A method of heating wastewater by jet mixing

Abstract

This invention discloses a jet mixing method for heating wastewater, comprising: achieving efficient heating through pretreatment, synergistic tension reduction by surfactant and ultrasound, staged stirring and coagulation with PAC, and alternating jet mixing of steam and wastewater; the synergistic effect of tension reduction and dispersion by surfactant and ultrasound results in smaller and more uniform oil droplet size, providing easier targets for subsequent PAC coagulation; the synergistic effect of adsorption and flocculation by staged stirring of PAC and pH adjustment rapidly encapsulates pollutants in the fast mixing stage and promotes floc cross-linking to form large and dense "heat carriers" in the slow mixing stage, significantly enhancing the mass transfer efficiency between wastewater and steam; the turbulent disturbance of alternating jets of steam and wastewater synergistically reduces the resistance at the mixing interface, resulting in more uniform heat transfer and avoiding local overheating or crusting; thus significantly improving heating efficiency.

Description

Technical Field

[0001] This invention relates to a wastewater heating method, and more particularly to a wastewater heating method using jet mixing. Background Technology

[0002] With increasingly stringent industrial wastewater discharge standards, the efficient treatment of oily wastewater (such as wastewater generated from oil extraction, machinery processing, and food processing) has become a key issue in the environmental protection field. Among these processes, wastewater heating is an important pre-treatment step for subsequent biochemical treatment, membrane separation, or distillation concentration, directly affecting treatment efficiency and energy costs.

[0003] The wastewater from Hualu adipic acid processes (such as wastewater from the production of nylon 66 and cyclohexanol) often has an effluent temperature below 25℃ (even lower in winter) due to the characteristics of cooling during the production process and material residues. Low temperatures directly inhibit the metabolic activity of denitrifying bacteria in biological treatment (the denitrification rate decreases by more than 50% for every 10℃ drop in temperature), and at the same time slow down the reaction rate between coagulants and oils and suspended solids, making it difficult for traditional coagulation sedimentation, flotation and other processes to efficiently remove emulsified oil and high-hardness ions.

[0004] Currently, the mainstream technologies for heating oily wastewater are still mainly direct steam mixing or single-agent assisted heating. When steam and wastewater are directly mixed, the interfacial tension is high, and oil droplets easily aggregate and form stable emulsions, which hinder heat transfer and make the heating efficiency unstable. In addition, the flocs formed during the coagulation process are small and loose in structure, making it difficult to adsorb oil and suspended solids in the wastewater, resulting in low heat transfer efficiency and affecting the overall heating efficiency of the wastewater. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a method for heating wastewater by jet mixing.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a wastewater heating method using jet mixing, comprising: S1, coarse filtration, fine filtration and oil removal of wastewater;

[0007] S2. Add surfactant to the wastewater after S1 treatment and simultaneously apply low-frequency ultrasound at 20-40kHz; wherein the mass ratio of surfactant to wastewater is 0.05-0.15:1.

[0008] S3. Add polyaluminum chloride to the wastewater treated by S2 at a certain mass ratio; the certain mass ratio is 1:0.08-0.15.

[0009] S4. Perform pH adjustment and scale inhibition pretreatment on the wastewater treated by S3.

[0010] S5. Stabilize the steam pressure to 0.4-0.8MPa through the pressure reducing valve and inject it into the mixing chamber through the nozzle;

[0011] S6. Pressurize the wastewater treated in S4 using a high-pressure pump. The pressurized wastewater is then injected into the mixing chamber through a nozzle, alternating with the depressurized steam from S5, and mixed for 3-5 seconds. The mass ratio of the added steam to the wastewater is 1:4-8.

[0012] In a preferred embodiment of the present invention, the specific steps of coarse filtration, fine filtration and oil removal of wastewater in step S1 are as follows:

[0013] The process involves coarse filtration, where wastewater is passed through a 20μm stainless steel screen made of 316L material, with a flow rate controlled at 10-15 m³ / h and a differential pressure alarm threshold of 0.3 MPa. Fine filtration involves passing the coarsely filtered wastewater through an activated carbon filter at a flow rate of 5-8 m / h to adsorb oil decomposition products and odor substances. The wastewater then enters a ceramic membrane with a transmembrane pressure difference of 0.1-0.3 MPa to trap particles with a diameter ≥1μm. Oil removal is achieved by passing the finely filtered wastewater into an inclined plate oil separator. Oil droplets rise to the surface due to density differences and are collected through an oil collection pipe, resulting in an oil-free inclined plate oil separator.

