A device for generating hydrogen

Abstract

The present invention provides an apparatus and process for generating hydrogen gas. The present invention also provides a system for generating electrical energy from hydrogen gas. More specifically, the present invention provides an apparatus for generating hydrogen gas comprising: an ammonia cracker having one or more untreated cracked gas outlets in fluid communication with a common untreated cracked gas conduit; one or more gas separators in fluid communication with the ammonia cracker via the common untreated cracked gas conduit and in fluid communication with a common partially purified cracked gas conduit; and one or more filter assemblies each having a first container having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets.

Description

Background Art

[0001] Hydrogen gas is a promising clean fuel that plays an important role as part of the global effort to reduce climate change. Hydrogen gas can be easily combusted or used to generate electrical energy using special devices such as fuel cells. There are several ways to produce hydrogen, for example, steam reforming of natural gas or electrolysis of water. However, one promising method to produce clean hydrogen is catalytic decomposition (commonly referred to as "catalytic cracking" or simply "cracking") that decomposes ammonia gas into hydrogen and nitrogen according to the following reaction.

Number

[0002] The device for producing hydrogen by this method is generally called an "ammonia cracker" and includes a heating chamber containing a catalyst through which ammonia gas flows. As soon as it contacts the catalyst, ammonia is decomposed to produce hydrogen and nitrogen gas. Such devices are known in the art (see, for example, Patent Document 1).

[0003] The gas is generally a hydrogen-rich gas mixture containing hydrogen gas, nitrogen gas, and ammonia gas. One of the technical challenges of hydrogen production by ammonia decomposition is to separate the hydrogen-rich gas mixture into its components. Depending on the downstream use, hydrogen gas of different purities may be required. Ammonia gas present in the output gas mixture is particularly troublesome in certain applications. The reason is that it can invalidate the specifications and cause technical problems in downstream devices when passing through various gas separation means employed in typical systems for purifying hydrogen gas.

[0004] Currently, several purification methods are employed to purify and reuse hydrogen gas. One method of purifying hydrogen gas is to bubble the impure gas through water so that ammonia is removed. The drawback of this method is that nitrogen is not removed, requiring further processing. Another common method uses a pressure swing adsorption ("PSA") apparatus, such as the one disclosed in Patent Document 2. In this system, impurities in a hydrogen-rich gas mixture are bonded under pressure to at least two adsorbent materials (non-zeolite adsorbent, e.g., activated carbon for ammonia gas; and zeolite adsorbent, e.g., 5A zeolite or 13X zeolite for nitrogen gas). While such systems are useful for removing nitrogen and ammonia gas for downstream use, in practice, such systems are expensive and cannot guarantee ammonia-free gas under all conditions. Furthermore, ammonia adsorption and nitrogen adsorption require different adsorbent materials because each impurity has different properties.

[0005] The applicants have discovered a low-cost, reliable, and environmentally friendly solution for further purifying hydrogen gas from a gas mixture from an ammonia decomposition system, for example, from which some, but not all, of the ammonia has been removed by pressure swing adsorption, and which offers numerous advantages over the prior art, as discussed below. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2009 / 098452 [Patent Document 2] International Publication No. 2022 / 265651 [Patent Document 3] Chinese Patent Application Publication No. 114408860 [Patent Document 4] U.S. Patent No. 3,352,716 [Patent Document 5] U.S. Patent Application Publication No. 2023 / 0174375 [Patent Document 6] U.S. Patent Application Publication No. 2003 / 0232224 [Patent Document 7] U.S. Patent No. 6340382 [Patent Document 8] UK Patent Application Publication No. 969673 [Patent Document 9] U.S. Patent No. 4293419 [Patent Document 10] UK Patent Application Publication No. 2508649 [Non-patent literature]

[0007] [Non-Patent Document 1] Kheimi, Marwan, and Sultan K. Salamah. “Simulation of temperature swing adsorption process to purify hydrogen for fuel cell uses by SAPO34 as adsorbent.” Chemosphere 338 (2023): 139454. [Overview of the project]

[0008] In a first aspect, the present invention provides an apparatus for generating hydrogen, comprising: an ammonia cracker having one or more untreated cracked gas outlets in fluid communication with a common untreated cracked gas conduit; one or more gas separators having fluid communication with the ammonia cracker via the common untreated cracked gas conduit and with a common partially purified cracked gas conduit; and one or more filter assemblies having a first container, each having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets, wherein the one or more partially purified cracked gas inlets are in fluid communication with the one or more gas separators via the common partially purified cracked gas conduit; the first container contains a single mass of adsorbent containing silica gel; and the one or more partially purified cracked gas inlets and the one or more purified cracked gas outlets are arranged so that the partially purified cracked gas flows through the single mass of adsorbent when in use.

[0009] In one embodiment, one or more walls are made of metal. In further embodiments, the metal is stainless steel, high-carbon steel, aluminum, or titanium.

[0010] In further embodiments, the metal includes a polymer coating. In further embodiments, the polymer coating is a fluorinated polymer, preferably PTFE or PFA.

[0011] In one embodiment, one or more walls include plastic, optionally transparent plastic and / or opaque plastic. In one embodiment, the plastic is fluorinated plastic or polycarbonate.

[0012] In one embodiment, each filter assembly further includes an inspection window for viewing a single clump of adsorbent.

[0013] In one embodiment, the apparatus further comprises an auxiliary container containing a second mass of adsorbent comprising silica gel, the auxiliary container being disposed downstream of the first container via one or more purified cracked gas outlets and in fluid communication with the first container, and the auxiliary container further comprising a second inspection window for viewing the second mass of adsorbent. In a further embodiment, one or more walls further comprise inspection windows. In a further embodiment, the inspection window is proximal to at least one of the one or more purified cracked gas outlets. In a further embodiment, the inspection window comprises a portion proximate to at least one of the one or more partially purified cracked gas inlets.

[0014] In some embodiments, the filter assembly further comprises a flow structure for lengthening the path of travel of the partially purified cracked gas through a single mass of adsorbent.

[0015] In some embodiments, the flow structure is disposed within a single mass of adsorbent and comprises one or more permeable tubes connected at one end to one or more partially purified cracked gas inlets, one or more baffles extending from one or more walls of the filter assembly, one or more inserts disposed within the container, the container comprising a sub-structure formed of a substrate that forms an internal volume at least partially filled with a single mass of adsorbent, the sub-structure being in fluid communication with one or more partially purified cracked gas inlets and one or more purified cracked gas outlets, one or more inserts, or any combination of the above.

[0016] In some embodiments, the silica gel comprises silica gel beads, silica gel powder, and / or silica gel granules.

[0017] In some embodiments, each filter assembly comprises an indicator adsorbed to, disposed on, and / or proximal to the silica gel.

[0018] In some embodiments, the apparatus further comprises an ammonia gas sensor. In further embodiments, the ammonia gas sensor is disposed downstream of and in fluid communication with one or more purified cracked gas outlets. In further embodiments, the ammonia gas sensor is connected to the one or more purified cracked gas outlets via a regulator.

[0019] In one embodiment, each of the one or more filter assemblies is in fluid communication with a common partially purified cracked gas flow conduit via one or more partially purified cracked gas inlets, and each filter assembly has a first valve between the one or more partially purified cracked gas inlets and the common partially purified cracked gas flow conduit.

[0020] In one embodiment, each of the one or more filter assemblies is in fluid communication with a common purified cracked gas flow conduit via one or more purified cracked gas outlets, and each filter assembly has a second valve between the one or more purified cracked gas outlets and the common purified cracked gas flow conduit.

[0021] In one embodiment, the one or more gas separators comprise a pressure swing adsorption device and / or a palladium filter and / or a catalytic converter reactor and / or a temperature swing adsorption device and / or a hollow fiber membrane filter.

[0022] In one embodiment, the one or more gas separators are proximal to or integral with the ammonia cracker.

[0023] In one embodiment, more than 30% of the single mass of the adsorbent is silica gel, and optionally, the single mass of the adsorbent consists essentially of silica gel.

[0024] In a second aspect, the present invention provides a system for generating electricity using ammonia, the system comprising an apparatus according to the first aspect or any embodiment thereof, and a hydrogen fuel cell in fluid communication with the apparatus for generating hydrogen via a common purified cracked gas flow conduit.

[0025] In a third aspect, the present invention provides a process for producing purified cracked gas of high-purity hydrogen, the process comprising: supplying ammonia gas to an ammonia cracker having one or more raw cracked gas outlets in fluid communication with a common raw cracked gas conduit to produce raw cracked gas containing hydrogen gas, nitrogen gas, and ammonia gas; a first purification step comprising transporting the raw cracked gas through the common raw cracked gas conduit to one or more gas separators, the one or more gas separators at least partially removing the ammonia gas and nitrogen gas from the raw cracked gas to produce partially purified cracked gas; and a second purification step comprising transporting the partially purified cracked gas through a common partially purified cracked gas conduit to one or more filter assemblies. The present invention comprises a first container having one or more walls, one or more partially purified decomposition gas inlets, and one or more purified decomposition gas outlets, wherein the one or more partially purified decomposition gas inlets are in fluid communication with the common partially purified decomposition gas conduit, the first container contains a single mass of adsorbent containing silica gel, the one or more partially purified decomposition gas inlets and the one or more purified decomposition gas outlets are arranged so that the partially purified decomposition gas flows through the single mass of adsorbent, the single mass of adsorbent selectively adsorbs the ammonia in the partially purified decomposition gas to produce a purified decomposition gas, the partially purified decomposition gas being transported through the one or more filter assemblies at process pressure, the process pressure being substantially constant.

