壳牌煤气化两起事故的经验分享

不当隔离造成S1103B发生严重安全事故Serious HSSE Incident at S-1103B as Result of

Inadequate System Isolation

Customer Communication Package

Agenda 内容

1.Incident Description

事故描述

2.IncidentClassificationand Analysis

事故分类和分析

3.Key Learning

主要教训

4.System Isolation Standard

系统隔离标准

Incident Description事故描述

1.

2.

3.

4.

5.Timing时间: Dec. 2009Venue地点: SCGP Licensee 某客户What happened事故: Explosion occurred to S1103 B 3h after S/U开车后3小时S1103 B发生爆炸Immediate actions当即措施: operator emergently shut down gasifier 紧急手动停车。Consequences事故后果:

①S1103Bfully damaged 布袋除尘器S1103B完全损坏

②Largeamount of coal powder poured onto the ground 大量煤粉抛向地面

③if somebody had been close to the bag filter then injury or worse could easily have happened幸好现场无人，否则会发生伤亡。

6.Preliminary findings 初步查证

①When client switched the syngas to the shift unit the syngas flew into the LP N2 system because the LP N2 system was not properly isolated from the shift unit. Then the syngas flew back to unit 1100 though LP N2 line and caused the explosion of the S-1103B bag filter. 全场低压氮气与变换及制粉系统联通。因为低压氮气与变换系统隔离不当，合成气导入变换系统后，合成气流入低压氮气系统，然后进入磨煤系统而导致布袋除尘器爆炸。

②Client did not add blind between the LP N2 system and the shift unitbut relied on a single valve to isolate the systems. 在低压氮气和变换系统之间未加盲板，仅靠单一阀门隔离。

③Syngas and coal powder formed an explosive mixture to the explosive limit due to H2 presence. Most likely a static electricity spark built up in this solid handling system ignited the mixture. 合成气进入布袋除尘器后，合成气里的氢、一氧化碳与煤粉及系统内的氧气形成爆炸物。氢气易燃，其混和物的爆炸下限很低，煤粉输送系统很容易形成静电，很可能是静电火花点燃了可燃粉尘/气体爆炸物。

IncidentClassificationand Analysis事故分类和分析1.Type of Incident 事故类别:Explosion &Asset Damage 爆炸及资产损坏

2.Incident RAM Rating –High Risk Potential: P4D, E2D, A3C, R4D; Actual: P0, E1, A3, R4事故分级–高风险潜在风险：人员4D,环境2D, 资产3C，声誉4D；实际：无伤亡，无伤亡，环境1，资产3，声誉43.Immediate Causes直接原因:

①Syngas ingress into S1103B from the shift unit via LP N2 line formed an explosive mixture with the coal dust inside S1103 B变换装置里的合成气进入低压氮气系统后，又进入S1103B,与煤粉形成爆炸粉尘/气体混和物。

②Presence of static electricity during solids handling ignited the explosive mixture inside S1103B 固体输送形成的静电点燃了S1103B里的爆炸混和物。

4.Underlying Causes间接原因:

①Isolation of the LP N2 system from the shift unit/syngas system relied on a single valve instead of using blinds or removal of spool piece

低压氮气与变换系统的隔离未采用盲板或断开的方式，而仅仅依靠单一阀门。

②The N2 fire fighting system relyingon O2 and COmonitoring escalated the fire and explosion process in this incident since more syngas instead of pure N2 was kept feeding to S1103 B once high CO content was detected.氮气消防系统根据测量到的布袋内的氧含量和一氧化碳含量的高低来决定氮气消防流量。此次事故中，一氧化碳含量高，氮气消防流量增加，但此时消防系统送入的恰恰是导致火灾和爆炸事故的合成气，而非纯氮，导致事故升级。

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Key Learning 主要教训

1.All valves leak. HP medium will leak to LP system if they are connected and isolated with valves only. Never rely on valves for system isolation. Air gapping is recommended.

