A gasification fly ash treatment system and method for heat energy recovery

Abstract

The present invention relates to the technical field of coal gasification for treating gasification fly ash, and provides a system and method for treating gasification fly ash with heat energy recycling. By setting a first fly ash coating chamber and a second fly ash coating chamber, fly ash particles with a fine particle size are coated on particle coal with a larger particle size to form fly ash-coated particle coal, which is then sent into the lower dense phase area with a high airflow velocity and high temperature, thereby improving the full utilization of chemical heat and physical heat energy of fly ash particles with second and third particle sizes. Fly ash-coated particle coal with a moderate particle size improves the fluidization activity of the particle material in the lower part of the circulating fluidized bed gasifier. By setting a molten salt heat exchanger for efficiently cooling high-temperature coal gas in the high-temperature section and a steam heat exchanger for cooling coal gas at a lower temperature, the high-temperature heat energy of the molten salt heat exchanger is used to preheat the recycled fly ash particles with a third particle size, and the steam heat exchanger converts the heat energy into the heat energy of an auxiliary gasifying agent for utilization, thereby achieving full utilization of the heat energy of the high-temperature flue gas before the dust collector and reducing costs.

Description

Technical Field

[0001] The present application relates to the technical field of coal gasification for gasification fly ash treatment, and in particular to a gasification fly ash treatment system and method for heat energy recovery. Background Art

[0002] Coal gasification refers to the process of converting solid coal into syngas (or synthesis gas) containing combustible gases such as CO, hydrogen, methane and non-combustible gases such as carbon dioxide and nitrogen by causing a series of chemical reactions between organic matter in coal and gasifying agents (such as steam / air and / or oxygen) at a certain temperature and pressure in a specific device. During coal gasification, gasifier, gasifying agent and heat supply are indispensable.

[0003] Circulating fluidized bed coal gasification technology is a relatively advanced and low-cost coal gasification technology. Through a high-circulation material circulation loop, the fluidization speed is greater than that of a traditional fluidized bed gasifier. It has the advantages of strong coal applicability, sufficient gas-solid mixing, and high gasification reaction rate. However, when producing qualified coal gas or industrial gas and other products, gasification fly ash with a carbon content of 30% to 50% will still be produced, which cannot be effectively treated, affecting the improvement of the carbon conversion rate of the gasifier. When producing gasification fly ash, in order to obtain qualified clean coal gas, the high-temperature coal gas containing gasification fly ash produced by the gasifier needs to be processed through a gas-solid separation device, a coal gas cooling device, a dust collector, etc. to remove the gasification fly ash and cool the high-temperature coal gas. In the above process, the carbon and high-temperature heat in the fly ash are not fully utilized.

[0004] By returning fly ash to the gasifier, the utilization rate of fly ash can be improved. In the prior art, the gasified fly ash is directly sent back to the furnace. Since the reaction activity of the gasified fly ash is not high, it is usually sent to the lower part of the gasifier to increase its residence time in the furnace and react in the high temperature area to improve the reaction efficiency. However, due to the small particle size of the fly ash and the large airflow in the lower part of the gasifier, the residence time in the furnace cannot be guaranteed, and the reaction efficiency cannot be effectively improved. Therefore, the fly ash with a very small particle size still cannot be effectively utilized in the gasifier, and the resource utilization of the fluidized bed gasification fly ash cannot be realized. There is an existing technology that realizes the resource processing of gasification fly ash by setting up a fly ash melting furnace with fly ash with very small particle size. The high-temperature flue gas coming out of the fly ash melting furnace can realize the preheating of the gasification agent and other methods to realize the utilization of gasification fly ash and the heat of the high-temperature flue gas. The fly ash melting furnace requires high-temperature treatment at 1500℃-1800℃, and the circulating fluidized bed coal gasification technology is treated under low-temperature conditions below 1100℃. The fly ash melting furnace is treated at high temperature, and the equipment loss under high temperature is much greater than the equipment loss of the circulating fluidized bed coal gasification technology equipment under low-temperature conditions. Because the high-temperature equipment is overhauled and maintained more frequently, the two production processes cannot be effectively matched, which restricts the improvement of production efficiency. In addition, the high-temperature flue gas and high-temperature slag in the fly ash melting furnace take away a large amount of heat (this heat comes from the reaction of the carbon component of the fly ash) and cannot be used, which affects the utilization of carbon and heat energy of the gasification fly ash.

[0005] How to realize the resource treatment of gasification fly ash in the above-mentioned treatment process, how to fully utilize the carbon in the gasification fly ash with a carbon content of 30% to 50% and reduce the carbon content in the gasification fly ash, how to effectively utilize the chemical heat of the gasification fly ash, and how to fully utilize the thermal energy of the high-temperature coal gas containing gasification fly ash generated by the gasifier are still the difficulties faced by the development of circulating fluidized bed coal gasification technology. Summary of the invention

[0006] In order to overcome the shortcomings of the prior art, the present application provides a gasification fly ash treatment system and method for heat recovery, which realizes the resource processing of gasification fly ash in a circulating fluidized bed under low temperature conditions, fully utilizes the carbon in the gasification fly ash, realizes the full chemical heat of the gasification fly ash, reduces the carbon content in the gasification fly ash, and at the same time, fully utilizes the thermal energy of the high-temperature coal gas containing gasification fly ash generated by the gasifier.

