Treatment method of direct coal liquefaction residue raffinate

Abstract

The invention belongs to the field of comprehensive utilization of coal chemical solid waste, and particularly relates to a treatment method of direct coal liquefaction residue raffinate, which comprises the following steps: (1) mixing direct coal liquefaction residue and an extraction agent to obtain an extraction system, and carrying out solid-liquid separation on the extraction system to obtain filtrate and filter residue; (2) carrying out distillation treatment on the filtrate to obtain asphalt; and (3) drying the filter residue to obtain a solid, and carrying out pyrolysis treatment on the solid to obtain pyrolytic oil. The method disclosed by the invention has the beneficial effects that the direct coal liquefaction residues are changed into products with industrial application values through a segmented processing method, so that an energy-saving, emission-reducing and resource-saving development mode is realized; a solution is provided for solving the problems of land occupation caused by accumulation and landfill of the direct coal liquefaction residues and serious damage to the ecological environment, and a new way with a wide market economic prospect is explored for realizing high-value utilization of liquefaction residue resources.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive utilization of coal chemical solid waste, and in particular relates to a method and a device for treating residues of direct coal liquefaction residues. Background Art

[0003] Coal direct liquefaction technology is used to produce gasoline and diesel. Liquefaction residue is a by-product of coal direct liquefaction technology. The output of coal liquefaction residue is generally 30% of the raw coal. Liquefaction residue has the characteristics of high carbon, high ash and high sulfur, and is composed of heavy oil, liquefaction intermediates, unconverted coal and minerals. Traditional gasification, coking and combustion do not reflect the high added value utilization potential of liquefaction residue. Therefore, the high carbon utilization of coal liquefaction residue is an important part of the development of coal liquefaction process technology and the extension of the industrial chain. The breakthrough of coal liquefaction residue technology will promote the rapid development of coal direct liquefaction technology, boost the transformation and upgrading of the industry, and play a significant supporting and leading role.

[0004] The preparation of high-end carbon materials from coal liquefaction residues is a hot topic in the field of coal direct liquefaction technology. The key to the realization of this process lies in the efficient and deep deashing of the residues. The 350,000 t / a liquefied residue extraction and preparation of high-medium-low grade asphalt unit put into operation in the Ordos million-ton coal direct liquefaction plant in China has realized the high-value utilization of part of the liquefied residues of the liquefaction plant. However, the million-ton direct liquefaction plant produces more than 170,000 tons of extracts per year as a by-product. From the perspective of energy utilization and economic benefits, the company's demand for extract disposal covers gasification, pyrolysis and combustion. In particular, the pyrolysis of the extract can efficiently recover the extractant in the liquefied residue extract, and the generated oil can be used to prepare gasoline, diesel and other products. Fuel gas can replace part of the energy consumption. As a supporting technology for the extraction and deashing of liquefied residues, the development of the efficient pyrolysis technology for the disposal of the extract will form a circular economy and a closed-loop technology for the high-value utilization of residues. At present, the treatment method of the residue is to dry and recover the entrained extractant and then burn it. The asphaltene and coal powder coke contained in it are not fully utilized. The excess residue is sold at a price of 300 yuan / ton. More than 90% of these residues have a particle size of less than 40μm. Long-term stacking is likely to cause dust pollution in the park and bring explosion risks to external transportation, which restricts the long-term stable production of enterprises and the large-scale development of direct coal liquefaction. How to efficiently dispose of the residue has become the key to the technical chain of deep deashing of liquefied residues to prepare high-end carbon materials, and is also an important part of the development of coal liquefaction process technology and the extension of the industrial chain. Summary of the invention

[0005] The present application provides a method for treating direct coal liquefaction residues, aiming to solve the problem that direct coal liquefaction residues accumulate and landfill and occupy land resources, seriously damage the ecological environment, and cannot be used at high value.

[0006] In a first aspect of the present application, a method for treating coal direct liquefaction residue is provided, comprising the following steps:

[0007] (1) mixing the coal direct liquefaction residue and an extractant to obtain an extraction system, and performing solid-liquid separation on the extraction system to obtain a filtrate and a filter residue;

[0008] (2) distilling the filtrate to obtain refined asphalt;

[0009] (3) Drying the filter residue to obtain a solid, and pyrolyzing the solid to obtain pyrolysis oil.

[0010] Since the direct coal liquefaction residue has high ash and high viscosity and contains a certain amount of carbonized precursors such as asphaltene, refined asphalt can be obtained through extraction and distillation with an extractant, and the extractant can be recycled. The extractant in the residue can be recovered and then subjected to pyrolysis treatment to obtain pyrolysis oil, which can be used as a raw material for the preparation of gasoline and diesel products. That is, the method described in this application realizes the use of materials according to the conditions and makes full use of the direct coal liquefaction residue without generating secondary pollution, realizing an energy-saving and emission-reduction and resource-saving development model, solving the problems of accumulation of direct coal liquefaction residue and damage to the ecological environment, and exploring a new way with broad market economic prospects for realizing high-value resource utilization of liquefied residue.

