Process for recycling ammonia water by internal coupling energy-saving atomization for high-concentration ammonia-nitrogen wastewater

Abstract

The application discloses an internal coupling energy-saving atomization ammonia water recovery process for high-concentration ammonia-nitrogen wastewater, and particularly relates to the technical field of wastewater treatment. The process comprises the following steps: ammonia gas and water vapor mixed gas generated after high-concentration ammonia-nitrogen wastewater is subjected to rectification in a deamination tower is introduced into an absorption-condensation integrated ammonia recovery device through a pipeline; an internal coupling energy-saving atomization energy-saving device of the integrated ammonia recovery device can generate superfine water mist; ammonia-containing steam is combined with the superfine water mist to rapidly exchange heat, so that the water vapor is liquefied into liquid water; meanwhile, due to the characteristic that ammonia is extremely easy to dissolve in water, ammonia gas molecules can be combined with the liquefied water vapor molecules and rapidly release the heat of dissolution to form ammonia water. The process has the advantages of simple process flow, less equipment investment and land occupation, saving of multistage absorption towers and a large amount of absorbents, one-step recovery of ammonia water, high purity and controllable concentration of the ammonia water, high purity of the ammonia water, almost no non-condensed gas generation, and steam energy consumption in the ammonia removal process of the high-concentration ammonia-nitrogen wastewater can be saved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an internally coupled energy-saving atomization process for recovering ammonia from high-concentration ammonia nitrogen wastewater. Background Technology

[0002] Industries such as non-ferrous metallurgy, ternary cathode materials, tungsten-molybdenum, and rare earth often generate wastewater containing high concentrations of ammonia nitrogen during production. Currently, those skilled in the art generally use ammonia removal towers to evaporate the ammonia nitrogen in the wastewater as ammonia gas through distillation, thus achieving compliant wastewater discharge. The specific process involves: the ammonia nitrogen wastewater to be treated first exchanging heat with the high-temperature effluent from the bottom of the ammonia removal tower before entering the tower, with fresh steam directly introduced; or using a reboiler to indirectly heat part of the circulating bottom effluent, thus distilling and removing ammonia from the high-concentration ammonia nitrogen wastewater. The heat source for the reboiler is generally steam. The ammonia gas evaporated from the top of the distillation tower is generally recovered as ammonia water of a certain concentration through multi-stage absorption towers or condensers for indirect cooling.

[0003] When the ammonia nitrogen concentration in wastewater is below 10 g / L, the ammonia gas at the top of the distillation column is easily condensed and absorbed during the rectification process, and the steam consumption per ton of water can be controlled below 120 kg. However, when the ammonia nitrogen concentration in wastewater is above 10 g / L, the excessive amount of ammonia gas at the top of the column during distillation often prevents timely and effective condensation and absorption, resulting in severe ammonia leakage, air pollution, and increased costs for secondary waste gas treatment. To reduce ammonia leakage, conventional techniques involve introducing a large amount of steam to distill water from the bottom to the top of the column (steam consumption per ton of water exceeds 180 kg and increases with increasing ammonia nitrogen concentration), followed by cooling with a large amount of circulating cooling water to absorb the ammonia gas into ammonia water. Alternatively, a multi-stage absorption tower can be used to spray and absorb the ammonia gas at the top. However, this process is not only cumbersome in terms of equipment and procedures, but also requires a large amount of absorbent and yields a low concentration of recovered ammonia water. Currently, the treatment of high-concentration ammonia nitrogen wastewater is hampered by problems such as high steam consumption, high circulating water consumption, large waste gas emissions, low ammonia concentration, high overall energy consumption, high cost, and high carbon emissions, which are urgent issues that need to be addressed.

[0004] CN 103641193A (An Energy-Saving Ammonia Distillation Technology) proposes an energy-saving production method for ammonia distillation. This method involves sequentially exchanging heat between the high-temperature wastewater generated during distillation and the raw ammonia water, as well as the ammonia vapor produced during rectification, to generate secondary steam. This secondary steam is then compressed again by a compressor to produce high-temperature, high-pressure steam, which is used as a heat source for the rectification column. However, this technology has several problems: 1. It only replaces a portion of the fresh steam with regenerated steam for recycling, failing to fundamentally solve the problem of high overall steam consumption during wastewater treatment; 2. The compressor consumes a large amount of electricity to provide the circulating steam, failing to guarantee a reduction in overall energy consumption, and the overall investment and land area are large; 3. The concentration of ammonia water recovered by this technology is only 10%, resulting in low economic efficiency; 4. The addition of equipment such as compressors leads to high investment.

