Coal direct liquefaction pitch gasification system and gasification method

Abstract

This invention belongs to the field of coal chemical industry and relates to a gasification system and method for direct coal liquefaction of bitumen. The gasification system includes a mixer, an injection assembly, and an integrated gasifier. The mixer is located above the gasifier and has inlets for bitumen and oxygen and an outlet for a first homogeneous mixture. The integrated gasifier includes a premixing zone and a gasification reaction zone. The injection assembly is sealed and connected to the outlet of the first homogeneous mixture and has a nozzle structure for injecting the first homogeneous mixture into the premixing zone. The premixing zone has a mixing steam inlet and an outlet for discharging a second homogeneous mixture formed by the first homogeneous mixture and the mixing steam to the gasification reaction zone. The gasification reaction zone has a crude syngas outlet, a gasification slag outlet, and an inlet for receiving the second homogeneous mixture. This invention ensures uniform mixing of materials before they enter the gasification reaction zone, solving the problem of poor mixing in traditional gasifiers and improving gasification efficiency and stability.

Description

Technical Field

[0001] This invention belongs to the field of coal chemical industry and waste treatment and recycling technology, specifically relating to a gasification system and gasification method for direct coal liquefaction pitch. Background Technology

[0002] Coal direct liquefaction is one of the important technical routes for the clean and efficient utilization of coal. The coal direct liquefaction pitch produced in this process is the by-product with the largest output and the most complex properties, usually accounting for 20% to 30% of the raw coal input. This type of pitch is characterized by high viscosity, high ash content, and high metal content, and contains a large number of highly abrasive catalyst particles, making it difficult to achieve comprehensive utilization.

[0003] Currently, the main technologies for treating coal direct liquefaction bitumen include solvent extraction and gasification. Solvent extraction can recover some heavy oil components, but this process requires the recycling of large amounts of organic solvents, resulting in high energy consumption and solvent loss. More importantly, extraction cannot achieve full utilization of liquefied bitumen, leaving a large amount of high-ash residue that requires further treatment, thus failing to fundamentally solve the environmental problems.

[0004] Gasification technology can efficiently convert the organic hydrocarbon components in liquefied asphalt into hydrogen-rich syngas, while the inorganic components are discharged as glassy slag, achieving the solidification and detoxification of heavy metals. The generated syngas can be purified and used as a chemical feedstock, or it can be used to produce hydrogen through a conversion process to provide a hydrogen source for direct coal liquefaction hydrogenation units, realizing the material and energy cycle within the coal-to-oil plant.

[0005] However, traditional asphalt or heavy oil gasification processes typically involve injecting raw materials, oxidants, and regulators into a high-temperature gasifier through independent nozzles in parallel, relying on turbulent diffusion within the furnace to achieve mixing and reaction, which has the following drawbacks.

[0006] 1. Poor mixing effect: High viscosity asphalt droplets are large in size and have a small contact area with oxygen and steam, resulting in a slow reaction rate. Extremely high furnace temperature needs to be maintained to ensure conversion rate, which leads to high energy consumption and easy damage to the furnace lining. 2. Prone to coking and slag formation: Uneven mixing in certain areas can lead to coke production from asphalt pyrolysis or the formation of molten slag that is difficult to remove, affecting the long-term operation of the system. 3. Large fluctuations in syngas quality: Uneven mixing directly leads to unstable proportions of syngas components, affecting the stable operation of downstream processes; IV. High safety risks: Oxygen coming into contact with insufficiently dispersed asphalt may form an explosive mixture, posing a safety hazard. Summary of the Invention

[0007] To address the shortcomings of the existing technology, the present invention aims to provide a liquefied asphalt gasification system and method. By pre-positioning the mixing process and combining it with swirl enhancement technology, the present invention fundamentally solves the problems of poor mixing effect, easy coking and slagging, large fluctuations in syngas quality, and high safety risks in traditional gasification processes, achieving efficient, stable, and safe gasification of coal directly into asphalt.

[0008] For the above considerations, the first aspect of the present invention provides a gasification system for direct coal liquefaction pitch, the gasification system comprising a mixer, an injection assembly, and an integrated gasifier; wherein, The mixer is located above the integrated gasifier and is provided with an asphalt inlet, an oxygen inlet, and a first homogeneous mixture outlet, for mixing externally input asphalt and oxygen to form a first homogeneous mixture and discharging it. The integrated gasifier is a closed, integral structure with the top and bottom connected, consisting of a premixing zone and a gasification reaction zone from top to bottom. The injection assembly is in sealed communication with the first homogeneous mixture outlet of the mixer and has a nozzle structure for injecting the first homogeneous mixture into the premixing zone; The premixing zone is provided with a mixing steam inlet and an outlet for discharging a second homogeneous mixture formed by the first homogeneous mixture and the mixing steam to the gasification reaction zone. The gasification reaction zone is provided with an inlet for receiving a second homogeneous mixture from the premixing zone, and with a crude syngas outlet and a gasification slag outlet.

