Ammonia decomposition hydrogen production system and method based on refinery plant

Abstract

The invention relates to the field of hydrogen production through ammonia decomposition, and discloses an ammonia decomposition hydrogen production system and method based on a refinery plant. The system comprises a raw material unit, a hydrogen preparation unit, a residual ammonia recovery and separation unit and a hydrogen purification unit which are mutually connected through pipelines, the hydrogen preparation unit comprises an ammonia decomposition reactor and is used for carrying out ammonia decomposition reaction on raw material ammonia gas; the residual ammonia recovery and separation unit comprises a temperature swing adsorption device which is used 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 the heat exchange unit is used for 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 and is used for purifying residual products; the raw material unit comprises a refinery hydrofining device and is used for providing ammonia source liquid ammonia and / or recovering desorption gas. The system can provide sufficient hydrogen sources for the existing refinery plants, reduce the reaction energy consumption and improve the hydrogen yield.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production by decomposing ammonia, and in particular to a refinery-based hydrogen production system and method by decomposing ammonia. Background Art

[0002] Currently, hydrogen almost all comes from catalytic steam reforming of fossil fuels, which is also the most mature commercial hydrogen production technology. However, due to the low-load operation of the atmospheric and vacuum units in refineries, the straight-run gasoline output is often difficult to meet the needs of the catalytic reforming unit, resulting in insufficient hydrogen sources for the refinery as a whole.

[0003] Liquid ammonia is one of the by-products in the refinery. Using ammonia as a liquid hydrogen storage medium, the advantage of developing ammonia decomposition hydrogen production technology based on the existing equipment of the refinery is that the hydrogen storage density is high and the decomposition product has no carbon emissions. Ammonia decomposition hydrogen production 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. There are problems such as high energy consumption, low production efficiency, and many ancillary projects. Therefore, it is urgent to develop an efficient, environmentally friendly, and highly compatible ammonia decomposition hydrogen production method with existing refineries to solve the problem of insufficient hydrogen source in the refinery. At the same time, ammonia as a raw material also has toxicity problems. If ammonia is not completely decomposed, the direct removal of ammonia in the tail gas will cause certain safety hazards. Therefore, the present invention aims to solve the problem of reducing energy consumption based on the existing equipment of the refinery, realizing ammonia decomposition hydrogen production as insufficient hydrogen source for the refinery, while reducing safety hazards and improving the yield and purity of hydrogen. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems of insufficient hydrogen source in refineries, low spatial effective hydrogen production efficiency of ammonia decomposition hydrogen production systems, tail gas safety hazards and high energy consumption in the prior art, and to provide a refinery-based ammonia decomposition hydrogen production system and method, which can provide sufficient hydrogen source for existing refineries, reduce reaction energy consumption and increase hydrogen yield.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides an ammonia decomposition hydrogen production system based on a refinery, wherein the system comprises a raw material unit, a hydrogen production unit, a residual ammonia recovery and separation unit and a hydrogen purification unit, wherein the hydrogen production unit, the residual ammonia recovery and separation unit and the hydrogen purification unit are interconnected by pipelines;

[0006] 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 gas;

[0007] The residual ammonia recovery and separation unit comprises a temperature swing adsorption device, which is used to adsorb unreacted ammonia in the product gas to obtain unreacted ammonia and residual products;

[0008] 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;

[0009] The hydrogen purification unit comprises a pressure swing adsorption device, which is used to purify the remaining product to obtain hydrogen and analytical gas;

[0010] The raw material unit comprises a refinery hydrotreating device, and the refinery hydrotreating device is used to provide ammonia source liquid ammonia and / or recover analytical gas.

[0011] A second aspect of the present invention provides a method for producing hydrogen by decomposing ammonia, wherein the method is performed in the system described in the first aspect, wherein the method comprises:

[0012] 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;

[0013] 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;

[0014] S3, the remaining product enters the pressure swing adsorption device of the hydrogen purification unit for purification to obtain hydrogen and analytical gas;

[0015] S4. The analyzed gas is returned to the refinery hydrotreating device of the raw material unit for recycling.

