A topless chamber heat shock furnace sootblower nozzle and optimization method

Abstract

This invention discloses a top-chamber-less, thermal shock resistant furnace sootblower nozzle and its optimization method. The top-chamber-less, thermal shock resistant furnace sootblower nozzle includes a nozzle body, characterized in that the nozzle body comprises a shell, a shell top, and a nozzle, with the nozzle axis angle slightly tilted backward by 2.5-5° and an expansion angle of 13°. Compared with existing technologies, this invention has the following advantages: reducing the distance between the nozzle tip and the fire-facing surface (~12mm) to reduce radiation; using a fluid curved surface in the cross-section to reduce thermal stress; reducing casting weight and cost through optimization; and reducing the occurrence of cracking.

Description

Technical Field

[0001] This invention belongs to the field of sootblower nozzle technology, specifically, it relates to a thermal shock resistant furnace sootblower nozzle without a top chamber and an optimization method. Background Technology

[0002] The furnace sootblower is installed in the furnace of a large thermal power plant boiler to clean ash and coke buildup on the water-cooled wall surface online. After the sootblower's telescopic rotating nozzle enters the furnace, it begins blowing soot. During the blowing process, the nozzle rotates 360°, and high-temperature, high-pressure steam (1.0~1.4 MPa, temperature 320~350°C) is ejected through the nozzle, evenly "sweeping" the water-cooled wall and removing coke, slag, and accumulated ash from the furnace. After the sootblower stops, the steam is shut off, and the nozzle withdraws from the furnace, but the tip of the nozzle remains approximately 70mm away from the furnace.

[0003] The entire working environment, with furnace temperatures reaching ~1400°C, requires the nozzles to withstand high levels of thermal radiation. During purging, the spherical nozzle tip bears extremely high thermal shock. The nozzles are manufactured using a casting process, made of heat-resistant steel (ZGCr20Ni14Si2), with a thickness of 6~8mm to withstand these high thermal shocks. In field use, tip cracking and nozzle failure frequently occur, requiring manual repair and replacement.

[0004] An optimized nozzle design for an IR furnace sootblower, originating from Diamond Electric Machinery, USA, comprises a nozzle consisting of a housing 1, a housing top 2, a nozzle 3, and a top chamber 4. Figure 1 The nozzle axis is slightly tilted backward by 2.5-5°, with a slight expansion angle of 13°. During sootblowing, high-temperature steam first enters the top chamber, then exits from the nozzle. As it passes through the throat, the steam is compressed and accelerated before leaving the nozzle through the expansion zone. Because there are chambers before and after the steam nozzle outlet, the pressure distribution after the steam leaves the outlet is relatively uniform, achieving a better sootblowing effect. However, nozzle bursting also frequently occurs.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0007] A thermal shock resistant furnace soot blower nozzle without a top chamber, the nozzle body includes a shell, a shell top, and a nozzle, the nozzle axis angle is slightly tilted back by 2.5-5°, and the expansion angle is 13°.

[0008] The wall thickness of the top of the shell is 6-8 mm.

[0009] The nozzle employs a fluid curved surface to reduce stress at the nozzle tip.

[0010] The nozzle body has an outer diameter of 60.3 mm and a throat diameter of 25.4 mm.

[0011] The nozzle body is made of A297-Gr-HT or ZGCr20Ni14Si2 heat-resistant cast steel.

[0012] Computer simulations were used to verify and optimize the pressure distribution of different dimensions of the nozzle body, and the optimal values ​​were selected. Based on these optimal values, a more suitable nozzle was designed.

[0013] Compared with existing technologies, this invention has the following advantages: reducing the distance between the nozzle tip and the flame-facing surface (~12mm) to reduce radiation; employing a fluid curved surface in the cross-section to reduce thermal stress; and reducing casting weight and cost through optimization. It also reduces the likelihood of cracking.

