Peak shaving system for bypass powder bin externally hung on powder outlet pipe of coal mill

Abstract

The utility model discloses a coal mill powder outlet pipe external bypass powder bin peak regulation system which is installed on a powder outlet pipe at an outlet of a coal mill and comprises a bypass powder bin, a bypass air powder pipe, a powder storage control valve, a powder feeder and an exhaust pipe. A bypass connector, a powder feeding port and an air return port are formed in the side wall of the powder outlet pipe. An air-powder separator is arranged at the top in the bypass powder bin, and an air-powder inlet and an exhaust gas outlet are formed in the air-powder separator; one end of the bypass pulverized coal pipe is communicated with the bypass interface, and the other end is tangentially connected into the pulverized coal inlet; the powder storage control valve is arranged on the bypass interface; a powder feeding inlet and a powder feeding outlet are formed in the powder feeder, the powder feeding inlet is communicated with the bottom of the bypass powder bin, and the powder feeding outlet is communicated with the powder feeding opening; and the other end of the exhaust pipe is communicated with the air return port. The device realizes rapid and accurate dynamic matching of a fuel system and a combustion system, is safe and environment-friendly, has an ingenious, simple and practical structure, and is easy to transform and popularize.

Description

Technical Field

[0001] This utility model relates to a system for peak shaving of coal mill pulverized coal silos with external bypass on the pulverized coal outlet pipe, belonging to the field of flexible operation control technology for coal-fired power plant boilers. Background Technology

[0002] The pulverized coal preparation system in a coal-fired power plant is often simply referred to as the pulverizing system. The pulverizing system refers to the combination of equipment and related connecting pipes required to grind and dry raw coal into pulverized coal with a certain fineness and moisture content, which is then fed into the boiler furnace for combustion. Common pulverizing systems are classified into two types based on the characteristics of the workers: direct-fired and intermediate-storage.

[0003] In a direct-fired pulverizing system, the pulverized coal produced by the heavy pulverizer is directly fed into the boiler furnace for combustion without intermediate stops. Therefore, the normal operation of the boiler depends on the reliability of the pulverizing system. Pulverizers with good variable load characteristics, such as medium-speed, high-speed, and double-inlet / double-outlet pulverizers, are preferable. Direct-fired pulverizing systems equipped with medium-speed pulverizers have a simple structure, fewer equipment, compact layout, low steel consumption, lower investment, and relatively low pulverizer power consumption, making them commonly used in medium and large-scale coal-fired power plants. While direct-fired pulverizing systems have many advantages, they are still relatively inferior in responding to boiler load changes. When the boiler load changes, the coal feed rate changes accordingly, but due to the 3-5 minute lag time in the pulverized coal grinding process, the pulverized coal output does not perfectly match the boiler's fuel consumption in real time. This limits the load change rate (i.e., the ramp rate, including upward and downward ramp rates) of the coal-fired unit, generally only reaching about 1.5% Pe / min.

[0004] Centralized coal storage pulverizing systems typically employ slower-speed ball mills. Compared to direct-fired pulverizing systems, they incorporate additional equipment such as fine powder separators, pulverized coal silos, feeders, and screw conveyors. In a centralized coal storage system, raw coal exits the silo, is fed by the feeder controller, and then flows into the downflow drying pipe, where it meets the drying hot air before being fed into the pulverizer. The raw coal is dried and ground in the pulverizer. The ground pulverized coal is carried out of the outlet by the drying air and sent to the coarse powder separator for further processing. Unqualified coarse powder is returned to the pulverizer via the return pipe for re-grinding, while qualified pulverized coal continues to be carried by the drying air into the fine powder separator. In the fine powder separator, approximately 90% of the pulverized coal is separated from the pulverized coal airflow and falls into the pulverized coal silo below, or is conveyed by the screw conveyor to the pulverized coal silos of other boilers. Pulverized coal for boiler combustion is taken from the pulverized coal silo according to the boiler's needs, fed into the primary air duct via an adjustable pulverizer, and then blown into the boiler for combustion by the primary air. Compared to direct-fired pulverized coal systems, intermediate-storage pulverized coal systems have more components, higher investment, larger footprint, higher power consumption, and greater maintenance workload, and are also more dangerous, posing a risk of explosion. However, they also have significant advantages, such as the ability to extract the required amount of fuel from the pulverized coal silo in real time, thus improving the ramp-up rate of coal-fired units.

