Method and device for resource utilization of acrylic acid wastewater

Abstract

The invention relates to a method and a device for resource utilization of acrylic acid wastewater, and belongs to the technical field of chemical wastewater treatment and resource recycling. A method for resource utilization of acrylic acid wastewater comprises the following steps: S1, feeding the acrylic acid wastewater into the upper part of an acrylic acid extraction tower, and feeding ethyl acetate as an extraction agent from the lower part of the acrylic acid extraction tower, so that acrylic acid in the wastewater is extracted to enter an ethyl acetate phase; an ethyl acetate phase containing acrylic acid and waste water with acrylic acid removed are obtained; s2, the ethyl acetate phase containing acrylic acid is sent into an acrylic acid recovery tower for separation, and ethyl acetate and acrylic acid are recovered; and S3, adding sodium hydroxide and glucose into the wastewater from which the acrylic acid is removed, and carrying out dealdehyding reaction under an alkaline condition, so that aldehyde substances in the wastewater are converted, and acetic acid is converted into sodium acetate, thereby obtaining a sodium acetate aqueous solution.

Description

Technical Field

[0001] The invention relates to a method and device for resource utilization of acrylic acid wastewater, belonging to the technical field of chemical wastewater treatment and resource recycling. Background Art

[0002] Acrylic acid occupies a very important position in the field of fine chemicals and can be used to manufacture resins and synthetic rubber. In industry, acrylic acid is mainly used to produce acrylates, accounting for about 96% of acrylic acid consumption, and is used in construction, papermaking, leather, textiles, plastic processing, packaging materials, daily chemicals, water treatment, oil production, metallurgy and other fields.

[0003] Currently, the mainstream production process of acrylic acid in the industry is the fixed-bed two-step catalytic oxidation method, that is, propylene and oxygen catalytically react in the first reactor to produce acrolein and water, and acrolein and oxygen catalytically react in the second reactor to produce acrylic acid. After the reaction gas passes through a quenching absorption tower, a 60% acrylic acid aqueous solution is obtained. The acrylic acid aqueous solution is subjected to three-stage distillation of dehydration, deacetic acid removal, and deheavy weight removal to remove impurities such as water, acetic acid, aldehydes, and heavy components in the acrylic acid aqueous solution, and finally an acrylic acid product with a purity of >99.5% is obtained.

[0004] During the acrylic acid production process, particularly during the lightness removal tower operation, wastewater containing acrylic acid, acetic acid, and aldehydes is generated. According to the propylene oxidation reaction equation, water is produced along with various byproducts, primarily acetic acid, formaldehyde, furfural, and benzaldehyde. Acrylic acid wastewater is composed of 89% water, 8% acetic acid, 1% acrylic acid, 1.5% formaldehyde, and trace amounts of acetaldehyde and acrolein.

[0005] Currently, there are two main methods for treating acrylic acid wastewater: biological treatment, which is difficult and requires stringent conditions due to the presence of formaldehyde in acrylic acid wastewater; and incineration, which consumes a significant amount of heat due to the wastewater's primary component being water. Both methods incur high treatment costs and fail to recycle valuable wastewater materials.

[0006] In view of the problems existing in the existing technology, there is an urgent need for a method that can not only effectively treat acrylic acid wastewater but also realize resource utilization, so as to reduce treatment costs, improve economic benefits and reduce environmental pollution. Summary of the Invention

[0007] Based on the above background, the purpose of the present invention is to provide a method for resource utilization of acrylic acid wastewater. The method pretreats acrylic acid wastewater, including removing acrylic acid and aldehydes, to produce a sodium acetate aqueous solution, which is used as a carbon source in a sewage biological treatment process, thereby converting it from wastewater into a nutrient solution, reducing the difficulty of treating acrylic acid wastewater while having certain economic efficiency.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A method for resource utilization of acrylic acid wastewater, comprising the following steps:

[0010] S1 feeds acrylic acid wastewater into the upper part of an acrylic acid extraction tower, and simultaneously feeds ethyl acetate as an extractant into the lower part of the acrylic acid extraction tower, so that acrylic acid in the wastewater is extracted into the ethyl acetate phase, thereby obtaining an ethyl acetate phase containing acrylic acid and wastewater after the acrylic acid is removed;

[0011] S2 sends the ethyl acetate phase containing acrylic acid to an acrylic acid recovery tower for separation to recover ethyl acetate and acrylic acid; S3 adds sodium hydroxide and glucose to the wastewater after the acrylic acid is removed, performs a dealdehyde reaction under alkaline conditions, converts the aldehyde substances in the wastewater, and converts acetic acid into sodium acetate to obtain a sodium acetate aqueous solution.

