Composite gasified coal based on carbon dioxide capture and method for preparing the same

Abstract

The application discloses a calcium-based tar residue composite gasification briquette based on a carbon dioxide capturing process, which comprises the following components in parts by mass: 100 parts of coal powder; 1-10 parts of slaked lime calculated according to calcium oxide; 1-15 parts of coal tar residue; and 1-10 parts of a high molecular binder; the use amount of each raw material is the use amount after moisture is deducted; the mixture is formed and dried by using boiler flue gas, and the preparation is completed while capturing carbon dioxide; the mechanical strength and thermal stability of the gasification briquette are improved due to the combination of the organic high molecular binder and the tar residue; the obtained gasification briquette has high mechanical strength and low production cost, and is not prone to thermal explosion and powdering during gasification, and can meet the requirements of coal gasification on granular raw materials; meanwhile, carbon dioxide capturing and resource utilization are realized during the preparation of the composite gasification briquette, and the disposal of coal tar residue hazardous waste is realized by blending and burning the composite gasification briquette in a pressurized gasification slagging furnace.

Description

Technical Field

[0001] This invention specifically relates to a calcium-based tar residue composite gasification briquette and its preparation method. Background Technology

[0002] In response to global warming, countries worldwide are actively engaged in research on carbon dioxide emission reduction, utilization, and storage. Carbon capture, storage, and utilization (CCUS) technology plays a crucial role in achieving the goals of "carbon neutrality and carbon peaking." The application of carbon capture technology in industries with high carbon emissions and heavy emission reduction tasks, such as power, steel, and chemicals, is currently a key focus of CCUS technology research.

[0003] Coal tar residue is a black or dark brown viscous paste-like solid formed after the solid components such as coal powder, coke powder, and graphite carried by the coal gas during the gasification or coking process, along with organic tar gas, are separated through a gas collecting pipe and a primary cooler. It has high viscosity and is difficult to separate into oil and water. The composition of coal tar residue is extremely complex, mainly containing benzene compounds, polycyclic aromatic hydrocarbons, nitrogen-containing and sulfur-containing heterocyclic compounds, heavy metals, and other pollutants. Coal tar residue is listed as HW11 distillation residue in the "National Hazardous Waste List (2021 Edition)," with codes: 252-002-11, 252-004-11, 252-005-11, 252-017-11, and 451-001-11. Therefore, the resource utilization of coal tar residue has become one of the urgent problems to be solved by enterprises and is currently a hot topic of research for domestic researchers.

[0004] CN91106220.3 discloses a briquette using coal tar residue as a binder; CN200510027429.0 discloses a composite binder for briquettes; CN202010021944.2 discloses a briquette based on coal tar residue and its coking coal blending method; CN201811188959.7 discloses a method for preparing briquette binders using coking waste, all of which involve preparing composite binders for briquettes using coal tar residue and additives or other industrial waste. These patented technologies are mainly applied to civilian briquettes or coal coking applications using tar residue as a binder. Their application in coal gasification is relatively limited, primarily due to poor thermal stability, severe gas explosion pulverization, and high levels of ash and volatile matter carried over.

[0005] To expand the sources of binders and utilize various industrial waste residues and liquids, turning waste into treasure and reducing environmental pollution, countries around the world have developed polymer binders in recent years, which are widely used in petroleum, chemical, building materials, pharmaceutical, and environmental protection fields. Studies on the preparation of bituminous coal briquettes using polymers as the main binder have shown that the preparation of briquettes requires a large amount of binder, a long drying time, poor combustion performance, and unsatisfactory results. Summary of the Invention

[0006] The purpose of this invention is to provide a calcium-based tar residue composite gasification briquette and its preparation method. By combining an organic polymer binder with the adhesive properties of tar residue, the mechanical strength and thermal stability of the gasification briquette are significantly improved. The resulting gasification briquette has high mechanical strength, low production cost, and is less prone to thermal explosion and pulverization during gasification, thus meeting the requirements for particulate feedstock in coal gasification. A second objective of this invention is to achieve carbon dioxide capture and resource utilization during the preparation of the composite gasification briquette, and simultaneously to dispose of hazardous coal tar residue by co-firing the aforementioned composite gasification briquette in a pressurized gasification slag furnace.

