A method for treating acetic acid distillation residue

Abstract

The application provides an acetyl distillation residual liquid treatment method, which comprises the following steps: uniformly laying sawdust on a reaction container; mixing and stirring the sawdust and slaked lime to form a mixture, and then laying the mixture on the sawdust layer in the reaction container; covering a plate frame sludge layer on the uppermost layer of the reaction container; finally, moving the reaction container with added accessories to a closed reaction room, covering a gas collection hood, connecting a pipeline to the gas collection hood and connecting the pipeline to an air induction system of an incinerator, inserting a waste liquid pipeline into the reaction container, and pumping acetyl distillation residual liquid into the reaction container for reaction with the accessories. The slaked lime is added before incineration, which helps to react with acidic elements (sulfur, chlorine, phosphorus and the like) to generate stable divalent salts, and the acidic elements can be removed in the form of incineration slag in the incinerator hearth during later incineration, so that the acidic elements are prevented from forming low-boiling potassium salts or sodium salts to cause fouling and blockage in the back end of the incineration system boiler; and the stability and continuity of the system production are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of acetyl distillation residue treatment technology, and relates to a method for treating acetyl distillation residue. Background Technology

[0002] Acetyl distillation residue is wastewater generated in the pesticide industry during the production of pesticide intermediates. Specifically, 91% spermine reacts with dimethyl sulfate through a transposition reaction to produce methamidophos. Acetic anhydride and concentrated sulfuric acid are then added to the acetyl production unit for an acylation reaction to produce acetamiprid. The acetyl wastewater generated in the pollution-generating stage of the reaction is acetyl distillation residue, which has characteristics such as high calorific value, strong odor, and high toxicity.

[0003] Acetyl is characterized by a calorific value of approximately 5000-6000 kcal / kg, total phosphorus of approximately 0.5-5%, total sulfur of approximately 3-7%, and total chlorine of approximately 0.5-2%. Studies have found that the high content of acidic elements such as sulfur, chlorine, and phosphorus in acetyl distillation residue leads to frequent scaling and blockage of the boiler and downstream process equipment in the incineration system during the treatment process. This affects the negative pressure and production stability of the incineration system, and may even cause shutdowns. Furthermore, the acidic elements consume large amounts of liquid alkali in the downstream flue gas treatment section, resulting in high treatment costs. Additionally, the excessively high calorific value of acetyl distillation residue means that, given a fixed system design heat load, its disposal will have a significant negative impact on system capacity. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for treating acetyl distillation residue, which can significantly reduce its calorific value and solidify it, thereby improving treatment efficiency, preventing blockage at the system's downstream end, and enhancing the stability and continuity of subsequent incineration system production.

[0005] The technical objective of this invention is achieved through the following technical solution: a method for treating acetyl distillation residue, comprising:

[0006] A layer of sawdust is evenly spread in the reaction vessel, which has an opening only at the top;

[0007] Separately, mix sawdust and slaked lime in a mass ratio of 1:1 to 1:1.5 until homogeneous to form a mixture;

[0008] Spread the mixture of sawdust and slaked lime evenly on the sawdust layer in the reaction vessel;

[0009] Cover the top of the reaction vessel with a plate and frame sludge layer, spread it evenly over the sawdust, and ensure that no sawdust is exposed.

[0010] Finally, move the reaction vessel with the added auxiliary materials to the closed reaction chamber, cover it with the gas collection hood, leaving a small gap, connect the pipe to the gas collection hood and connect it to the induced draft system of the incinerator.

[0011] Insert the waste liquid pipe into the reaction vessel and pump the acetyl distillation residue into the reaction vessel, so that the acetyl distillation residue seeps into the lower layer of the reaction vessel and reacts with the excipients;

[0012] After the acetyl distillation residue is removed, the gas collection hood is tightly closed, and the mixture is allowed to stand under negative pressure to allow for a full reaction.

[0013] Preferably, the thickness of the sludge layer laid in the plate and frame is 20-40cm.

[0014] Preferably, the thickness of the sawdust layer is 10-15cm.

[0015] Preferably, the reaction time is controlled to be 10-14 hours.

[0016] Preferably, after the acetyl distillation residue has reacted completely, the gas collecting hood is opened, and a low-calorific-value aqueous waste liquid with a calorific value of <1000kcal / kg, density ≤1.1kg / L, and pH 4-10 is injected into the reaction vessel to cool the reaction solids for a period of not less than 2 hours.

[0017] Preferably, the injection volume of the low-calorific-value aqueous waste liquid is 1.5-2 times the mass of slaked lime.

