Solutions for 'Flashing & Choked Flow'

In many industrial processes, flashing (the phase change from liquid to vapour) is deliberately induced. This is commonly achieved using flow devices such as fixed orifice plates or variable orifices, like control valves. Special Alloy Fabricators (SAF) has engineered a linear control valve with specialized trim designs tailored for flashing applications across diverse industries, including refineries, oil and gas, and Oil Sands operations.

This application reference highlights how SAF’s solution resolves challenges commonly encountered with traditional control valves in Steam Assisted Gravity Drainage (SAGD) processes for oil sands applications.

the problem

Conventional control valves used for flashing and choked flow, such as rotary-style valves with generic trim designs, face significant limitations in SAGD applications. These valves typically throttle at near-closed positions, generating excessive turbulence and leading to severe erosion-induced wear.

As a result, process control suffers, and internal components can deteriorate within a few months, necessitating complete valve replacements.

The Solution

SAF addressed these issues by replacing the client’s conventional rotary-style valves with SlurryFlo Control Valves, which were custom-designed for SAGD service. Key features include:

1. Optimized Trim Design

The trim is specifically engineered to accommodate high-pressure drops (needed to induce flashing) without over-throttling. Where a conventional valve might achieve the required process condition at 10% open, the SlurryFlo Control Valve accomplishes the same flow at 25% open while maintaining a streamlined, less erosive discharge jet.

2. Material Selection

All internal trim components are fabricated from sintered tungsten carbide, a material exceptionally resistant to energy-intensive flashing processes, particularly in the presence of solid particles. This toughness far exceeds steels and other alloys with hard-facing overlays, making it ideal for the demanding conditions in SAGD operations.

3. Bolt-on pipe accessory (ArmaSpool)

The ArmaSpool prevents downstream piping erosion by controlling and dispersing the discharge jet. This added safeguard is especially advantageous where frequent inspections or shutdowns for trim replacement are impractical. By mitigating pipe erosion risks, the valve can operate longer under severe conditions while reducing the risk of environmental incidents caused by potential pipe breaches.

The result

Upon inspection after one year of service, the installed SlurryFlo Control Valves showed close to zero wear. Originally placed in service in 2022, these valves have yet to require any repairs or replacements.

custom engineering
with cfd simulations

Computational Fluid Dynamics (CFD) simulations are integral to SAF’s engineering workflow for challenging flashing applications. Because each flow condition is unique, featuring multiphase fluids undergoing high-energy phase transitions, process engineers often need reliable, precise control over the flashing percentage of hydrocarbons.
For example, a process may demand 85% flashing at a specific pressure drop, achieved at an optimal valve throttling position while maintaining a streamlined discharge jet. Through extensive multiphase CFD simulations and iterative design, SAF optimizes each valve trim to meet the customer’s precise control objectives. These simulations also serve as a visual, data-driven demonstration of the engineered solution, rooted firmly in established principles of fluid mechanics.
By collaborating closely with clients from the early application engineering stages, SAF leverages simulation results to refine designs and deliver tailored solutions that consistently meet or exceed process requirements.
Flat Bottom Gate SlurryFlo Control Valve

The SlurryFlo Difference

SlurryFlo offers key advantages for applications involving flashing or choked flow conditions, including:
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Tailored process control.
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Ongoing engineering support.
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Custom trim geometry.
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Improved performance and reliability.
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3-10x longer service life.
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Lower total cost of ownership.
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