Oil shale and high-sodium coal coupling deep processing system and process

Abstract

The application provides a coupling deep processing system and process for oil shale and high-sodium coal, which can effectively solve the comprehensive utilization problem of oil shale and the problem of high-sodium coal as gasification coal, and can realize efficient utilization of energy. The system comprises a drying and dewatering unit, a dry distillation unit, a deep processing unit, a water-coal-oil slurry preparation unit and a gasification unit; the drying and dewatering unit is used for drying and dewatering oil shale; the dry distillation unit is used for receiving the dried oil shale and performing dry distillation on the oil shale; the deep processing unit is used for separating oil and water from shale oil and processing the shale oil; the water-coal-oil slurry preparation unit is used for receiving high-sodium coal, oil shale semi-coke and oil-containing wastewater and preparing water-coal-oil slurry; the gasification unit is used for performing gasification reaction of the water-coal-oil slurry and a gasification agent; the gasification unit and the dry distillation unit are connected through a synthesis gas output pipe; and the dry distillation unit and the drying and dewatering unit are connected through a coal gas output pipe.

Description

Technical Field

[0001] This invention relates to the field of deep processing technology for oil shale and high-sodium coal, specifically to a coupled deep processing system and process for oil shale and high-sodium coal. Background Technology

[0002] High-sodium coal suffers from problems such as slagging, ash accumulation, pipe wall fouling, and high-temperature corrosion during gasification. Entrained gasification technology, with its advantages of high gasification temperature, high gasification pressure, and wide applicability to various coal types, has become the mainstream direction for coal gasification technology development. Due to its high gasification temperature, the temperature of the syngas produced is also relatively high, and the fly ash particles remain in a molten state. During the quenching process, if the quenching amount is insufficient or the quenching temperature is too high, the molten fly ash easily adheres to the heat exchanger surface. This adhered fly ash continues to adhere to other fly ash particles, ultimately leading to fly ash deposition. Therefore, the ash accumulation problem on the heat exchanger surface has become a significant factor affecting the efficient and stable operation of entrained gasifiers. How to reduce the negative effects of sodium in high-sodium coal during coal processing and utilization is a major technical challenge for achieving the clean utilization of abundant high-sodium coal reserves.

[0003] The primary purpose of oil shale development and utilization is to produce shale oil. Currently, low-temperature dry distillation technology is mainly used. However, the main bottleneck restricting the development of this technology is the utilization of coal gas and dry distillation waste residue, especially the recovery and utilization of fixed carbon in oil shale semi-coke. Oil shale contains a large amount of minerals, resulting in a large amount of shale ash residue produced during combustion or dry distillation, accounting for almost 60%-80% of the oil shale processing volume. If this ash residue is not utilized during development and utilization, it will inevitably become an obstacle to the industry's development. In addition, the wastewater generated from oil shale dry distillation contains oily substances, water-soluble organic matter, and inorganic matter, which is currently difficult to treat with industrial technology. Even if treated, it is difficult to meet national emission standards, and it requires a large land area and is costly.

[0004] CN116557851A discloses a combustion system and process for ultra-low calorific value oil shale and oil shale dry distillation semi-coke, belonging to the field of oil shale resource utilization technology. It includes a fluidized bed boiler, with a cyclone separator installed at the boiler outlet. A return material device is connected to the bottom of the cyclone separator, and the return material device is connected to the fluidized bed boiler via a return material inclined pipe. The top of the cyclone separator is connected to a flue gas duct. A coal feed hopper is connected to the fluidized bed boiler via a first coal conveying pipeline and to the return material inclined pipe via a second coal conveying pipeline. A superheater and evaporative heating surface are installed at the top of the flue gas duct, and an air preheater and economizer are arranged at the bottom of the flue gas duct. A primary air box is installed at the bottom of the fluidized bed boiler, and secondary air boxes are installed on the front and rear walls and / or side walls of the water-cooled wall of the fluidized bed boiler. The flue gas duct is connected to the primary and secondary air boxes. This invention improves the boiler's combustion efficiency while ensuring the ignition, stable combustion, and complete combustion of ultra-low calorific value fuel. This invention uses oil shale and oil shale semi-coke for direct combustion, which has a low added value to the utilization of oil shale. Moreover, because oil shale has a high ash content, the ash and slag treatment methods in the gasification process are different (gasification uses liquid slag discharge and fly ash washing). Direct combustion results in a large amount of fly ash, which increases the load on subsequent ash treatment in the boiler and is prone to causing equipment scaling.

[0005] CN117165334A discloses a method for reducing sodium release from high-alkali coal. The method is as follows: high-alkali coal and additives are crushed and screened separately to obtain 160-200 mesh particles. The high-alkali coal and additives are then uniformly mixed in a specific ratio. The additives are added at a ratio of 1-10% of the high-alkali coal, including 5-10% silica, 5-10% alumina, and 80-90% phosphorus-containing additives. The mixture is then gasified in a high-temperature planar flame-carried flow reactor to elucidate the influence of the additives on the sodium release characteristics of alkali metals in high-alkali coal under actual fluidized bed gasification conditions. This invention can effectively suppress the release of sodium alkali metals from high-alkali coal and increase the melting temperature of the gasification ash, effectively alleviating problems such as dust accumulation, contamination, and corrosion caused by sodium alkali metal release during the gasification process of high-alkali coal, and contributing to the resource utilization of high-alkali coal.

