Internal coupling energy-saving atomization ammonia water recovery process for high-concentration ammonia-nitrogen wastewater

Abstract

The invention 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 steps that firstly, ammonia gas and water vapor mixed gas generated after high-concentration ammonia-nitrogen wastewater is rectified through a deamination tower enters the absorption-condensation integrated ammonia recoverer through a pipeline, an internal coupling energy-saving atomization energy-saving device of the integrated ammonia recoverer can generate superfine water mist, and after being combined, ammonia-containing vapor and the superfine water mist are subjected to rapid heat exchange; meanwhile, due to the characteristic that ammonia is extremely easy to dissolve in water, ammonia gas molecules can be combined with liquefied water vapor water molecules, and dissolving heat of the water vapor water molecules can be quickly released to form ammonia water. The method is simple in technological process and small in equipment investment and occupied area, a multi-stage absorption tower and a large amount of absorbent can be saved, the ammonia water is recycled in one step, the ammonia water is high in purity and controllable in concentration, almost no noncondensable gas is generated, and meanwhile steam energy consumption in the high-concentration ammonia-nitrogen wastewater deamination process can be saved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to an internally coupled energy-saving atomization process for recovering ammonia water from high-concentration ammonia nitrogen wastewater. Background Art

[0002] Nonferrous metallurgy, ternary metals, tungsten, molybdenum, rare earth and other industries often produce wastewater containing high concentrations of ammonia nitrogen during the production process. At present, those skilled in the art generally use a deamination tower to evaporate the ammonia nitrogen in the wastewater in the form of ammonia gas by distillation to achieve the discharge of wastewater in compliance with the standards. The specific process is: the ammonia nitrogen wastewater to be treated is first heat-exchanged with the high-temperature effluent water from the deamination tower kettle and then enters the deamination tower, and is directly passed into the deamination tower through fresh steam; or a reboiler is used to indirectly heat the partially circulating tower kettle effluent water to distill and deaminate the wastewater containing high concentrations of ammonia nitrogen, and the heat source of the reboiler is generally steam. The ammonia gas evaporated from the top of the distillation deamination tower is generally recovered as ammonia water of a certain concentration through a multi-stage absorption tower or a condenser for indirect cooling.

[0003] When the ammonia nitrogen concentration in the wastewater is below 10g / L, the ammonia gas at the top of the tower is easier to be condensed and absorbed during the distillation process, and the steam consumption per ton of water can be controlled below 120kg. When the ammonia nitrogen concentration in the wastewater is above 10g / L, the ammonia gas at the top of the tower is too large during the distillation process, and it is often not condensed and absorbed in time and effectively, and the ammonia gas escapes very seriously, causing air pollution and the cost of secondary waste gas treatment. In order to reduce the escape of ammonia gas, the conventional technology is to evaporate water from the bottom of the tower to the top of the tower by introducing a large amount of steam (the steam consumption per ton of water is higher than 180kg and increases with the increase of ammonia nitrogen concentration), and then use a large amount of circulating cooling water to cool it down, absorb the ammonia gas into ammonia water, or spray the ammonia gas at the top of the tower through a multi-stage absorption tower. This process not only has cumbersome equipment and processes, but also uses a large amount of absorbent and the concentration of recovered ammonia water is low. At present, in the process of treating high-concentration ammonia nitrogen wastewater, problems such as high steam consumption, high circulating water consumption, large exhaust gas emissions, low ammonia water concentration, high overall treatment energy consumption, high cost, and high carbon emissions have become problems that need to be solved urgently.

[0004] CN 103641193A (An energy-saving ammonia distillation technology) proposes an energy-saving production method for ammonia distillation, which generates secondary steam by exchanging heat with the raw ammonia water and the ammonia vapor generated by distillation in turn, and then enters the compressor for secondary compression to generate high-temperature and high-pressure steam for providing heat source for the distillation tower. However, this technology has the following problems: 1. It only replaces part of the fresh steam with regenerated steam for recycling, and does not fundamentally solve the problem of large overall steam consumption in the wastewater treatment process; 2. The compressor consumes a lot of electricity in the process of providing circulating steam, and cannot guarantee that the comprehensive energy consumption is reduced, and the overall investment and land occupation are large. 3. The concentration of ammonia water recovered by this technology is only 10%, and the economic efficiency is low. 4. Adding equipment such as compressors requires high investment.