[0005] Under the backdrop of carbon neutrality, coal-fired power will undergo a transformation from a primary energy source to a basic energy source to a regulating energy source. For boilers with direct-fired pulverized coal systems, after receiving a load increase command, the process of feeding, mixing, and grinding coal is required before fuel can be delivered into the furnace. The load response of the fuel system has a long periodicity, while combustion in the furnace is instantaneous. After receiving the command, the control of the combustion system will have a significant lag. To minimize the lag, some studies have proposed improvement schemes for the aforementioned direct-fired pulverized coal systems, such as adding small pulverized coal silos, aiming to combine the advantages of the two pulverized coal systems. However, small pulverized coal silos are prone to safety and environmental problems (they can easily lead to dead zones of pulverized coal accumulation causing deflagration, and can also easily cause pipe blockages, and the space for on-site modification is limited). It is also difficult to further overcome the bottleneck of rapid and accurate dynamic matching between the fuel system and the combustion system in the rapid peak shaving of coal-fired power plant boilers. Utility Model Content

[0006] In order to further overcome the bottleneck of rapid and accurate dynamic matching between the fuel system and the combustion system in the rapid peak shaving of coal-fired power plant boilers, and to ensure that the pulverizing system is safe and environmentally friendly, this utility model provides a system for peak shaving of coal mill pulverizers with external bypass pulverizer bins attached to the pulverizer outlet pipe.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0008] A system for peak shaving by connecting a bypass powder bin to the powder outlet pipe of a coal mill is installed on the powder outlet pipe of the coal mill and includes at least a bypass powder bin, a bypass air-powder pipe, a powder storage control device, a powder feeder, and a waste gas pipe; the powder storage control device includes a powder storage control valve and / or a powder storage suction device.

[0009] The side wall of the powder outlet pipe is equipped with a bypass interface, a powder inlet, and a return air inlet; the top of the bypass powder hopper is equipped with an air-powder separator, which has an air-powder inlet and a waste gas outlet.

[0010] One end of the bypass air-powder pipe is connected to the bypass interface, and the other end is tangentially connected to the air-powder inlet; the powder feeder is equipped with a powder feed inlet and a powder feed outlet, the powder feed inlet is connected to the bottom of the bypass powder silo, and the powder feed outlet is connected to the powder feed port; one end of the exhaust gas pipe is connected to the exhaust gas outlet, and the other end is connected to the return air inlet.

[0011] When a powder storage control valve is provided, it is located on the bypass interface; when a powder storage suction device is provided, it is located on the exhaust gas pipe; the amount of powder entering the bypass air-powder pipe is adjusted by regulating the opening of the powder storage control valve and / or the vacuum degree of the powder storage suction device.

[0012] The aforementioned powder storage control valve and powder storage suction device can be installed simultaneously or selectively. It is preferable to install them simultaneously, as this further improves control accuracy and allows for adjustment of the air-to-coal ratio in the powder outlet pipe as needed.

[0013] As one preferred implementation, the powder storage suction device operates based on the concentric jet principle (its structure is the same as existing concentric jet injectors and sampling jet injectors), and the working air source is drawn from the primary air duct. This allows for adjustment of the air-to-coal ratio in the powder outlet pipe.

[0014] The other end of the aforementioned bypass air-coal duct is tangentially connected to the air-coal inlet. This means the air and coal in the bypass air-coal duct enter the air-coal separator tangentially (along the tangent of a circle). After separation by the air-coal separator, the pulverized coal falls into the bypass pulverized coal bin, while the remaining gas (exhaust gas) returns to the pulverized coal outlet pipe through the exhaust gas pipe. Upon receiving a load increase command, the pulverized coal in the bypass pulverized coal bin is fed into the pulverized coal outlet pipe via the pulverizer, and then into the furnace, achieving rapid and precise dynamic matching between the fuel system and the combustion system.

[0015] In this application, "connected" refers to being linked and interconnected. The direction from upstream to downstream is consistent with the direction of material flow.

[0016] In this application, the air-coal separator and the bypass coal silo are connected, and the coal powder separated by the air-coal separator falls directly into the bypass coal silo.

