An ammonia refining apparatus and method

Abstract

The application discloses an ammonia refining device and method, and belongs to the technical field of sewage stripping. The ammonia refining device comprises a refining tower, a crystallization tank, an adsorption tank, a cyclone separator, a variable frequency refrigerator, a low-pressure liquid ammonia tank, a low-pressure liquid ammonia pump, a high-pressure liquid ammonia tank and a first heat exchanger, a third heat exchanger and a fourth heat exchanger which are connected in sequence. After carbon powder and moisture are removed through the cyclone separator, gaseous ammonia from the adsorption tank enters the variable frequency refrigerator, is directly changed into liquid ammonia after heat exchange with refrigerant medium of the variable frequency refrigerator, is temporarily stored in the low-pressure liquid ammonia tank, and is pumped into the first heat exchanger, the second heat exchanger, the third heat exchanger and the fourth heat exchanger in sequence through the low-pressure liquid ammonia pump after heat exchange, so that the temperature and the pressure are increased, and the liquid ammonia enters the high-pressure liquid ammonia tank for safe storage. The process flow is short, energy consumption is low, the system operation is safe and reliable, and the recovered liquid ammonia is high in purity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ammonia refining, in particular to an ammonia refining device and method. BACKGROUND

[0002] With the improvement of crude oil processing depth, especially the increase of high-sulfur crude oil processing ratio, the amount of sewage produced by oil refining device and the content of pollutants in the sewage are increasing, in order to meet the requirements of environmental protection and vehicle pollutant emission standards, the oil refinery generally matches the acid water stripping device and ammonia refining device to treat the acid water, the crude ammonia gas extracted from the side line of the acid water stripping device reaches 97% after three-part condensation and enters the ammonia refining device, and the sulfur is removed in the ammonia refining device to obtain industrial ammonia.

[0003] The ammonia refining device mainly comprises a refining tower, a crystallization tank and an adsorption tank connected in sequence, the crude ammonia from the stripping device first enters the refining tower to reduce the content of hydrogen sulfide and water, and then enters the crystallization tank and the adsorption tank in sequence for further removal of sulfides for refining; the refined ammonia gas from the adsorption tank is liquefied mainly by the following two processes, in the early stage, ammonia gas compressor is used for liquefaction, the ammonia gas compressor is damaged frequently, the ammonia refining system runs in poor condition and accidents often occur; in the later stage, ammonia rectification is used to prepare liquid ammonia process, which is safer than ammonia compression process and the system runs well, but the ammonia rectification process for preparing liquid ammonia still has the following problems:

[0004] 1. High energy consumption, and the obtained liquid ammonia also has high water content;

[0005] 2. The refining tower and the crystallization tank both need to use recovered liquid ammonia to spray and cool the inlet gas ammonia to achieve the process temperature required for washing and crystallization, which reduces the ammonia recovery rate;

[0006] 3. The refining tower and the crystallization tank use liquid ammonia gasification for cooling, the washing temperature control is unstable, and the desulfurization effect is poor. SUMMARY

[0007] To solve the above problems, the present application provides an ammonia refining device and method.

[0008] The technical scheme adopted by the present application is:

[0009] An ammonia refining device, comprising a refining tower, a crystallization tank, an adsorption tank, a cyclone separator, a variable frequency chiller, a low-pressure liquid ammonia tank, a low-pressure liquid ammonia pump, a high-pressure liquid ammonia tank, a first heat exchanger, a third heat exchanger and a fourth heat exchanger connected in sequence,

[0010] The first heat exchanger is arranged at the bottom of the crystallization tank and comprises heat exchange pipes A, which are used to cool the concentrated ammonia water at the bottom of the crystallization tank;

[0011] The third heat exchanger is arranged at the bottom of the refining tower and comprises heat exchange pipes C for cooling concentrated ammonia water at the bottom of the refining tower.

[0012] The inlet of the cyclone separator is communicated with the outlet at the top of the adsorption tank, the outlet at the top of the cyclone separator is communicated with the inlet of the variable frequency refrigerator, the outlet of the variable frequency refrigerator is communicated with the inlet of the low-pressure liquid ammonia tank, the inlet of the low-pressure liquid ammonia pump is communicated with the low-pressure liquid ammonia tank, the outlet of the low-pressure liquid ammonia pump is communicated with the inlet of the heat exchange pipe A, the outlet of the heat exchange pipe A is communicated with the inlet of the heat exchange pipe C, the outlet of the heat exchange pipe C is communicated with the cold medium inlet of the fourth heat exchanger, and the cold medium outlet of the fourth heat exchanger is communicated with the inlet of the high-pressure liquid ammonia tank.