[0026] In one embodiment, the process pressure is 35 bar or less.

[0027] In one embodiment, at least one of the one or more gas separators is a pressure swing adsorption device, the pressure swing adsorption device comprises a plurality of containers, each container comprising a first pressure swing adsorbent for adsorbing nitrogen gas from the untreated decomposition gas, a second pressure swing adsorbent for adsorbing ammonia gas from the untreated decomposition gas, and optionally a third pressure swing adsorbent for adsorbing water, the plurality of containers comprising a first pair of containers comprising a first container and a second container, the process comprising (a) the first of the first pair of containers (b) fluid connection of a container to the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit, and transporting the untreated decomposed gas to the first container at the process pressure, wherein the ammonia gas and nitrogen gas (and optionally water) in the untreated decomposed gas are at least partially removed to produce the partially purified decomposed gas; (c) transporting the partially purified decomposed gas from the first container to the common partially purified decomposed gas conduit at the process pressure; and (d) fluid connection of a container to the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit. (d) a step of fluidly isolating the first container from the decomposition gas conduit; (f) a step of fluidly connecting the first container to the second container of the first pair of containers, wherein the second container is at atmospheric pressure, so the first container is depressurized and the second container is pressurized, so that the first and second containers are at half the process pressure; (e) a step of fluidly isolating the first container from the second container, fluidly connecting the first container to a common waste gas conduit, and transporting the waste gas containing nitrogen gas and ammonia gas from the first container to the common waste gas conduit. (f) a step in which the first container is subjected to further depressurization so that the first container is at atmospheric pressure; (g) a step in which the first container is fluidly connected to a common purge gas conduit, and purge gas at atmospheric pressure is transported to the first container to remove residual waste gas from the first container via the common waste gas conduit; (h) a step in which the first container is fluidly isolated from the common waste gas conduit and the common purge gas conduit; and (e) a step in which the first container is fluidly connected to the second container, the second container being at the process pressure.The sequence includes the steps of (a) pressurizing the first container and depressurizing the second container so that the first and second containers are at half the process pressure; (i) fluidically isolating the first container from the second container, fluidly connecting the first container to a common backfill gas conduit, and transporting backfill gas such that the first container is pressurized and the first container is at the process pressure; and (j) fluidically isolating the first container from the common backfill gas conduit, and fluidly connecting the first container to the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit, wherein during steps (a) to (j), the partially purified decomposed gas is transported through one or more filter assemblies at the process pressure.

[0028] In one embodiment, the partially purified cracked gas is transported from multiple gas separators to one or more filter assemblies.

[0029] In one embodiment, a single mass of adsorbent comprises at least 30% by mass of silica gel, and optionally, a single mass of adsorbent is essentially composed of silica gel.

[0030] In one embodiment, the partially purified decomposed gas is transported through one or more filter assemblies at a process temperature, which is 100°C or less, and preferably between -50°C and 50°C. [Brief explanation of the drawing]

[0031] [Figure 1] The present invention illustrates an apparatus for producing purified hydrogen gas, comprising an ammonia cracker, one or more gas separators, and one or more filter assemblies according to the present invention. [Figure 2] An exemplary filter assembly according to the present invention, having one partially purified cracked gas inlet and one purified cracked gas outlet, is shown as a cross-sectional view. [Figure 3] An exemplary filter assembly according to the present invention, having multiple partially purified and decomposed gas inlets and purified and decomposed gas outlets, is shown as a cross-sectional view. [Figure 4] An exemplary filter assembly according to the present invention is shown, having one or more opaque walls, with an inspection window positioned therein. [Figure 5] An alternative filter assembly according to the present invention is shown, in which the inspection window extends over substantially the entire length of the filter assembly. [Figure 6] An exemplary filter assembly is shown, which includes an auxiliary container having one or more walls that are in fluid communication with the first container of the present invention. [Figure 7] An exemplary filter assembly according to the present invention, having perforated tubes for extending the gas flow path from one or more partially purified and cracked gas inlets, is shown as a cross-sectional view. [Figure 8] An exemplary filter assembly with baffles for extending the gas flow path is shown. [Figure 9] This document describes a system for generating hydrogen gas, comprising a gas separator and a plurality of filter assemblies according to the present invention. [Figure 10] The diagram shows a system for generating hydrogen gas, comprising an ammonia cracker, a gas separator, and a filter assembly, the filter assembly being in fluid communication with a common purified cracked gas flow conduit and an ammonia gas sensor via a regulator. [Figure 11] This diagram shows a system for generating electricity from hydrogen, comprising an ammonia cracker, a gas separator, a filter assembly, and a hydrogen fuel cell. [Modes for carrying out the invention]

[0032] Patent Document 3 discloses a two-stage pressure swing adsorption device. The first stage of this device includes three adsorbent blocks comprising activated alumina, activated carbon, silica gel, and molecular sieves. The second stage comprises activated alumina and / or molecular sieves.

[0033] Patent Document 2 discloses a pressure swing adsorption device having two adsorbent masses, wherein the first adsorbent is a non-zeolite adsorbent that adsorbs water and ammonia, and the second adsorbent is a zeolite adsorbent that adsorbs nitrogen.

[0034] Patent document 4 discloses a drying apparatus for drying exhaust gas from the combustion chamber of an ammonia cracker.

[0035] Patent Document 5 discloses a system that uses a single-stage or two-stage system including a conventional pressure swing adsorption apparatus for purifying hydrogen. Each unit includes two adsorbent blocks: a zeolite adsorbent for adsorbing nitrogen and a non-zeolite adsorbent for adsorbing water and ammonia.

[0036] The present invention will be illustrated here with reference to the drawings, using specific embodiments discussed below.

[0037] In a first embodiment, the present invention provides a hydrogen production apparatus comprising: an ammonia cracker having one or more untreated cracked gas outlets in fluid communication with a common untreated cracked gas flow conduit; one or more gas separators in fluid communication with the ammonia cracker via the common untreated cracked gas flow conduit and in fluid communication with a common partially purified cracked gas flow conduit; and one or more filter assemblies as described below. Figure 1 shows such an apparatus, where arrows represent gas flows, and the ammonia cracker 111 is in fluid communication with the common untreated cracked gas flow conduit 112a, which in turn fluidly connects the ammonia cracker to one or more gas separators 116. One or more gas separators 116 are in fluid communication with one or more filter assemblies 101 via the common partially purified cracked gas flow conduit 112b. The apparatus of the present invention may be described as a “system”. The drawings are for illustrative purposes only, and the components of the apparatus may be oriented as necessary.

[0038] The common untreated decomposed gas conduit, one or more gas separators, and the common partially purified decomposed gas conduit may be considered and described as a single conduit that can be referred to as the “common untreated decomposed gas conduit.” Thus, one or more gas separators described herein can be described as forming part of the common untreated decomposed gas conduit extending between the ammonia decomposer and one or more filter assemblies, and one or more gas separators can be described as being located between the ammonia decomposer and one or more filter assemblies and being in fluid communication with them. Thus, when “untreated decomposed gas” is referred to herein, it may mean partially purified decomposed gas, provided that the untreated decomposed gas has passed through one or more gas separators. The “common partially purified decomposed gas conduit” downstream of one or more gas separators may be referred to as the “common untreated decomposed gas conduit,” and one or more “partially purified decomposed gas inlets” of one or more filter assemblies may be referred to as one or more “untreated decomposed gas inlets.”

[0039] During use, ammonia gas is supplied to an ammonia cracker 111 to produce untreated cracked gas containing (or having contained) hydrogen gas, nitrogen gas, and ammonia gas. This untreated cracked gas flows out of the ammonia cracker and into one or more gas separators 116 via a common untreated cracked gas conduit 112a. The one or more gas separators 116 remove at least partially nitrogen gas and ammonia gas from the untreated cracked gas to produce partially purified cracked gas, which then flows into one or more filter assemblies 101 via a common partially purified cracked gas conduit 112b. Those skilled in the art will understand that the ammonia cracker and the one or more gas separators may have any number of inlets and outlets suitable for supplying the gases required for the operation of the apparatus. The ammonia cracker has at least one inlet and at least one outlet. The one or more gas separators each have at least one inlet and at least one outlet. The ammonia cracker is in fluid communication with at least one ammonia gas source, which may be a storage tank or a common ammonia gas conduit. For simplicity, the common untreated decomposed gas conduit 112a may be called the first common gas conduit, and the common partially purified decomposed gas conduit 112b may be called the second common gas conduit.

