Ammonia decomposition skid-mounted hydrogen production system and process

Abstract

The invention relates to the field of hydrogen production through ammonia decomposition, and discloses an ammonia decomposition skid-mounted hydrogen production system and process. The system comprises a hydrogen preparation unit, a residual ammonia recovery and separation unit and a hydrogen purification unit, wherein the hydrogen preparation unit, the residual ammonia recovery and separation unit and the hydrogen purification unit are connected through pipelines; the hydrogen preparation unit comprises an ammonia decomposition reactor for performing ammonia decomposition reaction on raw material ammonia gas; the residual ammonia recovery and separation unit comprises a temperature swing adsorption device for adsorbing unreacted ammonia gas in the product gas; the system further comprises a heat exchange unit used for conducting heat exchange on the product gas and the raw material ammonia gas and / or conducting heat exchange on the product gas and mixed gas containing the raw material ammonia gas and unreacted ammonia gas. The hydrogen purification unit comprises a pressure swing adsorption device, an ammonia washing tank and a membrane separator; the pressure swing adsorption device is used for purifying residual products; the ammonia washing tank is used for washing the desorption gas; and the membrane separator is used for separating and purifying the hydrogen-nitrogen mixture. The system can improve the hydrogen production efficiency and the hydrogen purity.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen production by decomposing ammonia, and in particular to a skid-mounted hydrogen production system and process by decomposing ammonia. Background Art

[0002] As a green, low-carbon and abundant secondary energy source, hydrogen energy is gradually becoming an important carrier of global energy transformation and development. At the same time, hydrogen energy is a clean carbon-free energy source. With the rapid development of fuel cell vehicles in the future, the demand for hydrogen energy will also increase rapidly. However, at present, the development of the hydrogen energy industry still faces certain problems, that is, the uneven distribution of fossil resources and renewable energy in my country, and the regional imbalance between hydrogen sources and hydrogen use scenarios is more prominent. To solve this problem, the use of distributed hydrogen production technology can realize hydrogen production directly in hydrogen refueling stations, thereby reducing hydrogen costs and reducing transportation safety risks.

[0003] The advantages of using ammonia as a liquid hydrogen storage medium and developing ammonia decomposition distributed hydrogen production technology are that ammonia is easy to liquefy and has a mature transportation network. At the same time, the hydrogen storage density is high, and the decomposition products have no carbon emissions. Ammonia decomposition to produce hydrogen also faces some problems. At present, ammonia decomposition can only be heated by electric heating, which will face the problems of long heating time and high energy consumption. Due to the limited space of the skid, the hydrogen obtained by ammonia decomposition cannot obtain a high hydrogen yield only through pressure swing adsorption. In addition, ammonia as a raw material also has toxicity problems. If the ammonia is not completely decomposed, the direct removal of ammonia in the exhaust gas will cause certain safety hazards. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of low space-effective hydrogen production efficiency, tail gas safety hazards and high energy consumption in the skid-mounted ammonia decomposition hydrogen production system in the prior art, and to provide an ammonia decomposition skid-mounted hydrogen production system and process, which can improve the purity of hydrogen while improving the efficiency of ammonia decomposition hydrogen production, and has low energy consumption and no polluting gas emissions.

[0005] In order to achieve the above-mentioned object, the present invention provides a skid-mounted hydrogen production system for decomposing ammonia in a first aspect, wherein:

[0006] The system comprises a hydrogen preparation unit, a residual ammonia recovery and separation unit and a hydrogen purification unit, wherein the hydrogen preparation unit, the residual ammonia recovery and separation unit and the hydrogen purification unit are interconnected through pipelines;

[0007] The hydrogen preparation unit comprises an ammonia decomposition reactor, which is used to perform an ammonia decomposition reaction on the raw ammonia to obtain a product;

[0008] The residual ammonia recovery and separation unit comprises a temperature swing adsorption device, which is used to absorb unreacted ammonia in the product to obtain unreacted ammonia and residual products;

[0009] The system further comprises a heat exchange unit, which is used to exchange heat between the product gas and the raw ammonia gas, and / or, the heat exchange unit is used to exchange heat between the product gas and a mixed gas containing the raw ammonia gas and unreacted ammonia gas;

[0010] The hydrogen purification unit comprises a pressure swing adsorption device, an ammonia washing tank and a membrane separator, wherein the pressure swing adsorption device is used to purify the remaining product to obtain product hydrogen and analytical gas;

[0011] The ammonia washing tank is used to wash the analytical gas with water to obtain a dilute ammonia solution and a hydrogen-nitrogen mixture;

[0012] The membrane separator is used to separate and purify the hydrogen-nitrogen mixture to obtain purified hydrogen and by-product nitrogen.

[0013] A second aspect of the present invention provides a process for producing hydrogen by decomposing ammonia, wherein the process is carried out in the system described in the first aspect, wherein the process comprises:

[0014] S1, the raw ammonia gas enters the ammonia decomposition reactor of the hydrogen preparation unit through the heat exchange unit to undergo ammonia decomposition reaction to obtain product gas;

[0015] S2, the product gas enters the temperature swing adsorption device of the residual ammonia recovery and separation unit to adsorb the unreacted ammonia in the product gas to obtain unreacted ammonia and residual products;

[0016] S3, the remaining product enters the pressure swing adsorption device of the hydrogen purification unit for purification to obtain product hydrogen and analytical gas;

[0017] S4, the analyzed gas enters the ammonia washing tank of the hydrogen purification unit for water washing to obtain a mixture of dilute ammonia water and hydrogen and nitrogen;

[0018] S5. The hydrogen-nitrogen mixture enters a membrane separator for separation and purification to obtain purified hydrogen and by-product nitrogen.