[0009] A second aspect of the present invention provides a method for processing coal direct liquefaction bitumen using the above-described gasification system, comprising the following steps: S1: Coal direct liquefaction pitch and oxygen are fed into a mixer to mix and form a first homogeneous mixture; the first homogeneous mixture is injected into a premixing zone through a spraying assembly and mixed with steam introduced through the mixing steam inlet to form a second homogeneous mixture; S2: The second homogeneous mixture enters the gasification reaction zone and undergoes a partial oxidation gasification reaction under high temperature and high pressure conditions; S3: The crude syngas generated by the reaction is discharged from the crude syngas outlet of the gasification reaction zone, and the molten gasification slag is discharged from the gasification slag outlet of the gasification reaction zone.

[0010] Advantages The present invention has the following beneficial effects: I. This invention employs an integrated gasification furnace comprising a premixing zone and a gasification reaction zone, pre-completing the material mixing process in the premixing zone. This ensures that the materials are uniformly mixed before entering the gasification reaction zone, fundamentally solving the problem of poor mixing effect in traditional furnaces. It also eliminates the risk of deflagration caused by oxygen in the furnace contacting undispersed asphalt to form an explosive mixture, significantly improving the efficiency and operational stability of the gasification reaction.

[0011] Second, the spraying component of this invention is a swirling nozzle with a swirling structure, which is uniformly arranged around the central conveying pipe to form a stable three-dimensional swirling field, so that the material is fully dispersed in the premixing zone, and the temperature and composition distribution in the gasification reaction zone are extremely uniform, resulting in stable syngas quality; the centrifugal force generated by the swirling can also achieve preliminary separation of gas and slag, reduce ash in the syngas, and reduce the load on the downstream purification section.

[0012] Third, this invention adopts a rationally arranged steam inlet. By adjusting the amount of steam introduced, the H2 / CO ratio of the syngas can be flexibly adjusted within a large range, and it can be precisely controlled within the target range, making the quality of the syngas more controllable and able to meet the production needs of various downstream chemical products. At the same time, the steam can also perform secondary atomization of the materials, further improving the mixing uniformity and making the gasification reaction conditions more stable.

[0013] Fourth, the present invention sets an annular protective gap at the connection between the premixing zone and the gasification reaction zone, and introduces protective steam to form a continuous gas curtain, which can effectively block the high temperature flame and radiant heat of the gasification reaction zone from being transferred to the premixing zone, prevent the materials in the premixing zone from reacting prematurely, and eliminate the safety risks of backfire and deflagration.

[0014] Fifth, the present invention adopts a heat recovery zone with three independent cooling water heat exchange sections, which can recover the sensible heat of high-temperature gasification slag to generate gradient steam, and reuse it in different parts of the system, thereby realizing the efficient utilization of waste heat in stages, reducing the energy consumption of system operation, and realizing the system's steam self-sufficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a gasification system for direct coal liquefaction and bitumen gasification provided by the present invention. Detailed Implementation

[0016] The technical solution and its effects of the present invention are further described below with reference to specific embodiments / examples. The following embodiments / examples are merely illustrative of the present invention and are not intended to limit it. Simple modifications made to the present invention based on the concept of the present invention are all within the scope of protection claimed by the present invention.

[0017] The first aspect of this invention provides a liquefied asphalt gasification system, comprising a mixer, an injection assembly, an integrated gasifier, and an optional heat recovery zone. This system is designed to address the high viscosity, high ash content, and high abrasiveness characteristics of liquefied asphalt. By replacing traditional in-furnace mixing with pre-mixing before the furnace, it fundamentally solves the industry pain points of traditional processes, such as poor mixing effect, easy coking and slagging, easy nozzle wear, and high safety risks, achieving efficient, stable, and safe gasification of liquefied asphalt.

[0018] Mixer In this invention, the mixer is located above the integrated gasification furnace and is provided with an asphalt inlet, an oxygen inlet and a first homogeneous mixture outlet. The mixer is used to mix externally input asphalt and oxygen to form a first homogeneous mixture and discharge it.

[0019] In some embodiments, the mixer is installed above the top of the integrated gasification furnace to forcibly shear and mix high-viscosity liquid asphalt with high-pressure oxygen to form a homogeneous aerosol mixture; the mixer can be any of the static mixer, venturi mixer or jet mixer in the art, and is equipped with multiple sets of shearing elements inside to achieve efficient mixing of high-viscosity gas and liquid phases.

[0020] Preferably, the mixer is a Venturi mixer, which can automatically draw in high-viscosity liquefied asphalt by utilizing the negative pressure generated by high-pressure oxygen in the throat section without the need for an additional booster pump; at the same time, the strong shear force generated by the high-speed oxygen flow in the throat section can break the asphalt into micron-sized droplets, which are fully mixed with oxygen to form an aerosol state, increasing the specific surface area of ​​the mixture by 1 to 2 orders of magnitude compared with traditional spraying, thus solving the problem of large asphalt droplet size and small contact area with the aerosol agent in traditional processes.

[0021] Injection assembly In this invention, the injection assembly is in sealed communication with the first homogeneous mixture outlet of the mixer and has a nozzle structure for injecting the first homogeneous mixture into the premixing zone of the integrated gasifier.

