Device and method for treating high-concentration ammonia nitrogen in condensate of coal chemical enterprise

Abstract

The invention discloses a high-concentration ammonia nitrogen treatment device and method for condensate of a coal chemical enterprise. The high-concentration ammonia nitrogen treatment device comprises a raw water storage system, a pretreatment system, an ammonia stripping system, an ammonia gas recovery system, a post-treatment system and an automatic control system, the raw water storage system, the pretreatment system, the ammonia stripping system, the ammonia gas recovery system and the post-treatment system are connected in sequence; the automatic control system is respectively connected with the raw water storage system, the pretreatment system, the ammonia stripping system, the ammonia gas recovery system and the post-treatment system. By adopting the technical scheme, the effects of remarkably reducing energy consumption, realizing resource utilization, being low in investment cost, low in operation cost, profitable, high and stable in treatment efficiency, high in automation degree, small in occupied area, capable of eliminating secondary pollution, high in adaptability, simple and convenient to maintain and short in investment payback period can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial wastewater treatment, and more particularly to a device and method for treating high-concentration ammonia nitrogen in condensate from a coal chemical enterprise. BACKGROUND

[0002] The condensate from a coal chemical enterprise of a petroleum chemical enterprise is a typical high-concentration ammonia nitrogen wastewater (ammonia nitrogen concentration is usually 15,000-25,000 mg / L), with an alkaline pH value (9-10) and a certain amount of organic matter (COD 2,000-5,000 mg / L). If such wastewater is directly discharged without treatment, it will cause serious pollution to the environment.

[0003] Currently, the methods for treating high-concentration ammonia nitrogen wastewater in the prior art mainly include: 1. Biological denitrification method Disadvantages: ammonia nitrogen concentration is too high to inhibit microbial activity, a large amount of dilution is required, the treatment cycle is long, the occupied area is large, and the operation is unstable.

[0004] 2. Chemical precipitation method (MAP method) Disadvantages: high cost of reagents (phosphate and magnesium salt need to be added), a large amount of chemical sludge is generated, and the treatment cost is as high as 50-80 yuan / m³.

[0005] 3. Breakpoint chlorination method Disadvantages: large consumption of chlorine, high treatment cost, generation of toxic by-products, and safety hazards.

[0006] 4. Traditional ammonia stripping method Disadvantages: although the process is simple, the following problems exist: External heating is required, and the energy consumption is high (usually heated to 60-80℃); The stripped ammonia gas is directly discharged, causing secondary pollution and resource waste; Lack of intelligent control, and difficulty in adjusting operating parameters; Efficiency significantly decreases in winter low-temperature environment; 5. Common problems of existing technologies High investment cost (usually 1.5-3 million yuan); High operating cost (treatment cost 15-30 yuan / m³); Cannot realize ammonia resource recycling; Complex equipment, difficult to maintain; Secondary pollution problem has not been effectively solved.

[0007] For the high-concentration ammonia-nitrogen wastewater treatment problem to be solved by the present application, the prior art has defects such as high energy consumption, high cost, resource waste, secondary pollution, and is difficult to meet the actual needs of economic and environmental protection. SUMMARY

[0008] Therefore, the present application provides a coal chemical enterprise condensate high-concentration ammonia-nitrogen treatment device and treatment method to solve the following technical problems: Reduce energy consumption: through the waste heat utilization system, make full use of the existing steam or hot water resources of the factory, reduce the heating energy consumption by 30-40%; Realize resource utilization: the ammonia gas blown out is prepared into ammonium sulfate product through the absorption tower, turning waste into treasure, and realizing economic benefit; Eliminate secondary pollution: through the high-efficiency ammonia gas recovery system, the ammonia gas recovery rate reaches more than 98%, avoiding air pollution; Improve the degree of automation: adopt intelligent control system to automatically adjust the key parameters such as pH, temperature, gas-water ratio, etc., realize unattended operation; Reduce investment and operating cost: through process optimization and modular design, the total investment is controlled within 900,000 yuan, the operating cost is reduced to 7-10 yuan / m³, and profit operation is realized through ammonia recovery; Improve the treatment efficiency: optimize the structure and filler configuration of the blow-off tower, so that the ammonia-nitrogen removal rate is stably above 95%, and the effluent ammonia-nitrogen is ≤250mg / L; Enhance the stability of the system: adopt multi-stage control and safety interlocking to ensure the stable operation of the system under various working conditions.

[0009] In order to achieve the above purpose, the present application adopts the following technical scheme: A coal chemical enterprise condensate high-concentration ammonia-nitrogen treatment device, comprising: a raw water storage system, a pretreatment system, an ammonia blow-off system, an ammonia gas recovery system, a post-treatment system and an automatic control system; The raw water storage system, the pretreatment system, the ammonia blow-off system, the ammonia gas recovery system and the post-treatment system are connected in sequence; The automatic control system is connected with the raw water storage system, the pretreatment system, the ammonia blow-off system, the ammonia gas recovery system and the post-treatment system respectively.

[0010] Preferably, the raw water storage system comprises a first raw water storage tank and a second raw water storage tank connected in sequence.

[0011] Preferably, the pretreatment system comprises a pH adjusting tank and a waste heat utilization preheating system; The waste heat utilization preheating system comprises a plate heat exchanger, a temperature sensor, an automatic adjusting valve and a steam distribution pipeline; The cold side inlet of the plate heat exchanger is connected with the outlet of the pH regulating tank, and the cold side outlet of the plate heat exchanger is connected with an ammonia stripping system; The steam distribution pipeline is connected with the hot side inlet of the plate heat exchanger through the automatic regulating valve, and the hot side outlet of the plate heat exchanger is provided with a condensed water discharge pipeline; The temperature sensor is arranged on the cold side outlet pipeline of the plate heat exchanger and used for detecting the temperature of the preheated wastewater; The automatic regulating valve adjusts the steam flow according to the detection signal of the temperature sensor.

[0012] Preferably, the ammonia stripping system comprises an ammonia stripping tower; The ammonia stripping tower comprises a tower body, a filler layer, a liquid distributor, a filler support, a mist eliminator, a water inlet, a water outlet, an air inlet, an air outlet and a manhole; The filler layer, the liquid distributor, the filler support and the mist eliminator are arranged inside the tower body, and are arranged in the order of the mist eliminator, the liquid distributor, the filler layer and the filler support from top to bottom; The air outlet is arranged at the top of the tower body, the air inlet is arranged at the bottom of the tower body, the water inlet is arranged on the upper part of the side wall of the tower body, the water outlet is arranged on the lower part of the side wall of the tower body, and the manhole is arranged in three, and is arranged on the side wall of the tower body from top to bottom; The water inlet is connected with the cold side outlet of the plate heat exchanger; The air blower is connected with the air inlet.

