
Integration of Process Safety in Chemical Process Design: Initiating a Different Way of Thinking
No full textTeaching process safety in Engineering curriculum in general and in Chemical Engineering curriculum in particular is becoming more crucial, giving the worldwide advancement and developments in process industries. Courses on chemical process safety usually involve, but are not limited to, the application of different principles and fundamentals studied in engineering courses (from mathematics and statistics up to transport phenomena and process design) to process safety.
This paper discusses the experience gained from teaching chemical process safety courses to the senior students in chemical engineering department at Texas A&M University at Qatar (TAMU-Qatar). Significant efforts have been made to develop teaching programs supported by key activities and the use of relevant experimental facilities to improve the quality of the teaching and transmit Safety and Process Safety as a value to the students. Process design final year project is considered as an excellent opportunity for the students to apply the principles of process safety to their process design. For this particular activity the students are encouraged to thinking a different way beyond the achievement of predefined design goals and assess the risks associated to abnormal working conditions (operation under severe condition, loss of control, etc) and reduce these risks by application of the principles of inherent safety, and the addition of prevention and mitigation measures. In other words, the challenge lies in getting the student to switch from focusing only on the process design goals to integrating different process safety concepts during solving different design problems at early stages of the project
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
- …
