Pretreatment method for acetic acid distillation residue before incineration

Abstract

The application provides a pretreatment method for acetyl distillation residual liquid before incineration, which comprises the following steps: S1, taking aqueous waste liquid with a density lower than that of the acetyl distillation residual liquid to be treated, and adding flake caustic soda to dissolve to obtain an alkaline waste liquid; S2, adding the acetyl distillation residual liquid into a container containing the alkaline waste liquid, and the acetyl distillation residual liquid is settled at the bottom, then adding slaked lime in batches, and standing to react until most of the materials in the container are solidified; and completing the pretreatment operation. The application provides a pretreatment method for acetyl distillation residual liquid before incineration, which can reduce the heat value of the acetyl distillation residual liquid, solidify the acetyl distillation residual liquid, improve the treatment efficiency, avoid the blockage of the rear end of the system, and improve the stability and continuity of the production of the incineration system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of environmental protection, and particularly relates to a pretreatment method for acetyl distillation residual liquid before incineration. BACKGROUND

[0002] The acetyl distillation residual liquid is a distillation residual liquid generated in the pesticide intermediate production process of a surrounding chemical plant collected by the applicant, that is, after 91% of the ethylenediamine reacts with dimethyl sulfate and then concentrated sulfuric acid is added into an acetyl production device, acetyl wastewater is generated after the reaction, which has high heat value, strong odor, high toxicity, great danger, great disposal difficulty, and high disposal charge price on the market. + , Na + ions form low-boiling-point salts such as potassium and sodium, causing the boiler and the post-end process equipment of the incineration system to be frequently blocked, resulting in the shutdown of the incineration system; and the acid elements consume a large amount of liquid alkali in the post-end flue gas treatment section, so that the disposal cost is high. Secondly, the heat value of the acetyl distillation residual liquid is too high, and under the condition that the system design heat load is determined, the disposal of the acetyl distillation residual liquid will have a great negative impact on the system capacity. SUMMARY

[0003] The present application provides a pretreatment method for acetyl distillation residual liquid before incineration, which can reduce the heat value, solidify the treatment, improve the treatment efficiency, avoid the blockage of the system post-end, improve the stability and continuity of the production of the incineration system, increase the disposal amount, and reduce the disposal cost.

[0004] The technical scheme of the present application is a pretreatment method for acetyl distillation residual liquid before incineration, which comprises the following steps:

[0005] S1. Taking water-based waste liquid with a density lower than the acetyl distillation residual liquid to be treated, dissolving the flake alkali to obtain alkaline waste liquid;

[0006] S2. Adding the acetyl distillation residual liquid into a container containing the alkaline waste liquid, the acetyl distillation residual liquid sinks to the bottom, and the slaked lime is added in batches, and the reaction is allowed to stand until more than 80% of the materials in the container are solidified; and the pretreatment operation of the acetyl distillation residual liquid before incineration is completed.

[0007] Further, the heat value of the acetyl distillation residual liquid is 5000-6000 kcal / kg, the phosphorus is 0.5-5%, the sulfur is 3-7%, and the chlorine is 0.5-2%.

[0008] Further, the heat value of the water-based waste liquid is <1000 kcal / kg, and the density is ≤1.1 kg / L.

[0009] Further, the addition amount of the flake alkali in the water-based waste liquid is 3-6 kg / ton.

[0010] Further, the volume ratio of acetyl distillation residue to alkaline waste liquid is 0.8:0.36-0.5.

[0011] Further, the amount of slaked lime added is 15-25% of the mass of the acetyl distillation residue.

[0012] Further, after the addition of slaked lime in S2 is completed, a gas collection hood is arranged at the top of the container and connected to a ventilation port, and the standing reaction time is 8h.

[0013] Further, the gas discharged from the ventilation port is treated by an alkali spray tower+UV photolysis+activated carbon adsorption. The effective component in the alkali washing is sodium hypochlorite.

[0014] Further, after the standing reaction in S2, the material in the container is completely solidified, and then the material is directly cooled and then incinerated.

[0015] Further, after the standing reaction in S2, the material in the container is not completely solidified, sawdust is added to dry the material in the container, then the material is cooled, and finally incinerated.

[0016] The present application has the following beneficial effects:

[0017] 1. The present application adds slaked lime to the acetyl distillation residue before incineration, which helps the acidic elements (sulfur, chlorine, phosphorus, etc.) in the acetyl distillation residue to react with Ca 2+ to form stable divalent salts, which can be removed in the form of incineration slag in the incinerator hearth during later incineration, avoiding the formation of low-boiling potassium or sodium salts into the back end of the incineration system boiler, which can cause equipment blockage; greatly improving the stability and continuity of the system production.

