A pulverizing system coupled with an external pulverizing bin, a pulverizing method and a boiler

Abstract

The present application relates to the technical field of boiler modification, and particularly relates to a coupling external powder bin's pulverizing system, a pulverizing method and a boiler, wherein an A-side coarse powder separator is arranged on one side of a coal mill, and a B-side coarse powder separator is arranged on the other side; the coal powder of the A-side coarse powder separator enters an A-side burner through a cyclone separator, a lock air unloader and a wind powder mixer in sequence; the coal powder of the B-side coarse powder separator directly enters a burner, realizing two different operation modes of the same coal mill; when the unit is in low load operation, the coal mill can be operated in a direct blowing mode on one side to ensure the basic load, and the coal mill can be operated in a powder storage mode, a powder feeding mode and a powder storage and feeding mode on the other side according to the load demand of the unit, so as to ensure the stability of system operation. The present application solves the problem of poor reliability of the existing pulverizing system in a low load state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of boiler reconstruction, in particular to a pulverizing system coupled with an external powder bin, a pulverizing method and a boiler. BACKGROUND

[0002] With a large number of renewable energy represented by solar energy and wind energy connected to the power grid, the existing coal-fired boiler will play a new role in the new power system. On the one hand, it will run at the lowest possible load to give capacity to renewable energy when renewable energy is sufficient; on the other hand, it can quickly increase the load to ensure power supply when renewable energy is insufficient. Therefore, it is necessary to improve the operation flexibility of the existing coal-fired boiler and have deep regulation capability to reduce the problem of large-scale new energy power grid connection and consumption.

[0003] Numerous studies have shown that for boilers, the unit flexibility can be improved by optimizing the coordination of the coal mill and the burner in the combustion system, optimizing the burner to reduce the minimum combustion power, and adding a coal powder bin. Among them, the optimization design of the pulverizing system is an important content to improve the operation flexibility of the boiler. Improving the economy, reliability and load adaptability of the pulverizing system, improving the combustion stability and efficiency of the boiler, and improving the load adaptability, operation reliability and energy saving and emission reduction of the thermal power plant all have important practical significance. The optimization of the pulverizing system includes optimization of the coal powder separator, capacity expansion optimization, optimization of the flow field at the outlet of the separator, and optimization of the control mode of the coal mill. In the capacity expansion optimization scheme, the addition of an intermediate powder storage bin is a more economical and flexible optimization scheme. The intermediate powder storage bin can consume the excess coal powder produced by the coal mill, and can supply powder to the outside as a backup for the coal mill when needed. At the same time, it can also cooperate with the coal mill to supply powder simultaneously to assist the unit to carry the load, and improve the load response rate of the unit.

[0004] Currently, most of the unit pulverizing systems are positive pressure direct blowing type, and the operation of the coal mill directly affects the operating condition of the boiler. The system has low reliability and large hysteresis when adjusting the load. With a high proportion of new energy power system connected to the grid, the situation of thermal power generating units running at 30% load for a long time is becoming more and more common. In order to ensure the safety and rapid load increase of the unit at 30% load, the number of coal mill operation in the pulverizing system is small. If any coal mill fails or is blocked, it is easy to cause the load of the unit to fluctuate, and the system has low reliability. When the unit is running at 30% load, the operation of multiple coal mills is not conducive to the control of nitrogen oxide (NO X ) emission. Therefore, optimizing the performance of the pulverizing system at 30% load has become a key problem. SUMMARY

[0005] In view of the problem of poor reliability of the pulverizing system at low load in the prior art, the present application provides a pulverizing system coupled with an external powder bin.

[0006] To achieve the above object, the application adopts the following technical solutions:

[0007] The application provides a pulverizing system coupled with an external powder bin, comprising a coal mill, an A-side coarse powder separator and an A-side coal feeder arranged on one side of the coal mill, and a B-side coarse powder separator and a B-side coal feeder arranged on the other side of the coal mill; the A-side coarse powder separator and the B-side coarse powder separator are both connected with a primary air main pipe;

[0008] A pulverized coal outlet of the A-side coarse powder separator is connected with a cyclone separator, a lock air unloader, a wind-powder mixer and an A-side burner in sequence; the wind-powder mixer is connected with the primary air main pipe; a waste gas outlet of the cyclone separator is divided into two paths, one of which is connected with a high-position burner, and the other of which is connected with the wind-powder mixer;

[0009] A pulverized coal outlet of the B-side coarse powder separator is connected with a burner.

