Low-energy-consumption synthetic ammonia production device

Abstract

The utility model relates to a low-energy-consumption synthetic ammonia production device which comprises a synthetic ammonia reactor, a feed port of the synthetic ammonia reactor is communicated with a raw material gas mixing tank, a discharge port of the synthetic ammonia reactor is connected with an inlet of a membrane separator, a gas inlet of the synthetic ammonia reactor is connected with a raw material nitrogen input pipe through a nitrogen branch, and a gas outlet of the synthetic ammonia reactor is communicated with a gas-liquid separator after passing through a cooling component; the raw material gas mixing tank is respectively connected with a raw material nitrogen input pipe and a raw material hydrogen input pipe through a nitrogen main path and a hydrogen pipeline; a permeation side outlet of the membrane separator is connected with a gas outlet of the synthetic ammonia reactor, and a retentate side outlet of the membrane separator is connected with a feed port of the synthetic ammonia reactor after passing through a circulating gas mixing tank; a liquid ammonia outlet of the gas-liquid separator is communicated with the liquid ammonia collector, and a gas outlet of the gas-liquid separator is communicated with the circulating gas mixing tank. According to the utility model, the separation temperature of liquid ammonia can be greatly improved, a liquid ammonia cooling system does not need to be additionally arranged, the energy consumption is effectively reduced, and energy conservation and environmental protection are facilitated.

Description

Technical Field

[0001] The utility model relates to chemical equipment, in particular to a synthetic ammonia production device, specifically to a low-energy consumption synthetic ammonia production device. Background Art

[0002] Ammonia is one of the most important basic chemicals in the fields of agriculture, chemical industry, energy, etc. About 75% of ammonia is used in fertilizer manufacturing to increase global food production. In addition, as a carbon-free and stable hydrogen storage medium, ammonia has a mass hydrogen storage density and a volume hydrogen storage density of 17.7 wt% and 108 g / L, respectively, showing great application prospects in the new energy industry chain.

[0003] At present, almost all ammonia synthesis processes in the world use the Haber-Bosch method. During the production process, due to the thermodynamic and kinetic equilibrium limitations of the ammonia synthesis reaction, the Haber-Bosch method ammonia production reaction needs to be carried out at high temperature (673K~773K) and high pressure (>100 bar), and the single conversion rate is only about 13%. Therefore, the gas after the reaction needs to be cooled and separated (<-10℃) before the liquid ammonia product can be obtained. Cooling the high-temperature ammonia mixture to a low temperature where liquid ammonia can be separated will generate huge cooling energy consumption, making ammonia synthesis a typical high-energy production process. According to statistics, the current energy consumption of Haber-Bosch ammonia production exceeds 1% of the world's total energy consumption, and the domestic ammonia synthesis device consumes an average of about 52 GJ of energy to produce 1 ton of finished ammonia, which is lower than the international advanced level and is not conducive to energy conservation and environmental protection.

[0004] Therefore, there is an urgent need to develop a low-energy consumption ammonia synthesis device to better meet market demand. Utility Model Content

[0005] The purpose of the utility model is to provide a low-energy consumption synthetic ammonia production device to address the deficiencies of the prior art, which can significantly reduce the temperature and pressure requirements of the synthetic ammonia reaction, improve the conversion rate of the reaction, and at the same time reduce the energy consumption of the cooling and separation sections, thereby achieving energy conservation and environmental protection and fully meeting market demand.

[0006] The technical solution of the utility model is:

[0007] A low-energy consumption synthetic ammonia production device comprises a synthetic ammonia reactor, the synthetic ammonia reactor comprises a shell, a purge pipe and a catalyst bed are arranged inside the shell; the purge pipe is a hollow tube, made of a hollow fiber membrane, buried in the catalyst bed, and its two ends are respectively connected to an air inlet and an air outlet on the shell;

[0008] The feed inlet of the synthetic ammonia reactor is connected to the raw gas mixing tank, the discharge port is connected to the inlet of the membrane separator, the gas inlet is connected to the raw nitrogen input pipe through a nitrogen branch, and the gas outlet is connected to the gas-liquid separator after passing through a cooling component;

[0009] The raw gas mixing tank is connected to the raw nitrogen inlet pipe and the raw hydrogen inlet pipe through the nitrogen main line and the hydrogen pipeline respectively;

[0010] The permeate side outlet of the membrane separator is connected to the gas outlet of the synthetic ammonia reactor, and the retentate side outlet thereof is connected to the feed inlet of the synthetic ammonia reactor after passing through a circulating gas mixing tank;

[0011] The liquid ammonia outlet of the gas-liquid separator is connected to the liquid ammonia collector, and the gas outlet of the gas-liquid separator is connected to the circulating gas mixing tank.