[0011] The extraction system described in the present application is a suspension, comprising an extraction liquid and a residue insoluble in the extraction liquid.

[0012] According to some embodiments of the method for treating coal direct liquefaction residue described in the present application, the extractant includes a light extractant and a heavy extractant, the final distillation point of the light extractant is <220°C, and the initial distillation point of the heavy extractant is ≥220°C.

[0013] According to some embodiments of the method for treating direct coal liquefaction residue described in the present application, the light extractant includes one or more of tetrahydrofuran, N-methylpyrrolidone and tetralin.

[0014] According to some embodiments of the method for treating direct coal liquefaction residue described in the present application, the heavy extractant includes coking wash oil and / or coking anthracene oil.

[0015] According to some embodiments of the method for treating the coal direct liquefaction residue of the present application, the mass ratio of the coal direct liquefaction residue to the extractant is 1:(1-10).

[0016] According to some embodiments of the method for treating the coal direct liquefaction residue of the present application, the extraction temperature is 20-180° C.; and the extraction time is 30-90 min.

[0017] According to some embodiments of the method for treating the coal direct liquefaction residue of the present application, the drying temperature is 100-300° C., and the drying time is 1-5 hours.

[0018] According to some embodiments of the method for treating coal direct liquefaction residue described in the present application, the method for treating coal direct liquefaction residue also includes the steps of: mixing the solid matter, binder, coal powder and activator aqueous solution, performing pyrolysis and activation treatment to obtain pyrolysis oil and adsorption material.

[0019] According to some embodiments of the method for treating the coal direct liquefaction residue described in the present application, the mass ratio of the solid matter, the binder and the coal powder is (2-3): (1-2): (10-20).

[0020] According to some embodiments of the method for treating the direct coal liquefaction residue of the present application, the amount of the activator aqueous solution added is 5%-10% of the total weight of the solid matter, the binder and the coal powder.

[0021] According to some embodiments of the method for treating the direct coal liquefaction residue of the present application, the pyrolysis temperature is 300-600°C.

[0022] According to some embodiments of the method for treating the coal direct liquefaction residue of the present application, the activation temperature is 800-950° C., and the activation time is 90-120 min.

[0023] According to some embodiments of the method for treating direct coal liquefaction residue of the present application, the binder includes coal tar and / or coal pitch.

[0024] According to some embodiments of the method for treating the direct coal liquefaction residue of the present application, the particle size of the coal powder is less than or equal to 0.2 mm;

[0025] According to some embodiments of the method for treating coal direct liquefaction residue described in the present application, the activating agent includes one or more of KOH, NaOH and phosphoric acid.

[0026] According to some embodiments of the method for treating the direct coal liquefaction residue of the present application, the mass concentration of the activator aqueous solution is 10%-20%.

[0027] According to some embodiments of the method for treating the coal direct liquefaction residue of the present application, when the extractant is a light extractant, the pyrolysis temperature is 500-600°C.

[0028] According to some embodiments of the method for treating coal direct liquefaction residue described in the present application, when the extractant is a heavy extractant, the pyrolysis includes a first-stage pyrolysis and a second-stage pyrolysis, the temperature of the first-stage pyrolysis is 300-400°C, and the time of the first-stage pyrolysis is 2-8h; the temperature of the second-stage pyrolysis is 500-600°C, and the time of the second-stage pyrolysis is 1-6h.

[0029] According to some embodiments of the method for treating coal direct liquefaction residue described in the present application, the method for treating coal direct liquefaction residue also includes the steps of: subjecting the pyrolysis treatment product to oil and gas buffering treatment to separate the pyrolysis oil and pyrolysis gas obtained by pyrolysis; the pyrolysis gas provides energy for pyrolysis.

[0030] According to some implementations of the method for treating the direct coal liquefaction residue described in the present application, the equipment for performing pyrolysis is a pyrolysis furnace.

[0031] According to some embodiments of the method for treating the direct coal liquefaction residue described in the present application, the equipment for implementing the oil and gas buffering treatment is a stabilization tower. Preferably, the pyrolysis gas is discharged through the gas outlet of the stabilization tower to provide energy for the pyrolysis furnace.

[0032] The beneficial effects of this application include at least:

[0033] 1. The method for treating coal direct liquefaction residue described in this application transforms coal direct liquefaction residue into products with industrial application value through a segmented processing method without generating secondary pollution, thus realizing a development model of energy conservation, emission reduction and resource conservation, and providing a solution to the problems of accumulation and land occupation of coal direct liquefaction residue and serious damage to the ecological environment, thereby exploring a new way with broad market economic prospects for realizing high-value resource utilization of liquefied residue.