[0010] Optionally, an A-side bypass air door and an A-side capacity air door are arranged between a wind supply end of the primary air main pipe and the A-side coarse powder separator, and the A-side bypass air door and the A-side capacity air door are connected in parallel.

[0011] Optionally, a B-side bypass air door and a B-side capacity air door are arranged between the wind supply end of the primary air main pipe and the B-side coarse powder separator, and the B-side bypass air door and the B-side capacity air door are connected in parallel.

[0012] Optionally, the pulverized coal outlet of the A-side coarse powder separator is connected with the cyclone separator through a pulverized coal collecting pipe.

[0013] Optionally, the pulverized coal outlet of the A-side coarse powder separator is provided with an A-side outlet valve.

[0014] Optionally, the pulverized coal outlet of the B-side coarse powder separator is provided with a B-side outlet valve.

[0015] Optionally, the waste gas outlet of the cyclone separator is provided with a powder exhaust fan.

[0016] Optionally, an A-waste gas powder feeding valve is arranged between the waste gas outlet of the cyclone separator and the wind-powder mixer; a B-waste gas powder feeding valve is arranged between the waste gas outlet of the cyclone separator and the high-position burner; and a powder feeding valve is arranged between the primary air main pipe and the wind-powder mixer.

[0017] A pulverizing method using the above-mentioned pulverizing system coupled with an external powder bin, comprising:

[0018] When the unit is running at a low load:

[0019] The A-side coal feeder is stopped from feeding powder, and the B-side coal feeder is required to feed powder at a load;

[0020] Part of the wind of the primary air main pipe carries the coal powder milled by the coal mill into the A-side coarse powder separator for separation;

[0021] The fine powder separated by the A-side coarse powder separator is transported to the cyclone separator, and after cyclone separation, falls into the coal powder bin for storage, and the cyclone separator exhaust gas is sent to the high-level burner for combustion;

[0022] Another part of the wind of the primary air main pipe carries the coal powder milled by the coal mill into the B-side coarse powder separator for separation, and the separated fine powder is transported to the burner for combustion to complete the milling;

[0023] When the unit is in high load or normal operation:

[0024] The A-side coal feeder and the B-side coal feeder simultaneously meet the load demand for powder feeding;

[0025] Part of the wind of the primary air main pipe carries the coal powder milled by the coal mill into the A-side coarse powder separator for separation;

[0026] The fine powder separated by the A-side coarse powder separator is transported to the cyclone separator, the air lock unloader and the air-powder mixer in turn, and then is fed to the A-side burner for combustion;

[0027] Another part of the wind of the primary air main pipe carries the coal powder milled by the coal mill into the B-side coarse powder separator for separation, and the separated fine powder is transported to the burner for combustion to complete the milling.

[0028] A boiler comprising the above-mentioned milling system coupled with an external powder bin.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] The application discloses a pulverized coal system coupled with an external powder bin. The system is characterized in that an A-side coarse powder separator is arranged on one side of a coal mill, and a B-side coarse powder separator is arranged on the other side. The coal powder from the A-side coarse powder separator is sequentially introduced into a cyclone separator, a lock air unloader and a wind-powder mixer, and then into an A-side burner. The coal powder from the B-side coarse powder separator is directly introduced into a burner, thereby realizing two different operation modes of the same coal mill. When the unit is operated at a low load, the coal mill can be operated in a direct-fired mode on one side to ensure the basic load, and the coal mill can be operated in a powder storage mode, a powder feeding mode and a powder storage and feeding mode on the other side according to the load demand of the unit, so as to ensure the stability of the system. The system has a simple structure, flexible and changeable operation modes and low transformation cost, can ensure the rapid input of the pulverized coal into the coal mill, ensure the load of the unit and improve the load change rate of the unit, and can also ensure that the coal mill is always operated at the most economical load, thereby improving the adaptability of the boiler to the coal type and the load. In addition, the A-side coarse powder separator is operated in a flue gas powder feeding mode, and there is no flue gas participating in recirculation in the barrel of the coal mill, so that the coal mill is always operated at the best air volume and has good economy. Meanwhile, since there is no low-temperature flue gas into the coal mill, the coal mill has strong drying capacity and can meet the full-load operation requirement of the high-moisture coal.

