Coal-fired mixed biomass feeding system and control method thereof

Abstract

The invention discloses a coal-fired mixed biomass feeding system and a control method thereof, and the coal-fired mixed biomass feeding system comprises a biomass bin used for storing biomass; the raw coal bunker is used for storing raw coal; an inlet of the coal feeder is connected to the biomass bin and the raw coal bin; an inlet of the coal mill is connected with an outlet of the coal feeder, the coal mill is used for grinding biomass and raw coal into a mixed material, and an outlet of the coal mill is connected with the combustor; the fan assembly is used for conveying mixed air into the coal mill so as to drive mixed materials in the coal mill into the combustor; and the CO concentration monitoring device is positioned in the coal mill and is used for detecting the CO concentration in the coal mill. According to the fire coal mixed biomass feeding system, biomass and raw coal are evenly mixed before entering the coal mill, so that the coal mill is not prone to deflagration, and the operation safety of the fire coal mixed biomass feeding system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation, and in particular to a coal-fired mixed biomass feeding system and a control method thereof. Background Art

[0002] It can be seen from the carbon emission quota allocation plan that the country actively encourages coal-fired units to burn biomass.

[0003] Coal-fired power generation primarily relies on a single fuel source, raw coal. Its combustion produces large amounts of pollutants such as carbon dioxide and nitrogen oxides, placing significant pressure on the environment. Biomass, a clean, renewable energy source with carbon neutrality, can effectively reduce pollutant emissions from coal-fired units and optimize the energy mix. However, the fuel supply systems of coal-fired units often rely on a single raw coal delivery system and lack adapters for efficient mixing of biomass and coal. This results in uneven mixing of the two, directly impacting the safety and reliability of pulverizer operation. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a coal-fired mixed biomass feeding system that can achieve uniform mixing of biomass and raw coal before entering the coal mill, making the coal mill less prone to deflagration.

[0005] The present invention also provides a control method for a coal-fired mixed biomass feeding system, and the control method for a coal-fired mixed biomass feeding system includes the above-mentioned coal-fired mixed biomass feeding system.

[0006] According to an embodiment of the present invention, the coal-fired mixed biomass feeding system is used for a coal-fired unit, which includes a burner, a biomass silo, which is used to store biomass; a raw coal silo, which is used to store raw coal; a coal feeder, whose inlet is connected to the biomass silo and the raw coal silo; a pulverizer, whose inlet is connected to the outlet of the coal feeder, and the pulverizer is used to grind the biomass and the raw coal into a mixed material, and whose outlet is connected to the burner; a fan assembly, which is used to convey mixed air into the pulverizer to drive the mixed material in the pulverizer into the burner; and a CO concentration monitoring device, which is located in the pulverizer and is used to detect the CO concentration in the pulverizer.

[0007] According to the coal-biomass mixing feeding system, the biomass bunker is used for storing biomass, the raw coal bunker is used for storing raw coal, the inlet of the coal feeder is connected to the biomass bunker and the raw coal bunker, the inlet of the coal mill is connected to the outlet of the coal feeder, the coal mill is used for grinding the biomass and the raw coal into mixed materials, the outlet of the coal mill is connected to the burner, and the fan assembly is used for conveying mixed air into the coal mill to drive the mixed materials in the coal mill to the burner, so that the raw coal can flow with the biomass when flowing in the coal feeder, the biomass and the raw coal can be uniformly mixed before entering the coal mill, the coal mill is not prone to deflagration, and the safety of the coal-biomass mixing feeding system is improved. Meanwhile, the CO concentration monitoring device arranged in the coal mill is used for detecting the CO concentration in the coal mill, so that the coal-biomass mixing feeding system can adjust the temperature and the air volume of the mixed air conveyed by the fan assembly into the coal mill according to the CO concentration in the coal mill, and the safety of the coal-biomass mixing feeding system is further improved.

[0008] In some embodiments of the present application, the fan assembly comprises a primary fan and an air preheater, the primary fan is communicated with the coal mill through parallel first and second pipelines, the second pipeline is provided with the air preheater, the first pipeline is provided with a first switch door, the second pipeline is provided with a second switch door, the opening degree of the first switch door is adjustable, and the opening degree of the second switch door is adjustable.

[0009] In some embodiments of the present application, the biomass feeding pipe is respectively connected to the biomass bunker and the inlet of the feeder, the outlet of the feeder is connected to the coal feeder, the coal falling pipe is respectively connected to the raw coal bunker and the coal feeder, and is used for conveying the raw coal into the coal feeder, the coal mill is provided with a separator, the separator is used for screening the size of the mixed materials entering the burner, the burner nozzle is provided with a temperature sensor, the temperature sensor is used for detecting the temperature of the burner nozzle, and the biomass bunker is provided with a blocking door, and the opening degree of the blocking door is adjustable.

[0010] According to the control method of the coal-biomass mixing feeding system, the control method of the coal-biomass mixing feeding system comprises the following steps: obtaining the CO concentration in the coal mill; determining that the CO concentration in the coal mill is greater than a preset concentration; reducing the temperature of the mixed air conveyed by the fan assembly into the coal mill; determining that the temperature of the mixed air is less than a minimum temperature of the mixed air, and determining that the CO concentration in the coal mill is greater than the preset concentration; and increasing the air volume of the mixed air conveyed by the fan assembly into the coal mill.

