Residual ammonia water self-circulation ammonia distillation system

Abstract

The utility model discloses a residual ammonia water self-circulation ammonia distillation system, and belongs to the technical field of ammonia water treatment. The residual ammonia water self-circulation ammonia distillation system comprises an ammonia water supply system, a deacidification system, an ammonia distillation circulation system and an ammonia water generation system which are communicated in sequence, the ammonia distillation circulation system is communicated with the ammonia water supply system, and the ammonia water generation system is communicated with the deacidification system. According to the technical scheme, the system is utilized, the technological method of residual ammonia water self-circulation ammonia distillation is achieved, the energy-saving efficiency is improved, the production cost is reduced, and recycling of ammonia is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of ammonia water treatment, in particular to a residual ammonia water self-circulating ammonia distillation system. Background Art

[0002] At present, a large amount of residual ammonia water is generated in the production and life of the coking and lignite industries, and it is necessary to use an ammonia distillation process to recover the ammonia water. However, the existing distillation process generally has the disadvantage of high energy consumption. The concentration of the recovered ammonia water is generally less than 15%, and the impurity content is relatively high, making it impossible to sell it as a commodity.

[0003] The "tubular furnace ammonia distillation process" with patent application number 200910201895.4 uses surplus coke oven gas from coking plants, blast furnace gas from steel mills, and other available combustible gases as fuel. It uses a tubular furnace to heat the circulating wastewater at the bottom of the ammonia distillation tower to a certain temperature before entering the ammonia distillation tower, thereby replacing or partially replacing direct steam. This process lacks energy-saving measures.

[0004] Patent application number 201310147764.9, "Process for Distilling Ammonia Using Waste Heat from Coke Oven Flue Gas," utilizes waste heat from the coking plant's coke oven flue gas as a heat source. This method heats wastewater at the bottom of the ammonia distillation tower to 160°C and flash-evaporates it. The resulting secondary steam enters the tower to distill the raw ammonia solution. The resulting ammonia gas is then directly fed to the ammonium sulfate process or further condensed into concentrated ammonia solution. This process merely changes the way the flue gas waste heat is utilized, reducing or eliminating the capacity of the existing flue gas waste heat boiler. Therefore, this utility model does not inherently achieve any energy-saving benefits.

[0005] Patent application number 201310578282.9, "An Apparatus and Improved Method for Ammonia Distillation from Coking Residual Ammonia," utilizes a sulfuric acid solution to scrub the ammonia-containing steam exiting the ammonia distillation tower, absorbing ammonia from the secondary steam. This steam, which has absorbed ammonia, is then pressurized and heated using a steam heat pump and returned to the ammonia distillation tower as a heat source. A portion of the deammoniated secondary steam is then pressurized using a two-stage mechanical compression heat pump to heat the reboiler at the bottom of the ammonia distillation tower. While this system offers significant energy savings, it converts ammonia into ammonium sulfate rather than supplying it to the coke oven gas desulfurization unit, potentially leading to a shortage of ammonia for the desulfurization process. Furthermore, the production of ammonium sulfate crystals consumes significant amounts of steam, weakening the energy efficiency of the system.

[0006] Therefore, it is necessary to design a self-circulating ammonia distillation system for residual ammonia water. Utility Model Content

[0007] The purpose of the utility model is to provide a self-circulating ammonia distillation system for residual ammonia water to solve the problems raised in the above background technology.

[0008] To achieve the above objectives, the present invention provides the following technical solutions:

[0009] A system for self-circulating ammonia distillation of excess ammonia water comprises an ammonia water supply system, a deacidification system, an ammonia distillation circulation system, and an ammonia water generation system which are connected in sequence. The ammonia distillation circulation system is connected to the ammonia water supply system, and the ammonia water generation system is connected to the deacidification system.

[0010] As a further solution of the present invention: the ammonia water supply system includes a raw ammonia water tank, the raw ammonia water tank is connected to an ammonia water-wastewater heat exchanger, a raw ammonia water pump is arranged between the raw ammonia water tank and the ammonia water-wastewater heat exchanger, and the ammonia water-wastewater heat exchanger is respectively connected to the deacidification system and the ammonia distillation circulation system.