[0019] The system provided by the present invention realizes hydrogen production by decomposing ammonia and internal circulation of heat within the limited space of the skid-mounted structure, thereby saving energy while reducing safety hazards and improving the yield and purity of hydrogen. At the same time, through the provision of an ammonia washing tank, the ammonia washing tank is used to wash ammonia for the analysis gas of the pressure swing adsorption device, thereby avoiding pollution of the environment by residual ammonia emissions, and the by-product dilute ammonia water can be used as plant fertilizer.

[0020] The system provided by the present invention adopts a heat exchange unit to use the product gas of the ammonia decomposition reaction to exchange heat with the raw ammonia gas and the mixed gas of the raw ammonia gas and unreacted ammonia gas (unreacted ammonia gas adsorbed by the temperature swing adsorption device), thereby reducing heat loss and achieving energy-saving effect through internal circulation heat exchange.

[0021] The system provided by the present invention uses a pressure swing adsorption device coupled with a membrane separator to purify hydrogen, thereby improving the hydrogen yield under skid-mounted conditions with limited space, while controlling the by-product to be nitrogen, which is directly discharged without pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the system of the present invention.

[0023] Description of Reference Numerals

[0024] 1-Liquid ammonia electrifier 11-First heat exchanger

[0025] 111- first heat exchange inlet 112- first heat exchange outlet

[0026] 113- Second heat exchange inlet 114- Second heat exchange outlet

[0027] 12- Second heat exchanger 121- Third heat exchange inlet

[0028] 122- third heat exchange outlet 123- fourth heat exchange inlet

[0029] 124- third heat exchange outlet 13- first buffer tank

[0030] 14- Second buffer tank 15- Third buffer tank

[0031] 16-Fourth buffer tank 2-Ammonia purifier

[0032] 3- Ammonia decomposition reactor 4- Temperature swing adsorption device

[0033] 5- Electric heater 6- First compressor

[0034] 7-Ammonia washing tank 8-Second compressor

[0035] 9- Pressure swing adsorption device 10- Membrane separator DETAILED DESCRIPTION

[0036] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0037] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit the present invention.

[0038] In the description of the present invention, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in a logical relationship of "or".

[0039] In the present invention, terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0040] Without further restrictions, in the present invention, the words "include", "comprises", "has" or other similar expressions used in sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0041] In the present invention, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of the present invention, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0042] In the description of the embodiments of the present invention, the space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present invention or facilitating the reader's understanding, and do not indicate or imply that the referred device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0043] Unless otherwise expressly specified or limited, in the description of the embodiments of the present invention, the terms such as "install", "connect", "connect", "fix", "set" and the like used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art of the technical field to which the present invention belongs, the specific meanings of the above terms in the embodiments of the present invention can be understood according to the specific circumstances.

[0044] The present invention provides a skid-mounted hydrogen production system for decomposing ammonia, such as Figure 1 As shown, the system includes a hydrogen preparation unit, a residual ammonia recovery and separation unit and a hydrogen purification unit, and the hydrogen preparation unit, the residual ammonia recovery and separation unit and the hydrogen purification unit are interconnected by pipelines;

[0045] The hydrogen preparation unit comprises an ammonia decomposition reactor 3, and the ammonia decomposition reactor 3 is used to perform an ammonia decomposition reaction on the raw ammonia to obtain a product gas;

[0046] The residual ammonia recovery and separation unit comprises a temperature swing adsorption device 4, and the temperature swing adsorption device 4 is used to adsorb unreacted ammonia in the product gas to obtain unreacted ammonia and residual products;

[0047] The system further comprises a heat exchange unit, which is used to exchange heat between the product gas and the raw ammonia gas, and / or, the heat exchange unit is used to exchange heat between the product gas and a mixed gas containing the raw ammonia gas and unreacted ammonia gas;

[0048] The hydrogen purification unit comprises a pressure swing adsorption device 9, an ammonia washing tank 7 and a membrane separator 10. The pressure swing adsorption device 9 is used to purify the remaining product to obtain product hydrogen and analytical gas;

[0049] The ammonia washing tank 7 is used to wash the analyzed gas with water to obtain a dilute ammonia solution and a hydrogen-nitrogen mixture;

[0050] The membrane separator 10 is used to separate and purify the hydrogen-nitrogen mixture to obtain purified hydrogen and by-product nitrogen.

[0051] The system provided by the present invention can realize the production of hydrogen by decomposing ammonia and the internal circulation of heat within the limited space of the skid-mounted structure, thereby saving energy and reducing safety hazards, and improving the yield and purity of hydrogen. At the same time, through the provision of an ammonia washing tank, the ammonia washing tank is used to wash ammonia for the analysis gas of the pressure swing adsorption device, thereby avoiding the pollution of ammonia emissions to the environment, and the by-product dilute ammonia water obtained can be used as plant fertilizer.