[0022] In some embodiments, the injection assembly extends from the top center of the integrated gasifier into its premixing zone.

[0023] In some embodiments, the injection assembly includes a central delivery pipe and a nozzle structure (preferably a swirling nozzle); the upper end of the central delivery pipe is sealed and connected to the first homogeneous mixture outlet of the mixer, and the lower end of the central delivery pipe extends from the top of the integrated gasifier into the premixing zone; the nozzle structure is fixedly connected to the lower sidewall of the central delivery pipe and arranged along the circumferential direction of the central delivery pipe; the nozzle structure is preferably a nozzle with a built-in swirling structure, the injection direction of the nozzle is towards the sidewall of the premixing zone, and it is inclined downward at a certain angle with the horizontal plane.

[0024] In some embodiments, the nozzle structure employs a tangential channel built-in swirling structure. As the first homogeneous mixture from the mixer flows through the tangential channel inside the swirling nozzle, a three-dimensional swirling field is naturally formed. The centrifugal force generated by the swirling flow throws heavier asphalt droplets towards the periphery of the premixing zone, where they continuously contact, collide, and exchange with the first and optional second mixing steam introduced through the mixing steam inlet of the premixing zone, ultimately achieving uniform mixing at the molecular scale. Nozzles such as those mentioned in CN221971508U, CN216513711U, and CN107353940A can also be used.

[0025] Preferably, the swirl nozzle is located in the upper half of the premixing zone, which helps to allow sufficient axial travel for the first homogeneous mixture and the mixing steam to be fully mixed.

[0026] Preferably, the number of swirling nozzles is 2 to 12, more preferably 4 to 8; they are evenly arranged along the circumference of the central conveying pipe (all swirling nozzles can be on the same horizontal plane or on different horizontal planes). This helps to evenly disperse the first homogeneous mixture across the entire cross-section of the premixing zone, avoiding excessively high local material concentrations and improving mixing uniformity.

[0027] Preferably, the downward-sloping spray direction of the swirling nozzle makes an angle of 5° to 30° with the horizontal plane, causing the second homogeneous mixture formed by the first homogeneous mixture and the mixed steam to swirl downwards at a certain angle. This angle not only helps to prolong the residence time of the second homogeneous mixture in the premixing zone and enhance the atomization mixing effect, but also allows the second homogeneous mixture to smoothly enter the gasification reaction zone, avoiding airflow turbulence.

[0028] Preferably, the swirl nozzle is a channel with a circular or elliptical cross-section, and the inner wall of the channel is overlaid with a wear-resistant alloy layer, which can resist the high-speed scouring and wear of high-ash asphalt and extend the service life of the nozzle.

[0029] In some embodiments, the number of central delivery pipes is 1 to 6, which are evenly arranged along the central axis or circumference of the premixing zone, and can be adapted to liquefied asphalt gasification systems of different processing scales.

[0030] Integrated gasifier In this invention, the integrated gasifier is the reaction vessel of the entire gasification system. It is a closed, integrated structure with the top and bottom connected, consisting of a premixing zone and a gasification reaction zone from top to bottom.

[0031] In some embodiments, the mixer is mounted above the top of the integrated gasifier, and the injection assembly extends from the top center of the integrated gasifier into its premixing zone.

[0032] In some implementations, the premixing zone and the gasification reaction zone are integrated structures, either welded as a whole or connected by flanges, sharing the same top shell. This eliminates the need for long-distance connecting pipelines between the traditional independent premixer and the gasifier. This helps reduce system leaks, improves operational stability, shortens the material transport path, reduces the transport resistance of high-viscosity asphalt, and enhances the system's continuous operation capability.

[0033] Preferably, the inner diameter of the premixing zone is smaller than the inner diameter of the gasification reaction zone, so that the premixing zone forms a relatively high-speed flow field, which enhances the material mixing effect. At the same time, the flow velocity of the second homogeneous mixture formed by the first homogeneous mixture and the mixed steam decreases after entering the gasification reaction zone, so that the high-temperature reaction is more complete.

[0034] Premixing zone In this invention, the premixing zone is further provided with a mixing steam inlet and an outlet for the second homogeneous mixture. The premixing zone is used to mix the first homogeneous mixture from the mixer with the mixing steam from the mixing steam inlet, and to discharge the resulting second homogeneous mixture to the gasification reaction zone.

[0035] In some embodiments, the mixing steam inlet includes a first mixing steam inlet and an optional second mixing steam inlet; the first mixing steam inlet is used to introduce atomized steam to atomize and mix with a first homogeneous mixture from the mixer to form a second homogeneous mixture; the second mixing steam inlet is used to introduce conditioning steam to assist in adjusting the material state of the second homogeneous mixture in the premixing zone.