[0011] As a further solution of the present invention: the deacidification system includes a deacidification tower connected to an ammonia water-wastewater heat exchanger, the distillation section of the deacidification tower is provided with a washing section, the middle part of the deacidification tower is connected to a flash tank 1, a steam compressor 1, and the lower part of the deacidification tower in sequence, the bottom of the flash tank 1 is connected to the top of the deacidification tower through a deacidification tower reflux pump, and the bottom of the deacidification tower is connected to the ammonia distillation circulation system.

[0012] As a further solution of the present invention: the ammonia evaporation circulation system includes an ammonia evaporation tower connected to the bottom of the deacidification tower, the top of the ammonia evaporation tower is connected to steam compressor 2, the upper part of the reboiler and the lower part of the ammonia evaporation tower in sequence, the lower part of the ammonia evaporation tower is connected to the ammonia water-wastewater heat exchanger, the bottom of the reboiler is connected to the bottom of the ammonia evaporation tower, a reboiler circulation pump is arranged between the bottom of the reboiler and the bottom of the ammonia evaporation tower, the lower part of the reboiler is connected to the ammonia water generation system, and the upper part of the ammonia evaporation tower is connected to the ammonia water generation system.

[0013] As a further solution of the present invention: the ammonia water generation system includes a gas-liquid separator, the top of the gas-liquid separator is connected to the upper part of the deacidification tower, the lower part of the gas-liquid separator is connected to the reboiler, the bottom of the gas-liquid separator is connected to the second flash tank, the top of the second flash tank is connected to the condenser cooler and the intermediate tank in sequence, the bottom of the second flash tank is connected to the reflux pump of the ammonia still tower, and the reflux pump of the ammonia still tower is respectively connected to the gas-liquid separator and the upper part of the ammonia still tower.

[0014] The beneficial effects of the utility model are as follows: the high-temperature circulating washing water generated by the flash tank pair in the deacidification tower flashes out secondary steam, which is compressed and heated by the steam compressor one and then sent back to the bottom of the deacidification tower to provide heat for the deacidification tower; the steam compressor two compresses the steam from the top of the ammonia evaporation tower and sends it to the reboiler at the bottom of the ammonia evaporation tower, effectively recovering the latent heat of evaporation of the secondary steam; the utility model achieves an energy-saving efficiency of more than 80% through the cooperation of the above devices, and at the same time, can produce ammonia water with adjustable concentration, realizes the recovery and utilization of ammonia, and saves costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a flow chart of a system for self-circulating ammonia distillation of residual ammonia water;

[0016] In the figure: 1. Raw ammonia water tank; 2. Raw ammonia water pump; 3. Ammonia water-wastewater heat exchanger; 4. Steam compressor 1; 5. Flash tank 1; 6. Deacidification tower reflux pump; 7. Deacidification tower; 8. Ammonia distillation tower; 9. Reboiler circulation pump; 10. Reboiler; 11. Steam compressor 2; 12. Gas-liquid separator; 13. Flash tank 2; 14. Ammonia distillation tower reflux pump; 15. Condenser cooler; 16. Intermediate tank. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] Example

[0019] See also Figure 1 ,like Figure 1 As shown, a residual ammonia self-circulating ammonia distillation system includes an ammonia supply system, a deacidification system, an ammonia distillation circulation system, and an ammonia generation system connected in sequence. The ammonia distillation circulation system is connected to the ammonia supply system, and the ammonia generation system is connected to the deacidification system.

[0020] The ammonia water supply system includes a raw ammonia water tank 1, which is connected to an ammonia water-wastewater heat exchanger 3. A raw ammonia water pump 2 is provided between the raw ammonia water tank 1 and the ammonia water-wastewater heat exchanger 3. The ammonia water-wastewater heat exchanger 3 is respectively connected to the deacidification system and the ammonia distillation circulation system.

[0021] The deacidification system includes a deacidification tower 7 connected to an ammonia-wastewater heat exchanger 3. The distillation section of the deacidification tower 7 is provided with a washing section. The middle part of the deacidification tower 7 is connected in sequence to a flash tank 5, a steam compressor 4, and the lower part of the deacidification tower 7. The bottom of the flash tank 5 is connected to the top of the deacidification tower 7 through a deacidification tower reflux pump 6. The bottom of the deacidification tower 7 is connected to the ammonia distillation circulation system.

