A fluidized bed dry powder gasification system and method for producing syngas using CO2

Abstract

The application discloses a gas flow bed dry powder gasification system and method for preparing synthesis gas by using CO2. The system comprises a CO2 treatment unit, a dry powder gasification unit, and a CO2 pretreatment device. The CO2 treatment unit comprises a CO2 collection device, a CO2 pretreatment device and a CO2 delivery device which are sequentially connected. The dry powder gasification unit is used for receiving CO2 from the CO2 delivery device, and coal powder or coke powder raw materials and oxygen provided from outside, and gasification is carried out to obtain CO-containing synthesis gas. The system comprises a gasification furnace and a furnace temperature control system, raw material delivery pipelines leading to each burner of the gasification furnace, CO2 delivery pipelines and oxygen delivery pipelines, and a metering control system for adjusting the addition proportion of raw materials and additives. The application combines CO2 emission reduction and utilization with the conversion of coal powder or coke powder in the gasification furnace, optimizes the process, widens the gasification operation temperature range, and improves the control precision.

Description

Technical Field

[0001] This invention belongs to the field of clean and energy-saving coal chemical industry, specifically relating to a fluidized bed dry powder gasification system and method for preparing syngas using CO2. Background Technology

[0002] Traditional coal chemical industry typically refers to the production of syngas, primarily composed of CO and H2, from coal and oxygen (air, oxygen-enriched, and pure oxygen) as raw materials. This syngas is then used in downstream gas shifting and purification processes to produce products such as synthetic ammonia, urea, methanol, dimethyl ether, ethylene glycol, olefins, and natural gas. Coal gasification, as the starting point of coal chemical industry, holds a crucial position in the entire field. In recent years, with increasingly stringent national requirements for efficiency, energy consumption, environmental protection, and safety, fluidized bed gasification, especially dry powder fluidized bed gasification, has been widely adopted in the industry due to its advantages such as strong coal adaptability, high gasification efficiency, energy saving, and environmental friendliness.

[0003] On the one hand, the requirements for CO2 emissions are more stringent, requiring not only enterprises to reduce CO2 emissions, but also to take advantage of the carbon sequestration capabilities of coal chemical industry and find ways to solidify the CO2 that would otherwise be emitted into chemical products through various means. On the other hand, the use of raw coal is more strictly controlled, and some by-products such as coke powder in the coking industry and petroleum coke in the petrochemical industry also need to be converted into syngas through gasification. Its main characteristics are high carbon content, high calorific value and low activity.

[0004] Currently, there are two main ways to utilize or recover CO2. One is as a preservative, refrigerant, or oil displacement agent, which only achieves reuse but does not achieve substantial carbon emission reduction. The other is CO2 capture and storage, which relies on the natural environment for long-term processing and has low added value. As for the gasification of coke powder, the disadvantage of low activity is generally overcome by reducing the particle size of the coke powder and extending the residence time.

[0005] Therefore, developing new CO2 recovery and utilization technologies that simultaneously achieve efficient coke powder gasification, realize low-carbon environmental protection, energy conservation and emission reduction, and create added value and economic benefits are of great practical significance.

[0006] While CN 112812930A proposes using systems such as coal gasification and fermentation to treat CO2, it is only conceptual and difficult to meet the needs of actual production. CN101285008A uses CO2 as a temperature regulator, but its application in a fixed-bed gasification process is problematic. On the one hand, due to its low gasification temperature, the utilization rate of CO2 is low; on the other hand, the control of CO2 quantity is relatively crude and cannot be precisely controlled, making implementation difficult and potentially affecting the normal operation of the original process. Summary of the Invention

[0007] In view of this, the main objective of the present invention is to provide a fluidized bed dry powder gasification system and method for producing syngas using CO2, which combines the reduction and utilization of CO2 emissions with the conversion of pulverized coal or coke powder in the gasifier, thereby optimizing the process, widening the operating temperature range, and improving control accuracy.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A fluidized bed dry powder gasification system for producing syngas using CO2, comprising:

[0010] The CO2 processing unit includes a CO2 collection device, a CO2 pretreatment device, and a CO2 conveying device connected in sequence.