[0011] According to the control method of the coal-fired mixed biomass feeding system according to an embodiment of the present invention, the CO concentration in the coal mill is obtained, it is determined that the CO concentration in the coal mill is greater than a preset concentration, the temperature of the mixed air delivered to the coal mill by the fan assembly is reduced, it is determined that the temperature of the mixed air is less than the minimum temperature of the mixed air, and it is determined that the CO concentration in the coal mill is greater than a preset concentration, and the air volume of the mixed air delivered to the coal mill by the fan assembly is increased, thereby effectively reducing the CO concentration in the coal mill and ensuring the safe and reliable operation of the coal-fired mixed biomass feeding system.

[0012] In some embodiments of the present invention, it also includes: obtaining the temperature at the burner nozzle; determining that the temperature at the burner nozzle is greater than the maximum preset temperature; reducing the temperature of the mixed air delivered by the fan assembly to the coal mill; determining that the temperature of the mixed air is less than the minimum temperature of the mixed air, and determining that the temperature at the burner nozzle is greater than the maximum preset temperature; increasing the air volume of the mixed air delivered by the fan assembly to the coal mill.

[0013] In some embodiments of the present invention, the fan assembly includes a primary fan and an air preheater, the primary fan is connected to the coal mill through a first pipe and a second pipe in parallel, the air preheater is provided in the second pipe, a first switch door is provided on the first pipe, and a second switch door is provided on the second pipe, and reducing the temperature of the mixed air delivered by the fan assembly to the coal mill includes: increasing the opening of the first switch door and reducing the opening of the second switch door.

[0014] In some embodiments of the present invention, the method further includes: obtaining the current of the motor of the coal mill; determining that the current of the motor of the coal mill is greater than the upper limit of the current; and increasing the air volume of the mixed air delivered by the fan assembly to the coal mill.

[0015] In some embodiments of the present invention, a separator is provided in the coal mill, and the control method of the coal-fired mixed biomass feeding system further includes: determining that the air volume of the mixed air is greater than an upper limit of the air volume, and determining that the current of the motor of the coal mill is greater than an upper limit of the current; increasing the rotation speed of the separator or increasing the size of the mixed material screened by the separator into the burner.

[0016] In some embodiments of the present invention, a material blocking door is provided at the outlet of the biomass silo, and the control method of the coal-fired mixed biomass feeding system further includes: determining that the air volume of the mixed air is greater than the air volume upper limit, and determining that the current of the motor of the pulverizer is greater than the current upper limit; reducing the opening of the material blocking door or reducing the conveying speed of the coal feeder.

[0017] In some embodiments of the present invention, before obtaining the CO concentration of the pulverizer, the control method of the coal-fired mixed biomass feeding system further includes: controlling the raw coal in the raw coal bin to be transported to the pulverizer via the coal feeder; and determining that the pulverizer is operating smoothly, controlling the biomass in the biomass silo to be transported to the pulverizer via the coal feeder.

[0018] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0020] Figure 1 is a schematic diagram of a coal-fired mixed biomass feeding system according to an embodiment of the present invention;

[0021] Figure 2 is a flow chart of a control method for a coal-fired mixed biomass feeding system according to an embodiment of the present invention;

[0022] Figure 3 is a flow chart of a control method for a coal-fired mixed biomass feeding system according to another embodiment of the present invention;

[0023] Figure 4 is a flow chart of a control method for a coal-fired mixed biomass feeding system according to yet another embodiment of the present invention.

[0024] Reference numerals:

[0025] 1. Biomass silo; 2. Feeding pipe; 3. Feeder; 4. Raw coal silo; 5. Coal blocking prevention device; 6. Coal drop pipe; 7. Coal feeder; 8. Coal mill; 9. Coal mill outlet pipe; 10. Burner; 11. Temperature sensor; 12. CO concentration monitoring device; 13. Coal mill motor; 14. Material blocking door; 15. Fan assembly. DETAILED DESCRIPTION

[0026] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0027] 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. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, features defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0029] The coal-fired mixed biomass feeding system according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0030] like Figure 1 As shown, the coal-fired mixed biomass feeding system according to an embodiment of the present invention is used for a coal-fired unit, the coal-fired unit includes a burner 10, and the coal-fired mixed biomass feeding system includes a biomass silo 1, a raw coal silo 4, a coal feeder 7, a pulverizer 8, a fan assembly 15 and a CO concentration monitoring device 12.

[0031] Among them, the biomass silo 1 is used to store biomass, the raw coal silo 4 is used to store raw coal, the inlet of the coal feeder 7 is connected to the biomass silo 1 and the raw coal silo 4, the inlet of the pulverizer 8 is connected to the outlet of the coal feeder 7, the pulverizer 8 is used to grind biomass and raw coal into a mixed material, the outlet of the pulverizer 8 is connected to the burner 10, and the fan assembly 15 is used to transport mixed air into the pulverizer 8 to drive the mixed material in the pulverizer 8 to the burner 10.

[0032] It can be understood that the biomass in the biomass silo 1 and the raw coal in the raw coal silo 4 can be transported to the coal feeder 7, and then transported to the pulverizer 8 through the coal feeder 7. The biomass and raw coal are ground into a mixed material by the pulverizer 8, and the mixed material in the pulverizer 8 is driven by the fan assembly 15 to be transported to the burner 10 through the pulverizer outlet pipe 9 for combustion.

