Crude oil deironing agent

Abstract

The invention relates to a crude oil deironing agent, and belongs to the technical field of oil field chemicals. The crude oil deironing agent is prepared by carrying out ultrasonic mixing reaction on ammonium citrate, citric acid and alkyl trimethyl ammonium hydrogen sulfate in water at 50-80 DEG C. After the mixing reaction, the obtained product possibly contains O and S six-membered rings and S = O, S-O and other bonds, and can jointly play a role in chelating iron, so that the chelating deironing capability is improved, the dosage of the agent is reduced, and the production cost is reduced. And meanwhile, the crude oil deironing agent has good water solubility, and can realize conversion from oil-soluble iron in crude oil to water-soluble iron when being used for deironing the crude oil, so that the iron in the crude oil can be effectively removed. The crude oil deironing agent is good in deironing effect, free of corrosivity, low in deironing cost, free of environment pollution in the operation process and easy to popularize on a large scale.

Description

Technical Field

[0001] The present invention relates to an iron remover for crude oil, belonging to the technical field of oilfield chemicals. Background Art

[0002] Crude oil needs to be processed through deep processing and fine processing to become petroleum products and chemical products for people to use. During these processing processes, it is often interfered by metal ions, which will affect the catalyst activity, service life, and electro-desalting operation, etc. The harm caused by iron in crude oil to the processing and use of crude oil is particularly obvious. Specifically, iron has a strong poisoning effect on catalytic cracking catalysts and heavy oil hydrogenation catalysts, and can cause the catalyst to bond and accumulate, resulting in catalyst fouling, inactivation, abnormal fluidization, and even permanent poisoning; iron will also promote the corrosion of the top of the atmospheric and vacuum distillation tower and the condensation system, and the fouling of the furnace tubes of the heating furnace and heat exchanger equipment. With the heavy quality, inferior quality of crude oil and the deepening of crude oil exploitation, the harm of metal elements in crude oil and the removal technical methods have attracted more and more attention.

[0003] Common methods for removing iron from crude oil mainly include: physical method, chemical method, biological method, etc. Among them, the chemical iron removal method is the simplest and feasible iron removal method, that is, an iron remover is added to the crude oil, and the iron remover reacts with oil-soluble iron (iron petroleum acid, porphyrin iron, non-porphyrin iron, etc.) to generate water-soluble iron, or generate a dispersed iron with hydrophilic-lipophilic characteristics and dispersed in the middle layer of the oil phase and water phase in the form of fine particles, and then the water-soluble iron or dispersed iron is separated from the crude oil through the electro-desalting process.

[0004] At present, there are mainly 3 types of iron removers used more: organic acids, chelating agents, and precipitants. Among them, organic acids are likely to cause corrosion of pipelines and equipment; the iron removal selectivity of chelating agents and precipitants is poor. Due to the high content of scale-forming and metal ions such as calcium and magnesium in crude oil and produced water, the consumption of the agent is large, and there are risks such as fouling and pipe blockage. For example, Chinese patent document CN112322340A discloses an iron metal remover for crude oil and its preparation method. This iron remover is composed of an iron chelating agent, an organic acid, a carboxylate, and a Schiff base. This crude oil metal iron remover has a significant iron removal effect on crude oil with a low iron content, but when removing iron from crude oil with an iron content higher than 30 ppm, a large amount of the agent needs to be used, and the iron removal effect is poor. Therefore, it is urgent to develop an iron remover for crude oil with good iron removal effect. Summary of the Invention

[0005] The purpose of the present invention is to provide an iron remover for crude oil, which can solve the problem of poor iron removal effect when the current iron remover for crude oil is used for iron removal of crude oil with a higher iron content.

[0006] In order to achieve the above purpose, the technical solution adopted by the iron remover for crude oil of the present invention is as follows:

[0007] An iron remover for crude oil is prepared by a method including the following steps: Mix ammonium citrate, alkyltrimethyl ammonium hydrogensulfate and citric acid in water at 50°C to 80°C; the mass ratio of ammonium citrate, alkyltrimethyl ammonium hydrogensulfate and citric acid is 1:(4.1 - 5):(0.8 - 1); the mixing reaction is carried out under ultrasonic conditions.

