Features of Pilotech Two Fluid Nozzle Spray Dryer
- 01 Bar precision air pressure for exact PSD control
- SUS316L stainless steel nozzle with anti-clogging auto-needle
- Real-time PID control holding inlet temp within ±1°C
- Borosilicate glass components offer excellent corrosion resistance
- Low-noise compressor integrated with anti-vibration technology
Your Trusted Two Fluid Nozzle Spray Dryer Manufacturer
Whether in laboratory R&D or industrial mass production, two fluid nozzle spray dryers are very common drying equipment. They use the shear force of compressed air to uniformly atomize the feed liquid into fine droplets, which are then rapidly dried to form powder. You can adjust the parameters to achieve your desired standards for particle size, moisture content, and other factors.
Pilotech specializes in the research and development of laboratory equipment with 21 years of experience. We offer a wide range of two fluid spray dryers suitable for new product development and pilot-scale testing across various industries, including food, pharmaceuticals, and chemicals.
Require a tailored setup? Our process engineers design custom atomization loops, special nozzle materials, and footprint-specific configurations for your exact feed slurry.
Designed for laboratory and corporate R&D, offering precise control of temperature and atomization. Its compact design saves space, and experiments can be conducted using only a small amount of material, helping to reduce your costs.
Bridge between lab R&D and mass production. Higher processing throughput with multi-nozzle options and stable airflow. Excellent for scaling up ceramic slurries, polymer powders, and medium-batch food ingredients.
Uses continuous ambient air intake to dry aqueous samples. Cost-effective, straightforward operation with HEPA exhaust filtration. Perfect for non-toxic, water-based solutions, herbal extracts, and non-flammable standard food products.
Recycles inert nitrogen gas with integrated solvent recovery. Helps maintain safety and explosion-proof operation. Essential for handling organic solvents, flammable chemicals, toxic compounds, and highly oxygen-sensitive active molecules.
Two Fluid Nozzle Spray Dryer Specifications
| Parameter | Laboratory Model | Pilot-Scale Model |
| Spray Dryer Type | Two Fluid Nozzle Spray Dryer | Two Fluid Nozzle Spray Dryer |
| Application Scale | Laboratory / R&D | Pilot / Process Development |
| Water Evaporation Capacity | 1.5–3.0 L/h | Up to 5.0 L/h |
| Max. Feed Rate | 1,500–3,000 mL/h | Up to 5,000 mL/h |
| Minimum Sample Volume | 30–100 mL | 100 mL |
| Inlet Air Temperature | 40–250°C / 40–280°C | 60–260°C |
| Outlet Air Temperature | 40–120°C | 50–120°C |
| Temperature Control Accuracy | ±1°C | ±2°C |
| Drying Time / Residence Time | 1.0–1.5 s | 1.0–1.5 s |
| Drying Airflow | 1.5–2.0 m³/min | Approx. 3.0 m³/min |
| Atomizing Gas | Compressed Air / Nitrogen | Compressed Air / Nitrogen |
| Atomizing Gas Pressure | 0.2–2 bar | 0.5–2 bar |
| Atomizing Gas Consumption | Approx. 32 L/min | Application-dependent |
| Nozzle Type | Two Fluid Nozzle | Two Fluid Nozzle |
| Standard Nozzle Diameter | 1.0–1.5 mm | 2.0 mm |
| Optional Nozzle Diameter | 0.5 / 0.8 / 1.5 / 2.0 mm | 0.5 / 0.8 / 1.0 / 1.5 mm |
| Possible Particle Size | 1–80 µm | 3–100 µm |
| Spray Direction | Downward, Co-current | Downward, Co-current |
| Atomizer Material | SUS316 / SUS316L | SUS316 / SUS316L |
| Drying Chamber Material | Borosilicate Glass / SUS304 | SUS304 Stainless Steel |
| Cyclone Separator | Borosilicate Glass / SUS304 | SUS304 Stainless Steel |
| Feed Pump | Peristaltic Pump | Peristaltic Pump |
| Temperature Control | PLC / PID | PLC / PID |
| Control Interface | LCD Touchscreen | LCD Touchscreen |
| Automatic Nozzle Deblocking | Optional / Standard | Standard / Optional |
| Inert Gas Loop | Optional | Optional / Available |
| Suitable Feed | Solutions, Emulsions, Suspensions | Solutions, Emulsions, Suspensions |
| Typical Applications | Pharmaceuticals, Food, Biotechnology, Ceramics, Chemicals | Pharmaceuticals, Food, Nutraceuticals, Chemicals, Materials |
Working Principle of Two Fluid Nozzle Spray Drying
A two-fluid nozzle is a type of air atomizing nozzle. Depending on the number of channels, there are also three-fluid nozzles, four-fluid nozzles, and so on. Its core principle involves using a high-speed gas stream to shear and impact a low-speed liquid stream, thereby atomizing the liquid. The atomization process can be broken down into the following three steps.
