A system and method for co-firing gasified fine slag in a pulverized coal boiler under a pulverized coal conveying method

Abstract

The present invention discloses a system and method for blending gasified fine slag in a pulverized coal boiler under a powder conveying mode, which mainly includes a gasified fine slag conveying system, a high-temperature and high-pressure atomization and drying system, and a new type of powder conveying system. The gasified fine slag conveying system includes a gasified fine slag storage bin, a positive pressure feeder, a paste pump, and a conveying pipeline connected in sequence; the high-temperature and high-pressure atomization and drying system includes a hot primary air bypass and an atomizing device, the atomizing air is drawn out from the hot primary air bypass, and the pressure head is increased by a booster fan and then led to the atomizing device to achieve atomization and drying of the gasified fine slag; the gasified fine slag carrying flow conveying pipeline at the outlet of the atomizing device is connected to the pulverized coal pipeline through a mixing device, forming a new type of powder conveying system, and achieving efficient mixing of the gasified fine slag carrying flow and the pulverized coal airflow. The present invention avoids the corrosion of the coal conveying system and the internal components of the coal mill by the gasified fine slag; realizes the atomization and drying of the gasified fine slag simultaneously; the blending ratio is easy to control; and the modification of the boiler body and the coal mill is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power generation and solid waste disposal, and particularly relates to a system and method for mixing gasified fine slag with a pulverized coal boiler in a pulverized coal conveying mode. Background Art

[0002] The State Council's "Carbon Peak Action Plan before 2030" aims to implement the major strategic decisions of carbon peak and carbon neutrality, solidly promote carbon peak action, and emphasize the need to strengthen the comprehensive utilization of bulk solid waste. Improve the level of comprehensive development and utilization of mineral resources and the comprehensive utilization rate, focus on bulk solid waste such as coal gangue, fly ash, tailings, co-existing minerals, smelting slag, industrial by-product gypsum, construction waste, and crop straw, support large-scale, large-value utilization, and encourage its application in replacing primary non-metallic minerals, sand and gravel and other resources. By 2025, the annual utilization of bulk solid waste will reach about 4 billion tons; by 2030, the annual utilization will reach about 4.5 billion tons.

[0003] With the large-scale promotion of coal gasification technology, the amount of coal gasification slag generated, stored and landfilled is increasing, causing serious environmental pollution and waste of land resources, which has an adverse impact on the sustainable development of coal chemical enterprises. The treatment of coal gasification slag is imminent. The proportion of coal gasification ash slag in solid waste is very large. The rational use of ash slag can not only eliminate the harm of ash slag, but also save a lot of material resources and turn waste into treasure. It is an important aspect related to the green and sustainable development of the coal chemical industry, and it is also an important aspect to achieve carbon peak and carbon neutrality. The comprehensive utilization of coal gasification slag mainly includes construction materials, soil and water remediation, residual carbon utilization based on blending, and high-value utilization based on catalyst carriers. The residual carbon content of gasification fine slag is higher than that of gasification coarse slag, resulting in low blending of construction materials, unstable quality, and poor economic and environmental benefits. Although the economic benefits of gasification fine slag in the development and utilization of carbon materials and the preparation of ceramic materials are relatively significant, they are all in the laboratory research stage. They are high in cost, complex processes, difficult to control impurities, and small downstream markets, and cannot be used on a large scale.

[0004] The high carbon content of gasification fine slag is one of the reasons why it is difficult to utilize. The recycling and blending of high-carbon gasification fine slag not only utilizes the carbon resources in it, but also converts high-carbon slag into low-carbon slag, which is beneficial to the utilization of gasification slag as building materials. The gasification fine slag has high moisture content and high viscosity. It can be directly introduced into the circulating fluidized bed boiler through the pipeline conveying system with the help of a paste pump for blending. The gasification fine slag can also be pre-dried and introduced into the coal transportation system. Due to the high moisture content of gasification fine slag, a large amount of steam and other drying media is consumed through the pre-drying process, the operating cost is high, and it is easy to cause secondary dust pollution. At the same time, the gasification fine slag is dried by the drying equipment and then mixed with raw coal to be sent to the boiler for combustion, which often blocks the crushing equipment and coal bunker, and the blending ratio is low.

