Efficient polymeric ferric sulfate production process method based on venturi spray reinforcement

Abstract

The invention discloses an efficient polyferric sulfate production process method based on venturi spray reinforcement. According to the method, ferrous sulfate and sulfuric acid are used as raw materials, a sodium nitrite catalytic oxidation process is adopted, efficient gas-liquid contact is achieved through an optimally designed Venturi sprayer, the section ratio of a feeding pipe of the sprayer is 0.25: 1, the length of a central guide pipe is 8 mm, the particle size of atomized liquid drops is 20-50 microns, and the volume ratio of gas to liquid is 5: 1. The process is operated under the conditions of 60-80 DEG C and normal pressure, the reaction time is shortened to 2.3 + / -0.2 hours, the Fe < 2 + > oxidation rate is larger than or equal to 99%, the power consumption is smaller than or equal to 4 kW.h / ton product, and the oxygen consumption is smaller than or equal to 0.9 m < 3 > / kg Fe < 2 + >. The alkalization degree of the product is stabilized at 0.78 + / -0.05, the total iron content is greater than or equal to 21.8%, and the content of water insoluble substances is less than or equal to 0.25%. Compared with a traditional process, the method has the advantages that the reaction time is shortened by 71.3%, the production cost is reduced by 30%, and the method is suitable for the fields of preparation of inorganic polymeric flocculants and industrial water treatment. The technical problems that in a traditional process, the aging is long, the cost is high, and environmental friendliness is difficult to consider are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic polymer flocculants, and particularly relates to a high-efficiency polymeric ferric sulfate production process method based on Venturi spray strengthening and application thereof. BACKGROUND

[0002] As a high-efficiency inorganic polymer flocculant, polymeric ferric sulfate (PFS) is widely used in wastewater treatment, industrial wastewater treatment and other fields. The traditional PFS production process mainly adopts air oxidation method or direct oxidation method of strong oxidizing agent, which has the following technical defects: low oxidation efficiency, the oxidation efficiency of the traditional air oxidation method is only 80-90% due to the limited gas-liquid contact area, and the reaction time is as long as 8-12 hours; high energy consumption, the power consumption per ton of product is as high as 120 kWh, and the oxygen utilization rate is less than 70%; unstable product quality: the alkalization degree of the product fluctuates greatly (±0.3), and hydrolysis precipitation phenomenon is easy to occur; environmental pollution, the traditional process has a large amount of NO X emissions, which has environmental hidden dangers. In the prior art, although some processes use strong oxidizing agents (such as NaClO3 and H2O2) to improve the reaction speed, there are the following problems: local reaction is violent, resulting in temperature out of control; the product is easy to gelatinize, and has poor stability; the residual oxidizing agent affects the purity of the product.

[0003] In view of the above problems, it is urgent to develop an efficient, energy-saving and environmentally friendly polymeric ferric sulfate production process, which can significantly improve the production efficiency and reduce the production cost while ensuring the product quality. SUMMARY

[0004] The present application provides a high-efficiency polymeric ferric sulfate production process based on Venturi spray strengthening, which can solve the problems of low oxidation efficiency, long reaction time and high energy consumption in the existing polymeric ferric sulfate production process. By optimizing the structure and process parameters of the Venturi sprayer, the gas-liquid contact efficiency is significantly improved, rapid oxidation and efficient polymerization are realized, and the polymeric ferric sulfate product prepared has good stability and uniform alkalization degree. The process is simple and controllable, easy to industrialize, and the polymeric ferric sulfate product prepared has excellent flocculation performance, which is very suitable for industrial wastewater treatment and other fields.

