Ethylene Carbonate Purification via Countercurrent Crystallization

Solution Overview

Problem

Current methods for purifying ethylene carbonate, such as distillation and crystallization, fail to achieve high purity due to thermal deterioration and residual impurities, with distillation consuming excessive energy and crystallization incorporating impurities in the crystals.

Innovation Solution

A countercurrent crystallization process where crude ethylene carbonate crystals fall and melt in a tower, with a solid-liquid countercurrent contact region maintained at a constant temperature, allowing for extended contact time and reduced temperature differences to achieve high purity ethylene carbonate without intermittent crystal shifting or scraping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If distillation is used to purify ethylene carbonate, then purification is achieved, but thermal deterioration occurs and energy consumption is high

Engineering Contradiction:

Improvepurity of ethylene carbonateVSAvoidthermal deterioration and polymerization

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The invention changes the operating parameters from high-temperature distillation to low-temperature crystallization. By controlling temperature to remain below the melting point of ethylene carbonate (−30°C to −100°C) during crystallization, the process avoids thermal deterioration and polymerization while achieving high purity (99.9% or higher).

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention utilizes the phase transition of ethylene carbonate from liquid to crystal form through controlled cooling. The crystallization process exploits the freezing point transition to separate pure ethylene carbonate crystals from impurities, avoiding the need for high-temperature distillation that causes decomposition.

Inventive Principle:

Principle #36Phase transitions

2Manufacturing precision

If distillation is used to purify ethylene carbonate, then purification is achieved, but energy consumption is high

Engineering Contradiction:

Improvepurity of ethylene carbonateVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The invention changes the operating parameters from high-temperature distillation to low-temperature crystallization. By controlling temperature to remain below the melting point of ethylene carbonate (−30°C to −100°C) during crystallization, the process avoids thermal deterioration and polymerization while achieving high purity (99.9% or higher).

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention utilizes the phase transition of ethylene carbonate from liquid to crystal form through controlled cooling. The crystallization process exploits the freezing point transition to separate pure ethylene carbonate crystals from impurities, avoiding the need for high-temperature distillation that causes decomposition.

Inventive Principle:

Principle #36Phase transitions

3Use of energy by stationary object

If crystallization is used to purify ethylene carbonate, then energy consumption is low, but impurities are occluded in the crystals

Engineering Contradiction:

Improveenergy consumptionVSAvoidpurity of ethylene carbonate

Core Design Contradiction:

Use of energy by stationary objectVSManufacturing precision

Solution Approach 1:

The invention performs preliminary purification by removing diols and water through molecular sieves or distillation before crystallization. This pre-treatment ensures that impurities do not get occluded in the crystals during the low-temperature crystallization process, achieving both low energy consumption and high purity (99.9% or higher).

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention employs dynamic control of temperature and crystallization conditions to prevent impurity occlusion. By maintaining temperature below the melting point and controlling the crystallization rate, the process dynamically adjusts to exclude impurities from the crystal lattice while keeping energy consumption low.

Inventive Principle:

Principle #15Dynamics

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 process results in ethylene carbonate with significantly reduced diol content, achieving continuous high-purity production without the need for crystal scraping and reducing energy consumption.

Implementation Method 1

melting the crude ethylene carbonate crystals in a bottom portion of the tower

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

allowing the remainder of the obtained melt to flow upward as a reflux liquid for countercurrent contact with the falling crude ethylene carbonate crystals

Methodology Applied

Scientific EffectCountercurrent flow: Convection

Implementation Method 3

allowing crude ethylene carbonate crystals to fall from an upper portion of a tower

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentEP1997817B1Process for purifying ethylene carbonate and process for producing purified ethylene carbonate

Publication Date: 2017.04.19 TSUKISHIMA KIKAI CO LTD

Figure 1

AI summary

Ethylene carbonate having a highly reduced content of especially diols is provided. A process for purifying ethylene carbonate, including falling crude ethylene carbonate crystals from an upper portion of a tower, melting the crude ethylene carbonate crystal in a bottom portion of the tower, withdrawing a part of the obtained melt from the tower, and flowing the remainder of the obtained melt as a reflux liquid upward for countercurrent contact with the falling crude ethylene carbonate crystals, characterized in that a solid-liquid countercurrent contact region maintained at a constant temperature is formed.