[0033] Therefore, the coal-biomass mixing feeding system of the present application can realize that the biomass flows together with the raw coal when the raw coal flows in the coal feeder 7, and can achieve uniform mixing of the biomass and the raw coal before entering the coal mill 8. The coal mill 8 is not prone to deflagration problem through uniform mixing of the raw coal and the biomass, and the safety of the coal-biomass mixing feeding system is improved. When the coal mill 8 grinds the mixture of the biomass and the raw coal, the particle size distribution of the biomass particles and the raw coal particles is more uniform, which is conducive to the temperature of combustion.

[0034] It should be noted that the biomass can include cellulose, hemicellulose, and lignin, etc. The addition of the biomass in the raw coal can realize energy cleaning and low carbonization.

[0035] The CO concentration monitoring device 12 is located in the coal mill 8 and is used to detect the CO concentration in the coal mill 8. It can be understood that the CO in the coal mill 8 is generated due to the pyrolysis or local overheating spontaneous combustion of the coal in the coal mill 8, and the excessive CO concentration in the coal mill 8 can cause explosion and other safety problems.

[0036] Therefore, the CO concentration monitoring device 12 needs to be arranged in the coal mill 8 to detect the CO concentration in the coal mill 8 in real time, and when it is determined that the CO concentration in the coal mill 8 is greater than the preset concentration, the temperature of the mixed air delivered into the coal mill 8 by the fan assembly 15 is reduced to reduce the CO concentration deflagration in the coal mill 8. When it is determined that the temperature of the mixed air is less than the minimum temperature of the mixed air, and the CO concentration in the coal mill 8 is still greater than the preset concentration, the air volume of the mixed air delivered into the coal mill 8 by the fan assembly 15 is increased to further reduce the CO concentration in the coal mill 8, thereby ensuring the safety of the coal-biomass mixing feeding system.

[0037] Specifically, the raw coal can be delivered into the raw coal bin 4 by the coal conveying belt to fill the raw coal bin 4. When the raw coal bin 4 or the biomass bin 1 is blocked, the anti-blocking device 5 can be used to dredge to keep the biomass and the raw coal falling smoothly. For example, the anti-blocking device 5 can include an air cannon or other rapping device arranged on the outer peripheral wall of the raw coal bin 4.

[0038] According to the coal-fired mixed biomass feeding system of an embodiment of the present invention, the biomass silo 1 is used to store biomass, the raw coal silo 4 is used to store raw coal, the inlet of the coal feeder 7 is connected to the biomass silo 1 and the raw coal silo 4, the inlet of the pulverizer 8 is connected to the outlet of the coal feeder 7, the pulverizer 8 is used to grind the biomass and raw coal into a mixed material, the outlet of the pulverizer 8 is connected to the burner 10, and the fan assembly 15 is used to convey the mixed air into the pulverizer 8 to drive the mixed material in the pulverizer 8 to the burner 10, so that the raw coal can entrain the biomass when flowing in the coal feeder 7, so that the biomass and raw coal can be evenly mixed before entering the pulverizer 8, so that the pulverizer 8 is not prone to explosion problems, thereby improving the safety of the operation of the coal-fired mixed biomass feeding system. At the same time, the CO concentration in the coal mill 8 is detected by the CO concentration monitoring device 12 provided in the coal mill 8, so that the coal-fired mixed biomass feeding system can adjust the temperature and air volume of the mixed air delivered to the coal mill 8 by the fan assembly 15 according to the CO concentration in the coal mill 8, thereby further ensuring the safety of the operation of the coal-fired mixed biomass feeding system.

[0039] In some embodiments of the present invention, Figure 1 As shown, the fan assembly 15 includes a primary fan and an air preheater. The primary fan is connected to the pulverizer 8 through a first pipe and a second pipe in parallel. The air preheater is provided in the second pipe. A first switch door is provided on the first pipe, and a second switch door is provided on the second pipe. The opening of the first switch door is adjustable, and the opening of the second switch door is adjustable.

[0040] It is understood that the primary air fan is used to convey cold air into the first and second ducts. An air preheater is provided in the second duct to heat the cold air in the second duct into hot air, and then convey a mixed air of hot air and cold air into the coal mill 8. The hot air and cold air are mixed and used to drive the mixed material to the burner 10. By mixing the cold air with the hot air, the cold air can be used to adjust the temperature of the hot air to prevent the hot air from being too hot.

[0041] For example, the temperature of cold air is about 25°C, the temperature of hot air is about 315°C, the temperature of the mixed air is 290°C, and the loading force is increased to 8.2 MPa.

[0042] A first switch door is provided on the first pipeline, and a second switch door is provided on the second pipeline. The opening of the first switch door is adjustable, and the opening of the second switch door is adjustable. Thus, the adjustable opening of the first switch door can adjust the volume of cold air delivered to the coal mill 8 from the first pipeline, and the adjustable opening of the second switch door can adjust the volume of hot air delivered to the coal mill 8 from the second pipeline, thereby adjusting the temperature of the mixed air delivered to the coal mill 8 as needed.

