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Drying of chemical compounds in solution or suspension

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An introduction to this case study

Drying is one of the main processes to produce high-purity powders from chemical compounds in solution or suspension. Common examples of these chemical compounds include calcium carbonate, aluminium hydroxide, calcium nitrate, magnesium sulphate, magnesium carbonate, copper sulphate, dicalcium phosphate, ammonium sulphate and phosphate, calcium carbonate and phosphate, and boric and adipic acids etc.

Spray drying is the most prominent technique used to produce fine powder from these chemical compound solutions or suspensions. In comparison to spray drying, pulse combustion drying produces generally superior powders in terms of particle morphology, size and powder flowability.

Technologies used in this case study:


Look at how we deal with the followingchallenge:

1. Drying of chemical compounds in solution or suspension

Drying of chemical compounds in solution or suspension


Powders in industrial processes are preferred to have spherical particles with a narrow size distribution and controllable morphology, both as raw materials in production and as final products. The size of the particles is very important during the application of the product.

The biggest challenge with spray drying is the fact that the powder particle morphology after the drying process is not predictable and for example can be undesirable hollow, toroidal-like spheres, or doughnuts.

In certain medical applications chemical compounds of powders with submicron particles are required and spray drying mostly cannot deliver the particle sizes as required.


With the advanced pulse combustion drying technology, Sinowatek can deliver superior powders from chemical compound solutions or suspensions. The powders are superior to spray dry powders due to the predictable smooth spherical solid particle formation, a very small (submicron) mean particle size, a narrow particle size distribution as well as high powder flowability.

The reason for these superior properties of the powders is the gas-dynamic atomization which takes place at the top of the drying chamber, whereby a low-pressure, slow-moving liquid solution or suspension is introduced through a single pipe into the pulsating, very high velocity gas stream.

Within a few milliseconds the pulsating exhaust stream produce ultra-fine (5-50μm) droplets while converting the surface moisture of the droplets into super-heated steam. This produces a very dry, fine powder with spherical shape and smooth surface particles. The energy absorbed by the evaporating water and the extremely short time the solids are exposed to the heat source, ensure the preservation of the characteristics of the solids.

Benefits for clients:

  • The energy consumption of PCD dryers is 1.15 kW/kg water evaporated (thermal and electric). Studies indicated that the energy consumption of spray drying processes can be as high as 2.3 kW/kg (8.4 GJ/metric ton). Pulse Combustion Dryers require less air than conventional dryers which results in smaller drying chambers and lower electrical consumption for smaller fans. Due to simple product injectors and smaller fans, running costs are 20-30% lower than spray driers.
  • Spray dryers utilize nozzles with small apertures, which with wear and tear, cause the dynamics of atomization to change and then the dryer begins to produce different particle sizes. The PCD has no equipment parts that can wear out because the atomization nozzle is essentially an open pipe.
  • The PCD uses no high-pressure pumps and high-RPM equipment; therefore, the maintenance is lower than its competitors.
  • The smaller air volumes, lower pressure required for mixture delivery, and smaller equipment footprint make the process more cost-effective than spray dryers.
  • At Sinowatek’s Pulse Combustion Dryer (PCD) Test Centre any chemical compound in solution or suspension can be dried to evaluate suitability and compatibility with the drying method. Energy consumption and product quality parameters are confirmed in this process allowing the design and construction of scaled-up production PCD units.
  • If low-volume toll processing is required we offer the use of our PC Dryer at the PCD test centre for the drying of high-value, high-purity products.

Let's talk  about your specific challenges in this field.