[0012] The present invention first selectively extracts acrylic acid through an organic extractant to prevent acrylic acid from reacting with alkali to generate sodium acrylate (a substance that inhibits microbial activity) in subsequent treatment. Then, valuable acrylic acid is recovered. Finally, aldehyde substances are removed and acetic acid is converted through glucose dealdehyde reaction and neutralization reaction under alkaline conditions, thereby converting harmful wastewater into an economically valuable sodium acetate aqueous solution.

[0013] Preferably, the extraction temperature in S1 is 20-30 degrees Celsius, and the extraction pressure is not controlled and is actually the static pressure of the tower.

[0014] Preferably, the feed mass ratio of ethyl acetate to acrylic acid wastewater in S1 is 1:1. This preferred solution determines a suitable ratio of extractant to wastewater, ensuring extraction efficiency while avoiding waste caused by excessive use of extractant, thereby achieving economical and efficient extraction and separation of acrylic acid.

[0015] Preferably, in S2, the ethyl acetate phase containing acrylic acid is preheated in a heat exchanger, a polymerization inhibitor is added, and then the phase is fed to an acrylic acid recovery tower. The polymerization inhibitor is phenothiazine, added at a concentration of 80-100 ppm. This preferred embodiment improves separation efficiency and reduces steam consumption through preheating, and the addition of the polymerization inhibitor prevents polymerization of acrylic acid at high temperatures, thereby ensuring the safety and stability of the acrylic acid recovery process.

[0016] Preferably, the acrylic acid recovery tower in S2 operates at a pressure of 80-85 kPaA, a bottom temperature of 80-85°C, a top temperature of 65-75°C, and a reflux ratio of 0.2:1. This preferred solution defines the optimal operating parameters for the acrylic acid recovery tower. Under these conditions, efficient separation of ethyl acetate and acrylic acid can be achieved, while reducing energy consumption and improving recovery purity.

[0017] Preferably, in S3, the amount of glucose added is 0.05%-0.1% of the wastewater mass, and the amount of sodium hydroxide added is such that the pH of the wastewater is maintained at 11-12. This preferred solution achieves cost-effective dealdehyde removal by precisely controlling the amounts of glucose and sodium hydroxide added. Simultaneously, by controlling the appropriate pH, an optimal alkaline environment is created for the dealdehyde removal reaction, promoting a rapid reaction between aldehydes and glucose and ensuring complete neutralization of acetic acid to sodium acetate.

[0018] Preferably, in S3, the temperature of the dealdehyde removal reaction is controlled at 88-92°C, and the reaction time is 0.5-2 hours. This preferred solution determines the optimal temperature and time range for the dealdehyde removal reaction. Under these conditions, the reaction rate of aldehydes such as formaldehyde with glucose is the fastest, achieving a removal rate of 99.9%, while avoiding the increased energy consumption caused by excessively high temperatures.

[0019] Preferably, in S3, the effective volume of the dealdehyde reaction is 1-2 times the maximum water inlet volume. This preferred solution determines the appropriate reactor size, which not only ensures sufficient reaction space and residence time, but also avoids the waste of investment caused by oversized equipment, thereby achieving an efficient and economical dealdehyde reaction process.

[0020] An acrylic acid wastewater resource utilization device based on the above method comprises:

[0021] An acrylic acid extraction tower is used to contact and extract acrylic acid wastewater with ethyl acetate;

[0022] An acrylic acid recovery tower connected to the acrylic acid extraction tower is used to separate and recover acrylic acid and ethyl acetate;

[0023] The formaldehyde removal reactor is connected to the acrylic acid extraction tower and is used to remove formaldehyde and neutralize acetic acid from the wastewater after the acrylic acid is removed.

[0024] This device scheme constructs a basic equipment system for realizing resource utilization of acrylic acid wastewater, including three core units of extraction separation, distillation recovery and chemical conversion, forming a complete process flow.

[0025] Preferably, the apparatus further comprises: a heat exchanger connected between the acrylic acid extraction tower and the acrylic acid recovery tower for preheating the ethyl acetate phase containing acrylic acid; an ethyl acetate condenser connected to the top of the acrylic acid recovery tower for condensing the ethyl acetate extracted from the top of the tower; an ethyl acetate receiving tank connected to the outlet of the ethyl acetate condenser for collecting the condensed ethyl acetate; and an ethyl acetate pump connected to the outlet of the ethyl acetate receiving tank for transporting the ethyl acetate to the acrylic acid recovery tower as reflux or to the acrylic acid extraction tower as an extractant.

