Biomass fuel pellets incorporating wax compositions

Abstract

A wax composition can be incorporated into a biomass mixture, such as a woody biomass mixture, for formation of pellets, such as wood fuel pellets. The addition of wax compositions with suitable amounts of n-paraffins relative to the amount of oil-in-wax can result in biomass pellets with improved properties, such as improved durability and/or reduced tendency to uptake moisture during storage. Addition of a suitable wax composition can also allow for formation of biomass pellets with improved properties while also reducing or minimizing the power requirements during pellet formation.

1 . A biomass pellet composition comprising 0.15 wt % to 5.0 wt % of a wax composition relative to a weight of the biomass pellet composition, the wax composition comprising n-paraffins and oil-in-wax, a weight of the n-paraffins being greater than a weight of the oil-in-wax by at least 0.10 wt % relative to the weight of the biomass pellet composition. 
     
     
         2 . The biomass pellet composition of  claim 1 , wherein the wax composition comprises at least 1.0 wt % oil-in-wax relative to a weight of the wax composition. 
     
     
         3 . The biomass pellet composition of  claim 1 , wherein the weight of the n-paraffins is greater than the weight of the oil-in-wax by at least 0.15 wt % relative to the weight of the biomass pellet composition. 
     
     
         4 . The biomass pellet composition of  claim 1 , wherein the biomass comprises woody biomass, grassy biomass, residual agricultural biomass, or a combination thereof. 
     
     
         5 . The biomass pellet composition of  claim 1 , wherein the biomass pellet composition comprises a surface wax concentration that differs from an interior wax concentration by less than 60 wt % relative to the surface wax concentration. 
     
     
         6 . The biomass pellet composition of  claim 1 , wherein the wax composition comprises a particle size of at least 4.0 μm. 
     
     
         7 . The biomass pellet composition of  claim 1 , wherein the biomass pellet composition comprises a pellet durability index of at least 97.0 wt %. 
     
     
         8 . The biomass pellet composition of  claim 1 , wherein the biomass pellet composition comprises a reduced tendency to adsorb water relative to a reference biomass pellet composition that contains less than 0.01 wt % of the wax composition. 
     
     
         9 . The biomass pellet composition of  claim 8 , wherein the wood pellet composition comprises a reduced tendency to produce CO as an off-gas during storage relative to the reference biomass pellet composition. 
     
     
         10 . The biomass pellet composition of  claim 1 , wherein the biomass pellet composition comprises a pressed biomass pellet composition. 
     
     
         11 . The biomass pellet composition of  claim 1 , wherein the biomass pellet composition comprises at least 80 wt % biomass, or wherein the biomass pellet composition comprises 10 wt % or less of water, or a combination thereof. 
     
     
         12 . A pressed biomass pellet composition comprising 0.15 wt % to 5.0 wt % of a wax composition relative to a weight of the biomass pellet composition, the wax composition comprising n-paraffins and oil-in-wax, a weight of the n-paraffins being greater than a weight of the oil-in-wax by at least 0.10 wt % relative to the weight of the biomass pellet composition. 
     
     
         13 . The pressed biomass pellet composition of  claim 12 , wherein the wax composition comprises at least 1.0 wt % oil-in-wax relative to a weight of the wax composition; or wherein the biomass pellet composition comprises a pellet durability index of at least 97.0 wt %; or wherein the biomass pellet composition comprises a surface wax concentration that differs from an interior wax concentration by less than 60 wt % relative to the surface wax concentration; or a combination thereof. 
     
     
         14 . A woody biomass composition comprising woody biomass, less than 25 wt % water, and 0.15 wt % to 5.0 wt % of a wax composition relative to a weight of the woody biomass composition, the wax composition comprising n-paraffins and oil-in-wax, a weight of the n-paraffins being greater than a weight of the oil-in-wax by at least 0.10 wt % relative to the weight of the woody biomass composition. 
     
     
         15 . The woody biomass composition of  claim 14 , wherein the wax composition comprises at least 5.0 wt % oil-in-wax relative to a weight of the wax composition. 
     
     
         16 . The woody biomass composition of  claim 14 , wherein the weight of the n-paraffins is greater than the weight of the oil-in-wax by at least 0.15 wt % relative to the weight of the woody biomass composition. 
     
     
         17 . The woody biomass composition of  claim 14 , wherein the woody biomass composition comprises 20 wt % or less of water. 
     
     
         18 . The woody biomass composition of  claim 14 , wherein the wax composition comprises a particle size of at least 4.0 μm. 
     
     
         19 . The woody biomass composition of  claim 14 , wherein the wax composition comprises a weight of n-paraffins that is greater than a weight of oil-in-wax by at least 15 wt % relative to a weight of the wax composition. 
     
     
         20 . A method of forming a biomass pellet, comprising:
 pressing a mixture comprising biomass and a wax composition through a die to form a pressed biomass pellet comprising 0.15 wt % to 5.0 wt % of the wax composition, the wax composition comprising n-paraffins and oil-in-wax, a weight of the n-paraffins being greater than a weight of the oil-in-wax by at least 0.10 wt % relative to the weight of the pressed biomass pellet.   
     
     
         21 . The method of  claim 20 , wherein the wax composition comprises at least 10 wt % oil-in-wax relative to a weight of the wax composition. 
     
     
         22 . The method of  claim 20 , wherein pressing the mixture to form a pressed biomass pellet comprises a power consumption of less than 2500 amps2/g. 
     
     
         23 . The method of  claim 22 , wherein pressing the mixture to form a pressed biomass pellet comprises a power consumption corresponding to less than 60% of a power consumption for pressing a reference mixture comprising less than 0.01 wt % of the wax composition. 
     
     
         24 . The method of  claim 20 , wherein the weight of the n-paraffins is greater than the weight of the oil-in-wax by at least 0.15 wt % relative to the weight of the pressed biomass pellet. 
     
     
         25 . The method of  claim 20 , wherein the pressed biomass pellet comprises a pressed woody biomass pellet.