[0013] According to the technical scheme, the gaseous ammonia from the adsorption tank is removed of carbon powder and water through the cyclone separator, enters the variable frequency refrigerator, exchanges heat with the refrigerant medium of the variable frequency refrigerator, is changed into liquid ammonia, and is stored in the low-pressure liquid ammonia tank; the liquid ammonia in the low-pressure liquid ammonia tank is pumped into the first heat exchanger, the third heat exchanger and the fourth heat exchanger in sequence through the low-pressure liquid ammonia pump, and the temperature and pressure of the liquid ammonia are increased after heat exchange, and the liquid ammonia is stored in the high-pressure liquid ammonia tank.

[0014] The ammonia refining process does not use a rectifying tower, the process is simple, and the energy consumption is greatly reduced; the refrigerant is closed-loop circulated in the refrigerator and does not directly contact with the ammonia gas, so that the compressor failure caused by liquid carried by the process medium (ammonia gas) is avoided, the safe operation of the system is ensured, the ammonia gas does not directly contact with the compressor, the recovered liquid ammonia does not contain oil, and the purity is improved. The use of the cyclone separator can separate the carbon powder and water in the ammonia gas, and the quality of the recovered liquid ammonia is improved.

[0015] Under the condition that the pressure is 1.3 MPa and the temperature is about 37℃, the liquid ammonia can be stably stored in a liquid state, the low-temperature liquid ammonia is cooled to about-16℃ through the variable frequency refrigerator, the temperature difference is 53℃ from-16℃ to 37℃, and the cold energy of the liquid ammonia can be fully utilized to cool the crystallization tank and the refining tower through three-stage heat exchange, the remaining cold energy is exchanged with the purified water, the cold energy is reused, the energy consumption of the ammonia production process is further reduced, the ammonia loss caused by the cooling of the liquid ammonia is reduced, and the ammonia recovery rate is improved; and the outlet ammonia gas is cooled through indirect heat exchange, the temperature of the outlet ammonia gas is easy to control, the temperature fluctuation range is small, and the desulfurization effect is improved.

[0016] Further, the second heat exchanger is arranged at the bottom of the refining tower and above the third heat exchanger, comprises a heat exchanger shell, the bottom of the heat exchanger shell is provided with an ammonia gas inlet, the top of the heat exchanger shell is provided with an ammonia gas outlet, and the middle of the heat exchanger shell is provided with heat exchange pipes B for cooling the ammonia gas entering the refining tower, the inlet of the heat exchange pipes B is communicated with the outlet of the heat exchange pipes C, and the outlet of the heat exchange pipes B is communicated with the cold medium inlet of the fourth heat exchanger.

[0017] The second heat exchanger is used to cool the ammonia gas entering the refining tower, and the third heat exchanger is used to cool the concentrated ammonia water at the bottom of the refining tower, which is conducive to better adjustment of the outlet temperature of the refining tower and improvement of the desulfurization effect; and the temperature of the liquid ammonia entering the second heat exchanger can be appropriately increased, and the crystallization on the surface of the heat exchanger is reduced.

[0018] Further, the heat exchange pipe B is a finned heat exchange pipe. The heat exchange efficiency of the heat exchanger is improved.

[0019] Further, the bottom of the heat exchanger shell is provided with a gas distributor, and the gas distributor is located between the ammonia gas inlet and the heat exchange pipe B. The uniformity of the inlet ammonia gas distribution is improved, and the desulfurization effect of the refining tower is improved.

[0020] Further, the inlet and outlet of the heat exchange pipe A are communicated through a connecting pipeline A, and the connecting pipeline A is provided with a temperature regulating valve A; the inlet of the heat exchange pipe C and the outlet of the heat exchange pipe B are communicated through a connecting pipeline B, and the connecting pipeline B is provided with a temperature regulating valve B.

[0021] By using the above technical scheme, the flow of ammonia gas entering the refining tower and the crystallization tank can be adjusted through the temperature regulating valve, so as to control the temperature of the outlet ammonia gas of the refining tower and the crystallization tank, and ensure the desulfurization effect.