[0016] The refinery-based ammonia decomposition hydrogen production system of the present invention utilizes the product gas of ammonia decomposition to perform heat exchange with the raw ammonia gas and the mixed gas of the raw ammonia gas and the 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.

[0017] The refinery-based ammonia decomposition hydrogen production system of the present invention preferably uses the refinery's original pressure swing adsorption device to purify hydrogen, thereby improving the hydrogen yield while saving costs.

[0018] The refinery-based ammonia decomposition hydrogen production system of the present invention adopts the analysis gas circulation of the pressure swing adsorption device to transfer the refinery hydrogenation refining device in the raw material unit to avoid the pollution of ammonia emission to the environment.

[0019] The refinery-based ammonia decomposition hydrogen production system of the present invention preferably uses a method of back-blowing the regenerated hydrogen obtained from the hydrogen purification unit through a temperature swing adsorption device, mixing the unreacted ammonia (unreacted ammonia adsorbed by the temperature swing adsorption device) with the raw ammonia, and re-entering the ammonia decomposition reactor for continuous reaction, thereby increasing the hydrogen yield and avoiding environmental pollution caused by ammonia emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the system of the present invention.

[0021] Description of Reference Numerals

[0022] 1-Refinery Hydrogenation Refining Unit 2-Liquid Ammonia Electrifier

[0023] 3- Ammonia Purifier 4- Ammonia Decomposition Reactor

[0024] 5- Temperature variable adsorption device 6- Electric heater

[0025] 7-First buffer tank 8-Compressor

[0026] 9- Pressure swing adsorption device 10- First heat exchanger

[0027] 101-first heat exchange inlet 102-first heat exchange outlet

[0028] 103- Second heat exchange inlet 104- Second heat exchange outlet

[0029] 11- Second heat exchanger 111- Third heat exchange inlet

[0030] 112- third heat exchange outlet 113- fourth heat exchange inlet

[0031] 114- fourth heat exchange outlet 12- second buffer tank

[0032] 13-Third buffer tank DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] 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".

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] The first aspect of the present invention provides a refinery-based ammonia decomposition hydrogen production system, such as Figure 1 As shown, the system includes a raw material unit, a hydrogen production unit, a residual ammonia recovery and separation unit and a hydrogen purification unit, and the hydrogen production unit, the residual ammonia recovery and separation unit and the hydrogen purification unit are interconnected by pipelines;

[0042] The hydrogen preparation unit comprises an ammonia decomposition reactor 4, and the ammonia decomposition reactor 4 is used to perform an ammonia decomposition reaction on the raw ammonia to obtain a product gas;

[0043] The residual ammonia recovery and separation unit comprises a temperature swing adsorption device 5, and the temperature swing adsorption device 5 is used to adsorb unreacted ammonia in the product gas to obtain unreacted ammonia and residual products;

[0044] 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;

[0045] The hydrogen purification unit comprises a pressure swing adsorption device 9, and the pressure swing adsorption device 9 is used to purify the remaining product to obtain hydrogen and analytical gas;

[0046] The raw material unit comprises a refinery hydrotreating device 1, and the refinery hydrotreating device 1 is used to provide ammonia source liquid ammonia and / or recover analytical gas.

[0047] The refinery-based ammonia decomposition hydrogen production system of the present invention utilizes the product gas of ammonia decomposition to perform heat exchange with the raw ammonia gas and the mixed gas of the raw ammonia gas and the backwash ammonia gas, thereby reducing heat loss and achieving energy-saving effect through internal circulation heat exchange.

[0048] In the present invention, the raw material unit is provided by the refinery. Preferably, the raw material unit can provide ammonia source liquid ammonia and recover the desorption gas. Through the above preferred implementation, the refinery-based ammonia decomposition hydrogen production system of the present invention circulates the desorption gas provided by the pressure swing adsorption device in the hydrogen purification unit to the raw material unit, that is, the ammonia is returned to the refinery hydrotreating device in the raw material unit, avoiding the pollution of the environment by ammonia emissions, realizing the recycling of unreacted ammonia, and avoiding the emission of residual ammonia.