[0007] The embodiment of the present application is implemented as follows:

[0008] In a first aspect, the present application example provides a gasification fly ash processing system for heat energy recovery, comprising:

[0009] A circulating fluidized bed gasifier, used for gasifying pulverized coal and a gasifying agent in the circulating fluidized bed gasifier to obtain high-temperature coal gas, wherein the circulating fluidized bed gasifier comprises an upper dilute phase zone, a middle transition zone, and a lower dense phase zone, wherein pulverized coal enters the lower dense phase zone from a coal bunker through a conveying pipeline through a pulverized coal inlet, and the gasifying agent comprises a main gasifying agent, and the main gasifying agent enters the lower dense phase zone through a main gasifying agent inlet at the bottom of the circulating fluidized bed gasifier;

[0010] A first gas-solid separator, wherein the high-temperature coal gas from the top of the circulating fluidized bed gasifier enters the first gas-solid separator through a pipeline, and the coal gas containing fly ash at a first temperature and fly ash particles of a first temperature and a first particle size are separated, and the fly ash particles of the first particle size are returned to the middle transition zone through a return port;

[0011] A second gas-solid separator, wherein the coal gas at the first temperature containing fly ash enters the second gas-solid separator through a pipeline, and the coal gas at the first temperature and fly ash particles of the second particle size at the first temperature are separated, and the fly ash particles of the second particle size are transported to the first fly ash coating cavity through a pipeline;

[0012] A molten salt heat exchanger is used to separate the coal gas at the first temperature, cool it to the second temperature through the molten salt heat exchanger, further cool it to the third temperature through the steam heat exchanger, and then enter the dust collector to obtain clean coal gas. Fly ash particles with a third particle size and a third temperature are collected at the bottom of the dust collector; the steam obtained by heat exchange in the steam heat exchanger enters the lower dense phase zone through the first auxiliary gasifying agent inlet located above the main gasifying agent inlet;

[0013] The heat transfer medium molten salt of the molten salt heat exchanger preheats the fly ash particles of the third particle size through the third heat exchanger, and the fly ash particles of the third particle size enter the second fly ash coating cavity;

[0014] The coking coal is fed into the first fly ash coating cavity and coated and mixed with the second particle size fly ash particles before entering the second fly ash coating cavity, and is further coated and mixed with the third particle size fly ash particles before entering the lower dense phase zone through the particle coal inlet; the particle size of the coking coal is 4mm-10mm.

[0015] Optionally, a fly ash activation chamber is set up, and the coking coal is fed into the first fly ash coating chamber and is coated and mixed with the fly ash particles of the second particle size before entering the second fly ash coating chamber, and is further coated and mixed with the fly ash particles of the third particle size before entering the fly ash activation chamber, and some of the fly ash particles of the first particle size are drawn out into the fly ash activation chamber, and the coking coal, fly ash particles of the second particle size, fly ash particles of the third particle size and fly ash particles of the first particle size are further coated and mixed before entering the lower dense phase zone from the particle coal inlet.

[0016] Optionally, the steam obtained by heat exchange in the steam heat exchanger enters the middle transition zone through a second auxiliary gasifying agent inlet located above the return port, and / or the steam obtained by heat exchange in the steam heat exchanger enters the lower dense phase zone through a third auxiliary gasifying agent inlet located above the pulverized coal inlet.

[0017] Optionally, the first auxiliary gasification agent inlet, the third auxiliary gasification agent inlet and the particle coal inlet are arranged to be inclined upward, and the second auxiliary gasification agent inlet is arranged to be inclined downward, and the central axes of the first auxiliary gasification agent inlet, the third auxiliary gasification agent inlet, the particle coal inlet and the second auxiliary gasification agent inlet are respectively arranged at an angle of 10°-25° with the horizontal plane.

[0018] Optionally, the first auxiliary gasification agent inlet and the particle coal inlet are at the same height in the horizontal direction, and along the circumferential direction of the shell of the lower dense phase zone, the particle coal inlet is located between two adjacent first auxiliary gasification agent inlets, and the angle α between the central axis of the first auxiliary gasification agent inlet and the particle coal inlet and the tangent of the shell circumference of the lower dense phase zone is 15°-35°.

[0019] Optionally, at least three second auxiliary gasifying agent inlets are arranged along the circumferential direction of the shell of the middle transition zone, and an angle β between a central axis of the second auxiliary gasifying agent inlet and a tangent line of the shell circumference of the middle transition zone is 50°-80°.

[0020] Optionally, the inner wall of the second fly ash coating cavity is provided with a baffle; the inner wall of the fly ash activation cavity is provided with spiral protrusions or grooves.

[0021] In a second aspect, the present application provides a method for treating gasified fly ash with heat recovery, using any of the aforementioned gasified fly ash treatment systems with heat recovery.

[0022] Step 1: coal powder and gasifying agent are gasified in the circulating fluidized bed gasifier to obtain high-temperature coal gas, wherein the gasification temperature is 800° C.-1100° C.;

[0023] Step 2: High-temperature coal gas is drawn out from the top of the circulating fluidized bed gasifier and enters the first gas-solid separator through a pipeline to separate the coal gas containing fly ash at a first temperature and fly ash particles of a first temperature and a first particle size, and the fly ash particles of the first particle size are returned to the middle transition zone through a return port; the first temperature is 700° C.-890° C.;

[0024] Step 3: the coal gas at the first temperature containing fly ash enters the second gas-solid separator through the pipeline, and the coal gas at the first temperature and the fly ash particles of the second particle size at the first temperature are separated, and the fly ash particles of the second particle size are transported to the first fly ash coating cavity through the pipeline;

[0025] Step 4: the coal gas at the first temperature is separated and cooled to the second temperature through a molten salt heat exchanger, and further cooled to the third temperature through a steam heat exchanger, and then enters a dust collector to obtain clean coal gas, and fly ash particles with a third particle size and a third temperature are collected at the bottom of the dust collector; the second temperature is 400°C-500°C, and the third temperature is 150°C-250°C;

[0026] The steam obtained by heat exchange in the steam heat exchanger enters the lower dense phase zone through a first auxiliary gasifying agent inlet located above the main gasifying agent inlet;

[0027] The heat transfer medium molten salt of the molten salt heat exchanger preheats the fly ash particles of the third particle size to a fourth temperature through a third heat exchanger, and the fly ash particles of the third particle size enter the second fly ash coating cavity; the fourth temperature is 300° C.-450° C.;

[0028] The coking coal is fed into the first fly ash coating cavity and coated and mixed with the second particle size fly ash particles, and then enters the second fly ash coating cavity, and then further coated and mixed with the third particle size fly ash particles, and then enters the lower dense phase zone through the particle coal inlet.