[0014] In a preferred embodiment of the present invention, in step S2, the specific steps of adding surfactant to the wastewater after treatment in S1 are as follows: in the wastewater after treatment in S1, the wastewater and surfactant are mixed in a static mixer at a mass ratio of surfactant to wastewater of 0.05-0.15:1, the flow rate is controlled at 1-2 m / s, and the mixing time is 1-2 min.

[0015] In a preferred embodiment of the present invention, in step S2, when low-frequency ultrasonic waves of 20-40 kHz are applied simultaneously, the duration of the ultrasonic waves is 10-20 minutes, during which the temperature of the wastewater needs to be kept ≤40°C.

[0016] In a preferred embodiment of the present invention, the specific steps for adding polyaluminum chloride to the wastewater after treatment in S2 according to a certain mass ratio in step S3 are as follows: add polyaluminum chloride to the wastewater after treatment in S2 at a mass ratio of 1:0.08-0.15, start the mechanical stirrer, first mix quickly at 200-300 rpm for 2 minutes, and then stir slowly at 50 rpm for 10 minutes to obtain the treated wastewater.

[0017] In a preferred embodiment of the present invention, in step S4, the pH value of the wastewater is monitored in real time by using a pH meter and an online sensor. Based on the pH meter data, HCl or NaOH is added to adjust the pH of the wastewater to 5-7. Subsequently, a scale inhibitor is added to inhibit subsequent steam heating or pipe scaling.

[0018] In a preferred embodiment of the present invention, in step S5, the steam filter is turned on to ensure that the steam is clean, and then the steam pressure is stabilized at 0.4-0.8MPa by a pressure reducing valve. The pressure is monitored in real time by a pressure gauge to ensure that the pressure fluctuation is ≤±5%.

[0019] In a preferred embodiment of the present invention, in step S6, the specific steps are as follows: the depressurized steam is injected into the mixing chamber through a fan-shaped nozzle at a flow rate of 10-20 m / s, and the wastewater is pressurized by a high-pressure pump (pressure 0.3-0.6 MPa) and injected into the mixing chamber from the other nozzle, where it is alternately mixed with the steam and stays in the mixing chamber for 3-5 seconds.

[0020] In a preferred embodiment of the present invention, the surfactant is a polyoxyethylene ether with a molecular weight of 1000-1500; the ultrasonic generator adopts an intermittent working mode with an action time of 10-20 minutes.

[0021] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0022] (1) The surface tension of wastewater is significantly reduced by the synergistic effect of surfactant and low-frequency ultrasound. The surfactant is polyoxyethylene ether, which is adsorbed on the oil-water interface to form a monomolecular film and reduce the interfacial tension. The low-frequency ultrasound applied at the same time generates microjets through cavitation effect to destroy the stability of emulsified oil droplets and promote oil droplet aggregation. At the same time, the vibration disperses the surfactant to avoid local concentration imbalance. This combined process significantly reduces the surface tension of wastewater, far exceeding the effect of using surfactant or ultrasound alone. The reduction in surface tension directly reduces the interfacial thermal resistance during steam heating, and the heat transfer coefficient increases from 920W / (m²·K) to 1200W / (m²·K), greatly reducing the heating time. Compared with the existing technology, the heating efficiency is significantly improved.

[0023] (2) After adding PAC at a mass ratio of 1:0.08-0.15, mechanically stir at 200-300 rpm for 2 minutes to rapidly disperse PAC and allow it to collide and adsorb with colloidal particles; then stir slowly at 50 rpm for 10 minutes to avoid breaking the already formed flocs; promote the hydrolysis of PAC to form and The colloid efficiently neutralizes the negative charge of the colloid, compresses the double electric layer, and significantly increases the particle size of the floc, forming a "heat carrier" effect and enhancing the mass transfer efficiency of subsequent steam heating. Compared with existing technologies, it reduces steam consumption from 0.47 kg / kg wastewater to 0.35 kg / kg wastewater, significantly improving heating efficiency.