[0005] Pulverized coal boiler is a boiler equipment that uses pulverized coal as fuel. It has the advantages of rapid and complete combustion, large capacity, high efficiency, wide adaptability to coal types, and easy control and regulation. The use of pulverized coal boilers to burn gasified fine slag has greatly broadened the treatment path of gasified fine slag, achieved a wider range of resource utilization of gasified fine slag, and reduced environmental pollution. However, the technology of directly burning gasified fine slag in pulverized coal boilers is not yet mature.

[0006] The moisture content of gasification fine slag is relatively high. Traditional transportation methods will lead to blockage of the coal transportation system and the coal feeding system, causing adhesion of the coal feeder belt, resulting in poor coal feeding and load fluctuations of the unit.

[0007] The synthesis gas of the gasification unit contains a large amount of chloride. When the synthesis gas passes through various levels of washing and flash evaporation processes, a considerable part of the chloride will eventually enter the gasification fine slag, which makes the gasification fine slag highly corrosive. If the gasification fine slag is directly introduced into the coal mill, it will accelerate the corrosion and wear of the internal parts of the coal mill, such as the grinding roller, grinding disc, separator, etc.; the water content of the gasification fine slag is high, and entering the coal mill will have a great impact on the drying output of the pulverizing system. Summary of the invention

[0008] In order to overcome the above technical problems, the present invention provides a system and method for the co-firing of gasified fine slag in a pulverized coal boiler under a pulverized powder conveying method. The gasified fine slag is introduced into the furnace of the pulverized coal boiler by adopting a pressurized pumping device, a high-temperature and high-pressure atomizing drying device, and a new type of pulverized powder conveying method. With the help of high-temperature and high-mixing intensity airflow, the efficient combustion and conversion of the gasified fine slag is promoted, thereby realizing large-scale disposal and high-value utilization of the gasified fine slag.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A system for mixing gasified fine slag with a pulverized coal boiler in a pulverized coal conveying mode, comprising a gasified fine slag conveying system, a high-temperature and high-pressure atomization drying system and a new type of pulverized coal conveying system;

[0011] The gasified fine slag conveying system includes a gasified fine slag storage bin 2 for storing finished gasified fine slag, and the gasified fine slag storage bin 2 is connected to the high-temperature and high-pressure atomization drying system through a positive pressure feeder 3 and a paste pump 4 via a conveying pipeline 5;

[0012] The high temperature and high pressure atomization drying system mainly comprises an atomization device 6 and a hot primary air bypass 8. The hot primary air bypass 8 is led out from a suitable position of the hot primary air main pipe 7. A booster fan 10 is arranged on the bypass and is connected to the atomization device 6 downstream.

[0013] The novel powder conveying system comprises a gasification fine slag entrained flow conveying pipeline 11 connected to the outlet of the atomization device 6 , and the gasification fine slag entrained flow conveying pipeline 11 is connected to the pulverized coal pipeline 14 through a mixing device 15 .

[0014] The gasification fine slag conveying system and the raw coal conveying system are arranged independently.

[0015] The pulverized coal pipeline 14 is connected to the raw coal via the coal supply system 12 through the coal mill 13 .

[0016] The mixing device 15 is a Y-shaped mixing structure, and the angle between the two branch pipes is relatively small; the outlet pipe of the mixing device 15 is connected to the furnace of the pulverized coal boiler 1 through the burner 16.

[0017] An atomizing air volume regulating valve 9 is provided between the hot primary air bypass 8 and the booster fan 10 .

