Oil product improving method based on modified blast furnace slag catalytic pyrolysis oil-rich coal

Abstract

The invention provides an oil product improving method based on catalytic pyrolysis of oil-rich coal from modified blast furnace slag, and belongs to the technical field of quality improvement of oil-rich kerosene. Aiming at the problems of low coal pyrolysis tar yield, high heavy fraction content and the like in the prior art, the method comprises the following steps: 1) modifying original blast furnace slag through an oxide; 2) mixing the modified blast furnace slag with oil-rich coal in proportion, performing catalytic pyrolysis, and collecting coal tar subjected to catalytic pyrolysis; 3) extracting and analyzing each fraction component in the coal tar; and 4) obtaining the yield and parameter conditions of the light tar. According to the method, CaO is the optimal modified oxide of the blast furnace slag through a single factor analysis method, meanwhile, it is verified that 15.12% of coal tar can be generated through catalytic pyrolysis of the oil-rich coal with the CaO modified blast furnace slag with the content of 5%, the carbolic oil content in the coal tar reaches 97.72%, and the promotion effect on oil product improvement of the oil-rich coal is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of improving the quality of oil-rich kerosene, and in particular to an oil quality improving method based on catalytic pyrolysis of oil-rich coal by modified blast furnace slag. Background Art

[0002] As a fossil fuel, coal has a relatively high carbon content and occupies an important position in my country's resources and energy. The rational use of coal should not only take into account the current energy situation, but also fully consider the chemical composition and structural characteristics of coal, and develop clean and efficient cascade conversion technology for coal based on this. Coal pyrolysis, as one of the most promising sustainable energy technologies, can produce liquid fuels, highly active semi-coke, valuable chemicals and high calorific value natural gas through mild coal conversion technology.

[0003] Coal pyrolysis refers to heating coal to a high temperature in an air-tight condition so that chemical bonds break, products recombine and react again in the process, and finally generate gaseous component coal gas, liquid component coal tar and solid component semi-coke, etc. Coal pyrolysis is considered to be one of the most important technologies for producing valuable gaseous and liquid fuels, but due to the low H / C molar ratio of coal, the tar yield of coal pyrolysis is low, and the content of heavy fractions with a boiling point above 360°C in coal tar is usually higher than 50% of the total tar. This heavy tar with high viscosity, easy pollution and low economic value will not only reduce the quality of tar, making it difficult to use, but also easily cause subsequent pipeline blockage and affect the stable operation of the pyrolysis system, limiting its application in actual industry. Therefore, it is necessary to develop advanced coal pyrolysis quality improvement technology to improve tar yield and quality.

[0004] At present, the research on catalytic pyrolysis of coal is one of the main development trends in the field of coal pyrolysis to improve the quality of oil and gas. It refers to adding catalysts during the pyrolysis of coal, using the selective promotion or inhibition of pyrolysis free radicals and the interaction between molecules to improve the pyrolysis conversion rate of coal, change the distribution of pyrolysis products, and realize the directional conversion of coal to target products. Alkali metals and alkaline earth metals, supported and semi-coke-based catalysts are catalysts commonly used in the pyrolysis of coal, and alkali metal and alkaline earth metal catalysts are a more ideal catalyst for pyrolysis and quality improvement of coal. Studies have shown that alkali metals / alkaline earth metals can combine with carboxyl and hydroxyl groups in coal molecules during pyrolysis to form crosslinking points to make the coal structure more compact, thereby preventing the escape of macromolecules in tar, allowing more tar macromolecules to undergo polycondensation reactions to form semi-coke. In addition, the acceleration of the pyrolysis reaction rate increases the cracking rate of oxygen-containing functional groups, greatly increases the yield of gas products, and can also reduce the content of sulfur and oxygen in liquid products.