[0029] Optionally, in step 4, the coking coal is fed into the first fly ash coating cavity and is coated and mixed with the fly ash particles of the second particle size, and then enters the second fly ash coating cavity, and is further coated and mixed with the fly ash particles of the third particle size, and then enters the fly ash activation cavity, and a portion of the fly ash particles of the first particle size are drawn out into the fly ash activation cavity, and the coking coal, the fly ash particles of the second particle size, the fly ash particles of the third particle size and the fly ash particles of the first particle size are further coated and mixed, and then enter the lower dense phase zone from the particle coal inlet.

[0030] Optionally, the average particle size of the fly ash particles of the first particle size is greater than the average particle size of the fly ash particles of the second particle size, and the average particle size of the fly ash particles of the second particle size is greater than the average particle size of the fly ash particles of the third particle size; the particle size of the coking coal (16) is 5mm-8mm.

[0031] Beneficial effects include:

[0032] The gasification fly ash treatment system and method for heat energy recovery provided by the present invention, the first gas-solid separator, the second gas-solid separator and the dust collector, remove the fly ash of the high-temperature flue gas in three stages, thereby achieving efficient production of clean coal gas with low fly ash content.

[0033] The high-temperature first-size fly ash particles separated from the high-temperature coal gas led out of the circulating fluidized bed gasifier are returned to the middle transition zone of the gas flow rate between the lower dense phase zone and the upper dilute phase zone, so that the first-size fly ash particles with high temperature and good reactivity increase their residence time in the gasifier and improve the reaction efficiency. While fully utilizing the chemical energy of the carbon-containing first-size fly ash particles, the high reaction heat and the high temperature of the first-size fly ash particles can increase the thermal energy of the upper dilute phase zone, improve the reaction efficiency of the upper dilute phase zone, and fully reuse the thermal energy of the first-size fly ash particles.

[0034] By setting up a first fly ash coating chamber and a second fly ash coating chamber, larger particle coal (coking coal) with a suitable volatile content is coated and mixed with the high-temperature second particle size fly ash particles separated by the second gas-solid separator. The high temperature of the second particle size fly ash particles is first used to preheat the coking coal to melt some of the colloid components on the surface of the particle coking coal, thereby increasing the viscosity of the coking coal particles. The second particle size fly ash particles adhere to the larger particle size coal particles to achieve partial coating of the fly ash on the surface of the particle coal, providing preheated modified high-viscosity coking coal particles with strong viscosity, and further introducing the second fly ash coating chamber into which the third particle size fly ash particles with a lower temperature are introduced, thereby achieving coating of the low-temperature third particle size fly ash particles on the surface of the coal particles with increased viscosity, thereby The fly ash particles of different particle sizes are mixed and coated on the larger particle size coal in steps to form fly ash coated particle coal, and then sent into the lower dense phase area with high air velocity and high temperature, which can avoid the direct mixing of fly ash particles of different temperatures and raw coal, the poor bonding effect of fly ash particles of small particle size with raw coal, the local concentrated combustion or reaction effect of fly ash particles of small particle size, the short residence time of fly ash particles of small particle size in the lower dense phase area with high air velocity, and the low reaction efficiency. The second particle size fly ash particles are recycled and utilized, especially the third particle size fly ash particles with low temperature and the smallest particle size are recycled and utilized efficiently, and the high temperature heat energy of the second particle size fly ash particles is recycled and utilized, which improves the full utilization of the chemical heat and physical heat energy of the second and third particle size fly ash particles. The fly ash coated particle coal with moderate particle size also improves the problem of excessive melting or even sintering of coal ash caused by the excessively high combustion temperature of the lower coal in the circulating fluidized bed gasifier, and improves the fluidization of the particle material in the lower part of the circulating fluidized bed gasifier.

[0035] By setting a molten salt heat exchanger for efficiently cooling the high-temperature coal gas in the high-temperature section and a steam heat exchanger for cooling the coal gas at a lower temperature, the high-temperature flue gas before entering the dust collector can be quickly and efficiently cooled. At the same time, the high-temperature heat energy of the molten salt heat exchanger is used to preheat the third-size fly ash particles for reuse, and the steam heat exchanger converts the heat energy into the heat energy of the auxiliary gasification agent for utilization, and reduces the investment in dedicated auxiliary gasification agent supply equipment, thereby achieving full utilization of the high-temperature flue gas heat energy before the dust collector and reducing costs.

[0036] Furthermore, a fly ash activation chamber is provided, by partially drawing out fly ash particles of the first particle size with high high-temperature reaction activity and coating and mixing them with fly ash-coated coal particles drawn out of the second fly ash coating chamber in the fly ash activation chamber, and high-temperature heating is used to make the fly ash particles of the first particle size with high reaction activity coat the fly ash-coated coal particles, thereby increasing their temperature and reaction activity, which is beneficial to further improving the utilization of the fly ash-coated coal particles.

[0037] In summary, the gasification fly ash treatment system and method with heat energy recovery provided by the present invention realize the true resource processing of circulating fluidized bed gasification fly ash under low temperature conditions, the carbon in the gasification fly ash is fully and efficiently utilized, the chemical heat of the gasification fly ash is fully utilized, the carbon content in the gasification fly ash is reduced, and at the same time, the heat energy of the high-temperature coal gas containing gasification fly ash generated by the gasifier is fully recovered and utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 A schematic structural diagram of a gasification fly ash treatment system for heat recovery provided in an embodiment of the present application.

[0040] Figure 2 A schematic structural diagram of a gasification fly ash treatment system for heat recovery provided in another embodiment of the present application.

[0041] Figure 3 It is a schematic cross-sectional diagram of the lower dense phase region section A.

[0042] Figure 4 It is a schematic cross-sectional diagram of section B in the middle transition zone.

[0043] Icons: 1-circulating fluidized bed gasifier; 2-upper dilute phase zone; 3-lower dense phase zone; 4-coal powder inlet; 5-main gasifying agent inlet; 6-middle transition zone; 7-first gas-solid separator; 8-return port; 9-second gas-solid separator; 10-molten salt heat exchanger; 11-steam heat exchanger; 12-dust collector; 13-first auxiliary gasifying agent inlet; 14-third heat exchanger; 15-second fly ash coating chamber; 16-coking coal; 17-particulate coal inlet; 18-clean coal gas; 19-fly ash activation chamber; 20-second auxiliary gasifying agent inlet; 21-third auxiliary gasifying agent inlet; 22-first fly ash coating chamber; 23-baffle; 24-protrusion or groove. DETAILED DESCRIPTION

[0044] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Those skilled in the art will understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as those generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless specifically defined as here.

