Flexible hybrid pulverized coal supply system based on online monitoring of coal flow and quality

Abstract

The present invention relates to a flexible mixed pulverized coal supply system based on online monitoring of coal flow and coal quality, comprising a coal mill, a burner, a primary air fan, a primary separator, a secondary separator, a clean coal hopper, an air-powder mixer and an exhaust air fan, wherein the coal mill is connected to the primary separator, the primary separator is connected to the burner through a first channel, the discharge port of the primary separator is sequentially connected to the secondary separator, the clean coal hopper, the air-powder mixer and the burner through a second channel, the coal inlet of the coal mill is connected to a coal conveying system, the primary air fan is respectively connected to the coal mill and the air-powder mixer through pipelines, the exhaust gas outlet of the secondary separator is connected to the air inlet of the exhaust air fan, and the air outlet of the exhaust air fan is respectively connected to the coal mill, the air-powder mixer and the second channel pipe section before the burner and the burner through pipelines. Advantages: can reduce the matching time difference between the coal mill and the burner; faster response speed to the instability of the low-load combustion furnace fire of the boiler; faster response speed to the peak load regulation of the boiler.

Description

Technical Field

[0001] The invention relates to the field of coal-fired power generation, and in particular to a flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality. Background Art

[0002] Wind power, solar energy and other new energy sources with high volatility and prominent indirectness have been connected to the grid for a large scale, and the proportion of new energy power sources in the power grid has increased significantly, and the problem of unstable load in the power grid has become prominent. Coal-fired power generation is currently the only flexible resource that can achieve large-scale economic deep and rapid peak regulation. It is the ballast stone and regulator of the stability of the power grid. Significantly improving the flexibility of coal-fired generating units is an urgent need for new energy hybrid power grids.

[0003] The flexibility of coal-fired power units requires stable combustion of the boiler at low load and rapid dynamic response combustion of the boiler under variable load. From the coal yard to the boiler, coal undergoes processes such as loading, mixing, and combustion. The fuel system undergoes a long period of 7 days and 8 hours and the instantaneous combustion in the furnace is only 10 seconds, which makes it difficult to match the fuel system and the combustion system in time and space. In particular, the pulverized coal supply system's pulverizer output adjustment rate and the burner load adjustment rate cannot be accurately matched, which seriously restricts the flexibility of the boiler. It can be seen that the key to improving the flexibility of coal-fired power units lies in improving fuel flexibility and operational flexibility. Therefore, starting from the fuel system, on the basis of accurate online identification of the type and characteristics of the coal entering the furnace, through the design of a hybrid pulverized coal supply system, the pulverized coal supply system can be quickly responded to the load changes of the burner under peak-shaving conditions, thereby improving the operational flexibility of coal-fired boilers and comprehensively improving the peak-shaving and new energy consumption capabilities of coal-fired power units. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a flexible hybrid coal powder supply system based on online monitoring of coal flow and coal quality, which effectively overcomes the defects of the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality, comprising a coal mill, a burner, a primary fan, a primary separator, a secondary separator, a clean coal hopper, an air-powder mixer and an exhaust gas fan, wherein the coal outlet of the coal mill is connected to the primary separator, the material outlet of the primary separator is connected to the burner through a first channel, the material outlet of the primary separator is sequentially connected to the secondary separator, the clean coal hopper, the air-powder mixer and the burner through a second channel, the coal inlet of the coal mill is connected to a coal conveying system, the primary fan is respectively connected to the coal mill and the air-powder mixer through pipelines, the exhaust gas outlet of the secondary separator is connected to the air inlet of the exhaust gas fan, the air outlet of the exhaust gas fan is respectively connected to the coal mill, the air-powder mixer and the second channel pipe section before the burner and the burner through pipelines, the coal conveying system is provided with a coal flow monitor, and an online coal quality monitor is provided at the outlet of the primary separator.

