LNG Storage Tank Area Safety Protection Distance And Application Research Based On Bleve Accident Risk Field

At present, in the dangerous chemicals equipment accidents of the petrochemical enterprise, lots of accidents resulted from lack of safety protection distance between the dangerous chemicals equipment and its surrounding personnel, equipment, buildings and other protection objects, which resulted in more severe accident consequences, such as significant casualties and property losses. And domestic LNG storage tank area construction is increasingly becoming into the large scale, safety and reliability for LNG storage tank area have been paid widespread attention, among them, one of the problems focused on is the safety protection distance between the LNG storage tank area and the surrounding sensitive area. When carrying out the construction and planning of LNG storage tank area, we need to give priority to the safety protection distance between LNG storage tank area and the surrounding protective goals, if the safety protection distance is not enough, LNG storage tank area should not put into operation. In China, there is yet no special method to determine the safety protection distance of LNG storage tank area. Fire prevention distance mentioned in the relevant standards has certain limitations in the practical applications and we cannot absolutely use it to replace safety protection distance. Therefore, it’s very necessary to analyze and research the safety protection distance determination method of LNG storage tank area.Because LNG is flammable and explosive, if LNG storage tank broke, it can lead to leaking out of a lot of liquefied natural gas, when it meets fire, this will cause the disasters and accidents such as fire or explosion. Among them, one of the most serious accident form is Boiling Liquid Expanding Vapor Explosion(BLEVE) and fireball thermal radiation is the main hazard of BLEVE, which will result in a huge loss to the production and economic development of our country, as well as the serious casualties. Therefore, this paper focuses on analyzing the safety protection distance of LNG storage tank area BLEVE fireball accident. With the introduction of related concepts of risk field, it builds BLEVE fireball accident risk model of LNG storage tank area, and analyzes the safety protection distance of LNG storage tank area on the basis of BLEVE accident risk model.Firstly, this paper analyzed the basic characteristics and harmfulness of LNG, on this basis, carried out the analysis of the risk of LNG storage tank area and found out the possible risk factors for LNG storage tank area. Then it used BLEVE fireball accident model of LNG storage tank area, meanwhile, combined with BLEVE fireball thermal radiation damage criterion in order to analyze the BLEVE accident harm range of LNG storage tank area Besides, it utilized MATLAB software by curve fitting to further obtain the function relation between the fireball thermal radiation and the distance, and adopted the human body vulnerability model to calculate the individual death probability that BLEVE accidents resulted in. Furthermore, the paper used Fault Tree to analyze the occurrence probability of BLEVE accident of LNG storage tank area, according to the actual situation of LNG storage tank area, established BLEVE fault tree, and adopted the minimal path set method to calculate the occurrence probability of top event of BLEVE fault tree. Then the paper referred to Dow Chemical and Mond process methods about the determination method of the safety factor value, and calculated the value of safety compensation coefficient system of LNG tank storage area, including the values of the security awareness compensation coefficient and fire rescue compensation coefficient. Then this paper integrated the occurrence probability of BLEVE accident of LNG storage tank area with the individual death probability which caused the death of personnel and the value of safety compensation coefficient system, referred to the relevant knowledge of the field theory and the establishing process of field model, built the BLEVE accident risk model of LNG storage tank area, calculated risk values of each position in the risk field by the risk field model, and utilized MATLAB software to carry out the numerical simulation of the calculated risk values and draw a risk level isosurface of the risk field. Finally, according to the practices of domestic and foreign risk acceptance criteria and relevant standards, this paper combined them with the actual situation of Chinese LNG storage tank area to determine the risk acceptance criteria of LNG storage tank area, and carried on the contrast analysis with the risk calculated by the risk field model of each position of the LNG storage area, which could adopt the method of making the two equal to obtain the minimum safety protection distance of LNG storage tank area BLEVE accident. Also, this safety protection distance determination method was applied to an engineering example of LNG storage tank area in order to verify its feasibility and reliability.This paper determines the safety protection distance of LNG storage tank area by the risk field, which is a meaningful exploration and provides the certain reference value for the safety protection distance determination of dangerous chemical devices of petrochemical enterprises. However, it is very necessary to combine the method with the actual situation of the scene and improve the method further in order to ensure that the safe protection distance calculated is more reasonable and effective.