A system for supplementing high-pressure nitrogen in the ammonia synthesis process

Abstract

This utility model discloses a system for supplementing high-pressure nitrogen in the ammonia synthesis process, including a liquid nitrogen vaporization branch and a first vaporization device and a second vaporization device connected in parallel to the liquid nitrogen vaporization branch. A high-pressure liquid nitrogen pump is installed on the liquid nitrogen vaporization branch. The first vaporization device includes a water bath vaporizer, which has a first liquid inlet pipe connected to the liquid nitrogen vaporization branch and a first liquid outlet pipe connected to the hydrogen-nitrogen gas pipeline network at the outlet of the synthesis compressor. A temperature and pressure interlock device is installed on the first liquid outlet pipe. The second vaporization device includes a liquid nitrogen-water heat exchanger, which has a second liquid inlet pipe connected to the liquid nitrogen vaporization branch and a second liquid outlet pipe connected to the hydrogen-nitrogen gas pipeline network at the outlet of the synthesis compressor. This utility model uses liquid nitrogen vaporization technology to replace the original gas-to-gas synthesis process, effectively solving the problems of high power consumption and high energy consumption of the ammonia synthesis compressor, while also recovering the cold energy generated by liquid nitrogen vaporization.

Description

Technical Field

[0001] This utility model belongs to the field of synthetic ammonia production technology, and specifically relates to a system for supplementing high-pressure nitrogen gas in the synthetic ammonia production process. Background Technology

[0002] The traditional hydrogen-nitrogen compression process for ammonia synthesis involves combining fresh synthesis gas (a hydrogen-nitrogen mixture at 5.18 MPa) from the purification process with flash vapor from the ammonia separator in the ammonia synthesis section. This mixture then enters the synthesis gas compressor, first undergoing compression and cooling in the low-pressure cylinder, followed by further compression to 13.66 MPa in the high-pressure cylinder. There, it is combined with recirculated gas from the ammonia synthesis unit and compressed to 14.4 MPa in the compressor's recirculation section before being sent to the ammonia synthesis unit. All the hydrogen-nitrogen mixture in the system is pressurized to 14.4 MPa by the synthesis gas compressor before being sent to the ammonia synthesis unit, resulting in high compressor power consumption and energy consumption. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide a reasonably designed, simple and reliable system for supplementing high-pressure nitrogen in the process of synthetic ammonia production, which addresses the shortcomings of the existing technology.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A system for supplementing high-pressure nitrogen in the ammonia synthesis process is characterized in that the system is located between the air separation pipeline and the hydrogen-nitrogen pipeline network at the outlet of the synthesis compressor, and includes a liquid nitrogen vaporization branch and a first vaporization unit and a second vaporization unit connected in parallel on the liquid nitrogen vaporization branch. A high-pressure liquid nitrogen pump is installed on the liquid nitrogen vaporization branch. The first vaporization device includes a water bath vaporizer, which is provided with a first liquid inlet pipe connected to the liquid nitrogen vaporization branch and a first liquid outlet pipe connected to the hydrogen and nitrogen gas pipeline network at the outlet of the synthesis compressor. The second vaporization device includes a liquid nitrogen-water heat exchanger. The liquid nitrogen-water heat exchanger is provided with a second inlet pipe connected to the liquid nitrogen vaporization branch and a second outlet pipe connected to the hydrogen-nitrogen gas pipeline network at the outlet of the synthesis compressor. Temperature and pressure interlocking devices are installed on both the first outlet pipe and the second outlet pipe.

[0005] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the outlet end of the high-pressure liquid nitrogen pump is connected to a liquid nitrogen storage tank through a return pipeline.

[0006] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the high-pressure liquid nitrogen pump is a horizontal piston pump with a design flow rate of 5000 m³ / h, and the horizontal piston pump is equipped with a variable frequency speed control unit to adapt to different working conditions.

[0007] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the temperature and pressure interlocking device includes a temperature sensor and a pressure sensor installed on the first liquid outlet pipe or the second liquid outlet pipe, and both the temperature sensor and the pressure sensor are signal connected to the high-pressure liquid nitrogen pump through the controller.

[0008] The technical problem to be solved by this utility model can also be achieved through the following technical solution: a number of safety valves are installed on the liquid nitrogen vaporization branch, and the outlet of the safety valve is connected to a special pressure relief and discharge tank through a low-temperature insulation pipeline.

[0009] The technical problem to be solved by this utility model can also be achieved through the following technical solution: the opening pressure of the safety valve is set to 17MPa.

