Delayed Coker Automation & Interlocks

Delayed Coker Automation & Interlocks a Presented by Mitch Moloney of ExxonMobil @ coking.com April-2005 MJ Moloney - ExxonMobil April-2005 coking.com 0

Automation & Interlocks @ ExxonMobil - Background We have 8 sites and 12 Delayed Cokers 3 sites (5 cokers) will be fully automated & interlocked by year end + Baton Rouge in response to a fire & fatality that resulted from opening feed to an open drum => They completed all three cokers prior to the 2000 merger + Baytown in 2001 because they knew it was the right thing to do + Jose Upgrader by YE2005 => justified using financially-based risk review => Adding 4 additional MOV s and PLC interlocking all valves MJ Moloney - ExxonMobil April-2005 coking.com 1

Automation & Interlocks @ ExxonMobil - Development => That leaves 5 sites (7 cokers) with manual LOTO operations in our circuit Beaumont, Campana, Chalmette No 1 & 2, Joliet, Torrance North & South => Our Beaumont Coker is blazing the trail - 8 drums, 48 kb/d of Maya resid on 12-hr cycle - Almost all valves are manually-operated - Rely on procedures, 2-person checking and Lock-Out/Tag-Out protocol => Automation & Interlock review is part of a large Safety Upgrade Project - Risk-based review (Safety, Environmental, Financial & Public Disruption) - Risk is converted to a quantified probability - Severity & Probability yield Unacceptable, Gray Area or Acceptable MJ Moloney - ExxonMobil April-2005 coking.com 2

Top Water Vents Top Water SP-2A SP-2B SP-1A SP-1B D-1301A SP-4A SP-4B D-1301B SP-3A To Warm-up Drum SP-8A SP-8B To Warm-up Drum To Main Fractionator Feed Inventory SP-7A SP-5A SP-Switch SP-7B Blowdown SP-6A SP-6B Drain Steam Steam Drain Resid Water Water MJ Moloney - ExxonMobil April-2005 coking.com 3

=> Feed & Switch Valves => Switch & Recirculation Valves => Feed & Utility Header Valves => Drain & Warm-Up Condensate Valves => Overhead Vapor Valves => Blowdown Vapor Valves => Vent Valves => Antifoam Valves => PRV Block Valves => Top Water Valves => Water Over Valves MJ Moloney - ExxonMobil April-2005 coking.com 4

Delayed Coker Industry Safety Database Assessing the Risk Probability (1) Assessment of Industry Accidents (2) Review of Plant Safety History (3) Open discussion with operators to determine how often they have made mistakes in routine structure valve operations (4) Risk goes up with high turnover of operations force => need to consider the lowest common denominator Human Error Potential (1) Level of Stress Complexity of Task Simplest Routine and Simple Routine, Require Care Complicated, nonroutine, other duties required Low 1 in 10,000 1 in 1,000 1 in 100 1 in 10 Moderate 1 in 1,000 1 in 100 5 in 100 3 in 10 Emergency, High Stress 1 in 100 1 in 10 to 1in 1 25 in 100 to 1 in 1 1 in 1 Note 1: Generic human error for various levels of stress and complexity of task. MJ Moloney - ExxonMobil April-2005 coking.com 5

Delayed Coker Industry Safety Database Optimized Base Case Manual or automatic valves that are controlled with LOTO procedures and two-person verification Double block valve arrangement on main hydrocarbon process flows - isolating hydrocarbon from the atmosphere and an open coke drum Proper barrier steam operation is a key element to a reliable double block: - Feed & Switch Spool - Overhead Vapor Spool - Overhead Blowdown Vapor Spool - Recirculation Valve & Switch Spool Leaking valves are assumed to be open 10%, worst case, given coking service MJ Moloney - ExxonMobil April-2005 coking.com 6

Feed & Switch Valves Risk of Switching to Open Drum Risk of Switching against a Closed Block Risk of Switching into a Leaking Block Valve => Severity & Base Probability are high enough (>1 in 10,000) to justify reducing the probability to less than 1 in 10,000 Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 7

