Abstract:
Disclosed is a process for conveying solid particulate biomass material to a reactor including: charging a quantity of solid particulate biomass material to a spool piece at a pressure P 1 ; pressurizing the spool piece to a pressure P 2 , wherein P 2  is greater than P 1 ; conveying the solid particulate biomass material either directly to a reactor operated at or below P 2  or first to a vibratory feeder and then to such reactor; isolating the spool piece from the vibratory feeder and or reactor and reducing the pressure in the spool piece to P 1 ; and repeating these steps at least once. The vibratory feeder can include a bowl and an outlet spout extending tangentially from the bowl. Optionally, a hopper and a hopper-mounted solids conveyer, both resting on a mass measuring device, can be used to feed the solid particulate biomass material to the spool piece.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to the conversion of biomass to oxygenated hydrocarbons. More particularly, the invention relates to an improved biomass feed system or process for conveying biomass to a reactor for conversion to oxygenated hydrocarbons. 
         [0003]    2. Description of the Related Art 
         [0004]    Pyrolysis, in particular flash pyrolysis, has been proposed as a process for converting solid biomass material to liquid products. Pyrolysis in general refers to a process in which a feedstock is heated in an oxygen-poor or oxygen-free atmosphere. If solid biomass is used as the feedstock of a pyrolysis process, the process produces gaseous, liquid, and solid products. 
         [0005]    Charging solid biomass to a reactor in an even and continuous manner poses numerous technical challenges. One such challenge is the pulsing of the biomass due in part to feed compaction during conveyance. Another challenge concerns the continuous re-charging of the biomass feed hopper in a pressurized system. 
         [0006]    Thus, it is desirable to develop improved methods/systems for charging solid biomass to a reactor in an even and continuous manner. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In accordance with an embodiment of the present invention, a process is provided including the steps of:
       a) providing a spool piece having a pressure vent, an inlet valve and an outlet valve; wherein the outlet valve is connected in fluid flow communication with a reactor;   b) closing the outlet valve;   c) opening the inlet valve;   d) charging a quantity of the solid particulate biomass material to the spool piece through the inlet valve at a pressure P 1 ;   e) closing the inlet valve;   f) pressurizing the spool piece to a pressure P 2 , wherein P 2  is greater than P 1 ;   g) opening the outlet valve and conveying the quantity of the solid particulate biomass material to the reactor operated at or below pressure P 2 ;   h) closing the outlet valve;   i) opening the pressure vent to reduce the pressure in the spool piece to P 1 ; and   j) closing the pressure vent.       
 
         [0018]    In accordance with an embodiment of the present invention, a process/system is provided including the steps of:
       a) providing a spool piece having a pressure vent, an inlet valve and an outlet valve;   b) providing a vibratory feeder connected in fluid flow communication with the outlet valve;   c) providing a reactor-mounted solids conveyer connected in fluid flow communication with the vibratory feeder and with a reactor;   d) closing the outlet valve;   e) opening the inlet valve;   f) charging a quantity of the solid particulate biomass material to the spool piece through the inlet valve at a pressure P 1 ;   g) closing the inlet valve;   h) pressurizing the spool piece to a pressure P 2 , wherein P 2  is greater than P 1 ;   i) opening the outlet valve and conveying the quantity of the solid particulate biomass material to the vibratory feeder;   j) conveying the quantity of the solid particulate biomass material to the reactor-mounted solids conveyer for charging to the reactor operated at a pressure at or below P 2 ;   k) opening the pressure vent to reduce the pressure in the spool piece to P 1 ; and   l) closing the pressure vent.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    The features and advantages of the invention will be appreciated upon reference to the following drawings, in which: 
           [0032]      FIG. 1  is a flow diagram showing an embodiment of the present invention. 
           [0033]      FIG. 2  is a flow diagram showing an embodiment of the present invention. 
           [0034]      FIG. 3  is a section taken across line  3 - 3  of  FIG. 2  showing in greater detail certain features and details of the feed system/process. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]    The biomass material useful in the current invention can be any biomass capable of being converted to liquid and gaseous hydrocarbons. 
         [0036]    Preferred are solid biomass materials comprising cellulose, in particular lignocellulosic materials, because of the abundant availability of such materials, and their low cost. Examples of suitable solid biomass materials include forestry wastes, such as wood chips and saw dust; agricultural waste, such as straw, corn stover, sugar cane bagasse, municipal waste, in particular yard waste, paper, and&#39;card board; energy crops such as switch grass, coppice, eucalyptus; and aquatic materials such as algae; and the like. 
         [0037]    An embodiment of the invention will be described with reference to  FIG. 1 . 
