Wide-load adjusting coal pulverizing system and method for W flame boiler

Abstract

The invention discloses a W-flame boiler wide-load adjusting coal pulverizing system which comprises a plurality of coal mills communicated with a W-flame boiler, each coal mill is provided with a plurality of coal milling outlets, each coal milling outlet is connected with a large pulverized coal pipeline, and each coal milling outlet is provided with a coal mill outlet insertion plate door. A plurality of large pulverized coal pipelines are arranged in the W flame boiler hearth, a pulverized coal distributor is further arranged at an outlet of each large pulverized coal pipeline, each pulverized coal distributor is connected with two small pulverized coal pipelines, each small pulverized coal pipeline is connected with a burner, and the small pulverized coal pipelines communicated with the coal mill are connected with the two sides of the W flame boiler hearth respectively. And the small pulverized coal pipelines on each coal mill are sequentially and alternately connected with the W flame boiler hearth one by one in the arrangement direction of the multiple coal mills. According to the method, the water cooling wall tension fracture caused by thermal load deviation can be effectively avoided, stable combustion of the whole hearth is achieved, the lowest stable combustion load without oil of low volatile coal types is smaller than 25%, and the wide load adjusting capacity of a boiler unit is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal power generating sets, and in particular relates to a wide load regulating pulverizing system and method for a W-flame boiler. Background Art

[0002] As an important part of the new power system, thermal power generating units are the best choice for achieving the dual carbon goals while ensuring safe power supply. That is, they are required to have flexible peak-shaving and high-efficiency and low-pollutant emission capabilities. The pulverizing system, as one of the core systems of thermal power coal-fired units, needs to have better wide-load regulation capabilities and coal type adaptability. Especially for W-flame boilers burning low-volatile coal, the wide-load regulation capability test is more severe.

[0003] At present, the minimum stable combustion load of conventional W-flame boilers burning low-volatile coal without oil addition is greater than 40%, and the wide load adjustment capability is poor. When the load changes, the unevenness of the combustion heat load in the width direction of the boiler can easily lead to cracking of the water-cooled wall. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a W-flame boiler wide load regulation pulverizing system and method, which can flexibly cut off the large pulverized coal pipelines of each pulverizer, optimize the air-powder uniformity of the entire furnace, make the small-power pulverized coal burners in operation state evenly distributed in the entire furnace, and evenly distribute the heat input of the entire furnace in the width direction of the furnace, which can effectively avoid the water-cooled wall cracking caused by thermal load deviation, and while cutting off some large pulverized coal pipelines, utilize the stable combustion characteristics of the small-power pulverized coal burners to achieve stable combustion of the entire furnace, and achieve a minimum stable combustion load of low-volatile coal without oil injection of less than 25%, thereby greatly improving the wide load regulation capability of the boiler unit.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] A W-flame boiler wide load regulation pulverizing system comprises a plurality of coal mills connected to the W-flame boiler, each of the coal mills having a plurality of coal mill outlets, each of the coal mill outlets being connected to a large coal powder pipeline, and a coal mill outlet plug door being provided at each of the coal mill outlets, a coal powder distributor being provided at the outlet of each of the large coal powder pipelines, each of the coal powder distributors being connected to two small coal powder pipelines, each of the small coal powder pipelines being connected to a burner, the plurality of small coal powder pipelines connected to the coal mills being connected to both sides of a W-flame boiler furnace respectively, and the small coal powder pipelines on each of the coal mills being connected to the W-flame boiler furnace one by one in sequence and alternately along the arrangement direction of the plurality of coal mills.

[0007] In one embodiment, an adjustable shrinkage hole is provided on the small pulverized coal pipeline connected to the pulverized coal distributor. Through this embodiment, the adjustable shrinkage hole is combined with the pulverized coal distributor to balance the resistance of the two small pulverized coal pipelines connected to the same pulverized coal distributor, and achieve the primary wind speed and pulverized coal concentration in the two small pulverized coal pipelines without deviation, providing each small-power pulverized coal burner with primary air and pulverized coal with optimal parameters, which is beneficial to its ignition organization, stable combustion and low nitrogen emissions.

[0008] In one embodiment, a burner front plug-in door is provided in the pulverized coal pipeline at the front end of the burner inlet. According to this embodiment, the provided burner front plug-in door can further ensure the closure of the pulverized coal pipeline.

