Micro Mist Spray Dryer
Single micron range has been achieved since it wan not possible in conventional spray dryer.
Comparison of spray dryer at fine powder range of few microns
| Micro mist spray dryer | Spray dryer | |
| Atomization device | Four-fluid nozzle | Two-fluid nozzle Rotary atomizer Fast rotation is required and do not have much sales records |
| Atomizing a small amount | One nozzle | One nozzle |
| Atomizing in high-volume fine powder production | One nozzle | Multiple nozzles |
| Scale-up | Easy to scale up using parameter tested by laboratory unit | There are some problems such as gas-flow turbulence and droplet collision since using multiple nozzle, so consideration should be made in many aspects |
| Drying efficiency | Drying efficiency is high since it is 180°hollow cone and there is no unevenness in hot air contact |
Drying efficiency is not good since it is full cone that has forwardness and takes a lot of time to contact the hot air |
| System size | Drying chamber can be smaller since the drying efficiency is high compared to the general spray drying | Drying chamber will be higher |
| Continuous operation | Long time operation without nozzle clogging | High chance to become nozzle clogging |
| Compressed air volume | If the liquid processing rate is the same, the air flow rate will be less than the total of multiple nozzle | Large |
| Operating performance | Operation is easy by central controlling on the touch panel |
Becomes complex since there are many nozzles and liquid sending pumps |
| Maintenance | Easy and simple since the number of nozzles and liquid sending pumps is not big |
Maintaining will be a hard task since there are many nozzles and liquid sending pumps |
| Initial cost | System can be smaller, and also can compete the existing price |
If the production becomes high-capacity, it might increase in cost |
| Running cost | Electrical energy consumption of compressor will be 20% to 50% less |
Electrical energy of compressor is huge |
Comparison of few microns fine powder manufacturing method
| Micro mist spray dryer | Other method | |
| Few microns fine powder manufacturing process | Powder can be attained directly from the liquid | In the case of slurry, condensation will be necessary if the solution is a type that attains powder by disintegrating/pulverizing the liquid after dehydrating at the filter press and drying by shelf drying. |
| System configuration | 1 unit | Several units |
| Research development | Powder can be attained easily | Takes time |
| Operating system | Long time continuous operation | Batch operation |
| Closed loop | Possible | Difficult |
| Classifying operation | Not necessary | Sometimes necessary |
| Productivity | Operating time is short for production amount and high productivity can be attained if the liquid concentration rises. Have great collection efficiency. | In case of long operating time. Low collection rate because of the adherence and flying apart at each device. |
| Operating performance | Simple | Operating knowledge is necessary for each device and washing and assembling is complex and difficult |
| Maintainability | Simple Nozzle is the only spare parts item that is necessary |
Maintenance knowledge and spare parts item is necessary for each device |
| Sanitary property | High | Low |
| Initial cost | Comparing the total cost, it is about the same, or even cheaper |
It can be either expensive or cheap depending on the device selection & combination? and system integration complexity |
| Running cost | Manpower is not needed much, electrical energy of compressor is big |
Manpower can be needed much depending on the material flow between devices |
| Contamination | Never | High chance of contamination |
| Fluid property | Possible on both solution and slurry Slurry initial particles better to be below 1 to 2 µm |
Difficult in solution, and increasing concentration will be necessary |
| Product property | Spherical form Porous, low density |
Formation is instable High density |
| Quality control of the product | Easy to control since the factor is less | Quality control is necessary on each device and the factor will be a lot |
| Residual moisture of the product | Almost every powders can observe the standard |
Sometimes final drying might be necessary |
| Thermal denatured | Instant drying at low temperature below boiling point is possible |
Exposure time at drying heat temperature is long |
Particle size distribution
Particle size distribution of primary particle before spray drying
Particle size distribution after spray drying by micro mist spray dryer
SEM picture of fine powder
made by micro mist dryer