[0005] CN104891726B (treatment system for high-concentration ammonia nitrogen wastewater) proposes a concentration energy-saving device, which first uses a heat exchanger to recover the heat energy of the tower kettle, increases the temperature of the ammonia nitrogen wastewater entering the concentration tank (i.e., the concentration device), and then uses the concentration energy-saving device to mix the wastewater entering the tower with the ammonia-containing steam at the top of the tower to increase its temperature and ammonia concentration. However, this technology has the following problems: 1. It is necessary to configure a large-volume concentration tank, and at the same time, the expansion of the water volume after the concentration tank increases the processing load of the system; 2. The ammonia-containing steam at the top of the tower enters the concentration tank for heat exchange and then enters the distillation tower again, resulting in the ammonia concentration at the top of the tower being in a fluctuating state at all times, and the pressure of the concentration tank and the top of the tower is also difficult to stably control, and the concentration of the recovered ammonia water is also in a fluctuating state; 3. The ammonia-containing steam cannot be condensed and recovered as ammonia water in one step, but when some ammonia-containing steam that cannot be condensed enters the concentration tank from the top of the tower and then enters the tower, ammonia is easy to leak in the whole process, thereby causing 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, ammonia water formed by cooling ammonia vapor after ammonia evaporation enters a reflux tank, and non-condensable steam in the reflux tank enters a jet circulating water tank after cooling. Part of the ammonia vapor in the non-condensable gas is dissolved in the circulating liquid, and the non-condensable gas tail gas enters the gas pipeline. The formed finished ammonia water is refluxed, and the rest of the finished ammonia water is sent out. However, the process route of this technology is relatively complicated, and ammonia water cannot be recovered by condensation in one step. At the same time, this technology changes the conventional ammonia evaporation tower from normal pressure operation to negative pressure operation, which greatly increases the manufacturing cost and maintenance cost of the equipment and the complexity of 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 process of high-concentration ammonia nitrogen wastewater. Summary of the invention

[0008] To this end, the present invention provides an internally coupled energy-saving atomization ammonia water recovery process for high-concentration ammonia nitrogen wastewater to solve the above-mentioned problems.

[0009] The present invention analyzes the high energy consumption of ammonia nitrogen recovery process in high-concentration ammonia nitrogen wastewater from the source, and learns that the reason why the deammoniation steam consumption of high-concentration ammonia nitrogen wastewater is large and the ammonia escape from the top of the tower is serious is that the amount of ammonia at the top of the tower is large. If the steam is not excessively introduced, the ratio of ammonia at the top of the tower to absorbent water does not match, and a large amount of ammonia cannot be dissolved and absorbed by water. The amount of ammonia and water vapor at the top of the tower is too large, and the indirect heat exchange of circulating water cannot fully condense the high-temperature gas in time, so the uncondensed ammonia is easy to escape and cause air pollution. According to this analysis process, the present invention proposes a simple and easy-to-implement energy-saving, environmentally friendly and efficient process, which can greatly reduce the steam and circulating water consumption in the process of ammonia nitrogen wastewater distillation deammoniation, reduce carbon emissions, reduce ammonia tail gas emissions, and can efficiently recover high-purity concentrated ammonia water in one step, with the characteristics of energy saving, environmental protection and high efficiency. And because its process flow is simple, the equipment investment cost is low, and the operation is stable, it is also convenient for enterprises to promote and apply it, and implement energy-saving transformation of existing devices as soon as possible.