[0036] Preferably, the first mixed steam inlet is located on the side wall of the premixing zone, close to the outlet of the nozzle structure of the injection assembly. In this case, the first mixed steam (atomized steam) can collide with the first homogeneous mixture ejected from the nozzle structure, subjecting the first homogeneous mixture to secondary shearing and atomization, further refining the asphalt droplet size; simultaneously, it can significantly reduce the material flow rate at the nozzle outlet, reducing the erosion and wear of the nozzle inner wall by high-ash asphalt, and extending the service life of the nozzle structure.

[0037] Preferably, the second mixed steam inlet is located at the top of the premixing zone, and more preferably, it is coaxially arranged with the central conveying pipe. In this case, the second mixed steam (regulating steam) can regulate the material state of the second homogeneous mixture entering the gasification reaction zone (e.g., adjust the temperature and carbon-oxygen ratio), thereby improving the stability of the gasification reaction.

[0038] Preferably, along the vertical central axis of the integrated gasifier body, all the mixed steam inlets (including the first mixed steam inlet and the second mixed steam inlet) are located above the nozzle structure of the injection assembly. That is, the horizontal plane where the mixed steam inlets are located is higher than the horizontal plane where the nozzle structure is located, which is beneficial to reserve sufficient space for the full mixing of steam and the first homogeneous mixture.

[0039] The inventors have discovered that the premixing zone sequentially completes three core processes: "homogeneous mixing of asphalt and oxygen, secondary mixing of the first homogeneous mixture and mixed steam, and swirling acceleration of the first homogeneous mixture." By moving the multi-step mixing process in the traditional gasification reaction zone to the premixing zone outside the furnace, the materials achieve a molecular-level uniform mixing state before entering the gasification reaction zone, significantly improving the rate and sufficiency of the subsequent gasification reaction.

[0040] Gasification reaction zone In this invention, the gasification reaction zone is provided with an inlet for receiving a second homogeneous mixture from the premixing zone, and is provided with a crude syngas outlet and a gasification slag outlet.

[0041] In some embodiments, the gasification slag outlet is located at the bottom of the gasification reaction zone, and the crude syngas outlet is located on the middle sidewall of the gasification reaction zone. The gasification reaction zone receives a second homogeneous mixture from the premixing zone and completes the gasification reaction under high temperature and high pressure conditions to generate crude syngas and molten gasification slag.

[0042] In some embodiments, the ratio of the height (or length) to the diameter of the gasification reaction zone is (1.5~4):1, which is beneficial for forming a stable three-dimensional swirling field in conjunction with the nozzle structure of the premixing zone, extending the residence time of high-viscosity asphalt material in the high-temperature zone, and improving the carbon conversion rate.

[0043] In some embodiments, the outer wall of the gasification reaction zone is surrounded by a jacketed annular protective gap structure. This annular protective gap can cover any position on the outer wall of the gasification reaction zone, including the sidewalls of the gasification reaction zone and the connection between the lower end of the premixing zone and the upper end of the gasification reaction zone, such as... Figure 1 The bolded black portion is shown in the image.

[0044] That is, the “coverage” here refers to the annular protective gap completely enveloping the corresponding outer wall area along the circumference of the gasification reaction zone, forming a surrounding jacket structure.

[0045] In some embodiments, the annular protective gap is a jacket structure with an internally closed annular cavity, which is tightly fitted with the outer wall of the gasification reaction zone to form an integrated structure; the annular protective gap is provided with a third protective steam inlet on the side facing the outside, which is connected to an external steam source, and the position of the third protective steam inlet can be flexibly set according to installation requirements; the annular protective gap is provided with a continuous third protective steam outlet on the side facing the gasification reaction zone, and the third protective steam outlet can be set on the side wall or top of the gasification reaction zone.

[0046] The flow path of the third protective steam is as follows: external steam source → third protective steam inlet → closed annular cavity of the annular protective gap → third protective steam outlet → inside the gasification reaction zone.

[0047] In some embodiments, after the third protective steam is continuously introduced from the outside, it first fills the entire annular cavity and maintains a stable positive pressure, and then uniformly enters the gasification reaction zone through the third steam outlet. This jacketed positive pressure filling structure has the following advantages: First, the continuously ejected steam forms a continuous positive pressure protective layer inside the shell of the gasification reaction zone, effectively preventing high-temperature corrosive gases in the gasification reaction zone from entering the shell connection gaps or the interior of the jacket, avoiding high-temperature corrosion and thermal fatigue damage, and significantly extending the overall service life of the reactor shell.

[0048] Second, the third protective steam acts as an inert medium to form an isolation layer, which can prevent external air from entering the reaction system. In the event of accidental damage to the furnace body, the positive pressure steam in the jacket will be quickly ejected outward to dilute the leaked flammable syngas, reduce the risk of explosion, and improve the safety of the system.

[0049] Preferably, the annular protective gap covers the connection between the lower end of the premixing zone and the upper end of the gasification reaction zone. In this case, the third protective steam outlet is preferably located at the top of the gasification reaction zone, along the connection surface between the premixing zone and the gasification reaction zone.

