Liquid-full Hydroprocessing Reactor for Heavy Feed Conversion
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Solution Overview
Problem
Conventional hydroprocessing of heavy hydrocarbon feeds is inefficient and costly due to high hydrogen consumption, catalyst deactivation, and difficulties in removing nitrogen and sulfur, particularly when dealing with high asphaltene content, leading to low commercial value products and operational challenges.
Innovation Solution
A process involving contacting a heavy hydrocarbon feed with a diluent and hydrogen in a liquid-full reactor, using a catalyst with non-precious metals like nickel, cobalt, or molybdenum, and recycling a portion of the product stream as diluent, which allows high hydrogen solubility and reduces the need for hydrogen gas recirculation, thereby minimizing reactor size and operational costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional hydroprocessing is used to treat heavy hydrocarbon feeds with high asphaltene content, then hydrogen consumption is high and catalyst deactivation occurs rapidly, but the process requires very large and expensive reactors
Solution Approach 1:
The patent changes the physical state parameter of hydrogen from gas phase to dissolved liquid phase by increasing hydrogen concentration in the liquid feed to 0.1-10 wt%. This parameter change allows the process to achieve high hydrogen consumption (improving_feature) while using much smaller reactor volumes (reducing worsening_feature) because the hydrogen is uniformly distributed and available in the liquid phase where mass transfer limitations are minimized.
Solution Approach 2:
The patent utilizes phase transition by dissolving hydrogen gas into the liquid hydrocarbon feed to create a liquid-full reaction environment. This phase transition from gas to dissolved state eliminates the need for large gas-liquid contactors and allows the reaction to proceed in a single liquid phase, thereby reducing reactor size while maintaining high hydrogen consumption levels.
2Productivity
If high hydrogen uptake is used to process heavy hydrocarbon mixtures, then conversion efficiency improves, but heat generation increases causing rapid coking of catalyst and deactivation
Solution Approach 1:
The patent introduces diluents (light hydrocarbons such as naphtha, diesel, or gas oil) as intermediaries that mix with the heavy hydrocarbon feed and dissolved hydrogen. This intermediary liquid phase acts as a heat sink and mass transfer medium, allowing high hydrogen uptake and conversion efficiency while distributing heat more uniformly to prevent localized hot spots that cause catalyst coking and deactivation.
Solution Approach 2:
The patent changes the thermal parameters by operating in a liquid-full environment with diluents present, which have different heat capacities and thermal conductivities compared to gas-phase systems. This parameter change in the thermal environment allows the system to handle the heat from high hydrogen uptake more effectively, maintaining catalyst stability while achieving high conversion efficiency.
3Ease of operation
If heavy hydrocarbon mixtures are heated prior to use to provide fluid feed, then flowability improves, but asphaltene aggregation increases causing pipe clogging and catalyst deactivation
Solution Approach 1:
The patent applies local quality by introducing diluents that preferentially interact with and solvate asphaltene molecules at the molecular level throughout the feed stream. This local solvation effect prevents asphaltene aggregation while maintaining overall feed flowability, allowing the system to achieve ease of operation without generating the harmful aggregation effects that occur in conventional heated systems.
Solution Approach 2:
The patent creates a composite liquid mixture consisting of heavy hydrocarbon feed, diluent, and dissolved hydrogen. This composite material system has improved rheological properties where the diluent component prevents asphaltene aggregation through solvation, thereby maintaining feed flowability while eliminating the harmful aggregation that would otherwise occur upon heating.
4Quantity of substance
If large volumes of hydrogen are recycled to maintain conversion, then hydrogen utilization improves, but compression costs and furnace duty increase significantly
Solution Approach 1:
The patent changes the physical state parameter of hydrogen from gas phase to dissolved liquid phase. This parameter change eliminates the need for large-volume hydrogen gas recycling and compression because the hydrogen remains dissolved in the liquid phase throughout the process. The system maintains high hydrogen utilization while avoiding the energy-intensive compression and furnace duty associated with gas-phase hydrogen recycle.
5Reliability
If conventional hydroprocessing is used for feeds with high asphaltene content, then treatment is attempted, but mass transfer limitations occur due to high viscosity resulting in low single pass conversion
Solution Approach 1:
The patent changes the viscosity parameter of the feed by dissolving hydrogen and adding diluents to create a liquid-full environment. This parameter change reduces the effective viscosity and improves mass transfer characteristics, allowing the system to achieve both treatment effectiveness for high asphaltene feeds and high single pass conversion that would otherwise be limited by mass transfer issues.
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 process enhances hydrogen solubility, reduces catalyst coking, and achieves efficient conversion of heavy hydrocarbon feeds with lower nitrogen and sulfur content, resulting in higher value products and prolonged catalyst life, while simplifying reactor design and reducing capital costs.
Implementation Method 1
contacting the feed with (i) a diluent and (ii) hydrogen to produce a feed/diluent/hydrogen mixture, wherein the hydrogen is dissolved in the mixture to provide a liquid feed
Implementation Method 2
contacting the feed/diluent/hydrogen mixture with a catalyst, in a liquid-full reactor, to produce a product mixture
Data Source
AI summary
A process to treat a heavy hydrocarbon feed in a liquid-full hydroprocessing reactor is disclosed. The heavy feed has a high asphaltenes content, high viscosity, high density and high end boiling point. Hydrogen is fed in an equivalent amount of at least 160 liters of hydrogen, per liter of feed, l/l (900 scf/bbl). The feed is contacted with hydrogen and a diluent, which comprises, consists essentially of, or consists of recycle product stream. The hydroprocessed product has increased value for refineries, such as a feed for an fluid catalytic cracking (FCC) unit.