High ammonia-nitrogen wastewater treatment system and process

Abstract

The application discloses a high-ammonia-nitrogen wastewater treatment system and process, and belongs to the field of distillation wastewater treatment. The system comprises a first collecting tank, an alkali liquor preparation tank, a second collecting tank, an ammonia evaporation tower, an intermediate water tank, a three-effect evaporator and a mixed water tank which are sequentially connected through pipelines; a third collecting tank, a rectifying tower and a fourth collecting tank which are sequentially connected through pipelines; a tail water discharge port of the rectifying tower is communicated with the mixed water tank; an exhaust port of the ammonia evaporation tower is communicated with an absorption tower; and the ammonia evaporation tower comprises a tower body, a condenser, a spraying assembly, a filler layer, an anti-fouling assembly, a tray assembly and a water vapor inlet pipe. The anti-fouling assembly is provided with a plurality of scrapers, and each tray assembly is provided with a scraper on the upper side. The three parts of wastewater are comprehensively treated, energy consumption is low, the effect temperature is strong, the applicability is strong, the operation cost is low, the investment cost is low, there is no secondary pollution, and the temperature influence is small.

Description

Technical Field

[0001] This invention belongs to the field of distillation wastewater treatment, and particularly relates to a high ammonia nitrogen wastewater treatment system and process. Background Technology

[0002] Currently, military products are processed using distillation. After distillation, some residual liquid is produced. The current treatment method is to mix it and send it to an incinerator for combustion, which is costly.

[0003] As production capacity expands, the amount of residual liquid increases, and the current incineration equipment is no longer sufficient to meet the capacity requirements. Therefore, it is necessary to install new incineration equipment or seek other ways to treat the liquid.

[0004] Distillation wastewater mainly originates from the residue after distillation, generated by different process stages. It primarily consists of overhead water, waste acid residue, and solvent residue. Overhead water is relatively clean, with relatively low COD and ammonia nitrogen levels. Waste acid residue is characterized by high levels of acetic acid, high COD, and high ammonia nitrogen. Solvent residue mainly consists of light solvent components such as ethyl acetate. Therefore, the main challenges in treating waste acid residue and solvent residue are...

[0005] With the rapid development and expansion of industry, the resulting high ammonia nitrogen wastewater has become one of the constraints on industry development. Excessive ammonia nitrogen discharge into water bodies will lead to eutrophication, reduce the aesthetic value of water bodies, and the nitrates and nitrites generated by oxidation will also affect the health of aquatic organisms and even humans. Therefore, the denitrification of high ammonia nitrogen wastewater has become a focus of attention.

[0006] Ammonia nitrogen wastewater is generally formed due to the coexistence of ammonia water and inorganic ammonia. In wastewater with a pH above neutral, the main source of ammonia nitrogen is the combined effect of inorganic ammonia and ammonia water. Under acidic conditions, ammonia nitrogen in wastewater is mainly due to inorganic ammonia. The composition of ammonia nitrogen in wastewater is mainly of two types: ammonia nitrogen formed from ammonia water and ammonia nitrogen formed from inorganic ammonia, primarily ammonium sulfate, ammonium chloride, etc.

[0007] The main methods for treating high ammonia nitrogen wastewater are as follows:

[0008] 1. Air-blowing method:

[0009] Air stripping involves adjusting the pH of ammonia nitrogen wastewater to alkaline, at which point ammonium ions are converted into ammonia molecules. Gas is then introduced into the water, allowing for thorough contact with the liquid. Dissolved gas and volatile ammonia molecules in the wastewater cross the gas-liquid interface and enter the gas phase, thus removing ammonia nitrogen. This method includes steam stripping, air stripping, and even ultrasonic stripping. The mechanism involves adjusting the wastewater to alkaline, then introducing air or steam into the stripping tower. Through gas-liquid contact, free ammonia in the wastewater is stripped away. This method is simple, effective, versatile, and requires relatively low investment. However, it consumes a lot of energy and can cause secondary pollution. Air stripping is suitable for treating high-concentration ammonia nitrogen wastewater. Its main drawback is its significant temperature dependence; efficiency drops considerably in colder northern climates.

[0010] 2. Ion exchange method:

[0011] Ion exchange is a common method for treating ammonia-containing wastewater, often using zeolite as the exchange medium to improve ammonia removal efficiency. Historical data shows that each gram of zeolite can adsorb 15.5 mg of ammonia nitrogen, and for zeolite with a particle size of 30-60 mesh, the ammonia removal efficiency can reach 78%. However, compared to other treatment technologies, zeolite exchange is more complex to operate, and the regenerated liquid is high-concentration ammonia nitrogen wastewater requiring further treatment. Therefore, it is more suitable for treating low-concentration ammonia nitrogen wastewater. Although ion exchange has achieved certain results in removing ammonia nitrogen from wastewater, the large amount of resin used and the difficulty of regeneration lead to high operating costs and secondary pollution.

[0012] 3. Membrane separation technology:

[0013] This method utilizes the selective permeability of membranes for ammonia nitrogen removal. It is convenient to operate, offers high ammonia nitrogen recovery rates, and produces no secondary pollution. For example, ammonia nitrogen is removed using a gas-liquid separation membrane. Ammonia nitrogen exists in water in a dissociation equilibrium. As the pH increases, the proportion of ammonia in the NH3 form in water increases. Under certain temperature and pressure conditions, the gaseous and liquid states of NH3 reach equilibrium. Chemical equilibrium can only be maintained under certain conditions. "If one of the conditions of the equilibrium system is changed, such as concentration, pressure, or temperature, the equilibrium will shift in the direction that weakens the change." Following this principle, the following design concept was implemented: one side of the membrane contains high-concentration ammonia nitrogen wastewater, and the other side contains an acidic aqueous solution or water. When the temperature on the left side T1>20℃, pH1>9, and P1>P2, and a certain pressure difference is maintained, the ionic ammonia NH4+ in the wastewater... + The nitrogen is converted into free ammonia (NH3) and diffuses to the membrane surface through the feed solution interface. Under the influence of the partial pressure difference on the membrane surface, it passes through the membrane pores and enters the absorbent, where it rapidly reacts with H+ in the acidic solution to form ammonium salt. This method has good nitrogen removal efficiency, but the investment cost is relatively high.

