WO2017127022A1

WO2017127022A1 - Portable hydrogen generator

Info

Publication number: WO2017127022A1
Application number: PCT/SG2017/050026
Authority: WO
Inventors: Man Yun Michelle CHENG; Fook Heng HO; De Tao Francis YAP; Yao Wei Alfred CHUA; Cheng Hok Aw; Chuan En Andrew ONG
Original assignee: Advanced Material Engineering Pte Ltd
Current assignee: ST Engineering Advanced Material Engineering Pte Ltd
Priority date: 2016-01-18
Filing date: 2017-01-18
Publication date: 2017-07-27
Anticipated expiration: 2018-07-18

Abstract

The present invention provides portable hydrogen generators (100, l00a-l00e, 500) with portable cartridges (110, 510) containing a hydride and/or borohydride. The borohydride (132,132a) and hydride (134,134a) can be configured in a two-stage configuration or a three-stage configuration with an additional Li hydride (136); the hydride or borohydride can also be powder (530) disposed in a multi-cellular cartridge (510). Water for hydrolysis of the hydride/borohydride is supplied as mist through a mist nozzle (182, 182a), as steam when the water supply is internally heated by exothermic reaction after an initial hydrolysis of has taken place, or as stoichiometric doses releasable by puncturing a bladder (526) or by activating a valve connected to a water receptacle (526a) disposed inside each reaction chamber.

Description

Portable Hydrogen Generator

Field of Invention

[001] The present invention relates to portable hydrogen generators that are compact and lightweight for a person to carry. Each hydrogen generator is configured as a cartridge that is replaceable when the hydrogen content is depleted. The hydrogen generators are suitable for use with a hydrogen fuel cell.

Background

[002] Hydrogen fuel cell is a promising alternative to a power source that burns hydrocarbon; it may be a solution to reduce global warming and pollution. With a proton exchange membrane, hydrogen is ionised on one side of the exchange membrane to supply electrons to perform an external work whilst oxygen ions are recombined with hydrogen ions at an opposite side of the membrane; the by-products are simply heat and water. An obstacle in the use of a hydrogen fuel cell includes the separate production and storage of gases of hydrogen and oxygen. A solution to storing hydrogen gas is to produce hydrogen on-demand; in other words, hydrogen is generated in a quantity as required by a fuel cell and no excess hydrogen is stored.

[003] Known hydrogen on-demand systems rely on hydrolysis of a chemical or metal hydride/borohydride. An advantage of a chemical or metal hydride/borohydride is the high hydrogen content; for eg., one mole of sodium borohydride NaBH4 is hydro lysed with two moles of water to generate four moles of hydrogen gas. A difficulty lays in the precise control of delivering water for hydrolysis of a hydride; if a solid hydride, for eg. borohydride, is used, the by-product of sodium metaborate retards diffusion of water into the borohydride. Another difficulty is in the temperature control to start and maintain the reaction kinetics.

[004] It can thus be seen that there exists a need for other configurations of portable hydrogen generators. Summary

[005] The following presents a simplified summary to provide a basic understanding of the present invention. This summary is not an extensive overview of the invention, and is not intended to identify key features of the invention. Rather, it is to present some of the inventive concepts of this invention in a generalised form as a prelude to the detailed description that is to follow.

[006] The present invention seeks to provide lightweight, compact and portable hydrogen generators in which cartridges can be replaced. In one embodiment, hydrogen is produced on-demand by controlling the amount of water for hydrolyzing a borohydride or hydride. In another embodiment, hydrogen is produced on-demand by hydrolyzing amounts of a borohydride or hydride with stoichiometric amounts of water in a multi-cellular cartridge.

[007] In one embodiment, the present invention provides a portable hydrogen generator that uses a two-stage hydride. The hydrogen generator is defined in claims 1-8, 10-14 and 23- 24.

[008] In another embodiment, the present invention provides a portable hydrogen generator that uses a three-stage hydride. The hydrogen generator is defined in claims 1, 9, 15 and 23-24.

[009] In another embodiment, the present invention uses a portable hydrogen generator, which provides multi-cellular reaction chambers and a stoichiometric amount of water associated with each reaction chamber is stored in a bladder. The hydrogen generator is defined in claims 1 and 16-24.

