A low-energy-consumption ammonium chloride production system using the soda ash process.

Abstract

This invention discloses a low-energy-consumption ammonium chloride production system using the soda ash process, comprising a mother stock storage tank and a mother stock delivery pipeline. The mother stock delivery pipeline connects to an ammonia absorber and then to an ammonia distribution tank. The outlet of the ammonia distribution tank is connected to two hot ammonia output pipelines. One hot ammonia output pipeline connects to an external cooler refrigeration system, which includes an external cooler for either receiving liquid from a cold crystallizer for ammonium production or switching to receiving hot ammonia solution for cleaning. The other hot ammonia output pipeline sequentially connects to a water cooler and a mother liquor heat exchanger for multi-stage heat recovery and cooling. The height of the external cooler, water cooler, and mother liquor heat exchanger decreases sequentially, and the hot ammonia solution recovers heat energy in a stepped manner, sequentially from the water cooler and mother liquor heat exchanger or from the external cooler, water cooler, and mother liquor heat exchanger. This invention optimizes the ammonium chloride preparation process, reduces secondary material transfer during production, lowers the power consumption and spare parts costs of the production system, and improves the production capacity of the production system.

Description

Technical Field

[0001] This invention relates to the field of combined alkali production technology, and in particular to a low-energy-consumption combined alkali process ammonium chloride production system. Background Technology

[0002] In the chemical industry, carbonation is a complex physicochemical process involving chemical reactions, energy conversion, solute transport and diffusion, and crystallization of supersaturated solutions. It also involves the simultaneous presence and reaction of solid, liquid, and gaseous states of matter. The carbonation tower is the core equipment in the soda ash (sodium carbonate) manufacturing process. The main chemical reactions for soda ash production take place within the carbonation tower, using the ammonia-soda process.

[0003] In the preparation process of soda ash, sodium bicarbonate (NaHCO3) needs to be prepared using ammonium brine and carbon dioxide in a carbonation tower. This typically includes a soda ash carbon filtration production system and an ammonium chloride crystallization production system. Soda ash (Na2CO3) is prepared using salt, carbon dioxide, ammonia, and water as raw materials. First, ammonia is passed into a saturated brine solution to form ammonium brine, and then carbon dioxide is passed in to generate a solution of sodium bicarbonate and ammonium chloride, which have relatively low solubility. The resulting small sodium bicarbonate crystals are then calcined after filtration and washing to obtain soda ash. The chemical reaction equation is shown below: NaCl (liquid) + NH3 (liquid) + H2O (liquid) + CO2 (gas) = ​​NaHCO3 (solid) + NH4Cl (liquid) 2NaHCO3(solid)=Na2CO3(solid)+CO2(g)↑+H2O↑(g) In the soda ash process for ammonium chloride production, the carbon filtration mother liquor (mother liquor solution I) output from the carbon filtration system is converted into a hot ammonium salt solution (hot ammonia solution I, T=42~48℃) after ammonia absorption. This solution is then stored in a hot ammonia I tank. The hot ammonia I solution is pumped to a water cooler for cooling before being transferred to a mother liquor heat exchanger to exchange heat with mother liquor solution II (T=12~17℃) and then stored in a cold ammonia I tank. Finally, the cold ammonia I solution is transferred to a cold crystallizer, maintaining the temperature of the cold crystallizer at 10℃. -12℃ promotes the crystallization of ammonium chloride. The supernatant of the cold crystallizer overflows into the salting-out crystallizer. By adding salt, the common ion effect further promotes the precipitation of ammonium chloride. The supernatant of the salting-out crystallizer overflows into the carbon filter mother liquor storage tank (mother II storage tank) for storage. The mother II solution (T=12~17℃) undergoes subsequent heat exchange and ammonia absorption, and is converted into an ammonium salt solution (ammonia II solution), which is then transported to the carbon filter system of the alkali production system as raw material for the cleaning tower and alkali production tower, forming a alkali production and ammonium production cycle system.

[0004] In the current ammonium chloride preparation process, the mother solution I absorbs ammonia to form a hot ammonia solution I, which first enters the hot ammonia I tank and is then pumped by the hot ammonia I pump to a water cooler for cooling before exchanging heat with the mother solution II. The resulting cold ammonia solution I is then first pumped by the cold ammonia I tank to a cold crystallizer to produce ammonium chloride. The hot ammonia I solution in the hot ammonia I tank is then pumped by the hot ammonia I pump to an external cooler to clean the scale formed during the ammonium production process. This ammonium chloride preparation process is lengthy, and the main material in the reaction system is a mixture of liquid and solid-liquid components. The material transportation requires a large number of pipelines, storage tanks, and pumps, resulting in significant energy loss during material transportation and increased power consumption. Furthermore, the frequent replacement of pumps and pipelines increases spare parts costs. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a low-energy-consumption ammonium chloride production system using the combined alkali process. By optimizing the ammonium chloride preparation process, the secondary transfer of materials during production is reduced, the process flow is shortened, the power consumption and spare parts costs of the production system are reduced, and the production capacity of the production system is improved.

