mushroom substrate treatment

mushroommatt

Hello everyone, I am a hobby level mushroom grower making the leap into full time growing. My goal right now is to design a steam vessel to treat my substrate in.
I know that ideally i would do it in a retort or autoclave to reach the higher temps typically required to truly sterilize something. Those are out of my price range and i don't have the footprint for most of the used ones that can be had.
Many small to mid-size growers use a process they call superpasturization, basically you use steam to heat the substrate up to 200+F and then hold it there for 8-12 hrs. For smaller scale, a insulated metal drum with a 1500- 3000W water heater element, false bottom, and float valve does the job. I need alot more capacity than that. I have a 6Kw steam generator. I am trying to determine how large a vessel i can use with it and still be able to get my substrate core up to at least 200F. i will be cooking hydrated supplemented sawdust in high temp polyproplene bags, aprox 10-12 lbs of hydrated sawdust per bag.
IS there any difference in heat loss between a tall thinner vessel vs a short long vessel?
IS there a way to calculate how much time it will take to heat up a known volume with a known mass?
Basically i am trying to fuiger out how large a vessel, in cubic feet, i can use with the 6 Kw unit i have. i plan to bypass the thermostat and run it wide open. i know this is not the designed use, or recomended but some people have used these units like that for over year doing once a week runs ] without the units breaking down. i am aware water quality can effect this also, they can be gotten cheap from china for like 150$ even if i burn one up ever 6 months, i am fine with that. Once i have the money i will probably pay someone to design a control system so i can have it cycle off and on once i reach my desired core temp
Usually growers design these things thru trial and error, i am hoping to bypass alot of that error by asking you experts in the field. Any thoughts, advice, criticism is welcome and i thank you for taking the time to read this.
i have had some thoughts of using a galvanized cattle trough, an aluminum proofer box for bread, or building a custom unit with sheet aluminum and galvanized studs. all these options can be insulated to whatever R value is recommended.
i do have some basic experience in a number of fields. I worked in the plastics industry for 23 years hanging molds, fixing machines, troubleshooting etc, until a back injury 4 years ago forced me out on medical leave and i was unable to return due to lifting restrictions. i am just trying to get back on my feet now. running my own business was the only feasible option i could think of for my broken **** lol. Plus i have been studying mushrooms in general for almost a decade. thanks again, Matt