Ethylene Dehydration Reactor Thermal Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current ethanol dehydration processes to produce ethylene face challenges in maintaining high selectivity and energy efficiency, with increased energy consumption and byproduct formation due to the endothermic nature of the reaction and the need for external heat sources.
Innovation Solution
A process involving vaporization, superheating, and dehydration of ethanol in a multitubular reactor with a zeolitic catalyst, utilizing a heat transfer fluid to maintain optimal temperatures and pressures, and incorporating thermal integration to maximize heat exchange and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external heat sources are used to maintain reaction temperature, then the dehydration reaction can proceed at optimal temperature, but energy consumption increases
Solution Approach 1:
The patent combines the reaction reactor with a heat exchange system, merging the reaction zone and heat transfer zone into an integrated unit. The heat transfer fluid circulates through the reactor shell, directly heating the reaction mixture without requiring external heat sources, thereby reducing energy consumption while maintaining optimal reaction temperature.
Solution Approach 2:
The system uses the reaction mixture itself as the heat transfer medium. The ethanol-dehydration mixture circulates through the reactor shell, absorbing and distributing heat within the system without requiring external heating utilities. This self-heating mechanism reduces external energy input while maintaining reaction temperature.
2Temperature
If heat transfer fluid is introduced into the reactor, then reaction temperature is maintained, but byproduct formation increases due to equilibrium shift
Solution Approach 1:
The patent introduces an inert heat transfer fluid (such as molten salt or thermal oil) as an intermediary heating medium. This fluid transfers heat to the reaction mixture without participating in the chemical equilibrium, thus maintaining temperature while avoiding the equilibrium shift problem caused by introducing reactive heat carriers like steam or recycled ethylene.
3Temperature
If heat transfer fluid is used for heating, then reaction temperature is controlled, but operational complexity increases
Solution Approach 1:
The heat transfer fluid circulates continuously through the reactor shell, providing constant heat input without interruption. This continuous circulation system, equipped with pumps and heat exchangers, maintains stable reaction temperature automatically, reducing the need for manual temperature adjustments and simplifying operational control despite the added equipment.
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 ethanol conversion rates and ethylene selectivity while minimizing byproduct formation and energy consumption, maintaining efficient operation and reducing the risk of feedstock degradation.
Implementation Method 1
a stage for vaporizing a vaporization feedstock comprising said ethanol feedstock in an exchanger by means of a heat exchange with a dehydration effluent
Implementation Method 2
a stage for vaporizing a vaporization feedstock comprising said ethanol feedstock in an exchanger by means of a heat exchange
Implementation Method 3
a stage for dehydrating said superheated feedstock so as to produce a dehydration effluent, wherein said stage for dehydrating comprises a reaction section comprising at least one multitubular reactor in which the dehydration reaction takes place, said multitubular reactor comprising a plurality of tubes having a length of between 2 and 4 m and a shell, said tubes each comprising at least one fixed bed comprising at least one dehydration catalyst
Implementation Method 4
a heat transfer fluid circulating inside said shell at a mass flow rate such that the ratio of the mass flow rate of said heat transfer fluid in the shell relative to the mass flow rate of said superheated feedstock introduced into said tubes is greater than or equal to 10
Data Source
AI summary
A process for dehydrating an ethanol feedstock to give ethylene, includes:a) a vaporization stage;b) a heating stage;c) a dehydration stage in a multitubular reactor comprising tubes having a length of between 2 and 4 m, said tubes comprising a, preferably zeolitic, dehydration catalyst, the feedstock having an inlet temperature of greater than 400° C. and less than 550° C. and an inlet pressure of between 0.8 and 1.8 MPa, the heat transfer fluid having an inlet temperature of greater than 430° C. and less than 550° C. and a mass flow rate such that the ratio of the mass flow rates of the heat transfer fluid relative to the feedstock is greater than or equal to 10;d) separation into an effluent comprising ethylene and an aqueous effluent;e) purification of the aqueous effluent and separation of a stream of purified water and a stream of unconverted ethanol.