System and method for coupling garbage grading pyrolysis gasification with pulverized coal boiler

Abstract

The invention provides a system and method for coupling garbage grading pyrolysis gasification with a pulverized coal boiler. A solid substance inlet of a drying kiln is used for introducing household garbage for drying; a solid substance outlet of the drying kiln communicates with a solid substance inlet of the pyrolysis kiln and is used for performing pyrolysis treatment on the dried household garbage to obtain pyrolysis oil gas and garbage carbon; a pyrolysis substance outlet of the pyrolysis kiln is communicated with a gasified substance inlet of the fluidized bed gasification furnace and is used for carrying out gasification treatment on pyrolysis oil gas and garbage carbon to obtain combustible gas, a combustible gas outlet of the fluidized bed gasification furnace is communicated with a hearth of the coal-fired boiler for combustion power generation, and a flue gas outlet of the coal-fired boiler is communicated with an inlet of the flue gas treatment system. The garbage grading pyrolysis gasification system and the coal-fired power generation unit are deeply coupled, efficient garbage cleaning treatment and resource utilization are achieved, the energy utilization rate is increased, and pollutant emission is reduced.

Description

Technical Field

[0001] This invention belongs to the field of energy utilization and waste pyrolysis gasification technology, specifically to a system and method for waste grading pyrolysis gasification coupled with a pulverized coal boiler. Background Technology

[0002] Municipal solid waste is an unavoidable part of daily life, and improper management can seriously harm the ecological environment and human health. Currently, the main methods for treating and disposing of municipal solid waste include landfill, composting, and thermal disposal. Among these, thermal disposal is the most important method.

[0003] Waste thermal treatment includes incineration, pyrolysis, and gasification. Waste incineration is currently the most widely used thermal treatment method. It decomposes toxic organic matter and pathogenic microorganisms in waste through high temperatures, eliminating their toxicity. It has advantages such as high volume and weight reduction rates and rapid processing. Simultaneously, it achieves energy utilization by recovering the heat generated during incineration. However, municipal solid waste has high moisture content and low calorific value, resulting in low efficiency of waste-to-energy incineration and higher costs for waste-to-energy power generation compared to thermal power generation. Furthermore, waste incineration equipment requires large investments, and the treatment of incineration exhaust gases is expensive and challenging, making it unsuitable for integrated treatment of small-scale municipal solid waste in urban areas.

[0004] Currently, coal-fired boiler combustion technology is highly mature, with flexible and versatile combustion systems and sophisticated flue gas pollutant treatment systems. The method of coupling waste pyrolysis technology with coal-fired boilers to treat municipal solid waste provides a clean and harmless solution to the problem of urban waste disposal, while efficiently utilizing the oil and gas produced after waste pyrolysis and reducing the cost of coal-fired power plants. Therefore, utilizing waste pyrolysis coupled with coal-fired boilers can yield significant economic benefits. However, waste pyrolysis produces high-temperature oil and gas and charcoal, with the charcoal having a high calorific value and requiring reuse. High-temperature flue gas easily condenses to form pyrolysis oil and gas. If this pyrolysis oil and gas is not treated, it will be carried through pipelines and gradually cool during transport, forming a viscous liquid that adheres to the pipelines. Excessive pyrolysis oil and gas content not only causes corrosion, scaling, and blockages, threatening pipeline and equipment safety, but also leads to environmental organic pollution. Furthermore, since the pyrolysis oil and gas itself has a certain calorific value, its incomplete combustion also results in energy waste.

[0005] Therefore, designing a system and method for waste-graded pyrolysis gasification coupled with pulverized coal boiler is of great significance for the stable operation of waste-graded pyrolysis gasification coupled with coal-fired power generation units and the efficient utilization of waste resources. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a system and method for coupled waste grading pyrolysis gasification with a pulverized coal boiler. The waste grading pyrolysis gasification system is deeply coupled with a coal-fired power generation unit, converting municipal solid waste into combustible gas. The combustible gas is then fed into the furnace of the coal-fired boiler for combustion and power generation. The flue gas from the coal-fired boiler is treated before being discharged. This solution achieves efficient and clean waste treatment and resource utilization, improves energy utilization, and reduces pollutant emissions.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a system for waste grading, pyrolysis, gasification, and coupled pulverized coal boilers, wherein the solid material inlet of a drying kiln is used to introduce domestic waste for drying; the solid material outlet of the drying kiln is connected to the solid material inlet of a pyrolysis kiln for pyrolysis treatment of the dried domestic waste to obtain pyrolysis oil and gas and waste char; the pyrolysis material outlet of the pyrolysis kiln is connected to the gasification material inlet of a fluidized bed gasifier for gasification treatment of the pyrolysis oil and gas and waste char to obtain combustible gas; the combustible gas outlet of the fluidized bed gasifier is connected to the furnace of a coal-fired boiler for combustion and power generation; and the flue gas outlet of the coal-fired boiler is connected to the inlet of a flue gas treatment system.

