Switch grass fuel objects with high heat output and reduced air emissions designed for large-scale power generation

Abstract

A Novel fuel object comprised of a proportion of switch grass and a proportion of wood fiber combined with a basically reacting compound. The fuel comprises fiber of the appropriate size and moisture content combined with an inorganic base. An appropriately sized fuel object is readily manufactured, provides high heat output, is consistent in fuel characteristics, and is sized and configured for use in power generation facilities. Based on fiber selection and processing, the fuel object may be used in a variety of current power generation technologies including stoker, fluidized bed, gasifier, cyclonic, direct-fired, and pulverized coal technologies, and results in significant reduction of air emissions (including sulfur dioxide, nitrogen oxides, hydrochloric acid, carbon monoxide, carbon dioxide, and mercury) compared to coal with no loss of boiler or furnace efficiency.

1 . A fuel source comprising a object having maximum dimension of about 6 cm, a volume of about 10 to 100 cm 3 , a moisture content of less than about 14 wt. %, the fuel comprising:
 (i) about 60 to 80 wt. % of a particulate derived from switch grass having a particle size of about 80 to 25,000 microns;   (ii) about 20 to 40 wt. % of a wood fiber having a particle size of about 100 to 30,000 microns;   (iii) about 1-10 wt % of an inorganic base; and   (iv) wherein the fuel source is substantially free of coal as a heat source and the fuel provides at least 7,000 BTU-lb. −1  (3500 cal.-gm −1 ).   
   
   
       2 . The fuel source of  claim 1  wherein the object comprises a cubic or cylindrical unit with a side dimension of 2 to 6 cm. 
   
   
       3 . The fuel source of  claim 1  wherein the object comprises about 60 to 80 wt. % of a particulate derived from switch grass having a particle size of about 80 to 25,000 microns. 
   
   
       4 . The fuel source of  claim 1  wherein the object comprises about 20 to 40 wt. % of a particulate derived from wood fiber having a particle size of about 100 to 30,000 microns. 
   
   
       5 . The fuel source of  claim 1  wherein the inorganic base comprises about 1 to 10 wt. % of sodium bicarbonate, dolomite or mixtures thereof. 
   
   
       6 . The fuel source of  claim 1  wherein the BTU source of the fuel consists essentially of about 60 to 80 wt. % of switch grass and 20 to 40 wt. % of wood fiber wherein the fuel source is substantially free of coal as a heat source and the fuel provides at least 7,000 BTU-lb. −1  ( 3500  cal.-gm −1 ). 
   
   
       7 . The fuel source of  claim 1  wherein the density of the fuel object is 30 to 40 lbs/ft 3  (0.5 to 0.65 gm-cm −3 ).