所有阀门都存在内漏。如果高压系统与低压系统相连，而仅用阀门隔离，高压介质会流向低压系统。所以不能依靠阀门担当系统隔离。建议采用断开的隔离方式。

2.Procedures need be adopted to ensure that whenever a unit is started, the systems not in use are properly isolated, for example the LP nitrogen system is positively isolated from the shift unit by dropping the spool piece.需要建立管理程序，当装置开车时，不用的系统需要可靠隔离，比如对于低压氮气系统，应拿掉短节，以确保与变换系统可靠隔离。

3.Correct rating and installation of the rupture discs are crucial. The bag filter need be airtight and O2 content to be kept below 8% or 6%, depending on the coals.The system shall also have a PSV.防爆片的定值和安装非常重要，布袋除尘器气密要合格，根据不同煤种，氧量保持在8%或6%以下。该系统也应考虑设置泻压阀。

4.The bag filter area is also a high risk area when CMD is in operation and requires barricading. A long term solution is required.

布袋除尘器区域是高风险区域，需要区域隔离。需要考虑长期解决放案。

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System Isolation Standard系统隔离标准

No.

1Isolation隔离方式Air

Gapping

断开

Blinding

盲板Examples示例①Removal of a valve or spool piece and fitting of blank flanges to both open ends拆掉阀门或管段，敞口处加盲法兰Advantage优点Reliable可靠Disadvantage缺点①More work and time工作量大，花费时间长②Tightness test required before put back in service due to potential damage to flange surfaces因为可能损坏法兰面，投用前需要作气密试验③New gaskets required每次需要更换垫片①More work and time工作量大，花费时间长②Tightness test required before put back in service due to

potential damage to flange surfaces

因为可能损坏法兰面，投用前需要作气密试验

③New gaskets required每次需要更换垫片

①This method will not be used for liquid hydrocarbon / gas /

nitrogen, toxic material or chemicals isolation for the

purpose of isolation for man entry.

如果人员需要进入容器，而需隔离的介质是液态

碳氢化合物/可燃气体/氮气/其他窒息性气体/有毒

材料或腐蚀性化学品等，不可使用此种隔离方法

②If either of the block valves is found to be passing, this

method will not be used.

如果任一个截止阀存在漏泄，这种隔离方法不得

使用。2①Fitting a blind in addition to valve isolation 在隔离阀后加一块盲板②Fitting a blind or slip plate 在法兰之间加堵板③Turning a spectacle blind to the closed position 八字盲板转到关闭位置①Double block isolation, valves locked closed, with a vent valve open between the isolation valves i.e. double block and bleed (DBB)双截止阀关闭，中间导淋或排空阀开启，阀门上锁。Reliable可靠3DBB双隔离阀+排放阀Easy executionNo damage to flanges and gaskets容易实施，不会损坏法兰面和垫片

4Single

valve

单阀Not recommended 不推荐使用

As general rule, air gapping or blinds are to be used as isolation where there is risk of fire, explosion, poison and asphyxiate. Do not forget isolation of motor radioactive instruments!

如果存在火灾、爆炸、中毒和窒息等风险，一般要求使用物理断开或盲板隔离的系统隔离方式。请勿忘记隔离马达和射源！6

连锁保护的重要性Importance of Safeguarding

Customer Communication Package

Agenda 内容

1.Incident Description

事故描述

2.IncidentClassificationand Analysis

事故分类和分析

3.Preliminary Findings

初步发现

4.Key Learning

主要教训

5.Critical Safeguarding for SCGP

SCGP关键联锁保护

Incident Description事故描述

1.Timing时间: Jan. 2010

2.Venue地点: SCGP Licensee某客户

3.What happened事故: a huge coal powder leakage from V1205A aeration cone and big fire on the gasifier deck near the No. 2 coal burner.

V1205A泄漏大量煤粉，2号煤烧嘴平台处发生大火。

4.Immediate actions当即措施: operator emergently shut down gasifier 90s afterwards. 90秒后紧急手动停车。

5.Consequences事故后果:

①No.2 coal burner fully damaged internally.

2号烧嘴内部完全损坏。

②Coal feed line burned out for roughly 1m.