[0040] The present invention provides an apparatus for generating hydrogen, comprising: an ammonia cracker having one or more untreated cracked gas outlets in fluid communication with a common untreated cracked gas conduit; one or more gas separators having fluid communication with the ammonia cracker via the common untreated cracked gas conduit, one or more gas separators also having fluid communication with the ammonia cracker via the common untreated cracked gas conduit; and one or more filter assemblies having fluid communication with one or more gas separators via a common partially purified cracked gas conduit, each filter assembly having a first container having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets, the one or more partially purified cracked gas inlets having fluid communication with a common partially purified cracked gas conduit, the first container containing a single mass of adsorbent including silica gel, the one or more partially purified cracked gas inlets and one or more purified cracked gas outlets being arranged so that the partially purified cracked gas flows through the single mass of adsorbent when in use, one or more filter assemblies. Therefore, one or more partially purified and cracked gas inlets and one or more purified and cracked gas outlets must be configured such that a single mass of adsorbent is located within the internal volume of the first container and is positioned between one or more partially purified and cracked gas inlets and one or more purified and cracked gas outlets.

[0041] In some embodiments, the present invention provides an apparatus for generating hydrogen, comprising: an ammonia cracker having one or more untreated cracked gas outlets in fluid communication with a common untreated cracked gas conduit, configured to generate untreated cracked gas containing hydrogen gas, nitrogen gas, and ammonia gas, and to supply the untreated cracked gas to a common untreated cracked gas flow path via one or more untreated cracked gas outlets; and one or more gas separators in fluid communication with the ammonia cracker via the common untreated cracked gas conduit and in fluid communication with a common partially purified cracked gas conduit, which remove at least partially ammonia gas and nitrogen gas from the untreated cracked gas to generate partially purified cracked gas, and to supply the partially purified cracked gas to a common partially purified cracked gas conduit. The filter assembly comprises one or more gas separators configured to do so, and one or more first containers, each having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets, wherein one or more partially purified cracked gas inlets are in fluid communication with one or more gas separators via a common partially purified cracked gas flow conduit, the first containers contain a single mass of adsorbent containing silica gel, and the one or more partially purified cracked gas inlets and one or more purified cracked gas outlets are arranged so that partially purified cracked gas flows through the single mass of adsorbent when in use, and the single mass of adsorbent is configured to selectively adsorb ammonia in the partially purified cracked gas supplied to one or more purified cracked gas outlets.

[0042] One or more filter assemblies of the present invention can be better understood with reference to Figure 2. The present invention provides an apparatus comprising one or more filter assemblies 200, each filter assembly having a first container 201 having one or more walls 202 and one or more partially purified cracked gas inlets 203 that are in fluid communication with a common partially purified cracked gas conduit, each filter assembly having one or more purified cracked gas outlets that can be fluidly connected to the common partially purified cracked gas conduit, the first container containing a single mass of adsorbent 205 containing silica gel, and the one or more partially purified cracked gas inlets and one or more purified cracked gas outlets are arranged so that the partially purified cracked gas flows through the single mass of adsorbent when in use. An exemplary filter assembly is shown in Figure 2. For simplicity, the common partially purified cracked gas conduit may be referred to as a third common gas conduit.

[0043] As discussed, apparatus for producing hydrogen from ammonia is, for example, an ammonia cracker. These apparatuses work by catalytic decomposition of ammonia at high temperatures to produce nitrogen and hydrogen gases (see, for example, Patent Document 6 incorporated herein by reference). Typically, an ammonia cracker comprises a reaction chamber containing an ammonia decomposition catalyst, the reaction chamber having an inlet and outlet configured to allow ammonia gas to flow into the reaction chamber, where it comes into contact with the ammonia decomposition catalyst and is decomposed into untreated decomposition gas containing nitrogen and hydrogen gases (and residual ammonia gas), which flows out through the outlet and into further downstream systems. The reaction chamber is heated by a heat source (internal and / or external) to allow the decomposition reaction to proceed. Ammonia decomposition catalysts are known in the art. Typical ammonia decomposition catalysts that can be used include, for example, supported monometallic catalysts (e.g., Fe, Ru, Cu, Ni, Ir, Co, Mo, Pt, and Pd), polymetallic or alloy catalysts (e.g., Ni-Pt, Ni-Co, Ir-Ni, Co-Mo, Fe-Co, Fe-Mo, Cu-Zn), nitride and carbide catalysts (e.g., carbides and nitrides of Mo, Fe, Co, Ni, Ti, V, Mn, and Cr), and metal amide / imide catalysts (e.g., LiNH2, NaNH2, KNH2). The reaction chamber can take any shape as long as it is airtight except for the inlet and outlet. The reaction chamber can be made of any suitable ammonia-resistant material or composite material, such as austenitic stainless steel. Any heat source may be used as long as it can heat the volume defined by the reaction chamber to a temperature suitable for the decomposition of ammonia. For example, the volume defined by the reaction chamber can be heated between 400 and 950°C. Reaction chambers typically operate at operating pressures of 100 bar (or barg) or less, preferably 50 bar (or barg) or less (e.g., 0.1 barg to 50 barg). Therefore, reaction chambers are appropriately constructed to withstand such pressures.The untreated cracked gas produced by the ammonia cracker typically contains a mixture of hydrogen gas, nitrogen gas, and residual ammonia gas remaining from the equilibrium reaction occurring within the ammonia cracker. As the untreated cracked gas leaves the ammonia cracker, it is initially separated using one or more gas separators to remove most of the nitrogen and / or ammonia before entering one or more filter assemblies. This is preferable because the filter assemblies described in this embodiment remove only ammonia and not nitrogen gas. Each filter assembly of the present invention is a container through which the partially purified cracked gas flows. The container 201 (i.e., the first container) has one or more walls 202 and is airtight except for one or more partially purified cracked gas inlets 203 that allow the flow of partially purified cracked gas into the internal volume of the container, and one or more purified cracked gas outlets 204 that allow the flow of purified cracked gas from the internal volume of the container. The container contains a single mass of adsorbent 205 containing silica gel, which is placed in the internal volume of the container, so that the partially purified cracked gas flows through the single mass of adsorbent containing silica gel in close proximity to it. The silica gel in this single adsorbent readily absorbs any ammonia in the partially purified cracked gas, thus removing the ammonia and purifying the gas to produce a purified cracked gas that is predominantly hydrogen gas. This removal of ammonia gas produces a purified hydrogen gas mixture, which is discharged from the first container for downstream use or storage.

[0044] The shape of the (first) container is airtight except for one or more partially purified cracked gas inlets and one or more purified cracked gas outlets, and is not problematic as long as it can hold a single mass of silica gel-containing adsorbent in a manner suitable for flowing gas through a single mass of silica gel-containing adsorbent. In the illustrated embodiment, the container is shown as a cylinder, but this is for illustrative purposes only and can be any shape. The filter assembly may have two or more (i.e., multiple) partially purified cracked gas inlets 303 and / or two or more (i.e., multiple) purified cracked gas outlets 304, as shown in Figure 3, which has the advantage of spreading the gas flow across the entire width of the single mass of silica gel-containing adsorbent and providing fail-safe in case one of the inlets and / or outlets is blocked.

[0045] Each of the filter assemblies contains a single mass of adsorbent containing silica gel. This means that there is only one mass of adsorbent in each of the filter assemblies. In some embodiments, the single mass of adsorbent containing silica gel may be distributed throughout the container as a single layer or as multiple separate layers. In some embodiments, the single mass of adsorbent may exist as a single part within the container, or as multiple separate parts of the adsorbent distributed through the container. In some embodiments, the phrase "single mass of adsorbent" may be understood to mean a homogeneous mass of adsorbent material containing silica gel. In some embodiments, there are no multiple different masses of adsorbent in the apparatus; that is, the components constituting the single mass of adsorbent are the same and in the same proportions. In other words, this may be thought of as a single type of adsorbent or a single mixture of adsorbents. This single mass of adsorbent contains silica gel. This single mass of adsorbent adsorbs only ammonia, and the ammonia is adsorbed into the silica gel. In contrast, a PSA apparatus used for the purposes of the present invention has at least two separate masses of adsorbent, typically a first mass containing a zeolite adsorbent for adsorbing nitrogen and a second mass containing a non-zeolite adsorbent for adsorbing ammonia. Suitable adsorbents are known to those skilled in the art. For example, the zeolite adsorbent may be 5A zeolite or 13X zeolite, and the non-zeolite adsorbent may be activated carbon.

[0046] In one or more filter assemblies of the present invention, the filter assemblies function to adsorb only residual ammonia, producing a high-purity product gas suitable for use, for example, in fuel cells. Such filter assemblies are simpler than, for example, PSAs. This is because they do not have the valves and inlets or outlets required by PSAs due to the pressure swing steps of their operation. The filter assemblies described herein have the advantage of being simpler than PSAs and such gas separators. The applicants envision that one or more filter assemblies of the present invention can be used simply until a single mass of adsorbent is nearly saturated with ammonia before replacement, and the used (i.e., nearly completely saturated) filter assemblies are sent for reprocessing. The advantage is that each filter assembly can be replaced quickly, minimizing downtime for the apparatus for hydrogen production. This is in contrast to PSAs, which must be shut down and undergo a purge cycle to remove impurities from the two adsorbent layers, and the impurities require further system architecture to be removed and disposed of. In addition, PSAs are typically not fixed in a removable manner, in the sense that they can be replaced quickly, in contrast to one or more filter assemblies of the present apparatus. A single mass of adsorbent contains silica gel that readily adsorbs ammonia gas. A single mass of adsorbent may contain 30%, 40%, 50%, 60%, 70%, 80%, or 90% or more by mass of silica gel. A single mass of adsorbent may consist essentially of silica gel, or it may consist of silica gel. Therefore, it may be described as an adsorbent mass consisting essentially of silica gel, or an adsorbent mass composed of silica gel. The composition of the remaining mass percentage of the single mass of adsorbent is not important as long as it does not interfere with the function of the silica gel. Each filter assembly has only a single mass of adsorbent. In other words, only adsorbent masses containing silica gel exist, and no other adsorbent masses exist.