[0010] In another embodiment, the present invention provides a process for generating hydrogen according to a hydrogen demand. The process is defined in claims 25-31.

Brief Description of the Drawings

[0011] This invention will be described by way of non-limiting embodiments of the present invention, with reference to the accompanying drawings, in which: [0012] FIG. 1A illustrates a sectional view of a two-stage hydrogen generator according to an embodiment of the present invention; FIG. IB illustrates a perforated mist delivery tube for use in FIG. 1A; FIG. 1C illustrates a variation of FIG. 1A by using an air assisted mist nozzle; FIG. ID illustrates a variation of FIG. 1A in which the water delivery tube is spirally coiled for internal heating by exothermic reaction; FIG. IE illustrates a variation of FIG. ID in which the water delivery tube is steam permeable;

[0013] FIG. 2 illustrates a sectional view of a two-stage hydrogen generator according to another embodiment of the present invention;

[0014] FIG. 3 illustrates a sectional view of a three-stage hydrogen generator according to another embodiment of the present invention;

[0015] FIG. 4 illustrates a control diagram for operating the above hydrogen generator and hydrogen fuel cell;

[0016] FIG. 5 A illustrates a hydrogen generator coupled to a fuel cell; FIG. 5B-5C illustrate the hydrogen generator shown in FIG. 5A; FIG. 5D illustrates a bladder holder shown in FIGs. 5B-5C; FIG.5E illustrate a solenoid operated plunger; FIG. 5F illustrates a vertical slide connection between the hydrogen generator and fuel cell; FIG. 5G illustrates hydrogen supply connections on top of the cap of the hydrogen generator, whilst FIG. 5H illustrates another hydrogen supply connections in the cap shown in FIG.s 5A-5C;

[0017] FIGs. 6A-6C illustrate two bladder puncturing apparatuses for use with the hydrogen generator shown in FIGs. 5A-5C; and

[0018] FIG. 7A illustrates a control diagram for operating the hydrogen generator shown in FIG. 5A; FIG. 7B illustrates the operating temperature envelop whilst FIG. 7C illustrates the amount of hydrogen produced. Detailed Description

[0019] One or more specific and alternative embodiments of the present invention will now be described with reference to the attached drawings. It shall be apparent to one skilled in the art, however, that this invention may be practised without such specific details. Some of the details may not be described at length so as not to obscure the invention.

[0020] FIG. 1A shows a sectional view of a two-stage hydrogen generator 100 according to an embodiment of the present invention. As shown in FIG. 1 A, the hydrogen generator 100 includes an insulated, re-sealable cartridge or cylinder 1 10, a tubular hydride 130, a mist nozzle 182 and a mist delivery tube 150. The cartridge or cylinder 110 has a closed bottom 1 13 and a closure cap 114. When the hydrogen generator 100 is assembled, the cartridge cylinder 110 co-axially encloses the tubular hydride 130 and the mist delivery tube 150 in an air-tight reaction chamber 1 11. The outside surfaces of the cartridge 110 and cap 114 are covered by a thermal insulator 112, such as polyurethane, fiberglass wool, rockwool, alumina silicate fibres, aerogel and so on. On an outside face of the cap 114 are located a water inlet port 180 which is connected to a water supply tube 181 and a hydrogen outlet port 190. On the inside face of the cap 114, the mist nozzle 182 is connected inline with the water inlet port 180, whilst at the hydrogen outlet port 190, an annular filter member 192 is fitted on the inside face of the cap 1 14. It is possible that two or even more than two hydrogen outlet ports 190 are provided.

