Steam Cracker Heat Integration with Ethanol Dehydration
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Solution Overview
Problem
Current ethanol dehydration processes are not fully selective for ethylene production, leading to the generation of C4 compounds as side products, which are costly and complex to remove, and combining steam cracking with ethanol dehydration has been thought to cause fouling and plugging due to oxygenate species.
Innovation Solution
Integrating ethanol dehydration with steam cracking by washing the ethylene-rich gas product before blending it with the olefin stream from steam cracking, reducing water, ethane, and aldehyde content, and combining the streams within a compression stage to prevent fouling and enable effective recovery of co-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ethanol dehydration is combined with steam cracking, then capital cost advantages and better utilization of side products are achieved, but fouling and plugging occur due to oxygenate species formation
Solution Approach 1:
The patent extracts and removes oxygenate species (ethanol, acetaldehyde) from the combined feed stream before entering the steam cracking furnace through a pre-treatment washing step. This prevents the harmful oxygenates from causing fouling and plugging in the cracking system while still allowing the integrated process to proceed with the beneficial capital cost advantages and side product utilization.
2Productivity
If ethanol dehydration is used for ethylene production, then ethylene is produced, but C4 compounds are generated as side products requiring costly and complex removal
Solution Approach 1:
The patent merges the ethanol dehydration process with the steam cracking process by combining their feed streams. The C4 compounds generated from ethanol dehydration are co-fed with hydrocarbon feedstocks into the steam cracking furnace, where they undergo cracking together with the hydrocarbons. This integration eliminates the need for separate, complex C4 removal systems while maintaining ethylene production from ethanol.
3Productivity
If unconverted ethanol and acetaldehyde from dehydration enter the steam cracker quench system, then recycling occurs, but fouling and undesirable oxygenate species formation are caused
Solution Approach 1:
The patent applies preliminary action by washing and removing oxygenate species (ethanol, acetaldehyde) from the combined feed stream before it enters the steam cracking furnace. This pre-treatment step prevents the formation of undesirable oxygenate species during cracking and eliminates the need for downstream caustic washing, while still allowing the integrated process to produce ethylene efficiently.
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 integrated process achieves capital cost advantages, better utilization of side products, and improved energy balance, allowing for the economic recovery of co-products like ethane and propylene, reducing the energy footprint and greenhouse gas emissions.
Implementation Method 1
steam cracking of saturated hydrocarbons
Implementation Method 2
heat transfer from steam cracking to alcohol dehydration process
Data Source
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AI summary
A method of producing ethylene and, optionally, propylene comprising : a) subjecting a feedstock to steam cracking to produce a first olefin containing stream; b) heating an ethanol containing stream with heat from a steam cracker; c) passing the heated ethanol containing stream over a dehydration catalyst at a temperature between 200C to 500C preferably 250C to 450C to produce a second olefin containing stream; d) combining the first and second olefin containing streams to give an initial product stream comprising ethylene and optionally propylene; and e) subjecting the initial product stream to purification comprising at least i) water content reduction ii) hydrogen content reduction iii) reduction of content of molecules containing 4 or more carbon atoms and iv) ethane content reduction.