[0008] Furthermore, the pyrolysis kiln is equipped with a central annular chamber and an outer annular cavity. The central annular chamber has a solid material inlet and a pyrolysis material outlet, while the outer annular cavity has a gaseous material inlet and a gaseous material outlet. The solid material inlet of the central annular chamber is connected to the solid material outlet of the drying kiln, and the pyrolysis material outlet of the central annular chamber is connected to the gasification material inlet of the fluidized bed gasifier. The gaseous material inlet of the outer annular cavity is connected to the high-temperature flue gas outlet of the coal-fired boiler, and the gaseous material outlet of the outer annular cavity is connected to the inlet of the flue gas treatment system.

[0009] Furthermore, the pyrolysis material outlet of the pyrolysis kiln includes the pyrolysis oil and gas outlet and the waste coal outlet, while the gasification material inlet of the fluidized bed gasifier includes the pyrolysis oil and gas inlet and the waste coal inlet; the pyrolysis oil and gas outlet of the pyrolysis kiln is connected to the pyrolysis oil and gas inlet of the fluidized bed gasifier, and the waste coal outlet of the pyrolysis kiln is connected to the waste coal inlet of the fluidized bed gasifier.

[0010] Furthermore, the flue gas treatment system includes a first inlet and a second inlet. The gaseous material inlet of the drying kiln is connected to the medium-temperature flue gas outlet of the coal-fired boiler, and the gaseous material outlet of the drying kiln is connected to the first inlet of the flue gas treatment system. The gaseous material inlet of the pyrolysis kiln is connected to the high-temperature flue gas outlet of the coal-fired boiler, and the gaseous material outlet of the pyrolysis kiln is connected to the first inlet of the flue gas treatment system. The heating medium inlet of the fluidized bed gasifier is connected to the high-temperature flue gas outlet of the coal-fired boiler. The low-temperature flue gas outlet of the coal-fired boiler is connected to the second inlet of the flue gas treatment system.

[0011] Furthermore, a high-temperature flue gas pipeline is installed at the economizer outlet of the coal-fired boiler. The high-temperature flue gas outlet of the coal-fired boiler is connected to the gaseous material inlet of the pyrolysis kiln and the heating medium inlet of the fluidized bed gasifier through the high-temperature flue gas pipeline. The direction of the high-temperature flue gas entering the pyrolysis kiln is the same as the direction of the organic matter entering, and the direction of the high-temperature flue gas entering the fluidized bed gasifier is the same as the direction of the pyrolysis oil and gas entering. The gasification temperature is 600℃~900℃.

[0012] Furthermore, it also includes an electrostatic cyclone dust collector, with the combustible gas outlet of the fluidized bed gasifier connected to the inlet of the electrostatic cyclone dust collector, the combustible gas outlet of the electrostatic cyclone dust collector connected to the furnace of the coal-fired boiler, and the pyrolysis oil and gas outlet of the electrostatic cyclone dust collector connected to the gasification material inlet of the fluidized bed gasifier.

[0013] This invention also provides a method for operating a system of waste grading pyrolysis gasification coupled with a pulverized coal boiler, the specific steps of which are as follows: Domestic waste is fed into a drying kiln for drying, and the dried organic matter is output. Dry organic matter is fed into a pyrolysis kiln for pyrolysis, and pyrolysis oil and gas and waste char are output. Pyrolysis oil and gas, waste charcoal and outside air are fed into the fluidized bed gasifier for gasification, and combustible gas is output. The combustible gas output from the fluidized bed gasifier is introduced into the furnace of a coal-fired boiler along with primary or secondary air for combustion and power generation. The flue gas generated from the combustion is treated by a flue gas treatment system before being discharged.

[0014] Furthermore, the drying kiln uses medium-temperature flue gas from a coal-fired boiler to dry the incoming domestic waste.