[0007] To achieve the above objectives, the following technical solution is adopted:

[0008] A calcium-based tar residue composite gasification briquette based on carbon dioxide capture, the composition of which is as follows by mass parts:

[0009] 100 parts by weight of pulverized coal; 1-10 parts by weight of quicklime (calculated as calcium oxide); 1-15 parts by weight of coal tar residue; 1-10 parts by weight of polymer binder; the amounts of all the above raw materials are after deducting moisture.

[0010] After the above mixture is shaped, it is dried using boiler flue gas, and the carbon dioxide is captured in it to complete the preparation.

[0011] In the optimized scheme, the composition of the calcium-based tar residue composite gasification briquettes, by mass fraction, is as follows:

[0012] 100 parts by weight of pulverized coal; 3-5 parts by weight of quicklime (calculated as calcium oxide); 5-8 parts by weight of coal tar residue; 4-6 parts by weight of polymer binder.

[0013] According to the above scheme, the particle size of the pulverized coal is ≤2mm.

[0014] According to the above scheme, the particle size of the coal tar residue is ≤5mm.

[0015] According to the above scheme, the polymer binder comprises 40-50 parts by weight of furfural resin, 50-40 parts by weight of polyacrylamide (PAM), and 2-5 parts by weight of silicate mixture.

[0016] The preparation method of the above-mentioned calcium-based tar residue composite gasification briquettes includes the following steps:

[0017] Coal powder, coal tar residue, quicklime, and polymer binder powder are added to a multi-stage mixer according to the formula requirements, water is added and the mixture is stirred thoroughly. The resulting mixture is fermented for more than 24 hours and then extruded to obtain a shaped mixture.

[0018] The resulting shaped mixture is fed into a drying tower and then introduced into the boiler flue gas. It reacts with CO2 in the flue gas to carbonize and dry simultaneously, yielding calcium-based tar residue composite gasified coal.

[0019] According to the above scheme, the moisture content of the resulting molded mixture is 10-15%, and the moisture content of the resulting calcium-based tar residue composite gasification briquette is 2-3%.

[0020] According to the above scheme, the boiler flue gas temperature is 100-200℃, with an optimized temperature of 120-130℃; the residence time of the mixture is 2-3 hours.

[0021] According to the above scheme, the boiler flue gas is drawn out from the rear of the flue gas dust collector, and the exhaust gas from the drying tower returns to the front of the flue gas dust collector at the tail of the boiler.

[0022] According to the above scheme, a temperature regulation chamber is set up before the boiler flue gas enters the drying tower to keep the temperature of the gas entering the drying tower within the optimal temperature range.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] The polymer binder used in this invention has a large number of active functional groups such as -OH and -COOH on its surface. Under alkaline conditions, hydrogen atoms in water form hydrogen bonds with oxygen atoms in the functional groups -OH and C=O on the surface of the binder and coal particles, respectively. After drying and dehydration, these bonds are transformed into chemical bonds between the binder and the coal particles. The non-active functional group ends of the binder have a macromolecular structure, which is stable and can effectively bind coal particles after being chemically bonded to them.

[0025] The gasified coal prepared by this invention captures CO2 from the boiler tail flue gas during the carbonization and drying processes, realizing the resource utilization of CO2 and achieving energy conservation and emission reduction. At the same time, quicklime can form a granular calcium carbonate skeleton, and its stable molecular structure effectively solidifies other components of the coal briquettes, thereby increasing the mechanical strength of the coal briquettes.

