HAZOP-3危險(xiǎn)與可操作性ppt課件

1、Loss PreventionLoss prevention in chemical industries involve:Identification and assessment of major hazardsControl of hazards by containment, substitution, improved maintenanceControl of process by utilizing automatic control, relief system , interlock, alarmLimitation of loss when accident happens

2、0;Loss PreventionThe major formalized techniques are:Hazards and Operability (HAZOP)Fault Tree Analysis (FTA)Failure mode-and-effect analysis (FMEA)Safety indexesSafety audit1;What is HAZOP? Systematic technique to IDENTIFY potential HAZard and OPerating problems A qualitative technique based on “gu

3、ide-words” to help provoke thoughts about the way deviations from the intended operating conditions can lead to hazardous situations or operability problems HAZOP is basically for safety Considerable engineering insight is involved2;3HAZOP study are applied during :Normal operationForeseeable change

4、s in operation, e.g. upgrading, reduced output, plant start-up and shut-downSuitability of plant materials, equipment and instrumentationProvision for failure of plant services, e. g . steam, electricity, cooling waterProvision for maintenance.HAZOP Study3;HAZOP Team Team Leader Team Secretary Proce

5、ss Engineer Mechanical Engineer Commissioning/Operations Engineer/Manager Instrument EngineerHAZOP studies are carried out using a brainstorming approach by a team, chaired and coordinated by a qualified person experienced in HAZOPs:4;5 H A Z O P i s a s y s t e m a t i c , r e a s o n a b l y compr

6、ehensive and flexible. It gives good identification of cause and excellent identification of critical deviations. The use of keywords is effective and the whole group is able to participate. HAZOP is an excellent well-proven method for studying large plant in a specific manner.Strength of HAZOP5;6HA

7、ZOP is very time consuming and can be laborious with a tendency for boredom for analysts.It tends to be hardware-oriented and process-oriented, although the technique should be amenable to human error application.HAZOP does not identify all causes of deviations and therefore omits many scenarios.Wea

8、kness of HAZOP6;NONE /Noe.g., NO FLOW caused by blockage; pump failure; valve closed or jammed : REVERSE Opposite, e.g., REVERSE FLOW caused by pump failureMORE Quantitative increase, e.g., MORE FLOW, Temp, LESS Quantitative increase, e.g., LESS FLOW, Temp,As Well AsQualitative increase, e.g. impuri

9、ty.PART OF Qualitative decrease, Change in composition high or low concentration of mixture; additional reactions in reactor or other location ; feed change.Other thanNothing of the intent happen, completely different occursGuide Words7;HAZOP StepsThese guide words are applied to flow, temperature,

10、pressure, liquid level and composition.Deviation of these variables from normal operation is consideredThe consequences of these deviations on the process is then assessed.The measures needed to correct these consequences are then establishedThis process enables a comprehensive evaluation ofHazard c

11、ontrol systems and produces recommendations for any necessary modifications. The overall result is a reduction in both hazards and potential operational problems8;9;HAZOP STUDY REPORT FORMTITLE : Sheet 1 ofLINE 1 : DEVIATIONCAUSESCONSEQUENCESEXISTING PROVISIONSACTIONS, QUESTIONS OR RECOMMENDATIONSHA

12、ZOP Study Form10;Storage Tank11;HAZOP Table - levelActionSafe guardConsequencesDeviationCauseLevelEstimate release quantityLIAPotential fireReagent release1. Rupture discharge lineLessEstimate release quantityLIAPotential fireReagent release2. V3 open or brokenV1 protectionLIAPotential fireReagent r

13、elease3. V1 open or brokenWhat external event cause tank ruptureLIAPotential fireReagent release4. Tank ruptureDoes RV1 allow for liquid release?Consider high level alarm shutoffLIAReagent release via RV1Overfill5. Too much truck unloadMoreConsider check valve at pump dischargeConsider high level al

14、arm shutoff at feedLIAReagent release via RV1Overfill6. Reverse flow from processSame as lessNO12;HAZOP Table - pressurePressureConsider independent PLAPICAPotential fireReagent release9. Break in nitrogen or flare lineLessConsider vacuum break valvePICAReagent releaseTank implode10. Lose nitrogenCo

15、nsider PALPICAReagent releaseTank implodes11. PV2 fails closedTank not designed for vacuumReagent releaseTank implodes12. PICA fails, closing PV2What PV1 and RV1 capacityPICATank rupture if RV1 failsReagent release via RV113. PICA fails, closing PV1MoreConsider independent PAHPICATank rupture if RV1

16、 failsReagent release via RV114. PV1 fails closedIs V7 locked openPICATank rupture if RV1 failsReagent release via RV115. V7 closedConsider second high level shutoffPICATank rupture if RV1 failsTruck unload16. Overfill tankWhat prevent high temp of feedConsider PAHPICATank rupture if RV1 failsReagen

