System and method for waste gasification coupled with ammonia production

Abstract

This invention relates to the field of waste gasification technology, and in particular to a system and method for coupled waste gasification with ammonia production. The system includes a waste gasification device. The mixed gas outlet of the waste gasification device is connected to an autothermal catalytic reforming system via a pipeline. The mixed gas outlet of the autothermal catalytic reforming system is connected to the inlet of a gas purification system via a pipeline. The hydrogen outlet of the gas purification system is connected to the hydrogen inlet of a synthetic ammonia system via a pipeline. The nitrogen inlet of the synthetic ammonia system is connected to the nitrogen outlet of an air separator via a pipeline. The oxygen outlet of the air separator is connected to the oxygen inlet of the waste gasification device via a pipeline. This system uses the oxygen produced by the air separator for waste gasification, and combines the hydrogen produced by waste gasification with the nitrogen produced by the air separator to synthesize ammonia. This improves resource utilization, achieves harmless resource utilization of waste, and reduces the cost of waste gasification and ammonia synthesis.

Description

Technical Field

[0001] This invention relates to the field of waste gasification treatment technology, and in particular to a system and method for coupled ammonia production from waste gasification. Background Technology

[0002] The main methods of municipal solid waste disposal are landfill and waste-to-energy incineration, both of which have an impact on the ecological environment. Compared with these two traditional waste disposal methods, gasification requires less land, does not produce or emit harmful substances such as dioxins, and the ash and gas produced can be utilized as resources, meeting the basic requirements of harmless, reduced, and resource-based on-site treatment of waste.

[0003] Currently, there are many waste gasification technologies available, among which the pure oxygen high-temperature pyrolysis process is mature and has many advantages: no pretreatment is required for waste, and the process is simple; almost all organic matter is decomposed, with a decomposition temperature reaching 1650℃; waste volume is significantly reduced, approximately 95%-98%; and due to the use of pure oxygen, the amount of nitrogen oxides (NOx) produced is extremely low. However, because pure oxygen is required during production, installing a separate air separation unit would be costly.

[0004] In the ammonia synthesis process, an air separation device is required to provide nitrogen. While the air separation device separates nitrogen, it also produces oxygen as a byproduct. Meanwhile, hydrogen, the main component of waste gasification, is one of the raw materials for ammonia synthesis. In order to achieve the harmless resource utilization of waste and improve the resource utilization rate, a system and method for coupled ammonia production from waste gasification is proposed. Summary of the Invention

[0005] The first objective of this invention is to provide a system for co-producing ammonia from waste gasification. This system can fully utilize the hydrogen generated during waste gasification to produce ammonia, while simultaneously using oxygen, a byproduct of the ammonia synthesis process, for waste pyrolysis and gasification, thereby achieving harmless resource utilization of waste, reducing the cost of waste gasification and ammonia production, and improving resource utilization efficiency. The second objective of this invention is to provide a method for co-producing ammonia from waste gasification using this system.

[0006] This invention provides a system for coupled ammonia production via waste gasification, comprising a waste gasification device. The mixed gas outlet of the waste gasification device is connected to an autothermal catalytic reforming system via a pipeline. The mixed gas outlet of the autothermal catalytic reforming system is connected to the inlet of a gas purification system via a pipeline. The hydrogen outlet of the gas purification system is connected to the hydrogen inlet of an ammonia synthesis system via a pipeline. The nitrogen inlet of the ammonia synthesis system is connected to the nitrogen outlet of an air separation device via a pipeline. The oxygen outlet of the air separation device is connected to the oxygen inlet of the waste gasification device via a pipeline.

[0007] Preferably, a first heat exchange device is provided between the waste gasification device and the self-heating catalytic reforming system, a second heat exchange device is provided between the self-heating catalytic reforming system and the gas purification system, and a third heat exchange device is provided in the ammonia synthesis system.