[0046] Those skilled in the art will appreciate that, unless expressly stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items. The following pipeline material transport process implementation, although not explicitly stated, may include the basic conditions required to realize the material transport, such as adding conveying gas according to actual needs, using suitable material adding equipment, etc. to realize pipeline material transport; gasification agent supply, which may supply the necessary external gas source required to maintain production conditions according to actual needs.

[0047] In order to solve the problems that gasification fly ash cannot be fully recycled, the carbon in gasification fly ash with a carbon content of 30% to 50% cannot be fully utilized and the carbon content in gasification fly ash cannot be reduced, and the thermal energy of the high-temperature coal gas containing gasification fly ash generated by the gasification furnace cannot be fully utilized, the embodiments of the present invention provide a gasification fly ash treatment system and method for heat energy recovery.

[0048] The features and performance of the present application are further described in detail below in conjunction with the embodiments:

[0049] Example 1

[0050] like Figure 1-4 As shown, an embodiment of the present invention provides a gasification fly ash treatment system and method for heat energy recovery, comprising:

[0051] A circulating fluidized bed gasifier (1) is used for gasifying pulverized coal and a gasifying agent in the circulating fluidized bed gasifier (1) to obtain high-temperature coal gas, wherein the gasification temperature is 800°C-1100°C (optionally 800°C, 830°C, 850°C, 870°C, 890°C, 910°C, 930°C, 940°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1050°C, 1080°C, 1100°C, etc.).

[0052] The circulating fluidized bed gasifier (1) comprises an upper dilute phase zone (2), a middle transition zone (6), and a lower dense phase zone (3); the main gasifying agent enters the lower dense phase zone (3) from a main gasifying agent inlet (5) at the bottom of the circulating fluidized bed gasifier (1); the diameter of the upper dilute phase zone (2) is greater than the diameter of the lower dense phase zone (3), and the diameter of the middle transition zone (6) gradually increases from bottom to top.

[0053] The pulverized coal (after drying and crushing to a particle size of less than 10 mm, the source of the pulverized coal is not limited, and it can be one or more of lean coal, lean coal, coking coal, fat coal, gas coal, and long flame coal) enters the lower dense phase zone (3) from the coal bunker through a conveying pipeline through a pulverized coal inlet (4), and the gasifying agent includes a main gasifying agent, which can be the following components or a combination of components: air, air + steam, oxygen-enriched air, oxygen-enriched air + steam, pure oxygen, pure oxygen + steam, etc. The air flow velocity in the lower dense phase zone (3) is relatively fast, and the pulverized coal and the gasifying agent react rapidly at the gasification temperature. Under the action of the air flow introduced at the bottom, an ascending air flow is formed, and the air flow enters the upper dilute phase zone (2) after passing through the middle transition zone (6). The air flow velocity in the upper dilute phase zone (2) decreases, and a large amount of coal particles and unreacted carbon undergo gasification reaction in the middle and upper part of the furnace, absorbing a large amount of heat to obtain a high gasification efficiency. The temperature in this area is relatively low, and particles of larger size return to the lower part of the gasifier by gravity. The diameter of the upper dilute phase zone (2) is larger than the diameter of the lower dense phase zone (3). The diameter of the middle transition zone (6) gradually increases from bottom to top. As the cross-sectional area of ​​the middle transition zone (6) gradually increases, the air flow velocity gradually decreases, and the air flow velocity is between the upper dilute phase zone (2) and the lower dense phase zone (3). At a moderate air flow velocity, the granular carbon can be provided with a prolonged residence time in the middle and upper part, thereby improving the reaction efficiency.

[0054] The first gas-solid separator (7) may be a cyclone separator or the like. The high-temperature coal gas drawn out from the top of the circulating fluidized bed gasifier (1) enters the first gas-solid separator (7) through a pipeline, and separates the coal gas containing fly ash at a first temperature and fly ash particles of a first temperature and a first particle size. The fly ash particles of the first particle size return to the middle transition zone (6) from the return port (8); the fly ash particles of the first particle size return to the middle transition zone (6) from the return port (8); the first temperature is 700°C-890°C (optionally 700°C, 720°C, 740°C, 770°C, 780°C, 800°C, 810°C, 830°C, 850°C, 870°C, 880°C, 890°C, etc.). It can be understood that the temperature of the fly ash particles of the first particle size is similar to the temperature of the middle and upper part of the circulating fluidized bed gasifier (1), so the temperature range thereof is roughly the same, but the specific temperature may be the same as or different from the temperature of the middle and upper part of the circulating fluidized bed gasifier (1).

[0055] The high-temperature first-size fly ash particles separated from the high-temperature coal gas drawn out from the circulating fluidized bed gasifier (1) are returned to the middle transition zone (6) where the gas flow rate is between the lower dense phase zone (3) and the upper dilute phase zone (2). The first-size fly ash particles are large-size particles just drawn out from the gasifier. Although their reaction activity is lower than that of the carbon particles just entering the gasifier, they still have the characteristics of well-developed pores, large specific surface area, high temperature, strong reaction activity and other characteristics that are beneficial to the gasification reaction. The first-size fly ash particles with high temperature and good reactivity are returned to the middle transition zone (6) to increase their residence time in the gasifier and improve the reaction efficiency. While fully utilizing the chemical energy of the carbon contained in the first-size fly ash particles, the high reaction heat and the high temperature of the first-size fly ash particles can increase the thermal energy of the upper dilute phase zone (2), thereby improving the reaction efficiency of the upper dilute phase zone (2) where the regional temperature is relatively low and needs to absorb a large amount of heat, so that the thermal energy of the first-size fly ash particles can be fully recycled. It is known that, if necessary, gasifying agent can be added to increase the chemical energy utilization of the carbon content of the first particle size fly ash particles.