[0005] CN104891726B (Treatment System for High-Concentration Ammonia Nitrogen Wastewater) proposes a concentration and energy-saving device. This device first uses a heat exchanger to recover heat energy from the column bottom, increasing the temperature of the ammonia nitrogen wastewater entering the concentration tank (i.e., the concentration unit). Then, the concentration and energy-saving device mixes the wastewater entering the column with ammonia-containing vapor from the top of the column, further increasing its temperature and ammonia concentration. However, this technology has the following problems: 1. It requires a large concentration tank, and the expansion of water volume after passing through the tank increases the system's processing load. 2. The ammonia-containing vapor from the top of the column enters the concentration tank for heat exchange and then re-enters the distillation column, causing the ammonia concentration at the top of the column to fluctuate constantly. The pressure in the concentration tank and at the top of the column is also difficult to control stably, resulting in fluctuating concentrations of the recovered ammonia water. 3. The ammonia-containing vapor cannot be condensed and recovered into ammonia water in one step. Instead, some of the uncondensable ammonia-containing vapor enters the concentration tank from the top of the column and then re-enters the column. Ammonia is prone to leakage throughout the process, leading to waste of ammonia resources and air pollution.

[0006] CN103833093A proposes an energy-saving and environmentally friendly device and process for producing concentrated ammonia water. In this technology, the ammonia water formed by cooling the ammonia vapor after ammonia stripping enters a reflux tank. Non-condensable vapors in the reflux tank are cooled and then enter a spray circulating water tank. Part of the ammonia vapors in the non-condensable vapors dissolve in the circulating liquid. The non-condensable vapor tail gas enters a gas pipeline, and the resulting finished ammonia water is refluxed, while the remaining finished ammonia water is sent externally. However, this technology has a relatively complex process route and cannot achieve one-step condensation and recovery of ammonia water. Furthermore, this technology changes the conventional ammonia stripping tower from atmospheric pressure operation to negative pressure operation, significantly increasing the manufacturing and maintenance costs of the equipment, as well as the complexity of the production operation.

[0007] None of the above technologies can effectively and cost-effectively solve the problems of high steam energy consumption, high circulating water consumption, ammonia leakage, and high carbon emissions in the treatment of high-concentration ammonia nitrogen wastewater. Summary of the Invention

[0008] To address these issues, this invention provides an internally coupled, energy-saving atomization process for recovering ammonia from high-concentration ammonia nitrogen wastewater.

[0009] This invention addresses the issue of excessive energy consumption in the ammonia nitrogen recovery process from high-concentration ammonia nitrogen wastewater. An analysis reveals that the high steam consumption and significant ammonia escape from the top of the distillation column are due to the large amount of ammonia at the top. If steam is not introduced in excess, the ratio of ammonia to water at the top of the column becomes mismatched, resulting in a large amount of ammonia gas remaining undissolved and unabsorbed. Furthermore, the excessive amount of ammonia and steam at the top prevents timely and sufficient condensation of the high-temperature gas through indirect heat exchange with circulating water, leading to the escape of uncondensed ammonia gas and air pollution. Based on this analysis, this invention proposes a simple, easy-to-implement, energy-saving, environmentally friendly, and efficient process. This process significantly reduces steam and circulating water consumption during the ammonia nitrogen wastewater distillation process, reduces carbon emissions, lowers ammonia tail gas emissions, and efficiently recovers high-purity concentrated ammonia water in one step. It is characterized by its energy-saving, environmentally friendly, and efficient nature. Moreover, its simple process flow, low equipment investment cost, and stable operation make it easy for enterprises to promote and apply, facilitating energy-saving retrofits of existing facilities.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] According to the present invention, an internally coupled energy-saving atomization process for recovering ammonia water from high-concentration ammonia nitrogen wastewater includes:

[0012] Step 1: The ammonia gas and water vapor mixture generated after the high-concentration ammonia nitrogen wastewater is distilled in the ammonia removal tower enters the absorption-condensation integrated ammonia recovery unit through a pipeline, preferably the shell side and / or the tube side.

[0013] Step 2: The energy-saving atomizing device is internally coupled to the absorption-condensation integrated ammonia recovery unit or the inlet pipe. The internally coupled energy-saving atomizing device absorbs and condenses the ammonia in the absorption-condensation integrated ammonia recovery unit or the inlet pipe to generate a continuous ultra-fine water mist, forming small droplets with ultra-high specific surface area, which greatly increases the contact area between ammonia and water.