[0017] The coal feeder of this application can control the amount of coal powder entering the coal outlet pipe from the bypass coal silo as needed. Existing equipment with relevant functions can be purchased directly. This application does not make any special improvements to the internal structure of the coal feeder, so it will not be described in detail here.

[0018] To enhance safety, the aforementioned system for peak shaving via a bypass pulverized coal silo attached to the pulverized coal mill outlet pipe also includes an explosion-proof gas delivery pipe. One end of the explosion-proof gas delivery pipe is connected to an explosion-proof gas source, and the other end leads to an air-coal separator. A control valve is installed on the explosion-proof gas delivery pipe. The explosion-proof gas can be nitrogen or an inert gas.

[0019] To ensure explosion-proof performance without affecting air-powder separation, the explosion-proof gas delivery pipe passes through the side wall of the exhaust gas pipe and enters the air-powder separator from the exhaust gas outlet.

[0020] To improve the air-coal separation efficiency, the air-coal inlet is located on the side wall of the air-coal separator, and the exhaust gas outlet is located at the top center of the air-coal separator. The exhaust gas pipe extends vertically into the air-coal separator from the exhaust gas outlet, exceeding the lowest point of the air-coal inlet; that is, the depth to which the exhaust gas pipe extends into the air-coal separator exceeds the lowest point of the air-coal inlet. This maximizes the separation of pulverized coal introduced into the air-coal separator and allows it to fall into the bypass pulverized coal silo.

[0021] To improve the separation effect, the air and powder in the bypass air-powder pipe enter the air-powder separator along the tangential direction of a circle coaxial with the air-powder separator.

[0022] To improve controllability and simplify the structure for easy installation, the powder storage control valve is a plate structure. It covers the bypass interface and is located inside the powder outlet pipe. One end of the powder storage control valve is a free end, and the other end is a connecting end. The direction from the free end to the connecting end is consistent with the direction of air-powder flow in the powder outlet pipe (i.e., consistent with the direction from upstream to downstream in the powder outlet pipe). The connecting end of the powder storage control valve is hinged to the inner wall of the powder outlet pipe. The rotation angle of the powder storage control valve is adjustable from 0 to 180°. When the powder storage control valve is in the open state, part of the air-powder in the powder outlet pipe is turbulent by the powder storage control valve and enters the bypass air-powder pipe. The amount of air-powder entering the bypass air-powder pipe can be adjusted by adjusting the opening angle of the powder storage control valve.

[0023] To improve the dust collection effect in the bypass dust hopper, the return air vent is located downstream of the bypass interface.

[0024] To facilitate installation and ensure effective powder collection within the bypass powder hopper, the bypass interface, powder inlet, and return air inlet are sequentially installed along the powder outlet pipe from upstream to downstream.

[0025] To improve adaptability, at least the exhaust gas pipe should be equipped with a pipe compensator. The pipe compensator can absorb the thermal expansion of the pipeline through its own deformation, preventing deformation or damage caused by thermal stress. Pipe compensators can also be installed on other pipelines depending on site conditions.

[0026] The aforementioned air-powder separator uses cyclone separation to separate air and powder. Existing equipment with relevant functions can be purchased directly. This application does not make any special improvements to the internal structure of the powder feeder, so it will not be described in detail here.

[0027] The aforementioned bypass pulverized coal bin is equipped with a gravity sensor and / or a level sensor to measure the weight and / or height of the pulverized coal inside the bypass pulverized coal bin.

[0028] To facilitate temperature testing inside the bypass powder hopper, temperature measuring points are also installed on the bypass powder hopper.

[0029] To ensure that the pulverized coal in the bypass silo can flow out smoothly and avoid dead corners, the bottom of the bypass silo has a tapering funnel structure.

[0030] A method for peak shaving by installing a bypass pulverized coal bin on the pulverized coal outlet pipe of a coal mill involves installing a bypass pulverized coal bin on the outlet pipe of the coal mill, with an air-coal separator installed at the top of the bypass pulverized coal bin. Part of the air and coal in the outlet pipe is tangentially introduced into the air-coal separator through the bypass air-coal separator for separation. The resulting pulverized coal falls into the bypass pulverized coal bin, while the generated exhaust gas returns to the outlet pipe through the exhaust gas pipe. Upon receiving a load increase command, the pulverized coal in the bypass pulverized coal bin is fed into the outlet pipe via a pulverized coal feeder, and then into the furnace, achieving rapid and precise dynamic matching between the fuel system and the combustion system.

