Full Cone Spray Nozzle: Flow Characteristics and Industrial Uses

Full cone spray nozzles produce a solid cone of liquid that fills the entire spray area with uniform distribution — the most important characteristic for packed bed scrubbers where every section of the packing must receive equal liquid flow to prevent dry zones and gas channeling. Unlike hollow cone nozzles that concentrate liquid at the outer annulus or spiral nozzles that use a vortex flow path, full cone nozzles achieve uniform distribution through internal vane structures or deflection surfaces that direct the liquid evenly across the full cross-section of the cone. This uniform distribution makes full cone nozzles the standard choice for packed bed scrubber distributors, quench systems, tank washing, and any application where liquid coverage uniformity matters more than fine atomization. This guide covers the three internal design types of full cone nozzles — axial-flow (swirl insert), tangential-flow, and deflection-type — with explanations of how each design achieves uniform distribution; flow characteristics including the uniform distribution index (UDI), flow-pressure relationship, droplet size, and spray angle data; a comparison of full cone vs hollow cone vs spiral nozzles across the decision-critical parameters for scrubber service; and application-specific guidance for packed bed liquid distribution, gas cooling, and vessel cleaning. For the EPA-referenced scrubber design methodology see the EPA wet scrubber design manual.

What Is a Full Cone Spray Nozzle?

A full cone spray nozzle is a single-fluid hydraulic nozzle that produces a solid cone of liquid with uniform distribution across the entire circular impact area. Unlike hollow cone nozzles that intentionally leave a void in the center, full cone nozzles fill the cone completely — the liquid flux at the center of the pattern is equal to the flux at the outer edge. This uniform distribution is achieved through one of three internal design approaches, each with distinct characteristics for scrubber service.

Axial-Flow Full Cone Nozzles (Swirl Insert)

Axial-flow full cone nozzles use an internal swirl insert — a precisely machined component with angled vanes that impart a controlled rotational motion to the liquid as it passes through the nozzle body. The rotating liquid exits the discharge orifice as a conical sheet that breaks into droplets, with the vane geometry designed to direct a portion of the liquid toward the center to fill the cone. The swirl insert is removable in most designs, allowing cleaning or replacement without discarding the entire nozzle body. Axial-flow nozzles produce the best distribution uniformity of all full cone types — UDI typically above 85% — and are the standard for packed bed scrubber distributors. The trade-off: the swirl insert adds internal obstructions that reduce free passage to 3-6 mm, limiting their use to liquids with suspended solids below 200 ppm.

Tangential-Flow Full Cone Nozzles

Tangential-flow full cone nozzles introduce the liquid through one or more tangential ports near the discharge end of the nozzle body, creating a swirling motion without an internal vane insert. The tangential ports have larger flow areas than vane-type inserts, giving tangential-flow nozzles a larger free passage (5-8 mm) and better clogging resistance at the cost of slightly less uniform distribution (UDI of 75-85%). Tangential-flow nozzles are preferred for services where the liquid contains moderate solids loading (200-500 ppm) or where the swirl insert of an axial-flow nozzle would clog. They are common in gas cooling and quenching applications where distribution uniformity is important but not as critical as in packed bed service.

Deflection-Type Full Cone Nozzles

Deflection-type full cone nozzles (also called impingement or impact plate nozzles) produce a solid cone by directing the liquid jet against a specially shaped deflector surface at the nozzle discharge. The deflector spreads the liquid into a conical sheet that fills the coverage area. Deflection-type nozzles have the largest free passage of all full cone designs — up to 10 mm in some configurations — but produce the coarsest droplet size and the lowest UDI (65-75%). They are used primarily for tank washing, vessel cleaning, and fire protection where high flow rates and clogging resistance matter more than distribution uniformity. In scrubber service, deflection-type nozzles are occasionally used for quench cooling where coarse droplets are advantageous for penetration through hot gas.

Flow Characteristics

The defining performance parameter of a full cone spray nozzle is distribution uniformity — how evenly the liquid is spread across the coverage area. This is measured by the uniform distribution index (UDI), where 100% means every point receives exactly the same liquid flux and 0% means all liquid is concentrated at a single point. For scrubber applications, the UDI requirement depends on the service: packed bed scrubbers need UDI above 80% to prevent dry zones in the packing; gas cooling and tank washing can tolerate UDI as low as 60%.