[0012] Furthermore, the purge pipe is centrally arranged; a hollow jacket structure is arranged on the side wall of the shell; the jacket structure is tightly fitted with the side wall of the shell, and a cooling water inlet and a cooling water outlet which are connected with the interior thereof are arranged on the outer wall.

[0013] Furthermore, the cooling component includes a first heat exchanger and a water cooler; the shell side inlet of the first heat exchanger is connected to the gas outlet of the synthetic ammonia reactor, and its shell side outlet is connected to the inlet of the gas-liquid separator after passing through the second compressor and the water cooler in sequence, and its tube side inlet is connected to the outlet of the raw gas mixing tank after passing through the first compressor, and its tube side outlet is connected to the gas buffer tank.

[0014] Furthermore, it also includes a second heat exchanger, whose tube-side inlet is connected to the outlet of the gas buffer tank, whose tube-side outlet is connected to the feed port of the synthetic ammonia reactor after passing through a preheater, whose shell-side inlet is connected to the discharge port of the synthetic ammonia reactor, and whose shell-side outlet is connected to the inlet of the membrane separator.

[0015] Furthermore, the outlet of the circulating gas mixing tank is connected to the inlet of the gas buffer tank after passing through the third compressor.

[0016] Furthermore, the preheater is an electric heater.

[0017] Furthermore, the outlet of the third compressor is also connected to a purge gas discharge pipe; and a purge gas regulating valve is provided on the purge gas discharge pipe.

[0018] Furthermore, the raw nitrogen inlet pipe and the raw hydrogen inlet pipe are respectively provided with a nitrogen regulating valve and a hydrogen regulating valve; the nitrogen main line and the hydrogen pipeline are respectively provided with a nitrogen flowmeter and a hydrogen flowmeter; the nitrogen branch line is provided with a purge gas flowmeter and a purge gas pressure gauge, as well as a purge gas pressure reducing valve and a purge gas regulating valve connected in series with each other.

[0019] Furthermore, it also includes an online gas composition analyzer, which is arranged on the pipeline of the gas buffer tank and the second heat exchanger.

[0020] Beneficial effects of the utility model:

[0021] The utility model sets a purge pipe made of a hollow fiber membrane in the synthetic ammonia reactor and couples a membrane separator in the whole device, so that the ammonia in the gas after the reaction is separated by the purge pipe and the membrane separator, and then the gas-liquid separation is performed, so that the subsequent cooling temperature can be significantly raised. Therefore, it not only effectively reduces the temperature and pressure requirements in the reaction, and can significantly improve the conversion rate, but also can greatly reduce energy consumption, which is beneficial to energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of the utility model.

[0023] Figure 2 It is a structural schematic diagram of a synthetic ammonia reactor of the utility model.

[0024] Among them, 1-nitrogen main regulating valve, 2-hydrogen regulating valve, 3-nitrogen flow meter, 4-hydrogen flow meter, 5-nitrogen branch regulating valve, 6-pressure reducing valve, 7-purge gas flow meter, 8-purge gas pressure gauge, 9-raw gas mixing tank, 10-first compressor, 11-first heat exchanger, 12-gas buffer tank, 13-online gas composition analyzer, 14-second heat exchanger, 15-preheater, 16-synthetic ammonia reactor, 17-temperature sensor, 18-membrane separator ; 19-circulating gas mixing tank, 19-hollow fiber membrane assembly, 20-third compressor, 21-relaxation gas regulating valve, 22-second compressor, 23-water cooler, 24-gas-liquid separator; 16-1-shell; 16-2-air inlet; 16-3-feed port; 16-4-catalyst bed, 16-5-purge pipe, 16-6-cooling water inlet, 16-7-air outlet, 16-8-discharge port, 16-9-jacket structure, 16-10-cooling water outlet. DETAILED DESCRIPTION

[0025] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0026] like Figure 1 and 2 shown.