[0008] Preferably, it also includes an oxygen transport pipeline, which is connected in sequence to the air separation device, the third heat exchange device, the second heat exchange device, the first heat exchange device, and the waste gasification device.

[0009] Preferably, the oxygen transport pipeline between the second heat exchanger and the first heat exchanger is connected to the oxygen inlet of the self-heating catalytic reforming system via a pipeline.

[0010] Preferably, the ammonia synthesis system employs the Haber process for ammonia synthesis.

[0011] Preferably, the gas purification system includes desulfurization, denitrification and carbon capture processes.

[0012] The present invention also provides a method for ammonia production via waste gasification coupling using the above system, comprising the following steps:

[0013] (1) Waste gasification

[0014] The waste undergoes high-temperature pyrolysis gasification with pure oxygen in the waste gasification device. The pure oxygen used comes from the air separation device. The high-temperature mixed gas generated by the waste gasification enters the self-heating catalytic reforming system. The components of the waste that cannot be gasified are cooled and used as building materials.

[0015] (2) Autothermal catalytic reforming

[0016] The high-temperature mixed gas enters the self-heating catalytic reforming system to react and produce hydrogen and carbon dioxide, and the mixed gas of hydrogen and carbon dioxide enters the gas purification system.

[0017] (3) Gas purification

[0018] After the mixed gas undergoes desulfurization, denitrification and carbon capture treatment in the gas purification system, pure hydrogen is separated.

[0019] (4) Synthesis of ammonia

[0020] The hydrogen produced in step (3) and the nitrogen produced by the air separation device enter the ammonia synthesis system to synthesize ammonia, while the oxygen produced by the air separation device enters the waste gasification device to pyrolyze the waste at high temperature.

[0021] Preferably, the oxygen in the air separation device is preheated three times by the third heat exchanger, the second heat exchanger, and the first heat exchanger before entering the waste gasification device.

[0022] Preferably, the oxygen used in the self-heating catalytic reforming system is oxygen generated by the air separation device and preheated twice by the third heat exchange device and the second heat exchange device.

[0023] Preferably, the reaction temperature in the self-heating catalytic reforming system is 650-750℃, and hydrogen and nitrogen in the ammonia synthesis system are used to synthesize ammonia at 300-500℃.

[0024] In summary, the present invention has the following advantages:

[0025] The technical solution of this invention improves resource utilization by using the oxygen produced by the air separation device as a byproduct of waste gasification, and synthesizing ammonia with the hydrogen produced by waste gasification and the nitrogen produced by the air separation device. This achieves the harmless resource utilization of waste and reduces the cost of waste gasification and ammonia synthesis. The mixed gas produced by waste gasification is then processed through a self-heating catalytic reforming system and a gas purification system to obtain pure hydrogen, which consumes little energy and saves resources.

[0026] The method for co-producing ammonia from waste gasification provided by this invention reduces the cost of waste gasification and ammonia synthesis, and is highly practical. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the system for co-producing ammonia from waste gasification in an embodiment of the present invention.

[0029] Explanation of reference numerals in the attached drawings: 1-Gas gasification unit, 2-Self-heating catalytic reforming system, 3-Gas purification system, 4-Ammonia synthesis system, 5-Air separation unit, 6-First heat exchanger, 7-Second heat exchanger, 8-Third heat exchanger, 9-Oxygen transport pipeline. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Example

[0034] A waste gasification coupled ammonia production system, such as Figure 1 As shown.

[0035] The high-temperature mixed gas outlet of the waste gasification unit 1 is connected to the self-heating catalytic reforming system 2 via a pipeline. The mixed gas outlet of the self-heating catalytic reforming system 2 is connected to the inlet of the gas purification system 3 via a pipeline. The hydrogen outlet of the gas purification system 3 is connected to the hydrogen inlet of the ammonia synthesis system 4 via a pipeline. The nitrogen inlet of the ammonia synthesis system 4 is connected to the nitrogen outlet of the air separator 5 via a pipeline. In this embodiment, the ammonia synthesis system 4 adopts the Haber process for ammonia synthesis. The gas purification system 3 includes desulfurization, denitrification, and carbon capture processes. In this embodiment, the waste gasification unit 1 uses a gasifier.