[0022] The ammonia evaporation circulation system includes an ammonia evaporation tower 8 connected to the bottom of the deacidification tower 7, the top of the ammonia evaporation tower 8 is connected to the steam compressor 11, the upper part of the reboiler 10 and the lower part of the ammonia evaporation tower 8 in sequence, the lower part of the ammonia evaporation tower 8 is connected to the ammonia water-wastewater heat exchanger 3, the bottom of the reboiler 10 is connected to the bottom of the ammonia evaporation tower 8, a reboiler circulation pump 9 is provided between the bottom of the reboiler 10 and the bottom of the ammonia evaporation tower 8, the lower part of the reboiler 10 is connected to the ammonia water generation system, and the upper part of the ammonia evaporation tower 8 is connected to the ammonia water generation system.

[0023] The ammonia solution generating system includes a gas-liquid separator 12, the top of the gas-liquid separator 12 is connected to the upper part of the deacidification tower 7, the lower part of the gas-liquid separator 12 is connected to the reboiler 10, the bottom of the gas-liquid separator 12 is connected to the flash tank 2 13, the top of the flash tank 2 13 is connected to the condenser cooler 15 and the intermediate tank 16 in sequence, the bottom of the flash tank 2 13 is connected to the ammonia still tower reflux pump 14, and the ammonia still tower reflux pump 14 is respectively connected to the gas-liquid separator 12 and the upper part of the ammonia still tower 8.

[0024] A process for self-circulating ammonia distillation using residual ammonia water comprises the following steps:

[0025] S1, the ammonia water in the raw ammonia water tank 1 is pressurized by the raw ammonia water pump 2 and enters the ammonia water-wastewater heat exchanger 3. Specifically, the flow rate of the ammonia water is 40m 3 / h, fully exchange heat with the high-temperature wastewater from the bottom of the ammonia distillation tower 8, and the raw ammonia water is heated to 95℃-105℃ before entering the deacidification tower 7;

[0026] S2, ammonia water is affected by temperature and pressure in the deacidification tower 7. The operating pressure of the deacidification tower 7 is 0.15-0.55MPa, the bottom temperature of the deacidification tower is 110-155℃, and the top temperature is 45℃. The ammonium bicarbonate and ammonium hydrogen sulfide in the ammonia water decompose and release CO2 and H2S gases, which are discharged from the top of the deacidification tower 7. At the same time, the high-temperature vapor phase medium in the deacidification tower 7 heats the circulating washing water and the heated circulating washing water enters the flash tank 5 for flash evaporation. The secondary steam after flash evaporation The steam is compressed by a steam compressor 4 and heated to 110-155°C before being sent back to the bottom of the deacidification tower 7. After flash evaporation, the residual liquid at the bottom of the flash tank 5 is returned to the upper part of the deacidification tower 7. Preferably, the top of the deacidification tower 7 is continuously supplemented with room-temperature ammonia wastewater to control the top temperature of the deacidification tower not to exceed 45°C. When the liquid level of the flash tank 5 exceeds the set value, a portion of the circulating washing water is sent to the distillation section of the deacidification tower. A steam inlet is reserved at the bottom of the deacidification tower 7. When the heat supply of the deacidification tower 7 is insufficient, an appropriate amount of low-pressure steam is added.

[0027] S3, the deacidified ammonia water enters the ammonia still 8 from the bottom of the deacidification tower 7 for evaporation. The operating pressure of the ammonia still 8 is 0.05-0.15 MPa, the temperature range of the bottom of the ammonia still 8 is 86-115°C, and the temperature range of the top of the tower is 81-110°C. The evaporated steam is sent to the shell side of the reboiler 10 by the steam compressor 11, and the steam saturation temperature is 98-127°C.