[0047] One or more walls of the first container can be made from any suitable material. In some embodiments, one or more walls are made from or contain metal. Examples of metals for this use are stainless steel, high-carbon steel, aluminum, or titanium. In one embodiment, one or more walls are made from or contain stainless steel. Metal structures have the advantage of being able to withstand high pressure. This is particularly useful in applications where partially purified decomposition gas enters the container and exerts high pressure on the container. For example, metal is preferred when the pressure is greater than 1 bar. One or more walls of the container are preferably made of a material that does not readily absorb ammonia. Ammonia can react with some metals, causing those metals to become brittle or otherwise altering their physical properties. For example, high-carbon steel is susceptible to the effects of ammonia, and when it absorbs ammonia, the metal degrades. Therefore, in some embodiments, at least the inner surfaces of one or more walls of the container are coated with a resistance coating. The inner surfaces are the surfaces of one or more walls of the container that face silica gel placed within the internal volume of the container. Resistive coatings allow for the use of various materials to construct the container while imparting resistance to the effects of ammonia gas to the constituent materials. In some embodiments, the coating may be a polymer coating. For example, the coating may be a fluorinated polymer such as polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA).

[0048] In some embodiments, one or more walls are made from or contain plastic. In some embodiments, the plastic is transparent plastic and / or opaque plastic. In some embodiments, the plastic is fluorinated plastic or polycarbonate. Such structures may be preferred for filter assemblies according to the present invention that are not subjected to high internal pressures. Such pressures may be less than 10 barg. In some embodiments, the fluorinated plastic is polytetrafluoroethylene (PTFE) or perfluoroalkoxyalkane (PFA). These plastics are particularly resistant to ammonia adsorption.

[0049] In further embodiments of the present invention, the filter assembly may include an inspection window for visualizing the silica gel. The inspection window may be located within one or more walls of the container so that a single clump of adsorbent containing silica gel can be observed from the outside, as shown in Figure 4. Here, the inspection window 406 is located near one or more purified cracking gas outlets 404 so that a single clump of adsorbent 405 containing silica gel is visible from the outside. In some embodiments, the inspection window is located near at least one of the one or more purified cracking gas outlets. As an addition or alternative, the inspection window is located near at least one of the one or more partially purified cracking gas inlets 403. For example, it may extend from one end of the container to the other so as to be near one or more partially purified cracking gas inlets and one or more purified cracking gas outlets. Figure 5 shows an embodiment in which the inspection window 506 extends near both one or more partially purified cracking gas inlets 503 and one or more purified cracking gas outlets 504, allowing the user to view a single clump of silica gel of the adsorbent 505. The inspection window can be made of any suitable material, such as clear or translucent plastic or glass. Soda-lime glass is a suitable glass for this application, but other suitable glasses such as quartz, sapphire, and borosilicate glass are known to those skilled in the art. The clear or translucent plastic may be, for example, PTFE or PFA. The inspection window must not affect the airtightness of the container. Furthermore, it must withstand the pressure the container is subjected to.

[0050] As an addition or alternative, the present invention may include an auxiliary container having an inspection window for visualizing its internal volume, the auxiliary container containing a second mass of silica gel located downstream of the first container and in fluid communication with it. Downstream refers to the flow of gas through the apparatus in use. Thus, the auxiliary container is located near the end of the first container proximal to one or more purified cracking gas outlets. Gas can flow from the first container into the auxiliary container. The inspection window is located on one or more walls of the auxiliary container. An exemplary embodiment is shown in Figure 6, in which the auxiliary container 607 is in fluid communication with the first container 602 via one or more purified cracking gas outlets 604. The auxiliary container contains a second mass 608 of adsorbent containing silica gel, and an inspection window 606 is located on one or more of its walls to allow the second mass 608 of adsorbent containing silica gel to be seen from the outside.

[0051] In one embodiment, the filter assembly further comprises a flow structure for lengthening the travel path of the partially purified decomposed gas through a single mass of adsorbent containing silica gel. Each partially purified decomposed gas inlet may be connected to one or more flow structures as needed. The flow structure comprises, for example, one or more permeable tubes connected to the inlets, which direct the gas along a predetermined path but allow the gas to flow out of the tubes and come into contact with a single mass of adsorbent containing silica gel. An exemplary embodiment is shown in Figure 7, where a perforated tube 709 is connected to one or more purified decomposed gas inlets 703 and is located within a single mass of adsorbent 705 containing silica gel. Such tubes can be molded to extend the gas flow path throughout the entire internal volume of the first container of the filter assembly. For example, they can be wound substantially perpendicular to the length of the container. Additionally or alternatively, the flow structure comprises one or more baffles, which extend from the inner wall of the container and physically guide the gas flow along a longer path. This exemplary embodiment is shown in Figure 8, where a plurality of baffles 810 extend from the inner wall of the first container 802 into its internal volume, so that the partially purified decomposed gas is forced to travel a longer path through a single mass of adsorbent 805 containing silica gel. The baffles may be made of the same material as the first container or of a different material. The material may be ammonia resistant. For example, they may be made of metal (e.g., stainless steel, high carbon steel, aluminum, or titanium) or plastic (e.g., PTFE or PFA). Each baffle may be made of different materials or the same materials. One or more baffles may comprise at least one baffle made of each of the above materials in any combination. The baffles are attached to the inner surface of one or more walls of the container by any means known to those skilled in the art.For example, the baffle may be attached by mechanical fasteners (e.g., bolts, rivets, etc.), welded thereto, brazed thereto, or actually form part of the inner wall so as to be a single unit (e.g., when the container is made by casting), or any combination of these techniques.

[0052] In one embodiment, the flow structure may comprise one or more inserts placed within the container. The inserts are placed on a single mass of adsorbent containing silica gel and provide a physical barrier that obstructs the gas flow, thereby forcing the gas to flow around a longer path. The inserts are essentially the baffles described above, but do not extend from the inside of one or more walls. The inserts may be made from the same material as the first container, or from a different material. The material may be ammonia resistant. For example, they may be made from metal (e.g., stainless steel, high-carbon steel, aluminum, or titanium) or plastic (e.g., PTFE or PFA). The inserts may each be made from different materials or the same material. One or more inserts may comprise at least one baffle made from each of the above materials in any combination. The shape and dimensions of the inserts are not important as long as they are gas impermeable.

[0053] In one embodiment, the flow structure may include a substructure formed of a substrate at least partially filled with a single mass of an adsorbent containing silica gel, the substructure being in fluid communication with one or more partially purified cracked gas inlets and one or more purified cracked gas outlets. For example, the substructure may be a series of plastic or metal inner walls that meander (coil or wrap) through substantially the entire internal volume of the first container, thus essentially forming a long tube that forces the gas to flow through almost the entire internal volume of the first container. The substructure may be made of the same material as the first container, or of a different material. The material may be ammonia resistant. For example, it may be made of metal (e.g., stainless steel, high carbon steel, aluminum, or titanium) or plastic (e.g., PTFE or PFA). The substructure may be made of a composite of these materials.

[0054] Those skilled in the art will understand that any of the above-described flow structures can be combined with any other, or in fact all, of the listed embodiments, without limitation. For example, a flow structure may include: • One or more baffles and one or more inserts, • One or more baffles and one or more permeable tubes, • One or more baffles and substructures, • One or more baffles, one or more inserts, and one or more permeable tubes, • One or more baffles, one or more inserts, and substructures, • One or more baffles, one or more permeable tubes, and substructures, • One or more baffles, one or more permeable tubes, one or more inserts, and substructures.

[0055] The first container contains a single mass of adsorbent containing silica gel. As discussed earlier, the single mass of adsorbent may be a homogeneous mass of adsorbent containing silica gel. The single mass of adsorbent may contain other components, but in some embodiments, at least 30% of the mass is silica gel. Silica gel is a well-known entity and is often used for water adsorption in a variety of applications. Silica gel readily adsorbs ammonia, and the applicants have found that, surprisingly, small amounts of silica gel can purify a partially purified decomposition gas stream and remove ammonia from it. This is particularly useful when the untreated decomposition gas has already been purified (at least partially) (e.g., in a gas separator), but a very high level of purity is required for use downstream of hydrogen gas. Preferably, the internal volume of the first container is at least partially filled with a single mass of adsorbent containing silica gel. In some embodiments, the silica gel may be in the form of silica gel beads, silica gel powder, and / or silica gel granules, or a combination thereof. Silica beads of uniform size are particularly preferred because the uniform bead size reduces channeling of the gas stream and reduces pressure drop. Suitable beads can be of any size, but are typically in the range of 3-5 mm in diameter. The silica gel in the filter assembly adsorbs ammonia and, once fully saturated, can be regenerated at least partially, meaning it is reusable.