[0013] Preferably, the ammonia gas recovery system comprises an ammonia gas absorption tower, a filler, a circulating pump, a circulating tank, a sulfuric acid storage tank, a spraying device, a product storage tank and a product neutralization device; The filler and the spraying device are arranged inside the ammonia gas absorption tower, and the spraying device is arranged above the filler; One end of the circulating pump is connected with the top of the ammonia gas absorption tower, and the other end is connected with the circulating tank, and the circulating tank is further connected with the product storage tank, the sulfuric acid storage tank and the bottom of the ammonia gas absorption tower respectively; The product neutralization device is arranged on the tail gas outlet pipeline of the ammonia gas absorption tower and used for neutralizing unabsorbed acid gas; The ammonia gas absorption tower is connected with the ammonia stripping tower.

[0014] Preferably, the post-treatment system comprises: a neutralization tank, an acid adding device, a flocculation and precipitation tank, a chemical adding device and a water outlet tank; The water inlet of the neutralization tank is connected with the water outlet of the ammonia stripping tower, and the water outlet of the neutralization tank is connected with the water inlet of the flocculation and precipitation tank; The acid adding device comprises an acid liquid storage tank, an acid adding pump and an acid adding pipeline, and the acid liquid storage tank is connected with the neutralization tank through the acid adding pump and the acid adding pipeline. The medicine adding device comprises a PAC storage tank, a PAM storage tank, a medicine adding pump and a medicine adding pipeline, and the PAC storage tank and the PAM storage tank are respectively connected with the flocculation and precipitation tank. The water outlet of the flocculation and precipitation tank is connected with the water outlet tank.

[0015] Preferably, the automatic control system comprises a PLC controller, a touch screen HMI, online monitoring instruments, an actuating mechanism and an alarm system. The online monitoring instruments comprise a pH meter, a thermometer, a flow meter, a liquid level meter and an ammonia nitrogen analyzer. The actuating mechanism comprises a frequency converter, an electric regulating valve and an electromagnetic valve. The alarm system comprises a light alarm and a short message alarm module. The pH meter is respectively arranged in the pH adjusting tank, the neutralization tank and the ammonia gas absorption tower, and is connected with the PLC controller through a signal line. The thermometer is arranged at the outlet of the plate heat exchanger, and is connected with the PLC controller through a signal line. The flow meter is respectively arranged in the water inlet pipeline, the medicine adding pipeline and the outlet of the air blower, and is connected with the PLC controller through a signal line. The liquid level meter is respectively arranged in the first raw water storage tank, the second raw water storage tank, the sulfuric acid storage tank, the product storage tank, the acid liquid storage tank, the PAC storage tank, the PAM storage tank, the pH adjusting tank, the neutralization tank, the flocculation and precipitation tank and the water outlet tank, and is connected with the PLC controller through a signal line. The actuating mechanism comprises a frequency converter, an electric regulating valve and an electromagnetic valve, and is respectively connected with the PLC controller through a control line, for controlling corresponding pumps, air blowers and valves. The alarm system comprises an audible and light alarm and a short message alarm module, and is connected with the PLC controller.

[0016] Furthermore, in the present application: Plate heat exchanger: heat transfer area 50 m 2 , material 316L stainless steel; Temperature sensor: measurement range 0-100℃, accuracy ±0.5℃; Automatic regulating valve: electric regulating valve, regulating ratio 50:1; Steam distribution pipeline: DN50 seamless steel pipe with insulation layer; Work flow: raw water is delivered to one side of the plate heat exchanger by the water inlet pump, and the factory waste heat steam (0.3-0.5MPa) or hot water (80-90℃) enters the other side of the heat exchanger through the pipeline, and the raw water is heated to 45-55℃ by the plate heat exchanger and then enters the stripping tower.

[0017] Working principle: the existing low-pressure steam or hot water in the factory is used as a heat source to indirectly heat through the plate heat exchanger. The temperature sensor monitors the outlet water temperature in real time, and when the temperature is lower than the set value, the PLC control system automatically opens the steam regulating valve to increase the heat input; when the temperature is higher than the set value, the regulating valve is automatically closed to reduce the heat input, so as to realize accurate temperature control.

[0018] Technical effect: compared with the traditional steam direct heating method, the waste heat utilization system can reduce the energy consumption by 30-40%, and save about 130,000 yuan of steam cost per year.

[0019] Further, the ammonia stripping system comprises an ammonia stripping tower; The ammonia stripping tower comprises a tower body, a filler layer, a liquid distributor, a filler support, a mist eliminator, a water inlet, a water outlet, an air inlet, an air outlet and a manhole; The filler layer, the liquid distributor, the filler support and the mist eliminator are arranged inside the tower body; from top to bottom, they are the mist eliminator, the liquid distributor, the filler layer and the filler support; The air inlet is arranged at the top of the tower body, the air outlet is arranged at the bottom of the tower body, the water inlet is arranged on the upper part of the side wall of the tower body, the water outlet is arranged on the lower part of the side wall of the tower body, and the manhole is arranged with three manholes arranged on the side wall of the tower body from top to bottom; The water inlet is connected with the plate heat exchanger.

[0020] Further, in the present application: Tower body: φ1500mm*10000mm, material Q235B+epoxy glass flake corrosion protection; Filler layer: PP Paul ring φ25mm, filler layer height 6000mm; Liquid distributor: water shower plate type, 304 stainless steel material, hole diameter φ3mm, hole distance 30mm; Filler support: 304 stainless steel hole plate, porosity 60%; Mist eliminator: wire mesh mist eliminator, mist elimination efficiency ≥99%; Water inlet: DN80, located above the liquid distributor on the upper part of the tower; Water outlet: DN80, located at the bottom of the tower; Air inlet: DN300, located at the center of the bottom of the tower; Air outlet: DN400, located at the top center of the tower; Manhole: φ600mm, located at the upper, middle and lower positions of the tower body respectively; Work flow: The preheated raw water enters from the water inlet at the top of the tower, is uniformly distributed by the liquid distributor, and then sprinkles on the top of the filler layer and flows down along the filler layer; air is blown into the tower from the air inlet at the bottom of the tower by the air blower, is uniformly distributed by the gas distributor, and then contacts with the liquid in countercurrent in the filler layer from bottom to top; the stripped ammonia gas rises with the airflow, removes the carried water mist by the demister, and then is discharged from the air outlet at the top of the tower into the ammonia gas recovery system; the ammonia-removed water is discharged from the water outlet at the bottom of the tower into the post-treatment system.