[0014] Step 3: After the ammonia vapor combines with the ultrafine water mist in the pipeline or integrated ammonia recovery unit, it quickly exchanges heat, causing the water vapor to liquefy into liquid water. At the same time, because ammonia is extremely soluble in water, ammonia gas molecules combine with the liquefied water vapor molecules and quickly release their heat of solution to form ammonia water.

[0015] Step four: The released heat of dissolution, along with some uncondensed water vapor and ammonia, enters the ammonia recovery unit. Since the partial pressure of ammonia and water vapor has been reduced, the remaining heat is indirectly exchanged through continuously flowing circulating cooling water, further increasing the dissolution rate and cooling rate of ammonia. Finally, high-purity concentrated ammonia water is formed and discharged from the condenser.

[0016] Furthermore, the process is accomplished through an internally coupled energy-saving atomization ammonia recovery device for high-concentration ammonia nitrogen wastewater.

[0017] Furthermore, the device includes an ammonia vapor pipeline, an integrated absorption-condensation ammonia recovery unit, an internally coupled energy-saving atomizing device, an automatic flow regulating valve, a water source booster pump, a water source tank, and a water source switch valve;

[0018] One end of the ammonia-containing steam pipeline is connected to the ammonia removal tower or other equipment / pipelines that generate ammonia-containing waste gas, and the other end is directly connected to the absorption-condensation integrated ammonia recovery unit or connected to the absorption-condensation integrated ammonia recovery unit after passing through an energy-saving atomization device.

[0019] The absorption-condensation integrated ammonia recovery unit is a horizontal shell-and-tube heat exchanger connected to the ammonia-containing vapor pipeline at the top of the ammonia removal tower. It is used to receive and exchange heat with the ammonia gas and water vapor that are heated and evaporated in the ammonia removal tower. The tube side medium is circulating cooling water, and the shell side medium is ammonia-containing vapor at the top of the tower.

[0020] A water source booster pump is connected to a water source buffer tank to supply water to the internally coupled energy-saving atomizing device. The water source for this buffer tank can come from various sources, including but not limited to pure water, or be connected to the outlet ammonia water pipeline or ammonia water tank of the integrated ammonia recoverer, or be connected to the outlet water of the deammoniation tower, or be connected to the condensate of the deammoniation tower reboiler, etc. The water source buffer tank is set with a water buffer capacity of 0.5~1h to provide a stable water flow.

[0021] The automatic flow regulating valve can automatically interlock and control the total water flow based on the temperature at the top of the tower and the concentration of ammonia water.

[0022] The water source switch valve can be opened to use this water source or closed to use other water sources, depending on the water source.

[0023] Furthermore, the internally coupled energy-saving atomizing device includes a spiral nozzle (containing an absorbent inlet, an absorbent outlet, and a guide spiral) and an atomization control section. The spiral nozzle is part of the atomizing device assembly and can be a commercially available product. Atomization control is part of the process described in this invention.

[0024] Furthermore, the atomization control section may include a water inlet, which is used to receive the absorbent to be atomized. The atomization control includes designs such as the distribution and arrangement of atomizers, the automatic interlock between the atomized water flow rate and the ammonia concentration, and the automatic interlock between the number of atomizers activated and the ammonia concentration. In actual production, the corresponding equipment design and automatic control design can be carried out according to the process requirements. That is to say, the atomization control process includes distributing and arranging atomizers according to requirements during the equipment design stage, and controlling the number of atomizers activated and adjusting the absorbent flow rate during the engineering operation stage.

[0025] Furthermore, the non-powered atomizing device is used to form atomized droplets from the absorbent introduced into the atomizing device without consuming any electrical energy or other power.

[0026] Furthermore, the atomizing device offers multiple selectable flow rates and angles. The atomizing guide spiral is located on the atomizing device, and the atomizing droplet guide spiral is a hollow / solid cone shape. The angle at which the absorbent is sprayed can be selected from 60° to 170° depending on the shape and length of the guide spiral, so as to uniformly and efficiently disperse the atomized droplets from the atomizing device into the pipeline or ammonia recovery unit housing according to different operating conditions; ensuring that the gas entering the ammonia recovery unit fully contacts the atomized droplets and is converted into ammonia water droplets.

[0027] This energy-saving atomizing device features adjustable angle (60°~170°), adjustable flow rate, non-clogging structural design, large flow diameter, simplified structure, and compact size. It can be connected to the ammonia recovery unit via threads or flanges, and can be coupled in the pipeline or shell side. It does not consume any form of power such as electricity or steam, but can form high-density, large-specific-area atomized droplets, ensuring that the gas entering the ammonia recovery unit is fully contacted with the atomized droplets and transformed into ammonia water droplets.

