Non-Critical Air Flow Control for Dense Phase Conveying
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Solution Overview
Problem
Existing low pressure continuous dense phase pneumatic convey systems face inefficiencies due to critical air flow control systems, which result in excessive energy consumption and unnecessary air production, as they rely on constant supply pressure and venting of excess air, leading to increased power requirements and energy loss.
Innovation Solution
A non-critical air flow control system that adjusts the air supply pressure and control valve position dynamically based on real-time pressure readings, using pressure transducers and a controller to maintain a lower supply pressure relative to convey pressure, reducing energy consumption and minimizing air venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a critical air flow control system is used with constant supply pressure and mechanical relief valve, then the air flow rate is predictable and stable, but energy consumption increases significantly due to excessive air production and venting
Solution Approach 1:
The patent transitions from a static critical air flow control system with constant supply pressure to a dynamic non-critical control system where supply pressure varies with downstream pressure. The control valve dynamically adjusts to maintain a constant pressure differential (e.g., 3-5 psi) rather than maintaining constant absolute pressure, allowing the system to adapt to changing conveying conditions and minimize energy consumption while maintaining reliable air flow control.
Solution Approach 2:
The invention changes the fundamental operating parameters from critical air flow regime (where downstream pressure has no effect on flow rate) to non-critical air flow regime. By maintaining a constant pressure differential across the control valve rather than constant absolute supply pressure, the system operates in a regime where air flow rate is directly controllable by valve position, eliminating the need for excessive pressure generation and venting.
2Ease of operation
If supply pressure is held constant at a value significantly greater than convey pressure, then air flow through the control valve is unaffected by downstream pressure changes, but the power required to drive the air control system increases
Solution Approach 1:
The patent implements a feedback control mechanism where the control valve position is continuously adjusted based on the actual downstream convey pressure. The system maintains a constant pressure differential by using the downstream pressure signal to modulate the control valve, ensuring that supply pressure automatically adapts to conveying conditions. This eliminates the need for constant high supply pressure while maintaining simple and reliable air flow control.
3Reliability
If a mechanical relief valve is used to vent excess air, then constant supply pressure is maintained, but unnecessary air is compressed and vented to atmosphere causing energy loss
Solution Approach 1:
The patent removes the mechanical relief valve from the system entirely, extracting the energy-wasting component that vented excess air to atmosphere. Instead of generating constant high pressure and venting the difference, the system directly generates only the necessary pressure differential, eliminating the source of energy loss while maintaining supply pressure stability through dynamic control.
4Productivity
If the blower is throttled to match varying convey system pressure, then air supply matches demand, but the blower operates inefficiently fluctuating between small and large throttling amounts
Solution Approach 1:
The patent introduces a control valve as an intermediary device between the blower and the conveying system. Rather than having the blower directly throttle to match varying pressure demands (which causes inefficient operation), the control valve acts as a mediator that precisely regulates air flow based on downstream conditions. This allows the blower to operate at or near optimal efficiency while the control valve handles the fine adjustments needed to match air supply with conveying demand.
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 achieves a 30-40% energy savings by optimizing air flow and pressure differential, improving accuracy and reducing noise and heat generation, while allowing for more efficient particulate conveyance over longer distances with reduced energy use.
Implementation Method 1
a first pressure transducer for sensing a supply pressure, P1, produced by the air source... a second pressure transducer for sensing a convey pressure, P2
Implementation Method 2
based on a non-critical flow equation, control output of the air source (30) to obtain a desired supply pressure P1, and positioning of the control valve (32) to obtain a desired air flow rate
Data Source
AI summary
An air control system for a low pressure continuous dense phase convey system employs a non-critical air flow control system that allows for a supply pressure to be only incrementally larger than a convey pressure. The convey system has an inlet for introduction of pressurized air into the system and an airlock associated with a feedpoint for introduction of particulate into the system. A first pressure sensor is positioned immediately downstream of an air source to measure the supply pressure, and a second pressure transducer is positioned proximate an airlock to measure the convey pressure. The non-critical air flow control system is dependent on the supply and convey pressures and a position of a control valve, such as a sonic nozzle. The difference between the convey pressure and the supply pressure is less than 10% of the supply pressure.