Preview only show first 10 pages with watermark. For full document please download

Hazop Reactor (autosaved).docx

   EMBED


Share

Transcript

HAZOP ANALYSIS ON ETHYLENE OXIDE REACTOR (R100) The Ethylene Oxide reactor converts ethylene to ethylene oxide using oxygen and a sliver catalyst. The operating temperature of the reactor is 280 o C and operating pressure is 8 atm. Ethylene oxide is very dangerous, carcinogenic, flammable and explosive. hen it reaches its decomposition temperature of approximately !00 o C, a very deadly explosion may occur.  Figure 1: Simple Diagram Diagram Showing Showing Ethylene Ethylene Oxide Reactor Reactor Streams Streams "#$ %"ac&%flo' $revention ()on%*eturn +alve +alve Oxygen and ethylene is combined and forms the feed stream. Oxygen inlet concentration and ethylene inlet concentration is dependent on the oxygen and ethylene supply respectively as sho'n in the diagram. The combined feed rate, feed compositions and coolant streams 'ill be analysed. The reactor products stream only needs a non%return valve to prevent bac&flo' of reactor products to the reactor. Deviations Property Possible Causes Possible Consequences (Guide Words)  )o Oy*en Inlet COMBI!D "!!D #O #$! R!%C#OR (R&') Control valve Technological Technological $roblem. • • Concentration failure. Ethylene Oxide Conversion (EO is 0. -ore Oy*en Inlet • Concentration Control valve • failed to close Thermal runa'ay effect (*eactor Temperature Temperature ncrease and possible explosion due to Ethylene Oxide decomposition. /ess Oy*en Inlet Other Than Concentration Oy*en Inlet • Control valve • failed to open rong reagent Concentration or ra' material. • Technological Technological $roblem and • Conversion is too lo'. +essel *upture #ormation of undesirable • • $roducts. ecreased conversion Technological Technological $roblem in • *eactor  Technological Technological $roblem and • 1s ell 1s Oy*en Inlet • mpurities in • ra' material Ethylene Concentration  )o !t+ylene Inlet Concentration  pipeline may be • conversion is ero. clogged. Control valve failure. -ore !t+ylene Inlet Concentration • Control valve • failed to close 1 very high 't. 3 of ethylene may form explosive mixtures • of hydrocarbon and oxygen. /o' selectivity. /ess !t+ylene Inlet Other Than Concentration !t+ylene Inlet • Control valve • failed to open rong reagent Concentration or ra' material. • Technological Technological $roblem and • Conversion is too lo' +essel *upture #ormation of undesirable • • $roducts. ecreased conversion Technological Technological $roblem in • *eactor  /oss of feed to reaction section • 1s ell 1s !t+ylene Inlet  )o Concentration "lo, • mpurities in • ra' material #lo' Controller • failure. /ine fracture. /ine bloc&age. • #lo' Controller • failed to close /o' flo' • -ore "lo, and no output • • ncreased EO Conversion. 4igh concentrations of ethylene oxide and oxygen controller valve leading to explosive mixtures.  bypass failed to /ess 1s ell 1s "lo, "lo, • close. #lo' Controller • /ess EO Conversion • failed to open ater • Out of spec. supply Contamination mpurities rong #eed • • ecreased conversion. ncreased formation of • undesirable products This may form explosive • Other Than "lo, • elivered *everse "lo, • $ump failure, non%return valve mixtures since ethylene is failure, flammable and explosive in the • -ore #emperature • • Over%  presence of high levels of  pressurisation of  oxygen. reactor. Temperature • O2 concentrations increases Controller and forms potential explosive #ailure. External #ire. mixture of hydrocarbons and • oxygen. ecreased conversion and • selectivity. ncreased *eaction Temperature Temperature leading to runa'ay effect. /ess #emperature • Temperature Controller • • ecreased 5electivity. /o' $ressure. #ailure 4igher COO-IG (COO-%#) .#R!%M P%..IG #$RO/G$ R!