Pressure Relief Valve Nozzle Geometry for Backpressure Flow Control
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Solution Overview
Problem
Pressure relief valves in gas processing facilities often require oversized designs due to deviations from idealized flow regimes, leading to bulkier and more expensive solutions, as they fail to maintain efficient flow rates under backpressure conditions.
Innovation Solution
A pressure relief valve design featuring a housing with a defined inlet and outlet, a seat forming a throat flow area, and a plunger that defines a curtain flow area, with a ratio of throat to curtain flow area optimized for sonic or supersonic velocities during critical flow and subsonic velocities during subcritical flow, mimicking the behavior of an ideal nozzle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pressure relief valves are sized to accommodate backpressure in sub-critical flow regime, then the valve can handle varying backpressure conditions, but the valve size increases and cost increases
Solution Approach 1:
The patent changes the geometric parameters of the valve flow passage, specifically designing a convergent-divergent nozzle shape with optimized throat area ratio. This geometric parameter optimization allows the valve to maintain critical flow conditions and achieve better backpressure recovery, reducing the required valve size for a given flow capacity.
Solution Approach 2:
The patent designs the flow passage geometry to dynamically adapt to varying backpressure conditions through the convergent-divergent shape. The nozzle geometry creates expanding flow areas that facilitate pressure recovery and maintain optimal flow characteristics across different operating conditions, eliminating the need for oversized valves.
2Productivity
If pressure relief valves are designed with idealized convergent-divergent nozzle geometry, then the flow capacity is optimized, but deviations from ideal flow regime reduce effectiveness
Solution Approach 1:
The patent applies local quality optimization by carefully designing different sections of the flow passage with specific geometric characteristics. The convergent section, throat, and divergent section each have optimized local geometries that collectively achieve near-ideal flow conditions, maintaining consistent critical flow regime even under varying backpressure.
3Reliability
If pressure relief valves are oversized to ensure sufficient flow rate under all conditions, then the flow capacity is adequate, but the valve becomes bulkier and more expensive
Solution Approach 1:
The patent incorporates preliminary action by designing the flow passage geometry to pre-condition the flow before it reaches the outlet. The convergent-divergent nozzle shape pre-accelerates and pre-pressurizes the flow, creating favorable flow conditions that maintain adequate flow rates without requiring oversized valve components.
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 design allows for smaller, more cost-effective pressure relief valves that maintain ideal flow rates, matching ISO and API standards, even under varying backpressure conditions, thereby reducing the need for oversized valves.
Implementation Method 1
A throat of the pressure relief valve lowers a pressure and increases a velocity of the fluid
Implementation Method 2
Flow through a pressure relief valve is idealized as the flow through a convergent-divergent nozzle
Implementation Method 3
An exit of a plunger increases the pressure and decreases the velocity of the fluid flow within the pressure relief valve
Implementation Method 4
In the critical flow regime, the mass flow through the relief valve is considered choked (or in critical flow) when the mass flow rate does not change with a change in back pressure
Implementation Method 5
For an idealized nozzle, the Mach number at the nozzle exit is equal to or greater than 1.0 as long as the exit area is equal to or greater than the throat area in the critical flow regime
Data Source
AI summary
A pressure relief valve includes the following features. A housing defines an inlet and an outlet. The housing defines a flow passage between the inlet and the outlet. A seat can be defined by the housing. The seat defines a throat flow area. A plunger is configured to rest upon the seat. The plunger blocks the flow passage when in a closed position. The plunger is configured to actuate between a fully open position and the closed position. The plunger and the seat can at least partially defining a curtain flow area. A bias directs the plunger towards the seat. A ratio of the throat flow area to the curtain flow area is sized for sonic or supersonic flow velocities during critical flow conditions and subsonic velocities during subcritical flow conditions.