[0010] Compared with existing technologies, this invention uses liquid nitrogen vaporization to replace the original gas-to-gas synthesis process, effectively solving the problems of high power consumption and high energy consumption of the ammonia synthesis compressor. It can also recover the cold energy generated by liquid nitrogen vaporization. By adding a high-pressure liquid nitrogen pump and equipping it with a variable frequency speed control system, it can adapt to different working conditions. The first vaporization device and the second vaporization device are set in parallel, respectively suitable for liquid nitrogen vaporization in winter and summer, which improves the safety of the device and also improves the efficiency of cold energy recovery. Attached Figure Description

[0011] Figure 1 This is a structural diagram of the system for supplementing high-pressure nitrogen gas in the ammonia synthesis process described in this utility model.

[0012] In the diagram: 1-Liquid nitrogen vaporization branch, 2-High-pressure liquid nitrogen pump, 3-Safety valve, 4-Temperature and pressure interlock device, 5-Liquid nitrogen water heat exchanger, 6-Water bath vaporizer, 7-Return pipeline. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0014] Reference Figure 1 A system for supplementing high-pressure nitrogen in the ammonia synthesis process is disclosed. This system is located between the air separation pipeline and the hydrogen-nitrogen pipeline network at the outlet of the synthesis compressor. It includes a liquid nitrogen vaporization branch 1 and a first vaporization unit and a second vaporization unit connected in parallel to the liquid nitrogen vaporization branch 1. A high-pressure liquid nitrogen pump 2 is installed on the liquid nitrogen vaporization branch 1; The first vaporization device includes a water bath vaporizer 6, which is provided with a first liquid inlet pipe connected to the liquid nitrogen vaporization branch 1 and a first liquid outlet pipe connected to the hydrogen and nitrogen gas pipeline network at the outlet of the synthesis compressor. The second vaporization device includes a liquid nitrogen-water heat exchanger 5. The liquid nitrogen-water heat exchanger 5 is provided with a second inlet pipe connected to the liquid nitrogen vaporization branch 1 and a second outlet pipe connected to the hydrogen-nitrogen gas pipeline network at the outlet of the synthesis compressor. Temperature and pressure interlocking devices 4 are installed on both the first outlet pipe and the second outlet pipe.

[0015] The outlet end of the high-pressure liquid nitrogen pump 2 is connected to a liquid nitrogen storage tank via a return pipeline 7.

[0016] The high-pressure liquid nitrogen pump 2 is a horizontal piston pump with a designed flow rate of 5000 m³ / h. The horizontal piston pump is equipped with a variable frequency speed control unit to adapt to different working conditions.

[0017] The temperature and pressure interlock device 4 includes a temperature sensor and a pressure sensor installed on the first or second liquid outlet pipe. Both the temperature sensor and the pressure sensor are connected to the high-pressure liquid nitrogen pump via a controller.

[0018] Several safety valves 3 are installed on the liquid nitrogen vaporization branch 1. The outlet of each safety valve 3 is connected to a dedicated pressure relief tank via a cryogenic insulation pipeline. The opening pressure of each safety valve 3 is set to 17 MPa. The liquid nitrogen-water heat exchanger and water bath vaporizer mentioned above are both commercially available products.

[0019] A method for supplementing high-pressure nitrogen in the above-mentioned ammonia synthesis process, wherein liquid nitrogen, under the action of high-pressure liquid nitrogen pump 2, enters the first gasification device or the second gasification device through the liquid nitrogen vaporization branch 1, and the nitrogen gas vaporized by the first gasification device or the second gasification device is sent to the hydrogen-nitrogen gas pipeline network at the outlet of the synthesis compressor. During the liquid nitrogen vaporization process, under the control of the temperature and pressure interlock device, when the temperature of the vaporized nitrogen is lower than -15℃ or the pressure exceeds 16.5MPa, the liquid nitrogen pump will automatically stop working; at the same time, the liquid nitrogen will be led to a dedicated pressure relief and discharge tank through the safety valve outlet and the cryogenic insulation pipeline.

[0020] The system and process described in this invention change the traditional process of pressurizing hydrogen and nitrogen gas produced by synthetic ammonia through a compressor. Instead, it uses a high-pressure liquid nitrogen pump to pressurize the cryogenic liquid nitrogen generated in the air separation unit. The pressurized high-pressure liquid nitrogen is then vaporized into high-pressure gaseous nitrogen through a water bath vaporizer or a liquid nitrogen-water heat exchanger, which is then added to the hydrogen and nitrogen gas pipeline system that is pressurized by a compressor in the traditional synthetic ammonia production process. This solves the problem of high power consumption and high energy consumption of the synthetic ammonia compressor, and also recovers the cold energy generated by the vaporization of liquid nitrogen.