[0050] At this point, after the third protective steam is injected and fills the annular cavity, it is uniformly sprayed downwards parallel to the connecting surface from the continuous third steam outlet at the top, forming a continuous and dense air curtain that adheres tightly to the entire connecting surface. In addition to possessing all the general protective effects mentioned above, this arrangement can also completely block the transfer of high-temperature flames and radiant heat from the gasification reaction zone to the premixing zone through the formed continuous air curtain, preventing the asphalt-oxygen mixture in the premixing zone from reacting prematurely due to excessive temperature, fundamentally eliminating the safety risks of backfire and deflagration in the premixing process before the furnace.

[0051] Preferably, the width of the third protective steam outlet is 1-15 mm, more preferably 2-10 mm. This range ensures that the steam is ejected at a suitable flow rate to form a continuous and dense positive pressure layer or gas curtain, without interfering with the mixing flow field of the premixing zone or the swirling flow field of the gasification reaction zone due to excessively high flow rate, while minimizing steam consumption.

[0052] Preferably, the number of the third protective steam outlets is 2 to 8, and they are evenly arranged along the circumferential direction at the top of the gasification reaction zone. This helps to ensure that the distribution of steam ejection is completely uniform, thereby making the thickness of the positive pressure layer or gas curtain uniform and covering the entire protective area without any dead angles.

[0053] Preferably, the third protective steam originates from the third recovered steam generated by the optionally set heat recovery zone, which can realize the cascade utilization of the system's waste heat and reduce the overall operating energy consumption.

[0054] Heat recovery zone The gasification system of the present invention may optionally include a heat recovery zone located below the gasification slag outlet of the gasification reaction zone, for recovering the sensible heat of the high-temperature gasification slag and converting it into water vapor for use by the system, thereby realizing internal energy self-circulation.

[0055] In some embodiments, the upper end of the heat recovery zone is sealed and connected to the high-temperature gasification slag outlet of the gasification reaction zone, and the lower end is sealed and connected to the slag pool of the low-level gasification slag. A water-cooled heat exchange method is adopted, in which water vapor and low-temperature gasification slag are generated by exchanging heat between cooling water and the downward-flowing high-temperature gasification slag.

[0056] Preferably, three independent cooling water heat exchange sections are provided from top to bottom along the flow direction of the gasified slag, corresponding to the generation of three stages of recovered steam with successively decreasing temperatures (i.e., first recovered steam, second recovered steam, and third recovered steam), which are respectively reused to the first mixed steam inlet, the second mixed steam inlet, and the protective steam inlet of the premixing zone; wherein the first recovered steam has a higher temperature and can be used as atomizing steam; the second recovered steam has a lower temperature and can be used as regulating steam; the third recovered steam has a lower temperature and can be used as a protective air curtain at the connection between the premixing zone and the gasification reaction zone, so as to achieve the cascaded and efficient utilization of waste heat.

[0057] A second aspect of the present invention provides a method for processing coal liquefaction pitch using the gasification system described above for coal liquefaction pitch gasification.

[0058] In some embodiments, the raw material processed by the method is direct coal liquefaction pitch with a carbon content of not less than 60 wt%. This system extracts carbon from the raw material and converts it into syngas, achieving the recycling of carbon within the coal-to-oil plant. The method sequentially includes premixing, gasification reaction, and product separation steps, optionally including heat recovery and steam self-circulation steps. By combining premixing in the premixing zone with enhanced gasification through swirling in the gasification reaction zone, the gasification challenges of high-viscosity, high-ash, and highly abrasive materials like direct coal liquefaction pitch are solved.

[0059] The typical composition of the coal direct liquefaction pitch is as follows: C content is 70-85 wt%, H content is 3-6 wt%, ash content is 10-20 wt%, volatile matter content is 30-40 wt%, and fixed carbon content is 45-55 wt%.

[0060] Premixing step In some embodiments, the premixing step is as follows: coal direct liquefaction pitch and oxygen are fed into a mixer to mix and form a first homogeneous mixture; then the first homogeneous mixture is injected into the premixing zone through a spraying assembly and mixed with the steam introduced through the mixing steam inlet to form a second homogeneous mixture.

[0061] In some implementations, a second mixing steam can be selectively introduced according to the operating conditions to help adjust the temperature and composition of the first homogeneous mixture; at the same time, a third protective steam can be selectively introduced to form a protective gas curtain at the connection between the premixing zone and the gasification reaction zone.

[0062] Preferably, the feed temperature of the direct coal liquefaction pitch is 120~200 ℃, and the feed pressure is 2.0~8.0 MPa; the oxygen purity is ≥90%, and the feed pressure is 0.2~0.5 MPa higher than that of the raw material; the mass ratio of raw material to oxygen is (1.4~1.8):1, and the mixing time of the two in the mixer is 0.1~1.0 s, which can form a uniformly dispersed aerosol state.

[0063] Preferably, the first mixed steam is atomized steam with a temperature of 200~350℃ and a pressure of 3.0~9.0MPa; the first mixed steam collides with the first homogeneous mixture sprayed from the nozzle structure, and performs secondary shearing and atomization on the first homogeneous mixture, further refining the size of the asphalt droplets.