[0005] Blast furnace slag is an industrial waste residue formed by the combination of iron ore impurities and added fluxes in a high-temperature molten state, mainly composed of calcium aluminosilicate. Inspired by the catalytic pyrolysis of coal by the above alkali metals and alkaline earth metals, through the analysis of the composition of blast furnace slag, it is found that metal oxides account for more than 80%. Therefore, a method for improving the quality of oil and gas by using some components of blast furnace slag to replace the above alkali metal catalysis is studied and developed, and the product distribution is verified and analyzed by catalytic pyrolysis of rich oil coal, providing effective theoretical support for the low-temperature pyrolysis and directional conversion technology of rich oil coal. Summary of the Invention

[0006] Aiming at the problems existing in the above-mentioned existing technologies, the purpose of the present invention is to propose a method for catalytic pyrolysis based on modified blast furnace slag combined with rich oil coal. Through the single-factor analysis method, the oxide with a high tar yield and a high content of light tar components in the catalytic pyrolysis is used as the target modifier, and further research is carried out on the dosage of the target modifier to form a method for increasing the yield of light tar in rich oil coal and directional conversion, thereby achieving the purpose of improving the quality of oil.

[0007] The present invention realizes the above technical purpose by adopting the following technical solutions:

[0008] A method for improving the quality of oil products by catalytic pyrolysis of rich oil coal based on modified blast furnace slag includes at least the following steps:

[0009] S1: Modify the original blast furnace slag with oxide X m O n to form modified blast furnace slag;

[0010] S2: Mix the modified blast furnace slag and rich oil coal in proportion and carry out catalytic pyrolysis, and collect the coal tar after catalytic pyrolysis.

[0011] As a further preferred solution of the above solution of the present invention, in step S1, X m O n is any one of CaO, MgO, Al2O3, SiO2 and Fe2O3.

[0012] A further preferred solution of the above solution is: X m O n is CaO. Mix CaO and the original blast furnace slag evenly to obtain modified blast furnace slag.

[0013] As a further preferred solution of the above solution of the present invention, the addition amount of CaO is 1wt% - 9wt%.

[0014] A further preferred solution of the above solution is: the addition amount of CaO is 5wt%.

[0015] As a further preferred solution of the above solution of the present invention, in step S2, the mixing ratio of the modified blast furnace slag to the oil-rich coal is 1:10 to 40.

[0016] Furthermore, the mixing ratio of the modified blast furnace slag to the oil-rich coal is 1:20.

[0017] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0018] 1. Based on the inherent catalytic performance of blast furnace slag rich in metal oxides, the present invention selects several oxides with relatively high contents among them to modify the original blast furnace slag. After mixing the modified blast furnace slag with the oil-rich coal for catalytic pyrolysis and analyzing the fraction components therein, an oxide that has the best effect on improving the yield of coal tar and the content of light components is verified, and the content of the modified oxide is further determined, thereby improving the oil quality of the oil-rich coal.

[0019] 2. The method of the present invention uses CaO-modified blast furnace slag as the best modified catalyst, which can not only improve the yield of coal tar from the pyrolysis of oil-rich coal, but also help to increase the content of light oil products (such as light oil, phenol oil, naphthalene oil, wash oil, anthracene oil) in the coal tar. The results show that using 5% content of CaO-modified blast furnace slag to catalytically pyrolyze oil-rich coal can produce 15.12% of coal tar, and the phenol oil content in this coal tar reaches 97.72%, which plays a promoting role in improving the oil quality of the oil-rich coal.

[0020] 3. Using CaO as the coal pyrolysis modified catalyst for oil-rich coal, at high temperature, CaO directly reacts chemically with the pyrolysis gas CO2, which can reduce CO2 emissions and effectively reduce the pollution caused by CO2 to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0022] Figure 1 It is the process flow chart of the method for improving the oil quality of catalytic pyrolysis of oil-rich coal based on modified blast furnace slag of the present invention;

[0023] Figure 2 It is the gas chromatogram of the tar fraction of catalytic pyrolysis of oil-rich coal with blast furnace slag modified by different oxides of the present invention;

[0024] Figure 3Effect of different oxide - modified blast furnace slag of the present invention on tar yield in catalytic pyrolysis of oil - rich coal

[0025] Figure 4 Content distribution of tar fractions in catalytic pyrolysis of oil - rich coal by different oxide - modified blast furnace slag of the present invention