[0024] (3) By adjusting the pH of the wastewater to 5-7 ( (Optimal hydrolysis range), at which point the PAC coagulation effect is improved by 30%, generating... The colloid carries a positive charge, which effectively neutralizes the negative charge of the colloidal particles; simultaneous addition of 1-2 mg / L scale inhibitor captures the scale through chelation or dispersion. This prevents scale from depositing on the surface of steam heating equipment or pipes; compared to existing technologies, it reduces the scaling rate, thereby reducing the impact of scaling on heating efficiency. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a flowchart of a preferred embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0029] Application Overview:

[0030] Hualu's adipic acid wastewater exhibits characteristics such as low temperature, high oil content, and high hardness. The jet mixing wastewater heating technology addresses these issues through the synergistic effect of high-speed jet shearing and the release of latent heat of steam: on the one hand, the high-speed turbulence of the jet mixer disrupts the protective film of the emulsified oil, reduces interfacial tension, promotes oil droplet coalescence, and accelerates the coagulation reaction in conjunction with heating; on the other hand, the heated wastewater directly provides a suitable temperature environment for denitrifying bacteria, while inhibiting the deposition of scale such as calcium carbonate, ultimately achieving a highly efficient synergy of "demulsification-coagulation-biological treatment".

[0031] like Figure 1 As shown, a method for heating wastewater using jet mixing includes:

[0032] S1. Perform coarse filtration, fine filtration and oil removal on wastewater;

[0033] S2. Add surfactant to the wastewater after S1 treatment and simultaneously apply low-frequency ultrasound at 20-40kHz; wherein the mass ratio of surfactant to wastewater is 0.05-0.15:1.

[0034] S3. Add polyaluminum chloride to the wastewater treated in S2 according to a certain mass ratio; the certain mass ratio in step S3 is 1:0.08-0.15;

[0035] S4. Perform pH adjustment and scale inhibition pretreatment on the wastewater treated by S3.

[0036] S5. Stabilize the steam pressure to 0.4-0.8MPa through the pressure reducing valve and inject it into the mixing chamber through the nozzle;

[0037] S6. Pressurize the wastewater treated in S4 using a high-pressure pump. The pressurized wastewater is then alternately injected into the mixing chamber through a nozzle along with the depressurized steam from S5, and mixed for 3-5 seconds. The mass ratio of the added steam to the wastewater is 1:4-8.

[0038] Furthermore, in step S1, the specific steps for coarse filtration, fine filtration, and oil removal of the wastewater are as follows:

[0039] The coarse filtration process involves passing wastewater through a 316L stainless steel screen with a 20μm mesh size. The flow rate is controlled at 10-15 m³ / h, and the differential pressure alarm threshold is 0.3 MPa. This prevents large particles from clogging the pipes or damaging the fine filtration and oil removal equipment. The wastewater inlet pressure in the coarse filtration is 0.1-0.3 MPa.

[0040] Fine filtration involves passing the coarsely filtered wastewater through an activated carbon filter at a flow rate of 5-8 m / h to adsorb oil decomposition products and odor substances. The wastewater then passes through a ceramic membrane with a transmembrane pressure difference of 0.1-0.3 MPa, trapping particles with a diameter ≥1 μm. Fine filtration reduces wastewater turbidity and minimizes interference from subsequent oil removal and coagulation processes. The activated carbon filter is made of coconut shell activated carbon with a particle size of 4-8 mesh and a pore size of 1-5 μm, capable of adsorbing organic matter and some colloids.

[0041] The ceramic membrane module is a multi-channel ceramic membrane (material) (Pore size 0.1-1μm, temperature resistance ≥80℃, pressure resistance ≥1.0MPa); ceramic material, resistant to high temperature and high pressure, used to trap tiny particles.

[0042] Oil removal is achieved by introducing finely filtered wastewater into an inclined plate oil separator. Oil droplets rise to the water surface due to density differences and are collected through an oil collection pipe, resulting in an oil-removed inclined plate oil separator. The inclined plate oil separator is made of polypropylene, with an inclination angle of 60°, a surface load of 2-4 m³ / (m²·h), and a wastewater retention time of 30-60 min.

[0043] Furthermore, in step S2, the specific steps for adding surfactant to the wastewater after treatment S1 are as follows: In the wastewater after treatment S1, the wastewater and surfactant are mixed in a static mixer at a mass ratio of surfactant to wastewater of 0.05-0.15:1, with the flow rate controlled at 1-2 m / s and the mixing time at 1-2 min.

[0044] The surfactant is polyoxyethylene ether, which can be adsorbed at the oil-water interface and oriented to form a monolayer, thereby reducing the surface tension of the wastewater. By reducing the repulsive force between droplets, it promotes the coalescence of emulsified oil and can improve the efficiency of steam heating wastewater. The surfactant polyoxyethylene ether has a molecular weight of 1000-1500.