[0028] Furthermore, the absorbent can be selected from different absorbents such as pure water or dilute ammonia water, reboiler condensate, tower bottom water, and acid solution, depending on the operating conditions.

[0029] The present invention has the following advantages:

[0030] 1) This invention effectively solves the problem of high steam and circulating water consumption when recovering ammonia water from high-concentration ammonia nitrogen wastewater. When the ammonia nitrogen concentration is too high, there is a mismatch between the ammonia gas and water vapor ratio at the top of the tower. To ensure sufficient condensation and absorption of ammonia, a large amount of steam needs to be evaporated to the top of the tower as an absorbent. The pure water atomization energy-saving device provides water that can condense ammonia gas from high-concentration ammonia nitrogen wastewater into ammonia water, supplementing the required water volume. Therefore, it replaces a portion of the steam consumption, reducing the overall energy consumption, operating costs, and carbon emissions of the entire device. Simultaneously, the water source can be matched according to the diverse processes, indirectly achieving wastewater reduction.

[0031] 2) By setting up an energy-saving atomization device, the present invention can recover ammonia to a greater extent, while saving steam and achieving energy-saving effect by adding an energy-saving atomization device.

[0032] 3) The introduction of the water absorbent in this invention reduces the partial pressure of ammonia and water vapor entering the heat exchanger. This allows a portion of the heat that would otherwise require a large amount of circulating water to be directly replaced by a very small amount of water absorbent, thus reducing the overall cooling load and saving circulating water. Simultaneously, the reduced heat exchange area saves the required heat exchange area in the integrated absorption-condensation ammonia recovery unit, lowering equipment investment and floor space requirements.

[0033] 4) The process of this invention is simple, requires little equipment investment and land area, and can save the need for multi-stage absorption towers and a large amount of absorbent to recover ammonia water in one step. Moreover, the ammonia water has high purity and controllable concentration. The ammonia water has high purity and almost no non-condensable gas is generated, thus avoiding the waste of ammonia resources and air pollution.

[0034] 5) This invention has a high degree of automation, stable and controllable process, low difficulty of modification, and facilitates enterprises to carry out energy-saving retrofits on existing equipment. Attached Figure Description

[0035] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0036] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0037] Figure 1 This is a schematic diagram of an internally coupled energy-saving atomization ammonia water recovery device for high-concentration ammonia nitrogen wastewater provided in Embodiment 1 of the present invention;

[0038] Figure 2 A diagram of the atomizing device provided in Embodiment 1 of the present invention;

[0039] Figure 3 This is a schematic diagram of the nozzle provided in Embodiment 1 of the present invention;

[0040] Figure 4 This is a diagram of an internally coupled energy-saving atomization ammonia water recovery device for high-concentration ammonia nitrogen wastewater provided in Embodiment 1 of the present invention;

[0041] Figure 5 This is a diagram of an internally coupled energy-saving atomization ammonia water recovery device for high-concentration ammonia nitrogen wastewater provided in Embodiment 2 of the present invention;

[0042] Figure 6 This is a diagram of an internally coupled energy-saving atomization ammonia water recovery device for high-concentration ammonia nitrogen wastewater provided in Embodiment 3 of the present invention;

[0043] In the diagram: 1-Ammonia removal tower, 2-Ammonia-containing steam pipeline, 3-Integrated absorption-condensation ammonia recovery unit, 4-Internal coupling energy-saving atomization device, 5-Automatic flow regulating valve, 6-Water source buffer tank, 7-Water source booster pump, 8-Reboiler, 9-Feed preheater, 10-Outlet water heat exchanger, 11-Ammonia water tank, 12-Ammonia water pipeline, 13-First switch valve, 14-Second switch valve, 15-Third switch valve, 16-Atomization control, 17-Ammonia water concentration indicator.

[0044] 18-Helical nozzle, 18-1-Absorbent inlet, 18-2-Absorbent outlet, 18-3-Guide spiral, 18-4-Spray mist angle;

[0045] 19 - Second automatic flow regulating valve; 20 - Third automatic flow regulating valve; 21 - Fourth automatic flow regulating valve. Detailed Implementation

[0046] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1

[0048] This embodiment provides an internally coupled energy-saving atomization ammonia water recovery device and process for high-concentration ammonia nitrogen wastewater:

[0049] Devices such as Figure 1 As shown, it includes an ammonia vapor pipeline 2, an absorption-condensation integrated ammonia recovery unit 3, an internally coupled energy-saving atomizing device 4, an automatic flow regulating valve 5, a water source booster pump 7, a water source buffer tank 6, a third switch valve 15, an atomization control 16, and an ammonia concentration indicator 17.