[0031] An A-side bypass damper and an A-side capacity damper are arranged between the air supply end of the primary air main pipe and the A-side coarse powder separator, and the A-side bypass damper and the A-side capacity damper are connected in parallel. The A-side bypass damper can adjust the air volume entering the A-side coarse powder separator, so that the system can flexibly adjust the air volume according to the coal type, load change and other factors, thereby optimizing the separation effect and combustion efficiency of the pulverized coal. The A-side capacity damper is mainly used for controlling the total air volume entering the pulverized coal system, so as to ensure the stable operation of the system. When the bypass damper is opened, the capacity damper can be adjusted correspondingly to maintain the balance and stability of the air volume of the system.

[0032] A B-side bypass damper and a B-side capacity damper are arranged between the air supply end of the primary air main pipe and the B-side coarse powder separator, and the B-side bypass damper and the B-side capacity damper are connected in parallel. The parallel connection of the B-side bypass damper and the B-side capacity damper allows the system to flexibly adjust the air volume entering the B-side coarse powder separator according to the actual demand, realizes the rapid adjustment of the air volume, and is helpful to maintaining the stability and efficiency of the system.

[0033] The coal powder outlet of the A-side coarse powder separator is connected with the cyclone separator through a coal powder collecting pipe. The coal powder collecting pipe serves as a bridge connecting the A-side coarse powder separator and the cyclone separator, can effectively collect the coal powder discharged from the outlet of the A-side coarse powder separator, and the cyclone separator connected with the coal powder collecting pipe can further separate and purify the coal powder, thereby improving the quality and purity of the coal powder, reducing the emission of pollutants in the combustion process, improving the combustion efficiency and reducing the energy consumption.

[0034] The coal powder outlet of the A-side coarse powder separator is provided with an A-side outlet valve. The A-side outlet valve can be used to more flexibly control and adjust the coal powder flow rate at the outlet of the A-side coarse powder separator, thereby further improving the flexibility of the system.

[0035] The coal powder outlet of the B-side coarse powder separator is provided with a B-side outlet valve. The B-side outlet valve can be used to more flexibly control and adjust the coal powder flow rate at the outlet of the B-side coarse powder separator, thereby further improving the flexibility of the system.

[0036] The exhaust gas outlet of the cyclone separator is provided with a powder exhaust fan. The main function of the powder exhaust fan is to extract the exhaust gas separated by the cyclone separator from the outlet of the cyclone separator and transport it to the subsequent high-level burner or the air-powder mixer. By providing the powder exhaust fan, the exhaust gas can be extracted in a timely and effective manner, thereby avoiding accumulation in the cyclone separator and improving the conveying efficiency of the coal powder.

[0037] An A-exhaust-gas powder feeding valve is arranged between the exhaust gas outlet of the cyclone separator and the air-powder mixer. A B-exhaust-gas powder feeding valve is arranged between the exhaust gas outlet of the cyclone separator and the high-level burner. A powder feeding valve is arranged between the primary air main pipe and the air-powder mixer. The A-exhaust-gas powder feeding valve, the B-exhaust-gas powder feeding valve and the powder feeding valve can be used to flexibly adjust the coal powder flow rate into the air-powder mixer and the high-level burner according to the combustion demand, thereby helping to optimize the combustion process and ensure stable operation of the equipment.

[0038] The present application provides a kind of to utilize the pulverizing system of coupling external powder bin described above to carry out the pulverizing method, which passes through when unit low load operation, make A side coal feeder stop powder feeding, so that the operating mode of mill A side enters powder storage mode, the coal powder separated by mill A side is stored to coal powder bin, and make exhaust gas participate in combustion, while making B side coal feeder load demand to carry out powder combustion, guarantee the stable operation of mill, avoid the influence of the work of mill to boiler operation, to further improve the reliability of system;When unit high load or normal operation, make A side coal feeder and B side coal feeder load demand to carry out powder combustion simultaneously, realize the double-side parallel processing capacity of system, improve the overall flexibility and efficiency of pulverizing system, can adjust the working state of two sides according to actual demand, optimize resource allocation, ensure the continuity and stability of pulverizing process.