[0028] S4. The condensate and non-condensable gas from the shell side of the reboiler 10 are conveyed into the gas-liquid separator 12. The condensate from the shell side of the reboiler 10 is a dilute ammonia solution with an ammonia concentration of 3-5%, and the non-condensable gas is a mixed gas with an ammonia concentration of 25-35%. The gas-liquid separator 12 fully recovers NH3 in the non-condensable gas and liquefies it into condensate. The CO2 and H2S in the non-condensable gas are not absorbed in the gas-liquid separator 12 and enter the deacidification tower 7 from the top of the gas-liquid separator 12 for collaborative treatment. The condensate enters the bottom of the gas-liquid separator 12. At the same time, the wastewater from the bottom of the ammonia distillation tower 8 is heated in the tube side of the reboiler 10, and the wastewater is circulated through the reboiler circulation pump 9.

[0029] S5. The condensate at the bottom of the gas-liquid separator 12 is sent to the second flash tank 13 for flash evaporation to obtain ammonia vapor with an ammonia concentration of 15-30%. The ammonia vapor enters the intermediate tank 16 for condensation and cooling. Specifically, a vacuum pump can be used to condense and cool the ammonia vapor.

[0030] It should be noted that the above embodiments are only specific and clear descriptions of the technical solutions and technical features of the present application. For those skilled in the art, solutions or features that belong to the prior art or common knowledge will not be described in detail in the above embodiments.

[0031] In addition, the technical solutions of the present application are not limited to the above-mentioned embodiments. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A self-circulating ammonia distillation system for excess ammonia water, characterized in that: The invention comprises an ammonia water supply system, a deacidification system, an ammonia evaporation circulation system and an ammonia water generation system which are connected in sequence. The ammonia evaporation circulation system is connected to the ammonia water supply system, and the ammonia water generation system is connected to the deacidification system.

2. The system for self-circulating ammonia distillation of excess ammonia water according to claim 1, characterized in that: The ammonia water supply system comprises a raw ammonia water tank (1), the raw ammonia water tank (1) is connected to an ammonia water-wastewater heat exchanger (3), a raw ammonia water pump (2) is provided between the raw ammonia water tank (1) and the ammonia water-wastewater heat exchanger (3), and the ammonia water-wastewater heat exchanger (3) is respectively connected to a deacidification system and an ammonia distillation circulation system.

3. The self-circulating ammonia distillation system of excess ammonia water according to claim 2, characterized in that: The deacidification system comprises a deacidification tower (7) connected to an ammonia water-wastewater heat exchanger (3); a washing section is provided in a distillation section of the deacidification tower (7); a flash tank (5), a steam compressor (4), and a lower part of the deacidification tower (7) are sequentially connected to the middle part of the deacidification tower (7); the bottom of the flash tank (5) is connected to the top of the deacidification tower (7) via a deacidification tower reflux pump (6); and the bottom of the deacidification tower (7) is connected to an ammonia vaporization circulation system.

4. The self-circulating ammonia distillation system for excess ammonia water according to claim 3, characterized in that: The ammonia evaporation circulation system comprises an ammonia evaporation tower (8) connected to the bottom of the deacidification tower (7); the top of the ammonia evaporation tower (8) is connected in sequence to the second steam compressor (11), the upper part of the reboiler (10) and the lower part of the ammonia evaporation tower (8); the lower part of the ammonia evaporation tower (8) is connected to the ammonia water-wastewater heat exchanger (3); the bottom of the reboiler (10) is connected to the bottom of the ammonia evaporation tower (8); a reboiler circulation pump (9) is provided between the bottom of the reboiler (10) and the bottom of the ammonia evaporation tower (8); the lower part of the reboiler (10) is connected to the ammonia water generation system; and the upper part of the ammonia evaporation tower (8) is connected to the ammonia water generation system.

5. The system for self-circulating ammonia distillation of excess ammonia water according to claim 3, characterized in that: The ammonia water generating system comprises a gas-liquid separator (12), the top of the gas-liquid separator (12) is connected to the upper part of the deacidification tower (7), the lower part of the gas-liquid separator (12) is connected to the reboiler (10), the bottom of the gas-liquid separator (12) is connected to the second flash tank (13), the top of the second flash tank (13) is connected in sequence to a condenser cooler (15) and an intermediate tank (16), the bottom of the second flash tank (13) is connected to an ammonia evaporation tower reflux pump (14), and the ammonia evaporation tower reflux pump (14) is respectively connected to the gas-liquid separator (12) and the upper part of the ammonia evaporation tower (8).

Images