Preparation method of direct coal liquefaction coal-oil slurry and prepared coal-oil slurry

Abstract

The invention discloses a preparation method of direct coal liquefaction coal-oil slurry and the prepared coal-oil slurry, and relates to the technical field of coal chemical industry. The technical problems that in the prior art, reactivity is insufficient in the preparation process of oil-coal slurry, and the viscosity of the oil-coal slurry cannot be reduced while the concentration of pulverized coal is increased are solved. The method comprises the following steps: firstly, crushing coal into pulverized coal particles with a certain particle size; determining a proper separation density set through a floating and sinking test; then separating the pulverized coal particles through a dense medium cyclone to obtain an inert component enriched product and an active component enriched product; carrying out secondary fine crushing on the inert component enrichment; carrying out particle size grading on a part of fine-particle pulverized coal subjected to secondary fine crushing and the active component enriched product; and finally, mixing the pulverized coal subjected to grain size distribution with a catalyst and a solvent to prepare slurry, so as to obtain the coal-oil slurry. While the concentration of the coal-oil slurry is improved, the stability of the coal-oil slurry is maintained, the viscosity of the coal-oil slurry is regulated and controlled, and the reaction performance and the liquefied oil yield are improved.

Description

Technical Field

[0001] The invention relates to the technical field of coal chemical industry, and in particular to a method for preparing oil-coal slurry of direct coal liquefaction and the prepared oil-coal slurry. Background Art

[0002] The main process unit of direct coal liquefaction includes four units: coal slurry preparation unit, reaction unit, separation unit and hydrogenation upgrading unit. Among them, the coal slurry preparation unit is the starting unit in the direct coal liquefaction process. Its main purpose is to mix coal powder, catalyst and solvent to obtain oil-coal slurry with stable properties and easy to transport. The slurry performance of oil-coal slurry is a key indicator that determines the coal conversion rate and light oil yield. On the one hand, the smaller the coal powder particles, the stronger the stability, but the higher the viscosity, and the higher the coal grinding input cost; while the larger the coal powder particle size, the lower the viscosity of the oil-coal slurry, but the worse the stability, and the easier it is to settle. On the other hand, increasing the concentration of oil-coal slurry can improve the processing capacity per unit reaction volume and increase the liquefied oil production within a certain range, but if the concentration is too high, the viscosity of the oil-coal slurry will increase, which will lead to transportation difficulties; at the same time, from the perspective of coal liquefaction reaction, if the concentration is too high and the solvent is insufficient to supply hydrogen, it is also easy to cause free radical polycondensation problems, thereby reducing the oil yield.

[0003] At present, the research reports on the preparation of oil-coal slurry in the prior art include: Application No. 201810667270.6 discloses a method for preparing oil-coal slurry, which can reduce the viscosity of oil-coal slurry while increasing the concentration of coal powder, but this method is still insufficient in improving the reactivity of oil-coal slurry. Application No. 201910407326.9 discloses a method for preparing highly matched oil-coal slurry, which can avoid the stratification of coal and heavy oil in the oil-coal slurry and cause the oil-coal slurry to be deposited in the preheater or reactor, thereby improving the conversion rate of coal and heavy oil and the oil yield. This method requires that the anhydrous and ash-free volatile matter of coal is ≥37%, and the coal powder particle size is ≤150μm. It has high requirements on the properties of the raw materials, and the cost of preparing coal powder is high. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for preparing oil-coal slurry for direct coal liquefaction, which aims to solve the deficiencies of the above-mentioned prior art. The present invention increases the concentration of the oil-coal slurry while maintaining the stability of the oil-coal slurry, regulating the viscosity of the oil-coal slurry, and improving the reaction performance and the yield of liquefied oil.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing coal direct liquefaction oil-coal slurry comprises the following steps in sequence:

[0007] (1) The pulverized coal is crushed into pulverized coal particles of a certain size by a primary crushing process;

[0008] (2) determining the appropriate separation density range of the coal powder particles through a floating and sinking test;

[0009] (3) according to the separation density set range obtained in step (2), the pulverized coal particles are separated by a heavy medium cyclone to obtain an inert component enriched product and an active component enriched product; the active component content in the inert component enriched product is ≤50%, and the active component content in the active component enriched product is ≥40%;

[0010] (4) performing secondary fine crushing on the inert component enriched product to obtain fine coal powder with a certain particle size;

[0011] (5) performing particle size grading on a portion of the fine coal powder obtained in step (4) and the active component enriched material to obtain particle size graded coal powder;

[0012] (6) A portion of the fine coal powder obtained in step (4) is used as a carrier for catalyst preparation, and the carrier is mixed with a catalyst formed by an active metal, a solvent and coal powder after particle size distribution to obtain an oil-coal slurry.