[0007] Based on the above technical solution, the present invention can also be improved as follows.

[0008] Furthermore, a first electric damper and a second electric damper are respectively provided on the pipe sections of the first channel and the second channel connecting to the secondary separator.

[0009] Furthermore, a third electric damper and an electric regulating damper are sequentially provided on the pipeline connecting the primary fan and the air-powder mixer.

[0010] Furthermore, an electric baffle for controlling the discharge of coal powder is provided at the outlet of the clean coal hopper.

[0011] Furthermore, the coal conveying system includes a coal feeder and a conveyor belt, the discharge port of the coal feeder is located above the feed end of the conveyor belt, the discharge end of the conveyor belt is used to convey coal to the coal mill, and the coal flow monitor is arranged on the side of the conveyor belt.

[0012] The beneficial effects of the present invention are: it can reduce the matching time difference between the coal mill and the burner, realize the rapid response of the coal powder supply system output to the burner load change, and improve the boiler load rise and fall rate; it has a faster response speed to the instability of the boiler low-load combustion furnace fire; it has a faster response speed to the boiler peak regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a structural schematic diagram of a flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality of the present invention;

[0014] Figure 2 Schematic diagram of the flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality of the present invention during operation Figure 1 ;

[0015] Figure 3 Schematic diagram of the flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality of the present invention during operation Figure 2 ;

[0016] Figure 4 This is a principle system diagram of the application of the flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality in a 300MW coal-fired unit.

[0017] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0018] 1. Coal mill; 2. Burner; 3. Primary fan; 4. Primary separator; 5. Secondary separator; 6. Clean coal hopper; 7. Air-powder mixer; 8. Exhaust air fan; 9. Coal conveying system; 31. Third electric damper; 32. Electric regulating damper; 51. First electric damper; 52. Second electric damper; 61. Electric baffle; 91. Coal feeder; 92. Conveyor belt; 93. Coal flow monitor. DETAILED DESCRIPTION

[0019] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0020] Example 1

[0021] The embodiment of the present invention proposes a flexible hybrid coal powder supply system based on online monitoring of coal flow and coal quality, the system structure includes a coal mill 1, a burner 2, a primary air fan 3, a primary separator 4, A secondary separator 5, a clean coal hopper 6, an air-powder mixer 7 and an exhaust gas fan 8, the coal outlet of the above-mentioned coal mill 1 is connected to the above-mentioned primary separator 4, the discharge port of the above-mentioned primary separator 4 is connected to the above-mentioned burner 2 through a first channel, the discharge port of the above-mentioned primary separator 4 is connected to the above-mentioned secondary separator 5, the clean coal hopper 6, the air-powder mixer 7 and the burner 2 in sequence through a second channel, the coal inlet of the above-mentioned coal mill 1 is connected to a coal conveying system 9, the above-mentioned primary fan 3 is connected to the above-mentioned coal mill 1 and the air-powder mixer 7 through pipelines, the exhaust gas outlet of the above-mentioned secondary separator 5 is connected to the air inlet of the above-mentioned exhaust gas fan 8, the air outlet of the above-mentioned exhaust gas fan 8 is connected to the above-mentioned coal mill 1, the above-mentioned air-powder mixer 7 and the second channel pipe section before the burner 2 and the above-mentioned burner 2 through pipelines, the above-mentioned coal conveying system 9 is provided with a coal flow monitor 93, and a coal quality online monitor (denoted by a in the figure) is provided at the outlet of the above-mentioned primary separator 4.

[0022] like Figure 1 As shown, when the boiler is running stably with basic load, the first channel is kept unobstructed, the second channel is closed, and the pulverized coal enters the burner 2 through the first channel.

[0023] More specifically, a first electric damper 51 and a second electric damper 52 are respectively provided on the pipe sections connecting the first channel and the second channel to the secondary separator 5. The first channel is unobstructed by normally opening the first electric damper 51, and the second channel is closed by closing the second electric damper 52.

