Gasification system and method for total heat recovery via waste heat boilers

Abstract

Disclosed in the embodiments of the present invention are a gasification system and method for total heat recovery via waste heat boilers. The system comprises a gasification chamber, a radiant waste heat boiler, a slag pool chamber, a convective waste heat boiler, a quencher and a circulating-gas treatment device, wherein a mixture of biomass and an oxidizer is gasified in the gasification chamber to generate high-temperature crude syngas and molten slag; the high-temperature crude syngas is output from a gas outlet of the radiant waste heat boiler to the convective waste heat boiler, the convective waste heat boiler exchanges heat with the high-temperature crude syngas by means of a heat-exchange tube, and the cooled high-temperature crude syngas is output to the quencher; the quencher quenches the high-temperature crude syngas and outputs quenched low-temperature crude syngas through a syngas outlet; and the circulating-gas treatment device transmits a portion of the low-temperature crude syngas to a circulating-gas inlet of the radiant waste heat boiler, forming a mixture of low-temperature crude syngas and high-temperature crude syngas in the radiant waste heat boiler, thereby reducing the temperature of the high-temperature crude syngas. In the present invention, the outlet temperature of the radiant waste heat boiler is maintained within an optimal range by means of circulating-gas quenching.

Description

A waste boiler heat recovery gasification system and method Technical Field

[0001] This invention relates to the field of biomass fluidized bed gasification technology, and in particular to a waste boiler heat recovery gasification system and method. Background Technology

[0002] Biomass or biomass carbon (non-coal) powder is converted into high-quality crude syngas through fluidized bed gasification technology, achieving the industrial goal of converting biomass or carbonized biomass into high-quality crude syngas. Biomass powder, oxygen, and steam are fed into the gasifier through a gasification burner, where a non-catalytic partial oxidation reaction occurs under high temperature and pressure, generating high-temperature crude syngas and molten ash.

[0003] In fluidized bed gasification technology using pulverized coal as raw material, a gasification-quench process is commonly used for high-temperature gas sensible heat recovery. The gasification-quench process involves the high-temperature crude syngas and molten ash in the gasification chamber of the gasifier being cooled by quench water before entering the quench chamber water bath. The high-temperature crude syngas, initially 1200–1600℃, cools to 200–300℃, while the molten ash is cooled and solidified by the quench water and enters the water bath.

[0004] In this gasification-quenching process, the sensible heat recovery efficiency of the high-temperature gas is low, the water system circulation volume is large, the fine ash content is high, the equipment and pipelines are severely eroded, and the discharge of solid waste and wastewater is large.

[0005] Currently, there is a lack of efficient solutions for recovering the sensible heat of high-temperature gases in biomass gasification processes. Summary of the Invention

[0006] The purpose of this invention is to provide a complete waste boiler heat recovery gasification system and method to at least partially solve the above-mentioned problems of the prior art.

[0007] To achieve the above objectives, the present invention provides a complete waste boiler heat recovery gasification system, comprising a gasification chamber, a radiant waste boiler, a slag pool chamber, a convective waste boiler, a quencher, and a circulating gas treatment device, wherein...

[0008] The gasification chamber is used to gasify the mixed biomass and oxidant to generate high-temperature crude syngas and liquid slag.

[0009] The radiant waste boiler is connected to the gasification chamber and receives the high-temperature crude syngas and the liquid slag generated in the gasification chamber. It is provided with a gas outlet and a circulating gas inlet. The high-temperature crude syngas is output to the convective waste boiler through the gas outlet, and the low-temperature crude syngas input by the circulating gas treatment device is received through the circulating gas inlet. A slag outlet is provided and connected to the slag pool chamber to output slag into the slag pool chamber.

[0010] The slag pool chamber is connected to the radiant waste pot and receives the liquid molten slag passing through the radiant waste pot.

[0011] The convective waste boiler is connected to the radiant waste boiler, receives the high-temperature crude syngas output from the radiant waste boiler, and exchanges heat with the high-temperature crude syngas through heat exchange tubes to reduce the temperature of the high-temperature crude syngas.