[0050] One end of the ammonia-containing steam pipeline 2 is connected to the ammonia removal tower or other equipment that generates ammonia-containing waste gas, and the other end is connected to the absorption-condensation integrated ammonia recovery unit 3.

[0051] The integrated absorption-condensation ammonia recovery unit 3 is a horizontal shell-and-tube heat exchanger connected to the top pipe of the ammonia removal tower. It is used to receive and exchange heat with the ammonia gas and water vapor evaporated by heating in the ammonia removal tower. The tube-side medium is circulating cooling water, and the shell-side medium is ammonia vapor from the top of the tower. The ammonia water in the integrated absorption-condensation ammonia recovery unit 3 is collected after the ammonia water concentration indicator 17 indicates high-purity concentrated ammonia water of 15% or higher.

[0052] The internally coupled energy-saving atomizing device 4 is equipped with an atomizing device, such as... Figure 2 As shown, the device includes a spiral nozzle 18 and a second automatic flow regulating valve 19. The spiral nozzle 18 injects absorbent, and the second automatic flow regulating valve 19 regulates the amount of absorbent injected. A schematic diagram of the spiral nozzle 18 is shown below. Figure 3 As shown, it includes: an absorbent inlet 18-1, an absorbent outlet 18-2, a guide spiral 18-3, and a spray mist angle 18-4. The guide spiral 18-3 is used to control the angle of spray formation. The absorbent inlet 18-1 is used to connect to the absorbent pipeline. The absorbent outlet 18-2 is used to spray out the absorbent input from the absorbent pipeline and form a spray under the action of the guide spiral 18-3. The spray mist angle 18-4 is the angle formed by the absorbent spraying out under the action of the guide spiral 18-3.

[0053] Preferably, multiple spiral nozzles and multiple automatic flow regulating valves can also be installed, such as Figure 2 The third automatic flow regulating valve 20, the fourth automatic flow regulating valve 21, etc. shown are equipped with different automatic flow regulating valves according to requirements, and their functions are the same as those of the second automatic flow regulating valve 19.

[0054] Specifically, the atomization control 16 may include a water inlet, which receives the absorbent to be atomized; the water inlet receives pure water (or dilute ammonia or other absorbents) to be atomized. The atomization control includes: during the design phase, distributing one or more atomizers according to process requirements to control the number and arrangement of atomizers; and during the engineering operation phase, adjusting the number and opening degree of nozzles. A non-powered atomization device is used to form atomized droplets from the pure water (or dilute ammonia or other absorbents) introduced into the atomization device without consuming any electrical energy or other power. The atomized droplet guide spiral is conical to uniformly and efficiently disperse the atomized droplets from the atomizer into the ammonia recovery unit housing. This pure water atomizing device features adjustable angle (stepless adjustment from 60° to 170°), adjustable flow rate, non-clogging structural design, large nozzle diameter, simplified structure, and compact size. It can be connected to the ammonia recovery unit via threads or flanges, and can be coupled within the pipeline or shell side. It can form high-density, large-specific-area atomized droplets without consuming any power, ensuring that the gas entering the ammonia recovery unit fully contacts the atomized droplets and is converted into ammonia water droplets.

[0055] The third switching valve 15 is a switching valve that can be opened or closed according to process requirements, and is used to provide the water source required by the energy-saving atomizing device.

[0056] like Figure 4As shown, the water source booster pump 7 is connected to the water source buffer tank 6 to supply pure water to the internally coupled energy-saving atomizing device 4. It can also be connected to the ammonia water tank 11 for storing products or to the ammonia water pipeline 12 of the tower top condenser outlet pipeline to supply dilute ammonia water as an absorbent to the internally coupled energy-saving atomizing device 4. A first switch valve 13 and a second switch valve 14 are respectively provided on the ammonia water tank 11 outlet connection pipeline and the tower top condenser outlet pipeline 12 to control the opening and closing of the pipeline.

[0057] The water buffer tank 6 is set with a water buffer capacity of 0.5 to 1 hour to provide a stable water flow.