Recirculation & Switch Valves Risk of Switching against a Closed Block Risk of Coking/Plugging Recirculation Line Risk of Unit Upset => Severity is medium to low; Base Probability is high (1 in 100); justifying reduction in probability to less than 1 in 1000 Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 8

Feed & Utility Header Valves Risk of Cracking Resid to: -Open Drain - Blowdown System, Cooling or Draining Drum Risk of Resid to Utility Systems Risk of Water to on-oil Drum => Severity & Base Probability are high enough (>1 in 10,000) to justify reducing the probability to less than 1 in 10,000 Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 9

Drain & Warm-Up Condensate Valves Risk of Coke Drum Vapors to Open Drain - Possibility of Fire & H 2 S Exposure & Environmental Release Risk of Leaking Coke Drum Vapors to Open Drain => Severity lower than feed valve event, but depends on drain disposition and activities near the drain line outlet; base probability is high (>1 in 10,000), justifying probability reduction to less than 1 in 10,000 Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 10

Overhead Vapor Valves to Main Fractionator Risk of 800ºF HC Vapors with high H 2 S to Open Drum Risk of Leaking Coke Drum Vapors to Open Drum => Severity is highest from safety, environmental and financial standpoints, but base probability is low (>1 in 10,000); however, the combination justifies probability reduction to less than 1 in 10,000 Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 11

Blowdown Vapor Valves Risk of Hot HC Vapors with high H 2 S & Steam to Open Drum Risk of Leaking Coke Drum HC & H 2 S to Open Drum => Severity is lower from safety and financial standpoints, base probability is still >1 in 10,000; which falls into the gray area and greatly depends on existing facilities in place and your assessment of their operation If MOV s are already in place, no-brainer to interlock If Manual, need to look at other advantages of automating - eliminate single block, ergonomics & manpower Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 12

Vent Valves Risk of 800 ºF HC and H 2 S to the atmosphere + Fire, Injury & Environmental Incident Risk of Coke Drum Damage, if closed during draining + Significant financial loss => Severity is highest; base probability is >1 in 10,000; however, the combination justifies probability reduction to less than 1 in 10,000 Note: Most new facilities are required to provide a reliable double block design from an environmental standpoint Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 13

Antifoam Valves Risk of cold antifoam carrier (LCGO or HCGO) contacting 200ºF coke in an open drum => Severity is low; base probability is greater than >1 in 10,000 Note: No automation or PLC interlocks provided Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 14

Coke Drum PRV s Risk of hydrocarbon vapors & H 2 S leaking from the discharge side to the open coke drum + Fire, Injury & Environmental Incident Safety Risk is a strong function of the discharge location - Flare (1-3 psig) -Blowdown System (1-30 psig) - Main Fractionator (20-65 psig) Mitigation Steps - Industrial Hygiene vapor sniffing -LOTO of discharge valve - Discharge valve interlocking Note: State Environmental agencies are starting to require closure of the discharge valve when the coke drum is open MJ Moloney - ExxonMobil April-2005 coking.com 15

Top Water Valves Risk of 200-400 gpm of water to live coke drum => results in severe unit upset and financial loss => Severity & Base Probability are high enough (> 1 in 10,000) to justify reducing the probability to less than 1 in 10,000 Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 16

Water Over Valves Risk of Blowdown or HC Vapors to Water Over Disposition, which is usually the coke pit or pad or maze - Risk is very dependent on base valve arrangement and if there is a common valve for BD and water over => Severity is low from safety and financial standpoints, base probability is still >1 in 10,000; which falls into the gray area and greatly depends on existing facilities in place and your assessment of their operation Base probability is defined as valves that are controlled with LOTO procedures and two-person verification MJ Moloney - ExxonMobil April-2005 coking.com 17

How do we Reduce the Probability of Incorrect Valve Movement to less than 1 in 10,000? Based on ExxonMobil analysis: - Use of automatically-controlled valves & a redundant Programmable Logic Computer (PLC) for most of the coke drum valves -Why? => Because it is the only design which gives you a reliable shift in probability of one to two orders of magnitude ( 10-100) versus the optimized base case - Acceptable valve automation: + Motor and/or hydraulic actuators - Acceptable PLC s: + Triconics & Allen-Bradley Control Logix MJ Moloney - ExxonMobil April-2005 coking.com 18