[0006] CN114854437B discloses a method and system for reducing the slagging characteristics of high-sodium coal. By pre-pyrolyzing the high-sodium coal, the residual sodium content is reduced, promoting the formation of high-melting-point sodium-containing aluminosilicates, thus reducing the slagging tendency of high-sodium coal at its source. Since insoluble sodium in the form of aluminosilicates has a high melting point and thermal stability, it poses less harm during combustion, achieving high-quality and clean utilization of coal. One aspect of this invention provides a method for reducing the slagging characteristics of high-sodium coal based on pyrolysis-combustion coupling technology, comprising the following steps: mixing the high-sodium coal with a heat carrier from a combustion furnace in a pyrolysis furnace and subjecting it to a pyrolysis reaction, wherein the fluidizing medium of the pyrolysis furnace is coal gas. A second aspect of this invention also provides a system for reducing the slagging characteristics of high-sodium coal based on pyrolysis-combustion coupling technology, comprising: a combustion furnace that generates a heat carrier; and a pyrolysis furnace that mixes the high-sodium coal and the heat carrier and subjects them to a pyrolysis reaction, wherein the fluidizing medium of the pyrolysis furnace is coal gas. This invention first involves pyrolyzing high-sodium coal to reduce its sodium content. However, coal pyrolysis occurs in an anaerobic or low-oxygen environment, where lighter components volatilize to form coke, condensable liquids, and gaseous products. Generally, most of the sodium in high-sodium coal is water-soluble, making it highly susceptible to volatilization along with the lighter components. This leads to scaling or blockage in downstream pipelines and equipment used for these lighter components after pyrolysis, disrupting the continuous operation of the pyrolysis process. Therefore, this invention merely shifts the problem from one process to another and does not truly solve the problems associated with high-sodium coal. Summary of the Invention

[0007] This invention provides a deep processing system and process for coupling oil shale and high-sodium coal. By using the system and process of this invention, not only can the comprehensive utilization problem of oil shale be effectively solved, but also the problems of using high-sodium coal as gasification coal can be solved. At the same time, through ingenious coupling, energy efficiency can also be achieved.

[0008] To achieve its objective, the present invention provides the following technical solution:

[0009] This invention provides a deep processing system for oil shale coupled with high-sodium coal, the system comprising a drying and dehydration unit, a carbonization unit, a deep processing unit, a water-coal-oil slurry preparation unit, and a gasification unit;

[0010] The drying and dehydration unit is used to dry and dehydrate the crushed oil shale to obtain dried oil shale.

[0011] The pyrolysis unit is used to receive the dried oil shale and pyrolyze it to obtain coal gas, shale oil and oil shale semi-coke;

[0012] The deep processing unit is used to separate and process the shale oil to obtain oily wastewater and oil products;

[0013] The water-coal-oil slurry preparation unit is used to receive the high-sodium coal, the oil shale semi-coke, and the oily wastewater and to prepare the water-coal-oil slurry.

[0014] The gasification unit is used to react the water-coal-oil slurry with the gasifying agent to obtain syngas and gasification residue.

[0015] The gasification unit and the pyrolysis unit are connected by a syngas output pipe for exchanging heat between the syngas obtained from the gasification unit and the pyrolysis unit; the pyrolysis unit and the drying and dehydration unit are connected by a coal gas output pipe for passing the coal gas obtained from the pyrolysis unit as fuel into the drying and dehydration unit for combustion to provide heat.

[0016] Preferably, it further includes a blending unit for receiving high-sodium coal and the oil shale semi-coke obtained from the dry distillation unit and pre-mixing the two; the water-coal-oil slurry preparation unit is connected to the blending unit to receive the pre-mixed high-sodium coal and the oil shale semi-coke.

[0017] Preferably, it further includes a dust removal and purification unit for removing dust and purifying the syngas that has undergone heat exchange with the dry distillation unit, so as to obtain purified syngas.

[0018] In some embodiments, the syngas obtained by the gasification unit exchanges heat with the pyrolysis unit through indirect heat exchange.

[0019] Preferably, it also includes a gasification slag processing unit for processing the gasification slag as a raw material into building materials.

[0020] This invention also provides a process for the coupled deep processing of oil shale and high-sodium coal using the aforementioned oil shale and high-sodium coal coupled deep processing system, comprising the following steps:

[0021] After the oil shale is crushed, it is sent to the drying and dehydration unit for drying and dehydration to obtain dried oil shale; the heat required by the drying and dehydration unit is the heat generated by the combustion of the coal gas obtained in the carbonization unit;

[0022] The dried oil shale is fed into the pyrolysis unit for pyrolysis to obtain coal gas, shale oil, and oil shale semi-coke. The pyrolysis unit obtains the heat required for the pyrolysis by exchanging heat with the syngas obtained from the gasification unit. The coal gas is output to the drying and dehydration unit through the coal gas output pipe for combustion to provide the heat required for the drying and dehydration.

[0023] The shale oil is fed into the deep processing unit for oil-water separation and processing to obtain oily wastewater and oil products.

