Ammonium Sulfate Crystallization with Three-Phase Organic Separation
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Solution Overview
Problem
Existing processes for producing ammonium sulfate from ε-caprolactam production streams face challenges in handling organic impurities, leading to costly wastewater treatment and reduced yield due to the need for harsh conditions like high pressures and temperatures, and incomplete oxidation of organic components.
Innovation Solution
A process involving multiple extraction and evaporative crystallization steps to separate and purify ammonium sulfate phases, producing a high-grade crystalline product while generating a usable oily phase, without requiring high pressures or pure oxygen, thus reducing energy consumption and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet air oxidation is used to treat aqueous ammonium sulfate phases containing organic components, then organic components are oxidized, but high pressures and temperatures are required leading to high energy consumption
Solution Approach 1:
The invention changes the parameters of the oxidation process by using atmospheric pressure and temperatures below 100°C instead of the high pressures (3-50 atm) and high temperatures (120-200°C) required by wet air oxidation. This is achieved by using a different oxidation approach that operates under milder conditions while still effectively removing organic components.
Solution Approach 2:
The invention uses air (atmospheric oxygen) instead of pure oxygen or other expensive oxidizing agents. Air is freely available and requires no special handling or storage infrastructure, dramatically reducing both capital and operational costs compared to wet air oxidation systems that require pure oxygen supply and high-pressure equipment.
2Manufacturing precision
If purging is performed during evaporative crystallization to reduce organic component incorporation, then crystal purity is improved, but valuable ammonium sulfate is removed requiring costly wastewater treatment
Solution Approach 1:
The invention converts the harmful organic components into a beneficial separable phase. By controlling the evaporation process to form a three-phase system, the organic impurities are concentrated into a distinct oily phase that separates from the crystalline ammonium sulfate, turning the contamination problem into a separation opportunity.
Solution Approach 2:
The invention utilizes phase transitions by controlling evaporation to create a three-phase system consisting of crystalline solid (ammonium sulfate), liquid aqueous phase, and liquid oily phase (organic impurities). This phase separation allows the organic components to be removed in the oily phase while the ammonium sulfate crystallizes in pure form, eliminating the need for purging.
3Reliability
If wet air oxidation is used to treat mother liquor and purge streams, then organic components are removed, but the process requires pure oxygen and high pressures increasing device complexity
Solution Approach 1:
The invention replaces expensive, complex wet air oxidation equipment with simple atmospheric evaporation equipment. By using air instead of pure oxygen and operating at atmospheric pressure, the process eliminates the need for oxygen storage tanks, high-pressure pumps, and specialized oxidation reactors, dramatically simplifying the equipment requirements.
4Productivity
If incomplete oxidation of organic components occurs in wet air oxidation, then treatment efficiency is reduced, but additional treatment steps are required increasing process complexity
Solution Approach 1:
The invention achieves complete separation of organic components through phase transition during controlled evaporation. The organic impurities form a distinct oily phase that separates from the crystalline ammonium sulfate, providing complete removal in a single step without requiring multiple treatment stages or additional processing 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
The process achieves high-quality ammonium sulfate and ε-caprolactam production with reduced waste and lower operational costs, improving the overall carbon footprint and economic efficiency.
Implementation Method 1
The first aqueous ammonium sulfate phase is usually extracted with an organic solvent to remove residual amounts of ε-caprolactam
Implementation Method 2
the organic components become concentrated in the aqueous phase and easily incorporate into the forming ammonium sulfate crystals during evaporative crystallization
Implementation Method 3
evaporative type crystallization is performed so that a three-phase system occurs: (1) a liquid oily phase comprising organic components; (2) a crystalline ammonium sulfate phase; and (3) a liquid aqueous ammonium sulfate comprising phase
Data Source
Figure 1A~1B
Figure 1C
Figure 2
AI summary
The invention provides a process for the production of crystalline ammonium sulfate, wherein the process comprises performing a Beckmann rearrangement reaction, neutralizing the Beckmann rearrangement reaction mixture, separating a first aqueous ammonium sulfate phase and an aqueous ε-caprolactam phase, charging the first ammonium sulfate phase to a first evaporative type crystallization section wherein crystalline ammonium sulfate is obtained, discharging from the first evaporative type crystallization section mother liquor enriched in organic components, extracting the aqueous ε-caprolactam phase to obtain an extracted ε-caprolactam phase and a second aqueous ammonium sulfate phase, discharging the mother liquor that is discharged from the first evaporative type crystallization section and/or the second aqueous ammonium sulfate phase to a second evaporative type crystallization section wherein evaporative type crystallization is performed so that a three-phase system occurs. At least a liquid oily phase is recovered from the three-phase system. The invention further provides a plant suitable to carry out the process of the invention, crystalline ammonium sulfate and a liquid oily phase obtained by the process of the invention.