[0022] Further, the refining tower circulation pipeline is provided with a branch, the upper portion of the second heat exchanger is provided with a circulating ammonia water spraying pipe, the circulating ammonia water spraying pipe is connected with the branch of the refining tower circulation pipeline, a flow regulating valve is arranged on the branch, a liquid discharge pipe is arranged at the bottom of the refining tower, and the liquid discharge pipe is connected with a raw material sewage tank.

[0023] By using the above technical scheme, the concentrated ammonia water with a flow not greater than 10% of the circulation amount of the refining tower is controlled to enter the second heat exchanger and spray the finned heat exchange pipe through the liquid level regulating valve, so that the ammonium hydrosulfide crystallized on the finned heat exchange pipe due to low temperature can be dissolved, and the heat exchange efficiency of the heat exchanger is ensured to be high. After the moisture in the ammonia gas is condensed, the liquid level at the bottom of the tower gradually rises, and the hydrogen sulfide reaction product washed down is sent out together with the concentrated ammonia water at the bottom of the tower to the raw material sewage tank through the liquid discharge pipe.

[0024] Further, the high-pressure liquid ammonia tank is provided with a first liquid ammonia outlet and a second liquid ammonia outlet, the first liquid ammonia outlet is communicated with a liquid ammonia delivery pump, the second liquid ammonia outlet is connected with a refining tower ammonia supplement inlet and a crystallization tank ammonia supplement inlet through a first ammonia supplement pipeline and a second ammonia supplement pipeline respectively, the refining tower ammonia supplement inlet is located above the second heat exchanger, and the crystallization tank ammonia supplement inlet is communicated with a crystallization tank ammonia gas inlet pipeline.

[0025] By using the above technical scheme, if the temperature of the outlet ammonia gas at the top of the refining tower and the crystallization tank cannot be reduced to the process requirement after heat exchange is completed, liquid ammonia can be supplemented through the ammonia supplement pipeline, and the liquid ammonia is gasified to reduce the temperature, so as to further ensure the desulfurization effect of the refining tower and the crystallization tank.

[0026] Further, the first ammonia supplement pipeline and the second ammonia supplement pipeline are respectively provided with an ammonia supplement regulating valve A and an ammonia supplement regulating valve B.

[0027] By using the above technical scheme, the flow of the added liquid ammonia can be controlled by the ammonia supplement regulating valve, so that the process temperature of the refining tower and the crystallization tank can be better controlled.

[0028] Further, the top of the low-pressure liquid ammonia tank and the high-pressure liquid ammonia tank is provided with a non-condensable gas discharge port, the non-condensable gas discharge port is connected with a residue discharge pipeline at the bottom of the cyclone separator through a pipeline, the residue discharge pipeline is connected with a blowdown tank, and the blowdown tank is connected with a raw material sewage tank through a blowdown pump.

[0029] By using the above technical scheme, the safety of liquid ammonia storage is ensured, waste gas emission is reduced, and the environment is protected.

[0030] A method for refining ammonia by using any one of the ammonia refining devices, comprising the following steps:

[0031] (1) The gaseous ammonia with a temperature of 0±3℃ from the adsorption tank is cooled to -19℃ to -13℃ by a frequency conversion freezer after removing carbon powder and water through a cyclone separator, and is temporarily stored in a low-pressure liquid ammonia tank in the form of liquid ammonia;

[0032] (2) The liquid ammonia with a temperature of -19℃ to -13℃ is first pumped from the low-pressure liquid ammonia tank into a first heat exchanger in the crystallization tank, and exchanges heat with concentrated ammonia water at the bottom of the crystallization tank, after the heat exchange is completed, the outlet gaseous ammonia of the crystallization tank is reduced to -5±3℃, and the liquid ammonia is warmed to -14±3℃;

[0033] (3) The liquid ammonia with a temperature of -14±3℃ enters a third heat exchanger of the refining tower, exchanges heat with concentrated ammonia water at the bottom of the refining tower, after the heat exchange is completed, enters a second heat exchanger and exchanges heat with gaseous ammonia with a temperature of 40±5℃ entering the refining tower, after the heat exchange is completed, the outlet gaseous ammonia of the refining tower is reduced to 0±3℃, and the liquid ammonia is warmed to 30±5℃;

[0034] (4) The liquid ammonia with a temperature of 30±5℃ enters a fourth heat exchanger, exchanges heat with purified water with a temperature of 45±5℃ in the fourth heat exchanger, after the heat exchange is completed, the temperature of the liquid ammonia is increased to 37±2℃, and the pressure is increased to 1.3±0.1MPa, and the liquid ammonia is stored in a high-pressure liquid ammonia tank.