[0021] Working principle: According to the gas-liquid equilibrium principle of ammonia, under alkaline conditions (pH 10.5-11.5), the ammonium ion (NH4 + ) in the wastewater is converted into free ammonia (NH3), and the free ammonia is transferred from the liquid phase to the gas phase at the gas-liquid interface. By increasing the gas-liquid contact area (provided by the filler), increasing the temperature (accelerating the mass transfer rate), and increasing the gas-water ratio (providing sufficient gas-phase mass transfer driving force), efficient mass transfer of ammonia from the liquid phase to the gas phase is realized, so as to achieve the purpose of removing ammonia nitrogen.

[0022] Key process parameters: Gas-water ratio: 4500:1 (air volume 45,000 m 3 / h, liquid volume 10 m 3 / h); Operating temperature: 50±5℃; Operating pH value: 10.5-11.5; Liquid surface load: 3 m 3 / (m 3 ·h); Residence time: 2.5 hours; Ammonia removal efficiency: ≥95%.

[0023] Technical effect: By optimizing the filler type, filler layer height, gas-water ratio and other parameters, the stripping tower of the present application can achieve an ammonia removal efficiency of more than 95% at a lower energy consumption, reducing the ammonia nitrogen from 20,000 mg / L to less than 1,000 mg / L.

[0024] Further, the ammonia gas recovery system comprises an ammonia gas absorption tower, a filler, a circulating pump, a circulating tank, a sulfuric acid storage tank, a spraying device, a product storage tank and a product neutralization device; The filler and the spraying device are arranged inside the ammonia gas absorption tower, and the spraying device is located above the filler; The circulating pump is connected with the top of the ammonia absorption tower at one end and connected with the circulating tank at the other end, and the circulating tank is also connected with the product storage tank, the sulfuric acid storage tank and the bottom of the ammonia absorption tower respectively. The ammonia absorption tower is connected with the ammonia stripping tower.

[0025] Furthermore, in the present application: Ammonia absorption tower: φ800mmx6000mm, material 316L stainless steel; Packing: ceramic Rasching ring φ25mm, packing layer height 4000mm; Sulfuric acid storage tank: 5m 3 , PE material, storing 98% sulfuric acid; Product storage tank: 10m 3 , PE material, storing 20% ammonium sulfate solution; Acid-base neutralization device: pH monitoring + NaOH feeding system; Connection relationship: ammonia gas (containing 3-5% ammonia) discharged from the top of the stripping tower enters the bottom of the absorption tower through a pipeline; 10% dilute sulfuric acid is sprayed from the top of the absorption tower and flows down in the packing layer to contact the rising ammonia gas in countercurrent; the acid liquid (ammonium sulfate solution) that has absorbed ammonia is discharged from the bottom of the tower into the circulating tank, part of which is circulated back to the top of the tower for further absorption, and part of which is discharged into the product storage tank; the tail gas (containing <0.1% ammonia) that is not absorbed is discharged through the top of the tower and is further treated by the alkali washing tower before being discharged.

[0026] Working principle: ammonium sulfate is prepared by using the acid-base neutralization reaction of ammonia and sulfuric acid: 2NH3+ H2SO4→ (NH4)2SO4.

[0027] Ammonia gas is fully contacted with dilute sulfuric acid in the absorption tower, a rapid neutralization reaction occurs, and ammonium sulfate solution is generated. By controlling the concentration and flow of sulfuric acid, the concentration of the product ammonium sulfate solution is stabilized at about 20%. The pH monitoring system monitors the pH value of the absorption liquid in real time, and when the pH value rises (insufficient acidity), sulfuric acid is automatically supplemented; when the pH value decreases (excess acid), water is automatically diluted.

[0028] Key process parameters: Absorbent: 10% dilute sulfuric acid; Circulating amount of absorption liquid: 5m 3 / h; Absorption tower operating temperature: 30-40℃; Liquid-gas ratio: 3:1; Absorption efficiency: ≥98%; Product concentration: 20% ammonium sulfate solution; Technical effects: The present application can produce 1.2 tons of ammonium sulfate per day (based on 20% solution), with an annual output value of about 788,000 yuan, which not only eliminates the secondary pollution caused by ammonia emission, but also realizes resource utilization, and produces significant economic benefits.

[0029] Further, in the present application: PLC controller: Siemens S7-1200 series; Touch screen HMI: 10-inch color touch screen; Control loop design: a) pH control loop Detection: On-line pH meter real-time monitoring of blow-off tower water pH value; Control: PLC receives pH signal and compares with set value (10.5-11.5); Execution: Control the rotation speed of the alkali pump through the PID algorithm to adjust the NaOH dosage; Accuracy: pH control accuracy ±0.2; b) Temperature control loop Detection: Temperature sensor monitors the blow-off tower water temperature; Control: PLC receives temperature signal and compares with set value (50±5℃); Execution: Control the opening degree of the steam regulating valve to adjust the heat input; Accuracy: Temperature control accuracy ±2℃; c) Liquid level control loop Detection: Liquid level meter monitors the tank liquid level; Control: PLC controls the start and stop of the water pump according to the liquid level; Protection: High liquid level alarm and low liquid level pump stop protection; d) Air volume control loop Detection: Air volume meter monitors the air volume at the blower outlet; Control: PLC calculates the required air volume according to the liquid flow and controls the frequency converter of the fan; Optimization: Automatically optimize the gas-water ratio according to the ammonia nitrogen removal effect; e) Ammonia recovery control loop Detection: pH meter monitors the absorption liquid pH value; Control: PLC controls the sulfuric acid metering pump to maintain the absorption liquid pH 2-3; Optimization: Automatically adjust the circulation amount according to the ammonia gas concentration; Safety interlocking function: High / low liquid level interlocking shutdown; Automatic switching to standby equipment in case of equipment failure; pH abnormality alarm and automatic adjustment; Automatic steam input reduction when temperature exceeds limit; Ammonia leakage alarm and emergency exhaust start; Remote monitoring function: Real-time display of process flow and operating parameters; Historical data query and trend analysis; Automatic generation of operation report; Mobile phone APP remote monitoring (optional).