[0010] In order to achieve the above object, the present invention provides the following technical solutions:

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

[0012] Step 1: After the high-concentration ammonia nitrogen wastewater is distilled in a deamination tower, a mixed gas of ammonia gas and water vapor is generated and enters the absorption-condensation integrated ammonia recovery device through a pipeline, preferably a shell side and / or a tube side;

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

[0014] Step 3: After the ammonia-containing steam combines with the ultrafine water mist in the pipeline or the integrated ammonia recovery device, heat is quickly exchanged to liquefy the water vapor into liquid water. At the same time, since ammonia is very soluble in water, the ammonia gas molecules can combine with the liquefied water vapor molecules and quickly release their heat of dissolution to form ammonia water.

[0015] In step 4, the released heat of solution and part of the uncondensed water vapor and ammonia enter the ammonia recovery device. Since the partial pressure of ammonia and water vapor has been reduced, the remaining heat is indirectly exchanged through the continuously flowing circulating cooling water, which further increases the dissolution rate and cooling rate of ammonia, and finally forms high-purity concentrated ammonia water and is discharged from the condenser.

[0016] Furthermore, the process is completed by an energy-saving atomization ammonia water recovery device that is internally coupled to high-concentration ammonia nitrogen wastewater.

[0017] Furthermore, the device includes an ammonia-containing steam pipeline, an absorption-condensation integrated ammonia recovery device, an internally coupled energy-saving atomization 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 a deammonification tower or other equipment / pipeline that produces ammonia-containing waste gas, and the other end is directly connected to an absorption-condensation integrated ammonia recovery device or connected to the absorption-condensation integrated ammonia recovery device after passing through an energy-saving atomization device;

[0019] The absorption-condensation integrated ammonia recovery device is a horizontal shell-and-tube heat exchanger, which is connected to the ammonia-containing steam pipeline at the top of the deamination tower and is used to receive the ammonia gas and water vapor evaporated by heat in the deamination tower and exchange heat; the tube-side medium is circulating cooling water, and the shell-side medium is the ammonia-containing steam at the top of the tower;

[0020] The water source booster pump is connected to the water source buffer tank, which is used to deliver water to the internally coupled energy-saving atomizing device; the water source of the water source buffer tank has multiple sources, including but not limited to pure water, or connected to the outlet ammonia water pipeline or ammonia water tank of the integrated ammonia recovery device, or connected to the water outlet of the deamination tower kettle, or connected to the condensed water of the deamination tower reboiler, etc. The water source buffer tank is set with a water source buffer volume of 0.5 to 1h to provide a stable water flow.

[0021] The automatic flow regulating valve can automatically perform interlocking control according to the temperature of the tower top and the ammonia concentration, and adjust the total water flow.

[0022] The water source switch valve can be opened according to different water sources to use this water source or closed to use other water sources.

[0023] Furthermore, the internal coupling energy-saving atomization device includes a spiral nozzle (including an absorbent inlet, an absorbent outlet, and a guide spiral) and an atomization control part. The spiral nozzle is a part of the atomization device assembly, and a product available on the market can be selected. Atomization control is part of the process described in the present invention.

[0024] Furthermore, the atomization control part may contain a water source inlet, wherein the water source inlet is used to receive the absorbent to be atomized; the atomization control includes designs such as atomizer distribution layout, automatic interlocking of atomization water spray flow rate and ammonia concentration, automatic interlocking of the number of atomization device openings and ammonia concentration, and in actual production, corresponding equipment design and automatic control design can be carried out in combination with process needs; that is to say, the atomization control process includes distributing and arranging the atomizers according to needs in the equipment design stage, controlling the number of atomizers opened in the engineering operation stage, and adjusting the absorbent flow rate.

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

[0026] Furthermore, the atomizing device has a variety of flow rates and angles to choose from. The atomizing guide spiral is located on the atomizing device. The atomizing droplet guide spiral is a hollow / solid cone. The angle of the absorbent spray can be selected from the range of 60° to 170° according to the shape and length of the guide spiral, so that the atomized droplets can be evenly and efficiently dispersed from the atomizer to the pipeline or the ammonia recovery device shell according to different working conditions; ensuring that the gas entering the ammonia recovery device is fully in contact with the atomized droplets and converted into ammonia droplets.

