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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 co

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.

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1. 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 hea

1. 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: ##EQU##F 2 =(D 1 +D 2 ) 2 L 2 π 2 K2WΔT/ΔHt where F=Hydrogen flow rate, moles/sec. D 1 =Diameter of inner wall of the hydride shell, cm D 2 =Diameter of outer wall of the hydride shell, cm L=Length of hydride bed, cm π=Constant=3.14 K=Thermal conductivity of hydride bed, cal·sec -1 ·cm -1 ·K -1 ρ=Density of hydride bed, g/cc ΔT=Temperature difference between reactor wall and mid-point of the hydride bed, °Kelvin ΔH=Heat of adsorption of hydride, cal/mole t=Charging or discharge time, sec. and D 2 is related to D 1 by the relationship ##EQU##D 2 =D 1 +8[KtΔT/ΔHρW] 1/2 where W=Grams of hydrogen per gram of hydride. 2. A reactor system of claim 1, wherein the system comprises at least two flow-through reactors capable of operating in tandem, and at a pre-determined time after initial absorption in the first reactor, at least one of the reactors is in the desorption mode, whereby a continuous supply of hydrogen is effected. 3. A reactor system of claim 1, wherein the hydridable material is characterized by an ambient temperature-pressure plateau of less than one atmosphere, and in that said hydride is not subject to poisoning by the ammonia dissociation stream and not subject to nitride formation under normal operating conditions of the system. 4. A reactor system of claim 1, wherein the hydridable material comprises at least one composition selected from: (a) elements selected from the group consisting of magnesium, titanium, vanadium and niobium; (b) compositions definable by the formula AB x where A comprises at least one element selected from the group consisting of rare earth metals (including yttrium) and calcium and B comprises at least one metal selected from the group nickel and cobalt, and x is a number between 3 and 8: or (c) compositions definable by the formula AD m where A comprises at least one element selected from the group rare earth metals (including Yttrium) and D comprises at least one composition selected from the group nickel, cobalt and a mixture thereof with one or more of the elements iron, copper, and manganese, and m satisfies the equation 1/3≤m<3. 5. A reactor system of claim 1, wherein the hydridable material is retained in a porous plastic. 6. A reactor system of claim 1, wherein the hydridable material is used in combination with a ballast material. 7. A reactor system of claim 1, wherein the hydridable material comprises at least one of the compositions selected from group Fe 0 .8 Ni 0 .2 Ti, ZrCr 0 .5 Fe 1 .5, LaNi 4 .7 Al 0 .3, MNi 4 Al (where M is mischmetal), LaNi 4 Cu, and La 1-x Ca x Ni 5 (where x≤0.5). 8. A reactor system of claim 1, wherein the hydridable material comprises LaNi 4 .7 Al 0 .3. 9. 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: ##EQU##F=(D 1 +D 2 ) 2 2 L 2 πKρΔT/ΔHt where F=Hydrogen flow rate, moles/sec. D 1 =Diameter of inner wall of the hydride shell, cm D 2 =Diameter of outer wall of the hydride shell, cm L=Length of hydride bed, cm π=Constant=3.14 K=Thermal conductivity of hydride bed, cal·sec -1 ·cm -1 ·K -1 ρ=Density of hydride bed, g/cc ΔT=Temperature difference between reactor wall and mid-point of the hydride bed, °Kelvin ΔH=Heat of adsorption of hydride, cal/mole t=Charging or discharge time, sec. and D 2 is related to D 1 by the relationship ##EQU##D 2 =D 1 =8[KtΔT/ΔHρW] 1/2 where W=Moles of hydrogen per gram of hydride. 10. A reactor system according to claim 9, wherein at least two flow-through reactors are used, said reactors being capable of operating in tandem.