I have never burned corn but I have burned a LOT of veg oil and made a lot of burners using different principals for that.
I am interested in your belief the pre heated air makes a difference to the fire and why?
People telling me all the time on my YT channel about air preheating but I have not been able work out any benefit other than a small increase in transition speed from preheat to operating temp which is negligible anyway. Certainly whilst burning there is no difference/ benefit at all.
Any heat in the air is removed as it were from the fire so the net output will be the same. In my burners there is so much excess heat, ( things run red hot in normal operation) that air preheating serves no purpose. But you are not burning oil or working on the retained heat principal my burners work on so I'm interested to learn more about what the pincipals involved with what you are doing are.
From your pictures it seems the corn burns under the air injection nozzles, is that correct?
Have you also worked out what the KW heating value is from your burner? That engine looks like a LOT of thermal mass and water to get up to temp.
I would think you'd be wanting significant output to get it up to steam in a timely manner.
I'd love to be able to throw one of my burners at something like a steam engine. My small burners do 200Kw+ and the largest I have verified is 600KW but I have taken it over 1000 only didn't accurately measure it. There really is no limit to what they can put out other than practacality. Even throwing 50Kw at a metal melting furnace tends to melt the furnace itself.
I had a heat exchanger that came out of a gas boiler that heated an Olympic size pool and was rated at 200Kw. I over powered that pretty easily ( and scarily!)
A steam engine I think would be a great use for one of these burners and probably be able to set a record for going from dead cold to full pressure. :0)
I have also used 12V blowers on my burners. They were boat bilge blowers and had them on a PWM as well although for my use, I pretty much ran the things flat out anyway and the controller was only used to regulate the start-up air.... which I could do every bit as well with a piece of cardboard over the inlet of the blower as a choke.
Air preheating aside, I think your burner would work well for oil if it were inverted and placed in a deep pan. If you don't get enough heat with corn, I'm thinking you should be able to get at least 100Kw with that setup on oil. You'd get a lot more with a bigger blower. An option may be to use a couple of batteries, a 12/24V inverter and a 110/ 220V blower. My favourites are those used for jumping castles but they may be a bit bulky for your needs. They are cheap off fleabay though. In any case there are certainly a lot more available in mains power than 12V.
That said, a lot of hair-dryers use 12V motors and as well as doing good volume, they also by design do good air pressure. With the convoluted tube you are using of smallish diameter, pressure is a consideration as well and high speed fans are much better at that than something like most 12V blowers. You could also use more than one hairdryer if needed as they could be modified to be pretty compact once you took away the heating elements, switches and superfluous housing.
As you are preheating the air, could you use steam once the boiler was up to speed for your burner air? I imagine a 1'/4 line at even 50 PSI and set up in an inducer fashion to pull in more air and drop the pressure would give a real good airflow. The steam should not be a worry as it will remain above condensing temps. If this could be made workable, You'd only need the blower to raise steam on once you had, the engine could be totally self sufficient.
Can the corn be burned on a grate like wood or coal? ( with a smaller mesh of course. )
Just an idea but I'd be very interested to know more on your thoughts about the preheated air and it's effect and what sort of KW output you are getting from burning corn.