[0052] The system provided by the present invention adopts a heat exchange unit to use the product gas of the ammonia decomposition reaction to exchange heat with the raw ammonia gas and the mixed gas of the raw ammonia gas and backwash ammonia gas (unreacted ammonia gas adsorbed by the temperature swing adsorption device), thereby reducing heat loss and achieving energy-saving effect through internal circulation heat exchange.

[0053] The system provided by the present invention uses a pressure swing adsorption device coupled with a membrane separator to purify hydrogen, thereby improving the hydrogen yield under skid-mounted conditions with limited space, while controlling the by-product to be nitrogen, which is directly discharged without pollution.

[0054] The system provided by the present invention adopts a pressure swing adsorption device coupled with a membrane reactor. The product hydrogen obtained by separation of the pressure swing adsorption device is preferably selected as a part of the regenerated hydrogen to back-blow the adsorbed unreacted ammonia in the temperature swing adsorption device into the ammonia decomposition reactor, thereby avoiding ammonia emission and improving the hydrogen yield. The analytical gas containing a certain amount of hydrogen is passed into the membrane separator to separate and obtain purified hydrogen. Preferably, the purified hydrogen is re-entered into the hydrogen purification unit for secondary purification to reduce hydrogen loss, thereby improving the hydrogen recovery rate while ensuring the purity of the hydrogen.

[0055] In the present invention, it should be noted that the residual product refers to the product gas after the unreacted ammonia is removed, which is mainly a mixed gas of hydrogen and nitrogen, and has a residual ammonia content of less than 10 ppm. The present invention does not specifically limit the content of each component in the residual product.

[0056] In the present invention, there is no particular limitation on the form of ammonia used as the raw material for the ammonia decomposition reaction. Preferably, ammonia gas is selected to achieve gasification of the ammonia source liquid ammonia, obtain the raw material, and better improve the efficiency of hydrogen production by ammonia decomposition. Preferably, the hydrogen preparation unit also includes a liquid ammonia electrifier 1, which is used to gasify the ammonia source liquid ammonia into ammonia gas.

[0057] In order to purify ammonia and improve the efficiency of hydrogen production by ammonia decomposition, preferably, the hydrogen preparation unit further comprises an ammonia purifier 2, which is used to purify ammonia to obtain raw ammonia.

[0058] In the present invention, ammonia purification refers to trace amounts of water and oil in raw ammonia. The present invention does not particularly limit the specific operation methods and conditions for ammonia purification, and those skilled in the art can select them according to actual needs.

[0059] In the present invention, there is no special limitation on the arrangement of the liquid ammonia electrifier and the ammonia purifier, as long as the raw liquid ammonia can be gasified and purified. Preferably, the liquid ammonia electrifier 1 and the ammonia purifier 2 are connected in series through a pipeline. According to a specific embodiment of the present invention, the inlet of the liquid ammonia electrifier 1 is connected to an external ammonia source, the outlet of the liquid ammonia electrifier 1 is connected to the inlet of the ammonia purifier 2, and the outlet of the ammonia purifier 2 is connected to the inlet of the ammonia decomposition reactor 3. In the above manner, the external ammonia source liquid ammonia enters the liquid ammonia electrifier for gasification to obtain ammonia gas, the ammonia gas enters the ammonia purifier for purification to obtain raw ammonia gas, and the raw ammonia gas enters the ammonia decomposition reactor for ammonia decomposition reaction.

[0060] In the present invention, in order to improve the efficiency of the ammonia decomposition reaction, preferably, the ammonia decomposition reactor 3 is filled with an ammonia decomposition catalyst. The present invention does not particularly limit the type of ammonia decomposition catalyst. Preferably, the ammonia decomposition catalyst comprises a metal active component, an auxiliary agent and an alumina carrier. In the present invention, there is no particular limitation on the type of active metal. Preferably, the metal active component comprises Ru and a non-precious metal component, and the non-precious metal component is selected from at least one of Mn, Fe, Co, Ni, and Cu. In the present invention, there is no particular limitation on the type of auxiliary agent. Preferably, the auxiliary agent is selected from CeO 2 , MgO, CuO, CaO and La 2 O 3 At least one of. In the present invention, there is no particular limitation on the content of each component in the ammonia decomposition catalyst. Preferably, based on the total weight of the ammonia decomposition catalyst, the content of Ru is 0.1-2.5% by weight, the content of the non-precious metal component calculated as oxide is 0.1-10% by weight, the content of the auxiliary agent is 2-8% by weight, and the content of the alumina carrier is 69.5-97.8% by weight.

[0061] In the present invention, there is no particular limitation on the preparation method of the ammonia decomposition catalyst, and all conventional methods defined in the art are applicable to the present invention.

[0062] In the present invention, in order to improve the energy utilization rate in the ammonia decomposition skid-mounted hydrogen production system, the energy consumption of the ammonia decomposition skid-mounted hydrogen production system is reduced to achieve the purpose of energy saving. In the present invention, there is no special limitation on the number of heat exchange stages in the heat exchange unit. Preferably, it is a two-stage heat exchange. In the present invention, the number of heat exchangers is used as the heat exchange stage for schematic illustration. Preferably, the heat exchange unit includes a first heat exchanger 11 and a second heat exchanger 12. In the present invention, there is no special limitation on the arrangement of the first heat exchanger 11 and the second heat exchanger 12. Preferably, the first heat exchanger 11 and the second heat exchanger 12 are arranged between the ammonia purifier 2 and the ammonia decomposition reactor 3, and the first heat exchanger 11 and the second heat exchanger 12 are arranged in series.