         [0038]    A process/system  100  is provided and comprises, consists of, or consists essentially of:
       a) providing a spool piece  102  having a pressure vent  104 , an inlet valve  106 , and an outlet valve  108  connected in fluid flow communication with a reactor  112  via a conduit  114 ;   b) closing outlet valve  108 ;   c) opening inlet valve  106 ;   d) charging a quantity of solid particulate biomass material to spool piece  102  through conduit  110  and inlet valve  106  at a pressure P 1 ;   e) closing inlet valve  106 ;   f) pressurizing spool piece  102  to a pressure P 2 , wherein P 2  is greater than P 1 ;   g) opening outlet valve  108  and conveying the quantity of solid particulate biomass material to reactor  112  via conduit  114 , wherein reactor  112  is operated at or below pressure P 2 ;   h) closing outlet valve  108 ;   i) opening pressure vent  104  to reduce the pressure in spool piece  102  to P 1 ; and   j) closing pressure vent  104 .       
 
         [0049]    Steps c) through j) are preferably repeated at least once. 
         [0050]    Pressure P 1  can be equal to or less than atmospheric pressure. Pressure P 2  can be greater than atmospheric pressure, and can be greater than 20 psia. 
         [0051]    The process/system  100  can also include a hopper  116  connected in fluid flow communication with a solids conveyer  118  which is connected in fluid flow communication with inlet valve  106  via conduit  110 . Solid particulate biomass material can be passed from hopper  116  to spool piece  102  by solids conveyer  118  and conduit  110 . Solids conveyer  118  can be a screw feeder. 
         [0052]    The process/system  100  can also include the measurement of the mass flow rate of the solid particulate biomass material to reactor  112 . Hopper  116  and solids conveyer  118  can rest on a mass measuring device  120  selected from the group consisting of a scale or a load cell, and the mass flow rate can be measured by monitoring the weight of the solid particulate biomass material entering hopper  116  and leaving solids conveyer  118  using mass measuring device  120 . 
         [0053]    Conduit  114  can be a screw feeder for conveying the solid particulate biomass into reactor  112 . A pressurized gas stream can be charged to conduit  114  to provide a constant flow of gas to reactor  112 . Reactor  112  can be a riser reactor, a fluid bed reactor, a moving bed reactor, or a cyclone reactor. 
         [0054]    An embodiment of the invention will be described with reference to  FIG. 2 . 
         [0055]    A process/system  200  is provided and comprises, consists of, or consists essentially of:
       a) providing a spool piece  202  having a pressure vent  204 , an inlet valve  206 , and an outlet valve  208 ;   b) providing a vibratory feeder  210  connected in fluid flow communication with outlet valve  208  via a conduit  212 ;   c) providing a reactor-mounted solids conveyer  216  connected in fluid flow communication with vibratory feeder  210  and with a reactor  218  (optionally, reactor-mounted solids conveyer  216  is connected in fluid flow communication with reactor  218  via a conduit  220 );   d) closing outlet valve  208 ;   e) opening inlet valve  206 ;   f) charging a quantity of solid particulate biomass material to spool piece  202  through conduit  214  and inlet valve  206  at a pressure P 1 ;   g) closing inlet valve  206 ;   h) pressurizing spool piece  202  to a pressure P 2 , wherein P 2  is greater than P 1 ;   i) opening outlet valve  208  and conveying the quantity of solid particulate biomass material to vibratory feeder  210  via conduit  212 ;   j) closing outlet valve  208 ;   k) conveying the quantity of solid particulate biomass material to reactor-mounted solids conveyer  216  for charging to reactor  218  operated at a pressure at or below P 2 ;   l) opening pressure vent  204  to reduce the pressure in spool piece  202  to P 1 ; and   m) closing pressure vent  204 .       
 
         [0069]    Steps e) through m) are preferably repeated at least once. 
         [0070]    Pressure P 1  can be equal to or less than atmospheric pressure. Pressure P 2  can be greater than atmospheric pressure, and can be greater than 20 psia. 
         [0071]    The process/system  200  can also include a hopper  222  connected in fluid flow communication with a hopper-mounted solids conveyer  224  connected in fluid flow communication with inlet valve  206  via conduit  214 . Solid particulate biomass material can be passed from hopper  222  to spool piece  202  by hopper-mounted solids conveyer  224  and conduit  214 . Hopper-mounted solids conveyer  224  can be a screw feeder. 
         [0072]    The process/system  200  can also include the measurement of the mass flow rate of the solid particulate biomass material to reactor  218 . Hopper  222  and hopper-mounted solids conveyer  224  can rest on a mass measuring device  226  selected from the group consisting of a scale or a load cell, and the mass flow rate can be measured by monitoring the weight of the solid particulate biomass material entering hopper  222  and leaving solids conveyer  224  using mass measuring device  226 . 
         [0073]    The vibratory feeder can comprise a bowl  228  and an outlet spout  230  extending tangentially from said bowl  228 , which are both subjected to vibration. In such embodiment, the outlet valve  208  is connected in fluid flow communication with bowl  228 , and the outlet spout  230  is connected in fluid flow communication with reactor-mounted solids conveyer  216 . The bowl  228  can be an open bowl. Also, the outlet valve  208 , vibratory feeder  210 , and reactor-mounted solids conveyer  216  can be sealed together in a pressure zone. 
