Abstract:
An apparatus and method for providing a hydrogen rich gas stream at a high pressure for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams are disclosed in the present invention. As the pressure of gaseous hydrogen is increased, the temperature of the gaseous hydrogen also increases due to the heat of compression. The apparatus and method of the present invention utilize localized cooling via a vortex tube to cool the gaseous hydrogen caused by the increase in pressure.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to providing a hydrogen rich gas stream at a high pressure for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams and in particular to an apparatus and method for dispensing a hydrogen rich gas stream at 700 bar for use by hydrogen vehicles. 
     BACKGROUND OF THE INVENTION 
     Hydrogen is utilized in a wide variety of industries ranging from aerospace to food production to oil and gas production and refining. Hydrogen is used in these industries as a propellant, an atmosphere, a carrier gas, a diluents gas, a fuel component for combustion reactions, a fuel for fuel cells, as well as a reducing agent in numerous chemical reactions and processes. In addition, hydrogen is being considered as an alternative fuel for power generation because it is renewable, abundant, efficient, and unlike other alternatives, produces zero emissions. While there is wide-spread consumption of hydrogen and great potential for even more, a disadvantage which inhibits further increases in hydrogen consumption is the absence of a hydrogen infrastructure to provide widespread generation, storage and distribution. 
     One way to overcome this difficulty is through the operation of hydrogen energy stations. At hydrogen energy stations, hydrogen generators such as reformers are used to convert hydrocarbons to a hydrogen rich gas stream. Hydrocarbon-based fuels, such as natural gas, LPG, gasoline, and diesel, require conversion processes to be used as fuel sources for most fuel cells. Current art uses multi-step processes combining an initial conversion process with several clean-up processes. The initial process is most often steam reforming (SR), autothermal reforming (ATR), catalytic partial oxidation (CPOX), or non-catalytic partial oxidation (POX), or combinations thereof. The clean-up processes are usually comprised of a combination of desulphurization, high temperature water-gas shift, low temperature water-gas shift, selective CO oxidation, selective CO methanation or combinations thereof. Alternative processes for recovering a purified hydrogen-rich reformate include the use of hydrogen selective membrane reactors and filters. The gaseous hydrogen is then stored in stationary storage vessels at the hydrogen energy stations to provide inventory to fuel hydrogen vehicles. 
     Currently, gaseous hydrogen is typically dispensed to hydrogen vehicles at a pressure of 350 bar. However, in order to extend the range of hydrogen vehicles, it is desirable to increase the storage density of gaseous hydrogen in hydrogen vehicles. Therefore, it is desirable to dispense gaseous hydrogen to hydrogen vehicles at an increased pressure of 700 bar. This increase in pressure will require cooling of the gaseous hydrogen during dispensing as the temperature of the gaseous hydrogen will increase due to the heat of compression. Conventional heat transfer of this fast flowing stream would require a very large heat exchanger. In addition, the mechanical cooler for this heat exchanger would have to be located remotely from the dispenser or be constructed to meet Class 1, Division 2, Group B electrical code as defined by OSHA regulations. 
     In addition to increasing the storage density of gaseous hydrogen in hydrogen vehicles, it is also desirable to use cold gaseous hydrogen (“cryocooled”) storage tanks to increase the amount of gaseous hydrogen stored per unit volume versus conventional stationary storage tanks while avoiding the energy penalties associated with hydrogen liquefaction. The cold gaseous hydrogen (“cryocooled”) storage tanks store gaseous hydrogen at a high pressure. 
     The present invention addresses these challenges by disclosing an apparatus and method for providing a hydrogen rich gas stream at a high pressure for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams. 
     SUMMARY OF THE INVENTION 
     In the present invention, an apparatus and method for providing a hydrogen rich gas stream at a high pressure for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams are disclosed. As the pressure of gaseous hydrogen is increased, the temperature of the gaseous hydrogen also increases due to the heat of compression. The apparatus and method of the present invention utilize localized cooling via a vortex tube to cool the gaseous hydrogen caused by the increase in pressure. In the present invention, the gaseous hydrogen stream is first introduced into a vortex tube which separates the compressed hydrogen into cold and hot streams. 
     In one embodiment, the cold hydrogen stream may then be dispensed to a hydrogen vehicle while the hot hydrogen stream may be routed to a surge tank for subsequent recompression, storage, and later re-dispensing. The apparatus of the present invention can be used to dispense gaseous hydrogen to hydrogen vehicles at a pressure of 700 bar. In addition, the apparatus of the present invention could be used to dispense gaseous hydrogen to hydrogen vehicles at some intermediate pressure between the current dispensing pressure of 350 bar and the current target of 700 bar. 
     In another embodiment, the cold hydrogen stream may then be used to fill a cold gaseous hydrogen (“cryocooled”) storage tank while the hot hydrogen stream may be routed to a surge tank for subsequent recompression, storage, and later re-dispensing. 
     The use of a vortex tube allows not only for the localized cooling of the gaseous hydrogen but also allows for the control of the sizing of the hydrogen energy station when the size (footprint) of the hydrogen energy station must be considered. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The description is presented with reference to the accompanying figures in which: 
         FIG. 1  depicts one embodiment of the apparatus of the present invention for dispensing gaseous hydrogen at 700 bar for use by hydrogen vehicles. 
         FIG. 1A  depicts another embodiment of the apparatus of the present invention for dispensing gaseous hydrogen at 700 bar for use by hydrogen vehicles. 
         FIG. 2  depicts another embodiment of the apparatus of the present invention for filling a high-pressure cold gaseous hydrogen (“cryocooled”) storage tank. 