[0043] Specifically, by increasing the opening of the first switch door and decreasing the opening of the second switch door, the temperature of the mixed air delivered by the fan assembly 15 to the coal mill 8 can be reduced, thereby reducing the CO concentration within the coal mill 8. At the same time, when the temperature of the mixed air is lower than the minimum mixed air temperature and the CO concentration within the coal mill 8 is still higher than the preset concentration, the speed of the primary fan can be increased to increase the volume of the mixed air delivered by the fan assembly 15 to the coal mill 8.

[0044] In some embodiments of the present invention, Figure 1 As shown, the coal-fired mixed biomass feeding system also includes a biomass discharge pipe 2 and a feeder 3. The biomass discharge pipe 2 is connected to the inlet of the biomass silo 1 and the feeder 3, respectively, and the outlet of the feeder 3 is connected to the coal feeder 7. Thus, the biomass in the biomass silo 1 is transported to the feeder 3 through the discharge pipe 2, and then transported to the coal feeder 7 through the feeder 3, thus realizing the biomass transportation from the biomass silo 1 to the coal feeder 7.

[0045] In some embodiments of the present invention, Figure 1 As shown, the coal-fired mixed biomass feeding system further includes a coal drop pipe 6, which is connected to the raw coal bin 4 and the coal feeder 7, respectively, for conveying raw coal into the coal feeder 7. Thus, the raw coal in the raw coal bin 4 is conveyed to the coal feeder 7 through the coal drop pipe 6, thereby conveying raw coal from the raw coal bin 4 to the coal feeder 7.

[0046] In some embodiments of the present invention, Figure 1 As shown, the coal mill 8 includes a separator for screening the size of the mixture entering the burner 10. It will be appreciated that the coal mill 8 grinds the biomass and raw coal into a mixture. After the mixture is screened by the separator, the mixture that meets the separator's size requirements is conveyed to the burner 10 for combustion, while the mixture that does not meet the separator's size requirements continues to be ground. Thus, the separator ensures the size of the mixture entering the burner 10, thereby ensuring the combustion efficiency of the burner 10.

[0047] In some embodiments of the present invention, Figure 1 As shown, the nozzle of the burner 10 is provided with a temperature sensor 11, which is used to detect the temperature at the nozzle of the burner 10. Thus, by detecting the temperature at the nozzle of the burner 10 in real time through the temperature sensor 11, the combustion state of the burner 10 can be detected, the safety and efficiency of the burner 10 can be ensured, and equipment damage, safety hazards, efficiency reduction, or emission problems caused by excessive temperature can be avoided.

[0048] In some embodiments of the present invention, Figure 1As shown, the outlet of the biomass silo 1 is provided with a blocking door 14, and the opening of the blocking door 14 is adjustable. Thus, by adjusting the opening of the blocking door 14, the delivery speed and amount of biomass delivered from the biomass silo 1 to the coal feeder 7 can be controlled, ensuring the reliable operation of the coal-fired mixed biomass feeding system.

[0049] The following describes a control method for a coal-fired mixed biomass feeding system according to an embodiment of the present invention.

[0050] like Figure 1 and Figure 2 As shown, the control method of the coal-fired mixed biomass feeding system according to an embodiment of the present invention includes the coal-fired mixed biomass feeding system, and the control method of the coal-fired mixed biomass feeding system includes:

[0051] Obtaining the CO concentration within the coal mill 8. It is understood that CO is generated within the coal mill 8 due to pyrolysis or local overheating and spontaneous combustion of coal within the coal mill 8. Excessive CO concentration within the coal mill 8 can cause safety issues such as explosions. Therefore, it is first necessary to obtain the CO concentration within the coal mill 8. Specifically, the CO concentration within the coal mill 8 can be obtained in real time using a CO concentration monitoring device 12 disposed within the coal mill 8.

[0052] Determine whether the CO concentration in the coal mill 8 is greater than a preset concentration. Based on previous data or experiments, the CO concentration in the coal mill 8 has a preset concentration, which is the upper limit of the CO concentration in the coal mill 8. If it is determined that the CO concentration in the coal mill 8 obtained in the above steps is greater than the preset concentration, subsequent operations are required to reduce the CO concentration in the coal mill 8.

[0053] Lowering the temperature of the mixed air delivered by the fan assembly 15 to the coal mill 8. Thus, by lowering the temperature of the mixed air delivered by the fan assembly 15 to the coal mill 8, the rate of temperature rise of the pulverized coal is slowed, the pyrolysis reaction is suppressed, and the release of CO from the volatile matter is reduced. Furthermore, the internal temperature of the coal mill 8 can be maintained within a safe range, preventing the generation of CO due to high-temperature decomposition or spontaneous combustion of the pulverized coal, thereby effectively reducing the CO concentration in the coal mill 8.

[0054] It is determined that the temperature of the mixed air is less than the minimum temperature of the mixed air, and that the CO concentration in the coal mill 8 is greater than a preset concentration. It is understood that if the CO concentration in the coal mill 8 is still greater than the preset concentration after the temperature of the mixed air delivered to the coal mill 8 by the fan assembly 15 is reduced to less than the minimum temperature of the mixed air, further action is required to reduce the CO concentration in the coal mill 8.

