Pingxiang Daier Separation Tech Aug 26, 2026

When Is Random Packing Suitable for TEG Gas Dehydration Contactors?

When Is Random Packing Suitable for TEG Gas Dehydration Contactors?

Introduction

Random packing can be used in some TEG gas dehydration contactors, but it is not automatically the best choice for every glycol absorber. Engineers should compare random packing with structured packing and trays based on gas capacity, glycol circulation rate, pressure drop, turndown, contamination risk, liquid distribution and retrofit constraints.

Triethylene glycol (TEG) dehydration is widely used to remove water vapor from natural gas before:

  • pipeline transportation;
  • compression;
  • cryogenic processing;
  • LNG pretreatment;
  • downstream gas processing.

Inside a TEG contactor, wet natural gas flows upward while lean glycol flows downward.

Water transfers from the gas phase into the glycol, producing:

  • dry gas at the top;
  • water-rich glycol at the bottom.

The contactor may use:

  • trays;
  • structured packing;
  • random packing.

The correct choice depends on the actual process and mechanical conditions.

This creates an important engineering question:

When is random packing a practical choice for a TEG dehydration contactor, and when should structured packing or trays be preferred instead?

1. What Does the TEG Contactor Actually Need to Do?

The purpose of the contactor is not simply to create gas-liquid contact.

It must achieve sufficient water removal while operating reliably over the expected gas and glycol flow range.

Important performance requirements include:

  • required dry-gas water content;
  • inlet gas water loading;
  • lean TEG concentration;
  • glycol circulation rate;
  • gas pressure;
  • temperature;
  • operating turndown.

Packing selection should therefore begin with the dehydration duty rather than with a preferred packing type.

2. Can Random Packing Be Used in a TEG Contactor?

Yes.

Random packing can be technically suitable in some TEG absorbers, especially when the design requires:

  • relatively low pressure drop;
  • simple packed-bed construction;
  • flexible retrofit installation;
  • acceptable mass-transfer efficiency;
  • moderate column size.

However, random packing should not be treated as the universal solution.

In some TEG systems:

  • structured packing may provide better mass-transfer efficiency or lower pressure drop;
  • trays may offer simpler liquid handling or better robustness under certain operating conditions.

The engineering decision is therefore:

Random Packing vs Structured Packing vs Trays

—not simply:

Which random packing should be purchased?

3. When Random Packing May Be a Good Choice

3.1 Retrofit of an Existing Packed Contactor

Random packing can be attractive when an existing column already contains:

  • packing support;
  • distributor system;
  • packed-bed space.

A retrofit may involve:

  • replacing older packing;
  • increasing open area;
  • reducing pressure drop;
  • improving capacity.

Random packing can sometimes be installed more easily than completely redesigning the column around trays.

But the existing internals must still be checked.

3.2 Pressure Drop Is Important

Gas dehydration contactors operate as part of a pressurized gas system.

Excessive column pressure drop may reduce:

  • available downstream pressure;
  • compressor efficiency;
  • overall process performance.

Open random packing geometries can provide relatively low resistance to gas flow.

Important packing characteristics include:

  • high void fraction;
  • open geometry;
  • suitable packing size;
  • low tendency toward liquid hold-up.

3.3 Moderate Separation Duty

For a contactor where required dehydration performance can be achieved without extremely high mass-transfer efficiency per unit bed height, random packing may provide a practical balance between:

  • performance;
  • pressure drop;
  • cost;
  • installation simplicity.

For more demanding dehydration targets or limited column height, structured packing may deserve closer evaluation.

3.4 Retrofit Cost Matters

In brownfield projects, the technically highest-performance packing is not always the most economical retrofit.

Random packing may provide advantages in:

  • procurement;
  • installation;
  • replacement;
  • maintenance.

The comparison should consider total modification cost rather than packing price alone.

4. When Structured Packing May Be Better

Random packing should not be forced into every TEG project.

Structured packing may be preferred when engineers need:

  • very low pressure drop;
  • high mass-transfer efficiency;
  • better performance within limited column height;
  • more predictable hydraulic behavior.

