Indigenous Spray Pyrolysis Techniques Basics and working of spray pyrolysis technique

 
 
 
Spray Head/ Nozzle 
The single spray nozzle consists of capillary tubes (stainless steel) fitted at 
perpendicular to the other tube as shown in Fig. 2.2. When compressed air is passed rapidly 
Fig. 2.3: Mask used for the preparation of film. 

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through the upper tube P in direction tangential to the mouth of the lower tube A whose other 
end is kept immersed in the spray liquid. Due to this partial vacuum the liquid rises up 
through the tube A and the compressed air drives it away in the form of the fine spray 
particles (aerosol). The thinner the spray nozzle the finer would be the spray particles. A very 
fine needle shaped capillary tube was used for the spray nozzle. Fine spray through the nozzle 
depends on the bore of the nozzle and it may vary from nozzle to nozzle. The diameters of 
the outer bore and inner bore were 2.12 mm and 0.71 mm respectively. 
Design of a Reactor 
The design of a typical reactor is shown in Fig. 2.2. It is a vertical batch type reactor 
composed of a galvanized iron enclosure ‘E’, heater ‘H’, and heat suspector ‘G’. For the 
rapid expulsion of the byproduct gasses there are opening at the side and at the top of the 
reactor. It helps focusing the incoming aerosol towards the substrate ‘S’ and also provides a 
chimney action to the exhaust gas upwards. 
The Fume Chamber 
It is a large box type chamber with a slanting top and is provided with a chimney. There 
is an exhaust fan with regulated power supply fitted at the mouth of the chimney. The 
slanting top and the sidewalls are made of glass. There are air tight doors in the front side. 
The chamber has purging facilities. The whole spray system is kept inside the fume chamber 
at the time of film deposition because of (a) Safety grounds and (b) To check air current 
disturbances at the deposition site. These two points just stated are very important for the 
pyrosol process when deposition is carried out in open air atmosphere.