[0034] 2. The method for treating the coal direct liquefaction residue described in this application can produce an active material with adsorption performance having a certain specific surface area and strength, which can be used in the fields of chemical wastewater treatment, adsorption and purification of toxic gases generated by waste incineration, etc., thereby increasing the added value of the coal direct liquefaction residue.

[0035] 3. The method for treating the coal direct liquefaction residue described in the present application can reuse the extractant, and the generated pyrolysis gas can also provide energy for pyrolysis, thereby fully utilizing the coal direct liquefaction residue without generating pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the method for treating the coal direct liquefaction residue described in Example 1 of the present application;

[0037] Figure 2 This is a flow chart of the method for treating the coal direct liquefaction residue described in Example 2 of the present application;

[0038] Figure 3 This is a flow chart of the method for treating the coal direct liquefaction residue described in Example 3 of the present application;

[0039] Figure 4 This is a flow chart of the method for treating coal direct liquefaction residue described in Example 4 of the present application. DETAILED DESCRIPTION

[0040] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0041] The technical solution of the present application is described in detail below in conjunction with specific embodiments and drawings.

[0042] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0043] The present application provides a method for treating coal direct liquefaction residue, comprising the following steps:

[0044] (1) mixing the coal direct liquefaction residue and an extractant to obtain an extraction system, and performing solid-liquid separation on the extraction system to obtain a filtrate and a filter residue;

[0045] (2) distilling the filtrate to obtain refined asphalt;

[0046] (3) Drying the filter residue to obtain a solid, and pyrolyzing the solid to obtain pyrolysis oil.

[0047] Since the direct coal liquefaction residue has high ash and high viscosity and contains a certain amount of carbonized precursors such as asphaltene, refined asphalt can be obtained through extraction and distillation with an extractant, and the extractant can be recycled. Pyrolysis oil can be obtained through pyrolysis treatment, and pyrolysis oil can be used as a raw material for the preparation of gasoline and diesel products. That is, the method described in this application realizes the use of materials according to the conditions and makes full use of the direct coal liquefaction residue without generating secondary pollution, realizing an energy-saving, emission-reduction and resource-saving development model, solving the problems of accumulation of direct coal liquefaction residue and damage to the ecological environment, and exploring a new way with broad market economic prospects for realizing high-value resource utilization of liquefied residue.

[0048] The extraction system described in the present application is a suspension, comprising an extraction liquid and a residue insoluble in the extraction liquid.

[0049] In some embodiments, the extractant includes a light extractant and a heavy extractant, the final boiling point of the light extractant is less than 220°C, such as 210°C, 195°C, 190°C, 185°C, 180°C, 175°C, 170°C, 160°C, 158°C, 150°C, etc.; the initial boiling point of the heavy extractant is ≥220°C, such as 230°C, 260°C, etc. The light or heavy extractant is used to extract the heavy oil and asphaltene in the liquefied residue to the maximum extent.

[0050] In some embodiments, the light extractant includes one or more of tetrahydrofuran, N-methylpyrrolidone, and tetralin.

[0051] In some embodiments, the heavy extractant includes coking wash oil and / or coking anthracene oil. The coking wash oil and coking anthracene oil described in the present application are both derived from coking plants in steel enterprises.

[0052] In some embodiments, the mass ratio of the coal direct liquefaction residue to the extractant is 1:(1-10), such as 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:8, 1:9, 1:10, etc. This mass ratio is conducive to the full dissolution of the liquefied residue, with appropriate viscosity and easy pumping.

[0053] In some embodiments, the extraction temperature is 20-180°C, and different temperatures are selected according to different extractants in order to obtain the best extraction effect, that is, to extract heavy oil and asphaltene from the liquefied residue, for example, 20°C, 50°C, 80°C, 100°C, 120°C, 150°C, 180°C; the extraction time is 30-90min, for example, 30min, 40min, 50min, 60min, 70min, 80min, 90min.

[0054] In some embodiments, the drying temperature is 100-300°C, for example 100°C, 120°C, 130°C, 150°C, 180°C, 200°C, 220°C, 230°C, 240°C, 250°C, 260°C, 300°C, etc., and the drying time is 1-5h, for example 1h, 3h, 5h, etc.

[0055] In some embodiments, the method for treating the coal direct liquefaction residue further includes the steps of mixing the solid matter, binder, coal powder and activator aqueous solution, forming, pyrolyzing and activating the solid matter to obtain pyrolysis oil and adsorption material.

