Master of Engineering Science
Chemical and Biochemical Engineering
Briens, Cedric L.
Bitumen-coke agglomerates form in Fluid Cokers when bitumen sprayed into the bed acts as a binding agent and clumps coke particles together. These agglomerates are devastating to the performance of Fluid Cokers as they reduce the yield of valuable refined oil and can lead to premature shutdowns through fouling. A novel method involving detection of magnetic model agglomerates predicts how well a gas-solid downsized cold model unit breaks up agglomerates using an algorithm. In this study, the impacts of changing nozzle properties, unit internals, and feed distribution are examined on a range of agglomerates with different strengths. Redirecting the feed bitumen to the upper banks increases the breakup in the bed by 34% on average. Including the baffle shows an additive impact, for a total of 131% increase in breakup. The algorithm proves to be accurate and can be used in the future for fluidized bed applications for determining agglomerate breakup performance.
Summary for Lay Audience
Agglomeration is a physical phenomenon where many particles bind together. Industries such as pharmaceuticals and paints view agglomeration as a benefit as it reduces particulate fines which are a health and safety risk to workers and the environment.
In Fluid Cokers, agglomeration is a detriment; large and heavy agglomerates, formed by bitumen binding to fine coke particles (a coal derivative), reach the bottom of a Fluid Coker reactor too quickly, destroying the valuable liquid bitumen, and creating a layer of deposit on the reactor. Over time, this deposit builds up and Fluid Cokers are forced to shut down to remove these deposits. This is costly as the time taken to remove the deposit is lost potential operation run-time. In other words, reducing the amount of agglomerates that reach the bottom of the reactor can reduce the down-time, therefore saving money for refineries and increasing the performance of Fluid Cokers.
A novel method was developed to measure the effectiveness of a dynamically scaled-down gas-solid cold model unit to break agglomerates. This method involves simulating agglomerates using connected magnets, then detecting the difference in detection times when the magnets pass through the bottom of the unit. Different parameters of the unit, such as injection volumes and internal barriers inside the reactor, were changed to determine each parameter’s impact on how well the reactor breaks agglomerates. An algorithm is proposed to predict how well a reactor can break agglomerates.
The algorithm suggests that redistributing the points where the bitumen is injected, namely towards the upper part of the bed, increases agglomerate breakup, as well as adding a “ring-baffle”. Applying both together sees an increased benefit.
Tang, Davin M. Mr, "Agglomerate Breakup in Recirculating Fluidized Beds" (2023). Electronic Thesis and Dissertation Repository. 9178.
Available for download on Monday, December 23, 2024