[0008] The iron remover for crude oil of the present invention is prepared by ultrasonically mixing ammonium citrate, citric acid and alkyltrimethyl ammonium hydrogensulfate in water at 50°C to 80°C. After the mixing reaction, the obtained product may contain O, S six-membered rings and bonds such as S=O and S-O, which can jointly play a role in chelating iron, improve the chelating iron removal ability, reduce the dosage of the agent. At the same time, the iron remover for crude oil of the present invention has good water solubility, and can realize the transformation of oil-soluble iron in crude oil into water-soluble iron when used for iron removal from crude oil, so as to effectively remove iron from crude oil. The iron remover for crude oil of the present invention has good iron removal effect, is not corrosive, the iron removal operation is simple, the iron removal cost is low, the environment will not be polluted during the operation process, and it is easy to be popularized on a large scale.

[0009] Citric acid and ammonium citrate can form a buffer system to promote the complexation of iron; when the dosage of citric acid is too much, the pH of the iron remover solution will be too low and the corrosiveness will be strong; when the dosage of citric acid is too little, the balance buffer capacity with ammonium citrate will be insufficient and the reaction promotion effect will be reduced. Citric acid can form a balance buffer system with ammonium citrate, effectively promoting the cyclization reaction between ammonium citrate and n-alkyltrimethyl ammonium hydrogensulfate.

[0010] Preferably, the power of the ultrasonic wave is 90 - 150 W·cm -2 . Preferably, the frequency of the ultrasonic wave is 20 - 50 kHz. If the frequency of the ultrasonic wave is too large, a large shear force will be generated, and the molecular chain is easily broken, affecting the stability of the product. If the frequency of the ultrasonic wave is too small, the reaction energy will be insufficient and the reactants will not be activated enough, which is not conducive to the formation of the target product.

[0011] Preferably, the time of the mixing reaction is not less than 60 min. Preferably, the time of the mixing reaction is 60 - 90 min. Experiments have proved that when the mixing reaction time is too short, the reaction is not sufficient and the iron removal effect of the prepared iron remover is poor; as the reaction time increases, the iron removal effect also improves. After 90 min, the iron removal effect changes little. In order to improve production efficiency and reduce costs, it is more appropriate to control the reaction time between 60 - 90 min.

[0012] Preferably, the alkyltrimethylammonium hydrogensulfate is selected from one or any combination of dodecyltrimethylammonium hydrogensulfate, tridecyltrimethylammonium hydrogensulfate, tetradecyltrimethylammonium hydrogensulfate, pentadecyltrimethylammonium hydrogensulfate, and hexadecyltrimethylammonium hydrogensulfate. The experimental results show that the crude oil iron remover prepared with the above-mentioned alkyltrimethylammonium hydrogensulfate has a good iron removal effect.

[0013] Preferably, after the mixing reaction is completed, the system after the mixing reaction is subjected to solid-liquid separation, and then the solvent in the liquid obtained by the solid-liquid separation is removed to obtain the iron remover. Preferably, the removal of the solvent in the liquid obtained by the solid-liquid separation is carried out by evaporation and drying.

[0014] Since water is required when using the crude oil iron remover, in order to save costs, after the mixing reaction is completed, the system after the mixing reaction may not be subjected to solid-liquid separation, but the system after the mixing reaction may be directly used as the iron remover; or the system after the mixing reaction may be subjected to solid-liquid separation, and then the liquid obtained by the solid-liquid separation may be directly used as the iron remover.

[0015] Preferably, the method for using the above-mentioned crude oil iron remover for iron removal from crude oil includes the following steps: mixing crude oil, a demulsifier, water, and the above-mentioned crude oil iron remover, and then separating the oil and water in the mixed system.

[0016] Preferably, the mass of the crude oil iron remover is 50-150 ppm of the mass of the crude oil.