[0027] A low-energy consumption synthetic ammonia production device includes a synthetic ammonia reactor 16, a membrane separator 18, a gas-liquid separator 24, etc.

[0028] The synthetic ammonia reactor 16 includes a shell 16-1, which is provided with a purge pipe 16-5 and a catalyst bed 16-4. The purge pipe 16-5 is a hollow tube made of a hollow fiber membrane, which has a selective permeability to ammonia. In this embodiment, the purge pipe is made of a ZnCl-IMS membrane, whose ammonia permeation rate is 160 GPU, and the selectivity of ammonia / nitrogen and ammonia / hydrogen is 3000 and 1000 respectively, and can withstand a temperature of 300°C. The purge pipe 16-5 is buried in the catalyst bed 16-4 and is centrally arranged, and its two ends are respectively connected to the air inlet 16-2 and the air outlet 16-7 arranged at the two ends of the shell 16-1, so as to facilitate the purge gas to pass through the shell.

[0029] The two ends of the shell 16-1 are respectively provided with a feed port 16-3 and a discharge port 16-8 which are connected with the inside thereof. The feed port 16-3 and the discharge port 16-8 are respectively located at the two ends of the catalyst bed 16-4, so that the raw gas can enter and exit the shell 16-1 from the feed port 16-3 and the discharge port 16-8, and flow through the catalyst bed 16-4 to achieve the reaction. Preferably, the catalyst loaded in the catalyst bed 16-4 is Topsoe KM1 iron-based ammonia synthesis catalyst, and other types of iron-based catalysts, ruthenium-based catalysts, cobalt-based catalysts, etc. can also be used. At the same time, temperature sensors 17 are respectively provided at the upper, middle and lower parts of the catalyst bed 16-4 to obtain the temperature information in the catalyst bed in time.

[0030] A hollow jacket structure 16-9 is provided on the side wall of the shell 16-1. The jacket structure 16-9 is tightly fitted with the side wall of the shell 16-1, and a cooling water inlet 16-6 and a cooling water outlet 16-10 are provided on the outer wall thereof, which are connected to the inside of the jacket structure 16-9. External cooling water can flow from the cooling water inlet 16-6 and the cooling water outlet 16-10 through the inside of the jacket structure 16-9 to exchange heat with the synthetic ammonia reactor, so that the temperature inside the jacket structure meets the reaction requirements.

[0031] The feed port 16-3 of the synthetic ammonia reactor 16 passes through the preheater 15, then passes through the tube side of the second heat exchanger 14, and then is connected to the outlet of the gas buffer tank 12, and its discharge port 16-8 passes through the shell side of the second heat exchanger 14 and is connected to the inlet of the membrane separator 18, so that part of the post-reaction gas exchanges heat with the raw gas from the gas buffer tank 12 to achieve heat recovery. Preferably, the preheater 15 is an electric heater, which can heat the raw gas flowing into the synthetic ammonia reactor to ensure that its temperature meets the reaction requirements.

[0032] The air inlet 16-2 of the synthetic ammonia reactor 16 is connected to the nitrogen main line after passing through the nitrogen branch line, and then connected to the nitrogen input pipe. The air outlet 16-7 passes through the shell side of the first heat exchanger 11, and then passes through the second compressor 22 and the water cooler 23 in sequence, and then is connected to the inlet of the gas-liquid separator 24, so that part of the ammonia in the post-reaction gas permeates into the purge pipe 16-5, and then enters the gas-liquid separator for gas-liquid separation after being cooled together with the purge gas.

[0033] The liquid ammonia outlet of the gas-liquid separator 24 is connected to the liquid ammonia collector, and the gas outlet thereof is connected to the circulating gas mixing tank 19, so that the separated liquid ammonia and gas flow into the liquid ammonia collector and the circulating gas mixing tank respectively.