[0056] In some embodiments, the indicator is mixed with / embedded in silica gel (or a mass of silica gel) so as to be adsorbed into the silica gel (or a mass of silica gel), so as to be placed on top of it, or so as to its vicinity. The indicator may be an ammonia indicator, a hydration indicator, a pH indicator, or any combination thereof. Moisture indicators typical of silica gel products can serve this purpose due to the similarity of their indicator functions. Several suitable indicators are known in the art and are suitable for this purpose. For example, silica gel may be mixed with cobalt(II) chloride, as well as non-toxic organic compounds (e.g., methyl violet) and iron salts. These indicators change color when the chemical additives undergo a chemical change or a change in pH. In practice, this means that it is possible to observe when the silica gel beads are saturated with ammonia, giving a visual indicator that the silica gel is almost used up and needs to be replaced and regenerated. Using an inspection window and / or when one or more walls contain transparent plastic, the change in the color of the indicator can be easily evaluated by those skilled in the art to provide a high level of warning that the filter assembly may need to be replaced to prevent ammonia leakage into the purified decomposition gas.

[0057] One or more filter assemblies are readily replaceable within the apparatus of the present invention and may be considered as cartridges. In some embodiments, each of the one or more filter assemblies is fluidly connected to a common partially purified cracked gas conduit and a common purified cracked gas conduit and is releasably fixed to the apparatus. As is known to those skilled in the art, any suitable fixture can be used to achieve this releasable fixing of each filter assembly. In some embodiments, each filter assembly is fluidly connected to the apparatus via valves. The valves are one or more partially purified cracked gas inlet valves and one or more purified cracked gas outlet valves. These valves allow for the isolation of each filter assembly, and as a result, when a single mass of adsorbent within it becomes nearly saturated with ammonia, the gas flow may be stopped, allowing for depressurization and removal of each filter assembly. This is advantageous over systems such as pressure swing adsorption (PSA) apparatus because the overall downtime can be reduced due to the simple replacement of each filter assembly. In embodiments where one or more filter assemblies comprise multiple filter assemblies, one filter assembly can be isolated and removed, while the other filter assemblies among the multiple filter assemblies continue to operate the apparatus to purify the partially purified cracked gas arriving from one or more gas separators. This is a technical advantage over prior art systems using PSA devices. Prior art systems are generally not fixed in a removable manner to the apparatus and instead require a more complex system architecture to allow “pressure fluctuations” within the PSA to release impurities from the adsorbent, which can then be purged into the waste gas stream. In addition, PSA devices are generally not fixed in a removable manner. Instead, the adsorbent within them is removed and replaced while the PSA device is isolated from the rest of the apparatus for hydrogen production. Replacing an actual PSA device is a far more complex procedure than replacing the filter assemblies of the present invention. Therefore, further purifying the partially purified cracked gas by having filter assemblies as in the apparatus of the present invention is advantageous compared to, for example, having two PSA devices connected in series.

[0058] In some embodiments, the filter assembly further comprises an ammonia gas sensor. This makes it possible to detect extremely small amounts of ammonia concentration in the gas entering and leaving the filter assembly. Typically, the sensor is located downstream of one or more purified cracking gas outlets and is in fluid communication with them. This means that the sensor is positioned to detect ammonia in the purified cracking gas flowing from the filter assembly and can detect whether ammonia is beginning to leave the internal volume of the first container. This prevents damage to downstream equipment by allowing the filter to be replaced before a significant amount of ammonia gas leaks downstream. Various sensors are available, for example, a tuned infrared sensor or an optical feedback cavity-enhanced absorption spectrometer (also called an optical feedback cavity-enhanced absorption spectrometer), which is known to those skilled in the art and is a standard sensor for measuring ammonia in parts per billion units. In some embodiments, a pair of sensors can be used, one positioned upstream of the first container and the other downstream of the first container. Such sensors can measure the ammonia concentrations on both sides and / or calculate the difference between them. In some embodiments, a single sensor is located downstream of one or more purified cracked gas outlets and is in fluid communication with one or more purified cracked gas outlets. For example, it may be connected to one or more purified cracked gas outlets via a conduit containing a regulator that reduces the pressure of the sampled gas to a pressure suitable for the sensor. In some embodiments, an alarm is configured to trigger when a set concentration of ammonia is detected. Figure 10 shows a gas separator 1016 in fluid communication with a filter assembly 1001 via a common partially purified cracked gas flow conduit 1012b, the filter assembly in fluid communication with a common purified cracked gas flow conduit 1013, and an ammonia gas sensor 1018 in fluid communication with the common purified cracked gas flow conduit 1013 via a regulator 1017. As indicated by the arrows, the untreated cracked gas enters the gas separator 1016, and the nitrogen and hydrogen gases are at least partially removed to produce a partially purified cracked gas containing hydrogen, nitrogen, and ammonia gases.The partially purified cracked gas exits the gas separator 1016 and flows through a common partially purified cracked gas conduit 1012b to the filter assembly 1001. A single mass of adsorbent containing silica gel in the filter assembly 1001 essentially removes any residual ammonia gas, producing purified cracked gas, which then exits the filter assembly 1001 and flows through the purified cracked gas conduit 1013. A portion of the purified cracked gas flows through the regulator 1017 to the ammonia gas sensor 1018. The ammonia gas sensor 1018 detects and signals whether the ammonia in the purified cracked gas exceeds a threshold determined and set by those skilled in the art. As shown in the figure, the majority of the purified cracked gas flows through the regulator 1017 to a downstream system or storage device.

[0059] In some embodiments, one or more filter assemblies may be multiple filter assemblies. An exemplary apparatus is shown in Figure 9. Each of the multiple filter assemblies downstream of the cracker and one or more gas separators 916 may be connected to a common partially purified cracked gas conduit 912b via a first valve 914. This valve can block the flow of partially purified cracked gas from the common partially purified cracked gas conduit 912b to the internal volume of the first container via one or more partially purified cracked gas inlets. This means that in an apparatus for producing hydrogen gas, the flow can be redirected from one filter assembly to a different downstream assembly, such as a second filter assembly. Thus, each filter assembly may be isolated from the common partially purified cracked gas conduit 912b without affecting the operation of the apparatus.

[0060] In some embodiments, one or more filter assemblies are each fluidly connected to a common purified cracking gas conduit 913 via one or more purified cracking gas outlets, and each filter assembly has a second valve 915 between one or more purified cracking gas outlets and the common purified cracking gas conduit 913. This means that in an apparatus for generating hydrogen gas, it is possible to prevent the flow from leaving the filter assembly, for example, if leakage is detected in the common purified cracking gas conduit near one or more purified cracking gas outlets. In other words, each filter assembly can be separated from the common purified cracking gas conduit 913 without affecting the operation of the apparatus.

[0061] In some embodiments, the hydrogen generator comprises one or more filter assemblies having the first valve and the second valve described above. By shutting off both valves for any given filter assembly, the filter assembly can be completely isolated from the rest of the apparatus, thereby allowing such a filter assembly to be safely replaced in place as described above.

[0062] In further embodiments, the common untreated decomposition gas flow conduit comprises a gas separator for separating the untreated decomposition gas into its constituent gases of hydrogen, nitrogen, and ammonia. Such a gas separator is positioned between the ammonia decomposer and one or more filter assemblies and is in fluid communication with them. In some embodiments, the gas separator may be a pressure swing adsorption device as described above, and / or comprise a palladium filter and / or a catalytic conversion reactor and / or a temperature swing adsorption device and / or a hollow fiber membrane filter. Such gas separators are known in the art. See, for example, Patent Documents 7, 8, 9, and Non-Patent Document 1 (incorporated herein by reference). One or more gas separators are used to remove most of the nitrogen and ammonia from the untreated decomposition gas before it enters one or more filter assemblies to remove the remaining ammonia. By having a gas separator between the cracker and one or more filter assemblies, it is possible to remove most of the nitrogen and ammonia from the gas mixture leaving the ammonia cracker, and thus most of the ammonia is removed before the partially purified cracked gas stream enters one or more filter assemblies, thus extending the life of a single mass of adsorbent containing silica gel in each filter assembly. Such a gas separator may be located in a separate conduit from the ammonia cracker, be integrated with the ammonia cracker, or be integrated with one or more filter assemblies. In any case, the untreated cracked gas must flow through the gas separator when leaving the ammonia cracker and before entering one or more filter assemblies. In some embodiments, the gas separator may be selected from the group consisting of a metal hydride-based purification apparatus, a low-temperature distillation apparatus with a fractional distillation column apparatus, or any combination thereof.

