3540 _ Chapter 28 



to be economically attractive. Wood or bark typically has a moisture content of 

 40 percent or less (wet- weight basis); an increase in moisture content to 60 

 percent reduces the capacity of a Herreshoff carbonizer by one-third. 



Wood or bark pieces admitted to the carbonizer should not exceed 1 by 1 by 4 

 inches, and if the proportion of fines (80-mesh or smaller) exceeds 5 percent, 

 capacity of the carbonizer will be substantially reduced. About 4 tons of wood or 

 bark (ovendry- weight basis) are required to produce 1 ton of charcoal. Systems 

 are usually sized for production of 1 to 4 tons of charcoal per hour. Single-shift 

 operation is not practical; the systems are designed for continuous operation, 24 

 hours/day, 7 days/week with annual scheduled operation totalling about 8,000 

 hours/year. 



No auxiliary fuel is required in charcoal manufacture and an excess of low- 

 Btu gas is produced which can be used for on-site generation of steam and 

 electricity for sale. Typically about 25,000 pounds of steam can be produced 

 from the excess gas yielded during production of 1 ton of charcoal. Steam, if 

 sold, might bring about $5.75 per thousand pounds. 



The charcoal can be sold in granular form at about $90/ton or it can be blended 

 with starch binder, pressed into briquets, and sold for about $240/ton. In this 

 study, cost of wood was estimated at $20/ton, ovendry- weight basis. 



Enterprises utilizing the Nichols Herreshoff carbonizer are projected profit- 

 able in operations with charcoal outputs from 8,000 to 40,000 tons/year, requir- 

 ing investments from $3.6 to $13.0 million. Key statistics for two enterprises, 

 both converting excess gas to steam for sale, are tabulated as follows; one 

 enterprise produces 32,000 tons/year of loose charcoal and the other 40,000 

 tons/year briquetted charcoal: 



Charcoal Charcoal 



sold sold 



Statistic unbriquetted briquetted 



Charcoal production rate, tons/year 32,000 40,000 



Steam production rate, pounds/hour 100,000 100,000 



Capital investment $7,229,000 $13,014,000 



Operating costs, annual $4,494,000 $ 9,089,000 



Sales, annual $7,480,000 $14,200,000 



Net profit, annual (before income tax) $2,986,000 $ 5,111 ,000 



Return on sales 39.9 percent 36.0 percent 



Return on investment 41.3 percent 39.3 percent 



Employees 14 69 



Energy requirement, annual 



Electrical 3,775,000 kWh 5,400,000 kWh 



Gasoline, oil, or natural gas 



Wood residue, as feed stock (ovendry- weight basis) .... 128,000 tons 128,000 tons 