[0006] Technical Solution: The present invention discloses a low-energy-consumption ammonium chloride production system using the soda ash process, comprising a mother liquor storage tank receiving the carbon filtration mother liquor produced by the soda ash carbon filtration system, and a mother liquor delivery pipeline connected to the outlet of the mother liquor storage tank. The mother liquor delivery pipeline is connected to a mother liquor pump and a mother liquor ammonia absorber, and then connected to an ammonia distribution tank via an ammonia delivery pipeline. The outlet of the ammonia distribution tank is connected to two hot ammonia output pipelines. One of the hot ammonia output pipelines is connected to an external cooler refrigeration system via a hot ammonia switching valve. The external cooler refrigeration system includes an external cooler, which can be used for ammonium production operations by receiving liquid from a cold crystallizer for heat exchange or switching to receiving hot ammonia solution for cleaning operations. The other hot ammonia output pipeline is connected to a water cooler and a mother liquor heat exchanger in sequence via a hot ammonia diversion valve for multi-stage heat recovery and cooling, and then returns the cold ammonia solution to the cold crystallizer via a cold ammonia output pipeline. The external cooler is equipped with a hot ammonia I overflow pipe and a hot ammonia I overflow valve connected to the hot ammonia I overflow pipe at its upper part, and the hot ammonia I overflow pipe is connected to the hot ammonia I delivery pipe downstream of the hot ammonia I diversion valve; the height of the external cooler, water cooler and mother liquor heat exchanger decreases sequentially, and the mother liquor pump pumps the hot ammonia I solution sequentially through the external cooler, water cooler and mother liquor heat exchanger or through the water cooler and mother liquor heat exchanger to recover heat energy in a stepped decrease.

[0007] Preferably, the liquid inlet of the cold crystallizer is connected to the cold ammonia I output pipeline of the final stage mother liquor heat exchanger or to the liquid outlet of the tube side of the external cooler. The cold ammonium chloride slurry from the cold crystallizer overflows into the mixing and thickening device, the concentrated slurry from the mixing and thickening device is output to the ammonium chloride centrifuge, and the filter cake produced by the ammonium chloride centrifuge is conveyed to the ammonium chloride drying process or wet ammonium packaging via an ammonium chloride conveyor belt. The supernatant of the cold crystallizer overflows to the salt-out crystallizer, the salt-out ammonium chloride crystal slurry of the salt-out crystallizer overflows to the salt-out thickener, and the concentrated crystal slurry of the salt-out thickener is returned to the cold crystallizer through the ammonium chloride crystal slurry reverse feed pump and the reverse feed crystal slurry delivery pipeline. The salting-out crystallizer is connected to the inlet of the Mother II storage tank via a salting-out overflow pipeline. The outlet of the Mother II storage tank is connected to the Mother Liquor Heat Exchanger and / or the Mother II Heater via a Mother II output pipeline in a counter-current flow. The downstream section of the Mother II output pipeline flows sequentially through the Mother II ammonia absorber and the Ammonia II distribution tank to the Ammonia II clarification tank. The supernatant of the Ammonia II clarification tank overflows into the Ammonia II storage tank. The discharge end of the Ammonia II storage tank is sent to the carbon filtration alkali production process via the Ammonia II conveying pipeline.

[0008] Preferably, the water cooler includes at least two sets, one for standby and one for use, and the upper end of the shell side of the water cooler is provided with a circulating water inlet pipe and a circulating water outlet pipe. Multiple sets of the water cooler are connected in parallel or / and in series, and the hot ammonia I solution flows through the tube side of the water cooler.

[0009] Preferably, the mother liquor heat exchanger includes at least three sets, one of which is for standby use and the other for dual use. The multiple sets of mother liquor heat exchangers are connected in parallel or / and in series. The hot ammonia I solution flowing through the water cooler flows sequentially through the shell side of the mother liquor heat exchanger, and the mother liquor II solution flows sequentially through the tube side of the mother liquor heat exchanger.