[0024] High-sodium coal, the oil shale semi-coke, and the oily wastewater are mixed in the water-coal-oil slurry preparation unit to prepare water-coal-oil slurry;

[0025] The water-kerosene slurry is fed into the gasification unit and reacts with the gasifying agent to produce syngas and gasification residue. The syngas obtained from the gasification unit is output through the syngas output pipe and exchanges heat with the dry distillation unit.

[0026] Preferably, the high-sodium coal and the oil shale semi-coke are pre-mixed in the blending unit and then fed into the water-coal-oil slurry preparation unit.

[0027] And / or, the syngas that has undergone heat exchange in the pyrolysis unit is sent to a dust removal and purification unit for dust removal and purification to obtain purified syngas; preferably, the purified syngas is used as a raw material for the production of chemicals;

[0028] And / or, the gasified slag is fed into a gasified slag processing unit and used as a raw material for processing building materials.

[0029] Furthermore, the gasification temperature of the gasification unit for the gasification reaction is 1200℃~1500℃, and the gasification pressure is 4.0~8.5MPa, preferably 4.0~6.0MPa.

[0030] Preferably, the vaporization temperature is 1250℃~1350℃.

[0031] In some embodiments, the water content of the dried oil shale is less than 6 wt%, preferably less than 3 wt%;

[0032] And / or, the drying temperature of the drying and dehydration unit is 100-200℃, preferably 105-120℃;

[0033] And / or, the pyrolysis temperature in the pyrolysis unit is 400-600℃, preferably 450-500℃;

[0034] And / or, in the pyrolysis unit, the temperature of the synthesis gas after the heat exchange is 600°C to 800°C;

[0035] And / or, the oil products obtained in the deep processing unit include diesel and / or gasoline;

[0036] And / or, when preparing the water-coal-oil slurry, the ratio of the mass of the oil shale semi-coke used to the mass of the high-sodium coal used does not exceed 15:100;

[0037] And / or, the solids content of the water-kerosene slurry is not less than 50 wt%, preferably 50-70 wt%, more preferably 60-65 wt%.

[0038] The technical solution provided by this invention has the following beneficial effects:

[0039] The system and process of this invention can effectively address both the efficient comprehensive utilization of existing oil shale resources and the applicability of high-sodium coal as gasification coal. The crushed oil shale is dried and dehydrated in a drying and dehydration unit, then subjected to dry distillation in a retorting unit. The gas produced during dry distillation is returned to the drying and dehydration unit for combustion and heating. The shale oil produced during dry distillation is sent to a deep processing unit to obtain oil products and oily wastewater. The oil shale semi-coke and high-sodium coal produced during dry distillation are mixed with the oily wastewater from the deep processing unit to form a water-coal-oil slurry, which is then reacted with a gasifying agent. The resulting high-temperature syngas is fed into the retorting unit for heat exchange and heating. Through this coupled system, not only can oil shale be fully and comprehensively utilized, but the problem of fly ash deposition and scaling caused by high-sodium coal leading to difficulty in long-term stable operation of the gasifier is also solved. Furthermore, this invention achieves efficient energy utilization within the system through ingenious coupling. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a deep processing system that couples oil shale and high-sodium coal in one embodiment. Detailed Implementation

[0041] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" may be used herein to include any and all combinations of one or more of the associated listed items.

[0043] See Figure 1 This invention provides a deep processing system coupled with oil shale and high-sodium coal. The system mainly includes a drying and dehydration unit, a dry distillation unit, a deep processing unit, a water-coal-oil slurry preparation unit, and a gasification unit.

[0044] The drying and dehydration unit is used to dry and dehydrate the crushed oil shale to obtain dried oil shale.

[0045] The pyrolysis unit is used to receive the dried oil shale obtained from the drying and dehydration unit, and to pyrolyze the dried oil shale to obtain coal gas, shale oil and oil shale semi-coke;

[0046] The deep processing unit is used to separate and process the shale oil obtained from the dry distillation unit to obtain oily wastewater and oil products, such as gasoline and / or diesel.

[0047] The coal-water slurry preparation unit is used to receive high-sodium coal, oil shale semi-coke from the dry distillation unit, and oily wastewater from the deep processing unit, and to prepare coal-water slurry to obtain coal-water slurry.

[0048] The gasification unit is used to react the water-oil slurry obtained from the water-oil slurry preparation unit with the gasifying agent to produce syngas and gasification residue.

[0049] The gasification unit and the pyrolysis unit are connected by a syngas output pipe, which is used to exchange heat between the syngas obtained from the gasification unit and the pyrolysis unit. Specifically, the syngas is exchanged with the pyrolysis reactor in the pyrolysis unit to provide the heat required by the pyrolysis unit. The pyrolysis unit and the drying and dehydration unit are connected by a coal gas output pipe, which is used to pass the coal gas obtained from the pyrolysis unit as fuel into the drying and dehydration unit for combustion, so as to provide the heat required for drying and dehydration by the combustion of coal gas.

[0050] Preferably, it also includes a mixing unit for receiving high-sodium coal and oil shale semi-coke obtained from the dry distillation unit and pre-mixing the two; the water-coal-oil slurry preparation unit is connected to the mixing unit, thereby receiving the pre-mixed high-sodium coal and oil shale semi-coke in the mixing unit, that is, the high-sodium coal and oil shale semi-coke are pre-mixed in the mixing unit and then sent to the water-coal-oil slurry preparation unit.