[0013] In the above-mentioned method for preparing coal direct liquefaction oil-coal slurry, in step (1), the particle size of the coal powder particles is 0-500 μm, and the coal powder is crushed in the first stage by a hammer crusher, a jaw crusher, a cone crusher or a double-roll crusher.

[0014] In the above-mentioned method for preparing coal direct liquefaction oil-coal slurry, in step (2), a floating and sinking test is performed on the coal powder particles using zinc chloride heavy liquid, and the separation density set range is 1300-1800 kg / m 3 .

[0015] In the above-mentioned method for preparing coal-to-oil slurry by direct coal liquefaction, in step (3), the diameter of the heavy medium cyclone is ≤700 mm, the inlet diameter of the heavy medium cyclone is 50-200 mm, and the outlet diameter of the heavy medium cyclone is 100-300 mm.

[0016] In the above-mentioned method for preparing oil-coal slurry from direct coal liquefaction, in step (4), the secondary fine crushing adopts a ball mill or a rod mill, and the particle size of the fine coal powder is 0 to 150 μm.

[0017] In the above-mentioned method for preparing oil-coal slurry from direct coal liquefaction, in step (5), the mass ratio of fine coal powder to active component concentrate is 1 to 5:1.

[0018] In the above-mentioned method for preparing coal direct liquefaction oil-coal slurry, in step (6), the mass ratio of the fine-grained coal powder used as a carrier to the fine-grained coal powder described in step (4) is 10-50%; and the active metal is a composite of one or more of iron, molybdenum, nickel, cobalt, and tungsten metals.

[0019] In the above-mentioned method for preparing oil-coal slurry from direct coal liquefaction, in step (6), the solvent refers to the circulating solvent produced by the self-circulation during the direct liquefaction process, the solvent is petroleum-based heavy oil or coal tar, and the concentration of the oil-coal slurry is 30-60%.

[0020] The above-mentioned method for preparing coal direct liquefaction oil-coal slurry is characterized in that the particle size of the coal powder particles is 0-300 μm, and the separation density is in the range of 1300-1550 kg / m 3 The particle size of fine coal powder is 0 to 75 μm.

[0021] Another object of the present invention is to provide an oil-coal slurry, which is prepared by the above-mentioned method for preparing an oil-coal slurry for direct coal liquefaction.

[0022] Compared with the prior art, the present invention brings the following beneficial technical effects:

[0023] (1) The method of the present invention effectively increases the concentration of coal powder and improves the processing capacity of oil-coal slurry per unit volume without increasing the viscosity of coal powder.

[0024] (2) The method of the present invention can improve the liquefaction reactivity of raw coal, especially for coal with high inert group content, the effect is more significant.

[0025] (3) The method of the present invention uses fine-particle coal powder after secondary fine crushing as a catalyst carrier, which can improve the dispersion performance of the catalyst. At the same time, using an inert component enriched material with relatively poor activity as a catalyst carrier can enable the inert component enriched material to better contact with the catalyst, promote the conversion of the raw coal, and make the catalyst more targeted.

[0026] (4) The present invention has good applicability and can prepare oil-coal slurry with stable properties and good fluidity using raw coal of different coal quality conditions and solvent oil from different sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings:

[0028] Figure 1 The present invention is a process flow chart for preparing coal-oil slurry by direct coal liquefaction. DETAILED DESCRIPTION

[0029] The present invention provides a method for preparing coal direct liquefaction oil-coal slurry and the prepared oil-coal slurry. In order to make the advantages and technical solutions of the present invention clearer and more specific, the present invention is further described below in conjunction with specific embodiments.

[0030] The raw materials described in the present invention can be purchased through commercial channels.

[0031] The technical solution of the present application is further described in detail below in conjunction with the accompanying drawings.

[0032] like Figure 1 As shown, the present invention provides a method for preparing coal-oil slurry by direct coal liquefaction, which specifically comprises the following steps:

[0033] Step 1: The coal powder is crushed to obtain coal powder particles with a particle size of 0 to 500 μm, preferably 0 to 300 μm. The crushing process can use a hammer crusher, jaw crusher, cone crusher or roller crusher.

[0034] Step 2: Use zinc chloride heavy liquid to conduct floating and sinking tests on coal powder. The test obtains a suitable separation density set range. The floating and sinking sequence gradually progresses from low density set to high density set. The separation density set range obtained is 1300~1800kg / m 3 The preferred separation density range is 1300~1550kg / m 3 The difference between different separation density sets is generally 100kg / m 3 It can also be flexibly adjusted to 80kg / m according to the raw coal conditions. 3 , 50kg / m 3 wait.