         [0074]    As shown in  FIG. 3 , the conveying of the quantity of solid particulate biomass material to vibratory feeder  210  in step i) can comprise charging the quantity of solid particulate biomass material  232  to bowl  228 . The vibration of bowl  228  causes at least a portion of the quantity of solid particulate biomass material  232  to migrate to the edge of bowl  228  and to circumferentially travel about the edge of bowl  228 , forming into a substantially uniform annular thickness of solid particulate biomass material prior to removal from bowl  228  through spout  230 . 
         [0075]    Reactor-mounted solids conveyer  216  can be a screw feeder for conveying the solid particulate biomass into reactor  218 . A pressurized gas stream can be charged to reactor-mounted solids conveyer  216  to provide a constant flow of gas to reactor  218 . Reactor  218  can be a riser reactor, a fluid bed reactor, a moving bed reactor, or a cyclone reactor. 
         [0076]    Vibratory feeder  210  can oscillate at a frequency between 1 and 60 hertz. 
         [0077]    The variation in mass flow rate of the solid particulate biomass material, at steady state conditions, can be within plus or minus about 10%, or within plus or minus about 5%, or within plus or minus about 2.5%. 
         [0078]    A solid inorganic material, which can be a catalyst, can be mixed with the solid particulate biomass material prior to feeding to spool piece ( 102  or  202 ). 
         [0079]    The catalyst can be selected from the group consisting of: a solid base, a clay, an inorganic oxide, an inorganic hydroxide, a zeolite, a supported metal, and combinations thereof. The solid base can be selected from the group consisting of: hydrotalcite; a hydrotalcite-like material; a clay; a layered hydroxy salt; a metal oxide; a metal hydroxide; a mixed metal oxide; or a mixture thereof. 
         [0080]    The catalyst can also be an equilibrium catalyst (“E-cat”) from a fluid catalytic cracking (“FCC”) unit of an oil refinery. The term refers to catalyst material that has, on average, circulated in the FCC unit for a considerable length of time. The term is used to distinguish fresh catalyst, which has not been exposed to the environment of the FCC unit, and which has much greater catalytic activity than the E-cat. The term E-cat also refers to catalyst material that is removed from the FCC unit, to be replaced with fresh catalyst. This spent catalyst is a waste product from oil refineries, and as such abundantly available at low cost. It has been found that the reduced catalytic activity of E-cat is in fact of particular advantage in the pyrolysis process. 
         [0081]    Preferably, the mean particle diameter of the solid particulate biomass material is less than about 500 μm, and more preferably less than about 125 μm. 
         [0082]    The solid particulate biomass material can also be subjected to pretreatment prior to charging to the spool piece ( 102  or  202 ). The pretreatment can comprise a method selected from the group consisting of: a) drying; b) heat treatment in an oxygen-poor or oxygen-free atmosphere; c) solvent explosion; d) mechanical treatment with catalyst particles which can be carried out in a mixer, a mill, a grinder, or a kneader; e) demineralization; f) swelling in an aqueous solvent; g) impregnation of catalytic agents, mineral acids, organic acids, mineral bases; or h) a combination thereof. 
         [0083]    Demineralization may be accomplished by swelling the solid particulate biomass material with an aqueous solvent, and subsequently removing at least part of the aqueous solvent by mechanical action. Examples of suitable mechanical action include kneading, and pressing, such as in a filter press. 
         [0084]    Suitable examples of mechanical action include kneading, grinding, milling, and shredding. In a preferred embodiment the mechanical action is carried out in the presence of a particulate inorganic material, preferably a catalyst for the subsequent pyrolysis reaction. 
         [0085]    The mechanical treatment described above can form an activated feed: a) coated with said catalyst particles, or b) having said catalyst particles embedded therein, or c) both a) and b). 
         [0086]    The term “solvent explosion” refers to a process by which the solid particulate biomass material is contacted with a solvent in its liquid form, under pressure, at a temperature which is above the normal boiling point of the solvent. After the solvent is allowed to penetrate the solid particulate biomass material, the pressure is released precipitously, resulting in a rapid evaporation of the solvent. The resulting pressure build-up in the pores of the solid particulate biomass material can result in a rupturing of the structure of the solid particulate biomass material, making it more susceptible to the subsequent size reduction and pyrolysis reaction. 
         [0087]    The heat treatment can be at a temperature in the range of from 90 to 300° C. In one preferred embodiment the heat treatment is at a temperature in the range of from 90 to 200° C., more preferably from 110 to 160° C. The heat treatment results in a modification of the structure of the solid particulate biomass material, making it significantly more susceptible to mechanical action. 
         [0088]    Examples of suitable materials for impregnation into the biomass include sulfuric acid; ammonia; alkali metal and earth alkaline hydroxides; alkali metal and earth alkaline carbonates; hydrochloric acid; acetic acid; and the like. It should be noted that acetic acid, together with the other lower carboxylic acids (formic acid; propionic acid), although organic materials, are considered inorganic acids in this context. 
         [0089]    While the technology has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the technology as defined by the appended claims.