[0009] In one embodiment, a monitoring device is also provided on the small coal powder pipeline, and the monitoring device is located between the adjustable shrinkage hole and the front plug-in plate door of the burner. Through this embodiment, the set monitoring device can provide the primary air velocity, coal powder fineness and coal powder concentration parameters of each small coal powder pipeline in real time, thereby facilitating the judgment of whether there is a deviation between the two small coal powder pipelines connected to the same coal powder distributor, so as to remind the operator to deal with it in time and make the air and powder distribution of each small coal powder pipeline as uniform as possible.

[0010] In one embodiment, the burner is a low-power burner with a power of 15 to 30 MW.

[0011] The present invention also provides a W-flame boiler wide load regulation pulverizing method, based on the above pulverizing system, comprising:

[0012] A large pulverized coal pipeline is connected to each outlet of the coal mill, and two burners are connected via a small pulverized coal pipeline on the outlet side of each large pulverized coal pipeline;

[0013] The burners connected to the coal mills are respectively arranged on both sides of the W-flame boiler furnace, and the small pulverized coal pipelines on each coal mill are alternately arranged on the W-flame boiler furnace in sequence according to the arrangement sequence of the multiple coal mills;

[0014] Wherein, a coal mill outlet plug door is arranged at each outlet of the coal mill to cut off the small coal powder pipeline connected with the outlet.

[0015] Through this implementation, the coal mill is matched with a small-power coal powder burner through multiple small coal powder pipelines, which can greatly improve the ignition stability and burnout of coal powder, prevent coking in the furnace, and reduce NO xAt the same time, multiple small pulverized coal pipelines are alternately arranged on the W-flame boiler furnace in sequence according to the arrangement sequence of the coal mills. Even under low-load conditions, such as when some coal mills are shut down and at least two coal mills are kept working, and some large pulverized coal pipelines of the working coal mills are also shut down, the remaining working burners are still evenly distributed on the front and rear walls of the W-flame boiler, and the input heat load of the entire furnace has no deviation. Combined with the stable combustion characteristics of the small-power pulverized coal burner, the lowest non-oil stable combustion load of less than 25% can be achieved for low-volatile coal, greatly improving the wide load adjustment capability of the low-volatile coal-fired boiler unit.

[0016] In one embodiment, it also includes: a pulverized coal distributor is arranged between the large pulverized coal pipeline and the small pulverized coal pipeline, one end of the pulverized coal distributor is connected to the outlet of the large pulverized coal pipeline, and the other end is connected to the inlets of the two small pulverized coal pipelines, and an adjustable shrinkage hole and a burner front plug-in plate door are sequentially arranged on the small pulverized coal pipeline.

[0017] In one embodiment, it also includes: a monitoring device is installed on the small pulverized coal pipeline between the adjustable shrinkage hole and the front plug-in door of the burner.

[0018] The beneficial effects of the present invention are:

[0019] (1) The coal mill is connected to the W-flame boiler through multiple small coal powder pipelines matched with small-power coal powder burners. At the same time, the small coal powder pipelines of multiple coal mills are alternately distributed in sequence, that is, each coal mill and the large coal powder pipeline of each coal mill can be flexibly cut off and stopped, and the air and powder uniformity of the whole furnace is optimized, so that the small-power coal powder burners in the operation state are evenly distributed in the whole furnace, and the heat input of the whole furnace is evenly distributed in the width direction of the furnace, which can effectively avoid the cracking of the water-cooled wall caused by the thermal load deviation. In the low working condition where some large coal powder pipelines are cut off, the stable combustion characteristics of the small-power coal powder burners are used to achieve stable combustion of the whole furnace, and the minimum stable combustion load of low-volatile coal without oil injection is less than 25%, which greatly improves the wide load adjustment capability of the boiler unit;

[0020] (2) The small pulverized coal pipeline is provided with an adjustable shrinkage hole and a monitoring device to balance the resistance of the two small pulverized coal pipelines connected to the same pulverized coal distributor, and to achieve no deviation in the primary wind speed and pulverized coal concentration in the two small pulverized coal pipelines, thereby providing each small-power pulverized coal burner with primary air and pulverized coal with optimal parameters, which is beneficial to its ignition organization, stable combustion and low nitrogen emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0022] Figure 1 A schematic diagram showing the structure of the flour making system of the present invention is shown;