[0021] The cartridge cylinder 1 10 is made of a high temperature polymer, for eg., to withstand a temperature of about 200 degC. Preferably, the polymer has a high glass transition temperature. Suitable polymers for making the casing cylinder 1 10 are: polyimide (PI), poly amide imide (PAI) and polyethersulfone (PES). The cartridge cylinder 1 10 has external dimensions of about 8-10 cm long and about 6-8 cm diameter. Preferably, the cap 1 14 is connected to a mouth of the cartridge cylinder 110 by a screw thread connection and the reaction chamber 1 11 is kept air-tight by an O ring or seal 118 disposed between the mouth of the cartridge cylinder and the cap 114. Preferably, the inside face of the cap 1 14 has a co-axial circular collar 116a and a corresponding circular collar 1 16b at the bottom of the reaction chamber 111 to locate the mist delivery tube 150 near the centre of the reaction chamber 111. [0022] As shown in FIG. IB, the mist delivery tube 150 is made of a thin steel or aluminum tube with perforations 152. Preferably, the perforations 152 are about 1 mm diameter and are axially inclined. It is possible that the perforations 152 are made on a sheet metal before the sheet metal is rolled into a tube. In use, the mist delivery tube 150 is installed so that the perforations 152 are upwardly inclined and the lowest row of perforations is a predetermined distance L of about 1 cm from the bottom end of the mist delivery tube. In use, a sponge 160 is disposed in the space at the bottom end of the mist delivery tube 110, as seen in FIG. 1A. When the inside of the mist delivery tube 150 is saturated, some of the mist tends to accumulate as water droplets and the upwardly inclined perforations 152 cause the water droplets to drip down and be absorbed by the sponge 160. After the hydrogen capacity of the tubular hydride 130 is used up, the hydride 130 is replaced and at the same time the sponge 160 is replaced or squeezed to remove the absorbed water. By absorbing the water condensate at the bottom of the tubular hydride 130, unintended surges of hydrolyzing of the hydride and, thus, surges of hydrogen generation become preventable.

[0023] The tubular hydride 130 is porous. As seen in FIG. 1A, the tubular hydride 130 is composed of an inner cylinder 132 of a borohydride (such as sodium borohydride) and an outer cylinder 134 of hydride (such as Mg hydride). In one embodiment, the cylinder 132 has an inside dimension, for example of substantially 2 cm diameter, to fit with the mist delivery tube 150 and an outer dimension, for example of substantially 3-4 cm diameter, whilst the outer cylinder 134 has an inside dimension, for example of 3-4 cm diameter, to fit with the inner cylinder 132 and an outer dimension, for example of substantially 5-6 cm diameter. The tubular hydride 130 has a porosity of about 10-50%. The borohydride 132 is wetted by water mist entering the pores by capillary action followed by wetting of the hydride 134; the hydrogen gas produced by hydrolysis of both the borohydride and hydride diffuses through the pores; with this controlled radial wetting of the tubular hydride, hydrogen gas diffuses both outwardly and upwardly through the open pores; hydrogen gas being light then collects at the top of the reaction chamber 11 1 and is released to the exterior through the hydrogen port 190. Preferably, the hydrogen gas passes through a filter 192 before passing through the hydrogen port 190. In one embodiment, the inner hydride cylinder 132, the outer hydride cylinder 134 and mist delivery tube 150 are slide fit to each other; in another embodiment, the inner and outer hydride cylinders are integrally formed; it is also possible for the inner hydride cylinder 132 to be integrally formed with the mist delivery tube 150. These cylindrical designs of the tubular hydride 130, 132, 134 allow quick and easy assembly and replacement.

[0024] In the above tubular hydride 130, the borohydride and hydride compose about 50- 50% ratio. It is possible that the composition ratio ranges from about 10% to about 90%.

[0025] FIG. 1C shows a variation 100a of the hydrogen generator shown in FIG. 1A. This hydrogen generator 100a is similar to the above hydrogen generator 100 except that an air- assisted mist nozzle 182a is used. A compressed air tube 171 is thus connected to the air- assisted mist nozzle 182a from a miniature air pump 480 as shown in FIG. 4. The compressed air may be supplied in pulses in coordination with a water supply pump 414 connected to the water supply tube 181.

[0026] FIG. ID shows a variation 100b of the hydrogen generator shown in FIG. 1A. This hydrogen generator 100b is similar to the above hydrogen generator 100 except that the water supply tube 181 goes down to the bottom of the reaction chamber and rises as upward spiral coils around the tubular hydride 130. After an initial hydrolysis of the borohydride/hydride, water in the supply tube 181 is internally heated by exothermic reaction and the outlet of the nozzle 182 is substantially steam or steam and vapour. Preferably, as shown in FIG. ID, internal ducts 184 are formed in the cap 114 to fluidly connect the end of the water supply tube 181 to the nozzle 182.