[0055] Increase the air volume of the mixed air delivered by the fan assembly 15 into the coal mill 8. It can be understood that the fan assembly 15 drives the mixed material in the coal mill 8 to the burner 10 for combustion, and by increasing the air volume of the mixed air delivered by the fan assembly 15 into the coal mill 8, the mixed material in the coal mill 8 can be delivered to the burner 10 more quickly, and increasing the air volume of the mixed air delivered by the fan assembly 15 into the coal mill 8 can increase the oxygen content in the coal mill 8 and dilute the CO concentration in the coal mill 8, thereby effectively reducing the CO concentration in the coal mill 8 and ensuring safe and reliable operation of the coal-biomass mixed feeding system.

[0056] According to the control method of the coal-biomass mixed feeding system, the CO concentration in the coal mill 8 is obtained, and it is determined that the CO concentration in the coal mill 8 is greater than the preset concentration. The temperature of the mixed air delivered by the fan assembly 15 into the coal mill 8 is reduced, and it is determined that the temperature of the mixed air is less than the minimum temperature of the mixed air, and it is determined that the CO concentration in the coal mill 8 is greater than the preset concentration. The air volume of the mixed air delivered by the fan assembly 15 into the coal mill 8 is increased, thereby effectively reducing the CO concentration in the coal mill 8 and ensuring safe and reliable operation of the coal-biomass mixed feeding system.

[0057] In some embodiments of the present application, as shown in Figure 1 and Figure 3 The control method of the coal-biomass mixed feeding system further comprises:

[0058] Obtain the temperature at the burner 10 nozzle. It can be understood that the temperature at the burner 10 nozzle can detect the combustion state of the burner 10, ensure the safety and efficiency of the burner 10, and avoid equipment damage, safety hazards, efficiency decline or emission problems caused by excessively high temperature. Specifically, the temperature at the burner 10 nozzle can be detected in real time by the temperature sensor 11 arranged at the burner 10 nozzle.

[0059] Determine that the temperature at the burner 10 nozzle is greater than the highest preset temperature. According to previous data or experiments, the temperature at the burner 10 nozzle has a highest preset temperature, which is the upper limit value of the temperature at the burner 10 nozzle. When it is determined that the temperature at the burner 10 nozzle obtained in the above step is greater than the highest preset temperature, subsequent operation needs to be taken to reduce the temperature at the burner 10 nozzle.

[0060] Reduce the temperature of the mixed air delivered by the fan assembly 15 into the coal mill 8. It can be understood that the fan assembly 15 drives the mixed material in the coal mill 8 to the burner 10, and by reducing the temperature of the mixed air delivered by the fan assembly 15 into the coal mill 8, the ignition time of the mixed material can be effectively reduced, and the ignition is delayed to reduce the temperature at the burner 10 nozzle, thereby reducing the temperature at the burner 10 nozzle greater than the highest preset temperature.

[0061] It is determined that the temperature of the mixed air is less than the minimum mixed air temperature, and that the temperature at the nozzle of the burner 10 is greater than the maximum preset temperature. It is understood that when the temperature of the mixed air delivered by the fan assembly 15 to the coal mill 8 is reduced to less than the minimum mixed air temperature, if the temperature at the nozzle of the burner 10 is still greater than the maximum preset temperature, further action is required to reduce the CO concentration in the coal mill 8.

[0062] Increase the volume of mixed air delivered by the fan assembly 15 to the coal mill 8. Thus, by increasing the volume of mixed air delivered by the fan assembly 15 to the coal mill 8, the volume and velocity of the mixed air entering the burner 10 are increased, thereby further reducing the temperature at the burner nozzle, ensuring safe and reliable operation of the coal-biomass mixed feeding system.

[0063] In some embodiments of the present invention, Figure 1 As shown, the fan assembly 15 includes a primary fan and an air preheater. The primary fan is connected to the coal mill 8 through a first pipe and a second pipe in parallel. The air preheater is provided in the second pipe. A first switch door is provided on the first pipe, and a second switch door is provided on the second pipe. Lowering the temperature of the mixed air delivered by the fan assembly 15 to the coal mill 8 includes increasing the opening of the first switch door and reducing the opening of the second switch door.

[0064] It can be understood that the primary fan is used to transport cold air toward the first pipe and the second pipe. An air preheater is provided in the second pipe to heat the cold air in the second pipe into hot air, so as to transport the mixed air formed by the hot air and the cold air toward the coal mill 8. By increasing the opening of the first switch door and reducing the opening of the second switch door, the temperature of the mixed air transported by the fan assembly 15 to the coal mill 8 can be reduced.

[0065] At the same time, the air volume and wind speed of the mixed air delivered by the fan assembly 15 to the coal mill 8 can also be increased by increasing the speed of the primary fan.

[0066] In some embodiments of the present invention, Figure 1 and Figure 4 As shown, the control method of the coal-fired mixed biomass feeding system is characterized by further comprising:

[0067] Obtain the current of the coal mill motor 13. It is understood that the current of the coal mill motor 13 is a direct indicator of the motor load. If the current is too high, it may mean that the motor is overloaded. Long-term overload will damage the motor and even cause a malfunction. Therefore, it is necessary to determine whether the coal mill 8 is in normal working condition based on the current value.