[0011] The dry powder gasification unit is used to receive CO2 from the CO2 conveying device, as well as coal powder or coke powder raw materials and oxygen provided externally, and to gasify them to obtain syngas containing CO; it includes a gasifier and its furnace temperature control system, raw material conveying pipelines to each burner of the gasifier, CO2 conveying pipelines and oxygen conveying pipelines, and a metering control system for adjusting the proportion of raw materials and additives.

[0012] According to the system of the present invention, the CO2 pretreatment device sequentially includes a filtration unit, a dehydration unit, and a concentration unit.

[0013] According to the system of the present invention, the CO2 conveying device includes a gas collecting cabinet, a compressor, and CO2 distribution pipelines. Pretreated CO2 is conveyed to the gas collecting cabinet via pipelines, pressurized by the compressor, and then distributed to various users of the gasification system via the CO2 distribution pipelines. Further, the distribution pipelines include pipelines for distributing CO2 to ignition burners, process burners, the gasifier annular cavity, and raw material conveying pipelines. Preferably, flow meters, controllers, and regulating valves are optionally installed on each pipeline to control the flow rate distributed to each user. The CO2 distributed to the ignition burners and process burners is directly used as a reaction gas and temperature regulator; the CO2 in the gasifier annular cavity is used as a protective gas, preventing backflow of gas from the gasification chamber into the annular cavity through a slightly positive pressure higher than that of the gasification chamber; the CO2 distributed to the raw material conveying pipelines is used as a conveying gas for raw materials such as pulverized coal or coke powder, entering the gasifier reaction chamber along with the pulverized coal or coke powder and participating in the gasification reaction.

[0014] According to the system of the present invention, the gasifier includes a gasification section and a cooling section. The gasification section has a water-cooled wall structure, and there is an annular cavity between the water-cooled wall and the shell. CO2 enters the annular cavity and enters the gasifier through the gap between the water-cooled wall and the burner seat. Furthermore, circulating water flows through the water-cooled wall, and the heat flux data of the water-cooled wall is obtained by the heat absorption of the circulating water. This data is used to control the reaction / slag temperature in the gasification section of the gasifier, that is, for the control of the gasifier's furnace temperature control system.

[0015] According to the system of the present invention, the furnace temperature control device of the gasifier includes flow meters, controllers, and regulating valves respectively installed on the raw material conveying pipeline, the CO2 conveying pipeline, and the oxygen conveying pipeline. Preferably, the raw material conveying pipeline also has a separate carrier gas control, including a raw material velocity and density meter, a carrier gas flow meter, a controller, and a carrier gas regulating valve, so as to ensure that raw materials such as pulverized coal or coke powder flow at a specified velocity and density.

[0016] According to the system of the present invention, the cooling section can be either a radiant waste boiler type + water quenching type or a radiant waste boiler type + convection waste boiler type.

[0017] Another aspect of the present invention provides the above-mentioned method for preparing syngas using a fluidized bed dry powder gasification process with CO2, comprising the following steps:

[0018] 1) The CO2-rich gas from the outside is collected and mixed by the CO2 collection device and then enters the CO2 pretreatment device. After filtration, drying, removal of solid particles and liquid water from the gas, and concentration to increase the CO2 concentration, it is then output through the CO2 conveying device.

[0019] 2) Coal powder or coke powder raw materials, additives, and CO2 provided by the external supplier are transported to the dry powder gasification unit, where they are gasified in an oxygen atmosphere to obtain CO-rich syngas.

[0020] According to the method of the present invention, the CO2 concentration in the CO2-rich gas is 50% to 100%, preferably 80% to 100%. This concentration requirement reduces the energy consumption and equipment investment in the CO2 enrichment and purification process.

[0021] According to the method of the present invention, CO2 supplied by the CO2 conveying device is conveyed to the ignition burner, process burner, gasifier annular cavity, and raw material conveying pipeline of the gasifier.

[0022] According to the method of the present invention, the vaporization temperature is 1500–2000°C, preferably 1600–1800°C. Under these preferred conditions, the vaporization operation is more comfortable while increasing CO2 consumption.

