CTA Solvent Exchange Pressure Filter Zone Optimization

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Solution Overview

Problem

Conventional solvent exchanging techniques for crude terephthalic acid (CTA) in the terephthalic acid (PTA) industrial apparatus require multiple stages and zones in pressure filters, leading to increased fault points, equipment size, energy consumption, and pressure drop issues, which affect productivity.

Innovation Solution

A two-stages-three-step CTA solvent exchanging method that reduces the number of zones by dividing the washing process into three steps, with washing liquor from the third step reused for the first and second steps, and external fresh water used in the final step, optimizing the pressure filter's zone division and reducing the overall number of zones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple stages and zones are used in pressure filters for solvent exchanging, then washing effectiveness is improved, but equipment complexity and fault points increase

Engineering Contradiction:
Improvewashing effectivenessVSAvoidequipment complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The pressure filter is divided into multiple zones (filtering zone, first washing zone, second washing zone, third washing zone, and drying zone) that work in sequence. Each zone performs a specific function, allowing the system to achieve thorough washing effectiveness while maintaining manageable complexity through functional segmentation rather than multiple separate equipment units.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If multiple stages and zones are used in pressure filters for solvent exchanging, then washing effectiveness is improved, but equipment size and investment increase

Engineering Contradiction:
Improvewashing effectivenessVSAvoidequipment size
Core Design Contradiction:
Manufacturing precisionVSVolume of stationary object

Solution Approach 1:

Multiple washing stages (first washing zone, second washing zone, third washing zone) and the drying function are merged into a single pressure filter unit. This integration achieves comprehensive washing effectiveness without requiring multiple separate equipment units, thereby reducing overall equipment size and investment while maintaining thorough washing performance.

Inventive Principle:
Principle #5Merging (Combining)

3Manufacturing precision

If more zones are added to the pressure filter, then washing effectiveness is improved, but processing capacity decreases due to smaller filtering area per zone

Engineering Contradiction:
Improvewashing effectivenessVSAvoidprocessing capacity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The pressure filter operates with multiple zones arranged circumferentially around a rotating drum, utilizing the rotational dimension to sequence different washing stages. This spatial arrangement allows each zone to maintain adequate filtering area while the system as a whole achieves comprehensive washing effectiveness through the sequential action of multiple zones during rotation.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

4Manufacturing precision

If conventional solvent exchanging technique is used, then impurities are removed, but energy consumption increases

Engineering Contradiction:
Improveimpurity removalVSAvoidenergy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The drying zone utilizes phase transition of water from liquid to vapor through heating, efficiently removing residual moisture from the filter cake. This phase transition-based drying method achieves thorough impurity removal and moisture elimination while consuming less energy compared to conventional multi-stage washing and drying processes.

Inventive Principle:
Principle #36Phase transitions

5Manufacturing precision

If conventional solvent exchanging technique is used, then impurities are removed, but pressure drop increases affecting productivity

Engineering Contradiction:
Improveimpurity removalVSAvoidproductivity
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The filtering zone performs preliminary separation and filtration of the slurry before the washing zones process the filter cake. This preliminary action removes bulk impurities and establishes a manageable filter cake structure, reducing the pressure drop that would otherwise occur during subsequent washing operations and maintaining higher productivity throughout the process.

Inventive Principle:
Principle #10Preliminary action

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 decreases equipment investment, energy consumption, and pressure drop, enhancing processing capacity by simplifying the processing flow and increasing the area of each zone, thereby improving the efficiency and productivity of the solvent exchanging process.

Implementation Method 1

separating solid particles and acetic acid in the CTA slurry gradually along with rotation of the pressure filter 1 to form a filter cake in the filtering zone

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 2

a second washing step for washing the filter cake processed by the first washing step in the second-step washing zone (8)

Methodology Applied
Scientific EffectSolvent extraction: Liquid-Liquid Extraction

Implementation Method 3

along with rotation of the pressure filter 1

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3524588B1CTA solvent exchanging method
Publication Date: 2024.02.28 TIANHUA INSTITUTE OF CHEMICAL MACHINERY AND AUTOMATION CO LTD
  • EP3524588B1 patent drawingFigure 1
  • EP3524588B1 patent drawingFigure 2
  • EP3524588B1 patent drawingFigure 3

AI summary

The present invention relates to a method for processing acetic acid solvent in Crude Terephthalic Acid (CTA) in an oxidized unit of a pure terephthalic acid (PTA) industrial apparatus. In the present invention, a filter cake in CTA is wahed by means of a two-stage-three-step method. The present invention further shortens the production process of solvent exchanging technique of CTA pressure filters, improves production capacity of a device, reduces investment of the device, reduces energy consumption of a system, and solves the shortcomings of the existing CTA solvent exchanging technique of the pressure filters.