When Column Performance Drops, Operating Conditions Aren’t the Only Variable
Why changes in throughput, feed, or duty in Distillation Towers often require internals reassessment — not just operational adjustments
Column performance issues often emerge as operational efficiencies are optimized for new outputs. As throughput targets increase, recovery goals tighten, or energy balances are improved, the column may begin operating outside the conditions its internals were originally designed to support. In these cases, declining performance is not the result of poor operation — it is a signal that internals alignment needs to be reassessed to support the new operating objectives.
In many facilities, declining distillation column performance is first addressed operationally. Rates are adjusted, setpoints are refined, and operating windows are tightened to stabilize performance. These steps are necessary — but when performance losses persist, they often point to a deeper issue: the internals were not designed for how the column is being asked to perform today.
This is where engineered internals solutions — not operational workarounds — become essential.
Column Internals Are Designed Around Assumed Operating Conditions
Column internals are engineered based on defined assumptions: throughput, vapor and liquid traffic, feed characteristics, pressure drop limits, and separation efficiency targets. When a column operates within those assumptions, internals perform predictably.
However, modern plants rarely remain static. Energy optimization projects and recovery improvements intentionally push columns beyond their original design basis. As those goals evolve, internals must evolve with them — otherwise they become the limiting factor.
AMACS designs and manufactures column internals specifically to support changing performance targets, not just original design conditions. Their engineered approach allows internals to be reassessed and reconfigured to align with how the column operates today.
Operating Changes That Commonly Trigger Internals Misalignment
- Throughput Increases and Capacity Expansion: Throughput increases driven by optimization frequently push internals toward hydraulic limits. When vapor and liquid traffic exceed design assumptions, separation efficiency and stability suffer — even though the column itself remains mechanically sound.
- Feed Composition and Fouling Behavior Changes: Feedstock changes introduced to improve yield or flexibility can dramatically affect fouling rates and distribution behavior. Internals that performed well in earlier service may no longer provide adequate distribution or fouling resistance under new conditions.
- Duty and Energy Balance Optimization: Energy efficiency initiatives often alter reboiler or condenser duty. These changes shift vapor and liquid traffic inside the column, requiring internals that can support new hydraulic and mass transfer demands without sacrificing efficiency.
How Internals Misalignment Shows Up in the Field
When internals are no longer aligned with operating objectives, the symptoms are typically operational:
- Distillation column flooding or unstable hydraulics
- Increased pressure drop in distillation columns
- Entrainment or liquid carryover
- Loss of separation efficiency
- Increased fouling or maintenance frequency
These symptoms are often treated as operational issues. In reality, they are engineering signals — indicators that internals are no longer supporting the column’s performance goals.
AMACS’ engineered mist elimination and separation solutions are designed specifically to address entrainment, carryover, and phase separation challenges created by changing operating conditions.
Why Operational Adjustments for Column Efficiency Can Only Go So Far
Operational tuning can temporarily manage symptoms, but it does so by trading away margin — reducing throughput, increasing energy consumption, or accepting reduced efficiency. Over time, these compromises limit the value of operational improvements. At this stage, the constraint is not operations. The constraint is internals capability.
Engineered internals solutions allow performance objectives to be met without sacrificing reliability or efficiency.
When Internals Reassessment Becomes the Right Next Step
Internals reassessment becomes necessary when column performance issues persist despite operational tuning, or when operating conditions have clearly moved beyond the original design basis. Common triggers include sustained capacity increases, repeated flooding or pressure drop limitations, and rising reliability or maintenance concerns.
Reassessment is not about replacement for its own sake. It is about understanding whether existing internals are still aligned with current service requirements.
What Internals Reassessment Typically Involves
A structured internals reassessment evaluates how the column is operating today compared to how it was originally designed to operate. This typically includes reviewing hydraulic capacity, pressure drop limits, mass transfer performance, fouling behavior, and overall internals suitability for current throughput, feed, and duty.
The goal is to identify whether internals can be optimized, retrofitted, or replaced in a way that restores performance while minimizing disruption.
How AMACS Engineers Internals for Today’s Operating Reality
The quality dimensional inspector/engineer checking metal components.
AMACS’ approach goes beyond catalog replacements. Their team evaluates hydraulic capacity, mass transfer requirements, fouling behavior, and pressure drop limits to engineer internals solutions that align with current and future operating conditions.
Engineering tools such as computational fluid dynamics are used to validate internals performance under updated process conditions, reducing risk before implementation and ensuring solutions are grounded in real operating behavior.
Aligning Internals With Today’s Operating Reality
When operating conditions change, internals alignment becomes a key lever for restoring distillation column performance. Addressing misalignment early—before performance losses escalate into reliability issues—helps preserve operating margins and supports long-term unit stability.
Involving internals expertise early in performance discussions allows teams to make informed decisions based on current operating reality, rather than continuing to push equipment beyond its original design envelope.
Executing Internals Changes During Turnarounds
Reassessing internals is only effective if changes can be implemented reliably and efficiently. AMACS’ turnaround teams specialize in executing internals modifications during planned outages and performance-driven turnarounds.
By aligning engineering, fabrication, and field execution, AMACS ensures that internals upgrades support operational goals without extending outage durations or introducing unnecessary risk.
This integrated approach — engineered solutions paired with experienced turnaround execution — is what allows plants to convert performance targets into sustained results.
Final Takeaway
Column performance drops are often a signal, not a failure. When throughput, feed, or duty changes, column internals should be reassessed alongside operational adjustments. Aligning internals with today’s operating conditions is a critical step in restoring efficiency, protecting reliability, and maintaining stable operation over time.
AMACS supports internals evaluation, retrofit, and replacement when operating conditions change and column performance is impacted.