A circulating fluidized bed boiler with high heat utilization rate and combustion method

Abstract

A circulating fluidized bed boiler with high heat utilization rate and a combustion method, belonging to the technical field of fluidized bed boilers. The invention is characterized in that: a residual powder collecting hood (3) is provided on the upper part of the combustion chamber of the combustion chamber furnace body (1), a flue gas passage is left between the residual powder collecting hood (3) and the combustion chamber furnace body (1), and the upper wall (301) and the lower wall (301) of the residual powder collecting hood form a powder inlet opening inward and downward; the residual powder collecting hood (3) is connected to the feed end of a venturi feeder (6) provided on the blast pipe (2) through an air duct (5); a guide plate (4) is provided below the residual powder collecting hood (3), the outer end of the guide plate (4) is fixed on the combustion chamber furnace body (1), and the inner end of the guide plate (4) extends below the residual powder collecting hood (3). The present invention realizes the recovery of unburned powder without adding additional negative pressure power equipment; the unburned powder is returned to the combustion chamber for combustion, ensuring the utilization rate of human energy and avoiding the waste of calorific value of the unburned powder when it is burned outside the combustion chamber.

Description

Technical Field

[0001] The invention relates to a circulating fluidized bed boiler with high heat utilization rate and a combustion method, belonging to the technical field of fluidized bed boilers. Background Art

[0002] Circulating fluidized bed boilers are the most industrialized clean coal combustion technology. Circulating fluidized bed boilers utilize fluidized combustion, and their primary structure consists of two major components: a combustion chamber (including dense and dilute phase zones) and a circulating recirculation furnace (including a high-temperature gas-solid separator and a return system). The biggest difference from bubbling fluidized bed combustion technology is the high operating wind speed, which intensifies heterogeneous reaction processes such as combustion and desulfurization, allowing the boiler capacity to be expanded to a large capacity acceptable to the power industry (600MW or above). Currently, circulating fluidized bed boilers have effectively addressed fundamental issues in thermodynamics, mechanics, and materials science, as well as engineering challenges such as expansion, wear, and overheating, making them an advanced technology for the energy utilization of difficult-to-burn solid fuels (such as coal gangue, oil shale, municipal waste, sludge, and other wastes).

[0003] In current circulating fluidized bed boilers, small fuel particles within the solid fuel are easily blown into the recirculating retort, a key objective of the recirculating retort design. Numerous patents and papers offer methods for increasing the combustion rate of small fuel particles after being blown into the recirculating retort, or for increasing their recovery rate in the solids separator and recirculation system. These methods all aim to improve fuel utilization. However, the utilization rate of the heat energy generated by the combustion of small fuel particles in the recirculating retort is far lower than that generated in the combustion chamber. Therefore, further improving the utilization rate of the heat energy generated by the combustion of small fuel particles in the combustion chamber still holds significant social value. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a circulating fluidized bed boiler and a combustion method with high heat utilization rate in the combustion chamber.

[0005] The technical solution adopted by the present invention to solve its technical problems is: the circulating fluidized bed boiler with high thermal utilization rate includes a combustion chamber furnace body, and a blast duct is provided at the bottom of the combustion chamber furnace body, which is characterized in that: a residual powder collection hood is provided on the upper part of the combustion chamber of the combustion chamber furnace body, and a flue gas passage is left between the residual powder collection hood and the combustion chamber furnace body, and the residual powder collection hood is composed of an upper wall of the residual powder collection hood and a lower wall of the residual powder collection hood, and the upper wall of the residual powder collection hood and the lower wall of the residual powder collection hood are fixed by connecting ribs therebetween, and the upper wall of the residual powder collection hood and the lower wall of the residual powder collection hood form a powder inlet opening facing inward and downward; the residual powder collection hood is connected to the feed end of the Venturi feeder arranged on the blast duct through an induced draft duct; a guide plate is provided below the residual powder collection hood, the outer end of the guide plate is fixed on the combustion chamber furnace body, and the inner end of the guide plate extends to the bottom of the residual powder collection hood.

[0006] Preferably, the air duct is provided with an adhesive liquid spraying inlet, and the adhesive liquid spraying inlet is connected to a adhesive liquid storage tank.

[0007] Preferably, the residual powder collection cover is made of refractory material. The residual powder collection cover can be an integrally formed refractory material and directly installed during the installation of the boiler or built on-site with refractory bricks during the installation of the boiler.