This can be especially important when:

  • the tower diameter is constrained;
  • packed height is limited;
  • high gas throughput is required;
  • dehydration specifications are demanding.

Therefore:

A random-packing supplier should not recommend random packing before comparing the hydraulic and mass-transfer requirements of the contactor.

This distinction is important for reliable engineering selection.

5. When Trays May Still Be Appropriate

Tray contactors remain relevant in glycol dehydration.

Possible reasons include:

  • established existing column design;
  • operating familiarity;
  • process turndown requirements;
  • maintenance strategy;
  • liquid handling characteristics.

A tray-to-packing conversion should therefore not be made only because packed columns can have lower pressure drop.

Engineers should first verify:

  • required mass transfer;
  • gas velocity;
  • liquid loading;
  • mechanical modifications;
  • distributor requirements;
  • available packed height.

6. TEG Circulation Rate Matters

TEG contactors may operate with relatively low liquid-to-gas ratios compared with some scrubber applications.

This makes liquid distribution especially important.

If glycol is poorly distributed across the packing bed:

  • parts of the packing may remain under-wetted;
  • effective mass-transfer area decreases;
  • dehydration performance becomes uneven;
  • theoretical packing efficiency may not be achieved.

For this reason, a high-quality liquid distributor can be as important as the packing itself.

7. Why Liquid Distribution Is Critical

Random packing does not automatically distribute lean glycol evenly.

The distributor must provide sufficient coverage across the bed.

Poor distribution can cause:

  • channeling;
  • dry zones;
  • reduced gas-liquid contact;
  • higher outlet water content.

The design should consider:

  • tower diameter;
  • glycol flow rate;
  • distributor drip-point density;
  • distributor turndown;
  • levelness.

For deeper packed beds, redistribution may also need evaluation.

8. Gas Velocity and Flooding

Gas velocity strongly affects TEG contactor hydraulics.

As gas velocity increases:

  • pressure drop increases;
  • liquid hold-up may increase;
  • entrainment risk rises;
  • flooding margin decreases.

Random packing should therefore be selected using actual hydraulic loading.

Engineers should evaluate:

  • gas mass flow;
  • gas density;
  • operating pressure;
  • glycol flow;
  • packing geometry;
  • packing factor.

Selecting packing only from nominal tower diameter is not sufficient.

9. Foaming and Contamination Can Control the Decision

One of the most important real-world issues in glycol systems is contamination.

TEG may become contaminated by:

  • compressor oil;
  • hydrocarbons;
  • corrosion products;
  • solids;
  • degraded glycol;
  • process chemicals.

Contamination can promote:

  • foaming;
  • fouling;
  • reduced mass transfer;
  • liquid carryover.

A theoretically high-efficiency packing may perform poorly if the glycol system is dirty.

For contaminated service, engineers may prefer packing with:

  • open geometry;
  • lower fouling sensitivity;
  • easier cleaning characteristics.

Upstream separation and glycol filtration should also be reviewed.

10. Hydrocarbon Condensation Must Be Considered

Natural gas entering the TEG contactor may contain heavier hydrocarbons.

Changes in:

  • pressure;
  • temperature;
  • gas composition

can result in hydrocarbon condensation.

Condensed hydrocarbons may interfere with:

  • glycol wetting;
  • mass transfer;
  • hydraulic behavior.

Before selecting packing, engineers should therefore understand whether the gas is near:

  • hydrocarbon dew point;
  • water dew point.

Packing selection cannot compensate for poor upstream phase separation.

11. Packing Size Selection

Packing size affects both efficiency and hydraulic capacity.

Smaller Random Packing

Potential advantages:

  • greater specific surface area;
  • improved mass-transfer potential.

Potential limitations:

  • higher pressure drop;
  • increased liquid hold-up;
  • greater sensitivity to contamination.

Larger Random Packing

Potential advantages:

  • lower pressure drop;
  • greater gas capacity;
  • more open flow passages.

Potential limitations:

  • lower specific surface area;
  • potentially greater required packed height.