[0010] Preferably, the external cooler refrigeration system further includes a liquid ammonia circulation tank and a liquid ammonia separator configured in conjunction with the external cooler; The number of external coolers is four groups, each group includes four external coolers. In each group, two external coolers are used for ammonium production and two external coolers are used for cleaning, and the cleaning operation or ammonium production operation cycle is 12 hours. The liquid ammonia circulation tank is connected to the inlet and outlet ends of the shell side of the external cooler, and the liquid ammonia circulation tank is connected to a liquid ammonia source. The inlet of the liquid ammonia separator is connected to the outlet of the liquid ammonia circulation tank. The liquid outlet of the liquid ammonia separator is connected to the shell-side inlet of the external cooler or the liquid ammonia is stored in a low-pressure refrigeration tank. The gaseous ammonia produced by the liquid ammonia separator is sent to an ammonia absorption / ammonia compressor or to a water seal tank.

[0011] Preferably, the overflow supernatant of the mixing thickener enters the filtrate tank through the overflow pipe of the mixing thickener, and the filtrate in the filtrate tank is returned to the salting-out crystallizer through the filtrate return pipe; The supernatant liquid from the cold crystallizer to the external cooler is also connected to a hot ammonia I delivery pipeline for the external cooler, and the hot ammonia I delivery pipeline for the external cooler is also connected to a hot ammonia I discharge valve.

[0012] Preferably, the filtrate produced by the ammonium chloride centrifuge is transported to a filtrate tank for storage via a centrifuge filtrate conveying pipeline.

[0013] Preferably, a control valve can be connected to any pipeline to control the pipeline opening.

[0014] Preferably, any one or a combination of a pressure sensor, flow sensor, temperature sensor, and safety valve can be connected to any pipeline.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: 1. The ammonium production system of the present invention integrates the original processes of scaling cleaning, cooling of hot ammonia I solution and feeding hot ammonia I into a cold crystallizer into one process, which greatly shortens the ammonium production process, reduces the use of intermediate conveying pipelines, booster pumps and intermediate tanks, and reduces spare parts consumption. 2. In this invention, the height of the external cooler, water cooler, and mother liquor heat exchanger decreases sequentially. The mother pump pumps hot ammonia I, which flows sequentially through the water cooler and mother liquor heat exchanger or through the external cooler, water cooler, and mother liquor heat exchanger, recovering heat energy in a stepped manner to maximize energy utilization. 3. The heat recovery system for cooling ammonia I solution can be used to clean scale in an external cooler or to cool and exchange heat in a water cooler and mother liquor heat exchanger through a hot ammonia I delivery pipeline, depending on the needs. The two are organically combined, thereby shortening the ammonium production process. 4. The mother liquor heat exchanger and mother II heater can increase the solution temperature of the mother II solution as it flows through the subsequent system, thereby reducing the risk of crystallization and clogging of the pipeline in the subsequent system and improving the ammonia absorption efficiency of gaseous ammonia. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the process of the novel low-energy-consumption ammonium chloride production system using the combined alkali process of the present invention. Figure 2 for Figure 1 A schematic diagram of the external air conditioning system.