[0063] According to a specific embodiment of the present invention, Figure 1 As shown, preferably, the first heat exchanger 11 is provided with a first heat exchange inlet 111 , a first heat exchange outlet 112 , a second heat exchange inlet 113 and a second heat exchange outlet 114 .

[0064] According to a specific embodiment of the present invention, Figure 1 As shown, preferably, the second heat exchanger 12 is provided with a third heat exchange inlet 121 , a third heat exchange outlet 122 , a fourth heat exchange inlet 123 and a fourth heat exchange outlet 124 .

[0065] In the present invention, preferably, there are two heat exchange modes, mode 1 is heat exchange between raw ammonia gas and product gas, and mode 2 is heat exchange between a mixed gas containing raw ammonia gas and unreacted ammonia gas adsorbed in a temperature swing adsorption device and product gas. In the present invention, when different heat exchange modes are used, there is no particular limitation on the connection mode of each heat exchanger in the heat exchange unit. When mode 1 heat exchange is required, according to a specific embodiment of the present invention, Figure 1 As shown, preferably, the outlet of the ammonia purifier 2 is communicated with the first heat exchange inlet 111, the first heat exchange outlet 112 is communicated with the third heat exchange inlet 121, the third heat exchange outlet 122 is communicated with the inlet of the ammonia decomposition reactor 3, the outlet of the ammonia decomposition reactor 3 is communicated with the fourth heat exchange inlet 123, and the fourth heat exchange outlet 124 is communicated with the second heat exchange inlet 113. Through the above embodiment, when the product gas at the outlet of the ammonia decomposition reactor 3 passes through the fourth heat exchange inlet 123, it exchanges heat with the raw ammonia gas discharged from the first heat exchange outlet 112, and the product gas of the fourth heat exchange outlet 124 exchanges heat with the raw ammonia gas at the outlet of the ammonia purifier 2, so that the temperature of the raw ammonia gas can reach the decomposition temperature faster to perform the decomposition reaction, while saving energy consumption.

[0066] When the second heat exchange mode is required, according to another specific embodiment of the present invention, Figure 1 As shown, preferably, the second heat exchange outlet 114 is communicated with the inlet of the temperature swing adsorption device 4, and the first heat exchange outlet 112 is communicated with the outlet of the temperature swing adsorption device 4. Through the above embodiment, the unreacted ammonia at the outlet of the temperature swing adsorption device 4 is mixed with the raw ammonia discharged from the first heat exchange outlet 112 to obtain a mixed gas containing raw ammonia and unreacted ammonia, and then heat is exchanged with the product gas, so that the temperature of the mixed gas containing raw ammonia and unreacted ammonia can reach the decomposition temperature faster to perform a decomposition reaction, while saving energy consumption.

[0067] Through the above-mentioned preferred implementation mode, heat exchange between raw ammonia and product gas, as well as heat exchange between the mixed gas of raw ammonia and unreacted ammonia in the temperature swing adsorption device and product gas are realized, so that the raw ammonia can reach the decomposition temperature and decomposition reaction more quickly, while achieving energy-saving effect.

[0068] In the present invention, by back-blowing the temperature swing adsorber with regenerated hydrogen, the unreacted ammonia adsorbed by the temperature swing adsorption device is mixed with the raw material and re-entered into the ammonia decomposition reactor for ammonia decomposition reaction, thereby increasing the hydrogen yield and avoiding the pollution of the environment by ammonia emission. Preferably, the residual ammonia recovery and separation unit also includes an electric heater 5, the inlet of the electric heater 5 is connected to the pressure swing adsorption device 9, and the outlet of the electric heater 5 is connected to the temperature swing adsorption device 4. In the present invention, the electric heater is used to convert at least part of the hydrogen in the product hydrogen into regenerated hydrogen, and the remaining part is used as the final product hydrogen. The regenerated hydrogen is used as a carrier gas to back-blow the unreacted ammonia in the pressure swing adsorption device to the heat exchange unit and mix it with the raw ammonia, and then exchange heat with the product gas, and then return to the ammonia decomposition reactor for ammonia decomposition reaction, thereby improving the decomposition effect of the ammonia decomposition skid-mounted hydrogen production, so that the raw material is more fully converted into hydrogen and nitrogen, while avoiding the emission of ammonia.

[0069] In the present invention, in order to realize the recycling of unreacted ammonia, a temperature swing adsorption device is used to adsorb the unreacted ammonia and temporarily store the unreacted ammonia in the temperature swing adsorption device, and then the regenerated hydrogen is backblown and mixed with the raw ammonia. Preferably, the temperature swing adsorption device 4 is provided with an adsorption bed and a regeneration bed, and the adsorption bed and the regeneration bed are connected in parallel. It should be noted that the adsorption bed and the regeneration bed are used alternately. Parallel connection means that there is no logistics exchange between the adsorption bed and the regeneration bed, but they have the same source of product gas, thereby forming multi-bed parallel processing, further improving the processing capacity of the temperature swing adsorption device. According to a specific embodiment of the present invention, the product gas enters the adsorption bed in the temperature swing adsorption device 5 for adsorption. After the adsorbent in the adsorption bed is saturated with adsorption, it is switched to be used as a regeneration bed, and regeneration is performed by backblowing with regenerated hydrogen. After the regeneration is completed, wait for the adsorption bed to be saturated with adsorption, and the two are switched again, and the cycle repeats.