[0049] In the present invention, there is no particular limitation on the source of the pressure swing adsorption device, for example, the original pressure swing adsorption device of the refinery can be used, or the pressure swing adsorption device can be introduced from the outside. Preferably, the pressure swing adsorption device comes from the original pressure swing adsorption device of the refinery. By adopting this preferred embodiment, the original pressure swing adsorption device of the refinery is used to purify hydrogen, thereby improving the hydrogen yield while saving costs.

[0050] In the present invention, there is no particular limitation on the form of the raw material ammonia for the ammonia decomposition reaction. Preferably, ammonia gas is selected to achieve gasification of ammonia source liquid ammonia to obtain raw materials and better improve the efficiency of hydrogen production by ammonia decomposition. Preferably, the hydrogen preparation unit also includes a liquid ammonia electrifier 2, which is used to gasify the ammonia source liquid ammonia provided by the refinery hydrotreating device 1 into ammonia gas.

[0051] 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 3, which is used to purify ammonia to obtain raw ammonia.

[0052] 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.

[0053] 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 2 and the ammonia purifier 3 are connected in series through a pipeline. According to a specific embodiment of the present invention, the inlet of the liquid ammonia electrifier 3 is connected to the refinery hydrotreating device 1 of the raw material unit, the outlet of the liquid ammonia electrifier 2 is connected to the inlet of the ammonia purifier 3, and the outlet of the ammonia purifier 3 is connected to the inlet of the ammonia decomposition reactor 4. In the above manner, the ammonia source liquid ammonia provided by the refinery hydrotreating device 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.

[0054] In the present invention, in order to improve the efficiency of the ammonia decomposition reaction, preferably, the ammonia decomposition reactor 4 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 includes 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 includes 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.

[0055] 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.

[0056] In the present invention, in order to improve the energy utilization rate in the refinery-based ammonia decomposition hydrogen production system and reduce the energy consumption of the refinery-based ammonia decomposition hydrogen production system to achieve the purpose of energy saving, a heat exchange unit is used in the present invention to perform heat exchange inside the system. 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 10 and a second heat exchanger 11. In the present invention, there is no special limitation on the arrangement of the first heat exchanger 10 and the second heat exchanger 11. Preferably, the first heat exchanger 10 and the second heat exchanger 11 are arranged between the ammonia purifier 3 and the ammonia decomposition reactor 4, and the first heat exchanger 10 and the second heat exchanger 11 are arranged in series.

[0057] According to a specific embodiment of the present invention, Figure 1 As shown, preferably, the first heat exchanger 10 is provided with a first heat exchange inlet 101 , a first heat exchange outlet 102 , a second heat exchange inlet 103 and a second heat exchange outlet 104 .

[0058] According to a specific embodiment of the present invention, Figure 1 As shown, preferably, the second heat exchanger 11 is provided with a third heat exchange inlet 111 , a third heat exchange outlet 112 , a fourth heat exchange inlet 113 and a fourth heat exchange outlet 114 .

[0059] 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 by 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 1As shown, preferably, the outlet of the ammonia purifier 3 is communicated with the first heat exchange inlet 101, the first heat exchange outlet 102 is communicated with the third heat exchange inlet 111, the third heat exchange outlet 112 is communicated with the inlet of the ammonia decomposition reactor 4, the outlet of the ammonia decomposition reactor 4 is communicated with the fourth heat exchange inlet 113, and the fourth heat exchange outlet 114 is communicated with the second heat exchange inlet 103. Through the above embodiment, when the product gas at the outlet of the ammonia decomposition reactor 4 passes through the fourth heat exchange inlet 113, it exchanges heat with the raw ammonia gas discharged from the first heat exchange outlet 102, and the product gas of the fourth heat exchange outlet 114 exchanges heat with the raw ammonia gas at the outlet of the ammonia purifier 3, so that the temperature of the raw ammonia gas can reach the decomposition temperature faster to perform the decomposition reaction, while saving energy consumption.

