Automated Electric Ignition Help

[knokep]

Once upon a time I dreamt up what I thought would be an excellent propane/electric herms hybrid system. 2 burners and a 110v water heater element. Plan was to maintain HLT temp with the water heater element, use one burner to quickly heat up HLT water initially, and use the 2nd burner for the boil kettle.

After a lengthy drawn out build, my system is now close to what I initially envisioned. Unfortunately my engineering calculations weren't perfect and my puny little 1500W element is not adequate with large volumes of water. I knew it wouldn't make large temperature changes, but it also doesn't maintain temperature as I expected.

I now am hoping I can draw on the knowledge of this group to help add an automated electronic ignition system to my HLT burner. I've done a lot of research and just keep getting more and more confused.

Does anyone have a parts list/picture of an installation that uses a 110v ignition system tied into a PID? I already have an ASCO solenoid installed for the gas to the HLT burner. I just need help in specing out the equipment necessary to light the burner automatically.

Thanks in advance.

 

[brian4508]

Sub'd. I'm just starting this research also

 

[amayhan]

I would look at a burner management system for direct ignition. Fenwal makes a nice inexpensive unit. You will need to come up with a spark/sense probe for it to work. Check out speedway for the different kinds available (google speedway pilots to find them)

You could also look at a real gas valve made by robertshaw that incorperates a standing pilot- or even an intermittent pilot.

As for control, I would use a hysteresis loop for control. A pid controller does not work very well with an on-off burner. You would need a modulating burner setup, which tend to be very expensive.

Be careful with gas burners- a setup without any safeties can mean a rather sudden lack of eyebrows or possibly much worse in a big hurry.

 

[The10mmKid]

A gas water heater burner and control seem appropriate. Look into the proper propane orifice change needed.
Lord knows there are plenty of scrapped leaky water heaters with good burners ready for experimenting.

You may be able to tighten the temp swing with probe placement.

Have fun,
'da Kid

 

[JonW]

You could easily just add a standing pilot light and use the Asco & PID as is. You would light the pilot once at the beginning of the brew day and let it light the burner every time the valve cycles on.

 

[ajdelange]

At one time I put together a system using a Superb burner fed through an 4-20 loop controlled valve which was tied to a PID controller's 4-20 output. This controller (Omega Engineering) had an auxiliary relay contacts which I programmed to close whenever the controller asked for more than 10% output. Those contacts were wired to a Honeywell gas furnace electronic ignition system. It sort of worked but not very well because heat output was in no way a linear function of the valve angle but it could still hold temperature. I really can't recommend something like this. The fact that you ask the question you do says that you should not be fooling with something like this. I'm an engineer and so was pretty easily able to come up with a design but still feel that it was not something I should have been fooling with. I still have my eyebrows but I did get carbon monoxide poisoning from the thing on one occasion.

 

[RufusBrewer]

I am looking to solve the same problem. I looked at Blichmann engineering and how they start their gas burners as part of their Tower of Power system.

They use a solenoid valve to turn on and off the gas supply. They use an electrode to generate a spark and ignite the gas. Electrodes are common and found on Amazon, EBay, Home Depot, etc.

The big question: How much voltage do you need to generate a sufficient spark to fire the burner? I contacted Blichmann to see how much of a potential they use to generate a sufficient spark. They declined to answer.

I do not blame them. Some guy with an email address asks them a question. Blichmann is going to tell them to start experimenting with high voltage in a wet environment? I would not do it either.

The mechanical installation is pretty simple of the electrode. How much voltage do you need? Part II: How do you generate and then switch or turn on or transmit the required high voltage?

One possible solution? Look up spark gap generator. 5 DC volts in, high volts out. 5 volts DC is easy to create, and switch. If the spark gap generator is physically close to the electrode, and the generator generates enough potential to spark and fire the burner, life is good.

Alternative is generate a high voltage in your control box, and run a high voltage wire out the electrode. It looks as if this is Blichmann's method.

What ever you do, my advice is switch the low voltage into your high voltage generator. Avoid switching high voltage, if you can.

 

[ajdelange]

Something in this series should do:
http://www.amazon.com/dp/B000NWFFIM/?tag=skimlinks_replacement-20
As these are used in home heating systems they are controllable by contact closure with 24 VAC supply. Pick a compatible valve (main and pilot) and you have a system. I do not recommend that amateurs undertake such projects but if you are determined something like this is probably safer than some of the kluges likely to be recommended here.
They also come in hot wire igniter versions.

 

[BigBlock]

I'm in the process of setting up a hsi ignition(S8910U) with 2 solenoid valves that provides a low/med/high heat output depending on which valves are open. I've tested out the solenoid valve setup but haven't finished wiring the HSI up yet. You can check out a video of the valve and manifold setup in another thread I started.

https://www.homebrewtalk.com/showthread.php?t=518609

As others have mentioned, I don't think PID is really what you want. Its possible with multi-stage firing, but may not be ideal.

 

[RufusBrewer]

It is my intention to use my solenoid valve + spark igniter for convenience and to be honest some "Wow! Cool." factor. Gas valves will open only with a press of a button and the sparks will fly when a button is pressed.

There is no auto-on function. The ability to have a Raspberry Pi do it will be there, but not employed. Maybe later, I have to see if I consider it safe enough to have auto turn on and fire a burner.

When I considered how much automation I could use, it is not much. About every step I might automate, there is a manual step that follows. Example: Put a temp probe on HLT and open a valve to fill your mashtun at your mash in temp. OK cool. But immediately after the water gets in the MT, I am going to stir the mash. If I am standing there, waiting for my auto-valve to open, I might as well reach over and open the valve myself.

