Device for improving pulverized coal distribution uniformity of opposed firing boiler pulverizing system

Abstract

The utility model discloses a device for improving pulverized coal distribution uniformity of a pulverizing system of an opposed firing boiler. The device is suitable for a 1000 MW grade coal-fired generator set with a horizontal elbow adopted as a pulverized coal conveying pipeline in front of a pulverized coal equally-distributing device. Comprising a horizontal pulverized coal pipeline and an elbow, an inlet of the elbow is connected with the horizontal pulverized coal pipeline, the air volume control device is arranged at an outlet of the elbow in the circumferential direction, a plurality of jet orifices are distributed in the air volume control device, all the jet orifices face the interior of the elbow, and all the jet orifices are obliquely arranged. An existing primary air or compressed air system is used for jetting at the outlet of the pipeline elbow through the jet orifice, the jetted gas forms tangent circle rotation at the center of the pipeline, stirring and mixing and disturbance of fluid at the outlet of the elbow are enhanced, and therefore the uniformity of pulverized coal distribution is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of safe operation of ultra-supercritical opposed combustion boilers, and in particular to a device for improving the uniformity of coal powder distribution. Background Art

[0002] In the context of carbon peak and carbon neutrality, coal-fired power units will play the role of "ballast stone" of the power system for a long time. Large-capacity thermal power units have outstanding economic benefits, high power generation efficiency, advanced technology, and are cleaner and more environmentally friendly, so they account for an important proportion of newly built coal-fired power units.

[0003] Boiler bias is a problem that is prone to occur in newly built large-capacity boilers. This problem will lead to deviations in boiler outlet flue gas temperature, main reheat steam, overheating of one-side water-cooled wall and steam, and excessive cooling water volume, affecting the economic operation of the unit. Long-term biased boiler burning may cause water-cooled wall cracking, superheater overheating and tube bursting, etc., which will bring major safety hazards and affect the safe operation of the boiler. The problem of pulverized coal burning is mainly investigated and treated from the two aspects of uneven air volume and pulverized coal volume.

[0004] For the ultra-supercritical opposed-combustion boiler equipped with a 1000 MW coal-fired power generation unit, the pulverizing system has a large coal powder conveying volume, and a coal powder distributor is required to distribute the coal powder that is about to enter the furnace. However, due to the influence of the coal powder distributor effect, the powder pipe elbow and the layout of the coal powder distributor, the coal powder concentration distribution uniformity in the pipeline in front of the coal powder distributor is not good. The poor balancing effect of the coal powder distributor leads to uneven powder distribution, causing the problem of biased burning of the boiler.

[0005] In response to the above problems, we designed an economical, efficient and low-cost device to improve the uniformity of coal powder distribution in the pulverizing system of the hedge combustion boiler, so as to ensure the equal distribution effect of the coal powder distributor, which can effectively solve the problem of uneven powder amount. Utility Model Content

[0006] The purpose of the utility model is to overcome the above-mentioned deficiencies in the prior art and to provide a device for improving the uniformity of coal powder distribution in a pulverizing system of a counter-firing boiler, so as to meet the demand of existing 1000MW-class units for achieving uniform distribution of coal powder in a smaller space.

[0007] The technical solution adopted by the utility model to solve the above-mentioned problem is: a device for improving the uniformity of coal powder distribution in the pulverizing system of a counter-combustion boiler, comprising a horizontal coal powder pipeline and an elbow, wherein the inlet of the elbow is connected to the horizontal coal powder pipeline, and is characterized in that it also comprises an air volume control device, wherein the air volume control device is circumferentially arranged at the outlet of the elbow, and a plurality of injection ports are distributed on the air volume control device, wherein the injection ports are all directed toward the inside of the elbow, and the injection ports are all inclined, and the inclination angle of the injection ports is 5°-15°.

[0008] In actual application, coal powder enters the elbow after passing through the horizontal coal powder pipeline. At the elbow, the coal powder tilts to one side of the pipeline due to inertia, resulting in uneven distribution of coal powder on the left and right sides of the elbow outlet. The air volume control device is placed at the elbow outlet, and the injection ports are arranged symmetrically at four points in the elbow powder pipe cross section. Each injection port sprays air toward the opposite injection port, and the injection angle has a certain inclination angle with the line connecting the injection port and the center of the pipeline, so that the air sprayed from the injection port converges at the center of the pipeline to form a tangent circle, and then forms a vortex, which achieves the mixing effect on the coal powder in the pipeline, thereby improving the uniformity of the coal powder in the pipeline.

[0009] The air volume control device is connected to the original primary air velocity sensor in the power plant to obtain the outlet velocity of the primary air, and then control the gas velocity at the outlet of the injection port to correspond to the primary air velocity in the pipeline to avoid excessive injection of gas and interference with the primary air. The total air intake of the injection port accounts for 10-15% of the primary air intake.

[0010] The air volume control device can be connected to the preheating device, which is placed in the air preheater, or directly obtains hot primary air from the air preheater to reduce the temperature difference loss caused by the mismatch between the injection port and the primary air temperature in the tube, while reducing the additional energy demand caused by preheating and reducing the complexity of the system. The uniform air inlet temperature of the injection port is controlled between 50-100℃.

[0011] Under normal operation, the device for uniform distribution of pulverized coal adopts the method of improving the flow field, using the mixing effect of the flow field to enhance the uniformity of pulverized coal distribution. The pipe lining near the device is recommended to use wear-resistant materials such as silicon carbide ceramics, which can effectively deal with the corrosion of pulverized coal and wind on the pipe wall. The air source of the injection port is the factory compressed air, primary air bypass, etc., and the nearest air source is selected as much as possible to reduce the complexity of the system and reduce expenses.

