Pulverized coal pore plate screening and refining screening device

Abstract

The utility model discloses a pulverized coal pore plate screening and refining screening device, which relates to the field of stable combustion of low-load pulverized coal combustors, and comprises a coal mill, a pulverized coal pipe, a combustor, and a first pore plate and a second pore plate which are arranged in the pulverized coal pipe. The front side of the first pore plate is provided with a guide plate, and the front side of the second pore plate is provided with a backflow pipeline communicated with the coal mill; the guide plate and a bottom wall cavity of the pulverized coal pipe are connected with a negative pressure area of the Venturi jet device through a through pipeline, an inlet of the jet device is connected with a sealing air pipe, and an outlet is connected with a backflow pipeline. The device further comprises an auxiliary pipeline, a vibration device, a flow monitoring meter and the like. Through double-pore plate screening, coarse particle backflow grinding and an intelligent blockage coping mechanism, fine screening and stable conveying of pulverized coal are achieved, the combustion efficiency and low-load adaptability of the boiler are remarkably improved, and the problems that in the prior art, the screening effect is poor, and combustion is unstable are solved.

Description

Technical Field

[0001] The utility model relates to the field of stable combustion of low-load pulverized coal burners, in particular to a pulverized coal perforated plate screening and refinement screening device. Background Art

[0002] In the thermal power generation sector, stable boiler combustion is crucial for efficient energy conversion and safe unit operation. As industrial production demands greater flexibility in energy supply, boilers must frequently respond to load fluctuations. However, existing technologies present numerous bottlenecks. Firstly, when boiler load decreases, furnace thermal intensity significantly weakens, reducing the system's resilience to operating disturbances. Even minor fluctuations can trigger combustion instability, and in severe cases, even boiler flameout, significantly impacting energy supply continuity and production safety. Secondly, pulverized coal quality plays a crucial role in combustion stability. Currently, the commonly used variable frequency separators in coal mills have limitations in pulverized coal screening, making it difficult to accurately separate coarse and fine particles. This results in a large amount of larger pulverized coal entering the burner directly. This coarse pulverized coal is difficult to burn fully under low-load conditions, leading to flame flickering and low combustion efficiency. Furthermore, traditional pulverized coal conveying systems lack effective blockage warning and emergency response mechanisms, resulting in frequent pulverized coal accumulation and blockages. This not only reduces equipment efficiency but also increases maintenance costs and the risk of downtime. Therefore, developing a screening device that can adapt to changes in operating conditions, achieve fine screening of coal powder, and have intelligent blockage response functions has become an urgent need to improve boiler combustion stability and energy utilization efficiency. Utility Model Content

[0003] The purpose of this utility model is to provide a coal powder orifice plate screening and refinement screening device.

[0004] To achieve the above objectives, the present invention provides the following technical solutions:

[0005] A pulverized coal orifice plate screening and refining device comprises a coal mill connected to a pulverized coal pipe, which is connected to a burner. The device is characterized in that a first orifice plate and a second orifice plate are provided in the pulverized coal pipe, and the first orifice plate and the second orifice plate are both inclined, and the inclination directions are mirror-symmetrical.

[0006] A guide plate is provided on the inner bottom wall of the pulverized coal pipe on the front side of the first orifice plate and is inclined toward the first orifice plate. A return pipe is provided on the bottom wall of the pulverized coal pipe on the front side of the second orifice plate, and the return pipe is connected to the coal mill.

[0007] The guide plate and the bottom wall of the pulverized coal pipe form a cavity, and a through pipe is arranged in the cavity. The through pipe is connected to the negative pressure zone in the middle of the venturi ejector. The inlet pipe of the venturi ejector is connected to the sealed air duct, and the outlet pipe is connected to the return pipe, and its outlet pipe faces the coal mill.

[0008] An auxiliary pipeline is provided at the upper end of the front side of the first orifice plate, and the auxiliary pipeline passes through to the rear side of the second orifice plate. Sealing clamps are provided at the front and rear through-openings of the auxiliary pipeline.