Valve Interlock System Availability Based on ExxonMobil analysis: - Delayed Coker Interlocks do NOT meet the definition of a Safety Instrumented System (SIS), consists of: the instrumentation or controls that are installed for the purpose of mitigating the hazard or bringing the process to a safe state in the event of a process upset. An SIS is used for any process in which the process hazards analysis has determined that the mechanical integrity of the process equipment, the process control, and other protective equipment are insufficient to mitigate the potential hazard. Heater Shutdown, Reactor Quench, HIPS, & Emergency Isolation are examples of SIS s - They are passive systems waiting for a signal prior to acting As a result SIL (Safety Integrity Level) is not applied - We require a 97% availability factor MJ Moloney - ExxonMobil April-2005 coking.com 19

Valve Interlock System Availability (cont d) Coker Interlock Systems are tested on an continual basis - Valve position indication consistency checking is needed (e.g., MOV s have position contacts for open & closed) Basic PLC Requirements: - Redundant Processors - Redundant Power Supply (Primary on UPS) - Environment conditioning system alarm - Self-testing and systems diagnostics - 1-0-0-2 redundant architecture for the PLC - Failure of communications to Central Control building shall not affect PLC operations - Input/output modules (the PLC) shall have redundant communications MJ Moloney - ExxonMobil April-2005 coking.com 20

Valve Interlock Systems - Miscellaneous Bypassing of Interlocks - Local Keyed Input with 5 minute reset - Alarm in Central Control ensures 2-person communication -Local Mimic Panels with view of valves help greatly Legend: xxxxx = Lighted Pushbutton D-1302-A Green ON / OFF Green 13106 13104 13107 Recirc -> A Recirc Amber Recirc -> B Bypass Stop Red XZLO Red Stop Bypass 13103 13040D 13105 Key Key SP-6C A -> Recirc Recirc B -> Recirc SP-6D 13091C 13101C Green Red SP-1302 Red Green Amber Amber Amber 13091A 13101B 13101A 13091B XZLO XZLO XZLO 13040A 13040B 13040C Open Close Close Open Brea -> A Mid Brea -> B Green Green Red Green Green D-1302-B Bypass Stop 13109 13122 13108 13120 13124 13121 Stop Bypass Key 13090C A -> Mid Mid -> B Stop Restart A <- Mid Mid <- B 13102C Key Green 13090A Open Red 13090B Close SP-7C ON / OFF Bypass Stop Stop Bypass 13254 Key 13X12C 13X13C Key MOV-10C Mid Position MOV-10D Green Red Red Green SP-7D Red 13102B Close Green 13102A Open Steam Water Bypass Stop 13X12A Open 13X12B Close 13X13B Close TRAIN 2 Switch Deck Schematic Control Panel 13X13A Open Stop Bypass Steam Water Key 13X03C Red Red Green 13X04C Key Green 13X03A Open Red 13X03B Close MOV-11C EL 13001 Actuator Power EL 13001 PLC Power 13259 Lamp Test MOV-11D Rev 1 MJM 8-dec-04 Red 13X04B Close Green 13X04A Open MJ Moloney - ExxonMobil April-2005 coking.com 21

Valve Interlock Systems - Manual Valve Applications Quarter-Turn Valves with Factory-Installed Limit Switches - Applicable to valve operations were incorrect opening or closing does not create a loss of containment - Second vent valve or PRV discharge valve - Wired to PLC with alarm function Application of Smith Flow Control Keyed Lock design - Requires use of specific keys to open or close a manual valve - Makes sense for applications where valve movements are not frequent => PRV blocks, Pipe Pigging, Emergency System Lockouts - Not practical for multiple coker valves Guiding light system is an improvement (factor of 2-4) over LOTO - However, does not yield an order of magnitude improvement since the human factor is still a big part MJ Moloney - ExxonMobil April-2005 coking.com 22