Multitubular Ethanol Dehydrogenation with Condensing Heat-Transfer Fluid
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Solution Overview
Problem
Existing technologies for the dehydrogenation of ethanol to produce acetaldehyde face challenges in achieving satisfactory conversion and selectivity while avoiding catalyst deactivation and minimizing utility consumption and costs.
Innovation Solution
A process using a multitubular reactor with a heat-transfer fluid condensation system, where ethanol is dehydrogenated at an inlet temperature of 240°C to 350°C, and a heat-transfer fluid circulates in the shell to maintain isothermal conditions, utilizing the phase-change enthalpy to provide necessary heat without steam dilution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional dehydrogenation processes are used, then ethanol conversion can be achieved, but catalyst deactivation occurs and utility consumption increases
Solution Approach 1:
The patent employs a heat-transfer fluid that undergoes phase transition (vaporization) to provide thermal energy for the endothermic dehydrogenation reaction. The fluid is introduced in liquid form, vaporizes within the reactor, and provides heat through its phase change, maintaining isothermal conditions and preventing catalyst deactivation while achieving satisfactory ethanol conversion
Solution Approach 2:
The patent introduces a heat-transfer fluid as an intermediary substance that mediates heat transfer between the heat source and the reaction zone. This fluid circulates through the reactor, absorbing and releasing thermal energy to maintain optimal reaction temperature, thereby protecting the catalyst from deactivation and sustaining productivity
2Temperature
If steam dilution is used to manage heat, then thermal compensation is achieved, but capital and operating costs increase
Solution Approach 1:
The patent replaces steam dilution with a dedicated heat-transfer fluid that undergoes phase transition to provide thermal compensation. This fluid is introduced in liquid form, vaporizes within the reactor to provide heat, and condenses in the condensation zone, achieving thermal management without requiring steam dilution and reducing process complexity
Solution Approach 2:
The heat-transfer fluid serves as an intermediary that handles thermal compensation independently from the main reaction process. It circulates through the reactor, providing heat where needed and condensing in the condensation zone, thereby managing temperature without requiring steam dilution and simplifying the overall process
3Productivity
If multiple catalytic beds are used to increase conversion, then ethanol conversion improves, but capital costs increase
Solution Approach 1:
The patent uses a single catalytic bed with a heat-transfer fluid that undergoes phase transition to provide continuous heat supply. This eliminates the need for multiple catalytic beds, as the phase-changing fluid maintains isothermal conditions throughout the single reactor, reducing capital costs while achieving satisfactory conversion
Solution Approach 2:
The heat-transfer fluid acts as an intermediary that enables effective heat management in a single catalytic bed. By circulating through the reactor and undergoing phase change, it provides continuous thermal energy to maintain optimal reaction conditions, eliminating the need for multiple beds and reducing system complexity
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 achieves ethanol conversion of 25% to 35% and acetaldehyde selectivity of over 90%, reducing capital and operating costs by avoiding steam dilution and multiple catalytic beds.
Implementation Method 1
a heat-transfer fluid circulating in said shell so that said heat-transfer fluid is introduced into said shell in gaseous form and is, at the shell outlet, at least partly in liquid form
Implementation Method 2
utilizing the phase-change enthalpy to provide necessary heat without steam dilution
Implementation Method 3
The ethanol dehydrogenation reaction is an equilibrium reaction which exhibits degrees of conversion of the ethanol conventionally in the vicinity of 30%. It is a highly endothermic reaction (AH reaction=72.4 kJ/mol).
Implementation Method 4
a heat-transfer fluid circulating in said shell so that said heat-transfer fluid is introduced into said shell in gaseous form and is, at the shell outlet, at least partly in liquid form
Data Source
AI summary
The invention relates to a process for the dehydrogenation of a feedstock comprising ethanol, using at least one multitubular reactor advantageously comprising a plurality of tubes comprising at least one dehydrogenation catalyst, and a calender, said feedstock being introduced into the tubes in gas form, at an inlet temperature of greater than or equal to 240° C., a pressure between 0.1 and 1.0 MPa, and a WWH between 2 and 15 h−1, wherein a heat-transfer fluid circulates in said calender at a flow rate such that the weight ratio of said heat-transfer fluid relative to said feedstock is greater than or equal to 1.0, and such that said heat-transfer fluid is introduced into said calender in gas form at an inlet temperature of greater than or equal to 260° C. and at an inlet pressure of greater than or equal to 0.10 MPa, and less than or equal to 1.10 MPa, and leaves the calender at least partly in liquid form.