Kinetic Energy Transfer
High-pressure gas (typically compressed air or nitrogen, with a pressure generally ranging from 0.2 to 0.6 MPa) is accelerated through the nozzle’s gas channel and ejected at high speed from the orifice.
Primary Atomization
At the same time, a feed pump delivers the feed liquid into the nozzle. When the high-velocity gas comes into contact with the low-velocity liquid, the resulting strong shear force stretches the liquid into a film or liquid thread.
Secondary Atomization and Drying
Under the turbulence of the gas flow, the liquid film instantly breaks into micrometer-sized droplets. Upon contact with hot air, the water in these droplets evaporates rapidly, thereby achieving drying.
Difference between Internal-Mixing and External-Mixing Two-Fluid Nozzle
| Comparison Dimension | Internal-Mixing Nozzle | External-Mixing Nozzle |
| Mixing Location | Air and liquid are mixed inside the nozzle chamber before being sprayed out. | Air and liquid mix in the ambient air outside the nozzle tip. |
| Air-Liquid Interaction | Gas and liquid pressures directly affect each other. Unstable liquid pressure may cause gas backflow into the feed tube. | Gas and liquid channels are completely independent, with almost no pressure interference. |
| Suitable Viscosity & Feed | Ideal for low-viscosity, particle-free, non-crystallizing clear solutions. | Ideal for high-viscosity slurries, suspensions with solids, and liquids easy to crystallize/solidify. |
| Anti-Clogging Performance | Lower resistance. Suspended solids tend to settle and cause blockages in the mixing chamber. | Exceptional. No internal narrow chamber at the outlet, reducing clogging issues. |
| Atomization Efficiency | Higher efficiency with full air-energy utilization, producing more uniform droplet sizes. | Slightly lower, requiring higher compressed air consumption and higher pressure. |
Applications of Two Fluid Nozzle Spray Dryers
Food Industry
In food processing, many ingredients contain high levels of sugar or fat and are extremely viscous. This atomization method of the two-fluid nozzle generates extremely strong shear forces, which can overcome the surface tension and cohesive forces of high-viscosity liquids.
Furthermore, the moment the fine droplets come into contact with the hot airflow, a hard shell rapidly forms on their surface, encapsulating the volatile flavor compounds and preserving the unique flavor of the food or seasoning.
Pharmaceuticals and Biotechnology
Many pharmaceutical ingredients are highly sensitive to temperature. Two-fluid nozzles can atomize the feed solution into ultra-fine micrometer-sized droplets, instantly increasing the specific surface area. As a result, moisture can evaporate instantly at lower outlet temperatures, helping to protect heat-sensitive substances from prolonged exposure to high temperatures.
At the same time, their concentrated, narrow-angle spray pattern significantly reduces material buildup on the walls of the drying tower, thereby improving the recovery rate of high-value samples. Two-fluid spray dryers are commonly used in the preparation of DPIs, protein microencapsulation, and ASDs of poorly soluble drugs.
Battery Materials and Ceramic Materials
Ceramic slurries and battery material suspensions typically have high viscosity, high solids content, and are abrasive. If you use conventional pressure nozzles, the nozzle orifices are prone to wear.
While external-mix two fluid nozzles have relatively large orifices in their liquid passages. Furthermore, they rely on pneumatic shear forces rather than forced extrusion for atomization. As a result, they can handle abrasive slurries containing particles without being prone to internal buildup or clogging.
Are the Two Fluid Nozzles and Pressure Nozzles the Same Thing?
A two fluid nozzle and a pressure nozzle are not the same.
Different Working Principle
A pressure nozzle relies on a high-pressure liquid pump (typically requiring 2–20 MPa) to force the feed liquid through a very small orifice. It uses the liquid’s own kinetic energy to achieve atomization. In contrast, a two fluid nozzle uses a high-speed gas stream to shear and impact a low-speed liquid stream.