[0026] This preferred device scheme improves the configuration of the acrylic acid recovery system, realizes energy recovery and utilization through the heat exchanger, and realizes the closed-loop circulation of ethyl acetate through the combination of condenser-liquid receiving tank-pump, thereby reducing the consumption of extraction agent and improving the economy and environmental protection of the system.

[0027] Preferably, the above-mentioned device also includes: a premixer connected between the acrylic acid extraction tower and the dealdehyde reaction kettle, used to mix the wastewater after the removal of acrylic acid with sodium hydroxide solution and glucose; a heat exchanger connected to the outlet of the dealdehyde reaction kettle, used to cool the sodium acetate aqueous solution after the dealdehydeation; and a sodium acetate storage tank connected to the outlet of the heat exchanger, used to collect the sodium acetate aqueous solution.

[0028] This preferred device scheme improves the configuration of the dealdehyde removal system, achieves uniform mixing of reactants through a premixer, and improves reaction efficiency; realizes energy recovery and utilization through a heat exchanger; and collects the final product through a sodium acetate storage tank, providing convenience for subsequent utilization.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The method and device for resource utilization of acrylic acid wastewater of the present invention use ethyl acetate as the extractant, and have a good selective extraction effect on acrylic acid in the wastewater. Other components in the wastewater are insoluble in ethyl acetate, thereby achieving efficient separation and recovery of acrylic acid.

[0031] 2. The present invention uses glucose as a dealdehyde agent with a small addition amount (0.05%-0.1% of the wastewater mass). Under alkaline conditions and a temperature of 88-92°C, formaldehyde reacts rapidly. After 0.5h of reaction, the formaldehyde removal rate can reach 99.9%, greatly reducing the difficulty of subsequent treatment.

[0032] 3. The present invention uses sodium hydroxide and acetic acid for neutralization, which not only obtains the target substance sodium acetate, but also creates alkaline conditions for the dealdehyde reaction, thereby achieving a synergistic effect of the process.

[0033] 4. The present invention converts acrylic acid wastewater into economically valuable sodium acetate aqueous solution and recovered acrylic acid through a systematic process combining extraction separation, distillation recovery and chemical conversion, thereby realizing resource utilization of wastewater and avoiding the high energy consumption of traditional incineration methods and the high difficulty of biological treatment methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of the acrylic acid wastewater resource utilization device of the present invention;

[0035] Wherein: 1. acrylic acid extraction tower, 2. heat exchanger, 3. acrylic acid recovery tower, 4. ethyl acetate condenser, 5. ethyl acetate receiving tank, 6. ethyl acetate pump, 7. acrylic acid recovery tower reboiler, 8. reboiler circulation pump, 9. dealdehyde reactor, 10. premixer, 11. dealdehyde reactor discharge pump, 12. acrylic acid cooler, 13. acrylic acid discharge pump. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described in detail below through specific examples. It should be understood that the implementation of the present invention is not limited to the following examples, and any form of modification and / or change made to the present invention will fall within the scope of protection of the present invention.

[0037] In the present invention, unless otherwise specified, all parts and percentages are by weight, and the equipment and raw materials used are commercially available or commonly used in the art. The methods in the following examples are all conventional methods in the art unless otherwise specified.

[0038] The following detailed description of the embodiments of the present invention is made in conjunction with the accompanying drawings. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, one or more embodiments may be implemented by those skilled in the art without these specific details.

[0039] The embodiments of the present invention disclose a method and apparatus for resource utilization of acrylic acid wastewater, which includes extraction, separation, and recovery of acrylic acid, as well as dealdehydeation and acetic acid neutralization treatment of the wastewater, ultimately achieving the goal of resource utilization by recovering acrylic acid and converting the wastewater into a sodium acetate aqueous solution.

[0040] Example 1

[0041] like Figure 1 As shown, the acrylic acid wastewater resource utilization device provided in this embodiment includes: an acrylic acid extraction tower 1, a heat exchanger 2, an acrylic acid recovery tower 3, an ethyl acetate condenser 4, an ethyl acetate receiving tank 5, an ethyl acetate pump 6, an acrylic acid recovery tower reboiler 7, a reboiler circulation pump 8, a dealdehyde reactor 9, a premixer 10, a dealdehyde reactor discharge pump 11, an acrylic acid cooler 12 and an acrylic acid discharge pump 13.