[0005] To achieve the above purpose, the present application provides a polymeric ferric sulfate production process based on Venturi spray strengthening, which comprises the following steps:

[0006] (1) Raw material preparation: mix ferrous sulfate and sulfuric acid in a mass ratio of 1:0.3-0.5 to prepare a solution with a total iron concentration of 10-15%, and add sodium nitrite as a catalyst, the dosage being 0.5-1% of the molar mass of Fe 2+ ;

[0007] (2) Spray oxidation: the mixed solution is atomized and sprayed into the reactor by a Venturi spray device, the reaction liquid volume is controlled to be 1 / 3 of the total volume of the reactor, oxygen is introduced into the reactor for oxidation reaction, the temperature is maintained at 60-80℃, and the reaction time is 2.3±0.2 hours;

[0008] (3) Tail gas treatment: the tail gas containing NO X is introduced into a denitrator, and oxygen is filled for recycling, and the oxygen filling amount is 10-20% of the tail gas volume;

[0009] (4) Maturation polymerization: the oxidation liquid is matured at 70-90℃ for 1-2 hours, the alkalization degree B is adjusted to 0.5-1.0, and the liquid polymeric ferric sulfate product is obtained.

[0010] In an embodiment of the present application, in step (2), the cross-sectional ratio of the feed pipe of the Venturi spray device is 0.2-0.32:1, and the length of the central guide pipe is 6-10mm.

[0011] Further, the throat flow rate v is 18-22m / s, and the feed pressure P is 0.25-0.35MPa.

[0012] The relationship between the throat flow rate v and the feed pressure P satisfies the formula:

[0013] Wherein ρ is the liquid density, C d is the flow coefficient 0.85-0.95.

[0014] In step (2), the atomized droplet particle size of the Venturi spray device is 20-50μm, and the gas-liquid volume ratio is 4.8:1-5.2:1, which satisfies the formula:

[0015] Wherein d is the droplet particle size, σ is the surface tension, ρ g is the gas density, U g is the gas velocity, and K is the empirical coefficient.

[0016] Wherein the optimized cross-sectional ratio design can ensure that the liquid passes through the throat at high speed, enhancing the atomization effect; the guide pipe length of 6-8mm can balance the gas flow resistance and mixing efficiency; the atomized particle size of 20-50μm can significantly improve the oxygen mass transfer efficiency.

[0017] In step (2), the reaction temperature is controlled at 60-70℃, the temperature distribution is monitored in real time by infrared thermal imaging to avoid local overheating; an automatic pH adjusting system is used to maintain pH=0.5-1.0, and the control accuracy can reach ±0.1. Accurate temperature and pH control is the key to ensure reaction efficiency and product quality.

[0018] In step (3), the denitrifier operates at a temperature of 40-60°C and is equipped with a tail gas heat recovery device to reduce system energy consumption. A multi-stage oxygen distribution system ensures uniform oxygen concentration within the reactor and improves oxygen utilization.

[0019] In step (4), the alkalinity is precisely controlled by the amount of sulfuric acid added and the aging time, with the fluctuation range controlled within ±0.05. A stable alkalinity is an important guarantee for the product to have excellent flocculation performance.

[0020] Furthermore, in step (2), the throat flow rate of the Venturi sprayer is 18-22 m / s, the feed pressure is 0.25-0.35 MPa, the system power consumption is ≤4 kW·h / ton product, and the oxygen consumption is ≤0.9m 3 / kg Fe 2+ Compared with the traditional process, energy consumption is reduced by 29.2% and oxygen consumption is reduced by 33.3%.

[0021] Furthermore, in step (4), the total iron content of the liquid product is ≥21.8%, the water-insoluble matter is ≤0.25%, and the alkalinity B is 0.78±0.05, and the product performance is significantly better than the national standard requirements.

[0022] Furthermore, in step (1), the sodium nitrite catalyst can be replaced by nitric acid, and the dosage is Fe 2+ The molar amount is 1-2%, and different catalysts can be flexibly selected according to actual production conditions.

[0023] Furthermore, in step (4), the liquid product can be prepared into a solid product by spray drying, the spray drying condition is a hot air temperature of 120-150° C., the moisture content of the solid product is ≤5%, and the solid product is more convenient for storage and transportation.

[0024] The present invention provides a high-efficiency polyferric sulfate product prepared according to the above preparation method. The polyferric sulfate product provided by the present invention can be used in fields such as industrial wastewater treatment and municipal sewage treatment, and is particularly suitable for treating high-turbidity wastewater, printing and dyeing wastewater, and phosphorus-containing wastewater.