[0030] Technical effect: The intelligent control system realizes full-automatic operation, reduces manual operation, and reduces labor cost by 60%; by accurately controlling various process parameters, the processing efficiency is improved by 15-20%, and the reagent consumption is reduced by 10-15%.

[0031] The devices of the present application adopt modular integrated design, and the functions of pretreatment, stripping, recovery and post-treatment are modularized, each module can be independently manufactured, transported and installed; standard interfaces are used for connection between modules. It is convenient for expansion and maintenance.

[0032] Technical effect: Shorten the construction period by 30%; reduce the installation cost by 20%; facilitate the future expansion and reconstruction.

[0033] Another object of the present application is to provide a coal chemical enterprise condensate high-concentration ammonia nitrogen treatment method, which specifically comprises the following steps: (1) raw water storage and homogenization: the condensate of the coal chemical enterprise enters the raw water storage tank, and is fully mixed by the stirrer to balance the water quality fluctuation; (2) pH adjustment: the raw water is conveyed to the pH adjustment tank by the water inlet pump, the pH value is detected by the online pH meter, and the 10% NaOH solution is added by the PLC control alkali pump, so that the pH is adjusted to 10.5-11.5, and the ammonium ion is converted into free ammonia; (3) preheating: the wastewater after pH adjustment enters the plate heat exchanger, and is heated to 50±5℃ by using the factory waste heat steam or hot water, so that the volatility and mass transfer rate of ammonia are improved; (4) ammonia stripping: the preheated wastewater enters from the top of the ammonia stripping tower, is uniformly distributed by the liquid distributor, and is sprinkled on the filler layer; the air is blown from the bottom of the tower by the air blower, the gas and water are countercurrently contacted, the ammonia is transferred from the liquid phase to the gas phase, and the water after ammonia removal is discharged from the bottom, and the ammonia nitrogen concentration is reduced from 20,000 mg / L to below 1,000 mg / L; (5) ammonia gas recovery: the ammonia gas stripped out enters the ammonia gas absorption tower, is countercurrently contacted with 10% dilute sulfuric acid, and generates ammonium sulfate solution through neutralization reaction; the absorption efficiency is ≥98%, and the ammonia concentration of tail gas emission is <50 mg / m³; (6) neutralization treatment: the wastewater after ammonia removal enters the neutralization tank, and the pH is adjusted to 7-8 by adding dilute sulfuric acid, so as to meet the subsequent treatment or discharge requirements; (7) Flocculation and sedimentation: according to the effluent requirements, a flocculation and sedimentation process is added to remove suspended solids and part of the COD; (8) Effluent discharge: the treated wastewater has ammonia nitrogen ≤ 250 mg / L, pH 6-9, and COD < 3000 mg / L, meeting the discharge standards.

[0034] Through the above technical solutions, compared with the prior art, the present application has the following beneficial effects: 1. Significant reduction in energy consumption: through the waste heat utilization system, the existing steam or hot water resources of the factory are fully utilized, and compared with the traditional direct heating method, the energy consumption is reduced by 30-40%, and the annual energy cost is saved by about 130,000 yuan.

[0035] 2. Realize resource utilization: innovatively convert the ammonia gas blown out into ammonium sulfate product, turning waste into treasure. Each processing of 240m³ wastewater can produce 1.2 tons of ammonium sulfate per day, with an annual output value of 788,000 yuan. Not only does it eliminate secondary pollution, but also achieves economic benefits, making the entire treatment system change from a "cost center" to a "profit center".

[0036] 3. Low investment cost: through process optimization and modular design, the total investment is only 900,000 yuan, which is reduced by 40-60% compared with the traditional treatment system (150-300 million yuan).

[0037] 4. Low operating cost and profitability: after deducting the ammonia recovery income, the net operating cost is negative (annual profit of 153,000 yuan), realizing the unity of economic benefits and environmental benefits. The operating cost of the traditional treatment method is 15-30 yuan / m³, and the present application realizes profitable operation through ammonia recovery.

[0038] 5. High treatment efficiency and stability: the optimized blow-off tower design makes the ammonia nitrogen removal rate stable at more than 95%, and the effluent ammonia nitrogen is ≤ 250 mg / L, meeting the discharge standards. The system has high running stability and is not affected by water quality fluctuations.

[0039] 6. High degree of automation: PLC intelligent control system is adopted to realize automatic control and optimized adjustment of key parameters such as pH, temperature, flow, and liquid level, reduce manual operation, reduce labor cost by 60%, and realize unattended operation.

[0040] 7. Small land area: modular integrated design makes the land area only need 300m 2 , which is 70-85% less than the traditional biological treatment (1000-2000m 2 ).

[0041] 8. Eliminate secondary pollution: ammonia recovery efficiency ≥ 98%, tail gas ammonia concentration < 50mg / m 3, far lower than the requirement of the Odor Pollutant Emission Standard, and the atmospheric pollution caused by ammonia emission is completely eliminated.

[0042] 9. Strong adaptability: the system can adapt to water quality fluctuations with ammonia nitrogen concentration of 15,000-30,000 mg / L, pH of 8-11, and COD of 2,000-5,000 mg / L, and has good impact resistance.

[0043] 10. Easy maintenance: the modular design facilitates daily maintenance, there are few key components and wearing parts, the maintenance cost is low, the service life of the filler is 3-5 years, the service life of the pump equipment is 5-8 years, and the intact rate of the equipment is ≥98%.

[0044] 11. Environmental standard: the effluent quality stably meets the requirement of the Integrated Wastewater Discharge Standard, ammonia nitrogen ≤250 mg / L, pH 6-9, and the system operation rate ≥95%.

[0045] 12. Short investment recovery period: considering the ammonia recovery income, the static investment recovery period is about 5.9 years, the dynamic investment recovery period is about 7.2 years (discount rate 8%), and good economic benefits are obtained. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0047] Figure 1 is a whole process flow diagram.

[0048] Figure 2 is a device plan layout of the present application.

[0049] Figure 3 is a planed surface diagram of the ammonia stripping tower structure.

[0050] Figure 4 is a structure diagram of the ammonia recovery system.

[0051] wherein, Figure 3 1-tower body, 2-packing layer, 3-liquid distributor, 4-packing support, 5-mist eliminator, 6-water inlet, 7-water outlet, 8-gas inlet, 9-gas outlet, 10-manhole.