[0018] 2. The raw material used in the pretreatment of the present application is slaked lime, which has low cost. Through the pretreatment in the early stage, the consumption of liquid caustic in the back end of the incineration can be reduced, the cost can be greatly saved, and the economic benefit can be improved. The heat value of the acetyl distillation residue is greatly reduced from about 6000 large calories to about 3000 large calories during the pretreatment process. Under the condition that the heat load of the system design is unchanged, the system capacity is greatly improved, and more acetyl distillation residue can be consumed.

[0019] 3. The acetyl distillation residue has a strong odor, and the odor is particularly strong during the pretreatment reaction with slaked lime. In the present application, alkaline waste liquid is added to the upper layer. Since the two are not miscible, the alkaline waste liquid is located in the upper layer, forming a liquid seal, which helps to absorb acidic gases during the pretreatment reaction and reduce environmental pollution. At the same time, a large amount of low-heat value aqueous waste liquid can be consumed during the heat release of the acetyl distillation residue pretreatment, and the synergistic disposal of low-heat value aqueous waste liquid is also achieved.

[0020] 4. Existing hazardous waste incineration systems have a solid-liquid ratio of approximately 7:3. Currently, most hazardous waste used for incineration 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 materials and improving hazardous waste treatment capacity. Detailed Implementation

[0021] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be regarded as limiting the scope of the present invention.

[0022] The acetyl distillation residue detection data involved in the following examples are shown in Table 1.

[0023] Table 1

[0024]

[0025]

[0026] The water-based waste liquid involved has a calorific value of <1000kcal / kg and a density of ≤1.1kg / L.

[0027] Example 1

[0028] S1. Take 1 ton of aqueous waste liquid (calorific value 800Kcal / kg, density 0.95Kg / L), add 5kg of caustic soda flakes to dissolve and prepare alkaline waste liquid for later use;

[0029] S2. Add 400L of alkaline waste liquid with fully dissolved caustic soda to the iron tank. Pour 1 ton of acetyl distillation residue into the iron tank. Since acetyl is denser than water, acetyl will automatically sink to the bottom. Slowly and evenly add 150Kg (6 bags) of quicklime to the iron tank. Each bag of quicklime should be added slowly in four portions. Do not add the whole bag of quicklime.

[0030] S3. After adding quicklime, move the iron tank to the pre-set deodorization system vent position, cover the iron tank with a gas collection hood, connect the deodorization vent with a hose, close the doors and windows of the pretreatment workshop, and let it stand for 9 hours to fully react. The acetyl distillation residue and the alkaline waste liquid in it have been completely solidified and there is no liquid phase residue. After cooling, it can be incinerated.

[0031] Example 2:

[0032] S1. Take 1 ton of aqueous waste liquid with a calorific value of 600 kcal / kg and a density of 1.02 kg / L, add 5 kg of caustic soda flakes to dissolve it to prepare alkaline waste liquid for later use.

[0033] S1, add 500L of alkali waste liquid with fully dissolved caustic soda to the iron tank, pour 1 ton of acetyl distillation residue into the iron tank, since acetyl has a higher density than water, acetyl will automatically sink to the bottom; slowly and evenly add 150kg of slaked lime (6 bags) to the iron tank, each bag of slaked lime is slowly added in four times, and the whole bag of slaked lime is prohibited to be added;

[0034] S2, after adding slaked lime, move the iron tank to the pre-set odor removal system air port position, cover the iron tank with a gas hood, connect the hose to the odor removal air port, close the doors and windows of the pretreatment workshop, and stand still for 10h for sufficient reaction; when only a small part of acetyl distillation residue and alkali waste liquid remains, add sawdust to dry the unreacted waste liquid; after the material is completely cooled, it can be crushed and incinerated.

[0035] Example 3

[0036] S1, take 1 ton of aqueous waste liquid, add 6kg of caustic soda to dissolve and prepare alkali waste liquid;

[0037] S2, add 500L of alkali waste liquid with fully dissolved caustic soda to the iron tank, pour 1 ton of acetyl distillation residue into the iron tank, since acetyl has a higher density than water, acetyl will automatically sink to the bottom; slowly and evenly add 150kg of slaked lime (6 bags) to the iron tank, each bag of slaked lime is slowly added in four times, and the whole bag of slaked lime is prohibited to be added;

[0038] S3, after adding slaked lime, move the iron tank to the pre-set odor removal system air port position, cover the iron tank with a gas hood, connect the hose to the odor removal air port, close the doors and windows of the pretreatment workshop, and stand still for 8h for sufficient reaction; a small amount of liquid phase remains in the iron tank, add 3kg of sawdust to dry it, and then it can be incinerated after cooling.

