Azeotropic Vaporization for Styrene Production Steam Ratios
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Solution Overview
Problem
Existing processes for the dehydrogenation of ethylbenzene to styrene face limitations in controlling the steam to oil weight ratio, which can lead to excessive furnace and transfer line temperatures when operating at lower overall steam to oil ratios, exceeding metallurgical limitations and impacting energy efficiency.
Innovation Solution
A process that utilizes only a portion of the ethylbenzene/styrene monomer splitter overheads for azeotropic vaporization, allowing for flexible operation at lower overall steam to oil weight ratios by adjusting the steam input while maintaining sufficient reactor effluent reheat capacity, and combining the azeotropic vaporization product with additional ethylbenzene and steam to achieve the desired ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the overall steam to oil weight ratio is reduced to improve energy efficiency, then energy requirements are reduced, but furnace and transfer line temperatures exceed metallurgical limitations
Solution Approach 1:
The steam input is segmented into two distinct components: main steam fed to the reactors and process steam generated by azeotropic vaporization. This segmentation allows independent control of each steam source, enabling reduction of overall steam-to-oil ratio while maintaining sufficient main steam to control reaction temperatures within metallurgical limitations.
Solution Approach 2:
The invention changes the physical state and source of steam by generating process steam through azeotropic vaporization of ethylbenzene-water mixtures. This parameter change allows flexible adjustment of the overall steam-to-oil ratio while maintaining adequate main steam for temperature control, resolving the contradiction between energy efficiency and temperature management.
2Adaptability or versatility
If only a portion of splitter overheads is used for azeotropic vaporization, then flexibility to operate at lower steam to oil ratios is improved, but control complexity increases
Solution Approach 1:
The azeotropic vaporization system is self-regulating through the natural equilibrium of the ethylbenzene-water azeotrope. By feeding liquid overheads and generating vapor in situ, the system automatically adjusts steam generation based on feed composition and demand, providing operational flexibility without requiring complex external control mechanisms.
Solution Approach 2:
The invention merges the ethylbenzene recycle stream with water to form an azeotropic mixture that vaporizes to provide process steam. This combination creates a self-regulating system where the azeotropic composition naturally controls the steam generation, achieving flexibility while simplifying control through the inherent properties of the mixed system.
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
Enables operation at lower overall steam to oil weight ratios without reducing the main steam to oil ratio, reducing energy requirements and maintaining heat recovery efficiency, thus avoiding metallurgical limitations and optimizing energy use in styrene production.
Implementation Method 1
azeotropic vaporization of the liquid ethylbenzene and water feeds to the dehydrogenation reactor
Implementation Method 2
indirect heat exchange with ethylbenzene (recycle and/or fresh) and water
Implementation Method 3
dehydrogenation of ethylbenzene to styrene takes place
Implementation Method 4
SM is manufactured by dehydrogenating the EB feed, which is an endothermic reaction
Implementation Method 5
Main Steam (MS), which is provided from a steam superheater
Implementation Method 6
The effluent from each reactor 26 may be reheated using steam before entering the next reactor 26
Data Source
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AI summary
A process for dehydrogenation of alkylaromatic hydrocarbon, including: contacting a reactant vapor stream, comprising an alkylaromatic hydrocarbon and steam and having a first steam to alkylaromatic hydrocarbon ratio, with a dehydrogenation catalyst to form a vapor phase effluent comprising a product hydrocarbon, the steam, and unreacted alkylaromatic hydrocarbon; feeding at least a portion of the effluent to a splitter to separate the product hydrocarbon from the unreacted alkylaromatic hydrocarbon; recovered from the splitter as bottoms and overheads fractions, respectively; recovering heat from a first portion of said overheads fraction by indirect heat exchange with a mixture comprising alkylaromatic hydrocarbon and water to at least partially condense said portion and to form an azeotropic vaporization product comprising alkylaromatic vapor and steam having a second steam to alkylaromatic hydrocarbon ratio; and combining the azeotropic vaporization product with additional alkylaromatic hydrocarbon and additional steam, together or separately, to form the reactant vapor stream.