I believe that most people know the mini spray dryer machine, because it has a wide range of applications, whether it is used in the pharmaceutical industry, food industry, chemical industry, university laboratories, new energy, etc., but you know what its structure is like of it? Next, I will briefly introduce to you the functions and functions of each component of the mini lab scale spray dryer
Structure of mini spray dryer machine
• Drying Chamber
• Cyclone Separator
• Peristaltic Pump
Among these types of installations, dry gas heating installations are the most important. In the laboratory mini spray dryer machine, electric heating is more commonly used.
However, due to the high power consumption, it is not commonly used in industry. In order to save costs, the alternate mode of steam heating and electric heating is often used in industrial production.
The air inlet temperature is the temperature at which the drying medium contacts the material for the first time. Air heat energy is the main energy source for drying, and the temperature will affect the evaporation amount of solvent per unit time. The temperature before the drying gas enters the drying chamber is the inlet air temperature.
Under normal air inlet temperature, the solvent in the feed liquid is evaporated rapidly within a few milliseconds to tens of milliseconds. Since the solvent is evaporated in an instant, a large amount of heat is taken away. The heat source of the solvent when evaporating is not only the heat provided by the instrument, but also absorbs heat from the raw material. This is why even if the inlet air temperature is much higher than the decomposition temperature of the raw material Reasons for staying active. It is for this reason that the inlet air temperature can often rise to more than twice the boiling point of the solution.
The atomizer is the core component of the mini spray dryer machine, and the parameters of the atomizer are one of the important scopes of investigation. The solution passes through the injection pump, first through the nebulizer. The performance of the atomizer determines the effect of the atomization.
In the centrifugal atomizer, the solution is mainly dispersed and split into small droplets by centrifugal force, and then dried to form granular products. For the common combination of co-current drying and centrifugal atomizer, the atomizer is at the top of the drying chamber, where the heat source starts.
When the solution enters the atomizer, it starts to absorb heat and is ready to evaporate the solvent. When the atomizer atomizes the solution into droplets in different states, the droplets absorb enough heat to start evaporating to form particles. The time for absorbing heat is very short, and in this extremely short time, the amount of heat that can be absorbed is certain.
The size of the atomized droplets determines the strength of the atomization effect
• Small droplets need to evaporate less solvent, need to absorb less heat, and easily reach the evaporation peak to form particles;
• Large droplets need to evaporate a large amount of solvent and absorb more heat. When the evaporation peak cannot be reached in a short time, the droplets will leave the atomizer as a solution or semi-dry, sticking to the wall or forming agglomerates.
3. Drying chamber
The commonly used shape of the drying chamber is a straight cylindrical inverted conical bottom. The shape of the cavity needs to be selected according to the type of dry atomization separation and the performance of the mini spray dryer machine product. The drying chamber can be divided into high chamber and small chamber.
Drying Chamber Classification
• High cavity: about 5:1 diameter
• Small cavity: about 2:1 diameter
In general, small chambers are more commonly used, mainly because almost all types of nebulizers can be used. Under the right atomization conditions, the droplet has enough time to dry before reaching the cavity wall. If it is not completely dry under the given conditions, it may cause sticking to the wall and so on.
In order to prolong the contact time of drying gas-droplets, pipes are usually extended between the drying chamber and the separation device to increase the efficiency of the mini spray dryer machine. The addition of pipes will not increase the drying rate and reduce product loss.
Inside the chamber, dispersed droplets move in an air stream. The droplets are therefore limited by the local air temperature and humidity (open type). The droplets lose solvent under different conditions to form specific types of dry particles.
4. Cyclone separator
The cyclone separator is to separate the solid from the gas through the centrifugal force of rapid rotation to separate the gas from the solid, the gas goes through the bag dust removal device, and the solid falls into the collector.
The cyclones inside some laboratory dryers are specially coated to reduce powder accumulation. In order to reduce product loss, multi-stage cyclone separators are often used in industrial production to reduce small particle products being carried away by the airflow.
The collector is located below the cyclone separator and is used to collect the solid product separated by the cyclone separator, which is the final product.
6. Belt dust collector
The bag filter is located behind the cyclone separator and is used to remove solid products that have not been separated in time in the cyclone separator.
Due to the continuous operation of industrial production, it is necessary to ensure the unimpeded circulation of the airflow. A spray system is often added before the bag filter, and the solids are absorbed and dropped into the waste tank below by spraying liquid. If there is no spray system, in order to prevent a large amount of solids from accumulating on the filter bags of the bag filter,