[0035] By using the above technical scheme, the cold energy of the liquid ammonia can be fully utilized, the energy consumption of the ammonia production process is reduced, and the desulfurization effect is improved.

[0036] The beneficial effects of the present application are: short process flow, low energy consumption, safe and reliable system operation, and high purity of recovered liquid ammonia. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The figure is a structural diagram of the ammonia refining device of the present application.

[0038] Figure 2 The second heat exchanger structure diagram of the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the present application more clear, the technical scheme of the present application will be described clearly and completely below in combination with the drawings and a preferred embodiment.

[0040] Referring to Figure 1 and Figure 2 , the present application provides an ammonia refining device, which comprises a refining tower 1, a crystallization tank 2, an adsorption tank 3, a cyclone separator 4, a variable frequency refrigerator 5, a low-pressure liquid ammonia tank 6, a low-pressure liquid ammonia pump 7, a high-pressure liquid ammonia tank 8, a liquid ammonia delivery pump 9, a refining tower circulating pump 10, a first heat exchanger 11, a second heat exchanger 12, a third heat exchanger 13, a fourth heat exchanger 14, a blowdown tank 15 and a blowdown pump 16.

[0041] The refining tower 1, the crystallization tank 2 and the adsorption tank 3 are connected in sequence and respectively carry out three-stage desulfurization on the ammonia gas from the sewage stripping device after three-stage condensation cooling, which is a prior art; that is, the ammonia gas from the three stages firstly enters the lower part of the refining tower 1, the refining tower circulating pump 10 sends the concentrated ammonia water at the bottom of the refining tower to the top of the refining tower as a washing agent, the ammonia gas is countercurrently contacted with the washing agent to wash and remove most of the hydrogen sulfide and water in the ammonia gas; the washed ammonia gas containing sulfur enters the bottom of the crystallization tank 2, is uniformly dispersed into the liquid ammonia in the crystallization tank through a distributor, is fully contacted with the liquid ammonia, exchanges substances, and reacts to generate ammonium hydrosulfide under low temperature, most of the hydrogen sulfide is fixed in the liquid phase and removed; the ammonia gas containing a small amount of hydrogen sulfide from the crystallization tank 2 enters the adsorption tank 3, and the hydrogen sulfide, water, phenol, oil and other impurities in the ammonia gas are adsorbed by the activated carbon adsorbent.

[0042] The existing process is that the ammonia gas from the adsorption tank enters a compressor, is compressed and condensed into liquid ammonia for storage, or enters a rectification tower, is rectified by pressure increase in the rectification tower, high-pressure ammonia gas is obtained at the top of the tower, and the ammonia gas is cooled by a cooler to obtain high-purity liquid ammonia.

[0043] The inventor finds that in actual operation, the purity of the ammonia gas from the adsorption tank can reach more than 99.7%, and the content of hydrogen sulfide is less than 10 ppm, which meets the industrial liquid ammonia use standard, therefore, in the embodiment, a method is proposed to omit the rectification process, increase the cyclone separator 4, the variable frequency refrigerator 5, the low-pressure liquid ammonia tank 6, the low-pressure liquid ammonia pump 7 and the high-pressure liquid ammonia tank 8 behind the adsorption tank, and additionally provide the second heat exchanger 12 and the third heat exchanger 13 in the refining tower 1, the first heat exchanger 11 in the crystallization tank 2 and the fourth heat exchanger 14 on the inlet pipeline of the high-pressure liquid ammonia tank 8.

[0044] The inlet of the cyclone separator 4 is communicated with the outlet at the top of the adsorption tank 3 through a pipeline, the outlet at the top of the cyclone separator 4 is communicated with the inlet of the variable frequency refrigerator 5 through a pipeline, the outlet of the variable frequency refrigerator 5 is communicated with the inlet of the low-pressure liquid ammonia tank 6 through a pipeline; the inlet of the low-pressure liquid ammonia pump 7 is communicated with the low-pressure liquid ammonia tank 6, the outlet of the low-pressure liquid ammonia pump 7 is connected with the inlets and outlets of the first heat exchanger 11, the second heat exchanger 12, the third heat exchanger 13 and the fourth heat exchanger 14 through pipelines in sequence, and the outlet of the fourth heat exchanger 14 is connected with the inlet of the high-pressure liquid ammonia tank 8 through a pipeline.