[0052] Figure 4 21-ammonia gas absorption tower, 22-packing, 23-spraying device, 24-circulating pump, 25-circulating tank, 26-sulfuric acid storage tank, 27-product storage tank, 28-pH online monitoring point, 29-product neutralizing device. DETAILED DESCRIPTION

[0053] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0054] Embodiment 1 The present embodiment provides a coal chemical enterprise condensate high-concentration ammonia nitrogen treatment device, comprising: A coal chemical enterprise condensate high-concentration ammonia nitrogen treatment device, comprising: a raw water storage system, a pretreatment system, an ammonia stripping system, an ammonia recovery system, a post-treatment system and an automatic control system; The raw water storage system, the pretreatment system, the ammonia stripping system, the ammonia recovery system and the post-treatment system are connected in sequence; The automatic control system is connected with the raw water storage system, the pretreatment system, the ammonia stripping system, the ammonia recovery system and the post-treatment system respectively.

[0055] In the present embodiment, the raw water storage system comprises a first raw water storage tank and a second raw water storage tank connected in sequence.

[0056] The pretreatment system comprises a pH adjusting tank and a waste heat utilization preheating system; The waste heat utilization preheating system comprises a plate heat exchanger, a temperature sensor, an automatic adjusting valve and a steam distribution pipeline; The cold side inlet of the plate heat exchanger is connected with the outlet of the pH adjusting tank, and the cold side outlet of the plate heat exchanger is connected with the ammonia stripping system; The steam distribution pipeline is connected with the hot side inlet of the plate heat exchanger through the automatic adjusting valve, and the hot side outlet of the plate heat exchanger is provided with a condensate water discharge pipeline; The temperature sensor is arranged on the cold side outlet pipeline of the plate heat exchanger, and is used for detecting the temperature of the preheated wastewater; The automatic adjusting valve adjusts the steam flow according to the detection signal of the temperature sensor.

[0057] The ammonia stripping system comprises an ammonia stripping tower; The ammonia stripping tower comprises a tower body, a filler layer, a liquid distributor, a filler support, a demister, a water inlet, a water outlet, an air inlet, an air outlet and a manhole; The filler layer, the liquid distributor, the filler support and the demister are arranged inside the tower body; from top to bottom, they are the demister, the liquid distributor, the filler layer and the filler support; The gas outlet is arranged at the top of the tower body, the gas inlet is arranged at the bottom of the tower body, the water inlet is arranged at the upper part of the side wall of the tower body, the water outlet is arranged at the lower part of the side wall of the tower body, and the manholes are arranged at the side wall of the tower body and arranged from top to bottom; The water inlet is connected with the cold side outlet of the plate heat exchanger. The air blower is connected with the gas inlet.

[0058] The ammonia recovery system comprises an ammonia absorption tower, a filler, a circulating pump, a circulating tank, a sulfuric acid storage tank, a spraying device, a product storage tank and a product neutralization device. The filler and the spraying device are arranged inside the ammonia absorption tower, and the spraying device is located above the filler. One end of the circulating pump is connected with the top of the ammonia absorption tower, the other end is connected with the circulating tank, and the circulating tank is also connected with the product storage tank, the sulfuric acid storage tank and the bottom of the ammonia absorption tower respectively. The product neutralization device is arranged on the tail gas outlet pipeline of the ammonia absorption tower and is used for neutralizing unabsorbed acid gas. The ammonia absorption tower is connected with the ammonia stripping tower.

[0059] The post-treatment system comprises: a neutralization tank, an acid adding device, a flocculation and sedimentation tank, a chemical adding device and a water outlet tank. The water inlet of the neutralization tank is connected with the water outlet of the ammonia stripping tower, and the water outlet of the neutralization tank is connected with the water inlet of the flocculation and sedimentation tank. The acid adding device comprises an acid liquid storage tank, an acid adding pump and an acid adding pipeline, and the acid liquid storage tank is connected with the neutralization tank through the acid adding pump and the acid adding pipeline. The chemical adding device comprises a PAC storage tank, a PAM storage tank, a chemical adding pump and a chemical adding pipeline, and the PAC storage tank and the PAM storage tank are connected with the flocculation and sedimentation tank respectively. The water outlet of the flocculation and sedimentation tank is connected with the water outlet tank.

[0060] The automatic control system comprises a PLC controller, a touch screen HMI, online monitoring instruments, an actuating mechanism and an alarm system. The online monitoring instruments comprise a pH meter, a thermometer, a flow meter, a liquid level meter and an ammonia nitrogen analyzer. The actuating mechanism comprises a frequency converter, an electric regulating valve and an electromagnetic valve. The alarm system comprises a light alarm and a short message alarm module. The pH meter is arranged in the pH adjusting tank, the neutralization tank, the circulating tank and the ammonia absorption tower respectively and is connected with the PLC controller through a signal line. The thermometer is arranged at the outlet of the plate heat exchanger and is connected with the PLC controller through a signal line. The flow meter is arranged in the water inlet pipeline, the chemical adding pipeline and the outlet of the air blower respectively and is connected with the PLC controller through a signal line. Liquid level meters are respectively arranged in the first raw water storage tank, the second raw water storage tank, the sulfuric acid storage tank, the product storage tank, the acid liquid storage tank, the PAC storage tank, the PAM storage tank, the pH adjusting tank, the neutralization tank, the flocculation and sedimentation tank, and the effluent tank, and are connected with the PLC controller through signal lines; The actuator includes a frequency converter, an electric regulating valve, and an electromagnetic valve, which are respectively connected with the PLC controller through control lines, and are used for controlling corresponding pumps, blowers, and valves; The alarm system includes an audible and visual alarm and a short message alarm module, and is connected with the PLC controller.

[0061] Example 2 Treatment of coal chemical enterprise condensate with ammonia nitrogen of 20,000 mg / L Raw water quality: Water quantity: 240 m³ / d (10 m³ / h) pH: 9.5 Ammonia nitrogen: 20,000 mg / L COD: 3,000 mg / L Temperature: 25℃ Treatment steps: Step 1: The raw water enters two 100 m³ storage tanks, is mixed and homogenized by 2.2 kW stirrers, and has a residence time of 8-10 hours.

[0062] Step 2: A stainless steel centrifugal pump (Q=15 m³ / h, H=20 m, N=5.5 kW) is started to deliver the raw water to the pH adjusting tank (volume 5 m³).

