Dehydrogenation Reactors for Shale Gas Alkene Production
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Solution Overview
Problem
Conventional processes for producing olefins from shale gas, such as steam cracking and catalytic dehydrogenation, are capital and energy intensive, with complex heat management and catalyst regeneration requirements, and often result in inefficient production of heavier alkenes like propylene and butylenes.
Innovation Solution
A process involving two dehydrogenation reactors where propane and ethane are dehydrogenated separately, with lighter components serving as chemical inert and thermal mass, allowing for efficient separation and recycling of hydrogen, thereby simplifying the process and improving energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking is used to produce olefins from shale gas, then olefin production is achieved, but the process becomes capital and energy intensive with complex heat management requirements
Solution Approach 1:
The patent extracts and removes water from the feedstock stream before it enters the dehydrogenation reactor. This water removal step simplifies the overall process by eliminating the need for complex steam generation, water conditioning, and heat management systems that are required in conventional steam cracking processes. The extraction of water as a preliminary step reduces both capital expenditure and operational complexity while maintaining olefin production capability.
Solution Approach 2:
The patent changes the operating parameters by using lower temperatures (400-700°C) compared to conventional steam cracking, and by adjusting the feedstock composition through water removal. This parameter change allows the process to achieve olefin production with reduced energy consumption and simpler heat management requirements, directly addressing the contradiction between productivity and device complexity.
2Productivity
If catalytic dehydrogenation is used to produce propylene, then propylene production is achieved, but catalyst regeneration is required due to severe coking
Solution Approach 1:
The patent changes the operating parameters by using lower temperatures (400-700°C) and adjusted pressure conditions that reduce coking on the catalyst. This parameter modification extends catalyst life and reduces the frequency and duration of regeneration cycles, thereby minimizing time loss while maintaining propylene production productivity.
3Productivity
If multiple adiabatic reaction beds are used in catalytic dehydrogenation, then propylene production is sustained, but heat management becomes complex
Solution Approach 1:
The patent removes water from the feedstock stream, which simplifies heat management by eliminating the need to manage steam condensation and condensation separation systems. This extraction step reduces the thermal load variations and eliminates complex heat integration requirements across multiple reaction beds, directly reducing device complexity while maintaining productivity.
Solution Approach 2:
The patent changes the temperature parameters to operate at lower temperatures (400-700°C) which reduces the heat management complexity compared to higher temperature steam cracking processes. This parameter change allows for simpler heat integration and reduces the need for complex heat exchange systems across multiple reaction beds.
4Manufacturing precision
If subambient temperature distillation columns are used for NGL separation, then pure ethane and propane streams are obtained, but energy consumption increases significantly
Solution Approach 1:
The patent extracts and removes water from the feedstock stream before dehydrogenation, which simplifies subsequent separation processes. This preliminary extraction reduces the energy consumption required for distillation columns by eliminating the need to handle water-liquid equilibrium and condensation separation that occurs in subambient temperature operations, while still achieving the required product purity.
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 reduces the complexity and cost of olefin production by utilizing lighter hydrocarbons as thermal mass, enhancing conversion rates and reducing equipment needs, leading to more efficient production of propylene, ethylene, and butylene from shale gas or natural gas streams.
Implementation Method 1
propane is dehydrogenated in a first reactor and ethane is dehydrogenated in a second reactor
Implementation Method 2
The lighter components which serve as chemical inert and thermal mass are separated from the dehydrogenated product after each reactor
Data Source
AI summary
Systems and processes for producing one or more alkenes from shale gas. The process includes at least two dehydrogenation reactors whereby propane, or a mixture of propane and butane, can be dehydrogenated in a first reactor and ethane can be dehydrogenated in a second reactor. The lighter components which serve as chemical inert and thermal mass are separated from the dehydrogenated product after each reactor.