W flame boiler coal mill and burner system and operation method
By employing a combined burner system with three sets of two coal mills each and cross-arranged in the W-flame boiler, the problem of uneven heat input in traditional W-flame boilers has been solved, achieving uniform heat input within the furnace and improving the boiler's safety and reliability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DONGFANG BOILER GROUP OF DONGFANG ELECTRIC CORP
- Filing Date
- 2026-01-29
- Publication Date
- 2026-04-24
AI Technical Summary
Traditional W-flame boilers, when shut down coal mills or when operating with an odd number of coal mills, struggle to achieve uniform heat input across the width and depth of the furnace body. This results in large temperature deviations on the heated surfaces, potentially leading to overheating, water-cooled wall cracking, and other problems that affect the safe operation of the boiler.
The system employs a combined burner system consisting of three groups of two coal mills each, symmetrically arranged and connected by pulverized coal pipelines and branch pipes. Each group of burners is cross-set on the front and rear furnace arches to achieve uniform heat input of fuel in the front-to-back direction of the furnace. The coal mills are operated in a specific sequence during boiler startup and load increase, and shut down in the reverse sequence during load reduction and shutdown to ensure uniform heat input within the furnace.
This achieves uniform heat input to the boiler in the front-to-back and left-to-right directions, reduces flue gas temperature deviation inside the furnace, reduces wall temperature deviation of the heated surfaces, and improves the boiler's operational safety and reliability.
Smart Images
Figure CN121916481A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a W-flame boiler coal mill and burner system and its operation method, and in particular to a W-flame boiler burner and pulverized coal pipeline arrangement and operation method that can achieve uniform heat input. Background Technology
[0002] W-flame boilers are suitable for efficient combustion of low-volatile coals, such as... Figure 1 As shown, its several burners 11 are arranged above the front and rear furnace arches, injecting the pulverized coal gas flow from the pulverizing system downward into the lower furnace. During the downward rushing process, the pulverized coal gas flow mixes with the combustion air and burns. The generated flue gas turns upward at a suitable position and flows out of the lower furnace. This combustion system prolongs the flame path and increases the residence time of fuel in the furnace, which is beneficial to the burnout of low volatile coal.
[0003] Traditional W-flame boiler coal mill outlet pulverized coal pipeline and burner layout as follows: Figure 2 Each coal mill's corresponding burners 12 are evenly distributed on the front and rear furnace arches. For example, the four burners A1, A2, A3, and A4 corresponding to coal mill A are staggered on the front and rear furnace arches, and the burners corresponding to each coal mill are cross-arranged on the front and rear furnace arches. This arrangement was adapted to the subcritical boilers of the past, where the medium in the heating surface had almost no temperature difference and low thermal stress, and could operate normally when the coal mills were shut down. However, most W-flame boilers are now supercritical boilers. The existing arrangement makes it difficult to achieve uniform heat input in the width and depth directions of the furnace body when the coal mills are shut down or when an odd number of coal mills are running. This results in large deviations in the wall temperature of the heating surface and large temperature differences in the medium in different locations of the heating surface. In severe cases, problems such as overheating and water-cooled wall cracking may occur, affecting the safe operation of the boiler. Summary of the Invention
[0004] The purpose of this invention is to address the above-mentioned shortcomings of the prior art by providing a W-flame boiler coal mill and burner system and its operation method. During operation, it can achieve uniform heat input in the left-right and front-back directions inside the furnace, reduce the deviation of flue gas temperature inside the furnace, and help reduce the deviation of wall temperature on the heated surface, thereby improving the safety and reliability of boiler operation.
[0005] To achieve the above objectives, the present invention provides a coal mill and burner system for a W-flame boiler, comprising three groups of two coal mills in each group and corresponding arrays of burners located on the front and rear furnace arches. Each coal mill outlet is connected to n pulverized coal pipes, where n is an even number ≥ 2. The system is characterized in that: each pulverized coal pipe is connected to two pulverized coal branch pipes via a pulverized coal distributor; each group of burners comprises 2n combined burners, each combined burner having two pulverized coal airflow channels; the 2n combined burners are divided into two groups symmetrically arranged on the front and rear furnace arches in the front-rear direction; the two pulverized coal airflow channels of the two combined burners symmetrically arranged on the front and rear furnace arches in each group are respectively connected to a pulverized coal branch pipe connected to the same pulverized coal pipe of the two coal mills in the corresponding group; the 2n combined burners of each group are arranged crosswise on the front or rear furnace arches.