[0039] A kind of boiler, including the pulverizing system of coupling external powder bin described above. The boiler has good combustion stability, high combustion efficiency and low operating cost, which is of great significance to solve the problem of large-scale new energy power grid connection and consumption. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 It is a structure schematic view of the pulverizing system of coupling external powder bin of the present application.

[0041] Figure 2 A flow chart of a method for grinding coal in a coal grinding system coupled with an external coal bin.

[0042] Wherein, 1-coal mill, 2-A side bypass damper, 3-A side capacity damper, 4-A side coal feeder, 5-coal bin, 6-cyclone separator, 7-pulverized coal fan, 8-air lock unloader, 9-A exhaust gas pulverized coal feeder valve, 10-pulverized coal feeder valve, 11-burner, 12-primary air main pipe, 13-A side outlet valve, 14-pulverized coal collecting pipe, 15-B side outlet valve, 16-B side coal feeder, 17-B side bypass damper, 18-B side capacity damper, 19-B exhaust gas pulverized coal feeder valve, 20-high level burner, 21-A side coarse powder separator, 22-B side coarse powder separator, 23-A side burner, 24-pulverized coal and air mixer. DETAILED DESCRIPTION

[0043] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0044] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative work fall within the scope of the present application.

[0045] It should be noted that: similar reference numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0046] In the description of the embodiments of the present application, it should be noted that, if the orientation or position relationship indicated by the terms "upper", "lower", "horizontal", "inner" and the like is based on the orientation or position relationship shown in the drawings, or is the orientation or position relationship when the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application. In addition, the terms "first", "second" and the like are only used for differentiation in description, and cannot be understood as indicating or implying relative importance.

[0047] In addition, if the term "horizontal" is used, it is not meant to require absolute horizontal, but can mean slightly inclined. For example, "horizontal" can mean more horizontal than "vertical", but not necessarily perfectly horizontal.

[0048] In the description of the embodiments of the present application, it should also be noted that unless specifically defined and limited, if the terms "set", "install", "connect", "connect" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0049] The present application will be further described in detail below in conjunction with specific embodiments, which are an explanation of the present application rather than a limitation.

[0050] Reference Figure 1 The present application provides a kind of coupling external powder bin's system, including coal mill 1, the side of the coal mill 1 is provided with A side coarse powder separator 21 and A side coal feeder 4, the other side of the coal mill 1 is provided with B side coarse powder separator 22 and B side coal feeder 16;The A side coarse powder separator 21 and B side coarse powder separator 22 are all connected with primary air main pipe 12;

[0051] The coal powder outlet of the A side coarse powder separator 21 is sequentially connected with cyclone separator 6, lock air unloader 8, wind powder mixer 24 and A side burner 23;The wind powder mixer 24 is connected with primary air main pipe 12;The exhaust gas outlet of the cyclone separator 6 is divided into two ways, one of which is connected with high burner 20, and the other is connected with wind powder mixer 24;

[0052] The coal powder outlet of the B side coarse powder separator 22 is connected with burner 11.

[0053] The system is provided with A side coarse powder separator 21 on one side of the coal mill, and B side coarse powder separator 22 on the other side;Make the coal powder of A side coarse powder separator 21 enter A side burner 23 in turn through cyclone separator 6, lock air unloader 8, wind powder mixer 24;Make the coal powder of B side coarse powder separator 22 directly enter burner 11, realize two different operating modes of the same coal mill;When the unit is running at low load, without reducing the output of the coal mill, one side of the coal mill can be directly operated to ensure the basic load, and the other side of the coal mill can be operated according to the load demand of the unit to ensure the stability of the unit operation, and at the same time, the stability of the unit operation and the economy of the coal mill 1 can be improved by adjusting the A side operating mode flexibly.