[0045] Through the above improvement, the gaseous ammonia from the adsorption tank is removed of carbon powder and moisture through the cyclone separator 4, and then enters the variable frequency refrigerator 6, and is directly changed into liquid ammonia after exchanging heat with the refrigerant medium of the variable frequency refrigerator 6, and is temporarily stored in the low-pressure liquid ammonia tank 6, and the liquid ammonia in the low-pressure liquid ammonia tank 6 is pumped into the first heat exchanger 11, the second heat exchanger 12, the third heat exchanger 13 and the fourth heat exchanger 14 in sequence through the low-pressure liquid ammonia pump 7, and the temperature and pressure are increased after heat exchange, and then the liquid ammonia enters the high-pressure liquid ammonia tank 8 for safe storage.

[0046] The improved ammonia refining process does not use a rectifying tower, the process is simple, and the energy consumption is greatly reduced; the variable frequency refrigerator is used to cool the gaseous ammonia, the refrigerant is closed-loop circulated in the refrigerator, and does not directly contact with the ammonia gas, so that the compressor failure caused by the liquid carried by the process medium (ammonia gas) is avoided, and the safe operation of the system is ensured. Through three-stage heat exchange, the cold energy of the liquid ammonia in the low-pressure liquid ammonia tank 6 can be fully utilized to cool the crystallization tank and the refining tower, and the remaining part of the cold energy is exchanged with the purified water, on the one hand, the cold energy is reused, the energy consumption of the ammonia production process is reduced, on the other hand, the ammonia loss caused by the liquid ammonia supplement for cooling in the existing process is reduced, and the ammonia recovery rate is improved.

[0047] In specific implementation, the first heat exchanger 11 is arranged at the bottom of the crystallization tank 2, and includes heat exchange pipes A, preferably the heat exchange pipes A are coil pipes, the two ends of the coil pipes extend out of the side wall of the crystallization tank 2 to form the inlets and outlets of the heat exchange medium, and the inlet is located above the outlet. The inlet and the outlet are communicated through a connecting pipeline A, and a temperature regulating valve A is arranged on the connecting pipeline A; the temperature regulating valve A adjusts the flow of the gaseous ammonia entering the crystallization tank, so as to control the temperature of the gaseous ammonia at the outlet of the crystallization tank, and ensure the desulfurization effect. The low-pressure liquid ammonia pump 8 is arranged at the front side of the low-pressure liquid ammonia tank 6, the inlet of the low-pressure liquid ammonia pump is communicated with the low-pressure liquid ammonia tank 6 through a pipeline, and the outlet of the low-pressure liquid ammonia pump is connected with the inlet of the heat exchange pipe A through a pipeline and a valve.

[0048] The second heat exchanger 12 and the third heat exchanger 13 are arranged at the bottom of the refining tower 1 and below the tower packing layer.

[0049] The third heat exchanger 13 includes heat exchange pipes C, preferably the heat exchange pipes A are coil pipes, the two ends of the coil pipes extend out of the side wall of the crystallization tank 2 to form the inlets and outlets of the heat exchange medium, and the inlet is located below the outlet.

[0050] The second heat exchanger 12 comprises a square shell 121, the bottom of the shell 121 is provided with an ammonia gas inlet 122, the upper side of the ammonia gas inlet 122 is provided with a lower cap, the upper side of the lower cap is provided with a gas distributor 125; the middle part of the shell is provided with finned heat exchange tube B 124, the upper side of the finned heat exchange tube B 124 is provided with a spray pipe 126, the spray pipe 126 is provided with an atomizing nozzle; the top of the shell is provided with an ammonia gas outlet 123, the upper side of the ammonia gas outlet 123 is provided with an upper cap. The lower cap and the upper cap are used to make the ammonia gas pass through the shell 121, and the ammonia water cannot enter the shell 121, which is beneficial to improve the heat exchange effect of the second heat exchanger 12 and accurately control the temperature of the refined tower outlet gas ammonia.

