MVR (mechanical vapor recompression) low-energy-consumption steam stripping deamination system

Abstract

The utility model discloses an MVR (Mechanical Vapor Recompression) low-energy-consumption steam stripping deamination system which comprises a deamination front liquid tank, a liquid inlet heat exchanger, a steam stripping deamination tower, a Roots compressor and a reboiler which are connected in sequence, a liquid outlet of the deamination front liquid tank is connected with a tube pass cold side inlet of a liquid inlet heat exchanger, a tube pass hot side outlet of the liquid inlet heat exchanger is connected with a feeding port in the upper portion of a steam stripping deamination tower, and an ammonia-containing steam exhaust port in the top of the steam stripping deamination tower is connected with a Roots compressor. A gas outlet of the Roots compressor is connected with a shell pass hot side inlet of the reboiler, a condensate outlet of the reboiler is connected with the gas-liquid separation tank, outlet water at the bottom of the steam stripping deamination tower is connected with a tube pass cold side inlet of the reboiler through a first water outlet pipe, and a tube pass hot side outlet of the reboiler is connected with the lower part of the steam stripping deamination tower; the system is low in operation energy consumption, small in fresh steam consumption and capable of achieving up-to-standard emission of tail gas and resource recycling of ammonia water.

Description

Technical Field

[0001] The utility model relates to the field of wastewater treatment, in particular to an MVR low-energy consumption steam stripping deammoniation system for one-time standard-reaching treatment of high-ammonia nitrogen wastewater and ammonia water resource utilization. Background Art

[0002] The wastewater discharged from the production processes of industries such as ternary batteries, fine chemicals and non-ferrous hydrometallurgy has a high concentration of ammonia nitrogen. Currently, steam stripping is mainly used for deammoniation, that is, fresh steam is introduced under alkaline conditions and countercurrently contacts the wastewater in the stripping tower, so that the ammonia nitrogen in the wastewater is continuously transferred from the liquid phase to the vapor phase, thereby achieving the purpose of removing ammonia nitrogen from the wastewater. The ammonia-containing vapor at the top of the stripping tower is converted into ammonia water for reuse through condensation and absorption.

[0003] In the traditional steam stripping deamination process, it completely relies on fresh steam from the outside as energy, and the steam consumption is generally more than 150Kg / ton of water. The ammonia-containing steam at the top of the tower requires a large amount of circulating cooling water for cooling, which results in large power loss and high energy consumption of the entire deamination system. Chinese patent CN103408086A discloses an MVR steam stripping deamination system and method thereof. The patent utilizes mechanical steam recompression technology to mechanically compress the steam after stripping deamination to increase the pressure and temperature of the steam, and uses it as a heating heat source for the reboiler at the bottom of the stripping deamination tower, so that only a small amount of compressor starting motor power is consumed during the stripping deamination process, and only a small amount of steam is consumed during the startup process. During normal operation, no additional consumption of stripping steam is required, which reduces the consumption of stripping steam, and effectively solves the problems of high steam consumption and high operating costs encountered in traditional high-ammonia nitrogen wastewater treatment methods, and achieves energy-saving, harmless, reduced, and stabilized treatment. However, this application also has certain defects:

[0004] (1) Using a distillation tower to extract concentrated ammonia water requires consuming heat source again.

[0005] (2) The use of centrifugal steam compressors is prone to high-temperature compressed steam cross-talk. Utility Model Content

[0006] The utility model aims to provide a MVR low energy consumption steam stripping deamination system.

[0007] The innovative purpose of the utility model is that the system has low operating energy consumption, uses less fresh steam, can avoid cross-flow of high-temperature compressed steam, and can achieve standard exhaust gas emission and resource recovery of ammonia water.

[0008] In order to achieve the above utility model purpose, the technical solution of the utility model is:

[0009] A MVR low-energy consumption steam stripping deamination system comprises a pre-deamination liquid tank, a liquid inlet heat exchanger, a steam stripping deamination tower, a Roots compressor and a reboiler which are connected in sequence; the liquid outlet of the pre-deamination liquid tank is connected to the tube side cold side inlet of the liquid inlet heat exchanger, the tube side hot side outlet of the liquid inlet heat exchanger is connected to the feed inlet at the top of the steam stripping deamination tower, the ammonia steam exhaust port at the top of the steam stripping deamination tower is connected to the Roots compressor, the gas outlet of the Roots compressor is connected to the shell side hot side inlet of the reboiler, the condensate outlet of the reboiler is connected to a gas-liquid separation tank, the outlet water at the bottom of the steam stripping deamination tower is connected to the tube side cold side inlet of the reboiler through a first water outlet pipe, the tube side hot side outlet of the reboiler is connected to the lower part of the steam stripping deamination tower; the shell side cold side outlet of the reboiler is connected to an ammonia absorption tower; the bottom of the gas-liquid separation tank is connected to the reflux port at the top of the steam stripping deamination tower through a concentration reflux pipe; the gas outlet at the top of the gas-liquid separation tank is connected to the ammonia absorption tower.

