Nitric acid production unit and device

Abstract

The utility model discloses a nitric acid production unit and device, and relates to the technical field of nitric acid production equipment. The nitric acid production unit comprises an air compressor, a nitric oxide compressor, an expansion machine and a driving module, the driving module comprises a driving machine and two first-stage transmission shafts, and the two first-stage transmission shafts are connected with the driving machine; wherein one first-stage transmission shaft is connected with one of the air compressor, the nitrogen oxide compressor and the expansion machine, and the other first-stage transmission shaft is correspondingly connected with the rest one or two of the air compressor, the nitrogen oxide compressor and the expansion machine. According to the nitric acid production unit, the axial length of the nitric acid production unit is shortened, the use number of couplings is reduced, the torsional vibration problem is greatly reduced, and the stability and reliability of the whole nitric acid production unit are greatly improved.

Description

Technical Field

[0001] This application relates to the field of nitric acid production equipment technology, and in particular to a nitric acid production unit and apparatus. Background Technology

[0002] The existing nitric acid production unit consists of four devices connected in series: an air compressor, a nitrogen oxide compressor, an expander, and a steam turbine. A gearbox is installed between the steam turbine and the air compressor to ensure that each device operates at the required speed. The rotors of each device are connected together by couplings, and the devices are connected to the gearbox.

[0003] This configuration results in a unit with a large axial length. The long rotor system rotates at very high speeds, and this multi-coupling combination of long rotors is prone to torsional vibration. Torsional vibration can easily lead to major quality problems such as rotor instability and failure. Utility Model Content

[0004] In view of this, this application provides a nitric acid production unit and apparatus, which aims to solve one of the technical problems in the prior art.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] In a first aspect, embodiments of this application provide a nitric acid production unit, comprising:

[0007] Air compressor;

[0008] Nitrogen oxide compressor;

[0009] Expander;

[0010] The drive module includes a drive motor and two primary drive shafts, the two primary drive shafts being connected to the drive motor respectively;

[0011] One of the primary drive shafts is connected to one of the air compressor, the nitrogen oxide compressor, and the expander, while the other primary drive shaft is connected to one or two of the remaining air compressor, nitrogen oxide compressor, and expander.

[0012] In one embodiment of the first aspect, when one of the primary drive shafts corresponds to the remaining one of the air compressor, the nitrogen oxide compressor, and the expander, one primary drive shaft is connected to the air compressor and the other primary drive shaft is connected to the nitrogen oxide compressor.

[0013] In one embodiment of the first aspect, when another of the primary drive shafts corresponds to the remaining two connections of the air compressor, the nitric oxide compressor, and the expander, the drive module further includes: a gearbox, one of the primary drive shafts being connected to one of the air compressor, the nitric oxide compressor, and the expander, and the other primary drive shaft being connected to the gearbox.

[0014] In one embodiment of the first aspect, the gearbox includes a gear shift shaft, a first secondary drive shaft, and a second secondary drive shaft, wherein the input end of the gear shift shaft is connected to the first primary drive shaft, and the first secondary drive shaft and the second secondary drive shaft are respectively connected to the output end of the gear shift shaft.

[0015] In one embodiment of the first aspect, the air compressor includes at least one air compressor rotor;

[0016] The nitrogen oxide compressor includes at least one nitrogen oxide compressor rotor;

[0017] The expander includes at least one expander rotor;

[0018] The air compressor rotor, the nitrogen oxide compressor rotor, and the expander rotor are respectively connected to the primary drive shaft; or, the air compressor rotor, the nitrogen oxide compressor rotor, and the expander rotor are respectively connected to the first secondary drive shaft or the second secondary drive shaft.

[0019] In one embodiment of the first aspect, the drive is an electric motor with a rated speed of not less than 3000 rpm.

[0020] In one embodiment of the first aspect, both the air compressor and the nitrogen oxide compressor are centrifugal compressors.

[0021] In one embodiment of the first aspect, the expander is a centripetal or axial flow expander.

[0022] Secondly, embodiments of this application also provide a nitric acid production apparatus, comprising:

[0023] The nitric acid production unit in any of the above embodiments;

[0024] An oxidation furnace is connected to the air compressor;

[0025] A heat exchanger connects the nitrogen oxide compressor and the oxidation furnace.

