Back

New design improves FCC slurry pumparound

Rising global demand for transportation fuels and propylene as a chemical feedstock will require new and revamped FCC units to increase supply. Technology enhancements have historically focused on improved or new catalyst formulations, updated feed nozzles, and reactor/regenerator designs.

FCC charge rate and reactor temperature are often limited by performance of the main column and bottoms system. To fully capture benefits associated with tailored catalyst formulation or new reactor/ regenerator designs, the main column and slurry pumparound system must be up to the task.

For many refiners, problems in the main column and bottoms section are a common occurrence. Rapid fouling in slurry pumparound exchangers requires frequent cleanings and added maintenance costs. Coking in the slurry pumparound bed leads to poor product quality, increased column pressure drop, and shortened run length. However, many chronic problems can be mitigated with innovative designs driven by a proper understanding of the root cause.

Slurry Pumparound Bed
Many FCCs are expected to operate 5-7 years between planned maintenance turnarounds. Modern grid packings have been used in this severe service with success. Even so, there have been times when the combination of high temperature, high liquid rate, and high vapor rate have caused severe coking. Trough distributors have been the go-to device to distribute liquid to the slurry pumparound bed. Special design features are used to mitigate risk of catalyst and coke particle accumulation in the troughs. The features that make the distributor more forgiving also make it more sensitive to liquid gradient and out-of- levelness. Even with the most careful design, slurry beds have experienced premature coking and shortened run lengths.

In order to solve old problems, sometimes new thinking is needed. The engineers at Process Consulting Services, Inc. have revamped high severity, highly-loaded slurry pumparound sections with innovative solutions. A new twist on a classic distributor design improves reliability while eliminating inherent problems of old designs. Patented solutions to highly loaded grid-beds offer needed breathing room. Contact us today to learn how PCS designs can improve your FCC.

DOWNLOAD LITERATURE

Sponsor:

Process Consulting Services

Categories:

Oil sands crude — profits and problems?

Canadian bitumen production currently runs about 1 MMbpd, with some being sold as Synbit and Dilbit. Over the next 10-12 years output is expected to increase to 3.5 MMbpd and more refiners will begin investing to process it and come to depend on the Synbit and Dilbit for a significant part of their supply. ...
Nasty stuff

Heavy crudes are here to stay. As longs as oil prices remain high, Canadian, Venezuelan, Deep Water Gulf of Mexico, Mexican and other low API gravity crude oils will play an ever more important role in supplying world refineries. And prices promise to remain high because gainsayers notwithstanding, Hubbert ...
Designing deepcut vacuum units that really work

Every barrel of vacuum gas oil (VGO) you can save from being reduced to coke in the delayed coker unit is a barrel more that can go to the FCCU. That’s a good reason to raise HVGO cutpoint. But how to do it? Some people think the job can be done just by running computer models in the engineering ...
A time for grass roots thinking ?

Within the past year or two spiking crude prices and surging refinery margins have led to overheated talk about increasing refinery capacity worldwide. Plans for construction of as many 60 grass roots refineries have been discussed. But stretched out lead times for major equipment and inflated prices, ...
A single integrated vacuum system

Failure to design the vacuum unit as an integrated system will invariably result in unsatisfactory yield and poor product quality (high vanadium, nickel, microcarbon, or asphaltenes), and ultimately, an unscheduled shutdown. To avoid these revamp problems the charge pump, fired heater, transfer line, ...
Is pinch enough?

Back in the late 1970’s and early 1980’s when fuel gas prices were high, energy utilization assumed major importance. A new method of calculating heat exchanger networks was developed. It was called Pinch Technology. Today pinch has been rediscovered by engineers who have access to fast computer ...
Opportunity knocks

A group of interesting articles* deals with opportunity crudes, a mixed breed that includes very heavy, sour and high total acid number types as well as those with unexceptional naphthenic acid content but which do have significant concentrations of aliphatic acids or possess the ability to generate ...
Processing heavy Canadian crude

Reducing crude oil cost is the major incentive driving crude and vacuum unit projects to handle heavy Canadian crudes. But such crudes–Albian Heavy, Christina Lake, MacKay River and others derived from oil sands–today present refiners with a unique set of problems not just because of extra-low ...
Why do many crude/vacuum units perform poorly?

In many cases it’s because the original design was based more on virtual than actual reality. There is no question: computer simulations have a key role to play but it’s equally true that process design needs to be based on what works in the field and not on the ideals of the process simulator. ...
Why produce diesel from the vacuum unit?

Look ahead five years. The economy is likely to keep tightening and the rush to control pollution will inevitably be accompanied by demands for greater energy conservation. Consequence? A growing market for diesel which yields more energy per unit volume. Yet many continue to believe that producing diesel ...