CN110240928B

CN110240928B - Deacidifying and refining method of diesel oil

Info

Publication number: CN110240928B
Application number: CN201910544084.8A
Authority: CN
Inventors: 于海莲; 胡震; 王忠磊
Original assignee: Sichuan University of Science and Engineering
Current assignee: Sichuan University of Science and Engineering
Priority date: 2019-06-21
Filing date: 2019-06-21
Publication date: 2021-05-04
Anticipated expiration: 2039-06-21
Also published as: CN110240928A

Abstract

The invention discloses a diesel oil deacidification refining method, which comprises the steps of preheating diesel oil to be deacidified, adding a composite deacidification agent, uniformly mixing, stirring at 20-30 ℃ for reaction, standing for layering after the reaction is finished, and separating an upper oil phase to obtain the deacidified diesel oil; the composite deacidification agent comprises sodium hexamethyldisilazide and polyoxy pentaerythritol polyether. The adopted composite deacidification agent and the two are cooperatively matched, so that the naphthenic acid is effectively removed, and the emulsification phenomenon in the deacidification process is avoided. The composite deacidification agent can be recycled, has no waste agent discharge, is beneficial to environmental protection, saves resources and meets the requirement of green deacidification. The method has the advantages of simple process flow operation, mild conditions, low cost and easy industrial production, and can be widely applied to the petroleum processing industry.

Description

Deacidifying and refining method of diesel oil

Technical Field

The invention relates to the technical field of wastewater treatment, in particular to a diesel oil deacidification refining method.

Background

The acidic substances in diesel oil, mainly naphthenic acid, have strong corrosivity. In the production process of diesel oil, can produce serious corruption to production facility, will influence its work after the corruption that produces equipment has reached a certain degree, has restricted the production progress of diesel oil, and too big to the corruption that storage device produced in the storage process still can cause revealing of diesel oil, and this has not only led to economic loss, still can cause serious pollution to the environment. The most serious problem is that the corrosion to the engine causes carbon deposition of an oil nozzle of the engine and increase of sediments in an air cylinder, and the service life of the engine is shortened; the over-high acidity can also reduce the stability of the diesel oil, cause the emulsification and rancidity and deterioration of the diesel oil, greatly reduce the cost performance of the diesel oil and further reduce the sale price of the diesel oil. Therefore, the removal of naphthenic acids from diesel oil is of great industrial importance.

At present, the diesel deacidification method mainly comprises the following steps: alkali washing deacidification, alcohol ammonia deacidification, esterification deacidification, hydrogenation, thermal decomposition, solvent extraction deacidification, adsorption separation deacidification, membrane separation deacidification and the like. The deacidification by the alkaline washing method is the most common deacidification method, the deacidification method is very thorough for high acid value raw oil, can effectively control the naphthenic acid corrosion phenomenon, has simple process flow, low investment and mild reaction temperature, and is widely applied to various domestic and foreign refineries, but the foam emulsification phenomenon is very serious in the deacidification reaction process by the alkaline washing method, so that the separation is difficult, the alkaline residue carries more oil, the yield of diesel oil can be greatly reduced, the diesel oil deacidification effect is poor, the refining work after the diesel oil deacidification is more difficult, the discharge amount of alkaline liquor is large, and the environment is greatly polluted. In order to solve the problems, researchers also do a lot of work, for example, the invention patent CN200410085318.0 discloses a process method for removing naphthenic acid from diesel oil, distillate oil and deacidification agent are added into a high-efficiency microwave reaction tank, the high-efficiency microwave reaction tank is directly moved into a high-efficiency microwave reaction system for microwave radiation, and the emulsification phenomenon is solved by using the microwave effect. However, the method has high requirements on production equipment, high cost, easy leakage of microwaves and the like, and is not beneficial to industrial production. The invention patent CN200410008621.0 discloses a method for removing and recovering acid components from oil products, which adopts a compound solvent composed of C2-5 saturated alkanol, ammonia water and a demulsifier, and can effectively inhibit emulsification in the process of extraction and deacidification, thereby obtaining naphthenic acid with higher purity. In the process of recovering naphthenic acid, the method needs to wash with petroleum ether and adjust the pH value with hydrochloric acid; the solvent can be reused only by adjusting with ammonia water or NaOH, and waste acid and waste alkali can be discharged, which is not beneficial to environmental protection.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a novel diesel deacidification refining method, and aims to solve the technical problems of serious emulsification phenomenon, large alkali liquor discharge amount, long deacidification period, more required labor force, high cost, low diesel yield, poor diesel quality, environmental pollution and the like of the conventional deacidification method.