[0068] Determine that the current of the coal mill motor 13 is greater than the current upper limit. Based on previous data or experiments, it is determined that the current of the coal mill motor 13 has a current upper limit. When it is determined that the current of the coal mill motor 13 is greater than the current upper limit, subsequent operations are required to reduce the temperature at the burner 10 nozzle.

[0069] Increasing the volume of the mixed air delivered by the fan assembly 15 to the coal mill 8. It is understood that increasing the volume of the mixed air delivered by the fan assembly 15 to the coal mill 8 can reduce the bulk density of the mixture formed by the raw coal and biomass inside the coal mill 8, reduce mechanical resistance, thereby reducing motor load, and optimize the conveying efficiency of the mixed material, avoiding deposition or blockage caused by insufficient air volume, thereby ensuring the normal and stable operation of the coal mill 8.

[0070] In some embodiments of the present invention, Figure 1 and Figure 4 As shown, the coal mill 8 is provided with a separator. After the mixed material is screened by the separator, the mixed material that meets the size requirements of the separator is transported to the burner 10 for combustion, while the mixed material that does not meet the size requirements of the separator continues to be ground. Thus, the size of the mixed material entering the burner 10 can be guaranteed by the separator, thereby ensuring the combustion efficiency of the burner 10.

[0071] The control method for the coal-fired mixed biomass feeding system further includes determining that the mixed air volume is greater than an upper limit, and determining that the current of the coal mill motor 13 is greater than an upper limit. It is understood that when the mixed air volume delivered by the fan assembly 15 to the coal mill 8 is increased to the upper limit, the current of the coal mill motor 13 is greater than the upper limit, and further operation is required to reduce the current of the coal mill motor 13.

[0072] Increase the separator's rotation speed or increase the size of the mixed material that the separator screens before entering the burner 10 .

[0073] Thus, by increasing the speed of the separator, the mixed material that meets the size requirements can be discharged more quickly and sent to the burner 10, while the mixed material that does not meet the standards can be more efficiently returned to the coal mill 8 for re-grinding. The efficient separation of the separator reduces the ineffective circulation of coarse particles in the coal mill 8, reduces the material packing density inside the coal mill 8, thereby reducing mechanical resistance and thus reducing the current of the coal mill motor. Alternatively, by increasing the size of the mixed material screened by the separator before entering the burner 10, the number of circulations of the mixed material can be reduced, thereby reducing mechanical resistance and thus reducing the current of the coal mill motor.

[0074] In some embodiments of the present invention, Figure 1 and Figure 4As shown, a material blocking door 14 is provided at the outlet of the biomass silo 1. The control method of the coal-fired mixed biomass feeding system further includes determining that the air volume of the mixed air is greater than an upper air volume limit, and determining that the current of the coal mill motor 13 is greater than an upper current limit. It is understood that when the air volume of the mixed air delivered by the fan assembly 15 to the coal mill 8 is increased to the upper air volume limit, the current of the coal mill motor 13 is greater than the upper current limit, and further operation is required to reduce the current of the coal mill motor 13.

[0075] Reduce the opening of the material-blocking door 14 or reduce the conveying speed of the coal feeder 7. It is understandable that, since the hardness of biomass is greater than that of raw coal, biomass circulates more times in the coal mill 8 and the separator than raw coal. Therefore, by reducing the opening of the material-blocking door 14, the conveying speed and quantity of biomass conveyed from the biomass silo 1 to the coal feeder 7 can be reduced, thereby reducing the quantity of biomass conveyed by the coal feeder 7 to the coal mill 8, thereby reducing the mechanical resistance and reducing the current of the coal mill's motor. Alternatively, by reducing the conveying speed of the coal feeder 7, the quantity of biomass and raw coal conveyed by the coal feeder 7 to the coal mill 8 can be reduced, thereby reducing the mechanical resistance and reducing the current of the coal mill's motor.

[0076] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, before obtaining the CO concentration of the coal mill 8 , the control method for the coal-fired mixed biomass feeding system further includes controlling the raw coal in the raw coal bin 4 to be transported to the coal mill 8 via the coal feeder 7 .

[0077] It is understandable that because biomass contains a lot of impurities or fibers and is relatively hard, it is not easy to grind. Therefore, before the coal mill 8 grinds the biomass, it is possible to stabilize the coal mill 8 before grinding the biomass, thereby improving the reliability of the coal mill 8. Specifically, before the biomass silo 1 conveys the biomass to the coal feeder 7, the raw coal in the raw coal silo 4 is first controlled to be conveyed to the coal mill 8 via the coal feeder 7, so that the coal mill 8 only grinds the raw coal.

[0078] To ensure that the coal mill 8 is operating smoothly, the biomass in the biomass silo 1 is controlled to be transported to the coal mill 8 via the coal feeder 7. It is understood that the smooth operation of the coal mill 8 can be determined by the current of the coal mill motor 13 being in a stable state, the differential pressure between the inlet and outlet of the coal mill 8 being stable, and the vibration of the coal mill 8 being reduced. Therefore, after ensuring that the coal mill 8 is operating smoothly, the biomass in the biomass silo 1 is controlled to be transported to the coal mill 8 via the coal feeder 7, so that the raw coal and biomass are transported to the coal mill 8 by the coal feeder 7 and ground to form a mixed material.