[0017] Attached reference numerals: 1. Mother liquor storage tank; 2. Mother liquor pump; 3. Mother liquor delivery pipeline; 4. Mother liquor ammonia absorber; 5. Gas ammonia source; 6. Ammonia delivery pipeline; 7. Ammonia distribution tank; 8. Hot ammonia diversion valve; 9. Water cooler; 10. Circulating water inlet pipeline; 11. Circulating water outlet pipeline; 12. Mother liquor heat exchanger; 13. Cold ammonia output pipeline; 14. Solution collection tank; 15. Cold crystallizer; 16. Cold crystallizer 17. Axial flow pump; 18. Cold precipitation overflow tank; 19. Cold precipitation ammonium chloride crystal slurry; 20. Mixing thickener; 21. Ammonium chloride centrifuge; 22. Ammonium chloride conveyor belt; 23. Ammonium chloride drying process; 24. Salting-out crystallizer; 25. Salting-out ammonium chloride crystal slurry; 26. Salting-out thickener; 27. Ammonium chloride crystal slurry reverse feed pump; 28. Reverse feed crystal slurry conveying pipeline; 29. ​​Main II output pipeline 30. Mother II Storage Tank; 31. Mother II Pump; 32. Mother II Heater; 33. Mother II Ammonia Suction Unit; 34. Ammonia II Delivery Pipeline; 35. Ammonia II Distribution Tank; 36. Ammonia II Clarification Tank; 37. Ammonia II Storage Tank; 38. Ammonia II Pump; 39. Hot Ammonia I Switching Valve; 40. Hot Ammonia I Discharge Valve; 41. Hot Ammonia I Overflow Valve; 42. Hot Ammonia I Overflow Pipeline; 43. External Cooler; 44. Liquid Ammonia 45. Circulating tank; 46. Liquid ammonia source; 47. Gaseous ammonia delivery pipeline; 48. Liquid ammonia separator; 49. Gaseous ammonia to ammonia absorption / compressor; 50. Gaseous ammonia to water seal tank; 51. Liquid ammonia to refrigeration low-pressure tank; 52. Mixing thickener overflow pipeline; 53. Centrifuge filtrate delivery pipeline; 54. External cooler hot ammonia I delivery pipeline; 55. Filtrate tank; 56. Filtrate pump; 57. Filtrate return pipeline; 58. Added sodium chloride. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figures 1-2 The technical solutions of the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0019] In the process of producing soda ash using the combined alkali process, raw materials such as salt, carbon dioxide, ammonia, and water undergo a gas-liquid reaction in a carbonization tower to produce sodium bicarbonate and ammonium bicarbonate. Because sodium bicarbonate and ammonium bicarbonate have low solubility in solution, they easily accumulate and form scale within the carbonization tower. If not cleaned regularly, this will cause blockage of the carbonization tower channels, thus reducing the carbonization efficiency. Therefore, in actual production, multiple carbonization towers are required. The carbonization towers with severe scaling are used for circulating cleaning and are also used as cleaning towers in the soda ash production system. Carbonization towers without scaling or with slight scaling are used as soda ash production towers. In the soda ash carbon filtration production system, the cleaning towers, after cleaning, are converted into soda ash production towers; when the soda ash production towers become severely scaled, they are converted into cleaning towers, thus ensuring that the carbonization towers in the soda ash production system are in good working condition. In this process, the filtrate produced by the belt filter from the heavy alkali crystal slurry prepared in the alkali production tower is separated into gas and liquid by a gas-liquid separator. The filtrate then enters the carbon filtration mother liquor clarification tank and the carbon filtration mother liquor storage tank for concentration. The concentrated slurry from the carbon filtration mother liquor clarification tank and the carbon filtration mother liquor storage tank is returned to the alkali production system. The carbon filtration mother liquor (mother I solution) in the carbon filtration mother liquor storage tank is transported to the ammonium chloride process of the combined alkali process through the carbon filtration mother liquor output pipeline for further processing. The carbon filtration mother liquor entering the ammonium chloride production system of the combined alkali process is defined as mother I solution. The main components of mother I solution are NaHCO3, NaCl, NH4Cl, and Na2CO3.

[0020] like Figures 1-2In the illustrated embodiment, the low-energy-consumption ammonium chloride production system of the present invention includes a mother I storage tank 1 that receives the mother I solution produced by the soda ash carbon filtration system and a mother I delivery pipeline 3 connected to the outlet of the mother I storage tank 1. The mother I delivery pipeline 3 is sequentially connected to a mother I pump 2 and a mother I ammonia absorber 4. The mother I solution is pumped by the mother I pump 2 to the mother I ammonia absorber 4 and ammonia gas source 5 to absorb ammonia, converting NaHCO3 into Na2CO3. The solution after one ammonia absorption has a high temperature and needs to be cooled before preparing ammonium chloride to facilitate the crystallization of ammonium chloride. This ammonium salt solution is defined as hot ammonia I solution. The hot ammonia I solution is connected to an ammonia I distribution tank 7 through an ammonia I delivery pipeline 6. The outlet of the ammonia I distribution tank 7 is connected to two hot ammonia I output pipelines. One of the hot ammonia I output pipelines is connected to the external cooler refrigeration system through the hot ammonia I switching valve 39. The external cooler refrigeration system includes an external cooler 43 and a liquid ammonia circulation tank 44 and a liquid ammonia separator 47 that are configured in conjunction with the external cooler 43. There are four groups of external coolers 43, each group including four external coolers. In each group, two external coolers produce ammonia and two external coolers are cleaned in rotation. The cleaning operation or ammonia production operation cycle is 12 hours. The liquid ammonia circulation tank 44 is connected to the shell side inlet end and outlet end of the external cooler 43, and the liquid ammonia circulation tank 44 is connected to the liquid ammonia source 45. The inlet end of the liquid ammonia separator 47 is connected to the gas outlet end of the liquid ammonia circulation tank 44, and the liquid outlet end of the liquid ammonia separator 47 is connected to the shell side inlet end of the external cooler 43 or the liquid ammonia is stored in the refrigeration low-pressure tank 50. The gaseous ammonia produced by the liquid ammonia separator 47 is sent to the ammonia absorption / ammonia compressor 48 or to the water seal tank 49. The external cooler 43 can be a partitioned heat exchanger. The shell side of the external cooler is supplied with liquid ammonia. The shell side of the external cooler is connected to the liquid ammonia circulation tank 44. The liquid ammonia in the liquid ammonia circulation tank acts as a refrigerant as it flows through the shell side of the external cooler. After flowing through the shell side of the external cooler, the liquid ammonia vaporizes and circulates back into the liquid ammonia circulation tank 44. The gaseous ammonia stored in the liquid ammonia circulation tank 44 is transported to the liquid ammonia separator 47 through the gas ammonia conveying pipeline 46 for gas-liquid separation. The liquid ammonia separated by the liquid ammonia separator returns to the shell side of the external cooler 43 for refrigeration or goes to the refrigeration low-pressure tank 50 for storage and standby. The gaseous ammonia separated by the liquid ammonia separator 47 can flow into the main ammonia absorber 41 and the main ammonia absorber 33 for ammonia absorption reaction or go to the water seal tank.