[0063] One or more gas separators may include a PSA having a first pressure swing adsorbent for adsorbing nitrogen gas, a second pressure swing adsorbent for adsorbing ammonia, and a third pressure swing adsorbent for adsorbing water. In a typical PSA system, the untreated decomposed gas flows first through the third pressure swing adsorbent to remove water, then through the second pressure swing adsorbent to remove ammonia, and then through the first pressure swing adsorbent to remove nitrogen. Thus, the adsorbent mass in the pressure swing adsorbent may be stacked from bottom to top as the third pressure swing adsorbent, the second pressure swing adsorbent, and the first pressure swing adsorbent, and the apparatus is arranged so that the untreated decomposed gas enters the bottom of the apparatus, flows through the third pressure swing adsorbent, the second pressure swing adsorbent, and the first pressure swing adsorbent in this order, produces a partially purified decomposed gas, and flows out through an outlet at the top of the apparatus. The pressure swing adsorbent may include any number of containers, as long as the apparatus is configured to have at least the first pressure swing adsorbent and the second pressure swing adsorbent, and the feed gas (untreated decomposed gas) flows through both. If multiple containers exist, each container may be equipped with a first pressure swing adsorbent, a second pressure swing adsorbent, and optionally a third pressure swing adsorbent, as described above.

[0064] In some embodiments, one or more gas separators may include palladium filters. In further embodiments, the palladium filters are in fluid communication with a heat exchanger positioned between the palladium filters and one or more filter assemblies, and the heat exchanger is in fluid communication with one or more filter assemblies. Such a device acts to cool the partially purified decomposition gas exiting the palladium filters before it enters one or more filter assemblies.

[0065] In some embodiments, there are multiple filter assemblies according to the first embodiment, which are fluidly connected to one or more gas separators via a common partially purified cracked gas flow conduit. These can be connected in parallel, in series, or both. The advantage of having multiple filter assemblies is that the system has redundancy in case of failure. Furthermore, when connected in parallel, if a mass of adsorbent containing silica gel in any of the filter assemblies is consumed or nearly consumed, the adsorbent can be separated and replaced using the valves described above. Once separated, the gas passes through another filter assembly among the multiple filter assemblies, and the separated assembly is replaced in the process. This allows for safe continuous operation of the apparatus without requiring shutdown of the apparatus and without the associated loss of productivity. The advantage of fluidly connecting multiple filter assemblies in series is that if the first filter assembly fails, ammonia is easily adsorbed by the second filter assembly, thus preventing impact on downstream assemblies in the apparatus. This is an advantage over the PSA described above.

[0066] A further aspect of the present invention provides a system for generating electricity using ammonia, comprising the apparatus of the preceding aspect and a hydrogen fuel cell, wherein the hydrogen fuel cell is in fluid communication with the hydrogen production system via a common purified cracking gas flow conduit. In this system, the ammonia cracker produces hydrogen gas purified by a gas separator and one or more filter assemblies, and from one or more filter assemblies, the purified hydrogen gas flows to a hydrogen fuel cell, where it is readily converted into electricity. An advantage of such a system is that there is no need to store hydrogen. Instead, energy can be transported as ammonia and converted on-site. Ammonia is easier and safer to transport than hydrogen gas, and therefore this configuration makes it possible to supply electricity remotely without the expensive infrastructure required for the transport and storage of hydrogen gas. Figure 11 shows an exemplary system comprising an ammonia cracker 1111, which is in fluid communication with a gas separator 1116 via a common untreated cracked gas conduit 1112a; a gas separator 1116, which is in fluid communication with a filter assembly 1101 via a partially purified cracked gas conduit 1112b; and a hydrogen fuel cell 1119, which is in fluid communication with the filter assembly 1101 via a common purified cracked gas conduit 1113. As indicated by the arrows, ammonia gas flows into the heating chamber of the ammonia cracker 1111, where it comes into contact with an ammonia decomposition catalyst and is decomposed into untreated cracked gas consisting of nitrogen gas and hydrogen gas, which contains unreacted residual ammonia gas. The untreated cracked gas exits the ammonia cracker 1111 via a common untreated cracked gas conduit 1112a and flows into a gas separator 1116, which removes most of the nitrogen gas and ammonia gas to produce partially purified cracked gas containing nitrogen gas, hydrogen gas, and ammonia gas. The partially purified cracked gas exits the gas separator 1116 and is transported via a common partially purified cracked gas conduit 1112b to the filter assembly 1101, where a single mass of adsorbent containing silica gel essentially removes residual ammonia from the partially purified cracked gas to produce purified cracked gas. The purified cracked gas then flows through a common purified cracked gas conduit 1113 to the hydrogen fuel cell 1119.The hydrogen gas in the purified cracking gas is used for power generation by fuel cells. Suitable hydrogen fuel cells are well known in the art. For example, see Patent Document 10 (incorporated herein by reference). In some embodiments, nitrogen may remain in the purified cracking gas, but this is not important as it does not adversely affect the fuel cell device.

[0067] A further aspect of the present invention provides a process for producing purified cracked gas of high-purity hydrogen, the process comprising: a first purification step of supplying ammonia gas to an ammonia cracker having fluid communication with a common untreated cracked gas conduit to produce untreated cracked gas containing hydrogen gas, nitrogen gas, and ammonia gas; and transporting the untreated cracked gas through the common untreated cracked gas conduit to one or more gas separators, the one or more gas separators at least partially removing the ammonia gas and nitrogen gas from the untreated cracked gas to produce partially purified cracked gas; and a second purification step of transporting the partially purified cracked gas through a common partially purified cracked gas conduit to one or more filter assemblies, the one or more Each of the filter assemblies has a first container having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets, the one or more partially purified cracked gas inlets being in fluid communication with the common partially purified cracked gas conduit, the first container containing a single mass of adsorbent containing silica gel, the one or more partially purified cracked gas inlets and the one or more purified cracked gas outlets being arranged so that the partially purified cracked gas flows through the single mass of adsorbent, the single mass of adsorbent selectively adsorbs the ammonia in the partially purified cracked gas to produce a purified cracked gas, the partially purified cracked gas being transported through the one or more filter assemblies at process pressure, the process pressure being substantially constant.

[0068] In this embodiment, the ammonia cracker uses an ammonia decomposition catalyst to decompose ammonia into untreated decomposition gas containing nitrogen and hydrogen gases. Since this is an equilibrium reaction, ammonia gas also remains in the untreated decomposition gas. Such ammonia crackers are well known in the art (see, for example, Patent Document 6 (incorporated herein by reference)). The untreated decomposition gas exits the reaction chamber of the ammonia cracker under pressure and enters a common untreated decomposition gas conduit, which leads to one or more gas separators that are in fluid communication with the ammonia cracker via the common untreated decomposition gas conduit. One or more gas separators remove at least a portion of the nitrogen gas and / or at least a portion of the ammonia gas to produce partially purified decomposition gas. The partially purified decomposition gas exits the one or more gas separators under pressure and enters a common partially purified decomposition gas conduit, which leads to one or more filter assemblies having the features described in the first embodiment. A single mass of silica gel adsorbent selectively adsorbs ammonia gas in a partially purified cracked gas to produce a purified cracked gas, which then flows downstream from one or more assemblies for further use or storage. The term "selectively" means that while negligible proportions of nitrogen and hydrogen gases may be adsorbed by the single mass of adsorbent, the majority of the gas adsorbed by the single mass of adsorbent is ammonia gas.

[0069] The partially purified cracked gas flows through each of one or more filter assemblies at process pressure. This is the pressure of the partially purified cracked gas entering one or more filter assemblies during the operation of the apparatus, when the untreated cracked gas and partially purified cracked gas are actively produced by the ammonia cracker and one or more gas separators, respectively. During the operation of the apparatus, the process pressure is constant. This means that the process pressure does not change substantially. This is in contrast to systems that require pressure swing to release adsorbed impurities for removal and disposal, such as systems using PSA equipment. In some embodiments, the process pressure is 35 bar or less. In some embodiments, the process pressure may be 30 bar or less, 25 bar or less, 20 bar or less, 15 bar or less, 10 bar or less, 5 bar or less, 4 bar or less, 3 bar or less, 2 bar or less, or 1 bar or less. In some embodiments, bar is barg. In some embodiments, the process pressure is greater than atmospheric pressure and less than 35 bar.

[0070] In some embodiments, at least one of one or more gas separators is a pressure swing adsorbent comprising a first pressure swing adsorbent and a second pressure swing adsorbent, which operates at a pressure equal to the process pressure, adsorbs nitrogen from the untreated decomposition gas onto the first pressure swing adsorbent and adsorbs ammonia from the untreated decomposition gas onto the second pressure swing adsorbent, and the pressure changes (e.g., decreases) to release the nitrogen and ammonia as waste gas discharged from the pressure swing adsorbent through a waste gas outlet that is in fluid communication with a common waste gas flow conduit. The pressure swing adsorbent operates at the same pressure as one or more filter assemblies, but when purged, it undergoes its characteristic pressure swing (i.e., pressure change) to release impurities for removal. The first pressure swing adsorbent may be a non-zeolite adsorbent for adsorbing ammonia, and the second pressure swing adsorbent may be a zeolite adsorbent for adsorbing nitrogen. The PSA apparatus may include further pressure swing adsorbents. For example, in some embodiments, the pressure swing adsorbents include a third pressure swing adsorbent for adsorbing water. Suitable adsorbents are known. For example, alumina may be used to remove water. With respect to the arrangement of two or three pressure swing adsorbents, the apparatus is configured such that the untreated decomposition gas first flows through a third pressure swing adsorbent (if present), then through a second pressure swing adsorbent, and then through a first pressure swing adsorbent. In a typical apparatus, the untreated decomposition gas flows into the bottom of the apparatus through the inlet, flows through each layer as described above to produce a partially purified decomposition gas, which then flows out through the outlet to a further downstream system as described herein. The adsorbents may be layered or in separate clumps in the same container or in separate containers. Considering the apparatus as a whole, there are always more than one clump of adsorbent, typically two or three as described above.