[0060] 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 104 is communicated with the inlet of the temperature swing adsorption device 5, and the first heat exchange outlet 102 is communicated with the outlet of the temperature swing adsorption device 5. Through the above embodiment, the adsorbed unreacted ammonia at the outlet of the temperature swing adsorption device 5 is mixed with the raw ammonia discharged from the first heat exchange outlet 102 to obtain a mixed gas containing the raw ammonia and the unreacted ammonia adsorbed by the temperature swing adsorber, and then heat-exchanges with the product gas, so that the temperature of the mixed gas containing the raw ammonia and the unreacted ammonia adsorbed by the temperature swing adsorber can reach the decomposition temperature more quickly for decomposition reaction, while saving energy consumption.

[0061] 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 adsorbed by the temperature swing adsorber and product gas are realized, so that the raw ammonia can reach the decomposition temperature and decomposition reaction faster, while achieving energy-saving effect.

[0062] In the present invention, by back-blowing the temperature swing adsorption device with regenerated hydrogen, the unreacted ammonia is mixed with the raw material and re-entered into the ammonia decomposition reactor for ammonia decomposition reaction, thereby improving the hydrogen yield and avoiding the pollution of the environment by ammonia emissions. Preferably, the residual ammonia recovery and separation unit also includes an electric heater 6, the inlet of the electric heater 6 is connected to the pressure swing adsorption device 9, and the outlet of the electric heater 6 is connected to the temperature swing adsorption device 5. In the present invention, the electric heater is used to convert at least part of the hydrogen in the hydrogen into regenerated hydrogen, and the regenerated hydrogen is used as a carrier gas to back-blow the unreacted ammonia adsorbed in the pressure swing adsorption device to the heat exchange unit to mix 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 ammonia decomposition to produce hydrogen, so that the raw material is more fully converted into hydrogen and nitrogen, while avoiding the emission of ammonia.

[0063] In the present invention, in order to realize the recycling of unreacted ammonia, the unreacted ammonia adsorbed by the temperature swing adsorption device is used and the unreacted ammonia is temporarily stored 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 5 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.

[0064] In the present invention, in order to achieve buffering and temporary storage of gas in each process, a buffer tank is usually provided. Preferably, the system further includes a first buffer tank 7 , a second buffer tank 12 and a third buffer tank 13 .

[0065] In the present invention, preferably, the inlet of the first buffer tank 7 is communicated with the outlet of the ammonia decomposition reactor 4 , and the outlet of the first buffer tank 7 is communicated with the inlet of the temperature swing adsorption device 5 .

[0066] In the present invention, preferably, the inlet of the second buffer tank 12 is connected to the outlet of the temperature swing adsorption device 5, and the outlet of the second buffer tank 12 is connected to the inlet of the pressure swing adsorption device 9. Through this embodiment, the hydrogen purification system and the residual ammonia recovery and separation system are connected to achieve hydrogen purification and residual ammonia recovery.

[0067] In the present invention, preferably, the inlet of the third buffer tank 13 is connected to the outlet of the pressure swing adsorption device 9 .

[0068] 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 unreacted ammonia adsorbed by the temperature swing adsorption device is back-flushed with the help of regenerated hydrogen 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.

[0069] 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.

[0070] In the present invention, preferably, the system further comprises a compressor 8 disposed between the second buffer tank 13 and the pressure swing adsorption device 9. The arrangement of the compressor of the present invention is a conventionally defined method in the art, and the present invention does not specifically limit this.

[0071] In the present invention, preferably, the system also includes an auxiliary unit, which 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.

[0072] A second aspect of the present invention provides a method for producing hydrogen by decomposing ammonia, wherein the method is performed in the system described in the first aspect, wherein the method comprises:

[0073] S1, the raw ammonia gas enters the ammonia decomposition reactor 4 of the hydrogen production unit through the heat exchange unit to undergo ammonia decomposition reaction to obtain product gas;

[0074] S2, the product gas enters the temperature swing adsorption device 5 of the residual ammonia recovery and separation unit to adsorb the unreacted ammonia in the product gas to obtain unreacted ammonia and residual products;

[0075] S3, the remaining product enters the pressure swing adsorption device 9 of the hydrogen purification unit for purification to obtain hydrogen and analytical gas;

[0076] S4. The analyzed gas is returned to the refinery hydrotreating device 1 of the raw material unit for recycling.