[0010] Furthermore, the outlet water at the bottom of the stripping deamination tower is connected to the shell side hot side inlet of the liquid inlet heat exchanger through a second outlet pipe, and a water outlet pump is arranged on the second outlet pipe.

[0011] Furthermore, a vaporizer is arranged between the exhaust port of ammonia-containing steam at the top of the stripping and deamination tower and the Roots compressor.

[0012] Furthermore, a dilute ammonia water reflux pump is provided on the concentration reflux pipe.

[0013] Furthermore, a pipeline mixer is arranged between the liquid inlet heat exchanger and the stripping deamination tower, the drug inlet pipe of the pipeline mixer is connected to the alkali liquid tank, and an alkali pump is arranged on the drug inlet pipe.

[0014] Furthermore, a reflux pipe is arranged at the bottom of the ammonia absorption tower, the other end of the reflux pipe is connected to the hot side inlet of the condenser tube, the cold side outlet of the condenser tube is connected to the upper part of the ammonia absorption tower, and an absorption circulation pump is arranged on the reflux pipe.

[0015] Furthermore, the cold side outlet of the condenser tube is also connected to an ammonia water storage tank.

[0016] The beneficial effects of the utility model are:

[0017] First: Utilize the combination of Roots compressor and reboiler to directly compress the ammonia-containing steam at the top of the stripping deamination tower. Adopt the heat pump principle to compress the low-temperature ammonia-containing steam into superheated ammonia-containing steam through Roots compressor. The temperature and pressure increase, and the thermal enthalpy increases. Then the steam enters the hot side shell of the reboiler to provide a heat source for the reboiler. The effluent from the stripping deamination tower enters the cold side tube of the reboiler. Under the action of the high-temperature phase change heat source, the effluent from the stripping deamination tower continuously vaporizes to form a heat source and enters the stripping deamination tower, effectively reducing the use of fresh steam. As the gas continues to evaporate, the effluent from the stripping deamination tower entering the reboiler is automatically replenished and circulated. The use of Roots compressor can avoid cross-gas of high-temperature compressed steam and ensure stable operation of the system.

[0018] Second: the moisture content of the ammonia-containing steam at the top of the stripping deamination tower is reduced. Before the ammonia-containing steam enters the Roots compressor, it is vaporized by spraying process water in the vaporizer to increase the latent heat of the ammonia-containing steam.

[0019] Third: The condensate in the reboiler enters the gas-liquid separation tank, and the dilute ammonia water at the bottom of the gas-liquid separation tank is refluxed to the stripping deamination tower through a reflux pump. On the one hand, it adjusts the ammonia concentration of the exhaust gas at the top of the stripping deamination tower to ensure the stability of the ammonia vapor concentration, and on the other hand, it can concentrate the dilute ammonia water.

[0020] Fourth: The ammonia absorption tower is connected to the circulation pump to circulate and absorb ammonia to ensure that the exhaust gas meets the emission standards or is connected to the subsequent exhaust gas purification device. The low-concentration ammonia absorption liquid can flow back to the liquid tank before deammoniation to achieve cyclic treatment and ammonia water resource recovery.

[0021] Fifth: The overall process of this system is simple, the operation is simple, the energy consumption is low, the operation is stable, the effluent ammonia nitrogen meets the national emission standards at one time, and the recovered ammonia water is of high quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the utility model. In the figure: 1 is the pre-deammoniation liquid tank, 2 is the liquid inlet heat exchanger, 3 is the stripping deammonification tower, 3.1 is the feed port, 3.2 is the steam inlet, 3.3 is the first water outlet pipe, 3.4 is the second water outlet pipe, 3.5 is the exhaust port for ammonia-containing steam, 3.6 is the reflux port, 4 is the Roots compressor, 5 is the reboiler, 5.1 is the shell side hot side inlet of the reboiler, 5.2 is the condensate outlet of the reboiler, 5.3 is the tube side cold side inlet of the reboiler, 5.4 is the tube side hot side outlet of the reboiler, 5.5 is the shell side cold side outlet of the reboiler, 6 is the gas-liquid separation tank, 6.1 is the concentration reflux pipe, 7 is the ammonia absorption tower, 8 is the water outlet pump, 9 is the vaporizer, 10 is the dilute ammonia reflux pump, 11 is the pipeline mixer, 12 is the alkali liquid tank, 13 is the alkali adding pump, 14 is the condenser, 15 is the absorption circulation pump, and 16 is the ammonia storage tank. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present utility model will be described clearly and completely below in conjunction with the accompanying drawings.