I settled on a temp probe and an alarm to go off when my water gets to mash in temps.

 

[amayhan]

I work in the propane vaporizer/ natural gas line heater industry. Typically a hysteresis loop is used with an on/off burner controller, or a three stage set point hysteresis loop is used with an off/low/hi setup when heating a directly fired water bath.

Be very careful when using a direct spark or hot surface igniter with an impinged jet burner- the ignition delay when directly fired without a pilot can be surprising. Many an eyebrows have been abruptly erased due to delayed ignition events. This is especially true when the burner has wind shrouds.

The idea behind using a burner management system when automating is to prevent having gas accumulate if there is a flameout during unattended operation. This can be catastrophic in an enclosed area with a vapor that is heavier than air... You also need to be very careful when selecting a solenoid for fuel gas service. They will have different seals and coils.

Water heater thermostats use a thermocouple / thermopile sensing element that will shut off the main gas valve if the pilot goes out- in order to prevent accumulated gas from exploding.

Using a PID loop for on/off control is akin to using a sledge hammer to drive a tack. You could use it in straight proportional mode, but you most likely will not be happy with it. If you are looking for fine temp control, you will not get it with a high output burner on a pot. Meaning that you have to make a trade off between speed of heating up and precision of control. This is where the off/lo/hi really allows a nice compromise between speed of warmup and temperature accuracy.

 

[ajdelange]

Be very careful when using a direct spark or hot surface igniter with an impinged jet burner- the ignition delay when directly fired without a pilot can be surprising. Many an eyebrows have been abruptly erased due to delayed ignition events. This is especially true when the burner has wind shrouds.

The Honeywell controllers I recommended in #6 upon demand for heat open a pilot valve and then shoot sparks at it. Between sparks it looks for current flow between the spark electrode and the frame (a flame apparently acts like a diode). Only when interspark current is detected (i.e. the pilot flame is proved) does the main gas valve open. If the pilot is not proven after some number of trials the controller shuts down and must be reset.

I'm not advocating Honeywell's approach above all others but rather as an example of a simple design that, to my way of thinking, takes care to a large extent of some of the major safety concerns. No pilot - no gas. There is, to my way of thinking, a lot of advantage to using a pre-configured, tested, off-the-shelf system.

The idea behind using a burner management system when automating is to prevent having gas accumulate if there is a flameout during unattended operation.

Continuing to use the Honeywell controllers as an example: If a gust of wind blows out the main flame and the pilot then the controller shuts off the main gas and tries to re-light the pilot. If the pilot is still on it re-establishes the main flame. Add a rollout switch and you are in pretty good shape.

Using a PID loop for on/off control is akin to using a sledge hammer to drive a tack. You could use it in straight proportional mode, but you most likely will not be happy with it.

I wasn't because as I pointed out in #6 50% output from the controller did not result in 50% output or if it did 25% didn't correspond to 25% nor 75% to 75%.

If you are looking for fine temp control, you will not get it with a high output burner on a pot. Meaning that you have to make a trade off between speed of heating up and precision of control. This is where the off/lo/hi really allows a nice compromise between speed of warmup and temperature accuracy.

My non-linear PID system was effectively an off/lo/med-lo/med/med-high/high system and so did hold temperature very well. The problem with PID (or any) control on a mash is mixing. It is very hard to get uniform heat distribution throughout a mix of porridge. I was finally able to achieve that by the use of a Lightnin drum mixer. So my dream of being able to push the start button on the controller and read the newspaper while the system went through the steps of a decoction was realized. Didn't like the system because that non-linearity just bugged me and it was a bit of a kluge. I now use steam with PID control (on/off output for the HLT only) and am much happier with that even though I've lost the automation in the mash.

 

[amayhan]

I completely agree- a bms in conjunction with a true gas valve takes care of the majority of the safety. I was cautioning towards using an innappropriate method of ignition.

I have unfortunately been witness to systems that either malfunctioned or were not designed correctly- with some pretty horrific results. A hot surface igniter is only really good for a simple burner - typically under 200,000 btu/hr.

I would check out bms systems made by fenwal- very simple and reliable.

Robertshaw or baso make an inexpensive pilot valve that is thermocouple maintained. That with an asco fuel gas valve makes a very simple and effective system utilizing a standing pilot.

There are only a couple of accepted methods of automatic burner control:
Hot surface igniter
Direct spark ignition
Interrupted pilot
Standing pilot

A good reference for industrial burner control guidelines is ASME CSD-1, while nfpa 54 is good for propane appliances. The design codes for an appliance vs an industrial system are different and can be confusing.

I understand your point with the pid loop- as pid controllers can be had for cheap. My comment was pointed at those whom are considering a new system.
My experience is mainly with using a plc to control the process.

 

[SnowRaven]

For my Boil Kettle I just wish to add an auto spark system (so if the flame goes out it sparks)

For my Mash RIMMS I already Have the Blichmann Gas Controller and love it so far for a out of the box solution

But for $$$$$ I just want an auto relight feature on the other Burner will not be spending another $500 sorry Blichmann

Would the Honeywell S8610U3009 Furnace Intermittent Pilot Control and a 24 V transformer do the trick or is there a better idea?

 

[BigBlock]

I don't think that you will have a problem with the honeywell setup. Make sure to setup the dip switches properly for your operation and purchase a compatible gas valve. There's a good seq of operation in the user manual.