[0014] 4. Breakpoint chlorination:

[0015] Breakpoint chlorination is a chemical denitrification process that involves adding excess chlorine or sodium hypochlorite to oxidize ammonia nitrogen in wastewater into nitrogen gas. This method can achieve a treatment efficiency of 90%–100%, with stable treatment results unaffected by water temperature. However, it has high operating costs, and the byproducts chloramines and chlorinated organic compounds can cause secondary pollution.

[0016] 5. Magnesium ammonium phosphate precipitation method:

[0017] Adding Mg to wastewater containing ammonia nitrogen 2+ and PO4 3- The three react to form MgNH4PO4·6H2O (MAP) precipitate. This method is simple, easy to operate, fast, and has few influencing factors. While removing ammonia nitrogen from wastewater, it also produces MgNH4PO4·6H2O, a compound fertilizer needed by many crops. Furthermore, it can remove phosphorus from the wastewater at the same time. It is an economical and feasible high-concentration ammonia nitrogen wastewater treatment technology that turns waste into treasure.

[0018] Currently, the main methods for treating high-concentration ammonia nitrogen wastewater include air stripping, breakpoint chlorination, and MAP (meta-parameteric acid) chemical precipitation. Air stripping is simple, provides stable results, and has low investment costs; however, it consumes a lot of energy and causes secondary pollution. Breakpoint chlorination offers stable treatment results unaffected by water temperature; however, it has high operating costs, and the byproducts chloramines and chlorinated organic compounds can cause secondary pollution. While chemical precipitation can effectively remove ammonia nitrogen and achieve resource recovery, its main limitation lies in the large amount of precipitating agents required, leading to high treatment costs.

[0019] In addition, the main approach to treating wastewater containing high concentrations of sulfate is to use sulfate-reducing bacteria to reduce sulfate to hydrogen sulfide under anaerobic conditions. If hydrogen sulfide is not recovered and removed, it will cause great harm to the environment.

[0020] Although denitrifying thiobacilli can simultaneously degrade sulfate and ammonia nitrogen, this method must be carried out in separate phases and cannot be carried out simultaneously in the same reactor, resulting in relatively high management and infrastructure costs.

[0021] Because the solvent residue wastewater contains a certain amount of organic matter, and mostly organic solvents, and has a high COD concentration, mainly due to acetic acid, acetone, and ethyl acetate, this membrane separation device cannot be used, and other methods need to be considered.

[0022] 1. Biochemical method:

[0023] Acetic acid, ethyl acetate, and acetone wastewater have very high biodegradability, with a B / C ratio of over 70%. However, substances such as acetone have certain biological toxicity. Therefore, physicochemical treatment is required to improve the biodegradability of organic solvent wastewater. Subsequently, wastewater biological treatment technology can be used to treat organic solvent pollutants in wastewater by cultivating microorganisms and carrying out microbial degradation.

[0024] Organic solvent wastewater can be treated using a combination of anaerobic and aerobic processes. After anaerobic fermentation in a hydrolysis-acidification tank, the wastewater is sent to an activated sludge tank. There, the activated sludge in the activated sludge tank adsorbs suspended solids and colloidal substances from the organic solvent wastewater, and the organic matter in the wastewater reacts with the activated sludge to produce carbon dioxide and water. However, due to the high COD of this wastewater, direct biological treatment is ineffective and can inhibit the development of a biological treatment system.

[0025] 2. Incineration method:

[0026] The main components of the residual liquid are organic solvents such as acetic acid and ethyl acetate. The purpose of incineration is to carbonize the combustible organic matter in wastewater, ultimately converting it into inorganic matter. If the calorific value of the wastewater is insufficient to support combustion, fuel needs to be added to the combustion system to assist combustion. Therefore, it can be seen that the higher the concentration of organic matter in the wastewater for incineration, the better; the more organic matter, the higher the calorific value of the wastewater, and the lower the cost of incineration.

[0027] The oxidation and decomposition temperatures of organic matter and the melting points of inorganic matter in wastewater are mostly between 800 and 1200 degrees Celsius. Carbon-containing fuels and organic matter undergo cracking at 600-900 degrees Celsius, easily producing harmful components such as 3,4-benzopyrene. However, 3,4-benzopyrene can decompose into CO2 and H2O at temperatures above 1000 degrees Celsius. In addition, it should be noted that the NOx content increases sharply at temperatures above 1500 degrees Celsius, resulting in serious secondary pollution. Therefore, the incinerator temperature is generally best kept at around 1000-1100 degrees Celsius.

[0028] The residual liquid is sprayed into the furnace of a circulating fluidized bed incinerator through a residual liquid tank. The combustion temperature is controlled at around 1100℃. Combustion within the furnace causes the residual liquid to decompose at high temperatures, producing CO2, H2O, N2, O2, SO2, and molten salt. In the high-temperature environment inside the furnace, the low-melting-point molten salt remains molten and flows down the vertical furnace wall. This molten salt exhibits severe corrosiveness, abrasiveness, and erosion of the furnace refractory materials, causing significant erosion of the lining. The existing system in this project uses a circulating fluidized bed incinerator to treat the residual liquid; however, the enthalpy of this residual liquid is relatively low, resulting in relatively high operating costs. A reduction method can be adopted, allowing concentrated residual liquid to re-enter the incineration system for combustion.

