Method for preparing powder from high-viscosity fluid amide polymer through spray drying

Abstract

The invention relates to a method for preparing powder from a high-viscosity fluid amide polymer through spray drying, and belongs to the technical field of high polymer material drying. The method comprises the following steps: mixing a high-viscosity fluid amide polymer aqueous solution with water to obtain a feed liquid with the solid content of 5-15%; hot water is introduced into a jacket of a feed liquid tank, and the feed liquid is preheated to 60-80 DEG C in cooperation with stirring of a double-layer stirring paddle; the preheated feed liquid is pumped into a spray dryer, atomized and dried at the centrifugal atomization rotating speed of 25,000-35000 rpm, and wall adhesion is prevented in the drying process through a rotary sweeping mechanism and a mode of introducing cold air to the tower wall; and collecting the dried powder through cyclone separation. According to the method disclosed by the invention, the problems of agglomeration, wiredrawing, molecular chain degradation and wall sticking in the drying process of the high-viscosity polymer are effectively solved by optimizing systematic synergy of feed liquid pretreatment, atomization and drying parameters on the premise of not adding any dispersing agent, and high-quality powder with low water content, quick dissolution, high molecular weight retention rate and purity greater than 99.9% is obtained; the process is simple, green and easy for industrial production.

Description

Technical Field

[0001] This invention relates to the field of polymer drying technology, specifically to a method for preparing powder from a high-viscosity flowable amide polymer by spray drying. Background Technology

[0002] Polyacrylamide (PAM), as an important water-soluble polymer, is widely used in various industrial fields such as water treatment, oil extraction, papermaking, and textiles due to its excellent flocculation, thickening, and adsorption bridging properties. Among them, the market demand for dry powder form of polyacrylamide continues to rise due to its advantages such as convenient storage, low transportation costs, and ease of use.

[0003] However, the strong hydrogen bonds between polyacrylamide molecular chains and its prominent hydrophilicity make it prone to agglomeration and clumping during drying, making it difficult to directly form a loose and uniform powder. To solve this technical problem, existing technologies generally employ the addition of dispersants (such as inorganic acid salts, surfactants, etc.) before or during drying to inhibit agglomeration by disrupting intermolecular forces and reducing surface tension. For example, patent CN105566539B discloses a fast-dissolving nonionic polyacrylamide dry powder with a microporous structure and its preparation method, which achieves particle dispersion by adding foaming agents and additives. However, the addition of dispersants has many drawbacks: on the one hand, it increases production costs and the difficulty of subsequent separation and purification, leading to a decrease in purity; on the other hand, residual dispersants may affect the application performance of polyacrylamide in specific fields and even cause secondary pollution.

[0004] In terms of applications, the performance requirements for polyacrylamide vary and are becoming increasingly stringent across different fields. In sludge dewatering, single polyacrylamide flocculants suffer from low cationicity, limited dewatering effect, and poor biodegradability. Long-term use may pose a potential threat to the environment and human health due to residual monomers. In coal slurry water treatment, traditional flocculants either have drawbacks such as large dosage, high cost, and risk of secondary pollution, or poor biodegradability and unstable flocculation effect, making them unsuitable for complex coal slurry water with high turbidity, high organic load, or heavy metal content. In oil extraction, conventional oil displacement agents formulated with polyacrylamide and surfactants are prone to separation in high-temperature and high-salinity reservoir environments, leading to a weakened synergistic effect and a significant decrease in shear resistance and oil displacement efficiency, failing to meet the extraction needs of complex reservoirs.