[0021] The system and process described in this utility model have good economic benefits: 1. Basis for Analysis The total daily liquid nitrogen evaporation volume is approximately 90 tons, with a price of 330 yuan per ton. Reduced main system energy consumption: Liquid nitrogen pump 140kw / h (dual pump operation) cost equivalent to 24kw / h, 1881.6 yuan. The cost of adding a liquid nitrogen pump with a power of 90KW / h is equivalent to 24 RMB / h, or 1209.6 RMB. 2. Technical and economic indicators achieved The reduction in total liquid nitrogen vaporization and evaporation during dual-pump operation is approximately 4 tons per hour, with a selling price of around 330 yuan per ton. Main system energy consumption is reduced by 140 kW / h for the liquid nitrogen pump (dual-pump operation). The additional operating cost of the liquid nitrogen pump is 90 kW / h.

[0022] With an annual operating time of 8,000 hours, it is estimated that waste in liquid products will be reduced by 10.56 million yuan, energy costs of the main system nitrogen pump will be reduced by 627,200 yuan, and the operating cost of the newly added nitrogen pump system will be 403,200 yuan, resulting in annual profit savings of approximately 10.784 million yuan. This also avoids the risk of equipment shutdown due to damage from high-load operation.

[0023] Furthermore, after the project is completed, it will comply with the company's energy conservation and emission reduction policies, reduce liquid nitrogen evaporation requirements, increase the company's sales revenue, and improve the company's economic efficiency. The unit price of liquid nitrogen is 330 yuan / ton. The main system's energy consumption will be reduced. The cost of the 140kw / h liquid nitrogen pump (dual-pump operation) is equivalent to 24 yuan / h, or 1881.6 yuan. The cost of operating the newly added liquid nitrogen pump is also equivalent to 24 yuan / h, or 1209.6 yuan.

[0024] 3. Social benefits Adding a liquid nitrogen pump system to the air separation workshop reduces liquid nitrogen evaporation, aligning with energy conservation and emission reduction policies and promoting a more rational allocation of energy resources. This also lowers equipment operating energy consumption and reduces enterprise operating costs. Simultaneously, the load on the syngas compressor is relatively reduced, saving steam.

[0025] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A system for supplementing high-pressure nitrogen gas during ammonia synthesis production, characterized in that, The system is located between the air separation pipeline and the hydrogen and nitrogen gas pipeline network at the outlet of the synthesis compressor. It includes a liquid nitrogen vaporization branch and a first vaporization unit and a second vaporization unit connected in parallel on the liquid nitrogen vaporization branch. A high-pressure liquid nitrogen pump is installed on the liquid nitrogen vaporization branch. The first vaporization device includes a water bath vaporizer, which is provided with a first liquid inlet pipe connected to the liquid nitrogen vaporization branch and a first liquid outlet pipe connected to the hydrogen and nitrogen gas pipeline network at the outlet of the synthesis compressor. The second vaporization device includes a liquid nitrogen-water heat exchanger. The liquid nitrogen-water heat exchanger is provided with a second inlet pipe connected to the liquid nitrogen vaporization branch and a second outlet pipe connected to the hydrogen-nitrogen gas pipeline network at the outlet of the synthesis compressor. Temperature and pressure interlocking devices are installed on both the first outlet pipe and the second outlet pipe.

2. The system for supplementing high-pressure nitrogen in the ammonia synthesis process according to claim 1, characterized in that, The outlet end of the high-pressure liquid nitrogen pump is connected to a liquid nitrogen storage tank via a return pipeline.

3. The system for supplementing high-pressure nitrogen in the ammonia synthesis process according to claim 1, characterized in that, The high-pressure liquid nitrogen pump is a horizontal piston pump with a designed flow rate of 5000 m³ / h. The horizontal piston pump is equipped with a variable frequency speed control unit to adapt to different working conditions.

4. A system for supplementing high-pressure nitrogen in the ammonia synthesis process according to claim 1, characterized in that, The temperature and pressure interlock device includes a temperature sensor and a pressure sensor installed on the first or second liquid outlet pipe. Both the temperature sensor and the pressure sensor are connected to the high-pressure liquid nitrogen pump via a controller.

5. A system for supplementing high-pressure nitrogen in the ammonia synthesis process according to claim 1, characterized in that, Several safety valves are installed on the liquid nitrogen vaporization branch, and the outlets of the safety valves are connected to a dedicated pressure relief and discharge tank via a cryogenic insulation pipeline.

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