Every spray drying machine comes with a distinct specifications sheet, and whether you are buying or selling these machines, you cannot afford to ignore these sheets. A spray dryer’s inherent specifications generally determine the dryer’s operational costs and the quality of the generated products. Below, we take you through the spray dryer specifications sheet, in an effort to help you read, interpret, and match specific specs to certain applications.
What is a Spray Dryer?
A spray dryer is simply a drying machine that relies on drying chambers to evaporate the solvent in liquid solutions, pumpable pastes, or emulsions, consequently generating granular or powdered products.
Modern spray drying machines are tailored to handle both heat-sensitive and heat-insensitive feeds, making them indispensable in most industries. However, procuring a dryer with the right specifications is essential, as it ensures that the resulting products meet the predetermined production specifications, for instance, the particle size and moisture content.
Common Spray Dryer Terminologies Explained
Specification sheets, as important as they are, can be difficult to understand owing to the technical terminologies used. That is why in this spray dryer selection guide, we are beginning by taking you through the technical jargon commonly featured in the machine specification sheets.
- Feed Capacity: Generally expressed in kilograms per hour (Kg/h), the feed capacity lets you know the highest amount of raw material you can turn into granules or powder per hour.
- Evaporation Rate: This paints a picture of the amount of solvent evaporated during the drying process under optimal operating conditions. Simply put, it puts into figures the speed at which your custom spray dryer generates powdered products.
- Inlet Air Temperature: Often expressed in °C, the inlet air temperature measures the amount of heated air injected into the drying chamber to help with the drying process.
- Outlet Air Temperature: Just like the inlet air temperature, the outlet air temperature is also expressed in °C, and it measures the amount of heated air exiting the drying chamber.
- Airflow Rate: The airflow rate shows the volume of heated air injected and passed through the drying chamber over a set period or per unit of time.
- Heating Capacity: This measures the maximum heat energy industrial spray drying equipment can convey to the inlet heated air in order to facilitate efficient drying. It is generally expressed in kWr. or BTU/hr.
- Atomization: This is the process that precedes the actual drying process, and it involves the liquid raw material being dissected into smaller droplets or portions. Atomization attempts to expand the feed’s surface area, ultimately enhancing your spray dryer’s drying efficiency.
Key Spray Dryer Specifications
When buying or choosing a spray dryer, a lot of emphasis is placed on the dryer’s capabilities. And to understand the drying machine’s capabilities, you have to look at its spec sheet. Having looked at the key terminologies used in these spec sheets, now we take you through the main spray dryer technical specifications.
- Feed Capacity: Small spray dryers designed for household use or laboratory use have feed capacities as low as 1.5 liters per hour. Larger dryers, particularly industrial spray drying equipment, in contrast, can boast feed capacities as high as hundreds of tons per hour.
- Water Evaporation Rate: Different spray dryers have varying inlet and outlet air temperatures, and this essentially dictates their evaporation rate. However, typical laboratory, pilot-scale, and industrial spray dryers have an evaporation rate at kg water/hour.
- Drying Chamber Dimensions: The dimensions of drying chambers found in spray dryers vary significantly with the diameter informed by the scale of operation. Industrial spray dryers typically utilize gigantic drying chambers, some with diameters as high as 10 meters. Laboratory spray drying machines, on the other hand, come equipped with comparatively smaller drying chambers. Their diameters can be as small as 1000 mm.
- Inlet Air Temperature: Spray dryers feature an adjustable interface that allows you to set the ideal inlet air temperature. The supported temperature range in most dryers ranges from 105°C to 500°C, allowing you to dry both heat-sensitive and ceramic raw materials.
- Outlet Air Temperature: The vast majority of spray drying machines support outlet air temperatures ranging between 60°C and 100°C, protecting the integrity of heat-sensitive products.
- Airflow Rate: Most conventional laboratory-scale spray drying machines boast an airflow rate of up to 75 m³/hr, while their industrial counterparts boast a drying capacity ranging from 10,000 m³/hr to approximately 50,000 m³/hr.
- Atomizer Type: Every spray dryer features an atomizer tasked with generating smaller droplets of the contained solvent. The spec sheet categorically indicates the type of atomizer installed in the spray dryer, and this can be either;
- Rotary atomizer
- Ultrasonic atomizer
- Pressure-nozzle atomizer
- Two-fluid nozzle atomizer
- Feed Pump Type: Spray dryers feature either progressing cavity pumps, which are designed for pumping viscous materials, high-pressure piston pumps designed for dryers with pressure nozzles, or diaphragm pumps, which favor abrasive slurries.