[0051] Preferably, it also includes a dust removal and purification unit for removing dust and purifying the syngas that has undergone heat exchange with the dry distillation unit, thereby obtaining purified syngas that can be used as a raw material for synthesizing chemicals (e.g., C1 chemicals).

[0052] In some specific implementations, the syngas obtained from the gasification unit exchanges heat with the pyrolysis unit through indirect heat exchange, thereby providing heat to the pyrolysis unit.

[0053] Preferably, it also includes a gasification slag processing unit for processing gasification slag into building materials.

[0054] The system of this invention effectively addresses both the efficient and comprehensive utilization of existing oil shale resources and the applicability of high-sodium coal as gasification coal. Crushed oil shale is dried and dehydrated in a drying and dehydration unit, then subjected to pyrolysis in a carbonization unit. The resulting gas is returned to the drying and dehydration unit for combustion and heating. The shale oil produced during carbonization is sent to a deep processing unit to produce gasoline, diesel, and other oil products, as well as oily wastewater. The semi-coke from the carbonization process is mixed with high-sodium coal and then combined with the oily wastewater from the deep processing unit to form a water-coal-oil slurry. This slurry, along with a gasifying agent, is then fed into a gasification unit for gasification. The resulting high-temperature syngas is fed back to the carbonization unit for heat exchange. After purification, the syngas can be used to synthesize chemicals, while the gasification slag can be used to produce building materials. The coupling system of this invention not only enables the full and comprehensive utilization of oil shale, but also solves the problem that high-sodium coal used for gasification is prone to fly ash deposition and scaling, which makes it difficult for gasifiers to operate stably for a long period of time. At the same time, the coupling process of this invention also realizes the efficient utilization of energy within the system.

[0055] This invention also provides a process for the coupled deep processing of oil shale and high-sodium coal using the aforementioned oil shale and high-sodium coal coupled deep processing system, comprising the following steps:

[0056] After the oil shale is crushed, for example to a particle size of 10-50 mm, it is sent to a drying and dehydration unit for drying and dehydration to obtain dried oil shale; the heat required for drying and dehydration in the drying and dehydration unit is the heat generated by the combustion of the coal gas obtained in the carbonization unit.

[0057] The dried oil shale is fed into the pyrolysis unit for pyrolysis to obtain coal gas, shale oil and oil shale semi-coke; the pyrolysis unit obtains the heat required for pyrolysis by exchanging heat with the high-temperature syngas obtained from the gasification unit; the coal gas obtained from the pyrolysis unit is output to the drying and dehydration unit for combustion through the coal gas output pipe, and the combustion of coal gas provides the heat required for the drying and dehydration unit to perform drying and dehydration.

[0058] The shale oil obtained from the carbonization unit is sent to the deep processing unit for oil-water separation and processing to obtain oily wastewater and oil products, such as gasoline and / or diesel. Processing may involve hydrogenating the crude oil obtained from oil-water separation to obtain gasoline, diesel, etc. The extraction of gasoline, diesel, and other oil products from shale oil through oil-water separation and processing can be carried out using conventional technologies well-known in the field, without particular limitations, and will not be elaborated upon further.

[0059] High-sodium coal, oil shale semi-coke obtained from the dry distillation unit, and oily wastewater obtained from the deep processing unit are sent to the water-coal-oil slurry preparation unit to prepare water-coal-oil slurry.

[0060] The water-coal-oil slurry prepared by the water-coal-oil slurry preparation unit is sent to the gasification unit to react with the gasifying agent to produce syngas and gasification residue. The high-temperature syngas obtained by the gasification unit is output through the syngas output pipe and exchanges heat with the dry distillation unit, thereby providing heat for the dry distillation unit.

[0061] Preferably, high-sodium coal and oil shale semi-coke are pre-mixed in the blending unit and then sent to the water-coal-oil slurry preparation unit for water-coal-oil slurry preparation.

[0062] Preferably, the syngas that has undergone heat exchange in the dry distillation unit is sent to the dust removal and purification unit for dust removal and purification to obtain purified syngas; the purified syngas is used as a raw material for the production of chemicals, such as C1 chemicals.

[0063] Preferably, the gasification slag obtained from the gasification unit is fed into the gasification slag processing unit, and the gasification slag is used as a raw material to process building materials, such as cement, bricks, gypsum, etc.

[0064] Specifically, the gasification temperature of the gasification unit for the gasification reaction is 1200℃~1500℃, and the gasification pressure is 4.0~8.5MPa, preferably 4.0~6.0MPa. More preferably, the gasification temperature is 1250℃~1350℃. Using this preferred gasification temperature, the water-coal-oil slurry prepared from oil shale semi-coke, high-sodium coal, and oily wastewater exhibits better gasification performance. This not only facilitates higher syngas production and a higher effective gas content in the syngas, but also avoids intermittent slag blockage caused by poor slag discharge, and eliminates the need for more stringent gasifier refractory requirements. This extends the gasifier's lifespan, improves process stability, and further extends the stable operating cycle. The inventors have discovered that when a water-coal-oil slurry prepared by blending high-sodium coal and oil shale semi-coke is gasified in a gasifier, a gasification temperature below 1250℃, compared to a gasification temperature controlled between 1250℃ and 1350℃, results in a decrease in the CO and H2 content of the syngas and a reduction in the overall syngas yield. This can lead to intermittent slag blockage due to poor high-temperature slag discharge. While a gasification temperature above 1350℃, compared to a temperature controlled between 1250℃ and 1350℃, increases the effective gas content and syngas yield, the higher gasification temperature also imposes more stringent refractory requirements on the gasifier, which is detrimental to extending the gasifier's lifespan.