[0018] A method for using a system for mixing and burning gasified fine slag in a pulverized coal boiler in a pulverized coal conveying mode comprises the following steps;

[0019] (a) Finished gasified fine slag is stored in gasified fine slag storage bin 2, and is led to atomization device 6 through positive pressure feeder 3 and paste pump 4 via conveying pipeline 5; raw coal is led to coal mill 13 through coal feeding system 12, and is led to coal powder pipeline 14 after grinding and drying;

[0020] (b) The hot air used for atomizing and drying the gasified fine slag is led out through the hot primary air bypass 8, pressurized by the booster fan 10 and led to the atomizing device 6, and the high-temperature and high-pressure hot air realizes the atomization and drying of the gasified fine slag; the atomizing air flow rate is adjusted by the atomizing air volume regulating valve 9 to improve the performance of the atomizing device 6;

[0021] (c) The gasified fine slag is fully atomized and dried by the atomizing device 6, and the resulting gasified fine slag carrying flow is introduced into the pulverized coal pipeline 14 through the mixing device 15;

[0022] (d) After the gasified fine slag carrying flow is mixed with the pulverized coal airflow, it is introduced into the furnace of the pulverized coal boiler 1 by the burner 16. With the help of the high-temperature and high-mixing-intensity airflow, the efficient combustion conversion of the gasified fine slag is achieved.

[0023] Beneficial effects of the present invention:

[0024] The present invention uses a paste pump to transport gasified fine slag, making full use of the high moisture content of gasified fine slag. With this transportation scheme, the gasified fine slag does not pass through the coal conveying system, the coal feeding system and the coal mill, thus avoiding the blockage of the raw coal bunker, reducing the adhesion of the coal feeder belt to the raw coal, and avoiding the corrosion of the raw coal bunker and the internal parts of the coal mill by the highly corrosive gasified fine slag; avoiding the direct impact of the gasified fine slag on the drying output of the pulverizing system.

[0025] The present invention realizes the atomization and drying of gasified fine slag and promotes the full mixing of the gasified fine slag carrying flow and the coal powder air flow by means of a high-temperature and high-pressure drying atomization device and a novel powder conveying system.

[0026] In the present invention, the gasified fine slag is mixed and burned, and only the coal powder pipeline in front of the furnace is partially modified to optimize the mixing mode, and the boiler body and the coal mill body are not involved.

[0027] The particle size of gasified fine slag in the present invention is very small, and can be directly introduced into the furnace through the coal powder pipeline without being ground by the coal mill, and its burnout characteristics are basically not affected;

[0028] In the present invention, the gasified fine slag does not need to be additionally pre-dried, thereby reducing the investment cost of the drying device and the steam cost.

[0029] The blending ratio of gasified fine slag in the present invention is easy to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a system layout diagram for implementing the mixed combustion of gasified fine slag in a pulverized coal boiler according to the present invention.

[0031] Description of reference numerals:

[0032] 1 is a pulverized coal boiler; 2 is a gasification fine slag storage bin; 3 is a positive pressure feeder; 4 is a paste pump; 5 is a conveying pipeline; 6 is an atomizing device; 7 is a hot primary air main pipe; 8 is a hot primary air bypass; 9 is an atomizing air volume regulating valve; 10 is a booster fan; 11 is a gasification fine slag carrying flow conveying pipeline; 12 is a raw coal feeding system; 13 is a coal mill; 14 is a pulverized coal pipeline; 15 is a mixing device; 16 is a burner. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0034] See also Figure 1 The present invention provides a system suitable for mixing and burning gasified fine slag in a pulverized coal boiler, which mainly includes a pulverized coal boiler 1; a gasified fine slag storage bin 2; a positive pressure feeder 3; a paste pump 4; a conveying pipeline 5; an atomizing device 6; a hot primary air bypass 8; a booster fan 10; a pulverized coal pipeline 14; and a mixing device 15. Atomizing air is led from the hot primary air bypass 8 to the atomizing device 6; and the gasified fine slag carrying flow conveying pipeline 11 is connected to the pulverized coal pipeline 14 through the mixing device 15.