[0031] To improve operational safety, explosion-proof gas is introduced into the air-powder separator through an explosion-proof gas delivery pipe.

[0032] To improve the air-dust separation effect, the air and dust in the bypass air-dust pipe enter the air-dust separator along the tangential direction of a circle coaxial with the air-dust separator.

[0033] To ensure operational stability, upon receiving a load reduction command, the control valve on the explosion-proof gas delivery pipe is closed. The powder storage control valve installed at the end of the bypass air-powder pipe and / or the powder storage suction device installed on the exhaust gas pipe are adjusted to allow a portion of the air-powder in the outlet pipe to enter the air-powder separator tangentially along a circle coaxial with the separator. When the gravity sensor and / or level sensor indicate that the amount of coal powder in the bypass powder silo has reached the set value, powder storage is stopped, and the control valve on the explosion-proof gas delivery pipe is reopened. At any time, if the temperature measuring point on the bypass powder silo reports an abnormal temperature increase, powder storage is immediately stopped, and the control valve on the explosion-proof gas delivery pipe is opened simultaneously.

[0034] Any technologies not mentioned in this utility model are based on existing technologies.

[0035] This utility model relates to a coal mill pulverizer bypass pulverizer bin system for peak shaving. A bypass pulverizer bin is installed on the pulverizer outlet pipe of the coal mill. A portion of the air and pulverized coal from the outlet pipe is tangentially introduced into the air-pulverized coal separator at the top of the bypass pulverizer bin via a bypass air-pulverized coal pipe. The resulting pulverized coal falls into the bypass pulverizer bin, while the generated exhaust gas returns to the outlet pipe through an exhaust gas pipe. Upon receiving a load increase command, the pulverized coal in the bypass pulverizer bin is fed back into the outlet pipe via a pulverizer feeder, and then into the furnace. This achieves rapid and precise dynamic matching between the fuel system and the combustion system, breaking through the bottleneck of rapid and precise dynamic matching between the fuel system and the combustion system in rapid peak shaving of coal-fired power plant boilers. It is safe and environmentally friendly; moreover, its structure is ingenious, simple, practical, and effective, and it is easy to modify and promote. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the structure of the system for peak shaving of coal mill powder outlet pipe with external bypass powder bin in Embodiment 1 of this utility model.

[0037] Figure 2 This is a schematic diagram of the structure of the coal mill pulverizer external bypass pulverizer peak-shaving system in Embodiment 2 of this utility model.

[0038] Figure 3 yes Figure 2 Top view.

[0039] Figure 4 yes Figure 2 A three-dimensional image.

[0040] Figure 5 This is a schematic diagram of the structure of the coal mill pulverizer external bypass pulverizer peak-shaving system in Embodiment 3 of this utility model.

[0041] Figure 6 yes Figure 5 Top view.

[0042] Figure 7 yes Figure 5 A three-dimensional image.

[0043] Figure 8 This is a schematic diagram of the structure of the coal mill pulverizer external bypass pulverizer peak-shaving system in Embodiment 5 of this utility model.

[0044] Figure 9 yes Figure 8 Top view.

[0045] Figure 10 yes Figure 8 A three-dimensional image.

[0046] Figure 11 This is a schematic diagram of the structure of the coal mill pulverizer external bypass pulverizer peak-shaving system in Embodiment 6 of this utility model.

[0047] Figure 12 yes Figure 11 Top view.

[0048] Figure 13 yes Figure 11 A three-dimensional image.

[0049] Figure 14 This is a schematic diagram of the structure of the coal mill pulverizer external bypass pulverizer peak-shaving system in Embodiment 10 of this utility model.

[0050] Figure 15 This is a schematic diagram of the structure of the coal mill pulverizer external bypass pulverizer peak-shaving system in Embodiment 11 of this utility model.

