Nozzles for the Conditioning of Gases

Gas conditioning refers to the process of injecting a spray into gas to change its properties.  A common conditioning application would be the cooling of a gas by the addition of a coolant spray.

The important spray characteristics to be considered in conditioning applications are:-

Droplet size  The smaller the average droplet size then the larger the surface area of any given amount of fluid so the higher the heat flux or chemical reactivity.  Smaller average droplet size sprays will cool and react more quickly with the gas.  Misting impingement nozzles, such as the P and PJ series, produce the finest droplet size for any direct pressure nozzle.  For finer sprays still air atomising nozzles in the XA or Spiral Air range should be considered.

Reach  Care needs to be taken to ensure that the spray will reach all parts of the gas.  If the gas is moving quickly there can be a danger that very fine sprays will be swept away in the gas and not reach all parts, thus not conditioning the whole flow.  This can mean that a balance between high surface area fine sprays and coarser sprays with higher momentums needs to be found.  The spiral nozzles such as the TF range produced by Bete will often have such a mixture of fine and coarse droplets.

Gas cooling nozzles

Amount of spray If contamination further down the process line is a problem the amount of fluid sprayed will need be calculated so that it is all absorbed or evaporated before it reaches a certain point.  As the absorption / evaporation is highly dependant on spray properties like droplet size it is often the case that nozzles with a high degree of uniformity of spray pattern are required.  

Typical gas cooling nozzles

For small gas flows
PJ series Low profile misting nozzle P series misting nozzle 

For medium and large gas flows
Spiral Hollow Cone Nozzles Maxipass full cone nozzle Spiral air, 3 stage air atomising high flow rate nozzle

Very small droplets at high volumes  The smallest droplets from any nozzle are formed by air atomising nozzles.   These use pressurised air to break up the fluid.  Unfortunately, standard air atomising nozzles will often operate with fluid flow rates below what is required for some gas conditioning applications.  Whilst it may be desirable to have exceptionally fine sprays, the lack of throughput makes them unsuitable.  To solve this problem Bete have developed the Spiral Air three stage atomising nozzle. T his uses an encased spiral nozzle as the first stage of atomisation, followed by air atomisation from pressurised gas and finally the fluid is forced through a shaping orifice.  Essentially this nozzle gives the best of both worlds, in that it delivers a relatively high volume of very finely atomised spray.  This makes them ideal for many larger gas conditioning applications.

Spiral Air Atomising Nozzle

 For full details one the spiral air nozzles please click on the product boxes below.

Spiral air, 3 stage air atomising high flow rate nozzle 

 

Chemical Processing Key Spray Applications

Chemical Processing Key Spray Challenges: