Nitrobenzene Production Gas Separator for Phase Separation
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Solution Overview
Problem
The efficiency of nitrobenzene production is hindered by inadequate phase separation in adiabatic nitration processes, where the presence of a gas phase leads to turbulence and entrainment of organics into the aqueous phase, causing inefficiencies and operational challenges in separating liquid phases.
Innovation Solution
A continuous process involving adiabatic nitration of benzene with sulfuric and nitric acids, followed by gas separation to remove gaseous components before phase separation, optimizing the discharge of the gas phase and separation of liquid phases in a dedicated apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If adiabatic nitration is used to improve productivity and reduce energy consumption, then the reaction temperature rises significantly, but this causes excessive temperature that complicates phase separation and increases turbulence
Solution Approach 1:
The process is divided into distinct stages: adiabatic nitration reaction followed by controlled cooling and phase separation. By segmenting the temperature management, the reaction benefits from adiabatic heating while the separation stage operates at lower, more manageable temperatures.
Solution Approach 2:
The reaction mixture is cooled before phase separation occurs. This preliminary cooling action reduces the temperature and turbulence in the separation stage, making phase separation more efficient despite the high temperature generated during adiabatic reaction.
2Loss of energy
If gas phase is present during phase separation to maintain adiabatic conditions, then energy losses are reduced, but the gas phase causes turbulence and entrainment of organics into aqueous phase
Solution Approach 1:
Gas removal is performed as a separate, preliminary step before liquid-liquid phase separation. By dividing the separation process into gas removal then liquid separation, the harmful effects of gas-induced turbulence are eliminated while maintaining the benefits of adiabatic operation.
Solution Approach 2:
The gas phase is removed in advance before the liquid phases are separated. This preliminary gas removal action eliminates the source of turbulence and entrainment problems that would otherwise occur during phase separation.
3Temperature
If sulfuric acid excess is used to control adiabatic temperature jump, then temperature rise is limited, but this increases the amount of acid to be handled and complicates downstream processing
Solution Approach 1:
Instead of using a large static excess of sulfuric acid, the process dynamically controls temperature through controlled cooling after the reaction. This allows using near-stoichiometric amounts of acid while still managing the temperature rise effectively.
Solution Approach 2:
The process changes the temperature parameter after reaction by introducing controlled cooling. This parameter change allows the system to achieve temperature control without relying on large excesses of sulfuric acid, thereby reducing the quantity of acid that must be handled.
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 reduces turbulence and enhances phase separation efficiency, minimizing entrainment and sulfuric acid losses, leading to improved product quality and reduced energy consumption.
Implementation Method 1
first removing a gaseous phase comprising benzene and gaseous secondary components from the crude process product of the nitration in a gas separator provided specifically for this purpose
Implementation Method 2
separating the liquid phase thus obtained comprising nitrobenzene and sulfuric acid and depleted of gaseous constituents in a downstream phase separation apparatus into a sulfuric acid phase and a nitrobenzene phase
Implementation Method 3
nitrating benzene under adiabatic conditions with sulfuric acid and nitric acid
Implementation Method 4
the exothermicity of the reaction, once unavoidable heat losses are disregarded, is reflected quantitatively in the temperature difference between the temperature on entry into the nitration reactor and the temperature of the completely converted product mixture
Data Source
AI summary
The invention relates to a continuously operating process for producing nitrobenzene, comprising the following steps: a) nitriding benzene in adiabatic conditions with sulfuric acid and nitric acid, using a stoichiometric excess of benzene in relation to the nitric acid; b) first separating a gaseous phase containing benzene and gaseous secondary components from the raw process product of the nitridation in a gas separator provided specifically for this purpose, then separating, in a downstream phase-separating apparatus, the resulting liquid phase, which is depleted in gaseous components and contains nitrobenzene and sulfuric acid, into a sulfuric acid phase and a nitrobenzene phase; and c) processing the nitrobenzene phase, obtaining nitrobenzene. The invention also relates to a production plant suitable for carrying out the claimed process.