[0029] 3. Wet oxidation method:

[0030] Supercritical water oxidation (SCWO) utilizes supercritical water, which is water in a critical gas-liquid state at a temperature above 200℃ and a pressure of 2.0 MPa. At this point, it is a good solvent for organic components and is completely miscible with oxygen. In the presence of O2 or H2O2, it can rapidly degrade organic matter, RDX, and HMX, among others. The reaction does not involve a drastic increase in temperature and pressure, and the final products are nitrogen, CO2, and H2O. It is characterized by high efficiency and environmental friendliness, making it a very promising water treatment technology. SCWO uses supercritical water as a medium to oxidize and decompose organic matter. Supercritical water is an excellent solvent for both organic matter and oxygen; therefore, the oxidation of organic matter can proceed in an oxygen-rich homogeneous phase, and the reaction is not limited by interphase transfer. Simultaneously, because a large amount of heat is released during supercritical water oxidation, the reaction temperature rises, accelerating the reaction rate and enabling high degradation efficiency of organic matter in a shorter time.

[0031] Supercritical water oxidation (SCWO) is used to treat explosives-contaminated wastewater. SCWO can effectively decompose explosives contaminants in the presence of oxygen, with temperature, pressure, residence time, and excess oxygen being the main controlling factors. The decomposition of explosives contaminants accelerates with increasing temperature and residence time. The mechanism of supercritical water oxidation degradation of explosives contaminants is due to the excellent solubility of both organic matter and oxygen in supercritical water. The oxidation of explosives contaminants can proceed in an oxygen-rich homogeneous phase, and the reaction is not limited by interphase transfer. Simultaneously, supercritical water is a non-polar solvent, and the high temperature and abundant oxygen environment readily induce free radicals. It can be considered that the oxidative degradation reaction of explosives contaminants in supercritical water is mainly a free radical reaction. Free radicals can be generated by O2 attacking weak CH bonds in explosives contaminants, or by the interaction between O2 and supercritical water. Straight-chain open-ring products continue to decompose in an oxygen-rich environment until the final products CO2 and H2O are generated. Supercritical water oxidation is less likely to cause secondary pollution in the treatment of explosives wastewater, but it has relatively high equipment requirements, certain safety risks, and high costs, making it difficult to industrialize.

[0032] Therefore, there is an urgent need for a system and process that can uniformly process light components with high ammonia nitrogen, high COD, high acetic acid, and solvents. Summary of the Invention

[0033] The purpose of this invention is to provide a high ammonia nitrogen wastewater treatment system and process to overcome at least one of the above-mentioned defects in the prior art.

[0034] To achieve this objective, the present invention adopts the following technical solution:

[0035] The high ammonia nitrogen wastewater treatment system provided by this invention includes a first collection tank, an alkali preparation tank, a second collection tank, an ammonia stripping tower, an intermediate water tank, a triple-effect evaporator, and a mixing water tank, all connected sequentially by pipes. A third collection tank, a distillation tower, and a fourth collection tank are also connected sequentially by pipes. The tailwater discharge port of the distillation tower is connected to the mixing water tank, and the exhaust port of the ammonia stripping tower is connected to the absorption tower. The first collection tank is used to collect top water from the tower, the second collection tank is used to collect residual waste acid, and the third collection tank is used to collect residual solvent. The ammonia stripping tower includes a tower body, a condenser, a spray assembly, a packing layer, an anti-scaling assembly, a tray assembly, and a steam inlet pipe. A condenser is installed at the top of the tower body, and the exhaust port of the condenser is connected to the absorption tower. Inside the tower body, from top to bottom, are a spray assembly, a packing layer, and several tray assemblies. The spray assembly is connected to the drain port of the second collection tank. The anti-scaling assembly has several scrapers, and each tray assembly has a scraper on its upper side.

[0036] Preferably, the anti-scaling component further includes a motor, a first rotating shaft, a sealing box, a first sealing bearing seat, a first bevel gear, a second sealing bearing seat, a second bevel gear, and a first hollow rotating shaft. The motor is fixed to the outer wall of the tower body, one end of the sealing box is fixed to the inner wall of the tower body, the first sealing bearing seat is fixed to the right side wall inside the sealing box, the right end of the first rotating shaft is fixedly connected to the motor, the left end of the first rotating shaft passes through the right side wall of the tower body, the right side wall of the sealing box, and the first sealing bearing seat in sequence, and is fixed with the first bevel gear, the bottom wall inside the sealing box is fixed with the second sealing bearing seat, the upper part of the first hollow rotating shaft passes through the bottom wall of the sealing box and the second sealing bearing seat, and is fixed with the second bevel gear, the second bevel gear meshes with the first bevel gear, and several scrapers are fixed along the axial direction on the first hollow rotating shaft.

[0037] Preferably, the anti-scaling component further includes a first rotary joint, a first diverter pipe, and a first booster pump. The first diverter pipe is fixedly connected to the steam inlet pipe. The first diverter pipe extends into the tower body and passes through the sealed box. It is connected to the top of the first hollow rotating shaft through the first rotary joint. The first booster pump is installed on the first diverter pipe. The scraper has a cavity inside, which is connected to the first hollow rotating shaft. The side wall of the scraper has several air holes, which are inclined downwards.