[0026] In one embodiment of the second aspect, the nitric acid production apparatus further includes:

[0027] An absorption tower, wherein the absorption tower is connected to the nitrogen oxide compressor and the expander; or, the absorption tower is connected to the nitrogen oxide compressor.

[0028] Compared to existing technologies, the advantages of this application are as follows: This application proposes a nitric acid production unit, including a drive module, an air compressor, a nitrogen oxide compressor, and an expander. The drive module includes a drive motor and two primary drive shafts, each connected to the drive motor. One primary drive shaft is connected to one of the air compressor, nitrogen oxide compressor, and expander, while the other primary drive shaft is connected to one or two of the remaining components. This structure shortens the axial length of the nitric acid production unit and reduces the number of couplings used, significantly reducing torsional vibration problems and greatly improving the stability and reliability of the entire nitric acid production unit. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 A schematic diagram of the structure of a nitric acid production unit in the relevant technology is shown;

[0031] Figure 2 This application shows one of the structural schematic diagrams of a nitric acid production apparatus in some embodiments;

[0032] Figure 3 This is shown as a second schematic diagram of the structure of a nitric acid production apparatus in some embodiments of this application;

[0033] Figure 4 The third schematic diagram of the nitric acid production apparatus in some embodiments of this application is shown;

[0034] Figure 5 The fourth schematic diagram of the nitric acid production apparatus in some embodiments of this application is shown;

[0035] Figure 6 The fifth of some embodiments of the nitric acid production apparatus shown in this application is a schematic diagram of its structure.

[0036] Figure 7 Sixth of the structural schematic diagrams of nitric acid production apparatuses in some embodiments of this application is shown;

[0037] Figure 8 The seventh of some embodiments of the nitric acid production apparatus shown is a schematic diagram of the structure of the apparatus.

[0038] Explanation of key component symbols:

[0039] 1000 - Nitric acid production unit; 100 - Nitric acid production unit; 200 - Oxidation furnace; 300 - Heat exchanger; 400 - Absorption tower;

[0040] 110-Drive module; 111-Drive motor; 112-Gearbox; 1111-First stage drive shaft; 1121-Transmission shaft; 1122-First and second stage drive shafts; 1123-Second stage drive shaft; 120-Air compressor; 130-Nitrogen oxide compressor; 140-Expander. Detailed Implementation

[0041] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0042] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0043] In this application, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0044] Example 1

[0045] Please see Figure 1The existing nitric acid production unit consists of four units connected in series: an air compressor, a nitrogen oxide compressor, an expander, and a steam turbine. Specifically, the turbine rotor is connected to one gear shaft of the gearbox via a coupling, while the other gear shaft of the gearbox is connected to the air compressor, nitrogen oxide compressor, and expander via three couplings. This configuration results in a large axial length for the entire unit. The long rotor system rotates at very high speeds, and this multi-coupling combination of long rotor structures is susceptible to torsional vibration. Torsional vibration can easily lead to significant quality problems such as rotor instability and failure.

[0046] In response to the above problems, such as Figures 2 to 8 As shown, an embodiment of this application provides a nitric acid production unit 100, mainly used for producing nitric acid. The nitric acid production unit 100 includes an air compressor 120, a nitrogen oxide compressor 130, an expander 140, and a drive module 110.

[0047] The drive module 110 includes a drive motor 111 and two primary drive shafts 1111, which are respectively connected to the drive motor 111.

[0048] One primary drive shaft 1111 is connected to one of the air compressor 120, the nitrogen oxide compressor 130, and the expander 140, and the other primary drive shaft 1111 is connected to one or two of the remaining air compressor 120, the nitrogen oxide compressor 130, and the expander 140.

[0049] It should be noted that the primary drive shaft 1111 serves as the rotor of the air compressor 120, nitrogen oxide compressor 130, or expander 140. The impellers of the air compressor 120, nitrogen oxide compressor 130, or expander 140 are directly mounted on the primary drive shaft 1111. This structure allows the air compressor 120, nitrogen oxide compressor 130, and expander 140 to be directly connected to the primary drive shaft 1111 of the drive unit 111, shortening the axial length of the nitric acid production unit 100 and reducing the number of couplings used. This significantly reduces torsional vibration problems and greatly improves the stability and reliability of the entire nitric acid production unit 100.