[0054] Embodiment 2

[0055] Referring to Figure 1 , the application provides a pulverized coal system coupled with an external coal bunker, which comprises a coal mill 1, an A-side bypass air door 2, an A-side capacity air door 3, an A-side coal feeder 4, a coal bunker 5, a cyclone separator 6, a coal discharge fan 7, a lock air unloader 8, an A-side exhaust gas coal feeder valve 9, a coal feeder valve 10, a burner 11, a primary air main pipe 12, an A-side outlet valve 13, a coal collection pipe 14, a B-side outlet valve 15, a B-side coal feeder 16, a B-side bypass air door 17, a B-side capacity air door 18, a B-side exhaust gas coal feeder valve 19, a high-level burner 20, an A-side coarse coal separator 21, a B-side coarse coal separator 22, an A-side burner 23 and a coal-pulverized air mixer 24.

[0056] The coal mill 1 is supplied with air from the primary air main pipe 12, and the A side of the coal mill 1 is supplied with coal by the A-side coal feeder 4 and air by the A-side bypass air door 2 and the A-side capacity air door 3; the B side of the coal mill 1 is supplied with coal by the B-side coal feeder 16 and air by the B-side bypass air door 17 and the B-side capacity air door 18; after the coal mill 1 grinds the coal into pulverized coal, the pulverized coal is sent to the A-side coarse coal separator 21 and the B-side coarse coal separator 22, respectively, the coal separated by the A-side coarse coal separator 21 is sent to the A-side burner 23 into the furnace to participate in combustion in sequence through the A-side outlet valve 21, the coal collection pipe 14, the cyclone separator 6, the coal bunker 5, the lock air unloader 8 and the coal-pulverized air mixer 24, the top exhaust gas of the cyclone separator 6 is divided into two routes by the coal discharge fan 7, one route is sent to the coal-pulverized air mixer 24 to participate in the feeding of the coal bunker 5 through the A-side exhaust gas coal feeder valve 9, and the other route is sent to the high-level burner 20 through the B-side exhaust gas coal feeder valve 19; the coal separated by the B-side coarse coal separator 22 is sent to the B-side burner 11 to participate in combustion through the B-side outlet valve 22.

[0057] Preferably, to reduce the coal pipe components, the A-side separator 21 outlet coal pipe can be combined into one, while the influence on the separation effect of the A-side separator needs to be considered; preferably, to reduce the coal pipe components, the A-side coarse coal separator 21 outlet coal pipe can be combined into one, while the influence on the separation effect of the A-side coarse coal separator 21 needs to be considered; to reduce the influence of exhaust gas on the combustion in the furnace, the exhaust fan 7 outlet exhaust gas can be constructed into a bag-type dust collector, and the dust-removed exhaust gas is sent to the secondary air main pipe of the air preheater; to improve the coal separation efficiency, the cyclone separator 6 can be appropriately increased according to the situation.

[0058] The powder storage process: when the unit needs the coal pulverizer to store powder, the coal feeder 4 sends raw coal to the coal pulverizer 1, the primary air in the primary air main pipe 12 enters the coal pulverizer 1 through the A-side bypass air door 2 and the A-side capacity air door 3, the primary air carrying the ground coal powder enters the A-side coarse powder separator 21 for separation, the separated fine powder is discharged from the A-side outlet valve 13, then enters the cyclone separator 6 through the coal powder collecting pipe 14, and falls into the coal powder bin 5 after the cyclone separation, and the exhaust gas at the top of the cyclone separator 6 is pressurized by the exhaust air blower 7, then enters the furnace through the high-level burner 20 to participate in combustion or is sent to the air-powder mixer 24.

[0059] The powder feeding process: when the unit needs the coal pulverizer to feed powder, the coal powder in the coal powder bin 5 falls into the air-powder mixer 24 through the air-lock unloader 8, the coal powder is mixed with the primary air to enter the A-side burner 23, and the primary air comes from the primary air main pipe 12 or the outlet of the exhaust air blower 7.

[0060] The operation mode: when the unit is in low load, in order to reduce the coal powder input, the A-side of the coal pulverizer 1 stops feeding powder into the furnace, the B-side of the coal pulverizer 1 feeds powder or stops feeding powder according to the load demand, and at the same time, in order to improve the unit load response rate during the unit load increasing stage, the coal pulverizer 1 is put into the powder storage program, the coal powder is stored in the coal powder bin 5 through the cyclone separator 6, and the exhaust gas is sent to the high-level burner 20 through the exhaust air blower 7 to participate in the furnace combustion, so that the coal pulverizer 1 can continuously operate without stopping.

