Purge gas energy utilization device in ammonia synthesis system

Abstract

The utility model particularly relates to a purge gas energy utilization device in a synthetic ammonia system. Comprising a purge gas pipeline connected with an ammonia synthesis system, the purge gas pipeline is connected with a gas inlet of a residual pressure generator set through a control valve assembly, the output end of the residual pressure generator set is connected with a battery energy storage system, and the battery energy storage system is electrically connected with an ammonia ice machine; an inlet of the ammonia ice machine is connected with a gas phase outlet in the top of the normal-pressure ammonia tank, and an outlet of the ammonia ice machine is connected with a liquid ammonia circulating inlet in the lower part of the normal-pressure ammonia tank; the pressure of the purge gas is recycled by arranging the residual pressure generator set, and the generated electric energy is stored through the battery energy storage system, so that the energy of the purge gas is coupled with the ammonia ice machine, and the characteristic of saving the energy consumption of the ammonia synthesis system is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of purge gas recovery, in particular to a purge gas energy utilization device in a synthetic ammonia system. Background Art

[0002] The conversion rate of the synthetic ammonia device in the traditional technology is not high, so it is impossible to convert all hydrogen and nitrogen into ammonia. Based on the above reasons, in order to achieve effective utilization of raw materials, hydrogen and nitrogen need to be recycled. In the circulation process of the circulating gas, the amount of inert gas accumulates continuously, which will cause the pressure of the synthesis tower to rise and affect the synthesis reaction, thereby reducing the net value of ammonia. Therefore, in the continuous production process, the venting operation should be performed frequently to reduce the inert gas content in the system and promote the forward progress of the synthesis reaction. The purge gas generated in the above venting operation is generally discharged in the form of intermittent discharge, and the gas volume cannot be determined. Based on the above reasons, the energy of the purge gas is generally not utilized, but is directly sent to the flare for combustion, which causes energy waste. Furthermore, the liquid ammonia produced in the synthetic ammonia system is generally stored in a normal pressure ammonia tank. The liquid ammonia in the normal pressure ammonia tank gradually gasifies, causing the pressure in the normal pressure ammonia tank to increase. In order to avoid the loss of product gas, it is necessary to use electricity to drive the ammonia ice machine to convert the ammonia gas into liquid ammonia and reflow it into the normal pressure ammonia tank. This process causes power loss due to the need to drive the ammonia ice machine. Utility Model Content

[0003] The utility model aims to provide a purge gas energy utilization device in a synthetic ammonia system to overcome the defects in the prior art.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] A purge gas energy utilization device in a synthetic ammonia system comprises a purge gas pipeline connected to the synthetic ammonia system, wherein the purge gas pipeline is connected to a gas inlet of a residual pressure generator set through a control valve assembly, an output end of the residual pressure generator set is connected to a battery energy storage system, and the battery energy storage system is electrically connected to an ammonia ice machine; an inlet of the ammonia ice machine is connected to a gas phase outlet at the top of a normal pressure ammonia tank, and an outlet of the ammonia ice machine is connected to a liquid ammonia circulation inlet at the bottom of the normal pressure ammonia tank.

[0006] The beneficial effects of the utility model are as follows: the purge gas discharged in the synthetic ammonia system described in the utility model is in the form of intermittent discharge, and the gas volume cannot be determined; and the timing of converting the gaseous ammonia in the atmospheric pressure ammonia tank into liquid ammonia cannot be determined either; the utility model recovers and reuses the pressure of the purge gas by arranging a residual pressure generator set, and the generated electric energy is stored by a battery energy storage system, so as to realize the coupling of the energy of the purge gas with the ammonia ice machine, thereby achieving the characteristic of saving the energy consumption of the synthetic ammonia system.

[0007] Preferably, the gas outlet of the residual pressure generator set is connected to the first channel of the circulating water heat exchanger, and the outlet of the first channel of the circulating water heat exchanger is connected to the mixed combustion gas inlet of the boiler.

