Study On Risk Classification Of Ammonia Refrigeration Enterprises Based On Extension Theory

Ammonia is widely used in refrigeration industry because of its favourable thermodynamic performance,energy saving and low cost.However,due to the corrosiveness,toxicity and combustibility of ammonia,it is easy to cause a large-scale range of poisoning and environmental pollution after the accident,result in bad social impact.Therefore,the safety of ammonia refrigeration enterprises cannot be ignored.At present,the research on ammonia refrigeration enterprises in China is mainly focused on the safety of ammonia refrigeration system,the consequence analysis and simulation of liquid ammonia leakage accident,but the research on its overall risk assessment is relatively insufficient.In this context,the paper studies the overall risk of ammonia refrigeration enterprises based on the requirements of accident prevention and enterprise safety management.The main contents and achievements of this paper are described below:(1)Statistics and analysis of ammonia leakage accidents in China from2011 to 2018 show that ammonia leakage accidents in ammonia refrigeration enterprises account for 74.8% of the total number of accidents.However,the study on the overall risk classification of ammonia refrigeration enterprises is insufficient.(2)Based on the characteristics of ammonia refrigeration enterprises industry and the principles of establishing the risk classification index system,according to the accident-causing theory,system safety analysis method and the four-element system as "people,things,management,environment ",combined with the relevant laws,regulations,standards and actual conditions of some ammonia refrigeration enterprises in Nanning City,a risk classification index system of ammonia refrigeration enterprises with two levels of evaluation indexes was constructed.Among them,there are 4 first-level indicators(human factors,inherent risks,management factors,and environmental factors)and 21second-level indicators(average length of service of employees in ammonia-related positions,cultural quality of employees in ammonia-related positions,and personnel holding certificates,etc.).(3)The classical domain and section domain of each secondary index were determined by using the relevant theoretical knowledge of extenics,the risk grading extension evaluation model of ammonia refrigeration enterprises was constructed,and the correlation degree of the overall risk of ammonia refrigeration enterprises on each risk level was determined by using the correlation function.The fuzzy analytic hierarchy process was introduced to determine the weight of each index to reduce the bias caused by people's subjective consciousness when determining the weight.(4)The established extension model of risk classification for ammoniarefrigeration enterprises was applied to access an ammonia refrigeration enterprises,and the overall risk level of the enterprise was concluded to be "low".The evaluation result was consistent with the actual situation,which confirmed the feasibility of applying the model to risk evaluation of ammonia refrigeration enterprises.