چکیده:
With regard to a study on accidents in chemical industries, approximately 2.3 percent of the damage is related to explosion. The explosions happen in no time and there will be no opportunity to avoid them, therefore, explosion damage is more than fire damage. Fire and explosion risks always exist in gas and oil industries. The present paper intends to assess fie, explosion, and toxicity risks based on MOND and DOW indices, and then compare the indices with each other regarding fuzzy logic. The last version of fire, explosion, and toxicity index introduction was used in the process subunits in northern Iso- max unit of Tehran oil refinery. The important process subunits in northern Iso-max unit were recognized based on process effective factors such as pressure, temperature, and value of the materials. In the next step, factors affecting fire, explosion and toxicity index (TF& EI) were recognized and estimated. Moreover, (TF& EI) index was calculated for each subunit, and then time duration and real rate of damage and their effects were studied. The results indicated that 6 subunits out of 8 had high fire, explosion and toxicity degree of risk. One of the subunits had high and the other had medium degree of risk. 2V432 catalytic conversion reactor is the most important subunit of northern Iso- max unit; it has the highest rank of fire, explosion, and toxicity risk; its fire risk equals 232.4 and its toxicity risk equals 49.3. 2H432 reactor feed heater with 124.8 degree of fire risk and 7.2 degree of toxicity risk has the minimum fire risk and the medium toxicity risk, respectively. The research shows that fire, explosion and toxicity index is a proper method to determine the most and least hazardous points of an industry. Catalytic conversion reactor is the most critical unit regarding fire, explosion, and toxicity.
خلاصه ماشینی:
"Table 6: determining fire and explosion index based on material factor, general and special risks of the process in reactor feed heater 2H-432 (AICHE, 1994) Operating temperature of the heater (389 degree of centigrade) is higher than inflammation point and gas oil self- burning point.
With regard to temperature condition higher than 60 degree of centigrade in process units under investigation, the results of tables 4 and 5 are used for all factors except for the high and low pressure separators and the need for correcting their material factors.
The index includes qualitative and quantitative factors and is calculated based on the following formula: (4) A B 1 m Q H E t 1 p 100 1000 300 The overall risk is used to compare the unit with all kinds of risks and its formula is obtained as follows: (5) R D1 F U E A 103 Toxicity index of unit (U): it is obtained from multiplying internal explosion by hygienic risks factor: (6) U T E 100 Table 8: indicates results of the above formulas calculations Table 10: MOND results based on the experts’ opinion in recycle splitter feed flash drum 2V-437 Toxicity risks T Material area risks Value of risks Special risks of the process S General risks of the process P Special risks of the process M Material factor B MOND index Scoring N H L Q K 100 6.
5 155 70 485 21 EX3 Table 15: form of MOND fire, explosion, toxicity risk analysis in diesel stripper 2V-444 Table 12: MOND results based on the experts’ opinion in low reactor feed heater 2H-432 Toxicity risks T Material area risks Value of risks Special risks of the process S General risks of the process P Special risks of the process M Material factor B MOND index Scoring N H L Q K 95 9."