Dispersion-intensified, coalescence-intensified chemical reactor and method

Abstract

Apparatus for intensifying heterogeneous chemical reactions is described. For the case of liquid-liquid reactions, with drops of a reactant distributed throughout the second continuous reactant, the physical phenomena of drop dispersion (break up) and drop coalescence are identified as the main physical steps affecting reaction rates. A basic flow cell structure is described in which the respective actions of dispersion and coalescence can be greatly intensified through the creation of enhanced body forces and shear flow zones. The basic cell structure can be arranged into pipe flow reactors to suit any production or process requirements. The basic cell structure is equally applicable to gas-liquid reactions with drops of one reactant being conveyed by a moving gas stream.

1 . Apparatus to allow chemical reactions between reactants comprising: 
 a vessel through which the reactants flow;    a baffle structure within the vessel to define at least one flow cell having an interior and at least one inlet to allow flow to pass into the cell interior as a jet to define a dispersion zone for the reactants, and an obstruction spaced from the at least one inlet to redirect the flow and form a coalescence zone for the reactants adjacent the obstruction, and at least one outlet to allow flow to exit the flow cell.    
     
     
         2 . Apparatus as claimed in  claim 1  in which the obstruction is positioned to redirect flow essentially transversely to the flow of the jet such that the obstruction imparts a shearing action to the flow and imparts centrifugal forces to the flow to cause coalescence.  
     
     
         3 . Apparatus as claimed in  claim 1  in which the at least one flow cell comprises a plurality of flow cells with each cell having a first end wall formed with the at least one inlet, a second end wall defining the obstruction formed with the at least one outlet, and side walls extending past the first and second end walls, the second end wall with the at least one outlet of one of the plurality of cells forming the first end wall and inlet of a subsequent, adjacent flow cell.  
     
     
         4 . Apparatus as claimed in  claim 3  in which the side wall in proximity to the inlet defines an additional coalescence zone for the reactants.  
     
     
         5 . Apparatus as claimed in  claim 3  in which the flow cells are arranged to extend along a longitudinal axis of the vessel.  
     
     
         6 . Apparatus as claimed in  claim 5  in which the flow cells are arranged to extend radially from the longitudinal axis of the vessel.  
     
     
         7 . Apparatus as claimed in  claim 1  in which the at least one inlet and outlet comprises a slot.  
     
     
         8 . Apparatus as claimed in  claim 1  in which the at least one inlet and outlet comprises a plurality of discrete openings.  
     
     
         9 . Apparatus as claimed in  claim 1  in which the vessel comprises a hollow body having a longitudinal axis, and the baffle structure is formed from a plurality of elements arranged within the body to define an array of interconnected flow cells that communicate with each other by virtue of the outlet of one flow cell being the inlet of one or more other flow cells.  
     
     
         10 . Apparatus as claimed in  claim 9  in which the plurality of elements includes members of generally T-shaped cross-section, the members being arranged through the hollow body in a repeating pattern to define the array of interconnected flow cells.  
     
     
         11 . Apparatus as claimed in  claim 10  in which the hollow body includes outer side walls and the elements extend between the outer sidewalls to define linear slot inlets and outlets to each flow cell that extend transversely to the longitudinal axis between the side walls.  
     
     
         12 . Apparatus as claimed in  claim 11  in which each member of generally T-shaped cross-section has a head portion and a base portion, and each member is positioned such that the head portion is aligned transversely to the longitudinal axis of the hollow body and the base portion is aligned parallel to the longitudinal axis, the members being arranged in a plurality of parallel rows extending along the longitudinal axis of the hollow body with every second row being offset such that the base portion of one member in an intermediate row extends between the head portions of other members in adjacent rows.  
     
     
         13 . Apparatus as claimed in  claim 9  in which the plurality of elements include a central core element of cylindrical configuration aligned along the longitudinal axis of the hollow body having a plurality of spaced first annular elements extending radially outwardly from the core element and a plurality of spaced second annular elements extending radially inwardly from the hollow body, the first and second annular elements co-operating to define a plurality of interconnected flow cells of annular configuration within an annular space about the central core element.  
     
     
         14 . Apparatus as claimed in  claim 9  in which the plurality of elements includes: 
 a ring cell element comprising an annular cylindrical member having an opening therethrough of a first diameter and an annular disc member having a central opening of a second diameter less than the first diameter positioned against an end of the annular cylindrical member;    a plurality of the ring cell elements of different first diameters being arranged through the hollow body centred about the longitudinal axis in a repeating pattern to define an array of interconnected annular flow cells.    
     
     
         15 . Apparatus as claimed in  claim 1  in which the vessel comprises a hollow body having a longitudinal axis and formed with a plurality of internal baffles extending transversely to the longitudinal axis to restrict axial flow and direct flow radially within the body with an array of flow cells extending between adjacent baffles, the flow cells having inlets and outlets oriented to permit radial flow through the cells.  
     