[0005] Furthermore, existing spray drying processes for high-viscosity polyacrylamide face a contradiction between drying temperature and molecular weight retention: low-temperature drying leads to excessive moisture content, while high-temperature drying easily causes molecular chain degradation. Even with the addition of dispersants, problems such as slow dissolution rate, uneven bulk density, and high energy consumption still exist. Meanwhile, the preparation and application of polyacrylamide also face other technical bottlenecks: for example, patent CN120463846A discloses a method for preparing polyacrylamide, polyacrylamide, and its application, pointing out that traditional preparation methods suffer from uneven molecular weight distribution of the product, limiting its application scope; patent CN120647113A discloses a highly efficient sludge dewatering agent, cationically modified chitosan-polyacrylamide supported on wood ash, its preparation method, and its application, mentioning that single polyacrylamide flocculants have low cationicity and limited dewatering effect in the field of sludge dewatering, and that the polymer monomer acrylamide, as a known neuropolymer, is also problematic. Toxins, long-term use may pose potential threats to human health and the environment; Patent CN120887534A discloses a method for preparing a flocculant for coal slurry water treatment, revealing that traditional inorganic flocculants for treating coal slurry water require large quantities, are costly, and easily introduce metal ions, causing secondary pollution, while single polyacrylamide-based organic flocculants have problems with poor biodegradability and long-term accumulation that pollutes the environment; Patent CN121108966A shows that conventional oil displacement agents compounded with polyacrylamide and surfactants are prone to separation in high-temperature and high-salinity oil reservoir environments, resulting in a weakened synergistic effect and a significant decrease in shear resistance and oil displacement efficiency.

[0006] Therefore, the development of a polyacrylamide preparation and drying method that requires no dispersant, has a simple process, low energy consumption, and can achieve precise molecular weight control and adapt to the special needs of multiple fields has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing powder from high-viscosity flowable amide polymers by spray drying. By precisely controlling the process parameters, the method achieves efficient drying and powdering of high-viscosity flowable amide polymer aqueous solutions without adding any dispersants or stabilizers, while ensuring low moisture content, good dispersibility, and high molecular weight retention.

[0008] The technical problem solved by this invention is achieved through the following technical solution: A method for preparing powder from a high-viscosity, flowable amide polymer by spray drying, characterized by comprising the following steps: Step 1, Material Pretreatment: A high-viscosity amide polymer aqueous solution is mixed with water at a mass ratio and stirred using a double-layer agitator. The lower agitator rotates at 100 rpm to stir the high-viscosity sediment at the bottom of the liquid, while the upper agitator rotates at 500 rpm to stir the material on the upper layer of the liquid. The mixture yields a liquid with a solid content of 5% to 15%. Hot water is introduced into the jacket of the liquid tank, and the temperature sensor installed on the tank wall monitors the temperature gradient of the liquid in real time to ensure that the temperature gradient of the liquid is ≤2℃. The liquid is preheated to 60-80℃ and continuously kept warm and stirred to eliminate the internal temperature gradient of the liquid. Step 2, Spray drying: Centrifugal atomization is used to pump the preheated liquid to the atomizer of the spray dryer, with the atomizer speed at 25,000-35,000 rpm. The inlet air temperature of the drying chamber is controlled at 130-155℃, and the outlet air temperature is controlled at 70-105℃. The drying chamber is kept under negative pressure. A rotating cleaning mechanism is installed inside the drying tower, and cold air is introduced through the gaps in the inner wall of the drying tower. Step 3, Product Collection: After separation by a cyclone separator, polyacrylamide powder is collected; the exhaust gas after separation is treated by dust removal before being discharged.

[0009] Furthermore, in step 1, the solid content of the high-viscosity amide polymer aqueous solution after mixing with water is 8.33%, and the preheating temperature of the liquid is 70°C.

[0010] Furthermore, in step 2, the atomizer speed is 30,000 rpm, the inlet air temperature is 150°C, and the outlet air temperature is 90°C.

[0011] Furthermore, the prepared polyacrylamide powder has a moisture content of ≤5%, a particle size D50 of 18.81 μm, and a molecular weight retention rate of ≥97%.

[0012] Furthermore, in step 2, the hot air and the liquid droplets move in parallel.

[0013] Furthermore, the molecular weight parameters of the high-viscosity fluidized amide polymer aqueous solution are as follows: determined by aqueous gel permeation chromatography, calibrated using polyethylene glycol as a standard, the weight-average relative molecular weight is 60.0 × 10⁻⁶. 4 -120.0×10 4 g / mol, number-average relative molecular weight is 15.0 × 10⁻⁶ g / mol. 4 -30×10 4 g / mol, polydispersity is 2.8-3.8.