[0034] The membrane separator 18 can use Nafion organic membrane, whose ammonia permeation rate is 1370 GPU, and the selectivity of ammonia / nitrogen and ammonia / hydrogen are respectively>2000 and>600, so as to separate ammonia by permeation. The permeation side outlet of the membrane separator 18 is connected to the shell side inlet of the first heat exchanger 11, and the permeated ammonia and the purge gas can be cooled and then enter the gas-liquid separator 24 for separation. The retentate side outlet of the membrane separator 18 is connected to the circulating gas mixing tank 19, so that the retentate gas flows into the circulating gas mixing tank, and is mixed with the gas from the gas-liquid separator and reused.

[0035] The outlet of the circulating gas mixing tank 19 is connected to the gas buffer tank 12 after passing through the third compressor 20, so that the gas mixed by the circulating gas mixing tank flows into the gas buffer tank for reuse.

[0036] The tube side outlet of the first heat exchanger 11 is connected to the gas buffer tank 12, and the tube side inlet thereof is connected to the raw gas mixing tank 9 after passing through the first compressor 10. The raw gas mixing tank 9 is also connected to the raw nitrogen input pipe through the nitrogen main line, and is connected to the raw hydrogen input pipe through the hydrogen pipeline, so that the raw nitrogen and raw hydrogen are input into the raw gas mixing tank for mixing, and then pass through the tube side of the first heat exchanger to exchange heat with the purge gas flowing through the shell side of the first heat exchanger at the same time, and then flow into the gas buffer tank.

[0037] The hydrogen pipeline is provided with a hydrogen flowmeter 4, and the raw hydrogen inlet pipe is provided with a hydrogen regulating valve 2, which can regulate and measure the flow of the raw hydrogen. At the same time, the nitrogen main line is provided with a nitrogen flowmeter 3, and the raw nitrogen inlet pipe is provided with a nitrogen regulating valve 1, which can regulate and measure the flow of the raw nitrogen. Furthermore, the nitrogen branch line is provided with a nitrogen branch regulating valve 5, a pressure reducing valve 6, a purge gas flowmeter 7 and a purge gas pressure gauge 8, which can reduce the pressure and regulate the nitrogen flowing through the nitrogen branch, and measure its pressure and flow.

[0038] The outlet of the third compressor 20 is also connected to a purge gas discharge pipe, and a purge gas regulating valve 21 is provided on the purge gas discharge pipe, which can control the gas from the circulating gas mixing tank to be properly discharged so as to discharge part of the inert gas in the gas.

[0039] Furthermore, it also includes an online gas composition analyzer 13. The online gas composition analyzer 13 is arranged on the pipeline of the gas buffer tank 12 and the second heat exchanger 14, and can perform online detection and analysis on the components of the mixed gas flowing out of the gas buffer tank.

[0040] The working process of the utility model is:

[0041] The hydrogen production equipment produces 300 kmol / h of hydrogen, which flows into the raw gas mixing tank 9 through the hydrogen regulating valve 1; the nitrogen production equipment produces 140 kmol / h of nitrogen, which is divided into two routes, of which 100 kmol / h of nitrogen flows into the raw gas mixing tank 9 through the nitrogen main route regulating valve 2, and the remaining 40 kmol / h flows into the purge pipe of the synthetic ammonia reactor as purge gas after the pressure is reduced to 1 bar through the nitrogen branch regulating valve 5 and the pressure reducing valve 6. The purge gas flowmeter 7 and the purge gas pressure gauge 8 installed on the nitrogen branch will transmit the detected flow and pressure values ​​to the central control system, and then automatically control the opening of the nitrogen branch regulating valve 5 and the pressure reducing valve 6 through the control loop to keep the flow and pressure of the purge nitrogen stable.

[0042] After the hydrogen and nitrogen in the raw gas mixing tank 9 are fully mixed, they are pressurized to about 31 bar by the first compressor 10, flow through the tube side of the first heat exchanger 11, flow to the gas buffer tank 12 after heat exchange, mix with the circulating gas, and then flow through the tube side of the second heat exchanger 14 for secondary heat exchange. During this period, the hydrogen-nitrogen ratio in the gas flowing out of the gas buffer tank can be detected and analyzed by the online gas composition analyzer 13, and the analysis signal is transmitted to the central control system, and the opening of the nitrogen main regulating valve 1 and the hydrogen regulating valve 2 is controlled accordingly, so that the hydrogen-nitrogen ratio in the gas flowing out of the gas buffer tank 12 is always maintained at 3:1.