[0056] The second gas-solid separator (9) may be a cyclone separator or the like. The coal gas at the first temperature containing fly ash enters the second gas-solid separator (9) through a pipeline, and the coal gas at the first temperature and fly ash particles of the second particle size at the first temperature are separated. The fly ash particles of the second particle size are transported to the first fly ash coating chamber (22) through a pipeline, thereby obtaining high-temperature fly ash particles of the second particle size. The colloid material of the granular coal is heated by its heat energy, so that the granular coal can become a matrix for adhering fine fly ash. The coal gas at the first temperature containing fly ash and the separated coal gas at the first temperature and fly ash particles of the second particle size at the first temperature have a temperature similar to each other, and thus have approximately the same temperature range, but this does not mean that their temperatures are necessarily the same. The temperatures of the three may be the same or different within the temperature range of the first temperature.

[0057] The coal gas at the first temperature is separated by a molten salt heat exchanger (10), and is cooled to a second temperature of 400°C-500°C (optionally 400°C, 410°C, 440°C, 470°C, 480°C, 500°C, etc.), and is further cooled to a third temperature of 150°C-250°C (optionally 150°C, 170°C, 190°C, 200°C, etc.) by a steam heat exchanger (11). The coal gas enters a dust collector (12) to obtain a clean coal gas (18). The third temperature is 150°C-250°C (optionally 150°C, 170°C, 190°C, 200°C, etc.). 220℃, 240℃, 250℃, etc.); the dust collector (12) collects fly ash particles of a third particle size with a third temperature at the bottom; the molten salt heat exchanger (10) can be a heat exchanger whose heat transfer medium is molten salt. Molten salt has the advantages of "four highs and three lows" such as high operating temperature, good thermal stability, high specific heat capacity, high convective heat transfer coefficient, low viscosity, low saturated vapor pressure, and low price. For example, it can be carbonate, fluoride salt, nitrate, chloride salt, etc. The specific structure and molten salt type are not limited, and existing heat exchange products can be selected. The steam heat exchanger (11) can be a heat exchanger that can exchange heat to produce steam, and the specific structure is not limited. The dust collector (12) can be a dust collector for removing fine fly ash, such as a bag dust collector.

[0058] The heat transfer medium molten salt of the molten salt heat exchanger (10) preheats the fly ash particles of the third particle size to a fourth temperature through the third heat exchanger (14), and the fly ash particles of the third particle size enter the second fly ash coating cavity (15); the fourth temperature is 300°C-450°C (optionally 300°C, 320°C, 360°C, 370°C, 380°C, 400°C, 410°C, 430°C, 450°C, etc.). The specific type of the third heat exchanger (14) is not limited, and can be any existing common heat exchanger. The heat transfer medium molten salt of the molten salt heat exchanger (10) is pumped through a pipeline into the third heat exchanger (14) to preheat the fly ash particles of the third particle size. It can be understood that the heat transfer medium molten salt returns to the molten salt heat exchanger (10) after heat exchange. It can also be used for preheating gasification agent, etc. by exchanging heat with other heat exchangers before or after entering the third heat exchanger (14) according to needs and the temperature of the heat transfer medium, so as to improve the utilization rate of its thermal energy.

[0059] Coking coal (16) is fed into the first fly ash coating chamber (22) and is coated and mixed with the second particle size fly ash particles before entering the second fly ash coating chamber (15). It is further coated and mixed with the third particle size fly ash particles before entering the lower dense phase zone (3) through the particle coal inlet (17). The particle size of the coking coal (16) is 4mm-10mm (optionally 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, etc.). If the particle size is larger than the above range, the coking coal particles are too large, which is not conducive to entering the lower dense phase zone (3) for fluidization and reaction. If the particle size is smaller than the above range, the coking coal particles are too small to achieve particle coal coating. The serious small particle size causes the particle coal to adhere to the fine particle fly ash and agglomerate, and cannot be returned for use. The preferred particle size is 5mm-8mm. Within the above range, it is more conducive to the coating of particle coal and fly ash, and has high reactivity and good ignition effect.

[0060] Since the average particle size of the first particle size fly ash particles is larger than the average particle size of the second particle size fly ash particles, and the average particle size of the second particle size fly ash particles is larger than the average particle size of the third particle size fly ash particles, the second and third particle size fly ash particles are fine in size and almost free of volatile matter. Although they contain carbon (the carbon content is generally 30-50%), the actual residence time in the furnace cannot be guaranteed when they are directly returned to the gasifier, so that they cannot be effectively utilized. By setting a first fly ash coating chamber (22) and a second fly ash coating chamber (15), larger particle size coal (coking coal) with a suitable volatile matter content is coated and mixed with the high-temperature second particle size fly ash particles separated by the second gas-solid separator (9), and the high temperature of the second particle size fly ash particles is firstly used to preheat the coking coal particles, so that the colloidal components on the surface of the coking coal particles are partially melted, thereby increasing the viscosity of the coking coal particles, and the second particle size fly ash particles adhere to the larger particle size coal particles, so that the surface of the coal particles is partially The coated fly ash provides highly viscous preheated modified coking coal particles, and is further introduced into a second fly ash coating chamber (15). In the second fly ash coating chamber (15), fly ash particles of a third particle size with a lower temperature are introduced to coat the third particle size fly ash particles on the surface of the coal particles with increased viscosity. Thus, fly ash particles of different temperatures and particle sizes are coated on the larger particle size coal by step-by-step mixing to form fly ash coated particle coal, which is then sent into the lower dense phase zone with a high air velocity and high temperature, thereby avoiding It is avoided that fly ash particles of different temperatures and fine particle sizes are directly mixed with raw coal, the adhesion effect of fly ash particles of fine particle sizes with raw coal is poor, and the fly ash particles of fine particle sizes are locally concentrated and burned or reacted poorly (if fly ash particles of different temperatures and fine particle sizes are directly mixed with raw coal, although high-temperature fly ash can also heat the raw coal, the low-temperature fly ash particles obviously reduce its heating effect, resulting in poor adhesion between fly ash and particle coal, and even local concentration of fly ash particles of fine particle sizes. The combustion and reactivity of fly ash particles of fine particle sizes are lower than those of coal particles, which will affect the return and utilization of fly ash particles of fine particle sizes). It can avoid the problems of short residence time of fly ash particles of fine particle sizes in the lower dense phase with high air flow velocity and low reaction efficiency, realize the return and utilization of fly ash particles of the second particle size, especially realize the return and efficient utilization of fly ash particles of the third particle size with low temperature and the smallest particle size, the high-temperature thermal energy of fly ash particles of the second particle size is returned and utilized, and the full utilization of chemical heat and physical heat energy of fly ash particles of the second and third particle sizes is improved. The second and third particle size fly ash particles are fine in size and have a lower carbon content than coal powder. They are not easy to burn and react. In order to avoid introducing them into the gasifier to affect the heat generation and gasification reactions in the lower dense phase (3), the fly ash-coated particle coal with a suitable particle size and high carbon content is used as the matrix, so that the fly ash-coated particle coal is still easy to ignite and has high reactivity. The fly ash-coated particle coal with a moderate particle size also improves the problem of excessive melting or even sintering of the coal ash caused by the high combustion temperature of the coal in the lower part of the circulating fluidized bed gasifier, and improves the fluidization activity of the particle material in the lower part of the circulating fluidized bed gasifier.