[0025] Beneficial effects of the present invention

[0026] (1) The present invention significantly improves gas-liquid mass transfer efficiency through an optimized Venturi spray oxidation process, significantly shortening the oxidation reaction time of ferrous sulfate solution from 8 hours in the traditional process to 2.3 hours, increasing production efficiency by more than three times. The Venturi sprayer's unique 0.25:1 cross-sectional ratio and 8mm central conduit ensure efficient atomization and oxygen utilization.

[0027] (2) The application adopts catalytic oxidation-thermal polymerization integrated process, and product performance is significantly improved. Through testing, the prepared polymeric ferric sulfate product has total iron content ≥21.8% (national standard ≥18.5%), alkalization degree is stably 0.78±0.05, and water insoluble substance ≤0.25%. In wastewater treatment application, flocculation and sedimentation speed is increased by 30% compared with traditional products, COD removal rate ≥85%, and TP removal rate ≥95%.

[0028] (3) The process can significantly reduce energy consumption, and power consumption ≤4 kW·h / ton product (traditional process 120 kW·h / ton), oxygen consumption ≤0.9 m 3 / kg Fe 2+ (Traditional process 1.2 m 3 / kg), and comprehensive production cost is reduced by 30%. The tail gas recycling system and heat recovery device further improve the environmental protection and economy of the process.

[0029] (4) The polymeric ferric sulfate product prepared by the application has good stability, liquid product can be stored for 6 months without precipitation, solid product has water content ≤5%, and is convenient for transportation and long-term storage. The process equipment has strong universality, simple operation, and is very suitable for large-scale industrial production, and has been successfully applied in many wastewater treatment projects.

[0030] (5) The process is environmentally friendly, adopts a closed reaction system and a tail gas treatment device, and NO X emission is reduced by more than 90%, solving the pollution problem of traditional processes and meeting the requirements of green chemical production. The product does not contain harmful substances such as heavy metals, and is safe and reliable in application in the water treatment field. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The flow chart for the production of polymeric ferric sulfate of the application is shown. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0033] The application will be further described below through specific embodiments:

[0034] The raw materials used in the following examples and comparative examples are as follows:

[0035] Ferrous sulfate: industrial grade, FeSO4·7H2O content ≥98%;

[0036] Concentrated sulfuric acid: industrial grade, concentration 98%;

[0037] Sodium nitrite: industrial grade, purity ≥ 99%;

[0038] Oxygen: industrial grade, purity ≥ 99.5%.

[0039] Example 1

[0040] A method for preparing high-efficiency polymeric ferric sulfate, the specific steps are as follows:

[0041] (1) Raw material preparation: 2500 kg of ferrous sulfate (FeSO4·7H2O) is mixed with 200 kg of concentrated sulfuric acid (98%), 1000 L of water is added to prepare a solution with a total iron concentration of 12%, and 180 kg of sodium nitrite is added as a catalyst.

[0042] (2) Spray oxidation: the mixed solution is atomized and sprayed into the reactor through a Venturi spray device (feed pipe cross section ratio 0.25:1, center pipe length 8 mm), the reaction liquid volume is controlled to be 1 / 3 of the total volume of the reactor. Oxygen is introduced into the reactor, the gas-liquid volume ratio is 5:1, the oxygen flow is 8 m 3 / h. The reaction temperature is controlled at 65℃, and the reaction time is 2.3 hours.

[0043] (3) Tail gas treatment: the tail gas containing NO X is introduced into a denitrator, and oxygen is circulated and utilized at 50℃, and the oxygen charging amount is 15% of the tail gas volume.

[0044] (4) Maturation polymerization: the oxidation liquid is matured at 80℃ for 1.5 hours, the alkalization degree B=0.78 is adjusted, and the liquid polymeric ferric sulfate product is obtained.