[0051] In the diagram, 1 is the powder outlet pipe, 2 is the bypass powder silo, 21 is the air-powder separator, 22 is the temperature measuring point, 23 is the gravity sensor, 24 is the level sensor, 3 is the bypass air-powder pipe, 4 is the powder storage control valve, 5 is the powder feeder, 6 is the exhaust gas pipe, 61 is the pipeline compensator, 7 is the explosion-proof gas delivery pipe, 71 is the control valve, 8 is the powder storage suction device, and a is the primary air. Detailed Implementation

[0052] To better understand this utility model, the following embodiments further illustrate the content of this utility model, but the content of this utility model is not limited to the following embodiments.

[0053] Example 1

[0054] like Figure 1 As shown, a system for peak shaving by connecting a bypass powder bin to the powder outlet pipe of a coal mill is installed on the powder outlet pipe of the coal mill and includes at least a bypass powder bin, a bypass air-powder pipe, a powder storage control valve, a powder feeder, and a waste gas pipe.

[0055] The powder outlet pipe is equipped with a bypass interface, a powder inlet, and a return air inlet on its side wall.

[0056] The bypass powder silo is equipped with an air-powder separator at the top, which has an air-powder inlet and a waste gas outlet.

[0057] One end of the bypass air-powder pipe is connected to the bypass interface, and the other end is tangentially connected to the air-powder inlet; the powder storage control valve is located on the bypass interface, and the amount of air-powder entering the bypass air-powder pipe is adjusted by adjusting the opening of the powder storage control valve.

[0058] The powder feeder is equipped with a powder inlet and a powder outlet. The powder inlet is connected to the bottom of the bypass powder bin, and the powder outlet is connected to the powder feed port.

[0059] One end of the exhaust gas pipe is connected to the exhaust gas outlet, and the other end is connected to the return air inlet.

[0060] During operation, the pulverized coal storage control valve is opened, and a portion of the pulverized coal in the outlet pipe is tangentially introduced into the pulverized coal separator through the bypass pulverized coal pipe for pulverized coal separation (the amount of pulverized coal entering the bypass pulverized coal pipe is adjusted by regulating the opening of the pulverized coal storage control valve). After separation by the pulverized coal separator, the pulverized coal falls into the bypass pulverized coal bin, and the remaining gas (exhaust gas) returns to the outlet pipe through the exhaust gas pipe. When a load increase command is received, the pulverized coal in the bypass pulverized coal bin is fed into the outlet pipe by the pulverized coal feeder, and then into the furnace, achieving rapid and precise dynamic matching between the fuel system and the combustion system.

[0061] Example 2

[0062] Based on Example 1, the following improvements were made: Figure 2-4 As shown, to improve adaptability, at least a pipe compensator should be installed on the exhaust gas pipe. The pipe compensator can absorb the thermal expansion of the pipe through its own deformation, preventing deformation or damage caused by thermal stress. To facilitate the measurement of the weight of pulverized coal in the bypass silo, a gravity sensor is installed on the bypass silo. Temperature measuring points are also installed on the bypass silo to facilitate temperature measurement.

[0063] Example 3

[0064] Based on Example 2, the following improvements were made: Figure 5-7 As shown, to improve safety, the aforementioned coal mill outlet pulverizer bypass pulverizer peak-shaving system also includes an explosion-proof gas delivery pipe. One end of the explosion-proof gas delivery pipe is connected to an explosion-proof gas source, and the other end is connected to an air-pulverizer separator. A control valve is installed on the explosion-proof gas delivery pipe. The explosion-proof gas is nitrogen.

[0065] Example 4

[0066] Based on Example 3, the following improvements were made: Figure 5-7 As shown, in order to ensure the explosion-proof effect without affecting the air-powder separation, the explosion-proof gas delivery pipe passes through the side wall of the exhaust gas pipe and enters the air-powder separator from the exhaust gas outlet.

[0067] Example 5

[0068] Based on Example 2, the following improvements were made: Figure 8-10 As shown, a powder storage suction device is installed on the exhaust gas pipe. The powder storage suction device operates based on the concentric jet principle (its structure is the same as existing concentric jet injectors and sampling jet injectors). The working air source is drawn from the primary air, and an automatic control ball valve is installed on the primary air inlet pipe (DN150 pipe) to regulate the introduced primary air volume. This allows for adjustment of the air-to-coal ratio in the powder outlet pipe. The amount of air and powder entering the bypass air-to-coal pipe is adjusted by regulating the opening of the powder storage control valve and the vacuum level of the powder storage suction device. Of course, depending on the specific operating conditions, either the powder storage control valve or the powder storage suction device can be selected.