Uniform Distribution Index

The UDI of a full cone nozzle is determined by the internal design quality and the operating pressure. Axial-flow nozzles with precision-machined swirl inserts consistently achieve UDI of 85-95% at their design pressure. At pressures below 50% of design, the distribution degrades because the rotational velocity of the liquid is too low to fill the cone uniformly. At pressures above 150% of design, the distribution also degrades as the high rotational velocity forces too much liquid to the outer edge, creating a distribution that approaches hollow cone characteristics. For this reason, full cone nozzles should be operated within ±25% of their rated design pressure for optimal UDI. Tangential-flow nozzles achieve UDI of 75-85% and are less sensitive to pressure variation. Deflection-type nozzles achieve UDI of 65-75% and are the least sensitive to pressure of all types.

Flow Rate vs Pressure

Full cone nozzles follow the same fundamental relationship as all hydraulic nozzles: Q = k√P. The flow coefficient k for a full cone nozzle is typically 30-50% lower than for a spiral nozzle of the same connection size because the internal vane structure creates additional flow restriction. For a 1-inch axial-flow full cone nozzle with k = 30: at 2 bar, Q = 30 × √2 = 42 L/min; at 3 bar, Q = 30 × √3 = 52 L/min; at 4 bar, Q = 30 × √4 = 60 L/min. The recommended operating pressure range for full cone nozzles in scrubber service is 1-4 bar. Below 1 bar, the spray pattern may not fully develop and the cone angle narrows by 15-30%. Above 4 bar, the internal vane and swirl insert experience increased erosion from any particles in the liquid, and the marginal benefit of further atomization diminishes.

Droplet Size and Spray Angle

Full cone nozzles produce the coarsest droplets of the three main scrubber nozzle types at the same pressure — SMD of 500-2,000 microns at 2 bar, compared to 100-800 microns for hollow cone and 300-1,500 microns for spiral nozzles. The coarse droplet size is a direct consequence of the internal vane design, which creates less shear than the open discharge of a hollow cone nozzle. This coarseness is beneficial for packed bed scrubbers because large droplets wet the packing surface without generating excessive mist that overloads the demister. It is a disadvantage for spray tower absorption where fine atomization is needed. Standard spray angles for full cone nozzles are 30-120 degrees, with 60-90 degree angles used for packed bed distributors and 90-120 degree angles used for gas cooling and quench systems. The coverage diameter follows the standard relationship D = 2 × H × tan(θ/2).

Full Cone vs Hollow Cone vs Spiral

The choice between full cone, hollow cone, and spiral nozzles for scrubber service depends on three parameters: distribution uniformity requirement, clogging risk from suspended solids, and target droplet size. The table below provides a direct comparison.

Select full cone nozzles when liquid distribution uniformity is the primary requirement — packed bed scrubbers, quench systems requiring even wall wetting, and any service where dry zones in the coverage area cause performance degradation. Select hollow cone nozzles when fine atomization for gas absorption is the priority and the liquid is clean. Select spiral nozzles when the liquid contains suspended solids above 500 ppm or maximum reliability against clogging is required. For a complete selection methodology see the spray nozzle selection guide for wet scrubbers.

Full Cone Nozzle Materials

Material selection for full cone nozzles follows the same chemical compatibility logic as other scrubber nozzles, with one additional consideration: the internal swirl insert or vane structure in axial-flow designs adds crevices and tight clearances that can trap corrosion products or promote localized corrosion. For this reason, axial-flow full cone nozzles in corrosive service should use the next higher grade of material compared to what would be specified for a simple open-orifice nozzle.

SS316L is the standard material for full cone nozzles in chemical scrubber service at temperatures below 400°C and chlorides below 2,000 ppm. For scrubbers handling chlorides above 2,000 ppm or operating above 80°C where PP cannot be used, upgrade the swirl insert to Hastelloy C276 even if the nozzle body remains SS316L — the insert experiences higher localized velocities and is more susceptible to crevice corrosion. For low-temperature acid scrubbers below 80°C, PP or PVDF full cone nozzles provide adequate service life at 30-70% of the cost of SS316L. For gas cooling and quenching in incinerator exhaust where temperatures reach 400-800°C, use full cone nozzles with silicon carbide ceramic swirl inserts and SS316L or Hastelloy bodies. The ceramic insert resists the thermal shock of intermittent quench operation while the metal body provides mechanical support. For deflection-type full cone nozzles in tank washing and vessel cleaning services, SS304 or SS316L with hardened stainless steel deflector plates extend service life by 2-3x compared to standard deflectors in abrasive services.