[0012] The quencher is connected to the convection waste boiler and receives the high-temperature crude syngas output from the convection waste boiler; the quencher is equipped with a quenching liquid, and the low-temperature crude syngas quenched by the quenching liquid is output through the syngas outlet.

[0013] The circulating gas treatment device is connected to the circulating gas inlet of the radiant waste boiler and is used to transfer a portion of the low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler, forming a mixed gas of the low-temperature crude syngas and the high-temperature crude syngas in the radiant waste boiler, thereby reducing the temperature of the high-temperature crude syngas.

[0014] In a preferred embodiment, the system further includes:

[0015] The fly ash treatment device is located between the convective waste boiler and the quencher. It removes fly ash from the high-temperature crude syngas by gas-solid separation and then outputs the high-temperature crude syngas to the quencher.

[0016] In a preferred embodiment, the fly ash treatment device includes a cyclone separator or a filter.

[0017] In a preferred embodiment, the convective waste boiler includes a superheated section heat exchange tube and an evaporation section heat exchange tube. The superheated section heat exchange tube contains saturated steam, and the evaporation section heat exchange tube contains saturated boiler water. The saturated steam in the superheated section heat exchange tube generates superheated steam after heat exchange and is then output.

[0018] In a preferred embodiment, the system further includes a syngas scrubbing device connected to the quencher and the circulating gas treatment device, for scrubbing the low-temperature crude syngas with a scrubbing liquid in a multi-layer tray;

[0019] The circulating gas treatment device is connected to the syngas scrubbing device, receives the low-temperature crude syngas after scrubbing by the syngas scrubbing device, and transmits a portion of the scrubbed low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler.

[0020] In a preferred embodiment, the circulating gas treatment device includes a compression device for pressurizing the low-temperature crude syngas output to the circulating gas inlet of the radiant waste boiler, and outputting the pressurized low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler.

[0021] In a preferred embodiment, the circulating gas treatment device is further used to regulate the temperature of the low-temperature crude syngas output to the circulating gas inlet of the radiant waste boiler.

[0022] In a preferred embodiment, a slag outlet is provided below the quencher for discharging wastewater that meets the first condition and recycling wastewater that meets the second condition back into the quencher.

[0023] In a preferred embodiment, the gasification chamber includes a top burner for injecting the mixture of biomass and oxidant into the gasification chamber.

[0024] Another aspect of the present invention provides a method for heat recovery using the above-described waste boiler heat recovery gasification system, comprising:

[0025] In the gasification chamber, the mixed biomass and oxidant are gasified to generate high-temperature crude syngas and liquid slag.

[0026] The high-temperature crude syngas is output from the gas outlet of the radiant waste boiler to the convective waste boiler, and the liquid slag is output from the slag outlet to the slag pool chamber.

[0027] The high-temperature crude syngas output from the radiant waste boiler is received by the convection waste boiler, and heat is exchanged with the high-temperature crude syngas through heat exchange tubes. The high-temperature crude syngas with reduced temperature is then output to the quencher.

[0028] The high-temperature crude syngas is quenched by the quenching liquid in the quencher, and the quenched low-temperature crude syngas is output through the syngas outlet.

[0029] A portion of the low-temperature crude syngas is transferred to the circulating gas inlet of the radiant waste boiler via a circulating gas treatment device, forming a mixed gas of the low-temperature crude syngas and the high-temperature crude syngas within the radiant waste boiler, thereby reducing the temperature of the high-temperature crude syngas.