[0035] Step 3: According to the preferred separation density set range, the pulverized coal is separated by a heavy medium cyclone, the diameter of the heavy medium cyclone is generally not more than 700 mm, the inlet diameter of the heavy medium cyclone is 50-200 mm, and the outlet diameter of the heavy medium cyclone is 100-300 mm, to obtain an inert component enriched product and an active component enriched product, the active component content in the inert component enriched product is ≤50%, and the active component content in the active component enriched product is ≥40%.

[0036] Step 4: The inert component enrichment is subjected to secondary fine crushing to obtain fine coal powder with a certain particle size. The fine crushing process uses a ball mill or a rod mill, etc. The grinding medium is generally made of stainless steel, and aluminum oxide, silicate, zirconium oxide, etc. can also be used. The medium in the wet grinding process can be water, ethanol, kerosene, glycerol, ethylene glycol, acetone, hexane or benzene, etc. The particle size of the fine coal powder obtained is 0-150μm, preferably 0-75μm.

[0037] Step 5: a portion of the fine coal powder and the active component enriched product obtained by the heavy medium cyclone are subjected to particle size grading, and the particle size grading ratio is 1 to 5: 1, and the preferred ratio range is 1.2 to 3.5: 1. The particle size grading ratio can be adjusted by the results of the floating and sinking test to adjust the ratio of the active component enriched product and the inert component enriched product of the heavy medium cyclone.

[0038] Step 6: Use a portion of fine coal powder as a carrier for catalyst preparation, the fine coal powder as a carrier accounts for 10-50% of the mass of the fine coal powder obtained after the secondary fine crushing, and the catalyst active metal is a composite of one or more metals such as iron, molybdenum, nickel, cobalt, and tungsten. The fine coal powder after the secondary fine crushing can be immersed in a catalyst solution to allow the catalyst to enter the pores and surface of the fine coal powder after the secondary fine crushing, or the catalyst particles can be precipitated on the surface of the fine coal powder after the secondary fine crushing, or the fine coal powder after the secondary fine crushing can be immersed in a catalyst solution, and then the catalyst is further fixed by precipitation reaction.

[0039] The catalyst, solvent and coal powder obtained by particle size distribution are mixed and stirred for about 4 hours to obtain oil-coal slurry with a concentration of 30-60%. The solvent refers to the circulating solvent produced by the direct liquefaction process itself, and can also be an external coal-based oil product such as petroleum-based heavy oil, coal tar, etc.

[0040] Embodiment 1:

[0041] A coal sample from Xinjiang was used. According to the preparation method of the present invention, the coal was first crushed into coal powder particles with a particle size of 278 μm. Then, the separation density was determined to be 1300 kg / m through a floating and sinking test. 3 After separation in a heavy medium cyclone, an inert component enrichment with a mass fraction of 68% and an active component enrichment with a mass fraction of 32% were obtained. The inert component enrichment was subjected to secondary fine crushing to obtain fine coal powder with a particle size of 75μm. The fine coal powder obtained by the secondary fine crushing was graded with the active component enrichment, and the mass ratio was 1.8:1. The iron-based supported catalyst, coal liquefaction circulating solvent and coal powder obtained by particle size grading were mixed to prepare a slurry with a coal slurry concentration of 45%, and stirred for 4 hours to obtain a stable oil-coal slurry.

[0042] Comparative Example 1:

[0043] A coal sample from Xinjiang was used and crushed into coal powder particles with a particle size of 75 μm; an iron-based supported catalyst, a coal liquefaction circulating solvent and the coal powder particles were mixed to prepare a slurry with a coal slurry concentration of 45% and stirred for 4 hours to obtain an oil-coal slurry with stable properties.

[0044] The viscosity of the oil-coal slurry prepared in Example 1 and Comparative Example 1 was analyzed, and the coal liquefaction reaction performance was evaluated using a 100 mL autoclave under the same conditions. The specific results are shown in Table 1.