[0006] This invention involves symmetrically arranging 2n combined burners in each group on the front and rear furnace arches of the furnace body. In each group, the two combined burners symmetrically arranged on the front and rear furnace arches have two pulverized coal airflow channels connected to a pulverized coal branch pipe of each of the two corresponding coal mills in the same group. Furthermore, the combined burners in each group are arranged crosswise on either the front or rear furnace arch. When any coal mill is put into operation, fuel is ejected and burned through one pulverized coal airflow channel of each of the corresponding combined burners symmetrically arranged in the front and rear furnace arches via its n pulverized coal pipes and two connected pulverized coal branch pipes. This ensures uniform heat input in the front and rear directions of the boiler under any load, reducing flue gas temperature deviation within the furnace. The combined burners also achieve balanced heat input, further reducing wall temperature deviation on the heated surfaces and improving the safety and reliability of boiler operation.
[0007] As a further improvement of the present invention, the 2n combined burners of each group of burners are divided into two groups and symmetrically arranged on the front and rear furnace arches in the furnace width direction; each combined burner corresponding to the first group of coal mills is located between the two combined burners corresponding to the second and third groups of coal mills, and each combined burner corresponding to the second group of coal mills is located outside the combined burner corresponding to the adjacent first group of coal mills in the furnace width direction; this can achieve uniform heat input in the left and right directions inside the furnace, further reducing the flue gas temperature deviation inside the furnace and reducing the wall temperature deviation of the heated surface; The present invention discloses an operation method for a W-flame boiler coal mill and burner system, characterized in that: during the boiler start-up and load increase phase: first, one coal mill in the first group of coal mills is put into operation, followed by the other coal mill in the same group; then, the second group of coal mills and the third group of coal mills are put into operation in sequence; during the boiler load decrease and shutdown phase: first, one coal mill in the third group of coal mills is shut down, followed by the other coal mill in the same group; then, the second group of coal mills and the first group of coal mills are shut down in sequence. When a W-flame boiler is running, the temperature at the center of the furnace width is higher than that on both sides. The combined burners corresponding to the first set of coal mills have better uniformity relative to the center line of the furnace width, while the combined burners corresponding to the second and third sets of coal mills are less uniform. Therefore, during the boiler startup and load increase phases, the first set of coal mills is put into operation first, followed by the second and third sets of coal mills in sequence. During the boiler load reduction and shutdown phases, they are shut down in the reverse direction. This can further reduce the deviation of flue gas temperature in the furnace and the deviation of wall temperature on the heated surfaces, thereby improving the safety and reliability of boiler operation. In summary, this invention can achieve uniform heat input in the left-right and front-back directions inside the furnace during operation, reducing flue gas temperature deviation inside the furnace, which is beneficial to reducing wall temperature deviation of the heated surface and improving the safety and reliability of boiler operation. Attached Figure Description
[0008] Figure 1 This is a schematic diagram of a traditional W-flame boiler.
[0009] Figure 2 This is a schematic diagram showing the correspondence between the pulverized coal outlet pipeline of the existing W-flame boiler coal mill and the connected burner.
[0010] Figure 3 This is a structural diagram of one set of coal mills and burners in an embodiment of the present invention.
[0011] Figure 4 This is a diagram showing the arrangement of each group of burners in an embodiment of the present invention. Detailed Implementation
[0012] The invention will be further described below with reference to the accompanying drawings.