[0030] Compared with the prior art, the present invention has at least the following advantages:

[0031] By employing a full waste heat recovery gasifier, utilizing circulating gas quenching, radiant waste heat boiler, and convective waste heat boiler heat exchange modes, the sensible heat of high-temperature gas is efficiently recovered, maintaining the outlet temperature of the radiant waste heat boiler within the optimal range and reducing fly ash stickiness. Simultaneously, the heat exchange tubes are protected to effectively prevent fly ash from adhering to the walls of the convective waste heat boiler heat exchange tubes. Furthermore, gaseous alkali metals are solidified, preventing their adhesion within the convective waste heat boiler heat exchange tubes. Furthermore, the use of top-mounted burners improves the flow field distribution in the gasification chamber, enhances the combustion reaction, and increases the carbon conversion rate of the gasification reaction. The fly ash generated during the gasification reaction undergoes dry ash removal and wet dechlorination, significantly reducing wastewater discharge. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the structure of the waste boiler heat recovery gasification system provided in an embodiment of the present invention.

[0033] Figure 2 is a schematic diagram of the structure of a waste boiler heat recovery gasification system provided in another embodiment of the present invention.

[0034] Figure 3 is a schematic flowchart of the waste boiler heat recovery gasification method provided in an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate to understand the embodiments of the invention described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a product or device comprising a series of units is not necessarily limited to those explicitly listed, but may include other units not explicitly listed or inherent to such product or device.

[0037] In this invention, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation.

[0038] Furthermore, in addition to indicating direction or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in certain situations to indicate a dependency or connection. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0039] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Example 1

[0042] This invention provides a complete waste boiler heat recovery gasification system. Figure 1 shows a schematic diagram of the system. As shown in Figure 1, the system includes a gasification chamber 10, a radiant waste boiler 20, a slag pool chamber 30, a convective waste boiler 40, a quencher 50, and a circulating gas treatment device 60. Wherein:

[0043] Gasification chamber 10 is used to gasify the mixed biomass and oxidant to generate high-temperature crude syngas and liquid slag.

[0044] The gasification chamber 10 may include a top-mounted burner for injecting a mixture of biomass and oxidant into the gasification chamber. This top-mounted burner injection feeding method enhances material mixing within the gasification chamber, improves the internal flow field distribution, results in more uniform contact and mixing of reactants, and leads to more complete combustion. The co-current flow of gas and slag allows for clear monitoring of the pressure difference at the inlet, facilitating temperature adjustment and simplifying operation, thus significantly reducing operating costs.

[0045] The number and arrangement of the top burners can be flexibly adjusted. For example, one top burner can be set, or two to four top burners can be set. The arrangement can be concentric with the axis or at other angles.

[0046] The gasification chamber 10, the radiant waste boiler 20, and the slag pool chamber 30 can be located on the same axis to facilitate gas flow and molten slag discharge.

[0047] The radiant waste boiler 20 is connected to the gasification chamber 10 and receives the high-temperature crude syngas and liquid slag generated in the gasification chamber 10. It is equipped with a gas outlet 21 and a circulating gas inlet 22. The high-temperature crude syngas is output to the convective waste boiler through the gas outlet 21, and the low-temperature crude syngas input by the circulating gas treatment device 60 is received through the circulating gas inlet 22. A slag outlet is provided and connected to the slag pool chamber 30 to output slag into the slag pool chamber 30.

[0048] In this process, the high-temperature crude syngas generated in the gasification chamber 10 is mixed with the low-temperature crude syngas input into the circulating gas treatment device 60, thereby achieving rapid cooling of the high-temperature crude syngas and increasing efficiency. Moreover, by adjusting the temperature of the low-temperature crude syngas, the target temperature of the cooled high-temperature crude syngas can be flexibly adjusted, allowing the target temperature of the cooled high-temperature crude syngas to better suit the materials in the radiant waste boiler and reduce damage to the materials.

[0049] The slag pool chamber 30 is connected to the radiant waste pot 20 and receives the liquid slag passing through the radiant waste pot 20.

[0050] The slag pool chamber 30 can be equipped with quench water, which allows the liquid slag to solidify rapidly upon contact with the quench water and be discharged as solid slag. The system may also include a slag remover for solid-liquid separation of the slag within the slag pool chamber.

[0051] The convection waste heat boiler 40 is connected to the radiant waste heat boiler 20. It receives the high-temperature crude syngas output from the radiant waste heat boiler 20 and exchanges heat with the high-temperature crude syngas through heat exchange tubes to reduce the temperature of the high-temperature crude syngas.

