Fire box insulation

I have read many interesting threads here in the past and decided to join today.
Has anyone used super firetemp x for a fire box on a diy project. I believe it's the same product used
for firemen practice buildings to protect the structure. Any feedback would be welcome.
I am thinking about building a water boiler this spring. I have built a gasifier in the past and it worked well. I will be moving and decided to build another (non gaser, not worried about smoke anymore and easier to build) using concrete block then ceramic blanket then super firetemp x against the flame.
The water tank will set on top of the structure.

For anyone interested, I found super firetemp x only has 1 to 4 hour fire rating.

IMO not too cool to not worry about smoke and pollution.

I'm not burning coal here. One's definition of smoke is different than another's. I should have said, I will build one to produce little smoke. The gasser had no visible smoke, does not mean there is no pollution. You can still build a stove to produce very high combustion temps without being a gasser. If you give the fire enough burn time in a well insulated environment, you will burn most of the smoke which I believe has half of the BTU's in it. I am changing designs because of fuel supply.

Would the water tank on top of the fire not cool it too much?

Maple, The fire box will have a refractory top below water tank, creating a channel for the fire to travel allowing a longer burn time before coming incontact with the tank. This idea is just in my head for now. I guess it is like a gasser in a way (it burns up not down through a layer of charcoal). If I have time today, I will draw my idea with google sketchup, a great free tool to get a good look at an idea.

Well - good luck!

The main thing I'm impressed about with how my new boiler burns is the way it burns everything so completely by downdrafting through the coal bed, ensuring everything down there gets turned to ashes. My old boiler would just pile up with hot coals & clinkers on the bottom, if I didn't clean them out regularly my firebox volume would go to nothing in short order. The last couple of days, once I've got a hot coal bed going, I've been loading up the firebox with waste off the floor (bark, chips, all the messy stuff) on a couple of new splits and getting great heat out of it - last few years, I'd been wheelbarrowing that stuff to the compost pile at the end of the season because my old one just couldn't handle it.

Not that it's relevant, but I used a piece of Microre 300 as a baffle in my old insert. It lasted about a month, as I recall, before it deteriorated.

I believe if you get anything hot enough, it will burn. I do like all the gassers you can buy but I like to tinker to much.

When I bought refractory for my first stove, they said that wood burning creates one of the harshest environments for their material.

Here's a quick drawing. I'm sure I will adjust deminsions, and the colors were just the one's sketchup had.
It will be insulated on the outside with 2" ceramic blanket and 4" of rock wool then wraped up with faced blocked.