[0042] The acrylic acid extraction tower 1 is used for contact extraction of acrylic acid wastewater with ethyl acetate.

[0043] The acrylic acid recovery tower 3 is connected to the acrylic acid extraction tower and is used to separate and recover acrylic acid and ethyl acetate. A heat exchanger 2 is located between the acrylic acid extraction tower and the acrylic acid recovery tower to preheat the ethyl acetate phase containing acrylic acid. The top outlet of the acrylic acid recovery tower 3 is connected to an ethyl acetate condenser 4 for condensing the ethyl acetate withdrawn from the tower. The outlet of the ethyl acetate condenser is connected in sequence to an ethyl acetate receiving tank 5 for collecting the condensed ethyl acetate and an ethyl acetate pump 6, which transports the ethyl acetate to the acrylic acid recovery tower as reflux or to the acrylic acid extraction tower as an extractant. A reflux line is provided at the bottom of the acrylic acid recovery tower 3, which is then connected to a reboiler circulation pump 8 and an acrylic acid recovery tower reboiler 7. The acrylic acid recovery tower 3 receives the heat required for vaporization via the acrylic acid recovery tower reboiler 7. The reboiler 7 typically uses steam as its heat source, and the reboiler circulation pump 8 circulates the liquid in the bottom of the tower, ensuring efficient heat transfer. The bottom outlet line of the acrylic acid recovery tower 3 is also connected in sequence to an acrylic acid discharge pump 13 and an acrylic acid cooler 12. The bottom product obtained from the bottom of the acrylic acid recovery tower 3 is transported by the acrylic acid discharge pump 13, cooled by the acrylic acid cooler 12, and then sent to the unqualified acrylic acid storage tank for temporary storage.

[0044] The bottom of the acrylic acid extraction column 1 is connected in sequence to a premixer 10, a dealdehyde reactor 9, and a dealdehyde reactor discharge pump 11. The dealdehyde reactor 9 is used to remove the formaldehyde and neutralize the wastewater after the acrylic acid is removed with acetic acid. The premixer 10 is used to mix the wastewater after the acrylic acid is removed with sodium hydroxide solution and glucose. The outlet of the dealdehyde reactor discharge pump 11 is connected to the heat exchanger 2, and the terminal of the pipeline is connected to a sodium acetate storage tank for collecting the sodium acetate aqueous solution.

[0045] In this example, the acrylic acid wastewater is composed of 89% water, 8% acetic acid, 1% acrylic acid, 1.5% formaldehyde, and trace amounts of acetaldehyde and acrolein. Because this wastewater contains acrylic acid and aldehydes, it is difficult to directly treat biologically. Incineration, however, results in high energy consumption and treatment costs.

[0046] The specific steps of the method for resource utilization of acrylic acid wastewater in this embodiment are as follows:

[0047] Step S1: Acrylic acid extraction and separation

[0048] Acrylic acid wastewater is fed at a constant flow rate to the upper feed port of acrylic acid extraction column 1. Simultaneously, ethyl acetate is fed as an extractant from the lower feed port of acrylic acid extraction column 1. Acrylic acid extraction column 1 is a packed column filled with structured packing to provide sufficient gas-liquid contact area.

[0049] In acrylic acid extraction column 1, ethyl acetate flows from bottom to top, while acrylic acid wastewater flows from top to bottom, forming countercurrent contact. Because ethyl acetate has excellent selective solubility for acrylic acid, while it has low solubility for water, acetic acid, and aldehydes in the wastewater, acrylic acid in the wastewater is extracted into the ethyl acetate phase, while other components remain in the aqueous phase.

[0050] The extraction process is performed at a temperature of 20-30°C, where ethyl acetate achieves optimal extraction efficiency for acrylic acid. The extraction column pressure is not specifically controlled; it is effectively the column's static pressure. The feed ratio of ethyl acetate to acrylic acid wastewater is maintained at 1:1, ensuring sufficient extraction of acrylic acid while avoiding waste caused by excessive use of the extraction agent.

[0051] In the acrylic acid extraction tower 1, as the extraction process proceeds, the ethyl acetate phase containing acrylic acid flows out from the top of the tower and enters the next step for acrylic acid recovery; the wastewater after removing acrylic acid flows out from the bottom of the tower and enters the subsequent dealdehyde treatment step.

[0052] Step S2: Acrylic acid recovery

[0053] After exiting the top of acrylic acid extraction column 1, the ethyl acetate phase containing acrylic acid is first preheated in heat exchanger 2. Heat exchanger 2 utilizes a spiral plate structure, and its heat source is the sodium acetate solution generated by the system. The preheating temperature is controlled at 60-70°C. This preheating improves the efficiency of subsequent distillation separation and reduces energy consumption in the reboiler.