[0043] The gas flowing out of the gas buffer tank 12 is first heated by the preheater to a temperature of about 300°C, and then enters the feed port of the synthetic ammonia reactor and flows into the synthetic ammonia reactor, and flows through the catalyst bed. Ammonia is generated after the reaction, and about 82 kmol / h of ammonia in the gas after the reaction penetrates into the purge pipe, is carried away by the 40 kmol / h purge gas from the nitrogen branch, and flows out from the gas outlet of the synthetic ammonia reactor. The gas volume at the outlet of the catalyst bed is about 207 kmol / h, and the conversion rate (in terms of nitrogen) can reach 55.3% at this time. At the same time, by setting three temperature sensors in the catalyst bed, the temperature distribution in the reactor can be monitored. At the same time, the heat generated in the reaction is taken away by the cooling water circulating in the jacket, so that the temperature of the entire reaction process is maintained within 300±15°C.

[0044] The post-reaction gas flowing out from the discharge port of the synthetic ammonia reactor mainly consists of: 28.6 kmol / h ammonia, 44.9 kmol / h nitrogen, 134.0 kmol / h hydrogen, flows through the shell side of the second heat exchanger 14, and exchanges heat with the raw gas flowing through at the same time and is cooled to about 158°C, and then flows into the membrane separator 24.

[0045] The membrane separator 24 is loaded with 2000 m 2 The ammonia selective permeable membrane (Nafion) is used to make about 20.8 kmol / h of ammonia gas with a purity of 97.3% in the inflowing post-reaction gas flow out from the permeation side outlet of the membrane separator. Subsequently, the outflowing ammonia gas and the purge gas from the synthetic ammonia reactor are combined and flow together to the shell side of the first heat exchanger 11. At the same time, another 186.6 kmol / h of retentate gas flows out through the retentate side outlet of the membrane separator 24 and flows into the circulating gas mixing tank 19.

[0046] The gas flowing through the shell side of the first heat exchanger is first pressurized to 31 bar by the first compressor 22, then cooled to about -10°C by the water cooler 23, and then flows into the gas-liquid separator 24 for separation, so that about 97.2 kmol / h of liquid ammonia with a purity of 99.85% flows out from the bottom as the final product and flows into the liquid ammonia collector. At the same time, about 45.7 kmol / h of separated gas flows out from the top of the gas-liquid separator and flows into the circulating gas mixing tank 29 to mix with the retentate gas from the membrane separator.

[0047] The gas in the circulating gas mixing tank 19 flows out after being fully mixed, and flows into the gas buffer tank 12 after being slightly pressurized to 30.8 bar by the third compressor 20, and enters the cycle again after being mixed with the raw gas. At the same time, by controlling the relaxation gas regulating valve 21, the mixed gas from the circulating gas mixing tank is appropriately discharged to remove part of the inert gas in the mixed gas.

[0048] According to calculation, it takes about 2000m 2 After the Nafion membrane separator separates about 20.2 kmol / h of ammonia from the post-reaction gas in advance, the power of the second compressor is about 822 kW and the heat transfer power is 1540 kW. At this time, the ammonia content in the gas is as high as 83.2%. Therefore, after being cooled to about 25°C by the water cooler, the ammonia in the gas can be fully condensed and liquid ammonia can be separated.

[0049] If the traditional process is used to produce liquid ammonia of the same output and purity, the cryogenic separation temperature needs to be lowered to about -15°C. Therefore, relying solely on a water cooler cannot meet the demand, and an ammonia cooler is usually required, which results in the second compressor power reaching 667 kW and the heat transfer power being 1959 kW.

[0050] In summary, the utility model greatly improves the separation temperature of liquid ammonia by adopting a synthetic ammonia reactor with separation function and a coupled membrane separator. Furthermore, the cooling effect can be achieved through circulating water, and there is no need to set up an additional liquid ammonia cooling system. Therefore, it not only effectively reduces the requirements for temperature and pressure in the reaction, but also significantly improves the conversion rate. Moreover, it can also greatly reduce energy consumption, which is beneficial to energy conservation and environmental protection, and can also reduce construction costs and floor space, creating favorable conditions for improving economic benefits.