[0056] Since the residue of coal direct liquefaction has the characteristics of high viscosity and high ash, it is used as a raw material to prepare an adsorption carbon product with a certain specific surface area and strength, which is used in chemical wastewater treatment, adsorption and purification of toxic gases produced by waste incineration, and other fields, which increases the added value of the resource utilization of the residue. The residue obtained by extracting the liquefied residue with a heavy extractant has a certain viscosity, which can reduce the amount of binder used. The preparation of adsorption carbon products after molding is conducive to increasing the added value of the residue. In addition, most of the heavy extractants are industrial solvents, which are cheap and easy to obtain, and have good extraction effects. They can extract more asphaltene and heavy oil, which is conducive to the disposal of more liquefied residues.

[0057] After the solid matter, binder, coal powder and activator aqueous solution are mixed, they are subjected to carbonization treatment which is equivalent to pyrolysis treatment, and then activation treatment to obtain adsorption materials. The adsorption materials can be used in chemical wastewater treatment, adsorption and purification of toxic gases generated by garbage incineration and other fields.

[0058] The solid matter, binder, coal powder and activator aqueous solution are mixed and heated to form coal paste, which is extruded into columns, spheres, squares, etc. in a hydraulic press at 16-22MPa, naturally ventilated and aired for 2-3 days until the moisture content is less than 10%, and then sent to a carbonization furnace, and nitrogen is introduced at a flow rate of 100-350ml / min for pyrolysis (carbonization treatment). After the pyrolysis is completed, the activation temperature is raised to 800-950°C. During the activation process, air with a gas flow rate of 30-50ml / min and nitrogen with a gas flow rate of 100-350ml / min are mixed in a gas mixing tank, and then mixed with water vapor with a flow rate of 10-50ml / h in a heated and heat-insulated outlet pipeline and enter the furnace body for activation treatment. The activation time is 90-120min. After the activation is completed, the water vapor and air are stopped, and nitrogen is continued to be passed to cool down until the temperature is lower than 150°C and the nitrogen is stopped. The oil distilled from the whole process can be mixed with the extractant recovered from the atmospheric distillation of the filtrate and reused for pulping with the residue. The excess oil can be used as a raw material for the preparation of gasoline and diesel products. The pyrolysis gas enters the hot air furnace through the exhaust gas blower and is used as fuel to supply heat to the pyrolysis furnace. The prepared activated carbon can be used in the fields of chemical wastewater treatment, adsorption and purification of toxic gases generated by garbage incineration, etc.

[0059] In some embodiments, the mass ratio of the solid matter, the binder and the coal powder is (2-3):(1-2):(10-20); for example, 2:1:10, 2:2:15, 3:1:10, 3:2:10, 3:2:20, etc.

[0060] In some embodiments, the amount of the activator aqueous solution added is 5%-10% of the total weight of the solid matter, the binder and the coal powder; for example, 5%, 6%, 7%, 8%, 10%, etc.

[0061] In some embodiments, the pyrolysis temperature is 300-600°C, such as 300°C, 550°C, 600°C, etc.

[0062] In some embodiments, the activation temperature is 800-950°C, for example, 800°C, 850°C, 900°C, 950°C; the activation time is 90-120 min, for example, 90 min, 100 min, 110 min, 120 min.

[0063] In some embodiments, the binder includes coal tar and / or coal pitch.

[0064] In some embodiments, the particle size of the coal powder is less than or equal to 0.2 mm.

[0065] In some embodiments, the activating agent includes one or more of KOH, NaOH, and phosphoric acid.

[0066] In some embodiments, the mass concentration of the aqueous activator solution is 10%-20%, such as 10%, 15%, 18%, 20%, etc.

[0067] In some embodiments, when the extractant is a light extractant, the pyrolysis temperature is 500-600°C, for example, 500°C, 520°C, 560°C, 600°C, etc.; the pyrolysis treatment time is 1-6h, for example, 1h, 2h, 4h, 5h, 6h, etc., and the extractant retained in the residue is basically recovered after drying. The dried residue is pyrolyzed at 500-600°C to generate pyrolysis oil to the maximum extent.

[0068] In some embodiments, when the extractant is a heavy extractant, the pyrolysis includes a first stage pyrolysis and a second stage pyrolysis, the temperature of the first stage pyrolysis is 300-400°C, for example, 300°C, 320°C, 350°C, 360°C, 380°C, 400°C; the time of the first stage pyrolysis is 2-8h, for example, 2h, 4h, 5h, 6h, 8h; the temperature of the second stage pyrolysis is 500-600°C, for example, 500°C, 520°C, 550°C, 560°C, 580°C, 600°C; the time of the second stage pyrolysis is 1-6h, for example, 1h, 2h, 3h, 4h, 6h. The pyrolysis under mild conditions in the first stage is intended to recover the heavy extractant in the raffinate. Under mild conditions, the extractant will not condense and become heavy, which is conducive to maintaining the original characteristics of the extractant. The second stage pyrolysis is intended to promote the pyrolysis of the raffinate to generate oil and improve the yield of pyrolysis oil.