[0052] The convective waste heat boiler can include superheated section heat exchange tubes and evaporation section heat exchange tubes. The superheated section heat exchange tubes contain saturated steam, and the evaporation section heat exchange tubes contain saturated boiler water. The saturated steam in the superheated section heat exchange tubes generates superheated steam after heat exchange and is then output. High-temperature crude syngas first enters the superheated section, where it exchanges heat with the saturated steam. The superheated steam, a byproduct, is then sent out. The temperature of the crude syngas decreases slightly. Then, in the evaporation section, it exchanges heat again with the saturated boiler water, further reducing its temperature. As a byproduct of the system, the superheated steam improves the system's resource utilization rate.

[0053] The quencher 50 is connected to the convection waste boiler 40 and receives the high-temperature crude syngas output from the convection waste boiler 40. The quencher 50 is equipped with a quenching liquid, and the low-temperature crude syngas quenched by the quenching liquid is output through the syngas outlet.

[0054] The quencher receives the high-temperature crude syngas output from the convective waste boiler 40 through a pipeline, and the pipeline outlet can be located below the liquid surface of the quenching liquid 51; a syngas outlet 53 is set above the quenching liquid in the quencher, and the quenched crude syngas is output through the syngas outlet 53.

[0055] A slag-water outlet 52 can be provided below the quencher for discharging wastewater. As an optional solution, the slag-water outlet 52 is used to discharge wastewater that meets a first condition, and to recycle wastewater that meets a second condition back into the quencher. The first and second conditions can be impurity concentration thresholds in the wastewater. Two impurity concentration thresholds can be set, one larger and one smaller. Wastewater exceeding the smaller threshold is discharged and then recycled back into the quencher. For example, a circulation inlet can be provided above the quencher, and wastewater exceeding the larger threshold is discharged. The crude syngas includes one or more of fly ash, CO, and H2, as well as HCl. The first condition includes an HCl concentration threshold. That is, wastewater with a concentration greater than the HCl concentration threshold is discharged to a wastewater treatment device. In a preferred embodiment, the system may further include a wastewater treatment device, equipped with two or more stages of flash evaporation mechanisms, a settling tank, and a filtration mechanism to treat the wastewater discharged from the quencher.

[0056] The circulating gas treatment device 60 is connected to the circulating gas inlet 22 of the radiant waste boiler 20. It is used to transfer a portion of the low-temperature crude syngas to the circulating gas inlet 22 of the radiant waste boiler 20, forming a mixed gas of low-temperature crude syngas and high-temperature crude syngas in the radiant waste boiler 20, thereby reducing the temperature of the high-temperature crude syngas.

[0057] The circulating gas treatment device 60 may include a compression device for pressurizing the low-temperature crude syngas output to the circulating gas inlet of the radiant waste boiler, and then outputting the pressurized low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler. Additionally, the circulating gas treatment device 60 can also be used to adjust the temperature of the low-temperature crude syngas output to the circulating gas inlet of the radiant waste boiler, so as to flexibly control the temperature of the low-temperature crude syngas as needed, thereby regulating the temperature reduction of the high-temperature crude syngas in the gasification chamber.

[0058] In a preferred embodiment, the system may further include:

[0059] A fly ash treatment unit, located between a convective waste boiler and a quencher, removes fly ash from the high-temperature crude syngas using a gas-solid separation method before outputting the high-temperature crude syngas to the quencher. This fly ash treatment unit may include a cyclone separator or a filter. Alternatively, the fly ash treatment unit can be located between a radiant waste boiler and a convective waste boiler, where the high-temperature crude syngas output from the radiant waste boiler is first treated to remove ash, and then cooled by the convective waste boiler.

[0060] In a preferred embodiment, the system may further include a syngas scrubbing device connected to the quencher and the circulating gas treatment device, used to scrub the low-temperature crude syngas with scrubbing liquid in a multi-layer tray; the circulating gas treatment device is connected to the syngas scrubbing device, receives the scrubbed low-temperature crude syngas, and transfers a portion of the scrubbed low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler. The syngas scrubbing device can be a standalone unit or integrated with the quencher.