[0024] An MVR low-energy consumption steam stripping deamination system comprises a pre-deamination liquid tank 1, a liquid inlet heat exchanger 2, a steam stripping deamination tower 3, a Roots compressor 4 and a reboiler 5 which are connected in sequence; the liquid outlet of the pre-deamination liquid tank 1 is connected to the cold side inlet of the tube side of the liquid inlet heat exchanger 2, the hot side outlet of the tube side of the liquid inlet heat exchanger 2 is connected to the feed port 3.1 at the top of the steam stripping deamination tower 3, fresh steam enters the steam stripping deamination tower 3 from the steam inlet 3.2 at the bottom of the steam stripping deamination tower 3, the steam contacts the ammonia-containing wastewater in countercurrent, flows into the lower layers of the tower plates step by step from top to bottom, and after the step-by-step vapor-liquid equilibrium, the ammonia nitrogen in the water reaching the bottom of the steam stripping deamination tower 3 is removed to meet the emission standard; the ammonia-containing wastewater at the top of the steam stripping deamination tower 3 is discharged from the steam inlet 3.2 at the bottom of the steam stripping deamination tower 3, and the steam is discharged from the steam stripping deamination tower 3 to the steam stripping deamination tower 3. The steam exhaust port 3.5 is connected to the Roots compressor 4, the gas outlet of the Roots compressor 4 is connected to the shell side hot side inlet 5.1 of the reboiler, the condensate outlet 5.2 of the reboiler is connected to the gas-liquid separation tank 6, the water outlet at the bottom of the stripping deamination tower 3 is connected to the tube side cold side inlet 5.3 of the reboiler through the first water outlet pipe 3.3, and the tube side hot side outlet 5.4 of the reboiler is connected to the lower part of the stripping deamination tower 3; the shell side cold side outlet 5.5 of the reboiler is connected to the ammonia absorption tower 7; the bottom of the gas-liquid separation tank 7 is connected to the reflux port 3.6 on the upper part of the stripping deamination tower 3 through the concentration reflux pipe 6.1; the gas outlet at the top of the gas-liquid separation tank 6 is connected to the ammonia absorption tower 7.

[0025] Furthermore, the ammonia-containing steam passes through the Roots compressor 4, and adopts the heat pump principle to compress the low-temperature ammonia-containing steam into superheated ammonia-containing steam through the Roots compressor 4, with the temperature and pressure increased and the thermal enthalpy increased, and then enters the hot side of the shell side of the reboiler 5 to provide a heat source for the reboiler 5, and the outlet water of the stripping deamination tower 3 enters the cold side of the tube side of the reboiler 5. Under the action of the high-temperature phase change heat source, the outlet water of the stripping deamination tower 3 is continuously vaporized to form a heat source and enters the stripping deamination tower 3, thereby effectively reducing the use of fresh steam. As the gas continues to volatilize, the outlet water of the stripping deamination tower 3 entering the reboiler 5 is automatically replenished and circulated.

[0026] Furthermore, the Roots compressor 4 and the reboiler 5 are connected to a controller, and the compression ratio of the Roots compressor 4 and the area of ​​the reboiler 5 can be intelligently matched and adapted to prevent cross-flow of high-temperature compressed steam and achieve efficient and stable operation; the controller is prior art and will not be described in detail here.

[0027] Furthermore, the outlet water at the bottom of the stripping deamination tower 3 is connected to the hot side inlet of the liquid inlet heat exchanger 2 through a second outlet water pipe 3.4. A water outlet pump 8 is arranged on the second outlet water pipe 3. The outlet water at the bottom of the stripping deamination tower 3 is used to preheat the ammonia-containing wastewater in the liquid inlet heat exchanger 2, thereby realizing the reuse of waste heat and saving energy.

[0028] Furthermore, a vaporizer 9 is arranged between the exhaust port 3.5 of the ammonia-containing steam at the top of the stripping deamination tower 3 and the Roots compressor 4, so that the moisture content of the ammonia-containing steam at the top of the stripping deamination tower 3 is reduced. Before the ammonia-containing steam enters the Roots compressor 4, the vaporizer 9 is used to spray process water for vaporization, thereby increasing the latent heat of the ammonia-containing steam.

[0029] Furthermore, a dilute ammonia water reflux pump 10 is provided on the concentration reflux pipe 6.1; the reflux structure can adjust the ammonia concentration of the top exhaust gas of the stripping deammonification tower 3 to ensure the stability of the ammonia-containing steam concentration, and can also concentrate the dilute ammonia water.

[0030] Furthermore, a pipeline mixer 11 is arranged between the liquid inlet heat exchanger 2 and the stripping deamination tower 3 , the drug inlet pipe of the pipeline mixer 11 is connected to the alkali liquid tank 12 , and an alkali pump 13 is arranged on the drug inlet pipe.