[0017] In the present invention, there is no requirement for the type of the demulsifier. Those skilled in the art can select a commercially available demulsifier according to the properties of the crude oil, which can be a single demulsifier or a composite demulsifier. At the same time, there is no special requirement for the dosage of the demulsifier, and the dosage can be 30-80 ppm of the mass of the crude oil.

[0018] The iron removal principle is that a deironing agent is added to the crude oil to react with the oil-soluble iron to form water-soluble iron. After adding water, the generated water-soluble iron can be removed with the water through an electro-desalting device, thereby achieving the purpose of reducing iron in the crude oil. Therefore, a medium water is required when the iron remover is used on site. Generally, the added water volume accounts for 10-20% of the mass of the crude oil. In actual applications, the additional added water volume can be flexibly adjusted according to the water content in the crude oil. If the water content in the crude oil is low, more water is added correspondingly. If the water content in the crude oil is high, no water or less water is added. Specific Embodiments

[0019] The technical solutions of the present invention will be further described below in conjunction with specific embodiments.

[0020] The crude oil iron removers of Examples 1-9 are prepared by a method including the following steps:

[0021] Add ammonium citrate with a mass of x g, alkyltrimethylammonium hydrogensulfate (the alkyltrimethylammonium hydrogensulfate is dodecyltrimethylammonium hydrogensulfate, tetradecyltrimethylammonium hydrogensulfate or hexadecyltrimethylammonium hydrogensulfate) with a mass of y g and distilled water with a mass of z g into a 500 mL beaker, stir until the ammonium citrate and alkyltrimethylammonium hydrogensulfate are completely dissolved, and then perform ultrasonic treatment under the condition that the ultrasonic temperature is a °C (the ultrasonic power is b W·cm -2 , the ultrasonic frequency is c kHz), while slowly adding citric acid with a mass of m g. After the addition of citric acid is completed, continue ultrasonic treatment for n min to make the mixture in the beaker undergo a mixing reaction. After the mixing reaction is completed, filter and remove impurities from the reaction system, and then evaporate and dry the filtered liquid to remove the solvent, obtaining a light yellow solid, which is the iron remover.

[0022] The dosages of ammonium citrate and citric acid, the type and dosage of alkyltrimethylammonium hydrogensulfate, as well as the ultrasonic power, ultrasonic frequency, temperature and time of the mixing reaction used in the preparation of the iron removers in Examples 1-9 are shown in Table 1.

[0023] Table 1 The dosages of ammonium citrate and citric acid, the type and dosage of alkyltrimethylammonium hydrogensulfate, as well as the ultrasonic power, ultrasonic frequency, temperature and time of the mixing reaction used in the preparation of the iron removers in Examples 1-9

[0024]

[0025] Comparative Example 1

[0026] The iron remover of this comparative example is prepared by a method including the following steps: Add 10 g of ammonium citrate, 41 g of dodecyltrimethylammonium hydrogensulfate and 248 g of distilled water into a 500 mL beaker, stir until the ammonium citrate and dodecyltrimethylammonium hydrogensulfate are completely dissolved, and then slowly add 0.8 g of citric acid to the beaker under the conditions of 60 °C and stirring (the addition rate of citric acid in this comparative example is the same as that in Example 1). After the addition of citric acid is completed, continue stirring for 60 min. After the stirring is completed, it is observed that the color change of the liquid in the beaker is not significant. Then, filter and remove impurities from the mixture in the beaker, and then evaporate and dry the filtered liquid to remove the solvent, obtaining the iron remover.

[0027] Comparative Example 2

[0028] The iron remover of this comparative example is prepared by a method including the following steps: Add ammonium malonate with a mass of 10 g, dodecyl trimethyl ammonium hydrogensulfate with a mass of 41 g, and distilled water with a mass of 248 g into a 500 mL beaker, stir until ammonium malonate and dodecyl trimethyl ammonium hydrogensulfate are completely dissolved, and then perform ultrasonic treatment (ultrasonic power is 90 W·cm -2 , ultrasonic frequency is 40 kHz) under the condition that the ultrasonic temperature is 60 °C. Meanwhile, slowly add 8 g of citric acid. After the addition of citric acid is completed, continue ultrasonic treatment for 60 min to enable the mixture in the beaker to carry out a mixing reaction. After the mixing reaction ends, it is observed that the liquid in the beaker is light yellow. Then, filter and remove impurities from the mixture in the beaker, and then evaporate and dry the filtered liquid to remove the solvent to obtain the iron remover.

