Cinnamon , From my days of putting down new roofs with a hand held flame thrower , they make 20 # , 30 # , and 40# tanks . the one pictured looks like a 30 or 40 # er. See if you have a welding / propane dealer around.A comercial roofing suply may tell you where to look as well, They may be able to hook you up with a little bigger tank. When you get into the 100# ers , you get into liquid and vapor tanks. Same stuff goes into the tank , but one draws the liquid from the bottom of the tank and the other is like the 20 , 30 , and 40 #ers drawing from the top.
Hope this helps.