[0045] Example 2

[0046] A method for preparing high-efficiency polymeric ferric sulfate, the specific steps are as follows:

[0047] (1) Raw material preparation: 2500 kg of ferrous sulfate (FeSO4·7H2O) is mixed with 200 kg of concentrated sulfuric acid (98%), 1000 L of water is added to prepare a solution with a total iron concentration of 13%, and 130 kg of sodium nitrite is added as a catalyst.

[0048] (2) Spray oxidation: the mixed solution is atomized and sprayed into the reactor through a Venturi spray device (feed pipe cross section ratio 0.25:1, center pipe length 8 mm), the reaction liquid volume is controlled to be 1 / 3 of the total volume of the reactor. Oxygen is introduced into the reactor, the gas-liquid volume ratio is 5:1, the oxygen flow is 10 m 3 / h. The reaction temperature is controlled at 60℃, and the reaction time is 2.5 hours.

[0049] (3) Tail gas treatment: X The tail gas is introduced into the denitrifier and filled with oxygen at 55°C for recycling. The oxygen filling amount is 18% of the tail gas volume.

[0050] (4) Ripening and polymerization: The oxidizing liquid was aged at 85° C. for 2 hours, and the alkalinity B was adjusted to 0.80 to obtain a liquid polyferric sulfate product.

[0051] Example 3

[0052] A method for preparing high-efficiency polyferric sulfate, the specific steps of which are as follows:

[0053] ((1) Raw material preparation: 2500 kg of ferrous sulfate (FeSO4·7H2O) was mixed with 200 kg of concentrated sulfuric acid (98%), and 1000 L of water was added to prepare a solution with a total iron concentration of 13%, and 100 kg of sodium nitrite was added as a catalyst.

[0054] (2) Spray oxidation: The mixed liquid was sprayed into the reactor through a Venturi spray device (feed pipe cross-section ratio 0.25:1, central conduit length 8mm), and the reaction liquid volume was controlled to be 1 / 3 of the total volume of the reactor. Oxygen was introduced into the reactor with a gas-liquid volume ratio of 5:1 and an oxygen flow rate of 10m 3 The reaction temperature was controlled at 70°C and the reaction time was 2.5 hours.

[0055] (3) Tail gas treatment: X The tail gas is introduced into the denitrifier and filled with oxygen at 55°C for recycling. The oxygen filling amount is 18% of the tail gas volume.

[0056] (4) Ripening and polymerization: The oxidizing liquid was aged at 85° C. for 2 hours, and the alkalinity B was adjusted to 0.80 to obtain a liquid polyferric sulfate product.

[0057] Example 4

[0058] A method for preparing high-efficiency polyferric sulfate, the specific steps of which are as follows:

[0059] (1) Prepare liquid polyferric sulfate according to steps (1) to (3) of Example 1;

[0060] (2) Spray drying:

[0061] The liquid product is pumped into a Venturi sprayer and atomized and dried in contact with 140°C hot air. The outlet temperature of the drying tower is 80°C. The collected powder is sieved through an 80-mesh sieve to obtain a solid polymerized ferric sulfate product with a moisture content of ≤5%.

[0062] Comparative Example 1

[0063] Preparation of polyferric sulfate by traditional air oxidation method:

[0064] (1) The raw material preparation is the same as in Example 1;

[0065] (2) Oxidation reaction:

[0066] The mixed solution was introduced into the reactor and oxidized by air bubbling at a temperature of 70°C for 8 hours.

[0067] (3) Ripening polymerization:

[0068] The oxidizing solution was aged at 80°C for 3 hours to adjust the alkalinity B to 0.75.

[0069] Table 1 below shows the performance test results of Examples 1-4 of the present invention and Comparative Example 1.

[0070] Table 1

[0071]

[0072] Comparative Example 2

[0073] A parameter optimization comparison experiment of a polyferric sulfate preparation method, the specific steps are as follows:

[0074] (1) Raw material preparation

[0075] 2500 kg of ferrous sulfate (FeSO4·7H2O) was mixed with 200 kg of concentrated sulfuric acid (98%), and 1000 L of water was added to prepare a solution with a total iron concentration of 12%, and 180 kg of sodium nitrite was added as a catalyst.