[0050] in addition, Figure 1 The nitric acid production unit 100 consists of four devices connected in series: an air compressor, a nitrogen oxide compressor 130, an expander 140, and a steam turbine. The entire unit system has a large axial length, requiring a large floor space and having a large overall size, which is not conducive to its widespread use.

[0051] This application shortens the axial length of the nitric acid production unit 100 by setting the drive motor 111 to have two primary connecting shafts, making the entire unit structure more compact, highly integrated, and smaller in size.

[0052] It is understandable that the tail gas produced during the production of nitric acid can be used in other places. Therefore, in some cases, the expander 140 may not be installed in the nitric acid production unit 100, but only the air compressor 120 and the nitrogen oxide compressor 130 may be installed.

[0053] To address the above situation, in some embodiments, when another primary drive shaft 1111 is connected to the remaining one of the air compressor 120, nitrogen oxide compressor 130, and expander 140, one primary drive shaft 1111 is connected to the air compressor 120, and the other primary drive shaft 1111 is connected to the nitrogen oxide compressor 130. By making the primary drive shaft 1111 the rotor of either the air compressor 120 or the nitrogen oxide compressor 130, and directly mounting the impeller of either the air compressor 120 or the nitrogen oxide compressor 130 on the primary drive shaft 1111, the axial length of the nitric acid production unit 100 is shortened, and the number of couplings and gearboxes 112 used is reduced, significantly reducing torsional vibration problems and greatly improving the stability and reliability of the entire nitric acid production unit 100.

[0054] For example, such as Figure 2 As shown, the primary drive shaft 1111 on the left side of the drive motor 111 is connected to the air compressor 120, and the primary drive shaft 1111 on the right side of the drive motor 111 is connected to the nitrogen oxide compressor 130.

[0055] Normally, when the nitric acid production unit 1000 can provide high-temperature, high-pressure gas to drive the expander 140, the work done by the expander 140 is used to supplement the compression work required in the unit (the power required by the air compressor 120 and the nitrogen oxide compressor 130 to compress the gas). Essentially, the motor and expander 140 act as power sources, providing energy to the air compressor 120 and the nitrogen oxide compressor 130 for gas compression, thereby reducing the power consumption of the drive motor 111 and improving the overall operating efficiency of the unit.

[0056] In response to the above situation, in some embodiments, when another primary drive shaft 1111 corresponds to the connection of the remaining two of the air compressor 120, nitrogen oxide compressor 130 and expander 140, the drive module 110 also includes a gearbox 112, one primary drive shaft 1111 is connected to one of the air compressor 120, nitrogen oxide compressor 130 and expander 140, and the other primary drive shaft 1111 is connected to the gearbox 112.

[0057] In one embodiment, the gearbox 112 includes a shift shaft 1121, a first secondary drive shaft 1122, and a second secondary drive shaft 1123. The input end of the shift shaft 1121 is connected to the primary drive shaft 1111, and the first secondary drive shaft 1122 and the second secondary drive shaft 1123 are respectively connected to the output end of the shift shaft 1121. By configuring the gearbox 112, the drive motor 111, which originally had two primary drive shafts 1111 forming two output ends, becomes a machine with one primary drive shaft 1111, a first secondary drive shaft 1122, and a second secondary drive shaft 1123, forming three output ends. By increasing the number of connected ends, the two primary drive shafts 1111 of the drive motor 111 can simultaneously drive the air compressor 120, the nitrogen oxide compressor 130, and the expander 140 to rotate.

[0058] In addition, when the nitric acid production unit 1000 can provide high-temperature and high-pressure gas to drive the expander 140 to do work, the drive motor 111 and the expander 140 act as power sources to do work and deliver power to the air compressor 120 and the nitrogen oxide compressor 130, providing them with the energy to compress the gas, thereby reducing the power consumption of the drive motor 111 and improving the operating efficiency of the entire unit.

[0059] In one embodiment, the air compressor 120 includes at least one air compressor rotor, the nitrogen oxide compressor 130 includes at least one nitrogen oxide compressor 130 rotor, and the expander 140 includes at least one expander 140 rotor.

