Hydrogen Allocation in Integrated Refinery Olefin Plants
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Solution Overview
Problem
Conventional methods for processing crude oil in refineries face challenges in efficiently converting hydrocarbons into valuable olefins and aromatics, with high capital costs and hydrogen consumption, leading to suboptimal product yields and hydrogen imbalance in refinery systems.
Innovation Solution
A method integrating hydrogen-consuming and hydrogen-producing process units within a refinery system, utilizing steam cracking, propane dehydrogenation, and butane dehydrogenation units to optimize hydrogen allocation and conversion of crude oil fractions into low-boiling hydrocarbons, such as ethane, propane, and butanes, which are then processed to produce olefins and BTX products, while managing hydrogen distribution and consumption across the refinery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods for processing crude oil in refineries are used, then the processing can be performed with existing technology, but the conversion efficiency into valuable olefins and aromatics is low and hydrogen consumption is high
Solution Approach 1:
The patent combines hydrogen-consuming process units (hydrocrackers, hydrodealkylation units) with hydrogen-producing process units (steam crackers, dehydrogenation units) into an integrated refinery system. This merging allows internal hydrogen circulation where hydrogen produced by cracking and dehydrogenation units is directly utilized by hydroprocessing units, reducing external hydrogen requirements and improving overall conversion efficiency to olefins and aromatics.
Solution Approach 2:
The integrated refinery system is designed so that process units serve multiple functions. For example, steam crackers not only produce olefins but also generate hydrogen that is reused elsewhere in the system. Dehydrogenation units produce both aromatics and hydrogen. This multi-functionality reduces the need for separate dedicated hydrogen production facilities and improves overall system efficiency.
2Productivity
If more hydrogen is supplied to hydrogen-consuming units to improve conversion, then the conversion of crude oil fraction into low-boiling hydrocarbons increases, but the hydrogen imbalance in the refinery system worsens
Solution Approach 1:
The patent implements a feedback mechanism where hydrogen production from steam cracking and dehydrogenation units is continuously monitored and fed back to hydrogen-consuming units. This internal feedback loop allows the system to self-regulate hydrogen distribution, ensuring that increased conversion in one unit is balanced by hydrogen availability from other units, maintaining overall hydrogen balance stability.
Solution Approach 2:
The system dynamically adjusts operating parameters such as temperature, pressure, and feed rates in hydrogen-producing and hydrogen-consuming units to optimize hydrogen generation and consumption. By changing these parameters in response to system conditions, the refinery maintains hydrogen balance while maximizing conversion to low-boiling hydrocarbons.
3Productivity
If conventional separate processing of crude oil and olefin production is used, then the process design is simpler, but the product yield and hydrogen utilization are suboptimal
Solution Approach 1:
The integrated refinery is divided into distinct functional segments: hydrogen-producing segment (steam crackers, dehydrogenation units), hydrogen-consuming segment (hydrocrackers, hydrodealkylation units), and hydrogen distribution network. This segmentation allows each unit to be optimized independently while maintaining overall integration benefits, managing complexity through modular design.
Solution Approach 2:
The patent introduces a hydrogen distribution network as an intermediary system that connects hydrogen-producing and hydrogen-consuming units. This intermediary infrastructure manages hydrogen flow, pressure, and composition between units, enabling efficient integration without requiring direct complex coupling between all process units.
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 integration of refinery units and olefin plants, achieving profitable product slate integration and hydrogen gas balancing, with at least 25 wt.% of the crude oil fraction converted into low-boiling hydrocarbons, thereby improving the yield of valuable hydrocarbon products and optimizing hydrogen usage.
Implementation Method 1
steam cracking unit
Implementation Method 2
propane dehydrogenation unit (PDH)
Implementation Method 3
butane dehydrogenation unit (BDH)
Implementation Method 4
hydrogen consuming process units
Data Source
AI summary
A method of controlling the supply and allocation of hydrogen gas in a hydrogen system of a refinery integrated with olefins and aromatics plants to convert crude oil into petrochemicals. The method includes one or more supply sources that provide hydrogen at individual rates, purities, pressures and costs, multiple consumption sites that consume hydrogen at individual rates, purities and pressures and an interconnecting hydrogen distribution network. The method further includes the integration of hydrogen consuming process units with hydrogen producing process units in which hydrogen recovered from the effluents from the hydrogen consuming process units and hydrogen recovered from the hydrogen producing process units are re-used in the hydrogen consuming process units.