Fracturing Blender Tub Level Control Using Pump Pressure Feedback
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Solution Overview
Problem
Conventional blender tub level control systems in hydraulic fracturing systems rely solely on pump rate adjustments, which can lead to inefficiencies and overfilling or underfilling due to variations in fluid flow rates, particularly when using gravity-fed water tanks.
Innovation Solution
Implementing a dual-control system that regulates suction pump pressure and inlet valve opening based on predetermined setpoints, in addition to tub level monitoring, to maintain consistent blender tub filling by adjusting suction pump speed and valve openness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pump rate adjustment control is used, then the system is simple to operate, but the tub level control precision deteriorates due to fluid flow rate variations
Solution Approach 1:
The control system is segmented into two independent control loops: an outer tub level control loop that monitors blender tub level and generates reference signals, and an inner suction pump pressure control loop that rapidly adjusts pump operation. This segmentation allows each loop to specialize in specific control tasks, improving overall precision without requiring a single overly complex system.
Solution Approach 2:
The system implements dual feedback mechanisms: tub level feedback from the blender tub level sensor provides long-term level information for reference signal generation, while suction pump pressure feedback from the pressure sensor provides rapid short-term adjustment information. This multi-level feedback structure enhances control precision by capturing both slow level changes and fast pressure fluctuations.
2Reliability
If only tub level monitoring is used, then the control system is simple, but overfilling or underfilling occurs due to fluid flow rate variations
Solution Approach 1:
The system generates reference signals in advance based on tub level measurements and fluid flow rate characteristics. These pre-calculated reference signals anticipate required pump adjustments before actual level deviations occur, enabling proactive correction and preventing overfilling or underfilling conditions.
Solution Approach 2:
Suction pump pressure serves as an intermediary parameter between tub level control and actual fluid delivery. The inner control loop uses pressure as a mediator to translate level-based reference signals into precise pump adjustments, accounting for fluid flow rate variations that directly affect pressure but not immediately reflected in level measurements.
3Productivity
If gravity-fed water tanks are used, then the system is simple to operate, but fluid delivery rate stability deteriorates
Solution Approach 1:
The system replaces purely mechanical gravity-fed operation with a controlled pump-based system. The suction pump, regulated by the dual-loop control system, substitutes for gravity as the driving force, enabling stable fluid delivery rates through active control rather than passive gravitational flow.
Solution Approach 2:
The control system dynamically adjusts pump operating parameters (speed, pressure) based on real-time measurements. By changing these parameters in response to actual system conditions, the system maintains stable fluid delivery rates despite variations in tank level, fluid properties, or demand conditions.
Data Source
AI summary
A method includes supplying a blender tub and a suction pump, the suction pump connected to the blender tub through a tub inlet valve and measuring a suction pump pressure. The method also includes determining if the suction pump pressure is above or below a predetermined suction pump pressure. In addition, the method includes raising the suction pump pressure if the suction pump pressure is below the predetermined suction pump pressure setpoint or lowering the suction pump pressure if the suction pump pressure is above the predetermined suction pump pressure setpoint.