[0015] Furthermore, the pyrolysis kiln is heated by high-temperature flue gas from a coal-fired boiler.

[0016] Furthermore, the fluidized bed gasifier uses high-temperature flue gas from a coal-fired boiler for heating.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides a system for graded pyrolysis gasification coupled with a pulverized coal boiler, in which municipal solid waste is sequentially dried in a drying kiln and pyrolyzed in a pyrolysis kiln, achieving efficient and clean waste treatment. The drying process removes excess moisture from the waste, creating favorable conditions for subsequent pyrolysis; the pyrolysis process converts the waste into pyrolysis oil and gas and waste char, achieving initial waste reduction and resource recovery. Based on this, the pyrolysis products (pyrolysis oil and gas, waste char) are introduced into a fluidized bed gasifier for gasification, further converting them into combustible gas. Finally, the combustible gas is fed into a coal-fired boiler for combustion and power generation, allowing the energy in the waste to be fully released and utilized, significantly improving the energy utilization rate of waste, and truly realizing the transformation of municipal solid waste from "waste" to "energy," providing a sustainable resource utilization model for the waste treatment industry.

[0018] This invention innovatively integrates a waste-to-energy pyrolysis gasification system with a coal-fired power generation unit. The boiler flue gas generated during the coal-fired boiler power generation process provides a heat source for the drying and pyrolysis gasification of municipal solid waste, eliminating the need for a separate heating system. This design not only avoids resource waste caused by redundant construction but also significantly reduces the system's investment and construction costs. Simultaneously, the coupled system achieves cascaded energy utilization, fully recovering the waste heat from the coal-fired boiler flue gas, improving the overall energy efficiency of the system, saving operating costs for enterprises, and enhancing the project's economic feasibility and market competitiveness.

[0019] To address the safety hazards such as corrosion, scaling, and blockage that pyrolysis oil and gas can cause to pipelines and equipment during processing, this invention employs a fluidized bed gasifier to gasify the pyrolysis oil and gas. Through the gasification reaction, the pyrolysis oil and gas are converted into clean, combustible gases, effectively preventing damage to pipelines and equipment from direct transport and ensuring the long-term stable operation of the system. Furthermore, gasification treatment further improves the energy quality of the pyrolysis products, making them more compatible with coal-fired boiler systems, achieving a dual improvement in the efficient utilization of waste pyrolysis products and system safety. Attached Figure Description

[0020] Figure 1 This is a schematic flow diagram of a waste grading pyrolysis gasification coupled pulverized coal boiler system according to an embodiment of the present invention. In the diagram: 1. Drying kiln; 2. Pyrolysis kiln; 3. Fluidized bed gasifier; 4. Electrostatic cyclone dust collector; 5. Coal-fired boiler; 6. Flue gas treatment system; 7. Exhaust fan; a. Domestic waste; b. Flue gas; c. Pyrolysis oil and gas; d. Waste charcoal; e. Gasification gas; f. Combustible gas; g. Secondary air; h. Primary air; i. High-temperature flue gas passage; j. Medium-temperature flue gas passage; k. Flue gas meeting emission standards. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0022] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0023] This invention provides a system for waste grading, pyrolysis, gasification, and coupled pulverized coal boilers, comprising a drying kiln 1, a pyrolysis kiln 2, a fluidized bed gasifier 3, a coal-fired boiler 5, and a flue gas treatment system 6, wherein... Drying kiln 1 is used to input domestic waste and dry it, and output the dried organic matter. Pyrolysis kiln 2 is used to input organic matter output from the drying kiln and perform pyrolysis treatment, outputting pyrolysis oil and gas and waste charcoal; Fluidized bed gasifier 3 is used to input pyrolysis oil and gas and waste char from the pyrolysis kiln and perform gasification treatment to output combustible gas. Coal-fired boiler 5 is used to introduce combustible gas output from the fluidized bed gasifier into the furnace for combustion and power generation; The flue gas treatment system 6 is used to treat the flue gas from the drying kiln 1, the pyrolysis kiln 2 and the coal-fired boiler 5 for emission reduction. A further improvement of the present invention is that it also includes: an electrostatic cyclone dust collector 4, used to remove pyrolysis oil gas and dust carried in the combustible gas output after gasification treatment by the fluidized bed gasifier 3, and the combustible gas with pyrolysis oil gas and dust removed is input into the furnace of the coal-fired boiler 5 for combustion and power generation; the separated pyrolysis oil gas is input into the fluidized bed gasifier 3 for gasification treatment.