[0070] In the present invention, a buffer tank is usually provided to achieve buffering and temporary storage of gas in each process. Preferably, the system further includes a first buffer tank 13 , a second buffer tank 14 , a third buffer tank 15 and a fourth buffer tank 16 .

[0071] In the present invention, preferably, the inlet of the first buffer tank 13 is communicated with the outlet of the ammonia decomposition reactor 3 , and the outlet of the first buffer tank 13 is communicated with the inlet of the temperature swing adsorption device 4 .

[0072] In the present invention, preferably, the inlet of the second buffer tank 14 is communicated with the outlet 42 of the temperature swing adsorption device 4 , and the outlet of the second buffer tank 14 is communicated with the inlet of the pressure swing adsorption device 9 .

[0073] In the present invention, preferably, the inlet of the third buffer tank 15 is connected to the outlet of the pressure swing adsorption device 9 .

[0074] In the present invention, preferably, the inlet of the fourth buffer tank 16 is communicated with the outlet of the ammonia washing tank 7 , and the outlet of the fourth buffer tank 16 is communicated with the inlet of the membrane separator 10 .

[0075] In the present invention, in order to realize the recycling of unreacted ammonia, a temperature swing adsorption device is used to adsorb the unreacted ammonia, and then the regenerated hydrogen is back-flushed to mix with the raw ammonia, and the ammonia decomposition reaction is performed again to realize the effective utilization of ammonia. Preferably, the adsorption bed and the regeneration bed are each independently filled with an adsorbent.

[0076] In the present invention, the selection range of the adsorbent type is relatively wide, and all adsorbents conventionally defined in the art are applicable to the present invention. Preferably, the adsorbent is selected from at least one of molecular sieves, activated carbon, silica gel and alumina.

[0077] In the present invention, there is no particular limitation on the type of membrane separator, and any membrane separator conventionally defined in the art is applicable to the present invention.

[0078] In the present invention, the purified hydrogen needs to be purified again to obtain high-purity product hydrogen. Preferably, the outlet of the membrane separator 10 is connected to the pressure swing adsorption device 9, which is used to purify the purified hydrogen to obtain product hydrogen. Through this embodiment, the purified hydrogen obtained after purification by the membrane separator is subjected to pressure swing adsorption again, which further improves the purity of hydrogen while increasing the hydrogen yield.

[0079] In the present invention, there is no particular limitation on the type of membrane used in the membrane separator. Preferably, the membrane used in the membrane separator 10 is an inorganic membrane and / or an organic membrane.

[0080] In the present invention, there is no particular limitation on the type of inorganic membrane. Preferably, the inorganic membrane is selected from at least one of a ceramic membrane, a glass membrane, a metal membrane and a molecular sieve membrane.

[0081] In the present invention, there is no particular limitation on the material of the organic membrane. Preferably, the material of the organic membrane is polysulfone and / or polyimide.

[0082] In the present invention, there is no particular limitation on the property parameters of the membrane, and those skilled in the art may select them according to actual conditions.

[0083] In the present invention, preferably, the system further comprises a first compressor 6 and a second compressor 8. In the present invention, there is no particular limitation on the arrangement of the first compressor and the second compressor, and those skilled in the art can select them according to actual needs.

[0084] In the present invention, preferably, the system also includes an auxiliary unit, the auxiliary system includes a gas collection pipe, an air supply pipeline, a ventilation system, a power distribution system and a PLC control system, and the auxiliary unit is used to control and connect in series the hydrogen preparation unit, the residual ammonia recovery and separation unit, the hydrogen purification unit and the heat exchange unit.

[0085] A second aspect of the present invention provides a process for producing hydrogen by decomposing ammonia, wherein the process is carried out in the system described in the first aspect, wherein the process comprises:

[0086] S1, the raw ammonia gas enters the ammonia decomposition reactor 3 of the hydrogen production unit through the heat exchange unit to undergo ammonia decomposition reaction to obtain product gas;

[0087] S2, the product gas enters the temperature swing adsorption device 4 of the residual ammonia recovery and separation unit to adsorb the unreacted ammonia in the product gas to obtain unreacted ammonia and residual products;

[0088] S3, the remaining product enters the pressure swing adsorption device 9 of the hydrogen purification unit for purification to obtain product hydrogen and analytical gas;

[0089] S4, the analyzed gas enters the ammonia washing tank 7 of the hydrogen purification unit for water washing to obtain a dilute ammonia solution and a hydrogen-nitrogen mixture;

[0090] S5. The hydrogen-nitrogen mixture enters the membrane separator 10 for separation and purification to obtain purified hydrogen and by-product nitrogen.

[0091] The process provided by the present invention is carried out in the aforementioned system, which can improve the purity of hydrogen while improving the hydrogen yield, and can realize the ammonia decomposition hydrogen production reaction within the limited space of the skid-mounted system. The entire process has no residual ammonia emissions, truly achieving zero pollution.

[0092] In the present invention, the conditions for the ammonia decomposition reaction can be selected in a wide range. Preferably, in step S1, the temperature of the ammonia decomposition reaction is 480-600°C.

[0093] In the present invention, other conditions involved in the ammonia decomposition reaction are not particularly limited, and those skilled in the art may select them according to actual needs.