[0027] FIG. IE shows a variation 100c of the hydrogen generator shown in FIG. ID. In this hydrogen generator 100c, the water supply coils 181a inside the reaction chamber 1 1 1 is steam-permeable. After an initial hydrolysis of the borohydride/hydride, water in the supply coils 181a is turned into steam, which is then released through both the wall of the water supply coils 181a and the mist nozzle 182. In one embodiment, the steam permeable supply coil is made of PTFE (Teflon).

[0028] FIG. 2 shows a two-stage hydrogen generator 1 OOd according to another embodiment of the present invention. The reaction chamber 1 11 of the hydrogen generator lOOd is similar to that of the above hydrogen generator 100, 100a- 100c except that a mist delivery tube 150a is now disposed to surround a tubular hydride 130a, which is located by collars 1 16c, 116d. In contrast with the above embodiment, the tubular hydride 130a is now composed of an outer cylinder of borohydride 132a and an inner cylinder of hydride 134a. Consistent with the above disclosure, ratio of the borohydride to hydride ranges from about 10:90 % to about 50:50 %. The outside diameter of the mist delivery tube 150a is smaller than the inside diameter of the reaction chamber 1 1 1 so that there is an annular space around the mist delivery tube 150a. The water supply tube 181 terminates as a circular mist spray ring 184 disposed in the annular space near the inside of the cap 114. The circular mist spray ring 184 has a plurality of tiny holes or groups of tiny holes for turning water into mist for hydrolyzing the tubular hydride 130a. Like in the above embodiment, a sponge 160a is disposed in the annular space around the bottom of the mist delivery tube 150a to absorb water condensate that has dripped down the mist delivery tube 150a. Consistent with the above description, water mist diffuses radially through the pores of the tubular hydride 130a and hydrolysis of the borohydride 132a heats up the hydrogen generator l OOd to about 60-120 degC. After a first stage hydrolysis of the borohydride 132a, a second stage hydrolysis of the hydride 134a proceeds at a higher temperature of about 120-250 degC. The cartridge cylinder 1 10 being made of high temperature polymer together with the thermal insulator 112 help to reduce heat conduction to the exterior surface of the hydrogen generator lOOd to about 60-70 degC.

[0029] In the above embodiments, the tubular hydride does not contain an acid constituent. In a further embodiment, the tubular hydride 130 contains dry acid particles; suitable dry acid includes particles of boric, citric, tartaric or phosphoric acid, or a mixture, in an amount of up to about 1 : 1 molar hydrogen content of the tubular hydride. Advantages of this embodiment are increasing the hydrogen generating capacity and reducing the cost of using noble metal catalysts.

[0030] FIG. 3 shows a hydrogen generator lOOe according to yet another embodiment of the present invention. The hydrogen generator lOOe is similar to the hydrogen generator shown in FIG. IE except that the tubular hydride is now composed of three compositions. In FIG. 3, the tubular hydride 130b is composed of a cylinder of hydride 134b around a cylinder of borohydride 132b and an outer cylinder of lithium hydride 136. In this embodiment, water is initially supplied as mist from the mist nozzle 182 to an inside of the tubular hydride 130b, and after the hydrogen generator lOOe is heated up, water is then supplied as steam to the Li hydride 136. In another embodiment, the tubular hydride 130b is composed of an outer borohydride, an inner Li hydride and hydride sandwich, then water mist is first supplied to the inside of the hydride (ie. Li hydride 136) before steam is supplied to the outside circumference (ie. borohydride 132b).

[0031] For use with the above hydrogen generators, the tubular hydride 130, 130a, 130b are supplied in sealed polymer bags to keep the tubular hydride/borohydride dry. After use, the depleted tubular hydride is caustic and they should be kept in the polymer bags for proper disposal.

[0032] In the above tubular hydride, sodium borohydride, Mg hydride and Li hydride are used as constituents. It is possible to use an alternative borohydride or hydride, or a mixture of alternative borohydrides or hydrides. For eg, it is possible to use lithium aluminium hydride as an alternative or as a mixture with lithium hydride.