[0008] Preferably, the inlet of the second channel of the circulating water heat exchanger is connected to the process circulating water outlet pipeline in the synthetic ammonia system, and the outlet of the second channel of the circulating water heat exchanger is connected to the process circulating water inlet pipeline in the synthetic ammonia system.

[0009] Preferably, a first tee is provided on the process circulating water outlet pipe in the synthetic ammonia system, and the third end of the first tee is connected to the inlet of the cooling tower; a second tee is provided on the process circulating water inlet pipe in the synthetic ammonia system, and the third end of the second tee is connected to the outlet of the cooling tower.

[0010] Preferably, a first valve is provided between the first tee and the inlet of the second channel of the circulating water heat exchanger, and a second valve is provided between the third end of the first tee and the inlet of the cooling tower; a third valve is provided between the second tee and the outlet of the second channel of the circulating water heat exchanger, and a fourth valve is provided between the third end of the second tee and the outlet of the cooling tower.

[0011] Preferably, the control valve assembly includes a quick-closing valve and a quick-closing regulating valve.

[0012] A purge gas energy utilization device in a synthetic ammonia system is manufactured according to the above scheme. The utility model overcomes the characteristic that the purge gas energy in the synthetic ammonia system in the traditional technology cannot be recovered. Firstly, the energy of the pressure in the purge gas is recovered to generate electricity, and the electricity is stored by using a battery energy storage system, so as to achieve the characteristic of reducing energy consumption when the ammonia ice machine needs to be started. Secondly, the low temperature of the purge gas after power generation is utilized to recover the cold energy, so that it can be heat-exchanged with the process circulating water in the synthetic ammonia system, so as to achieve the characteristic of reducing the energy consumption of the cooling tower; finally, the characteristic of the purge gas after heating is utilized to make it used as boiler blending gas; in the above process, the pressure and cold energy of the purge gas and the purge gas itself can be fully utilized, so as to achieve the characteristic of reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of the utility model.

[0014] In the figure: 1. Synthetic ammonia system; 2. Relaxation gas pipeline; 3. Quick-closing valve; 4. Residual pressure generator set; 5. Battery energy storage system; 6. Normal pressure ammonia tank; 7. Ammonia ice machine; 8. Quick-closing regulating valve; 9. Circulating water heat exchanger; 10. Boiler; 11. Blending gas inlet; 12. Process circulating water outlet pipeline; 13. Process circulating water inlet pipeline; 14. First tee; 15. Second tee; 16. Cooling tower; 17. First valve; 18. Second valve; 19. Third valve; 20. Fourth valve. DETAILED DESCRIPTION

[0015] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0016] Reference Figure 1 As shown, a purge gas energy utilization device in a synthetic ammonia system includes a purge gas pipeline 2 connected to the synthetic ammonia system 1, the purge gas pipeline 2 is connected to the gas inlet of the residual pressure generator set 4 through a control valve assembly, the output end of the residual pressure generator set 4 is connected to the battery energy storage system 5, and the battery energy storage system 5 is electrically connected to the ammonia ice machine 7; the inlet of the ammonia ice machine 7 is connected to the gas phase outlet at the top of the atmospheric pressure ammonia tank 6, and the outlet of the ammonia ice machine 7 is connected to the liquid ammonia circulation inlet at the bottom of the atmospheric pressure ammonia tank 6. The utility model controls the flow rate of the relaxation gas in the relaxation gas pipeline 2 by setting a control valve assembly, so that the relaxation gas in the relaxation gas pipeline 2 enters the residual pressure generator set 4 to generate electricity using the pressure of the relaxation gas, and the electricity generated by the residual pressure generator set 4 enters the battery energy storage system 5 for storage. When it is necessary to start the ammonia ice machine 7 to convert the gaseous ammonia in the atmospheric pressure ammonia tank 6 into liquid ammonia, the electric energy stored in the battery energy storage system 5 is supplied to the ammonia ice machine 7, thereby realizing the coupling of intermittent discharge of the relaxation gas and intermittent start-up of the ammonia ice machine 7; the residual pressure generator set 4 described in the utility model includes a turbine expander, a high-speed gear reducer, a flexible coupling, a lubrication and cooling system, etc., and generates electricity using a turbine by converting pressure difference energy into mechanical energy; the battery energy storage system 5 described in the utility model is preferably a lithium battery pack; the ammonia ice machine 7 is preferably a screw ice machine.

