Cyclohexanone Distillation Fouling Reduction
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Solution Overview
Problem
The conventional process for preparing cyclohexanone from phenol results in severe fouling and increased energy consumption in post-distillation sections, leading to frequent plant shutdowns and reduced production capacity.
Innovation Solution
An additional separation step is introduced in the process, involving multiple distillation sections to separate phenol and cyclohexanol-rich fractions, reducing fouling and energy consumption by recycling enriched phenol fractions back into the hydrogenation section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional post-distillation sections are used to separate phenol and cyclohexanol, then separation of product fractions is achieved, but severe fouling occurs and energy consumption increases
Solution Approach 1:
The patent divides the post-distillation separation into multiple sequential sections (first post-distillation section, second post-distillation section, and optional third post-distillation section). Each section performs a specific separation function, with the first section removing light components, the second section separating phenol-rich from cyclohexanol-rich fractions, and the third section further purifying the phenol fraction. This segmentation reduces fouling in each individual section compared to a single comprehensive separation unit.
Solution Approach 2:
The patent introduces an intermediate phenol-rich fraction that is recycled back to the hydrogenation section. This intermediate fraction acts as a mediator, allowing the separation process to continue efficiently while the recycled phenol reduces fouling in subsequent distillation sections by maintaining lower temperatures and reducing residue formation.
2Manufacturing precision
If conventional post-distillation sections are used to separate phenol and cyclohexanol, then product fractions are separated, but energy consumption increases
Solution Approach 1:
The patent implements a feedback loop where the phenol-rich fraction from the second post-distillation section is recycled back to the hydrogenation section. This feedback mechanism allows the system to maintain separation efficiency while reducing energy consumption by utilizing the recycled phenol to lower temperatures in subsequent distillation steps, thereby reducing the energy required for heating and vaporization.
Solution Approach 2:
The patent changes operational parameters across multiple distillation sections, with each section operating at optimized temperature, pressure, and flow rates. The first section operates at higher temperatures to remove light components, while subsequent sections operate at lower temperatures to separate phenol and cyclohexanol efficiently. This parameter optimization reduces overall energy consumption while maintaining separation efficiency.
3Object-generated harmful factors
If frequent plant shutdowns are performed for cleaning, then fouling is removed, but production capacity is reduced
Solution Approach 1:
The patent performs preliminary separation actions in multiple sequential distillation sections that prevent severe fouling from accumulating in the first place. By continuously removing light components and separating phenol-rich from cyclohexanol-rich fractions in controlled environments, the system reduces the frequency and intensity of required cleaning operations, thereby maintaining higher production capacity.
Solution Approach 2:
The patent enables continuous operation with minimal shutdowns by implementing a multi-section distillation system that continuously manages and removes fouling-prone components. The sequential separation process operates continuously, with the phenol-rich fraction being recycled back to the hydrogenation section, maintaining steady-state operation and reducing the need for interruptive cleaning shutdowns.
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 significantly reduces fouling, decreases energy losses, and allows for continuous production of cyclohexanone with increased production capacity, minimizing the need for plant shutdowns and maintaining high separation efficiency.
Implementation Method 1
separating at least part of the product stream, or at least part of the product stream from which one or more components having a lower boiling point than cyclohexanone have been removed, into a first fraction comprising cyclohexanone and a second fraction comprising phenol, cyclohexanol, using distillation
Data Source
AI summary
The present invention relates to a method for continuously preparing cyclohexanone from phenol making use of a catalyst comprising at least one catalytically active metal selected from platinum and palladium comprising hydrogenating phenol to form a product stream comprising cyclohexanone and unreacted phenol; separating at least part of the product stream, or at least part of the product stream from which one or more components having a lower boiling point than cyclohexanone have been removed, into a first fraction comprising cyclohexanone and a second fraction comprising phenol and cyclohexanol, using distillation; separating the second fraction into a third fraction, rich in cyclohexanol, and a fourth fraction, rich in phenol, using distillation; —subjecting at least part of the fourth fraction to a further distillation step, thereby forming a fifth fraction and a sixth fraction, wherein the fifth fraction is enriched in phenol compared to the sixth fraction, and wherein the sixth fraction comprises side-products having a higher boiling point than phenol, and phenol; and which method is characterized in the additional step of continuously or intermittently separating at least part of the sixth fraction to yet a further distillation step, thereby forming a seventh fraction and an eight fraction, wherein the seventh fraction is enriched in phenol compared to the eight fraction, and wherein the eight fraction comprises side-products having a higher boiling point than phenol.