[0018] Preferably, after the core temperature of the solid material in the reaction vessel is lower than 40°C, the residue in the reaction vessel is poured into the incineration pit, mixed evenly with other waste materials, and then incinerated.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This invention provides a method for treating acetyl distillation residue. Before incineration, quicklime is added to the residue for treatment, which helps the acidic elements (sulfur, chlorine, phosphorus, etc.) react with Ca2+ to form stable divalent salts. During subsequent incineration, these salts can be removed from the incinerator as incinerator slag, preventing them from forming low-boiling-point potassium or sodium salts that can enter the boiler back end of the incineration system and cause scaling and blockage. This greatly improves the stability and continuity of system production.

[0021] 2. The raw material used in the pretreatment of this invention is slaked lime, which is low in cost. Through the pretreatment, the consumption of liquid alkali at the end of the incineration can be reduced, significantly saving costs and improving economic efficiency. The calorific value of the acetyl distillation residue is greatly reduced during the pretreatment process, from about 6000 kcal to about 3000 kcal. Under the condition that the system design heat load remains unchanged, the system capacity is greatly increased, and more acetyl distillation residue can be consumed.

[0022] 3. Acetyl distillation residue has a strong odor, especially when reacting with quicklime. This invention reduces the intensity of the reaction between acetyl distillation residue and quicklime by mixing sawdust and quicklime before contacting them. However, the heat preservation effect of sawdust prolongs the reaction time between acetyl distillation residue and quicklime. At the same time, the steam and gas generated by the reaction are directly drawn into the incinerator by the incineration exhaust system for treatment. The odor is controllable throughout the reaction process, with no smoke or odor escaping, thus preventing environmental pollution.

[0023] 4. Existing hazardous waste incineration systems have a solid-liquid ratio of approximately 7:3, while most hazardous waste requiring incineration in the market is predominantly liquid with less solid, posing a challenge to hazardous waste incineration. The method provided by this invention converts acetyl distillation residue into solid through pretreatment technology, effectively reducing the amount of liquid material and improving hazardous waste treatment capacity. Simultaneously, because the pretreatment reaction of acetyl distillation residue is exothermic, a significant amount of low-calorific-value aqueous waste liquid is consumed for cooling, achieving the co-treatment of low-calorific-value aqueous waste liquid.

[0024] 5. During the static reaction of the acetyl distillation residue, heat and steam are generated. At the same time, due to the heat preservation effect of sawdust, the reaction between the acetyl distillation residue and quicklime is promoted to be more thorough. When the reaction is most vigorous, the temperature of the inner core of the container can exceed 100°C. However, the sawdust only carbonizes under the air-isolated conditions of sludge and does not pose a fire risk. In addition, the steam and gas generated by the reaction are immediately drawn into the incinerator for treatment through the exhaust system. There is no smoke or odor escaping during the reaction process. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the examples are for illustrative purposes only and should not be construed as limiting the present patent.

[0026] Example 1

[0027] This embodiment provides a method for treating acetyl distillation residue, including the following steps:

[0028] First, a 10cm thick layer of sawdust is evenly spread in the reaction vessel, which has an opening only at the top.

[0029] Separately, mix 100g of sawdust and 150g of slaked lime until homogeneous to form a mixture;

[0030] Spread the mixture of sawdust and slaked lime evenly on the sawdust layer in the reaction vessel;

[0031] Cover the top of the reaction vessel with a layer of plate and frame sludge, spread it evenly and cover it with sawdust. The thickness of the plate and frame sludge should be 20cm to ensure that no sawdust is exposed.

[0032] Finally, move the reaction vessel with the added auxiliary materials to the closed reaction chamber, cover it with the gas collection hood, leaving a small gap, connect the pipe to the gas collection hood and connect it to the induced draft system of the incinerator.

[0033] Insert the waste liquid pipe into the reaction vessel and pump the acetyl distillation residue into the reaction vessel, so that the acetyl distillation residue seeps into the lower layer of the reaction vessel and reacts with the excipients;

[0034] After the acetyl distillation residue is removed, the gas collection hood is tightly closed, and the mixture is allowed to stand under negative pressure for a full reaction. The reaction time is controlled to be 10 hours.

[0035] After the acetyl distillation residue has reacted completely, open the gas collecting hood and inject low-calorific-value aqueous waste liquid into the reaction vessel. High-calorific-value waste liquid refers to waste liquid with a calorific value above 3000 kcal. This type of waste liquid can be directly burned or its energy can be utilized in industrial production, such as methanol and styrene in the petrochemical industry. Low-calorific-value waste liquid refers to waste liquid with a calorific value below 3000 kcal, such as acidic or alkaline waste liquid after solid waste incineration. It should have a calorific value <1000 kcal / kg, density ≤1.1 kg / L, and pH 4-10. Cool the reaction solids for at least 2 hours. The injection volume of the low-calorific-value aqueous waste liquid is 300-400 L.