[0079] In some embodiments, the coal-fired mixed biomass feeding system also includes a control system, which is communicated with a CO detection device provided in the coal mill 8, a temperature detection device at the nozzle of the burner 10, and the motor 13 of the coal mill, so as to obtain the CO concentration in the coal mill 8, the temperature at the nozzle of the burner 10, and the current of the motor 13 of the coal mill in real time, and according to the instructions of the control system, controls are performed to reduce the temperature of the mixed air delivered by the fan assembly 15 to the coal mill 8, increase the air volume of the mixed air delivered by the fan assembly 15 to the coal mill 8, increase the opening of the first switch door, reduce the opening of the second switch door, or reduce the opening of the material blocking door 14, or reduce the conveying speed of the coal feeder 7, so as to ensure reliable and stable operation of the coal-fired mixed biomass feeding system.

[0080] In a specific embodiment of the present application, taking the direct co-firing of biomass in a domestic 600MW supercritical unit boiler as an example, the boiler is a supercritical parameter transformer-operated direct current coal-fired boiler produced by Harbin Boiler Plant Co., Ltd. using technology introduced from Mitsui Babcock Energy Limited of the United Kingdom. The boiler model is HG-1913 / 25.4-YM7, which adopts a П-type layout, spiral water-cooled walls, a single furnace, front and rear wall counter-combustion mode, one-time intermediate reheating, balanced ventilation, open-air layout, solid slag discharge, and an all-steel frame fully suspended structure.

[0081] The boiler's front and rear walls were originally equipped with three layers of Mitsui Babcock low-NOx axial swirl burners (10), five per layer, for a total of 30. A layer of OFA burners (10) was also installed on each of the front and rear walls, five per layer, for a total of 10. The pulverizing system was a positive pressure, direct-fired system equipped with six HP-1003 medium-speed pulverizers (8). Five pulverizers (8) were sufficient to meet the boiler's MCR load.

[0082] The first step is to start the coal conveyor belt to fill the raw coal bin 4 with raw coal, and at the same time start the coal feeder 7 to feed a small amount of raw coal into the coal mill 8 for grinding.

[0083] Step 2: Start the coal mill 8 and the primary air blower, so that the cold air in the first duct and the hot air in the second duct mix and enter the coal mill 8. The cold air temperature is approximately 25°C, the hot air temperature is approximately 315°C, and the mixed air temperature is 290°C. The loading pressure is increased to 8.2 MPa. The raw coal is ground into pulverized coal and enters the burner 10 located in the furnace for combustion. The output of the coal mill 8 is 50 t / h. The primary air volume entering the coal mill 8 is 97 t / h. The differential pressure between the inlet and outlet of the coal mill 8 is 2.9 kPa, the coal fineness R90 is 19%, and the air and pulverized coal temperature at the outlet of the coal mill 8 is 77°C. The coal mill 8 is operating at a safe level.

[0084] Third step: after the stable operation of the coal mill 8, the biomass material is put into the bunker in advance, the baffle door of the biomass bunker and the feeder 3 are opened in turn, so that the biomass in the biomass bunker 1 is conveyed to the coal feeder 7 through the feeder 3. The biomass and the raw coal are mixed and flow downward into the coal mill 8. The biomass feeding amount is 8 t / h.

[0085] Fourth step: after a period of operation, the CO detection device inside the coal mill 8 detects that the CO concentration reaches 250 ppm, the system automatically issues a high concentration prompt, the risk of deflagration of the mixed biomass and raw coal in the coal mill 8 is prompted, the opening degrees of the first baffle and the second baffle are adjusted to reduce the temperature of the mixed air and increase the air volume of the coal mill 8. The air volume of the coal mill 8 is increased to 110 t / h, and after a period of operation, the CO concentration inside the coal mill 8 is reduced to 60 ppm, which ensures the safety of the operation of the coal mill 8.

[0086] Fifth step: when the combustion nozzle temperature field monitoring system issues a high temperature prompt within 0.5 meters of the burner 10 nozzle, the temperature reaches 700℃, the system issues a risk of burning the burner 10 in advance. Adjust the opening degrees of the first baffle and the second baffle to reduce the temperature of the mixed air and increase the air volume of the coal mill 8, control the temperature of the air and powder at the outlet of the coal mill 8, increase the air volume of the coal mill 8 to 115 t / h, and control the temperature of the air and powder at the outlet of the coal mill 8 to 70℃.

[0087] Sixth step: when the motor current of the coal mill 8 reaches 70A, the system issues a high risk of coal mill 8 blockage prompt, first adjust the opening degrees of the first baffle and the second baffle of the coal mill 8 to reduce the temperature of the mixed air and increase the air volume of the coal mill 8, increase the air volume of the coal mill 8 to 125 t / h, reduce the speed of the separator to 600 rpm, and reduce the current of the coal mill 8 to about 45A, and operate at a safe level. If the pressure difference is not improved by adjusting the air volume and the speed of the separator, the biomass material feeding amount is adjusted at this time, and the biomass material feeding amount is reduced to 5 t / h.

[0088] Seventh step: when the raw coal bunker 4 is blocked, the air cannon or other vibration devices are started to keep the coal falling smooth.

[0089] It should be noted that the coal-fired boiler coal type and biomass blending parameters are shown in Table 1.