[0054] Before the preheated acrylic acid-containing ethyl acetate phase enters acrylic acid recovery column 3, phenothiazine is added as a polymerization inhibitor at a concentration of 80-100 ppm. Since acrylic acid readily polymerizes at high temperatures, the addition of phenothiazine effectively inhibits polymerization, ensuring safe and stable operation of the distillation process. Phenothiazine not only exhibits excellent polymerization inhibition at high temperatures but is also soluble in acrylic acid and ethyl acetate, making it an ideal polymerization inhibitor.

[0055] After adding the polymerization inhibitor, the material enters acrylic acid recovery tower 3. Acrylic acid recovery tower 3 is a plate-type distillation tower equipped with 15-20 sieve plates, which is used to separate ethyl acetate from acrylic acid. The operating parameters of acrylic acid recovery tower 3 are strictly controlled as follows: operating pressure of 80-85 kPaA, bottom temperature of 80-85°C, top temperature of 65-75°C, and reflux ratio of 0.2:1. These parameters have been optimized to achieve effective separation of ethyl acetate and acrylic acid while maintaining low energy consumption. Under vacuum conditions, the operating temperature can avoid the polymerization temperature range of acrylic acid.

[0056] The bottom of acrylic acid recovery tower 3 provides heat required for vaporization through acrylic acid recovery tower reboiler 7. Reboiler 7 usually uses steam as heat source, and reboiler circulation pump 8 realizes circulation of tower bottom liquid to ensure efficient heat transfer.

[0057] In acrylic acid recovery tower 3, ethyl acetate, due to its low boiling point, flows out of the tower's overhead vapor phase and is condensed into a liquid by ethyl acetate condenser 4, with the condensation temperature controlled at 20-25°C. The condensed ethyl acetate flows into ethyl acetate receiving tank 5 for collection. Ethyl acetate from ethyl acetate receiving tank 5 is pumped by ethyl acetate pump 6, with a portion returning to acrylic acid recovery tower 3 as reflux and the remaining portion circulating back to acrylic acid extraction tower 1 for reuse as an extractant, thus achieving recycling of the extractant.

[0058] The bottom product of acrylic acid recovery tower 3 is recovered acrylic acid, typically containing greater than 98.5% acrylic acid and less than 0.2% ethyl acetate. This bottom product is pumped by acrylic acid discharge pump 13, cooled to 30-35°C in acrylic acid cooler 12, and then temporarily stored in a substandard acrylic acid storage tank (not shown). This recovered acrylic acid can be re-injected into the butyl acrylate production process as raw material, achieving resource recycling.

[0059] Step S3: Dealdehyde Reaction and Acetic Acid Neutralization

[0060] The wastewater from the acrylic acid extraction column 1, after acrylic acid has been removed, flows into pre-mixer 10. In pre-mixer 10, the wastewater is thoroughly mixed with sodium hydroxide solution and glucose. The concentration of sodium hydroxide solution is typically 20-30%, and the amount added is calculated based on the acetic acid content in the wastewater to control the pH of the wastewater to 11-12. The amount of glucose added is 0.05-0.1% of the wastewater mass. Pre-mixer 10 uses a mechanical agitator to ensure uniform mixing of the components.

[0061] The mixed materials enter the dealdehyde removal reactor 9. This is a stirred reactor equipped with a temperature control system and a mechanical stirrer. The reactor is heated by a steam coil to maintain a temperature of 88-92°C. The effective volume of the dealdehyde removal reactor 9 is 1-2 times the maximum inlet water volume. This design ensures a sufficient reaction residence time, typically 0.5-2 hours.

[0062] In the dealdehyde removal reactor 9, under alkaline conditions, glucose reacts with aldehydes such as formaldehyde in the wastewater to form hydroxymethyl glucose. Simultaneously, acetic acid reacts with sodium hydroxide to produce sodium acetate and water. These two reactions proceed simultaneously, achieving the removal of aldehydes and the conversion of acetic acid.

[0063] After the reaction is complete, the product is pumped through the dealdehyde reactor discharge pump 11, cooled to 40-45°C through the heat exchanger 2, and finally collected in a sodium acetate storage tank (not shown). The resulting sodium acetate aqueous solution has a concentration of approximately 10-15% and can be used as a carbon source in the biological treatment process to provide nutrition for microorganisms.