[0069] When the heavy raffinate system is pyrolyzed at a temperature of 300-400°C in the first stage, what is recovered is mainly the heavy extractant retained in the raffinate. The heavy extractant mainly undergoes physical volatilization, and the structural composition of the extractant does not change much. It can still be reused to maintain the initial state of extraction performance. When the heavy oil, asphaltene and organic solids are pyrolyzed at a temperature of 500-600°C in the second stage, the heavy oil, asphaltene and organic solids undergo condensation reaction to transform into heavy product semi-coke, and tar (pyrolysis oil) and pyrolysis gas are generated at the same time.

[0070] In some embodiments, the method for treating the coal direct liquefaction residue further includes the steps of: subjecting the pyrolysis product to oil and gas buffering treatment to separate the pyrolysis oil and pyrolysis gas obtained by pyrolysis; and the pyrolysis gas provides energy for pyrolysis.

[0071] In some embodiments, the apparatus for performing pyrolysis is a pyrolysis furnace.

[0072] In some embodiments, the equipment for implementing the oil and gas buffering treatment is a stabilization tower. Preferably, the pyrolysis gas is discharged through the gas outlet of the stabilization tower to provide energy for the pyrolysis furnace.

[0073] The results of physical property analysis of the coal and coal direct liquefaction residue used in the examples of the present application are shown in Table 1-2:

[0074] Table 1 Coal quality analysis data of coal and residue

[0075]

[0076] Table 2 Composition analysis data of the raffinate

[0077] Oil Asphaltene Solid organic matter Ash water 25 20.50 27.48 26.10 0.92

[0078] Specific implementation cases

[0079] Example 1

[0080] A method for treating coal direct liquefaction residue comprises the following steps:

[0081] Coal liquefaction residue with a particle size of 3 mm was added to tetralin with a mass ratio of 1:3 and a stirring rate of 300 rpm. After constant temperature extraction for 60 min at an extraction temperature of 100 ° C, the obtained extraction system was vacuum filtered at 80 ° C, and the filtrate was subjected to atmospheric distillation to recover the extractant tetralin and obtain refined asphalt. The residue (filter residue) was placed in a hollow paddle dryer and dried for 2.5 h at a drying temperature of 280 ° C. The extractant tetralin retained therein was further recovered. The extractant recovered by distillation of the filtrate and drying of the residue was The extractant is mixed and reused as the extractant of the liquefied residue. The dried extract residue is placed in a pyrolysis furnace for further pyrolysis and oil extraction. The pyrolysis temperature is 600°C and the pyrolysis time is 3h. The pyrolysis oil is distilled out. The pyrolysis oil can be used as a raw material for the preparation of gasoline and diesel products. The pyrolysis gas generated during the pyrolysis process enters the hot blast furnace through the exhaust gas blower as fuel to supply heat to the pyrolysis furnace. The semi-coke generated during the pyrolysis process can be used as a heat source to enter the boiler and burn with coal. The gas discharged from the hot blast furnace can be directly discharged into the atmosphere after desulfurization. The process of the treatment method of the coal direct liquefaction residue described in Example 1 is as follows Figure 1 shown.

[0082] Example 2

[0083] A method for treating coal direct liquefaction residue comprises the following steps:

[0084] Coal liquefaction residue with a particle size of 3 mm was added to tetralin in a mass ratio of 1:3, with a stirring rate of 300 rpm. After constant temperature extraction for 60 minutes at an extraction temperature of 100°C, the obtained extraction system was vacuum filtered at 80°C, and the filtrate was subjected to atmospheric distillation to recover the extractant tetralin, and refined asphalt was obtained. The residue (filter residue) was placed in a hollow paddle dryer and dried at a drying temperature of 280°C for 2.5 hours to further recover the extractant tetralin retained therein. The extractant recovered by distillation of the filtrate and drying of the residue was mixed and reused as the extractant of the liquefied residue.

[0085] The above-mentioned dried residue, coal tar and coal powder with a particle size of 0.2 mm are mixed in a mass ratio of 2:1:10, and then 10% (accounting for the mass of the mixture of residue, coal powder and coal tar) of 20% KOH aqueous solution at 90°C is added and mixed evenly to form a coal paste, which is extruded into a column at 19MPa in a hydraulic press to obtain a molding raw material, and the molding raw material is spontaneously combusted, ventilated and air-dried for 2 days until the moisture content reaches 8%.