[0021] A cold axial flow pump 16 is installed in the cold crystallizer 15. The cold axial flow pump 16 can transport the supernatant liquid of the cold crystallizer 15 to the tube side of the external cooler 43 through the cold circulation pipeline. When the liquid ammonia flows through the shell side of the external cooler, it cools the liquid flowing in the tube side of the external cooler 43. After cooling, the liquid returns to the cold crystallizer 15 and further cools the cold ammonia I solution in the cold crystallizer so as to facilitate the condensation and crystallization of ammonium chloride for ammonium production.

[0022] A hot ammonia I overflow pipe 42 is installed at the upper part of the external cooler 43. A hot ammonia I overflow valve 41 is connected to the hot ammonia I overflow pipe 42, and the hot ammonia I overflow pipe 42 is connected to the hot ammonia I delivery pipe downstream of the hot ammonia I diversion valve 8. After the external cooler 43 completes one ammonium production cycle, the hot ammonia I switching valve 39 is activated. The tube side of the external cooler can switch to receive hot ammonia I solution for cleaning and scaling operations to clean the scaling on the side wall of the external cooler tube side during the ammonium production process. The mother I solution absorbs ammonia to form hot ammonia I solution (1200 m³ / h, T=42~48℃) and no longer enters the hot ammonia I tank. The solution is directly transported to the tube side of the external cooler for scaling cleaning. The cleaning process of the external cooler 43 directly accepts the hot ammonia I solution, which can reduce the heat loss during the intermediate transfer process. The hot ammonia I solution is more stable when it enters the external cooler 43, thereby improving the scaling cleaning effect on the external cooler. The hot ammonia I solution that has completed cleaning the external cooler 43 flows back through the hot ammonia I overflow pipe 42 at a high level and flows through the water cooler 9 and the mother liquor heat exchanger 12 to exchange heat with the mother II solution to form a cold ammonia I solution. Then, it is pressurized and transported to the cold crystallizer 15 through the cold ammonia I output pipe 13 to produce ammonium chloride.

[0023] The ammonium production process of this invention integrates the original processes of scaling and cleaning, cooling of hot ammonia I solution, and feeding hot ammonia I into a cold crystallizer into one process, which greatly shortens the ammonium production process, reduces the use of intermediate conveying pipelines, booster pumps and intermediate tanks, and reduces spare parts consumption.

[0024] Another hot ammonia I output pipeline is connected to the water cooler 9 and the mother liquor heat exchanger 12 in sequence through the hot ammonia I diversion valve 8 for multi-stage heat recovery and cooling. The hot ammonia I diversion valve 8 can control the connection of this process. When the four groups of a total of sixteen external coolers 43 are in the alternation process of ammonium production and cleaning operations, and the cleaning requirements are met, the hot ammonia I diversion valve 8 can be opened to conduct the hot ammonia I output pipeline. The hot ammonia I solution undergoes heat recovery when passing through the water cooler 9 and the mother liquor heat exchanger 12, and the temperature of the hot ammonia I solution is reduced to the precipitation process temperature of the cold crystallizer 15. At this time, the ammonium salt solution is defined as the cold ammonia I solution. The cold ammonia I solution is returned to the cold crystallizer 15 for precipitation through the cold ammonia I output pipeline 13. A solution collection tank 14 is set at the liquid inlet on one side of the cold crystallizer 15. The cold ammonia I solution is first pumped into the solution collection tank 14 and then distributed into the cold crystallizer 15 for precipitation. In this embodiment, the heights of the external cooler 43, water cooler 9, and mother liquor heat exchanger 12 decrease sequentially. The mother I pump 2 pumps hot ammonia I solution to the water cooler 9 and mother liquor heat exchanger 12 in a stepped manner, or the external cooler 43, water cooler 9, and mother liquor heat exchanger 12, to recover heat energy and maximize energy utilization.

