01 / TOWER INTERNALS · PACKED
Packed Column Internals
The components that distribute, support and protect the packing bed inside a packed distillation or absorption column — distributors, redistributors, supports, hold-downs and demisters, matched to your packing and duty.
What’s inside a packed column
In a packed column, gas and liquid contact each other over the wetted surface of a packing bed (random or structured). The internals around that bed decide how uniformly the fluids move through it — and therefore the separation efficiency, pressure drop and turndown of the whole column. PCX supplies the full set of packed-tower internals (อุปกรณ์ภายในหอ packing) — sourced from qualified international manufacturing partners and matched to your packing, column diameter and process duty.
- Liquid distributor — spreads liquid onto the top of the bed
- Liquid redistributor — corrects wall-flow between beds
- Packing support device — carries the bed while keeping gas flow open
- Packing hold-down device — stops the bed lifting under gas flow
- Demister — removes entrained droplets from the outlet gas
LIQUID DISTRIBUTOR
Liquid Distributor
Installed above the packing bed, the liquid distributor spreads incoming liquid evenly across the column cross-section before it enters the packing — distribution quality here has a direct bearing on mass-transfer performance. Uneven spread lowers the effective liquid-to-gas ratio in parts of the bed and can reduce separation efficiency well below what the packing itself is capable of.
- Trough-type distributors
- Trough-tray gas–liquid distributors — liquid and gas distribution in one unit
- Wider operating flexibility and better resistance to fouling
Applications: the entry point of liquid into a packed bed, new columns, revamps and internals replacement
Documentation
Catalogs and technical documentation are available upon request. Please contact our team for product information, specifications, and documentation.
Contact Us
LIQUID REDISTRIBUTOR
Liquid Redistributor
As liquid travels down through a packing bed, more of it gradually migrates toward the column wall — a pattern known as the wall-flow effect. Left uncorrected, this concentrates liquid at the wall and starves the centre of the bed, reducing contact efficiency in the packing below. A liquid redistributor is installed between packing beds to collect this wall-flow liquid and spread it evenly across the column again before it enters the next bed.
- Corrects the wall-flow effect between beds
- Restores even liquid spread over the bed below
- Also used to blend in side feeds or draws
Applications: between packing beds in multi-bed columns, side-feed and side-draw points
Documentation
Catalogs and technical documentation are available upon request. Please contact our team for product information, specifications, and documentation.
Contact UsPACKING SUPPORT DEVICE
Packing Support Device
Positioned beneath the packing bed, the support device carries the full weight of the packing plus the liquid it holds, while still allowing rising gas to pass through with minimal resistance. A poorly designed support restricts gas flow at exactly the point where flooding is most likely to start, so a high open area and low pressure drop are as important as mechanical strength.
- Grid-type supports
- Gas-injection (domed or corrugated) designs — raise open area further
- High open area and low pressure drop with full mechanical strength
Applications: carrying random or structured packing beds while keeping gas flow open
Documentation
Catalogs and technical documentation are available upon request. Please contact our team for product information, specifications, and documentation.
Contact Us
PACKING HOLD-DOWN DEVICE
Packing Hold-Down Device
Fitted at the top of the packing bed, the hold-down device stops individual packing pieces or the top layer of structured packing from lifting or shifting when gas velocity rises, which would otherwise loosen the bed and damage the packing over time. Ceramic packing, being brittle, is generally protected with a hold-down (pressure) plate that rests directly on the bed; metal and plastic packing, being less prone to breakage, is more commonly restrained with a lighter bed-limiter grid.
- Hold-down (pressure) plate — rests on the bed, protects brittle ceramic packing
- Bed-limiter grid — lighter, fixed to the shell for metal and plastic packing
Applications: the top of a packing bed, protecting the packing under high gas velocity
Documentation
Catalogs and technical documentation are available upon request. Please contact our team for product information, specifications, and documentation.
Contact UsDEMISTER
Demister
Installed at the gas outlet — typically at the top of the column — the demister removes fine liquid droplets carried along in the rising gas stream before it leaves the vessel. Left uncaptured, these droplets represent lost product, added load on downstream equipment, and a source of environmental emissions. Knitted wire-mesh pads are the most widely used type, offering a large droplet-capture surface at low pressure drop; vane-type (chevron) demisters are used where higher gas velocities or higher liquid loads make a mesh pad prone to flooding or clogging.
- Knitted wire-mesh pads — large capture surface, low pressure drop
- Vane-type (chevron) demisters — for higher gas velocity or liquid load
- Process mist eliminators for columns and separator vessels
Applications: gas outlets at the top of columns, separator vessels, and gas-scrubbing systems
Documentation
Catalogs and technical documentation are available upon request. Please contact our team for product information, specifications, and documentation.
Contact Us
Frequently Asked Questions
What does a liquid distributor do in a packed column?
A liquid distributor sits above the packing bed and spreads incoming liquid evenly across the whole column cross-section before it enters the packing. Distribution quality has a direct effect on mass-transfer performance — uneven spread starves parts of the bed and can pull separation efficiency well below what the packing is capable of. Common types are trough-type distributors and trough-tray gas–liquid distributors, the latter distributing liquid and gas in one unit for better fouling resistance.
What is the difference between a liquid distributor and a redistributor?
A distributor spreads liquid onto the top of a packing bed. A redistributor is installed between two beds to correct the wall-flow effect — as liquid travels down a bed it drifts toward the column wall, starving the centre. The redistributor collects that wall-flow liquid and spreads it evenly again before it enters the next bed, and is also used to blend in side feeds or draws.
What is the difference between a packing support and a hold-down device?
A packing support sits beneath the bed and carries the full weight of the packing plus the liquid it holds, while keeping a high open area so rising gas passes with minimal pressure drop. A hold-down device sits on top of the bed and stops the packing lifting or shifting when gas velocity rises. Brittle ceramic packing is protected with a heavier hold-down (pressure) plate resting on the bed; metal and plastic packing is usually restrained with a lighter bed-limiter grid fixed to the shell.
What type of demister should I use — mesh pad or vane?
A demister (mist eliminator) removes entrained liquid droplets from the outlet gas at the top of the column. Knitted wire-mesh pads are the most widely used, giving a large droplet-capture surface at low pressure drop. Vane-type (chevron) demisters are used where higher gas velocities or higher liquid loads would make a mesh pad flood or clog. Note these are process demister pads for vessels and columns — not automotive or mirror demisters.
How are packed column internals specified and quoted?
Packing supports, hold-down devices and distributor / redistributor designs are matched to the packing type, column diameter and process duty at quotation stage — there is no fixed size table. PCX sources them from qualified international manufacturing partners and supplies to your drawing or specification. Send the column diameter, packing type, materials and operating conditions and we will return a quotation.
Ready to specify or order?
Send us your requirements — we'll source and supply to your spec.
Send an Inquiry