[0069] Example 6

[0070] Based on Example 4, the following improvements were further made: Figure 11-13 As shown, a powder storage suction device is installed on the exhaust gas pipe. The powder storage suction device operates based on the concentric jet principle (its structure is the same as existing concentric jet injectors and sampling jet injectors). The working air source is drawn from the primary air, and an automatic control ball valve is installed on the primary air inlet pipe (DN150 pipe) to regulate the introduced primary air volume. This allows for adjustment of the air-to-coal ratio in the powder outlet pipe. The amount of air and powder entering the bypass air-to-coal pipe is adjusted by regulating the opening of the powder storage control valve and the vacuum level of the powder storage suction device. Of course, depending on the specific operating conditions, either the powder storage control valve or the powder storage suction device can be selected.

[0071] Example 7

[0072] Based on Examples 4, 5, or 6, the following improvements were further made: Figure 1-13 As shown, to improve the air-coal separation effect, the air-coal inlet is located on the side wall of the air-coal separator, and the exhaust gas outlet is located at the center of the top of the air-coal separator. The exhaust gas pipe extends vertically into the air-coal separator from the exhaust gas outlet, exceeding the lowest point of the air-coal inlet; that is, the depth to which the exhaust gas pipe extends into the air-coal separator exceeds the lowest point of the air-coal inlet. This allows for the separation of coal dust introduced into the air-coal separator as much as possible and for it to fall into the bypass dust silo. To further improve the separation effect, the air and coal dust in the bypass air-coal pipe enter the air-coal separator tangentially along a circle coaxial with the air-coal separator.

[0073] Example 8

[0074] Based on Example 7, the following improvements were further made: Figure 1-13 As shown, to improve controllability and simplify the structure for easy installation, the powder storage control valve is a plate structure. It covers the bypass interface and is located inside the powder outlet pipe. One end of the control valve is a free end, and the other is a connecting end. The direction from the free end to the connecting end is consistent with the direction of powder flow in the powder outlet pipe (i.e., consistent with the upstream to downstream direction). The connecting end of the control valve is hinged to the inner wall of the powder outlet pipe. The rotation angle of the control valve is adjustable from 0-180°. When the control valve is in the open state (e.g....), Figure 1 (Open at 90°) Part of the powder in the powder outlet pipe is turbulently introduced into the bypass powder pipe through the powder storage control valve. The amount of powder entering the bypass powder pipe is adjusted by adjusting the opening angle of the powder storage control valve.

[0075] Example 9

[0076] Based on Example 8, the following improvements were further made: Figure 1-13As shown, to improve the powder collection effect in the bypass powder hopper, the return air vent is located downstream of the bypass interface. For ease of installation and to ensure effective powder collection in the bypass powder hopper, the bypass interface, powder inlet, and return air vent are sequentially arranged from upstream to downstream along the powder outlet pipe.

[0077] Example 10

[0078] Based on Example 1, the following improvements were made: Figure 14 As shown, the bypass pulverized coal hopper is equipped with a level sensor to measure the height of the pulverized coal inside. Alternatively, a gravity sensor can be installed to measure the weight of the pulverized coal, depending on site conditions. Temperature measuring points are also provided on the bypass pulverized coal hopper to facilitate temperature monitoring. To ensure smooth flow of pulverized coal and prevent accumulation in dead zones, the bottom of the bypass pulverized coal hopper has a tapering funnel structure.

[0079] Example 11

[0080] Based on Example 9, the following improvements were further made: Figure 15 As shown, a powder storage suction device is installed on the exhaust gas pipe. The powder storage suction device operates based on the concentric jet principle (its structure is the same as existing concentric jet injectors and sampling jet injectors). The working air source is drawn from the primary air, and an automatic control ball valve is installed on the primary air inlet pipe (DN150 pipe) to regulate the introduced primary air volume. This allows for adjustment of the air-to-coal ratio in the powder outlet pipe. The amount of air and powder entering the bypass air-to-coal pipe is adjusted by regulating the opening of the powder storage control valve and the vacuum level of the powder storage suction device. Of course, depending on the specific operating conditions, either the powder storage control valve or the powder storage suction device can be selected.