[0013] like Figure 3 , Figure 4 As shown, this embodiment of a W-flame boiler includes a coal mill and burner system comprising three sets of two coal mills each and three sets of burners mounted on the front and rear furnace arches. Figure 3Taking the first group of coal mills 1 and 2 as an example, each coal mill 1 and 2 has four pulverized coal pipes 3 or 4 connected to its outlet. Each pulverized coal pipe 3 or 4 is connected to two pulverized coal branch pipes 6 or 7 through a pulverized coal distributor 5. The first group of burners corresponding to this group of coal mills 1 and 2 includes eight combined burners 8. Each combined burner 8 has two pulverized coal airflow channels. The eight combined burners 8 are divided into two groups and are symmetrically arranged on the front and rear furnace arches in both the front-to-back direction and the furnace width direction. The two pulverized coal airflow channels of the two combined burners 8 symmetrically arranged on the front and rear furnace arches of this group are respectively connected to the two coal mills of the corresponding group. The pulverized coal pipes 6 and 7 of the same pulverized coal pipeline of mills 1 and 2 are connected; the structure of the other two sets of pulverizers and the corresponding two sets of burners is exactly the same as that of the first set of pulverizers 1 and 2 and the first set of burners; the twenty-four combined burners 8, 9 and 10 of the three sets of burners are arranged crosswise on the front or rear furnace arch. Each combined burner 8 of the first set of pulverizers is located between the two combined burners 9 and 10 of the second and third sets of pulverizers, and each combined burner 9 of the second set of pulverizers is located outside the combined burner 8 of the adjacent first set of pulverizers in the furnace width direction. This invention achieves uniform heat input in the front and rear directions and the left and right sides of the furnace by symmetrically arranging several combined burners 8, 9, and 10 in each group of burners on the front and rear furnace arches in both the front and rear directions and the furnace width direction. Furthermore, the two pulverized coal airflow channels of the two combined burners symmetrically arranged on the front and rear furnace arches in each group are connected to a pulverized coal branch pipe of the corresponding two coal mills in the same group. The combined burners in each group are arranged crosswise on the front or rear furnace arch. When any coal mill is put into operation, fuel is ejected and burned through the pulverized coal airflow channels of the corresponding combined burners symmetrically arranged in the front and rear directions of the furnace, via its several pulverized coal pipes and two connected pulverized coal branch pipes. This ensures uniform heat input in the front and rear directions and the left and right sides of the furnace during boiler operation under any load, reducing flue gas temperature deviation in the furnace. In addition, the combined burners 8, 9, and 10 achieve balanced heat input through the two pulverized coal airflow channels, which helps reduce wall temperature deviation of the heated surfaces and improves the safety and reliability of boiler operation.
[0014] The present invention discloses an operation method for a W-flame boiler coal mill and burner system. During the boiler start-up and load increase phase: first, coal mill 1 in the first group of coal mills is put into operation, then another coal mill 2 in the same group is put into operation, followed by the second group of coal mills and the third group of coal mills in sequence, so that the corresponding combined burners 8, 9, and 10 operate in sequence; during the boiler load reduction and shutdown phase: first, one coal mill in the third group of coal mills is shut down, then another coal mill in the same group is shut down, followed by the second group of coal mills and the first group of coal mills in sequence. Because the temperature at the center of the furnace width is higher than that on both sides when the W-flame boiler is running, the combined burners 8 corresponding to the first group of coal mills have better uniformity relative to the center line of the furnace width (the combined burners 9 corresponding to the second group of coal mills are farther from the center line of the furnace width, and the combined burners 10 corresponding to the third group of coal mills are closer to the center line of the furnace width), and the combined burners 9 and 10 corresponding to the second and third groups of coal mills are less uniform. Therefore, during the boiler startup and load increase phase, the first group of coal mills is put into operation first, followed by the second and third groups of coal mills in sequence. During the boiler load decrease and shutdown phase, they are shut down in reverse order. This can further reduce the deviation of flue gas temperature in the furnace, reduce the deviation of wall temperature on the heated surface, and improve the safety and reliability of boiler operation. The above embodiments have been used to illustrate the invention, but it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments.
Claims
1. A W-flame boiler coal mill and burner system, comprising three groups of two coal mills in each group and corresponding groups of burners located on the front and rear furnace arches, wherein each coal mill outlet is connected to n pulverized coal pipes, where n is an even number ≥ 2; characterized in that: Each pulverized coal pipeline is connected to two pulverized coal branch pipes via a pulverized coal distributor. Each group of burners includes 2n combined burners. Each combined burner has two pulverized coal airflow channels. The 2n combined burners are divided into two groups and are symmetrically arranged on the front and rear furnace arches in the front-rear direction of the furnace body. The two pulverized coal airflow channels of the two combined burners symmetrically arranged on the front and rear furnace arches in each group are respectively connected to a pulverized coal branch pipe of the same pulverized coal pipeline of the two coal mills in the same group. The 2n combined burners of each group are arranged crosswise on the front or rear furnace arch.
2. The W-flame boiler coal mill and burner system as described in claim 1, characterized in that: The 2n combined burners of each group of burners are divided into two groups and symmetrically arranged on the front and rear furnace arches in the furnace width direction; each combined burner corresponding to the first group of coal mills is located between the two combined burners corresponding to the second and third groups of coal mills, and each combined burner corresponding to the second group of coal mills is located outside the combined burner corresponding to the adjacent first group of coal mills in the furnace width direction.
3. The operating method of a W-flame boiler coal mill and burner system as described in claim 2, characterized in that: During boiler startup and load ramp-up: First, start operating one coal mill in the first group of coal mills, then start operating the other coal mill in the same group, and then start operating the second and third coal mills in sequence. During boiler load ramp-down and shutdown: First, shut down one coal mill in the third group of coal mills, then shut down the other coal mill in the same group, and then shut down the second and first coal mills in sequence.