[0065] Specifically, the drying and dehydration unit can employ a rotary kiln for drying and dehydration. For example, oil shale rotates within the kiln, with gas combustion in the center providing heat for dehydration, used to heat the oil shale particles for dehydration. In some examples, the drying temperature in the drying and dehydration unit is 100-200°C, preferably 105-120°C. In some examples, the moisture content of the dried oil shale obtained in the drying and dehydration unit is less than 6 wt%, preferably less than 3 wt%.

[0066] The heat required for the pyrolysis unit comes from the waste heat of the high-temperature syngas produced by the gasification unit. Preferably, the syngas produced by the gasification unit exchanges heat indirectly with the pyrolysis reactor in the pyrolysis unit; for example, the high-temperature syngas flows through the tube side, and the oil shale particles flow through the shell side. In some examples, the pyrolysis temperature in the pyrolysis unit is 400-600℃, preferably 450-500℃; and the temperature of the syngas after heat exchange in the pyrolysis unit is 600℃-800℃.

[0067] Preferably, when preparing the water-coal-oil slurry, the ratio of the mass of the oil shale semi-coke used to the mass of the high-sodium coal used does not exceed 15:100, for example, 0.1:100, 1:100, 5:100, 10:100, 13:100, 15:100, etc.

[0068] In some examples, the solids content of the water-kerosene slurry prepared in the water-kerosene slurry preparation unit is not less than 50 wt%, preferably 50-70 wt%, and more preferably 60-65 wt%. The prepared water-kerosene slurry is pumped to the gasification unit via a coal slurry pump. Specifically, the gasification unit may be an entrained flow gasifier. The gasifying agent used in the gasification unit is, for example, oxygen.

[0069] Unless otherwise specified, the specific equipment or operations involved in the system and process of this invention are all existing or conventional technologies well known to those skilled in the art, and will not be described in detail.

[0070] Compared with existing technologies, the oil shale and high-sodium coal coupled deep processing system and process provided by this invention have the following beneficial technical effects:

[0071] (1) The waste heat carried by the high-temperature syngas generated in the gasifier of the gasification unit is used to provide heat for the dry distillation of oil shale, so that the heat energy of the entire gasification process is fully utilized and does not affect the dry distillation and gasification performance, resulting in high overall process efficiency.

[0072] (2) The main components of oil shale semi-coke are SiO2 and Al2O3. This invention cleverly mixes high-sodium coal with oil shale semi-coke so that most of the sodium will eventually exist in the form of aluminosilicates, thereby reducing the tendency of fly ash deposition. In addition, if oil shale is directly mixed with high-sodium coal for gasification in the gasification unit, it will be difficult to make deep utilization of oil shale. For example, it will lead to the inability to produce shale oil. Moreover, oil shale has a high oil content. Directly mixing it with high-sodium coal will result in high viscosity and difficulty in grinding to obtain water-coal-oil slurry suitable for gasification. However, this invention cleverly first dry distills oil shale to extract shale oil, and then mixes oil shale semi-coke with high-sodium coal. This does not have the above-mentioned drawbacks, and can produce shale oil. The generated coal gas can also be used as fuel for heating in the system, and can solve the problem of easy scaling in high-sodium coal gasification, which makes it difficult for the system to operate stably for a long period of time.

[0073] (3) The wastewater generated from the deep processing of shale oil contains oily substances, water-soluble organic matter and inorganic matter, which is difficult to treat with current industrial technology. Even if it is treated, it is difficult to meet the national emission standards. In addition, it occupies a large area and has high cost. This invention cleverly mixes it with high-sodium coal and oil shale semi-coke to form a water-coal-oil slurry. Through gasification treatment, it not only solves the environmental protection problem of wastewater treatment, but also increases the production of gasification syngas.

[0074] (4) Oil shale semi-coke is rich in organic matter, and its use in gasification can also "fully utilize" oil shale. The coupling of the entire process can not only obtain qualified oil products, but also produce syngas (C1 chemical synthesis raw materials), and the process has low energy consumption, so the overall process added value is significantly improved.

[0075] The present invention will be further illustrated by the following embodiments, but it should not be construed as the present invention being limited to these embodiments.

[0076] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in this technical field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0077] Example 1

[0078] This embodiment adopts Figure 1 The system shown is used for the coupled deep processing of oil shale and high-sodium coal. (Regarding...) Figure 1 The system shown is described above and will not be repeated here.