[0063] Step 3: An on-line pH meter (measurement range 0-14, accuracy ±0.02) detects that the pH is 9.5, and the PLC control system starts an alkali pump (Q=100 L / h) to add 10% NaOH solution at 15 L / h, so as to adjust the pH to 11.0 and convert 98% of the ammonium ions into free ammonia.

[0064] Step 4: The wastewater after pH adjustment enters a plate heat exchanger (heat transfer area 50 m², heat transfer coefficient 3000 W / (m²·K)), 0.4 MPa steam from the factory enters the hot side of the heat exchanger at a flow rate of about 1.5 t / h, and the wastewater is heated from 25℃ to 52℃. A temperature sensor detects that the outlet temperature is 52℃, and the PLC automatically adjusts the steam regulating valve to keep the temperature stable.

[0065] Step 5: The preheated wastewater enters from the DN80 water inlet at the top of the stripping tower (φ1500 mm×10000 mm) at a flow rate of 10 m³ / h. The liquid distributor (304 stainless steel, hole diameter φ3 mm, hole pitch 30 mm, opening rate 15%) uniformly distributes the water above the filler layer.

[0066] Step 6: A blower (Q = 50,000 m3 / h, P = 5 kPa, N = 15 kW) blows ambient air from the DN300 inlet at the bottom of the tower at an actual air flow of 45,000 m3 / h and an air-water ratio of 4500:1. The air contacts the downward-flowing wastewater in countercurrent flow in a PP Pall ring packing layer (packing layer height 6000 mm, packing diameter φ 25 mm, specific surface area 220 m2 / m3, void fraction 92%) that provides a gas-liquid contact area of about 25,000 m2.

[0067] Step 7: Ammonia is transferred from the liquid phase to the gas phase at a temperature of 52°C, a pH of 11.0, and an air-water ratio of 4500:1. After a contact time of 2.5 hours, the ammonia nitrogen concentration in the wastewater is reduced from 20,000 mg / L to 900 mg / L, with a removal rate of 95.5%. The deaminated water is discharged from the DN80 outlet at the bottom of the tower and enters the neutralization tank.

[0068] Step 8: The stripped ammonia gas (containing about 3.8% ammonia, with a flow rate of about 1700 Nm3 / h) carries water mist upwards to the top of the tower, where the water mist is removed by a wire mesh demister (demisting efficiency 99.5%) before being discharged from the DN400 gas outlet at the top of the tower and entering the ammonia gas absorption tower through a DN400 glass steel pipeline.

[0069] Step 9: Ammonia gas enters the bottom of the absorption tower (φ 800 mm x 6000 mm, 316L stainless steel). 10% dilute sulfuric acid is sprayed from the top of the tower at a flow rate of 5 m 3 / h, with a liquid-gas ratio of about 3:1. The ammonia gas and dilute sulfuric acid are fully contacted in a ceramic Rasching ring packing layer (packing layer height 4000 mm) to undergo a neutralization reaction: 2NH3+ H2SO4→ (NH4)2SO4 Step 10: The acid solution that has absorbed ammonia (20% ammonium sulfate solution) flows out from the bottom of the tower into the circulating tank (volume 3 m3), and the pH meter detects a pH value of 2.5. The circulating pump (Q = 5 m3 / h) delivers the absorption liquid to the top of the tower for continuous absorption. When the liquid level in the circulating tank reaches 80%, 0.5 m3 of ammonium sulfate solution is automatically discharged to the product storage tank, and fresh dilute sulfuric acid is supplemented.

[0070] Step 11: The tail gas (containing <0.05% ammonia) that is not absorbed is discharged from the top of the absorption tower and further absorbed by an alkali washing tower (with the addition of 5% NaOH solution) before being discharged. The ammonia concentration in the tail gas is <30 mg / m3, meeting the "Standard for the Discharge of Odorous Pollutants".

[0071] Step 12: The deaminated wastewater (ammonia nitrogen 900 mg / L, pH 11.0) enters the neutralization tank (3 m x 2 m x 2 m, volume 12 m3). The online pH meter detects that the pH is 11.0, and the PLC control system starts the acid pump (Q = 80 L / h) to add 10% dilute sulfuric acid solution to adjust the pH to 7.5. The neutralization reaction releases heat, and the wastewater temperature rises to about 35°C.

[0072] Step 13: The neutralized wastewater enters the flocculation and sedimentation tank (4 m x 3 m x 3 m, volume 36 m3), and PAC flocculant 50 mg / L and PAM coagulant aid 2 mg / L are added to remove part of the suspended solids and COD, with a residence time of 3 hours.

[0073] Step 14: The effluent is transported to the discharge outlet or subsequent treatment system by the effluent pump.

[0074] Treatment effect: Effluent ammonia nitrogen: 230 mg / L (removal rate 98.85%); Effluent pH: 7.5; Effluent COD: 2,800 mg / L; Ammonia recovery rate: 98.2%; Ammonium sulfate production: 1.15 t / d (20% solution, approximately 0.23 t / d); Energy consumption data: Electricity consumption: 480 kWh / d (20 kWh / h); Steam consumption: 1.5 t / h x 24h = 36 t / d; NaOH consumption: 15 L / h x 10% x 24h x 1.1 kg / L = 40 kg / d; H2SO4 consumption: 12 kg / d for neutralization + 35 kg / d for ammonia absorption = 47 kg / d; Operating cost: Electricity cost: 480 x 0.8 = 384 yuan / d; Steam cost: 36 x 100 = 3,600 yuan / d (using waste heat, actual cost is zero or very low); NaOH cost: 40 x 2.5 = 100 yuan / d; H2SO4 cost: 47 x 0.8 = 38 yuan / d; Labor cost: 300 yuan / d; Total: 4,422 yuan / d (excluding steam) or 422 yuan / d (using waste heat); Economic benefit: Ammonium sulfate revenue: 1.15 x 1,800 = 2,070 yuan / d; Net income: 2,070 - 422 = 1,648 yuan / d (with waste heat); Example 3 Treatment of coal chemical enterprise condensate with ammonia nitrogen 15,000 mg / L; Raw water quality: Water quantity: 240 m³ / d (10 m³ / h) pH: 9.8; Ammonia nitrogen: 15,000 mg / L; COD: 2,500 mg / L; Temperature: 30°C; Treatment steps: Step 1-3 same as Example 1, pH adjusted to 10.8.