[0060] It should be noted that the air compressor rotor, the 130 rotor of the nitrogen oxide compressor, and the 140 rotor of the expander all refer to the impeller or impeller shaft. Figures 2 to 8 The air compressor 120, the nitrogen oxide compressor 130, and the expander 140 are respectively the air compressor rotor, the nitrogen oxide compressor rotor, and the expander rotor.

[0061] When the air compressor rotor, the nitrogen oxide compressor rotor, and the expander rotor are connected to the gearbox 112, the gearbox 1121 acts as the rotor of the impeller or impeller shaft, driving the impeller or impeller shaft to rotate.

[0062] The air compressor rotor, nitrogen oxide compressor rotor, and expander rotor are respectively connected to the primary drive shaft 1111; or, the air compressor rotor, nitrogen oxide compressor rotor, and expander rotor are respectively connected to the first and second secondary drive shafts 1122 or the second and second secondary drive shafts 1123, making the structure of the air compressor 120, nitrogen oxide compressor 130, and expander 140 connected to the drive motor 111 more compact, shortening the axial length of the nitric acid production unit 100, and reducing the number of couplings and gearboxes 112 used, greatly reducing torsional vibration problems, and significantly improving the stability and reliability of the entire nitric acid production unit 100.

[0063] For example, such as Figure 3and Figure 4 As shown, the primary drive shaft 1111 on the left side of the drive motor 111 is connected to the expander rotor, and the gearbox 112 on the right side of the drive motor 111 is connected to the air compressor rotor and the nitrogen oxide compressor rotor.

[0064] For example, such as Figure 5 and Figure 6 As shown, the primary drive shaft 1111 on the left side of the drive motor 111 is connected to the air compressor rotor, and the gearbox 112 on the right side of the drive motor 111 is connected to the expander rotor and the nitrogen oxide compressor rotor.

[0065] For example, such as Figure 7 and Figure 8 As shown, the primary drive shaft 1111 on the left side of the drive motor 111 is connected to the rotor of the nitrogen oxide compressor, and the gearbox 112 on the right side of the drive motor 111 is connected to the rotor of the air compressor and the rotor of the expander.

[0066] In some embodiments, the drive unit 111 is an electric motor. In related technologies, the drive unit 111 uses a steam turbine, which is driven by steam and requires a gas source, while an electric motor only needs to be connected to a power source, making it more widely applicable.

[0067] When the nitric acid production unit 100 is first started, the motor is mainly used to drive the air compressor 120 and the nitrogen oxide compressor 130 to compress the gas. When the nitric acid production unit 1000 can provide high-temperature and high-pressure gas to drive the expander 140, the work done by the expander 140 is used to supplement the compression work required in the unit (the power required by the air compressor 120 and the nitrogen oxide compressor 130 to compress the gas), thereby reducing the power consumption of the motor and improving the overall operating efficiency of the unit.

[0068] This is equivalent to the motor and expander 140 acting as power sources to do work and supply energy to the air compressor 120 and the nitrogen oxide compressor 130, providing them with the energy to compress the gas.

[0069] It should be noted that the design speed required for the air compressor rotor, nitrogen oxide compressor rotor, and expander rotor is higher than the synchronous speed of 3000 rpm for a typical three-phase asynchronous motor.

[0070] In view of the above, the motor in this application is a common three-phase asynchronous motor or a permanent magnet variable frequency synchronous motor.

[0071] When using a conventional three-phase asynchronous motor, similar to existing turbine drives, the air compressor rotor, nitric oxide compressor rotor, and expander rotor all require speed-changing gears to achieve speed increase. Furthermore, regardless of whether the drive unit 111 uses an existing turbine or a conventional three-phase asynchronous motor, the output shaft of the drive unit 111 generally needs to be connected to the drive gear shaft (i.e., the input large gear shaft) in the speed-changing gearbox via a coupling.

[0072] When using a permanent magnet synchronous variable frequency motor (high-speed motor), compared to a typical three-phase asynchronous motor (rated frequency 50Hz, synchronous speed 3000rpm, rated speed around 2970rpm; due to the structural principle of asynchronous motors, there will be a slip rate, so the rated speed of an asynchronous motor will be slightly lower than its synchronous speed), the rated frequency of a high-speed motor is not limited to 50Hz (that is, the rated frequency of a high-speed motor can be higher than 50Hz, and the synchronous speed can also be higher than 3000rpm; and high-speed motors are generally synchronous motors, and their rated speed is the synchronous speed. For example, a permanent magnet synchronous variable frequency high-speed motor with a rated frequency of 800Hz has a rated speed of 48000rpm, and can achieve stepless speed regulation by changing the motor frequency through a frequency converter within the rated speed range).