Applications in Scrubbers

Packed Bed Liquid Distribution

Packed bed scrubbers rely on full cone nozzles to distribute the scrubbing liquid evenly over the packing surface. A typical packed bed distributor uses 6-12 axial-flow full cone nozzles with 60-90 degree spray angles mounted on a ring header 300-500 mm above the packing. The nozzles are arranged in a triangular pitch pattern with 30-50% overlap to ensure every point on the packing surface receives liquid. The distance between the nozzle discharge and the packing surface — the freeboard height — must be at least 300 mm to allow the spray cone to fully develop before reaching the packing. For a 2.0 m diameter packed bed scrubber operating at L/G = 4 L/m³ with a total recirculation flow of 800 L/min, a typical arrangement is 8 full cone nozzles each delivering 100 L/min at 2-3 bar, spaced at 0.6 m centers in a ring-and-center triangular pattern. The distribution uniformity at the packing surface should be verified during commissioning using a collection grid — 16 equal-area compartments arranged across the bed cross-section — with the measured liquid flux in each compartment within ±15% of the average.

Gas Cooling and Quenching

In quench scrubbers where hot gas enters at 400-800°C and must be cooled to saturation temperature (60-80°C) within a few meters of contact distance, full cone nozzles provide the coarse droplet spray needed for deep penetration through the hot gas stream. Tangential-flow full cone nozzles with 90-120 degree spray angles at 2-4 bar are standard for quench service. The coarse droplets (1,000-2,000 microns SMD) resist evaporation longer than fine atomized spray, reaching 2-4 m into the vessel before complete vaporization. For a quench scrubber handling 10,000 m³/hr of incinerator exhaust at 600°C, a typical arrangement is 4-6 tangential-flow full cone nozzles in a ring pattern, each delivering 200-400 L/min at 3 bar. The nozzle material must be SS316L or Hastelloy with ceramic swirl inserts to resist the thermal cycling of intermittent quench operation.

Tank Washing and Vessel Cleaning

Deflection-type full cone nozzles are used for washing scrubber vessel walls, cleaning sump tanks, and flushing ductwork. The wide spray angle (120-150 degrees) and large free passage (up to 10 mm) allow these nozzles to handle dirty wash water without clogging while delivering high-impact droplets that dislodge scale and deposits. Install deflection-type full cone nozzles at 2-6 bar through tank wall mountings or fixed headers, angled to sweep the full vessel surface. For FGD scrubber sump tank cleaning, specify SS316L or Hastelloy deflection-type nozzles with a 140 degree spray angle to cover the full tank diameter from a single side-entry mounting.

Full Cone Nozzle Sizing

Sizing full cone nozzles for a packed bed scrubber follows the general nozzle sizing procedure with emphasis on verifying uniform coverage across the packing surface. The key difference from spray tower nozzle sizing is that the freeboard height — the distance from nozzle discharge to packing surface — is fixed by the vessel geometry and is typically 300-500 mm, which directly determines the coverage diameter per nozzle.

Given: A 2.5 m diameter packed bed scrubber with 400 mm freeboard height. Total recirculation flow: 1,200 L/min. Target liquid distribution: UDI above 85%.

Step 1: Select axial-flow full cone nozzles with 90-degree spray angle for the best UDI. At 400 mm height, coverage diameter D = 2 × 0.4 × tan(45°) = 0.8 m per nozzle.

Step 2: With 50% overlap requirement, effective spacing = 0.8 × 0.65 = 0.52 m. For a 2.5 m diameter, a ring of 6 nozzles at 0.52 m spacing plus 1 center nozzle = 7 nozzles total.

Step 3: Flow per nozzle = 1,200 / 7 = 171 L/min. Select a nozzle with k = 99 at 3 bar: Q = 99 × √3 = 171 L/min. Available from standard full cone nozzle ranges with 90-degree angle and 1-inch connection.

Step 4: Verify coverage uniformity. At 0.4 m height, each of the 7 nozzles covers a 0.8 m diameter circle. Total theoretical coverage area = 7 × π × 0.4² = 3.5 m². Tower area = 4.9 m². The 40% overlap between adjacent cones ensures all points on the packing surface receive liquid from at least 2 nozzles, providing UDI above 85%.

Maintenance

Full cone nozzles require more frequent maintenance than spiral nozzles because the internal swirl insert or vane structure creates surfaces where solids can accumulate. The most common failure mode is partial clogging of the vane passages in axial-flow nozzles, which reduces the flow rate and degrades the spray pattern long before complete blockage occurs.

Inspection: Inspect full cone nozzles every 3 months in clean service, monthly in fouling service. Remove the swirl insert where possible and inspect the vane passages for deposits, corrosion, and erosion. Measure the flow rate at a reference pressure and compare to baseline. A decrease of 10-15% indicates partial vane clogging. An increase of 10-15% indicates vane erosion — the vanes have worn and the internal geometry has changed, permanently altering the spray pattern.