[0058] The automatic flow regulating valve 5 can be automatically interlocked and controlled according to the temperature at the top of the tower and the ammonia concentration to coarsely regulate the flow rate of pure water or dilute ammonia. More precise regulation is achieved through automatic control between the internally coupled energy-saving atomizing device 4 and the ammonia concentration indicator 17. Specifically, based on the ammonia concentration indicated by the ammonia concentration indicator 17, when the ammonia concentration is less than the required 15%, the flow regulating valve in the internally coupled energy-saving atomizing device 4 is adjusted to its minimum value through the automatic control program connected to the atomization control 16. This continues until the ammonia concentration indicated by the ammonia concentration indicator 17 reaches 15% or higher. Then, through the automatic control program connected to the atomization control 16, the opening of the flow regulating valve of one nozzle in the internally coupled energy-saving atomizing device 4 is gradually increased. If the ammonia concentration indicated by the ammonia concentration indicator 17 still exceeds 15%, the number and opening degree of the flow regulating valves of the other nozzles in the internally coupled energy-saving atomizing device 4 are increased through the automatic control program, thereby regulating the ammonia concentration by controlling the injection flow rate of the absorbent.

[0059] The first switching valve 13, the second switching valve 14, and the third switching valve 15 are all switching valves, which can be selected to open or close according to process requirements, and are used to switch the water source required by the energy-saving atomizing device. Process: The ammonia gas and water vapor mixture generated after the high-concentration ammonia nitrogen wastewater is distilled by the deammoniation tower enters the absorption-condensation integrated ammonia recovery unit 3 through the ammonia vapor pipeline 2. The internally coupled energy-saving atomizing device 4 generates continuous small droplets with ultra-high specific surface area in the shell side (or inlet) of the absorption-condensation integrated ammonia recovery unit 3, which greatly increases the contact area between ammonia gas and water, and improves the mass transfer efficiency during condensation and absorption. When ammonia vapor combines with this ultrafine water mist, it rapidly exchanges heat, causing the water vapor to liquefy into liquid water. At the same time, because ammonia is highly soluble in water, ammonia gas molecules can combine with liquefied water vapor molecules and rapidly release their heat of solution to form ammonia water. The released heat of solution, along with some uncondensed water vapor and ammonia, enters the ammonia recovery unit. Since the partial pressure of ammonia and water vapor has been reduced, the remaining heat is indirectly exchanged through continuously flowing circulating cooling water, further increasing the dissolution rate and cooling rate of ammonia gas. Finally, high-purity concentrated ammonia water is formed and discharged from the condenser.

[0060] Example 2

[0061] This embodiment provides an internally coupled energy-saving atomization ammonia water recovery device and process for high-concentration ammonia nitrogen wastewater:

[0062] Devices such as Figure 5 As shown, it includes an ammonia removal tower 1, an ammonia-containing steam pipeline 2, an integrated absorption-condensation ammonia recovery unit 3, an internally coupled energy-saving atomizing device 4, an automatic flow regulating valve 5, a water source buffer tank 6, a water source booster pump 7, and a reboiler 8.

[0063] Other connection methods are the same as in Example 1, except that the waste ammonia gas in the ammonia-containing steam pipeline 2 comes from the ammonia removal tower 1, the water source buffer tank 6 is connected to the reboiler 8, and the reboiler 8 is connected to the ammonia removal tower 1.

[0064] Process: Ammonia removal unit for high-concentration ammonia nitrogen wastewater currently has an influent ammonia nitrogen concentration as high as 60 g / L, a steam consumption of 380 kg / m³ per ton of water, and a strong ammonia odor in the removal tower. The ammonia water recovered by the ammonia system differs from the theoretical recovery volume by approximately 600-1000 tons / year. Based on the production process, the reason for the large difference between the actual recovered ammonia water volume and the theoretical calculation, as well as the strong ammonia odor on site, is that unabsorbed and uncondensed ammonia gas at the top of the tower is wasted as waste gas during the removal process, resulting in a recovered ammonia water concentration of less than 10% and serious ammonia leakage.