[0061] By employing a full waste heat recovery gasifier, utilizing circulating gas quenching, radiant waste heat boiler, and convective waste heat boiler heat exchange modes, the sensible heat of high-temperature gas is efficiently recovered, maintaining the outlet temperature of the radiant waste heat boiler within the optimal range and reducing fly ash stickiness. Simultaneously, the heat exchange tubes are protected to effectively prevent fly ash from adhering to the walls of the convective waste heat boiler heat exchange tubes. Furthermore, gaseous alkali metals are solidified, preventing their adhesion within the convective waste heat boiler heat exchange tubes. Furthermore, the use of top-mounted burners improves the flow field distribution in the gasification chamber, enhances the combustion reaction, and increases the carbon conversion rate of the gasification reaction. The fly ash generated during the gasification reaction undergoes dry ash removal and wet dechlorination, significantly reducing wastewater discharge.

[0062] Example 2

[0063] This invention provides a complete waste boiler heat recovery gasification system, and Figure 2 shows a schematic diagram of the system. As shown in Figure 2, the system includes a gasification chamber 10, a radiant waste boiler 20, a slag pool chamber 30, a convective waste boiler 40, a fly ash treatment device 70, a quencher and syngas scrubbing device 50, and a circulating gas treatment device 60.

[0064] Gasification chamber 10 is used to gasify the mixed biomass and oxidant to generate high-temperature crude syngas and liquid slag.

[0065] The gasification chamber 10 may include a top burner 11 for injecting a mixture of biomass and oxidant into the gasification chamber. The top burner is concentric with the axis of the gasification chamber.

[0066] The gasification chamber 10, the radiant waste boiler 20, and the slag pool chamber 30 are located on the same axis, which facilitates gas flow and molten slag discharge.

[0067] Biomass carbon powder from the pulverizing unit is conveyed to the burner 11 at the top of the gasifier via a thermal inert gas dense phase. An oxygen-steam mixture is also fed into the burner as a gasifying agent. After the biomass carbon powder, oxygen, and steam are uniformly mixed in the gasification chamber 11 of the gasifier, a non-catalytic partial oxidation reaction is carried out at approximately 1100-1500℃ and 2.0-4.0 MPaG, preferably 1400℃ and 4.0 MPaG, to generate high-temperature crude syngas and liquid slag. The gasification chamber is equipped with water-cooled wall coils filled with saturated boiler water to protect the gasifier shell from overheating.

[0068] The radiant waste boiler 20 is located below the gasification chamber 10 and is connected to the gasification chamber 10. It receives the high-temperature crude syngas and liquid slag generated in the gasification chamber 10. It is equipped with a gas outlet and a circulating gas inlet. The high-temperature crude syngas is output to the convective waste boiler through the gas outlet, and the low-temperature crude syngas input by the circulating gas treatment device 60 is received through the circulating gas inlet. A slag outlet is provided and connected to the slag pool chamber 30 to output slag into the slag pool chamber 30.

[0069] The slag pool chamber 30, located below and connected to the radiant waste pot 20, receives the liquid slag passing through the radiant waste pot 20. The slag pool chamber 30 can be equipped with quench water at a temperature of 160-200℃, causing the liquid slag to rapidly solidify upon contact with the quench water and be periodically discharged as solid slag.

[0070] The convective waste heat boiler 40 is connected to the radiant waste heat boiler 20 and receives the high-temperature crude syngas output from the radiant waste heat boiler 20. It exchanges heat with the high-temperature crude syngas through heat exchange tubes, thus reducing the temperature of the crude syngas. The convective waste heat boiler may include superheated section heat exchange tubes and evaporation section heat exchange tubes. The high-temperature crude syngas first enters the superheated section, where it exchanges heat with saturated steam. The byproduct superheated steam is then sent out, causing the crude syngas temperature to decrease. In the evaporation section, it exchanges heat again with saturated boiler water, further reducing its temperature.