[0064] Example 2

[0065] The difference between this embodiment and embodiment 1 lies in the optimization of extraction conditions and dealdehydeation reaction conditions.

[0066] During the extraction step, the extraction temperature was maintained at a constant 25°C, where ethyl acetate has the highest extraction coefficient for acrylic acid. Furthermore, the feed ratio of ethyl acetate to acrylic acid wastewater was controlled at 1.2:1, and the amount of extractant was slightly increased to improve the extraction efficiency of acrylic acid.

[0067] In the dealdehyde removal step, the glucose addition was increased to 0.1% of the wastewater mass, the reaction temperature was maintained at 90°C, and the reaction time was extended to 1.5 hours. These adjustments further improved the aldehyde removal efficiency, reaching a formaldehyde removal rate of over 99.99%.

[0068] Through the above optimization, the resource utilization efficiency of acrylic acid wastewater in this embodiment is further improved, the acrylic acid recovery rate can reach more than 98%, the purity of the final product sodium acetate aqueous solution is higher, and the COD reduction rate can reach 18%.

[0069] Example 3

[0070] This embodiment provides a design of an industrialized device with a treatment capacity of 500 kg / h of acrylic acid wastewater.

[0071] Acrylic acid extraction tower 1 features an inner diameter of 800mm and a height of 8 meters. It is packed with 500Y metal structured packing, with a packing layer height of 5 meters. A liquid distributor is installed at the top of the tower to ensure even distribution of wastewater, and a liquid distributor is installed at the bottom to ensure even distribution of ethyl acetate.

[0072] Acrylic acid recovery tower 3 is a 600mm inner diameter, 12m high plate tower equipped with 15 sieve plates spaced 500mm apart. A condenser is located at the top of the tower, using cooling water as the cooling medium; a reboiler is located at the bottom of the tower, using 0.2MPa steam as the heat source.

[0073] The dealdehyde reactor 9 has an effective volume of 2m 3 The stirred reactor is equipped with a variable-frequency speed-controlled agitator with a stirring power of 3kW. A steam coil with a steam pressure of 0.2MPa is installed inside the reactor to heat the reaction materials to the required temperature. The reactor's outer wall is insulated to reduce heat loss.

[0074] The premixer 10 has a volume of 0.5m 3 The stirring tank is equipped with a high-speed stirrer with a stirring power of 1.5kW to ensure that the sodium hydroxide solution and glucose are quickly and evenly mixed with the wastewater.

[0075] Heat exchanger 2 uses a spiral plate heat exchanger with a heat exchange area of 5m 2 ; Acrylic acid cooler 12 adopts shell and tube heat exchanger with a heat exchange area of 15m 2 , the cooling medium is cooling water.

[0076] The polymerization inhibitor phenothiazine is prepared using ethyl acetate as a solvent with a concentration of 2%. The addition amount is controlled by a precise metering pump to ensure that the system concentration is within the range of 80-100 ppm.

[0077] In this example, the various devices in the industrial plant are connected by pipes and pumps, forming a continuous process flow. The entire system is equipped with an automatic control system, including temperature, pressure, liquid level, and flow rate detection and control, to ensure the stability of process parameters and the safe operation of the equipment.

[0078] This industrial device can process 500 kg of acrylic acid wastewater per hour, recover about 5 kg of acrylic acid, and produce about 40 kg of sodium acetate (in solid form), greatly reducing wastewater treatment costs and creating considerable economic value.

[0079] Example 4

[0080] This example explores the effects of the type and amount of polymerization inhibitor added on the recovery of acrylic acid.

[0081] In this example, three common polymerization inhibitors were tried: phenothiazine, hydroquinone, and 4-methoxyphenol, with the addition amounts set to 50 ppm, 80 ppm, and 100 ppm, respectively, to investigate the effects of different types and addition amounts of polymerization inhibitors on the purity of the recovered acrylic acid product (the effect of different polymerization inhibitors on the content of acrylic acid dimers in the acrylic acid product).

[0082] Experimental results show that phenothiazine performs best at an addition level of 80-100 ppm, achieving an acrylic acid recovery rate of 97%, a recovered product purity exceeding 98%, and excellent storage stability. Hydroquinone is second most effective, with 4-methoxyphenol being the least effective. When the polymerization inhibitor is added at levels below 80 ppm, slight polymerization is observed as the acrylic acid recovery process proceeds. While the addition level exceeds 100 ppm, while the polymerization inhibition effect is enhanced, it negatively impacts the purity of the recovered acrylic acid and increases costs. Therefore, choosing phenothiazine as a polymerization inhibitor and controlling the addition level within the 80-100 ppm range is optimal.