[0075] Step 4: preheated to 50°C (steam consumption reduced to 1.2 t / h).

[0076] Step 5-7: operate the stripping tower at a temperature of 50°C, pH 10.8, and gas-water ratio 4000:1. The actual air volume of the air blower is 40,000 m³ / h, and the energy consumption is reduced.

[0077] Step 8-11: ammonia gas absorption system normal operation, absorption efficiency 98.5%.

[0078] Step 12-14: normal operation of post-treatment system.

[0079] Treatment effect: Effluent ammonia nitrogen: 180 mg / L (removal rate 98.8%); Effluent pH: 7.3; Ammonia recovery rate: 98.5%; Ammonium sulfate production: 0.88 t / d; Optimization: Due to the low concentration of ammonia nitrogen in the influent, the system automatically reduces the gas-water ratio and heating temperature, reducing energy consumption while still achieving good treatment effect. This reflects the optimization function of the intelligent control system.

[0080] Example 4 Treatment of high-concentration coal chemical enterprise condensate with ammonia nitrogen 25,000 mg / L; Raw water quality: Water quantity: 240 m³ / d (10 m³ / h); pH: 9.2; Ammonia nitrogen: 25,000 mg / L; COD: 3,500 mg / L; Temperature: 20°C; Treatment steps: Step 1-3 Same as Example 1, pH adjusted to 11.3 (increase pH to enhance deamination effect).

[0081] Step 4: Preheated to 55°C (increase temperature to enhance deamination effect, steam consumption increased to 2.0 t / h).

[0082] Step 5-7: The stripping tower was operated at a temperature of 55°C, pH 11.3, and gas-water ratio of 5000:1. The actual air volume of the blower was 50,000 m³ / h, and the gas-water ratio was increased to cope with high concentration of ammonia nitrogen. After 3 hours of contact time, the ammonia nitrogen decreased from 25,000 mg / L to 1,100 mg / L, with a removal rate of 95.6%.

[0083] Step 8-11: Ammonia concentration was about 4.5%, absorption system circulation increased to 6 m³ / h, absorption efficiency was 97.8%.

[0084] Step 12-14: Post-treatment system was running normally.

[0085] Treatment effect: Effluent ammonia nitrogen: 240 mg / L (final removal rate 99.04%); Effluent pH: 7.6; Ammonia recovery rate: 97.8%; Ammonium sulfate production: 1.45 t / d; Optimization: In the face of high concentration of ammonia nitrogen wastewater, the system automatically increased the pH, temperature and gas-water ratio, although the energy consumption increased, but still achieved good treatment effect and economic benefit. The production of ammonium sulfate increased, and the economic benefit was higher.

[0086] Example 5 Running condition under low temperature condition in winter; Operating conditions: Ambient temperature: -5°C; Inlet water temperature: 15°C; Other conditions are the same as Example 1.

[0087] Special measures: Step 1: Strengthen equipment insulation, outdoor pipeline uses 50mm thick rock wool insulation + aluminum skin protection layer.

[0088] Step 2: Increase steam consumption, heat the inlet water to 58°C (increase by 6°C compared with normal temperature condition), steam consumption increased to 2.2 t / h.

[0089] Step 3: The stripping tower body uses 50mm thick insulation layer to reduce heat loss.

[0090] Step 4: Insulate or heat the raw water tank to prevent freezing.

[0091] Step 5: The ammonia gas pipeline adopts heat tracing measures to prevent condensation.

[0092] Treatment effect: Effluent ammonia nitrogen: 245 mg / L; Effluent pH: 7.4; Ammonia recovery rate: 97.5%.

[0093] Description: By taking measures such as insulation and increasing heating temperature, the system can still operate stably and meet the discharge standard under low temperature conditions in winter, proving the full-season adaptability of the system.

[0094] Example 6 Combined process with biochemical treatment Application scenario: When the effluent ammonia nitrogen is required to be less than 15 mg / L, simple physical and chemical treatment is difficult to meet the standard, and the "ammonia stripping + biochemical treatment" combined process can be used.

[0095] Process flow: raw water → pH adjustment → preheating → ammonia stripping (95% ammonia nitrogen removal) → neutralization → biochemical treatment (A / O process) → effluent.

[0096] Design of biochemical treatment section: Anoxic tank: residence time 4h, volume 40m³; Oxygen tank: residence time 6h, volume 60m³, aeration rate 60m³ / h; Secondary sedimentation tank: residence time 2h, surface load 1.0m³ / (m²·h).

[0097] Treatment effect: Effluent of ammonia stripping: ammonia nitrogen 900mg / L → after biochemical treatment: ammonia nitrogen 8mg / L; COD: 3000mg / L → 50mg / L; Total nitrogen: 1000mg / L → 30mg / L; Advantages: Through physical and chemical pretreatment, the ammonia nitrogen load is greatly reduced, and the biochemical system can operate stably. Compared with direct biochemical treatment, the biochemical tank volume is saved by 70%, and the dilution water quantity is reduced by 80%.

[0098] In the specification, each embodiment is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between each embodiment can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the related parts can be referred to the method part.

[0099] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for treating high-concentration ammonia nitrogen in condensate from coal chemical plants, characterized in that, include: Raw water storage system, pretreatment system, ammonia stripping system, ammonia recovery system, post-treatment system, and automatic control system; The raw water storage system, pretreatment system, ammonia stripping system, ammonia recovery system, and post-treatment system are connected in sequence. The automatic control system is connected to the raw water storage system, pretreatment system, ammonia stripping system, ammonia recovery system, and posttreatment system, respectively.

2. The high-concentration ammonia nitrogen treatment device for condensate in coal chemical enterprises according to claim 1, characterized in that, The raw water storage system includes a first raw water storage tank and a second raw water storage tank connected in sequence.

3. A high-concentration ammonia nitrogen treatment device for condensate in a coal chemical enterprise according to claim 2, characterized in that, The pretreatment system includes a pH adjustment tank and a waste heat utilization preheating system; The waste heat utilization preheating system includes a plate heat exchanger, a temperature sensor, an automatic regulating valve, and a steam distribution pipeline. The cold-side inlet of the plate heat exchanger is connected to the outlet of the pH adjustment tank, and the cold-side outlet of the plate heat exchanger is connected to the ammonia stripping system. The steam distribution pipeline is connected to the hot-side inlet of the plate heat exchanger through the automatic regulating valve, and the hot-side outlet of the plate heat exchanger is provided with a condensate discharge pipeline. The temperature sensor is installed on the cold side outlet pipe of the plate heat exchanger to detect the temperature of the preheated wastewater. The automatic regulating valve adjusts the steam flow rate according to the detection signal from the temperature sensor.