[0061] The steam obtained by heat exchange in the steam heat exchanger (11) enters the lower dense phase zone (3) through a first auxiliary gasifying agent inlet (13) located above the main gasifying agent inlet (5). The first auxiliary gasifying agent inlet (13) is at the same height as the particle coal inlet (17) in the horizontal direction. The steam is added as the first auxiliary gasifying agent, which is beneficial to the reaction of the fly ash-coated particle coal from the particle coal inlet (17) and increases the residence time of the fly ash-coated particle coal in the furnace. The steam obtained by heat exchange in the steam heat exchanger (11) enters the middle transition zone (6) through a second auxiliary gasifying agent inlet (20) located above the return port (8). By introducing the second auxiliary gasifying agent in the middle transition zone (6), the turbulent state of the gas field is increased, the particle residence time is prolonged, and the reaction in this area is promoted, which is beneficial to the full reaction of the recovered high-temperature second particle size fly ash particles.

[0062] The steam obtained by heat exchange with the steam heat exchanger (11) enters the lower dense phase zone (3) through the third auxiliary gasifying agent inlet (21) located above the pulverized coal inlet (4), and the gasifying agent is supplemented above the pulverized coal, which is beneficial to improving the reaction and the gasification efficiency.

[0063] By providing a molten salt heat exchanger (10) for efficiently cooling the high-temperature coal gas in the high-temperature section and a steam heat exchanger (11) for cooling the coal gas at a lower temperature, the high-temperature flue gas before entering the dust collector (12) can be quickly and efficiently cooled. At the same time, the high-temperature heat energy of the molten salt heat exchanger (10) is used to preheat the third-size fly ash particles for reuse, and the steam heat exchanger (11) converts the heat energy into the heat energy of the auxiliary gasification agent for utilization, and reduces the investment in the dedicated auxiliary gasification agent supply equipment, thereby achieving full utilization of the high-temperature flue gas heat energy before the 12-dust collector and reducing costs. By adding auxiliary gasification agents to different areas of the lower dense phase zone (3) and the middle transition zone (6), the auxiliary gasification agents are used in combination according to the different return particles and raw coal particles in each area, thereby improving the reaction and improving the gasification efficiency. It can be understood that the auxiliary gasification agent is mainly steam obtained by heat exchange in the steam heat exchanger (11). If necessary, an external gasification agent can also be added according to the needs of the reaction and the heat demand.

[0064] Optionally, the first auxiliary gasifying agent inlet (13), the third auxiliary gasifying agent inlet (21) and the particle coal inlet (17) are arranged to be inclined upward, which is conducive to the auxiliary gasifying agent and the particle coal coated with fly ash entering the rising airflow formed by the main gasifying agent entering from the bottom, reducing the impact on the rising airflow, and improving the rising power of the airflow at the bottom of the furnace body, while promoting the reaction between the raw coal and the particle coal coated with fly ash and the gasifying agent. The second auxiliary gasifying agent inlet (20) is arranged to be inclined downward, which is conducive to extending the residence time of the fly ash particles of the first particle size by adding the auxiliary gasifying agent, thereby improving the reaction rate. Thereby further improving the reaction and improving the gasification efficiency. The angle between the central axis of the above-mentioned inlet and the horizontal plane is 10°-25° (optionally: 10°, 12°, 13°, 15°, 17°, 19°, 21°, 23°, 25°, etc.). If it is lower than the above range, the effects of promoting the upward flow of air and prolonging the residence time of particles are reduced. If it is higher than the range, the granular coal with added gasifying agent and coated fly ash is too close to the outer wall of the gasifier, which is not conducive to the reaction.

[0065] Optionally, along the circumferential direction of the shell of the lower dense phase zone (3), the particle coal inlet (17) is located between two adjacent first auxiliary gasification agent inlets (13), Figure 3 The particle coal inlet (17) and the two first auxiliary gasifying agent inlets (13) are evenly spaced, and the gasifying agent entering through the two adjacent first auxiliary gasifying agent inlets (13) promotes the fly ash-coated carbon particles entering through the particle coal inlet (17) to disperse upward into the ascending gasification airflow, and increases the fly ash-coated carbon particles entering the reaction. The angle α between the central axis of the first auxiliary gasifying agent inlet (13) and the particle coal inlet (17) and the tangent of the shell circumference of the lower dense phase zone (3) is 15°-35° (optionally: 15°, 17°, 23°, 26°, 28°, 30°, 32°, 35°, etc.), so that the airflow entering through the inlet is closer to the outer wall of the gasifier, forming an ascending circulation in the peripheral circumferential direction close to the outer wall of the gasifier, so that the fly ash-coated carbon particles circulate upward and enter the upper part of the gasifier, thereby increasing the residence time of the fly ash-coated carbon particles and promoting the reaction. When the angle is smaller than this range, the airflow is too close to the outer wall of the gasifier, which is not conducive to gas flow and reaction. When the angle is larger than this range, it is not conducive to forming an upward circulation in the circumferential direction near the outer wall of the gasifier.

