Propane Flame Projector Controller

[4pyros]

This is a write-up I started for a new project.
I consider it a work in progress.
At this point I am looking for comments on the write-up.
Can you under stand it?
Am I getting my point across?


Propane Flame Projector Controller

Objective;

I would like to make a controller for a Propane Flame Projector to be used for entertainment.

Here is some links to an example of a commercially available Propane Flame Projector.

**broken link removed**

In order to use these safely you need a controller to monitor the flame and stop the flow of fuel if it is not igniting.

I have found many off the shelf controllers for continuous flame use like for furnaces or dryers but none for intermittent flame use. For continuous flame safety the controller will shut off the fuel if it does not see fire after a few seconds. These will not work for a flame that is only there for a short time. For intermittent flame safety the controller should shut off the fuel supply if it does not light after so many try’s.

As well as safety this controller would also provide a means of remote control so the flame can be triggered by different types of input and left on for varying amounts of time.

This Flame Projector will be used in a hunted hay ride as a startle scare. Triggered off sensors and automation controllers. Both of witch have adjustable on times.

It will also be used as part of low level fireworks shows with several spread out across hundreds of feet. These will need to be triggered by the firing system. The output of the firing system is vary short so it would need to trigger an adjustable timer. I would like multiple inputs of different durations like .5 sec, 1sec, 1.5 sec and so on.

 

[Reloadron]

Seems the lead pyro of the famous four pyros is coming out.

That was pretty cool. Like a flame version of all the Christmas Lighting done using a computer. As to flame detection I have worked with both the rod type and the UV detector types. My best guess would be open a valve and apply ignition to the burner. When ignition is applied look for a flame. This is where a UV detector might be a good bet. Maybe ignition off a flip flop and also a delay. If you have a flame then leave the valve open, if there is no flame turn the valve off. Looking at the video the delay will be short. A Google of "uv flame detector" will bring up some of what I mentioned. However, the suckers aren't cheap and you would need one for each channel. The delay scheme could be all worked into a small UC. Likely easier to program a few cheap PIC chips than use individual components.

Ron

 

[dr pepper]

Your going to get a load of dont do it its dangerous comments on this one.

The steam boiler where I work uses a photo resistor to detec tthe flame, but thats no good if theres ambient light, another machine uses an ionization probe which is tricky to get right.
I looked into flame detection a while back as a safety device, the best way I came up with but never pursued was an infra red diode to detect heat, I think a bpw41 was the device in mind.
Maybe you could look at something like this.

 

[KeepItSimpleStupid]

Lots of stuff exists here: https://www.google.com/url?sa=t&rct...=EAc4zkkN-4vPGhfx6TZ3LA&bvm=bv.58187178,d.cWc

Also look into flame proving with "Flame rectification".

 

[cowboybob]

From the video it would appear that these devices use a pilot light igniter. Which makes sense for something that must ignite an often very short burst of gas and very quickly.

As such, all you really need are pilot light sensors.

Simpler to deal with then trying to detect the actual "flame projection" within a time frame where flame iterations are too short and too closely spaced for most sensors to detect in time to be effective.

 

[jpanhalt]

I second dr pepper's suggestion for infrared. In 1982, I installed a couple of infrared heaters in a shop. They were similar to today's Detroit (**broken link removed**) units and used infrared for flame detection. They are still working well, so far as I know.

Flame electrical conductivity and detection of combustion products are other methods to consider.

John

 

[dr pepper]

How about a pilot tlight with an auto ignite and flame detection.
In software you could extinguish the pilot light if the burner hasnt operated for a period.

 

[Reloadron]

Put me in the IR group. Thinking about it a little more the UV I worked with were designed for a nice blue flame. Based on response I am also thinking a pilot light system, much like used on what are now older furnaces.

@ John, we had some of those radiant heaters you linked to around our loading docks. They work great! Serious warm heat during winters like this.

Ron

 

[KeepItSimpleStupid]

put me in the IR group.

Spark ignition doesn't necessarily work the first time. Your little controller, could possibly support both pilot and spark for ignition. A pilot wastes gas.
Maybe, you could incorporate something like. If not ignited for 1/2 hour - switch to spark ignition mode, otherwise use pilot mode.

 

[dr pepper]

Engine spark plugs are good for ignition if you go that route, I converted a burner to use spark plugs instead of its original spark gaps.

