Dynamic Impeller Speed Control for Slurry Homogeneity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Continuous stirred-tank reactors experience splashing of slurry onto the vessel walls when the slurry level is near the impeller, leading to catalyst accumulation and potential blockages, despite the use of down- and up-pumping hydrofoil impellers, which can cause sedimentation and reactor failure.
Innovation Solution
Reducing the rotational speed of the impeller to a predetermined minimum speed when the slurry level is close to the impeller's upper or lower end, as calculated by the Zwietering equation, to prevent sedimentation and splashing, while maintaining homogeneity of the slurry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the rotational speed of the impeller is reduced to prevent splashing when slurry level is near the impeller, then splashing and catalyst accumulation on vessel walls is reduced, but sedimentation of particles in the slurry occurs
Solution Approach 1:
The impeller rotational speed is made dynamically adjustable based on real-time slurry level detection. When the slurry level approaches the impeller (within distance d), the rotational speed is reduced to prevent splashing; when the slurry level is far from the impeller, the rotational speed is increased to prevent sedimentation. This dynamic adjustment resolves the contradiction between preventing splashing and maintaining particle suspension stability.
Solution Approach 2:
A level detection device continuously monitors the slurry level and provides feedback to the control unit, which automatically adjusts the impeller rotational speed accordingly. This closed-loop feedback system ensures that the rotational speed is optimally adjusted in real-time based on the actual slurry level, preventing both splashing and sedimentation.
2Stability of the object's composition
If down- and up-pumping hydrofoil impellers are used to enhance mixing and reduce splashing, then mixing efficiency is improved, but splashing still occurs when slurry level is at the impeller level
Solution Approach 1:
Instead of relying solely on impeller design, the rotational speed is dynamically adjusted based on slurry level. This dynamic control complements the hydrofoil impeller design by reducing speed when the slurry level reaches the impeller, thereby eliminating splashing while maintaining mixing efficiency during normal operation.
Solution Approach 2:
The rotational speed parameter is changed in response to slurry level changes. By adjusting this operational parameter dynamically, the system optimizes both mixing efficiency and splashing prevention, overcoming the limitations of fixed impeller designs.
3Object-affected harmful factors
If the rotational speed of the impeller is significantly reduced to prevent splashing, then splashing is minimized, but sedimentation of particles occurs which can block the outlet and decrease reactor yield
Solution Approach 1:
The rotational speed is dynamically adjusted rather than significantly reduced. When slurry level is near the impeller, speed is temporarily reduced to prevent splashing; when slurry level is low, speed is increased to prevent sedimentation and maintain productivity. This dynamic approach minimizes splashing without sacrificing reactor yield.
Solution Approach 2:
The rotational speed varies periodically in response to the cyclic nature of slurry level changes during filling and withdrawal operations. This periodic adjustment ensures splashing prevention during critical phases while maintaining high productivity during normal operation.
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 significantly reduces splashing and prevents sedimentation, ensuring uninterrupted operation and maintaining slurry quality by minimizing material accumulation on the vessel walls and avoiding blockages, even during extended slurry withdrawal periods.
Implementation Method 1
rotating the at least one impeller at least around the vertical axis for homogenizing and/or maintaining a homogeneous particle distribution within the slurry
Implementation Method 2
the rotational speed n1 of the at least one impeller is higher than nmin according to equation (1)... nmin=minimum rotational speed of the impeller... to prevent sedimentation
Implementation Method 3
nmin=minimum rotational speed of the impeller... g = gravitational constant... to prevent sedimentation
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention is concerned with a process for providing a homogeneous particle-containing slurry comprising the steps of: (a) providing a vessel comprising at least one impeller rotating around a vertical axis of the vessel, wherein a rotational speed n1 of the at least one impeller is higher than nmin according to equation (1), the vessel further comprising an inlet and an outlet; (b) introducing a particle-containing slurry into the vessel or introducing components forming the particle-containing slurry into the vessel; (c) rotating the at least one impeller at least around the vertical axis for homogenizing and/or maintaining a homogeneous particle distribution within the slurry; (d) withdrawing the homogeneous particle-containing slurry via the outlet; (e) reducing the rotational speed n1 of the at least one impeller to a reduced rotational speed nred, whereas nred is lower than n1 and higher or equal than nmin according to equation (1): nmin=Sv0.1Dp0.2gΔρρf0.45B0.13Da0.85