Different Orifice Size and Clog Resistance
Pressure nozzles have extremely small orifices and are highly prone to clogging when used with feed fluids that have high solids content or high viscosity. Two fluid nozzles have relatively larger orifices in their fluid channels and offer better resistance to clogging than pressure nozzles.
Different Methods for Adjusting Particle Size
The droplet size produced by pressure nozzles is primarily determined by the pumping pressure and the nozzle orifice diameter. You should replace the nozzle insert to adjust droplet size. In contrast, two-fluid nozzles allow for flexible control of droplet size by independently adjusting the gas-to-liquid ratio (GLR).
Two Fluid Nozzle vs. Rotary Atomizer
The two fluid nozzle and the rotary atomizer are two mainstream atomization methods. But which one is actually better suited for your material? This section will explore this question from four perspectives.
Working Principle
Two-fluid nozzles atomize a liquid by using the shear stress generated by a high-pressure gas flow to impact the liquid.
Rotary atomizers use a motor to drive a high-speed rotating disc or wheel (typically 10,000–50,000 RPM). Under the influence of centrifugal force, the feed liquid is flung outward along the surface of the disc, forming droplets. You will find that this method is not limited by the physical size of orifices, making it ideal for processing high solids content materials.
Particle Size Adjustment
For a two fluid nozzle, if you want to reduce the droplet size, you need to keep the feed rate constant and increase the gas-to-liquid ratio (GLR). Conversely, lowering the gas pressure or increasing the feed rate will result in larger droplets.
For a rotary atomizer, you can increase the atomizer disc speed (RPM) to increase the centrifugal force. This causes the droplets to be stretched extremely thin, resulting in smaller droplet sizes. Reducing the rotational speed results in larger droplet sizes.
Product Features
| Product Feature Dimension | Two-Fluid Nozzle | Rotary Atomizer |
| Mean Particle Size | Fine / Small (typically 5 – 30µm). | Medium to Large (typically 20 – 100µm). |
| Particle Size Distribution | Broad, with a slight amount of sub-micron particles. | Narrow, featuring excellent powder particle uniformity. |
| Particle Morphology | Solid spheres or slightly raisin-like particles. | Hollow spheres or porous micro-balls. |
| Bulk Density | High bulk density. | Lower bulk density. |
| Cause Analysis | Strong shear from high-speed air generates micro-droplets with large specific surface areas. Water evaporates instantly, solidifying the particle before the internal matrix can expand, forming compact solid micro-particles. The fine powders fill interstitial voids, resulting in higher bulk density. | Centrifugal force flings out larger droplets, which rapidly form a hard surface shell under high temperatures. As internal moisture vaporizes, it expands and balloons the outer shell (puffing effect), creating hollow structures that result in lower bulk density. |
Suitable Materials
Two Fluid Nozzle
You can use two fluid nozzles to handle high-viscosity liquids. Because compressed air exerts extremely strong shear forces, the two fluid nozzle can overcome the surface tension and cohesive forces of high-viscosity liquids, atomizing them into fine droplets.
Additionally, due to the narrow spray angle, the tower can be designed with a smaller diameter, with minimal material buildup on the walls and a high recovery rate. Using this method to process small batches and high-value samples can help you save costs.
Rotary Atomizer
Centrifugal discs offer high throughput and require no compressed air, resulting in lower operating costs. Therefore, they are commonly used in large-scale, continuous industrial production, including infant formula and bulk chemical products.
Furthermore, rotary atomizers have no narrow passages and do not generate high pressure during the atomization process, making them good for handling highly abrasive suspensions like coarse-particle mineral slurries. If you need to process such materials, we recommend using centrifugal discs made of materials like silicon carbide to enhance wear resistance.
Two Fluid Nozzle Spray Dryer Maintenance
If you want your two fluid nozzle spray dryer to operate reliably, prevent nozzle clogging, and avoid cross-contamination between batches, you need to maintain it properly. This will not only prevent time wasted due to downtime but also save you costs.
Automated Feed-Line Flushing
After drying is complete, do not shut off the gas supply or the pump immediately. Switch the feed line to deionized water or a suitable solvent and flush for 10 to 15 minutes at the rated temperature. This will effectively remove residual material from the feed line.