[0038] Preferably, the tray assembly includes a perforated tray, a downcomer, and connecting rods. Connecting rods are fixed to both the left and right side walls inside the tower body. The curvature center of the perforated tray is located below the perforated tray. The cross-section of the perforated tray is arc-shaped. A downcomer is fixed to the bottom edge of the perforated tray. The bottom end of the downcomer is fixedly connected to the connecting rod. The perforation diameter of the perforated tray decreases sequentially from top to bottom.

[0039] Preferably, the orthographic projection of the perforated tray onto the bottom wall of the tower body is circular, there is a gap between the perforated tray and the tower body, and the scraper is arc-shaped and fits snugly against the tray.

[0040] Preferably, the spray assembly includes an inlet pipe, a second booster pump, a second diverter pipe, a first collecting disc, a second collecting disc, a slider, a second rotary joint, a third sealed bearing seat, a second hollow rotating shaft, a rotating plate, and an atomizing nozzle. The first collecting disc is fixed to the upper part of the tower body. One end of the inlet pipe is connected to the drain port of the second collecting tank, and the other end of the inlet pipe is fixedly connected to the first collecting disc. The second booster pump is installed on the inlet pipe. An annular groove is formed on the bottom wall of the first collecting disc. Two opposing sliders are slidably connected in the annular groove. The bottom of the sliders is fixed with the second collecting disc. A third sealed bearing seat is fixed to the top of the flow disc. The bottom end of the second hollow rotating shaft passes through the third sealed bearing seat and the first flow collecting disc in sequence and is fixedly connected to the second flow collecting disc. Several rotating plates are fixed inside the first flow collecting disc on the second hollow rotating shaft. The connection between the liquid inlet pipe and the first flow collecting disc is opposite to the rotating plate. The contact point between the second hollow rotating shaft and the first flow collecting disc is sealed. A second diverter pipe is fixedly connected to the liquid inlet pipe. The second diverter pipe extends into the tower body and is connected to the top end of the second hollow rotating shaft through a second rotary joint. Several atomizing nozzles are fixedly connected to the bottom of both the first and second flow collecting discs.

[0041] Preferably, the atomizing nozzles of the first collecting disk are distributed at equal intervals along the circumference of the first collecting disk, and the second collecting disk has three atomizing nozzles, and the center lines of the three atomizing nozzles form an equilateral triangle.

[0042] Preferably, it also includes a preheater, which is installed on the liquid inlet pipe.

[0043] This invention also provides a high ammonia nitrogen wastewater treatment process, which uses the above-mentioned high ammonia nitrogen wastewater treatment system and includes the following steps: the top water of the tower is sent to the first collection tank for collection, the collected top water of the tower enters the alkali preparation tank, alkali is added and then sent to the second collection tank, the waste acid residue is sent to the second collection tank and mixed with the top water of the tower after alkali preparation, and then sent to the ammonia stripping tower to separate ammonia and wastewater, the separated ammonia enters the absorption tower for treatment to recover 15%-20% of ammonia water, the separated wastewater enters the intermediate water tank, the wastewater stays in the intermediate water tank for a period of time and then is sent to the triple-effect evaporator for treatment, the resulting distillation residue is treated as general solid waste by an outsourced treatment agency, the generated condensate is sent to the mixing water tank, the solvent residue is sent to the third collection tank, the collected solvent residue is sent to the distillation tower for separation treatment, the separated heavy components are sent to the mixing water tank to mix and dilute with the condensate generated by the triple-effect evaporator, and the separated light components are sent to the fourth collection tank.

[0044] Preferably, the mixture of waste acid residue and top water is adjusted to pH 10-10.5 before being fed into the ammonia stripping tower.

[0045] The beneficial effects of this invention are as follows:

[0046] 1. A single system can comprehensively treat the overhead water, waste acid residue, and solvent residue generated during the distillation process. This not only solves the drawbacks of traditional separate treatment processes, but also integrates the treatment of the three wastewaters, resulting in low energy consumption, high efficiency, wide applicability, low operating costs, low investment costs, no secondary pollution, and minimal temperature sensitivity.

[0047] 2. By setting up anti-scaling components, the newly formed scale on the sieve plate is scraped off, achieving online descaling without stopping the machine. At the same time, mechanical descaling avoids a series of problems caused by chemical cleaning.

[0048] 3. A portion of the water vapor is fed into the first hollow rotating shaft through the first diverter pipe and the first rotary joint. It then enters the internal cavity of the scraper through the first hollow rotating shaft. During the scraping process, gas is blown out, making the descaling more thorough and efficient. Furthermore, the water vapor blown out from various heights further enhances the gas-liquid mass exchange and heat exchange, thereby further improving the ammonia stripping efficiency.

[0049] 4. The downward-sloping air holes ensure that the blown water vapor is directed downwards at an angle, which, combined with the rotating scraper, enhances the descaling effect. The addition of a first booster pump increases the pressure of the blown water vapor, further effectively removing dirt adhering to the perforated tray.

[0050] 5. By setting up the spray assembly, the water effluent from the second collection tank can be sprayed evenly and comprehensively onto the packing layer, improving the utilization rate of the packing layer and increasing the contact area between saturated steam and wastewater, resulting in more thorough mass exchange and heat exchange, and improving ammonia stripping efficiency.

[0051] 6. The system employs a fixed atomizing nozzle located on the first collecting disc, combined with a rotating atomizing nozzle located on the second collecting disc. This combination ensures comprehensive spraying coverage and significantly improves spray uniformity. Furthermore, the rotation is not driven by additional electricity, but rather by the impact force of the liquid delivered by the second booster pump on the rotating plate, causing the second hollow shaft to rotate—a clever design.