[0081] Example 9

[0082] A method for peak shaving using a bypass pulverized coal silo attached to the pulverized coal outlet pipe of a coal mill involves installing a bypass pulverized coal silo on the outlet pipe of the coal mill. A pulverized coal separator is installed at the top of the bypass silo. A portion of the air and pulverized coal in the outlet pipe is tangentially introduced into the separator for separation. The resulting pulverized coal falls into the bypass silo, while the generated exhaust gas returns to the outlet pipe through an exhaust gas pipe. Upon receiving a load increase command, the pulverized coal in the bypass silo is fed into the outlet pipe via a pulverizer, and then into the furnace, achieving rapid and precise dynamic matching between the fuel system and the combustion system. The amount of air and pulverized coal entering the bypass pulverized coal silo is regulated by a pulverized coal storage control valve installed inside the outlet pipe.

[0083] Example 10

[0084] Based on Example 9, the following improvements were made: To enhance operational safety, explosion-proof gas, specifically nitrogen, was introduced into the air-powder separator through an explosion-proof gas delivery pipe. To improve the air-powder separation effect, the air and powder in the bypass air-powder pipe entered the air-powder separator tangentially along a circle coaxial with the separator.

[0085] Application Experiment:

[0086] The bypass pulverized coal silo system described in Example 9, combined with the method described in this example, employs a design with an explosion-proof gas delivery pipe, and is equipped with a pulverized coal storage suction device and a pulverized coal storage control valve. To ensure smooth outflow of pulverized coal from the bypass silo and avoid dead zones, the bottom of the bypass silo has a tapering funnel structure. Upon receiving a load reduction command, the control valve on the explosion-proof gas delivery pipe is closed. By adjusting the pulverized coal storage control valve installed at the end of the bypass air-powder pipe and / or opening the pulverized coal storage suction device installed on the exhaust gas pipe, a portion of the air-powder in the outlet pipe enters the air-powder separator tangentially along a circle coaxial with the air-powder separator. When the gravity sensor and / or level sensor indicate that the amount of pulverized coal in the bypass silo has reached a set value, pulverized coal storage is stopped, and the control valve on the explosion-proof gas delivery pipe is reopened. At any time, if the temperature measuring point on the bypass silo indicates an abnormal temperature increase, pulverized coal storage is immediately stopped, and the control valve on the explosion-proof gas delivery pipe is simultaneously opened.

[0087] The above scheme was applied to a 660MW coal-fired generating unit, equipped with six medium-speed coal mills (five in operation and one on standby). A bypass pulverized coal silo system was installed on each of the four pulverized coal outlet pipes of one of the mills (Mill B), with each silo holding no less than 0.5 tons of pulverized coal. Upon receiving a load increase command, the pulverizers immediately started, rapidly adding pulverized coal to the outlet pipes at a rate of 112 kg / min per millimeter. This increased the unit's upward ramp rate from approximately 2% to over 3%, raising the load factor by 10% within three minutes and significantly improving the stability of the new power system.

[0088] The above scheme was applied to a 1000MW coal-fired generating unit, equipped with six medium-speed coal mills (five in operation and one on standby). A bypass pulverized coal silo system was installed on each of the four pulverized coal outlet pipes of two of the mills (Mill B and Mill D), with each silo holding no less than 0.8 tons of pulverized coal. Upon receiving a load increase command, the pulverizers immediately started, rapidly adding pulverized coal to the outlet pipes at a rate of 160 kg / min per millimeter. This increased the unit's upward ramp rate from approximately 2% to over 4%, resulting in a 20% increase in the unit's load rate within five minutes, significantly improving the stability of the new power system.

[0089] The above-described coal mill pulverized coal discharge pipe external bypass pulverized coal bin peak-shaving systems install a bypass pulverized coal bin on the pulverized coal discharge pipe at the coal mill outlet. A portion of the air and pulverized coal in the discharge pipe is tangentially introduced into the air-coal separator at the top of the bypass pulverized coal bin for separation. The resulting pulverized coal falls into the bypass pulverized coal bin, while the generated exhaust gas returns to the discharge pipe through the exhaust gas pipe. Upon receiving a load increase command, the pulverized coal in the bypass pulverized coal bin is fed into the discharge pipe via a pulverizer, and then into the furnace. This achieves rapid and precise dynamic matching between the fuel system and the combustion system, breaking through the bottleneck of rapid and precise dynamic matching between the fuel system and the combustion system in rapid peak-shaving of coal-fired power plant boilers. It is safe and environmentally friendly; moreover, its structure is ingenious, simple, practical, and effective, and it is easy to modify and promote.