[0023] According to the method of the present invention, the additive is one or a mixture of CaCO3, silica, and kaolin. The addition ratio of the additive is determined according to the ash composition of the raw material, generally 0-10%, and preferably 0-5% by mass of the coal powder raw material to reduce the amount of additive used. The ash composition of the raw material affects the operating temperature of the fluidized bed gasification water-cooled wall quenching process, mainly referring to the silicon-aluminum ratio (SiO2 / Al2O3) and acid-base ratio ((SiO2+Al2O3) / (Fe2O3+CaO+MgO)) in the ash composition. For example, the silicon-aluminum ratio is required to be >1.4, preferably 1.8-3.5, and the acid-base ratio is required to be: the proportion of silicon-aluminum acidic oxides in the ash composition >60wt%, CaO+MgO <20wt%, preferably CaO+MgO <15wt%, Fe2O3 <15wt%, preferably Fe2O3 <12wt%. If the coal ash composition is not within this range, appropriate additives are added to adjust the ash composition.

[0024] According to the method of the present invention, it further includes: controlling the flow rates of oxygen, pulverized coal or coke powder, and CO2 entering the dry powder gasification unit, the control basis being the water-cooled wall heat load. Specifically, the water-cooled wall heat load and the target heat load are calculated in the controller module during control, and selective control is performed using a selector, adjusting the CO2 flow rate control or the oxygen-coal ratio control to the target heat load at different stages.

[0025] In a specific implementation plan, the heat load control parameters of the gasifier are set according to different coal types. The control parameters are compared with the feedback values ​​obtained from gasification measurement and calculation, and the CO2 flow rate or oxygen-coal ratio is adjusted accordingly. When the difference between the set value and the feedback value is less than the set difference, the selector outputs to the CO2 flow controller, and the CO2 flow rate is adjusted by the module to control the furnace temperature. When the difference between the set value and the feedback value is greater than the set difference, the selector outputs to the oxygen-coal ratio controller, and the furnace temperature is controlled by adjusting the oxygen-coal ratio.

[0026] According to the method of the present invention, after gasification in step 2), a small amount of CO2 is also obtained, which can be returned to the CO2 processing unit for reuse.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1) The system of this invention collects the CO2 waste gas that needs to be emitted as product gas and generates CO-rich syngas that can be used to produce chemicals through a gasification reaction; it has high adaptability to CO2-rich gas, high conversion rate and wide treatment range.

[0029] 2) By adding additives and strictly controlling the proportion of additives, a higher gasification temperature is achieved, enabling efficient gasification of raw materials such as pulverized coal, coke powder, and petroleum coke to produce syngas. These raw materials, such as coke powder and petroleum coke, are difficult to gasify and were previously used as boiler fuel. In this invention, they are gasified as raw materials, which not only reduces carbon emissions from boiler combustion but also additionally treats CO2.

[0030] 3) The CO2 separated after syngas treatment can be recycled and reused, achieving zero CO2 emissions throughout the entire process. It can also consume and convert CO2 emitted by other systems.

[0031] 4) The method of this invention produces syngas primarily composed of CO, with a CO content of 75%–99%, optimally reaching 95%–99%, which is highly favorable for the production of chemical products using CO as the main raw material. In regions where electrolytic hydrogen production has a cost advantage, gasification can be selectively combined with the new technology "green hydrogen" process. The CO / H2 ratio can be flexibly adjusted according to the types of downstream chemical products, thereby avoiding the generation of CO2 during the conversion process. Simultaneously, the oxygen from the green hydrogen process can supplement the consumption of the gasification process.

[0032] 5) The temperature control of the fluidized bed gasifier in this invention is achieved through the adjustment of the heat load. This is achieved through the selective synergistic control of CO2 flow rate and oxygen-to-coal ratio. When there are minor fluctuations in the heat load, the CO2 flow rate is adjusted; when the heat load fluctuates significantly, the oxygen-to-coal ratio is adjusted. This control principle avoids the problem of fluctuations easily caused by adjusting the oxygen-to-coal ratio alone, reduces the difficulty of gasifier operation, achieves precise and stable temperature control of the gasifier, minimizes fluctuations in the composition of the syngas, and also extends the service life of vulnerable components such as the gasifier burner and the gasifier downcomer. Attached Figure Description

[0033] Figure 1 This is a schematic diagram illustrating a flow bed dry powder gasification method for preparing syngas using CO2, as shown in an embodiment of the present invention.

[0034] Figure 2 yes Figure 1 A schematic diagram of the CO2 processing flow in the CO2 processing unit.

[0035] Figure 3 yes Figure 1 Schematic diagram of CO2 distribution pipeline.

[0036] Figure 4 This is a schematic diagram of the raw material and additive transportation and control process.