[0026] The gasified coal produced from the raw materials of this invention has good thermal stability, high mechanical strength, low production cost, and is not prone to thermal explosion and pulverization during gasification, thus meeting the requirements of coal gasification for particulate raw materials.

[0027] The gasified coal prepared by this invention is applied to a pressurized gasification slag furnace, which utilizes the large amount of solid carbon and organic components in coal tar residue to achieve resource utilization. At the same time, it can also treat and dispose of hazardous waste such as coal tar residue, thus achieving both environmental and economic benefits. Attached Figure Description

[0028] Figure 1 : Flowchart of the preparation process of calcium-based tar residue composite gasification briquettes of the present invention. Detailed Implementation

[0029] The following embodiments further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0030] A specific embodiment provides a calcium-based tar residue composite gasification briquette based on carbon dioxide capture, the composition of which is as follows by mass parts:

[0031] 100 parts by weight of pulverized coal; 1-10 parts by weight of slaked lime (calculated as calcium oxide); 1-15 parts by weight of coal tar residue; 1-10 parts by weight of polymer binder; the above mixture is shaped and then dried using boiler flue gas, capturing carbon dioxide while completing the preparation. Furthermore, the amounts of all the above raw materials are after deducting moisture; the moisture content of the shaped mixture is 10-15%, and the moisture content after drying is 2-3%.

[0032] In the optimized scheme, there are 100 parts by weight of pulverized coal; 3-5 parts by weight of quicklime (calculated as calcium oxide); 5-8 parts by weight of coal tar residue; and 4-6 parts by weight of polymer binder.

[0033] Specifically, the pulverized coal is crushed and screened to a particle size ≤2mm. The coal tar residue has a particle size ≤5mm.

[0034] Specifically, the polymeric adhesive comprises 40-50 parts by weight of furfural resin, 50-40 parts by weight of polyacrylamide (PAM), and 2-5 parts by weight of silicate mixture.

[0035] The polymer binder used contains a large number of active functional groups such as -OH and -COOH on its surface. Under alkaline conditions, hydrogen atoms in water form hydrogen bonds with oxygen atoms in the functional groups -OH and C=O on the surface of the binder and coal particles, respectively. After drying and dehydration, these bonds are transformed into chemical bonds between the binder and the coal particles. The non-active functional group ends of the binder are macromolecular structures with stable properties. After being chemically bonded to the coal, they can effectively bind the coal particles.

[0036] The specific implementation also provides a method for preparing the above-mentioned calcium-based tar residue composite gasification briquettes, as shown in the appendix. Figure 1 As shown, it includes the following steps:

[0037] Coal powder, coal tar residue, quicklime, and polymer binder powder are added to a multi-stage mixer according to the formula requirements, water is added and the mixture is stirred thoroughly. The resulting mixture is fermented for more than 24 hours and then extruded to obtain a shaped mixture.

[0038] The resulting shaped mixture is fed into a drying tower and then introduced into the boiler flue gas. It reacts with CO2 in the flue gas to carbonize and dry simultaneously, yielding calcium-based tar residue composite gasified coal.

[0039] Specifically, the boiler flue gas temperature is in the range of 100–200℃, with an optimized temperature of 120–130℃; the residence time of the mixture is 2–3 hours. This capture of CO2 from the boiler tail flue gas enables CO2 resource utilization, achieving energy conservation and emission reduction. Simultaneously, quicklime can form a granular calcium carbonate skeleton, and its stable molecular structure effectively solidifies other components of the briquettes, thereby increasing the mechanical strength of the briquettes.

[0040] Specifically, the boiler flue gas is drawn out from the rear of the flue gas dust collector, and the exhaust gas from the drying tower returns to the front of the flue gas dust collector at the tail of the boiler.

[0041] Ideally, the boiler flue gas is placed in a temperature-regulating chamber before entering the drying tower to maintain the temperature within the optimal range upon entering the drying tower.