Disassembly and Inspection
Once the drying tower and nozzle have cooled to room temperature, shut off the compressed air supply and remove the two fluid nozzle. In this step, you should check that the auto-deblocking needle moves smoothly. Check the outlet micropores of the fluid cap and air cap for any buildup of crystalline powder or physical scratches.
Ultrasonic Cleaning
Immerse the removed metal nozzle components in an ultrasonic cleaning tank filled with cleaning solution. Clean for 15–20 minutes to thoroughly remove deposits from inside the micro-holes. Avoid using a metal needle or stiff wire to poke the nozzle’s micro-holes. Doing so will damage the spray holes and affect atomization performance.
Seals Maintenance
The spray dryer’s seal integrity is also very important. Please remember to check the O-rings inside the nozzle. If you find that the O-rings have hardened, deformed, cracked, or swollen, they must be replaced immediately. Otherwise, gas and liquid phases may mix, affecting the atomization performance.
Air Source and Filter Maintenance
Inspect the oil-water separator and HEPA filter, and drain accumulated water regularly. This prevents moisture and trace amounts of oil from contaminating the nozzle and the sample.
Scaling Up of the Two Fluid Nozzle Spray Dryer
When scaling up a drying process from the lab-scale to the pilot scale or an industrial production line, a simple linear geometric scaling approach is not viable. The following scaling principles are provided for your reference.
Keep the GLR Unchanged
During atomization, if the feed liquid flow rate increases, the compressed air mass flow rate must increase proportionally. This helps maintain the same atomization kinetic energy and keeps particle size consistent.
Adapt Multi-head Nozzle Cluster
A single nozzle that is too large can result in uneven atomization in the central area. If you need to scale up to industrial-grade equipment, we recommend using a multi-head nozzle cluster. This method increases production capacity by adding more nozzles while reducing the impact on atomization performance.
The GLR is a core process parameter for controlling atomization quality. Increasing the GLR enhances the shearing and tearing effects on the droplets, breaking the feed liquid into finer droplets. It will significantly reduce the average particle size of the final powder. In contrast, decreasing the GLR weakens the atomization shear force, causing the droplets to grow larger and form coarse particles. By adjusting the gas-to-liquid ratio, you can flexibly optimize the particle size distribution (PSD) of the powder.
Under standard operating conditions, when a two fluid nozzle spray dryer processes conventional aqueous solutions, the residual moisture content of the dry powder can be controlled within the range of 1% to 3%. For heat-sensitive or difficult-to-dry materials, the moisture content can be further reduced to below 0.5% by optimizing the inlet and outlet temperatures, feed rate, and drying air flow rate. If the material is highly hygroscopic, the dryer can also be equipped with an extra drying system to meet your requirements.
Our spray dryers are equipped with a multi-stage filtration system. First, a high-speed cyclone separator separates the vast majority of dry powder particles from the gas stream. The remaining fine dust passes through a pre-filter and finally enters the HEPA. This system achieves a capture efficiency of up to 99.95% for particles 0.3 µm or larger. The filtered exhaust gas can be discharged directly into the cleanroom or routed out through dedicated ductwork, fully meeting the air quality requirements for GMP-grade cleanrooms.
Yes. For abrasive ceramic slurries or mineral suspensions, we offer fluid caps and air caps made of highly wear-resistant materials. In addition to standard 316L stainless steel, you can opt for nozzles with tungsten carbide, sapphire, or ruby liners. These materials can withstand prolonged, high-speed erosion from slurries with high solids content, thereby extending nozzle life and ensuring long-term stability in atomization angle and particle size distribution.
The main challenge in capturing fine powders lies in their tendency to disperse with the exhaust gas. We adopt a high-efficiency streamlined cyclone separator that enhances the capture rate by optimizing the internal flow field. For extremely fine powders, you can also opt for an electrostatic precipitator or a wet scrubbing bag filter system. This facilitates more efficient capture. Additionally, the inner walls of the chamber undergo electropolishing, which significantly reduces electrostatic adsorption of fine powders on the tower walls and reduces material loss due to buildup.
Yes. Our equipment can be configured with a rupture disc or an explosion-proof relief valve. In the event of abnormal overpressure inside the system, the rupture disc will rupture instantly at a preset pressure, safely releasing the pressure into a designated area. For systems using organic solvents, the equipment is typically equipped with a nitrogen-based closed-loop system and online oxygen concentration monitoring. This design helps reduce the risk of explosion and maintains the safety of the laboratory and people.