[0031] Furthermore, a reflux pipe is provided at the bottom of the ammonia absorption tower 7, the other end of the reflux pipe is connected to the hot side inlet of the condenser 14, the hot side outlet of the condenser 14 is connected to the upper part of the ammonia absorption tower 7, and an absorption circulation pump 15 is provided on the reflux pipe.

[0032] Furthermore, the hot side outlet of the condenser 14 is also connected to the ammonia water storage tank 16 .

[0033] Furthermore, the uncondensed ammonia-containing gas in the reboiler 5 and the gas-liquid separation tank 6 enters the air inlet of the ammonia absorption tower 7, passes through the absorption circulation pump 15 on the reflux pipe, is first cooled by the cooler 14, and then enters the upper part of the ammonia absorption tower 7 for circulation absorption. After the ammonia concentration in the ammonia absorption tower 7 reaches the requirement, it is discharged into the ammonia storage tank 16; the remaining ammonia after the circulation absorption in the ammonia absorption tower 7 is absorbed by spraying process water to ensure that the exhaust gas meets the emission standards or goes to the subsequent exhaust gas purification device, and the low-concentration ammonia absorption liquid can be returned to the liquid tank 1 before deammonification to achieve standard emission and resource recovery of ammonia water.

[0034] The described embodiments are only some embodiments of the utility model, not all embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

Claims

1. A MVR low energy consumption steam stripping deamination system, characterized by: The invention comprises a pre-deamination liquid tank (1), a liquid inlet heat exchanger (2), a stripping deamination tower (3), a Roots compressor (4) and a reboiler (5) which are connected in sequence; the liquid outlet of the pre-deamination liquid tank (1) is connected to the cold side inlet of the tube side of the liquid inlet heat exchanger (2), the hot side outlet of the tube side of the liquid inlet heat exchanger (2) is connected to the feed inlet (3.1) at the top of the stripping deamination tower (3), the ammonia-containing steam exhaust port (3.5) at the top of the stripping deamination tower (3) is connected to the Roots compressor (4), the gas outlet of the Roots compressor (4) is connected to the shell side hot side inlet (5.1) of the reboiler, and the condenser (5.1) of the reboiler is connected to the hot side inlet (5.2) of the reboiler. The liquid outlet (5.2) is connected to the gas-liquid separation tank (6); the water outlet at the bottom of the stripping deamination tower (3) is connected to the tube side cold side inlet (5.3) of the reboiler through the first water outlet pipe (3.3); the tube side hot side outlet (5.4) of the reboiler is connected to the lower part of the stripping deamination tower (3); the shell side cold side outlet (5.5) of the reboiler is connected to the ammonia absorption tower (7); the bottom of the gas-liquid separation tank (6) is connected to the reflux port (3.6) at the upper part of the stripping deamination tower (3) through the concentration reflux pipe (6.1); the gas outlet at the top of the gas-liquid separation tank (6) is connected to the ammonia absorption tower (7).

2. The MVR low energy consumption steam stripping deamination system according to claim 1, characterized in that: The water outlet at the bottom of the stripping deamination tower (3) is connected to the shell side hot side inlet of the liquid inlet heat exchanger (2) through a second water outlet pipe (3.4), and a water outlet pump (8) is provided on the second water outlet pipe (3.4).

3. The MVR low energy consumption steam stripping deamination system according to claim 1, characterized in that: A vaporizer (9) is also provided between the exhaust port (3.5) for ammonia-containing steam at the top of the stripping and deammonification tower (3) and the Roots compressor (4).

4. The MVR low energy consumption steam stripping deamination system according to claim 1, characterized in that: The concentration reflux pipe (6.1) is provided with a dilute ammonia water reflux pump (10).

5. The MVR low energy consumption steam stripping deamination system according to claim 1, characterized in that: A pipeline mixer (11) is further arranged between the liquid inlet heat exchanger (2) and the stripping deamination tower (3); a drug inlet pipe of the pipeline mixer (11) is connected to an alkali liquid tank (12); and an alkali pump (13) is arranged on the drug inlet pipe.

6. The MVR low energy consumption steam stripping deamination system according to claim 1, characterized in that: A reflux pipe is provided at the bottom of the ammonia absorption tower (7), the other end of the reflux pipe is connected to the hot side inlet of the condenser (14) tube side, the cold side outlet of the condenser (14) tube side is connected to the upper part of the ammonia absorption tower (7), and an absorption circulation pump (15) is provided on the reflux pipe.

7. The MVR low energy consumption steam stripping deamination system according to claim 6, characterized in that: The cold side outlet of the tube side of the condenser (14) is also connected to the ammonia water storage tank (16).

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