- Construction Material: The spray dryer’s spec sheet clearly outlines the specific material used to construct each component. Conventional spray drying machines are made from stainless steel, while custom spray dryers are often tailored using pharmaceutical-grade or food-grade materials.
- Power Requirements: Whereas laboratory-scale spray drying machines thrive on a 1-phase 220V or 380V power supply, industrial spray dryers demand at least a 3-phase Industrial Voltage.
- Noise Level: Modern spray drying machines, particularly lab-scale dryers, are conveniently quiet, allowing their deployment in noise-sensitive environments. They generally operate at noise levels well below 60 decibels. Industrial dryers, in contrast, are slightly louder, with noise levels reaching up to 85 decibels.
Spray Dryer Performance Specifications
Reviewing the spec sheet for any spray-drying equipment is undeniably important, as it helps buyers anticipate the dryer’s performance before making a purchase. This technical piece of paper outlines optimal performance parameters and what must be done to achieve them.
· Drying Efficiency
Whereas typical spray dryer technical specifications may not categorically express the drying efficiency of your spray dryer, they provide key variables and a formula to help you work out the dryer’s efficiency. For instance, the spec sheet may provide the optimal evaporation rate as well as the residence time, which you can use to calculate the dryer’s drying efficiency.
· Particle Size Distribution
Virtually every spray drying equipment spec sheet outlines the particle size distribution of the dried product. In most specification sheets, this is described in a statistical range such as D90 to D10. This performance specification helps prospective buyers anticipate the quality of the powdered products and their functional performance.
· Final Moisture Content
Spray dryer specification sheets clearly state the achievable final moisture content, allowing manufacturers to control the quality and shelf-life of their powdered products. For most industrial spray drying machines, the final moisture content is left at 5%, while in most lab-scale spray dryers, it can be as low as 2%.
· Powder Recovery Rate
Comparatively smaller spray drying equipment tends to lose more powder since they lack a multi-stage powder recovery system. Their recovery rate ranges between 50% and 80%, making them comparatively inefficient. Larger spray dryers, particularly industrial and pilot spray drying machines, boast elaborate recovery systems, which boost their powder recovery rate to approximately 80% to 90%.
Utility & Installation Specifications
Installing spray drying machines and getting them up and running is no easy feat. Luckily, each dryer comes with an elaborate spec sheet detailing key installation parameters. The table below summarizes these specifications.
| Spray Dryer Specifications | Requirements |
| Electric power | 3 kW to over 30 kW for small dryers and up to 100 kW for industrial dryers. |
| Steam or gas requirements | Superheated steam, ambient air, or nitrogen. |
| Compressed air | Four to seven bars. |
| Ventilation | Ventilation duct air velocity of at least 1200 feet per minute. |
| Installation height | Significant vertical clearance for industrial spray dryers and relatively smaller clearance for laboratory dryers. |
| Factory Space | 2–5 m² for lab spray dryers and up to over 300 m² for industrial spray dryers. |
FAQs
How can you determine the right spray dryer capacity?
To arrive at the perfect spray dryer capacity, you need to think beyond the physical volume. You must factor in the ideal evaporation rate as well as the heat sensitivity of your liquid feed.
What is the ideal inlet and outlet air temperature of a spray dryer?
To determine the ideal inlet and outlet air temperature for a spray dryer, you need to weigh your material’s heat sensitivity against the required moisture level. The ideal temperatures for distinct materials and products are outlined in the dryer’s spec sheet.
How do you determine the best type of atomizer for spray drying?
The atomizer simply dictates how efficient a spray dryer is when it comes to producing powdered or granular products. Whereas there are pneumatic, rotary, and pressure nozzle atomizers, you need to factor in your scale of operation and the raw material to determine which atomizer suits you best.
What is the difference between an industrial spray dryer and a laboratory spray dryer?
Industrial spray drying equipment is built to dry large volumes of liquid feed over short periods of time and relies on gigantic drying chambers or towers. Laboratory spray dryers, in contrast, are scaled-down versions of industrial dryers designed to generate powdered products in smaller volumes.
Looking for Custom Dryer Solutions?
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