4. A high-concentration ammonia nitrogen treatment device for condensate in a coal chemical enterprise according to claim 3, characterized in that, The ammonia stripping system includes an ammonia stripping tower and a blower; The ammonia stripping tower includes a tower body, a packing layer, a liquid distributor, a packing support, a demister, a water inlet, a water outlet, an air inlet, an air outlet, and a manhole; The packing layer, liquid distributor, packing support, and demister are all located inside the tower body; from top to bottom, they are demister, liquid distributor, packing layer, and packing support. The air outlet is located at the top of the tower body, the air inlet is located at the bottom of the tower body, the water inlet is located on the upper part of the side wall of the tower body, the water outlet is located on the lower part of the side wall of the tower body, and there are three manholes, which are respectively located on the side wall of the tower body and arranged from top to bottom; The water inlet is connected to the cold side outlet of the plate heat exchanger; The blower is connected to the air inlet.

5. A high-concentration ammonia nitrogen treatment device for condensate in a coal chemical enterprise according to claim 4, characterized in that, The ammonia recovery system includes an ammonia absorption tower, packing material, a circulating pump, a circulating tank, a sulfuric acid storage tank, a spraying device, a product storage tank, and a product neutralization device. The packing material and spraying device are installed inside the ammonia absorption tower, with the spraying device located above the packing material. One end of the circulating pump is connected to the top of the ammonia absorption tower, and the other end is connected to the circulating tank. The circulating tank is also connected to the product storage tank, the sulfuric acid storage tank, and the bottom of the ammonia absorption tower. The product neutralization device is installed on the tail gas outlet pipeline of the ammonia absorption tower and is used to neutralize the unabsorbed acidic gas. The ammonia absorption tower is connected to the ammonia stripping tower.

6. A high-concentration ammonia nitrogen treatment device for condensate in a coal chemical enterprise according to claim 5, characterized in that, The post-processing system includes: Neutralization tank, acid addition device, flocculation sedimentation tank, chemical dosing device, and effluent tank; The inlet of the neutralization tank is connected to the outlet of the ammonia stripping tower, and the outlet of the neutralization tank is connected to the inlet of the flocculation sedimentation tank. The acid addition device includes an acid storage tank, an acid addition pump, and an acid addition pipeline. The acid storage tank is connected to the neutralization tank through the acid addition pump and the acid addition pipeline. The dosing device includes a PAC storage tank, a PAM storage tank, a dosing pump, and a dosing pipeline. The PAC storage tank and the PAM storage tank are respectively connected to the flocculation sedimentation tank through the dosing pump and the dosing pipeline. The outlet of the flocculation sedimentation tank is connected to the effluent tank.

7. A high-concentration ammonia nitrogen treatment device for condensate in a coal chemical enterprise according to claim 6, characterized in that, The automatic control system includes a PLC controller, a touch screen HMI, online monitoring instruments, actuators, and an alarm system; The online monitoring instruments include: pH meter, thermometer, flow meter, level gauge, and ammonia nitrogen analyzer; The actuator includes a frequency converter, an electric regulating valve, and a solenoid valve; The alarm system includes a light alarm and an SMS alarm module; The pH meters are respectively installed in the pH adjustment tank, neutralization tank, circulation tank and ammonia absorption tower, and are connected to the PLC controller via signal lines; The thermometer is located at the outlet of the plate heat exchanger and is connected to the PLC controller via a signal line; The flow meters are respectively installed in the water inlet pipeline, the chemical dosing pipeline and the blower outlet, and are connected to the PLC controller via signal lines; The level gauges are respectively installed in the first raw water storage tank, the second raw water storage tank, the sulfuric acid storage tank, the product storage tank, the acid storage tank, the PAC storage tank, the PAM storage tank, the pH adjustment tank, the neutralization tank, the flocculation sedimentation tank, and the effluent tank, and are connected to the PLC controller via signal lines; The actuator includes a frequency converter, an electric regulating valve, and a solenoid valve, which are respectively connected to the PLC controller via control lines to control the corresponding pumps, blowers, and valves. The alarm system includes an audible and visual alarm and an SMS alarm module, which are connected to the PLC controller.

8. A method for treating high-concentration ammonia nitrogen in condensate from coal chemical plants, characterized in that, The apparatus according to claim 7 specifically includes the following steps: (1) Raw water storage and homogenization: The condensate from the coal chemical enterprise enters the raw water storage tank and is thoroughly mixed by a stirrer to balance water quality fluctuations; (2) pH adjustment: Raw water is pumped to pH adjustment tank through inlet pump. The pH value is detected by online pH meter. PLC controls alkali addition pump to add 10% NaOH solution to adjust pH to 10.5-11.5, so that ammonium ions are converted into free ammonia. (3) Preheating: After pH adjustment, the wastewater enters the plate heat exchanger and is heated to 50±5℃ using waste heat steam or hot water from the factory to improve the volatility and mass transfer rate of ammonia. (4) Ammonia stripping: The preheated wastewater enters from the top of the ammonia stripping tower, is evenly distributed by the liquid distributor and then sprayed onto the packing layer; the blower blows air into the bottom of the ammonia stripping tower, and the air and water come into countercurrent contact, and the ammonia is transferred from the liquid phase to the gas phase; the water after ammonia stripping is discharged from the bottom of the tower, and the ammonia nitrogen concentration drops from 20,000 mg / L to below 1,000 mg / L; (5) Ammonia recovery: The ammonia gas stripped off enters the ammonia absorption tower and comes into countercurrent contact with 10% dilute sulfuric acid to neutralize and generate ammonium sulfate solution; the absorption efficiency is ≥98% and the ammonia concentration in the tail gas emission is <50mg / m³; (6) Neutralization treatment: The wastewater after ammonia removal enters the neutralization tank, and dilute sulfuric acid is added to adjust the pH to 7-8 to meet the requirements of subsequent treatment or discharge; (7) Flocculation and sedimentation: According to the effluent requirements, a flocculation and sedimentation process is added to remove suspended solids and part of COD; (8) Wastewater discharge: The treated wastewater has ammonia nitrogen ≤250mg / L, pH 6-9, and COD<3000mg / L, which meets the discharge standards.

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