[0065] To improve the energy efficiency and environmental friendliness of the ammonia removal system, an internally coupled energy-saving atomizing device 4 was added at the connection between the ammonia-containing vapor pipeline 2 at the top of the ammonia removal tower 1 and the integrated absorption-condensation ammonia recovery unit 3. An automatic flow regulating valve 5 was also installed. Pure water was supplied to the internally coupled energy-saving atomizing device 4 via a water source buffer tank 6 and a water source booster pump 7. The water in the water source buffer tank 6 could also utilize the steam condensate from the reboiler 8 outlet. The internally coupled energy-saving atomizing device 4 forms a uniformly distributed water mist at the inlet space of the integrated absorption-condensation ammonia recovery unit 3 at the top of the tower, creating multiple "absorption nuclei" at the inlet. Simultaneously, tiny negative pressure cavitation forms on the surface of the water mist droplets, encouraging more gas to flow towards the integrated absorption-condensation ammonia recovery unit 3. Some of the ammonia-containing vapor is absorbed and cooled by pure water spray at the internally coupled energy-saving atomizing device 4 and then enters the integrated absorption-condensation ammonia recovery unit 3. The uncondensed ammonia gas undergoes indirect heat exchange within the integrated absorption-condensation ammonia recovery unit 3 via circulating water. When ammonia nitrogen concentration and temperature fluctuate, the opening range of the flow regulating valve of the atomizing device is automatically interlocked with the concentration of the produced ammonia water. Based on the ammonia water concentration, the number of atomizers opened, the pure water flow rate, and the pure water valve in the energy-saving atomizing device are adjusted to regulate the gas inside the housing. Specifically: based on the ammonia water concentration indicated by the ammonia water concentration indicator 17, when the ammonia water concentration is insufficient, the automatic control program connected to the atomization control 16 will minimize the flow regulating valve in the internally coupled energy-saving atomizing device 4 until the ammonia water concentration indicated by the ammonia water concentration indicator 17 reaches or exceeds the required concentration. Then, through the automatic control program connected to the atomization control 16, the opening of the flow regulating valve of one of the nozzles in the internally coupled energy-saving atomizing device 4 will be gradually increased. When the influent ammonia nitrogen value increases, or the ammonia water concentration indicated by the ammonia water concentration indicator 17 still exceeds the preset ammonia water concentration, the automatic control program will continue to increase the number and opening of the flow regulating valves of other nozzles in the internally coupled energy-saving atomizing device 4. By controlling the injection flow rate of the absorbent, the ammonia water concentration is adjusted, simultaneously saving steam.

[0066] After the renovation, the concentration of ammonia water recovered at the top of the tower can be controlled at 10%~20% according to the owner's needs, and the steam consumption per ton of water is reduced to 150kg steam / m³ wastewater, with a steam saving rate of 61%. The carbon emissions per ton of water treated are reduced by 44.7kg (based on the requirement of 0.034g of standard coal for 1kJ of heat, and the carbon dioxide emission value of standard coal is calculated as 2.54 tCO2 / tce).

[0067] Example 3

[0068] This embodiment provides an internally coupled energy-saving atomization ammonia water recovery device and process for high-concentration ammonia nitrogen wastewater:

[0069] Devices such as Figure 6As shown, the device includes an ammonia stripping tower 1, an ammonia-containing steam pipeline 2, an integrated absorption-condensation ammonia recovery unit 3, an internally coupled energy-saving atomizing device 4, an automatic flow regulating valve 5, a water source buffer tank 6, a water source booster pump 7, a feed preheater 9, and an outlet water heat exchanger 10.

[0070] Other connection methods are the same as in Example 2, except that the reboiler 8 is replaced in sequence with the feed preheater 9 and the outlet water heat exchanger 10.

[0071] Process: A certain ammonia absorption system produces dilute ammonia water with an ammonia concentration of approximately 25 g / L. This concentration is insufficient for reuse. An ammonia removal tower can be used to remove ammonia and recover ammonia concentrations of over 15%. Conventional ammonia removal processes consume 180-200 kg of steam per ton of dilute ammonia water and 400 m³ / h of circulating water per ton of water. By employing a tower top condenser with an internally coupled energy-saving atomizing device, steam consumption per ton of water is reduced to 120 kg / h, a reduction of 33-40%, and circulating water consumption is reduced to 100 m³ / h, achieving a savings of 75%. Simultaneously, the diameters of the ammonia-containing steam pipeline 2 and the circulating water pipeline can be correspondingly reduced, saving on piping material costs.

[0072] In addition, a feed preheater 9 and an outlet water heat exchanger 10 are added after the ammonia removal tower 1 in this system. The feed preheater 9 is used to exchange heat between the feed water and the tower bottom water to recover the heat of the tower bottom water and increase the temperature of the material entering the ammonia removal tower, thus saving steam consumption. The outlet water heat exchanger 10 uses low-temperature water to cool the tower bottom water, so that the cooled water can be used again as an ammonia absorbent in the system or as a source of pure water atomization at the top of the tower for ammonia absorption.

