Hydrogen from ammonia
AssigneeErgenics, Inc.
InventorRobert W. Meyerhoff
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Abstract
A reactor system for production of hydrogen by use of a hydride bed acting upon dissociated ammonia is formed of coaxial annular shells. A central one of the shells includes a hydride bed composed of pelletized material supported on a screen. Inner and outer shells contiguous to the central shell conduct fluid for heat exchange with the hydride bed. Inner and outer diameter of the central shell differ in length by an amount inversely proportional to the square root of the heat adsorption characteristic of the hydride.
Claims10
A reactor system for the delivery of between 28 to 2800 cu m/day of hydrogen on-site using hydridable materials to separate hydrogen from a dissociated ammonia stream comprising at least one flow-through reactor, said reactor comprising an annularly-shaped hydride bed, means defining an inner heat-exchange shell and means defining an outer heat exchange shell, wherein said hydride bed is located coaxially to and between said inner shell and said outer shell;
- means to provide uniform gas flow with low pressure drop through the hydride bed;
- means for introducing the dissociated ammonia feed stream to and means for permitting the flow of waste gas or hydrogen from the hydride bed, the hydride bed comprising a hydridable material which exothermally and selectively absorbs hydrogen and endothermally desorbs hydrogen, said heat exchanger shells being provided with circulating fluid and means to supply and extract heat therefrom, whereby said reactor when charged with the dissociated ammonia stream, is at any time capable of delivering hydrogen through desorption of hydrogen from hydridable material contained therein;
- and wherein
- said hydride bed has an inner diameter and an outer diameter, wherein the difference in size of the two diameters differs by an amount which is inversely proportional to the square root of a heat of absorption characteristic of a hydride in the hydride bed, and wherein the performance of said reactor system is predicted semi-quantitively by the equation:
- F.sup.2 =(D.sub.1 +D.sub.2).sup.2 L.sup.2 .pi..sup.2 K2W.DELTA.T/.DELTA.Ht
- where
- F=Hydrogen flow rate, moles/sec.
- D.sub.1 =Diameter of inner wall of the hydride shell, cm
- D.sub.2 =Diameter of outer wall of the hydride shell, cm
- L=Length of hydride bed, cm
- .pi.=Constant=3.14
- K=Thermal conductivity of hydride bed, cal.multidot.sec.sup.-1 .multidot.cm.sup.-1 .multidot.K.sup.-1
- .rho.=Density of hydride bed, g/cc
- .DELTA.T=Temperature difference between reactor wall and mid-point of the hydride bed, .degree.Kelvin
- .DELTA.H=Heat of adsorption of hydride, cal/mole
- t=Charging or discharge time, sec. and D.sub.2 is related to D.sub.1 by the relationship
- D.sub.2 =D.sub.1 +8[Kt.DELTA.T/.DELTA.H.rho.W].sup.1/2
- where W=Grams of hydrogen per gram of hydride.
A reactor system for the delivery of between 28 to 2800 cu m/day of hydrogen comprising at least one flow-through reactor (10), said reactor comprising an insulated cylindrical shell (11), a cylindrical housing (12) within the shell, hydridable material disposed as a hydride bed (13) in the cylindrical housing (12), an inner heat exchange shell (14) and an outer heat exchange shell (15) through which a heat exchange medium can be circulated, said cylindrical housing (12) being located coaxially to and between said inner heat exchange shell (14) and said outer heat exchange shell (15), gas inlet means (17) for delivery of dissociated ammonia to the hydridable material, means (18) to control the inlet flow, outlet means (19) for the passage of waste gas or hydrogen from the hydride, means (20) to control the outlet flow through the outlet means, heat exchanger inlet and outlet means (21) for entry and exit, respectively, of heat exchange medium to and from outer heat exchange shell (15) and heat exchanger inlet and outlet means (23) and (24) for entry and exit respectively of heat exchange medium to and from the inner heat exchange shell (14);
- and wherein
- said hydride bed has a generally annular shape having an inner diameter and an outer diameter, with the difference in size between said inner diameter and said outer diameter being inversely proportional to the square root of the heat of absorption characteristic of the hydridable material of said hydride bed and wherein the performance of said reactor system is predicted semi-quantitatively by the equation:
- F=(D.sub.1 +D.sub.2).sup.2 2 L.sup.2 .pi.K.rho..DELTA.T/.DELTA.Ht
- where
- F=Hydrogen flow rate, moles/sec.
- D.sub.1 =Diameter of inner wall of the hydride shell, cm
- D.sub.2 =Diameter of outer wall of the hydride shell, cm
- L=Length of hydride bed, cm
- .pi.=Constant=3.14
- K=Thermal conductivity of hydride bed, cal.multidot.sec.sup.-1 .multidot.cm.sup.-1 .multidot.K.sup.-1
- .rho.=Density of hydride bed, g/cc
- .DELTA.T=Temperature difference between reactor wall and mid-point of the hydride bed, .degree.Kelvin
- .DELTA.H=Heat of adsorption of hydride, cal/mole
- t=Charging or discharge time, sec. and D.sub.2 is related to D.sub.1 by the relationship
- D.sub.2 =D.sub.1 =8[Kt.DELTA.T/.DELTA.H.rho.W].sup.1/2
- where W=Moles of hydrogen per gram of hydride.
Dependencies are inferred from the claim text.