[0026] Figure 5 Gas chromatography of tar fractions in catalytic pyrolysis of oil - rich coal by blast furnace slag modified with different contents of CaO of the present invention

[0027] Figure 6 Effect of blast furnace slag modified with different contents of CaO of the present invention on tar yield in catalytic pyrolysis of oil - rich coal

[0028] Figure 7 Content distribution of tar fractions in catalytic pyrolysis of oil - rich coal by blast furnace slag modified with different contents of CaO of the present invention Detailed implementation manners

[0029] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0030] Refer to Figures 1-7 , and an oil upgrading method for catalytic pyrolysis of oil - rich coal based on modified blast furnace slag includes the following steps:

[0031] S1: Modify the original blast furnace slag with oxide X m O n to form modified blast furnace slag;

[0032] In step S1, X m O n is any one of CaO, MgO, Al2O3, SiO2 and Fe2O3.

[0033] Preferably: X m O n is CaO, and the addition amount of CaO is 1wt% - 9wt%. Mix CaO evenly with the original blast furnace slag to obtain the modified blast furnace slag.

[0034] Preferably: the addition amount of CaO is 5wt%.

[0035] S2: Mix the modified blast furnace slag and oil - rich coal in a ratio of 1:20 and then carry out catalytic pyrolysis, and collect the coal tar after catalytic pyrolysis.

[0036] The method of the present invention generally includes two stages: selecting a modified oxide and further quantifying the selected oxide. The first stage: using a variety of different oxides X with the same content m O n , respectively modify the original blast furnace slag, carry out catalytic pyrolysis of rich oil coal according to the above steps S1 - S4, and analyze the tar yield and fraction distribution; The second stage: based on the results of the first stage, among a variety of different oxides X m O n , select one of the oxides Y m O n , and use Y m O n to modify the original blast furnace slag, and again carry out catalytic pyrolysis of rich oil coal according to the above steps S1 - S4, analyze the tar yield and fraction distribution, so as to form a method that helps to improve the oil products of rich oil coal.

[0037] Before that, the composition detection and analysis of the target substance to be used (i.e., the original blast furnace slag) was carried out first. The original blast furnace slag used was the powder after granulated blast furnace slag was ground by vertical mill, and the results are shown in Table 1 and Table 2 below.

[0038] Table 1 Main chemical components of blast furnace slag powder (%)

[0039]

[0040] Table 2 Main element composition of blast furnace slag powder (%)

[0041]

[0042]

[0043] As can be seen from Table 1, the main components of the blast furnace slag powder used in the present invention are CaO, SiO2, Al2O3, Fe2O3 and MgO. In addition, it contains oxides such as TiO2 and MnO. And through research, it is known that the blast furnace slag rich in metal oxides has catalytic performance and also has a promoting effect in the co-pyrolysis with rich oil coal; the rich oil coal used is a low-rank coal sample, taken from the Zhangjiamao mining area in Shenmu County, Yulin City, northern Shaanxi. The coal sample of rich oil coal was collected from a fresh coal mining face, and the rich oil coal was crushed and then dried in an oven at 60 °C for standby.

[0044] 1) Determine an oxide Y m O n from a variety of different oxides X m O n ;

[0045] In the present invention, five oxides, namely CaO, MgO, Al2O3, SiO2 and Fe2O3, are respectively selected to modify the original blast furnace slag, and the modified blast furnace slag is used for low-temperature catalytic pyrolysis of rich oil coal.

[0046] Specifically, the device used in the present invention is as Figure 1 shown. CaO, MgO, Al2O3, SiO2 and Fe2O3 are separately added to the original blast furnace slag to form five groups of modified blast furnace slag. Among them, the contents of CaO, MgO, Al2O3, SiO2 and Fe2O3 are all 7 wt%. After the five groups of modified blast furnace slag are mechanically mixed with rich oil coal in a ratio of 1:20 and evenly mixed, they are placed in a fixed bed reactor ( Figure 1 in the pyrolysis furnace), and catalytic pyrolysis is carried out at 550 °C. The tar after pyrolysis is collected using acetone, and then the tar is extracted by a rotary evaporator. The extracted tar is analyzed for light oil components and heavy oil components using a gas chromatograph instrument;