[0045] The surfactant is sourced from Wanhua Chemical Group Co., Ltd., and its model is fatty alcohol polyoxyethylene ether (AEO-9). The polyaluminum chloride is sourced from Gongyi Hongyuan Water Purification Materials Co., Ltd., and its model is PAC-28.

[0046] Furthermore, in step S2, during the synchronous application of low-frequency ultrasound at 20-40kHz, the ultrasonic generator operates in an intermittent mode (5 seconds on, 2 seconds off), and the duration of the ultrasound is 10-20 minutes, during which the wastewater temperature must be maintained ≤40℃. Ultrasonic waves generate microjets and free radicals in the wastewater through cavitation, disrupting the stability of emulsified oil droplets and accelerating droplet aggregation. Furthermore, ultrasonic vibration promotes the uniform dispersion of surfactants in the wastewater, preventing excessively high or low local concentrations.

[0047] Furthermore, in step S3, the specific steps for adding polyaluminum chloride to the wastewater treated in S2 according to a certain mass ratio are as follows: Add polyaluminum chloride to the wastewater treated in S2 at a mass ratio of 1:0.08-0.15, start the mechanical stirrer, first rapidly mix at 200-300 rpm for 2 minutes, then slowly stir at 50 rpm for 10 minutes to obtain the treated wastewater; wherein the polyaluminum chloride hydrolyzes to generate… and The colloid neutralizes the negative charge of colloidal particles in wastewater and compresses the double electric layer, thereby reducing the repulsive force between colloidal particles in the wastewater and causing them to aggregate into large flocs. These flocs can act as a "heat carrier," enhancing the mass transfer efficiency of subsequent steam heating.

[0048] Furthermore, in step S4, the pH value of the wastewater is monitored in real time by using a pH meter and an online sensor. Based on the pH meter data, HCl or NaOH is added to adjust the pH of the wastewater to 5-7. Then, a scale inhibitor (1-2 mg / L) is added to inhibit subsequent steam heating or pipe scaling.

[0049] More specifically, The hydrolysis efficiency is highest at pH 5-7, producing... The colloid improves coagulation by 30%, and the scale inhibitor prevents calcium and magnesium ions from depositing on equipment surfaces through chelation or dispersion. Under pH 5-7 conditions, PAC hydrolysis generates... The colloid carries a positive charge, effectively neutralizing the negative charge of the colloidal particles and promoting floc formation. The concentration of HCl or NaOH is 30% of industrial grade.

[0050] Furthermore, in step S5, steam is used as the main heat source for heating wastewater. Before connecting the steam source to the pressure reducing valve, the steam filter needs to be turned on to ensure the steam is clean. Then, the steam pressure is stabilized at 0.4-0.8 MPa through the pressure reducing valve, and the pressure is monitored in real time by a pressure gauge to ensure that the pressure fluctuation is ≤±5%.

[0051] In step S6, the specific steps are as follows: the depressurized steam is injected into the mixing chamber through a fan-shaped nozzle at a flow rate of 10-20 m / s, and the wastewater is pressurized by a high-pressure pump (pressure 0.3-0.6 MPa) and injected into the mixing chamber from the other nozzle to mix with the steam alternately and stay in the mixing chamber for 3-5 seconds.

[0052] Example 1:

[0053] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0054] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0055] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0056] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0057] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0058] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0059] Comparative Example 1:

[0060] The difference from Example 1 is as follows: S2, wastewater and surfactant are mixed in a static mixer at a mass ratio of 0.05:1, the flow rate is controlled at 1.5m / s, and the mixing time is 1.5min; low-frequency ultrasound of 30kHz is applied simultaneously for 15min, and the temperature is controlled at ≤40℃.

[0061] The specific steps are as follows:

[0062] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0063] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.05:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0064] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0065] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0066] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0067] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0068] Comparative Example 2:

[0069] The difference from Example 1 is as follows: S2, wastewater and surfactant are mixed in a static mixer at a mass ratio of 0.15:1, the flow rate is controlled at 1.5m / s, and the mixing time is 1.5min; low-frequency ultrasound of 30kHz is applied simultaneously for 15min, and the temperature is controlled at ≤40℃.