[0073] The entire process of this invention does not require the introduction of additional pure water, thus avoiding water volume expansion in the entire system and reducing the processing load on enterprises. Simultaneously, the ammonia gas at the top of the tower is fully absorbed, dissolved, and condensed in the condenser, achieving an ammonia recovery rate of over 99.9%, with no ammonia gas escaping.

[0074] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A high-concentration ammonia-nitrogen wastewater internal coupling energy-saving atomization ammonia water recovery process, characterized in that, include: Step 1: The ammonia gas and water vapor mixture produced by the distillation of high-concentration ammonia nitrogen wastewater in the deammoniation tower enters the integrated absorption-condensation ammonia recovery unit through pipelines. Step 2: The internally coupled energy-saving atomizing device is internally coupled to the absorption-condensation integrated ammonia recovery unit or the inlet pipe. The internally coupled energy-saving atomizing device generates a continuous ultra-fine water mist in the absorption-condensation integrated ammonia recovery unit or the inlet pipe, forming small droplets with ultra-high specific surface area, which greatly increases the contact area between ammonia gas and water vapor and water. Step 3: After the ammonia vapor combines with this ultrafine water mist, it rapidly exchanges heat, causing the water vapor to liquefy into liquid water. At the same time, because ammonia is extremely soluble in water, ammonia gas molecules combine with the liquefied water vapor molecules and rapidly release their heat of solution to form ammonia water. Step four: The released heat of dissolution, along with some uncondensed water vapor and ammonia, enters the integrated absorption-condensation ammonia recovery unit. Since the partial pressure of ammonia and water vapor has been reduced, the remaining heat is indirectly exchanged through continuously flowing circulating cooling water, further improving the dissolution rate and cooling rate of ammonia. Finally, high-purity concentrated ammonia water is formed and discharged from the integrated absorption-condensation ammonia recovery unit. The internally coupled energy-saving atomizing device includes a spiral nozzle and an atomization control section; wherein, the spiral nozzle includes an absorbent inlet, an absorbent outlet, and a guide spiral; The atomization control section includes a water inlet, which is used to receive the absorbent to be atomized; the atomization control includes the atomizer distribution, the automatic control interlock between the atomized water flow rate and the ammonia concentration, and the automatic control interlock between the number of atomizing nozzles opened and the ammonia concentration. The internally coupled energy-saving atomizing device is used to form atomized droplets from the absorbent introduced into the atomizing device without consuming any electrical energy or other power. The atomizing device has multiple flow rate and angle options. The guide spiral of the atomized droplets is a hollow / solid cone shape, and the angle of the absorbent spray is 60°~170°. According to different working conditions, the atomized droplets are evenly and efficiently dispersed from the atomizing device into the pipeline or ammonia recovery unit shell, ensuring that the gas entering the ammonia recovery unit is fully contacted with the atomized droplets and transformed into ammonia water droplets.

2. The process of claim 1, wherein the process is characterized by, The process is accomplished through an internally coupled, energy-saving atomization device for recovering ammonia from high-concentration ammonia nitrogen wastewater. 3.The process of claim 2, wherein, The internally coupled energy-saving atomization ammonia water recovery device for high-concentration ammonia nitrogen wastewater includes an ammonia vapor pipeline, an integrated absorption-condensation ammonia recovery unit, an internally coupled energy-saving atomization device, an automatic flow regulating valve, a water source switch valve, a water source booster pump, and a water source buffer tank. One end of the ammonia-containing steam pipeline is connected to the ammonia removal tower or other equipment / pipelines that generate ammonia-containing waste gas, and the other end is directly connected to the absorption-condensation integrated ammonia recovery unit or connected to the absorption-condensation integrated ammonia recovery unit after passing through an internally coupled energy-saving atomization device. The absorption-condensation integrated ammonia recovery unit is a horizontal shell-and-tube heat exchanger, which is connected to the ammonia-containing vapor pipeline at the top of the deammoniation tower. It is used to receive and exchange heat with the ammonia gas and water vapor that are heated and evaporated in the deammoniation tower. The water source booster pump is connected to the water source buffer tank and is used to supply water to the internally coupled energy-saving atomizing device; The automatic flow regulating valve can automatically control the water flow rate based on the temperature at the top of the tower and the concentration of ammonia water. The water source switch valve is selected to open to use this water source, or to close to use other water sources, depending on the water source.

4. The process for internal coupling energy-saving ammonia water recovery from high-concentration ammonia-nitrogen wastewater according to claim 1, characterized in that, The absorbent is selected from one or more of the following: pure water, dilute ammonia water, reboiler condensate, tower bottom water, and acid solution.

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