[0066] Optionally, at least three second auxiliary gasifying agent inlets (20) are provided along the circumferential direction of the shell of the middle transition zone (6). Figure 3, three evenly distributed second auxiliary gasification agent inlets (20) are provided, which is conducive to the introduction of the second auxiliary gasification agent to cover the upper part of the returned particles, increase the turbulent state of the gas field, prolong the particle residence time, promote the reaction in this area, and facilitate the full reaction of the recovered high-temperature second particle size fly ash particles. The angle β between the central axis of the second auxiliary gasification agent inlet (20) and the tangent of the shell circumference of the middle transition zone (6) is 50°-80° (optionally: 50°, 54°, 57°, 61°, 65°, 69°, 72°, 75°, 77°, 80°, etc.). If the angle is less than this range, the second auxiliary gasification agent is introduced too close to the outer wall of the gasifier, which is not conducive to the reaction.

[0067] Optionally, the inner wall of the second fly ash coating chamber (15) is provided with a baffle (23) to help extend the path of coating the mixed particles and improve the coating effect; the inner wall of the fly ash activation chamber (19) is provided with spiral protrusions or grooves (24) to help improve the mixing effect of solids and gases in the chamber. By arranging different diversion and mixing structures in different chambers, the effect of fly ash coating carbon particles can be further improved and its reaction activity can be improved.

[0068] Example 2

[0069] like Figure 2 , 3 -4, another embodiment of the present invention provides a gasification fly ash treatment system and method for heat energy recovery,

[0070] A fly ash activation chamber (19) is additionally provided, and the coking coal (16) is fed into the first fly ash coating chamber (22) and coated and mixed with the fly ash particles of the second particle size before entering the second fly ash coating chamber (15), and is further coated and mixed with the fly ash particles of the third particle size before entering the fly ash activation chamber (19), and a portion of the fly ash particles of the first particle size is drawn out and enters the fly ash activation chamber (19), and a portion of the fly ash particles of the first particle size is drawn out and enters the fly ash activation chamber (19), and the coking coal (16), the fly ash particles of the second particle size, the fly ash particles of the third particle size and the fly ash particles of the first particle size are further coated and mixed before entering the lower dense phase zone (3) through the particle coal inlet (17). By partially drawing out the first particle size fly ash particles with high high-temperature reaction activity and coating and mixing them with the fly ash-coated particle coal drawn out from the second fly ash coating chamber in the fly ash activation chamber, high-temperature heating is used to make the first particle size fly ash particles with high reaction activity coat the fly ash-coated particle coal, so that its temperature and reaction activity are improved, which is beneficial to further improve the utilization of the fly ash-coated particle coal.

[0071] In summary, the gasification fly ash treatment system and method with heat energy recovery provided by the present invention realize the true resource processing of circulating fluidized bed gasification fly ash under low temperature conditions, the carbon in the gasification fly ash is fully and efficiently utilized, the chemical heat of the gasification fly ash is fully utilized, the carbon content in the gasification fly ash is reduced, and at the same time, the heat energy of the high-temperature coal gas containing gasification fly ash generated by the gasifier is fully recovered and utilized.

[0072] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0073] The terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0074] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific conditions. In the description of this specification, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gasification fly ash treatment system for heat recovery, characterized in that: include: A circulating fluidized bed gasifier (1) is used for gasifying coal powder and a gasifying agent in the circulating fluidized bed gasifier (1) to obtain high-temperature coal gas, wherein the circulating fluidized bed gasifier (1) comprises an upper dilute phase zone (2), a middle transition zone (6), and a lower dense phase zone (3), wherein the coal powder enters the lower dense phase zone (3) from a coal bunker through a conveying pipeline through a coal powder inlet (4), and the gasifying agent comprises a main gasifying agent, and the main gasifying agent enters the lower dense phase zone (3) through a main gasifying agent inlet (5) at the bottom of the circulating fluidized bed gasifier (1); A first gas-solid separator (7), wherein high-temperature coal gas is drawn out from the top of the circulating fluidized bed gasifier (1) and enters the first gas-solid separator (7) through a pipeline, and coal gas containing fly ash at a first temperature and fly ash particles of a first temperature and a first particle size are separated, and the fly ash particles of the first particle size are returned to the middle transition zone (6) through a return port (8); a second gas-solid separator (9), wherein the coal gas at a first temperature containing fly ash enters the second gas-solid separator (9) through a pipeline, and the coal gas at the first temperature and fly ash particles of a second particle size at the first temperature are separated, and the fly ash particles of the second particle size are transported to the first fly ash coating cavity (22) through the pipeline; A molten salt heat exchanger (10) is used to separate coal gas at a first temperature, which is cooled to a second temperature through the molten salt heat exchanger (10), further cooled to a third temperature through a steam heat exchanger (11), and then enters a dust collector (12) to obtain clean coal gas (18). Fly ash particles with a third particle size and a third temperature are collected at the bottom of the dust collector (12); steam obtained by heat exchange in the steam heat exchanger (11) enters the lower dense phase zone (3) through a first auxiliary gasifying agent inlet (13) located above the main gasifying agent inlet (5); The heat transfer medium molten salt of the molten salt heat exchanger (10) preheats the fly ash particles of the third particle size through a third heat exchanger (14), and the fly ash particles of the third particle size enter the second fly ash coating cavity (15); The coking coal (16) is fed into the first fly ash coating chamber (22) and is coated and mixed with the fly ash particles of the second particle size before entering the second fly ash coating chamber (15), and is further coated and mixed with the fly ash particles of the third particle size before entering the lower dense phase zone (3) through the particle coal inlet (17); the particle size of the coking coal (16) is 4 mm-10 mm; a fly ash activation chamber (19) is provided, and the coking coal (16) is fed into the first fly ash coating chamber (22) and is coated and mixed with the fly ash particles of the second particle size before entering the second fly ash coating chamber (15), After being further coated and mixed with the fly ash particles of the third particle size, the particles enter the fly ash activation chamber (19); a portion of the fly ash particles of the first particle size are drawn out to enter the fly ash activation chamber (19); the coking coal (16), the fly ash particles of the second particle size, the fly ash particles of the third particle size and the fly ash particles of the first particle size are further coated and mixed and enter the lower dense phase zone (3) through the particle coal inlet (17); the diameter of the upper dilute phase zone (2) is greater than the diameter of the lower dense phase zone (3); and the diameter of the middle transition zone (6) gradually increases from bottom to top.