17、t release in RV117. Temperature of inlet higher than normalConsider PAHConsider sampling before unloadingPICATank rupture if RV1 failsReagent release in RV118. Volatile impurities in feed13;Hazop Table - compositionActionSafe guardConsequencesDeviationCauseCompositionConsider sampling before unloadT

18、ank rupturePossible reaction7. Wrong reagentOther thanAre other material delivered in tankAre unloading connection differentProblem in reactor8. Impurities in reagentAs well as14;HAZOP Table - TemperatureTemperatureWhat are temp limits of tankThermal stress on tankPossible vacuum19. Temperature of i

19、nlet cooler than usualLessWhat are pressure limits of tankThermal stress on tankSee 9-1220. Low tank pressureWhat are temp limits on tankThermal stress on tankSee 1721. temperature of inlet is higher than usualHighWhat could cause external fireWhat are fire protection capabilitiesIs fire protection

20、adequateReagent releaseTank fails22. external fire15;Preliminary HAZOP ExampleTCCooling CoilsMonomerFeedCooling Water to SewerCooling Water InThermocoupleRefer to reactor system shown. The reaction is exothermic. A cooling system is provided to remove the excess energy of reaction. In the event of c

21、ooling function is lost, the temperature of reactor would increase. This would lead to an increase in reaction rate leading to additional energy release. The result could be a runaway reaction with pressures exceeding the bursting pressure of the reactor. The temperature within the reactor is measur

22、ed and is used to control the cooling water flow rate by a valve.Perform HAZOP Study 16;Preliminary HAZOP on ReactorGuide WordDeviationCauses ConsequencesActionNONo coolingCooling water valve malfunctionTemperature increase in reactorInstall high temperature alarm (TAH)REVERSEReverse cooling flowFai

23、lure of water source resulting in backward flowLess cooling, possible runaway reactionInstall check valveMOREMore cooling flowControl valve failure, operator fails to take action on alarmToo much cooling, reactor coolInstruct operators on proceduresAS WELL ASReactor product in coilsMore pressure in

24、reactorOff-spec productCheck maintenance procedures and schedulesOTHER THANAnother material besides cooling waterWater source contaminatedMay be cooling inefffective and effect on the reactionIf less cooling, TAH will detect. If detected, isolate water source. Back up water source?17;Case Study Shel

25、l & Tube Heat ExchangerUsing relevant guide works, perform HAZOP study on shell & tube heat exchangerProcessfluidCooling water18;HAZOP on Heat Exchanger Guide WordDeviationCauses ConsequencesActionNONENo cooling water flowFailure of inlet cooling water valve to openProcess fluid temperature

26、is not lowered accordinglyInstall Temperature indicator before and after the process fluid lineInstall TAHMOREMore cooling water flowFailure of inlet cooling water valve to closeOutput of Process fluid temperature too lowInstall Temperature indicator before and after process fluid lineInstall TALLES

27、SLess cooling waterPipe leakageProcess fluid temperature too lowInstallation of flow meterREVERSEReverse process fluid flowFailure of process fluid inlet valveProduct off setInstall check valve (whether it is crucial have to check?)CONTAMINATIONProcess fluid contaminationContamination in cooling wat

28、erOutlet temperature too lowProper maintenance and operator alert19;Documents needed for HAZOP Study For Preliminary HAZOP Process Flow Sheet ( PFS or PFD ) Description of the Process For Detailed HAZOP Piping and Instrumentation Diagram ( P & ID ) Process Calculations Process Data Sheets Instru

29、ment Data Sheets Interlock Schedules Layout Requirements Hazardous Area Classification Description of the Process20;Planning for HAZOPAdditional required information: Safety procedures documents Relief/venting philosophy Chemical involved Piping specifications Previous HAZOP report21;Planning for HA

30、ZOP Carry out the study Record the results (may need a secretary) Follow-up of actions noted final report contain resolution of all recommended actions must appoint someone as leader to check progress of action team may meet again if answers to questions do not simply lead to an action team may meet

31、 again if significant design changes in interim report22;Responsibility of HAZOP Team MembersHAZOP leader Plan sessions and timetable Control discussion Limit discussion Encourage team to draw conclusion Ensure secretary has time for taking note Keep team in focus Encourage imagination of team membe

32、rs Motivate members Discourage recriminations Judge importance issues23;HAZOP Secretary Take adequate notes Record documentations Inform leader if more time required in taking notes If unclear, check wording before writing Produce interim lists of recommendations Produce draft report of study Check

33、progress of chase action Produce final reportResponsibility of HAZOP TeamMembers24;Process Engineer Provide a simple description Provide design intention for each process unit Provide information on process conditions and design conditions Provide a simple description Provide design intention for each process unit Provide information on process conditions and design conditionsResponsibility of HAZOP TeamMembers25;Mechanical Design Engineer Provide specification details P