[0037] Figure 5 This is a schematic diagram of the furnace temperature control system of the gasifier.

[0038] The markings in the image are as follows:

[0039] 3.1 - CO2 storage tank; FT1 / FT2 / FT3 / FT4 - flow meters; FC1 / FC2 / FC3 / FC4 - flow controllers;

[0040] 4.1 Additive conveying, metering and control equipment; 4.2 Raw material conveying, metering and control equipment; 4.3 Proportional control module; 4.4 Dry powder gasification unit;

[0041] 5.1-First CO2 gas flow meter, 5.2-First CO2 gas flow controller, 5.3-Carrier gas regulating valve, 5.4-Raw material velocity and density meter, 5.5-Second CO2 gas flow meter, 5.6-Second CO2 gas flow controller, 5.7-CO2 regulating valve, 5.8-Raw material flow meter, 5.9-Raw material flow controller, 5.10-Raw material regulating valve, 5.11-Oxygen flow meter, 5.12-Oxygen flow controller, 5.13-Oxygen regulating valve, 5.14-Selector, 5.15-Oxygen-coal ratio measuring instrument, 5.16-Oxygen-coal ratio controller, 5.17-Water-cooled wall heat load controller. Detailed Implementation

[0042] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0043] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0044] Unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to fixed connections or detachable connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and connections within two components or interactions between two components. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0045] In the process of dry gasification in a fluidized bed, dry coal powder or coke powder and oxygen are usually used as raw materials and carried out at high temperature. The process is as follows: the coal powder or coke powder and oxygen are burned to generate CO and CO2 and release heat violently (as shown in reactions (1) and (2) below), which provides temperature for subsequent gasification reactions; C reacts with CO2 or water endothermically and produces CO and H2 (as shown in reactions (3) and (4) below). In traditional dry gasification, water vapor is added. Based on the heat absorption of water vapor during heating and the heat absorption of water vapor in the reaction, the temperature is adjusted. As a carbon-containing substance, CO2 can also absorb heat through heating after entering the gasifier, and can also participate in the reaction endothermically in the furnace, thus achieving the purpose of acting as a regulator. In addition, CO2 can also be converted into CO, which is converted into useful syngas. Furthermore, the increase in the content and concentration of CO2 also helps to move and strengthen the reaction between C and CO in coal powder or coke powder, thus overcoming its poor activity.

[0046] The main reactions within the dry powder airflow bed are as follows:

[0047] C + O₂ → CO₂ - 393.5 KJ / mol (1)

[0048] C + 1 / 2O₂ → CO - 110.5 kJ / mol (2)

[0049]

[0050]

[0051] Based on the above theoretical foundation, this invention develops a fluidized bed dry gasification method for producing syngas using CO2, which achieves efficient conversion of pulverized coal or coke powder while recovering and utilizing CO2 to produce syngas and chemicals, thereby achieving the dual goals of social benefits in CO2 emission reduction and economic benefits in creating added value.

[0052] Therefore, as Figure 1 As shown, this embodiment of the invention provides a fluidized bed dry powder gasification system for producing syngas using CO2, comprising:

[0053] The CO2 processing unit includes a CO2 collection device, a CO2 pretreatment device, and a CO2 conveying device connected in sequence.

[0054] The dry powder gasification unit is used to receive CO2 from the CO2 conveying device, as well as coal powder or coke powder raw materials and oxygen provided externally, and to gasify them to obtain syngas containing CO; it includes a gasifier and its furnace temperature control system, raw material conveying pipelines to each burner of the gasifier, CO2 conveying pipelines and oxygen conveying pipelines, and a metering control system for adjusting the proportion of raw materials and additives.

[0055] The CO2 processing unit is used to realize functions such as CO2 collection, pretreatment, transportation, storage and distribution. Specifically, it may include a CO2 rich gas collection device, CO2 filtration, dehydration and concentration pretreatment devices, CO2 gas holder, CO2 compressor and CO2 distribution pipeline and other transportation devices, and may also be equipped with CO2 storage tank and distribution control equipment.