[0051] The finned heat exchange tube B 124 can be one group or multiple groups in series, and the two ends of the finned heat exchange tube B 124 extend from the side wall of the refining tower 1 to form the inlet and outlet of the heat exchange medium, and the inlet is located above the outlet.

[0052] The outlet of the heat exchange tube A is communicated with the inlet of the heat exchange tube C through a pipeline, the outlet of the heat exchange tube C is communicated with the inlet of the finned heat exchange tube B 124 through a pipeline, and the outlet of the finned heat exchange tube B 124 is communicated with the inlet of the heat exchange tube C through a connecting pipeline B, and the connecting pipeline B is provided with a temperature regulating valve B; the temperature regulating valve B adjusts the flow of the low-temperature liquid ammonia entering the refining tower, so as to control the temperature of the refined tower outlet gas ammonia and ensure the desulfurization effect.

[0053] The outlet of the heat exchange tube B 124 is communicated with the cold medium inlet of the fourth heat exchanger 14 through a pipeline, and the cold medium outlet of the fourth heat exchanger 14 is communicated with the inlet of the high-pressure liquid ammonia tank 8 through a pipeline; the hot medium inlet of the fourth heat exchanger 14 is connected to purified water, and the residual cold quantity of the liquid ammonia is absorbed by the purified water, so that the liquid ammonia is in a temperature stable state before entering the high-pressure liquid ammonia tank, thereby controlling the pressure of the high-pressure liquid ammonia tank. A temperature regulating valve is arranged on the purified water inlet pipeline, and the temperature regulating valve is adjusted according to the pressure of the high-pressure liquid ammonia tank. In winter, the control pressure can be slightly lower, and in summer, it needs to be slightly higher, so as to ensure that the high-pressure liquid ammonia delivery pump will not be empty.

[0054] In the embodiment, the high-pressure liquid ammonia tank 8 is provided with a first liquid ammonia outlet and a second liquid ammonia outlet, the first liquid ammonia outlet is communicated with the liquid ammonia delivery pump 14, and the second liquid ammonia outlet is connected with the ammonia supplement inlet of the refining tower 1 and the ammonia supplement inlet of the crystallization tank 2 through the first ammonia supplement pipeline and the second ammonia supplement pipeline respectively, the ammonia supplement inlet of the refining tower is located above the second heat exchanger 12, the ammonia supplement inlet of the crystallization tank is communicated with the gas ammonia inlet pipeline of the crystallization tank through a pipeline, and the first ammonia supplement pipeline and the second ammonia supplement pipeline are respectively provided with an ammonia supplement adjusting valve A and an ammonia supplement adjusting valve B.

[0055] If the temperature of the overhead outlet gas ammonia cannot be reduced to the process requirement after the heat exchange of the refining tower 1 and the crystallization tank 2 is completed, liquid ammonia can be supplemented through the ammonia supplement pipeline to reduce the temperature by gasification, thereby further ensuring the desulfurization effect of the refining tower 1 and the crystallization tank 2. When the heat exchange pipe needs to be disabled due to leakage, or during specific processes such as start-up and shutdown, liquid ammonia can be supplemented to the refining tower and the crystallization tank through the ammonia supplement pipeline to reduce the temperature by gasification.

[0056] In order to further improve the control effect, temperature controllers can also be arranged on the outlet pipelines of the refining tower and the crystallization tank, and the temperature controller of the refining tower is connected with the ammonia supplement regulating valve A and the temperature regulating valve A, and the temperature controller of the crystallization tank is connected with the ammonia supplement regulating valve B and the ammonia supplement regulating valve B.

[0057] In the embodiment, a branch is arranged on the circulating pipeline of the refining tower 1, the branch is connected with the ammonia water spraying pipe of the second heat exchanger 12, a flow regulating valve is arranged on the branch, a liquid discharge pipe is arranged at the bottom of the refining tower 1, and the liquid discharge pipe is connected with the raw material sewage tank.

[0058] In the embodiment, the top of the low-pressure liquid ammonia tank 6 and the top of the high-pressure liquid ammonia tank 8 are each provided with a non-condensed steam discharge port, the non-condensed steam discharge port is connected with the slag discharge pipeline at the bottom of the cyclone separator 4 through a pipeline, the slag discharge pipeline is connected with a blowdown tank 15, and the blowdown tank 15 is connected with the raw material sewage tank through a blowdown pump 16.