[0086] The above-mentioned molding raw materials are sent into the carbonization furnace, and nitrogen is introduced into the carbonization furnace at a flow rate of 300ml / min. The carbonization temperature (pyrolysis temperature) is set to 550℃, and the pyrolysis time is 1.5h. After the pyrolysis is completed, the temperature is raised to 850℃ for activation. During the activation process, air with a flow rate of 40ml / min and nitrogen with a flow rate of 300ml / min are introduced into the gas mixing tank and mixed. Then, they are mixed with water vapor with a flow rate of 50ml / h in the heated and insulated gas outlet pipeline and introduced into the carbonization furnace body. The activation time is 120min. After the activation is completed, the introduction of water vapor and air is stopped, and nitrogen is continued to be introduced to cool down until the temperature of the carbonization furnace is lower than 150℃ and the introduction of nitrogen is stopped. The pyrolysis oil distilled from the whole process can be mixed with the extractant recovered by atmospheric distillation of the filtrate and reused for pulping with the residue. The excess pyrolysis oil can be used as a raw material for the preparation of gasoline and diesel products. The pyrolysis gas enters the hot blast furnace through the exhaust gas blower as fuel to supply heat to the pyrolysis furnace. The prepared activated carbon can be used in the fields of chemical wastewater treatment, adsorption and purification of toxic gases generated by garbage incineration, etc. The semi-coke produced in the whole process can be used as a heat source to enter the boiler and burn with coal. The gas discharged from the hot blast furnace can be directly discharged into the atmosphere after desulfurization. The process of the treatment method of the coal direct liquefaction residue described in Example 2 is as follows Figure 2 shown.

[0087] Example 3

[0088] A method for treating coal direct liquefaction residue comprises the following steps:

[0089] Coal liquefaction residue with a particle size of 3 mm was added to coking wash oil in a mass ratio of 1:3. The stirring rate was 300 rpm and the extraction temperature was 120°C. After constant temperature extraction for 60 minutes, the obtained extraction system was vacuum filtered at 80°C, and the filtrate was distilled under reduced pressure (5 mmHg) to recover the extractant wash oil and obtain refined asphalt.

[0090] The extract (filter residue) was placed in a hollow paddle dryer and dried at a drying temperature of 280°C for 2.5 hours to further recover the coking wash oil retained therein as the extractant. The extractant recovered by distillation of the filtrate and drying of the extract was mixed and reused as the extractant for the liquefied residue.

[0091] The dried residue is placed in a pyrolysis furnace, and the first pyrolysis temperature of the pyrolysis furnace is set to 350°C, and the residence time is 3h. The residual extractant in the residue is recovered, and the recovered extractant can be mixed with the extractant recovered by vacuum distillation of the filtrate and reused for pulping with the residue. The temperature of the pyrolysis furnace is adjusted to raise the temperature to the second pyrolysis temperature of 600°C, and the residence time is 5h. Further pyrolysis is performed to extract oil to obtain pyrolysis oil. The obtained pyrolysis oil can be used as a raw material for the preparation of gasoline and diesel products. The pyrolysis gas generated during the pyrolysis process enters the hot blast furnace through the exhaust gas blower as fuel to supply heat to the pyrolysis furnace. The semi-coke generated during the pyrolysis process can be used as a heat source to enter the boiler and burn with coal. The gas discharged from the hot blast furnace can be directly discharged into the atmosphere after desulfurization. The process of the treatment method of the coal direct liquefaction residue described in Example 3 is as follows Figure 3 shown.

[0092] Example 4

[0093] A method for treating coal direct liquefaction residue comprises the following steps:

[0094] Coal liquefaction residue with a particle size of 3 mm was added to coking wash oil in a mass ratio of 1:3. The stirring rate was 300 rpm and the extraction temperature was 120°C. After constant temperature extraction for 60 minutes, the obtained extraction system was vacuum filtered at 80°C, and the filtrate was distilled under reduced pressure (5 mmHg) to recover the extractant wash oil and obtain refined asphalt.

[0095] The extract (filter residue) was placed in a hollow paddle dryer and dried at a drying temperature of 280°C for 2.5 hours to further recover the coking wash oil retained therein as the extractant. The extractant recovered by distillation of the filtrate and drying of the extract was mixed and recycled as the extractant of the liquefied residue.

[0096] The above-mentioned dried residue, coal tar and 0.2mm coal powder are mixed in a mass ratio of 2:1:10, and then 10% (accounting for the mass of the mixture of residue, coal powder and coal tar) of a 20% KOH aqueous solution at 90°C is added and mixed evenly to form a coal paste, which is extruded into a column at 19MPa in a hydraulic press to obtain a molding raw material, and the molding raw material is spontaneously combusted, ventilated and air-dried for 2 days until the moisture content is 8%.