[0073] Using a high-speed motor as the drive unit 111, the output shafts at both ends of the high-speed motor serve as the rotors of the air compressor, nitrogen oxide compressor 130, and exhaust gas expander 140, respectively. The impellers of the air compressor or nitrogen oxide compressor 130 and the exhaust gas expander 140 are directly mounted on the output shafts at both ends of the high-speed motor, reducing the number of couplings used and greatly reducing torsional vibration problems. The stability and reliability of the entire nitric acid production unit 100 are greatly improved.

[0074] In some embodiments, the air compressor 120 and the nitrogen oxide compressor 130 are both centrifugal compressors, and the expander 140 is a centripetal or axial flow expander 140. The air compressor 120, the nitrogen oxide compressor 130, and the expander 140 are all rotary turbine machines that generate centrifugal or centripetal force through the rotation of the impeller to perform work.

[0075] Example 2

[0076] Please refer to the following: Figures 2 to 8 This application also provides a nitric acid production apparatus 1000, including the nitric acid production unit 100, oxidation furnace 200, heat exchanger 300 and absorption tower 400 in any of the above embodiments.

[0077] The oxidation furnace 200 is connected to the air compressor 120.

[0078] Specifically, the oxidation furnace 200 is located at the compressed air output end of the air compressor 120.

[0079] Oxidation furnace 200 is used to mix compressed air and ammonia to produce high-temperature nitrogen oxide gas.

[0080] The heat exchanger 300 is connected to the nitrogen oxide compressor 130 and the oxidizer 200.

[0081] It needs to be explained, such as Figure 2As shown, in some embodiments, when the expander 140 is not installed in the nitric acid production unit 100, the absorber 400 is connected to the nitrogen oxide compressor 130.

[0082] like Figures 3 to 8 As shown, in some embodiments, when an expander 140 is provided in the nitric acid production unit 100, the absorption tower 400 is connected to the nitrogen oxide compressor 130 and the expander 140.

[0083] Specifically, the heat exchanger 300 is installed at the high-temperature nitrogen oxide gas output end of the oxidizing furnace 200. The heat exchanger 300 is used to cool the high-temperature nitrogen oxide gas. The heat exchanger 300 is also installed at the gas input end of the nitrogen oxide compressor 130.

[0084] The absorption tower 400 is connected to the nitrogen oxide compressor 130 and the expander 140.

[0085] Specifically, the absorption tower 400 is located at the compressed gas output end of the nitrogen oxide compressor 130, and the expander 140 is located at the tail gas output end of the absorption tower 400.

[0086] The compressed nitrogen oxide gas produced by the nitrogen oxide compressor 130 is fed into the absorption tower 400 to produce nitric acid, and the tail gas produced by the absorption tower 400 is supplied to the expander 140 to perform work.

[0087] It should be noted that please refer to the following: Figures 1 to 3 In related technologies, a steam turbine is used as the drive module 110. Since the steam turbine requires a certain amount of steam to operate, the relevant technologies typically add a boiler to produce a certain amount of steam to drive the steam turbine. Before the nitric acid production unit 100 is started, the oxidizer 200 cannot generate heat to supply the steam boiler to produce steam. Therefore, additional steam is needed to drive the steam turbine when the unit starts up. Only after the entire equipment is fully operational can the self-sufficiency of steam required to drive the steam turbine be achieved. This not only makes the entire unit more complex but also adds a lot of large equipment.

[0088] In response to the above problems, such as Figures 2 to 8 As shown, the drive module 110 of this application uses an electric motor 111 for its drive unit, replacing the steam turbine in the related art. Thus, at the start-up of the nitric acid production unit 1000, the nitric acid production unit 100 drives the air compressor 120, the nitrogen oxide compressor 130, and the expander 140 via the electric motor. This replaces the operation method in the related art that requires additional steam to drive the steam turbine, which in turn drives the air compressor 120, the nitrogen oxide compressor 130, and the expander 140. Furthermore, it eliminates the need for additional steam-generating equipment such as boilers, simplifying the overall composition of the nitric acid production unit 1000.

