Dynamic risk assessment and fault detection in process facilities

A new multivariate risk-based fault detection and diagnosis technique targeting the safety issues of a process system is being proposed. In contrast to typical fault detection methods which only aim to detect operational faults that affect the control objectives of the process, this method targets the safety of the process. Typical fault detection and diagnosis methods are inadequate as none of the methods considers the consequences of the fault on process safety, integrity and the environment. However the proposed method provides a dynamic process risk indication based on the probability of occurrence of a fault and its consequences. In this method, the consequence is expressed in economic value that demonstrates the potential economic impact of the fault on the process, equipment, workers and the environment. Through this approach, warning system and risk management strategies may be activated when the risk of operation exceeds the acceptable threshold. This is an important concept because it can direct the attention and effort of operators to the faults which poses the most operational or safety risk. Both model based and history based fault detection and diagnosis techniques have been extended to a risk-based fault detection and diagnosis framework. Application of this new risk-based approach provides early warnings and early activation of safety systems prior to the fault impacting the system. This multivariate technique provides much early warning compared to the univariate methods. It has more power in discerning between operational changes and abnormal conditions which have potential to cause accidents. The main benefits of this approach are improved safety, minimum interruption of operation, better alarm management or early warning system and higher availability of process. The novelties and contributions of this work are development of multivariate dynamic risk assessment methodology using history based and model based methods for linear and nonlinear models combined with a newly developed economic consequence analysis methodology. This methodology makes the severity of the faults more sensible by quantifying consequences in economic terms. This new economic consequence methodology helps to integrates real time process state to accident scenarios via loss functions. The proposed framework when implemented on a process could serve as a real-time process risk monitor. This would help to take preventive actions in order to minimize process risks

Flare Gas Recovery in Oil and Gas Refineries

Environmental and economic considerations have increased the use of gas recovery systems. Regarding our comprehensive process evaluation in 11 oil and gas refineries, we devised practical methods to approach zero flaring. This paper presents the results of two case studies of reducing, recovering and reusing flare gases from the Tabriz Petroleum Refinery and Shahid Hashemi-Nejad (Khangiran) Natural Gas Refinery, both in Iran. The design considerations, economics of the process and system operation are studied in this paper. Flare gases are compressed and returned to the fuel gas header for immediate use as fuel gas. Flare gas recovery reduces noise and thermal radiation, operating and maintenance costs, air pollution and emission, and fuel gas and steam consumption. Process stability and flare tip increment without any impact on the existing safety relief system are also the effects of the flare gas recovery system

Risk-based process system monitoring using self-organizing map integrated with loss functions

Free to read\ud \ud The conventional dynamic risk assessment technique does not consider the effect of nonlinear interactions among process variables in its operational risk estimation. Thus, this type of technique fails to provide a realistic estimation of the operational risk of complex industrial processes. To address this issue, a multivariate risk-based process monitoring technique is proposed. This technique takes advantage of the powerful nonlinear dimensionality reduction and visualization power of the self-organizing map to identify the origin and propagation path of the fault. Through integration with the inverted normal loss function, a robust estimation of the hazard potential and operational risk of process operations can be achieved. The proposed technique is tested with two fault conditions in the benchmark Tennessee Eastman chemical process. The results show promising performance

Risk Analysis of Flare Flame-out Condition in a Gas Process Facility Analyse des risques des conditions d’extinction de torche au sein d’une installation de traitement de gaz

Flaring is a common method of disposal of flammable waste gases in the downstream industries. Flare flame out (flame lift-off or blow-outs) often occurs causing toxic vapors to discharge. The toxic gases released may have hazardous effects on the surrounding environment. To study the effect of inhalation exposure of these toxic gases on human health, the four steps of the EPA (Environmental Protection Agency) framework with the field data to quantify the cancer and non-cancer health risks are integrated in this paper. As a part of exposure assessment, gas dispersion modeling using AERMOD and UDM-PHAST is applied in two different conditions of normal flaring and flare flame out during a particular climate condition in Khangiran region. Recommendations to avoid flare flame out conditions are also presented here. Le torchage est un procédé courant d’élimination des gaz résiduaires inflammables dans les industries de traitement. L’extinction de la torche (par décollage ou soufflage de flamme) provoque souvent une émission de vapeurs toxiques. Ces gaz toxiques libérés peuvent présenter des effets dangereux sur le milieu environnant. Pour étudier l’effet d’une exposition par inhalation de ces gaz toxiques sur la santé, cet article croise les quatre étapes de la démarche de l’EPA (Environmental Protection Agency, Agence de protection de l’environnement) avec les données d’exploitation afin de quantifier le risque sanitaire cancérologique et non cancérologique. Dans le cadre de l’estimation d’exposition, une modélisation de dispersion des gaz utilisant AERMOD et UDM-PHAST est évaluée dans deux configurations différentes de torchage normal et d’extinction de torche à l’occasion de conditions climatiques particulières dans la région du Khangiran. L’article propose également des recommandations destinées à éviter les conditions d’une extinction de flamme de torche

Risk Analysis of Flare Flame-out Condition in a Gas Process Facility

Flaring is a common method of disposal of flammable waste gases in the downstream industries. Flare flame out (flame lift-off or blow-outs) often occurs causing toxic vapors to discharge. The toxic gases released may have hazardous effects on the surrounding environment. To study the effect of inhalation exposure of these toxic gases on human health, the four steps of the EPA (Environmental Protection Agency) framework with the field data to quantify the cancer and non-cancer health risks are integrated in this paper. As a part of exposure assessment, gas dispersion modeling using AERMOD and UDM-PHAST is applied in two different conditions of normal flaring and flare flame out during a particular climate condition in Khangiran region. Recommendations to avoid flare flame out conditions are also presented here