[0014] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0016] In the attached diagram:

[0017] Figure 1 This is a cross-sectional view of an existing nozzle;

[0018] Figure 2 This is a cross-sectional view of the optimized nozzle;

[0019] Figure 3 These are pressure distribution diagrams at the outlets of the two types of nozzles;

[0020] Figure 4 This is a cross-sectional view of the pressure distribution at a distance of 0.2m from the outlet for two types of nozzles;

[0021] Figure 5 This is a cross-sectional view of the pressure distribution at a distance of 0.3m from the outlet for two types of nozzles;

[0022] Figure 6 It optimizes the nozzle velocity distribution cloud map.

[0023] In the diagram: 1. Shell; 2. Shell top; 3. Nozzle; 4. Top chamber. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention.

[0025] This invention eliminates the top chamber and optimizes the curved surface. We have made adjustments to the nozzle shape (such as...). Figure 2The spherical tip was eliminated, and the nozzle adopted a fluid curved surface to reduce stress at the nozzle tip. Due to the improved mechanical properties, the wall thickness of the tip was reduced from the original 9mm to 6-8mm. After 10 months of operation testing, no nozzle breakage occurred, and the service life was greatly increased.

[0026] The improved advantages are: reduced distance between the nozzle tip and the fire-facing surface (~12mm) to decrease radiation; and a fluid-curved cross-section to reduce thermal stress. Through optimization, the casting weight and cost are reduced. In a case study of this product used in the sootblower of a 4x200MW boiler at a power plant in Hami, Xinjiang, with a main pipe steam pressure of 1.2MPa and a temperature of 330°C~350°C, and the sootblowing steam source branch pipe containing a small amount of condensate, no bursting occurred after 14 months of trial operation.

[0027] Computer simulations have verified that the steam nozzle maintains relatively uniform pressure at a distance of 10-15 cm, effectively and evenly purifying the furnace surface. The verification results are as follows.

[0028] Taking a nozzle with an outer diameter of 60.3 mm and a throat diameter of 25.4 mm as an example, the optimized nozzle not only enhances its impact resistance but also reduces its weight compared to existing nozzles.

[0029] Figure 3 This is a cloud map showing the distribution of steam pressure at the nozzle outlet, obtained from computer simulations of both the old and new nozzles.

[0030] Based on the outlet pressure results, the optimized nozzle, due to the elimination of the front chamber, exhibits a less uniform pressure distribution at the outlet compared to the existing nozzle. Therefore, further simulations were performed on the pressure distribution at a distance from the outlet. Figure 4 and Figure 5 .

[0031] The results show that although the pressure distribution at the nozzle exit of the optimized nozzle is not as good as that of the existing nozzle, the steam pressure becomes nearly uniform after traveling a certain distance. Meanwhile, Figure 6 A profile diagram of the steam velocity distribution at a distance of 0-0.5m from the nozzle outlet was used to optimize the nozzle. The analysis results show that the steam velocity distribution at this distance is relatively uniform.

Claims

1. A top-chamber-less, thermal shock resistant furnace sootblower nozzle, comprising a nozzle body, characterized in that, The nozzle body includes a housing (1), a housing top (2), and a nozzle (3). The nozzle axis is slightly tilted backward by 2.5-5°, and the expansion angle is 13°.

2. The top-chamberless, thermal shock resistant furnace soot blower nozzle according to claim 1, characterized in that, The wall thickness of the shell top (2) is 6~8mm.

3. The top-chamberless, thermal shock resistant furnace soot blower nozzle according to claim 1, characterized in that, The nozzle (3) employs a fluid surface to reduce stress at the nozzle tip.

4. The top-chamberless, thermal shock resistant furnace soot blower nozzle according to claim 1, characterized in that, The nozzle body has an outer diameter of 60.3 mm and a throat diameter of 25.4 mm.

5. The top-chamberless, thermal shock resistant furnace soot blower nozzle according to claim 1, characterized in that, The nozzle body is made of A297-Gr-HT or ZGCr20Ni14Si2 heat-resistant cast steel.

6. The method for optimizing a sootblower nozzle according to any of the foregoing claims, characterized in that, The pressure distribution of different dimensional parameters of the nozzle body was verified and optimized through computer simulation, and the optimal value was obtained.

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