Split-Flow Ethanol Dehydration for Ethylene Production
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Solution Overview
Problem
Existing ethanol dehydration processes for producing ethylene often require a caustic scrubber and consume significant amounts of steam, leading to inefficiencies and increased reactor size.
Innovation Solution
A split flow process is implemented, dividing the ethanol feed into two portions, with steam mixing in a charge heater before entering reactors, followed by combining effluents and processing through multiple reactors, reducing reactor volume by 30-40% and steam usage compared to single-reactor systems without a caustic scrubber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single reactor system is used for ethanol dehydration, then the reactor volume is larger, but the process consumes more steam and requires a caustic scrubber
Solution Approach 1:
The single reactor system is segmented into two separate reactors (first reactor and second reactor). The first reactor performs ethanol dehydration while the second reactor handles effluent processing. This segmentation eliminates the need for a caustic scrubber and reduces steam consumption by distributing the thermal load and enabling more efficient heat integration between the two reactor units.
2Volume of stationary object
If a caustic scrubber is included in the process, then the ethylene production is achieved, but the reactor section volume increases and steam consumption increases
Solution Approach 1:
The caustic scrubber unit is completely extracted and removed from the process flow. The functionality previously performed by the caustic scrubber is integrated into the two-reactor system, where the second reactor processes the effluent from the first reactor without requiring separate caustic treatment equipment. This extraction eliminates the additional volume and steam consumption associated with caustic scrubbing operations.
3Productivity
If steam is mixed with ethanol in a charge heater before reactor, then dehydration efficiency is improved, but steam consumption increases
Solution Approach 1:
The charge heater and reactor systems are merged and optimized across two units. Steam is introduced in the charge heater before the first reactor to enhance dehydration kinetics, but the second reactor is designed to efficiently process the resulting effluent with minimized additional steam requirements. This merging and optimization of the heating and reaction systems across two reactors improves overall conversion efficiency while reducing total steam consumption compared to a single-reactor design.
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 ethanol conversion to ethylene efficiency, achieving high selectivity and conversion rates while minimizing reactor size and steam consumption, allowing ethylene production suitable for further processing without the need for a caustic scrubber.
Implementation Method 1
mixing steam with said first portion at said charge heater and sending an ethanol/steam mixture to said reactor
Implementation Method 2
sending said first portion to a reactor through a charge heater
Implementation Method 3
subjecting said ethanol/steam mixture to sufficient conditions to dehydrate said ethanol to produce an effluent comprising ethylene and water
Data Source
AI summary
A process for dehydration of ethanol to produce ethylene is provided. Ethanol is dehydrated to produce ethylene and the subsequent conversion of ethylene to longer chain olefins and then their hydrogenation to produce long chain paraffins. In some embodiments, a split feed is employed to improve efficiency and a caustic wash column is eliminated. The advantages of the process include a lower requirement for steam and a reduction in the combined reactor volume of 30-40% when two reactors are used as compared to a single reactor.