[0047] In the present invention, the detection of tar mainly uses the simulated distillation method to analyze the distribution of each fraction in the tar, which is carried out on a simulated distillation chromatograph. The principle is as follows: a non-polar chromatographic column with a certain separation degree is used, and the retention time of the components of a known mixture is tested under linear programmed temperature conditions. Then, under the same chromatographic conditions, the components are separated in turn according to the boiling point of the components and sliced and integrated to obtain the corresponding cumulative area and the corresponding residence time. After interpolation correction of temperature-time, the temperature corresponding to the percentage yield (i.e., the distillation range) is obtained, where: the percentage of the cumulative area is the yield.

[0048] As Figure 2 shown, according to the different peak emergence times of the tar fractions in the chromatograph, after area normalization treatment, the oils in the tar are divided into 6 categories: light oil, phenol oil, naphthalene oil, wash oil, anthracene oil and pitch by simulated distillation. After catalytic pyrolysis of rich oil coal, the tar fractions produced have changed, the content of heavy components in the tar has decreased significantly, and the oil product has changed from the original multi-fraction to a relatively concentrated phenol oil fraction.

[0049] At the same time, it can be seen that after catalytic pyrolysis of rich oil coal with blast furnace slag modified by different oxides with the same content, different effects on the tar yield are produced. Referring to Figures 3-4 it can be seen that the tar yields produced by catalytic pyrolysis of rich oil coal using blast furnace slag modified by CaO, MgO, Al2O3, SiO2 and Fe2O3 are 14.92%, 14.73%, 12.34%, 13.21% and 14.68% in turn; overall, the blast furnace slag modified by basic oxides (CaO, MgO) has a higher oil production yield for catalytic pyrolysis of rich oil coal than that modified by acidic oxides (Al2O3, SiO2), and among the amphoteric oxides, the catalytic performance of Fe2O3@GGBS is better than that of acidic oxides (SiO2). CombiningFigure 4 It can be seen that the reason for the good catalytic cracking effect of blast furnace slag modified by basic oxides on tar fractions is that asphalt is cracked into light components of phenol oil; relatively speaking, the catalytic ability of Al2O3@GGBS among acidic oxides is weak, and asphalt is not completely cracked into phenol oil, and the content of anthracene oil in it is higher than that of anthracene oil in the catalytic pyrolysis modified by other oxides. The catalytic performance of acidic oxide SiO2 is limited (but better than Al2O3@GGBS). Although it can reduce the asphalt content, it will not convert asphalt into specific fractions. Iron-based catalysts can increase the tar yield and reduce the molecular weight of tar, and Fe2O3@GGBS reduces the asphalt content in catalytic pyrolysis, and produces naphthalene oil while generating phenol oil.

[0050] 2) Determine the oxide Y m O n Optimal modification content;

[0051] From the results obtained above, since CaO has a high efficiency in the directional conversion of phenol oil, CaO is determined as the oxide with the best modification effect on blast furnace slag. Further, blast furnace slag is modified with metal oxide CaO with different contents, and then the content with the best catalytic pyrolysis effect on rich oil coal is studied.

[0052] The original blast furnace slag is modified with metal oxide CaO of 1wt%, 3wt%, 5wt%, 7wt% and 9wt% respectively. As Figure 5 shown, the main influence of different contents of CaO on the pyrolysis tar fractions lies in the obvious reduction of heavy components, the directional generation of phenol oil fractions, and the highest content of phenol oil fractions produced by 5% CaO@GGBS catalytic pyrolysis of rich oil coal (the outflow times of different fractions from gas chromatography are different, and the phenol oil fractions are mainly concentrated in the 2 - 6 min outflow), and the components are more concentrated, mainly manifested as a single peak in the chromatogram, while the phenol oil fractions of 3% CaO@GGBS and 7% CaO@GGBS contain different peaks, that is, there are multiple substances, and the heavy components are not obvious in Figure 5 due to the low content and wide fraction. It can be seen that the addition of metal oxide CaO catalyzes rich oil coal to achieve the directional regulation of tar and improves the quality of coal tar.

