Hydraulic Wash Column Front Position Control

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Solution Overview

Problem

Hydraulic washing columns face challenges in maintaining the optimal position of the build-up front, which affects the efficiency and stability of the crystal bed transport and separation process, particularly due to fluctuations in mass flow and crystal content, leading to inefficiencies in crystal purification and product yield.

Innovation Solution

The method involves using pressure differences (ΔP SK) to determine and control the mass flows of control liquor and suspension fed into the washing column, adjusting for hydrostatic pressure to precisely regulate the position of the build-up front, ensuring consistent operation and high purity of the separated crystals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the position of the build-up front is regulated by adjusting the mass flow of control liquor and suspension, then the stability of crystal bed transport is improved, but the complexity of the control system increases

Engineering Contradiction:
Improvestability of build-up front positionVSAvoidcontrol system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent implements a feedback control mechanism where the position of the build-up front is continuously monitored and used to adjust the mass flow of control liquor and suspension. The control system measures the actual position and compares it with the desired position, then automatically adjusts the flow rates to maintain optimal operation, thereby improving stability without requiring overly complex manual control procedures

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system is designed to automatically regulate itself by using the measured build-up front position to determine the required adjustments in mass flow. The system performs self-adjustment without requiring external intervention, simplifying the overall control architecture while maintaining stable operation of the crystal bed transport

Inventive Principle:
Principle #25Self-service

2Measurement precision

If pressure differences are used to determine mass flows, then the measurement precision is improved, but the device complexity increases

Engineering Contradiction:
Improvemass flow measurement precisionVSAvoidpressure measurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses pressure difference as an intermediary parameter to determine mass flow rates. Instead of directly measuring mass flow, the system measures pressure differences at various points in the system, which are then used to calculate the mass flow of control liquor and suspension. This indirect measurement approach improves precision while avoiding the complexity of direct mass flow sensors

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The control system replaces direct mechanical mass flow measurement with pressure-based measurement. By using pressure sensors and calculations based on pressure differences, the system achieves accurate mass flow determination without requiring complex mechanical flow meters or direct measurement devices

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If the build-up front position is not properly regulated, then the device complexity remains low, but the productivity decreases

Engineering Contradiction:
Improvecrystal purification efficiencyVSAvoidcontrol mechanism complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements dynamic control of the build-up front position by continuously adjusting the mass flow of control liquor and suspension based on real-time position measurements. The control system adapts to changing operating conditions and maintains optimal front position, ensuring high crystal purification efficiency without requiring overly complex static control mechanisms

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 approach enhances the economic efficiency and stability of the hydraulic washing column operation by allowing continuous control of the crystal bed transport and separation, improving the purity and yield of the purified crystals, particularly effective for acrylic acid crystals.

Implementation Method 1

the crystal bed is transported (13) past the filters into the washing zone located between the filters and the second end of the washing column (12) by the force resulting from the hydraulic flow pressure loss of the mother and optionally control liquor guide in the column

Methodology Applied
Scientific EffectHydraulic flow pressure loss: Pressure Drop

Implementation Method 2

the end of the crystal bed opposite the construction front continuously removes crystals (14), melts the removed crystals (15) and directs part of the melt as a washing liquid stream from the second end of the column through the crystal bed against the transport direction of the crystals (16)

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP1874422B1Method for the regulation of a hydraulic wash column
Publication Date: 2008.10.08 BASF SE
  • EP1874422B1 patent drawingFigure 1
  • EP1874422B1 patent drawingFigure 2
  • EP1874422B1 patent drawingFigure 3

AI summary

Disclosed is a method for operating a hydraulic wash column, in which the position of the wash front in the wash column is determined by means of the rate of flow of the control liquor conducted into the wash column and/or by means of the rate of flow of the suspension conducted into the wash column, and the rate of flow is defined with the aid of the difference in pressure between points in the suspension zone located upstream of the wash front and points in the zone extending from the wash front to the end of the crystal bed in the column.