[0036] A first heat exchanger 6 is installed on the pipeline between the waste gasification unit 1 and the autothermal catalytic reforming system 2. A second heat exchanger 7 is installed on the pipeline between the autothermal catalytic reforming system 2 and the gas purification system 3. A third heat exchanger 8 is provided in the ammonia synthesis system 4. An oxygen transport pipeline 9 is sequentially connected to the air separator 5, the third heat exchanger 8, the second heat exchanger 7, the first heat exchanger 6, and the waste gasification unit 1. The oxygen transport pipeline between the first heat exchanger 6 and the second heat exchanger 7 is connected to the autothermal catalytic reforming system 2 via a pipeline.

[0037] The third heat exchange device 8 preheats the oxygen generated by the air separator 5 with the waste heat generated during the ammonia synthesis process for the first time. The second heat exchange device 7 preheats the oxygen with the mixed gas generated by catalytic reforming for the second time. The first heat exchange device 6 preheats the oxygen with the high-temperature mixed gas generated by waste gasification for the third time. The oxygen after the three preheatings can meet the temperature requirements of waste gasification.

[0038] The self-heating catalytic reforming system 2 and the ammonia synthesis system 4 in this invention both adopt conventional process flows in the art, and the desulfurization, denitrification and carbon capture processes in the gas purification system 3 adopt conventional process flows in the art.

[0039] The method for producing ammonia via waste gasification using the above system comprises the following steps:

[0040] (1) Waste gasification

[0041] Waste enters the waste gasification unit 1 and undergoes high-temperature pyrolysis and gasification to produce a high-temperature mixed gas. The main components of the high-temperature mixed gas are hydrogen, methane, and carbon monoxide. The pure oxygen used comes from the by-product oxygen produced by the air separation unit 5. The oxygen is preheated three times by the third heat exchanger 8, the second heat exchanger 7, and the first heat exchanger 6. The high-temperature mixed gas produced by waste gasification enters the self-heating catalytic reforming system 2. The components of waste that cannot be gasified are cooled to form a hard, glassy residue, which is used as a building material.

[0042] (2) Autothermal catalytic reforming

[0043] The high-temperature mixed gas enters the self-heating catalytic reforming system 2 to produce hydrogen and carbon dioxide. The temperature of the catalytic reforming reaction is controlled at 700℃. The catalytic reforming reaction system itself can achieve self-heating. The oxygen used is generated by the air separation device 5 and provided after being preheated twice by the third heat exchange device 8 and the second heat exchange device 7. The mixed gas of hydrogen and carbon dioxide enters the gas purification system 3.

[0044] (3) Gas purification

[0045] After the mixed gas undergoes desulfurization, denitrification and carbon capture treatment in gas purification system 3, pure hydrogen is separated.

[0046] (4) Ammonia synthesis

[0047] The hydrogen produced in step (3) and the nitrogen produced by the air separation device 5 enter the ammonia synthesis system 4 to synthesize ammonia under high temperature and high pressure conditions. The reaction temperature is controlled at 300-500℃. At the same time, the oxygen produced by the air separation device 5 enters the waste gasification device 1 to pyrolyze the waste at high temperature, so as to realize the full utilization of resources.