[0036] Example 2

[0037] This embodiment provides a method for treating acetyl distillation residue, including the following steps:

[0038] First, a 15cm thick layer of sawdust is evenly spread in the reaction vessel, which has an opening only at the top.

[0039] Separately, mix 150 kg of sawdust and 200 kg of slaked lime evenly to form a mixture;

[0040] Spread the mixture of sawdust and slaked lime evenly on the sawdust layer in the reaction vessel;

[0041] Cover the top of the reaction vessel with a layer of plate and frame sludge, spread it evenly with sawdust, and the thickness of the plate and frame sludge should be 40cm to ensure that no sawdust is exposed.

[0042] Finally, move the reaction vessel with the added auxiliary materials to the closed reaction chamber, cover it with the gas collection hood, leaving a small gap, connect the pipe to the gas collection hood and connect it to the induced draft system of the incinerator.

[0043] Insert the waste liquid pipe into the reaction vessel and pump the acetyl distillation residue into the reaction vessel, so that the acetyl distillation residue seeps into the lower layer of the reaction vessel and reacts with the excipients;

[0044] After the acetyl distillation residue is removed, the gas collection hood is tightly closed, and the mixture is allowed to stand under negative pressure for a full reaction. The reaction time is controlled to be 14 hours.

[0045] After the acetyl distillation residue has reacted completely, open the gas collecting hood and inject a low-calorific-value aqueous waste liquid (calorific value <1000 kcal / kg, density ≤1.1 kg / L, pH 4-10) into the reaction vessel. Cool the reaction solids for at least 2 hours. The injection volume of the low-calorific-value aqueous waste liquid is 300-400 L.

[0046] Example 3

[0047] This embodiment provides a method for treating acetyl distillation residue, including the following steps:

[0048] First, a 10cm thick layer of sawdust is evenly spread in the reaction vessel, which has an opening only at the top.

[0049] Separately, mix 100g of sawdust and 150g of slaked lime until homogeneous to form a mixture;

[0050] Spread the mixture of sawdust and slaked lime evenly on the sawdust layer in the reaction vessel;

[0051] Cover the top of the reaction vessel with a layer of plate and frame sludge, spread it evenly and cover it with sawdust. The thickness of the plate and frame sludge should be 20cm to ensure that no sawdust is exposed.

[0052] Finally, move the reaction vessel with the added auxiliary materials to the closed reaction chamber, cover it with the gas collection hood, leaving a small gap, connect the pipe to the gas collection hood and connect it to the induced draft system of the incinerator.

[0053] Insert the waste liquid pipe into the reaction vessel and pump the acetyl distillation residue into the reaction vessel, so that the acetyl distillation residue seeps into the lower layer of the reaction vessel and reacts with the excipients;

[0054] After the acetyl distillation residue is removed, the gas collection hood is tightly closed, and the mixture is allowed to stand under negative pressure for a full reaction. The reaction time is controlled to be 10 hours.

[0055] After the acetyl distillation residue has reacted completely, open the gas collecting hood and inject a low-calorific-value aqueous waste liquid (calorific value <1000 kcal / kg, density ≤1.1 kg / L, pH 4-10) into the reaction vessel. Cool the reaction solids for at least 2 hours. The injection volume of the low-calorific-value aqueous waste liquid is 300-400 L.

[0056] In the above embodiment, after the core temperature of the solid material in the reaction vessel is lower than 40°C, the residue in the reaction vessel is poured into the incineration pit, mixed evenly with other waste materials, and then incinerated.

[0057] Before processing, relevant indicators of the acetyl distillation residue were tested, and the relevant test data are shown in Table 1:

[0058]

[0059]

[0060] Table 1

[0061] The products obtained from the above Examples 1 and 2 were sampled and tested to compare and analyze with relevant test indicators, in order to verify the effectiveness and degree of action of the treatment process. The test indicators of the products obtained after the treatment in Example 1 are shown in Table 2:

[0062]

[0063] Table 2

[0064] The detection indicators of the products obtained after treatment in Example 2 are shown in Table 3:

[0065]

[0066] Table 3

[0067] Comparison of various detection indicators before and after treatment shows that the content of P, S, and Cl in the product obtained after treatment is much lower than the original level. The quicklime played a good role in fixing P, S, and Cl in acetyl, which further supports the feasibility of this treatment method.

[0068] Testing verified that the calorific value of the acetyl distillation residue was significantly reduced during the reaction with raw and auxiliary materials, decreasing from 6000 kcal to around 3000 kcal. Under the condition that the system design heat load was determined, the system capacity was greatly improved.