[0035] When the pulverized coal boiler is mixed with gasified slag, the gasified slag conveying system and the raw coal conveying system are arranged independently. The gasified slag is stored in the gasified slag storage bin 2, and is led to the atomization device 6 through the positive pressure feeder 3 and the paste pump 4 through the conveying pipeline 5; the raw coal is led to the coal mill 13 through the coal feeding system 12, and is led to the pulverized coal pipeline 14 after grinding and drying.

[0036] The gasified fine slag is atomized and dried by the atomizing device 6 to form a gasified fine slag entrained flow. The gasified fine slag entrained flow conveying pipeline 11 is connected to the coal powder pipeline 14 through a Y-shaped mixing device 15, and the angle between the two branch pipelines is small.

[0037] The gasified fine slag entrained flow is mixed with the pulverized coal airflow and then introduced into the furnace of the pulverized coal boiler 1 by the burner 16 .

[0038] The hot air used for gasification, fine slag atomization and drying is led out through the hot primary air bypass 8, pressurized by the booster fan 10 and then led to the atomization device 6. The atomization air flow rate is adjusted by the atomization air volume regulating valve 9 to improve the performance of the atomization device.

[0039] The output and number of the atomizing devices 6 determine the proportion of gasified fine slag blended in the pulverized coal boiler.

[0040] The specific implementation process of the present invention is:

[0041] The gasified fine slag storage bin 2 is used to store the finished gasified fine slag after impurities (solid bulk objects, metals, etc.) are removed; the gasified fine slag is quantitatively fed and metered through the positive pressure feeder 3; the gasified fine slag is pressurized through the paste pump 4, and then led to the atomization device 6 through the conveying pipeline 5. The above system and method are used to complete the primary conveying of the gasified fine slag.

[0042] The high-temperature hot primary air is led out through the bypass, and the pressure head is increased by the booster fan 10, and then introduced into the atomizing device 6. The atomizing device 6 completes the atomization and drying of the gasified fine slag, forming a gasified fine slag entrained flow, which is introduced into the coal powder pipeline 14 through the gasified fine slag entrained flow conveying pipeline 11 and the mixing device 15. The above system and method are used to complete the secondary conveying of the gasified fine slag. A thermocouple can be arranged on the gasified fine slag entrained flow conveying pipeline 11 to monitor the temperature of the gasified fine slag entrained flow after mixing.

[0043] An atomizing air volume regulating valve 9 for regulating the air volume is arranged on the hot primary air bypass 8. The valve is an electric valve and can be feedback-controlled according to the temperature of the gasified fine slag entrainment flow.

[0044] The raw coal is led to the coal mill 13 through the coal feeding system 12, and after being ground and dried, it is led to the coal powder pipeline 14. The above system and method are used to complete the transportation of raw coal.

[0045] The mixing device 15 adopts a Y-shaped structure, and the gasification fine slag carrying flow pipeline and the coal powder airflow pipeline are arranged at a small angle. In specific implementation, an angle of no more than 30° can be adopted, or the end of the gasification fine slag carrying flow conveying pipeline can be built into the coal powder pipeline 14, so that the direction of the gasification fine slag carrying flow is consistent with the direction of the coal powder airflow, thereby improving the mixing effect.

[0046] The gasified fine slag entrained flow and the pulverized coal airflow are mixed and then introduced into the furnace of the pulverized coal boiler 1 through the burner 16 .

[0047] In the specific implementation of the present invention, the gasification fine slag conveying system, the atomizing device, the mixing structure and the downstream pulverized coal pipeline thereof are all required to be made of corrosion-resistant materials, and the atomizing device may adopt a multi-stage atomizing structure.

[0048] The above content is a further detailed description of the present invention in combination with a specific preferred embodiment. It cannot be determined that the specific embodiments of the present invention are limited to this. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the present invention and the scope of patent protection determined by the submitted claims.