[0097] The above-mentioned forming raw materials are sent into the carbonization furnace, and nitrogen is introduced into the carbonization furnace at a flow rate of 300ml / min. The first carbonization temperature (pyrolysis temperature) is set to 350°C, and the first carbonization time is 1.5h. After the first carbonization is completed, the temperature of the carbonization furnace is adjusted to 600°C for the second carbonization (second pyrolysis). The time of the second carbonization (second pyrolysis) is 1h. After the carbonization is completed, the temperature is raised to 850°C for activation treatment. During the activation process, air with a flow rate of 40ml / min and nitrogen with a flow rate of 300ml / min are introduced into the gas mixing tank and mixed, and then mixed with water vapor with a flow rate of 50ml / h in the heated and heat-insulated outlet pipeline and introduced into the carbonization furnace body. After the activation is completed, the introduction of water vapor and air is stopped, and nitrogen is continued to be introduced to cool down until the temperature of the carbonization furnace is lower than 150°C and the nitrogen is stopped. The pyrolysis oil distilled from the entire carbonization and activation process can be used as a raw material for the preparation of gasoline and diesel products. The pyrolysis gas enters the hot blast furnace through the exhaust gas blower as a fuel to supply heat to the pyrolysis furnace. The prepared activated carbon can be used in the fields of chemical wastewater treatment, adsorption and purification of toxic gases generated by garbage incineration, etc. The semi-coke produced in the whole process can be used as a heat source to enter the boiler and burn with coal. The gas discharged from the hot blast furnace can be directly discharged into the atmosphere after desulfurization. The process of the treatment method of the coal direct liquefaction residue described in Example 4 is as follows Figure 4 shown.

[0098] Comparative Example 1

[0099] The difference between Comparative Example 1 and Example 1 is that in the treatment process of the coal direct liquefaction residue in Comparative Example 1, the obtained extract (filter residue) is not dried and directly enters the pyrolysis furnace for pyrolysis and oil extraction. The other steps are the same as those in Example 1.

[0100] Comparative Example 2

[0101] The difference between Comparative Example 2 and Example 2 is that in the treatment process of the coal direct liquefaction residue in Comparative Example 2, no binder and activator are added in the process of kneading the dried extract and coal powder, and the other steps are the same as Example 2.

[0102] Comparative Example 3

[0103] The difference between Comparative Example 3 and Example 3 is that in the treatment process of coal direct liquefaction residue in Comparative Example 3, there is no first temperature and second temperature step-by-step temperature increase in the pyrolysis furnace, and the temperature is directly increased from room temperature to 600°C. The other steps are the same as Example 3.

[0104] Comparative Example 4

[0105] The difference between Comparative Example 4 and Example 4 is that, in the treatment process of the coal direct liquefaction residue in Comparative Example 4, the extract (filter residue) is not kneaded with coal powder and coal tar, but is directly subjected to pyrolysis activation, and the other steps are the same as those in Example 4.

[0106] The physical properties of the products obtained from the treatment process of the coal direct liquefaction residue in Examples 1-4 and Comparative Examples 1-4 of the present application are analyzed, and the results are shown in Table 3:

[0107] Table 3

[0108] Solvent recovery rate / % <![CDATA[Crushing strength / N·cm -1 > Ash / % <![CDATA[Specific surface area / m 2 / g]]> Example 1 97.5％ - 37.2 - Example 2 97％ 110 19.5 620 Example 3 98.4％ - 38 - Example 4 97.3％ 112 20 590 Comparative Example 1 85％ - 35 - Comparative Example 2 97.2％ 90 22 550 Comparative Example 3 88％ - 36.5 - Comparative Example 4 97.2％ - 58 150

[0109] Note: Crushing strength refers to the force required to apply radial force to the sample until it is crushed, and the molecular sieve crushing strength test method HG / T 2783-2020 is used.

[0110] Ash content refers to the percentage of the residue after high-temperature burning in the original sample mass. Coal quality classification: Part 1 Ash content GB / T15224.1-2018.

[0111] Specific surface area refers to the surface area per unit mass of porous solid matter, and the test method for coal-based granular activated carbon GB / T 7702.20-2008 is adopted.

[0112] From Table 3 we can see that:

[0113] The extraction agent recovery rate of the treatment method of the coal direct liquefaction residue described in the present application is relatively high, while the method described in comparative example 1 has a relatively low extraction agent recovery rate because the light raffinate system has not undergone a drying process, and a large amount of residual extraction agent inside is polycondensed under the high temperature of the pyrolysis furnace. The extraction agent recovery rate of comparative example 3 is also low, because the pyrolysis does not undergo a step-by-step heating process. The first stage of the step-by-step heating at 350°C is a physical recovery process of the heavy extraction agent, and the latter stage is a chemical pyrolysis process. The pyrolysis temperature of comparative example 3 is directly raised to 600°C, and the heavy extraction agent in the raffinate undergoes cracking and polycondensation at this temperature, resulting in a reduction in extraction agent, which is the essence of the reduced extraction agent recovery.