[0056] like Figure 2 As shown, CO2-rich gas collected from external sources or other sections within the system (such as CO2 recovered from conversion or purification sections) is collected, mixed, and then enters a pretreatment unit. After filtration and drying, solid particles and liquid water are removed from the gas to prevent impact on the compressor; concentration is then applied to increase the CO2 concentration. After pretreatment, the gas is transported via pipeline to a CO2 gas holder, pressurized by a compressor, and then distributed to various users of the gasification system via CO2 storage tanks, CO2 distribution pipelines, and distribution control equipment. Preferably, as shown... Figure 3 As shown, CO2 is distributed to the ignition burner, process burner, gasifier annular cavity, and raw material conveying device via a high-pressure CO2 storage tank 3.1 and individual flow meters (FT1 / FT2 / FT3 / FT4) and regulating valves (FC1 / FC2 / FC3 / FC4). Precise control of CO2 usage for each user is achieved through flow distribution adjustment parameters, tailored to individual user needs. The CO2 from the ignition and process burners is directly used as reactant and temperature regulator; the CO2 in the gasifier annular cavity is used as protective gas, with a slightly positive pressure higher than that of the gasification chamber preventing backflow of gas from the gasification chamber into the annular cavity; the CO2 distributed to the raw material conveying device is used as raw material conveying gas, entering the gasifier reaction chamber with pulverized coal and other raw materials to participate in the gasification reaction.

[0057] The dry powder gasification unit may also include subsequent conventional treatment processes such as slag discharge, syngas washing, and black water treatment system. For reference, see the applicant's patent CN202022190849.3, "A Coal Gasification System with Top Burner".

[0058] The gasifier mentioned above includes a gasification section and a cooling section. Depending on the structure and configuration of the cooling section, it can be divided into a radiant waste boiler + water quench type or a radiant waste boiler + convection waste boiler type.

[0059] The gasification section has a water-cooled wall structure inside, and there is an annular cavity between the water-cooled wall and the shell. CO2 enters the annular cavity and enters the gasifier through the gap between the water-cooled wall and the burner seat.

[0060] Furthermore, circulating water flows through the water-cooled wall, and heat flux data of the water-cooled wall is obtained through heat absorption by the circulating water. This heat flux data is used to control the reaction / slag-coating temperature within the gasification section of the gasifier, i.e., furnace temperature control, to ensure stable operation within a maintained temperature range. The furnace temperature control system (e.g.) Figure 5This includes pipelines for raw materials such as pulverized coal or coke powder, oxygen, and CO2-rich gas, as well as flow meters, controllers, and regulating valves for each pipeline. The pulverized coal pipeline also includes separate carrier gas control (e.g., the first CO2 gas flow meter 5.1, the first CO2 gas flow controller 5.2, the carrier gas regulating valve 5.3, and the raw material velocity and density meter 5.4 in the diagram) to ensure that the pulverized coal and other raw materials flow at specified speeds and densities. The furnace temperature control system utilizes the characteristics of CO2 and the oxygen-to-coal ratio for furnace temperature control, as shown in the attached diagram. Figure 5 As shown: The flow rates of O2, raw materials, and CO2 are each controlled and regulated by their respective flow control and regulation devices (e.g., second CO2 flow meter 5.5, second CO2 flow controller 5.6, CO2 regulating valve 5.7, raw material flow meter 5.8, raw material flow controller 5.9, raw material regulating valve 5.10, oxygen flow meter 5.11, oxygen flow controller 5.12, oxygen regulating valve 5.13). The control target is the water-cooled wall heat load controller 5.17. During control, the measured water-cooled wall heat load and the target heat load are calculated in the water-cooled wall heat load controller 5.17, and selective control is performed using selector 5.14. That is, at different stages, the flow control of CO2 (via second CO2 flow meter 5.5, second CO2 flow controller 5.6, CO2 regulating valve 5.7) and the control and adjustment of the oxygen-coal ratio (via oxygen-coal ratio measuring instrument 5.15, oxygen-coal ratio controller 5.16) are selected to reach the target heat load. Figure 5 The heat load feedback is the measured heat load value from the gasifier. This value is compared and calculated with the set target value within the water-cooled wall heat load controller 5.17, and the calculated value is output to the selector 5.14. Depending on the furnace size, heat load fluctuations are controlled by adjusting the CO2 flow rate when they are less than a certain range. When heat load fluctuations exceed a certain range, the oxygen-to-coal ratio is adjusted (e.g., for a 400MW gasifier, the target heat load is controlled at 5MW, with fluctuations allowed between 4 and 6MW. When the fluctuation is within ±0.5MW, CO2 adjustment is automatically selected; when it exceeds this range, oxygen-to-coal ratio adjustment is automatically selected).