[0025] like Figure 1In the illustrated embodiment, the inlet of the cold crystallizer 15 is connected to the cold ammonia I output pipeline 13 of the final stage mother liquor heat exchanger 12 or to the outlet of the tube side of the external cooler 43. When the external cooler 43 is in ammonium production operation, the cold axial flow pump 16 draws the supernatant liquid from the cold crystallizer 15 and pumps it into the tube side of the external cooler 43 for cooling and heat exchange, and then returns the liquid to the cold crystallizer 15 for ammonium chloride production. Alternatively, when the external cooler 43 is in cleaning operation, the hot ammonia I solution enters the tube side of the external cooler to clean the scale and then overflows through the hot ammonia I overflow pipeline 42. The hot ammonia I delivery pipeline sequentially enters the water cooler 9 and the mother liquor heat exchanger 12 to exchange heat with the mother liquor II solution. Then, it is returned to the cold crystallizer 15 through the cold ammonia I output pipeline 13 for ammonium production. This hot ammonia I solution cooling and heat recovery system can be used to either enter the external cooler for cleaning scale or enter the water cooler and mother liquor heat exchanger through the hot ammonia I delivery pipeline for cooling and heat exchange, thus achieving an organic combination of the two. This shortens the ammonium production process, reduces the use of intermediate delivery pipelines, pumps, and intermediate tanks, and lowers production costs.

[0026] The cold-precipitated ammonium chloride slurry 18 from the cold crystallizer 15 overflows to the mixing and thickening tank 19 for further thickening. The concentrated slurry from the mixing and thickening tank 19 is output to the ammonium chloride centrifuge 20. The filter cake produced by the ammonium chloride centrifuge 20 is conveyed by the ammonium chloride conveyor belt 21 to the ammonium chloride drying process 22 or wet ammonium packaging for further preparation of ammonium chloride. The supernatant from the cold crystallizer 15 overflows through the cold overflow tank 17 to the salt-precipitation crystallizer 23. A salt-precipitation axial flow pump 24 is installed in the center of the salt-precipitation crystallizer 23. Sodium chloride 57 is added to the solution in the salt-precipitation crystallizer 23 to further promote the crystallization of ammonium chloride. The salt-precipitated ammonium chloride slurry 25 from the salt-precipitation crystallizer 23 overflows to the salt-precipitation thickening tank 26. The concentrated slurry from the salt-precipitation thickening tank 26 is returned to the cold crystallizer 15 through the ammonium chloride slurry backflow pump 27 and the backflow slurry conveying pipeline 28 for circulating crystallization. The salt-out crystallizer 23 is connected to the inlet of the mother II storage tank 30 through the salt-out overflow pipeline. The supernatant overflow of the salt-out thickener 26 flows through the mother II output pipeline to the mother II storage tank 30. The supernatant overflow of the salt-out crystallizer 23 and the salt-out thickener 26 is defined as the mother II solution. The outlet of the mother II storage tank 30 is connected to the mother liquor heat exchanger 12 and / or the mother II heater 32 in a countercurrent manner through the mother II output pipeline 29 for preheating. The downstream section of the mother II output pipeline 29 flows through the mother II ammonia absorber 33 and the ammonia II distribution tank 35 to the ammonia II clarification tank 36. The supernatant of the ammonia II clarification tank 36 overflows to the ammonia II storage tank 37. The discharge end of the ammonia II storage tank 37 is sent to the carbon filtration alkali production process through the ammonia II conveying pipeline 34. The mother liquor heat exchanger 12 and the mother II heater 32 can increase the solution temperature of the mother II solution in the subsequent system to reduce the risk of crystal precipitation and pipeline blockage in the subsequent system and improve the ammonia absorption efficiency of gaseous ammonia.

[0027] like Figure 1In the embodiment shown, the water cooler 9 includes at least two sets, one for standby and one for use. The upper end of the shell side of the water cooler 9 is provided with a circulating water inlet pipe 10 and a circulating water outlet pipe 11. Multiple sets of water coolers 9 are connected in parallel or / and in series. The hot ammonia I solution flows through the tube side of the water cooler 9, and the condensate flows through the water cooler 9 to achieve heat recovery of the hot ammonia I solution.