[0071] In some embodiments, at least one of one or more gas separators is a pressure swing adsorption apparatus, the pressure swing adsorption apparatus comprising a plurality of vessels, each vessel comprising (or containing) a first pressure swing adsorbent for adsorbing nitrogen gas from untreated decomposition gas, a second pressure swing adsorbent for adsorbing ammonia gas from untreated decomposition gas, and optionally comprising (or containing) a third pressure swing adsorbent for adsorbing water, the plurality of vessels comprising a first pair of vessels comprising a first vessel and a second vessel, the process comprising the sequence of adsorption step, first equalization step, blowdown step, purge step, second equalization step, and backfill step as follows:

[0072] The adsorption step includes the steps of: fluidly connecting the first of a first pair of containers to a common untreated decomposed gas conduit and a partially purified decomposed gas conduit, and transporting the untreated decomposed gas to the first container at process pressure, wherein ammonia gas and nitrogen gas (and optionally water) in the untreated decomposed gas are at least partially removed to produce partially purified decomposed gas; and transporting the partially purified decomposed gas from the first container to a common partially purified decomposed gas conduit at process pressure.

[0073] The first equalization step includes the steps of fluidly isolating the first vessel from a common partially purified cracked gas conduit and a common untreated cracked gas conduit, and fluidly connecting the first vessel to a second vessel of a plurality of vessels, wherein the second vessel is at atmospheric pressure, the first vessel is depressurized, the second vessel is pressurized, and the first and second vessels are at half the process pressure.

[0074] The blowdown step includes fluidly isolating a first vessel from a second vessel, fluidly connecting the first vessel to a common waste gas conduit, and transporting waste gas containing (or consisting of) nitrogen gas and ammonia gas from the first vessel to the common waste gas conduit, wherein the first vessel is subjected to further depressurization so that the first vessel is at atmospheric pressure.

[0075] The purging step includes the steps of fluidly connecting the first vessel to a common purge gas conduit, transporting purge gas at atmospheric pressure to remove residual waste gas from the first vessel via a common waste gas conduit, and fluidly isolating the first vessel from the common waste gas conduit and the common purge gas conduit. The purge gas may be, for example, hydrogen gas. This may be supplied from the apparatus of the present invention itself or from another source.

[0076] The second equalization step is a step of fluidly connecting the first vessel to the second vessel, the first vessel being pressurized and the second vessel being depressurized, so that the first and second vessels are at half the process pressure, since the second vessel is at process pressure.

[0077] The backfill step includes fluidly isolating the first vessel from the second vessel, fluidly connecting the first vessel to a common backfill gas conduit, transporting backfill gas such that the first vessel is pressurized and reaches process pressure, and fluidly isolating the first vessel from the common backfill gas conduit. The backfill gas may be, for example, hydrogen gas, which may be obtained from the apparatus of the present invention or from another source.

[0078] Next, the first vessel is fluidly connected to a common untreated cracked gas conduit and a common partially purified cracked gas conduit for the adsorption step in the new PSA cycle, according to the sequence described above.

[0079] During these steps, the partially purified cracked gas is transported through one or more filter assemblies at process pressure. This demonstrates that while pressure swing adsorbents undergo their characteristic pressure swing, no such swing occurs in the one or more filter assemblies of this process. Instead, they operate at a substantially constant pressure.

[0080] In some embodiments, the multiple vessels in the pressure swing adsorption device may comprise a first pair of vessels and a second pair of vessels, the first pair comprising the aforementioned first and second vessels, and the second pair comprising a third and a fourth vessel. The third vessel undergoes the same sequence as described for the first vessel, and the fourth vessel operates in the same manner as described for the second vessel. Each pair of vessels operates according to the sequence described above, but their operations are offset. This operation allows for the consistent delivery of partially purified cracked gas to one or more filter assemblies via a common partially purified cracked gas conduit. Each vessel undergoes the same sequence, but is offset to perform its functions as described above.

[0081] While the first container undergoes the adsorption step, the second container undergoes the purging step. Next, the first and second containers undergo the equalization step. Then, while the first container undergoes the blowdown step, the second container undergoes the backfill step. Next, the first container undergoes the purging step and the second container undergoes the adsorption step. Then, each container undergoes the second equalization step. Finally, the first container undergoes the backfill step and the second container undergoes the blowdown step. This cycle is repeated during the process of the present invention.

[0082] If the process includes a second pair of containers, including a third and a fourth container, they act as counterparts in the same manner as described above for the first and second containers. However, as stated above, their cycles are offset. For example, when the first container is in the first adsorption stage, the third container undergoes the first equalization step with the fourth container as described above, and then undergoes a backfill step while the fourth container undergoes its blowdown step. When the first container has undergone the first equalization step and blowdown step, the third container undergoes its adsorption step, and the fourth container undergoes its purge step. When the first container has undergone its purge step, the third container undergoes the second equalization step with the fourth container as described above, followed by a blowdown step, and the fourth container undergoes its backfill step. When the first container has undergone its second equalization step and backfill step, the third container undergoes its purge step, and the fourth container undergoes its adsorption step. As is clear, the third and fourth containers operate when the first and second containers move relative to each other. Each pair can be considered as two corresponding containers, each having a first and a second container that undergo the sequences described above, the third container undergoing the sequence described for the first container, and the fourth container undergoing the sequence described for the second container.

[0083] In some embodiments, a common backfill gas conduit is used to fluidly connect the first and second vessels between the first and second equalization steps. Alternatively, there may be a separate conduit independent of the common backfill gas conduit connecting the first and second vessels. If there is a first pair of vessels and a second pair of vessels, the common backfill gas conduit may be used to fluidly connect the first and second vessels, and may also be used to fluidly connect the third and fourth vessels. In some embodiments, the partially purified cracked gas is transported from a plurality of gas separators to one or more filter assemblies. In other words, one or more gas separators comprise a plurality of gas separators, each of which transports the partially purified cracked gas to one or more filter assemblies. These may be any of the gas separators discussed in the first aspect of the invention, and may be any combination or number. For example, in some embodiments, the process includes at least two of one or more gas separators, which are pressure swing adsorbents, the first of which is fluidically disconnected from a common untreated decomposed gas conduit and a partially purified decomposed gas conduit, and the second of which is fluidly connected to the untreated decomposed gas conduit and the partially purified decomposed gas conduit. This is the case when one of the pressure swing adsorbents undergoes a maintenance cycle while the other continues normal operation to supply partially purified decomposed gas to one or more filter assemblies at process pressure. This process enables continuous operation of the apparatus for producing high-purity hydrogen gas. In some embodiments, the process includes the step of transporting the untreated decomposed gas through a common untreated decomposed gas conduit to one or more gas separators, the gas separators comprising a first pressure swing adsorbent and a second pressure swing adsorbent, wherein during operation, the first pressure swing adsorbent is fluidically disconnected from the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit, while during operation, the second pressure swing adsorbent remains fluidly connected to the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit.In other words, when the first pressure swing adsorption device is disconnected from the device, the second pressure swing adsorption device remains connected and continues to operate at process pressure. As discussed, each PSA device may also include a third pressure swing adsorption device, such as alumina, for removing further pressure swing adsorptions, such as water.

[0084] In some embodiments, a single mass of adsorbent comprises at least 30% by mass of silica gel, and optionally, the adsorbent is substantially composed of silica gel. Thus, a single mass of adsorbent may contain at least 30% by mass, at least 40% by mass, at least 50% by mass, at least 60% by mass, at least 70% by mass, at least 80% by mass, or at least 90% by mass of silica gel. This may be essentially silica gel, or may consist of silica gel. What constitutes the remaining mass percent of the single mass of adsorbent is not important as long as it does not interfere with the function of silica gel.

[0085] In some embodiments, the partially purified decomposed gas is transported through one or more filter assemblies at a process temperature, which is 100°C or less. In some embodiments, the process temperature is between -50 to 90°C, -50 to 80°C, -50 to 70°C, -50 to 60°C, or 50 to 50°C. In some embodiments, the partially purified decomposed gas is transported to one or more filter assemblies via one or more heat exchangers, and the partially purified decomposed gas may be cooled to an appropriate process temperature before entering one or more filter assemblies.