[0012] There is a certain inclination angle between the injection angle and the line connecting the injection port and the center of the pipe. The recommended angle is 5-15° and is distributed consistently along the circumference. Too large an inclination angle will cause the tangent circle to scour the pipe wall, aggravating the wear of the pipe wall. Too small an inclination angle will result in an unclear mixing effect. To ensure the tangent circle injection effect, the injection ports are set to an even number and are evenly distributed around the circumference. The nozzles of the injection ports are made of 316 stainless steel or above to ensure that the nozzles are wear-resistant and corrosion-resistant.

[0013] Compared with the prior art, the utility model has the following advantages and effects: the utility model has reasonable design, simple structure, and is easy to integrate with the existing system, which can minimize the changes to the existing system, can reduce the impact of uneven distribution of coal powder at the elbow, and achieve efficient equal distribution of coal powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a front view structural schematic diagram of the utility model.

[0015] Figure 2 It is a side structural schematic diagram of the utility model.

[0016] Figure 3 It is a schematic diagram of the airflow direction in the utility model.

[0017] In the figure: horizontal pulverized coal pipeline 1, elbow 2, air volume control device 3, injection port 4. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are provided to explain the present invention, but the present invention is not limited to the following examples.

[0019] Example

[0020] See also Figures 1 to 3 In this embodiment, there is an elbow pipeline in front of the coal powder equalizer of a 1000 MW coal-fired power plant, and the coal powder passes through the horizontal coal powder pipeline 1 and enters the elbow 2. At the elbow 2, the coal powder tilts to one side of the pipeline due to inertia, resulting in uneven distribution of the coal powder on the left and right sides at the outlet of the elbow 2.

[0021] In view of this situation, a device is designed to improve the uniformity of coal powder distribution in the pulverizing system of a counter-firing boiler, comprising a horizontal coal powder pipeline 1 and an elbow 2, wherein the inlet of the elbow 2 is connected to the horizontal coal powder pipeline 1, and also comprising an air volume control device 3, wherein the air volume control device 3 is circumferentially arranged at the outlet of the elbow 2, and a plurality of injection ports 4 are distributed on the air volume control device 3, wherein the injection ports 4 are all directed toward the inside of the elbow 2, and the injection ports 4 are all inclined, and the inclination angle of the injection ports 4 is 5°-15°.

[0022] After the factory compressed air reaches a certain temperature after passing through the preheating device, it enters the air volume control device 3, is evenly distributed to the injection port 4, and enters the coal powder pipeline to achieve an even distribution of coal powder. The temperature sensor and the flow sensor are respectively connected to the air volume control device 3. When the temperature of the compressed air entering the pipeline is higher than the primary air and powder temperature in the pipe, the output of the preheating device is reduced to reduce the temperature of the compressed air entering the powder pipe, and vice versa. When the flow rate of the main powder pipe is reduced, the flow rate of the compressed air entering the air volume control device 3 is reduced, and then the compressed air ejected from the injection port 4 is reduced, so as to achieve a uniformity improvement effect and match the air and powder flow rate of the main pipeline.

[0023] After passing through the horizontal coal powder pipeline 1, the coal powder enters the elbow 2. The air volume control device 3 is placed at the outlet of the elbow 2, and four identical injection ports 4 are evenly arranged on the four sides. Each injection port 4 sprays air toward the injection port 4 opposite to it. There is a certain inclination angle between the two injection ports 4 facing each other, so that the air sprayed by the four injection ports 4 forms a tangent circle at the center of the pipeline, and then forms a vortex, which achieves the mixing effect on the coal powder in the pipeline, thereby improving the uniformity of the coal powder in the pipeline. The radius of the tangent circle is controlled by controlling the angle of the injection port 4. By cutting the circle, the uniformity of the coal powder at the outlet of the elbow 2 is effectively improved, and the uniformity of the coal powder concentration at the outlet of the equalizer is ensured, thereby alleviating the problem of biased burning of the boiler.

[0024] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0025] In addition, it should be noted that the above content described in this specification is only an example of the structure of the utility model. All equivalent changes made based on the structure, features and principles described in the utility model patent are included in the protection scope of the utility model patent. Technicians in the technical field of the utility model can make various modifications, supplements or replace the specific embodiments described in a similar manner, as long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the protection scope of the utility model.

Claims

1. A device for improving the uniformity of pulverized coal distribution in a pulverizing system of an opposed-firing boiler, comprising a horizontal pulverized coal pipeline (1) and an elbow (2), wherein the inlet of the elbow (2) is connected to the horizontal pulverized coal pipeline (1), and wherein: The invention also comprises an air volume control device (3), the air volume control device (3) being arranged circumferentially at the outlet of the elbow (2), the air volume control device (3) being provided with a plurality of injection ports (4), the injection ports (4) all facing the inside of the elbow (2), the injection ports (4) being arranged at an angle, and the angle between the injection angle of the injection ports (4) and the line connecting the center of the cross section of the elbow (2) outlet is 5°-15°.

2. The device for improving the uniformity of pulverized coal distribution in a pulverizing system of an opposed-firing boiler according to claim 1 is characterized in that: The inner lining material of the air volume control device (3) is silicon carbide ceramic.

3. The device for improving the uniformity of pulverized coal distribution in a pulverizing system of an opposed-firing boiler according to claim 1 is characterized in that: The nozzle of the injection port (4) is made of 316 stainless steel.

4. The device for improving the uniformity of pulverized coal distribution in a pulverizing system of an opposed-firing boiler according to claim 1 or 3, characterized in that: The injection ports (4) are arranged in an even number, and the injection ports (4) are evenly distributed around the circumference.

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