Claims

1. A system for peak shaving by connecting a bypass pulverized coal silo to the pulverized coal outlet pipe of a coal mill, characterized in that: The powder discharge pipe installed at the outlet of the coal mill includes at least a bypass powder bin, a bypass air-powder pipe, a powder storage control device, a powder feeder, and a waste gas pipe; the powder storage control device includes a powder storage control valve and / or a powder storage suction device. The side wall of the powder outlet pipe is equipped with a bypass interface, a powder inlet, and a return air inlet; the top of the bypass powder hopper is equipped with an air-powder separator, which has an air-powder inlet and a waste gas outlet. One end of the bypass air-powder pipe is connected to the bypass interface, and the other end is tangentially connected to the air-powder inlet; the powder feeder is equipped with a powder feed inlet and a powder feed outlet, the powder feed inlet is connected to the bottom of the bypass powder silo, and the powder feed outlet is connected to the powder feed port; one end of the exhaust gas pipe is connected to the exhaust gas outlet, and the other end is connected to the return air inlet. When a powder storage control valve is provided, it is located on the bypass interface; when a powder storage suction device is provided, it is located on the exhaust gas pipe; the amount of powder entering the bypass air-powder pipe is adjusted by regulating the opening of the powder storage control valve and / or the vacuum degree of the powder storage suction device.

2. The system of claim 1, wherein: It also includes an explosion-proof gas delivery pipe, one end of which is connected to an explosion-proof gas source and the other end is connected to an air-powder separator; a control valve is installed on the explosion-proof gas delivery pipe.

3. The system of claim 2, wherein: The explosion-proof gas delivery pipe passes through the side wall of the exhaust gas pipe and enters the air-powder separator from the exhaust gas outlet.

4. The system of claim 1-3, wherein the system is characterized in that: The powder storage suction device works based on the concentric jet principle, and its working air source is drawn from the primary air duct.

5. The system of claim 1-3, wherein the system is characterized in that: The air-powder inlet is located on the side wall of the air-powder separator, and the exhaust gas outlet is located at the top center of the air-powder separator; the exhaust gas pipe extends vertically from the exhaust gas outlet into the air-powder separator and exceeds the lowest point of the air-powder inlet.

6. The system of claim 1-3, wherein the system is characterized in that: The air and powder in the bypass air-powder pipe enter the air-powder separator along the tangential direction of a circle coaxial with the air-powder separator.

7. The system of claim 1-3, wherein the system is characterized in that: The powder storage control valve is a plate structure, covering the bypass interface and located inside the powder outlet pipe. One end of the powder storage control valve is a free end, and the other end is a connecting end. The direction from the free end to the connecting end is consistent with the direction of air-powder flow in the powder outlet pipe. The connecting end of the powder storage control valve is hinged to the inner wall of the powder outlet pipe. The rotation angle of the powder storage control valve is adjustable from 0 to 180°. When the powder storage control valve is in the open state, part of the air-powder in the powder outlet pipe enters the bypass air-powder pipe through the turbulence of the powder storage control valve. The amount of air-powder entering the bypass air-powder pipe can be adjusted by adjusting the opening angle of the powder storage control valve.

8. The system of claim 1-3, wherein the system is characterized in that: The bypass interface, powder supply port, and return air port are installed sequentially from upstream to downstream along the powder outlet pipe.

9. The system of claim 1-3, wherein the system is characterized in that: At least the exhaust gas pipe is equipped with a pipe compensator.

10. The system for peak shaving by external bypass pulverized coal bins attached to the pulverized coal outlet pipe of a coal mill according to any one of claims 1-3, characterized in that: The bypass powder hopper is equipped with a gravity sensor and / or a level sensor; the bypass powder hopper is equipped with a temperature measuring point; the bottom of the bypass powder hopper is a tapered funnel structure.

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