[0024] Example 2

[0025] Different from Example 1, Figure 1 As shown, in this embodiment, when the coal flow and coal quality monitoring finds that the coal transported in the coal transport system 9 is low-moisture, high-volatile, and easy-to-ignite bituminous coal, the first channel is kept unobstructed (that is, the first electric damper 51 is always open), the second channel is also kept unobstructed (that is, the second electric damper 52 is always open), and the pipeline between the primary fan 3 and the air-powder mixer 7 is closed, and the discharge port of the clean coal hopper 6 is closed (that is, the pipeline between the clean coal hopper 6 and the air-powder mixer 7 is disconnected). At the same time, the pipeline between the air outlet of the exhaust gas fan 8 and the coal mill 1 is kept unobstructed, and the second channel enters the pulverizing operation mode. At this time, a part of the coal powder enters the burner 2 through the first channel, and a part of the coal powder enters the clean coal hopper 6 through the second channel for storage, and the exhaust gas of the secondary separator 5 is introduced into the coal mill 1 through the exhaust gas fan 8 for recirculation, so as to increase the ventilation volume of the coal mill 1.

[0026] More specifically, a third electric damper 31 is provided on the pipeline between the primary fan 3 and the air-powder mixer 7 , and the pipeline between the primary fan 3 and the air-powder mixer 7 is closed by closing the third electric damper 31 .

[0027] More specifically, an electric damper 61 is provided at the discharge port of the clean coal hopper 6 , and the opening and closing of the discharge port pipeline of the clean coal hopper 6 is controlled by the opening and closing of the electric damper 61 .

[0028] It should be noted that: in the mixed pulverized coal supply system of this embodiment, a coal flow monitor 93 is set at the coal conveyor belt in front of the coal feeder, and a coal quality online measuring device is set on the outlet pulverized coal pipeline of the coal mill 1, so as to form a two-level online real-time monitoring of the coal flow and coal quality entering the furnace. The coal flow monitor 93 refers to the rapid identification of the raw coal entering the coal feeder through radio frequency tags and database technology, and the acquisition of real-time coal type, coal quality, and coal quantity data. The coal quality online measuring device refers to the non-destructive and rapid determination of the real-time industrial analysis, elemental analysis, calorific value and other combustion characteristic data of the pulverized coal at the outlet of the coal mill 1 through spectral technologies such as Raman spectroscopy, laser induced breakdown spectroscopy or near infrared spectroscopy. Based on the real-time data on the type and combustion characteristics of the coal entering the furnace, the intelligent switching of the coal flow channel and the active screening and regulation of the coal flow entering the furnace are realized. When it is found that the coal quality transported by the coal conveying system 9 is good, it is sent to the fine powder hopper 6 for storage. When the coal quality is inferior coal, it is directly sent to the burner 2 through the first channel.

[0029] Example 3

[0030] Different from Example 1, Figure 1 As shown, in this embodiment, when the boiler is unloaded, the first channel and the second channel are both kept unobstructed, the pipeline between the primary fan 3 and the air-powder mixer 7 is closed, and the discharge port of the clean coal hopper 6 is closed, and the second channel enters the pulverizing operation mode, and at the same time, the pipeline between the air outlet of the exhaust gas fan 8 and the coal mill 1 is kept unobstructed. At this time, a part of the coal powder enters the burner 2 through the first channel, and a part of the coal powder enters the clean coal hopper 6 through the second channel for storage, and the exhaust gas of the secondary separator 5 is introduced into the coal mill 1 through the exhaust gas fan 8 for recirculation, so as to reduce the air volume entering the burner 2.