[0079] Taking a gasifier pressure of 4.0 MPa and a single gasifier processing capacity of 2000 tons / day as an example, and an oil shale dry distillation processing capacity of 300 tons / day as an example, the properties of the raw coal and oil shale used are shown in Tables 1 and 2 below:

[0080] Table 1. Raw material industrial analysis and elemental analysis

[0081]

[0082] Table 2 Raw material ash composition / wt%

[0083] raw material <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[TiO2]]> <![CDATA[SO3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[P2O3]]> High-sodium coal 18.25 9.81 24.93 11.96 6.50 0.52 19.45 0.35 6.36 0.06 oil shale 63.32 28.12 2.25 2.05 0.31 1.22 0.40 0.22 0.40 0.09

[0084] The deep processing steps in this embodiment are as follows:

[0085] After the oil shale is crushed to a particle size of 20-30mm, it is sent to the drying and dehydration unit for drying and dehydration. The heat required for the drying and dehydration unit is the heat generated by burning the coal gas obtained in the dry distillation unit as fuel in the drying and dehydration unit. The oil shale particles are heated by the combustion of coal gas. The drying temperature is 105-110℃. The water content of the dried oil shale is 3wt%.

[0086] The dried oil shale is fed into a pyrolysis unit for pyrolysis to obtain coal gas, shale oil, and oil shale semi-coke. The pyrolysis unit obtains the heat required for pyrolysis by indirectly exchanging heat with the syngas obtained from the gasification unit. The coal gas obtained from the pyrolysis unit is then output to the drying and dehydration unit through a coal gas output pipe for combustion to provide heat for the drying and dehydration unit. The pyrolysis unit has a pyrolysis temperature of 500℃, a pyrolysis pressure of atmospheric pressure, and a pyrolysis processing capacity of 300t / d.

[0087] Shale oil is sent to a deep processing unit for oil-water separation to obtain oily wastewater and crude oil. The crude oil is then processed to obtain oil products such as diesel and gasoline.

[0088] High-sodium coal and oil shale semi-coke are mixed in a blending unit to obtain a mixture, wherein the mass ratio of high-sodium coal to oil shale semi-coke is 22:3. Then, the obtained mixture and oily wastewater are mixed in a water-coal-oil slurry preparation unit to prepare water-coal-oil slurry, and the solid concentration of the water-coal-oil slurry is 60wt%.

[0089] A water-kerosene slurry is fed into a gasification unit (using an entrained flow gasifier) ​​where it undergoes a gasification reaction with oxygen as the gasifying agent. The gasification temperature is 1350℃, the gasification pressure is 4.0 MPa, and the gasifier's processing capacity is 2000 t / d. The gasification unit yields syngas and gasification slag. The syngas from the gasification unit is output through a syngas outlet pipe and undergoes heat exchange with a pyrolysis unit. The syngas after heat exchange with the pyrolysis unit reaches a temperature of approximately 800℃. This syngas is then sent to a dust removal and purification unit, where it is used downstream as a raw material for the synthesis of C1 chemicals. The gasification slag is sent downstream for the processing of building materials.

[0090] The experimental results are as follows:

[0091] The main components (mol%) of the syngas produced by the gasifier are: CO: 53%, H2: 36%, CO2: 11%;

[0092] Syngas production capacity of the gasifier: 4.2 × 10⁻⁶ 6 Nm 3 / d;

[0093] Composition of gas produced by the dry distillation unit (mol%): CO: 13%, H2: 12.0%, CO2: 30%, CH4: 12.0%, C n H m : 20%, N2: 13%; among which, C n H m In the examples, n = 2-3, m = 4-8 (C in each embodiment and comparative example) n H m (Therefore, I will not go into details again.)

[0094] Gas production from the pyrolysis unit: 2.8 × 10⁻⁶ 4 Nm 3 / d;

[0095] The output of diesel, gasoline and other petroleum products in the deep processing unit is 10.5 t / d.

[0096] As can be seen from the above process indicators, the deep processing technology of oil shale and high-sodium coal coupled in this invention requires almost no additional heat for the oil shale dry distillation process, while also producing 10.5 t / d of oil as a by-product. For the gasification process, the ash composition of the mixture of high-sodium coal and oil shale semi-coke at a mass ratio of 22:3 is shown in Table 3.

[0097] Table 3 Ash composition (wt%) of high-sodium coal and oil shale semi-coke blended at a mass ratio of 22:3.

[0098] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[TiO2]]> <![CDATA[SO3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[P2O3]]> 45.03 20.69 11.46 6.07 2.82 0.94 8.13 0.27 2.82 0.08

[0099] As shown in Table 3, the blending reduced the sodium content in the high-sodium coal from 6.36% to 2.82%, and increased the silicon-aluminum content from 28% to approximately 66%. The total potassium and sodium content after blending fully meets the requirement of ≤3.5% for potassium and sodium content in coal ash in the group standard T / CCT 015-2024 "Coal for Entrained Fluidized Bed Coal-Water Slurry Gasification". Furthermore, using this blended coal sample as gasification feedstock achieved stable and long-term operation of the process system during gasification, without any shutdowns due to scaling, slag blockage, or other problems caused by feedstock issues. Meanwhile, the fly ash generated during the gasification operation in this embodiment was sampled and analyzed, and the results are shown in Table 4.