[0033] FIG. 4 shows a control system 400 for regulating the above hydrogen generator in conjunction with a hydrogen fuel cell 420. As shown in FIG. 4, on the cap 114 of the hydrogen generator 100, lOOa-lOOe, there is a temperature sensor 410 and hydrogen pressure sensor 412. An outlet of the water pump 414 is connected to the water inlet port 180 via the water supply tubing 181 whilst a water reservoir 416 supplies water to the water pump. Preferably, the water supply tubing 181 has a check valve 418 to prevent back flow of water. At the hydrogen outlet port 190, a tubing 191 supplies hydrogen to the fuel cell 420 via a pressure relief valve 422, a pressure regulator 424 and a check valve 428. Fluidly connected to the fuel cell 420 is a purge valve 430 for releasing any hydrogen remaining in the fuel cell and hydrogen generator. From the fuel cell, a tubing recycles the by-product of water to the water reservoir 416. An external electric load is connected to an output terminal of the fuel cell 420 whilst a battery 450 is connected in parallel to the electric load for uninterrupted operation. Electrically, a controller 460 monitors the entire control system 400, such as, receiving signals from the temperature sensor 410, pressure sensor 412, level sensor 417 at the water reservoir 416, a temperature sensor 442 at the fuel cell and a pressure sensor 444 located in the hydrogen supply tube before the fuel cell, current-voltage levels at the battery 450 and the load, and a user input signals to control the water supply pump 414. In this manner, the controller 460 ensures safe and efficient operation of the hydrogen generator and fuel cell. In another embodiment, a miniature air pump 480 is provided when an air-assisted mist nozzle 182a is employed. [0034] The above control system 400, the controller 460 and various sensors provide for safe and efficient operation of the hydrogen generator 100, lOOa-lOOe and fuel cell 420. When excess pressure or temperature is detected in the hydrogen generator, the control 460 regulates or turns off the water pump 414. If the pressure in the hydrogen line is too high, the relief valve 422 opens to restore pressure to within the normal operating level. Chemically, hydrolysis of the tubular hydride 130, 130a- 130b is controlled by regulating the amount of water supplied according to the amount of hydrogen on-demand at the fuel cell and keeping to within predetermined allowable temperature and pressure in the reaction chamber. For example, during cold start of hydrolysis, the mist nozzle 182 or air assisted mist nozzle 182a turns a predetermined amount of water into mist at a predetermined rate. The mist goes through the perforations 152 on the mist delivery tube 150 and wets the borohydride 132, 132a, 132b. Hydrolysis of the borohydride, using sodium borohydride as an example, begins at a controlled rate and heat plus hydrogen are released by exothermic reaction as follows:

NaBH₄ + 2H₂0 — --> NaB0₂ + 4H₂†; ΔΗ = - 217 kJ/mol H

Or

NaBH₄ + x¾0 — -> NaBO₂.(x-2)H₂0 + 4H₂†

After the sodium borohydride 132 is hydrolysed, temperature of the reaction chamber 1 1 1 reaches to about 60-120 degC and water mist, now turned into steam, wets the hydride 134; using Mg hydride as an example, further exothermic hydrolysis of the Mg hydride continues to release hydrogen and the controller 460 regulates the water pump 414 to maintain the exothermic reaction at a controlled rate:

MgH₂ + 2H₂0 > Mg(OH)₂ + 2H₂† ; ΔΗ = - 277 kJ/mol H

[0035] Where the tubular hydride 130b has an outer layer of Li hydride as shown in FIG. 3, after the reaction chamber 1 11 has heated up, water in the supply coils 181a is emitted as steam. Steam wets the Li hydride 136 and hydrolysis of Li hydride adds heat to the reaction chamber. A reader will appreciate that the controller 460 plays a central command in the control system 400 to ensure safe and efficient operation of both the hydrogen generator 100, lOOa-lOOe and fuel cell 420. [0036] The purge valve 430 is provided to release hydrogen remaining in the fuel cell 420 and reaction chamber 111 , for eg. before startup, during shutdown or maintenance. Other safety consideration includes the use of electrostatically conductive insulator 112 to prevent electrostatic charge buildup to prevent any hazard when handling hydrogen gas. For further enhancement, the insulator 112 and cartridge cylinder 110, ie. the entire hydrogen generator 100, lOOa-lOOe, can be disposed inside an outer casing (such as a casing 505 shown in FIGs. 5A and 5B).