[0053] Refer to Figure 6 It can be seen that the oil yields of CaO@GGBS with contents of 1%, 3%, 5%, 7%, 9% for the catalytic pyrolysis of rich oil coal are 14.98%, 15.03%, 15.12%, 14.92%, 14.84% in turn. Combining Figure 7It can be seen that within the range of 1% - 5% CaO content, the degree of lightening of tar increases with the increase of CaO content. At the same time, the output of asphalt decreases significantly, while the content of phenol oil increases from 90.38% to 97.72%. This is because the addition of CaO can reduce the activation energy of the tar cracking reaction and improve the degree of lightening. Within the range of 5% - 9%, the degree of lightening of tar decreases from 97.72% to 85.89%. Although the content of heavy components in tar under the action of 9% CaO@GGBS is low, the presence of naphthalene oil reduces the content of phenol oil.

[0054] It can be seen from this that the present invention determines the optimal modified metal oxide and its content according to the above method. The results show that not only can the yield of pyrolysis coal tar from rich-oil coal be increased by modifying blast furnace slag with CaO, but also the content of light oil product phenol oil in it can be increased. Modifying blast furnace slag to catalytically pyrolyze rich-oil coal can increase the tar yield. The results show that catalytically pyrolyzing rich-oil coal with blast furnace slag modified by 5% CaO can produce 15.12% of coal tar, and the content of phenol oil in this coal tar reaches 97.72%. Thus, it can be proved that the method of the present invention has a further improvement effect on the oil quality of rich-oil coal.

[0055] In addition, using CaO as the catalyst for modifying blast furnace slag, through the chemical reaction between CaO and the pyrolysis gas CO2, specifically: CaO and CO2 can directly react at high temperature to form CaO + CO2 = CaCO3. In a humid environment (coal pyrolysis will produce water), CaO + H2O = Ca(OH)2 will occur, and Ca(OH)2 + CO2 = CaCO3 + H2O. Under these two reactions, the CO2 emissions can be consumed and reduced, and the environmental pollution caused can be reduced.

[0056] The detailed description of the embodiments of the present invention provided above is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, it is only used to illustrate the technical solutions of the present invention and not to limit. Other modifications or equivalent replacements made by those of ordinary skill in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for improving the quality of oil products by catalytic pyrolysis of oil-rich coal based on modified blast furnace slag, characterized in that, At least include the following steps: S1: Through oxide X m O n Modifying the original blast furnace slag to form modified blast furnace slag; S2: Mix the modified blast furnace slag and the oil-rich coal in proportion and then carry out catalytic pyrolysis, and collect the coal tar after catalytic pyrolysis.

2. The method for improving the quality of oil products by catalytic pyrolysis of oil-rich coal based on modified blast furnace slag according to claim 1, wherein, In step S1, X m O n is any one of CaO, MgO, Al2O3, SiO2, and Fe2O3.

3. The method for improving the quality of oil products by catalytic pyrolysis of oil-rich coal based on modified blast furnace slag according to claim 2, wherein, X m O n is CaO. Mix CaO evenly with the original blast furnace slag to obtain the modified blast furnace slag.

4. The method for improving the quality of oil products by catalytic pyrolysis of oil-rich coal based on modified blast furnace slag according to claim 3, wherein The addition amount of CaO is 1wt% - 9wt%.

5. The method for enhancing the quality of oil products by catalytic pyrolysis of oil-rich coal based on modified blast furnace slag according to claim 4, characterized in that, The addition amount of CaO is 5wt%.

6. The method for enhancing the quality of oil products by catalytic pyrolysis of oil-rich coal based on modified blast furnace slag according to claim 5, wherein In step S2, the mixing ratio of the modified blast furnace slag to the oil-rich coal is 1:10 - 40.

7. The method for improving the quality of oil products from catalytic pyrolysis of oil-rich coal based on modified blast furnace slag according to claim 6, wherein The mixing ratio of the modified blast furnace slag to the oil-rich coal is 1:20.

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