[0027] The energy-saving atomizing device has the characteristics of adjustable angle (60°~170°), adjustable flow, non-clogging structural design, large flow diameter, simple structure and compact size. It can be connected to the ammonia recovery device by thread or flange, and can be coupled in pipeline or shell. It does not consume any power in the form of electricity or steam, and can form high-density and large-area atomized droplets, ensuring that the gas entering the ammonia recovery device is fully in contact with the atomized droplets and then converted into ammonia droplets.

[0028] Furthermore, the absorbent may be selected from pure water or dilute ammonia water, reboiler condensate, tower bottom water, acid solution and other different absorbents according to the working conditions.

[0029] The present invention has the following advantages:

[0030] 1) The present invention effectively solves the problem of large steam and circulating water consumption when recovering ammonia water from high-concentration ammonia nitrogen wastewater. When the ammonia nitrogen concentration is too high, the ammonia-containing steam at the top of the tower has a mismatched ratio of ammonia gas to water vapor. In order to fully condense and absorb the ammonia, a large amount of steam needs to evaporate to the top of the tower as an absorbent. The water source provided by the pure water atomization energy-saving device can be used to supplement the amount of water required for the ammonia gas in the high-concentration ammonia nitrogen wastewater to condense into ammonia water, thereby replacing part of the steam consumption and reducing the energy consumption, operating costs and carbon emissions of the entire device as a whole. At the same time, the source of the water source can be matched according to the diversification of processes, and the reduction of wastewater emissions can also be indirectly achieved.

[0031] 2) The present invention can recover ammonia to a greater extent by providing an energy-saving atomizing device, and can save steam and achieve energy-saving effects by adding an energy-saving atomizing device.

[0032] 3) The introduction of the water absorbent of the present invention reduces the partial pressure of ammonia and water vapor entering the heat exchanger, thereby replacing part of the heat that needs to be exchanged by a large amount of circulating water with direct heat exchange of a very small amount of water absorbent, thereby reducing the cooling capacity required by the entire system and saving circulating water. At the same time, due to the reduction in heat exchange, the heat exchange area required for the absorption-condensation integrated ammonia recovery device can be saved, reducing equipment investment and land occupation.

[0033] 4) The process flow of the present invention is simple, the equipment investment and the land occupation are small, and the multi-stage absorption tower and a large amount of absorbent can be saved to recover the ammonia water in one step. The ammonia water has high purity and controllable concentration, and almost no non-condensable gas is produced, thereby avoiding the waste of ammonia resources and air pollution.

[0034] 5) The present invention has a high degree of automation, a stable and controllable process, and low difficulty in transformation, which facilitates enterprises to implement energy-saving transformation of existing devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0036] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0037] Figure 1 A schematic diagram of an internally coupled energy-saving atomizing ammonia water recovery device for high-concentration ammonia nitrogen wastewater provided in Example 1 of the present invention;

[0038] Figure 2 A diagram of an atomization device provided in Example 1 of the present invention;

[0039] Figure 3 A schematic diagram of a nozzle provided in Example 1 of the present invention;

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

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

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

[0043] In the figure: 1-deammonia tower, 2-ammonia steam pipeline, 3-absorption-condensation integrated ammonia recovery device, 4-internal coupling energy-saving atomization device, 5-flow automatic 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- spiral nozzle, 18-1- absorbent inlet, 18-2- absorbent outlet, 18-3- guide spiral, 18-4- spray outlet angle;

[0045] 19 - the second automatic flow regulating valve, 20 - the third automatic flow regulating valve, 21 - the fourth automatic flow regulating valve. DETAILED DESCRIPTION

[0046] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are 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 creative work 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 steam pipeline 2, an absorption-condensation integrated ammonia recovery device 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 atomizing control 16, and an ammonia water concentration indicating instrument 17;

[0050] One end of the ammonia-containing steam pipeline 2 is connected to a deammonification tower or other equipment that produces ammonia-containing waste gas, and the other end is connected to an absorption-condensation integrated ammonia recovery device 3 .