[0094] In the present invention, the type and source of the ammonia decomposition catalyst used in the ammonia decomposition reaction process have been described in the first aspect and will not be repeated here.

[0095] In the present invention, preferably, the method further comprises conveying the ammonia source liquid ammonia to the liquid ammonia electrifier 1 and the ammonia purifier 2 of the hydrogen preparation unit in sequence for gasification and purification to obtain raw ammonia gas.

[0096] In the present invention, preferably, step S3 further comprises electrically heating at least part of the product hydrogen through the electric heater 5 to obtain regenerated hydrogen, and the remaining part of the product hydrogen is used as the final product hydrogen.

[0097] In the present invention, preferably, the regenerated hydrogen is used as a carrier gas to transport the unreacted ammonia adsorbed in the temperature swing adsorption device 4 to the heat exchange unit to mix with the raw ammonia to obtain a mixed gas containing the raw ammonia and the unreacted ammonia.

[0098] In the present invention, preferably, the mixed gas containing raw ammonia and unreacted ammonia is heat exchanged with the product gas of step S1, and then enters the ammonia decomposition reactor 3 for decomposition reaction.

[0099] In the present invention, the range of conditions for pressure swing adsorption is relatively wide, and those skilled in the art can make a selection according to actual conditions. Preferably, the inlet pressure of the pressure swing adsorption device 9 is 1500-2300 KPa.

[0100] In the present invention, the range of conditions for membrane separation is relatively wide, and those skilled in the art can make a selection according to actual conditions. Preferably, the inlet pressure of the membrane separator 10 is 1500-2300 KPa.

[0101] In the present invention, the hydrogen can be further increased under the premise of increasing the hydrogen yield. Preferably, the process further comprises: conveying the purified hydrogen in step S5 to the pressure swing adsorption device 9 in step S3 for purification to obtain product hydrogen. In this way, the purified hydrogen with lower purity can be further purified to obtain high-purity hydrogen.

[0102] According to a specific embodiment of the present invention, the ammonia decomposition hydrogen production process is as follows Figure 1In the system shown, the raw liquid ammonia is vaporized by the liquid ammonia electric vaporizer 1, impurities are removed by the ammonia purifier 2, and enters from the first heat exchange inlet 111 of the first heat exchanger 11. After heat exchange in the first heat exchanger 11, it enters from the third heat exchange inlet 121 of the second heat exchanger 12 for a second heat exchange, and then enters the ammonia decomposition reactor 3 through the third heat exchange outlet 122. The ammonia decomposition reactor 3 is equipped with an ammonia decomposition catalyst. The raw ammonia gas undergoes an ammonia decomposition reaction in the ammonia decomposition reaction device 3. The obtained product gas enters the heat exchange from the third heat exchange inlet 123 of the second heat exchanger 12, flows out from the fourth heat exchange outlet 124 of the second heat exchanger 12, enters the heat exchange from the second heat exchange inlet 113 of the first heat exchanger 11, flows out from the second heat exchange outlet 114 of the first heat exchanger 11, enters the temperature swing adsorption device 4 through the first buffer tank 13 to adsorb unreacted ammonia in the product gas, and then is pressurized by the second buffer tank 14 and the first compressor 6, enters the pressure swing adsorption device 9 for separation, and flows out from the first outlet and the second outlet of the pressure swing adsorption device 9. (not shown in the figure) product hydrogen and analysis gas are obtained respectively, the product hydrogen enters the third buffer tank 15, a part of the product hydrogen is output from the second outlet of the third buffer tank 15 (not shown in the figure) as the final product hydrogen, and the other part is output from the first outlet of the third buffer tank 15 (not shown in the figure) as the regenerated hydrogen, the regenerated hydrogen enters the temperature swing adsorption device 4 through the electric heater 5, the regeneration bed in the temperature swing adsorption device 4 is backblown, the unreacted ammonia desorbed by the temperature swing adsorption device 4 enters the second heat exchanger 12 from the third heat exchange inlet 121 of the second heat exchanger 12 for heat exchange, and then re-enters the ammonia decomposition reactor 3 for ammonia decomposition reaction. The analyzed gas enters the ammonia washing tank 7 for water washing, and the second outlet (not shown in the figure) of the ammonia washing tank 7 discharges dilute ammonia water for plant fertilizer. The gas (hydrogen-nitrogen mixture) output from the first outlet (not shown in the figure) of the ammonia washing tank 7 is pressurized by the second compressor 8 and the fourth buffer tank 16, and enters the membrane separator 10 for separation to obtain purified hydrogen and by-product nitrogen. The purified hydrogen re-enters the second buffer tank 14 through the first outlet (not shown in the figure) of the membrane separator 10 for secondary separation and purification, and the by-product nitrogen gas is directly discharged through the second outlet (not shown in the figure) of the membrane separator 10.

[0103] The present invention will be described in detail below through examples.

[0104] In order to illustrate the system and method provided by the present invention, the following embodiments are schematically illustrated by simulation experiments, and specifically, ASPEN software is used for simulation to illustrate the continuous progress of the ammonia decomposition reaction.