[0061] A metering and control system for adjusting the ratio of raw materials and additives, such as Figure 4 As shown, it includes raw material conveying metering and control equipment 4.2, additive conveying metering and control equipment 4.1, proportional control module 4.3, etc. During control, the conveying amount of raw material is determined by the load requirements of the gasifier and is metered and controlled to enter the dry powder gasification unit 4.4 at the required flow rate. After the proportional control module 4.3 calculates the additive addition flow rate according to the additive addition ratio, the required additive is added to the dry powder gasification unit 4.4 through the additive conveying metering and control equipment 4.1. The amount of additive changes with the amount of raw material, but the addition ratio remains unchanged.

[0062] For ease of understanding, the following examples illustrate the application and operation of the gasification system of the present invention in the production process, and should not be construed as limiting the technical solution of the present invention to this:

[0063] The above-mentioned method for producing syngas using a fluidized bed dry powder gasification process with CO2 includes the following steps:

[0064] 1) The CO2-rich gas from the outside is collected and mixed by the CO2 collection device and then enters the CO2 pretreatment device. After filtration, drying, removal of solid particles and liquid water from the gas, and concentration to increase the CO2 concentration, it is then output through the CO2 conveying device.

[0065] 2) Coal powder or coke powder, additives, and CO2 supplied by an external supplier are transported to the dry powder gasification unit for gasification in an oxygen atmosphere to obtain CO-rich syngas.

[0066] Preferably, the CO2 concentration in the CO2-rich gas is 50% to 100%, more preferably 80% to 100%.

[0067] Preferably, the vaporization temperature is 1500–2000°C, more preferably 1600–1800°C.

[0068] Preferably, the additive is one or a mixture of CaCO3, silica, and kaolin. The proportion of the additive added is determined according to the ash composition of the raw material, generally accounting for 0-10% of the raw material mass, and preferably 0-5% to reduce the amount of additive used.

[0069] The syngas produced by the gasifier contains >75% CO (dry basis), <2% CO2 (dry basis), and ~20% H2 (dry basis).

[0070] Preferably, when coke powder or petroleum coke is used as the gasification feedstock, the raw materials have a higher C content, lower H content, and higher calorific value, resulting in a stronger CO2 processing capacity and a higher CO content in the syngas (CO>90% (dry basis)) and a CO2 content (<2% (dry basis)).

[0071] According to the method of the present invention, in addition to generating CO-rich syngas after gasification in step 2), a small amount of CO2 is also obtained, which can be returned to the CO2 processing unit for reuse.

[0072] Preferably, the process also includes step 3): mixing the CO-rich syngas obtained in step 2) with "green hydrogen" in a specified ratio, and then introducing the mixture into a downstream system to produce corresponding chemical products. In this process, hydrogen is produced using methods such as water electrolysis, without generating CO2. The electricity for water electrolysis mainly comes from renewable resources such as hydropower, wind power, and solar power; therefore, the hydrogen produced using this method is called "green hydrogen." This differs from traditional coal chemical processes that use the reaction of CO with water to generate CO2 and H2 to produce hydrogen while simultaneously releasing CO2.

[0073] The following specific production examples illustrate the application of the gasification and pyrolysis system of this invention. These examples are only for the purpose of facilitating understanding of the invention and should not be construed as limiting the invention to these examples.

[0074] Application Example 1:

[0075] The final product of a certain project is acetic acid. Raw materials include methanol and CO. Methanol is purchased externally, while CO is obtained through gasification of metallurgical coke powder (metallurgical coke has particle size requirements; coke that is too small cannot be used in metallurgical ironmaking and needs to be treated or converted) and CO2 gas collected from other sections of the plant. The CO requirement is approximately 120,000 Nm³. 3 The system employs a 2000-ton-per-hour coal gasification system. The cooling section utilizes a combination of radiant and convective waste boilers to increase steam production and meet the requirements of other processes. The gasification temperature is 1650℃. To ensure proper furnace temperature and slag adhesion and removal on the water-cooled walls, 2% silica is added to the coke powder, with the addition amount maintained by an additive control system. The raw material consumption is 70 t / h, and the CO2 consumption is 16000 Nm³. 3 / h; CO content in syngas is ~96%, CO2 content is ~1.8%, equivalent to producing 120,000 Nm³. 3 / hCO produced 2300 Nm³ as a byproduct 3 CO2 production per hour, with a CO2 conversion rate of approximately 86%. A byproduct of 2300 Nm³ / h. 3 The CO2 produced per hour, after separation in the downstream process, can be returned to the gasification plant for further reaction and conversion. The gasification plant can also additionally process and convert CO2 from other sources, totaling 13700 Nm³. 3 According to the above production process calculations, all CO2 in the plant is recovered and reused, achieving zero emissions. It can also process and convert an additional 220,000 tons / year of CO2 gas, while saving approximately 70,000 tons / year of raw coke powder. Furthermore, the selective control of CO2 and oxygen-to-coal ratio reduces control difficulty and improves control precision, resulting in an average continuous operating time of over one year for the gasifier and a burner lifespan of over two years.