[0014] Furthermore, the detection conditions included: the mobile phase was water, the detector was a differential refractive index detector, and the Mark-Houwink parameter K = 14.1 × 10⁻⁶. -5 dL / g, α=0.7, calibration type is narrow calibration.

[0015] The advantages and positive effects of this invention are: 1. The present invention provides a method for preparing powder from high-viscosity flowable amide polymer by spray drying. This method does not require the addition of dispersants. By optimizing the liquid-to-material ratio, preheating temperature and spray drying parameters, the problem of agglomeration and stringing of high-viscosity flowable amide polymer aqueous solution during drying is fundamentally solved. This method avoids the cost increase and performance impact caused by dispersants. The product purity is greater than 99.9%.

[0016] 2. The method for preparing powder from high-viscosity fluidized amide polymer by spray drying of the present invention is simple and efficient, eliminating the need for dispersant addition, mixing, separation and other steps, shortening the process flow, and drying time is only 20-30 seconds; compared with drying processes such as drying and microwave drying, there is no need for pulverization.

[0017] 3. The method for preparing powder from the high-viscosity fluidized amide polymer of this invention via spray drying results in a product with excellent performance. During the drying process, the material is dried at a low temperature, with a molecular chain degradation rate of ≤3% and a molecular weight retention rate of ≥97%. The product has a moisture content of ≤5%, uniform particle size distribution (D50=18±0.81μm), and a bulk density of 300kg / m³. 3 Its dissolution time in water is less than 10 seconds, which is significantly better than existing products with added dispersants.

[0018] 4. The method for preparing powder from high-viscosity flowable amide polymer by spray drying of the present invention has strong applicability. The process parameters can be finely adjusted according to the characteristics of the aqueous solution of high-viscosity flowable amide polymer without changing equipment. It is easy to scale up industrial production and has no waste discharge, which meets the requirements of green production.

[0019] 5. The present invention provides a method for preparing powder from high-viscosity fluidized amide polymer by spray drying. The method features an innovative structure, with a double-layer stirring paddle and hot water design to precisely control the temperature gradient of the liquid to ≤2℃, effectively avoiding molecular chain pre-degradation caused by local overheating and further improving the molecular weight retention rate. The dual anti-sticking design of the rotating cleaning mechanism inside the drying tower and the cold air introduced through the gap between the inner wall of the drying tower solves the problem of material sticking to the wall and ensures product yield. Attached Figure Description

[0020] Figure 1 The image shows the dried polyacrylamide colloid with a solid content of 15%, prepared by the spray drying method of the high-viscosity flowable amide polymer of the present invention. Figure 2 This is a photograph of the dried polyacrylamide colloid with a solid content of 12.5% ​​according to the present invention. Figure 3 This is a photograph of the dried polyacrylamide colloid with a solid content of 8.3% according to the present invention. Figure 4This is a particle size distribution diagram of the dried polyacrylamide colloidal product with a solid content of 8.3% according to the present invention. Detailed Implementation

[0021] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0022] This invention discloses a method for preparing powder from a high-viscosity fluid amide polymer via spray drying. The method involves polymerizing a high-viscosity fluid polymer from monomers containing amide or olefin groups, such as acrylamide (AM), acrylic acid (AA), and 2-acrylamido-2-methylpropanesulfonic acid (AMPS), via aqueous solution polymerization. The powder is prepared by optimizing the spray drying process parameters. The molecular weight parameters of the high-viscosity fluid amide polymer aqueous solution are as follows: determined by aqueous gel permeation chromatography (GPC) and calibrated using polyethylene glycol as a standard, the weight-average relative molecular weight is 60 × 10⁻⁶. 4 -120×10 4 g / mol, number-average relative molecular weight is 15 × 10⁻⁶ g / mol 4 -30×10 4 g / mol, polydispersity 2.8-3.8. Detection conditions included: mobile phase water, detector a refractive index detector (RID), Mark-Houwink parameter K = 14.1 × 10⁻⁶. -5 dL / g, α=0.7, calibration type is narrow calibration.