     
         16 . Apparatus as claimed in  claim 15  in which the internal baffles comprise alternating disc and annular plates spaced along the longitudinal axis of the hollow body to define a series of interrupted central channels for flow extending between pairs of disc plates and a series of interrupted annular perimeter channels for flow extending between pairs of annular plates, the interrupted channels communicating through arrays of flow cells extending between adjacent overlapping plate surfaces in an annular configuration, whereby flow through the hollow body is directed longitudinally along a central channel, radially outwardly through one of the arrays of flow cells, longitudinally along an annular perimeter channel, and radially inwardly through another of the arrays of flow cells.  
     
     
         17 . Apparatus as claimed in  claim 1  including a vessel inlet for introducing at least one of the reactants into the vessel.  
     
     
         18 . Apparatus as claimed in  claim 17  in which the vessel inlet comprises at least one pipe extending radially into the vessel.  
     
     
         19 . Apparatus as claimed in  claim 18  in which the at least one pipe includes openings to introduce the at least one of the reactants into the other reactants which are already flowing through the vessel.  
     
     
         20 . Apparatus as claimed in  claim 19  in which the at least one pipe includes openings along the pipe positioned to introduce the at least one reactant into multiple flow cells.  
     
     
         21 . Apparatus to allow chemical reactions between reactants comprising: 
 a vessel through which the reactants flow including a first reactant distributed as drops throughout a second reactant;    a baffle structure within the vessel to define at least one flow cell having an interior and at least one inlet to allow flow to pass into the cell interior as a jet to define a dispersion zone for the drops, and an obstruction spaced from the at least one inlet to redirect the flow and form a coalescence zone for the drops, and at least one outlet to allow flow to exit the flow cell.    
     
     
         22 . A method for promoting chemical reactions between reactants comprising: 
 delivering the reactants through a vessel in a mixed flow including a first reactant distributed as drops throughout a second reactant; and    controlling the flow through the vessel to create a flow path that alternates between dispersing the drops and coalescing the drops to increase the reaction rate.    
     
     
         23 . The method of  claim 22  in which the step of controlling the flow includes forming the flow into a jet to disperse the drops.  
     
     
         24 . The method of  claim 23  in which the step of controlling the flow includes redirecting the flow past an obstruction to coalesce the drops due to shear zone forces and intensified body forces.  
     
     
         25 . The method of  claim 22  in which the step of controlling the flow includes directing the flow through at least one flow cell in the vessel, the flow cell having at least one inlet to allow flow to pass through the inlet as a jet to define a dispersion zone for the drops, and an obstruction spaced from the at least one inlet to redirect the flow and form a coalescence zone for the drops within an interior of the flow cell adjacent the obstruction, and at least one outlet adjacent the obstruction to allow flow to exit the flow cell.  
     
     
         26 . The method of  claim 25  in which the at least one flow cell is arranged in an array of a plurality of flow cells within the vessel positioned to intercept and control flow through the vessel.  
     
     
         27 . The method of  claim 25  including a side wall in proximity to the jet to provide an additional zone of coalescence of the drops due to fluid shear forces at the side wall.  
     
     
         28 . The method of  claim 22  in which the first and second reactants are liquids, with the drops of the first liquid reactant being distributed throughout the second reactant  
     
     
         29 . The method of  claim 22  in which the first reactant is a liquid, and the second reactant is a moving gas stream.  
     
     
         30 . Apparatus to allow chemical reactions between reactants comprising: 
 a vessel through which the reactants flow including a first reactant distributed as drops throughout a second reactant; and    means for controlling the flow of reactants through the vessel to intensify the dispersion and coalescence of the drops comprising:    means for creating a zone of dispersion for the drops; and    means for creating a zone of coalescence for the drops.    
     
     
         31 . Apparatus as claimed in  claim 30  in which the means for controlling the flow of reactants through the vessel comprises a baffle structure within the vessel to define at least one flow cell having an interior, the flow cell being formed with the means for creating a zone of dispersion for the drops and means for creating a zone of coalescence for the drops.  
     
     
         32 . Apparatus as claimed in  claim 31  in which the means for creating a zone of dispersion comprises at least one inlet to the flow cell shaped to create a jet flow into the cell interior.  
     
     
         33 . Apparatus as claimed in  claim 32  in which the means for creating a zone of coalescence comprises an obstruction spaced from the at least one inlet and extending transverse to the flow.  
     
     
         34 . Apparatus as claimed in  claim 31  including at least one outlet to allow flow to exit the flow cell.  
     
     
         35 . Apparatus as claimed in  claim 32  in which the means for creating a zone of coalescence comprises a surface in proximity to the jet.