[0059] The method for ammonia refining using the ammonia refining device is as follows:

[0060] (1) The gas ammonia with a temperature of about 0°C from the adsorption tank 3 is introduced into the frequency conversion refrigerator 5 after the carbon powder and water are removed through the cyclone separator 4, and the temperature of the gas ammonia is reduced to about -16°C through the frequency conversion refrigerator 5, and the gas ammonia is converted into liquid ammonia and temporarily stored in the low-pressure liquid ammonia tank 6;

[0061] (2) The liquid ammonia with a temperature of about -16°C is first pumped into the crystallization tank 2 from the low-pressure liquid ammonia tank 6, and the liquid ammonia is exchanged with the concentrated ammonia water at the bottom of the crystallization tank, after the heat exchange is completed, the outlet gas ammonia of the crystallization tank 2 is reduced to about -5°C, and the liquid ammonia is heated to about -14°C;

[0062] (3) The liquid ammonia with a temperature of about -14°C is introduced into the refining tower 1, and the liquid ammonia is exchanged with the gas ammonia with a temperature of about 40°C at the inlet of the refining tower 1 through the second heat exchanger 12, after the heat exchange is completed, the outlet gas ammonia of the refining tower 1 is reduced to about 0°C, and the liquid ammonia is heated to about 30°C;

[0063] (4) The liquid ammonia with a temperature of about 30°C is introduced into the fourth heat exchanger 14, and the liquid ammonia is exchanged with the purified water with a temperature of about 45°C in the fourth heat exchanger 14, after the heat exchange is completed, the temperature of the liquid ammonia is increased to about 37°C, and the pressure is increased to about 1.3 MPa, and the liquid ammonia is stored in the high-pressure liquid ammonia tank 8.

[0064] Through the above process, the operation energy consumption of the ammonia refining device can be reduced by about 70%, the purity of the liquid ammonia in the high-pressure liquid ammonia tank 8 can reach 99.7-99.8%, and the hydrogen sulfide content is 5-8 ppm.

[0065] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements are also within the protection scope of the present application.

Claims

1. An ammonia refining apparatus comprising a refining column (1), a crystallization tank (2) and an adsorption tank (3) connected in series, characterized in that, The cyclone separator (4), the variable frequency refrigerator (5), the low-pressure liquid ammonia tank (6), the low-pressure liquid ammonia pump (7), the high-pressure liquid ammonia tank (8), the first heat exchanger (11), the third heat exchanger (13) and the fourth heat exchanger (14) are further included, The first heat exchanger (11) is arranged at the bottom of the crystallization tank (2) and includes heat exchange pipes A, which are used for cooling concentrated ammonia water at the bottom of the crystallization tank (2); The third heat exchanger (13) is arranged at the bottom of the refining tower (1) and includes heat exchange pipes C, which are used for cooling concentrated ammonia water at the bottom of the refining tower (1); The inlet of the cyclone separator (4) is communicated with the outlet at the top of the adsorption tank (3), the gas outlet at the top of the cyclone separator (4) is communicated with the inlet of the variable frequency refrigerator (5), the outlet of the variable frequency refrigerator (5) is communicated with the inlet of the low-pressure liquid ammonia tank (6), the inlet of the low-pressure liquid ammonia pump (7) is communicated with the low-pressure liquid ammonia tank (6), the outlet of the low-pressure liquid ammonia pump (7) is communicated with the inlet of the heat exchange pipes A, the outlet of the heat exchange pipes A is communicated with the inlet of the heat exchange pipes C, the outlet of the heat exchange pipes C is communicated with the cold medium inlet of the fourth heat exchanger (14), and the cold medium outlet of the fourth heat exchanger (14) is communicated with the inlet of the high-pressure liquid ammonia tank (8).

2. An ammonia refining device according to claim 1, characterized in that The second heat exchanger (12) is further included, which is arranged at the bottom of the refining tower (1) and above the third heat exchanger (13) and includes a heat exchanger shell (121), the bottom of the heat exchanger shell (121) is provided with an ammonia gas inlet (122), the top is provided with an ammonia gas outlet (123), and the middle is provided with heat exchange pipes B (124), which are used for cooling ammonia gas entering the refining tower, the inlet of the heat exchange pipes B is communicated with the outlet of the cooling heat exchange pipes C, and the outlet is communicated with the cold medium inlet of the fourth heat exchanger (14).