[0023] Example 1: like Figure 1 As shown, a method for preparing powder from a high-viscosity flowable amide polymer by spray drying is described: Step 1, Material Pretreatment: A high-viscosity, fluid amide polymer aqueous solution was selected (GPC analysis showed a weight-average relative molecular weight of 68.68 × 10⁻⁶). 4 g / mol, number-average relative molecular weight 20.40 × 10⁻⁶ g / mol 4 (g / mol, polydispersity 3.37), mixed with water, stirred with a double-layer impeller, the lower impeller rotates at 100 rpm to stir the high-viscosity sediment at the bottom of the liquid, and the upper impeller rotates at 500 rpm to stir the upper layer of the liquid, to obtain a liquid with a solid content of 15%. Hot water is introduced into the jacket of the liquid tank, and the temperature gradient of the liquid is monitored in real time by a temperature sensor installed on the tank wall to ensure that the temperature gradient of the liquid is ≤2℃. The liquid is preheated to 70℃ and continuously kept warm and stirred to eliminate the internal temperature gradient of the liquid and avoid local overheating that could lead to pre-degradation of molecular chains.

[0024] Step 2, Spray drying: Centrifugal atomization is used to pump the preheated liquid material to the atomizer of the spray dryer at a speed of 32,000 rpm. The inlet air temperature of the drying chamber is 150℃, the outlet air temperature is 92℃, the internal negative pressure of the drying chamber is -0.035MPa, the hot air velocity is 12m / s, and the hot air and the liquid droplets move in parallel. The rotating cleaning mechanism inside the drying tower is activated, and cold air is introduced into the gaps in the inner wall of the drying tower to prevent the material from sticking to the wall.

[0025] Step 3, Product Collection: After separation by a cyclone separator, polyacrylamide powder is collected; the exhaust gas after separation is treated by dust removal before being discharged.

[0026] The results of the polyacrylamide powder test are as follows: moisture content is less than 3.2%, and molecular weight retention is 97.2%.

[0027] No dispersants, stabilizers, or foaming agents are added throughout the process.

[0028] Example 2: like Figure 2 As shown, a method for preparing powder from a high-viscosity flowable amide polymer by spray drying is described: Step 1, Material Pretreatment: A high-viscosity, fluid amide polymer aqueous solution was selected (GPC analysis showed a weight-average relative molecular weight of 68.68 × 10⁻⁶). 4 g / mol, number-average relative molecular weight 20.40 × 10⁻⁶ g / mol 4 (g / mol, polydispersity 3.37) is mixed with water and stirred with a double-layer impeller. The lower impeller rotates at 100 rpm to stir the highly viscous sediment at the bottom of the liquid, while the upper impeller rotates at 500 rpm to stir the upper layer of the liquid. The mixture yields a liquid with a solid content of 12.5%. Hot water is introduced into the jacket of the liquid tank, and the temperature gradient of the liquid is monitored in real time by a temperature sensor installed on the tank wall to ensure that the temperature gradient of the liquid is ≤2℃. The liquid is preheated to 70℃ and continuously kept warm and stirred to eliminate the internal temperature gradient of the liquid and avoid local overheating that could lead to pre-degradation of molecular chains.

[0029] Step 2, Spray drying: Centrifugal atomization is used to pump the preheated liquid material to the atomizer of the spray dryer at a speed of 28,000 rpm. The inlet air temperature of the drying chamber is 150℃, the outlet air temperature is 88℃, the internal negative pressure of the drying chamber is -0.045MPa, the hot air velocity is 12m / s, and the hot air and the liquid droplets move in parallel. The rotating cleaning mechanism inside the drying tower is activated, and cold air is introduced into the gaps in the inner wall of the drying tower to prevent the material from sticking to the wall.

[0030] Step 3, Product Collection: After separation by a cyclone separator, polyacrylamide powder is collected; the exhaust gas after separation is treated by dust removal before being discharged.