[0051] The absorption-condensation integrated ammonia recovery device 3 is a horizontal shell-and-tube heat exchanger, which is connected to the top pipeline of the deamination tower and is used to receive the ammonia gas and water vapor evaporated by heat in the deamination tower and exchange heat. The tube side medium is circulating cooling water, and the shell side medium is the ammonia-containing steam at the top of the tower. The ammonia water in the absorption-condensation integrated ammonia recovery device 3 is collected after the ammonia water concentration indicator 17 indicates that the ammonia water is more than 15% high-purity concentrated ammonia water.

[0052] The inner coupling energy-saving atomizing device 4 is provided with an atomizing device, such as Figure 2 As shown, the spiral nozzle 18 and the second automatic flow regulating valve 19 are included. The spiral nozzle 18 sprays the absorbent, and the second automatic flow regulating valve 19 regulates the spraying amount of the absorbent. Figure 3 As shown, it includes: an absorbent inlet 18-1, an absorbent outlet 18-2, a guide spiral 18-3, and a spray outlet 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 the absorbent pipeline. The absorbent outlet 18-2 is used to spray the absorbent input from the absorbent pipeline and form a spray under the action of the guide spiral 18-3. The spray outlet angle 18-4 is the angle formed by the absorbent spray under the action of the guide spiral 18-3.

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

[0054] Specifically, the atomization control 6 may include a water source inlet, wherein the water source inlet is used to receive the absorbent to be atomized; the water source inlet is used to receive the pure water (or other absorbents such as dilute ammonia water) to be atomized, and the atomization control includes: in the design stage, a single or multiple atomizers are distributed and arranged according to the process requirements to control the number and arrangement of the atomizers, and the number and opening of the nozzles can be adjusted in the engineering operation stage. The unpowered atomization device is used to form atomized droplets from the pure water (or other absorbents such as dilute ammonia water) introduced into the atomization device without consuming any electrical energy or other power. The atomized droplet guide spiral is conical so that the atomized droplets can be evenly and efficiently dispersed from the atomizer into the ammonia recovery device shell. The pure water atomization device has the characteristics of adjustable angle (60°~170° stepless adjustment), adjustable flow, non-clogging structure design, large nozzle diameter, simple structure and compact size. It can be connected to the ammonia recovery device by thread or flange, and can be coupled in the pipeline or shell. At the same time, high-density and large-area atomized droplets can be formed without consuming any power, ensuring that the gas entering the ammonia recovery device is fully in contact with the atomized droplets and then converted into ammonia droplets.

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

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

[0057] The water source buffer tank 6 is provided 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 of the tower top and the concentration of ammonia water, and the flow of pure water or dilute ammonia water can be roughly adjusted. A more precise adjustment is the automatic control between the internal coupling energy-saving atomizing device 4 and the ammonia concentration indicating instrument 17, which is specifically: according to the ammonia concentration indicated by the ammonia concentration indicating instrument 17, when the ammonia concentration is less than the required 15% or more, the flow regulating valve in the internal coupling energy-saving atomizing device 4 can be adjusted to the minimum through the automatic control program connected to the atomizing control 16, until the ammonia concentration indicated by the ammonia concentration indicating instrument 17 reaches more than 15%, and the flow regulating valve opening of one of the nozzles in the internal coupling energy-saving atomizing device 4 is gradually increased through the automatic control program connected to the atomizing control 16. When the ammonia concentration indicated by the ammonia concentration indicating instrument 17 still exceeds 15%, the flow regulating valve opening number and opening of other nozzles in the internal coupling energy-saving atomizing device 4 are continued to be increased through the automatic control program, and the ammonia concentration is adjusted by controlling the injection flow of the absorbent.