In order to solve the technical problems, the invention adopts the following technical scheme: a deacidification refining method of diesel oil comprises the following steps: preheating diesel oil to be deacidified, adding a composite deacidifying agent, uniformly mixing, stirring at 20-30 ℃ for reaction, standing for layering after the reaction is finished, and separating out an upper-layer oil phase to obtain the deacidified diesel oil; the composite deacidification agent comprises sodium hexamethyldisilazide solution and polyoxy pentaerythritol polyether.

Therefore, the hexamethyldisilazane sodium amide in the composite deacidification agent solution can react with the acid substances in the diesel oil to generate a sodium naphthenate solution, and the sodium naphthenate solution and the diesel oil are two phases which can be separated to form an oil phase and a water phase, so that the diesel oil deacidification is realized, and the diesel oil is refined. When diesel oil is deacidified, the deacidification system usually shows an emulsification phenomenon, the charge of the deacidification system is negative, polyoxy pentaerythritol polyether can ionize cations, the cations with opposite polarities are adsorbed on the surfaces of water drops in the emulsification system and neutralize the positive charges in the emulsification system, so that electrostatic repulsion among emulsion drops is weakened instantly and greatly, an interface protective film formed by the same charges is damaged, and emulsion is broken and rapidly settled from an oil phase; in addition, once the emulsion meets polyoxy pentaerythritol polyether, the emulsion can compress and destroy an electric double layer formed by an emulsion system, the interfacial film tension strength is greatly weakened, the frequency of mutual collision among emulsion droplets is greatly increased, and the polyoxy pentaerythritol polyether continuously enters and permeates into the emulsion system, so that the basic structure of the emulsion system can be changed, and rapid aggregation demulsification is formed.

Further, the concentration of the hexamethyldisilazane sodium amide solution is 0.05 g/mL-0.20 g/mL.

Further, the mass ratio of the hexamethyldisilazane sodium amide solution to the polyoxy pentaerythritol polyether is 10: 1-3: 1.

Further, the volume ratio of the composite deacidification agent to the diesel oil is 1: 10-12: 10.

Further, the reaction time is 1-50 min, so that the composite deacidification agent can fully react with acidic substances in the diesel oil.

Further, the standing time is 5-45 min, so that an oil phase and a water phase can be formed and separated, deacidification of the diesel oil is realized, and refining of the diesel oil is realized.

Further, the stirring speed is 100-500 rpm/min, so that the composite deacidification agent is fully contacted with the diesel oil, and the reaction efficiency is effectively increased.

Further, the preheating temperature is 10-50 ℃.

The action mechanism of the composite deacidification agent is as follows:

besides the deacidification agent sodium hexamethyldisilazide and polyoxy pentaerythritol polyether exert respective excellent deacidification effect, the deacidification agent sodium hexamethyldisilazide and polyoxy pentaerythritol polyether generate positive synergistic demulsification effect between the deacidification agent sodium hexamethyldisilazide and the polyoxy pentaerythritol polyether, further enhance the deacidification effect of the diesel oil, and are mainly reflected in the following aspects: firstly, the active components of the deacidification agent, namely the sodium hexamethyldisilazane and the polyoxy pentaerythritol polyether, are two surfactants, and have excellent surface activity, one surfactant can enable the system to generate cations, and the other surfactant can generate anions, so that the negative emulsification problem caused by mutual repulsion of charges of the same kind in the deacidification system can be effectively solved by combining the two surfactants, and more importantly, the separation of precipitates in the deacidification system is accelerated, and the deacidification effect is improved. Secondly, the active ingredient sodium hexamethyldisilazide can automatically ionize sodium ions under the condition of excess, the sodium ions are taken as cations and can offset the electronegativity of anions in an oil phase in a diesel deacidification system, the negative effect of an isolating membrane generated by only one kind of charges in an emulsification system formed in the deacidification process can be eliminated, the active self-demulsification effect can be achieved, more importantly, the active ingredient polyoxy pentaerythritol polyether contains more hydroxyl groups, the hydroxyl groups can be exchanged by the sodium ions of the deacidification agent under the external effect, more positive cations are released, and when the active ingredient sodium hexamethyldisilazide enters the inside of an emulsion, the isolating membrane can penetrate through the isolating membrane, the rupture of the membrane is accelerated, and the layered emulsion is accelerated. The cations can further counteract anions in an oil phase emulsification system, so that the charge is quickly balanced, and the unfavorable emulsification phenomenon caused by over concentration of the same charge in a deacidification system is further avoided. Finally, the deacidification agent of the polyoxy pentaerythritol polyether is also a hydrophilic viscosity regulating surfactant, has good viscosity regulating effect, can independently increase the viscosity of an emulsified phase after the diesel oil generates an emulsification phenomenon in the deacidification process, can inhibit the viscosity of the polyoxy pentaerythritol polyether after encountering an emulsified system, greatly reduces the viscosity of the emulsified system, further releases substances agglomerated in the emulsified system, disperses the agglomeration degree of the emulsified system, can independently separate different systems to form two phases, a system with high density is settled, is positioned at a lower layer, and a substance with low density runs to an upper layer, so that the deacidification agent of the polyoxy pentaerythritol polyether is synergistically layered, and solves the technical problem of emulsification formed in the diesel oil deacidification process. Therefore, besides the deacidification function of the hexamethyldisilazane sodium amide and the polyoxy pentaerythritol polyether, the hexamethyldisilazane sodium amide and the polyoxy pentaerythritol polyether also have the positive synergistic compatibility demulsification function, so that the deacidification effect of the diesel oil is further improved, and the quality of the refined diesel oil is improved.

Compared with the prior art, the invention has the following beneficial effects:

1. in the deacidification and refining process of the diesel oil, the hexamethyldisilazane-based sodium amide and the polyoxy pentaerythritol polyether are used as the composite deacidification agent, and the hexamethyldisilazane-based sodium amide and the polyoxy pentaerythritol polyether are cooperatively compatible, so that the naphthenic acid is effectively removed, and the emulsification phenomenon formed in the deacidification process of the diesel oil is avoided. In the whole deacidification process, the composite deacidification agent can be recycled, no waste agent is discharged, the environment is protected, resources are saved, and the requirement of green deacidification is met.

2. The method has the advantages of good effect of removing naphthenic acid, high diesel oil yield (over 94%) and good separation effect, and the deacidification rate of the diesel oil can reach over 92%. The process flow has simple operation, mild condition and low cost, is easy for industrial production and can be widely applied to the petroleum processing industry.

Detailed Description

The present invention will be described in further detail with reference to examples. The acid value of the raw diesel oil used in the following examples was 135.52mgKOH/100 mL.

Example 1

1) And mixing the hexamethyldisilazane sodium amide solution with the concentration of 0.06g/mL and polyoxy pentaerythritol polyether according to the mass ratio of 9:1 to obtain the composite deacidification agent.

2) Preheating 30mL of diesel oil to be deacidified at 25 ℃, then placing the diesel oil in a 500mL three-neck flask, adding 30mL of composite deacidification agent, uniformly mixing, stirring at a constant speed of 200r/min by using an electronic constant-speed stirrer at 20 ℃, reacting for 5min, transferring the liquid in the three-neck flask into a separating funnel, standing for 10min, layering, and separating out an upper oil phase to obtain the deacidified diesel oil.

