The procedure proposed in this study can be of value to process engineers who design emergency depressurization system in high pressure hydrocarbon processing facilities. By following this procedure, not only the necessity of emergency depressurization system installation can be analyzed qualitatively and quantitatively, but also the key conditions which will be used for system design and equipment and piping material selection can be figured out.
Otherwise, there are several advantages as follows.
1. By using computer program to perform HAZOP Study, time and efforts required can be reduced by building the database necessary for HAZOP Study. And the results of HAZOP Study can be updated and reused easily.
2. By introducing equipment rupture assessment, the necessity of emergency depressurization system installation can be verified quantitatively to enable CAPEX (capital expenditures) decision support.
3. By using dynamic simulator to model emergency depressurization system, the time and efforts can be reduced.
Additionally, this study is expected to be more beneficial research from the point of view of CBA (cost-benefit analysis).
References
[1] Handbook of Fire and Explosion Protection Engineering Principles, second edition, 2011.
[2] CCPS, Layers of Protection Analysis: Simplified process Risk Assessment, New York: Center for Chemical Process Safety in American Institute of Chemical Engineers, 2001.
[3] R.S.Ettouney, M.A.El-Rifai, A.A.Elzoubier, “Emergency venting into redundant pipelines”, Journal of Loss Prevention in the Process Industries vol. 25, pp. 739-745, 2012
[4] G.Montgomery, “How to predict temperatures during gas depressuring”, HYDROCARBON PROCESSING, 1995.
[5] ANSI/API STANDARD 521, “Pressure-relieving and Depressuring Systems”, 5th edition, 2007.
[6] D.A.Crowl, J.F.Louvar, Chemical Process Safety Fundamentals with Applications, second edition, 2002.
[7] J.H.Kim, “Integrated Analysis of Designing Safety Integrity Level during the Life Cycle of Hydroxylamine Production Process”, Master Thesis, Seoul National University, 2013.
[8] K.Kawamura, Y.Naka, T.Fuchino, A.Aoyama, N.Takagi, “HAZOP Support System and Its Use for Operation”, Computer-Aided Chemical Engineering, vol. 25, pp. 1003-1008, 2008.
[9] Guidelines for the Protection of Pressurised Systems Exposed to Fire, SCANDPOWER, 2004.
[10] J.R.Couper, W.R.Penney, J.R.Fair, S.M.Walas, Chemical Process Equipment, second edition, 2009.
[11] Aspen HYSYS Dynamics, User Guide, V7.1, 2009.
[12] K.T.Kim, “A Study on the Design Procedure for Efficient Flare System through Dynamic Analysis of Abnormal Condition”, Doctoral dissertation, Seoul National University, 2012.
[13] “Hydrocracking is an important source of diesel and jet fuel”, Energy Information Administration (EIA), 2013.
[14] “Hydrocracking”, from the website of Chemical and Process
[15] “Hydrocracking”, from the website of citizendium.
[16] J.Scherzer, A.J.Gruia, Hydrocracking Science and Technology, 1st edition, 1996.
[17] “Schematic flow diagram of a typical hydrocracker”, from the website of citizendium.
[18] “Dynamic Depressuring”, Aspen HYSYS, 2011.
Appendix
HAZOP Results of Hydrocracker Plant
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Table1 HAZOP results of node 1 AZOP Work Sheet lant: Hydrocracker ode: Reaction uip. Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. failure stop noF
Tripping of G- 0001, and the feed in surge drum D-0001 will accumulate
D-0001 High LevelOAL2
①LIT-1201 D-0001 By level high alarm, operator can recover
failure stop noF
Tripping of G- 0001, and no liquid flow to E- 0001 Loss of tube side liquid flow across E-0001, but the recycle gas will still continue through the heat exchanger
O A L2 failure stop noF
Tripping of G- 0001, and no liquid flow to F- 0001 Loss of liquid flow through heater F-0001, but the recycle gas will still continue through the heater
O A L2 Adjust the fuel gas flow to the heater failure stop noF
Tripping of G- 0001, and no liquid flow to C- 0001 Loss of liquid flow to the reactor C-0001,but the recycle gas will still continue through the heat exchanger, so no adverse consequence
O A L2
68
Equip. Tag Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. FCV- 0001failure close noF Controller malfunctions and closes FCV- 0001 on the discharge line of pump
Closed discharge when pump is running, the pump will potentially run to shut off condition, damage to pump
O B L2
Minimum continuous flow to be provided in the pump discharge FCV- 0001failure close noF
Controller malfunctions and closes FCV- 0001 on the discharge line of pump
D-0001 High LevelOAL2
①LIT-1201 D-0001 By level high alarm, operator can recover
FCV- 0001failure close noF
Controller malfunctions and closes FCV- 0001 on the discharge line of pump Loss of tubeside liquid flow across E-0001, but the recycle gas will still continue through the heat exchanger
O A L2 FCV- 0001failure close noF
Controller malfunctions and closes FCV- 0001 on the discharge line of pump Loss of liquid flow through heater F-0001, but the recycle gas will still continue through the heater
O A L2 Adjust the fuel gas flow to the heater
69
p. Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. failure close noF Controller malfunctions and closes FCV- 0001 on the discharge line of pump
Loss of liquid flow to the reactor C-0001,but the recycle gas will still continue through the heat exchanger, so no adverse consequence
O A L2 failure openmrF
Controller malfunctions and opens FCV- 0001 on the discharge line of pump Loss of level in the feed surge drum D-0001. In adverse case, loss of suction to the feed pump O B L2
①LIT-1201 D-0001 By level low alarm, operator can recover
Check periodically pump NPSH tube leakageTube leakage
Feed will leak into the effluent side. Potential contamination of reactor effluent. This will lead to off spec product Q A L3 Provide sampling point
70
Equip. Tag Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. F-0001excess burningmrT
Excess burning will cause reactor feed temperature to rise highly There is a potential of runaway reactions inside the reactor, the reactor temperature will rise extremely to cause reactor rupture.