[0064] Preferably, the second mixed steam is regulating steam with a temperature of 180~300 ℃ and a pressure of 2.5~8.5 MPa; the second mixed steam precisely regulates the temperature and carbon-oxygen ratio of the material entering the gasification reaction zone.

[0065] Preferably, the temperature of the third protective steam is 150~220 ℃ and the pressure is 2.0~8.0 MPa; the protective steam fills the cavity of the annular protective gap and is then evenly sprayed out from the inner annular gap to form a continuous air curtain, which blocks high-temperature radiant heat.

[0066] Preferably, the mass ratio of the total steam formed by the first mixed steam and the optional second mixed steam to the coal direct liquefaction bitumen is (0.2~0.5):1.

[0067] Gasification reaction and product separation step In some embodiments, the gasification reaction and product separation steps are as follows: the second homogeneous mixture enters the gasification reaction zone and undergoes a partial oxidation gasification reaction under high temperature and high pressure conditions; the crude syngas and molten gasification slag generated by the reaction are discharged from the side wall and bottom of the gasification reaction zone, respectively.

[0068] In some embodiments, the first homogeneous mixture forms a stable three-dimensional rotating vortex after being ejected through the nozzle structure, making the temperature and concentration fields in the reaction zone more uniform, while using the centrifugal force of the swirling flow to achieve the initial separation of crude syngas and molten ash.

[0069] Preferably, the gasification reaction temperature is 1200~1700 ℃, the pressure is 0.1~6.0 MPa, and the residence time of the second homogeneous mixture in the gasification reaction zone is 1.0~5.0 s, which helps to reduce the furnace lining heat load while ensuring carbon conversion rate.

[0070] Preferably, the temperature of the crude syngas leaving the gasification reaction zone is 1300~1400 ℃, the dry basis effective gas (CO+H2) content is ≥89%, the carbon conversion rate is ≥99.5%, and the residual carbon in the gasification slag is ≤0.5%.

[0071] Heat recovery and steam self-circulation step In some embodiments, the heat recovery and steam self-circulation are optional steps used to recover the sensible heat of the gasification slag and achieve system steam self-sufficiency.

[0072] In some implementations, after the high-temperature gasification slag enters the heat recovery zone, it exchanges heat with the three-stage cooling water in a countercurrent manner to generate three-stage recovered steam with a temperature gradient distribution. The first recovered steam with the highest temperature is recycled to the premixing zone as atomizing steam, the second recovered steam with the next highest temperature is recycled to the premixing zone as regulating steam, and the third recovered steam with the lowest temperature is recycled to the annular protective gap as protective steam, thereby achieving efficient utilization of waste heat in stages.

[0073] Example 1 I. Gasification System The coal direct liquefaction bitumen gasification system includes an integrated gasifier, a Venturi mixer, injection components, and a three-stage heat recovery zone. The mixer is located above the integrated gasification furnace body and is provided with an asphalt inlet, an oxygen inlet and a first homogeneous mixture outlet, used to mix externally input asphalt and oxygen to form a first homogeneous mixture; The integrated gasifier body is a sealed, integrally welded structure, divided into a premixing zone and a gasification reaction zone from top to bottom. The inner diameter of the premixing zone is smaller than that of the gasification reaction zone, and the length-to-diameter ratio of the gasification reaction zone is 3:1.

[0074] The injection assembly includes a central delivery pipe and six swirling nozzles. The upper end of the central delivery pipe is sealed and connected to the first homogeneous mixture outlet of the mixer, and the lower end extends from the top of the integrated gasifier into the interior of the premixing zone. The six swirling nozzles are fixedly connected to the lower side wall of the central delivery pipe and are evenly arranged along the circumference of the central delivery pipe. Their openings are based on the central axis of the central delivery pipe and have a radial outward and downward tilt of 15°. All swirling nozzles are located in the upper half of the premixing zone.

[0075] The premixing zone has a first mixing steam inlet on its sidewall and a second mixing steam inlet on its top, both of which are located above the horizontal plane where the swirl nozzle is located.

[0076] The outer wall of the gasification reaction zone is surrounded by an annular jacketed protective gap structure, which covers the connection between the lower end of the premixing zone and the upper end of the gasification reaction zone. The annular protective gap is a jacket structure with a closed annular cavity inside, which fits tightly with the outer wall of the gasification reaction zone to form an integrated structure. A third protective steam inlet is provided on the side of the annular protective gap facing the outside, which is connected to an external steam source. Four third protective steam outlets are provided on the side of the annular protective gap facing the gasification reaction zone, which are evenly arranged along the circumference of the top of the gasification reaction zone.

[0077] The three-stage heat recovery zone is located below the gasification slag outlet of the gasification reaction zone, and three independent cooling water heat exchange sections are set from top to bottom along the flow direction of the gasification slag.

[0078] II. Gasification is carried out using the above-mentioned gasification system: 1. Coal direct liquefaction pitch is preheated to 125℃ and fed into a Venturi mixer at a flow rate of 3.5 t / h and a pressure of 4.0 MPa; at the same time, pure oxygen with a purity of 99.5% is preheated to 300℃ and fed into the mixer at a flow rate of 2.2 t / h and a pressure of 4.3 MPa; the two are strongly sheared and mixed in the throat section of the mixer for 0.3 s to form a homogeneous aerosol mixture, namely the first homogeneous mixture.