[0042] The gasified briquettes obtained through this specific implementation method exhibit good thermal stability, high mechanical strength, and low production costs. They are also less prone to thermal explosion and pulverization during gasification, meeting the requirements for particulate feedstock in coal gasification. Applied to pressurized gasification slag furnaces, they utilize the abundant solid carbon and organic components in coal tar slag for resource utilization. Simultaneously, they enable the treatment and disposal of hazardous coal tar slag, achieving both environmental and economic benefits.

[0043] Specific embodiments 1, 2, 3 and comparative example 1 are prepared according to the ingredients in Table 1.

[0044] Table 1

[0045]

[0046] Because there are no national industry standards for testing the thermal stability, drop strength, and cold compressive strength of coal tar residue briquettes, the following standards were used for testing: MT / T 924-2004 (Determination of Thermal Stability of Industrial Briquettes), MT / T 925-2004 (Determination of Drop Strength of Industrial Briquettes), MT / T 748-2007 (Determination of Cold Compressive Strength of Industrial Briquettes), and MT / T 1073-2008 (Determination of Thermal Strength of Industrial Briquettes). The testing conditions and data processing methods were consistent with the relevant standards. The physicochemical properties of the composite gasification briquettes prepared in each embodiment were tested using the composite gasification briquette preparation method of this invention, as shown in Table 2.

[0047] Table 2

[0048] Appearance spherical disc spherical disc spherical disc spherical disc Particle diameter (mm) 30mm 30 30 30 Moisture (%) 3.10 3.20 2.90 3.10 Ash content (%) 12.50 13.20 11.60 10.70 Volatile matter (%) 20.30 21.30 18.90 16.80 Fixed carbon (%) 64.10 62.30 66.60 69.40 <![CDATA[Thermal stability S +13 (%)]]> 83.3 82.1 81.5 78.3 Drop strength (%) 83.2 82.6 82.4 80.6 Cold compressive strength (N / piece) 622 625 645 606 Thermal compressive strength (N / piece) 391 394 401 378

[0049] As can be seen from Table 2, compared with the comparative example, the present invention improves the thermal stability, drop strength, cold compressive strength, and hot compressive strength of the coal tar residue molding raw material.

[0050] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing calcium-based tar residue composite gasification briquettes, characterized in that... Includes the following steps: Coal powder, coal tar residue, quicklime, and polymer binder powder are added to a multi-stage mixer according to the formula requirements, water is added and the mixture is thoroughly stirred. The resulting mixture is fermented for more than 24 hours, and then extruded into molded material to obtain a molded mixture. The moisture content of the obtained molded mixture is 10-15%. The resulting shaped mixture is fed into a drying tower and circulated with boiler flue gas. It reacts with CO2 in the flue gas to carbonize and simultaneously dry, yielding calcium-based tar residue composite gasification briquettes. The boiler flue gas temperature is 100-200℃, and the mixture residence time is 2-3 hours. The resulting calcium-based tar residue composite gasification briquettes have a moisture content of 2-3%. The raw materials are as follows, by mass: 100 parts by weight of pulverized coal; 1-10 parts by weight of quicklime (calculated as calcium oxide); 1-15 parts by weight of coal tar residue; 1-10 parts by weight of polymer binder; the amounts of all the above raw materials are after deducting moisture. The polymeric adhesive comprises, by weight, 40-50 parts furfural resin, 50-40 parts polyacrylamide, and 2-5 parts silicate mixture.

2. The method for preparing calcium-based tar residue composite gasification briquettes as described in claim 1, characterized in that... The boiler flue gas is drawn out from the rear of the flue gas dust collector, and the exhaust gas from the drying tower returns to the front of the flue gas dust collector at the tail of the boiler.

3. The method for preparing calcium-based tar residue composite gasification briquettes as described in claim 1, characterized in that... The boiler flue gas is placed in a temperature regulating chamber before entering the drying tower to maintain the temperature within the optimal range upon entering the drying tower.

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