[0052] 7. By setting the position of the atomizing nozzles in this way, combined with fixed and rotating atomizing nozzles, the spraying is more comprehensive, and can even achieve coverage without dead angles, achieving the maximum spraying coverage with the least amount of atomizing nozzles required.

[0053] 8. The downcomer plates are connected via connecting rods on both sides, and a perforated tray is installed at the top of the downcomer plates, creating gaps around the perimeter of the perforated tray. This design allows for downcomer flow from all sides, and combined with the arc-shaped cross-section of the perforated tray, it facilitates better removal of scraped scale. During the scraping process, the scraper directly pushes out the scraped scale nearby, eliminating the need to push it all to one side for discharge, resulting in higher descaling efficiency. Attached Figure Description

[0054] Figure 1 This is a system block diagram of the present invention.

[0055] Figure 2 This is a schematic diagram of the ammonia stripping tower of the present invention.

[0056] Figure 3 This is a partial structural schematic diagram of the ammonia stripping tower of the present invention.

[0057] Figure 4 This is a partial cross-sectional view of the first hollow rotating shaft and scraper of the present invention.

[0058] Figure 5 This is a cross-sectional view of the scraper of the present invention from the left view direction.

[0059] Figure 6 This is a partial cross-sectional view of the spray assembly of the present invention.

[0060] Figure 7 This is a top-view cross-sectional structural diagram of the first flow-collecting disk of the present invention.

[0061] Figure 8 This is a bottom view of the structure of the first collector disk, the second collector disk, and the atomizing nozzle of the present invention.

[0062] The labels in the attached diagram are as follows: 1-First collecting tank, 2-Ammonia stripping tower, 3-Alkali preparation tank, 4-Second collecting tank, 5-Intermediate water tank, 6-Triple-effect evaporator, 7-Mixed water tank, 8-Third collecting tank, 9-Distillation tower, 10-Fourth collecting tank, 21-Tower body, 22-Condenser, 23-Spray assembly, 24-Packing layer, 25-Anti-scaling assembly, 26-Tower tray assembly, 27-Steam inlet pipe, 251-Motor, 252-First rotating shaft, 253-Sealed box, 254-First sealed bearing seat, 255-First bevel gear, 256-Second sealed bearing seat, 257-Second bevel gear, 258-First hollow rotating shaft, 25... 9-First rotary joint, 2510-First diverter pipe, 2511-First booster pump, 2512-Scraper, 2513-Cavity, 2514-Vent, 261-Sieve tray, 262-Downcomer plate, 263-Connecting rod, 29-Gap, 231-Inlet pipe, 232-Second booster pump, 233-Second diverter pipe, 234-First collecting disc, 235-Second collecting disc, 236-Slider, 237-Second rotary joint, 238-Third sealing bearing seat, 239-Second hollow shaft, 2310-Rotating plate, 2311-Atomizing nozzle, 2312-Annular chute, 210-Preheater, 11-Absorption tower. Detailed Implementation

[0063] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0064] Contents not described in detail in this specification are prior art known to those skilled in the art. In the description of this invention, it should be understood that terms such as "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, terms such as "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0065] like Figures 1 to 8As shown, the high ammonia nitrogen wastewater treatment system provided in this embodiment includes a first collection tank 1, an alkali preparation tank 3, a second collection tank 4, an ammonia stripping tower 2, an intermediate water tank 5, a triple-effect evaporator 6, and a mixing water tank 7, all connected sequentially by pipelines. A third collection tank 8, a distillation tower 9, and a fourth collection tank 10 are also connected sequentially by pipelines. The tailwater discharge port of the distillation tower 9 is connected to the mixing water tank 7, and the exhaust port of the ammonia stripping tower is connected to the absorption tower 11. The first collection tank 1 is used to collect top water from the tower, the second collection tank 4 is used to collect residual waste acid, and the third collection tank 8 is used to collect residual solvent. The ammonia stripping tower 2 includes a tower body 21, a condenser 22, a spray assembly 23, a packing layer 24, an anti-scaling assembly 25, a tray assembly 26, and a steam inlet pipe 27. The top of the tower body 21 is equipped with a condenser 22, and the exhaust port of the condenser 22 is connected to the absorption tower. The interior of the tower body 21 is equipped with a spray assembly 23, a packing layer 24, and several tray assemblies 26 arranged sequentially from top to bottom. The spray assembly 23 is connected to the drain port of the second collection tank 4. The anti-scaling assembly 25 has several scrapers 2512, and each tray assembly 26 has a scraper 2512 on its upper side.

[0066] The influent water quality of the top water, waste acid residue, and solvent residue in this embodiment is shown in Table 1:

[0067] name Water at the top of the tower Waste acid residue Solvent residue Acidity (%, calculated as acetic acid) 3 25 7 Ammonia nitrogen (mg / L) 18000 45000 2000 COD (mg / L) 40000 60000 200000 Total nitrogen (mg / L) 21000 60000 3000 <![CDATA[Water volume (m 3 / d)]]> 20 60 25

[0068] Table 1

[0069] The effluent quality of the treated top water, waste acid residue, and solvent residue in this embodiment is shown in Table 2:

[0070]

[0071] Table 2

[0072] This invention provides a comprehensive system for the treatment of overhead water, waste acid residue, and solvent residue generated during distillation. It not only overcomes the drawbacks of traditional separate treatment processes but also integrates the three wastewater components, resulting in low energy consumption, high efficiency, wide applicability, low operating costs, low investment costs, no secondary pollution, and minimal temperature sensitivity. The spray assembly 23 ensures that the effluent from the second collection tank 4 is evenly and comprehensively sprayed onto the packing layer 24, improving the utilization rate of the packing layer 24 and increasing the contact area between saturated steam and wastewater, leading to more thorough mass and heat exchange and improved ammonia stripping efficiency.