[0114] The activated carbon obtained by the method for treating the coal direct liquefaction residue described in the present application has a relatively high crushing strength. Although the dried residue described in the method described in Comparative Example 2 contains asphaltene and has certain adhesiveness, and can be mixed with coal powder to form a shape, its compatibility with coal powder is not as good as that of coal-based binders, and it cannot bond the coal powder particles together well in the form of a monomolecular layer. In addition, the asphalt content in the residue is much lower than that of coal tar, and the residue filling the pores between the coal powder particles forms insufficient asphalt coke in the subsequent carbonization process, and cannot play a good role in supporting the skeleton. Therefore, the strength of the product of Comparative Example 2 is significantly reduced.

[0115] It can also be seen from Table 3 that the ash content of the residue is as high as 26.10%. In Comparative Example 4, due to the absence of coal powder, the ash of the residue is enriched in the product after carbon activation, resulting in an ash content of up to 58%. The specific surface area of ​​the adsorptive carbon product is mostly contributed by the pore expansion reaction of organic carbon through carbon activation, while the high ash content of the product in Comparative Example 4 causes a sharp decrease in its specific surface area, greatly reducing the adsorption performance of the product.

[0116] The activated carbon obtained by the direct coal liquefaction residue extraction and coal powder molding and carbon activation in this application has a relatively large specific surface area. The specific surface area of ​​the product in Example 2 reaches 620m 2 / g, the specific surface area of ​​the product in Example 4 is 590m 2 / g, both meet the index requirements of activated carbon products for sewage treatment.

[0117] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for treating coal direct liquefaction residue, characterized in that: The following steps are involved: (1) mixing the coal direct liquefaction residue and an extractant to obtain an extraction system, and performing solid-liquid separation on the extraction system to obtain a filtrate and a filter residue; (2) distilling the filtrate to obtain refined asphalt; (3) Drying the filter residue to obtain a solid, and pyrolyzing the solid to obtain pyrolysis oil.

2. The method for treating the direct coal liquefaction residue according to claim 1, characterized in that: The extractant comprises a light extractant and a heavy extractant, the final distillation point of the light extractant is less than 220°C, and the initial distillation point of the heavy extractant is greater than or equal to 220°C.

3. The method for treating the direct coal liquefaction residue according to claim 2, characterized in that: The light extractant includes one or more of tetrahydrofuran, N-methylpyrrolidone and tetralin; And / or, the heavy extractant includes coking wash oil and / or coking anthracene oil.

4. The method for treating the direct coal liquefaction residue according to any one of claims 1 to 3, characterized in that: The mass ratio of the coal direct liquefaction residue to the extractant is 1:(1-10); And / or, the extraction temperature is 20-180° C., and the extraction time is 30-90 min.

5. The method for treating the direct coal liquefaction residue according to claim 1, characterized in that: The drying temperature is 100-300° C., and the drying time is 1-5 hours.

6. The method for treating the direct coal liquefaction residue according to claim 1, characterized in that: The method for treating the coal direct liquefaction residue also includes the steps of: mixing the solid matter, the binder, the coal powder and the activator aqueous solution, performing pyrolysis and activation treatment to obtain pyrolysis oil and adsorption material.

7. The method for treating the direct coal liquefaction residue according to claim 6, characterized in that: The mass ratio of the solid matter, the binder and the coal powder is (2-3): (1-2): (10-20); and / or, the amount of the activator aqueous solution added is 5%-10% of the total weight of the solid matter, the binder and the coal powder; And / or, the pyrolysis temperature is 300-600°C; And / or, the activation temperature is 800-950°C, and the activation time is 90-120min; and / or, the binder comprises coal tar and / or coal pitch; and / or, the particle size of the coal powder is less than or equal to 0.2 mm; And / or, the activator comprises one or more of KOH, NaOH and phosphoric acid; And / or, the mass concentration of the activator aqueous solution is 10%-20%.

8. The method for treating the direct coal liquefaction residue according to claim 7, characterized in that: When the extractant is a light extractant, the pyrolysis temperature is 500-600°C, and the pyrolysis treatment time is 1-6h; Preferably, when the extractant is a heavy extractant, the pyrolysis includes a first stage pyrolysis and a second stage pyrolysis, the temperature of the first stage pyrolysis is 300-400°C, and the time of the first stage pyrolysis is 2-8h; the temperature of the second stage pyrolysis is 500-600°C, and the time of the second stage pyrolysis is 1-6h.

9. The method for treating the direct coal liquefaction residue according to claim 1, characterized in that: The method for treating the coal direct liquefaction residue also includes the steps of: subjecting the pyrolysis product to oil and gas buffering treatment to separate the pyrolysis oil and pyrolysis gas obtained by pyrolysis; and the pyrolysis gas provides energy for pyrolysis.

10. The method for treating the direct coal liquefaction residue according to claim 9, characterized in that: The equipment for implementing pyrolysis is a pyrolysis furnace; And / or, the equipment for implementing the oil and gas buffering treatment is a stabilization tower. Preferably, the pyrolysis gas is discharged through the gas outlet of the stabilization tower to provide energy for the pyrolysis furnace.

Images