Marc, you mentioned burning waste lube-oils. These short US videos give an excellent description of the pressure jet burner adapted for that purpose, show a burner set up, running and what oils it will burn, [ These are adverts, so this is not a personal endorsement of the product.]

The parts are described in American English.
You will note that there is no gear-pump, the oil being delivered by air-powered venturi nozzles, so an air compressor is required. The nozzles look similar to Danfoss-Hago stainless-steel types which I've used. The machine is fed from a day-tank, scales to about 20-30 US gallons. The oil is heated to about 212F/100C for viscosity and ignition purposes - veg oil has to be a lot hotter. The air is heated too, with a cartridge-heater; this is an essential part of the machine.
This is a powerful burner, twin top-end Hagos could put out well in excess of a million BTU/hr = 290kW.

You can rate oil consumption at roughly :
1 liter waste lube or veg oil = 10kW hours
1 US gallon " ditto " = 129,000 BTU

http://www.youtube.com/watch?v=q4ZriEMN0FQ&feature=related

http://www.youtube.com/watch?v=4SX1lNvUjZg&feature=related

http://www.youtube.com/watch?v=BrTXJDcTzn4&feature=channel

Alan






Wood work but can't!