[0009] The first orifice plate and the second orifice plate are extended to the outside of the pulverized coal pipe, and the extended parts are suitable for mounting a vibration device.

[0010] The first orifice plate and the second orifice plate have an inclination angle of 60 to 75 degrees.

[0011] A rubber ring is provided for sealing at the intersection of the first orifice plate, the second orifice plate and the pulverized coal pipe.

[0012] A flow monitor is provided in the pulverized coal pipe between the second orifice plate and the burner.

[0013] The diameter of the second orifice plate hole is smaller than the diameter of the first orifice plate hole.

[0014] The specific working mechanism is as follows: After being ground by the pulverized coal mill, it is transported through the pulverized coal pipe and passes through the first and second orifice plates, which are inclined in opposite directions. A guide plate in front of the first orifice plate is tilted to receive the falling pulverized coal, directing coarse particles to the first orifice plate while allowing fine particles to pass smoothly. Coarse particles that fail to pass through the first orifice plate slide down the plate and fall into the cavity formed by the guide plate and the bottom wall of the pulverized coal pipe. At this point, the Venturi ejector plays a key role. Its inlet is connected to the sealed air duct, which uses the sealed air to generate suction in the central negative pressure zone. The coarse pulverized coal particles in the cavity are sucked in through the through-duct and then sent into the return duct through the outlet duct. The outlet duct faces the pulverizer, generating return air, and ultimately returns to the pulverizer for re-grinding.

[0015] The pulverized coal that passes the first orifice plate continues on its way to a second orifice plate for further screening. Any coarse particles that fail to pass through the orifice plate are also returned through the return pipe for grinding. The qualified pulverized coal that passes through the second orifice plate is directly delivered to the burner. Furthermore, during operation of the orifice plate screening and refining system, a flow meter monitors the pulverized coal flow between the second orifice plate and the burner in real time. If the flow meter detects a sudden drop in the pulverized coal flow rate or falls below a preset threshold, indicating a blockage, the system triggers an emergency mechanism in the auxiliary pipeline.

[0016] At this point, the sealing plates at the front and rear openings of the auxiliary pipe automatically open, freeing the previously sealed auxiliary pipe. One end of this pipe connects to the front of the first orifice plate, and the other runs directly to the back of the second orifice plate, creating a diversion path to the blockage. Pulverized coal accumulated upstream of the blockage can bypass the obstruction through the auxiliary pipe and be transported directly downstream, effectively alleviating the blockage pressure and maintaining continuous coal delivery.

[0017] At the same time, the vibration device extending from the outer part of the pulverized coal pipe of the first and second orifice plates will increase the vibration frequency and amplitude after detecting the blockage signal, and perform high-frequency vibration on the orifice plate to cause the pulverized coal particles attached to the sieve holes to fall off, and cooperate with the diversion of the auxiliary pipeline to further clear the blockage. After the flow monitor detects that the flow has returned to normal, the sealing card is reclosed, the auxiliary pipeline stops working, and the device returns to the normal screening mode to ensure that the burner can stably obtain pulverized coal of qualified particle size. The rubber ring seal at the intersection of the orifice plate and the pulverized coal pipe, as well as the flow monitor between the second orifice plate and the burner, ensure the sealing of the device and the stability of the pulverized coal flow, ensuring the efficient operation of the entire system.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] Precision screening improves combustion quality: To address the poor screening performance of conventional coal mill variable frequency separators, this new system utilizes dual orifice plates with opposite inclinations, combined with a guide plate, Venturi ejector, and return duct. This achieves two stages of fine coal screening and automatic reflux grinding of coarse particles. Compared to conventional technologies, this system provides more precise control of coal particle size, avoiding flame flickering caused by overly coarse coal. This results in more uniform and finer coal particles fed into the burner, significantly improving combustion efficiency and stability.