[0073] The anti-scaling component 25 includes a motor 251, a first rotating shaft 252, a sealing box 253, a first sealing bearing seat 254, a first bevel gear 255, a second sealing bearing seat 256, a second bevel gear 257, and a first hollow rotating shaft 258. The motor 251 is fixed to the outer wall of the tower body 21. One end of the sealing box 253 is fixed to the inner wall of the tower body 21. The first sealing bearing seat 254 is fixed to the right side wall inside the sealing box 253. The right end of the first rotating shaft 252 is fixedly connected to the motor 251, and the left end of the first rotating shaft 252 passes through the tower body in sequence. The right side wall of tower body 21, the right side wall of sealing box 253, and the first sealing bearing seat 254 are all sealed together, and a first bevel gear 255 is fixed thereon. A first rotating shaft 252 is sealed to tower body 21. A second sealing bearing seat 256 is fixed to the bottom wall inside sealing box 253. The upper part of the first hollow rotating shaft 258 passes through the bottom wall of sealing box 253 and the second sealing bearing seat 256, and a second bevel gear 257 is fixed thereon. The second bevel gear 257 meshes with the first bevel gear 255. Several scrapers 2512 are fixed along the axial direction of the first hollow rotating shaft 258. The first rotating shaft 252 and the first hollow rotating shaft 258 are sealed at the sealing connection. The rotation of motor 251 drives the first rotating shaft 252, which in turn drives the first bevel gear 255, which in turn drives the second bevel gear 257, causing the first hollow rotating shaft 258 to rotate. This, in turn, drives the scraper 2512 to rotate, scraping away the newly formed dirt on the perforated tower plate 261, achieving online descaling without stopping the machine. Mechanical descaling also avoids a series of problems associated with chemical cleaning. The cooperation of the first bevel gear 255 and the second bevel gear 257 prevents motor 251 from directly driving the first hollow rotating shaft 258. This facilitates the connection between the top of the first hollow rotating shaft 258 and the first rotary joint 259. If the top of the first hollow rotating shaft 258 were directly connected to the motor 251, the motor 251 could not be directly installed inside the tower body 21. This would require the first hollow rotating shaft 258 to penetrate the packing layer 24, the spray assembly 23, and then exit the top of the tower, necessitating changes to the structure and placement of the packing layer 24, the spray assembly 23, and the condenser 22.

[0074] The anti-scaling component 25 also includes a first rotary joint 259, a first diversion pipe 2510, and a first booster pump 2511. The first diversion pipe 2510 is fixedly connected to the steam inlet pipe 27. The first diversion pipe 2510 extends into the tower body 21 and passes through the sealing box 253. The contact point between the first diversion pipe 2510 and the sealing box 253 is sealed. It is connected to the top end of the first hollow rotating shaft 258 through the first rotary joint 259. The first booster pump 2511 is installed on the first diversion pipe 2510. The scraper 2512 has a cavity 2513 inside, which is connected to the first hollow rotating shaft 258. The side wall of the scraper 2512 has several air holes 2514, which are inclined downwards. A portion of the water vapor is fed into the first hollow rotating shaft 258 through the first diverter pipe 2510 and the first rotary joint 259. It then enters the internal cavity 2513 of the scraper 2512 through the first hollow rotating shaft 258. During the scraping process of the scraper 2512, gas is blown out, making descaling more thorough and efficient. Furthermore, the water vapor blown out from various heights further enhances gas-liquid mass exchange and heat transfer, further improving ammonia stripping efficiency. The downwardly inclined air holes 2514 ensure that the blown water vapor is directed downwards, which, combined with the rotating scraper 2512, further improves the descaling effect. The first booster pump 2511 increases the pressure of the blown water vapor, more effectively removing the dirt adhering to the perforated tray 261.

[0075] The tray assembly 26 includes a perforated tray 261, a downcomer 262, and a connecting rod 263. The connecting rod 263 is fixed to both the left and right side walls inside the tower body 21. The curvature center of the perforated tray 261 is located below the perforated tray 261. The cross-section of the perforated tray 261 is arc-shaped. The downcomer 262 is fixed to the bottom edge of the perforated tray 261. The bottom end of the downcomer 262 is fixedly connected to the connecting rod 263. The orthographic projection of the perforated tray 261 onto the bottom wall of the tower body 21 is circular. There is a gap 29 between the perforated tray 261 and the tower body 21. The scraper 2512 is arc-shaped and fits against the tray. Compared to the traditional tray configuration where one end is fixed to the inner wall of the tower body 21 and the other end has a gap 29 between it and the tower body 21, this invention connects a downcomer plate 262 to the left and right sides via connecting rods 263. A perforated tray 261 is then installed at the top of the downcomer plate 262, creating gaps 29 around the perforated tray 261. This configuration allows for downcomering from all sides, and the arc-shaped cross-section of the perforated tray 261 further facilitates the removal of scraped scale. During the scraping process, the scraper 2512 directly pushes out the scraped scale nearby, eliminating the need to push it all the way to the gap 29 on one side, resulting in higher descaling efficiency. Because the aperture of the perforated tray 261 decreases sequentially from top to bottom, it prevents scale from contacting lower layers and gradually increasing in size, significantly improving descaling efficiency.