[0077] The method provided by the present invention is carried out in the aforementioned system, with the refinery as the raw material source. On the one hand, it can realize the effective utilization of ammonia, and on the other hand, its raw material ammonia is converted into hydrogen to provide a hydrogen source for the refinery, thereby making up for the shortage of hydrogen source; further, the method provided by the present invention can improve the purity of hydrogen while improving the hydrogen yield, and the ammonia obtained by re-inputting the analyzed gas into the hydrorefining unit and the unreacted ammonia discharged from the regeneration bed of the temperature swing adsorption device are re-decomposed in the ammonia decomposition reactor again, and the whole method has no residual ammonia emission, truly achieving zero pollution.

[0078] The method provided by the present invention uses liquid ammonia obtained from a refinery hydrotreating unit as raw material, couples the original hydrogen purification unit of the refinery through a hydrogen preparation system and a residual ammonia recovery system, and realizes an ammonia decomposition hydrogen production process based on liquid ammonia, a by-product of the refinery.

[0079] 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.

[0080] 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.

[0081] In the present invention, the ammonia decomposition catalyst used in the ammonia decomposition hydrogen production reaction has been described in the first aspect and will not be described in detail here. Those skilled in the art can select it according to actual needs.

[0082] In the present invention, preferably, the method further comprises transporting the ammonia source liquid ammonia provided by the refinery hydrotreating device to the liquid ammonia electrifier 2 and the ammonia purifier 3 of the hydrogen preparation unit in sequence for gasification and purification to obtain raw ammonia.

[0083] In the present invention, preferably, step S3 further comprises electrically heating at least part of the hydrogen through an electric heater 6 to obtain regenerated hydrogen, and the remaining part of the hydrogen is used as product hydrogen.

[0084] 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 5 to the heat exchange unit to mix with the raw ammonia to obtain a mixed gas containing the raw ammonia and the unreacted ammonia. The advantage of adopting this preferred embodiment is that the undecomposed ammonia is subjected to a secondary reaction to improve the hydrogen recovery rate, while avoiding the emission of residual ammonia, which is beneficial to environmental protection.

[0085] 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 4 for decomposition reaction. The advantage of adopting this preferred embodiment is that the heat of the product gas is used to heat the unreacted ammonia, thereby reducing heat loss.

[0086] In the present invention, the range of conditions for temperature 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.

[0087] According to a specific embodiment of the present invention, Figure 1As shown, the ammonia source liquid ammonia provided by the refinery hydrotreating device 1 enters the liquid ammonia electrifier 2 for gasification to obtain ammonia gas, and the ammonia gas enters the ammonia purifier 3 for purification to obtain raw ammonia gas, which enters from the first heat exchange inlet 101 of the first heat exchanger 10, and after heat exchange through the first heat exchanger 10, enters the second heat exchanger 11 through the first heat exchange outlet 102 and the third heat exchange inlet 111 of the second heat exchanger 11 for a second heat exchange, and then enters the ammonia decomposition reactor 4 for ammonia decomposition reaction, and the obtained product gas enters from the fourth heat exchange inlet 113 of the second heat exchanger 11 and flows out from the fourth heat exchange outlet 114 of the second heat exchanger 11 after heat exchange, and returns to the first heat exchanger 10 from the second heat exchange inlet 103 of the first heat exchanger 10 and flows out from the second heat exchange outlet 104 of the first heat exchanger 10. The unreacted ammonia in the product gas is adsorbed by the temperature swing adsorption device 5 through the first buffer tank 7, and the remaining product is pressurized by the second buffer tank 12 and the compressor 8 and then enters the pressure swing adsorption device 9 for separation. Hydrogen and analytical gas are obtained from the first outlet (not shown in the figure) and the second outlet (not shown in the figure) of the pressure swing adsorption device 9, respectively. The hydrogen enters the third buffer tank 13, and a part of the hydrogen is output from the second outlet of the third buffer tank 13 as product hydrogen, and the other part is output from the first outlet of the third buffer tank 13 as regenerated hydrogen, and enters the temperature swing adsorption device 5 through the electric heater 6 to back-blow the regeneration bed, and the unreacted ammonia desorbed in the regeneration bed enters from the first heat exchange inlet 101 of the second heat exchanger 11 for heat exchange, and then re-enters the ammonia decomposition reactor 4 for continuous reaction. The analytical gas enters the refinery hydrotreating device 1 for re-separation to obtain ammonia source liquid ammonia.

