Additive Injection Nozzles for Delayed Coker Drum Interphase
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Solution Overview
Problem
Existing delayed coking processes in petroleum refineries face challenges in reducing coke yield, improving the quality and quantity of liquid and gaseous products, and modifying coke morphology, particularly due to the inefficiency of adding additives before the coker drum where they may lose activity and cause coke deposition in furnace tubes.
Innovation Solution
Adding external additives to the coker feedstock at the vapor-liquid interphase within the delayed coker drum using a system of injection nozzles controlled to maintain effective additive distribution and switching to steam as the interphase level changes, ensuring efficient mass transfer and minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If additives are added to the feedstock before the coker drum, then the residence time of the additive is increased, but the activity of the additive is reduced
Solution Approach 1:
The additive is pre-mixed with a carrier fluid (such as water, alcohol, or acid) to create a stable composition before introduction into the coker drum. This preliminary preparation ensures the additive remains active and effective when introduced at the critical vapor-liquid interphase, rather than being degraded by prolonged residence time in the feedstock
Solution Approach 2:
A carrier fluid is introduced as an intermediary substance to deliver the additive to the vapor-liquid interphase. The carrier fluid protects the additive from premature degradation and ensures controlled delivery at the optimal location, maintaining additive activity while achieving the desired residence time effect
2Ease of operation
If additives are added to the feedstock before the coker drum, then the additive is distributed throughout the process, but coke deposition on furnace tube metal surface increases
Solution Approach 1:
Instead of uniform distribution throughout the feedstock, the additive is selectively introduced only at the vapor-liquid interphase location within the coker drum. This localized application ensures the additive acts where coking reactions are occurring, preventing coke deposition on furnace tubes while avoiding unnecessary presence in other process areas
Solution Approach 2:
The harmful effect of additive-induced coke deposition is eliminated by extracting the additive from the feedstock stream and introducing it separately at the vapor-liquid interphase. This separation removes the harmful interaction between additive and furnace tube surfaces while preserving the beneficial coking modification effects
3Ease of manufacture
If additives are injected into the vapor phase at the upper portion of the coker drum, then the additive is easily introduced, but the effectiveness is reduced because coking reactions predominantly take place in the liquid pool
Solution Approach 1:
The vapor-liquid interphase serves as an intermediary zone that bridges the ease of vapor-phase introduction with the effectiveness of liquid-phase action. By introducing the additive at this interphase boundary, the system leverages the accessibility of vapor injection while ensuring the additive reaches the liquid pool where coking reactions occur
Solution Approach 2:
The additive is introduced at the phase boundary where vapor and liquid coexist. This strategic use of the phase transition zone allows the additive to efficiently transfer from the vapor phase into the liquid pool, combining the ease of vapor-phase injection with the effectiveness of liquid-phase reaction modification
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the utilization of additives, reduces coke deposition, and improves the quality and quantity of products by maintaining additive activity and facilitating efficient mass transfer at the turbulent vapor-liquid interphase, leading to better downstream operations and reduced coke removal time.
Implementation Method 1
facilitating efficient mass transfer at the turbulent vapor-liquid interphase
Implementation Method 2
at the turbulent vapor-liquid interphase
Data Source
AI summary
An apparatus for supplying additives into a coker drum includes an inlet for supplying a hydrocarbon feed stream into the coker drum and conduits along the circumference of walls of the coker drum. Each conduit has an injection nozzle to supply additives inside the coker drum. An injection control system controls the operation of the injection nozzles such that 1) one or more of the injection nozzles placed within a first distance above a vapour liquid interphase of the hydrocarbon feed stream are configured to supply the additives; and 2) supply of the additive discontinues from a particular injection nozzle when a distance between the injection nozzle and the vapour liquid interphase is less than or equal to a second distance. The apparatus optionally includes a mechanical drive system moving at least one of the conduits based on the level of the vapour liquid interphase in the coker drum.