[0031] The results of the polyacrylamide powder test are as follows: moisture content is less than 2.8%, and molecular weight retention is 97.5%.

[0032] No dispersants, stabilizers, or foaming agents are added throughout the process.

[0033] Example 3: like Figure 3 , Figure 4 As shown, a method for preparing powder from a high-viscosity flowable amide polymer by spray drying is described: Step 1, Material Pretreatment: A high-viscosity, fluid amide polymer aqueous solution was selected (GPC analysis showed a weight-average relative molecular weight of 68.68 × 10⁻⁶). 4 g / mol, number-average relative molecular weight 20.40 × 10⁻⁶ g / mol 4 (g / mol, polydispersity 3.37) is mixed with water and stirred with a double-layer impeller. The lower impeller rotates at 100 rpm to stir the highly viscous sediment at the bottom of the liquid, while the upper impeller rotates at 500 rpm to stir the upper layer of the liquid. The resulting liquid has a solid content of 8.33%. Hot water is introduced into the jacket of the liquid tank, and the temperature gradient of the liquid is monitored in real time by a temperature sensor installed on the tank wall to ensure that the temperature gradient of the liquid is ≤2℃. The liquid is preheated to 70℃ and continuously kept warm and stirred to eliminate the internal temperature gradient of the liquid and avoid local overheating that could lead to pre-degradation of molecular chains.

[0034] Step 2, Spray drying: Centrifugal atomization is used to pump the preheated liquid material to the atomizer of the spray dryer at a speed of 30,000 rpm. The inlet air temperature of the drying chamber is 150℃, the outlet air temperature is 90℃, the internal negative pressure of the drying chamber is -0.04MPa, the hot air velocity is 12m / s, and the hot air and the liquid droplets move in parallel. The rotating cleaning mechanism inside the drying tower is activated, and cold air is introduced into the gaps in the inner wall of the drying tower to prevent the material from sticking to the wall.

[0035] Step 3, Product Collection: After separation by a cyclone separator, polyacrylamide powder is collected; the exhaust gas after separation is treated by dust removal before being discharged.

[0036] The results of the polyacrylamide powder test are as follows: moisture content 1.5%, particle size D50=18.81μm, and molecular weight retention rate 97.8%.

[0037] No dispersants, stabilizers, or foaming agents are added throughout the process.

[0038] Comparative experiment: Take the same high-viscosity, fluidized amide polymer aqueous solution as in Example 3 (GPC measured, weight-average relative molecular weight 68.68 × 10⁻⁶). 4 g / mol, number-average relative molecular weight 20.40 × 10⁻⁶ g / mol 4 The polyacrylamide powder obtained by drying with existing technology (adding 5% sodium chloride dispersant, drum drying method, drying temperature 120℃, drying time 2 hours) has the following parameters: water content less than 5%, molecular weight retention 90.5%, dissolution time 8.5 minutes, purity 94.8%, and sodium chloride residue 4.2%.

[0039] The comparative results show that the method of preparing polyacrylamide powder by spray drying of the high viscosity flowable amide polymer of the present invention is significantly superior to the prior art in terms of water content, dispersibility, molecular weight retention, dissolution rate and purity of polyacrylamide powder, and no dispersant needs to be added.

[0040] This invention discloses a method for preparing powder from high-viscosity flowing amide polymers via spray drying. This method eliminates the need for dispersants and fundamentally solves the problems of agglomeration and fiber formation during the drying of high-viscosity flowing amide polymers from aqueous solutions by optimizing the feed-liquid ratio, preheating temperature, and spray drying parameters. It avoids the increased costs and performance impacts associated with dispersants, resulting in a product purity greater than 99.9%. The process is simple and efficient, eliminating the need for dispersant addition, mixing, and separation, thus shortening the process flow. The drying time is only 20-30 seconds. Compared to drying processes such as baking and microwave drying, pulverization is unnecessary. The product exhibits excellent performance, with a low drying temperature, a molecular chain degradation rate of ≤3%, and a molecular weight retention rate of ≥97%. The product has a moisture content of ≤5%, uniform particle size distribution (D50=18±0.81μm), and a bulk density of 300kg / m³. 3 It dissolves in water in less than 10 seconds, significantly better than existing products with added dispersants; it has strong applicability, and the process parameters can be fine-tuned according to the characteristics of high-viscosity fluidized amide polymer aqueous solutions without changing equipment, making it easy to scale up industrial production, and it produces no waste, meeting the requirements of green production; it features an innovative structure, with a double-layer stirring paddle combined with a hot water design, precisely controlling the temperature gradient of the liquid to ≤2℃, effectively avoiding molecular chain pre-degradation caused by local overheating, and further improving the molecular weight retention rate; the dual anti-sticking design of the rotating cleaning mechanism inside the drying tower and the cold air introduced through the gap between the inner wall of the drying tower solves the problem of material sticking to the wall and ensures product yield.