[0100] Table 4. Composition of fly ash during gasification operation (wt%)

[0101] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[TiO2]]> <![CDATA[SO3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[P2O3]]> 45.36 19.84 13.43 6.25 2.92 0.82 7.21 0.16 2.05 0.32

[0102] As can be seen from the table above, compared with the composition of the coal ash fed into the furnace, the potassium and sodium contents of the mixed fly ash are reduced, especially the sodium content, which is reduced from 2.82% to 2.05%. This indicates that potassium and sodium alkali metals are not enriched in the fly ash. The process of this invention can make most of the sodium exist in the form of aluminosilicates, so that high-sodium coal can be used as gasification coal without problems such as fly ash deposition and scaling, and the energy efficiency of the whole process can be fully utilized.

[0103] Example 2

[0104] The procedure was carried out in accordance with Example 1, except that the vaporization temperature of the vaporization unit was 1200°C.

[0105] The experimental results are as follows:

[0106] The main components (mol%) of the syngas produced by the gasifier are: CO: 51%, H2: 33%, CO2: 16%;

[0107] Syngas production capacity of the gasifier: 4.12 × 10⁻⁶ 6 Nm 3 / d;

[0108] Composition of gas produced by the dry distillation unit (mol%): CO: 13%, H2: 12.0%, CO2: 30%, CH4: 12.0%, C n H m 20% N2: 13%

[0109] Gas production from the pyrolysis unit: 2.8 × 10⁻⁶ 4 Nm 3 / d;

[0110] The deep processing unit produces 10.5 tons of diesel, gasoline, and other petroleum products per day.

[0111] The above indicators show that when the gasification temperature is 1200℃, the contents of CO and H2 are both lower than in Example 1, while the CO2 content is higher, resulting in a decrease in the overall syngas production. Additionally, at a gasification temperature of 1200℃, compared to Example 1, there is a problem with the smooth discharge of high-temperature molten slag from the gasifier.

[0112] Example 3

[0113] The procedure was carried out in accordance with Example 1, except that the vaporization temperature of the vaporization unit was 1400°C.

[0114] The experimental results are as follows:

[0115] The main components (mol%) of the syngas produced by the gasifier are: CO: 55%, H2: 36%, CO2: 9%;

[0116] Syngas production capacity of the gasifier: 4.26 × 10⁻⁶ 6 Nm 3 / d;

[0117] Composition of gas produced by the dry distillation unit (mol%): CO: 13%, H2: 12.0%, CO2: 30%, CH4: 12.0%, C n H m 20% N2: 13%

[0118] Gas production from the pyrolysis unit: 2.8 × 10⁻⁶ 4 Nm 3 / d;

[0119] The output of diesel, gasoline and other petroleum products in the deep processing unit is 10.5 t / d.

[0120] The above indicators show that when the gasification temperature is 1400℃, the contents of both CO and H2 increase, while the CO2 content decreases, resulting in an overall increase in syngas production. However, at a gasification temperature of 1400℃, more stringent high-temperature resistance requirements are placed on the gasifier to prevent damage to the refractory materials inside the gasifier due to excessively high temperatures. The outer wall temperature of the gasifier increases from approximately 200℃ to approximately 260℃ compared to Example 1.

[0121] Comparative Example 1

[0122] The process was carried out in accordance with Example 1, except that: the high-sodium coal was not coupled with oil shale for deep processing; during the preparation of coal-water slurry with high-sodium coal, no oily wastewater generated during the deep processing of oil shale semi-coke and shale oil was introduced; the solid concentration of the coal-water slurry in this comparative example was the same as that of the coal-water oil slurry in Example 1; and the process conditions for gasification of coal-water slurry prepared with high-sodium coal were the same as those in Example 1.

[0123] The experimental results are as follows:

[0124] The main components (mol%) of the syngas produced by the gasifier are: CO: 50%, H2: 31%, CO2: 19%;

[0125] Syngas production capacity of the gasifier: 3.96 × 10⁻⁶ 6 Nm 3 / d;

[0126] When high-sodium coal is used alone as the gasification feedstock, the effective gas composition and yield are lower compared to when it is blended with oil shale semi-coke, and no other by-products are generated. Furthermore, direct gasification using coal-water slurry prepared with high-sodium coal often leads to scaling problems. Sampling and analysis of the fly ash are shown in Table 5.

[0127] Table 5. Composition of fly ash in high-sodium coal gasification operation (wt%)

[0128] <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[TiO2]]> <![CDATA[SO3]]> <![CDATA[K2O]]> <![CDATA[Na2O]]> <![CDATA[P2O3]]> 44.65 18.46 11.76 6.86 3.02 0.73 5.54 0.33 6.82 0.38

[0129] As can be seen from the table above, most of the potassium and sodium in coal ash are enriched in fly ash. Compared with Examples 1-3, fly ash is more prone to deposition and scaling, which leads to frequent scaling problems in downstream pipelines. This makes the system operation unstable, with a short operating cycle and a stable operating cycle of less than 20 days, requiring frequent inspection and maintenance. In contrast, in the above embodiments of the present invention, the stable operating cycle is greater than 100 days.