[0008] A circulating fluidized bed combustion method with high thermal utilization rate for the above-mentioned boiler, wherein during the combustion process of the boiler, a large amount of air is blown into the blast pipe, and an airflow is formed in the blast pipe, and the method is characterized in that: the airflow in the blast pipe forms a negative pressure in the induced draft pipe through the venturi feeder, thereby forming an inward suction force at the powder inlet of the residual powder collection hood; the rising flue gas is guided to the bottom of the residual powder collection hood by a guide plate, and the flue gas is blocked by the residual powder collection hood and forms a backflow along the outer wall of the lower wall of the residual powder collection hood, and the reflux flue gas carries particulate fuel that has not been fully burned and is sucked into the residual powder collection hood when passing through the powder inlet of the residual powder collection hood, and the particulate fuel enters the blast pipe through the induced draft pipe and the venturi feeder and returns to the combustion chamber to be burned again.

[0009] Preferably, the binder liquid storage tank stores an aqueous solution of a combustible binder, and the aqueous solution of the combustible binder is pumped into the induced draft duct to humidify the particle fuel and cause the particle fuel to adsorb each other to form particle agglomerates.

[0010] Preferably, the combustible binder is cotton linters. Cotton linters are preferred because their natural composition can effectively agglomerate the pellets, and after combustion, they do not produce new combustion residues or residual oil, nor do they generate harmful gases. This also does not increase sulfur and nitrogen emissions.

[0011] Compared with the prior art, the beneficial effects of the circulating fluidized bed boiler and combustion method with high heat utilization rate of the present invention are as follows: the present invention utilizes the airflow of the blast pipe itself and the venturi feeder to form suction, and the guide plate guides the flue gas to the bottom of the residual powder collection hood, and is forced to flow back under the action of the residual powder collection hood. Most of the particles in the flue gas are pressed on the lower outer wall of the residual powder collection hood under the action of the airflow, and are sucked into the residual powder collection hood when passing through the powder inlet of the residual powder collection hood. Most of the lighter flue gas will not be affected by the suction of the powder inlet of the residual powder collection hood, and will continue to rise through the flue gas channel left between the residual powder collection hood and the combustion chamber furnace body, and enter the circulating re-furnace to further recover the residual powder.

[0012] The present invention realizes the recovery of unburned powder without adding additional negative pressure power equipment; the unburned powder is returned to the combustion chamber for combustion, ensuring the utilization rate of human energy and avoiding the waste of calorific value of the unburned powder when it is burned outside the combustion chamber.

[0013] The present invention adds an aqueous solution of a combustible binder to the unburned powder, and forms the unburned powder into large agglomerated particles by adding the aqueous solution of the combustible binder, thereby reducing the probability of the powder being blown away again and increasing the combustion rate of the fuel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise specified, these drawings are intended only to conceptually illustrate the structures described herein and are not necessarily drawn to scale.

[0015] FIG1 is a schematic diagram of a circulating fluidized bed boiler with high heat utilization rate according to the present invention.

[0016] Among them, 1, combustion chamber furnace body 2, blast pipeline 3, residual powder collection cover 301, residual powder collection cover upper wall 301, residual powder collection cover lower wall 4, guide plate 5, induced draft pipe 6, venturi feeder 7, and adhesive liquid storage tank. DETAILED DESCRIPTION

[0017] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0018] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0019] Refer to the attached Figure 1The present embodiment provides a circulating fluidized bed boiler with high heat utilization rate, including a combustion chamber furnace body 1, a blast pipe 2 is provided at the bottom of the combustion chamber furnace body 1, a residual powder collection cover 3 is provided at the upper part of the combustion chamber of the combustion chamber furnace body 1, and a flue gas channel is reserved between the residual powder collection cover 3 and the combustion chamber furnace body 1, and the residual powder collection cover 3 is composed of an upper wall 301 of the residual powder collection cover and a lower wall 301 of the residual powder collection cover, the upper wall 301 of the residual powder collection cover and the lower wall 301 of the residual powder collection cover are fixed by connecting ribs therebetween, and the upper wall 301 of the residual powder collection cover and the lower wall 301 of the residual powder collection cover form a powder inlet opening facing inward and downward; the residual powder collection cover 3 is connected to the feeding end of the venturi feeder 6 provided on the blast pipe 2 through an induced draft pipe 5; a guide plate 4 is provided below the residual powder collection cover 3, the outer end of the guide plate 4 is fixed on the combustion chamber furnace body 1, and the inner end of the guide plate 4 extends to the bottom of the residual powder collection cover 3. The induced draft pipe 5 is provided with a bonding liquid spraying port, which is connected to the bonding liquid storage tank 7 via a pipeline with a material pump, and the bonding liquid spraying port is provided with a spray head. The residual powder collecting cover 3 is made of refractory material.

[0020] The residual powder collecting cover 3 is hemispherical and is suspended and fixed in the middle position of the upper part of the combustion chamber. The upper wall 301 of the residual powder collecting cover and the lower wall 301 of the residual powder collecting cover are connected and fixed by multiple connecting columns.