[0045] Table 1 Comparative test of oil-coal slurry stability and reactivity

[0046]

[0047] Embodiment 2:

[0048] A coal sample from Shaanxi Province was used. According to the preparation method of the present invention, the coal was first crushed into coal powder particles with a particle size of 200 μm. Then, the separation density was determined to be 1350 kg / m by floating and sinking tests. 3 After separation in a heavy medium cyclone, an inert component enrichment with a mass fraction of 75% and an active component enrichment with a mass fraction of 25% are obtained. The inert component enrichment is subjected to secondary fine crushing to obtain fine coal powder with a particle size of 45μm. The fine coal powder obtained by the secondary fine crushing is subjected to particle size grading with the active component enrichment, and the mass ratio is 2.5:1. The coal powder obtained after particle size grading, the iron-based supported catalyst, and the coal liquefaction circulating solvent are mixed to prepare a slurry, and the coal slurry concentration is 50%. The mixture is stirred for 4 hours to obtain a stable oil-coal slurry.

[0049] Comparative Example 2:

[0050] A coal sample from Shaanxi Province was crushed into coal powder particles with a particle size of 45 μm. An iron-based supported catalyst, coal liquefaction circulating solvent and coal powder particles were mixed to prepare a slurry with a coal slurry concentration of 50%. The slurry was stirred for 4 hours to obtain an oil-coal slurry with stable properties.

[0051] The viscosity of the two oil-coal slurries was analyzed, and the coal liquefaction reaction performance was evaluated under the same conditions using a 100 mL autoclave. The specific results are shown in Table 2.

[0052] Table 2 Comparative test of oil-coal slurry stability and reactivity

[0053]

[0054] Based on the technical enlightenment of the above-mentioned Examples 1 and 2, those skilled in the art can also prepare oil-coal slurries with coal slurry concentrations of 30% and 60%.

[0055] In the description of this application, unless otherwise specified, " / " means "or", for example, A / B can mean A or B. "And / or" in this article is only a way to describe the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0056] In the description of this application, words such as "first" and "second" are only used to distinguish different objects, and do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit differences. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0057] Parts not described in the present invention can be implemented by those skilled in the art by referring to the existing technology.

[0058] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application and are not intended to be limiting of the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments should fall within the scope of protection of the claims of the present application.

Claims

1. A method for preparing coal-oil slurry from direct coal liquefaction, characterized in that: The following steps are included in sequence: (1) The pulverized coal is crushed into pulverized coal particles of a certain size by a primary crushing process; (2) determining the appropriate separation density range of the coal powder particles through a floating and sinking test; (3) according to the separation density set range obtained in step (2), the pulverized coal particles are separated by a heavy medium cyclone to obtain an inert component enriched product and an active component enriched product; the active component content in the inert component enriched product is ≤50%, and the active component content in the active component enriched product is ≥40%; (4) performing secondary fine crushing on the inert component enriched product to obtain fine coal powder with a certain particle size; (5) performing particle size grading on a portion of the fine coal powder obtained in step (4) and the active component enriched material to obtain particle size graded coal powder; (6) A portion of the fine coal powder obtained in step (4) is used as a carrier for catalyst preparation, and the carrier is mixed with a catalyst formed by an active metal, a solvent and coal powder after particle size distribution to obtain an oil-coal slurry.

2. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 1, characterized in that: In step (1), the particle size of the coal powder particles is 0 to 500 μm, and the coal powder is crushed in the primary stage by a hammer crusher, a jaw crusher, a cone crusher or a roller crusher.

3. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 2, characterized in that: In step (2), a floating and sinking test of the coal powder particles is carried out using zinc chloride heavy liquid, and the separation density range is 1300-1800 kg / m 3 .

4. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 1, characterized in that: In step (3), the diameter of the heavy medium cyclone is ≤700 mm, the inlet diameter of the heavy medium cyclone is 50-200 mm, and the outlet diameter of the heavy medium cyclone is 100-300 mm.

5. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 3, characterized in that: In step (4), the secondary fine crushing adopts a ball mill or a rod mill, and the particle size of the fine coal powder is 0 to 150 μm.

6. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 1, characterized in that: In step (5), the mass ratio of fine coal powder to active component concentrate is 1 to 5:

1.

7. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 1, characterized in that: In step (6), the mass ratio of the fine coal powder as a carrier to the fine coal powder described in step (4) is 10-50%; the active metal is a composite of one or more of iron, molybdenum, nickel, cobalt and tungsten metals.

8. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 1, characterized in that: In step (6), the solvent refers to the circulating solvent generated by the direct liquefaction process itself, the solvent is petroleum-based heavy oil or coal tar, and the concentration of the oil-coal slurry is 30-60%.

9. The method for preparing coal-oil slurry from direct coal liquefaction according to claim 5, characterized in that: The particle size of the coal powder is 0-300 μm, and the separation density range is 1300-1550 kg / m 3 The particle size of fine coal powder is 0 to 75 μm.

10. An oil-coal slurry, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 9.

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