煤粉管线烧毁约1米。

③Some instruments, cables and control boxes also caught fire and were seriously damaged . 一些仪表、电缆、控制盘着火，严重损坏。

④V1205A aeration cone for line 2 heavily damaged & leakage observed in the flange where N2 was supplied to the aeration cone.

V1205A2号线通气锥严重损坏，通气锥氮气法兰处发生泄漏。

⑤if somebody had been close to the coal burner then injury or worse could easily have happened

幸好现场无人，否则会发生伤亡。

⑥A significant amount of coal powder spilled into the structure. This could easily have been ignited, resulting in a bigger fire and much more damage.

大量煤粉在框架内飞扬，很容易被点燃，造成大火或更大损坏。

Preliminary Findings 初步发现

①Syngas backflowto burner No.2 and coal feedline, resulting in leakage and creating a fire. 合成气倒流进入2号烧嘴和煤粉管线, 造成合成气泄露和大火.

②SCGP coal feed lines have three safeguards against back flow: the 2nd velocity meter near the coal burner, the 2nd density meter near the coal burner and the oxygen/coal ratio based on the 2ndvelocity meter and density meter near the coal burner. For example, if the velocity measured by the 2nd velocity meter drops below 3 m/sec, it automatically trips the burner. SCGP煤管线设有三种防倒流保护：靠近煤烧嘴的第二个速度计和和第二个密度计，以及建立在第二个速度计和密度计基础上的氧煤比。如果第二个速度计流速降到3米/秒以下，自动停烧嘴。

③The 2nd velocity safeguard was in override and more than likely was the 2nd density meter safeguardingalso overridden. 第二个速度计连锁被解除，第二个密度计连锁极可能也被解除。

IncidentClassificationand Analysis事故分类和分析1.

2.

3.Type of Incident 事故类别:Fire & Asset damage 火灾及资产损坏Incident Classification/RAM Rating –High RiskPotential: P4D, A4D, R4D; Actual: P0, A3, R4事故分级–高风险潜在风险：潜在风险：人员4D，资产4D，声誉4D；实际：实际：无伤亡，无伤亡，资产3，声誉4Immediate Causes直接原因:

①

②Failure of the gasket of the flange for HP N2 to the aeration cone of V-1205A resulted in sudden decrease of the pressure in the coal feed line, (leading to back flow to the coal burner and the coal feed line due to override of majority of the safeguarding functions)V1205 A通气锥高压氮气法兰垫片失效，造成煤粉管线内压力突然下降(因为绝大部分联锁保护功能被解除, 造成煤烧嘴和煤管线回流).The safeguards of the coal flow velocity was in override. The density was most likely in override and though O2/C ratio was in operation 煤粉速度联锁保护被解除，密度联锁保护可能被解除，尽管氧煤比联锁保护处于投入状态。

Wrong gasket material.垫片材料错误

Majority of safeguarding in override. 绝大部分连锁被解除

No proper instructions/procedures for overriding safeguarding and risk assessment.解除连锁无适当的管理程序，未进行风险分析

Incorrect manual intervention to avoid tripping of the line.为避免煤线跳车，不当使用手动调节方式Poor HSSE management and philosophy. Do not learn from previous lessons

安全管理和理念不到位，未接受以往教训。

Poor equipment maintenance设备检修不到位。

Under pressure to keep the unit running continuously保持装置连续运行的压力。

114.Underlying Causes间接原因:①②③④⑤⑥⑦

Key Learning 主要教训

1.

2.

3.Safeguarding is crucial for the process safety. If the 2nd velocity, density meter safeguards would have been in operation and no manual intervention would have been done to prevent the line trips as result of O2/C ratio, most likely this would have been adequate to prevent this incident from happening 联锁保护对于工艺安全至关重要。如果第二个速度计、密度计联锁保护处于投入状态,且未对氧煤比进行手动干预，本事故很可能就可以避免。Two kinds of safeguarding for SCGP有两种联锁保护: ①For plant protection located in ESD (UZfunction) which is very critical 用于装置保护，带有UZ，分布在ESD中，非常重要。②For equipment protectionlocated in DCS (USfunction) which is less critical. 用于保护设备，带有US，分布在DCS中，重要性次之。All the UZfunctions located in ESD are very critical and shallnot be overridden. ESD中的所有UZ联锁保护功能非常关键，不应该解除。All safeguarding for flow, pressure, differential pressure, level and flame detection are followed in series by a timer. The timer prevents nuisance trips resulting from a momentarily loss of signal. The timer settings are to be determined during detailed design and/or commissioning.