O C L2
1. TE-0005 2.TE-0001 3.TE-0003 4.The interlock ZC-0001 will close the feed control valve FCV- 0001 . 5.C-0001 By temperature high alarm , operator can recover
1.Connect interlock system to fuel gas supply system for tripping heater 2.Install emergency quench system 3.Install emergency depressurization system C-0001ruptureFire case
The strength of C-0001 construction material will be weakened and vessel rupture will occur S B L2 Install emergency depressurization system
71
Table2 HAZOP results of node 2 AZOP Work Sheet lant: Hydrocracker ode: Separation p. Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. 01failure stop lsP,no F
Tripping of compressor K- 0001 Potential reverse flow from liquid feed line to recycle gas header. Potential damage to compressor K-0001
O BL2FIT-0007 Install check valve upstream of the injection point
72
Equip. Tag Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. K-0001failure stop lsP,no F
Tripping of compressor K- 0001 Recycle gas pressure is lost. There is a potential of runaway reactions inside the reactor. Reactor temperature will rise extremely to cause reactor rupture
O C L2
1. FIT-0007 2.TE-0003 3.TE-0001 4.TE-0005 5.Interlock ZC-0001 will close liquid feed control valve FCV- 0001. 6.Make up H2 will compensate loss of pressure to some extent 7.C-0001 by high temperature alarm, operator can cover
1.Connect interlock system to fuel gas supply system for tripping heater 2.Install emergency quench system for reactor 3.Install emergency depressurization system K-0001failure stop lsP,no F
Tripping of compressor K- 0001 Recycle gas flow through E- 0003 will be reduced, potential high temperature on the reactor effluent side, but no adverse consequence
O AL2FIT-0007 Add high temperature alarm on TI-0006
73
p. Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. failure close noF
Controller malfunctions and closes FCV- 0016 Loss of recycle gas flow to reactor. There is a potential of runaway reactions inside the reactor. Reactor temperature will rise extremely to cause reactor rupture
O C L2
1.TE-0003 2.TE-0001 3.TE-0005 4.The interlock ZC-0001 will close liquid feed control valve FCV- 0001 5.C-0001 by high temperature alarm, operator can cover
1. Connect interlock system to fuel gas supply system for tripping heater 2. Install emergency quench system for reactor 3.Install emergency depressurization system failure close noF
Controller malfunctions and closes FCV- 0016 Loss of recycle gas flow through E-0003, potential high temperature on the reactor effluent side, damage to the heat exchanger E-0003 tube
O B L2
Add high temperature alarm on TI-0006, and check whether the heat exchanger E- 0003 is designed for dry running condition
74
Equip. Tag Fail. ModeDevi.Cause Consequence S/O/ E/QLevelFreq.Counter measure Recommend. FCV- 0016failure openmrF Controller malfunctions and opens FCV- 0016 Excess recycle gas flow to the reactor C-0001, but no impact on the operation of the reactor is likely.
O A L2 FCV- 0016failure openmrF
Controller malfunctions and opens FCV- 0016 Excess recycle gas flow through E-0003, potential low temperature on the reactor effluent side, but no adverse consequence
O A L2 D-0002 D-0003 C-0002 D-0004
ruptureFire case
The strength of equipment construction material will be weakened and equipment rupture will occur S B L2 Install emergency depressurization system
초 록
수소 첨가 분해 공장과 같은 발열반응이 동반된 고압 탄화수소 처리시설에서는 일반적으로 인화성, 가연성 또는 독성 유체를 취급하기 때문에 화재, 폭발, 장비 파열과 유독 가스 방출 등 심각한 위험성을 초래할 수 있다. 이러한 사건에서의 잠재적인 손실은 비상 정지 (ESD) 시스템과 비상 감압 시스템을 이용하여 효율적으로 예방할 수 있다.
기존의 연구에서는 감압 중 비상 감압 시스템을 통과하는 가스 유량과 장비 및 배관에서의 온도를 예측하기 위한 다양한 모델을 제시하였지만, 이때의 비상 감압 시스템은 이미 공장에 설치되어 있다는 전제로 수행되었다. 또한 산업에서 비상 감압 시스템의 응용은 많은 문헌들이 가이드라인을 많이 제공하였음에도 불구하고 단지 화재 혹은 다른 과열 시나리오로 인한 장비 파열의 결과를 고려하기 때문에 경험적이고, 허가자(licensor)의 디자인에 대한 의존도가 높을 뿐만 아니라 고려되는 운전조건은 표준화가 되어있지 않기 때문에 보다 높은 정확도가 요구된다. 이러한 단점들을 보완하기 위해 본 연구에서는 비상 감압 시스템의 설치를 포함하는 통합 설계 절차를 제안하였다.
첫 번째로 화재, 발열 폭주 반응 혹은 다른 과열 시나리오와 관련된 위험을 알아내기 위해 정성적 위험성 평가-HAZOP Study 수행한다. 본 연구에서는 HAZOP Study을 수행하기 위해 상업용 컴퓨터 프로그램 TechmasNavi® 시리즈를 사용하였다. 이 프로그램을 사용하면 기존의 HAZOP Study을 수행할 때의 필요한 시간과 노력을 줄일 수 있고 위험성 평가 보고서에 대한 데이터베이스를 구축할 수 있다. HAZOP Study을 통해 비상 감압 시스템 설치의 필요성을 정성적으로 논의할 수