[0061] Referring to Figure 2 , the application provides a powder making method using the above-mentioned coupling external powder bin powder making system, which comprises the following steps:

[0062] When the unit is in low load operation:

[0063] S11: the A-side coal feeder 4 stops feeding powder, and the B-side coal feeder 16 feeds powder according to the load demand;

[0064] S12: a part of the primary air in the primary air main pipe 12 carries the ground coal powder of the coal pulverizer 1 to enter the A-side coarse powder separator 21 for separation;

[0065] S13: the fine powder separated by the A-side coarse powder separator 21 is transported to the cyclone separator 6, falls into the coal powder bin 5 after the cyclone separation, and the exhaust gas of the cyclone separator 6 is sent to the high-level burner 20 to participate in combustion;

[0066] S14: another part of the primary air in the primary air main pipe 12 carries the ground coal powder of the coal pulverizer 1 to enter the B-side coarse powder separator 22 for separation, and the separated fine powder is transported to the burner 11 to participate in combustion, and the powder making is completed.

[0067] When the unit is in high load or normal operation:

[0068] S21: simultaneously load the A-side coal feeder 4 and the B-side coal feeder 16 to send the powder;

[0069] S22: a part of the wind of the primary air main pipe 12 carries the coal powder ground by the coal mill 1 into the A-side coarse powder separator 21 for separation;

[0070] S23: the fine powder separated by the A-side coarse powder separator 21 is sequentially conveyed to the A-side burner 23 for combustion through the cyclone separator 6, the air lock unloader 8 and the wind-powder mixer 24;

[0071] S24: another part of the wind of the primary air main pipe 12 carries the coal powder ground by the coal mill 1 into the B-side coarse powder separator 22 for separation, and the separated fine powder is conveyed to the burner 11 for combustion, and the process of powder making is completed.

[0072] The method stops the A-side coal feeder 4 from sending powder when the unit is in low load operation, so that the operation mode of the A-side of the coal mill 1 enters the powder storage mode, the coal powder separated by the A-side of the coal mill 1 is stored in the coal powder bin, the exhaust gas is used for combustion, and the B-side coal feeder 16 is loaded to send powder for combustion, which ensures the stable operation of the coal mill 1 and avoids the influence of the operation of the coal mill 1 on the operation of the boiler, thereby improving the reliability of the system; when the unit is in high load or normal operation, the A-side coal feeder 4 and the B-side coal feeder 16 are simultaneously loaded to send powder for combustion, which realizes the parallel processing capacity of the system on both sides, improves the overall flexibility and efficiency of the powder making system, adjusts the working state of the two sides according to the actual demand, optimizes the resource allocation, and ensures the continuity and stability of the powder making process.

[0073] A boiler comprising the above-mentioned powder making system coupled with an external powder bin. The boiler has good combustion stability, high combustion efficiency and low operation cost, and is of great significance for solving the problem of large-scale new energy power grid connection and consumption.

[0074] In summary, the present application provides a powder making system coupled with an external powder bin, a powder making method and a boiler. By dividing the two sides of the double-in double-out coal mill into two operation modes, the straight blowing operation of one side of the coal mill 1 is ensured to guarantee the basic load without reducing the output of the coal mill 1, and the other side of the coal mill 1 is operated in the powder storage mode, the powder sending mode and the powder storage and sending mode according to the load demand of the unit, so that the operation mode is flexible and variable, the stability of different unit loads is ensured, the unit load change rate is improved, the coal mill 1 is always operated at the most economical load, and the economy and load adaptability of the coal mill 1 are improved.

[0075] The above merely describes the preferred embodiments of the present application, and is not intended to limit the technical solutions of the present application in any way. Those skilled in the art should understand that, without departing from the spirit and principle of the present application, the technical solutions can also be modified and replaced in several simple ways, and these modifications and replacements also all belong to the protection scope covered by the claims.