[0029] Comparative Example 3

[0030] The iron remover of this comparative example is prepared by a method including the following steps: Add sodium citrate with a mass of 10 g, dodecyl trimethyl ammonium hydrogensulfate with a mass of 41 g, and distilled water with a mass of 248 g into a 500 mL beaker, stir until sodium citrate and dodecyl trimethyl ammonium hydrogensulfate are completely dissolved, and then perform ultrasonic treatment (ultrasonic power is 90 W·cm -2 , ultrasonic frequency is 40 kHz) under the condition that the ultrasonic temperature is 60 °C. Meanwhile, slowly add 8 g of citric acid. After the addition of citric acid is completed, continue ultrasonic treatment for 60 min to enable the mixture in the beaker to carry out a mixing reaction. After the mixing reaction ends, it is observed that the liquid in the beaker is light yellow. Then, filter and remove impurities from the mixture in the beaker, and then evaporate and dry the filtered liquid to remove the solvent to obtain the iron remover.

[0031] Comparative Example 4

[0032] The iron remover of this comparative example is prepared by a method including the following steps: Add ammonium citrate with a mass of 10 g, dodecyl trimethyl ammonium chloride with a mass of 41 g, and distilled water with a mass of 248 g into a 500 mL beaker, stir until ammonium citrate and dodecyl trimethyl ammonium chloride are completely dissolved, and then perform ultrasonic treatment (ultrasonic power is 90 W·cm -2 , ultrasonic frequency is 40 kHz) under the condition that the ultrasonic temperature is 60 °C. Meanwhile, slowly add 8 g of citric acid. After the addition of citric acid is completed, continue ultrasonic treatment for 60 min to enable the mixture in the beaker to carry out a mixing reaction. After the mixing reaction ends, it is observed that the color of the liquid in the beaker changes little. Then, filter and remove impurities from the mixture in the beaker, and then evaporate and dry the filtered liquid to remove the solvent to obtain the iron remover.

[0033] Comparative Example 5

[0034] The iron remover of this comparative example was prepared by a method including the following steps: Add 10 g of ammonium citrate, 41 g of dodecyltrimethylammonium hydrogensulfate, and 248 g of distilled water into a 500 mL beaker, stir until ammonium citrate and dodecyltrimethylammonium hydrogensulfate are completely dissolved, and then perform ultrasonic treatment (ultrasonic power is 90 W·cm -2 , ultrasonic frequency is 40 kHz) under the condition that the ultrasonic temperature is 60 °C. Meanwhile, slowly add 8 g of malonic acid. After the addition of malonic acid is completed, continue ultrasonic treatment for 60 min to make the mixture in the beaker undergo a mixing reaction. After the mixing reaction ends, it is observed that the liquid in the beaker is light yellow. Then, filter and remove impurities from the mixture in the beaker, and then evaporate and dry the filtered liquid to remove the solvent to obtain the iron remover.

[0035] Comparative Example 6

[0036] The iron remover of this comparative example was prepared by a method including the following steps: Add 10 g of ammonium citrate, 41 g of dodecyltrimethylammonium hydrogensulfate, and 248 g of distilled water into a 500 mL beaker, stir until ammonium citrate and dodecyltrimethylammonium hydrogensulfate are completely dissolved, and then perform ultrasonic treatment (ultrasonic power is 90 W·cm -2 , ultrasonic frequency is 40 kHz) under the condition that the ultrasonic temperature is 25 °C. Meanwhile, slowly add 8 g of citric acid. After the addition of citric acid is completed, continue ultrasonic treatment for 60 min to make the mixture in the beaker undergo a mixing reaction. After the mixing reaction ends, it is observed that the color change of the liquid in the beaker is not significant. Then, filter and remove impurities from the mixture in the beaker, and then evaporate and dry the filtered liquid to remove the solvent to obtain the iron remover.