[0028] like Figure 1 In the embodiment shown, the mother liquor heat exchanger 12 includes at least three sets of one standby heat exchangers. Multiple sets of mother liquor heat exchangers 12 are connected in parallel or / and in series. The hot ammonia I solution flowing through the water cooler 9 flows sequentially through the shell side of the mother liquor heat exchanger 12, and the mother liquor II solution flows sequentially through the tube side of the mother liquor heat exchanger 12. The hot ammonia I solution and the mother liquor II solution exchange heat in the mother liquor heat exchanger 12.

[0029] like Figure 1 In the illustrated embodiment, the overflow supernatant of the thickener 19 enters the filter tank 54 through the thickener overflow pipe 51, and the filtrate in the filter tank 54 returns to the salting-out crystallizer 23 through the filtrate return pipe 56; the supernatant of the cold crystallizer 15 is also connected to the external cooler 43 via the external cooler hot ammonia I delivery pipe 53, which is also connected to the hot ammonia I discharge valve 40. After the external cooler 43 completes the scaling cleaning, the hot ammonia I discharge valve 40 is activated to deliver the cleaning liquid to the filter tank 54 for storage; the filtrate produced by the ammonium chloride centrifuge 20 is delivered to the filter tank 54 for storage via the centrifuge filtrate delivery pipe 52.

[0030] In the above embodiments, in this low-energy-consumption soda ash process ammonium chloride production system, a control valve can be connected to any conveying pipeline as needed. The control valve can control the opening and closing of the relevant conveying pipeline or control the flow rate. The control valve can be a ball valve, butterfly valve, etc., and can be a manual valve, an electric valve, a magnetic valve, etc., as long as it meets the requirement of controlling the pipeline opening degree. The hot ammonia I output pipeline, cold ammonia I output pipeline, reverse material crystal slurry conveying pipeline, filtrate return pipeline, mother II output pipeline, and ammonia II conveying pipeline can all be connected to conveying pumps and shut-off valves that cooperate with the inlet and outlet ends of the conveying pumps, such as mother II pump 31, ammonia II pump 38, filtrate pump 55, etc. The conveying pumps connected to the relevant conveying pipelines meet the requirements for extended liquid conveying. Any conveying pipeline can be connected to one or a combination of pressure sensors, flow sensors, temperature sensors, and safety valves. By connecting the corresponding sensors, the pressure, flow rate, volume, and other indicators of the fluid flowing through the conveying pipeline can be detected.

[0031] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-energy-consumption ammonium chloride production system using the soda ash process, characterized in that, The system includes a mother I storage tank (1) that receives the carbon filter mother liquor produced by the soda ash carbon filtration system and a mother I delivery pipeline (3) connected to the outlet of the mother I storage tank (1). The mother I delivery pipeline (3) is connected to a mother I pump (2) and a mother I ammonia absorber (4) to absorb ammonia, and then connected to an ammonia distribution tank (7) via an ammonia delivery pipeline (6). The outlet of the ammonia distribution tank (7) is connected to two hot ammonia output pipelines. One of the hot ammonia output pipelines is connected to an external ammonia distribution tank via a hot ammonia switching valve (39). The external cooler refrigeration system includes an external cooler (43), which includes an ammonium production operation that receives liquid from the cold crystallizer for heat exchange or switches to receiving hot ammonia I solution for cleaning operation; another hot ammonia I output pipeline is connected to a water cooler (9) and a mother liquor heat exchanger (12) in sequence through a hot ammonia I diversion valve (8) for multi-stage heat recovery and cooling, and the cold ammonia I solution is returned to the cold crystallizer (15) through the cold ammonia I output pipeline (13). The external cooler (43) is provided with a hot ammonia I overflow pipe (42) and a hot ammonia I overflow valve (41) connected to the hot ammonia I overflow pipe (42). The hot ammonia I overflow pipe (42) is connected to the hot ammonia I conveying pipe downstream of the hot ammonia I diversion valve (8). The height of the external cooler (43), water cooler (9) and mother liquor heat exchanger (12) decreases sequentially. The mother I pump (2) pumps hot ammonia I solution to flow sequentially through the external cooler (43), water cooler (9) and mother liquor heat exchanger (12) or through the water cooler (9) and mother liquor heat exchanger (12) to recover heat energy in a step-by-step manner. The water cooler (9) includes at least two sets, one for standby and one for use. The upper shell side of the water cooler (9) is provided with a circulating water inlet pipe (10) and a circulating water outlet pipe (11). Multiple sets of the water cooler (9) are connected in parallel or / and in series. The hot ammonia I solution flows through the tube side of the water cooler (9). The mother liquor heat exchanger (12) includes at least three sets, one for standby and two for use. Multiple sets of the mother liquor heat exchanger (12) are connected in parallel or / and in series. The hot ammonia I solution flowing through the water cooler (9) flows through the shell side of the mother liquor heat exchanger (12) in sequence, and the mother liquor II solution flows through the tube side of the mother liquor heat exchanger (12) in sequence.