[0071] The fly ash treatment device 70 is connected to the convective waste heat boiler 20 and the quencher and syngas scrubbing device 50. Its crude syngas inlet is connected to the syngas outlet of the convective waste heat boiler 20. The crude syngas and fly ash undergo gas-solid separation and are sent to the quencher and syngas scrubbing device 50. The solid fly ash is cooled and depressurized before being transported to the fly ash storage tank. Gas-solid separation can be achieved through cyclone separators or filters.

[0072] The quencher and syngas scrubbing unit 50 integrates a quencher and a scrubbing mechanism. It receives the crude syngas after gas-solid separation by the fly ash treatment unit 70. Within the quencher, the crude syngas undergoes dechlorination and preliminary dust removal through spray and / or immersion scrubbing. Then, it passes through the scrubbing mechanism for further dust removal to meet downstream requirements. This scrubbing mechanism can use trays and / or immersion scrubbing to further scrub the crude syngas with scrubbing liquid. A portion of the scrubbed crude syngas is sent to the downstream process, while the other portion is fed into the circulating gas treatment unit 60.

[0073] The circulating gas treatment device 60 is connected to the quencher and the syngas scrubbing device 50. It is used to transfer a portion of the low-temperature crude syngas to the circulating gas inlet 22 of the radiant waste boiler 20, forming a mixed gas of low-temperature crude syngas and high-temperature crude syngas in the radiant waste boiler 20, thereby reducing the temperature of the high-temperature crude syngas.

[0074] By employing a full waste heat recovery gasifier, utilizing circulating gas quenching, radiant waste heat boiler, and convective waste heat boiler heat exchange modes, the sensible heat of high-temperature gas is efficiently recovered, maintaining the outlet temperature of the radiant waste heat boiler within the optimal range and reducing fly ash stickiness. Simultaneously, the heat exchange tubes are protected to effectively prevent fly ash from adhering to the walls of the convective waste heat boiler heat exchange tubes. Furthermore, gaseous alkali metals are solidified, preventing their adhesion within the convective waste heat boiler heat exchange tubes. Furthermore, the use of top-mounted burners improves the flow field distribution in the gasification chamber, enhances the combustion reaction, and increases the carbon conversion rate of the gasification reaction. The fly ash generated during the gasification reaction undergoes dry ash removal and wet dechlorination, significantly reducing wastewater discharge.

[0075] Example 3

[0076] Based on the same technical concept as the above-described device embodiments, this embodiment of the invention also provides a method for complete waste boiler heat recovery gasification, as shown in Figure 3. The method includes:

[0077] Step 31: Gasify the mixed biomass and oxidant in the gasification chamber to generate high-temperature crude syngas and liquid slag.

[0078] Step 32: The high-temperature crude syngas is output to the convective syngas through the gas outlet of the radiant waste boiler, and the liquid slag is output to the slag pool chamber through the slag outlet.

[0079] Step 33: Receive the high-temperature crude syngas output from the radiant waste boiler through the convection waste boiler, exchange heat with the high-temperature crude syngas through the heat exchange tube, and output the high-temperature crude syngas after temperature reduction to the quencher.

[0080] Step 34: The high-temperature crude syngas is quenched by the quenching liquid in the quencher, and the quenched low-temperature crude syngas is output through the syngas outlet.

[0081] Step 35: A portion of the low-temperature crude syngas is transferred to the circulating gas inlet of the radiant waste boiler through a circulating gas treatment device, forming a mixed gas of the low-temperature crude syngas and the high-temperature crude syngas in the radiant waste boiler, thereby reducing the temperature of the high-temperature crude syngas.

[0082] The method may also include: injecting a mixture of biomass and oxidant into the gasification chamber through a top burner.

[0083] Prior to step 34, the process may further include: gas-solid separation of the crude syngas output from the convective waste heat boiler 40. The solid fly ash, after cooling and depressurization, is transported to a fly ash storage tank. The separated crude syngas then enters step 34 for quenching treatment.