[0037] FIG. 5 A shows a portable hydrogen generator 500 coupled to a hydrogen fuel cell 420. The hydrogen generator 500 includes a multi-cellular cartridge 510 disposed in a casing 505. A heat insulator 512 is disposed between the multi-cellular cartridge 510 and the casing 505 to reduce heat transfer from inside the multi-cellular cartridge 510 to an exterior of the casing 505 during or after hydrogen generation. For illustration, in FIG. 5B- 5C, the multi-cellular cartridge 510 is shown to contain six compartments or reaction chambers 513a-513f; each compartment/reaction chamber 513a-513b is shaped and sized to receive a bladder holder 520 so that the remaining space below the bladder holder holds a predetermined amount of borohydride or hydride powder 530. A cap 514 is shaped and dimensioned to fit on top of the multi-cellular cartridge 510 so that the inside of the cartridge 510 is air-tight except for a hydrogen delivery port 590 associated with each reaction chamber 513a-513f or a common hydrogen delivery port 590a. An adapter 540 is sealingly connected through a thickness of the cap 514 so that each adapter is fluid connected with each compartment 513a-513f. Each adapter 540 allows a bladder puncturing apparatus 542 to be connected onto the cap 514 and operable to release a stoichiometric amount of water from an associated bladder 526 located in the bladder holder 520. In use, water released from the bladder 526 flows down into each associated compartment and hydrolyses the borohydride/hydride powder 530; hydrogen thus released is channeled out through the hydrogen outlet port 590 to an associated fuel cell 420. As will be seen in FIG. 7B, the hydrogen generator 500 is controlled to operate within a temperature range of 40-60 degC when sodium borohydride is used as the hydrogen source. Depending on the type of borohydride or hydride used, the temperature range may differ. [0038] The principle of operating hydrogen generator 500 is similar to the previous embodiment 100, 100a, etc. in that hydrogen on-demand is generated and controlled by delivering predetermined amounts of water to the borohydride or hydride. In the latter embodiment, water is delivered in predetermined or stoichiometric doses/amounts, whilst in the previous embodiment the amount of water is controlled by operating a pump.

[0039] FIG. 5B shows the hydrogen generator whilst FIG. 5C shows a partially exploded view of the hydrogen generator 500. As shown in FIGs. 5B-5D, the bladder holder 520 is formed from a sheet metal into a U-shape body so that two of the sides are open. A top part is formed with a rim 522, which is used to locate the bladder holder 520 at an upper portion of each compartment 513a-513f. The bottom part of the bladder holder 520 has an aperture 524 to support a lower part of the bladder 526. The bladder is made of a thin elastic membrane (about 0.03 to 0.1 mm thick) and holds a stoichiometric amount of water; in use, the bladder 526 is snugly held inside the bladder holder 520, with two sides of the bladder 526 contacting the two body sides of the bladder holder 520, two sides of the bladder 526 contacting the other two walls of the multi-cellular cartridge 510, a top part of the bladder in contact with an inside face the cap 514 and a bottom part being supported around the aperture 524; when the bladder 526 is punctured, the bladder bursts and water is released to hydrolyse the borohydride or hydride 530. To keep the compartments 513a- 513f airtight, a seal 516 is disposed at the interface between the multi-cellular cartridge 510 and the cap 514. The seal 516 is more clearly shown in FIGs. 6A-6B; it is possible that the seal can be configured like a gasket. In another embodiment, when the multi-cell cartridge 510 is configured for single use, the cap 514 may be adhesively bonded or welded (for eg. by ultrasonic welding) to the multi-cellular cartridge 510. Suitable polymers for the multi-cellular cartridge are: PI, PAI, PES or PC. As the casing 505 is subjected to lower temperatures, suitable polymers for the casing 505 may further include PA, PP, PE and so on.

[0040] In FIGs. 5B-5C, the bladder puncturing apparatus 542 is configured with an electric solenoid 543 and a pointed plunger 544; FIG. 5E shows such a solenoid operated plunger. In FIG. 6A, a bladder puncturing apparatus 542 is configured with an electric resistance rod element 545; when installed, the resistance rod element 545 may be offset and contacts a side of the bladder 526. In use, a current is passed through the rod element 545 and heat generated melts the bladder material that the heated rod element is in contact with. In another embodiment, two heater rod elements 545 may be employed. In yet another embodiment, FIG. 6B shows a bladder puncturing apparatus 542 is configured with a compressed air chamber 546, an electric operated valve 547 and a pointed plunger 544; to puncture the bladder, the compressed air is released by the valve 547 and causes the pointed plunger 544 to extend and to burst the bladder 526. In another embodiment shown in FIG. 6C, the bladder holder 520 holds a water receptacle 526a and an electric valve 548 is activated to release a stoichiometric amount of water to hydrolyse the hydride/borohydride 530 disposed at the bottom of the associated reaction chamber 513a- 513f. Preferably, the borohydride/hydride in each reaction chamber 513e-513f is hydrolysed one after another according to the amount of hydrogen demanded.