[0076] The spray assembly 23 includes an inlet pipe 231, a second booster pump 232, a second diverter pipe 233, a first collecting disc 234, a second collecting disc 235, a slider 236, a second rotary joint 237, a third sealed bearing seat 238, a second hollow rotating shaft 239, a rotating plate 2310, and an atomizing nozzle 2311. The first collecting disc 234 is fixed to the upper part of the tower body 21. One end of the inlet pipe 231 is connected to the drain port of the second collection tank 4, and the other end of the inlet pipe 231 is fixedly connected to the first collecting disc 234. The second booster pump 232 is installed on the inlet pipe 231. An annular groove 2312 is opened on the bottom wall of the first collecting disc 234. Two opposing sliders 236 are slidably connected in the annular groove 2312. The bottom of the sliders 236 is fixed with the second collecting disc 235, and the top of the first collecting disc 234 is... The second hollow rotating shaft 239 is fixedly provided with a third sealed bearing seat 238. The bottom end of the second hollow rotating shaft 239 passes through the third sealed bearing seat 238 and the first collecting disc 234 in sequence and is fixedly connected to the second collecting disc 235. Several rotating plates 2310 are fixedly provided inside the first collecting disc 234. The connection between the liquid inlet pipe 231 and the first collecting disc 234 is opposite to the rotating plate 2310. The contact point between the second hollow rotating shaft 239 and the first collecting disc 234 is sealed. A second diverter pipe 233 is fixedly connected to the liquid inlet pipe 231. The second diverter pipe 233 extends into the tower body 21 and is connected to the top end of the second hollow rotating shaft 239 through a second rotary joint 237. The contact point between the second diverter pipe 233 and the tower body 21 is sealed. Several atomizing nozzles 2311 are fixedly connected to the bottom of both the first collecting disc 234 and the second collecting disc 235. Part of the water emanating from the second collecting tank 4 enters the first collecting disc 234 through the inlet pipe 231 and is atomized and sprayed out by the atomizing nozzles 2311 on the first collecting disc 234; the other part enters the second hollow rotating shaft 239 through the second diverting pipe 233, then enters the second collecting disc 235 through the second hollow rotating shaft 239, and finally is atomized and sprayed out by the atomizing nozzles 2311 on the second collecting disc 235. When the water flows into the first collecting disc 234, it pushes the rotating plate 2310 to rotate, causing the second hollow rotating shaft 239 to rotate, which in turn drives the second collecting disc 235 to rotate, causing the atomizing nozzles 2311 on it to spray atomized liquid while rotating. By using a fixed atomizing nozzle 2311 located on the first collecting disc 234 in combination with a rotating atomizing nozzle 2311 located on the second collecting disc 235, the combination of the two ensures a comprehensive spray range and greatly improves the uniformity of spraying. Furthermore, the rotational power is not driven by additional electricity, but by the impact force of the liquid delivered by the second booster pump 232 on the rotating plate 2310, which causes the second hollow rotating shaft 239 to rotate, a clever design.

[0077] In this configuration, the atomizing nozzles 2311 of the first collecting disc 234 are evenly spaced along its circumference. The second collecting disc 235 has three atomizing nozzles 2311, and the center lines of these three nozzles form an equilateral triangle. This arrangement of the atomizing nozzles 2311, combined with both fixed and rotating nozzles, ensures more comprehensive spraying, even achieving coverage without blind spots, thus maximizing spray coverage with minimal nozzle usage.

[0078] This also includes a preheater 210, which is installed on the liquid inlet pipe 231. Preheating is performed through the preheater 210.

[0079] This embodiment also provides a high ammonia nitrogen wastewater treatment process, which uses the above-mentioned high ammonia nitrogen wastewater treatment system for treatment, including the following steps:

[0080] The overhead water is collected in the first collection tank 1. The collected overhead water then enters the alkali preparation tank, where alkali is added before being sent to the second collection tank 4. Waste acid residue is also sent to the second collection tank 4 and mixed with the alkali-prepared overhead water. The pH of the mixture is adjusted to 10 before being sent to the ammonia stripping tower 2. The ammonia and wastewater are then separated in the ammonia stripping tower. The separated ammonia gas enters the absorption tower for treatment, achieving a concentration of up to 95%, recovering 15%-20% of the ammonia water. The separated wastewater enters the intermediate water tank 5, where it remains for a period of time. After a period of time, the attached substances scraped off by the ammonia stripping tower 2 settle, and the supernatant is sent to the triple-effect evaporator 6 for treatment. The resulting distillation residue is treated as general solid waste and outsourced. The generated condensate is sent to the mixing tank 7, and the solvent residue is sent to the third collection tank 8. The collected solvent residue is sent to the distillation tower 9 for separation treatment. The separated heavy components, which are mainly water, are sent to the mixing tank 7 and mixed with the condensate generated by the triple-effect evaporator 6 for dilution before being discharged to the No. 5 Chemical Plant for further treatment. The separated light components are sent to the fourth collection tank 10 and then transferred to the No. 271 boiler for combustion treatment.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high ammonia nitrogen wastewater treatment system, characterized in that: It includes a first collection tank, an alkali preparation tank, a second collection tank, an ammonia stripping tower, an intermediate water tank, a triple-effect evaporator, and a mixing water tank, which are connected in sequence by pipelines. The third collection tank, the distillation column, and the fourth collection tank are connected in sequence by pipelines; The tailwater discharge port of the distillation column is connected to the mixing tank; The exhaust port of the ammonia stripping tower is connected to the absorption tower; The first collection tank is used to collect water from the top of the tower, the second collection tank is used to collect waste acid residue, and the third collection tank is used to collect solvent residue. The ammonia stripping tower includes a tower body, a condenser, a spray assembly, a packing layer, an anti-scaling assembly, a tower plate assembly, and a steam inlet pipe. A condenser is provided at the top of the tower body, and the exhaust port of the condenser is connected to the absorption tower. The interior of the tower body is provided with a spray assembly, a packing layer, and several tower plate assemblies from top to bottom. The spray assembly is connected to the drain port of the second collection tank; The anti-scaling component has several scrapers, and each of the tray components has one scraper on its upper side. The anti-scaling assembly also includes a motor, a first rotating shaft, a sealing box, a first sealed bearing housing, a first bevel gear, a second sealed bearing housing, a second bevel gear, a first hollow rotating shaft, a first rotary joint, a first diverter pipe, and a first booster pump; A motor is fixed to the outer wall of the tower body, one end of the sealing box is fixed to the inner wall of the tower body, a first sealing bearing seat is fixed to the right side wall inside the sealing box, the right end of the first rotating shaft is fixedly connected to the motor, and the left end of the first rotating shaft passes through the right side wall of the tower body, the right side wall of the sealing box and the first sealing bearing seat in sequence, and is fixed with a first bevel gear. The bottom wall inside the sealed box is fixed with a second sealed bearing seat. The upper part of the first hollow rotating shaft passes through the bottom wall of the sealed box and the second sealed bearing seat, and is fixed with a second bevel gear. The second bevel gear meshes with the first bevel gear. The first hollow rotating shaft has several scrapers fixed along its axial direction; A first branch pipe is fixedly connected to the steam inlet pipe. The first branch pipe extends into the tower body and passes through the sealed box. It is connected to the top of the first hollow rotating shaft through the first rotary joint. A first booster pump is installed on the first diversion pipe; The scraper has a cavity inside, which is connected to the first hollow rotating shaft. The side wall of the scraper has a number of air holes, which are inclined downwards.