[0017] Furthermore, the gas outlet of the residual pressure generator set 4 is connected to the first channel of the circulating water heat exchanger 9, and the outlet of the first channel of the circulating water heat exchanger 9 is connected to the mixed combustion gas inlet 11 of the boiler 10. In the utility model, not only the residual pressure generator set 4 is used to recycle the pressure of the relaxation gas, but also the circulating water heat exchanger 9 is used to recycle the coldness of the relaxation gas, and finally the heated relaxation gas is used as mixed combustion gas through the boiler 10, thereby achieving full utilization of the relaxation gas.

[0018] Further, the inlet of the second channel of the circulating water heat exchanger 9 is connected to the process circulating water outlet pipe 12 in the synthetic ammonia system 1, and the outlet of the second channel of the circulating water heat exchanger 9 is connected to the process circulating water inlet pipe 13 in the synthetic ammonia system 1. The heat exchange medium in the circulating water heat exchanger 9 described in the utility model is preferably the process circulating water in the synthetic ammonia system 1, which is used to cool the process circulating water in the synthetic ammonia system 1 to achieve the characteristic of reducing energy consumption in the cooling tower. The circulating water heat exchanger 9 described in the utility model is preferably a shell and tube heat exchanger, and further, the first channel of the circulating water heat exchanger 9 is preferably the shell side of the shell and tube heat exchanger, and the second channel of the circulating water heat exchanger 9 is preferably the tube side of the shell and tube heat exchanger.

[0019] Furthermore, a first tee 14 is provided on the process circulating water outlet pipe 12 in the synthetic ammonia system 1, and a third end of the first tee 14 is connected to the inlet of a cooling tower 16; a second tee 15 is provided on the process circulating water inlet pipe 13 in the synthetic ammonia system 1, and a third end of the second tee 15 is connected to the outlet of the cooling tower 16. A first valve 17 is provided between the first tee 14 and the inlet of the second channel of the circulating water heat exchanger 9, and a second valve 18 is provided between the third end of the first tee 14 and the inlet of the cooling tower 16; a third valve 19 is provided between the second tee 15 and the outlet of the second channel of the circulating water heat exchanger 9, and a fourth valve 20 is provided between the third end of the second tee 15 and the outlet of the cooling tower 16. Since the relaxation gas described in the utility model is in the form of intermittent discharge, the purpose of convenient operation can be achieved by setting the first tee 14 and the second tee 15. When the relaxation gas is discharged, part of the process circulating water can pass through the circulating water heat exchanger 9, and part of the process circulating water can pass through the cooling tower 16; when the relaxation gas is partially discharged, all of the process circulating water can pass through the cooling tower 16; further, by setting the above-mentioned corresponding valves, the process circulating water can be adjusted, and the temperature of the relaxation gas passing through the circulating water heat exchanger 9 is preferably guaranteed by the above-mentioned adjustment; further, when the process circulating water is discharged from the outlet of the second channel of the circulating water heat exchanger 9, its temperature can meet the recycling of the circulating process water.

[0020] Furthermore, the control valve assembly includes a quick-closing valve 3 and a quick-closing regulating valve 8. The quick-closing valve 3 described in the utility model is mainly used to quickly cut off the relaxation gas when a fault occurs in the residual pressure generator set 4 or the battery energy storage system 5; the quick-closing regulating valve 8 described in the utility model is arranged at the rear of the quick-closing valve 3, and is mainly used to adjust the flow size when starting and shutting down.