 

[4pyros]

Wow you guys are jumping way ahead of me.
I have not even finished with a detailed list of requirements.
But thanks for all your ideas and thoughts, I had a lot of stuff to look thru already.

One of the main things with this project is that these Flame Projectors will be used outside exclusively and exposed to the elements like wind, rain, and sometimes snow. This makes it a lot harder to come up with something that works reliably.

We have been using Flame Projectors under manual control (a spotter) for some time now with pilot lights that have proved vary unreliable, they keep going out and have to be relit.

I am thinking of using a hot surface igniter that would also be used for flame rectification sensing.

I will list my reasons for these choices soon.

Thanks again for all your input so far.

 

[dr pepper]

How about a diesel engine glowplug, they glow red and can withstand extreme combustion pressures, only drawback is they pull a few amps.

 

[4pyros]

How about a diesel engine glowplug, they glow red and can withstand extreme combustion pressures, only drawback is they pull a few amps.

Thanks but I would prefer to use something that runs straight off 110 volts AC.

 

[ClydeCrashKop]

Model airplane glow plugs are $7.00 and don't use much power.
https://www.hobbyexpress.com/super_duty_glow_plug_1037531_prd1.htm?pSearchQueryId=4645837

 

[alec_t]

I would prefer to use something that runs straight off 110 volts AC.

That doesn't seem safe if "these Flame Projectors will be used outside exclusively and exposed to the elements like wind, rain, and sometimes snow."
Perhaps use a standard mains-to-12V (or whatever) transformer to drive a glow-plug? The 'business end' of the electrics would then be mains-isolated.

 

[4pyros]

Model airplane glow plugs are $7.00 and don't use much power.
https://www.hobbyexpress.com/super_duty_glow_plug_1037531_prd1.htm?pSearchQueryId=4645837

I was thinking along the lines of RC car plugs.
I dont know if they get hot enough to light the propane, or if they would provide a large enough surface area to light the propane.
Here is what a commercial hot surface igniter looks like. It is big and heats up to 2000 deg fahrenheit.

 

[jpanhalt]

Model glow plugs glow yellow-red. They may ignite propane at normal pressure, but I am not sure. My other concern would be longevity. In a model, they can be relatively short lived (several hours). They are kept hot as a result of catalyzing oxidation of methanol. With so-called "gas-glow" fuel (a mixture of methanol, oil, and gasoline) they provide ignition after removal of the battery. Again, the methanol keeps them hot. They will not ignite pure gasoline-oil mixtures after removal of the battery. Moreover, pure hydrocarbon fuels burn hotter than methanol fuels.

Thus, it is hard to assess their longevity in a situation where they would be exposed to a continuous propane flame. My guess is that a hot-bar ignitor, as you illustrate, would last longer. However, if longevity is not an issue, then model glow plugs may be a cost-effective alternative.

John

 

[4pyros]

That doesn't seem safe if "these Flame Projectors will be used outside exclusively and exposed to the elements like wind, rain, and sometimes snow."
Perhaps use a standard mains-to-12V (or whatever) transformer to drive a glow-plug? The 'business end' of the electrics would then be mains-isolated.

Ya I am just realizing that now that you said it, but you need AC power to use flame rectification sensing.
Maybe it could be done with a lower AC voltage like 24 volts?

 

[jpanhalt]

Why do you need AC for flame conductivity testing?

John

 

[4pyros]

Model glow plugs glow yellow-red. They may ignite propane at normal pressure, but I am not sure. My other concern would be longevity. In a model, they can be relatively short lived (several hours). They are kept hot as a result of catalyzing oxidation of methanol. With so-called "gas-glow" fuel (a mixture of methanol, oil, and gasoline) they provide ignition after removal of the battery. Again, the methanol keeps them hot. They will not ignite pure gasoline-oil mixtures after removal of the battery. Moreover, pure hydrocarbon fuels burn hotter than methanol fuels.

Thus, it is hard to assess their longevity in a situation where they would be exposed to a continuous propane flame. My guess is that a hot-bar ignitor, as you illustrate, would last longer. However, if longevity is not an issue, then model glow plugs may be a cost-effective alternative.

John

Speaking of longevity, I am now reading that the ceramic (silicon carbide) hot surface igniters can be damaged by water, this is not good either.
The newer silicon nitride igniters are more robust and less affected by moisture but don't know if they can still be damaged by rain.