[0084] To facilitate understanding, an example process is given below with reference to Figure 2:

[0085] Biomass carbon powder from the pulverizing unit is transported to the burner 11 at the top of the gasifier via a thermal inert gas dense phase, and an oxygen-steam mixture is also fed into the burner 11 as a gasifying agent.

[0086] After biomass carbon powder, oxygen and steam are mixed evenly in the gasification chamber 10 of the gasifier, a non-catalytic partial oxidation reaction is carried out at about 1400℃ and 4.0MPaG to generate high-temperature crude syngas and liquid slag. The gasification chamber 10 is equipped with water-cooled wall coils, and the coils are filled with saturated boiler water to protect the gasifier shell from overheating.

[0087] The lower section of the gasification chamber 10 is a radiant waste boiler 20. The vertical heat exchange tubes of the radiant waste boiler 20 contain saturated boiler water. The molten slag flows downward through the radiant waste boiler and is rapidly cooled and solidified after encountering quench water in the slag pool chamber 30, and is periodically discharged. The crude syngas and fly ash, after heat exchange in the radiant waste boiler 20, enter the convective waste boiler 40.

[0088] The convective waste heat boiler is divided into a superheating section and an evaporation section. The heat exchange tubes in the superheating section contain saturated steam, while the heat exchange tubes in the evaporation section contain saturated boiler water. The crude syngas first enters the superheating section and exchanges heat with the saturated steam. The by-product superheated steam is sent out. The temperature of the crude syngas decreases. When it passes through the evaporation section, it exchanges heat with the saturated boiler water again, and the temperature decreases further.

[0089] After the crude syngas and fly ash leave the gasifier's convection waste heat boiler 40, they enter the fly ash treatment device 70, where the fly ash is separated in the gas-solid separator and periodically discharged.

[0090] After gas-solid separation, the crude syngas enters the quencher and syngas washing device 50. After direct contact with process water, washing and cooling, part of it is sent to the downstream section, and the other part is sent to the radiant waste boiler 20 after being pressurized by the circulating gas compression device 60. It is mixed with the high-temperature crude syngas from the first reaction, so that the temperature of the crude syngas at the outlet of the radiant waste boiler 20 is maintained within the optimal range.

[0091] In this embodiment of the invention, circulating gas quenching, radiant waste boiler, and convective waste boiler heat exchange modes are used to efficiently recover the sensible heat of high-temperature gas, maintain the outlet temperature of the radiant waste boiler within the optimal range, reduce fly ash stickiness, and simultaneously protect the heat exchange tubes to effectively prevent fly ash from adhering to the heat exchange tube walls of the convective waste boiler. Furthermore, gaseous alkali metals can be converted into solids to prevent them from adhering inside the convective waste boiler heat exchange tubes. A top-mounted burner is further employed to improve the flow field distribution in the gasification chamber, enhance the combustion reaction, and increase the carbon conversion rate of the gasification reaction. The fly ash generated by the gasification reaction is removed using dry ash removal and wet dechlorination, significantly reducing wastewater discharge.

[0092] 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 them. Those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A complete waste boiler heat recovery gasification system, characterized in that, It includes a gasification chamber, a radiant waste boiler, a slag pool chamber, a convection waste boiler, a quencher, and a circulating gas treatment unit, among which, The gasification chamber is used to gasify the mixed biomass and oxidant to generate high-temperature crude syngas and liquid slag. The radiant waste boiler is connected to the gasification chamber and receives the high-temperature crude syngas and the liquid slag generated in the gasification chamber. It is provided with a gas outlet and a circulating gas inlet. The high-temperature crude syngas is output to the convective waste boiler through the gas outlet, and the low-temperature crude syngas input by the circulating gas treatment device is received through the circulating gas inlet. A slag outlet is provided and connected to the slag pool chamber to output slag into the slag pool chamber. The slag pool chamber is connected to the radiant waste pot and receives the liquid molten slag passing through the radiant waste pot. The convective waste boiler is connected to the radiant waste boiler, receives the high-temperature crude syngas output from the radiant waste boiler, and exchanges heat with the high-temperature crude syngas through heat exchange tubes to reduce the temperature of the high-temperature crude syngas. The quencher is connected to the convection waste boiler and receives the high-temperature crude syngas output from the convection waste boiler; the quencher is equipped with a quenching liquid, and the low-temperature crude syngas quenched by the quenching liquid is output through the syngas outlet. The circulating gas treatment device is connected to the circulating gas inlet of the radiant waste boiler and is used to transfer a portion of the low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler, forming a mixed gas of the low-temperature crude syngas and the high-temperature crude syngas in the radiant waste boiler, thereby reducing the temperature of the high-temperature crude syngas.