[0090] Table 1 Coal-fired boiler coal type and biomass blending parameters

[0091]

[0092] The coal-fired biomass feeding system and the operation according to the embodiments of the present application are known to those skilled in the art, and will not be described in detail here.

[0093] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0094] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A coal-fired mixed biomass feeding system, characterized in that: Used for a coal-fired unit, the coal-fired unit includes a burner, and the coal-fired mixed biomass feeding system includes: A biomass silo, wherein the biomass silo is used to store biomass; A raw coal bunker, which is used to store raw coal; a coal feeder, wherein the inlet of the coal feeder is connected to the biomass silo and the raw coal silo; a coal mill, wherein the inlet of the coal mill is connected to the outlet of the coal feeder, the coal mill is used to grind the biomass and the raw coal into a mixed material, and the outlet of the coal mill is connected to the burner; a fan assembly, the fan assembly being used to deliver mixed air into the coal mill to drive the mixed material in the coal mill into the burner; A CO concentration monitoring device is located in the coal mill and is used to detect the CO concentration in the coal mill.

2. The coal-fired mixed biomass feeding system according to claim 1, characterized in that: The fan assembly includes a primary fan and an air preheater. The primary fan is connected to the coal mill through a first pipe and a second pipe connected in parallel. The air preheater is installed in the second pipe. A first switch door is provided on the first pipe, and a second switch door is provided on the second pipe. The opening of the first switch door is adjustable, and the opening of the second switch door is adjustable.

3. The coal-fired mixed biomass feeding system according to claim 1, characterized in that: Also includes: A biomass feeding pipe and a feeder, wherein the biomass feeding pipe is connected to the biomass silo and the inlet of the feeder respectively, and the outlet of the feeder is connected to the coal feeder; and / or, a coal drop pipe, the coal drop pipe being connected to the raw coal bin and the coal feeder, respectively, for conveying the raw coal into the coal feeder; And / or, the coal mill is provided with a separator, the separator being used to screen the size of the mixed material entering the burner; And / or, the burner nozzle has a temperature sensor, and the temperature sensor is used to detect the temperature at the burner nozzle; And / or, the biomass silo has a material blocking door at its outlet, and the opening of the material blocking door is adjustable.

4. A control method for a coal-fired mixed biomass feeding system, characterized in that: The coal-fired mixed biomass feeding system according to any one of claims 1 to 3, wherein the control method of the coal-fired mixed biomass feeding system comprises: Obtaining the CO concentration in the coal mill; Determining that the CO concentration in the coal mill is greater than a preset concentration; reducing the temperature of the mixed air delivered by the fan assembly to the coal mill; Determining that the temperature of the mixed air is lower than a minimum temperature of the mixed air, and determining that the CO concentration in the coal mill is higher than a preset concentration; Increase the volume of the mixed air delivered by the fan assembly to the coal mill.

5. The control method of the coal-fired mixed biomass feeding system according to claim 4, characterized in that: Also includes: Obtaining the temperature at the burner nozzle; Determining that the temperature at the burner nozzle is greater than a maximum preset temperature; reducing the temperature of the mixed air delivered by the fan assembly to the coal mill; Determining that the temperature of the mixed air is lower than a minimum temperature of the mixed air, and determining that the temperature at the burner nozzle is higher than a maximum preset temperature; Increase the volume of the mixed air delivered by the fan assembly to the coal mill.

6. The control method of the coal-fired mixed biomass feeding system according to claim 4 or 5, characterized in that: The fan assembly includes a primary fan and an air preheater. The primary fan is connected to the coal mill through a first pipe and a second pipe connected in parallel. The air preheater is installed in the second pipe. A first switch door is provided on the first pipe, and a second switch door is provided on the second pipe. Reducing the temperature of the mixed air delivered by the fan assembly to the coal mill includes: Increase the opening of the first opening door and decrease the opening of the second opening door.

7. The control method of the coal-fired mixed biomass feeding system according to claim 4, characterized in that: Also includes: obtaining the current of the motor of the coal mill; Determining that the current of the motor of the coal mill is greater than an upper current limit; Increase the volume of the mixed air delivered by the fan assembly to the coal mill.

8. The control method of the coal-fired mixed biomass feeding system according to claim 7, characterized in that: The coal mill is provided with a separator, and the control method of the coal-fired mixed biomass feeding system further comprises: Determining that the air volume of the mixed air is greater than an air volume upper limit, and determining that the current of the motor of the coal mill is greater than an upper limit; Increase the rotation speed of the separator or increase the size of the mixed material that the separator screens to enter the burner.

9. The control method of the coal-fired mixed biomass feeding system according to claim 7, characterized in that: The biomass silo has a material blocking door at its outlet, and the control method of the coal-fired mixed biomass feeding system further includes: Determining that the air volume of the mixed air is greater than an air volume upper limit, and determining that the current of the motor of the coal mill is greater than an upper limit; Reduce the opening of the material blocking door or reduce the conveying speed of the coal feeder.

10. The control method of the coal-fired mixed biomass feeding system according to claim 4, characterized in that: Before obtaining the CO concentration of the coal mill, the control method of the coal-fired mixed biomass feeding system further includes: Controlling the raw coal in the raw coal bunker to be transported to the coal mill via the coal feeder; The coal mill is ensured to operate smoothly, and the biomass in the biomass silo is controlled to be transported to the coal mill via the coal feeder.

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