[0076] (2) Spray oxidation

[0077] The mixed liquid was sprayed into the reactor through a venturi spray device with different structural parameters, and the volume of the reaction liquid was controlled to be 1 / 3 of the total volume of the reactor. Oxygen was introduced into the reactor with an oxygen flow rate of 8m 3 / h, and the reaction temperature was controlled at 65±5℃. The specific experimental groups are as follows:

[0078] The present invention group: Venturi sprayer cross-section ratio 0.25:1, central tube length 8mm, atomized particle size 20-50μm, gas-liquid volume ratio 5:1, reaction time 2.3 hours;

[0079] Satisfies the formula:

[0080]

[0081] Where d is the droplet size, σ is the surface tension, and ρ g is the gas density, U g is the gas velocity, and K is the empirical coefficient.

[0082] Control 1 group: cross-section ratio 0.20:1, other parameters same as Example 3.

[0083] Control 2 group: cross-section ratio 0.32:1, other parameters same as Example 3.

[0084] Control 3 group: conduit length 6mm, other parameters same as Example 3.

[0085] Control 4 group: conduit length 10mm, other parameters same as Example 3.

[0086] Fixed feed pressure P = 0.30MPa, throat velocity v = 20.1m / s;

[0087] Satisfy the formula:

[0088] Where ρ is the liquid density, C d is the flow coefficient 0.85-0.95, the following table of parameters shown in Table 2:

[0089] Table 2

[0090] Gas-liquid volume ratio <![CDATA[气体流量Q g (m 3 / h)]]> Liquid flow rate Q l (L / h) Atomized particle size d (μm) 4.8:1 288 60 42.5 5.0:1 300 60 41.2 5.2:1 312 60 39.8

[0091] As shown in Table 2, the atomized particle size decreases with increasing pressure (48.2μm→37.9μm), indicating that high pressure can improve the atomization effect.

[0092] (3) Exhaust gas treatment

[0093] The exhaust gas containing NO X is introduced into the denitrator, and oxygen is circulated at 50℃, and the oxygen filling amount is 15% of the exhaust gas volume.

[0094] (4) Maturation polymerization

[0095] The oxidation liquid is matured at 80℃ for 1.5 hours, the alkalinity B = 0.78 is adjusted, and the liquid polymeric ferric sulfate product is obtained.

[0096] The following Table 3 shows the performance test results of the present application comparative example 2.

[0097] Table 3

[0098]

[0099] In the above Example 3, by increasing the pressure to 0.32MPa and the gas-liquid ratio to 5.2:1, the particle size is controlled in the range of 25-45μm, the oxidation rate is increased to 99.5%, and the power consumption and oxygen consumption are reduced, and the particle size is adjusted to a more reasonable range (30-50μm), and the oxidation rate is increased to 98.1%.

[0100] Performance testing of the present invention's process and conventional processes and parameter comparisons showed that the polyferric sulfate production process using a specific Venturi sprayer structure (cross-sectional ratio 0.25:1 + conduit length 8 mm) exhibited a significant critical point effect on key technical indicators. In terms of reaction efficiency, the reaction time of Examples 1-4 of the present invention was stabilized at 2.3-2.5 hours, a reduction of more than 70% compared to the 8 hours of the conventional process, significantly improving production efficiency.

[0101] In terms of product quality, the total iron content of the product of the present invention reaches 21.5-21.8%, which is higher than the 20.3% of the traditional process and the 20.8-21.2% of the control group; the alkalinity is stable in the range of 0.77-0.80, and the fluctuation range is smaller than that of the traditional process (±0.3) and the control group (±0.15); the water-insoluble matter content is only 0.22-0.28%, which is significantly lower than the 0.45% of the traditional process and the 0.30-0.35% of the control group, showing better product purity and stability. In terms of energy consumption indicators, the electricity consumption per ton of product of the process of the present invention is 3.8-4.2kWh, which is 7-27% lower than the 4.1-5.2kWh of the control group and 96.8% lower than the 120kWh of the traditional process; the oxygen consumption is 0.87-0.90m 3 / kg Fe 2+ , compared with 0.93-1.12m in the control group 3 / kg is optimized by 6.5-22.3%, compared with the traditional process of 1.2m 3 In actual application tests, the COD removal rate of the product of the present invention reaches 85-88%, which is 7-10 percentage points higher than that of the traditional process, the TP removal rate is ≥95%, and the flocculation sedimentation rate is increased by 30%.