[0024] A further improvement of the present invention is that the electrostatic cyclone dust collector 4 can operate normally at an environment of 600°C.

[0025] A further improvement of the present invention is that the inlet of the high-temperature flue gas pipeline is located at the outlet of the economizer of the coal-fired boiler 5; the direction in which the high-temperature flue gas enters the pyrolysis kiln 2 is consistent with the direction in which the organic matter enters, and pyrolysis is carried out in a forward direction; the direction in which the high-temperature flue gas enters the fluidized bed gasifier 3 is consistent with the direction in which the pyrolysis oil and gas enter, and the gasification temperature is 600℃~900℃.

[0026] A further improvement of the present invention is that the drying kiln 1 is provided with a solid material inlet, a gaseous material inlet, a solid material outlet, and a gaseous material outlet; the pyrolysis kiln 2 is provided with a central annular chamber and an outer annular cavity; the central annular chamber is provided with a solid material inlet and a pyrolysis material outlet, and the outer annular cavity is provided with a gaseous material inlet and a gaseous material outlet; the solid material inlet of the central annular chamber is connected to the solid material outlet of the drying kiln 1; the fluidized bed gasifier 3 is provided with a heating medium inlet, a gasification medium inlet, a gasified material inlet, and a combustible gas outlet; the material outlet of the central annular chamber is connected to the gasified material inlet of the fluidized bed gasifier 3; the gaseous material outlet of the drying kiln 1 and the gaseous material outlet of the outer annular cavity of the pyrolysis kiln 2 are connected to the flue gas treatment system 6; the combustible gas outlet of the fluidized bed gasifier 3 is connected to the inlet of the electrostatic cyclone dust collector 4.

[0027] A further improvement of the present invention is that the flue gas treatment system 6 has a first inlet, a second inlet, and an outlet; the first inlet of the flue gas treatment system 6 is connected to the gaseous substance outlet of the pyrolysis kiln 2 and the gaseous substance outlet of the drying kiln 1, and the second inlet of the flue gas treatment system 6 is connected to the flue gas outlet of the coal-fired boiler 5. The operation method of the waste grading pyrolysis gasification coupled pulverized coal boiler system of the present invention includes the following steps: A drying kiln 1 inputs domestic waste and performs drying treatment, outputting dried organic matter; a pyrolysis kiln 2 inputs the organic matter output from the drying kiln 1 and performs pyrolysis treatment, outputting pyrolysis oil and gas and waste char; a fluidized bed gasifier 3 inputs the pyrolysis oil and gas and waste char output from the pyrolysis kiln 2 and external air for gasification treatment, outputting combustible gas; an electrostatic cyclone dust collector 4 inputs the combustible gas output from the fluidized bed gasifier 3 for dust removal and removal of pyrolysis oil and gas, outputting pyrolysis oil and gas and combustible gas; and a coal-fired boiler 5 introduces the combustible gas output from the electrostatic cyclone dust collector 4 into the furnace for combustion and power generation. When the drying kiln 1 performs drying treatment, it uses the flue gas output from the medium-temperature flue gas pipeline of the coal-fired boiler 5 for heating; when the pyrolysis kiln 2 performs pyrolysis treatment, it uses the flue gas output from the high-temperature flue gas pipeline of the coal-fired boiler 5 for heating; when the fluidized bed gasifier 3 performs gasification treatment, it uses the flue gas output from the high-temperature flue gas pipeline of the coal-fired boiler 5 for heating.

[0028] This invention couples a coal-fired power generation unit with a waste pyrolysis gasification system. The boiler flue gas generated by the coal-fired power generation unit is used to dry, pyrolyze, and gasify municipal solid waste. The waste char and combustible gas produced after drying and pyrolysis, as well as the combustible gas produced by the gasification of pyrolysis oil and gas, can be fed back into the coal-fired boiler for combustion and power generation. This achieves the resource utilization of municipal solid waste and solves a series of problems that threaten the safety of pipelines and equipment, such as corrosion, scaling, and blockage caused by excessive pyrolysis oil and gas content.

