Crude Vacuum Tower Wash Bed Optimization

Posted by Margaret Bletsch

Jun 6, 2017 5:58:02 PM

The crude unit of today’s modern refinery is where it all starts.  Good, clean fractionation from the crude atmospheric and crude vacuum towers greatly impacts the operation of downstream units.

The wash bed in the Crude vacuum tower is one of those so-called evil necessities.  When it operates well, it does not seem to garner much attention but, when things go wrong challenges can occur.  The wash bed of the Crude vacuum tower is prone to coking/fouling due to the low liquid rates along with high vapour rates and high temperatures.  Generally, the wetting rate at the top of the wash bed is minimised to prevent high-value product loss, but lower wetting rates lead directly to coke formation in the bed.  The operating condition or the rate and severity of coking in the Crude vacuum tower wash bed is also one of the key variables determining the cycle time or run length between turnarounds.  So, the typical refiner works to balance the economics of product Heavy Vacuum Gas Oil (HVGO) recovery versus unscheduled or premature downtime to replace a coked bed. 

Marathon Petroleum Company LP’s (MPC) approach for operation of the vacuum tower wash bed is based on a novel approach.  MPC regards the packing in the wash bed as a consumable item.  The goal – fully consume the useful life of the packing by the end of the operating cycle to maximise operating profit, by maximising HVGO yield.  MPC uses Tracerco’s ThruVision™ technology to routinely monitor the wash bed density to help manage the wash bed useful life during the operating cycle.  The ThruVision™ technology provides a detailed density map at a specific vertical elevation that can pinpoint specific areas of liquid maldistribution or solids/liquid build-up. 

This case study shows the learning process over short operating cycles and an example of the operating stratagem to manage the operating life of the vacuum column wash bed over a multi-year operating cycle.

 CLICK HERE To download the full article that was published in the April 2017 issue of Hydrocarbon Engineering.

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Topics: Gamma Scanning, Tru-Grid Scan, ThruVision scan, gamma scan, liquid distribution, quantitative analysis pack beds, PackView Analysis, monitor wash bed coking, tomography scan

Are you looking for a way to detect fouled or damaged packing before entering a tower?

Posted by Margaret Bletsch

Apr 13, 2017 4:20:42 PM

Tru-Grid™ Scans reveal vital process information that helps solve operating problems.
A Tru-Grid™ Scan of packed towers is a reliable and widely used field measurement used for evaluating the hydraulic performance in packed beds, including the results from plugging / fouling or damage. When experiencing problems there are two important questions you would like answered:
1. Where is the fouling / plugging or damage?  
2. What is the extent of the hydraulic problem due to fouling or damage to the packing?

Gamma scanning has proven to be an essential measurement tool to supplement operating history data analysis. Process engineers and operations personnel need to know what is happening inside their process equipment so they can take corrective action. A Tru-Grid™ Scan provides a density profile of the internal process to diagnose hydraulic operating conditions such as damage to internals, flooding, liquid levels on trays and distributors, and liquid distribution through packed beds.

Performing Tru-Grid™ Scans before a scheduled shutdown can help capture real-time data to optimize your turnaround and reduce cost over-runs. Scan results will prepare those planning the turnaround activities with the knowledge needed for critical path decisions. Scans performed five to six weeks prior to a scheduled shutdown usually provides enough time to order new equipment without expediting charges and to schedule the required manpower. 

In this latest blog, Tracerco, part of Johnson Matthey Plc, discusses how an unexpected pressure surge affected the performance of an acid solvent recovery column.

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Topics: Gamma Scanning, Tru-Grid Scan, gamma scan, packing mal-distribution, liquid distribution, quantitative analysis pack beds, PackView Analysis, packed bed towers, packed bed scan

Learn more about PackView™ technology at AIChE 2017.

Posted by Margaret Bletsch

Mar 20, 2017 8:32:00 PM

Tracerco will be highlighting our latest technology and improved analysis, PackView™ for packed towers, at this year's AIChE 2017 Spring Meeting in San Antonio, Texas.

Topical 8 - Session: Kister Distillation Symposium 2017:
Distillation Troubleshooting and Controls: Lessons Learned 
Tracerco Presentation Details:
"Packed Bed Performance Analytics Based on Gamma Scans"
Wednesday March 29, 2017 8:05 am 
Room 302 AB, Henry B. Gonzalez Convention Center 

Mark your schedule to sit in on the paper "Packed Bed Performance Analytics Based on Gamma Scans" presented by Lowell Pless - Business Development Manager - Distillation Applications for Johnson Matthey - Tracerco. The presentation will provide actual case studies illustrating how this advanced analysis provides a new method of extracting quantitative information from gamma scan data to diagnose and characterize operation of distillation and separation towers. Read more about the the presentation in the following abstract that will provide an overview of what will be presented.

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Topics: Gamma Scanning, Tru-Grid Scan, gamma scan, packing mal-distribution, liquid distribution, quantitative analysis pack beds, PackView Analysis

How to define foam profiles in coke drums and verify level devices: A case study

Posted by Margaret Bletsch

Mar 3, 2017 3:24:45 PM

Tru-Scan™ is used by refineries to define foam profiles and verify level detection devices in their coke drums. A Tru-Scan can determine the difference in vapour density throughout a typical drum cycle.

In this latest blog, Tracerco, part of Johnson Matthey Plc, discusses how a Tru-Scan™ can be a powerful tool for gathering much needed information to optimise a coke drum cycle.

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Topics: Gamma Scanning, Tru-Scan, coke buildup, coke deposits, gamma scan, level detection devices, coke drum cycle, coke drum optimization, coke drum, foam profile, coker optimization, coker units, delayed coke drum

How to determine catalyst loss in FCC reactor or FCC regenerator cyclones: A case study

Posted by Nicola Porter

Jan 5, 2017 11:09:32 AM

The loss of catalyst through reactor or regenerator cyclones is a fairly common problem. Identifying the reason for the loss is often difficult.

In this latest blog, Tracerco, part of Johnson Matthey Plc, discusses how a Tru-Scan™ can be a powerful tool for gathering much needed information regarding the loss of catalyst.

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Topics: Gamma Scanning, Tru-Scan, fcc unit, fcc, fcc diagnostics, fccu process, fccu studies, cracking unit, fcc troubleshooting, fcc units, fcc unit process, fluid catalytic cracking diagnostics, fluid catalytic cracking services, fluid catalytic cracking unit, Catalytic cracking, fcc cracking, reactor cyclone, gamma scan, fcc additives, fcc services, reactor distributor, riser reactor, fcc reactor, reactor riser, reactor stripper, regenerator cyclone, catalyst loss, Intercat, fcc addition systems

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