[0070] The specific steps are as follows:

[0071] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0072] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.15:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0073] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0074] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0075] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0076] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0077] Comparative Example 3:

[0078] The difference from Example 1 is as follows: S2, wastewater and surfactant are mixed in a static mixer at a mass ratio of 0.1:1, the flow rate is controlled at 1.5m / s, and the mixing time is 1.5min; low-frequency ultrasound of 30kHz is applied simultaneously for 10min, and the temperature is controlled at ≤40℃.

[0079] The specific steps are as follows:

[0080] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0081] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 10 min, with the temperature controlled at ≤40℃.

[0082] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0083] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0084] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0085] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0086] Comparative Example 4:

[0087] The difference from Example 1 is as follows: S2, wastewater and surfactant are mixed in a static mixer at a mass ratio of 0.1:1, the flow rate is controlled at 1.5m / s, and the mixing time is 1.5min; low-frequency ultrasound of 30kHz is applied simultaneously for 20min, and the temperature is controlled at ≤40℃.

[0088] The specific steps are as follows:

[0089] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0090] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 20 min, with the temperature controlled at ≤40℃.

[0091] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0092] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0093] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0094] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0095] Comparative Example 5:

[0096] The difference from Example 1 is that: S3, polyaluminum chloride is added to the wastewater at a mass ratio of 1:0.08, and the mechanical stirrer is used to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0097] The specific steps are as follows:

[0098] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0099] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0100] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.08. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0101] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0102] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0103] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0104] Comparative Example 6:

[0105] The difference from Example 1 is that: S3, polyaluminum chloride is added to the wastewater at a mass ratio of 1:0.15, and the mechanical stirrer is used to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0106] The specific steps are as follows:

[0107] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0108] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0109] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.15. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0110] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0111] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0112] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:5).

[0113] Comparative Example 7:

[0114] The difference from Example 1 is that: S6, the wastewater is pressurized to 0.45MPa and flow rate is 15m / s by a high-pressure pump, and then alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:6).

[0115] The specific steps are as follows:

[0116] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0117] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0118] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0119] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0120] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0121] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:6).

[0122] Comparative Example 8:

[0123] The difference from Example 1 is that: S6, the wastewater is pressurized to 0.45MPa and the flow rate is 15m / s by a high-pressure pump, and then alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:4).

[0124] The specific steps are as follows:

[0125] S1. Industrial oily wastewater obtained through the Hualu adipic acid process has an oil content of 80 mg / L, suspended solids of 50 mg / L, pH of 6.5, hardness of 120 mg / L, and COD of 280 mg / L. The wastewater is filtered through a 316L stainless steel screen filter (pore size 20 μm) at a flow rate of 10 m³ / h and a differential pressure alarm threshold of 0.3 MPa. The coarsely filtered wastewater enters a coconut shell activated carbon filter (particle size 4-8 mesh, pore size 1-5 μm) at a flow rate of 5 m / h to adsorb oil decomposition products. It then enters a ceramic membrane module. The finely filtered wastewater enters a polypropylene inclined plate oil separator (inclination angle 60°, surface loading 3 m³ / (m²·h)) and the floating oil is collected through an oil collection pipe.

[0126] S2. Mix wastewater and surfactant in a static mixer at a mass ratio of 0.1:1, with the flow rate controlled at 1.5 m / s and the mixing time at 1.5 min; simultaneously apply low-frequency ultrasound at 30 kHz for 15 min, with the temperature controlled at ≤40℃.

[0127] S3. Add polyaluminum chloride to the wastewater at a mass ratio of 1:0.1. Use a mechanical stirrer to quickly mix at 200 rpm for 2 minutes, and then slowly stir at 50 rpm for 10 minutes.

[0128] S4. Add HCl to adjust the pH to 6, then add polyacrylate scale inhibitor;

[0129] S5. Connect the steam source to the fan-shaped nozzle (2mm orifice), and stabilize the pressure to 0.6MPa (160℃) using the pressure reducing valve. The pressure fluctuation should be ≤±5%.

[0130] S6. The wastewater is pressurized to 0.45MPa and flowed at a velocity of 15m / s by a high-pressure pump and alternately injected into the mixing chamber with steam (steam:wastewater mass ratio 1:4).

[0131] Experimental Example 1:

[0132] Take wastewater samples (S6 effluent) after treatment of Example 1 and Comparative Examples 1-8, and make 3 replicates for each sample.

[0133] Calibrate the surface tension meter with distilled water to ensure that the zero-point error is < ±0.1 mN / m.