[0031] Example 4

[0032] Different from Example 1, Figure 2 As shown, in this embodiment, when the boiler needs to increase the load quickly, the first channel remains unobstructed, the second electric damper 52 is closed, the pipeline between the primary fan 3 and the air-powder mixer 7 is kept unobstructed, and the discharge port of the clean coal hopper 6 is opened, the second channel enters the powder feeding operation mode, the ventilation volume of the second channel is adjusted, and at the same time, the outlet of the exhaust gas fan 8 and the second channel pipe section between the above-mentioned air-powder mixer 7 and the burner 2 are kept unobstructed. At this time, the pulverized coal in the clean coal hopper 6 enters the burner 2 through the air-powder mixer 7, and the exhaust gas of the secondary separator 5 is introduced to the outlet of the air-powder mixer 7 through the exhaust gas fan 8 and enters the burner 2 as the primary air, the coal feeding amount entering the boiler is increased, and the boiler load is quickly increased.

[0033] More specifically, an electric regulating damper 32 is provided on the pipe section close to the air-powder mixer 7 on the pipeline between the primary fan 3 and the air-powder mixer 7 , and the ventilation volume of the second channel is adjusted by operating the electric regulating damper 32 .

[0034] Example 5

[0035] Different from Example 1, Figure 3 As shown, in this embodiment, when the coal flow and coal quality monitoring finds that the coal conveying system 9 contains low-calorific value low-quality coal, in order to prevent the boiler load from decreasing, the first channel is kept unobstructed, the second electric damper 52 is closed, the pipeline between the primary fan 3 and the air-powder mixer 7 is kept unobstructed, and the discharge port of the clean coal hopper 6 is opened, and the second channel enters the powder feeding operation mode. At the same time, the pipeline between the air outlet of the exhaust gas fan 8 and the burner 2 is kept unobstructed, and the ventilation volume of the second channel is adjusted. At this time, the coal powder in the clean coal hopper 6 enters the burner 2 through the air-powder mixer 7, and the exhaust gas of the secondary separator 5 enters the burner 2 as the tertiary air through the exhaust gas fan 8, the coal feeding amount entering the boiler increases and the coal quality improves, and the boiler load remains stable.

[0036] In this embodiment, the ventilation volume of the second channel is adjusted as described in Example 4.

[0037] Example 6

[0038] Different from Example 1, Figure 3 As shown, in this embodiment, when the boiler is in low-load operation, the first channel remains unobstructed, the second electric damper 52 is closed, the pipeline between the primary fan 3 and the air-powder mixer 7 is kept unobstructed, and the second channel enters the powder feeding operation mode. At the same time, the pipeline between the air outlet of the exhaust gas fan 8 and the burner 2 is kept unobstructed, and the ventilation volume of the second channel is adjusted. At this time, the pulverized coal in the clean coal hopper 6 enters the burner 2 through the air-powder mixer 7, and the exhaust gas from the secondary separator 5 enters the burner as the tertiary air through the exhaust gas fan 8, so that the boiler can be operated stably at low load.

[0039] In this embodiment, the ventilation volume of the second channel is adjusted as described in Example 4.

[0040] Example 7

[0041] This embodiment is a specific implementation scheme of the present invention in a 300MW coal-fired unit. Figure 4 As shown. The flexible mixed pulverized coal supply system of the coal-fired unit includes four coal mills A, B, C, and D, wherein the outlet pulverized coal pipelines of coal mills B and D are led out to the two corresponding secondary separators 5, and one air duct is led out from the outlet air duct of the primary fan 3 to the air-powder mixer 7 below the clean coal hopper 6. The coal pulverized coal in the clean coal hopper 6 is divided into four paths through the primary air and sent to the four burners 2 distributed at the four corners of the boiler. The exhaust gas of the secondary separator 5 is divided into two paths, one path is introduced into the coal mill A and the coal mill C for recirculation, and the other path is connected to the burner 2 as the tertiary air. This system can achieve a boiler load operation range of 20%-100%, and the load lifting rate is not less than 6% / min.

