Nano-dispersions of coal in water as the basis of fuel related technologies and methods of making same

Abstract

Colloidal coal-in-water slurries having nano-particles of coal creating a pseudo-fluid. The colloidal coal-in-water slurry generally includes from about fifty to about seventy two weight percent of coal, with about 20 to about 80 percent of the coal having a particle size of about one micron or less with a mode particle size of about 250 nanometers. The coal-in-water slurry can also include a surfactant system containing one surfactant or mixtures of two or more surfactants, or mixtures of one or more surfactants and an inorganic or organic salt. The coal-in-water slurry can be used in low NOx burner applications as the main fuel and/or the reburn fuel, in gasification processes as the input fuel either alone, or in combination with organic materials, in gas turbine applications, and in diesel engine applications.

What is claimed is: 
     
         1 . A colloidal slurry of nano-dispersed coal in water suitable for use as an efficient-burning fuel, the slurry comprising:
 coal particles dispersed in water, the coal particles comprising about 50 weight percent to about 80 weight percent of the slurry, the water comprising about 20 weight percent to about 50 weight percent of the slurry, between about 30% to about 50% of the coal particles having a size of about 10 microns or less, and about 20% to about 80% of the coal particles having a size of one micron to about 100 nm with a size mode of about 200 nm to about 300 nm.   
     
     
         2 . The coal-water slurry according to  claim 1 , wherein the coal particles comprise about 60 weight percent to about 70 weight percent of the slurry, and the water comprises about 30 weight percent to about 40 weight percent of the slurry. 
     
     
         3 . The coal-water slurry according to  claim 1 , the slurry further comprising at least one surfactant system selected from the group consisting of a nonionic surfactant, an ionic surfactant, an inorganic salt, an organic salt, and combinations thereof. 
     
     
         4 . The coal-water slurry according to  claim 3 , wherein the at least one surfactant system is present in the slurry in the amount of about 500 to about 3000 parts per million. 
     
     
         5 . The coal-water slurry according to  claim 1 , the slurry further comprising large coal particles having a size of about 150 μm to about 400 μm. 
     
     
         6 . The coal-water slurry according to  claim 5 , wherein a size ratio of the large coal particles to the coal particles is greater than 100. 
     
     
         7 . The coal-water slurry according to  claim 6 , wherein the coal particles comprise about 58 weight percent to about 62 weight percent of the slurry, and the coal particles and the large coal particles comprise about 68 weight percent to about 72 weight percent of the slurry. 
     
     
         8 . The coal-slurry according to  claim 7 , wherein at least a portion of the water is replaced with a volatile component, the volatile component selected from the group consisting of methanol, ethanol, propanol, butanol, glycerol or combinations thereof. 
     
     
         9 . The coal-water slurry according to  claim 5 , wherein a mass fraction of the large particle size coal is about 25% to about 35% of the total coal in the slurry. 
     
     
         10 . The coal-water slurry according to  claim 5 , wherein the large coal particles are suspended in a relevant colloidal fraction of the coal particles. 
     
     
         11 . The coal-water slurry according to  claim 1 , wherein the slurry has a viscosity at 120 degrees Fahrenheit in the range of about 350 centipoise to about 1000 centipoise. 
     
     
         12 . The coal-water slurry according to  claim 1 , wherein the coal particles have a size less than 100 microns. 
     
     
         13 . The coal-water slurry according to  claim 1 , wherein a particle size distribution of the coal particles is multi-modal, with a first mean particle size of about 200 to about 350 nanometers, a second mean particle size of about 1 to about 2 microns, and a third mean particle size greater than 4 microns. 
     
     
         14 . The coal-water slurry according to  claim 1 , wherein a particle size distribution of the coal particles is bimodal. 
     
     
         15 . The coal-water slurry according to  claim 1 , further comprising a nano-dispersion of an organic liquid or oil. 
     
     
         16 . The coal-water slurry according to  claim 1 , further comprising at least one alternative fuel source selected from the group consisting of biomass, petroleum coke, and combinations thereof, wherein the 50 weight percent to about 80 weight percent of the slurry comprised of coal particles is about 50% to about 60% coal particles and about 40% to about 50% alternative fuel source. 
     
     
         17 . The use of the coal-water slurry according to  claim 1  as the efficient-burning liquid fuel in an application selected from the group consisting of a low NOx burner, a gasification process, a gas turbine, a diesel engine, and a Rankine cycle. 
     
     
         18 . The coal-water slurry according to  claim 1 , wherein the coal particles are selected from the group consisting of lignite, sub-bituminous, bituminous, and anthracite. 
     
     
         19 . A slurry of coal-in-water comprising:
 large coal particles having a size of about 150 microns to about 400 microns suspended in a colloidal fraction of a nano-dispersion of coal in water, the nano-dispersion of coal in water having nano-sized coal particles and micronized coal particles, wherein the water comprises about 28 weight percent to about 32 weight percent of the slurry, between about 30% to about 50% of the micronized coal particles have a size of about 4 microns or less, at least 20% of the nano-sized coal particles have a size less than 1 micron with a mode size of about 200 nm to about 300 nm, the nano-sized and microsized coal particles comprising about 58 weight percent to about 62 weight percent of the slurry, and the large coal particles comprising about 10 weight percent to about 14 weight percent of the slurry.   
     
     
         20 . The coal-water slurry according to  claim 19 , further comprising at least one surfactant system selected from the group consisting of a nonionic surfactant, an ionic surfactant, an inorganic salt, an organic salt, and combinations thereof.