Variable Speed Pump Interface Control in Centrifugal Separators
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Solution Overview
Problem
Existing centrifugal separator control equipment is complex, expensive, and bulky, making it difficult to maintain a stable radial level of the interface layer between separated liquids, particularly in processes like oil and water separation, where uncontrollable heavy liquid discharge with solids leads to radial displacement of the interface layer.
Innovation Solution
A centrifugal separator with a variable speed pump as the pressure source, where the interface layer level detection controls the pump speed to manage the supply and discharge of liquid, eliminating the need for separate conduits and constant pressure valves, allowing for simple and effective control of the interface layer within predetermined radial levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate conduits and constant pressure valves are used for liquid supply and discharge, then the interface layer level can be controlled, but the device complexity and cost increase
Solution Approach 1:
The patent combines the liquid supply and discharge functions into a single conduit system. The variable speed pump integrates both supply and discharge operations through one conduit, eliminating the need for separate conduits and constant pressure valves. This merging reduces device complexity while maintaining the ability to control interface layer level through pump speed adjustment.
Solution Approach 2:
The single conduit is designed to serve multiple functions: it can supply liquid to the separation chamber and discharge liquid from the chamber through the same pathway. The variable speed pump provides multi-functionality by controlling both liquid inflow and outflow by adjusting its rotation speed, making the control system more compact and less complex.
2Stress or pressure
If gas compression systems and pressure vessels are used, then liquid pressure can be maintained, but the device size and cost increase
Solution Approach 1:
The patent replaces the traditional mechanical gas compression system and pressure vessels with a variable speed pump that directly controls liquid pressure through rotational mechanical energy. This substitution eliminates bulky pressure vessels and gas compression equipment, significantly reducing the overall size of the control system while maintaining effective liquid pressure for interface layer control.
Solution Approach 2:
Instead of using gas compression to maintain pressure, the system changes the control parameter to pump rotation speed. By adjusting the rotational speed of the variable speed pump, the liquid pressure is directly controlled without needing large pressure vessels or gas compression systems, thus reducing device volume while maintaining pressure control capability.
3Device complexity
If a variable speed pump is used instead of gas compression system, then the system becomes more compact and inexpensive, but control precision must be maintained
Solution Approach 1:
The patent implements a feedback control mechanism where the detected interface layer level is continuously monitored and used to adjust the variable speed pump operation. When the interface layer moves radially outward, the pump speed is increased to discharge more liquid; when it moves inward, the pump speed is reduced to decrease discharge. This feedback loop maintains measurement precision and control accuracy despite using a simpler variable speed pump system.
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 solution provides a compact, inexpensive, and efficient control system that maintains the interface layer within predetermined levels, preventing radial displacement and ensuring effective separation of liquids, such as oil and water, without the need for gas compression systems or pressure vessels.
Implementation Method 1
a centrifugal separator comprising a rotor, which is rotatable around a rotational axis and forms an inlet for said mixture and a separating chamber, which communicates with the inlet and which has a radially inner zone and a radially outer zone, said zones being adapted during a separating operation to contain separated light liquid and separated heavy liquid respectively
Implementation Method 2
an interface layer formed in the rotor's separating chamber between separated light liquid and separated heavy liquid
Data Source
Figure 1
AI summary
The invention relates to a centrifugal separator and method for controlling a radial level of an interface layer (22) formed during operation between a light and a heavy liquid in a separating chamber (7) in said centrifugal separator. The control comprises means (26) for detecting the interface layer level in the separating chamber, and a device (21, 23, 24) for supplying/discharging a control liquid to/from the separating chamber (7) by means of a variable speed pump (23), wherein said means (26) for detecting the interface layer level is adapted to communicate with means (25) for controlling the speed of the pump in such a way that supply and discharge of the liquid take place in such amount per unit of time that the interface layer (22) in the separating chamber (7) is within predetermined radial inner and outer levels.