[0130] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A deep processing system coupling oil shale and high-sodium coal, characterized in that, The system includes a drying and dehydration unit, a dry distillation unit, a deep processing unit, a water-coal-oil slurry preparation unit, and a gasification unit; The drying and dehydration unit is used to dry and dehydrate the crushed oil shale to obtain dried oil shale. The pyrolysis unit is used to receive the dried oil shale and pyrolyze it to obtain coal gas, shale oil and oil shale semi-coke; The deep processing unit is used to separate and process the shale oil to obtain oily wastewater and oil products; The water-coal-oil slurry preparation unit is used to receive the high-sodium coal, the oil shale semi-coke, and the oily wastewater and to prepare the water-coal-oil slurry. The gasification unit is used to react the water-coal-oil slurry with the gasifying agent to obtain syngas and gasification residue. The gasification unit and the pyrolysis unit are connected by a syngas output pipe, which is used to exchange heat between the syngas obtained by the gasification unit and the pyrolysis unit. The pyrolysis unit and the drying and dehydration unit are connected by a gas output pipe, which is used to pass the gas obtained by the pyrolysis unit into the drying and dehydration unit as fuel for combustion to provide heat.

2. The deep processing system for coupled oil shale and high-sodium coal according to claim 1, characterized in that, It also includes a blending unit for receiving high-sodium coal and the oil shale semi-coke obtained from the dry distillation unit and pre-mixing the two; the water-coal-oil slurry preparation unit is connected to the blending unit to receive the pre-mixed high-sodium coal and the oil shale semi-coke.

3. The deep processing system for coupled oil shale and high-sodium coal according to claim 1 or 2, characterized in that, It also includes a dust removal and purification unit, which is used to remove dust and purify the syngas that has undergone heat exchange with the dry distillation unit, so as to obtain purified syngas.

4. The deep processing system for oil shale and high-sodium coal coupled according to claim 1 or 2, characterized in that, The synthesis gas obtained from the gasification unit exchanges heat with the pyrolysis unit through indirect heat exchange.

5. The deep processing system for coupled oil shale and high-sodium coal according to claim 1 or 2, characterized in that, It also includes a gasification slag processing unit for processing the gasification slag into building materials.

6. A process for the coupled deep processing of oil shale and high-sodium coal using the oil shale and high-sodium coal coupled deep processing system according to any one of claims 1-5, characterized in that, Includes the following steps: After the oil shale is crushed, it is sent to the drying and dehydration unit for drying and dehydration to obtain dried oil shale; the heat required by the drying and dehydration unit is the heat generated by the combustion of the coal gas obtained in the carbonization unit; The dried oil shale is fed into the pyrolysis unit for pyrolysis to obtain coal gas, shale oil, and oil shale semi-coke. The pyrolysis unit obtains the heat required for the pyrolysis by exchanging heat with the syngas obtained from the gasification unit. The coal gas is output to the drying and dehydration unit through the coal gas output pipe for combustion to provide the heat required for the drying and dehydration. The shale oil is fed into the deep processing unit for oil-water separation and processing to obtain oily wastewater and oil products. High-sodium coal, the oil shale semi-coke, and the oily wastewater are mixed in the water-coal-oil slurry preparation unit to prepare water-coal-oil slurry; The water-kerosene slurry is fed into the gasification unit and reacts with the gasifying agent to produce syngas and gasification residue. The syngas obtained from the gasification unit is output through the syngas output pipe and exchanges heat with the dry distillation unit.

7. The process according to claim 6, characterized in that, The high-sodium coal and the oil shale semi-coke are pre-mixed in the blending unit and then sent to the water-coal-oil slurry preparation unit. And / or, the syngas that has completed the heat exchange in the pyrolysis unit is sent to the dust removal and purification unit for dust removal and purification to obtain purified syngas; And / or, the gasified slag is fed into a gasified slag processing unit and used as a raw material for processing building materials.

8. The process according to claim 7, characterized in that, The purified syngas is used as a raw material for the synthesis of chemicals.

9. The process according to claim 6 or 7, characterized in that, The gasification unit performs the gasification reaction at a temperature of 1200℃~1500℃ and a gasification pressure of 4.0~8.5MPa.

10. The process according to claim 9, characterized in that, The gasification pressure for the gasification reaction in the gasification unit is 4.0~6.0 MPa.

11. The process according to claim 9, characterized in that, The vaporization temperature is 1250℃~1350℃.

12. The process according to claim 6 or 7, characterized in that, The dried oil shale has a water content of less than 6 wt%. And / or, the drying temperature of the drying and dehydration unit is 100-200℃; And / or, the pyrolysis temperature in the pyrolysis unit is 400-600℃; And / or, in the pyrolysis unit, the temperature of the synthesis gas after the heat exchange is 600°C to 800°C; And / or, the oil products obtained in the deep processing unit include diesel and / or gasoline; And / or, when preparing the water-coal-oil slurry, the ratio of the mass of the oil shale semi-coke used to the mass of the high-sodium coal used does not exceed 15:100; And / or, the solids content of the water-kerosene slurry is not less than 50 wt%.

13. The process according to claim 12, characterized in that, The dried oil shale has a water content of less than 3 wt%. And / or, the drying temperature of the drying and dehydration unit is 105~120℃; And / or, the pyrolysis temperature in the pyrolysis unit is 450~500℃; And / or, the solids content of the water-kerosene slurry is 50-70 wt%.

14. The process according to claim 13, characterized in that, The solids content of the water-coal-oil slurry is 60-65 wt%.

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