[0083] Example 5

[0084] This example explores the effects of glucose addition and dealdehydeation reaction conditions on the aldehyde removal effect.

[0085] In this example, the amount of glucose added was set to 0.03%, 0.05%, 0.08% and 0.1% of the wastewater mass, the reaction temperatures were 85°C, 90°C and 95°C, and the reaction times were 0.5h, 1h and 2h, respectively, to study the effects of different combinations of conditions on the aldehyde removal effect.

[0086] Experimental results show that when the glucose addition level is 0.05%, the formaldehyde removal rate reaches 99.5% after 0.5 h at a reaction temperature of 90°C. When the glucose addition level is increased to 0.08%, the formaldehyde removal rate reaches 99.9% under the same conditions. When the glucose addition level is 0.1%, the formaldehyde removal rate exceeds 99.95%. When the reaction temperature is below 88°C, the reaction rate slows significantly, requiring longer reaction times to achieve the same removal rate. When the temperature exceeds 92°C, although the reaction rate further increases, energy consumption increases and the carbonization of glucose may occur, affecting product quality. Regarding reaction time, the aldehyde removal rate gradually increases with increasing reaction time, but the improvement in removal rate decreases after 0.5 h.

[0087] Taking into account aldehyde removal efficiency, reaction time, and energy consumption, the optimal conditions recommended in this example are: 0.08% glucose addition, 90°C reaction temperature, and 1 hour reaction time. Under these conditions, formaldehyde removal rates reached over 99.9%, and removal rates for other aldehydes such as acetaldehyde and acrolein were also over 95%. The resulting sodium acetate solution met the carbon source requirements for subsequent biological treatment.

[0088] Example 6

[0089] This example studies the optimization of acrylic acid extraction process in detail.

[0090] In this example, the effects of different extraction equipment types on extraction efficiency were investigated. Using a packed tower, a sieve plate tower, and a pulse extraction tower, the extraction efficiency of acrylic acid and the co-extraction of other components were tested under identical operating conditions (temperature 25°C, ethyl acetate to wastewater ratio of 1:1).

[0091] Experimental results show that packed towers, due to their large contact area, low pressure drop, and flexible operation, perform best in this process, achieving acrylic acid extraction rates exceeding 98% and minimizing co-extraction of acetic acid, water, and aldehydes. While pulse extraction towers offer high extraction efficiency, they are complex and energy-intensive. Sieve plate towers, however, suffer from severe mist entrainment and unsatisfactory phase separation. Therefore, the use of packed towers as extraction equipment in this invention is a reasonable choice. Regarding the selection of extractants, in addition to ethyl acetate, common extractants such as butyl acetate and cyclohexanone were also investigated. Studies have shown that ethyl acetate has the strongest selective solubility for acrylic acid, has low miscibility with water and acetic acid, offers excellent phase separation, and is easily recoverable, making it the most suitable extractant.

[0092] By further optimizing the operating parameters of the extraction tower, including fine-tuning the temperature within the range of 20-30°C, rationally designing the packing layer height and packing type, and optimizing the liquid distributor structure, the acrylic acid extraction rate can be stabilized at above 99%, providing reliable guarantees for subsequent processes.

[0093] In summary, the method and device for resource utilization of acrylic acid wastewater provided by the present invention solve the problems of difficulty and high cost in wastewater treatment during the acrylic acid production process, realize the recovery of valuable substances and transformation of harmful substances in the wastewater, and turn wastewater into treasure, with significant economic and environmental benefits.

[0094] Taking the current mainstream acrylic acid production capacity of 160,000 tons / year as an example, the wastewater generated is 32,000 tons / year. The technology of the present invention can recover about 320 tons of acrylic acid, which is worth about 2.2 million yuan; produce about 30,000 tons of 10-15% sodium acetate aqueous solution, which is worth about 24 million yuan; the energy consumed by the wastewater resource recovery device, and the cost of adding liquid caustic soda and glucose is 328 yuan / ton, as follows:

[0095] Glucose formaldehyde removal operating cost (fresh alkali)

[0096]

[0097] The processing fee is 10.5 million yuan / year, the overall economic benefit can reach 13.5 million yuan / year, the total investment is 1.5 million yuan, and the investment recovery period is about 2 months.

[0098] In terms of environmental benefits, the technology of the present invention can reduce the COD of wastewater by more than 15%, reducing environmental pollution and greatly reducing the difficulty and cost of subsequent biological treatment. It helps enterprises meet emission standards and high-standard emissions, improves corporate competitiveness, promotes the reduction of corporate taxes, and reduces the risk of environmental penalties.