[0023] Figure 2 A schematic diagram showing that a plurality of small pulverized coal pipelines of six coal mills are connected to the furnace of a W-flame boiler in sequence and alternately (only the pipeline of the first coal mill is shown);

[0024] Figure 3 A schematic diagram showing the pipeline arrangement structure of a coal mill in the pulverizing system of the present invention is shown;

[0025] Figure 4 A schematic diagram showing the operation of a powder making system according to an embodiment of the present invention under low load conditions;

[0026] Figure 5 A schematic diagram showing the operation of another embodiment of the pulverizing system of the present invention under low load conditions;

[0027] In the drawings, like reference numerals are used for like parts. The drawings are not necessarily to scale.

[0028] Reference numerals:

[0029] 1- coal mill, 2- large pulverized coal pipeline, 3- coal mill outlet plug door, 4- coal powder distributor, 5- adjustable shrinkage hole, 6- monitoring device, 7- small pulverized coal pipeline, 8- burner front plug door, 9- burner, 10- furnace. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] The present invention provides a W-flame boiler wide load regulation pulverizing system, such as Figures 1 to 3 As shown, it includes a plurality of coal mills 1 connected to a W-flame boiler, each coal mill 1 has a plurality of coal mill outlets, each coal mill outlet is connected to a large pulverized coal pipeline 2, and a coal mill outlet plug door 3 is provided at each coal mill outlet, a pulverized coal distributor 4 is also provided at the outlet of each large pulverized coal pipeline 2, each pulverized coal distributor 4 is connected to two small pulverized coal pipelines 7, each small pulverized coal pipeline 7 is connected to a burner 9, and the plurality of small pulverized coal pipelines 7 connected to the coal mill 1 are respectively connected to the two sides of the W-flame boiler furnace 10, and the small pulverized coal pipelines 7 on each coal mill 1 are connected to the W-flame boiler furnace 10 one by one in sequence and alternately along the arrangement direction of the plurality of coal mills 1;

[0032] It should be noted that this embodiment takes a typical 660MW grade W flame boiler pulverizing system as an example, each boiler is equipped with 6 double-inlet and double-outlet coal mills 1, and the burner 9 is a low-power burner with a power of 15 to 30MW. Figure 1 and Figure 3As shown, only the pulverized coal pipeline corresponding to one coal mill 1 is shown. Each coal mill 1 has 6 pulverized coal outlets, each of which is connected to a large pulverized coal pipeline 2. The 6 pulverized coal outlets can be arbitrarily distributed on the coal mill, and can also be as follows Figure 1 In the structure shown, the six coal pulverizing outlets are arranged symmetrically, which facilitates the routing of the small coal pulverizing pipeline 7 connected thereto, so as to be connected to the front and rear walls of the W-flame boiler respectively. Figure 2 As shown, only the pulverized coal pipeline corresponding to one coal mill 1 is shown. The small pulverized coal pipeline 7 on each coal mill 1 is connected to the W-flame boiler furnace one by one in sequence along the arrangement direction of the multiple coal mills 1, and the small pulverized coal pipeline 7 is connected to the W-flame boiler furnace through the burner 9. For example, on one side of the W-flame boiler furnace, the six coal mills are named A mill, B mill, C mill, D mill, E mill and F mill in sequence according to their arrangement direction. The first burner A1 of the A mill, the first burner B1 of the B mill, the first burner C1 of the C mill, the first burner D1 of the D mill, the first burner E1 of the E mill and the first burner F1 of the F mill are connected to the W-flame boiler furnace alternately in sequence. The flame boiler furnace 10 is connected, so that all or part of the large pulverized coal pipelines 2 and the corresponding low-power burners 9 corresponding to any coal mill 1 can be flexibly stopped under any working conditions, so that the fineness of the pulverized coal, the primary wind speed, the uniformity of the wind and pulverized coal, etc. do not deviate from the design parameters, so that the combustion uniformity in the furnace width direction is guaranteed, and the problems such as the cracking of the water-cooled wall caused by the thermal load deviation can be effectively avoided. The pulverized coal ignition and stable combustion are organized with the low-power pulverized coal burner, and then the stable combustion of the whole furnace is realized, and the minimum stable combustion load of low-volatile coal without oil injection is less than 25%, thereby greatly improving the wide load adjustment capacity of the boiler unit. At the same time, the low-power burner can also prevent coking and control the generation of nitrogen oxides;