[0076] Application Example 2:

[0077] A certain project involves the production of methanol from syngas. Part of the syngas is obtained through gasification of a mixture of anthracite and petroleum coke with CO2. After purification, desulfurization, and CO2 removal (CO2 is recycled through gasification), it is mixed with "green hydrogen" produced by water electrolysis to achieve a specified ratio, producing 1.6 million tons of methanol per year. Two 1500-ton-per-hour coal-fired gasification systems are used. The cooling section employs a radiant waste boiler + water quench cooling system to save on investment. The gasification temperature is 1600℃. To ensure the furnace temperature and the slag adhesion and removal on the water-cooled walls, 1% silica is added to the coke powder, with the addition amount maintained by an additive control system. The usage of the mixed anthracite and petroleum coke feedstock is 110 t / h, and the CO2 usage is ~23000 Nm³. 3 / h; CO content in syngas ~77% (144000 Nm³) 3 / h), H2 content ~19% (36000Nm 3 / h), CO2 content ~1.5% (~2800Nm 3 / h). "Green hydrogen" is produced through water electrolysis – 250,000 Nm³. 3 / h, while producing 125,000 Nm³ of oxygen as a byproduct. 3 / h. The syngas produced by gasification is purified to remove impurities such as CO2 and H2S, and then mixed with "green hydrogen" to synthesize methanol at a rate of ~1.6 million tons / year. The O2 produced as a byproduct of the hydrogen production section contains ~60,000 Nm³. 3 The oxygen demand for gasification can be met by [amount] / h, and the remaining O2 can be sold externally as a product. The gasification section produces 180,000 Nm³ / h. 3 / hCO+H2 simultaneously produces 2800 Nm³ of byproduct 3 CO2 per hour, with a CO2 conversion rate of ~88%.

[0078] 2800Nm of by-product 3 The CO2 produced per hour, after separation in subsequent stages, can be returned to the gasification process for further reaction and conversion. The gasification process can also additionally treat and convert CO2 from other sources, up to 20200 Nm³. 3 According to the above production process calculations, all CO2 in the factory is recycled and reused, achieving zero emissions. It can also process and convert an additional 320,000 tons / year of CO2 gas, while saving approximately 110,000 tons / year of raw materials and selling 750,000 tons / year of oxygen.

[0079] In the embodiments of the present invention, since the various devices are connected by air circuits, electrical circuits, or other means, or by automatic control systems, operating instructions, or the specific structure of controllers, etc., all of these are existing technologies and are known to those skilled in the art. Therefore, they will not be described in detail in the text.

[0080] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are within the scope of protection of the present invention.

