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These digital transcripts are meant to share information on process safety practices in order to help improve process safety performance and awareness throughout industry. The goal is to capture and share knowledge that could be used by other companies or sites when developing new process safety practices or improving existing ones. The documents being shared have been used by an industry member, but this does not mean it should be used or that it will produce similar results at any other site. Rather, it is an option to consider when implementing or adjusting programs and practices at a site. ​

BY THEMSELVES, THESE DIGITAL TRANSCRIPTS ARE NOT STANDARDS OR RECOMMENDED PRACTICES. THEY ARE NOT INTENDED TO REPLACE SOUND ENGINEERING JUDGMENT. THEY DO NOT PRECLUDE THE USE OF ALTERNATIVE METHODS THAT COMPLY WITH LEGAL REQUIREMENTS. A SUBJECT MATTER EXPERT SHOULD BE CONSULTED PRIOR TO DETERMINING WHETHER A PRACTICE CAN BE USED IN ANY SPECIFIC SITUATION. 

​

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(2019) Question 9: How do you track chloride in liquid/gas/LPG? What are your criteria for replacing adsorbent in chloride treaters?

DAVINDER MITTAL (HPCL Mittal Energy)
Chlorides have been a long standing issue in catalytic reformer operation. Until a few years ago, the focus on preventing operational problems from the chloride compounds in the catalytic reformer product stream was to remove HCl.  More recently, a growing

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(2019) Question 10: What causes metal-catalyzed coking (MCC) that obstructs catalyst circulation in CCR reformers? What actions do you take to mitigate MCC formation?

BILL KOSTKA (AXENS NORTH AMERICA)
Metal-catalyzed coke (MCC) formation typically occurs on 3d valence transition metals such as iron and nickel.  Under CCR-like conditions of low hydrogen partial pressure (less than about 620 kpa), high temperature (more than about 480 °C) and low or stagnant flow

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(2019) Question 14: What are your strategies to reduce alky acid consumption?

ABIGAIL SLATER (HollyFrontier)
The most impactful parameter affecting alky acid consumption is feed quality. Reducing feed contamination will greatly reduce acid consumption. There are also operational changes that can be made to reduce acid consumption, but the biggest impact will be feed

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(2019) Question 15: What practices and modifications have you implemented in response to the new High Temperature Hydrogen Attack (HTHA) guidelines and updated Nelson curves?

JOE RYDBERG (CITGO)
The primary source document for dealing with High Temperature Hydrogen Attack (HTHA) is API Recommended Practice 941 – Steels for Hydrogen Service at Elevated Temperatures and Pressures in Petroleum Refineries and Petrochemical Plants. This document provides the basic guidelines

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(2019) Question 16: What is required to achieve Safety Integrity Level 2 (SIL-2) rating on the hydrocracker depressuring system? For a hydrotreater that does not require SIL-2, what position should the depressurization valve fail to?

JOE RYDBERG (CITGO)
CITGO typically seeks process safety consultants to help with SIS design including SIL selection.  Kenexis is such a company who has provided the following technical information regarding depressurization systems.   

There are a multitude of different initiating events (loss of

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(2019) Question 17: What testing frequency and additional feed characterization (apart from bulk properties) should be used to accurately monitor catalyst performance on heavy feeds?

FERNANDO MALDONADO (Shell Catalysts & Technologies)
The type and frequency of tests performed are unit and refinery specific. When creating or modifying a unit’s laboratory test schedule some factors to be considered include: 

1.    Unit objectives
2.    Past and/or current operational issues 
3.  

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(2019) Question 19: In a hydrocracking unit, what methods do you use to determine the pretreat reactor operating temperature for optimum nitrogen slip to cracking catalyst?

AMIT KELKAR (Shell Catalysts & Technologies)
Nitrogen slip is a key variable in balancing the performance of the pretreat and cracking catalysts for cycle optimization. The optimum nitrogen slip depends on the specific unit objectives and constraints. In general, the pretreat temperature is adjusted

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(2019) Question 28: In light of IMO (International Maritime Organization) 2020 and the potential for shipping intermediate streams from refinery to refinery, what are your plans to ensure H2S specification in the vapor space is met, either at the shipping or receiving point?

STEVE WILLIAMS (Marathon Petroleum Corporation)

•    Movement of intermediate streams from refinery to refinery has been a common practice, including movement of heavy oils.  This activity is expected to increase following implementation of the IMO 2020 rules reducing the sulfur content in maritime

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(2019) Question 32: Where are ammonium chloride and amine hydrochloride salt found in your crude unit? What is your best practice to monitor and mitigate the resulting corrosion and fouling?

Ammonium chloride and amine hydrochloride salts can form in the top section of the Atmospheric and Vacuum Towers, and the overhead exchangers of the tower. The formation of these salts is a function of partial pressures which dictated by the concentrations of ammonia, amines, chlorides in addition to operating conditions such as overhead temperature, pressure, steam flow rate and hydrocarbon flow rate.
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Question 1: Historically, instrument air was used to purge FCC reactor instruments. More recently, dry gas or nitrogen is typically used for this service. Please explain the reasons for moving away from air and provide examples of operating upsets that have occurred when using air to purge instruments.

Gas purge streams for instrumentation in FCCU reactor-regenerator service are required to ensure their functionality. For example, the reliability of level- and pressure-measuring devices relies on clear impulse lines. The utilization of a continuous-purge gas stream ensures that catalyst particles are prevented from entering or are swept from impulse lines to keep them clear and reliable.
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