%C#OR ( Inlet and Outlet Cooling 'ater Thermal runa'ay effect and • • #emperature valve  possible explosion malfunction or /o'er  Inlet and Outlet • #emperature failure. Control valve • failure, operator The temperature of the reactor may become very cool fails to ta&e action on alarm  )o "lo, • Cooling 'ater valve or flo' controller • malfunction. Cooling 'ater service failure. • *una'ay effect and possible explosion -ore /ess "lo, "lo, • • • • Control valve • The reactor becomes very cool failure, operator and reactant concentration fails to ta&e  builds up and potential action on alarm. runa'ay effect on heating. $ipe /ea&age. Temporary • Temperature Temperature of process fluid ater 5ource • remains constant or increases Thermal runa'ay effect • /ess Cooling, $otential #ailure. $artially clogged cooling line. $art of  "lo, • $artially clogged cooling 1s ell 1s "lo, • line. Contamination runa'ay effect. • ecreased Conversion. • /ess cooling, runa'ay effect ($resence of *eactor  product in *everse "lo, • cooling tubes #ailure of 'ater source or high  bac&pressure resulting in  bac&'ard flo' and explosion -ore #emperature R!%C#OR PROD/C#. -!%0IG #$! R!%C#OR (R&') Temperature O2 concentrations increases • • • • Controller and forms potential explosive #ailure. External #ire. 4igh *eaction mixture of hydrocarbons and • Temperature. oxygen. ncreased Ethylene Oxide Temperature Temperature leading to runa'ay effect. /ess #emperature • Temperature • /o' *eactor $ressure. Controller  )o "lo, • • • • #ailure #lo' Controller • failure. /ine fracture. #ull /ine  )o production of ethylene oxide.  bloc&age. rong Catalyst or Catalyst is fully consumed. -ore "lo, • #eed #lo' • -ore production of ethylene • oxide. 4igh concentrations of Controller failed • to close. /o' feed flo' ethylene oxide and oxygen controller valve leading to explosive mixtures.  bypass failed to /ess "lo, • close. #eed #lo' • Controller failed 1s ell 1s "lo, • • Other Than "lo, • to open ater Contamination mpurities rong #eed oxide. • Out of spec. supply to the reactor. • ecreased Ethylene oxide •  production. 5tream may contain a large elivered to the *eactor  /ess production of Ethylene amount of undesirable *everse "lo, • • $ump failure, •  products. This may form explosive non%return valve mixtures since ethylene is failure, Over% flammable and explosive in the  presence of high levels of  pressurisation of  oxygen. reactor. -ore Reactor Pressure OP!R%#IG CODI#IO. O" R!%C#OR (R&') ncreased steam *educed 6ield. • • #ormation of undesirable • flo' rate. *elief valve •  products. evelopment of Temperature Temperature • fails closed. 7radients 'ith localied hot spots leading to impairment of the catalyst to produce /ess Reactor Pressure • *elease valve • fails open. #illing hose • ethylene oxide. +essel overpressure or rupture. • ecreased Conversion. • O2 concentrations increases ruptures. -ore #emperature • • Temperature Controller and forms potential explosive #ailure. External #ire. mixture of hydrocarbons and oxygen. • ecreased conversion and • selectivity. ncreased *eaction Temperature Temperature leading to /ess #emperature • Temperature Controller #ailure • • runa'ay effect. ecreased 5electivity. /o' $ressure. Thermal runa'ay 1n exothermic reaction can lead to thermal runa'ay, 'hich begins 'hen the heat produced  by the reaction exceeds the heat removed. The surplus heat heat raises the temperature of the reaction mass, 'hich causes the rate of reaction to increase. This in turn accelerates the rate of heat production. Thermal runa'ay can occur because, as the temperature increases, the rate at 'hich heat is removed increases linearly but the rate at 'hich heat is produced increases exponentially. Once control of the reaction is lost, temperature can rise rapidly leaving little time for correction. The reaction vessel may be at ris& from over%pressurisation due to violent boiling or rapid gas generation. Executive temperatures may initiate secondary, more haardous runa'ays or decompositions. 1n over%pressure may result in the plant failing catastrophically resulting in blast or missile damage. 1 release of flammable materials from the process could result in a fire or an explosion in the 'or&room. 4ot liuors and toxic materials may contaminate the 'or&place or generate a toxic cloud that may spread off%site. There can be serious ris& of in9uries, even death, to plant operators, and the general public and the local environment may be harmed. 1t best, a runa'ay cause loss and disruption of  production, at 'orst it has the potential for a ma9or accident.