[0079] The volatile matter content of direct coal liquefaction pitch is 34.38%, the fixed carbon content is 49.97%, the moisture content is 0.21%, and the ash content is 15.65%; and the C element content is 77.43%, the H element content is 4.17%, the N element content is 0.75%, and the S element content is 2.18%.

[0080] 2. The first homogeneous mixture is transported to the swirl nozzle through the central conveying pipe and injected into the premixing zone at high speed in a tangential manner to form a stable three-dimensional swirl field.

[0081] At this time, the first recovered steam from the primary heat exchange section of the heat recovery zone is introduced through the first steam inlet on the side wall of the premixing zone, and collides perpendicularly with the first homogeneous mixture ejected from the swirl nozzle, undergoing secondary shearing and atomization to form the second homogeneous mixture; the second recovered steam from the secondary heat exchange section of the heat recovery zone is introduced through the second steam inlet at the top of the premixing zone, and mixes with the second homogeneous mixture to adjust the temperature and composition of the homogeneous mixture; the third recovered steam from the tertiary heat exchange section of the heat recovery zone is introduced into the annular protective gap to form a continuous gas curtain to block the high-temperature radiation from the gasification reaction zone to the premixing zone.

[0082] The first type of recovered steam is atomized steam, with a temperature of 280℃, a pressure of 4.5 MPa, and a flow rate of 1.2 t / h. The second type of recovered steam is conditioning steam, with a temperature of 240℃, a pressure of 4.0 MPa, and a flow rate of 0.3 t / h. The third type of recovered steam is protective steam, with a temperature of 180℃, a pressure of 3.5 MPa, and a flow rate of 0.2 t / h. In this embodiment, the mass ratio of the total steam formed by the first and second recovered steam to the liquefied asphalt is 0.49:1.

[0083] 3. The second homogeneous mixture smoothly enters the gasification reaction zone for partial oxidation gasification reaction. The generated crude syngas is initially separated from the slag by swirling centrifugal force and discharged from the crude syngas outlet on the middle side wall of the gasification reaction zone. The molten gasification slag is discharged from the gasification slag outlet at the bottom of the gasification reaction zone.

[0084] The partial oxidation gasification reaction was carried out at a temperature of 1350℃ and a pressure of 3.0 MPa, with an average residence time of 2.5 s for the second homogeneous mixture.

[0085] The temperature of the crude syngas exiting the gasification reaction zone is 1320℃. The dry basis composition of the crude syngas is as follows: H2 content is 39.35 mol%, CO content is 50.01 mol%, CH4 content is 0.04 mol%, CO2 content is 8.54 mol%, Ar+N2 content is 0.46 mol%, H2S content is 1.48 mol%, and COS content is 0.07 mol.

[0086] The effective gas (CO+H2) content in the dry basis reached 89.36%; The carbon conversion rate was 99.62%, and the residual carbon content of the gasification slag was 0.38%.

[0087] 4. After entering the heat recovery zone, the high-temperature gasification slag undergoes countercurrent heat exchange with cooling water at 25℃ and a flow rate of 3 t / h. It passes through three independent heat exchange sections from top to bottom, generating three stages of steam with a temperature gradient distribution.

[0088] The three-stage steam is recycled to the first and second mixed steam inlets of the premixing zone and the third protective steam inlet of the gasification reaction zone, respectively, to achieve efficient utilization of the system's waste heat in stages.

Claims

1. A gasification system for direct coal liquefaction pitch, characterized in that, The gasification system includes a mixer, an injection assembly, and an integrated gasifier; wherein... The mixer is located above the integrated gasifier and is provided with an asphalt inlet, an oxygen inlet, and a first homogeneous mixture outlet, for mixing externally input asphalt and oxygen to form a first homogeneous mixture and discharging it. The integrated gasifier is a closed, integral structure with the top and bottom connected, consisting of a premixing zone and a gasification reaction zone from top to bottom. The injection assembly is in sealed communication with the first homogeneous mixture outlet of the mixer and has a nozzle structure for injecting the first homogeneous mixture into the premixing zone; The premixing zone is provided with a mixing steam inlet and an outlet for discharging a second homogeneous mixture formed by the first homogeneous mixture and the mixing steam to the gasification reaction zone. The gasification reaction zone is provided with an inlet for receiving a second homogeneous mixture from the premixing zone, and with a crude syngas outlet and a gasification slag outlet.

2. The gasification system according to claim 1, characterized in that, The mixing steam inlet includes a first mixing steam inlet and an optional second mixing steam inlet; the first mixing steam inlet is used to introduce atomized steam to atomize and mix with a first homogeneous mixture from the mixer to form a second homogeneous mixture; the second mixing steam inlet is used to introduce regulating steam to help adjust the temperature and composition of the second homogeneous mixture in the premixing zone; Preferably, the first mixing steam inlet is located on the side wall of the premixing zone; Preferably, the second mixing steam inlet is located at the top of the premixing zone; Preferably, the horizontal plane where the mixed steam inlet is located is higher than the horizontal plane where the nozzle structure is located.