[0041] Preferably, the casing 505 of the hydrogen generator 500 is connected to the fuel cell 420 by a slide coupling, for eg. by relative sliding in a vertical direction, such as shown in FIG. 5F. Hydrogen produced in the generator rises and flow out through the hydrogen port 590 disposed on the cap 514. In one embodiment, each individual compartment/reaction chamber 513a-513f has a hydrogen outlet port 590. On the top side of the cap 514, each of the hydrogen outlet port 590 is connected to a common supply tubing, as shown in FIG. 5G. The tubing may terminate with a quick-disconnect coupling 592. A mating half of the quick-disconnect coupling is connected to an end of a supply tube, which supplies hydrogen to the fuel cell 420. In another embodiment, the hydrogen ports do not break through the thickness of the cap but grooves 593 are formed on the inside face of the cap 514 and the grooves 593 channel hydrogen to a common hydrogen outlet port 590a, as seen in FIG. 5H; in another embodiment, the common hydrogen port 590a may be fitted with a hose nipple 594 for connection with the hydrogen supply tube to the fuel cell 420. Preferably, a filter 596 (as seen in FIG. 7A) is fitted at each hydrogen port.

[0042] FIG. 7A shows a control system 700 for regulating the hydrogen generator shown in FIGs. 5A-5C. In one embodiment, a temperature sensor 710 and a pressure sensor 712 are located on the inside face of the cap 514, and the sensor wires are terminated at the associated terminals 711 and 713, which are shown in FIG. 5G. In addition, a wiring terminal 715 is also provided for wires from the heaters 532. In another embodiment, the pressure sensor 712 can be located in the hydrogen supply tube. From the hydrogen outlet port 590, quick coupling 592 or nipple 594, the hydrogen supply tube is connected to a check valve 720, a relief valve 730, a cooling coil 750, a buffer tank 760 and a pressure regulator 740, before terminating at the fuel cell 420. As in the above embodiment, a purge valve 770 is connected at the fuel cell for discharging or purging hydrogen from the generator 500 or fuel cell 420. The output from the fuel cell is connected to an electric load 780 whilst a batteiy 790 is comiected between the electric load and a controller 705. The controller 705 monitors the entire control system 700, such as, receiving signals from the temperature sensor 710, pressure sensor 712, current-voltage levels at the battery and load, and controls the heater 532 and bladder puncturing apparatus 542 besides receiving input signals from the user. In this manner, the controller 705 ensures safe and efficient operation of the hydrogen generator 500 and fuel cell 420.

[0043] While specific embodiments have been described and illustrated, it is understood that many changes, modifications, variations and combinations thereof could be made to the present invention without departing from the scope of the present invention.

Claims

CLAIMS:

1. A portable hydrogen generator comprising:

a reaction chamber formed inside a portable cartridge and a cap;

a water delivery system; and

a hydride or borohydride disposed in the reaction chamber, so that when a predetermined amount of water is supplied through the water delivery system, hydrolysis of the hydride/borohydride occurs, and hydrogen gas thus produced is released and delivered out through a hydrogen port.

2. The portable hydrogen generator according to claim 1 , wherein the water delivery system comprises a mist delivery tube disposed in the reaction chamber.

3. The portable hydrogen generator according to claim 2, wherein the borohydride is configured as a porous inner cylinder and the hydride is configured as a porous outer cylinder, or the borohydride is configured outside the hydride.

4. The portable hydrogen generator according to claim 2 or 3, further comprising a mist nozzle fitted to an inside face of the cap for supplying water as mist to a top of the mist delivery tube.

5. The portable hydrogen generator according to claim 4, wherein the mist nozzle is assisted by compressed air.

6. The portable hydrogen generator according to any one of claims 2-5, further comprising a sponge disposed at a bottom of the mist delivery tube to absorb water condensate.