[0029] Example 1 like Figure 1 As shown, an embodiment of the present invention provides a waste grading pyrolysis gasification coupled pulverized coal boiler system, comprising: Drying kiln 1 is used to input domestic waste a and dry it, and output the dried organic matter. Pyrolysis kiln 2 is used to input the organic matter output from drying kiln 1 and perform pyrolysis treatment, outputting pyrolysis oil and gas c and waste char d; Fluidized bed gasifier 3 is used to input pyrolysis oil gas c and waste char d from pyrolysis kiln 2 and electrostatic cyclone dust collector 4 and perform gasification treatment, and output gasified gas e. The electrostatic cyclone dust collector 4 is used to remove dust and treat the gasified gas e output from the fluidized bed gasifier 3 to remove pyrolysis oil gas, and output combustible gas f and pyrolysis oil gas c. The pyrolysis oil gas c output from the pyrolysis kiln 2 is mixed with the gasified gas e from the fluidized bed gasifier 3 and enters the electrostatic cyclone dust collector 4. This method can avoid the condensation of pyrolysis oil gas c.

[0030] The coal-fired boiler 5 is used to introduce the primary air h, secondary air g, and combustible gas f output from the fluidized bed gasifier 3 into the furnace for combustion and power generation. When the drying kiln 1 performs drying treatment, it uses medium-temperature flue gas output from the medium-temperature flue gas pipe j of the coal-fired boiler 5 for heating, and the medium-temperature flue gas is sent into the drying kiln 1 by the induced draft fan 7; when the pyrolysis kiln 2 performs pyrolysis treatment, it uses high-temperature flue gas output from the high-temperature flue gas pipe i of the coal-fired boiler 5 for heating, and the high-temperature flue gas is sent into the pyrolysis kiln 2 by the induced draft fan 7; when the fluidized bed gasifier 3 performs gasification treatment, it uses high-temperature flue gas output from the high-temperature flue gas pipe i of the coal-fired boiler 5 for heating, and the high-temperature flue gas is sent into the fluidized bed gasifier 3 by the induced draft fan 7.

[0031] The flue gas treatment system 6 is used to treat the flue gas b output from the drying kiln 1, the pyrolysis kiln 2 and the coal-fired boiler 5 by removing dust, desulfurizing and denitrifying, so that the flue gas k emitted meets the emission standards.

[0032] This invention utilizes graded pyrolysis of waste to ensure efficient and clean waste treatment while simultaneously coupling with a coal-fired power plant system. This effectively utilizes the pyrolysis products, improves energy efficiency, and reduces pollutant emissions, resulting in significant economic benefits. Addressing the threats to pipelines and equipment safety posed by corrosion, scaling, and blockage caused by pyrolysis oil and gas, this invention employs a fluidized bed gasifier to gasify the pyrolysis oil and gas and utilizes flue gas from a coal-fired boiler to dry and pyrolyze municipal solid waste. This eliminates the need for external heating systems, saving on system investment and construction costs. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A system for waste grading pyrolysis gasification coupled with a pulverized coal boiler, characterized in that, The solid material inlet of the drying kiln (1) is used to feed domestic waste for drying. The solid material outlet of the drying kiln (1) is connected to the solid material inlet of the pyrolysis kiln (2) for pyrolysis treatment of the dried domestic waste to obtain pyrolysis oil and gas and waste char. The pyrolysis material outlet of the pyrolysis kiln (2) is connected to the gasification material inlet of the fluidized bed gasifier (3) for gasification treatment of pyrolysis oil and gas and waste char to obtain combustible gas. The combustible gas outlet of the fluidized bed gasifier (3) is connected to the furnace of the coal-fired boiler (5) for combustion and power generation. The flue gas outlet of the coal-fired boiler (5) is connected to the inlet of the flue gas treatment system (6).

2. The system for a waste grading pyrolysis gasification coupled pulverized coal boiler according to claim 1, characterized in that, The pyrolysis kiln (2) is provided with a central annular chamber and an outer annular cavity. The central annular chamber is provided with a solid material inlet and a pyrolysis material outlet, and the outer annular cavity is provided with a gaseous material inlet and a gaseous material outlet. The solid material inlet of the central annular chamber is connected to the solid material outlet of the drying kiln (1), and the pyrolysis material outlet of the central annular chamber is connected to the gasification material inlet of the fluidized bed gasifier (3). The gaseous material inlet of the outer annular cavity is connected to the high-temperature flue gas outlet of the coal-fired boiler (5), and the gaseous material outlet of the outer annular cavity is connected to the inlet of the flue gas treatment system (6).