[0037] Comparative Example 7

[0038] The iron remover of this comparative example was prepared by a method including the following steps: Mix 10 g of ammonium citrate, 41 g of dodecyltrimethylammonium hydrogensulfate, and 0.8 g of citric acid evenly to obtain the iron remover.

[0039] Experimental Example

[0040] In order to evaluate the iron removal effect of the iron removers of Examples 1 - 9 and Comparative Examples 1 - 7, heat 200 g of crude oil to e °C, keep it warm for f min, and then add a certain amount of clear water, demulsifier, and iron remover (the masses of clear water, demulsifier, and iron remover are r, s, and t of the mass of the crude oil in sequence) into the crude oil. Then, stir at e °C for p min, and then perform electro - desalting on the stirred system (the function of electro - desalting is to remove the water - soluble iron generated after the action of the iron remover with water to achieve the purpose of iron removal and iron reduction). Then, perform oil - water separation, and then test the iron content in the oil phase obtained from the oil - water separation. Finally, calculate the iron removal rate.

[0041] The iron content in the crude oil used in this experimental example is 80.25 mg / kg. The iron content before and after electro - desalting of the crude oil is determined according to the provisions in the standard "GB / T 118608 - 2012 Determination of Nickel, Vanadium, Iron and Sodium Contents in Crude Oil and Residual Oil - Flame Atomic Absorption Spectrometry". After measuring and calculating the iron content in the crude oil and the iron - removed crude oil, the iron - removal rate of the crude oil can be calculated. The calculation formula is: iron - removal rate of crude oil w = [(X0 - X1) / X0]×100, where w is the iron - removal rate of the crude oil, X0 is the iron content in the crude oil, with the unit of mg / kg, and X1 is the iron content in the iron - removed crude oil, with the unit of mg / kg.

[0042] When using the iron - removing agents of Examples 1 - 9 and Comparative Examples 1 - 7 for iron removal, the heating temperature and time of the crude oil, the amounts of fresh water, demulsifier and iron - removing agent, and the iron - removal rate (iron - removal rate of crude oil) of each iron - removing agent are shown in Table 2.

[0043] Table 2 Heating temperature and time of the crude oil, amounts of fresh water, demulsifier and iron - removing agent, and iron - removal rate of each iron - removing agent when using the iron - removing agents of Examples 1 - 9 and Comparative Examples 1 - 7 for iron removal

[0044]

[0045]

Claims

1. An iron remover for crude oil, characterized in that Prepared by a method comprising the following steps: mixing ammonium citrate, alkyltrimethylammonium hydrogensulfate and citric acid in water at 50°C to 80°C; the mass ratio of ammonium citrate, alkyltrimethylammonium hydrogensulfate and citric acid is 1:(4.1 - 5):(0.8 - 1); the mixing reaction is carried out under ultrasonic conditions.

2. The crude oil iron remover according to claim 1, characterized in that, The power of the ultrasound is 90 to 150 W·cm -2 .

3. The crude oil iron remover according to claim 1, characterized in that, The frequency of the ultrasonic wave is 20 - 50 kHz.

4. The crude oil iron remover according to any one of claims 1-3, characterized in that, The time of the mixing reaction is not less than 60 min.

5. The crude oil iron remover according to claim 4, wherein, The time of the mixing reaction is 60 - 90 min.

6. The crude oil iron remover according to any one of claims 1-3, characterized in that, The alkyltrimethylammonium hydrogensulfate is selected from one or any combination of dodecyltrimethylammonium hydrogensulfate, tridecyltrimethylammonium hydrogensulfate, tetradecyltrimethylammonium hydrogensulfate, pentadecyltrimethylammonium hydrogensulfate, hexadecyltrimethylammonium hydrogensulfate.

7. The crude oil iron remover according to any one of claims 1-3, characterized in that After the mixing reaction is completed, the system after the mixing reaction is subjected to solid-liquid separation, and then the solvent in the liquid obtained by the solid-liquid separation is removed to obtain an iron remover.

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