Novel hearth structure of circulating fluidized bed boiler

Abstract

The utility model discloses a novel hearth structure of a circulating fluidized bed boiler. The novel hearth structure comprises a hearth body, the lower portion of the hearth body is in a funnel shape, the upper portion of the funnel-shaped portion of the hearth body is a dense-phase area, the lower portion of the funnel-shaped portion of the hearth body is an air chamber, the side wall of the upper portion of the dense-phase area of the hearth body is an efficient heat transfer area, and the side wall of the lower portion of the dense-phase area is a low-efficiency heat transfer area. The dense-phase area of the hearth is divided into two heat transfer areas, namely the high-efficiency heat transfer area at the upper part and the low-efficiency heat transfer area at the lower part, so that the lower part of the dense-phase area is poor in heat transfer property, small in heat loss, high in heat efficiency and stable in combustion, and when the boiler runs at a low load, compared with a conventional boiler hearth structure, the low-heat-value fuel can be combusted, and the bed temperature is high; the bottom slag is low in carbon content and high in combustion efficiency, the desulfurization effect of limestone in the furnace is good, the dosage is small, NOX is originally generated, meanwhile, the temperature of a hearth outlet is increased, the denitration efficiency of SNCR is improved, and the risk that an air pre-heater is blocked by ammonium bisulfate is reduced.

Description

Technical Field

[0001] This utility model relates to the field of circulating fluidized bed boiler technology, specifically to a novel furnace structure for a circulating fluidized bed boiler. Background Technology

[0002] A circulating fluidized bed boiler system typically consists of a fluidized bed combustion chamber (furnace), a circulating ash separator, a fly ash return device, a tail heating surface, and auxiliary equipment.

[0003] Currently, there are many circulating fluidized bed boilers in operation, but their peak-shaving capacity is low, typically operating at 30% of their rated load. Although these boilers have the ability to operate at low loads, their operating parameters deteriorate, mainly manifested during the lowest stable combustion load period as excessively low bed temperature, low in-furnace desulfurization efficiency, low furnace outlet temperature, low SNCR reaction efficiency, and high oxygen content in the boiler outlet flue gas, posing significant environmental risks.

[0004] At present, the heat transfer efficiency of the upper and lower parts of the dense phase zone is the same. When the boiler equipment is operating under low load and using low calorific value fuel for combustion, the heat loss is more significant, the thermal efficiency is reduced, the fluidization is deteriorated, and combustion instability is easily caused. Utility Model Content

[0005] In order to solve the problems of the prior art, this utility model provides a novel furnace structure for a circulating fluidized bed boiler.

[0006] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution: a new type of furnace structure for a circulating fluidized bed boiler, including a furnace body;

[0007] The lower part of the furnace body is funnel-shaped. The upper part of the funnel-shaped part of the furnace body is a dense phase zone and the lower part is a wind chamber. The side wall of the upper part of the dense phase zone of the furnace body is a high-efficiency heat transfer zone and the side wall of the lower part of the dense phase zone is a low-efficiency heat transfer zone.

[0008] Furthermore, the high-efficiency heat transfer zone is provided with refractory material, and the low-efficiency heat transfer zone is also provided with refractory material.

[0009] Furthermore, the wall thickness of the refractory material in the high-efficiency heat transfer zone is less than the wall thickness of the refractory material in the low-efficiency heat transfer zone.

[0010] Furthermore, the wall thickness of the refractory material in the high-efficiency heat transfer zone is the same as that in the low-efficiency heat transfer zone. The refractory material in the high-efficiency heat transfer zone has a high heat transfer coefficient, while the refractory material in the low-efficiency heat transfer zone has a low heat transfer coefficient.

[0011] The advantages of this invention compared to existing technologies are as follows: The dense phase zone of the furnace in this invention is divided into two heat transfer zones: an upper high-efficiency heat transfer zone and a lower low-efficiency heat transfer zone. This structure results in poor heat transfer in the lower part of the dense phase zone, less heat loss, improved thermal efficiency, and stable combustion. When the boiler is running at low load, compared with conventional boiler furnace structures, it can burn lower calorific value fuels, has a higher bed temperature, lower carbon content in the bottom ash, higher combustion efficiency, better desulfurization effect of limestone in the furnace, lower dosage, and less NOx formation. At the same time, the furnace outlet temperature is increased, improving the denitrification efficiency of SNCR and reducing the risk of ammonium bisulfate blockage in the air preheater. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the furnace structure of a novel circulating fluidized bed boiler according to this utility model.

