Propane Burner Pilot Size

[electrosteam]

A friend of mine is building a steam launch, about 22 feet, 3x4 inch single cylinder and a propane water tube boiler.
Forum members previously assisted with advice on machining the propeller.

All items are essentially complete, but not assembled in the boat.
I am assisting with preliminary boiler testing in the workshop and we are having problems with the draft and pilot operation.

The burner is one that is routinely provided for use under a wok in restaurants.
Circular ring with multiple screwed-in burners and a pilot burner with a temperature detector (mechanical ?).
The gas supply has a pressure regulator, isolating valve, safety valve and a feed regulator valve.

We cannot reliably light the pilot unless the natural ambient draft up the stack is blocked.
When the main burners ignite, with a disturbing 'whoomp' after a couple of seconds delay, the pilot is extinguished and the safety kicks the system off a few seconds later.
We can maintain operation using a hand-held gas burner directed at the temperature detector.

Our development scope is to review the pilot arrangement and size with the supplier.
Then, install a manually operated stack damper and develop our own larger pilot to get easy lighting, reliable operation and reduced whoomp.

Is our proposed scope correct, or should we be looking at something else ?
Thanks in advance for any comments or advice provided,
John.

[cava]

Consider relocating the pilot slightly lower down, and also modify the pilot hood (if required) so that it is more shielded and has more of a spread pattern or vis versa.

From memory the calorific rating of most pilot burners is typically limited to 0.5 mJ/h, so the injector spud should not need resizing.

Another possibility, is that the main burner injectors are oversized for the volume/area causing the oxygen to be used at burner ignition, and the resultant pilot being extinguished.

Hope this helps.

[Stustoys]

Another possibility, is that the main burner injectors are oversized for the volume/area causing the oxygen to be used at burner ignition, and the resultant pilot being extinguished.

Pretty much my only experience with this sort of thing was the opposite. A partially blocked main jet delayed the main burner lighting, 'whoomp', extinguishing main burner and pilot.

Stuart

[cava]

Pretty much my only experience with this sort of thing was the opposite. A partially blocked main jet delayed the main burner lighting, 'whoomp', extinguishing main burner and pilot.

Stuart
Always a possibility. However, if my reading is correct, there are multiple jets on this burner so it is unlikely to be a blocked injector. A photograph would help.

Is it like these?

https://www.auscrown.com.au//shop_image/product/f_jb10.jpg
https://www.auscrown.com.au//shop_image/product/62e0f9b68e9d25e74f02b0d3eef78acc.jpg

[electrosteam]

It is similar to:

https://www.auscrown.com.au//shop_image/product/f_jb10.jpg

but with more burners and a bracket to hold a small pilot assembly.
I searched the Gameco product catalog, but could not find the actual unit.

The builder and I are planning to visit Gameco to discuss the situation and investigate increasing the pilot size, or adding another pilot.

John.

[electrosteam]

Further to my previous, some rather poor quality photos show the current build status of the pilot.

The builder drilled out the pilot valve to 1 mm (perhaps about 0.3 mm before), and added a stainless steel cover to direct one of the three pilot flames onto the temperature detector.
The resultant pilot flame was very large, but the pilot adjustment on the safety valve enabled a suitable flame size to be set.

Photo #37 is the pilot without any damper on the stack.

Photo #38 shows the main burners operating with the pilots dancing around due to the air turbulence, but not going out.

Main burner ignition was good, no minor explosions.

Photo #42 is the safety valve and associated manual cocks.

322169322170322171

John.