3. An ammonia refining device according to claim 2, characterized in that The heat exchange pipes B (124) are finned heat exchange pipes.

4. An ammonia refining device according to claim 2, characterized in that The bottom of the heat exchanger shell (121) is provided with a gas distributor (125), which is located between the ammonia gas inlet (122) and the heat exchange pipes B (124).

5. An ammonia refining device according to claim 2, characterized in that The inlet and outlet of the heat exchange pipes A are communicated through a connecting pipeline A, and the connecting pipeline A is provided with a temperature regulating valve A; the inlet of the heat exchange pipes C and the outlet of the heat exchange pipes B (124) are communicated through a connecting pipeline B, and the connecting pipeline B is provided with a temperature regulating valve B.

6. An ammonia refining device according to claim 2, characterized in that The circulating pipeline of the refining tower (1) is provided with a branch, a circulating ammonia water spray pipe is arranged above the second heat exchanger (12), the circulating ammonia water spray pipe is connected with the branch of the circulating pipeline of the refining tower (1), a flow regulating valve is arranged on the branch, a liquid discharge pipe is arranged at the bottom of the refining tower (1), and the liquid discharge pipe is connected with a raw material sewage tank.

7. An ammonia refining device according to claim 2, characterized in that The high-pressure liquid ammonia tank (8) is provided with a first liquid ammonia outlet and a second liquid ammonia outlet, the first liquid ammonia outlet is communicated with a liquid ammonia delivery pump (9), the second liquid ammonia outlet is connected with a refining tower (1) ammonia supplement inlet and a crystallization tank (2) ammonia supplement inlet through a first ammonia supplement pipeline and a second ammonia supplement pipeline respectively, the refining tower (1) ammonia supplement inlet is located above the second heat exchanger (12), and the crystallization tank (2) ammonia supplement inlet is communicated with a crystallization tank ammonia inlet pipeline.

8. An ammonia refining device according to claim 7, characterized in that The first ammonia supplement pipeline and the second ammonia supplement pipeline are respectively provided with an ammonia supplement regulating valve A and an ammonia supplement regulating valve B.

9. An ammonia refining device according to claim 2, characterized in that The top of the low-pressure liquid ammonia tank (6) and the high-pressure liquid ammonia tank (8) is provided with a non-condensed steam discharge port, which is connected with the deslagging pipeline at the bottom of the cyclone separator (4) through a pipeline, and the deslagging pipeline is connected with a blowdown tank (15), which is connected with the raw material sewage tank through a blowdown pump (16).

10. A process for the purification of ammonia using the ammonia purification apparatus according to any one of claims 2 to 9, characterized in that The method comprises the following steps: (1) The gaseous ammonia with a temperature of 0±3℃ discharged from the adsorption tank (3) is cooled to -19℃ to -13℃ in the frequency conversion refrigerator (5) after removing carbon powder and moisture in the cyclone separator (4), and is temporarily stored in the low-pressure liquid ammonia tank (6) as liquid ammonia; (2) The liquid ammonia with a temperature of -19℃ to -13℃ is first pumped into the first heat exchanger (11) in the crystallization tank (2) from the low-pressure liquid ammonia tank (6), and exchanges heat with the concentrated ammonia water at the bottom of the crystallization tank, after the heat exchange is completed, the outlet gaseous ammonia of the crystallization tank (2) is reduced to -5±3℃, and the liquid ammonia is warmed to -14±3℃; (3) The liquid ammonia with a temperature of -14±3℃ enters the third heat exchanger (13) of the refining tower (1), exchanges heat with the concentrated ammonia water at the bottom of the refining tower, after the heat exchange is completed, enters the second heat exchanger (12) and exchanges heat with the gaseous ammonia with a temperature of 40±5℃ entering the refining tower, after the heat exchange is completed, the outlet gaseous ammonia of the refining tower (1) is reduced to 0±3℃, and the liquid ammonia is warmed to 30±5℃; (4) The liquid ammonia with a temperature of 30±5℃ enters the fourth heat exchanger (14), exchanges heat with the purified water with a temperature of 45±5℃ in the fourth heat exchanger (14), after the heat exchange is completed, the temperature of the liquid ammonia is increased to 37±2℃, and the pressure is increased to 1.3±0.1MPa, and the liquid ammonia is stored in the high-pressure liquid ammonia tank (8).

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