[0105] Example

[0106] According to Figure 1In the system shown, the raw liquid ammonia (mass flow rate: 121.4 kg / h) is vaporized by the liquid ammonia electric vaporizer 1, and then the impurities are removed by the ammonia purifier 2, and then the raw liquid ammonia enters from the first heat exchange inlet 111 of the first heat exchanger 11, and is heat exchanged from 35°C to 48°C by the first heat exchanger 11, and then enters the second heat exchanger 12 through the first heat exchange outlet 112 of the first heat exchanger 11 and the third heat exchange inlet 121 of the second heat exchanger 12 for the second heat exchange to 350°C, and then enters the ammonia decomposition reactor 3 through the third heat exchange outlet 123 of the second heat exchanger 12. An ammonia decomposition reaction is carried out at 550°C, and the obtained product gas (ammonia mass flow rate: 0.4 kg / h, where the ammonia includes the unreacted ammonia in the first ammonia decomposition reaction and the unreacted ammonia desorbed by the temperature swing adsorption device 4 during the continuous reaction; nitrogen mass flow rate: 99.9 kg / h; hydrogen mass flow rate: 23.5 kg / h) enters from the second heat exchange inlet 123 of the second heat exchanger 12 for heat exchange to 300°C, flows out from the fourth heat exchange outlet 124 of the second heat exchanger 12, enters from the second heat exchange inlet 113 of the first heat exchanger 11 for heat exchange to 40°C, then flows out from the second heat exchange outlet 114 of the first heat exchanger 11, enters the adsorption bed of the temperature swing adsorption device 4 through the first buffer tank 13 to adsorb the unreacted ammonia in the product gas, and then is pressurized to 1500 KPa by the second buffer tank 14 and the first compressor 6, enters the pressure swing adsorption device 9 for separation, and flows out from the first outlet and the second outlet of the pressure swing adsorption device 9. (not shown in the figure) to obtain product hydrogen (mass flow rate: 22.9 kg / h) and analytical gas (nitrogen mass flow rate: 99.9 kg / h; hydrogen mass flow rate: 4.5 kg / h), respectively. The product hydrogen enters the third buffer tank 15, and a part of the product hydrogen is output as the final product hydrogen (mass flow rate: 20.9 kg / h) from the second outlet (not shown in the figure) of the third buffer tank 15, and the other part is output as regenerated hydrogen (mass flow rate: 2 kg / h) from the first outlet (not shown in the figure) of the third buffer tank 15. The regenerated hydrogen is heated to 250° C. by the electric heater 5 and enters the temperature swing adsorption device 4 to backflush the regeneration bed in the temperature swing adsorption device 4. The unreacted ammonia (ammonia mass flow rate: 0.4 kg / h) desorbed by the temperature swing adsorption device 4 enters the second heat exchanger 12 from the third heat exchange inlet 121 of the second heat exchanger 12 for heat exchange, and then re-enters the ammonia decomposition reactor 3 for ammonia decomposition reaction.The analyzed gas enters the ammonia washing tank 7 for water washing, and the second outlet (not shown in the figure) of the ammonia washing tank 7 discharges dilute ammonia water for plant fertilizer. The hydrogen-nitrogen mixture (mass flow rate of hydrogen-nitrogen mixture: 104.4 kg / h) output from the first outlet (not shown in the figure) of the ammonia washing tank 7 is pressurized to 1700 KPa by the second compressor 8 and the fourth buffer tank 16, and enters the membrane separator 10 for separation to obtain purified hydrogen and by-product nitrogen (mass flow rate: 100.6 kg / h). The purified hydrogen (mass flow rate: 3.8 kg / h) re-enters the second buffer tank 14 through the first outlet (not shown in the figure) of the membrane separator 10 for secondary separation and purification, and the by-product nitrogen is directly discharged through the second outlet (not shown in the figure) of the membrane separator 10. The purity of the final product hydrogen is 99.999%, and the final product hydrogen recovery rate is 97.6% (the final product hydrogen recovery rate is calculated based on the ratio of the mass of the final product hydrogen to the mass of hydrogen atoms in the raw liquid ammonia).

[0107] It can be seen from the above embodiments that the ammonia decomposition skid-mounted hydrogen production system provided by the present invention uses ammonia as a hydrogen production raw material, which is easy to decompose and has a high decomposition rate, low cost, easy to store, not prone to safety accidents such as explosion, and the product after the reaction is clean and environmentally friendly, and will not cause air pollution; and the heat obtained from the ammonia decomposition reaction is recycled and utilized, thereby reducing the energy loss of the system; in addition, the ammonia decomposition skid-mounted hydrogen production system uses a pressure swing adsorption device coupled with a membrane separator to purify hydrogen, thereby improving the hydrogen yield under skid-mounted conditions with limited space, and at the same time controlling the by-product to be nitrogen, which can be directly discharged without pollution; at the same time, the ammonia decomposition skid-mounted hydrogen production system uses a method of back-blowing the regenerated hydrogen obtained by the hydrogen purification system through a temperature swing adsorption device, mixing the unreacted ammonia with the raw material, re-entering the ammonia decomposition reactor for reaction, thereby improving the hydrogen yield and avoiding the pollution of ammonia emissions to the environment; finally, the ammonia decomposition skid-mounted hydrogen production system uses an ammonia washing tank to wash ammonia for the analysis gas of the pressure swing adsorption device, thereby avoiding the pollution of ammonia emissions to the environment, and the by-product dilute ammonia water obtained can be used as a plant fertilizer.