2. The low-energy-consumption ammonium chloride production system according to claim 1, characterized in that, The liquid inlet of the cold crystallizer (15) is connected to the cold ammonia I output pipeline (13) of the final stage mother liquor heat exchanger (12) or to the liquid outlet of the tube side of the external cooler (43). The cold crystallizer (15) overflows the cold ammonium chloride slurry to the mixing and thickening device (19), and the concentrated slurry from the mixing and thickening device (19) is output to the ammonium chloride centrifuge (20). The filter cake produced by the ammonium chloride centrifuge (20) is conveyed to the ammonium chloride drying process (22) or wet ammonium packaging via the ammonium chloride conveyor belt (21). The supernatant of the cold crystallizer (15) overflows to the salt crystallizer (23), the salt crystallized ammonium chloride slurry (25) of the salt crystallizer (23) overflows to the salt thickener (26), and the concentrated slurry of the salt thickener (26) returns to the cold crystallizer (15) through the ammonium chloride slurry backfeed pump (27) and backfeed slurry delivery pipeline (28). The salting crystallizer (23) is connected to the inlet of the mother II storage tank (30) through the salting overflow pipeline. The outlet of the mother II storage tank (30) is connected to the mother liquor heat exchanger (12) or / and the mother II heater (32) in reverse flow through the mother II output pipeline (29). The downstream section of the mother II output pipeline (29) flows through the mother II ammonia absorber (33), the ammonia II distribution tank (35) to the ammonia II clarification tank (36). The supernatant of the ammonia II clarification tank (36) overflows to the ammonia II storage tank (37). The discharge end of the ammonia II storage tank (37) is sent to the carbon filtration alkali production process through the ammonia II conveying pipeline (34).

3. The low-energy-consumption ammonium chloride production system according to claim 1, characterized in that, The external cooler refrigeration system also includes a liquid ammonia circulation tank (44) and a liquid ammonia separator (47) that are configured in conjunction with the external cooler (43). The number of external coolers (43) is four groups, each group includes four external coolers. In each group, two external coolers are used for ammonium production and two external coolers are used for cleaning. The cleaning operation or ammonium production operation cycle is 12 hours. The liquid ammonia circulation tank (44) is connected to the inlet and outlet of the shell side of the external cooler (43), and the liquid ammonia circulation tank (44) is connected to the liquid ammonia source (45). The inlet end of the liquid ammonia separator (47) is connected to the outlet end of the liquid ammonia circulation tank (44), the liquid outlet end of the liquid ammonia separator (47) is connected to the shell-side inlet end of the external cooler (43) or the liquid ammonia is stored in the refrigeration low-pressure tank (50), and the gaseous ammonia produced by the liquid ammonia separator (47) is sent to the ammonia absorption / ammonia compressor (48) or to the water seal tank (49).

4. The low-energy-consumption ammonium chloride production system according to claim 2, characterized in that, The overflow supernatant of the mixing thickener (19) enters the filter tank (54) through the mixing thickener overflow pipe (51), and the filtrate in the filter tank (54) returns to the salting-out crystallizer (23) through the filtrate return pipe (56). The supernatant of the cold crystallizer (15) to the external cooler (43) is also connected to the external cooler hot ammonia I delivery pipeline (53), and the external cooler hot ammonia I delivery pipeline (53) is also connected to the hot ammonia I discharge valve (40).

5. The low-energy-consumption ammonium chloride production system according to claim 4, characterized in that, The ammonium chloride centrifuge (20) produces filtrate, which is then transported to the filtrate tank (54) via the centrifuge filtrate delivery pipeline (52) for storage.

6. The low-energy-consumption ammonium chloride production system according to any one of claims 1 to 5, characterized in that, A control valve can be connected to any pipeline to control the pipeline opening.

7. The low-energy-consumption ammonium chloride production system according to any one of claims 1 to 5, characterized in that, Pressure sensors, flow sensors, temperature sensors, and safety valves, or a combination thereof, can be connected to any pipeline.

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