[0089] In addition, when the oxidizer 200 can generate heat to supply the boiler to produce steam, the steam enters the expander 140 to do work and is then discharged into the atmosphere. The motor is mainly used to drive the air compressor 120 and the nitrogen oxide compressor 130 to compress the gas and do work.

[0090] The work done by expander 140 supplements the compression work required by the unit (the power needed by air compressor 120 and nitrogen oxide compressor 130 to compress gas), thereby reducing the power consumption of the motor and improving the overall operating efficiency of the unit. Essentially, the motor and expander 140 act as power sources, performing work and supplying it to air compressor 120 and nitrogen oxide compressor 130 to provide them with the energy for compressing gas.

[0091] The entire equipment process is relatively simple and efficient. The heat exchanger 300 can be replaced by a boiler to produce steam to drive the expander 140. Especially during the start-up phase of the entire unit, there is no need to obtain additional steam through other methods to provide steam for turbine drive during unit startup.

[0092] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0093] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A nitric acid production unit, characterized in that, include: Air compressor; Nitrogen oxide compressor; Expander; The drive module includes a drive motor and two primary drive shafts, which are respectively connected to the drive motor. The drive motor is a permanent magnet variable frequency synchronous motor. One of the primary drive shafts is connected to one of the air compressor, the nitrogen oxide compressor, and the expander, and the other primary drive shaft is connected to one or two of the remaining air compressor, nitrogen oxide compressor, and expander. The output shafts at both ends of the permanent magnet variable frequency synchronous motor serve as the rotors of the air compressor, the nitrogen oxide compressor, and the expander, respectively, and the impellers of the air compressor or the nitrogen oxide compressor and the expander are directly mounted on the output shaft of the permanent magnet variable frequency synchronous motor.

2. The nitric acid production unit according to claim 1, characterized in that, When one of the primary drive shafts corresponds to the remaining one of the air compressor, the nitrogen oxide compressor, and the expander, one primary drive shaft is connected to the air compressor, and the other primary drive shaft is connected to the nitrogen oxide compressor.

3. The nitric acid production unit according to claim 1, characterized in that, When another primary driveshaft corresponds to the remaining two connections of the air compressor, the nitric oxide compressor, and the expander, the drive module further includes: a gearbox, one primary driveshaft connected to one of the air compressor, the nitric oxide compressor, and the expander, and the other primary driveshaft connected to the gearbox.

4. The nitric acid production unit according to claim 3, characterized in that, The gearbox includes a gear shift shaft, a first secondary drive shaft, and a second secondary drive shaft. The input end of the gear shift shaft is connected to the first primary drive shaft, and the first secondary drive shaft and the second secondary drive shaft are respectively connected to the output end of the gear shift shaft.

5. The nitric acid production unit according to claim 4, characterized in that, The air compressor includes at least one air compressor rotor; The nitrogen oxide compressor includes at least one nitrogen oxide compressor rotor; The expander includes at least one expander rotor; The air compressor rotor, the nitrogen oxide compressor rotor, and the expander rotor are respectively connected to the primary drive shaft; or, the air compressor rotor, the nitrogen oxide compressor rotor, and the expander rotor are respectively connected to the first secondary drive shaft or the second secondary drive shaft.

6. The nitric acid production unit according to any one of claims 1 to 5, characterized in that, The drive unit is an electric motor, and the rated speed of the electric motor is not less than 3000 rpm.

7. The nitric acid production unit according to any one of claims 1 to 5, characterized in that, Both the air compressor and the nitrogen oxide compressor are centrifugal compressors.

8. The nitric acid production unit according to any one of claims 1 to 5, characterized in that, The expander is a centripetal or axial flow expander.

9. A nitric acid production apparatus, characterized in that, include: The nitric acid production unit according to any one of claims 1 to 8; An oxidation furnace is connected to the air compressor; A heat exchanger connects the nitrogen oxide compressor and the oxidation furnace.

10. The nitric acid production apparatus according to claim 9, characterized in that, The nitric acid production unit also includes: An absorption tower, wherein the absorption tower is connected to the nitrogen oxide compressor and the expander; or, the absorption tower is connected to the nitrogen oxide compressor.

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