[0059] The first switch valve 13, the second switch valve 14 and the third switch valve 15 are all switch valves, which can be opened or closed according to the process requirements, and are used to switch the water source required by the energy-saving atomization device. Process: The mixed gas of ammonia and water vapor generated by the high-concentration ammonia nitrogen wastewater after distillation in the deamination tower enters the absorption-condensation integrated ammonia recovery device 3 through the ammonia-containing steam pipeline 2. The internally coupled energy-saving atomization device 4 produces continuous small droplets with ultra-high specific surface area in the shell side (or inlet) of the absorption-condensation integrated ammonia recovery device 3, which greatly increases the contact area between ammonia and water, and improves the mass transfer efficiency during condensation and absorption. The ammonia-containing vapor combines with the ultrafine water mist to quickly exchange heat, liquefying the water vapor into liquid water. At the same time, since ammonia is very soluble in water, ammonia gas molecules can combine with liquefied water vapor molecules and quickly release their heat of solution to form ammonia water. The released heat of solution and some uncondensed water vapor and ammonia enter the ammonia recovery device. Since the partial pressure of ammonia and water vapor has been reduced, the remaining heat is indirectly exchanged through the continuously flowing circulating cooling water, further improving the dissolution rate and cooling rate of the ammonia gas, and finally forming high-purity concentrated ammonia water and then 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 a deammonification tower 1, an ammonia-containing steam pipeline 2, an absorption-condensation integrated ammonia recovery device 3, an internally coupled energy-saving atomization 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 those in Example 1, except that the waste ammonia gas of the ammonia-containing steam pipeline 2 comes from the deammonification tower 1, the water source buffer tank 6 is connected to the reboiler 8, and the reboiler 8 is connected to the deammonification tower 1;

[0064] Process: A high-concentration ammonia nitrogen wastewater deammonification device. The current ammonia nitrogen concentration of the influent is as high as 60g / L, and the unit consumption of steam per ton is 380kg / m 3 , and the ammonia smell in the deamination tower is serious. The difference between the amount of ammonia water recovered by the ammonia system and the theoretical amount of ammonia water recovered is about 600 to 1,000 tons / year. According to the production process, the actual amount of ammonia water recovered is quite different from the theoretical calculation and the reason for the strong ammonia smell on site is that the ammonia gas that is not absorbed and condensed at the top of the tower is wasted in the form of waste gas during the deamination process, resulting in the concentration of recovered ammonia water being less than 10%, and ammonia leakage is serious.

[0065] The deammonification system is transformed into an energy-saving and environmentally friendly one. An internally coupled energy-saving atomizing device 4 is added at the connection between the ammonia steam pipeline 2 at the top of the deammonification tower 1 and the absorption-condensation integrated ammonia recovery device 3, and an automatic flow regulating valve 5 is set. Pure water is provided to the internally coupled energy-saving atomizing device 4 through a water source buffer tank 6 and a water source booster pump 7. The water in the water source buffer tank 6 can also be condensed water from the steam at the outlet of the tower kettle reboiler 8. The internally coupled energy-saving atomizing device 4 at the top of the tower forms a uniformly distributed water mist at the inlet space of the absorption-condensation integrated ammonia recovery device 3 at the top of the tower, so that multiple "absorption core points" are generated at the inlet of the absorption-condensation integrated ammonia recovery device 3. At the same time, extremely small negative pressure cavitations are formed on the surface of the water mist droplets, which promotes more gas to flow to the absorption-condensation integrated ammonia recovery device 3. Part of the ammonia-containing steam is absorbed and cooled down by pure water spraying at the internally coupled energy-saving atomizing device 4, and enters the absorption-condensation integrated ammonia recovery device 3. The uncondensed part of the ammonia gas is indirectly heat-exchanged by circulating water in the absorption-condensation integrated ammonia recovery device 3. When the ammonia nitrogen concentration and temperature fluctuate, the opening amplitude of the flow regulating valve of the atomizing device is automatically interlocked with the concentration of the output ammonia water, and the opening number of the atomizers of the energy-saving atomizing device, the pure water flow rate, and the pure water valve are adjusted according to the ammonia concentration to adjust the gas in the shell. The specific method is: according to the ammonia concentration indicated by the ammonia concentration indicator 17, when the ammonia concentration is less than the required concentration, the flow regulating valve in the internal coupling energy-saving atomizing device 4 can be minimized through the automatic control program connected to the atomizing control 16, until the ammonia concentration indicated by the ammonia concentration indicator 17 reaches the required concentration or above, and the flow regulating valve opening of one of the nozzles in the internal coupling energy-saving atomizing device 4 is gradually increased through the automatic control program connected to the atomizing control 16. When the ammonia nitrogen value of the inlet water increases, or the ammonia concentration indicated by the ammonia concentration indicator 17 still exceeds the preset ammonia concentration, the opening number and opening of the flow regulating valves of other nozzles in the internal coupling energy-saving atomizing device 4 are continued to be increased through the automatic control program, and the ammonia concentration is adjusted by controlling the injection flow of the absorbent, and the effect of saving steam is achieved at the same time.