[0108] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An ammonia decomposition skid-mounted hydrogen production system, characterized in that: The system comprises a hydrogen preparation unit, a residual ammonia recovery and separation unit and a hydrogen purification unit, wherein the hydrogen preparation unit, the residual ammonia recovery and separation unit and the hydrogen purification unit are interconnected through pipelines; The hydrogen preparation unit comprises an ammonia decomposition reactor (3), and the ammonia decomposition reactor (3) is used to carry out an ammonia decomposition reaction on the raw ammonia to obtain a product gas; The residual ammonia recovery and separation unit comprises a temperature swing adsorption device (4), and the temperature swing adsorption device (4) is used to adsorb unreacted ammonia in the product gas to obtain unreacted ammonia and residual products; The system further comprises a heat exchange unit, which is used to exchange heat between the product gas and the raw ammonia gas, and / or, the heat exchange unit is used to exchange heat between the product gas and a mixed gas containing the raw ammonia gas and unreacted ammonia gas; The hydrogen purification unit comprises a pressure swing adsorption device (9), an ammonia washing tank (7) and a membrane separator (10), wherein the pressure swing adsorption device (9) is used to purify the remaining product to obtain product hydrogen and analytical gas; The ammonia washing tank (7) is used to wash the analyzed gas with water to obtain a dilute ammonia solution and a hydrogen-nitrogen mixture; The membrane separator (10) is used to separate and purify the hydrogen-nitrogen mixture to obtain purified hydrogen and by-product nitrogen.

2. The system according to claim 1, wherein: The hydrogen production unit further comprises a liquid ammonia electrifier (1), wherein the liquid ammonia electrifier (1) is used to gasify the ammonia source liquid ammonia into ammonia gas; Preferably, the hydrogen preparation unit further comprises an ammonia purifier (2), and the ammonia purifier (2) is used to purify ammonia to obtain raw ammonia.

3. The system according to claim 1 or 2, wherein: The residual ammonia recovery and separation unit further comprises an electric heater (5), the inlet of the electric heater (5) is connected to the pressure swing adsorption device (9), and the outlet of the electric heater (5) is connected to the temperature swing adsorption device (4).

4. The system according to any one of claims 1 to 3, wherein: The temperature-swing adsorption device (4) is provided with an adsorption bed and a regeneration bed, and the adsorption bed and the regeneration bed are connected in parallel; Preferably, the adsorption bed and the regeneration bed are each independently filled with an adsorbent; Preferably, the adsorbent is selected from at least one of molecular sieves, activated carbon, silica gel and alumina.

5. The system according to any one of claims 1 to 4, wherein: The outlet of the membrane separator (10) is connected to the pressure swing adsorption device (9) for purifying the purified hydrogen to obtain product hydrogen; Preferably, the membrane used in the membrane separator (10) is an inorganic membrane and / or an organic membrane; Preferably, the inorganic membrane is selected from at least one of a ceramic membrane, a glass membrane, a metal membrane and a molecular sieve membrane; Preferably, the material of the organic film is polysulfone and / or polyimide.

6. A process for producing hydrogen by decomposing ammonia, wherein: The process is carried out in a system as claimed in any one of claims 1 to 5, wherein the process comprises: S1, the raw ammonia gas enters the ammonia decomposition reactor (3) of the hydrogen production unit through the heat exchange unit to undergo an ammonia decomposition reaction to obtain a product gas; S2, the product gas enters the temperature swing adsorption device (4) of the residual ammonia recovery and separation unit to adsorb unreacted ammonia in the product gas to obtain unreacted ammonia and residual products; S3, the remaining product enters the pressure swing adsorption device (9) of the hydrogen purification unit for purification to obtain product hydrogen and analytical gas; S4, the analyzed gas enters the ammonia washing tank (7) of the hydrogen purification unit for water washing to obtain a dilute ammonia water and a hydrogen-nitrogen mixture; S5. The hydrogen-nitrogen mixture enters a membrane separator (10) for separation and purification to obtain purified hydrogen and by-product nitrogen.

7. The process according to claim 6, wherein: In step S1, the temperature of the ammonia decomposition reaction is 480-600°C.

8. The process according to claim 6 or 7, wherein: The method further comprises transporting the ammonia source liquid ammonia to the liquid ammonia electrifier (1) and the ammonia purifier (2) of the hydrogen preparation unit in sequence for gasification and purification to obtain raw ammonia gas.

9. The process according to any one of claims 6 to 8, wherein: Step S3 also includes electrically heating at least part of the product hydrogen through an electric heater (5) to obtain regenerated hydrogen, and the remaining part of the product hydrogen is used as the final product hydrogen; Preferably, the regenerated hydrogen is used as a carrier gas to transport the unreacted ammonia adsorbed in the temperature swing adsorption device (4) to the heat exchange unit to be mixed with the raw ammonia to obtain a mixed gas containing the raw ammonia and the unreacted ammonia; Preferably, the mixed gas containing raw ammonia and unreacted ammonia is heat exchanged with the product gas of step S1, and then enters the ammonia decomposition reactor (3) for decomposition reaction.

10. The process according to any one of claims 6 to 9, wherein: The inlet pressure of the pressure swing adsorption device (9) is 1500-2300 KPa; Preferably, the inlet pressure of the membrane separator (10) is 1500-2300 KPa; Preferably, the process further comprises: conveying the purified hydrogen in step S5 to the pressure swing adsorption device (9) in step S3 for purification to obtain product hydrogen.

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