[0039] Example 4

[0040] S1, take 1 ton of aqueous waste liquid, add 3kg of caustic soda to dissolve and prepare alkali waste liquid;

[0041] S2, add 550L of alkali waste liquid with fully dissolved caustic soda to the iron tank, pour 1 ton of acetyl distillation residue into the iron tank, since acetyl has a higher density than water, acetyl will automatically sink to the bottom; slowly and evenly add 210kg of slaked lime (7 bags) to the iron tank, each bag of slaked lime is slowly added in four times, and the whole bag of slaked lime is prohibited to be added;

[0042] S3, after adding slaked lime, move the iron tank to the pre-set odor removal system air port position, cover the iron tank with a gas hood, connect the hose to the odor removal air port, close the doors and windows of the pretreatment workshop, and stand still for 8h for sufficient reaction; acetyl distillation residue and alkali waste liquid have been completely solidified and no liquid phase remains, and then it can be incinerated after cooling.

[0043] The material pretreated in Examples 1-4 is incinerated, and the odor diffusion is effectively controlled during transfer, mixing and feeding. The high-melting-point calcium salt produced by combining with calcium is discharged in advance by the chain plate machine, effectively reducing the salt content entering the flue, controlling coking, reducing the cleaning period and time, effectively improving the disposal efficiency and reducing the disposal cost. Directly incinerating the acetyl distillation residue has a large odor during the treatment process, a long disposal period, salt in the material easily adheres to the flue wall, high halogen content leads to high consumption of liquid caustic, and the effect is far less reasonable than the disposal method of the present application.

[0044] Before the acetyl distillation residue is solidified and pretreated, it is all incinerated by direct spraying, and the flue cleaning period is every 2 days, and the time is 1-1.5 hours each time. After the acetyl distillation residue is solidified and pretreated by the above examples, the flue cleaning period of the incineration line is once a week, and the cleaning time is 30-50 minutes. Combined with the liquid caustic consumption in the caustic washing tower before and after the acetyl distillation residue is solidified and pretreated, the liquid caustic consumption in the caustic washing tower is reduced by 20% during the incineration disposal of the acetyl distillation residue after solidification and pretreatment. It can be seen that the incineration disposal of the acetyl distillation residue after solidification and pretreatment can effectively reduce the halogen content of the material itself, improve the flue plugging condition, and prolong the cleaning period. The disposal amount of the material is improved, and the consumption of liquid caustic is reduced.

[0045] The above examples are only to illustrate the technical ideas and characteristics of the present application, and the content is only the preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Within the technical scope disclosed in the present application, equivalent changes or improvements according to the technical solutions and inventive concepts of the present application should be covered within the protection scope of the present application.

Claims

1. A pretreatment method for acetyl distillation residue before incineration, characterized in that, Includes the following steps: S1. Take an aqueous waste liquid with a density lower than the acetyl distillation residue to be treated, add caustic soda flakes to dissolve it to obtain an alkaline waste liquid. The amount of caustic soda flakes added to the aqueous waste liquid is 3-6 kg / ton. S2. Add the acetyl distillation residue to a container containing alkaline waste liquid. The volume ratio of the acetyl distillation residue to the alkaline waste liquid is 0.8:0.36~0.

5. The acetyl distillation residue settles to the bottom. Add quicklime in batches. After the quicklime is added, install a gas collection hood connected to a vent at the top of the container. The gas discharged from the vent is treated by alkaline washing, ultraviolet photolysis, and activated carbon adsorption. The effective component in the alkaline washing is sodium hypochlorite. After adding the quicklime, allow the reaction to stand for more than 8 hours until more than 80% of the material in the container is solidified. This completes the pretreatment operation before incineration of the acetyl distillation residue.

2. The method according to claim 1, characterized in that: The calorific value of the acetyl distillation residue is 5000~6000 kcal / kg, the phosphorus content is 0.5~5%, the sulfur content is 3~7%, and the chlorine content is 0.5~2%.

3. The method according to claim 1, characterized in that: The calorific value of the aqueous waste liquid is <1000kcal / kg, and the density is ≤1.1kg / L.

4. The method according to claim 1, characterized in that: The amount of slaked lime added is 15-25% of the mass of the acetyl distillation residue.

5. The method according to any one of claims 1 to 4, characterized in that: After the material in the container is allowed to stand for reaction in S2 and then completely solidified, it is directly cooled and then fed into the incinerator.

6. The method according to any one of claims 1 to 4, characterized in that: After the reaction in S2 is allowed to stand, the material in the container is not completely solidified. Sawdust is added to dry the material in the container, then it is cooled, crushed, and finally fed into the incinerator.

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