[0066] After the transformation, the concentration of ammonia water recovered from the top of the tower can be controlled at 10% to 20% according to the needs of the owner, and the steam consumption per ton of water is reduced to 150kg steam / m 3 The savings rate of wastewater and steam reaches 61%, and the carbon emissions per ton of water processed are reduced by 44.7kg (based on the fact that 1kJ of heat requires 0.034g of standard coal, and the carbon dioxide emissions of standard coal are calculated at 2.54tCO2 / 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 a deammonification tower 1, an ammonia-containing steam pipeline 2, an absorption-condensation integrated ammonia recovery device 3, an internally coupled energy-saving atomization device 4, a flow automatic 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] The other connection methods are the same as those in Example 2, except that the reboiler 8 is replaced by the feed preheater 9 and the outlet water heat exchanger 10 in sequence;

[0071] Process: The dilute ammonia water produced by an ammonia absorption system has an ammonia concentration of about 25g / L. This concentration is difficult to meet the reuse standard. A deammonification tower can be used to deammonify and recover ammonia water with a concentration of more than 15%. Conventional deammonification processes require 180 to 200 kg of steam per ton of dilute ammonia water, and 400 m3 of circulating water per ton of water. 3 / h, by using the top condenser with internal coupling energy-saving atomization device, the steam consumption per ton of water is reduced to 120kg / h, reducing steam consumption by 33-40%, and circulating water consumption is reduced to 100m 3 / h, the saving rate can reach 75%. At the same time, the diameter of the ammonia steam pipeline 2 and the circulating water pipeline can be reduced accordingly, saving the pipeline material cost of the device.

[0072] In addition, a feed preheater 9 and an outlet water heat exchanger 10 are added after the deamination tower 1 of the system. The feed preheater 9 is used to perform heat exchange between the inlet water and the outlet water of the tower bottom, so as to recover the heat of the outlet water of the tower bottom to increase the temperature of the material entering the deamination tower and save steam usage. The outlet water heat exchanger 10 uses low-temperature water to cool the outlet water of the tower bottom, so that the outlet water can be used as the ammonia absorbent of the system or the water source for the atomization of the pure water at the top of the tower after cooling, and used as the absorbent of ammonia.

[0073] The whole process of the present invention does not need to introduce additional pure water, which can avoid causing water expansion in the whole system and reduce the processing load of the enterprise. At the same time, the ammonia gas at the top of the tower is fully absorbed, dissolved and condensed in the condenser, and the ammonia recovery rate reaches more than 99.9%, and there is no ammonia gas leakage as a whole.

[0074] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. An internally coupled energy-saving atomization process for recovering ammonia water from high-concentration ammonia nitrogen wastewater, characterized in that: include: Step 1: After the high-concentration ammonia nitrogen wastewater is distilled in the deamination tower, the ammonia and water vapor mixed gas is sent into the absorption-condensation integrated ammonia recovery device through the pipeline; Step 2: The internally coupled energy-saving atomizing device is internally coupled to the absorption-condensation integrated ammonia recovery device or the inlet pipeline, and the internally coupled energy-saving atomizing device generates continuous ultrafine water mist in the absorption-condensation integrated ammonia recovery device or the inlet pipeline to form small droplets with ultra-high specific surface area, so that the contact area between ammonia gas and water vapor and water is greatly increased; Step 3: After the ammonia-containing steam combines with the ultrafine water mist, heat is quickly exchanged to liquefy the water vapor into liquid water. At the same time, since ammonia is very soluble in water, the ammonia gas molecules can combine with the liquefied water vapor molecules and quickly release their heat of dissolution to form ammonia water. In step 4, the released heat of solution and part of the uncondensed water vapor and ammonia enter the absorption-condensation integrated ammonia recovery device. Since the partial pressure of ammonia and water vapor has been reduced, the remaining heat is indirectly exchanged through the continuously flowing circulating cooling water, which further increases the dissolution rate and cooling rate of ammonia, and finally forms high-purity concentrated ammonia water and is discharged from the condenser.

