Pressure Jet vs Normal Oil Boiler?

[Ivan]

Can anyone tell me how a pressure jet boiler works, and how a normal boiler works? I remember being shown how an oil boiler works a long long time ago - it had a thing that spun round squirting oil tangentally - I guess that's very old.

Modern boilers usually have a burner assembly which I presume injects oil into a fast moving, turbulent airstream......but how does this vary from a pressure jet boiler?

I'm looking for a second hand oil boiler to convert to Babbington burner to experiment with waste liquid fuels, but need to make sure I get something suitable....pressure jet boilers seem to be a lot cheaper.

[Stuart]

A Pressure jet is a very simple design.
Pump drives liquid through tiny jet, fine mist of fuel produced, and usually a electric ignition source fires it up.
electric fan blows air into combustion chamber.
Was fixing one on a steam cleaner Saturday, they get easily blocked by debris in the fuel. Hence adding a large car diesel filter instead of the in line jobbie. There are usually mesh filters just before the nozzle.
supposed to change the nozzle depending on the fuel, there also fussy about how much air you blasting in, though you can set it up well with the smoke colour.

[Ivan]

Thanks Stuart. Do you know if the flame from a pressure jet is similar to a standard oil burner (not sure what that's called) and does it burn in a similar type of combustion chamber (aka waterjacket heat exchanger) - or is this different from a pressure jet boiler?

[Stuart]

Ivan, thinking back to 'secret life of machines' and the old (whirlyflow?) boiler on my friends farm we were always fixing, they had a water jacket and were made out of thick steel.
The steam cleaner had a coil heat exchanger, with the thin combustion chamber upturned, injector and 2 spark plugs in top so the heat has to go down and back up the other side of the coils. would have thought this would make it more efficient. certainly a lot lighter. The flame is the same colour in both, though the pressure jet is more intense. Don't know about modern oil boilers, as they went down the LPG path. If your trying different viscosity fuels a variable speed fuel pump or pre heat loop maybe handy. this thing gets parafin, heating oil and a fair bit of oil contaminated loco fuel 
quick fiddle with the air balance gets it burning clean(ish) again.

[sleepybubble]

Thanks Stuart. Do you know if the flame from a pressure jet is similar to a standard oil burner (not sure what that's called) and does it burn in a similar type of combustion chamber (aka waterjacket heat exchanger) - or is this different from a pressure jet boiler?

Ivan I think you might be confusing yourself somehow... pressure jet is a normal oil burner nowadays. Previous oil burners relied on evapouration from a pan or burning from a wick.
Stuart described well enough how a presure jet system is built. There are a few interlock bits and bobs such as fuel shut off solenoid and the good old magic eye.
There are a wide variety of nozzles available to the pressure jet service engineer, most often a like for like replacment is taken for granted at service. However it must be noted that the nozzle is selected to suit the burner and combustion chamber, based upon flame pattern. Which in your case will also be dependent upon fuel selection.

If your just going to stick a babbington burner into the cumbustion chamber of a standard oil boiler than great fire on.

[billt]

There was another type, common about 25 years or more ago, called wall flame boilers. They operated as Ivan described, with a central spinning distributor inside a cylindrical water jacket and the oil burnt with a flame going up the walls of the jacket. They were much quieter than pressure jet burners, and hence were more suitable for indoor use.

[Alan]

Quote “with a central spinning distributor inside a cylindrical water jacket and the oil burnt with a flame going up the walls of the jacket “

These would run at a combustion efficiency of about 50%

A pressure jet burner gets you in combustion efficiency’s of 86%

On bigger burners with steam atomisation your getting in the 90%

The days of dripping oil in a pot and setting fire to it are hopefully long gone.

Regards

Alan