[0021] The working principle of the utility model is as follows: the ammonia synthesis tower in the synthetic ammonia system 1 is connected to the purge gas pipeline 2. When the purge gas in the purge gas pipeline 2 is discharged, the purge gas enters the residual pressure generator set 4 through the control valve assembly to generate electricity, and the electricity generated by the power generation enters the battery energy storage system 5 for temporary storage; the temperature of the purge gas after passing through the generator set 4 is reduced to about -15°C, and the purge gas is heat exchanged through the first channel of the circulating water heat exchanger 9. The temperature of the purge gas after heat exchange is 5°C, and the purge gas after heat exchange enters the boiler 10 through the mixed combustion gas inlet 11 for mixed combustion; in the above process, the first valve 17 is adjusted to control the flow rate of the process circulating water to enter the second channel of the circulating water heat exchanger 9 for heat exchange, and the time for the process circulating water to enter the second channel of the circulating water heat exchanger 9 is controlled by the third valve 19 to ensure that the process circulating water and the purge gas are fully heat exchanged; when no purge gas passes through, the process circulating water can enter the cooling tower 16 to ensure the stable operation of the process circulating water in the synthetic ammonia system 1. Furthermore, when the amount of gaseous ammonia inside the atmospheric pressure ammonia tank 6 is large, causing the pressure in the atmospheric pressure ammonia tank 6 to be too high, the battery energy storage system 5 supplies power to the ammonia ice machine 7, so that the ammonia ice machine 7 starts to convert the gaseous ammonia into liquid ammonia, and the liquid ammonia is sent into the atmospheric pressure ammonia tank 6 to ensure the safety of the atmospheric pressure ammonia tank 6; in the above process, the pressure, coldness and the relaxation gas itself can be fully utilized, which has the characteristic of saving energy consumption compared with traditional technologies.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A purge gas energy utilization device in a synthetic ammonia system, comprising a purge gas pipeline (2) connected to the synthetic ammonia system (1), characterized in that: The relaxation gas pipeline (2) is connected to the gas inlet of the residual pressure generator set (4) through a control valve assembly, the output end of the residual pressure generator set (4) is connected to the battery energy storage system (5), and the battery energy storage system (5) is electrically connected to the ammonia ice machine (7); The inlet of the ammonia ice machine (7) is connected to the gas phase outlet at the top of the atmospheric pressure ammonia tank (6), and the outlet of the ammonia ice machine (7) is connected to the liquid ammonia circulation inlet at the bottom of the atmospheric pressure ammonia tank (6).

2. The purge gas energy utilization device in a synthetic ammonia system according to claim 1, characterized in that: The gas outlet of the residual pressure generator set (4) is connected to the first channel of the circulating water heat exchanger (9), and the outlet of the first channel of the circulating water heat exchanger (9) is connected to the mixed combustion gas inlet (11) of the boiler (10).

3. The purge gas energy utilization device in a synthetic ammonia system according to claim 2, characterized in that: The inlet of the second channel of the circulating water heat exchanger (9) is connected to the process circulating water outlet pipe (12) in the synthetic ammonia system (1), and the outlet of the second channel of the circulating water heat exchanger (9) is connected to the process circulating water inlet pipe (13) in the synthetic ammonia system (1).

4. The purge gas energy utilization device in a synthetic ammonia system according to claim 3, characterized in that: A first tee (14) is provided on the process circulating water outlet pipe (12) in the synthetic ammonia system (1), and a third end of the first tee (14) is connected to the inlet of a cooling tower (16); A second tee (15) is provided on the process circulating water inlet pipeline (13) in the synthetic ammonia system (1), and the third end of the second tee (15) is connected to the outlet of the cooling tower (16).

5. The purge gas energy utilization device in a synthetic ammonia system according to claim 4, characterized in that: A first valve (17) is provided between the first tee (14) and the inlet of the second channel of the circulating water heat exchanger (9), and a second valve (18) is provided between the third end of the first tee (14) and the inlet of the cooling tower (16); a third valve (19) is provided between the second tee (15) and the outlet of the second channel of the circulating water heat exchanger (9), and a fourth valve (20) is provided between the third end of the second tee (15) and the outlet of the cooling tower (16).

6. The purge gas energy utilization device in a synthetic ammonia system according to claim 1, characterized in that: The control valve assembly comprises a quick-closing valve (3) and a quick-closing regulating valve (8).

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