[0069] The above embodiments involve adding slaked lime before incineration, which helps the acidic elements (sulfur, chlorine, phosphorus, etc.) react with Ca2+ to form stable divalent salts. During the later stage of incineration, these salts can be removed from the incineration furnace as incineration slag, preventing them from forming low-boiling-point potassium or sodium salts that enter the boiler back end of the incineration system and cause scaling and blockage. This greatly improves the stability and continuity of system production.

[0070] The raw material used in the pretreatment of the above embodiments is slaked lime, which is low in cost. Through pretreatment, the consumption of liquid alkali at the end of incineration can be reduced, significantly saving costs and improving economic efficiency. The calorific value of the acetyl distillation residue is greatly reduced during the pretreatment process, from about 6000 kcal to about 3000 kcal. Under the condition that the system design heat load remains unchanged, the system capacity is greatly increased, and more acetyl distillation residue can be consumed.

[0071] Acetyl distillation residue has a strong odor, which is especially pronounced when it reacts with quicklime. This invention reduces the intensity of the reaction between acetyl distillation residue and quicklime by mixing sawdust and quicklime before contacting them. However, the heat preservation effect of sawdust prolongs the reaction time between acetyl distillation residue and quicklime. At the same time, the steam and gas generated by the reaction are directly drawn into the incinerator by the incineration exhaust system for treatment. The odor is controllable throughout the reaction process, with no smoke or odor escaping, thus preventing environmental pollution.

[0072] Existing hazardous waste incineration systems have a solid-liquid ratio of approximately 7:3, while most hazardous waste requiring incineration in the market is predominantly liquid with less solid, posing a challenge to hazardous waste incineration. The method provided by this invention converts acetyl distillation residue into solid through pretreatment technology, effectively reducing the amount of liquid material and improving hazardous waste treatment capacity. Simultaneously, because the pretreatment reaction of acetyl distillation residue is exothermic, a significant amount of low-calorific-value aqueous waste liquid is consumed for cooling, achieving the co-treatment of low-calorific-value aqueous waste liquid.

[0073] During the static reaction of the acetyl distillation residue, heat and steam are generated. At the same time, due to the heat preservation effect of sawdust, the reaction between the acetyl distillation residue and quicklime is promoted to be more thorough. When the reaction is most vigorous, the temperature of the inner core of the container can exceed 100°C. However, the sawdust only carbonizes under the air-isolated conditions of sludge and does not pose a fire risk. In addition, the steam and gas generated by the reaction are then drawn into the incinerator for treatment through the exhaust system. There is no smoke or odor escaping during the reaction process.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for treating acetyl distillation residue, characterized in that, include: A layer of sawdust is evenly spread in the reaction vessel, which has an opening only at the top; Separately, mix sawdust and slaked lime in a mass ratio of 1:1 to 1:1.5 until homogeneous to form a mixture; Spread the mixture of sawdust and slaked lime evenly on the sawdust layer in the reaction vessel; Cover the top of the reaction vessel with a plate and frame sludge layer, spread it evenly over the sawdust, and ensure that no sawdust is exposed. Finally, move the reaction vessel with the added auxiliary materials to the closed reaction chamber, cover it with the gas collection hood, leaving a corner gap, connect the pipe to the gas collection hood and connect it to the induced draft system of the incinerator; Insert the waste liquid pipe into the reaction vessel and pump the acetyl distillation residue into the reaction vessel, so that the acetyl distillation residue seeps into the lower layer of the reaction vessel and reacts with the auxiliary materials; After the acetyl distillation residue is removed, the gas collection hood is tightly closed, and the mixture is allowed to stand under negative pressure to allow for a full reaction. After the acetyl distillation residue has reacted completely, open the gas collecting hood and inject a low-calorific-value aqueous waste liquid into the reaction vessel. The liquid has a calorific value of <1000kcal / kg, a density of ≤1.1kg / L, and a pH of 4-10. Cool the reaction solids for at least 2 hours. Once the core temperature of the solid material in the reaction vessel is below 40°C, the residue in the reaction vessel is poured into the incineration pit, mixed evenly with other waste materials, and then incinerated.

2. The method for treating acetyl distillation residue according to claim 1, characterized in that: The thickness of the sludge layer laid in the plate frame is 20-40cm.

3. The method for treating acetyl distillation residue according to claim 1, characterized in that: The thickness of the sawdust layer should be 10-15cm.

4. The method for treating acetyl distillation residue according to claim 1, characterized in that: The reaction time is controlled to be 10-14 hours.

5. The method for treating acetyl distillation residue according to claim 1, characterized in that: The injection volume of the low-calorific-value aqueous waste liquid is 1.5-2 times the mass of slaked lime.

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