[0088] The refinery-based ammonia decomposition hydrogen production system of the present invention adopts the analysis gas circulation of the pressure swing adsorption device to return the ammonia to the raw material unit, thereby avoiding the pollution of the environment by the ammonia emission.

[0089] The refinery-based ammonia decomposition hydrogen production system of the present invention adopts ammonia as the 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 involved in the ammonia decomposition reaction is recycled and utilized, thereby reducing the energy loss of the system; in addition, the refinery-based ammonia decomposition hydrogen production process adopts the refinery's original pressure swing adsorption device to purify hydrogen, thereby improving the hydrogen yield while reducing the cost of device construction; at the same time, the refinery-based ammonia decomposition hydrogen production process adopts the method of back-blowing the regenerated hydrogen obtained from the hydrogen purification system through the temperature swing adsorption device, mixing the unreacted ammonia with the raw material, and 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 refinery-based ammonia decomposition hydrogen production process adopts the analytical gas circulation process of the pressure swing adsorption device to avoid the pollution of ammonia emissions to the environment.

[0090] 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. A refinery-based ammonia decomposition hydrogen production system, characterized in that: The system comprises a raw material unit, 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 (4), and the ammonia decomposition reactor (4) 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 (5), and the temperature swing adsorption device (5) 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), and the pressure swing adsorption device (9) is used to purify the remaining product to obtain hydrogen and analytical gas; The raw material unit comprises a refinery hydrotreating device (1), and the refinery hydrotreating device (1) is used to provide ammonia source liquid ammonia and / or recover analytical gas.

2. The system according to claim 1, wherein: The hydrogen production unit further comprises a liquid ammonia electrifier (2), wherein the liquid ammonia electrifier (2) is used to gasify the ammonia source liquid ammonia provided by the refinery hydrotreating device (1) into ammonia gas; Preferably, the hydrogen preparation unit further comprises an ammonia purifier (3), and the ammonia purifier (3) 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 (6), the inlet of the electric heater (6) is connected to the pressure swing adsorption device (9), and the outlet of the electric heater (6) is connected to the temperature swing adsorption device (5).

4. The system according to any one of claims 1 to 3, wherein: The temperature swing adsorption device (5) 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. A refinery-based method for producing hydrogen by decomposing ammonia, wherein: The method is performed in a system according to any one of claims 1 to 4, wherein the method comprises: S1, the raw ammonia gas enters the ammonia decomposition reactor (4) 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 (5) 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 hydrogen and analytical gas; S4. The analyzed gas is returned to the refinery hydrotreating device (1) of the raw material unit for recycling.

6. The method according to claim 5, wherein: In step S1, the temperature of the ammonia decomposition reaction is 480-600°C.

7. The method according to claim 5 or 6, wherein: The method further comprises transporting the ammonia source liquid ammonia provided by the refinery hydrotreating device (1) to the liquid ammonia electrifier (2) and the ammonia purifier (3) of the hydrogen preparation unit in sequence for gasification and purification to obtain raw ammonia.

8. The method according to any one of claims 5 to 7, wherein: Step S3 also includes electrically heating at least part of the hydrogen through an electric heater (6) to obtain regenerated hydrogen, and the remaining part of the hydrogen is used as product hydrogen.

9. The method according to claim 8, wherein: The regenerated hydrogen is used as a carrier gas to transport the unreacted ammonia adsorbed in the temperature swing adsorption device (5) 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 (4) for decomposition reaction.

10. The method according to any one of claims 5 to 9, wherein: The inlet pressure of the pressure swing adsorption device (9) is 1500-2300 KPa.

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