[0020] Enhanced boiler adaptability at low loads: When boiler load decreases and furnace heat intensity weakens, even minor disturbances can easily lead to unstable combustion or even flameout under traditional technologies. This new utility model utilizes a stable pulverized coal screening and delivery mechanism to continuously supply the burner with pulverized coal of acceptable particle size, reducing the impact of pulverized coal quality issues on combustion conditions. Furthermore, an intelligent feedback control system automatically adjusts the pulverizer grinding speed based on load changes, working in conjunction with the flow monitor to ensure stable pulverized coal flow. This enhances the boiler's resistance to disturbances under low-load conditions, effectively preventing unstable combustion and flameout.

[0021] Stable powder supply ensures combustion conditions: To address the problem of uneven powder supply, the design of the auxiliary pipeline and sealing card in the utility model can quickly open the diversion branch when the coal powder transportation is abnormal, thereby maintaining a stable coal powder flow rate; the vibration device, Venturi ejector and other components work together to prevent pipeline blockage and coal powder accumulation, ensuring that the coal powder is evenly and continuously delivered to the burner, avoiding flame flickering caused by uneven powder supply, and stabilizing the combustion conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This utility model is a pulverized coal perforated plate screening and refining screening device;

[0023] In the figure: 1. Coal mill; 2. Pulverized coal pipe; 21. Through pipe; 31. First orifice plate; 32. Second orifice plate; 33. Vibration device; 4. Guide plate; 5. Venturi ejector; 6. Return pipe; 8. Auxiliary pipe; 81. Sealing card; 9. Flow monitor. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be fully described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0025] like Figure 1 As shown, a pulverized coal perforated plate screening and refining device includes a coal mill 1, the coal mill 1 is connected to a pulverized coal pipe 2, and the pulverized coal pipe 2 is connected to a burner. The device is characterized in that a first perforated plate 31 and a second perforated plate 32 are provided in the pulverized coal pipe 2, and the first perforated plate 31 and the second perforated plate 32 are both inclined, and the inclination directions are mirror-symmetrical;

[0026] A guide plate 4 is provided on the inner bottom wall of the pulverized coal pipe 2 in front of the first orifice plate 31 and is inclined toward the first orifice plate 31. A return pipe 6 is provided on the bottom wall of the pulverized coal pipe 2 in front of the second orifice plate 32 and is connected to the coal mill 1.

[0027] The guide plate 4 and the bottom wall of the pulverized coal pipe 2 form a cavity, in which a through pipe 21 is arranged. The through pipe 21 is connected to the negative pressure zone in the middle of the venturi ejector 5. The inlet pipe of the venturi ejector 5 is connected to the sealed air duct, and the outlet pipe is connected to the return pipe 6, and its outlet pipe faces the coal mill 1.

[0028] An auxiliary pipe 8 is provided at the upper front end of the first orifice plate 31 , and the auxiliary pipe 8 passes through to the rear side of the second orifice plate 32 . Sealing clamps 81 are provided at both the front and rear through-openings of the auxiliary pipe 8 .

[0029] The first orifice plate 31 and the second orifice plate 32 are extended to the outside of the pulverized coal pipe 2 , and the extended portions are adapted to be fitted with a vibration device 33 .

[0030] The first orifice plate 31 and the second orifice plate 32 have an inclination angle of 60 to 75 degrees.

[0031] Rubber rings are provided for sealing at the intersections of the first orifice plate 31 , the second orifice plate 32 and the pulverized coal pipe 2 .

[0032] A flow rate monitoring meter 9 is provided in the pulverized coal pipe 2 between the second orifice plate 32 and the burner.

[0033] The diameter of the holes of the second orifice plate 32 is smaller than the diameter of the holes of the first orifice plate 31 .

