we are drying pea gravel, and also fine sand, for use as concrete aggregate and mason agg. the dryer is 5' dia 29' long. with an 8 million BTU Gas burner, dust collection fan is moving 14,000 CFM
Without having to go into a detailed investigation, I can tell you some basics about your dryer capacity:
1) Calculate the sensible heat required to warm the air to 212F from the follwoing equation: q=1.08 CFM (212-Ti).
2) The most water you can evaporate from the air is:
M=q/dH = 8,000,000 Btu /970 Btu/lbs = 8,247 lbs. (This is an approximation because you need to subtract the heat required from 1).
3) The actual values will change based on your before and after gravel moisture content and the incoming air properties.
Is your aggregate and sand produced at a rock crushing plant that you operate? and what is the utimate use for your products?
I was involved at CS&S in Ct. for 10 years and the aggregate did not require drying. As a matter of fact, we wetted the aggregate most of the years for our cement batch mixing plants. Drying was never considered but looking at the above equations from Dracula they appear correct as well as his statement concerning state of wettness.
What you want to do is perform a mass balance and a heat transfer analysis of moisture and of the aggregate and estimate the time element of the drying process and compare with the actual values; of course do not discount the enviromental factors affecting the plant performance.