所有流量、压力、差压、液位和火焰检测都串接一个定时器。这个定时器可以防止因信号瞬间消失而导致误跳车。定时器的定值由详细设计和试车来决定。

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Critical Safeguarding 关键联锁保护

1.The gasifier emergency shutdown system (13UZ-0001)–major incidents

气化炉紧急停车(13UZ-0001)–重大事故

2.The gasifier oxygen supply shutdown systems (13UZ-0002/0003)-back flash of burner flame气化炉氧气供给停车系统(13UZ-0002/0003) -回火危险

3.The slag bath safeguarding system (13UZ-0004)-syngas entering spray ring and supply lines. 渣池连锁保护(13UZ-0004) –合成气进入喷淋环和供水管线

4.The fuel and oxygen system of the start-up burner (13UZ-0005), -SUburner back flash/damage开工烧嘴燃料氧气连锁保护(13UZ-0005), -开工烧嘴回火损坏危险

5.The fuel system of the ignition burner (13UZ-0006)-LPG / air mixture in the gasifier

点火烧嘴燃料系统连锁(13UZ-0006)-在气化炉内形成LPG/空气混和物

6.The gasifier purge logic monitoring system (13UZ-0010)–equipment/explosion incidents气化炉吹扫逻辑监督系统–设备/爆炸事故

7.The coal burner oxygen and coal supply systems (13UZ-0011 through 13UZ-0014). Overheating of burners and gasifier

烧嘴氧煤供应连锁保护(13UZ-0011 ~13UZ-0014). 烧嘴/气化炉过烧

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Coal Burner Emergency Shutdown Syste

ms (13UZ0011/12/13/14)1. 13SZL-0103: too low a coal flow velocity to burner煤粉流速过低–burner front overheating and back flow 2. 13DZL-0102: too low a coal flow density to burner煤粉密度过低 - overheating of burner front and back flow 3. 13PDZL-0127: too low a differential pressure over O2 control valve氧气控制阀差压过低 - back flow 4. 13FZLL-0103: too low an oxygen flow to the burner烧嘴氧气流量太低 - back flow protection 5. 13FZHH-0103: too high an oxygen flow to burner烧嘴氧气流量太高 - too high thermal load of burner 6. 13FZHH-0109: too high oxygen/coal ratio氧煤比太高 - serious over-firing 7. 13PDZL-0133: too low a positive differential pressure between pulverised coal feed vessel and steam/ oxygenline to burner高压粉仓与氧气/蒸气管线正压差太低- back flow protection

8. 13PDZLL-0007: too low a positive differential pressure between oxygen supply and gasifier氧管线与气化炉之间正压差太低 - unstable burner operation or back flow of gasifier content

9. 12LZLL-0104 (via 12UZ-0102): too low level in feed vessel (UNIT 1200) with operational override高压粉仓料位太低 - unstable flow to the burner and back flow protection

10. 13XV-0110: 11. 13XV-0120: 12. 13XV-0108:protection

“Not open’ (13GSH-0110 not present)“Not open” (13GSH-0120 not present)“Not open” (13GSH-0108 not present)Isolation of feed line to prevent back flow. erosion of shutdown valve (leaking afterwards) or unstable operation.阀门磨损(阀门磨损(以后漏粉)以后漏粉)或运行不稳定

13. 13PdZLL-0122: low differential pressure over valve 13XV-0116阀门差压低 present - back flow Because of risk of overheating of burner or gasifier, the burner control system is provided with a number of safeguarding measures因为烧嘴和气化炉存在过烧风险，烧嘴控制系统设置了一系列连锁保护措施14

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