[0033] In one embodiment, on the furnace of a W-flame boiler, two adjacent burners 9 are fitted to each other, and the two adjacent burners 9 form a group of powder supply structures, and the spacing between the two adjacent groups of powder supply structures is the same, that is, the burners 9 are evenly arranged, so that when all or part of the large pulverized coal pipelines 2 and the corresponding low-power burners 9 corresponding to any coal mill 1 are flexibly stopped under any working condition, the combustion uniformity in the furnace width direction is further ensured;

[0034] Specifically, Figure 4 and Figure 5 As shown, when put into operation under low load conditions, only two coal mills 1 can be retained, such as A mill and B mill running together, or A mill and C mill running together, or three or four coal mills 1 can be retained to run together, and some of the large pulverized coal pipelines 2 therein can be shut down, and the combustion uniformity in the furnace width direction can still be guaranteed, preventing the water-cooled wall from cracking due to thermal load deviation, greatly improving the low-load stable combustion capability of the boiler unit, and achieving a minimum stable combustion load of less than 25% for the low-volatile coal boiler unit without oil injection;

[0035] In one embodiment, Figure 1 and Figure 3 As shown, an adjustable shrinkage hole 5 is provided on the small pulverized coal pipeline 7 connected to the pulverized coal distributor 4, a burner front plug-in plate door 8 is provided in the pulverized coal pipeline at the front end of the burner 9 inlet, and a monitoring device 6 is also provided on the small pulverized coal pipeline 7, and the monitoring device 6 is located between the adjustable shrinkage hole 5 and the burner front plug-in plate door 8;

[0036] It should be noted that the small pulverized coal pipeline 7 is provided with an adjustable shrinkage hole 5 and a monitoring device 6, so that the resistance of the two small pulverized coal pipelines 7 connected to the same pulverized coal distributor 4 is balanced, and the primary wind speed and pulverized coal concentration in the two small pulverized coal pipelines 7 are achieved without deviation, and the primary wind and pulverized coal with the best parameters are provided for each small-power pulverized coal burner 9, which is conducive to its ignition organization, stable combustion and low nitrogen emission, and the pulverized coal pipeline at the front end of the burner 9 inlet is provided with a burner front plug-in door 8, that is, cooperate with the pulverizer outlet plug-in door 3, to further ensure the effect of cutting off the pulverized coal pipeline;

[0037] The present invention also provides a W-flame boiler wide load regulation pulverizing method, based on the pulverizing system provided in the above embodiment, comprising:

[0038] A large pulverized coal pipeline is connected to each outlet of the coal mill, and two burners are connected via a small pulverized coal pipeline on the outlet side of each large pulverized coal pipeline;

[0039] The burners connected to the coal mills are respectively arranged on both sides of the W-flame boiler furnace, and the small pulverized coal pipelines on each coal mill are alternately arranged on the W-flame boiler furnace in sequence according to the arrangement sequence of the multiple coal mills;

[0040] Wherein, a coal mill outlet gate is provided at each outlet of the coal mill to cut off the small coal powder pipeline connected to the outlet;

[0041] It should be noted that the outlet of the coal mill is matched with multiple low-power burners, and multiple low-power burners are alternately arranged in sequence on the furnace of the W-flame boiler, so that all or part of the large pulverized coal pipelines and their corresponding low-power burners corresponding to any coal mill can be flexibly cut off under any working conditions, so that the fineness of the pulverized coal, the primary wind speed, the uniformity of the wind and the pulverized coal, etc. do not deviate from the design parameters, so that the combustion uniformity in the furnace width direction is guaranteed, and the problems such as the cracking of the water-cooled wall caused by the thermal load deviation can be effectively avoided. The low-power pulverized coal burner is used to organize the ignition and stable combustion of the pulverized coal, and then the stable combustion of the whole furnace is realized, especially under low-load conditions, the minimum stable combustion load of low-volatile coal without oil injection is less than 25%, thereby greatly improving the wide load adjustment capacity of the boiler unit;