[0034] The specific embodiment of the present invention is as follows: After the coal mill 1 grinds the raw coal into pulverized coal, heated primary air is fed into the pulverized coal pipe 2 for transportation. The pulverized coal first passes through an inclined first orifice plate 31. A guide plate 4 on its front side guides the pulverized coal toward the orifice plate. Coarse particles, which are too large to pass through, slide along the guide plate into a cavity formed by the bottom wall of the pulverized coal pipe. The venturi ejector 5 uses the negative pressure generated by the sealed air to draw the coarse particles in the cavity through the through-duct 21 and into the return duct 6. The air outlet of the venturi ejector 5 enters the return duct 6, generating return air, which returns the coarse particles to the coal mill 1 for re-grinding. The coal that passes through the first orifice plate 31 continues to move forward and is screened again at the second orifice plate 32, which is inclined in the opposite direction. The coarse particles that fail to pass through the return duct 6 also pass through the return duct 6, and then through the air outlet of the venturi ejector 5 into the return duct 6, generating return air, which returns the coarse particles to the coal mill 1 for re-grinding. The qualified pulverized coal is then smoothly transported to the burner. During operation, the flow monitor 9 monitors the coal powder flow in real time. When blockage is detected, the sealing card plates 81 before and after the auxiliary pipe 8 are automatically opened to provide a diversion branch for the blockage. At the same time, the vibration device 33 on the first orifice plate 31 and the second orifice plate 32 increases the vibration frequency to promote the fall of the sieve blockage, and cooperates with the Venturi ejector 5 to enhance the negative pressure powder extraction capacity and quickly clear the blocked area. After the flow returns to normal, the sealing card plate 81 is closed again and the device resumes normal operation. The entire process is achieved through the coordinated operation of various components to achieve fine screening and stable transportation of coal powder.

Claims

1. A pulverized coal perforated plate screening and refining device, comprising a coal mill (1), the coal mill (1) being connected to a pulverized coal pipe (2), the pulverized coal pipe (2) being connected to a burner, characterized in that: A first orifice plate (31) and a second orifice plate (32) are provided in the pulverized coal pipe (2); the first orifice plate (31) and the second orifice plate (32) are both in an inclined state, and the inclination directions are mirror-symmetrical; A guide plate (4) is provided on the inner bottom wall of the pulverized coal pipe (2) on the front side of the first orifice plate (31), and the guide plate (4) is inclined toward the first orifice plate (31). The bottom wall of the pulverized coal pipe (2) on the front side of the second orifice plate (32) is connected to a return pipe (6), and the return pipe (6) is connected to the coal mill (1). The guide plate (4) and the bottom wall of the pulverized coal pipe (2) form a cavity, a through pipe (21) is provided in the cavity, the through pipe (21) is connected to the negative pressure zone in the middle of the venturi ejector (5), the inlet pipe of the venturi ejector (5) is connected to the sealed air duct, the outlet pipe is connected to the return pipe (6), and the outlet pipe faces the coal mill (1).

2. A pulverized coal perforated plate screening and refining device according to claim 1, characterized in that: An auxiliary pipe (8) is provided at the upper end of the front side of the first orifice plate (31), and the auxiliary pipe (8) passes through to the rear side of the second orifice plate (32). Sealing clamps (81) are provided at the front and rear through-openings of the auxiliary pipe (8).

3. The pulverized coal perforated plate screening and refining device according to claim 1, characterized in that: The first orifice plate (31) and the second orifice plate (32) are extended to the outside of the pulverized coal pipe (2), and the extended portion is fitted with a vibration device (33).

4. The pulverized coal perforated plate screening and refining device according to claim 1, characterized in that: The first orifice plate (31) and the second orifice plate (32) have an inclination angle of 60 to 75 degrees.

5. The pulverized coal perforated plate screening and refining device according to claim 1, characterized in that: A rubber ring seal is provided at the intersection of the first orifice plate (31), the second orifice plate (32) and the pulverized coal pipe (2).

6. The pulverized coal perforated plate screening and refining device according to claim 1, characterized in that: A flow rate monitor (9) is provided in the pulverized coal pipe (2) between the second orifice plate (32) and the burner.

7. The pulverized coal perforated plate screening and refining device according to claim 1, characterized in that: The diameter of the holes of the second orifice plate (32) is smaller than the diameter of the holes of the first orifice plate (31).

Images