2. The internally coupled energy-saving atomization ammonia recovery process for high-concentration ammonia nitrogen wastewater according to claim 1 is characterized in that: The process is completed by an internally coupled energy-saving atomization ammonia water recovery device for high-concentration ammonia nitrogen wastewater.

3. The internally coupled energy-saving atomization ammonia recovery process for high-concentration ammonia nitrogen wastewater according to claim 2 is characterized in that: The device comprises an ammonia-containing steam pipeline, an absorption-condensation integrated ammonia recovery device, 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; Among them, one end of the ammonia-containing steam pipeline is connected to the deammonification tower or other equipment / pipeline that produces ammonia-containing waste gas, and the other end is directly connected to the absorption-condensation integrated ammonia recovery device or connected to the absorption-condensation integrated ammonia recovery device after being internally coupled with an energy-saving atomization device; The absorption-condensation integrated ammonia recovery device is a horizontal shell-and-tube heat exchanger, which is connected to the ammonia steam pipeline at the top of the deamination tower and is used to receive the ammonia and water vapor evaporated by heat in the deamination tower and exchange heat; The water source booster pump is connected to the water source buffer tank and is used to deliver water to the internally coupled energy-saving atomizing device; The automatic flow regulating valve can automatically interlock and control the water flow according to the temperature at the top of the tower and the concentration of ammonia water; The water source switch valve can be opened according to different water sources to use this water source, or closed to use other water sources.

4. The internally coupled energy-saving atomization ammonia recovery process for high-concentration ammonia nitrogen wastewater according to claim 3 is characterized in that: The internal coupling energy-saving atomization device comprises a spiral nozzle and an atomization control part; wherein the spiral nozzle comprises an absorbent inlet, an absorbent outlet, and a guide spiral.

5. The internally coupled energy-saving atomization ammonia recovery process for high-concentration ammonia nitrogen wastewater according to claim 4 is characterized in that: The atomization control part contains a water source inlet, wherein the water source inlet is used to receive the absorbent to be atomized; the atomization control includes the distribution arrangement of the atomizer, the automatic control linkage between the atomization water spray flow rate and the ammonia concentration, and the automatic control linkage between the number of atomization nozzle openings and the ammonia concentration.

6. The internally coupled energy-saving atomization ammonia recovery process for high-concentration ammonia nitrogen wastewater according to claim 5 is characterized in that: The internally coupled energy-saving atomizing device is used to form atomized droplets of the absorbent introduced into the atomizing device without consuming any electrical energy or other power.

7. The internally coupled energy-saving atomization ammonia recovery process for high-concentration ammonia nitrogen wastewater according to claim 6 is characterized in that: The atomizing device has a variety of flow rates and angles to choose from. The guide spiral of the atomized droplets is a hollow / solid cone. The absorbent spraying angle is 60° to 170°. According to different working conditions, the atomized droplets are evenly and efficiently dispersed from the atomizing device to the pipeline or the ammonia recovery device shell, ensuring that the gas entering the ammonia recovery device is fully in contact with the atomized droplets and then converted into ammonia water droplets.

8. The process for recovering ammonia water by internal coupling energy-saving atomization of high-concentration ammonia nitrogen wastewater according to claim 7, characterized in that: The absorbent is selected from one or more of pure water or dilute ammonia water, reboiler condensate, tower bottom water, and acid solution.

Images