[0102] Of particular note, the solid product (Example 4) prepared via spray drying maintains the excellent properties of the liquid product while maintaining a moisture content below 5% and exhibiting 12 months of storage stability without agglomeration. These test data fully validate the technical criticality of a 0.25:1 cross-sectional ratio and an 8mm tube length, and their combined advantages in terms of reaction efficiency, product quality, energy consumption control, and practical application, providing a precise control solution for industrialized polyferric sulfate production.

[0103] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A high-efficiency polyferric sulfate production process based on Venturi spray intensification, characterized in that The following steps are involved: Step 1: Mix ferrous sulfate and sulfuric acid in a mass ratio of 1:0.3-0.5, and add water to prepare a solution with a total iron concentration of 10-15%; Step 2: Add sodium nitrite catalyst in an amount of Fe 2+ 0.5-1% of molar mass; Step 3: atomizing the mixed liquid and spraying it into the reactor through a Venturi spray device; Step 4: introducing oxygen into the reactor for oxidation reaction, maintaining the temperature at 60-80°C, and the reaction time is 2.1-2.3 hours; Step 5: Add NO X The tail gas is introduced into the denitrifier for treatment, and the oxygen charging amount is 10-20% of the tail gas volume; Step 6: Mature the polymer solution for 1-2 hours and adjust the alkalinity B to 0.5-1.

0.

2. The high-efficiency polyferric sulfate production process based on Venturi spray enhancement according to claim 1 is characterized in that: The feed pipe cross-sectional ratio of the Venturi sprayer is 0.2-0.32:1, and the length of the central conduit is 6-10 mm.

3. The high-efficiency polyferric sulfate production process based on Venturi spray enhancement according to claim 2, characterized in that: The throat flow velocity v is 18-22 m / s, and the feed pressure P is 0.25-0.35 MPa. The relationship between the throat flow velocity v and the feed pressure P satisfies the formula: Where ρ is the liquid density, C d The flow coefficient is 0.85–0.

95.

4. The high-efficiency polyferric sulfate production process based on Venturi spray enhancement according to claim 1 is characterized in that: The atomized droplet size of the Venturi sprayer is 20-50 μm, and the gas-liquid volume ratio is 4.8:1-5.2:1, satisfying the formula: Where d is the droplet size, σ is the surface tension, and ρ g is the gas density, U g is the gas velocity, and K is the empirical coefficient.

5. The high-efficiency polyferric sulfate production process based on Venturi spray enhancement according to claim 1 is characterized in that: By matching the cross-sectional ratio of the Venturi sprayer to 0.2-0.32:1 and the conduit length to 6-10 mm, the throat flow rate of the Venturi sprayer is 18-22 m / s and the feed pressure is 0.25-0.35 MPa.

6. The process for producing high-efficiency polyferric sulfate based on Venturi spray enhancement according to claim 1, characterized in that: The operating temperature of the reactor was 60-70°C, and the temperature distribution was monitored by infrared thermal imaging.

7. The process for producing high-efficiency polyferric sulfate based on Venturi spray enhancement according to claim 1, characterized in that: The operating temperature of the denitrifier is 40-60°C.

8. The process for producing high-efficiency polyferric sulfate based on Venturi spray enhancement according to claim 1, characterized in that: When nitric acid is used instead of sodium nitrite, the reaction temperature is adjusted to 70-90° C. and the reaction time is extended to 3-4 hours.

9. The high-efficiency polyferric sulfate production process based on Venturi spray enhancement according to claim 1, characterized in that: During the reaction, the amount of sulfuric acid added was controlled by online pH monitoring to maintain pH = 0.5-1.

0.

10. Polyferric sulfate prepared according to any one of claims 1 to 9.

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