How to Choose a Spray Dryer That Suits You

Choosing the appropriatespray dryerinvolves a thorough assessment of various elements. This manual simplifies the vital considerations to assist you in making a well-informed choice that fits your material characteristics, production demands, and quality standards.

The characteristics of your material play a crucial role in the selection process. Begin by examining these significant properties:

Solid Content and Concentration

The concentration of your feed material has a direct effect on evaporation load, output, and energy consumption. An elevated amount of solids in the material reduces the amount of water that needs to be evaporated, leading to improved energy efficiency. Therefore, it is important to record the usual range of solid content in your material (between 5% and 60%) to calculate the necessary evaporation capacity.

Viscosity Considerations

The flow of materials is influenced by their viscosity, impacting both the choice of pumping method and atomizer. Standard pumps and nozzles are suitable for low-viscosity materials (<100 mPa·s), as they facilitate easy flow. However, high-viscosity materials (>500 mPa·s) necessitate specialized equipment such as screw pumps or piston pumps, and typically necessitate the use of rotary atomizers or special two-fluid nozzles.

Heat Sensitivity

Identify the highest temperature that your material can withstand. For materials that are sensitive to heat, such as proteins, enzymes, and biological extracts, it is important to operate at lower temperatures (ranging from 40-150°C). Special attention must be given to materials like honey, coffee, and pharmaceuticals, which may require additional measures, such as using maltodextrin as a carrier to prevent them from sticking or degrading.

Finished Product Specifications: What are the requirements for powder fineness, bulk density, and particle morphology? These factors dictate the selection of the atomizer type (centrifugal or air jet).

Centrifugal atomizers use a high-speed rotating disc that creates uniform droplets through centrifugal force. When feed rate and disc speed are high, the liquid forms unstable ligaments that break into consistent droplets.

Two-fluid nozzles use compressed air (0.3-0.7 MPa) to atomize the feed. The high-velocity air stream creates friction with the slower-moving liquid, producing extremely fine particles.

Utilize these fundamental measurements to determine your required capacity:

• Water Evaporation Rate (kg H₂O/h): The core capacity indicator. Determine the initial moisture content and target final moisture content to calculate the required evaporation volume.

• Powder Output (kg/h): How many kilograms of wet material must be processed per hour, or how many kilograms of dry powder must be produced? This is central to determining equipment scale. Related directly to the evaporation rate and the solid content.

• Scale Considerations: Laboratory (1-5 L/h), pilot (10-25 L/h), or production (>50 L/h)

The quality of the product can be notably affected by adjusting the temperature settings.

The temperature range at the inlet:

• The required temperature range for standard materials is between 150 and 300°C.
• Materials that are sensitive to heat can withstand temperatures between 40 and 150 degrees Celsius.
• Achieving the desired precision of ±2°C through optimal control.

The temperature of the outlet:

Usually kept at 80-90°C to achieve sufficient drying without excessive heat. The outlet temperature must be higher than the material's glass transition temperature (Tg) to avoid sticking.

Heat Source Selection:

• Electric heating: Clean, precise control, highest operating cost. Best for laboratories
• Steam heating: Moderate cost, stable control, requires a steam supply
• Gas/oil heating: Lowest operating cost, high efficiency, requires indirect heating for food/pharma

Operating Mode:

Is continuous production or batch production required? This determines whether the equipment is designed for continuous or batch operation.

Heat-Sensitive Materials: Materials like honey and coffee require:

• Operation at temperatures below 120°C (<120°C inlet).
• Incorporation of carriers, such as 10-30% maltodextrin.
• Systems that utilize a closed-loop design are effective in preventing oxidation.

Organic Solvent Recovery For materials containing organic solvents:

• Explosion-proof equipment certification
• Nitrogen circulation mechanisms
• Efficiency in recuperating solvents is above 90%.
• Closed-loop operation

Ceramic and Metal Powders. Special considerations include:

• The centrifugal atomizer must have a minimum capacity of 5L.
• Improved durability
• The regulation of particle shape

The construction materials must align with your specific needs.

Essential system components include:

• A drying chamber that has a suitable ratio of diameter to height.
• Particle collection cyclone separators
• Bag filters are designed specifically for the recovery of fine particles.
• Containers equipped with valves for releasing the product

Think about your control needs:

• Manual operation: This includes basic temperature and feed control.
• Semi-automatic: utilizing PLC control and data logging.
• Completely automated: Featuring a touch screen HMI, remote monitoring capabilities, and the ability to store recipes.

Adhere to this methodical process:

• Outline Criteria: Record physical characteristics, desired result, powder standards, and financial limitations.
• Initial Screening: This involves analyzing and determining the suitable atomizer type, system configuration, and estimated scale.
• Material Testing: Conducting small-batch trials using pilot equipment to confirm the viability of the process.
• Evaluate Proposals: Comparing their technical specifications rather than solely focusing on price.
• Total Cost Analysis: Analyze factors such as energy usage, upkeep requirements, availability of spare parts, and the possibility of downtime.

Ensure that all information is accurate before making your final decision.

✓ Material viscosity matches atomizer capabilities
✓ Temperature range suits material heat sensitivity
✓ Capacity meets current and future production needs
✓ Construction materials compatible with your product
✓ Automation level aligns with operational requirements
✓ Supplier provides pilot testing capabilities
✓ Spare parts and technical support readily available
✓ Total lifecycle cost justified by production value

When choosing a spray dryer, it is important to first comprehend the properties of your material and then find the corresponding technology. Prioritize attaining the desired particle size, moisture level, and production capability, all while safeguarding heat-sensitive parts.

Keep in mind that opting for the lowest initial price does not always guarantee the best long-term value. A well-designed spray dryer, built with high-quality materials and backed by dependable support, will ensure consistent performance and minimize any interruptions to operations. Be sure to request pilot-scale testing to confirm your choice before moving forward with purchasing full-scale equipment.

For complex materials or unique applications, consult the experienced experts at TOPTION. We will help you overcome technical challenges and ensure successful spray drying.

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