2. The total waste boiler heat recovery gasification system according to claim 1, characterized in that, Also includes: The fly ash treatment device is located between the convective waste boiler and the quencher. It removes fly ash from the high-temperature crude syngas by gas-solid separation and then outputs the high-temperature crude syngas to the quencher.

3. The total waste boiler heat recovery gasification system according to claim 1 or 2, characterized in that, The fly ash treatment device includes a cyclone separator or a filter.

4. The total waste boiler heat recovery gasification system according to any one of claims 1-3, characterized in that, The convective waste boiler includes a superheated section heat exchange tube and an evaporation section heat exchange tube. The superheated section heat exchange tube contains saturated steam, and the evaporation section heat exchange tube contains saturated boiler water. The saturated steam in the superheated section heat exchange tube generates superheated steam after heat exchange and is then output.

5. The total waste boiler heat recovery gasification system according to any one of claims 1-4, characterized in that, It also includes a syngas scrubbing device, which is connected to the quencher and the circulating gas treatment device, and is used to scrub the low-temperature crude syngas with scrubbing liquid in multi-layer trays; The circulating gas treatment device is connected to the syngas scrubbing device, receives the low-temperature crude syngas after scrubbing by the syngas scrubbing device, and transmits a portion of the scrubbed low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler.

6. The total waste boiler heat recovery gasification system according to any one of claims 1-5, characterized in that, The circulating gas treatment device includes a compression device for pressurizing the low-temperature crude syngas output to the circulating gas inlet of the radiant waste boiler, and outputting the pressurized low-temperature crude syngas to the circulating gas inlet of the radiant waste boiler.

7. The total waste boiler heat recovery gasification system according to claim 6, characterized in that, The circulating gas treatment device is also used to regulate the temperature of the low-temperature crude syngas output to the circulating gas inlet of the radiant waste boiler.

8. The total waste boiler heat recovery gasification system according to any one of claims 1-7, characterized in that, The quencher is provided with a slag and water outlet at the bottom for discharging wastewater that meets the first condition and recycling wastewater that meets the second condition back into the quencher.

9. The total waste boiler heat recovery gasification system according to any one of claims 1-8, characterized in that, The gasification chamber includes a top burner for injecting the mixture of biomass and oxidant into the gasification chamber.

10. A method for heat recovery using the total waste boiler heat recovery gasification system according to any one of claims 1-9, characterized in that, include: In the gasification chamber, the mixed biomass and oxidant are gasified to generate high-temperature crude syngas and liquid slag. The high-temperature crude syngas is output from the gas outlet of the radiant waste boiler to the convective waste boiler, and the liquid slag is output from the slag outlet to the slag pool chamber. The high-temperature crude syngas output from the radiant waste boiler is received by the convection waste boiler, and heat is exchanged with the high-temperature crude syngas through heat exchange tubes. The high-temperature crude syngas with reduced temperature is then output to the quencher. The high-temperature crude syngas is quenched by the quenching liquid in the quencher, and the quenched low-temperature crude syngas is output through the syngas outlet. A portion of the low-temperature crude syngas is transferred to the circulating gas inlet of the radiant waste boiler via a circulating gas treatment device, forming a mixed gas of the low-temperature crude syngas and the high-temperature crude syngas within the radiant waste boiler, thereby reducing the temperature of the high-temperature crude syngas.

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