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 object having maximum dimension of about 6 cm, a volume of about 10 to 100 cm 3 , the fuel object 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) less than about 14% of water,   wherein the fuel object is substantially free of coal and polymeric binder, and the fuel and provides at least 7,000 BTU-lb. −1  (3500 cal.-gm −1 ) upon combustion.   
     
     
         2 . The fuel object of  claim 1  wherein the fuel object comprises a cubic or cylindrical unit with a side dimension of 2 to 6 cm. 
     
     
         3 . The fuel object of  claim 1  wherein the inorganic base is selected from the group consisting of sodium bicarbonate, dolomite, and mixtures thereof. 
     
     
         4 . The fuel object of  claim 1  wherein the BTU source of the fuel object consists essentially of:
 (i) about 60 to 70 wt. % of switch grass; 
 (ii) about 30 to 40 wt. % of wood fiber; 
 (iii) about 2 to 3 wt. % of an inorganic base; and 
 (iv) about 8 to 14 wt. % of water. 
 
     
     
         5 . The fuel object 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 ). 
     
     
         6 . The fuel object of  claim 8 , wherein upon combustion, the fuel object produces a first amount of energy and emits about 95% less SO 2  compared to combustion of an amount of coal that provides substantially the same amount of energy as the first amount of energy. 
     
     
         7 . The fuel object of claim  10 , wherein upon combustion, the fuel object produces a first amount of energy and emits about 40% less NO x  compared to combustion of an amount of coal that provides substantially the same amount of energy as the first amount of energy. 
     
     
         8 . The fuel object of  claim 1 , wherein upon combustion, the fuel object produces a first amount of energy and emits about 95% less SO 2  and about 40% less NO x  compared to combustion of an amount of coal that provides substantially the same amount of energy as the first amount of energy. 
     
     
         9 . A fuel object 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 to 10 wt. % of sodium bicarbonate; and   (iv) less than about 14% of water;   wherein the fuel object is substantially free of coal and conventional binder material, and, upon combustion, produces a first amount of energy and emits about 95% less SO 2  and about 40% less NO x  compared to combustion of an amount of coal that provides substantially the same amount of energy as the first amount of energy.