[0048] The technical solution provided by this invention employs a pure oxygen high-temperature pyrolysis gasification method for waste gasification. The pure oxygen used is a byproduct of the ammonia synthesis process, and it is preheated three times using a heat cascade utilization principle, passing through the ammonia synthesis process, the pre-purification mixed gas, and a high-temperature mixed gas pipeline heat exchange device. The mixed gas after waste gasification is then subjected to autothermal catalytic reforming to produce hydrogen, resulting in low energy consumption. Simultaneously, the oxygen required for hydrogen production through autothermal catalytic reforming is also preheated twice using a heat cascade utilization principle, passing through the ammonia synthesis process and the pre-purification mixed gas pipeline heat exchange device. This solution fully utilizes the hydrogen produced by waste gasification and the nitrogen and oxygen produced by the air separation device, and makes full use of the waste heat from each process, achieving harmless resource utilization of waste, reducing the cost of waste gasification and ammonia synthesis, enhancing economic efficiency, and demonstrating strong practicality.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for producing ammonia by coupling garbage gasification, characterized by, The system includes a waste gasification device (1), the mixed gas outlet of which is connected to a self-heating catalytic reforming system (2) via a pipeline, the mixed gas outlet of which is connected to the inlet of a gas purification system (3) via a pipeline, the hydrogen outlet of which is connected to the hydrogen inlet of a synthetic ammonia system (4) via a pipeline, the nitrogen inlet of which is connected to the nitrogen outlet of an air separator (5) via a pipeline, and the oxygen outlet of which is connected to the oxygen inlet of the waste gasification device (1) via a pipeline. A first heat exchange device (6) is provided between the waste gasification device (1) and the self-heating catalytic reforming system (2), a second heat exchange device (7) is provided between the self-heating catalytic reforming system (2) and the gas purification system (3), and a third heat exchange device (8) is provided in the ammonia synthesis system (4). It also includes an oxygen transport pipeline (9), which is connected in sequence to the air separation device (5), the third heat exchange device (8), the second heat exchange device (7), the first heat exchange device (6), and the waste gasification device (1); The oxygen transport pipeline between the second heat exchanger (7) and the first heat exchanger (6) is connected to the oxygen inlet of the self-heating catalytic reforming system (2) via a pipeline.

2. The system for ammonia production by waste gasification coupling according to claim 1, characterized in that, The The ammonia synthesis system (4) adopts the Haber process for ammonia synthesis.

3. The system for waste gasification coupled preparation according to claim 1, characterized in that, The gas purification system (3) includes desulfurization, denitrification and carbon capture processes.

4. A method for ammonia production via waste gasification coupling using the system described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Waste gasification Waste undergoes high-temperature pyrolysis gasification with pure oxygen in the waste gasification device (1). The pure oxygen used comes from the air separation device (5). The high-temperature mixed gas generated by waste gasification enters the self-heating catalytic reforming system (2). The components of waste that cannot be gasified are cooled and used as building materials. (2) Autothermal catalytic reforming The high-temperature mixed gas enters the self-heating catalytic reforming system (2) and reacts to generate hydrogen and carbon dioxide. The mixed gas of hydrogen and carbon dioxide enters the gas purification system (3). (3) Gas purification After the mixed gas undergoes desulfurization, denitrification and carbon capture treatment in the gas purification system (3), pure hydrogen is separated. (4) Synthesis of ammonia The hydrogen produced in step (3) and the nitrogen produced by the air separation device (5) enter the ammonia synthesis system (4) to synthesize ammonia. At the same time, the oxygen produced by the air separation device (5) enters the waste gasification device (1) to pyrolyze the waste at high temperature.

5. The method according to claim 4, characterized in that, The oxygen in the air separation device (5) is preheated three times by the third heat exchange device (8), the second heat exchange device (7), and the first heat exchange device (6) before entering the waste gasification device (1).

6. The method according to claim 5, characterized in that, The oxygen used in the self-heating catalytic reforming system (2) is generated by the air separation device (5) and preheated twice by the third heat exchange device (8) and the second heat exchange device (7).

7. The method according to claim 6, characterized in that, The reaction temperature in the self-heating catalytic reforming system (2) is 650-750℃, and hydrogen and nitrogen are synthesized into ammonia in the ammonia synthesis system (4) at 300-500℃.

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