[0134] Immerse the platinum plate 1-2 mm below the surface of the wastewater to be tested and let it stand for 10 seconds until the liquid is stable and adsorbed.

[0135] Slowly lift the platinum plate vertically, and the instrument will automatically record the maximum tensile force (unit: mN / m).

[0136] Each sample was measured three times, and the average value was taken as the surface tension value.

[0137] Calculation of surface tension reduction rate:

[0138] ,

[0139] in, The original surface tension of the wastewater (measured value approximately 45 mN / m). The surface tension of the treated wastewater was calculated. The data are shown in Table 1.

[0140] Experimental Example 2:

[0141] The measurement of Example 1 and Comparative Examples 1-8 in step S6 was performed to determine the time required for wastewater to enter the mixing chamber and reach an outlet temperature of 75°C.

[0142] Heat transfer coefficient (U): ;

[0143] in, Wastewater flow rate Let A be the specific heat capacity of the wastewater, and let A be the heat transfer area of ​​the mixing chamber (m²). The logarithmic mean temperature difference (°C) Wastewater outlet temperature, The wastewater inlet temperature;

[0144] Steam consumption: ;

[0145] in, Steam flow rate;

[0146] Record the U, heating time, and steam consumption for each experimental group, and repeat the experiment three times, taking the average value. The data are shown in Table 1.

[0147] Table 1

[0148]

[0149] According to the data in Table 1, Example 1 exhibited the highest surface tension reduction rate, shortest heating time, and highest heat transfer coefficient. This is because Example 1 used a surfactant with a mass ratio of 0.1:1 under ultrasonic treatment (30 kHz, 15 min), which formed a uniform emulsion, significantly reducing the interfacial tension (12.0). (mN / m), the ultrasonic cavitation effect promotes the directional arrangement of surfactant molecules at the oil-water interface, while the mechanical shear force refines oil droplets and enhances emulsion stability. A PAC dosage of 1:0.1, combined with initial fast-then-slow stirring (200rpm→50rpm), achieves rapid coagulation and slow sedimentation, avoiding colloid restabilization. Rapid mixing ensures rapid collision and adsorption of PAC and pollutants, while slow stirring prevents the breakage of existing flocs. A steam:wastewater mass ratio of 1:5 ensures hybrid mixing while avoiding excessive dilution, and the steam heat is efficiently utilized. In Comparative Example 1, reducing the surfactant dosage from 0.1:1 to 0.05:1 weakens emulsification and reduces the interfacial adsorption efficiency of oil decomposition products. Due to insufficient emulsification, heat transfer resistance increases, requiring more steam to compensate for heat loss. In Comparative Example 2, excessive surfactant leads to excessive solution dilution, reducing effective adsorption capacity and inhibiting the decrease in interfacial tension. Excessive reagent may also form micelles, hindering heat transfer. In Comparative Example 3, reducing the ultrasonic treatment time from 15min to 10min results in insufficient mixing. Poor surfactant dispersion and reduced mixing efficiency led to a decrease in heat transfer rate. In Comparative Example 4, excessive ultrasonic time (20 min) caused overactive cavitation, resulting in localized high temperatures that decomposed and degraded the surfactant, lowering the final wastewater temperature. Energy was wasted on ineffective cavitation, resulting in a decrease in actual heating efficiency. In Comparative Example 5, the dosage of polyaluminum chloride (PAC) was reduced from 0.1:0.1 to 0.1:0.08, resulting in insufficient coagulation capacity, ineffective destabilization of suspended solids, and impeded mass transfer. Steam consumption increased, and steam heat energy was ineffectively absorbed due to unremoved pollutants. In Comparative Example 6, excessive PAC increased water turbidity, weakened emulsification due to colloid restabilization, and decreased heat transfer coefficient. Excessive coagulant formed secondary precipitation, increasing thermal resistance. In Comparative Example 7, the steam:wastewater ratio was increased from 1:5 to 1:6, leading to excessive dilution of surfactant concentration, reduced emulsification efficiency, and wasted heat energy due to excessive steam. In Comparative Example 8, the steam:wastewater ratio was reduced to 1:4, resulting in insufficient hybridization, inadequate surfactant dispersion, uneven mixing, a significant decrease in heat transfer efficiency, and prolonged heating time.