[0051] The parts not involved in the present invention are the same as the prior art or can be implemented by using the prior art.

Claims

1. A low-energy consumption synthetic ammonia production device, comprising a synthetic ammonia reactor, characterized in that: The synthetic ammonia reactor comprises a shell, in which a purge pipe and a catalyst bed are arranged; the purge pipe is a hollow tube, made of a hollow fiber membrane, buried in the catalyst bed, and its two ends are respectively connected to the air inlet and the air outlet on the shell; The feed inlet of the synthetic ammonia reactor is connected to the raw gas mixing tank, the discharge port is connected to the inlet of the membrane separator, the gas inlet is connected to the raw nitrogen input pipe through a nitrogen branch, and the gas outlet is connected to the gas-liquid separator after passing through a cooling component; The raw gas mixing tank is connected to the raw nitrogen inlet pipe and the raw hydrogen inlet pipe through the nitrogen main line and the hydrogen pipeline respectively; The permeate side outlet of the membrane separator is connected to the gas outlet of the synthetic ammonia reactor, and the retentate side outlet thereof is connected to the feed inlet of the synthetic ammonia reactor after passing through a circulating gas mixing tank; The liquid ammonia outlet of the gas-liquid separator is connected to the liquid ammonia collector, and the gas outlet of the gas-liquid separator is connected to the circulating gas mixing tank.

2. The low-energy consumption synthetic ammonia production device according to claim 1 is characterized in that: The purge pipe is centrally arranged; a hollow jacket structure is arranged on the side wall of the shell; the jacket structure is tightly fitted with the side wall of the shell, and a cooling water inlet and a cooling water outlet which are connected with the inside of the jacket structure are arranged on the outer wall.

3. The low-energy consumption synthetic ammonia production device according to claim 1 is characterized in that: The cooling component includes a first heat exchanger and a water cooler; the shell side inlet of the first heat exchanger is connected to the gas outlet of the synthetic ammonia reactor, the shell side outlet is connected to the inlet of the gas-liquid separator after passing through the second compressor and the water cooler in sequence, the tube side inlet is connected to the outlet of the raw gas mixing tank after passing through the first compressor, and the tube side outlet is connected to the gas buffer tank.

4. The low-energy consumption synthetic ammonia production device according to claim 3 is characterized in that: It also includes a second heat exchanger, whose tube-side inlet is connected to the outlet of the gas buffer tank, whose tube-side outlet is connected to the feed port of the synthetic ammonia reactor after passing through a preheater, whose shell-side inlet is connected to the discharge port of the synthetic ammonia reactor, and whose shell-side outlet is connected to the inlet of the membrane separator.

5. The low-energy consumption synthetic ammonia production device according to claim 3 is characterized in that: The outlet of the circulating gas mixing tank is connected to the inlet of the gas buffer tank after passing through the third compressor.

6. The low-energy consumption synthetic ammonia production device according to claim 4 is characterized in that: The preheater is an electric heater.

7. The low-energy consumption synthetic ammonia production device according to claim 5 is characterized in that: The outlet of the third compressor is also connected to a purge gas discharge pipe; a purge gas regulating valve is provided on the purge gas discharge pipe.

8. The low-energy consumption synthetic ammonia production device according to claim 1 is characterized in that: The raw nitrogen inlet pipe and the raw hydrogen inlet pipe are respectively provided with a nitrogen regulating valve and a hydrogen regulating valve; the nitrogen main line and the hydrogen pipeline are respectively provided with a nitrogen flowmeter and a hydrogen flowmeter; the nitrogen branch line is provided with a purge gas flowmeter and a purge gas pressure gauge, as well as a purge gas pressure reducing valve and a purge gas regulating valve connected in series with each other.

9. The low-energy consumption synthetic ammonia production device according to claim 4 is characterized in that: It also includes an online gas composition analyzer, which is arranged on the pipeline of the gas buffer tank and the second heat exchanger.

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