Have customer with problems with propane vaporise rs.

Question

Claims that it is the propane I am selling him. Highly unlikely . Stain tests were done with supplier and were O.K. Sell a lot of propane to customers with propane powered forklifts. No other problems. Seems peculiar only with new toyota forklifts. Have not seen system like these before . Has something to do with the new emission standards and the way regulators are installed. Know that propane does contain oil and will leave residue over time. He describes a tar buildup in vaporise rs > I would assume that is oil. Claims that heat on vaporiser is causing this to occur

Answer 1

You have to supply the latent heat of vaporization to get the propane liquid to vaporize fast enough to power the vehicle. Propane burners will not need any extra heat as the heat transfer from the ambient suffices.

If the heater surface area is small it is possible that the surface temperature is high enough to make the high boiling oil fraction to leave a 'tarry' residue.

If the heat transfer area can be increased lowering the surface temperature, the problem may disappear.

Answer 2

I believe it's cold, not heat, in the vaporiser which is placed in the wrong position in the system... i.e a design fault.

I don't even know why heat is required on the propane vaporiser.

Propane boils at -42°C and only its vapour is used, NOT the liquid.

The vapour downstream of the regulator will be cold but, it only needs to be passed through a coil of sufficient length in order to be heated to atmospheric (or room) temperature by heat exchange with the ambient air.

If oil is the problem, then a heated exchanger should be used BEFORE the regulator in order to prevent the oil being cooled by the pressure drop across the regulator to a temperature which will cause the oil to form a residue.