[0021] It can also be that: the residual powder collection cover 3 is a curved surface, the upper end is the outer side, fixed on the inner wall of the combustion chamber furnace body 1, the lower end is the inner side, suspended in the combustion chamber furnace body 1, and a flue gas channel is left with the combustion chamber furnace body 1; the guide plate 4 is fixed on the inner wall of the combustion chamber furnace body 1 below the residual powder collection cover 3 at the same inclination angle.

[0022] A circulating fluidized bed combustion method with high heat utilization rate, during the combustion process of the boiler, a large amount of air is blown into the blast pipe 2, and an air flow is formed in the blast pipe 2. The air flow in the blast pipe 2 forms a negative pressure in the induced draft pipe 5 through the venturi feeder 6, thereby forming an inward suction force at the powder inlet of the residual powder collection hood 3; the rising flue gas is guided to the bottom of the residual powder collection hood 3 by the guide plate 4, and the flue gas is blocked by the residual powder collection hood 3 and then forms a backflow along the outer wall of the lower wall 301 of the residual powder collection hood. The refluxed flue gas carries particulate fuel that has not been fully burned and is sucked into the residual powder collection hood 3 when it passes through the powder inlet of the residual powder collection hood 3. The particulate fuel enters the blast pipe 2 through the induced draft pipe 5 and the venturi feeder 6 and returns to the combustion chamber to be burned again.

[0023] The binder storage tank 7 stores an aqueous solution of a combustible binder, and the aqueous solution of the combustible binder is pumped into the induced draft pipe (5), humidifying the particle fuel and adsorbing the particle fuel to form particle agglomerates.

[0024] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A circulating fluidized bed boiler with high heat utilization rate, comprising a combustion chamber furnace body (1), a blast pipe (2) being provided at the bottom of the combustion chamber furnace body (1), and characterized in that: A residual powder collecting hood (3) is provided at the upper part of the combustion chamber of the combustion chamber furnace body (1), and a flue gas passage is reserved between the residual powder collecting hood (3) and the combustion chamber furnace body (1). The residual powder collecting hood (3) is composed of an upper wall (301) of the residual powder collecting hood and a lower wall (301) of the residual powder collecting hood. The upper wall (301) of the residual powder collecting hood and the lower wall (301) of the residual powder collecting hood are fixed by connecting ribs therebetween. The upper wall (301) of the residual powder collecting hood and the lower wall (301) of the residual powder collecting hood form a powder inlet opening inward and downward; the residual powder collecting hood (3) is connected to the feed end of the Venturi feeder (6) provided on the blast pipe (2) through an air duct (5); a guide plate (4) is provided below the residual powder collecting hood (3), the outer end of the guide plate (4) is fixed on the combustion chamber furnace body (1), and the inner end of the guide plate (4) extends below the residual powder collecting hood (3).

2. The circulating fluidized bed boiler with high heat utilization rate according to claim 1, characterized in that: The air duct (5) is provided with a bonding liquid spraying port, and the bonding liquid spraying port is connected to a bonding liquid storage tank (7).

3. The circulating fluidized bed boiler with high heat utilization rate according to claim 1, characterized in that: The residual powder collecting cover (3) is made of refractory material.

4. A circulating fluidized bed combustion method with high heat utilization rate for a boiler according to claim 2, wherein during the combustion process of the boiler, a large amount of air is blown into the blast pipe (2), and an air flow is formed in the blast pipe (2), characterized in that: The airflow of the blast pipe (2) forms a negative pressure in the induced draft pipe (5) through the venturi feeder (6), thereby forming an inward suction force at the powder inlet of the residual powder collecting hood (3); the rising smoke is guided to the bottom of the residual powder collecting hood (3) by the guide plate (4); the smoke is blocked by the residual powder collecting hood (3) and forms a backflow along the outer wall of the lower wall (301) of the residual powder collecting hood; the backflowing smoke carries particulate fuel that has not been fully burned and is sucked into the residual powder collecting hood (3) when passing through the powder inlet of the residual powder collecting hood (3); the particulate fuel enters the blast pipe (2) through the induced draft pipe (5) and the venturi feeder (6) and returns to the combustion chamber to be burned again.

5. The circulating fluidized bed combustion method with high heat utilization rate according to claim 4, characterized in that: The binder storage tank (7) stores an aqueous solution of a combustible binder, and the aqueous solution of the combustible binder is pumped into the induced draft pipe (5) to humidify the particle fuel and adsorb the particle fuel to form particle agglomerates.

6. The circulating fluidized bed combustion method with high heat utilization rate according to claim 4, characterized in that: The combustible bonding material is cotton linters.

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