         FIG. 3  depicts an example of the vortex tube of the apparatus of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention discloses an apparatus and method for providing a hydrogen rich gas stream at a high pressure for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams. 
     With reference to  FIG. 1 ,  FIG. 1  depicts one embodiment of the apparatus and method of the present invention for dispensing gaseous hydrogen at 700 bar for use by hydrogen vehicles.  FIG. 1  depicts a hydrogen energy station  100  for generating, storing, and dispensing gaseous hydrogen for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams. First, the gaseous hydrogen is generated (not illustrated) at the hydrogen station  100  and stored in at least one stationary storage tank  101 . In addition, the gaseous hydrogen may be generated off-site and transported to the hydrogen energy station  100 . 
     Prior to dispensing the gaseous hydrogen at a pressure of 700 bar to a hydrogen vehicle  106 , the gaseous hydrogen is introduced into a least one vortex tube  102 . In the vortex tube  102 , the gaseous hydrogen is separated into a cold hydrogen stream  103  and a hot hydrogen stream  104 . As is known in the art, vortex tubes utilize vortex action to separate compressed air into a cold stream and a hot stream. For example, Exair Corporation and ITW Air Management manufactures products such as vortex tubes. The present invention adapts this compressed air technology, vortex tubes, for use at a hydrogen energy station. 
     An example of the vortex tube  300  of the apparatus of the present invention is depicted in  FIG. 3 . Gaseous hydrogen  301  enters the vortex tube  300  and is separated into at least one cold hydrogen stream  302  and at least one hot hydrogen stream  303 . 
     Fluid (air) that rotates around an axis (like a tornado) is called a vortex. A Vortex Tube creates cold air and hot air by forcing compressed air through a generation chamber which spins the air centrifugally along the inner walls of the Tube at a high rate of speed (1,000,000 RPM) toward the control valve. A percentage of the hot, high-speed air is permitted to exit at the control valve. The remainder of the (now slower) air stream is forced to counterflow up through the center of the high-speed air stream, giving up heat, through the center of the generation chamber finally exiting through the opposite end as extremely cold air. Vortex tubes generate temperatures down to 100° F. below inlet air temperature. A control valve located in the hot exhaust end can be used to adjust the temperature drop and rise for all Vortex Tubes. 
     The cold hydrogen stream  103  is routed to a dispenser  105  and dispensed to a hydrogen vehicle or other devices requiring hydrogen rich feed stream  106 . The hot hydrogen stream  104  is routed to a surge tank  107 . The hot hydrogen stream  104  from the surge tank  107  is then recompressed via a compressor  108  and routed back to at least one stationary storage tank  101  for later re-dispensing. 
     With reference to  FIG. 1A ,  FIG. 1A  depicts another embodiment of the apparatus and method of the present invention for dispensing gaseous hydrogen at 700 bar for use by hydrogen vehicles.  FIG. 1A  depicts a hydrogen energy station  150  for generating, storing, and dispensing gaseous hydrogen for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams. First, the gaseous hydrogen is generated (not illustrated) at the hydrogen station  150  and stored in at least one stationary storage tank  151 . In addition, the gaseous hydrogen may be generated off-site and transported to the hydrogen energy station  150 . 
     Prior to dispensing the gaseous hydrogen at a pressure of 700 bar to a hydrogen vehicle  156 , the gaseous hydrogen is first introduced into a dispenser  155 . Following the dispenser, the gaseous hydrogen is introduced into at least one vortex tube  152 . In the vortex tube  152 , the gaseous hydrogen is separated into a cold hydrogen stream  153  and a hot hydrogen stream  154 . 
     The hot hydrogen stream  154  is routed to a surge tank  157 . The hot hydrogen stream  154  from the surge tank  157  is then recompressed via a compressor  158  and routed back to at least one stationary storage tank  151  for later re-dispensing. The cold hydrogen stream  153  is dispensed to a hydrogen vehicle  156  or other devices requiring hydrogen rich feed stream. In order to determine the amount of gaseous hydrogen is dispensed to the vehicle  156  a meter (not illustrated) must be incorporated into or placed after the vortex tube  152 . 
     With reference to  FIG. 2 ,  FIG. 2  depicts another embodiment of the apparatus of the present invention for filling a high-pressure cryocooled storage tank.  FIG. 2  depicts a hydrogen energy station  200  for generating, storing, and dispensing gaseous hydrogen for use by hydrogen vehicles or other devices requiring hydrogen rich feed streams. First, the gaseous hydrogen is generated (not illustrated) at the hydrogen station  200  and stored in at least one stationary storage tank  201 . In addition, the gaseous hydrogen may be generated off-site and transported to the hydrogen energy station  200 . 
     Prior to filling at least one cold gaseous hydrogen (“cryocooled”) storage tank  205 , the gaseous hydrogen is introduced into a least one vortex tube  202 . In the vortex tube  202 , the gaseous hydrogen is separated into a cold hydrogen stream  203  and a hot hydrogen stream  204 . 
     The cold hydrogen stream  203  is routed to the cold gaseous hydrogen (“cryocooled”) storage tank  205 . The hot hydrogen stream  204  is routed to a surge tank  206 . The hot hydrogen stream  204  from the surge tank  206  is then recompressed via a compressor  207  and routed back to at least one stationary storage tank  201 . 
     While the methods of this invention have been described in terms of preferred or illustrative embodiments, it will be apparent to those of skill in the art that variations may be applied to the process described herein without departing from the concept and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the scope and concept of the invention as it is set out in the following claims.