[0099] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The description of the above examples is only used to help understand the method of the present invention and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in several ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. For example, the extraction conditions, recovery tower operating parameters and dealdehyde reaction conditions can be adjusted according to actual needs; other suitable inhibitors can be selected; the equipment structure can be improved to improve efficiency; this technology can be combined with other wastewater treatment technologies to achieve better treatment effects.

Claims

1. A method for resource utilization of acrylic acid wastewater, characterized in that: The method comprises the following steps: S1 feeds acrylic acid wastewater into the upper part of an acrylic acid extraction tower, and simultaneously feeds ethyl acetate as an extractant into the lower part of the acrylic acid extraction tower, so that acrylic acid in the wastewater is extracted into the ethyl acetate phase, thereby obtaining an ethyl acetate phase containing acrylic acid and wastewater after the acrylic acid is removed; S2 sends the ethyl acetate phase containing acrylic acid to an acrylic acid recovery tower for separation to recover ethyl acetate and acrylic acid; S3 adds sodium hydroxide and glucose to the wastewater after the acrylic acid is removed, performs a dealdehyde reaction under alkaline conditions, converts the aldehyde substances in the wastewater, and converts acetic acid into sodium acetate to obtain a sodium acetate aqueous solution.

2. The method for resource utilization of acrylic acid wastewater according to claim 1, characterized in that: The feed mass ratio of ethyl acetate to acrylic acid wastewater in S1 is 1:

1.

3. The method for resource utilization of acrylic acid wastewater according to claim 1, characterized in that: In S2, the ethyl acetate phase containing acrylic acid is preheated in a heat exchanger and then an inhibitor is added, and then sent to an acrylic acid recovery tower; the inhibitor is phenothiazine, which is added at a concentration of 80-100 ppm.

4. The method for resource utilization of acrylic acid wastewater according to claim 3, characterized in that: The operating pressure of the acrylic acid recovery tower in S2 is 80-85 kPaA, the bottom temperature is 80-85°C, the top temperature is 65-75°C, and the reflux ratio is 0.2:

1.

5. The method for resource utilization of acrylic acid wastewater according to claim 1, characterized in that: In S3, the amount of glucose added is 0.05%-0.1% of the mass of the wastewater, and the amount of sodium hydroxide added is such that the pH value of the wastewater is maintained at 11-12.

6. The method for resource utilization of acrylic acid wastewater according to claim 5, characterized in that: In S3, the temperature of the dealdehyde reaction is controlled at 88-92° C., and the reaction time is 0.5-2 hours.

7. The method for resource utilization of acrylic acid wastewater according to claim 6, characterized in that: In S3, the effective volume of the dealdehyde reaction kettle used in the dealdehyde reaction is 1-2 times the maximum water inlet volume.

8. An acrylic acid wastewater resource utilization device based on the method according to any one of claims 1 to 7, characterized in that: include: An acrylic acid extraction tower is used to contact and extract acrylic acid wastewater with ethyl acetate; An acrylic acid recovery tower connected to the acrylic acid extraction tower is used to separate and recover acrylic acid and ethyl acetate; The formaldehyde removal reactor is connected to the acrylic acid extraction tower and is used to remove formaldehyde and neutralize acetic acid from the wastewater after the acrylic acid is removed.

9. The device according to claim 8, characterized in that Also includes: a heat exchanger connected between the acrylic acid extraction tower and the acrylic acid recovery tower for preheating the ethyl acetate phase containing acrylic acid; The ethyl acetate condenser is connected to the top of the acrylic acid recovery tower and is used to condense the ethyl acetate produced from the top of the tower; The ethyl acetate receiving tank is connected to the outlet of the ethyl acetate condenser and is used to collect the condensed ethyl acetate; The ethyl acetate pump is connected to the outlet of the ethyl acetate receiving tank and is used to transport the ethyl acetate to the acrylic acid recovery tower as reflux or to the acrylic acid extraction tower as an extractant.

10. The device according to claim 8, characterized in that Also includes: A premixer is connected between the acrylic acid extraction tower and the dealdehyde reaction kettle, and is used to mix the wastewater after the removal of acrylic acid with sodium hydroxide solution and glucose; A heat exchanger is connected to the outlet of the dealdehyde removal reactor to cool the sodium acetate aqueous solution after dealdehyde removal; The sodium acetate storage tank is connected to the outlet of the heat exchanger and is used to collect the sodium acetate aqueous solution.

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