Example 2

1) And mixing the hexamethyldisilazane sodium amide solution with the concentration of 0.07g/mL and polyoxy pentaerythritol polyether according to the mass ratio of 7:1 to obtain the composite deacidification agent.

2) Preheating 30mL of diesel oil to be deacidified at 35 ℃, then placing the diesel oil in a 500mL three-neck flask, adding 36mL of composite deacidification agent, uniformly mixing, stirring at a constant speed of 150r/min by using an electronic constant speed stirrer at 25 ℃, after reacting for 5min, transferring the liquid in the three-neck flask to a separating funnel, standing for 20min, layering, and separating out an upper oil phase to obtain the deacidified diesel oil.

Example 3

1) And mixing the hexamethyldisilazane sodium amide solution with the concentration of 0.08g/mL and polyoxy pentaerythritol polyether according to the mass ratio of 6:1 to obtain the composite deacidification agent.

2) Preheating 30mL of diesel oil to be deacidified at 48 ℃, then placing the diesel oil in a 500mL three-neck flask, adding 21mL of composite deacidification agent, uniformly mixing, stirring at a constant speed of 200r/min by using an electronic constant-speed stirrer at 20 ℃, reacting for 5min, transferring the liquid in the three-neck flask into a separating funnel, standing for 20min, layering, and separating out an upper oil phase to obtain the deacidified diesel oil.

Conventional deacidification analysis and demulsification experiments are carried out on the diesel oil obtained in the embodiments 1-3, and the results are shown in table 1.

The calculation formula of the deacidification rate of the diesel oil is as follows:

in the formula: a. the₀Acid number of diesel oil sample before deacidification, mgKOH/(100mL)

A-acid number of deacidified Diesel sample, mgKOH/(100mL)

TABLE 1

Examples	Acid value (mgKOH/100mL)	Deacidification Rate (%)	Yield (%)	Interface of oil phase and water phase
					Example 1	10.16	92.5	94.40	Clear interface and distinct layering
Example 2	6.4	95.3	96.1	Clear interface and distinct layering
					Example 3	3.25	97.6	98.0	Clear interface and distinct layering

As can be seen from Table 1, the oil phase and the water phase have clear interfaces, obvious layering, low acid value, good stability and good oil quality after the separation by the composite deacidification agent, the deacidification rate of the diesel oil can reach more than 92 percent, the yield of the diesel oil can also reach more than 94 percent, and the composite deacidification agent has good separation effect and can be widely applied to the petroleum processing industry.

The above description is only exemplary of the present invention and should not be taken as limiting, and any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A deacidification refining method of diesel oil is characterized by comprising the following steps: preheating diesel oil to be deacidified, adding a composite deacidifying agent, uniformly mixing, stirring at 20-30 ℃ for reaction, standing for layering after the reaction is finished, and separating out an upper-layer oil phase to obtain the deacidified diesel oil; the composite deacidification agent comprises sodium hexamethyldisilazide solution and polyoxy pentaerythritol polyether;

the concentration of the hexamethyldisilazane sodium amide solution is 0.05 g/mL-0.20 g/mL;

the mass ratio of the hexamethyldisilazane-based sodium amide solution to the polyoxypentaerythritol polyether is 10: 1-3: 1.

2. The diesel oil deacidification and refining method according to claim 1, wherein the volume ratio of the composite deacidification agent to the diesel oil is 1: 10-12: 10.

3. The diesel oil deacidification and purification method according to claim 1, wherein the reaction time is 1 to 50 min.

4. The diesel oil deacidification and purification method according to claim 1, wherein the standing time is 5 to 45 min.

5. The method for deacidifying and refining diesel oil according to claim 1, wherein the stirring speed is 100 to 500 rpm/min.

6. The diesel oil deacidification and purification method according to claim 1, wherein the preheating temperature is 10 to 50 ℃.