3. The gasification system according to claim 1 or 2, characterized in that, The outer wall of the gasification reaction zone is surrounded by a jacketed annular protective gap, which is tightly fitted with the outer wall of the gasification reaction zone to form an integrated structure. The annular protective gap covers the side wall of the gasification reaction zone and the connection between the lower end of the premixing zone and the upper end of the gasification reaction zone. The annular protective gap has a third protective steam inlet on the side facing the outside, which is connected to an external steam source; the annular protective gap has a third protective steam outlet on the side facing the gasification reaction zone, located on the side wall or top of the gasification reaction zone. Preferably, the third protective steam outlet is located at the top of the gasification reaction zone, and there are 2 to 8 outlets, which are evenly arranged along the circumferential direction of the top of the gasification reaction zone.

4. The gasification system according to any one of claims 1 to 3, characterized in that, The injection assembly includes a central delivery pipe and a swirling nozzle. The upper end of the central delivery pipe is sealed and connected to the first homogeneous mixture outlet of the mixer, and the lower end extends from the top of the integrated gasifier into the interior of the premixing zone. Preferably, the swirling nozzle is fixedly connected to the lower side wall of the central conveying pipe, the spray direction is towards the side wall of the premixing zone, and the angle between the spray direction and the horizontal plane is 5°~30°. Preferably, the number of swirl nozzles is 2 to 12, and they are evenly arranged along the circumference of the central conveying pipe; Preferably, the horizontal plane where the swirl nozzle is located is in the upper half of the premixing zone; Preferably, the number of central delivery pipes is 1 to 6, and they are evenly arranged along the central axis of the premixing zone.

5. The gasification system according to any one of claims 1 to 4, characterized in that, The inner diameter of the premixing zone is smaller than the inner diameter of the gasification reaction zone; and / or The aspect ratio of the gasification reaction zone is (1.5-4):

1.

6. The gasification system according to any one of claims 1 to 5, characterized in that, The mixer is at least one of a static mixer, a venturi mixer, and a jet mixer.

7. The gasification system according to any one of claims 3 to 6, characterized in that, The gasification system also includes a heat recovery zone located below the gasification slag outlet of the gasification reaction zone, which is used to recover the sensible heat of the high-temperature gasification slag and convert it into water vapor. Preferably, three independent cooling water heat exchange sections are provided from top to bottom along the flow direction of the gasified slag, corresponding to the generation of first recovered steam, second recovered steam and third recovered steam with successively decreasing temperatures, which are respectively reused to the first mixed steam inlet, second mixed steam inlet and third protective steam inlet of the premixing zone.

8. A method for treating direct coal liquefaction bitumen using the gasification system according to any one of claims 1 to 7, comprising the following steps: S1: Coal direct liquefaction pitch and oxygen are fed into a mixer to mix and form a first homogeneous mixture; the first homogeneous mixture is injected into a premixing zone through a spraying assembly and mixed with steam introduced through the mixing steam inlet to form a second homogeneous mixture; S2: The second homogeneous mixture enters the gasification reaction zone and undergoes a partial oxidation gasification reaction under high temperature and high pressure conditions; S3: The crude syngas generated by the reaction is discharged from the crude syngas outlet of the gasification reaction zone, and the molten gasification slag is discharged from the gasification slag outlet of the gasification reaction zone.

9. The method according to claim 8, characterized in that, In step S1: The carbon content in the direct coal liquefaction pitch is not less than 60 wt%, the feed temperature of the direct coal liquefaction pitch is 120~200 ℃, and the feed pressure is 2.0~8.0 MPa; and / or The oxygen has a purity of ≥90%, and the feed pressure is 0.2~0.5 MPa higher than that of direct coal liquefaction pitch; and / or The mass ratio of coal direct liquefaction pitch to oxygen is (1.4~1.8):1, and the mixing time is 0.1~1.0 s; and / or The steam introduced through the mixed steam inlet includes a first mixed steam, the temperature of which is 200~350 ℃ and the pressure of which is 3.0~9.0 MPa; Optionally, a second mixed steam is also introduced into the mixed steam inlet, the temperature of the second mixed steam being 180~300℃ and the pressure being 2.5~8.5 MPa; Optionally, a third protective steam is introduced into the annular protective gap at the connection between the premixing zone and the gasification reaction zone. The temperature of the third protective steam is 150~220℃ and the pressure is 2.0~8.0 MPa. The total mass ratio of the first mixed steam and the optional second mixed steam to the mass ratio of coal direct liquefaction bitumen is (0.2~0.5):

1.

10. The method according to claim 8 or 9, characterized in that, In step S2: the temperature of the gasification reaction is 1200~1700 ℃, the pressure is 0.1~6.0 MPa, and the residence time of the second homogeneous mixture in the gasification reaction zone is 1.0~5.0 s; and / or In step S3: the temperature of the crude syngas leaving the gasification reaction zone is 1300~1400 ℃.

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