[0150] Based on the preferred embodiments of the present invention described above, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for heating wastewater using jet mixing, characterized in that, include: S1. Perform coarse filtration, fine filtration and oil removal on wastewater; S2. Add surfactant to the wastewater after S1 treatment and simultaneously apply low-frequency ultrasound at 20-40kHz; wherein the mass ratio of surfactant to wastewater is 0.05-0.15:

1. S3. Add polyaluminum chloride to the wastewater treated by S2 at a certain mass ratio; the certain mass ratio is 1:0.08-0.

15. S4. Perform pH adjustment and scale inhibition pretreatment on the wastewater treated by S3. S5. Stabilize the steam pressure to 0.4-0.8MPa through the pressure reducing valve and inject it into the mixing chamber through the nozzle; S6. Pressurize the wastewater treated in S4 using a high-pressure pump. The pressurized wastewater is then injected into the mixing chamber through a nozzle, alternating with the depressurized steam from S5, and mixed for 3-5 seconds. The mass ratio of the added steam to the wastewater is 1:4-8.

2. The wastewater heating method using jet mixing according to claim 1, characterized in that: In step S1, the specific steps for coarse filtration, fine filtration, and oil removal of the wastewater are as follows: The process involves coarse filtration, where wastewater is passed through a 20μm stainless steel screen made of 316L material, with a flow rate controlled at 10-15 m³ / h and a differential pressure alarm threshold of 0.3 MPa. Fine filtration involves passing the coarsely filtered wastewater through an activated carbon filter at a flow rate of 5-8 m / h to adsorb oil decomposition products and odor substances. The wastewater then enters a ceramic membrane with a transmembrane pressure difference of 0.1-0.3 MPa to trap particles with a diameter ≥1μm. Oil removal is achieved by passing the finely filtered wastewater into an inclined plate oil separator. Oil droplets rise to the surface due to density differences and are collected through an oil collection pipe, resulting in an oil-free inclined plate oil separator.

3. The wastewater heating method using jet mixing according to claim 2, characterized in that: In step S2, the specific steps for adding surfactant to the wastewater after treatment in S1 are as follows: In the wastewater after treatment in S1, the wastewater and surfactant are mixed in a static mixer at a mass ratio of surfactant to wastewater of 0.05-0.15:1, with the flow rate controlled at 1-2 m / s and the mixing time at 1-2 min.

4. The wastewater heating method using jet mixing according to claim 1, characterized in that: In step S2, when low-frequency ultrasound of 20-40kHz is applied simultaneously, the duration of the ultrasound is 10-20 minutes, during which the temperature of the wastewater needs to be kept ≤40℃.

5. The wastewater heating method using jet mixing according to claim 1, characterized in that: In step S3, the specific steps are as follows: the specific steps of adding polyaluminum chloride to the wastewater after treatment in S2 according to a certain mass ratio are as follows: add polyaluminum chloride to the wastewater after treatment in S2 at a mass ratio of 1:0.08-0.15, start the mechanical stirrer, first mix quickly at 200-300 rpm for 2 minutes, and then stir slowly at 50 rpm for 10 minutes to obtain the treated wastewater.

6. The wastewater heating method using jet mixing according to claim 1, characterized in that: In step S4, the specific steps are as follows: by using a pH meter and an online sensor to monitor the pH value of the wastewater in real time, HCl or NaOH is added according to the pH meter data to adjust the pH of the wastewater to 5-7, and then a scale inhibitor is added to inhibit subsequent steam heating or pipe scaling.

7. The wastewater heating method using jet mixing according to claim 1, characterized in that: In step S5, the specific steps are as follows: turn on the steam filter to ensure that the steam is clean, then stabilize the steam pressure at 0.4-0.8MPa through the pressure reducing valve, and monitor the pressure in real time through the pressure gauge to ensure that the pressure fluctuation is ≤±5%.

8. The wastewater heating method using jet mixing according to claim 1, characterized in that: In step S6, the specific steps are as follows: the depressurized steam is injected into the mixing chamber through a fan-shaped nozzle at a flow rate of 10-20 m / s, and the wastewater is pressurized by a high-pressure pump and injected into the mixing chamber from the other nozzle, where it is alternately mixed with the steam and stays in the mixing chamber for 3-5 seconds.

9. The wastewater heating method using jet mixing according to claim 1, characterized in that: The surfactant is a polyoxyethylene ether with a molecular weight of 1000-1500; the low-frequency ultrasound operates intermittently for 10-20 minutes.

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