The selection should balance:

mass transfer + capacity + pressure drop + contamination tolerance

12. Which Random Packing Types May Be Considered?

Depending on hydraulic and mechanical requirements, engineers may evaluate:

  • metal Pall Ring;
  • high-performance metal random packing;
  • Cascade Mini Ring;
  • other open ring-type packing.

A high-performance open geometry can be attractive where the objective is to combine:

  • low pressure drop;
  • good gas capacity;
  • adequate mass transfer.

The exact packing type should be selected from actual process data.

13. Packing Material Selection

For many pressurized TEG contactors, metal packing is the more practical starting point because of:

  • mechanical strength;
  • dimensional stability;
  • temperature capability.

Possible materials include:

  • carbon steel in suitable services;
  • SS304;
  • SS316;
  • SS316L.

Final material selection should consider:

  • gas composition;
  • H₂S;
  • CO₂;
  • chlorides;
  • water content;
  • operating temperature;
  • corrosion allowance;
  • existing vessel metallurgy.

Plastic packing should not automatically be selected simply because it has good corrosion resistance.

Mechanical and process requirements must also be considered.

14. Do Not Use HETP Alone for TEG Absorber Selection

This is an important engineering distinction.

HETP is commonly associated with distillation packing performance.

For gas absorption such as TEG dehydration, engineers may instead evaluate performance using approaches based on:

  • mass-transfer coefficients;
  • transfer units;
  • packed height;
  • required absorption duty.

Therefore, choosing a TEG packing only because it has a quoted low HETP can be misleading.

The actual dehydration duty must be evaluated.

This is an important difference between:

distillation packing selection

and

TEG absorption packing selection.

15. Mist and Glycol Carryover

Gas leaving the top of the contactor may entrain glycol droplets.

Excessive glycol carryover causes:

  • glycol loss;
  • downstream contamination;
  • operating cost increase.

A top separator or mist elimination system may therefore be required.

Engineers should evaluate:

  • gas velocity;
  • droplet loading;
  • disengagement space;
  • mist eliminator type.

Packing and mist elimination should be considered as parts of the same contactor system.

16. Random Packing Retrofit Checklist

When replacing existing packing or converting an existing contactor, check:

  • tower internal diameter;
  • manway dimensions;
  • existing packing type;
  • existing bed depth;
  • support grid;
  • hold-down device;
  • liquid distributor;
  • redistributor;
  • top mist eliminator;
  • available disengagement space;
  • allowable pressure drop.

Mechanical fit must be confirmed before fabrication.

For large columns, packing may also need to be delivered in installation-friendly quantities or packages compatible with manway access.

17. Common Mistakes in TEG Packing Selection

Mistake 1: Assuming Random Packing Is Always Better Than Trays

It is not.

The correct choice depends on the specific contactor.

Mistake 2: Selecting Packing Only by Surface Area

Higher surface area may also increase:

  • pressure drop;
  • liquid hold-up;
  • contamination sensitivity.

Mistake 3: Ignoring Lean TEG Distribution

Poor distribution can destroy the expected benefit of high-performance packing.

Mistake 4: Ignoring Glycol Condition

Foaming or contaminated glycol can create operational problems regardless of packing quality.

Mistake 5: Ignoring Existing Internals During Retrofit

Changing packing without checking:

  • support;
  • distributor;
  • hold-down;
  • mist elimination

may create a poorly integrated retrofit.

18. Data Required Before Selecting Random Packing for a TEG Contactor

Gas Conditions

  • gas composition;
  • gas flow rate;
  • operating pressure;
  • operating temperature;
  • inlet water content;
  • required outlet water content.

TEG Conditions

  • lean TEG concentration;
  • glycol circulation rate;
  • lean glycol temperature;
  • expected rich glycol condition.

Tower Data

  • internal diameter;
  • available packed height;
  • existing packing;
  • existing internals;
  • manway size.

Hydraulic Requirements

  • allowable pressure drop;
  • required turndown;
  • maximum gas rate;
  • operating range.