Claims

1. A fluidized bed dry powder gasification system for producing syngas using CO2, characterized in that: include: The CO2 processing unit includes a CO2 collection device, a CO2 pretreatment device, and a CO2 conveying device connected in sequence. The CO2 pretreatment device includes a filtration unit, a dehydration unit, and a concentration unit in sequence. The CO2 conveying device includes a gas collection cabinet, a compressor, and a CO2 distribution pipeline. The distribution pipeline includes a pipeline for distributing CO2 to ignition burners, process burners, the gasifier annular cavity, and raw material conveying pipelines. The dry powder gasification unit is used to receive CO2 from the CO2 conveying device, as well as coal powder or coke powder raw materials and oxygen provided externally, and to gasify them to obtain syngas containing CO; it includes a gasifier and its furnace temperature control system, raw material conveying pipelines to each burner of the gasifier, CO2 conveying pipelines and oxygen conveying pipelines, and a metering control system for adjusting the proportion of raw materials and additives. The flow rates of oxygen, pulverized coal or coke powder, and CO2 entering the dry powder gasification unit are controlled based on the water-cooled wall heat load. During control, the measured water-cooled wall heat load and the target heat load are calculated in the controller module, and selective control is performed using a selector. The heat load control parameters of the gasifier are set according to different coal types. The control parameters are compared with the feedback values ​​obtained from gasification measurement and calculation. The CO2 flow rate or oxygen-coal ratio is adjusted accordingly. When the difference between the set value and the feedback value is less than the set difference, the selector outputs to the CO2 flow controller. The module calculates and adjusts the CO2 flow rate to control the furnace temperature. When the difference between the set value and the feedback value is greater than the set difference, the selector outputs to the oxygen-coal ratio controller. The furnace temperature is controlled by adjusting the oxygen-coal ratio.

2. The fluidized bed dry powder gasification system according to claim 1, characterized in that: The gasifier includes a gasification section and a cooling section. The gasification section has a water-cooled wall structure inside, and there is an annular cavity between the water-cooled wall and the shell. CO2 enters the annular cavity and enters the gasifier through the gap between the water-cooled wall and the burner seat.

3. The fluidized bed dry powder gasification system according to claim 2, characterized in that: Circulating water flows through the water-cooled wall, and the heat flux data of the water-cooled wall is obtained by the heat absorption of the circulating water, which is used for the control of the furnace temperature control system.

4. The fluidized bed dry powder gasification system according to claim 1 or 2, characterized in that: The gasifier temperature control system includes flow meters, controllers, and regulating valves respectively installed on the raw material conveying pipeline, CO2 conveying pipeline, and oxygen conveying pipeline.

5. The fluidized bed dry powder gasification system according to claim 4, characterized in that: The raw material conveying pipeline also has a separate carrier gas control system, including a raw material speed and density meter, a carrier gas flow meter, a carrier gas controller, and a carrier gas regulating valve.

6. The fluidized bed dry powder gasification system according to claim 2, characterized in that: The cooling section is either a radiant waste boiler type + water quenching type or a radiant waste boiler type + convection waste boiler type.

7. A method for preparing syngas using a fluidized bed dry powder gasification process with CO2, characterized in that: Includes the following steps: 1) CO2-rich gas from the outside is collected and mixed by a CO2 collection device and then enters a CO2 pretreatment device. After filtration, drying, removal of solid particles and liquid water from the gas, and concentration to increase the CO2 concentration, it is then output through a CO2 conveying device. The CO2 provided by the CO2 conveying device is delivered to the ignition burner, process burner, gasifier annular cavity, and raw material conveying pipeline of the gasifier. 2) Coal powder or coke powder raw materials, additives, and CO2 provided by the CO2 conveying device are transported to the dry powder gasification unit, where they are gasified in an oxygen atmosphere to obtain CO-rich syngas. In this process, CO2 flow control or oxygen-to-coal ratio control is selected at different stages to adjust to the target heat load. The flow rates of oxygen, pulverized coal or coke powder, and CO2 entering the dry powder gasification unit are controlled based on the water-cooled wall heat load. During control, the measured water-cooled wall heat load and the target heat load are calculated in the controller module, and selective control is performed using a selector. The heat load control parameters of the gasifier are set according to different coal types. The control parameters are compared with the feedback values ​​obtained from gasification measurement and calculation. The CO2 flow rate or oxygen-coal ratio is adjusted accordingly. When the difference between the set value and the feedback value is less than the set difference, the selector outputs to the CO2 flow controller. The module calculates and adjusts the CO2 flow rate to control the furnace temperature. When the difference between the set value and the feedback value is greater than the set difference, the selector outputs to the oxygen-coal ratio controller. The furnace temperature is controlled by adjusting the oxygen-coal ratio.

8. The method for gasification of dry powder in an airflow bed according to claim 7, characterized in that: The vaporization temperature is 1500~2000℃.

9. The method for gasification of dry powder in an airflow bed according to claim 8, characterized in that: The vaporization temperature is 1600~1800℃.

10. The method for gasification of dry powder in an airflow bed according to claim 7, characterized in that: The additive is one or a mixture of CaCO3, silica and kaolin; the addition ratio of the additive is determined according to the ash composition of the raw materials.

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