----- Original Message -----
From: Moacir Beltrame
Sent: Sunday, September 15, 2002 5:45 PM
Subject: Fire in pile !
Dear Mr. Jim Mc Nelly, and all.
Thank you very much for your answer, that was very elucidating.
I also would like to say that I am a great admirer of your work, because I always learn a lot with your opinions in the forum, that has people that really understand of composting, very rare fact in my country.
Actually, I work with approximately 50 ton/day of different types of residues, as remains of candies, destroyed victuals or with due validity, but mainly with biological sludges of food industries.
All those residues and also the shavings of wood, prunings of trees and grass, shavings of return of the sieve, are constantly analyzed at the Laboratory of the University of Agronomy of Sao Paulo State (ESALQ/USP), so I know the composition of each one of them (total humidity, pH, Total Organic Matter - %, Compostible Organic Matter - %, Organic Carbon - %, N - %, P - %, K - % and other, in dry base).
To calculate the proportions of each residue, for to adapt the humidity and the relationship C/N of the mixture, I use the spreadsheet developed by Tom Richard, of Department of Agricultural and Biological Engineering, Cornell University.
My blowers have very high pressure, I don't have, now in my hands, its catalog for to specify it, but the entrance of air has to be protected, to avoid accidents, because it "pulls" the air with a lot of force.
The blower's exit is of 4 inches. The size of the pipe and of its perforated area, the number of holes for line, the diameter of the holes, as well as the spacing among them, all are calculated for that the total area of the holes, don't be larger than the double of the area of the pipe, and the speed of the air of the pipe it doesn't exceed 2,000 ft/min.
I use 2 lines of holes placeds in the positions of "5" and "7" hours. I make the "bed" with grass because it is an abundant and cheap material, already the shavings are very expensive and I need them to form spaces for the circular air for the whole mass that will be composting.
Our piles are with 4 to 5 meters of width, in the maximum 2 to 2.5 meters of height, because the machines, that we use to make the mixture and set up and disassemble the piles, don't reach more than that. The piles had between 18 to 20 meters in length.
The reading of the temperature is made daily, by "termopares" that are placed to stocking height of the piles, at the 0.70 to 0.80 meters of depth. They installed in 10 points of each pile. So I have a very representative average of each one.
Depending on the total dry mass of the pile, and of the daily evolution of the temperature, I alter the programming of the timers, to increase or to reduce, the aeration periodicity, and to obtain a flow of air, that doesn't just maintain the oxygenated the pile, as well as the temperature below 70° C.
Really, the aeration system developed in Belstville in the 80's it is defective, because I also observed that the need of air is much larger than the suitable.
Usually, I have problems to lower the humidity of the sludges, and it is very difficult and not always I can work in ideal conditions, and if the aeration cannot be adapted, eventually cans drain liquid of the pile.
To avoid that, and as the demand for oxygen is a lot of high in the beginning, I work with flows of air almost continuous, leaving the blower turned off by very small intervals of time.
I suppose that in the pile that fired, the employee that changed the programming of the timer had wandered and the pile had received too much air, that ended up cooling the pile too much, and killing the microorganisms termophylics. This explains the low temperatures, and for this I suspended the ventilation, so that they could recover, but in this point the pile was already too dry. With the lack of oxygen, must have happened some anaerobic activity, which generated methane inside of the pile, or still alcohol, like you suggested. With the retaking of the aeration and the entrance of oxygen, should have servant the ideal condition to begin the fire and, really the pile totally burned from within for outside, everything turned coal and the pipe melted. Only remained some 4 meters in the end.
After I ordered the question to the Forum of C.C., I researched the theme in the Internet and I found your answer for another person in September of 1998, very completes and informative. Therefore for the that you explained at that time to him, I already had an idea of what it could have happened with my pile.
If it goes of your interest, or another of Forum of C.C., I can order more material on my Company (photos, etc.), I don't develop composting facilitys, I only sell compost. In last June's issue of the magazine BIOCYCLE, have a article, signed by my husband (Moacir Beltrame) that works with me. You can see if you wants.
I love what I do, I think you should also like very much, for the enthusiasm with talk about composting.
Thank you very much for all.
Kátia Goldschmidt Beltrame
BIOLAND Industria e Comercio de Composto Organico Ltda.
P.O. Box 02 - Piracicaba - 13400-970 - Sao Paulo State - Brasil