Operating History

For an existing contactor:

  • current outlet water content;
  • pressure-drop problems;
  • foaming history;
  • glycol carryover;
  • flooding symptoms;
  • maintenance frequency.

19. TEG Random Packing Selection Workflow

Step 1 — Define the dehydration target

Confirm:

  • inlet water content;
  • required outlet water content.

Step 2 — Confirm lean TEG condition

Review:

  • concentration;
  • circulation rate;
  • temperature.

Step 3 — Calculate gas and liquid hydraulic loading

Evaluate:

  • gas velocity;
  • liquid load;
  • flooding margin;
  • pressure drop.

Step 4 — Compare contacting technologies

Evaluate:

Trays vs Random Packing vs Structured Packing

Do not assume one technology is universally superior.

Step 5 — Select packing geometry and size

Balance:

  • mass transfer;
  • pressure drop;
  • capacity;
  • contamination tolerance.

Step 6 — Verify liquid distribution

Confirm that lean TEG can be distributed effectively across the bed.

Step 7 — Review tower internals and mist elimination

Confirm the complete contactor system rather than packing alone.

Frequently Asked Questions

Can random packing be used in a TEG gas dehydration contactor?

Yes. Random packing can be suitable in some TEG contactors, particularly where low pressure drop, retrofit flexibility and simple packed-bed construction are important. Final selection should be based on process and hydraulic evaluation.

Is random packing better than structured packing for TEG dehydration?

Not necessarily.

Structured packing may offer advantages in efficiency and pressure drop, while random packing may offer advantages in retrofit simplicity, robustness and cost.

The correct choice depends on the specific contactor.

What packing is suitable for a TEG absorber?

Possible options include:

  • metal Pall Ring;
  • high-performance metal random packing;
  • structured packing;
  • trays.

Selection depends on gas loading, glycol rate, dehydration target and tower geometry.

What causes poor performance in a packed TEG contactor?

Common causes include:

  • poor glycol distribution;
  • contaminated glycol;
  • foaming;
  • excessive gas velocity;
  • flooding;
  • hydrocarbon condensation;
  • insufficient packed height.

Is HETP enough to select packing for a TEG absorber?

No.

TEG dehydration is an absorption process. Packing selection should consider mass-transfer and hydraulic performance for the actual gas-glycol system rather than relying only on HETP.

What information should be included in a TEG packing RFQ?

Provide:

  • gas composition;
  • gas flow;
  • pressure;
  • temperature;
  • inlet/outlet water specification;
  • lean TEG concentration;
  • glycol circulation rate;
  • tower diameter;
  • packed height;
  • existing internals.

Engineering Takeaway

Random packing can be an effective option for TEG gas dehydration contactors, but the decision should be made only after comparing it with structured packing and trays.

The key selection logic is:

Dehydration duty → gas and glycol conditions → hydraulic loading → contacting technology → packing geometry → distributor → tower internals

For TEG systems, packing performance is strongly affected by:

  • glycol distribution;
  • contamination;
  • flooding margin;
  • pressure drop;
  • entrainment.

The correct engineering question is therefore not:

“Which random packing is best?”

It is:

“Is random packing the right contacting technology for this TEG contactor, and if so, which geometry and size best fit the actual operating conditions?”

Need help evaluating whether random packing is suitable for a TEG gas dehydration contactor?

Prepare:

gas composition · gas flow · pressure · temperature · inlet/outlet water content · lean TEG concentration · glycol circulation rate · tower diameter · packed height

DAIER Tower Packing Engineering Assistant can support preliminary hydraulic and packing screening before detailed process design review.

Internal Links

S069 → S064 Natural Gas Processing TowersS069 → S065 Gas Sweetening TowersS069 → S011 Random Packing Material SelectionS069 → S012 Random Packing Size SelectionS069 → S013 Random Packing Pressure Drop GuideS069 → Tower Packing Engineering Assistant

When Should Trays Be Replaced with Random Packing in an Existing Column?

How Do Engineers Choose the Right Tower Packing Solution for a Complete Project?