[0042] Furthermore, it also includes: a pulverized coal distributor is arranged between the large pulverized coal pipeline and the small pulverized coal pipeline, one end of the pulverized coal distributor is connected to the outlet of the large pulverized coal pipeline, and the other end is connected to the inlets of the two small pulverized coal pipelines, and an adjustable shrinkage hole and a burner front plug-in door are arranged in sequence on the small pulverized coal pipeline, and a monitoring device is installed on the small pulverized coal pipeline between the adjustable shrinkage hole and the burner front plug-in door;

[0043] It should be noted that the monitoring device is used to monitor the state of the pulverized coal in the small pulverized coal pipeline in real time. When the pulverized coal state in the two small pulverized coal pipelines connected to the same pulverized coal distributor deviates, the primary wind speed and pulverized coal concentration in the two small pulverized coal pipelines are adjusted to be non-deviation by adjusting the adjustable shrinkage hole, so as to provide each small-power pulverized coal burner with the primary wind and pulverized coal with the best parameters, which is beneficial to its ignition organization, stable combustion and low nitrogen emission;

[0044] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0045] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in other described embodiments.

Claims

1. A W-flame boiler wide load regulation pulverizing system, characterized in that: It comprises a plurality of coal mills connected with a W-flame boiler, each of the coal mills having a plurality of coal mill outlets, each of the coal mill outlets being connected with a large pulverized coal pipeline, and a coal mill outlet plug door being provided at each of the coal mill outlets, a coal powder distributor being provided at the outlet of each of the large pulverized coal pipelines, each of the pulverized coal distributors being connected with two small pulverized coal pipelines, each of the small pulverized coal pipelines being connected with a burner, and the plurality of small pulverized coal pipelines connected with the coal mills being connected with the two sides of the furnace of the W-flame boiler respectively, and the small pulverized coal pipelines on each of the coal mills being connected with the furnace of the W-flame boiler alternately one by one in sequence along the arrangement direction of the plurality of coal mills.

2. A W-flame boiler wide load adjustment pulverizing system according to claim 1, characterized in that: The small pulverized coal pipeline connected to the pulverized coal distributor is provided with an adjustable shrinkage hole.

3. A W-flame boiler wide load adjustment pulverizing system according to claim 2, characterized in that: A burner front plug-in door is arranged in the pulverized coal pipeline at the front end of the burner inlet.

4. A W-flame boiler wide load adjustment pulverizing system according to claim 3, characterized in that: The small pulverized coal pipeline is also provided with a monitoring device, which is located between the adjustable shrinkage hole and the burner front plug-in door.

5. A W-flame boiler wide load adjustment pulverizing system according to claim 1, characterized in that: The burner is a low-power burner with a power of 15 to 30 MW.

6. A W-flame boiler wide load regulation pulverizing method, based on the pulverizing system according to any one of claims 1 to 5, characterized in that: include: A large pulverized coal pipeline is connected to each outlet of the coal mill, and two burners are connected via a small pulverized coal pipeline on the outlet side of each large pulverized coal pipeline; The burners connected to the coal mills are respectively arranged on both sides of the W-flame boiler furnace, and the small pulverized coal pipelines on each coal mill are alternately arranged on the W-flame boiler furnace in sequence according to the arrangement sequence of the multiple coal mills; Wherein, a coal mill outlet plug door is arranged at each outlet of the coal mill to cut off the small coal powder pipeline connected with the outlet.

7. A W-flame boiler wide load regulation pulverizing method according to claim 6, characterized in that: Also includes: A pulverized coal distributor is arranged between the large pulverized coal pipeline and the small pulverized coal pipeline. One end of the pulverized coal distributor is connected to the outlet of the large pulverized coal pipeline, and the other end is connected to the inlets of the two small pulverized coal pipelines. Adjustable shrinkage holes and burner front plug-in doors are sequentially arranged on the small pulverized coal pipeline.

8. A W-flame boiler wide load regulation pulverizing method according to claim 7, characterized in that: Also includes: A monitoring device is installed on the small pulverized coal pipeline between the adjustable shrinkage hole and the front plug-in door of the burner.

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