سیستم های هوشمند برای تجزیه و تحلیل HAZOP نیروگاه های دارای فرایند پیچیده

Process safety, occupational health and environmental issues are ever increasing in importance in response to heightening public concerns and the resultant tightening of regulations. The process industries are addressing these concerns with a systematic and thorough process hazards analysis (PHA) of their new, as well as existing facilities. Given the enormous amounts of time, effort and money involved in performing the PHA reviews, there exists considerable incentive for automating the process hazards analysis of chemical process plants. In this paper, we review the progress in this area over the past few years. We also discuss the progress that has been made in our laboratory on the industrial application of intelligent systems for operating procedure synthesis and HAZOP analysis. Recent advances in this area have promising implications for process hazards analysis, inherently safer design, operator training and real-time fault diagnosis.

HAZOP analysis is a process hazard analysis method which has been widely used in chemical process industries, especially in some complex process plants. Processes, human operations, many pieces of equipment, a mass of material, a number of instruments, several control systems, safety and environment, etc., interweave to form a complex process plant. Human operations always play a tremendous role in running the plant. In an analysis process, P&ID of the complex process plant should be examined by a multi-disciplinary team of experts systematically, and all conceivable deviations far from design intentions in the plant can be identified and all the possible abnormal causes and the adverse consequences of these deviations can be determined. The considerations of the experts are provided in the following four aspects: 1) determining whether a given operation or activity has the potential to give rise to a hazardous situation, 2) determining the range of hazardous events that the operation or activity could present (Jeong, Lee, Lee, & Lim, 2008), 3) identifying the routes by which each of these hazardous events could be realized, i.e., identifying the potential incident scenarios, 4) providing some prevention suggestions or measures to avoid hazardous events if the safeguards are not enough (Guimaraes and Lapa, 2006, Kim and Seong, 2006 and Wu et al., 2003). However, there are three problems which are difficult to deal with in the practical application of HAZOP analysis. 1) The inheritance instrument of the experience knowledge. Firstly, information is always hard to acquire. Secondly, information obtained from different channels is sometimes inaccurate. Thirdly, an available inheritance instrument can be helpful for the experts to record their experience knowledge, and can be subservient to the need of the analysis groups, who hope to obtain sufficient experience knowledge which is more valuable than that of any others associated with the current analysis object to compensate for lack of engineering experience or expertise (Wang, Gao, & Guo, 2009). 2) The classification of accident causes. Case-based HAZOP analysis and rule-based HAZOP analysis have a common disadvantage that both are over-reliance on the completeness of the information contained in their databases. Hazards could not be identified if the kind of the accident had never occurred. For one thing, it is difficult to ensure the completeness of the experience knowledge, and for another thing, it may lead to an information explosion if too many cases or rules were filled in the database. 3) The recurrence of the analysis process and the verification of the analysis results. It is difficult to verify whether the analysis results were loaded correctly or not. Personnel not involved in the analysis process can not accurately understand the intentions of the analysis group and it is difficult for them to reproduce the analysis process only based on the final analysis report. There are some computer-aided HAZOP analysis programs developed, such as the HAZOPExpert program, the SDG-HAZOP program, the HAZOPSuite program, the PHA-Pro program and the like, most of which do not have special modules to store experience knowledge, could be utilized to execute the HAZOP analysis. This paper will introduce a new program, the HELPHAZOP program, which can be combined with a computer-aided HAZOP analysis software to solve the above problems in the practical application of HAZOP analysis. The HELPHAZOP program can be considered as an expert system. And the expert system is a computer program built for the diagnosing, fault-finding and problem-solving purposes and closely matches the human logic thinking process. Some information stored in the HELPHAZOP program database can be employed to infer new facts. The plant of the residuum hydrotreating process is one of the most dangerous plants in chemical industry. Firstly, many types of equipments are often operated at extremes of pressure and temperature, which makes them more vulnerable to equipment failures. Secondly, the operations are so complex that it is almost impossible for operators to identify all the abnormal situations and obtain the causes thereof in the first time. Thirdly, there are a variety of risk factors in the process, and it is very difficult to control the strongly exothermic reaction while the plant is in an abnormal situation. Therefore, the HAZOP analysis and the other risk identifications of the complex process are worth of being done for the accident preventions. The HELPHAZOP program has been applied in the HAZOP analysis process of the residuum hydrotreating process. In contrast with the customary analysis, it is confirmed that the probability of human errors caused by the misunderstanding or the lack of experience can be reduced, and the accuracy, practicability and analysis efficiency of the accident forecast can be greatly improved by the use of the program.

The HELPHAZOP program is developed for the inheritance of the experience knowledge, and the program application in the HAZOP analysis of the residuum hydrotreating process can not only make up for the deficiency of plant experience but also improve the analysis efficiency. The effective understanding of the danger spread process can significantly enhance plant safety, reduce fault-caused shutdowns and save maintenance cost, resulting in great economical and social benefits. It has reduced the probability of the human errors because of the misunderstanding or the deficiency of plant experience in the HAZOP analysis, and has improved the accuracy, practicability and analysis efficiency of the accident forecast. However, due to the change of the design intentions of the plant, the knowledge stored in the program should be corrected according to the practical situations and expert experience.