3. The system for a waste grading pyrolysis gasification coupled with a pulverized coal boiler according to claim 2, characterized in that, The pyrolysis material outlet of the pyrolysis kiln (2) includes the pyrolysis oil and gas outlet and the waste coal outlet, and the gasification material inlet of the fluidized bed gasifier (3) includes the pyrolysis oil and gas inlet and the waste coal inlet; the pyrolysis oil and gas outlet of the pyrolysis kiln (2) is connected to the pyrolysis oil and gas inlet of the fluidized bed gasifier (3), and the waste coal outlet of the pyrolysis kiln (2) is connected to the waste coal inlet of the fluidized bed gasifier (3).

4. The system for a waste grading pyrolysis gasification coupled with a pulverized coal boiler according to claim 1, characterized in that, The flue gas treatment system (6) has a first inlet and a second inlet. The gaseous material inlet of the drying kiln (1) is connected to the medium-temperature flue gas outlet of the coal-fired boiler (5), and the gaseous material outlet of the drying kiln (1) is connected to the first inlet of the flue gas treatment system (6). The gaseous material inlet of the pyrolysis kiln (2) is connected to the high-temperature flue gas outlet of the coal-fired boiler (5), and the gaseous material outlet of the pyrolysis kiln (2) is connected to the first inlet of the flue gas treatment system (6). The heating medium inlet of the fluidized bed gasifier (3) is connected to the high-temperature flue gas outlet of the coal-fired boiler (5). The low-temperature flue gas outlet of the coal-fired boiler (5) is connected to the second inlet of the flue gas treatment system (6).

5. A system for a waste grading pyrolysis gasification coupled with a pulverized coal boiler according to claim 4, characterized in that, A high-temperature flue gas pipeline is installed at the economizer outlet of the coal-fired boiler (5). The high-temperature flue gas outlet of the coal-fired boiler (5) is connected to the gaseous material inlet of the pyrolysis kiln (2) and the heating medium inlet of the fluidized bed gasifier (3) through the high-temperature flue gas pipeline. The direction of the high-temperature flue gas entering the pyrolysis kiln (2) is consistent with the direction of the organic matter entering. The direction of the high-temperature flue gas entering the fluidized bed gasifier (3) is consistent with the direction of the pyrolysis oil and gas entering. The gasification temperature is 600℃~900℃.

6. The system for a waste grading pyrolysis gasification coupled pulverized coal boiler according to claim 1, characterized in that, It also includes an electrostatic cyclone dust collector (4), the combustible gas outlet of the fluidized bed gasifier (3) is connected to the inlet of the electrostatic cyclone dust collector (4), the combustible gas outlet of the electrostatic cyclone dust collector (4) is connected to the furnace of the coal-fired boiler (5), and the pyrolysis oil and gas outlet of the electrostatic cyclone dust collector (4) is connected to the gasification material inlet of the fluidized bed gasifier (3).

7. The operating method of the system for waste grading pyrolysis gasification coupled with pulverized coal boiler as described in claim 1, characterized in that, The specific steps are as follows: Domestic waste is fed into the drying kiln (1) for drying treatment, and the dried organic matter is output; Dry organic matter is fed into the pyrolysis kiln (2) for pyrolysis treatment, and pyrolysis oil and gas and waste char are output; Pyrolysis oil and gas, waste charcoal and external air are fed into the fluidized bed gasifier (3) for gasification treatment, and combustible gas is output. The combustible gas output from the fluidized bed gasifier (3) is introduced into the furnace of the coal-fired boiler (5) along with the primary or secondary air for combustion and power generation. The flue gas generated by combustion is treated by the flue gas treatment system (6) before being discharged.

8. The operating method of a waste grading pyrolysis gasification coupled pulverized coal boiler system according to claim 7, characterized in that, The drying kiln (1) uses the medium-temperature flue gas from the coal-fired boiler (5) to dry the input domestic waste.

9. The operating method of a waste grading pyrolysis gasification coupled pulverized coal boiler system according to claim 8, characterized in that, The pyrolysis kiln (2) is heated by the high-temperature flue gas from the coal-fired boiler (5).

10. The operating method of a waste grading pyrolysis gasification coupled pulverized coal boiler system according to claim 7, characterized in that, The fluidized bed gasifier (3) uses high-temperature flue gas from the coal-fired boiler (5) for heating.

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