Claims

1. A device for generating hydrogen, An ammonia cracker having one or more untreated cracked gas outlets that are in fluid communication with a common untreated cracked gas flow conduit, One or more gas separators are fluidly connected to the ammonia cracker via the common untreated cracked gas flow conduit and to the common partially purified cracked gas flow conduit, One or more filter assemblies having a first container, each having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets, wherein the one or more partially purified cracked gas inlets are in fluid communication with the one or more gas separators via a common partially purified cracked gas flow conduit, the first container contains a single mass of adsorbent containing silica gel, and the one or more partially purified cracked gas inlets and the one or more purified cracked gas outlets are arranged so that the partially purified cracked gas flows through the single mass of adsorbent when in use, A device equipped with the following features.

2. The apparatus according to claim 1, wherein one or more of the walls include metal.

3. The apparatus according to claim 2, wherein the metal is stainless steel, high carbon steel, aluminum, or titanium.

4. The apparatus according to claim 3, wherein the metal includes a polymer coating.

5. The apparatus according to claim 4, wherein the polymer coating is a fluorinated polymer, preferably PTFE or PFA.

6. The apparatus according to any one of claims 1 to 5, wherein the one or more walls include plastic, optionally transparent plastic and / or opaque plastic.

7. The apparatus according to claim 6, wherein the plastic is a fluorinated plastic or polycarbonate.

8. The apparatus according to any one of claims 1 to 7, wherein each filter assembly further comprises an inspection window for viewing a single clump of the adsorbent.

9. The apparatus according to any one of claims 1 to 8, further comprising an auxiliary container containing a second mass of an adsorbent comprising silica gel, wherein the auxiliary container is located downstream of the first container via one or more purified decomposition gas outlets and is in fluid communication with the first container, and the auxiliary container further comprises a second inspection window for viewing the second mass of the adsorbent.

10. The apparatus according to claim 8, wherein one or more of the walls further comprises an inspection window.

11. The apparatus according to claim 10, wherein the inspection window is located near at least one of the one or more purified decomposition gas outlets.

12. The apparatus according to claim 10 or 11, wherein the inspection window has a portion adjacent to at least one of the one or more partially purified and decomposed gas inlets.

13. The apparatus according to any one of claims 1 to 12, further comprising a flow structure for lengthening the transport path of the partially purified decomposed gas through a single mass of the adsorbent.

14. The aforementioned flow structure is, One or more permeable tubes are placed within a single mass of the adsorbent and connected at one end to one or more partially purified and decomposed gas inlets, One or more baffles extending from one or more walls of the filter assembly, One or more inserts placed inside the container, The container comprises a substructure formed of a substrate that forms an internal volume at least partially filled with a single mass of the adsorbent, the substructure having one or more inserts that are in fluid communication with the one or more partially purified cracked gas inlets and the one or more purified cracked gas outlets, or Any of the above combinations The apparatus according to claim 13, selected from the group consisting of the following.

15. The apparatus according to any one of claims 1 to 14, wherein the silica gel comprises silica gel beads, silica gel powder, and / or silica gel granules.

16. The apparatus according to any one of claims 1 to 15, further comprising an indicator adsorbed on the silica gel, disposed on the silica gel, and / or disposed proximally to the silica gel.

17. The apparatus according to any one of claims 1 to 16, further comprising an ammonia gas sensor.

18. The apparatus according to claim 17, wherein the ammonia gas sensor is located downstream of one or more purified cracking gas outlets and is in fluid communication with the one or more purified cracking gas outlets.

19. The apparatus according to claim 18, wherein the ammonia gas sensor is connected to one or more purified decomposition gas outlets via a regulator.

20. The apparatus according to any one of claims 1 to 19, wherein each of the one or more filter assemblies is in fluid communication with the common partially purified and decomposed gas conduit via the one or more partially purified and decomposed gas inlets, and each filter assembly has a first valve between the one or more partially purified and decomposed gas inlets and the common partially purified and decomposed gas conduit.

21. The apparatus according to any one of claims 1 to 20, wherein each of the one or more filter assemblies is in fluid communication with a common purified decomposition gas conduit via the one or more purified decomposition gas outlets, and each filter assembly has a second valve between the one or more purified decomposition gas outlets and the common purified decomposition gas conduit.

22. The apparatus according to any one of claims 1 to 21, wherein the one or more gas separators comprises a pressure swing adsorption device and / or a palladium filter and / or a catalytic conversion reactor and / or a temperature swing adsorption device and / or a hollow fiber membrane filter.

23. The apparatus according to any one of claims 1 to 22, wherein the one or more gas separators are located near the ammonia cracker or are integrated with the ammonia cracker.

24. The apparatus according to any one of claims 1 to 23, wherein more than 30% of the single mass of the adsorbent is silica gel, and optionally, the single mass of the adsorbent is essentially composed of silica gel.

25. A system for generating electricity using ammonia, - An apparatus for generating hydrogen according to any one of claims 1 to 24, • Hydrogen fuel cell, A hydrogen fuel cell that is in fluid communication with the apparatus for generating hydrogen via the aforementioned common purified cracking gas flow conduit, A system that includes these features.

26. A process for producing purified decomposition gas of high-purity hydrogen, - A step of supplying ammonia gas to an ammonia cracker having one or more untreated cracked gas outlets that are in fluid communication with a common untreated cracked gas flow conduit to generate untreated cracked gas containing hydrogen gas, nitrogen gas, and ammonia gas, - A first purification step comprising the step of transporting the untreated decomposition gas to one or more gas separators via the common untreated decomposition gas flow conduit, wherein the one or more gas separators at least partially remove the ammonia gas and the nitrogen gas from the untreated decomposition gas to produce a partially purified decomposition gas, - A second purification step comprising the step of transporting the partially purified cracked gas to one or more filter assemblies via a common partially purified cracked gas conduit, wherein each of the one or more filter assemblies has a first container having one or more walls, one or more partially purified cracked gas inlets, and one or more purified cracked gas outlets, the one or more partially purified cracked gas inlets being in fluid communication with the common partially purified cracked gas conduit, the first container containing a single mass of adsorbent containing silica gel, the one or more partially purified cracked gas inlets and the one or more purified cracked gas outlets being arranged so that the partially purified cracked gas flows through the single mass of adsorbent, and the single mass of adsorbent selectively adsorbs the ammonia in the partially purified cracked gas to produce purified cracked gas, Includes, The partially purified cracked gas is transported through one or more filter assemblies at process pressure, the process pressure being substantially constant.

27. The process according to claim 26, wherein the process pressure is 35 bar or less.

28. At least one of the one or more gas separators is a pressure swing adsorption device, the pressure swing adsorption device comprises a plurality of containers, each container comprising a first pressure swing adsorbent for adsorbing nitrogen gas from the untreated decomposition gas, a second pressure swing adsorbent for adsorbing ammonia gas from the untreated decomposition gas, and optionally a third pressure swing adsorbent for adsorbing water, the plurality of containers comprising a first pair of containers including the first container and the second container, the process is, (a) Fluidly connecting the first of the first pair of containers to the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit, and transporting the untreated decomposed gas to the first container at process pressure, wherein the ammonia gas and nitrogen gas (and optionally water) in the untreated decomposed gas are at least partially removed to produce the partially purified decomposed gas; (b) A step of transporting the partially purified cracked gas from the first container to the common partially purified cracked gas flow conduit at the process pressure, (c) A step of fluidly isolating the first container from the common partially purified decomposed gas conduit and the common untreated decomposed gas conduit, (d) A step of fluidly connecting the first container to the second container of the first pair of containers, wherein the second container is at atmospheric pressure, so the first container is depressurized, the second container is pressurized, and the pressure of the first and second containers is half of the process pressure. (e) A step of fluidly isolating the first container from the second container, fluidly connecting the first container to a common waste gas conduit, and transporting waste gas containing nitrogen gas and ammonia gas from the first container to the common waste gas conduit, wherein the first container is subjected to further depressurization so that the first container is at atmospheric pressure. (f) A step of fluidly connecting the first container to a common purge gas flow conduit, transporting purge gas at atmospheric pressure to the first container, and removing residual waste gas from the first container via the common waste gas flow conduit, (g) The step of fluidly isolating the first container from the common waste gas flow conduit and the common purge gas flow conduit, (h) A step of fluidly connecting the first container to the second container, wherein the second container is at the process pressure, so the first container is pressurized, the second container is depressurized, and the pressures of both the first and second containers are halved. (i) The steps of fluidly isolating the first container from the second container, fluidly connecting the first container to a common backfill gas flow conduit, and transporting backfill gas such that the first container is pressurized and the first container is at the process pressure, (j) The steps of fluidly isolating the first container from the common backfill gas conduit and fluidly connecting the first container to the common untreated decomposed gas conduit and the common partially purified decomposed gas conduit, Includes the sequence, The process according to claim 26 or 27, wherein during steps (a) to (j), the partially purified cracked gas is conveyed through one or more filter assemblies at the process pressure.

29. The process according to any one of claims 26 to 28, wherein the partially purified cracked gas is transported from a plurality of gas separators to one or more filter assemblies.

30. The process according to any one of claims 26 to 29, wherein the single mass of the adsorbent comprises at least 30% by mass of silica gel, and optionally, the single mass of the adsorbent is essentially composed of silica gel.

31. The process according to any one of claims 26 to 30, wherein the partially purified cracked gas is transported through one or more filter assemblies at a process temperature, the process temperature being 100°C or less, and preferably between -50°C and 50°C.

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