2. The high ammonia nitrogen wastewater treatment system according to claim 1, characterized in that: The tray assembly includes a perforated tray, a downcomer, and a connecting rod; The left and right side walls inside the tower body are both fixed with connecting rods; The curvature center of the perforated tray is located below the perforated tray. The cross-section of the perforated tray is arc-shaped. A downcomer is fixed to the bottom edge of the perforated tray. The bottom end of the downcomer is fixedly connected to the connecting rod. The sieve aperture diameter of the perforated trays decreases sequentially from top to bottom.

3. The high ammonia nitrogen wastewater treatment system according to claim 2, characterized in that: The perforated tray has a circular shape when projected onto the bottom wall of the tower body, and there is a gap between the perforated tray and the tower body. The scraper is arc-shaped and fits into the tray.

4. The high ammonia nitrogen wastewater treatment system according to claim 1, characterized in that: The spray assembly includes an inlet pipe, a second booster pump, a second diverter pipe, a first collector disc, a second collector disc, a slider, a second rotary joint, a third sealed bearing seat, a second hollow rotating shaft, a rotating plate, and an atomizing nozzle; The first collecting disc is fixed above the interior of the tower body. One end of the liquid inlet pipe is connected to the drain port of the second collecting tank, and the other end of the liquid inlet pipe is fixedly connected to the first collecting disc. A second booster pump is installed on the liquid inlet pipe. The bottom wall of the first collecting disk is provided with an annular groove, and two opposing sliders are slidably connected in the annular groove. The bottom of the sliders is fixed with a second collecting disk. The top of the first collecting disc is fixed with a third sealed bearing seat. The bottom end of the second hollow rotating shaft passes through the third sealed bearing seat and the first collecting disc in sequence and is fixedly connected to the second collecting disc. The second hollow rotating shaft has several rotating plates fixed inside the first collecting disc. The connection between the liquid inlet pipe and the first collecting disc is opposite to the rotating plates. The contact point between the second hollow rotating shaft and the first collecting disc is sealed. A second diversion pipe is fixedly connected to the inlet pipe. The second diversion pipe extends into the tower body and is connected to the top end of the second hollow rotating shaft through the second rotary joint. The bottom of both the first and second collector disks is fixedly connected to several atomizing nozzles.

5. The high ammonia nitrogen wastewater treatment system according to claim 4, characterized in that: The atomizing nozzles of the first collecting disk are distributed at equal intervals along the circumference of the first collecting disk; The second collector disk has three atomizing nozzles, and the center lines of the three atomizing nozzles form an equilateral triangle.

6. The high ammonia nitrogen wastewater treatment system according to claim 4, characterized in that: It also includes a preheater, which is installed on the liquid inlet pipe.

7. A high-ammonia nitrogen wastewater treatment process, characterized in that, The treatment of high ammonia nitrogen wastewater using the high ammonia nitrogen wastewater treatment system according to any one of claims 1-6 includes the following steps: The top water from the tower is collected in the first collection tank. The collected top water then enters the alkali preparation tank, where alkali is added before being sent to the second collection tank. The waste acid residue is also sent to the second collection tank and mixed with the top water after alkali preparation. This mixture is then sent to the ammonia stripping tower to separate ammonia and wastewater. The separated ammonia is sent to the absorption tower for treatment, recovering 15%-20% of the ammonia. The separated wastewater enters the intermediate water tank and, after a period of time, is sent to the triple-effect evaporator for treatment. The resulting distillation residue is treated as general solid waste and outsourced. The resulting condensate is sent to the mixing tank, and the solvent residue is sent to the third collection tank. The collected solvent residue is then sent to the distillation tower for separation. The separated heavy components are sent to the mixing tank and mixed with the condensate from the triple-effect evaporator for dilution. The separated light components are sent to the fourth collection tank.

8. The high ammonia nitrogen wastewater treatment process according to claim 7, characterized in that: The pH of the mixture of waste acid residue and top water is adjusted to 10-10.5 before being sent to the ammonia stripping tower.

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