Two-Phase Hydroprocessing Pretreatment for Trickle Bed Reactors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional hydroprocessing systems, such as trickle bed reactors, are inefficient due to high hydrogen consumption, coke formation, and limited conversion in liquid-phase zones, making it challenging to produce clean fuels that meet stringent specifications like Euro V ULSD.

Innovation Solution

A process involving a two-phase hydroprocessing zone with liquid-full reactors followed by a three-phase hydroprocessing zone in a trickle bed reactor, where hydrogen is dissolved in the liquid phase, allowing for efficient sulfur and nitrogen removal and cetane number increase, using a sequence of catalyst beds with increasing volume and recycling of product effluent to optimize hydrogen utilization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional three-phase trickle bed reactor is used for hydroprocessing, then hydrogen transfer from vapor phase through liquid phase to catalyst surface can be achieved, but the process becomes expensive to operate with large excess hydrogen requirement and significant coke formation causing catalyst deactivation

Engineering Contradiction:

Improvecatalyst stabilityVSAvoidhydrogen consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention changes the physical state of hydrogen from vapor phase to dissolved liquid phase by controlling hydrogen solubility parameters in the hydrocarbon feed. This parameter change eliminates the need for vapor-liquid-gas three-phase mass transfer, reducing hydrogen consumption and preventing catalyst deactivation while maintaining effective hydroprocessing.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If a two-phase hydroprocessing system with dissolved hydrogen is used, then the need for vapor phase hydrogen transfer is eliminated, but conversion may be limited due to hydrogen solubility constraints

Engineering Contradiction:

Improveconversion efficiencyVSAvoidhydrogen availability

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The invention segments the hydroprocessing system into multiple reactor zones with different functions: a first two-phase zone for initial conversion and a second three-phase zone for achieving high conversion. This segmentation allows each zone to operate optimally within its design parameters, overcoming the limitations of hydrogen solubility in single-phase systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention performs preliminary hydroprocessing in the first two-phase reactor zone where hydrogen is dissolved in the liquid phase, achieving initial conversion. This preliminary action reduces the burden on the second zone and allows the system to overcome hydrogen solubility limitations by distributing the conversion load across multiple stages.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If a combination of liquid-phase and three-phase zones is used as in Kokayeff et al., then hydrogen requirements for both zones can be met, but the liquid-phase zone effectiveness is limited by hydrogen solubility requiring large reactor size

Engineering Contradiction:

Improveconversion achievementVSAvoidreactor volume

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention applies local quality by creating distinct functional zones with different characteristics: the first zone uses dissolved hydrogen in liquid phase for controlled conversion, while the second zone uses vapor phase hydrogen for high conversion. Each zone is optimized for its specific function, allowing the system to achieve high overall conversion without requiring excessively large reactor volumes.

Inventive Principle:

Principle #3Local quality

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 achieves high conversion of sulfur and nitrogen, reducing sulfur content from over 10,000 wppm to below 10 wppm, meeting Euro V specifications, while minimizing reactor size and hydrogen recirculation, and enhancing cetane number, thus producing high-quality clean fuels.

Implementation Method 1

Hydrogen is dissolved in the feed/diluent mixture to provide hydrogen in the liquid phase. Substantially all of the hydrogen required in the hydroprocessing reaction is available in solution.

Methodology Applied

Scientific EffectHydrogen dissolution: Absorption (physical)

Implementation Method 2

Hydroprocessing processes, such as hydrodesulfurization (HDS) and hydrodenitrogenation (HDN), which remove sulfur and nitrogen, respectively, have been used to treat hydrocarbon feeds to produce clean fuels.

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentUS8945372B2Two phase hydroprocessing process as pretreatment for tree-phase hydroprocessing process

Publication Date: 2015.02.03 REFINING TECHNOLOGY SOLUTIONS LLC

AI summary

The present invention provides a process for hydroprocessing comprising treating a hydrocarbon feed in a first two-phase hydroprocessing zone having a liquid recycle, producing product effluent, which is contacted with a catalyst and hydrogen in a downstream three-phase hydroprocessing zone, wherein at least a portion of the hydrogen supplied to the three-phase zone is a hydrogen-rich recycle gas stream. Optionally, the product effluent from the first two-phase hydroprocessing zone is fed to a second two-phase hydroprocessing zone containing a single-liquid-pass reactor. The two-phase hydroprocessing zones comprise two or more catalyst beds disposed in liquid-full reactors. The three-phase hydroprocessing zone comprises one or more single-liquid-pass catalyst beds disposed in a trickle bed reactor.