2. The gasification fly ash treatment system for heat recovery according to claim 1 is characterized in that: The steam obtained by heat exchange in the steam heat exchanger (11) enters the middle transition zone (6) through a second auxiliary gasifying agent inlet (20) located above the return port (8), and / or the steam obtained by heat exchange in the steam heat exchanger (11) enters the lower dense phase zone (3) through a third auxiliary gasifying agent inlet (21) located above the pulverized coal inlet (4).

3. The gasification fly ash treatment system for heat recovery according to claim 2 is characterized in that: The first auxiliary gasifying agent inlet (13), the third auxiliary gasifying agent inlet (21) and the particle coal inlet (17) are arranged to be inclined upward, and the second auxiliary gasifying agent inlet (20) is arranged to be inclined downward, and the central axes of the first auxiliary gasifying agent inlet (13), the third auxiliary gasifying agent inlet (21), the particle coal inlet (17) and the second auxiliary gasifying agent inlet (20) are respectively arranged at an angle of 10° to 25° with the horizontal plane.

4. The gasification fly ash treatment system for heat recovery according to claim 3 is characterized in that: The first auxiliary gasifying agent inlet (13) and the particle coal inlet (17) are at the same height in the horizontal direction. Along the circumferential direction of the shell of the lower dense phase zone (3), the particle coal inlet (17) is located between two adjacent first auxiliary gasifying agent inlets (13). The angle α between the central axis of the first auxiliary gasifying agent inlet (13) and the particle coal inlet (17) and the tangent of the shell circumference of the lower dense phase zone (3) is 15°-35°.

5. The gasification fly ash treatment system for heat recovery according to claim 3 is characterized in that: At least three second auxiliary gasifying agent inlets (20) are arranged along the shell circumference direction of the middle transition zone (6), and the angle β between the central axis of the second auxiliary gasifying agent inlet (20) and the tangent of the shell circumference of the middle transition zone (6) is 50°-80°.

6. The gasification fly ash treatment system for heat recovery according to claim 1 is characterized in that: The inner wall of the second fly ash coating cavity (15) is provided with a baffle (23); and the inner wall of the fly ash activation cavity (19) is provided with a spiral protrusion or groove (24).

7. A method for treating gasified fly ash with heat recovery, using the gasified fly ash treatment system with heat recovery as described in any one of claims 1, 2-5, characterized in that: Step 1: coal powder and a gasifying agent are gasified in the circulating fluidized bed gasifier (1) to obtain high-temperature coal gas, wherein the gasification temperature is 800° C.-1100° C.; Step 2: High-temperature coal gas is drawn from the top of the circulating fluidized bed gasifier (1) and enters the first gas-solid separator (7) through a pipeline to separate coal gas containing fly ash at a first temperature and fly ash particles of a first temperature and a first particle size, and the fly ash particles of the first particle size are returned to the middle transition zone (6) through a return port (8); the first temperature is 700° C.-890° C.; Step 3: the coal gas at the first temperature containing fly ash enters the second gas-solid separator (9) through a pipeline, and the coal gas at the first temperature and fly ash particles of the second particle size at the first temperature are separated, and the fly ash particles of the second particle size are transported to the first fly ash coating cavity (22) through a pipeline; Step 4: separating the coal gas at the first temperature, cooling it to a second temperature through a molten salt heat exchanger (10), further cooling it to a third temperature through a steam heat exchanger (11), and then entering a dust collector (12) to obtain clean coal gas (18); fly ash particles of a third particle size and a third temperature are collected at the bottom of the dust collector (12); the second temperature is 400° C. to 500° C., and the third temperature is 150° C. to 250° C.; The steam obtained by heat exchange in the steam heat exchanger (11) enters the lower dense phase zone (3) through a first auxiliary gasifying agent inlet (13) located above the main gasifying agent inlet (5); The heat transfer medium molten salt of the molten salt heat exchanger (10) preheats the fly ash particles of the third particle size to a fourth temperature through a third heat exchanger (14), and the fly ash particles of the third particle size enter the second fly ash coating cavity (15); the fourth temperature is 300° C.-450° C.; Coking coal (16) is fed into the first fly ash coating chamber (22) and coated and mixed with the fly ash particles of the second particle size before entering the second fly ash coating chamber (15), and is further coated and mixed with the fly ash particles of the third particle size before entering the lower dense phase zone (3) through the particle coal inlet (17).

8. The method for treating gasified fly ash for heat recovery according to claim 7, characterized in that: In step 4, the coking coal (16) is fed into the first fly ash coating chamber (22) and is coated and mixed with the fly ash particles of the second particle size before entering the second fly ash coating chamber (15), and is further coated and mixed with the fly ash particles of the third particle size before entering the fly ash activation chamber (19), and a portion of the fly ash particles of the first particle size is drawn out to enter the fly ash activation chamber (19), and the coking coal (16), the fly ash particles of the second particle size, the fly ash particles of the third particle size and the fly ash particles of the first particle size are further coated and mixed before entering the lower dense phase zone (3) through the particle coal inlet (17).

9. The method for treating gasified fly ash for heat recovery according to claim 7 or 8, characterized in that: The average particle size of the fly ash particles of the first particle size is greater than the average particle size of the fly ash particles of the second particle size, and the average particle size of the fly ash particles of the second particle size is greater than the average particle size of the fly ash particles of the third particle size; the particle size of the coking coal (16) is 5 mm-8 mm.

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