Claims

1. A powder-making system coupled with an external powder silo, characterized in that, The coal mill (1) is provided with an A-side coarse powder separator (21) and an A-side coal feeder (4) on one side, and a B-side coarse powder separator (22) and a B-side coal feeder (16) on the other side; the A-side coarse powder separator (21) and the B-side coarse powder separator (22) are connected with a primary air main pipe (12); The coal powder outlet of the A-side coarse powder separator (21) is connected with a cyclone separator (6), a lock air unloader (8), a wind-powder mixer (24) and an A-side burner (23) in sequence; the wind-powder mixer (24) is connected with the primary air main pipe (12); the exhaust gas outlet of the cyclone separator (6) is connected with a high-level burner (20) and the wind-powder mixer (24) in two ways; The coal powder outlet of the B-side coarse powder separator (22) is connected with a burner (11).

2. The mill system coupled with an external hopper according to claim 1, wherein An A-side bypass air door (2) and an A-side capacity air door (3) are arranged between the primary air main pipe (12) and the A-side coarse powder separator (21); the A-side bypass air door (2) and the A-side capacity air door (3) are connected in parallel.

3. The mill system coupled with an external hopper according to claim 1, wherein A B-side bypass air door (17) and a B-side capacity air door (18) are arranged between the primary air main pipe (12) and the B-side coarse powder separator (22); the B-side bypass air door (17) and the B-side capacity air door (18) are connected in parallel.

4. The mill system with an external hopper according to claim 1, wherein The coal powder outlet of the A-side coarse powder separator (21) is connected with the cyclone separator (6) through a coal powder collecting pipe (14).

5. The coupled external hopper milling system of claim 1, wherein, The coal powder outlet of the A-side coarse powder separator (21) is provided with an A-side outlet valve (13).

6. The coupled external hopper milling system of claim 1, wherein, The coal powder outlet of the B-side coarse powder separator (22) is provided with a B-side outlet valve (15).

7. The coupled external hopper milling system of claim 1, wherein, The exhaust gas outlet of the cyclone separator (6) is provided with a powder exhaust fan (7).

8. The coupled external hopper milling system of claim 1, wherein, An A-exhaust gas powder feeding valve (9) is arranged between the exhaust gas outlet of the cyclone separator (6) and the wind-powder mixer (24); a B-exhaust gas powder feeding valve (19) is arranged between the exhaust gas outlet of the cyclone separator (6) and the high-level burner (20); a powder feeding valve (10) is arranged between the primary air main pipe (12) and the wind-powder mixer (24).

9. A method of milling using the coupling external mill bunker system according to any one of claims 1 to 8, characterized in that, It comprises: When the unit is running at low load: The A-side coal feeder (4) is stopped to feed powder, and the B-side coal feeder (16) feeds powder according to the load demand; Part of the wind of the primary air main pipe (12) carries the coal powder milled by the coal mill (1) into the A-side coarse powder separator (21) for separation; The fine powder separated by the A-side coarse powder separator (21) is transported to the cyclone separator (6), and after cyclone separation, it falls into the coal powder bin (5) for storage, and the exhaust gas of the cyclone separator (6) is sent to the high-level burner (20) for combustion; The other part of the wind of the primary air main pipe (12) carries the coal powder milled by the coal mill (1) into the B-side coarse powder separator (22) for separation, and then the separated fine powder is transported to the burner (11) for combustion to complete the milling; When the unit is running at high load or normal load: The A-side coal feeder (4) and the B-side coal feeder (16) simultaneously feed powder according to the load demand; A part of the wind of the primary air main pipe (12) carries the coal powder milled by the coal mill (1) into the A-side coarse powder separator (21) for separation; The fine powder separated by the A-side coarse powder separator (21) is sequentially transported to the A-side burner (23) for combustion through the cyclone separator (6), the lock air unloader (8) and the wind-powder mixer (24); Another part of the wind of the primary air main pipe (12) carries the coal powder milled by the coal mill (1) into the B-side coarse powder separator (22) for separation, and the separated fine powder is transported to the burner (11) for combustion, thus completing the milling.

10. A boiler characterized by The milling system coupled with the external powder bin comprises the milling system according to any one of claims 1-8.

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