7. The hydrogen generator according to any one of claims 4-6, wherein a water supply tube connected to the mist nozzle reaches to a bottom of the reaction chamber and rises up in spiral coils.

8. The portable hydrogen generator according to claim 7, wherein the water supply tube in the reaction chamber is made of steam permeable PTFE (Teflon).

9. The portable hydrogen generator according to claim 8, further comprising Li hydride disposed around the hydride/borohydride to form a three-stage cartridge.

10. The portable hydrogen generator according to claim 2, wherein the hydride is composed of an outer porous cylinder of a borohydride and an inner porous cylinder of hydride, and the mist delivery tube is disposed coaxially outside the cylindrical hydride.

1 1. The portable hydrogen generator according to claim 10, further comprising a circular mist spray ring fitted to an inside face of the cap for supplying water as mist in an annular space around a top of the mist delivery tube.

12. The portable hydrogen generator according to claim 1 1, further comprising a sponge disposed in an annular space around a bottom of the mist delivery tube.

13. The portable hydrogen generator according to any one of claims 3-8 or 10-12, wherein the cylinders of borohydride and hydride and the mist delivery tube are dimensioned for slide fit.

14. The portable hydrogen generator according to any one of claims 3-8 or 10-12, wherein the borohydride, hydride and mist delivery tube are integrally formed.

15. The portable hydrogen generator according to claim 9, wherein the Li hydride is cylindrically formed to slide fit or integrally formed with the hydride.

16. The portable hydrogen generator according to claim 1, wherein the reaction chamber comprises a plurality of reaction chambers formed inside a multi-cellular cartridge.

17. The portable hydrogen generator according to claim 16, wherein the water delivery system associated with each of the plurality of reaction chambers comprises a bladder holding a stoichiometric amount of water and a bladder puncturing apparatus.

18. The portable hydrogen generator according to claim 17, wherein the hydride/borohydride, in the form of powder, is disposed at a bottom of each associated reaction chamber.

19. The portable hydrogen generator according to claim 17, wherein the bladder puncturing apparatus comprises an electric solenoid operable to actuate a pointed plunger.

20. The portable hydrogen generator according to claim 17, wherein the bladder puncturing apparatus comprises an electric resistance rod element disposed in contact with the bladder, which the resistance rod element is operable to be heated up by supplying an electric current to puncture the bladder.

21. The portable hydrogen generator according to claim 17, wherein the bladder puncturing apparatus comprises a compressed air chamber, a valve and a pointed plunger.

22. The portable hydrogen generator according to claim 16, wherein the water delivery system associated with each of the plurality of reaction chambers comprises a water receptacle holding a stoichiometric amount of water and a valve, which valve is electrically operable to release the stoichiometric amount of water from the water receptacle.

23. The portable hydrogen generator according to any one of the preceding claims, further comprising a heat insulator disposed around the portable cartridge.

24. The portable hydrogen generator according to claim 23, further comprising a casing to contain the heat insulator and portable cartridge.

25. A process for generating hydrogen on-demand comprising:

disposing a water delivery system in an enclosed reaction chamber;

disposing a hydride/borohydride in the reaction chamber;

releasing a stoichiometric amount of water from the water delivery system to hydrolyse the hydride/borohydride; and

channeling an amount of hydrogen produced through an outlet port to a hydrogen fuel cell.

26. The process according to claim 25, wherein releasing a stoichiometric amount of water comprises delivering water as mist by operating a pump with a nozzle.

27. The process according to claim 25, wherein releasing a stoichiometric amount of water comprises delivering water through a steam permeable supply tubing disposed inside the reaction chamber.

28. The process according to any one of claims 25-27 comprising a two-stage hydrogen generation, which includes a first stage borohydride and a second stage hydride.

29. The process according to any one of claims 25-27 comprising a three-stage hydrogen generation, which includes a borohydride, a hydride and a Li hydride.

30. The process according to claim 25, wherein releasing a stoichiometric amount of water comprises puncturing a bladder disposed in the reaction chamber.

31. The process according to claim 25, wherein releasing a stoichiometric amount of water comprises activating a valve to release the stoichiometric amount of water from a water receptacle located in each reaction chamber.