Claims

1. A system for mixing gasified fine slag with pulverized coal boiler in a pulverized coal conveying mode, characterized in that: Including gasification fine slag conveying system, high temperature and high pressure atomization drying system, raw coal conveying system and new powder conveying system; The gasified fine slag conveying system comprises a gasified fine slag storage bin (2) for storing finished gasified fine slag, and the gasified fine slag storage bin (2) is connected to the high-temperature and high-pressure atomization drying system via a positive pressure feeder (3), a paste pump (4) and a conveying pipeline (5); The high-temperature and high-pressure atomization drying system comprises a hot primary air bypass (8) and an atomization device (6), wherein the hot primary air bypass (8) is led out from a suitable position of the hot primary air main pipe (7), and a booster fan (10) is arranged on the bypass and connected to the atomization device (6) at the downstream; The raw coal conveying system comprises a coal feeding system (12), a coal mill (13) and a pulverized coal pipeline (14); The novel powder conveying system comprises a gasified fine slag entrained flow conveying pipeline (11) connected to the outlet of the atomizing device (6), and the gasified fine slag entrained flow conveying pipeline (11) is connected to the pulverized coal pipeline (14) via a mixing device (15); The gasification fine slag conveying system and the raw coal conveying system are arranged independently; The mixing device (15) adopts a Y-shaped structure, and the gasified fine slag carrying flow conveying pipeline (11) and the pulverized coal pipeline (14) are arranged at a small angle; the outlet pipeline of the mixing device (15) is connected to the furnace of the pulverized coal boiler (1) through the burner (16).

2. The system for mixing gasified fine slag with pulverized coal boiler in a pulverized coal conveying mode according to claim 1 is characterized in that: An atomizing air volume regulating valve (9) is provided between the hot primary air bypass (8) and the booster fan (10).

3. The system for mixing gasified fine slag with pulverized coal boiler in a pulverized coal conveying mode according to claim 1 is characterized in that: The gasification fine slag conveying system, the atomizing device (6), the mixing device (15) and the downstream pulverized coal pipelines thereof are all required to be made of corrosion-resistant materials.

4. A method for using a system for mixing gasified fine slag with a pulverized coal boiler in a pulverized coal conveying mode according to any one of claims 1 to 3, characterized in that: The steps include: (a) The finished gasified fine slag is stored in a gasified fine slag storage bin (2), quantitatively fed by a positive pressure feeder (3), pressurized by a paste pump (4), and led to an atomizing device (6) via a conveying pipeline (5), completing the primary conveying of the gasified fine slag. The raw coal is led to a coal mill (13) via a coal feeding system (12), and after being ground and dried, is led out to a coal powder pipeline (14); (b) High-temperature hot air used for atomizing and drying the gasified fine slag is drawn out through the hot primary air bypass (8), and introduced into the atomizing device (6) after the pressure head is increased by a booster fan (10); the gasified fine slag is atomized and dried through the atomizing device (6), and a gasified fine slag entrained flow is formed; the gasified fine slag entrained flow is introduced into the pulverized coal pipeline (14) through the gasified fine slag entrained flow conveying pipeline (11) and the mixing device (15), or the end of the gasified fine slag entrained flow conveying pipeline (11) is built into the pulverized coal pipeline (14), so that the direction of the gasified fine slag entrained flow is consistent with the direction of the pulverized coal airflow, and the secondary conveying of the gasified fine slag is completed; the atomizing air flow rate is adjusted by the atomizing air volume regulating valve (9) arranged on the hot primary air bypass (8), and the performance of the atomizing device (6) is improved; (c) After the gasified fine slag carrying flow and the pulverized coal airflow are mixed, they are introduced into the furnace of the pulverized coal boiler (1) through the burner (16), and with the help of the high-temperature and high-mixing-intensity airflow, efficient combustion conversion of the gasified fine slag is achieved.

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