[0042] In the above embodiment, the coal conveying system 9 includes a coal feeder 91 and a conveyor belt 92. The discharge port of the coal feeder 91 is located above the feed end of the conveyor belt 92. The discharge end of the conveyor belt 92 is used to convey coal to the coal mill 1. The coal flow monitor 93 is arranged on the side of the conveyor belt 92.

[0043] In actual use, in this embodiment, all electrical components, such as electric dampers, electric adjustable dampers, fans, etc., are connected to the boiler control system to achieve automatic and intelligent adjustment and operation.

[0044] The whole system has the following advantages:

[0045] 1) In this system, the coal mill is decoupled and directly connected to the burner, which acts as a "speed transmission" to synchronize the coal mill output and the burner load adjustment rate, reduce the matching time difference between the coal mill and the burner, realize the rapid response of the coal powder supply system output to the burner load change, and improve the boiler load rise and fall rate.

[0046] 2) This system responds faster to the instability of the boiler's low-load combustion fire. By opening the second channel to supplement low-moisture, high-volatile, easy-to-ignite bituminous coal, the fire under low-load conditions can be made more stable, achieving stable combustion of the boiler at low load.

[0047] 3) This system responds faster to boiler peak load regulation and can quickly increase boiler load by opening the second channel to increase coal supply.

[0048] 4) This system can maintain the boiler load stable when the coal quality entering the furnace fluctuates.

[0049] 5) In this system, the coal mill can still maintain rated operation under low load, which can reduce the net power of the unit connected to the grid and expand the load adjustment range of the unit.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like 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 referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0052] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0054] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0055] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality, characterized by: The invention comprises a coal mill (1), a burner (2), a primary air fan (3), a primary separator (4), a secondary separator (5), a clean coal hopper (6), an air-powder mixer (7) and an exhaust air fan (8), wherein the coal outlet of the coal mill (1) is connected to the primary separator (4), the material outlet of the primary separator (4) is connected to the burner (2) via a first channel, the material outlet of the primary separator (4) is connected to the secondary separator (5), the clean coal hopper (6), the air-powder mixer (7) and the burner (2) in sequence via a second channel, the coal inlet of the coal mill (1) is connected to a coal conveying system (9), the primary air fan (3) is connected to the secondary separator (5), the clean coal hopper (6), the air-powder mixer (7) and the burner (2) via a second channel, the coal inlet of the coal mill (1) is connected to a coal conveying system (9), the primary air fan (3) is connected to the secondary separator (5), the clean coal hopper (6), the air-powder mixer (7) and the burner (2) via a pipe. The coal mill (1) and the air-powder mixer (7) are connected by a line, the exhaust gas outlet of the secondary separator (5) is connected to the air inlet of the exhaust gas fan (8), the air outlet of the exhaust gas fan (8) is connected to the coal mill (1), the air-powder mixer (7) and the second channel pipe section before the burner (2) and the burner (2) through pipelines, the coal conveying system (9) is provided with a coal flow monitor (93), the outlet of the primary separator (4) is provided with a coal quality online monitor, and the first channel and the second channel are respectively provided with a first electric damper (51) and a second electric damper (52) on the pipe sections connecting the secondary separator (5).

2. A flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality according to claim 1, characterized in that: A third electric damper (31) and an electric regulating damper (32) are sequentially arranged on the pipeline connecting the primary fan (3) and the air-powder mixer (7).

3. A flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality according to claim 1, characterized in that: An electric baffle (61) for controlling the discharge of coal powder is provided at the outlet of the clean coal hopper (6).

4. A flexible hybrid pulverized coal supply system based on online monitoring of coal flow and coal quality according to any one of claims 1 to 3, characterized in that: The coal conveying system (9) comprises a coal feeder (91) and a conveying belt (92), wherein the discharge port of the coal feeder (91) is located at the conveying belt (92). Above the feed end, the discharge end of the conveyor belt (92) is used to convey coal to the coal mill (1). The coal flow monitor (93) is arranged on the side of the conveyor belt (92).

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