Cleaning: For axial-flow nozzles with removable swirl inserts, disassemble the nozzle and soak the insert in dilute acid (2-5% HCl for mineral scale) or solvent (for organic deposits). Clean the vane passages with a soft brush — never with wire brushes or metal picks that would damage the precision vane geometry. For tangential-flow and deflection-type nozzles without removable internals, clean by back-flushing or soaking followed by high-pressure water jetting. After cleaning, reassemble and verify the spray pattern visually — any distortion, streaking, or asymmetry indicates internal damage requiring nozzle replacement.

Replacement: Replace axial-flow full cone nozzles when the UDI is visibly degraded (spray pattern shows streaks or voids) or when the flow rate deviation exceeds 15% from baseline. Replace the swirl insert annually in corrosive service even if no visible damage is present — the insert is the most stressed component and its gradual degradation is often invisible until the spray pattern suddenly fails. For tangential-flow and deflection-type full cone nozzles, replacement is required only when the flow deviation exceeds 20% or visible damage is present.

FAQ

What is the difference between full cone and hollow cone nozzles?

Full cone nozzles fill the entire spray area with uniform liquid distribution, while hollow cone nozzles concentrate liquid at the outer annulus with minimal liquid in the center. Full cone nozzles are used where uniform coverage is critical (packed bed distribution). Hollow cone nozzles are used where fine atomization is needed (spray tower absorption).

What is axial-flow vs tangential-flow in full cone nozzles?

Axial-flow nozzles use an internal swirl insert with vanes to create the spray pattern, providing the best distribution uniformity (UDI 85-95%) but with smaller free passage (3-6 mm). Tangential-flow nozzles introduce liquid through side ports, providing larger free passage (5-8 mm) and better clogging resistance but lower UDI (75-85%).

Can full cone nozzles handle slurry?

Standard full cone nozzles with 3-8 mm free passage can handle liquids with suspended solids up to 200-500 ppm. For higher solids loading, use tangential-flow full cone nozzles with 5-8 mm free passage or switch to spiral nozzles with 5-15 mm free passage. For FGD limestone slurry above 500 ppm solids, spiral nozzles are the only reliable choice.

What spray angle should I use for packed bed distributor nozzles?

60-90 degree spray angles are standard for packed bed distributors. Narrower angles (60 degrees) provide better penetration through deep packing beds. Wider angles (90 degrees) provide more coverage per nozzle and are used when the freeboard height is limited. The angle should be selected so that the coverage diameter at the packing surface is 1.3-1.5x the nozzle spacing.

How do I verify uniform liquid distribution from full cone nozzles?

Install a collection grid of 16 equal-area compartments arranged across the bed cross-section during commissioning. Collect liquid from each compartment simultaneously and measure the volume over a fixed time period. The distribution is acceptable if each compartment’s flux is within ±15% of the average. If any compartment deviates by more than 20%, adjust nozzle positioning or replace the affected nozzle.

How often should I clean the swirl insert in a full cone nozzle?

Inspect and clean the swirl insert every 3 months in clean service, every 1-2 months in fouling service. Replace the swirl insert annually in corrosive service even if no visible damage is present — the insert experiences the highest localized velocity and its gradual erosion is often invisible until the spray pattern degrades.

Can full cone nozzles be used for spray tower gas absorption?

Full cone nozzles can be used for spray tower absorption but are less efficient than hollow cone nozzles because their coarser droplets (500-2,000 microns SMD at 2 bar) provide less surface area per unit volume. If full cone nozzles must be used because the liquid contains solids that would clog hollow cone nozzles, increase the operating pressure to 3-5 bar to reduce droplet size and improve mass transfer.

Conclusion

Full cone spray nozzles are the standard choice for scrubber applications requiring uniform liquid distribution — primarily packed bed liquid distributors, but also quench cooling and vessel cleaning. The three internal design types — axial-flow, tangential-flow, and deflection-type — offer different balances of distribution uniformity, clogging resistance, and droplet size, allowing selection of the optimum design for each specific duty. The axial-flow design with precision-machined swirl insert provides the best distribution uniformity for packed bed scrubbers where liquid coverage determines mass transfer efficiency. For services with higher solids loading, tangential-flow full cone nozzles provide an acceptable compromise between uniformity and reliability, while deflection-type nozzles serve specialized cleaning and quenching duties where flow capacity matters most.

XICHENG EP LTD supplies full cone nozzles in axial-flow, tangential-flow, and deflection-type designs, with spray angles from 30 to 150 degrees, in materials from PP and SS316L through Hastelloy C276 with silicon carbide swirl inserts, in flow rates from 5 to 500 L/min per nozzle. Contact our applications engineering team with your scrubber dimensions, operating conditions, and coverage requirements for a full cone nozzle system design recommendation and quote. For the complete nozzle selection methodology see the spray nozzle selection guide for wet scrubbers.