[0041] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for preparing powder from a high-viscosity flowable amide polymer by spray drying, characterized in that: Includes the following steps: Step 1, Material Pretreatment: A high-viscosity amide polymer aqueous solution is mixed with water at a mass ratio and stirred using a double-layer agitator. The lower agitator rotates at 100 rpm to stir the high-viscosity sediment at the bottom of the liquid, while the upper agitator rotates at 500 rpm to stir the material on the upper layer of the liquid. The mixture yields a liquid with a solid content of 5% to 15%. Hot water is introduced into the jacket of the liquid tank, and the temperature sensor installed on the tank wall monitors the temperature gradient of the liquid in real time to ensure that the temperature gradient of the liquid is ≤2℃. The liquid is preheated to 60-80℃ and continuously kept warm and stirred to eliminate the internal temperature gradient of the liquid. Step 2, Spray drying: Centrifugal atomization is used to pump the preheated liquid to the atomizer of the spray dryer, with the atomizer speed at 25,000-35,000 rpm. The inlet air temperature of the drying chamber is controlled at 130-155℃, and the outlet air temperature is controlled at 70-105℃. The drying chamber is kept under negative pressure. A rotating cleaning mechanism is installed inside the drying tower, and cold air is introduced through the gaps in the inner wall of the drying tower. Step 3, Product Collection: After separation by a cyclone separator, polyacrylamide powder is collected; the exhaust gas after separation is treated by dust removal before being discharged.

2. The method according to claim 1, characterized in that: In step 1, the solid content of the high-viscosity amide polymer aqueous solution after mixing with water is 8.33%, and the preheating temperature of the liquid is 70℃.

3. The method for preparing powder from the high-viscosity flowable amide polymer according to claim 1 by spray drying, characterized in that: In step 2, the atomizer speed is 30,000 rpm, the inlet air temperature is 150℃, and the outlet air temperature is 90℃.

4. The method for preparing powder from the high-viscosity flowable amide polymer according to claim 1 by spray drying, characterized in that: The prepared polyacrylamide powder has a moisture content of ≤5%, a particle size D50 of 18.81 μm, and a molecular weight retention rate of ≥97%.

5. The method for preparing powder from the high-viscosity flowable amide polymer according to claim 1 by spray drying, characterized in that: In step 2, the hot air and the liquid droplets move in parallel.

6. The method for preparing powder from the high-viscosity flowable amide polymer according to claim 1 by spray drying, characterized in that: The molecular weight parameters of the high-viscosity fluidized amide polymer aqueous solution are as follows: determined by aqueous gel permeation chromatography, calibrated with polyethylene glycol as a standard, the weight-average relative molecular weight is 60.0 × 10⁻⁶. 4 -120.0×10 4 g / mol, number-average relative molecular weight is 15.0 × 10⁻⁶ g / mol. 4 -30×10 4 g / mol, polydispersity is 2.8-3.

8.

7. The method for preparing powder from the high-viscosity flowable amide polymer according to claim 1 by spray drying, characterized in that: The detection conditions included: water as the mobile phase, a differential refractive index detector, and a Mark-Houwink parameter K = 14.1 × 10⁻⁶. -5 dL / g, α=0.7, calibration type is narrow calibration.

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