[0013] As shown in the figure:

[0014] 1. Furnace body; 101. Dense phase zone; 10101. High-efficiency heat transfer zone; 10102. Low-efficiency heat transfer zone; 102. Air chamber. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0016] Example 1, in conjunction with Appendix Figure 1 A novel circulating fluidized bed boiler furnace structure, comprising a furnace body 1;

[0017] The lower part of the furnace body 1 is funnel-shaped. The upper part of the funnel-shaped part of the furnace body 1 is the dense phase zone 101 and the lower part is the air chamber 102. The side wall of the upper part of the dense phase zone 101 of the furnace body 1 is the high-efficiency heat transfer zone 10101 and the side wall of the lower part of the dense phase zone 101 is the low-efficiency heat transfer zone 10102.

[0018] In this specific embodiment, the high-efficiency heat transfer zone 10101 is provided with refractory material, and the low-efficiency heat transfer zone 10102 is provided with refractory material.

[0019] In this specific embodiment, the wall thickness of the refractory material in the high-efficiency heat transfer zone 10101 is the same as that in the low-efficiency heat transfer zone 10102. The heat transfer coefficient of the refractory material in the high-efficiency heat transfer zone 10101 is high, while the heat transfer coefficient of the refractory material in the low-efficiency heat transfer zone 10102 is low.

[0020] Working principle:

[0021] The dense phase zone of the boiler primarily functions as a high-density combustion zone for fuel, mainly releasing heat through fuel combustion to maintain the combustion temperature. Thin refractory materials are used for wear protection.

[0022] The high-efficiency heat transfer zone 10101 is located near the combustion acceleration zone and undertakes the main task of heat release and transfer. It adopts a thin-walled design, such as a wall thickness of 50mm, and is combined with high thermal conductivity refractory materials, such as silicon carbide bricks, with a thermal conductivity ≥15W / (m·K), to accelerate the transfer of heat to the working fluid, enhance heat absorption, and reduce the peak temperature of the bed.

[0023] The inefficient heat transfer zone 10102 is located near the air chamber 102 and its main function is to reduce the amount of heat dissipated to the water-cooled wall, allowing more heat to remain in the bed material at the bottom of the dense phase zone 101, thus maintaining the temperature stability of the bottom of the dense phase zone 101. It employs a thick-walled design or refractory materials with poor heat transfer coefficients, such as wall thicknesses of 50-200 mm, combined with low thermal conductivity refractory materials (≤10 W / (m·K)) to form a thermal resistance barrier, reducing heat loss and maintaining combustion stability.

[0024] Therefore, boiler equipment is suitable for burning low-calorific-value fuels when operating under low load conditions.

[0025] In particular, the refractory materials of the high-efficiency heat transfer zone 10101 and the low-efficiency heat transfer zone 10102 can also use the same matrix material. In this case, the wall thickness of the refractory material of the high-efficiency heat transfer zone 10101 is smaller than the wall thickness of the refractory material of the low-efficiency heat transfer zone 10102, such as CA-70 aluminate cement-based, to avoid the risk of cracking caused by expansion mismatch of dissimilar materials.

[0026] In the description of the embodiments of this utility model, it should be noted that if terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," or "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, they are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, terms such as "first," "second," and "third" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0027] Furthermore, the use of terms such as "horizontal," "vertical," and "sag" does not imply that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] In the description of the embodiments of this utility model, "a plurality of" means at least two.

[0029] In the description of the embodiments of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0030] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A novel circulating fluidized bed boiler furnace structure, comprising a furnace body (1), characterized in that: The lower part of the furnace body (1) is funnel-shaped. The upper part of the funnel-shaped part of the furnace body (1) is a dense phase zone (101) and the lower part is a wind chamber (102). The side wall of the upper part of the dense phase zone (101) of the furnace body (1) is a high-efficiency heat transfer zone (10101) and the side wall of the lower part of the dense phase zone (101) is a low-efficiency heat transfer zone (10102).

2. The furnace structure of a novel circulating fluidized bed boiler according to claim 1, characterized in that: The high-efficiency heat transfer zone (10101) is provided with refractory material, and the low-efficiency heat transfer zone (10102) is provided with refractory material.

3. The furnace structure of a novel circulating fluidized bed boiler according to claim 2, characterized in that: The wall thickness of the refractory material in the high-efficiency heat transfer zone (10101) is less than that in the low-efficiency heat transfer zone (10102).

4. The furnace structure of a novel circulating fluidized bed boiler according to claim 2, characterized in that: The wall thickness of the refractory material in the high-efficiency heat transfer zone (10101) is the same as that in the low-efficiency heat transfer zone (10102). The heat transfer coefficient of the refractory material in the high-efficiency heat transfer zone (10101) is high, while the heat transfer coefficient of the refractory material in the low-efficiency heat transfer zone (10102) is low.

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